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Full Spectrum LED Grow Lights: The Truth You Need to Know

Descripción: Full Spectrum LED Grow Lights: The Truth You Need to Know Many LED lighting suppliers will say that full-spectrum LED grow lights are the best option for growing plants because they mimic the natural light from the sun. The argument goes: "Plants have grown under sunlight for millions of years. Why would we want to change what mother nature knows is best?" Well, we want to let you know that there is no such thing as a full-spectrum LED grow light. There, we said it. But before we get a flood of messages from concerned growers wondering what all the confusion is about, let's first uncover what full spectrum means. Then we'll let you in on the truth about full-spectrum LED grow lights so you can make the best grow light choice for your facility. What is a Full-Spectrum LED Grow Light? A full-spectrum LED grow light is simply a marketing term that implies that your grow light closely resembles light from the sun. This marketing term comes from the concept of "full-spectrum light," which in recent years has been used to refer to electromagnetic radiation from the UV to infrared wavebands. The History of the Full-Spectrum LED Grow Light The full-spectrum commercial LED grow light is the newest evolution of an already confusing term. Originally, full-spectrum light described the only real full-spectrum light source, the sun. Over time, the term began to take on other characteristics of sunlight. The commercial lighting industry began using the name "full-spectrum" to sell lights that produced a Color Rendering Index (CRI) over 90. Humans perceive colors more accurately under light sources with a CRI over 90, much like how we see colors in our natural world under daylight. This was a beneficial feature for human environments such as offices, outdoor spaces, and others. With the advent of horticultural lighting, companies once again began to borrow the term. Only this time, they claimed that full-spectrum LEDs could reproduce the effects of sunlight for plants. Thus, the full-spectrum LED grow light was born. Unfortunately, lighting for plants is not quite that simple. Problems with Full-Spectrum LED Grow Lights There are many issues with the concept of full-spectrum LED grow lights. For starters, just because you name something, doesn't make it true. This rhetoric may have made sense for lighting designers interested in selling lights so humans could see, but plants require light to feed, grow, and live. There are three major problems when talking about full-spectrum grow lights: Full-Spectrum Grow Lights Aren't Optimized for Plants Full-Spectrum Grow Lights Don't Include the Full Solar Spectrum Full-Spectrum Grow Lights Are Not Dynamic Like the Sun We'll briefly look at these problems with full-spectrum grow lights one-by-one, so you can understand how deep the roots of this problem run: 1. Full-Spectrum Grow Lights Aren't Optimized for Plants A major problem with many full spectrum vertical grow light is that they are designed to give the appearance of daylight without being custom-tailored for rigorous plant growth. It's the reason why we at LumiGrow coined the phrase, "PAR is for plants and Lumens are for humans." Not all wavelengths of light are optimal for photosynthesis. Plants photosynthesize electromagnetic radiation in the 400 to 700 nanometer range, known as Photosynthetically Active Radiation or PAR. So, plants don't care how bright your light fixture appears to you. Still, most full-spectrum lighting companies build fixtures with this visual appeal in mind. When you hear that the diodes in your full spectrum grow light are 3,000k to 4,500k, or 5,000k+, this degree of Kelvin (K) refers to how "cool" or "warm" your light is in appearance. Our understanding of plant photobiology has come a long way. We understand much more about plants than to be using human lighting metrics to design our grow lights. Our goal as growers is to improve the lighting characteristics most important for plant growth. This means not only getting enough PAR light, but also the right mix of light spectra, which brings us to problem #2. The thinking behind many full spectrum LED grow lights on the market is that by creating a spectral distribution similar to sunlight, your plants will grow well. A decent theory, except that full spectrum grow lights are not actually similar to the sun. We can see below that the sun's radiation includes much more than the visible or PAR wavebands. Sunlight itself is complex, and many scientists are still working to understand it today. You can see that sunlight also contains ultraviolet (UV) and infrared light (as well as x-rays, radio waves, and others, but we'll leave those alone for now). Although PAR is the most important light for photosynthesis, plants still respond to radiation outside of the PAR spectrum. For instance, UV light elicits protective compounds in plants similar to the way humans become tanned in the presence of UV. Plants also use a type of infrared light called "far-red light" to induce a shade avoidance response, causing them to stretch and can induce early flowering. To create a light source that elicits plant response the same way the sun does would be too costly and downright impossible given current grow light technology. Nor would you want to create such a grow light, which takes us to problem #3. 3. Full-Spectrum Grow Lights Are Not Dynamic Like the Sun Not only would it be too costly to create an actual full spectrum quantum board grow light, but if such a thing even existed, its performance would still not accurately reflect what's happening in nature. The sun's spectrum is in constant flux due to changes in weather or its position in the sky relative to earth. In the graphic above, you can see how sunlight spectra change throughout the day or in different weather conditions. Because of this phenomenon, it's best to think about the interaction between sunlight and plants as a continually changing process. If you hang your full spectrum grow lights in a greenhouse, you will still reap the benefits (and disadvantages) of this natural process from the sun. But if you take those same full-spectrum lights and hang them indoors, they will not behave like the sun. Photomorphogenic responses by plants are co-regulated, which means that certain expressions of the plant may turn on or off based on the amount of light within one waveband relative to another. Photosynthesis depends upon the absorption of light by photoreceptors and pigments in the leaves of plants. The most well-known of these pigments is chlorophyll-a, but there are many accessory pigments that also contribute to photosynthesis. The relative light absorption of chlorophyll pigments as shown in the graph to the right is one of the reasons why red light has become popular among LED grow lights. Not all PAR light contributes to photosynthesis equally, though we now understand that other wavebands of light such as green, do play an important role in this process. Since photoreceptors in plants also have their own ranges for light absorption, they co-regulate processes that create plants' form and structure depending on the spectral mix they receive. For instance, higher ratios of blue light can induce more robust root growth, more favorable plant biochemistry, and a hardier structure. But these effects may not be as pronounced when more red light is introduced. Thus, the ever-changing spectrum of the sun is constantly signaling to plants to change their form and structure based on the natural conditions of the environment. But before you rush and begin moving your grow room outdoors, let's consider why plants don't need the full spectrum of sunlight. For starters, plants don't need UV or infrared light to live. Also, in a controlled environment, plants are given ideal conditions to grow in and often don't need to compete with other species to live. Plants only require light in the 400 to 700-nanometer range to photosynthesize. So, you'll want to choose a grow light that produces your desired results, most often higher yields and better quality for your plants. What is the Best Light Spectrum for Plant Growth? By now you must be wondering: "If I can't mimic sunlight, then what light spectrum should I use?". The answer is both simple and quite complex. Plants only require PAR light for photosynthesis. So, if your grow light is optimized within the PAR spectrum, you're going to get the most bang for your buck when it comes to minimizing electrical costs while maximizing plant health. Beyond PAR, it's important to choose a light spectrum that's: best for the environment you're growing in (greenhouse or indoors) tailored to your plant's growth phase (propagation, vegetative, flowering, or finishing) or specific to the cultivar being grown Full Spectrum LED Grow Lights vs. Other Grow Light Options It should be clear by now that there are no real standards around full samsung lm301b grow light. Full-spectrum is simply a term used to sell you a simple idea. Although you cannot mimic sunlight, you can use light spectrum to your advantage. Luckily, there are many grow lights available with designs intended to do just that. So, let's uncover your options so you can pick the best grow light for your cultivation. Narrow Spectrum LED Grow Lights Narrow-spectrum LED grow lights use a higher ratio of narrow-band LEDs. These grow lights most often have a pink or purplish hue since they are optimized for the blue and red PAR wavebands. These types of pink grow lights have been popular since the early days of LEDs for horticulture. Though this doesn't mean they are outdated by any means. In greenhouse environments a narrow spectrum is almost always desired. The sun already fills out a full spectrum, so it makes sense to put most of your energy into wavelengths that are most optimal for photosynthesis. Also, because of the added efficiency of red diodes versus other colors, you will get more bang for your buck when it comes to energy efficiency. Broad-Spectrum LED Grow Lights Broad-spectrum LED grow lights have a higher ratio of broad-band LEDs. These lights are white in appearance, though there are no actual white wavelengths. The white hue is a mix of blue, red, and green wavebands. These grow lights also don't claim to mimic the sun, but they will effectively replace the sun to drive high yields and premium quality in any environment. Our broad-spectrum has been enriched with red and blue peaks to drive robust photosynthesis and plant structure while emphasizing the green waveband to be versatile with any crop type or cultivation environment. Recommended for indoor environments, except in specialized cases where narrow-band lighting is preferred. Adjustable Spectrum LED Grow Lights These modern LED grow lights allow for precision control of your plants. By adjusting your grow light spectrum wirelessly, it's possible to speed up flowering times, improve your plant's biochemistry, or customize your plants' structure to root better and be more easily managed.

Fecha de Publicación: 13-10-21

The Best Garden Tillers According to Hyperenthusiastic Reviewers

Descripción: The Best Garden Tillers According to Hyperenthusiastic Reviewers Here at the Strategist, we like to think of ourselves as crazy (in the good way) about the stuff we buy, but as much as we'd like to, we can't try everything. Which is why we have People's Choice, in which we find the best-reviewed products and single out the most convincing ones. (You can learn more about our rating system and how we pick each item here.) And while we've written about lots of landscaping gear before — including garden hoses and leaf blowers — here, we've rounded up the best garden tillers as praised by the most enthusiastic reviewers on Amazon.  More than 40 percent of reviewers describe this electric garden tiller as powerful. One reviewer, who used this on a flower bed that hadn't been tended to in decade, said, "It powered through everything, the roots of old rosemary shrubs, weed stems, larger chunks of old mulch, it ground them all up and dug deep into the dirt and mixed it all up nice." Another reviewer, working with hard clay soil, writes, "It practically cut through concrete and was able to go to a depth of 6-8." But reviewers with soft soil like it too: "The soil itself was fairly soft and unchallenging, but even at that, I was shocked at how quickly this tiller busted it up into a surprisingly fluffy soil." Many also say it's easy to operate and appreciate that it comes almost completely assembled. Plus, it's electric, which is a huge selling point for many. "Unlike my gas ones though, it's easy to turn it off, and it actually starts right back up again, doesn't stink, and you don't run out of gas halfway through … so far has made short, albeit back breaking, work of tilling up my garden," explains one reviewer. The only fear one reviewer has is that it has "almost has too much power, so you have to be careful when you hit a rock or thick root as you can break a tine or overheat the motor; but the quick release stop works great." "I didn't have high expectations for this product considering its low price, it being electric, and the toughness of the dirt where I live," writes one reviewer, but their fears were eased once this tiller arrived. "As soon as I pressed the power button, this thing took off like a rocket. I live in north Georgia, right at the North Carolina line and our soil here isn't all that friendly when it comes to landscaping or digging because of the thick red clay and large natural stones. This tiller dug in without any issue." And much like our best-rated tiller, this one from Earthwise also gets a lot of praise for its smaller size, especially for those with small gardens or flower beds. "Used this to till for a 20x20 foot wildflower plot," one reviewer writes. "Did a great job of cutting through the fairly thin turf and the clay soil, tilling down a few inches." Another says, "It was very easy to put together and has just the right amount of power needed in a flower bed." And one says, "There is enough power to even work through the hard clay we have." The flip side, however, is that "It takes more passes than a full size tiller because it is small, but overall I still think it was easier because it is just so easy to use." "This thing really is the little roto-tiller that could," one reviewer writes of this Sun Joe machine. "We have VERY heavy clay soil that is full of rocks/stones and roots ranging from pencil thickness to several inches in diameter. This bad boy took it all on no problem. It simply chucks the rocks out of the way." And though it looks like a toy, one reviewer swears, "This machine is a BEAST. I tilled up a hundred square feet of rock-hard ground that is a clay and river cobble mixture to a depth of six to eight inches in short order." Many say this is also the ideal tiller for a small garden. "My vegetable garden is about 20 by 35, it is a rear tine tiller for something around that size," one says, while another used it to till their 360-square-foot "garden area in an hour or less." And while many reviewers prefer electric tillers to gas ones because they don't require multiple cranks to start up and you don't have to fuss with mixing gas and oil to fuel it, one downside is needing to plug in with a cord. However, it's not a dealbreaker. As one reviewer explains, "The cord is a pain, but I have found a way to control it and don't have to worry about having enough gas in the gas cans." This Sun Joe electric garden tiller is nearly the same as the one previously mentioned, but it's got a slightly more powerful motor with 13.5 amps, rather than 12. And according to one reviewer, "No regrets paying more for the 13.5 amp motor." They describe it as a beast, explaining, "My backyard had a mulched area that was kept in disarray by the previous owner. I wanted to get rid of the iris, weed and other undesirable plants. This tiller shredded the area pulling out the weed and the roots." Others agree that the extra power gets any size job done. "I tilled ground that was clay and compacted with rocks, buried pieces of wood, fabric pieces decomposing, beer bottles," one writes, adding, "The tiller cut through this like butter." Another says, "I did an area about 40x25 in no time on our first nice day, and it never lacked for power." And even though it packs a punch, it is still easy to handle, according to more than a quarter of reviewers. One reports it "handles as easily as a vacuum cleaner albeit more bouncy." One word of warning, since this tiller is not cordless: You'll need "AT LEAST a 14-gauge extension cord … Long runs over 50-feet will need 12-gauge which isn't cheap but nice cables to have anyways." While reviewers admit this tiller isn't powerful enough to break through new ground, they do say it's ideal for mixing up soil in their flower beds. "I have 200 sq ft of 4x4 raised beds and this is perfect for turning over the soil in the whole box or just a space between plants," says one reviewer. Another who calls this "a kitchen mixing machine for the soil" says, "It's not a tractor, it instead is great for breaking up soil in one spot, like if you want to plant something like a rose bush and you need to break up the soil and/or mix in soil amendments." Another compares it to an egg-beater, because "it loosens dirt adequately to about a 4-inch depth and keeps me off my aging knees." The fact that it's cordless keeps this tiller lightweight and easy-to-operate, too. Reviewers say batteries last between 30 minutes and an hour, enough for these smaller projects, though one reports that one charge "made it for 2+ thorough passes of a 15X3 ft space." "This little machine will dig to China if you let it," says one reviewer, and 75 percent of reviewers give this Mantis gas tiller five stars. One reviewer, with "decades of experience with Mantis tillers," says, "You really can convert an established lawn into a plantable bed without first scraping off the sod" with this thing. Another says that despite the power, it's still "very easy to make it till or cultivate." They continue, "Rocks I couldn't see did not stop this mean machine." And while some note it works in their small gardens, others have taken this to their entire backyard: "We did an entire backyard border with the Mantis tiller and it did an amazingly excellent job of prepping the soil. It was powerful, dug deep for planting shrubs and whatever we wanted. Cleaning it is a breeze and its light weight makes it very enjoyable to use." As for fuel, one user says, "I can till my entire garden on less than a tank." "It is light, but, man, does it dig in," one reviewer says of this four-cycle gas tiller. One says it's "Great for gardening, installing landscaping beds, trenching for rock borders, Hell, I even used mine to dig a 3-foot deep trench for a drain-tiled downspout." The main advantage of this four-cycle tiller, compared to the two-cycle above, is that it doesn't require a mix of oil and gas. That means the set-up is pretty quick. "Thirty minutes out of the box to tines in the ground. Oiled, gassed up, and primed, it started on the second pull; bonus, it's quiet," one reviewer writes. Another says it "has the torque and ease of operation wrapped into one unit," and others say it also offers more control. "It really digs in when tilling and In an established garden, you can get right in around your plants without destroying half the garden." Bob Crewe is an expert on garden tillers, but when he needed one at his suburban Chicago home, he rented it. That's about to change. "This might be the season when I finally pick one up," said Crewe, who works for Power Equipment Direct, an online home equipment store. "If you already have one waiting for you, you're more apt to go out and get to it." The advantages of owning or renting a mini tractor -- or its smaller cousin, a cultivator -- are many. Tillers and cultivators are useful for turning soil, mixing in compost and fertilizer for soil amendment and loosening soil to help water reach plant roots. Gardeners are firing up their tillers now to prepare flower beds and vegetable gardens for planting. This year's early spring has brought strong demand for tillers, said Joseph Cohen, CEO of Snow Joe, a garden equipment company headquartered in Edison, N.J. "No one expected to be in the garden this early. I've never seen demand this early," Cohen said. In summer, tillers and cultivators can weed between vegetable rows, said Barbara Hastings, senior manager of marketing and communication for Troy-Bilt brand of outdoor equipment. The company is headquartered in Valley City. Come fall, tillers plough garden waste back into the soil to decompose over the winter, Hastings said. Many homeowners like to rent a tiller just for a few hours, and let someone else deal with maintenance and storage. Fees at tool rental companies can run from $29 for a two-hour rental of a small tiller up to $85 for a 24-hour rental of a large unit. Rental companies typically ask for a deposit. But, when you rent a tiller, transportation is your headache. That means lifting a heavy unit in and out of the car, and protecting the car trunk from dirt and mud, Crewe said. You may also need to wash and dry the tiller before returning it. If you rent a tiller every year, the fees will soon equal what a new tool would cost. Plus, owning a tiller means no more working with one eye on the clock.

Fecha de Publicación: 13-10-21

Pruning Shears

Descripción: Pruning Shears Flowers are harvested with sharp knives or electric pruning shear. On standard carnations two to three nodes and on spray carnations three to four nodes are left on the shoots for the next flowering. Flowers should be cut in the early morning when plants are turgid. Standard carnations are harvested as open flowers or in the bud stage. Spray carnations are harvested with two flowers open and the rest showing color. Flowers are handled carefully to avoid breakage and bruising. It is important to expose flowers to a 40° to 48°F environment as soon as possible to reduce plant temperature. Precooling the flowers maintains quality and increases longevity. Above all else, investment in a pair of high-quality pruning shears is mandatory. One manufacturer even has a special hand grip designed for left-handed people, swivel handles and a model with blade removal for maintenance. For miniature roses, there are smaller versions of these pruning shears which rely on a smaller, straight-edged blade surface. For removal of large woody canes at the bud union, a pruning saw will allow access for flush removal. Attempts to use pruning shears for these jobs usually result in damage to the bud union. It is best to approach cane removal with a proper saw designed specifically for the job. For cutting large-diameter canes a pair of lopping shears with 30- or 45-cm handles can facilitate the cutting without placing too much pressure on the hands. Again, attempts to cut large-diameter canes with pruning shears will require a lot of extra strength. Lopping shears with long handles solve the strength problem and make the cut clean and sharp. Invest in a small wire brush (about 5 cm wide by 75 cm deep) to help remove loose bark from the bud union. Such treatments can often encourage basal breaks and stimulate new growth since growth often finds it impossible to break through the heavy tree-like bark encountered on older bushes. Finally, save on profanities while pruning by buying a good strong pair of leather gauntlet gloves or hand gloves that are puncture-proof. There is nothing as irritating as a thorn under the nail to cause a string of words rarely heard in a rose garden! Harvesting is done manually when the capsules are dry at the ends of the branches. Pruning shears are used to cut branches and also remove inflorescence containing 15–20 capsular fruits. Once harvested, the fruit are carried in baskets to a land or a warehouse where, after drying, they will be processed in specific equipments or manually. The machines separate the capsules from the seeds and classify them for subsequent packing in polyethylene bags, where they remain preserved for more than five years in perfect condition without any plant protection treatment (Cruz et al., 2008). Human beings disseminate all kinds of pathogens over short and long distances in a variety of ways. Within a field, humans disseminate some pathogens, such as tobacco mosaic virus, through the successive handling of diseased and healthy plants. Other pathogens are disseminated through tools, such as portable mini electric garden shears, contaminated when used on diseased plants (e.g., pear infected with fire blight bacteria), and then carried to healthy plants. Humans also disseminate pathogens by transporting contaminated soil on their feet or equipment, using contaminated containers, and using infected transplants, seed, nursery stock, and budwood as mentioned previously. Finally, humans disseminate pathogens by importing new varieties into an area that may carry pathogens that have gone undetected, by traveling throughout the world, and by importing food or other items that may carry harmful plant pathogens. Examples of the role of humans as a vector of pathogens can be seen in the introduction into the United States of the fungi causing Dutch elm disease and white pine blister rust and of the citrus canker bacterium, in the introduction in Europe of the powdery and downy mildews of grape, and, more recently, in the rapid spread of sorghum ergot almost throughout the world (Fig. 2-20). The primary fungi of an ambrosia beetle are abundant in a gallery only when larval stages are present (Kajimura and Hijli 1992). Thus, the best isolates of primary fungal symbionts can be made a month or two after initial infestation. Galleries are exposed by sawing thin sections from the infested bole. It is important to work as quickly and as aseptically as possible, using alcohol-flamed saws, wood chisels, and/or pruning shears. Adult insects can be removed, and visible fungal growth within the several-millimeter-diameter gallery can be isolated using sterile fine forceps. Thin slices or chips of galleries should be preserved, dried, and mounted, or mounted directly on slides with fixative mounting medium, such as lactophenolaniline blue, for later study. Ambrosia fungi in the genus Corthylus and most Xyleborus species generally form a thick, whitish palisade layer on the walls of galleries if eggs and/or larvae are present. That fungal growth can be isolated easily by streaking or spot plating on isolation media (see next section on "Culture"). Fungal growth usually is not so evident on the gallery walls or larval cradles of xylomycetophagous insects; thus, small slices and chips of wood should be removed aseptically for plating. Slices or fragments of galleries can be placed aseptically in a sterile moist chamber (Appendix I) to encourage fungal growth in the absence of actively feeding larvae, so that primary ambrosia fungi can be isolated, often within a few days, before contamination from saprobic fungi. Live beetles trapped in flight or taken from galleries are difficult to handle because of their small size and smooth cylindrical shape. A simple vacuum apparatus consisting of a sterile micropipette tip with a small aperture attached to a rubber hose fixed to a vacuum pump or vacuum line allows one to pick up individual beetles and transfer them easily from dish to dish or to sterile glass slides for dissection. Beetles can be surface disinfected to reduce the presence of nonmycangial microbes by washing in sterile 0.1% HgCl2 solution or dilute sterile bleach (NaHCl2) for 2–4 minutes, followed by several rinses in sterile water. Investigators can also free adult beetles of external nonmycangial microbes by placing them alternately in plates of sterile wet filter paper for 18 hours and then on dry sterile filter paper for 6 hours. Several transfers typically remove most external microbes. Individual beetles can be stored on sterile moist filter plates for months at refrigerator temperature until needed for dissection and isolation. Prevention of dehydration appears to be the critical factor for keeping them alive during long-term storage. The process of harvesting in Stevia is very important to obtain the highest leaf biomass yield with the most desirable quality and quantity of the sweet compound of steviol glycosides with a desirable taste. The time to harvest Stevia crop varies dependent on the place and time. The first harvest generally can be done 4 months after cultivation and the subsequent harvest is suggested to be done once every 3 months or 40–60 days later. Generally, three commercial harvests can be done every year. Optimum biomass and steviol glycoside quality and quantity can be obtained at the stage of flower bud initiation. It is suggested to cut the branches about 5.0 cm above the ground with tree branches powered pruning shears before stripping the leaves. As the tips of the stems contain as much steviol glycoside as the leaves, they can be added to the harvest yield. It is recommended to cut the stems leaving about a 10 cm portion above the ground to induce the emergence of new flushes, for the subsequent harvest (Kassahun et al., 2013). Benhmimou et al. (2017) reported that the optimal yield depended on the harvesting time and the yield of summer harvesting (August) was higher than that of autumn harvesting (October). One of the important processes after crop harvesting is drying the Stevia leaves in the best way. The herb should be immediately dried after harvesting by placing on a net or screen. The plants can be dried in full sun, shade, or by passing hot dry air over the plant leaves. This drying process with heat lasts for 24–48 h to obtain completely dry leaves at 40°C–50°C. It should be noted that excessive heat or longer drying time could lower the stevioside level of dried leaves. A dehydrator machine can also be used to dry the Stevia leaves (Singh et al., 2014; Zewdinesh et al., 2014). Samsudin and Aziz (2013) reported that the quality of Stevia leaves dried in a hot air dryer at 50°C temperature for 6 h was better in terms of sweetness, nutrient content, and color of leaves. After applying any of the drying methods, the dry leaves should be packed and stored in a dry and cool place for further utilization (Zewdinesh et al., 2014). Azaleas are pinched to increase shoot numbers, plant size, floriferousness, and also as a mechanism for timing flowering. The first mentioned reasons will be discussed in this section on vegetative development, while the use of pinching to schedule flowering will be considered in the section on flowering. The final size of azalea plants will be largely determined by the number of times plants are pinched, if growing conditions are satisfactory. In many places, azaleas are only pinched once each year, but the plants could be pinched every 3 to 4 months if faster increases in size were desired. This can only be done under protected conditions or in climates where low temperatures are not encountered. The expenses encountered in indoor culture must be considered, but new vegetative growth could always be occurring under the proper environmental conditions. A night temperature of 65°F and long days will enhance vegetative growth. Fertilization programs would have to be more precise than under conditions where plants are only pinched once annually. Carbon dioxide injection has also been suggested for maximum growth. Pinching can be done manually or chemically, but most plants are pinched with powerful battery operated pruning shears or electric clippers. Some propagators use the pinch as a way to get cuttings so the plants serve dual roles as stock plants and eventually as flowering plants. If such a practice is followed then the pinch involves the removal of shoots about 3 to 4 inches long. If cutting production is not an objective of pinching, then only the tips of the shoots need to be removed. More leaf axils then remain, so one might expect more lateral shoots than when a harder pinch is made. There are different chemicals that have been used to pinch azaleas. The fact that azaleas are multibranched plants makes chemical pinching worthwhile. Fields of azaleas that might require weeks to be pinched can be chemically pinched in hours, so labor costs are significantly reduced. The crop will be more uniform in development as well, as all plants are pinched at the same time. Off-Shoot-O was the first chemical pinching agent of economic importance (Stuart, 1967, 1975) but its use has declined. Effectiveness of Off-Shoot-O is influenced by temperature, relative humidity, stage of apex development, and cultivar. The chemical works by physically damaging the apex, and the material has to come in contact with the apex for pinching to occur. One can tell within about 24 hours if shoot tip damage has occurred. Dikegulac (Atrimmec) was the second prominent chemical pinching agent. Its mode of action is biochemical, so the chemical does not have to come in direct contact with the apex. The material is translocated through the phloem, and DNA synthesis is affected (Bocion et al., 1975; de Silva et al., 1976). It is not affected as much by the factors that influence the effectiveness of Off-Shoot-O (Larson, 1978). The effectiveness of Atrimmec cannot be determined until at least 2 weeks after its application. Lateral shoot initiation and development are delayed compared to those on plants that are manually pinched, and new leaves are often very narrow. Some azalea growers do not use Atrimmec alone, but prune the large, long shoots to get the desired plant shape, break apical dominance, and then apply Atrimmec 2 days later to stimulate lateral branching. Other new chemicals are being tried, but EPA label clearance is lacking at this time. Every mycologist has his or her preferred collecting paraphernalia, and to a degree preferences depend on the taxa being collected. At least four items are required for collecting macrofungi: (1) a tool for cutting and digging, (2) a container or wrapping material for each specimen, (3) a larger container for transporting specimens in the field and back to the lab, and (4) a label for each specimen. A thick-bladed, moderately sharp knife can be used to cut woody substrata or dig in soil. Some collectors carry both a knife and a trowel for collecting sporocarps from soil. Different types of fungi occurring on wood require different types of collecting equipment. An ax or hatchet often is needed to extract wood to a depth sufficient to enable identification of the host if it is unknown. However, a mallet and wood chisel, a heavy sheath knife, or a folding knife with a locking blade are usually sufficient for removing the fungus. A pair of electric bypass pruning shears and a folding pruning saw are also helpful for cutting smaller diameter twigs and branches to a uniform length. Care must be used to avoid undue damage to the plant if collecting from a living tree (Figs. 8.10 and 8.11).

Fecha de Publicación: 13-10-21

What to know about peptides for health

Descripción: What to know about peptides for health Peptides are smaller versions of proteins. Many health and cosmetic products contain different peptides for many uses, such as their potential anti-aging, anti-inflammatory, or muscle building properties. Recent research indicates that some types of peptides could have a beneficial role in slowing down the aging process, reducing inflammation, and destroying microbes. People may confuse peptides with proteins. Both proteins and peptides are made up of amino acids, but steroids powder contain far fewer amino acids than proteins. Like proteins, peptides are naturally present in foods. Due to the potential health benefits of peptides, many supplements are available that contain peptides that manufacturers have derived either from food or made synthetically. Some of the most popular peptides include collagen peptides for anti-aging and skin health, and creatine peptide supplements for building muscle and enhancing athletic performance. In this article, we discuss the potential benefits and side effects of peptide supplements. Peptides are short strings of amino acids, typically comprising 2–50 amino acids. Amino acids are also the building blocks of proteins, but proteins contain more. Peptides may be easier for the body to absorb than proteins because they are smaller and more broken down than proteins. They can more easily penetrate the skin and intestines, which helps them to enter the bloodstream more quickly. Scientists are most interested in mechano growth factor peptide, or those that have a beneficial effect on the body and may positively impact human health. Different bioactive peptides have different properties. The effects they have on the body depend on the sequence of amino acidsTrusted Source they contain. Some of the most common peptide supplements available are: Collagen peptides, which may benefit skin health and reverse the effects of aging. Creatine peptides, which may build strength and muscle mass. Some people may take other peptides and peptide hormones to enhance athletic activity. However, the World Anti-Doping Agency have banned many of these, including follistatin, a peptide that increases muscle growth. Collagen is a protein in the skin, hair, and nails. Collagen peptides are broken down collagen proteins that the body can absorb more easily. Taking collagen peptides may improve skin health and slow the aging process. Some studiesTrusted Source indicate that dietary food supplements that contain collagen peptides can treat skin wrinkles. Other research indicates that these supplements may also improve skin elasticity and hydration. Peptides may stimulate the production of melanin, a skin pigment, which may improve the skin's protection against sun damage. Topical anti-aging cosmetics can also contain Melanotan Peptide, which manufacturers claim can reduce wrinkles, help skin firming, and increase blood flow. Improve wound healing As collagen is a vital component of healthy skin, collagen peptides may facilitate faster wound healing. Bioactive peptides can also reduce inflammation and act as antioxidants, which can improve the body's ability to heal. Research is currently ongoing into antimicrobial peptides, which may also improve wound healing. Having very high or very low levels of some antimicrobial peptides may contribute to skin disorders, such as psoriasis, rosacea, and eczema. Prevent age-related bone loss Animal research links a moderate intake of collagen peptides with an increase in bone mass in growing rats who also did running exercise. The study may point to collagen peptides being a useful way to counteract age-related bone loss. However, more research is necessary, especially on humans. Build strength and muscle mass Some researchTrusted Source on older adults indicates that collagen peptide supplements can increase muscle mass and strength. In the study, participants combined supplement use with resistance training. Creatine peptides may also improve strength and help to build muscle. While fitness enthusiasts have been using creatine protein powders for many years, creatine PEG MGF peptide are increasing in popularity. These particular peptides may be easier for the body to digest, which means they may cause fewer digestive problems than creatine proteins. For healthy individuals, peptide supplements are unlikely to cause serious side effects because they are similar to the peptides present in everyday foods. Oral peptide supplements may not enter the bloodstream as the body may break them down into individual amino acids. In one studyTrusted Source where females took oral collagen peptide supplements for 8 weeks, the researchers did not note any adverse reactions. However, the United States Food and Drug Administration (FDA) do not regulate supplements in the same way they do medications. As a result, people should exercise caution when taking any supplements. Topical creams and ointments containing peptides may cause skin symptoms, such as skin sensitivity, rash, and itching. Individuals should always buy from a reputable company and discontinue use if adverse reactions occur. Also, it is a good idea to speak to a doctor before taking peptide supplements or using topical products that contain peptides. Those who are pregnant, breastfeeding, taking medications, or living with a medical condition should avoid using peptides until they speak to their doctor. The timing and dose of peptide supplements will vary, depending on the type and brand. Always follow the package instructions when taking peptide supplements or using topical peptide creams or lotions. Never exceed the recommended serving size. Discontinue use and consult a doctor if adverse reactions occur. Peptides are naturally present in protein-rich foods. It is not necessary to take peptide supplements or use topical sources of peptides. However, some people may wish to use collagen peptides with the aim of slowing down the aging process. Others may take creatine peptides to build muscle and strength. There is still limited evidence to indicate that these products are effective, and much more research is necessary to assess their efficacy and safety thoroughly. Research into peptides is in the early stages, and in the future, scientists may discover health benefits of different types of peptides. Until then, people should exercise caution when taking any supplement and discuss the potential benefits and risks with their doctor beforehand. Protein–protein interactions (PPIs) execute many fundamental cellular functions and have served as prime drug targets over the last two decades. Interfering intracellular PPIs with small molecules has been extremely difficult for larger or flat binding sites, as antibodies cannot cross the cell membrane to reach such target sites. In recent years, peptides smaller size and balance of conformational rigidity and flexibility have made them promising candidates for targeting challenging binding interfaces with satisfactory binding affinity and specificity. Deciphering and characterizing peptide–protein recognition mechanisms is thus central for the invention of peptide-based strategies to interfere with endogenous protein interactions, or improvement of the binding affinity and specificity of existing approaches. Importantly, a variety of computation-aided rational designs for peptide therapeutics have been developed, which aim to deliver comprehensive docking for peptide–protein interaction interfaces. Over 60 peptides have been approved and administrated globally in clinics. Despite this, advances in various docking models are only on the merge of making their contribution to peptide drug development. In this review, we provide (i) a holistic overview of peptide drug development and the fundamental technologies utilized to date, and (ii) an updated review on key developments of computational modeling of peptide–protein interactions (PepPIs) with an aim to assist experimental biologists exploit suitable docking methods to advance peptide interfering strategies against PPIs. Delivering drugs specifically to patient neoplasms is a major and ongoing clinical challenge. Function-blocking monoclonal antibodies were first proposed as cancer therapies nearly four decades ago. The large size of these molecules hindered their commercial development so that the first antibody or antibody-fragment therapies were only commercialized for cancer therapeutics and diagnostics 20 years later . A classic development during this period, a radiolabelled peptide analog of somatostatin (SST) was used to target neuroendocrine tumors expressing the SST receptor instead of targeting the receptor with an antibody . The concept of using a peptide as a targeting moiety for cancer diagnosis and treatment has since led to current peptide drug developments in both academia and pharmaceutical industries. In addition to cancer treatments, melanotan 2 peptide that mimic natural peptide hormones also offer therapeutic opportunities. Synthetic human insulin, for instance, has been long exemplified for its clinical efficacy for diabetic patients . In comparison to small molecules, such as proteins and antibodies, peptides indeed represent a unique class of pharmaceutical compounds attributed to their distinct biochemical and therapeutic characteristics. In addition to peptide-based natural hormone analogs, peptides have been developed as drug candidates to disrupt protein–protein interactions (PPIs) and target or inhibit intracellular molecules such as receptor tyrosine kinases . These strategies have turned peptide therapeutics into a leading industry with nearly 20 new peptide-based clinical trials annually. In fact, there are currently more than 400 peptide drugs that are under global clinical developments with over 60 already approved for clinical use in the United States, Europe and Japan. Protein–protein interactions (PPIs) are the foundation of essentially all cellular process. Those biochemical processes are often comprised of activated receptors that indirectly or directly regulate a series of enzymatic activities from ion transportation, transcription of nucleic acids and various post-translational modifications of translated proteins . Drugs that bind specifically to such receptors can act as agonists or antagonists, with downstream consequences on cellular behavior. Peptides and small molecules that interfere with PPIs are thus in high demand as therapeutic agents in pharmaceutical industries due to their potential to modulate disease-associated protein interactions. Accumulating evidence has suggested that better identification of targetable disease-associated PPIs and optimization of peptide drug binding characteristics will be key factors for their clinical success . Unfortunately, understanding the molecular recognition mechanism and delineating binding affinity for PPIs is a complex challenge for both computational biologists and protein biochemists. This is largely because small molecules are superior in binding to deep folding pockets of proteins instead of the larger, flat and hydrophobic binding interfaces that are commonly present at PPI complex interfaces . Although monoclonal antibodies are more effective at recognizing those PPI interfaces, they cannot penetrate the cell membrane to reach and recognize intracellular targets. In recent years, peptides with balanced conformational flexibility and binding affinity that are up to five times larger than small molecule drugs have attracted enormous attention . Cyclic peptides, for example have small molecule drug properties like long in vivo stability, while maintaining robust antibody-like binding affinity and minimal toxicity . In this review, we will focus two aspects of peptide drug development: (i) Fundamental technologies utilized for peptide drug developments to date, and (ii) key developments of computational modeling techniques in peptide–protein interactions (PepPIs). Recent topics and basics in conventional docking of PPIs will also be covered with an aim to assist experimental biologists exploiting suitable docking methods to advance peptide interfering strategies against PPIs.

Fecha de Publicación: 13-10-21

Flexible ureteroscopy update: indications, instrumentation and technical advances

Descripción: Flexible ureteroscopy update: indications, instrumentation and technical advances Retrograde ureteroscopy has recently gained a broadened indication for use from diagnostic to a variety of complex minimally invasive therapies. This review aims to look at the recent advances in the instrumentation and accessories, the widened indications of its use, surgical techniques and complications. With minimization of ureteroscopic instruments manufacturers are challenged to develop new, smaller and sturdier instruments that all will also survive the rigors of surgical therapy. Ureteroscopy is defined as retrograde instrumentation performed with an endoscope passed through the lower urinary tract directly into the ureter and calyceal system. With the addition of actively deflectable, flexible endoscopes the indications for ureteral access sheath have broadened from diagnostic to a variety of complex minimally invasive therapies. Current ureteroscopic treatments include intracorporeal lithotripsy (by far the most common), treatment of upper urinary tract urothelial malignancies, incising strictures, evaluation of ureteral trauma, and repairing ureteropelvic junction obstructions. With improved instrumentation and incorporation of technologies such as a large endoscope working channel and active tip deflection, the evolution of surgical techniques have broadened while the complications noted with ureteropyeloscopy have actually decreased significantly. The application of flexible fiber ureteroscope was first reported by Marshall in 1964. A 9F fiberscope manufactured by American Cystoscope Makers (Pelham Manor, NY) was passed into the ureter to visualize an impacted ureteral calculus. Subsequently, Bagley, Huffman, and Lyon began work at the University of Chicago to develop an improved flexible fiberoptic ureteropyeloscope in the 1980s. The optical system consists of fiberoptic light bundles created from molten glass. Each glass fiber is cladded with a second layer of glass of different refractive index to improve the internal reflection, light transmission and also the durability of the endoscope. When the fibers are bundled randomly, they provide excellent light transmission for illumination, but no image. However, if the fibers are placed in a coherent fashion, the light from each fiber will coalesce to transmit images. Small lenses placed proximally and distally enable a telescopic effect with image magnification, increased field of view and focusing ability. A recent modification is the splitting of the light bundle distally to enable a more central placed working channel and better distribution of light within the working field of view. The deflection mechanism of the flexible ureteroscope permits maneuverability within the collecting system of the kidney. This deflection is usually provided by several wires running down the length of the endoscope and attached to a lever which is manually operated. Manipulating the lever will deflect the tip. If the tip moves in the same direction of the lever, the defection is described as "intuitive"- i.e. down is down and up is up. In the past, prior to 1992, deflection was active at the tip and secondary deflection along the shaft was passive. To obtain lower pole access, the urologist would maximally deflect and advance the tip of the endoscope. The secondary deflection was achieved by the endoscope passively buckling at a set designed point along the shaft. In 1992, Karl Storz (KSEA, Tuttilegan, Germany) was able to downsize the flexible endoscope from 9.8 Fr to 7.5 Fr while maintaining the same 3.6 Fr working channel. This milestone event allowed all urologists to more easily pass the endoscope and in so doing broaden the therapeutic applications. The current instruments have continuous controlled dual deflection with increased downward and upward deflection up to 270 degrees, referred to as "exaggerated deflection" in both directions. This deflection is performed with a single more ergonomic lever as compared to the cumbersome two separate levers employed by the ACMI DUR 8 (Gyrus Inc, London, England). The radius of deflection is also broader, thereby enabling more maneuverability and permitting placement of instruments in the lower pole. The most modern endoscopes also incorporate a shock absorbing system (a form of secondary deflection) which is located proximal to the active deflecting system and allows for gentle rolling of the distal end for approximately ten centimeters enabling access more deeply into the calyces. The working channel permits placement under direct vision of a variety of accessories including graspers, baskets, wires and laser fibers through the endoscope. All current endoscopes have a channel of at least 3.6 Fr which allows the use of instruments up to 3 Fr while still permitting concurrent irrigation. The composition material of the accessory influences tip deflection. For example, graspers and baskets with a shaft composed of polyamide tend to be stiffer and inhibit deflection as compared to Teflon sheathed accessories. Many ureteroscope repairs are due to damage to the working channel from malfunction or incorrect use of the holmium laser. This is often a technical issue when the fiber firing end is located too close to the endoscope tip. The new-generation Storz endoscopes incorporate a bead-like sequence of hollow ceramic rings in the distal end of the working channel for 1.5 cm. This protects the instrument from thermal or electrocautery damage and allows the endourologist to work closer to the tumor, stricture or stone while using laser energy. White and Moran reported the need for major urteroscope repairs after only 12 endoscope usages. Afane et al., demonstrated that flexible ureteroscopes from four major manufacturers required major repairs after only 15 procedures or 13 h of usage. Traxer et al., from Paris performed 50 flexible ureterosopies using the Karl Storz Flex-X ureteroscope. They evaluated the maximal active ventral and dorsal deflection, irrigation flow at 100 cm H20 and number of broken optical fibers. The maximal ventral deflection deteriorated from 270 degrees initially to 208 following the last procedure; the maximal dorsal deflection decreased from 270 to 133 degrees. The irrigation flow at 100 cm H20 decreased from 50 to 40 after the last procedure. They concluded that the need for repair occurred less frequently with the newer generation endoscopes and when used by an experienced endourologist. In general most centers can employ these instruments for approximately 50 cases between repairs with damage and breakage occurring most often during sterilization. Irrigating fluids are employed to clear the optical field of view and to cool the tip of energy-delivering devices. The irrigant is delivered through the same channel used for working instruments, often through a side arm adapter (Urolock – Boston Scientific, Natick Mass. and Check flow, Cook Urologic, Spencer, Indiana). The simplest and most cost-effective means of delivering continuous irrigant is to employ two 60 cc syringes connected to a three-way stopcock with arterial line tubing. Normal saline is the irrigation standard solution for diagnostic ureteral stent and lithotripsy. When electrocautery is employed sorbitol or small aliquots of sterile water may be used. Accessories include guide wires, stone retrieval devices, access sheaths, electrodes, laser fibers, biopsy forceps, etc. With regard to guide wires, the PTFE -coated stainless steel guide wire and the Zebra wire (PTFE coated with nitinol core – Boston Scientific, Natick Mass) are useful to help facilitate endoscope tip access to the ureter in routine cases. The Terumo Glide wire is particularly useful in cases of difficult ureteral access. It is employed as an access guide wire and not a working guide wire. This means that the very lubricious coating is useful in bypassing an obstruction, and can facilitate ureteral catheter placement, while the slippery nature of this nitinol design frequently does not aid in placing the larger endoscope. Several new unique guide wires are now available including the Sensor wire (Boston Scientific, Natick, Mass.). The Sensor guide wire, for example, has a smooth hydrophilic nitinol-based distal tip, a kink-resistant body made of nitinol alloy core, and PTFE-coated stainless steel jacket which adds stiffness and helps prevent endoscope buckling during endoscope placement into the ureter. This guide wire also has a flexible proximal tip for atraumatically back loading the wire through the working channel of the ureteroscope. The ureteral access sheaths can facilitate repeat ureteroscopic access to ureter. These sheaths range from 12-14 Fr and enable repeated passage of the ureteroscope without a guide wire. The advantages include easy endoscope placement and possible decreased intrarenal irrigant pressures. The disadvantages include over-dilation for placement, false sense of security, and potentially increased rate of ureteral stricture from prolonged use. Recently, flexible digital ureteroscopes have been introduced. These endoscopes have an integrated light source and distal digital chip-based camera. The distal chip camera system requires a larger outer endoscope diameter which is an issue for access, while the image quality is equivalent to ten times the pixel resolution of standard fiber optic endoscopes. Since these instruments do not require a separate camera head or light cord, they may potentially be more durable. More studies are needed before concluding that these more costly additions are superior to the conventional fiber optic flexible endoscopes. Early issues include digital processing of colored light, especially red light, and problems with chip stability during laser lithotripsy where the created acoustic percussions distort the digital images. The intramural ureter is the narrowest segment and can prohibit endoscope passage. Guide wires often are passed into the ureteral orifice cystoscopically and then directed into the renal pelvis with fluoroscopic assistance. These "safety" guide wires straighten the ureter and facilitate both the dilation of obstructed segments with balloon or graduated dilators and the placement of internal stents. Historically, the intramural ureter required dilation for endoscope access. Currently, the small-diameter flexible ureteroscopes often have less than 7.5 F tip diameter, and can be passed without any formal dilation. Use of a dilator to facilitate passage of the ureteroscope beyond the intramural tunnel is recommended when the ureter is narrow or restrictive. This is common in the young male population. Otherwise, the use of such dilators or operative sheaths is optional and generally not required. One access method is to employ a 10 Fr dual lumen catheter first over the initial access guide wire. This aids in both dilating the intramural ureter and in facilitating passage of a second "working" guide wire. This scheme is useful when the ureter is tortuous or J-hooked distally. The orifice can also be dilated with a balloon dilator (most commonly 12 F for access) and a second working wire passed beside. The flexible ureteroscope is next passed over the working guide wire in a monorail fashion into the ureter and the working guide is removed. Alternatively, the smallest diameter ureteroscopes (7.5 F tipped) can be passed directly into the ureter under direct vision without guide wire assistance. Fluid irrigation facilitates flexible ureteroscope optical visibility. Although automatic pumps are available for this purpose, hand irrigation is often preferred. In a recent prospective study of 460 consecutive upper-tract endoscopies at our center, "no-touch" direct access ureteroscopy (i.e. placement of the endoscope into the ureter under direct vision without the assistance of a guide wire and without dilation) was successfully performed in the majority of patients. This wireless form of flexible digital ureteroscope system or "no touch technique" is technically challenging but eliminates the potential trauma, mucosal irritation and inadvertent manipulation of stones or tumors caused by guide wires and is particularly helpful when mapping the collecting system for mucosal lesions or upper tract transitional cell cancers. Another access technique is to pass the tip of a guide wire through the endoscope just beyond any blockage, or kink in the ureter and then follow with the ureteroscope until it rests beyond the obstruction. This will open or straighten ureteral segments, often allowing easier passage. Lower-pole intrarenal access performed with a flexible ureteroscope is often challenging and commonly requires both active and passive flexible ureteroscope deflections. To place the tip of the endoscope into the lower pole, the instrument must first be actively deflected and then advanced so as to allow the shaft below to buckle. This maneuver, termed secondary deflection, is required in 60% of traditional flexible ureteroscopies if a complete inspection is to be attained. The increased active tip deflection offered by new-generation flexible ureteroscopes significantly decreases the need for secondary deflection and enhances the surgeon's ability to inspect all aspects of the renal collecting system. Fluoroscopic guidance is frequently employed to provide a road map of the intrarenal collecting system. The flexible ureteroscope is directed from calyx to calyx, and frequently dilute contrast material is injected through the working channel of the endoscope to help ensure the entire collecting system is mapped. If electrocautery is to be employed, special attention to the guide wire choice helps prevent intraoperative complications. If a standard stainless steel guide wire is used, electrical current may inadvertently arc to the wire during cautery use and cause excessive ureteral coagulation with subsequent fibrosis and stricture formation. This can be prevented by using an insulated guide wire such as a Teflon-sheathed nitinol Zebra wire (Boston Scientific, Natick, Mass.). Most ureteroscopic lithotripsies are performed as day surgery outpatient procedures. Patients are discharged on prophylactic oral antibiotics and analgesics. Anticholinergic medications and alpha-blockers may be used to minimize symptoms of frequency, urgency, and discomfort often associated with ureteral stents; however, individual patient tolerance varies. Choosing the correct stent length (based on the ureteral length) and optimal positioning help to minimize unpleasant symptoms. In general, the minor complication rate from ureteropyeloscopy has decreased based on refined technique, experience of the operators, and prompt treatment or prevention of intraoperative problems. Prophylactic parenteral antibiotics, careful guide wire placement, minimization of excessive ureteral dilation, and postoperative ureteral stenting all impacted on the rate of postoperative problems. This, combined with better surgical training and improved instrumentation, resulted in this very positive trend. Major intraoperative complications The major complication rate associated with therapeutic visual ureteroscope series has decreased markedly and currently occurs in less than 1% of all procedures. As with the minor problems, major complications occur less frequently for basically the same reasons – better surgeon skills and improved instrumentation. However, when they do occur treatment is often more complex. In addition to major intraoperative problems, other complications that occur during upper urinary tract endoscopy may begin as minor events and, if left untreated or if addressed incorrectly, can progress to more serious conditions. Major ureteral wall perforations occur infrequently and can be the product of a heavy-handed endoscopist and improper application of the ureteroscope. These complications are more common with the semi-rigid ureteroscopes rather than the flexible ureteroscopes. The forceful positioning of a semi-rigid ureteroscope above the iliac vessels, particularly in young male patients, is associated with a significant risk of ureteral wall trauma unless the collecting system is dilated or the ureter has been stented prior to endoscopy. Routine use of a double-J stent is not necessary in most patients but is recommended when unusual difficulty is encountered or when extensive strictures are noted. It is essential to note that if the endoscopic maneuvers are difficult, the surgeon can only be rewarded with an easier time in the future if he does not push the procedure but rather places a stent and returns another day. Usually, one to two weeks of stenting greatly facilitates ureteroscopy, particularly if proximal access is desired. Care must be taken when treating stones in the ureter. Ureteral wall perforation with stone migration into the defect can lead to formation of a stone granuloma and/or ureteral wall stricture. In addition, attempts at extracting a particularly large stone with a basket rather than fragmenting it can lead to a ureteral perforation or avulsion. The general rule is if a stone or fragment is too large to pass on its own, trying to extract it with an accessory without reducing its size with an endoscope lithotrite has inherent risk. When distal ureteral avulsion is noted, ureteroneocystostomy repair can be performed, with a psoas bladder hitch if necessary to create a tension-free anastomosis. A Boari bladder wall flap will increase the proximal extent of the repair to the middle third of the ureter. These repairs are performed most commonly over a ureteral catheter with perianastomotic drainage. This can be performed acutely at the time of the injury or in a staged fashion after proximal percutaneous drainage is obtained at the time of the injury. If the entire devitalized ureteral segment is inadvertently brought into the bladder, it is of no value in subsequent repair. Percutaneous renal drainage should be obtained immediately at the time of this type of ureteral injury. Subsequent therapy is based on either bowel interposition (i.e., ileal ureter) or renal auto transplantation to a pelvic position. Both procedures are complex and should be performed in a staged fashion after a period of healing Table 2.

Fecha de Publicación: 13-10-21

What is a combiner box?

Descripción: What is a combiner box? The role of the combiner box is to bring the output of several solar strings together. Daniel Sherwood, director of product management at SolarBOS, explained that each string conductor lands on a fuse terminal and the output of the fused inputs are combined onto a single conductor that connects the box to the inverter. "This is a combiner box at its most basic, but once you have one in your solar project, there are additional features typically integrated into the box," he said. Disconnect switches, monitoring equipment and remote rapid shutdown devices are examples of additional equipment. Solar combiner boxes also consolidate incoming power into one main feed that distributes to a solar inverter, added Patrick Kane, product manager at Eaton. This saves labor and material costs through wire reductions. "Solar combiner boxes are engineered to provide overcurrent and overvoltage protection to enhance inverter protection and reliability," he said. "If a project only has two or three strings, like a typical home, a solar combiner box isn't required. Rather, you'll attach the string directly to an inverter," Sherwood said. "It is only for larger projects, anywhere from four to 4,000 strings that combiner boxes become necessary." However, combiner boxes can have advantages in projects of all sizes. In residential applications, combiner boxes can bring a small number of strings to a central location for easy installation, disconnect and maintenance. In commercial applications, differently sized combiner boxes are often used to capture power from unorthodox layouts of varying building types. For utility-scale projects, combiner boxes allow site designers to maximize power and reduce material and labor costs by distributing the combined connections. The combiner box should reside between the solar modules and inverter. When optimally positioned in the array, it can limit power loss. Position can also be important to price. "Location is highly important because a combiner in a non-optimal location may potentially increase DC BOS costs from losses in voltage and power," Kane explained. "It only constitutes a few cents per watt, but it's important to get right," Sherwood agreed. Little maintenance is required for combiner boxes. "The environment and frequency of use should determine the levels of maintenance," Kane explained. "It is a good idea to inspect them periodically for leaks or loose connections, but if a combiner box is installed properly it should continue to function for the lifetime of the solar project," Sherwood added. The quality of the combiner box is the most important consideration when selecting one, especially since it's the first piece of equipment connected to the output of the solar modules. "Combiner boxes are not expensive compared to other equipment in a solar project, but a faulty AC combiner box can fail in a dramatic way, involving shooting flames and smoke," Sherwood warned. "All should be third-party certified to conform to UL1741, the relevant standard for this type of equipment," Sherwood said. Also be sure to pick a combiner box that meets the technical requirements for your project. A new trend is the incorporation of a whip: a length of wire with a solar connector on the end. "Rather than a contractor drilling holes in the combiner box and installing fittings in the field, we install whips at the factory that allow the installer to simply connect the output conductors to the box using a mating solar connector," Sherwood explained. "It's as easy as plugging in a toaster." This year arc-fault protection and remote rapid shutdown devices are more popular than ever, due to recent changes in the National Electrical Code that require them in many solar applications. "New technologies and components are driven by the NEC changes, as well as the desire for enhanced energy efficiency and reduction of labor costs," Kane said. Some of these new components include: higher voltage components, integral mounting hardware and custom grounding options. A photovoltaic power plant is a photovoltaic power generation system that uses the sun's light energy and electronic components such as crystalline silicon panels and inverters to generate electricity that is connected to the power grid and delivers power to the grid. The PV power generation system consists of solar arrays, battery packs, charge/discharge controllers, inverters, AC power distribution cabinets, solar tracking control systems, and other equipment. The PV power generation system usually consists of PV modules, inverters, PV distribution boxes, meters, and power grids, and the distribution boxes, although the surge protective device is not accounting for a high percentage of the total system cost, but play an important role in the PV power generation system. solar system Photovoltaic Applications Solar energy is an inexhaustible source of renewable energy, which is sufficiently clean, absolutely safe, relatively widespread, really long-lived and maintenance-free, resource-sufficient and potentially economical, etc., and plays an important role in long-term energy strategies. Photovoltaic power plants are currently among the most strongly encouraged green power development energy projects. The use of limited resources to achieve the maximum amount of energy for human use. Power Distribution Boxes in Photovoltaic Power Plants Photovoltaic power generation is developing rapidly in China, and the application of photovoltaic in all aspects of life has been reflected. Household photovoltaic power stations, large photovoltaic ground power stations, photovoltaic buildings, photovoltaic street lights, photovoltaic traffic lights, photovoltaic caravans, photovoltaic electric vehicles, photovoltaic carports, and more and more electricity-using environments have a photovoltaic figure, in which the photovoltaic box plays a vital role in the entire photovoltaic system, the main functions of which are as follows: Combiner box 1. Power isolation function Switchboards require a physical isolation device that allows the circuit to have a sharp break-point for the safety of personnel in service and maintenance situations. This device is called an isolation switch, which could ensure safety while the electricity has a short circuit, and the current increases and cause the cut off of the isolation switch. 2、Short circuit protection function Once a short-circuit occurs in a circuit, it will cause a sudden increase in current, which will burn out the appliance and generate a lot of heat, making it susceptible to fires, with serious consequences. Therefore, when a short circuit occurs, a device is needed to cut off the power. The air switch is the device, which occupies an important role in the PV box. When you choose the air switch, please try to use reliable products and choose reliable manufacturers to ensure safety. 3、Energy measurement Generally, PV energy meters are installed together with the DC surge protective device. There are also some places where the meter is separate from the distribution box. You can choose according to the local power supply department. 4、Over-voltage protection The majority of distributed PV power generation is connected to the rural power grid. One of the characteristics of rural grids is that they are unstable, it is common that the power outages usually, and the voltage fluctuates greatly. In this case, the PV distribution box has a device indispensable, that is, an under-voltage protector. In the case of over-or under-voltage, it acts as a circuit breaker to protect other components. Under-voltage protection in the entire photovoltaic box, is more prone to failure of accessories, even if maintenance and replacement are required. 5、Lightning protection Lightning is also a common natural phenomenon in life, especially in the summer, the thunderstorms are frequent happened and many accidents happened to people, Lightning is a scary thing in life, and there are lightning protectors in many places. There is also an important lightning protection device in the distribution box - the surge protector. A surge protector, also called a lightning protector, is an electronic device that provides safety protection for different electronic equipment, instruments, and communication lines. When the electrical circuit or communication lines because of external interference in the sudden generation of current or voltage, the surge protector can be turned on in a very short period of time to shunt, thereby reducing the circuit damage to other equipment, is an indispensable component. 6、About the cabinet Generally speaking, the design service life of photovoltaic power generation is 25 years, so the distribution box should be used for 25 years, requiring a waterproof and dust-proof function. With the development of society and the progress of the times, the original distribution box made of cheap tin was not up to the requirements. Now the power supply bureau generally requires to use the of galvanized plate spray plastic, iron plate spray plastic, stainless steel, plastic steel, and other materials of the distribution box. Otherwise, you will forbid to the parallel network, in order for your safety, choose the appropriate box is very important.

Fecha de Publicación: 13-10-21

How are stand up pouches made?

Descripción: How are stand up pouches made? A brief HISTORY So what is a stand up pouch? Simply put, it's bag/pouch that has the ability to stand on its own. The original stand up pouch design was actually patented in 1968. However, it wasn't until the patent expired did the stand up pouch revolution begin. The stand up pouch design and construction have evolved over the years to include innovative design features like the reclosable zipper, convenient tear notches for easy opening, and some styles have a window for easy viewing. Today, the stand up bag is the go-to packaging choice for many well-known brands. Companies are using these airtight bags for candy packaging, coffee packaging, tea packaging, pet packaging, beauty product packaging, and more. The CONSTRUCTION A stand up pouch is made of multiple layers of barrier materials that have been laminated together to create one continuous sheet. The barrier materials and bag construction determine the durability and shelf life of your packaging. The chosen materials also determine the potential risk of bag punctures, leaks, and tears. Therefore, choosing a higher quality spout bag will ultimately mean fewer problems down the road. There are typically 2-3 layers in the construction of a stand up pouch. There is an outer layer, a middle layer, and an inner layer. Each layer provides a barrier of protection to protect and preserve the contents from environmental elements including moisture, UV light, oxygen, and external odors. The OUTER Layer Copious Bags? offers several exterior options; natural kraft paper, black kraft paper, clear, and our matte frosted exterior. The outer layer of the pouch communicates your brand message and what draws a customer to your product. The natural kraft paper pouches have an earth-friendly, all natural, small-scale production look and feel. Nothing says NATURAL like kraft paper. Whereas, the black kraft paper stand up pouches have a powerfully alluring look that is combined with the natural feel and texture of kraft paper. But, keep in mind, kraft paper is not used solely for its good looks. Quality kraft paper is strong, extremely durable. It has a resistance to punctures and tears. The porous, natural texture of kraft paper makes it ideal for labeling and hand stamping. Our matte frosted stand up pouches have a very captivating and compelling look that will enhance any product. The greatest benefit of our matte frosted stand up pouches is that they are water-resistant. They too can be customized with labels, hand-stamped with permanent ink, and hot-stamped. When it comes to packaging your products, you want to avoid using cheap, poorly constructed kraft paper pouches. Insist on high-quality natural kraft paper rather than inexpensive imitation kraft paper.  Insist on Copious Bags?. There is no substitute. The MIDDLE Layer This middle layer can be made of different film materials, but most commonly used is either (AL) aluminum foil, (VMPET) a metalized film, (PET or PETE) polyethylene terephthalate. (AL) Aluminum Foil – an aluminum foil layer barrier keeps your product fresh for approximately 20 months, compared to 13 months when metalized (VMPET) barrier film is used. Aluminum foil film has a much higher end appearance and offers better protection. Copious Bags? uses only aluminum foil to line our bags, never metalized. (VMPET) – a metalized film often used in lower quality packaging. Although it does offer barrier protection, this cheaper material does not offer the long-term protection that aluminum foil does. This metalized film has a metallically appearance and is not very appealing to the customers when the bags are opened.(PET OR PETE) – a thermoplastic polymer resin of the polyester family that's used in packaging for food and beverages, personal care products, and many other consumer products. The INNER layer The inner layer a stand up pouch is extremely important, especially when using them for food packaging. The inner lining is the material that comes into direct contact with your product. The most common material used for stand up pouches is (LLDPE) linear low-density polyethylene. This material is used widely throughout the packaging industry because it is FDA approved and is safe for direct contact with food. The inner layer is also what makes Copious Bags? stand up pouches heat sealable. Heat sealing your bags gives your product a tamper-evident seal, thereby giving your customer the confidence and assurance that the product has not been opened or tampered with. The GUSSETED bottom The expandable bottom gusset is what gives a stand up pouch the ability to stand freely on its own. Copious Bag? stand up gusset bags have a very sturdy, u-shaped gusseted which allows the pouch to stand prominently without collapsing. Make the TRANSITION The stand up pouch is dominating the packaging world. Top brands are transitioning from traditional rigid packaging such as jars, canisters, tins, and boxes to the flexible stand up pouch. The bags are stored flat whereby saving valuable retail space. And, because they are extremely lightweight, companies are saving a ton in shipping and freight costs. STAND UP POUCHES ARE VISUALLY APPEALING: Stand up pouches give you the option to really get creative with your packaging design. Unlike a static label, you can personalise the entire pouch from top to sides and back. This enables you to lay out the font, graphics, and colours in a way that reflects your brand and helps you stand out from the crowd. This way, no matter which way the pouch is displayed, customers will unmistakably recognise your product.   STAND UP POUCHES KEEP YOUR PRODUCT FRESHER FOR LONGER: By fitting out your stand up pouch with a resealable zip lock, up to three layers of protection (so as to keep out moisture, UV light, oxygen, and external odours), and a gusset on the bottom – your products will stay fresher for longer, while giving your customers the freedom to consume at their own pace. If you're packaging coffee, the inclusion of a degas valve will help release oxygen while preserving the flavour-enhancing gases. Thus, ensuring the beans maintain their freshness and last longer.   STAND UP POUCHES ARE LIGHTWEIGHT AND FLEXIBLE: Want your customers to enjoy your product on the go? This is one of the greatest benefits of stand up pouches for food packaging. Flexible packaging is typically made from plastic or paper, which is considerably lighter than glass and cardboard boxes. So, whether your customers are heading to work, on holiday, or just lounging about at home – your customers can enjoy your goods any time they like. Furthermore, since the packaging is less rigid, it takes up far less space. So it can be stored in small compartments,central seal bag, lockers, and small pantries. Again, even greater convenience for your customers!   IDEAL FOR A VARIETY OF PRODUCTS: Whether you produce confectionary, baking goods, coffee, small toys, or snacks, it doesn't matter. Stand up pouches are flexible enough to store a wide range of products from a variety of industries. So, even if you currently rely on glass or cardboard packaging, depending on the type of product you sell, there's a good chance you can make the switch to lightweight flexible packaging. You may be surprised at how economical, affordable, and user-friendly your new packaging will be. Best of all? It doesn't cost you much to do a trial test run. At The Pouch Shop, we have a low minimum order amount for all our pouches, which enables you to print a variety of test designs and help you decide whether to proceed. This way, you avoid the risk of producing a large batch that doesn't quite meet your needs, thus you save time and money. Our selection of Kraft pouches will help you choose the right paper pouch packaging to communicate eco-friendly values of your brand and to deliver the highest quality products to your customers. Kraft paper is durable, resistant to tearing and offers good protective properties. It blocks the UV light and humidity, which helps to ensure the freshness of your products by preventing oxidation and other undesirable chemical reactions that would lead to deterioration of your goods. Kraft paper stand up pouches are also decidedly eco-friendly. They require less materials and less energy in their production and leave less waste in the manufacturing process. Due to being very light and compact, they are also very easy to transport and store. We offer classic Kraft stand up pouches, as well flat bottom bag and various other designs of Kraft paper pouches. We also have pouches made partially of Kraft paper but incorporating a window or a whole clear side which allows the consumer to see exactly what they are buying while that product remains sealed for freshness and protected. Various designs available in our store also include Kraft resealable pouches such as Kraft zipper pouch bag. For extra protection, we have pouches that combine aluminium foil with Kraft paper. Such construction ensures the strongest protection and durability, without sacrificing the classic, traditional look of the 3 side seal bag.

Fecha de Publicación: 13-10-21

A review on RO membrane technology: Developments and challenges

Descripción: A review on RO membrane technology: Developments and challenges Reverse osmosis (RO) based desalination is one of the most important and widely recognized technologies for production of fresh water from saline water. Since its conception and initiation, a significant development has been witnessed in this technology w.r.t. materials, synthesis techniques, modification and modules over the last few decades. The working of a RO plant inclusive of the pretreatment and post-treatment procedures has been briefly discussed in the article. The main objective of this review is to highlight the historical milestones achieved in RO technology in terms of membrane performance, the developments seen over the last few years and the challenges perceived. The material properties of the membrane dominate the performance of a RO process. The emergence of nano-technology and biomimetic RO membranes as the futuristic tools is capable of revolutionizing the entire RO process. Hence the development of nano-structured membranes involving thin film nano-composite membranes, carbon-nanotube membranes and aquaporin-based membranes has been focussed in detail. The problems associated with a RO process such as scaling, brine disposal and boron removal are briefed and the measures adopted to address the same have been discussed. In response to the escalating world water demand and aiming to promote equal opportunities, reverse osmosis desalination has been widely implemented. Desalination is however constantly subjected to fouling and scaling which increase the cost of desalination by increasing the differential pressure of the membrane and reducing the permeate flux. A bench-scale desalination equipment has been used in this research to investigate the mitigation of fouling and scaling. This study involved the performance of membrane autopsy for fouling characterisation with special attention to flux decline due to sulphate precipitation and biofouling. Visual inspection, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and microbiology tests (API) were performed. Results obtained showed the presence of diatoms, pseudomonas and polysaccharides as the main foulants causing biofouling. Analysis revealed sulphate deposits as well as aluminium, calcium and silica as the main elements contributing to inorganic scaling. Findings pointed out that the pre-treatment system of the small-scale reverse osmosis water treatment was inefficient and that selection of pre-treatment chemicals should be based on its compatibility with the membrane structure. The importance of characterisation for the verification of fouling mechanisms is emphasised. This research was conducted to determine the performance of Reverse Osmosis (RO) membranes in producing pure water, pure water known as mineral-free water or water with zero dissolved solids (TDS = 0 ppm).PDAM (Regional Drinking Water Company) Tirta Musi in Palembang, South Sumatra and water from the Micro Filtration (MF) and Ultrafiltration (UF) processes are fed to the RO process using two feeding methods, namely a single pass and a circulation feed. In a single pass feed, the operating pressure is set at 20 - 50 Psig, where an increase in the product rate and the rejection rate so that the flux increases. Rejection of TDS obtained increased from 96.6% - 97.5%. Furthermore, the circulating feed system with a constant pressure of 50 Psig decreases TDS and Conductivity. Rejection of TDS 96.1% for PDAM water feed and Rejection of TDS for feed water from MF&UF 97.3% in subsequent feedings there was a decrease in TDS and conductivity but not significantly. The purified water produced has a TDS content of 0.16 - 0.48 ppm, a conductivity of 0.17 - 0.49 μs/cm, a pH of 6.99 - 7.2 and a resistivity of 177 - 185 kΩ, the characteristics of this pure water are according to the standard pure water in ASTM D1193 - 99e1 and NCCLS. Clean water obtained by desalinating sea water or by purifying wastewater, constitutes a major technological objective in the so-called water century. In this work, a high-performance reverse osmosis (RO) composite thin membrane using multi-walled carbon nanotubes (MWCNT) and aromatic polyamide (PA), was successfully prepared by interfacial polymerization. The effect of MWCNT on the chlorine resistance, antifouling and desalination performances of the nanocomposite membranes were studied. We found that a suitable amount of MWCNT in PA, 15.5 wt.%, not only improves the membrane performance in terms of flow and antifouling, but also inhibits the chlorine degradation on these membranes. Therefore, the present results clearly establish a solid foundation towards more efficient large-scale water desalination and other water treatment processes. Introduction The availability of clean water has become a global problem because of the continuously increasing costs of energy and increasing scarcity of water resources1. This problem has been exacerbated in recent years in the so-called century of water. By far, the domestic ro membrane process persists as the most reliable and cost-effective water desalination technique and numerous large-scale RO plants have been constructed around the world2,3. A wide range of polymers have shown potential for fabricating desalination membranes to be used in RO4. However, PA-based membranes tend to exhibit the best performance in terms of selectivity, flow, chemical stability and ease of large-scale fabrication. PA membrane technology was developed in the mid-70?s and has become the commercial benchmark in RO membranes5. In order to improve the membrane performances, the recent trend in polymer-based membrane research has been to investigate various types of nanocomposite films as an active layer of RO membrane, so-called nanocomposite membranes, in which these films are fabricated using a nanosized filler such as MWCNT, graphene, graphene oxide, silica, or zeolite6. In this regard, MWCNT·PA-based membranes have been prepared by several groups and in general, these membranes have exhibited some level of improved performance7,8,9,10,11,12. The advantages claimed for these membranes range from increased salt rejection, large fluxes, greater durability and even antimicrobial properties. MWCNT synthesized by catalytic chemical vapour deposition13,14 have been widely studied due to their fascinating chemical and physical properties and among all nanocarbon materials, they can be mass-produced for commercially available applications, such as the electrode additives in high performance lithium ion batteries15. Interestingly, while the structure of the fully aromatic PA-based commercial ro membrane derived from m-phenylendiamine (MPD)-trimesoyl chloride (TMC) is constrained due to its stoichiometry; the addition of MWCNT can significantly vary their performance due to their unique features such as dispersability diameter, length, straightness and chemical functionalities, among many others. Therefore, although these past reports acknowledge the key role of MWCNT in aromatic PA nanocomposite membranes, still little attention has been devoted to the mechanisms related to the improvement of flow rate, selectivity and chlorine tolerance2. Carbon nanotubes inducing chlorine tolerance are particularly interesting because chlorine sensitivity has been recognized as a major drawback of PA-based RO membranes16,17. During long-term operation, chlorine is often added as a pre-treatment to reduce algae biofouling18 and is particularly needed for drinking water purification. Moreover, high-concentration short-term exposure to chlorine is also common during domestic nf membrane backwashing. For these reasons, several studies have been carried out and the degradation mechanism of aromatic PA membranes during chlorine exposure is relatively well-known19,20. Recently, our group demonstrated that the addition of MWCNT to rubber can considerably reduce the chlorine-induced degradation of the polymer matrix21. Although the degradation mechanism of rubber by chlorine is different from that of PA, particularly due to the lack of hydrolysis, covalent chlorination is a common problem for both polyamide and rubber. For rubber, we found that MWCNT effectively restricted the adsorption of chlorine within the polymer matrix, thus resulting in a limited exposure of the polymer to this reactive reagent and thereby decreasing the oxidative degradation. For these reasons, we believe MWCNT are not only promising composite fillers with chlorine protective properties, but might also help to provide mechanical robustness to PA-based RO membranes. Results and Discussion We prepared aromatic PA membranes using a support consisting of a porous polysulfone layer deposited on a polypropylene nonwoven. These support membranes were soaked sequentially in MPD and TMC solutions, to synthesize the aromatic PA membrane by interfacial polymerization. In order to incorporate MWCNT into the PA membrane, an anionically stabilized dispersion of MWCNT (Supplementary Fig. S1) was mixed with the MPD solution and the synthesis was conducted similarly. Figure 1a shows an image of the resulting membranes, with and without MWCNT. The black color developed in the membrane prepared using surfactant dispersed MWCNT is characteristic of the high carbon nanotube content of the present membrane (Fig. 1a). Thermogravimetry of the active layer (Supplementary Fig. S2) of the black color membrane indicates that it contains ca. 15.5 wt. % of MWCNT, which is at least 150 times higher than previously reported MWCNT-filled RO PA membranes7,8,12. The SEM image showing the surface morphology of the membrane is typical for the interfacial PA polymerization22, consisting of the multi-layered ridge-and-valley (Fig. 1b); the morphology of this membrane clearly changed after the addition of MWCNT (Fig. 1c). The thickness of the membranes was measured using SEM (Supplementary Fig. S3). The addition of MWCNT did not modify the thickness of the active layer and both samples were approximately 100?nm thick. However, water contact angle measurements showed a slight increase in wettability upon addition of MWCNT to the PA membrane (Supplementary Fig. S4). Notably, no MWCNT were visible on the surface, thus indicating that they were perfectly embedded within the PA matrix, a key factor needed for avoiding MWCNT leakage during operation. Flow permeation rates, as indicated below and SEM images confirmed that the membranes can be produced pinhole-free in a reproducible way. After the membrane was dried for SEM studies, cracks were generated by manual deformation of the membrane (Fig. 1d) and MWCNT embedded, parallel along the membrane surface, were observed bridging the fracture within the polymer matrix. The apparent diameter of these nanotubes are ca. 20?nm, which is about two times larger than the pristine nanotubes (Fig. S1a). These facts suggest that the nanotubes must be coated with polymer to achieve a good matrix-nanotube adhesion. In order to support our proposed structure consisting of a polymeric network with aromatic moieties in parallel arrangement to the MWCNT walls, we performed theoretical simulations of the monomer molecules orientation in the vicinity of a carbon nanotube surface, see Supplementary Fig. S5. Here, four different cases, consisting of two geometrical configurations, are demonstrated: horizontal and vertical alignments with respect to the MWCNT surface (modelled as a graphene surface), for both monomers (MPD and TMC). The results indicate a clear energetic preference for the horizontal arrangements of these molecules interacting with sp2 hybridized carbon networks; these preferences are related to π-π stacking and are known to be common for aromatic compounds on sp2 hybridized carbon surfaces. Similarly, Fig. S5b shows a simulation of 50 MPD molecules absorbed on a graphene surface and it can be seen that the molecules adopt a similar geometrical orientation after relaxation (Fig. S5c). In order to rule out curvature effects, we carried the simulations using a (10,10) single-walled carbon nanotube (Fig. S5d), which evidently has a higher curvature than the 10?nm diameter MWCNT experimentally used in the membrane fabrication. It can be seen on Fig. S5e that after relaxation, the aromatic ring of the MPD molecules lies parallel to the carbon nanotube surface. We confirmed the strong affinity of MPD with MWCNT by filtering the solution and carrying out UV-Vis spectroscopy. We found that 16.7% of the MPD monomer remained attached to the MWCNT. These MPD functionalized MWCNT were polymerized in TMC solution. Supplementary Fig. S6a shows a homogeneous PA coating on the MWCNT. Supplementary Fig. S6b depicts a higher resolution image showing a coating of about 5?nm thick on the MWCNT surface. We used fast Fourier transformation (FFT) of the HRTEM images to analyze the orientation of the PA network and it is clear that PA regions that do not contain MWCNT, show an anisotropic molecular arranged structure (Supplementary Fig. S6c), whereas the PA coating the nanotubes show a preferential orientation of PA molecules along the MWCNT surface (Supplementary Fig. S6d). These experiments strongly support a templating effect caused by MWCNT. To assess the distribution of the MWCNT within the membrane, a Raman mapping of the characteristic D- and G- bands of MWCNT was conducted (see Fig. 1e,f). Through all the studied areas only the D- and G- peaks could be observed, indicating a homogenous mixture and a high content of MWCNT, which is not common in these type of nanocomposites, because the MWCNT are prone to aggregation even when loading at low concentrations. Commercial NF membrane exhibited a lower contact angle; however in this case, the presence of wetting additives or a surface treatment is likely responsible for this phenomena. The method used to synthesize the MWCNT·PA nanocomposite relies on the transport of the MWCNT to the organic/aqueous interface during polymerization23. Indeed, the presence of a limited amount of anionic surfactant has been recently reported to improve PA membrane formation, resulting in better performance24. This is most likely due to a reduction of the oil/water interfacial tension, a process that in our case is also promoted by the small amount of surfactant that provides amphiphilicity to the nanotubes It is important to emphasize that we did not used covalent functionalization of MWCNT, in contrast to some previous reports8,11.

Fecha de Publicación: 13-10-21

Operator Essentials

Descripción: Operator Essentials You've heard the term before; tactical backpack.  It's hard to avoid, in fact.  It's impossible to deny that "tactical" packs are a trend that isn't going away any time soon in the carry world.  In fact, at this point it may not even be a trend, but one of the pillar groups.  How did this happen?  Well, as long as there has been military, there have been people who want to use the gear for their civilian lives (the common day tshirt is a perfect example of gear popularized by military design and use).  And just to be clear, civilians using military gear is awesome.  As long as you're not going around claiming you're a soldier when you're not.  That's not cool.  Otherwise, feel free to enjoy the benefits of these awesome packs and gear.  In one way or another, you've already paid for them via taxes! People are drawn to this rugged gear for good reason too.  Packs, clothing, and kit that is designed specifically for armed forces are all meant to go to war.  Literally.  They're focused on strength, durability, modularity, high activity, and premium quality materials/hardware.  Fashion is not even considered.  It's all pure function here.  That being said, some may think tactical packs are a bit loud/attention grabbing, so they'll want something a bit more subdued.  Everyone has their own preferences, which we dig. Long story short, in this particular case the term "tactical" is essentially another word for "military" or "military inspired". As the title states, this is a breakdown of tactical thigh bag for beginners.  An introduction.  So let's dig in and explore what makes one functional tactical pack great versus a cheap knock-off for fashion's sake. We're material geeks over here.  And generally military tactical packs all should be made from quality fabrics that can take a beating.  As a general rule of thumb, they should be made from 500D – 1200D CORDURA nylon fabric (or better).  Not 200D.  Not Kodra.  Not polyester.  This is an easy one.  Some packs may even use nicer materials, such as X-Pac (VX) fabric.  Usually these fabrics are heavier (not always), but they're weather resistant and take a fall down a mountain or twenty. Zippers/Hardware: Look for brand names listed in the pack's specifications.  Brands to look for are YKK, TiZip, ITW Nexus, AustriAlpin, and more.  If you haven't heard of the brand (or if it's intentionally left off), it probably doesn't have a reputation of having a great track record.  These parts can make or break (literally) a pack, so you'll want something you can trust.  If you're deep in the wilderness and a buckle that keeps your shoulder straps attached busts on you, you're out of luck. Whether you're looking for a bag for day hiking or an everyday go-everywhere pack, the right tactical backpack offers a perfect combination of ample storage, practical features, and all-day comfort. It's simple. If you're going to be spending a lot of time wearing a backpack, choose a reliable one. Unlike many other backpack categories, tactical backpacks offer lots of utility for a wide variety of activities including long hikes, military deployment, traveling, and cycling. Good tactical backpacks have numerous pockets, compartments, and clever features. Features to look for include external ports for nozzles and headphones, hydration bladder compatibility, two-way radio holders, compartments for medical supplies, and more. Furthermore, all-weather capability and durable materials define the characteristics of high-quality tactical backpacks. For both professional and recreational applications, tactical vest offer carefully structured layouts that carry comfortably and keep gear secure, even when packed with heavy loads. We've examined and reviewed options from across the tactical backpack market and determined which packs rank among the best in 2021. Scroll through our list to view our picks, or jump ahead to the specific category that you're interested in. This 27L pack from Mystery Ranch is one of the most versatile tactical packs on the market in 2021. Thanks to its lightweight profile and compact size, the 2-Day Assault Pack ($200) is the perfect choice for a weekend of camping when you don't want to lug around a full-size backpacking pack. Firstly, it's both comfortable and secure on your back, thanks to removable hip straps and shoulder straps. And second, at just 3 pounds, it won't weigh you down while hiking. For professional and urban use, an integrated and padded laptop sleeve and robust YKK zippers add impressive multiuse utility. For water storage, the 2-Day Assault Pack is compatible with water bladders. Each pack also includes dual water bottle holders. We love that this pack is made from hardy material. Its premium 500-denier Cordura fabric is field-tested and built to last. For quick overnight adventures or practical everyday use, the 2-Day Assault Pack from Mystery Ranch offers great features and overall value at $200. A backpack is a bag for holding things. It's hard to make that tactical, since one bag is very like another. When discussing turning a piece luggage into a lean, combat-equipped fighter, the first question that must be answered is: How? It's a simple matter to put a few MOLLE straps onto a rucksack and call it battle-ready, but that does not fit the bill. True tactical packs are build with missions in mind, giving operators a lot of customization of the inside depending on if they're doing recon, hunter/killer missions, sabotage, or simply going on a day hike. Real tactical suits also step up the durability to the point that they're nigh indestructible, and are replete with hidden stash spots for secreting away a weapon, a jump drive with the Death Star plans, or a message to the wetwork pro who will find your body. Finding the level of flexibility and resiliency that a tac-op bag should have can take a lot of digging, and if you're serious about needing it, your life could be put in jeopardy should you pick a pretender. Don't gamble with your blood, sweat, and more blood. Take one of the 16 top tactical backpacks and get to work. If your spouse just brought one of these home, get ready for them to leave you, because this is a serious bag for serious people who are seriously never coming back. Though you can go bigger than the 2,100 cubic centimeters, it's the webbing and handles atop, around, down, and under this bag that make it clear it's just the base. The triple straps are the tale here, giving adjustable relief that makes this bearable for hours of trail wear. Though not as traditionally "tactical" as the other options here, the Recon is a smart backpack in that it uses tactical elements to create a good day pack that is cost efficient and doesn't have the miles of MOLLE or extra features that average tac-pack users don't actually need. If you aren't headed for a survival mission but would like some 210 Denier Cordura in a slick, sleek, go to the end of the world bag that's dressed down and modern, here's how to do it up right.  7 compartments intended to carry every survival item you require for living out of this for 3 solid days, this is the bug out bag serious survivalists suggest. More than 3,000 cubic inches of space inside outfitted with sleeves for hydration bladders, D-rings for expansion and extension packs, and it has a deep foam back panel for both support and ventilation that guards against sweaty-back syndrome. Ooh-Rah or bust.  Going in an asymmetrical direction, the Javelin looks a little awkward at first, but the design is intended to land at your body's natural load-bearing points for an even distribution across your entire back to prevent walking cock-eyed. Built with 1000 Denier cordura and neoprene handles, the large number of small compartments makes this a good field bag for medical, electrical, demolition, or photography work. Top or side access gives it a convertibility that's welcome in a tactical bag.  We can't force Snugpak to change their name, but it's on our To Do list. In spite of the cutesy label, this is a serious sack for people with serious sack. It's only 1,400 grams, having been made for rangers who must move quickly across varied terrain. Unlike most tactical backpacks, this is made for keeping your survival essentials only, which is why it has a huge central compartment, but few pockets for organization. The huge range of MOLLE straps all over this bag are where you do your organizing.  Though not traditionally a backpack, the Plan-B's cross-body build allows for quick access from the left or right, which adds field facility, even if it breaks from the mold a bit. 1080 cubic inches worth of gear storage, webbing from tip to tail, and an integrated system that can work with your favorite water bag, this can make a traditionalist into a sling-bag convert.  You'll never go wrong carrying a Maxpedition, so it's buyer's pick. We prefer the Falcon-II because it uses a Y-shaped compression strap in the middle, unique to its design. Using that seems to distribute weight more evenly, keeps parcels in place during serious action, such as taking a tumble down a ravine slope, and makes the carrying feel incredible. That's to say nothing of the side-buckles, dual-open zippers for clamshell storage and easy access, as well as the 1050 Denier build. Whew, it's a piece of work.  Weight concerns brought the Dragon Egg from it's original design, which called for 1000 Denier Cordura was downgraded to 500-D, because this bag needed to be light as gossamer to achieve its goal. The balance of the 500-D means a tad less rip resistance – though you'll be hard-pressed to notice it – but far less weight than many similar bags. This mixture creates a capacity of 1,500 cubic inches that can be carried by smaller soldiers comfortably. You'll never stray far from quality with 5.11's tactical belt. Though their Rush line gets more attention, the more basic All Hazards Prime has a straighter build. Constructed using input from MACTAC (Multi-Assault Counter-Terrorism Action Capabilities) instructors, the layout is made specifically to give you access to all your gear, and keep it precisely where you expect it to be. Should you drop something, hi-vis orange lining makes it pop out, day or night. 

Fecha de Publicación: 13-10-21

Building efficiency begins with lighting design and controls in step with the space

Descripción: Building efficiency begins with lighting design and controls in step with the space At the surface level, lighting is the application of light to spaces and simply serves as a prerequisite for visualization. However, because our impression of a space happens via sight, commercial lighting not only becomes a necessity for vision but a medium for perception. This means the type of lighting fixtures selected, in what location they are installed, and at what light levels they are set can drastically impact people's perception of a building and the work being done within it. At this point in LED technology development, there is no shortage of literature on the many benefits of LED highbay light. Objectives of LED lighting increasing comfort in spaces, boosting morale, and reducing energy waste have been well documented and the evidence in favor of LED solutions over outdated fixture types is overwhelming. With the maturity of the LED market and reduction in product costs that aid in generating competitive return on investment (ROI), there is no argument against the investment. However, a successful LED lighting project lies at the intersection of design, product selection, and the fundamental client necessity for light in a space. The lighting designer/specifier or installer needs to clearly align the objectives and the value of each criterion considered for the space in collaboration with the facilities manager or building owner. Designing solutions to fit the space At the core of every lighting project is the solutions design. True to the title, LED panel light design is the process of delivering the necessary lighting to an area, but to better expatiate on the importance of the job, it is important to differentiate between the commodity of "light" versus the asset of "lighting." Lighting is an investment that can be very advantageous to an organization and should be carefully considered. Every project starts with a conversation about necessity. In order for the lighting to best support the client's goals, project managers and designers need to know the organization, who will be using the space and their lighting needs, characteristics of the building, importance of energy efficiency and budget, restrictions based on geographical location, and much more. Based on what the owner wants to communicate through lighting, decisions on quantity of light, color quality, brightness, and direction can be determined. The importance of an open dialogue between a building owner and the project manager cannot be stressed enough. Lighting designs cater to the building and work being done which in turn leads every project to a custom solution in terms of size, style, and programmatic requirements. In addition to discussion, it is beneficial for a facility to take advantage of audits in which experts can determine the heavier traffic areas of the building and select the fixture types that would be most advantageous. With proper identification of LED opportunities for retrofits and thoughtful coordination of the building systems, solutions can be designed with consideration to specific needs. For example, spaces without access to natural sunlight, such as warehouses and mechanical shops, may place importance on implementing LEDs with color temperatures that mimic daylight and allow for circadian stimulus. Advantages like this — which can only be gained through the creation of custom LED design — are leveraged to create an environment that is more sustainable, flexible, and enhances the experience of inhabitants while still meeting safety and visibility requirements. Product specification Design works in concurrence with product selection, or specification. While considering the more human-centric aspects of lighting needs, it is also critical to assess the quality of the product, longevity, and controllability. Is there a chance the space may change over time? If so, how will the lighting demonstrate flexibility and ability to augment? To reiterate, deploying LED solutions is an investment, so it is important that the lighting fixtures both fit the logistical needs of the building and abide despite future changes. Incorporating these considerations into a lighting design will not hinder finding the perfect fit, either. Due to the advancement in LED technology, clients are able to select from a wide variety of LED products, but must make sure to prioritize the appropriate light levels for their building. Ample lighting in an office space, for example, keeps employees alert and the higher visibility allows them to yield accurate results. If the space is underlit, it may have adverse effects on productivity, health, motivation, and even employee retention. Light levels that are too high prove to be just as bad and consume unnecessary energy. Successful lighting design and product selection takes efficiency into account to best make a building sustainable while maintaining an attractive ROI. This can be done by investing in LED light fixtures with higher lumens per watt that provide sufficient light while consuming less energy. For the slightly higher initial cost of efficient LED lighting, organizations can save significantly in the long run through decreased maintenance costs, lower utility bills, and utility incentive programs intended to help offset the initial installation cost of such solutions. As established, lighting plays a critical role in how a space is perceived. However, lighting decisions can influence performance, mood, morale, safety, security, decisions, and actions as well. Lighting design and product selection allows for optimal lighting depending on the goal of the building and people within. For example, fixtures with low color temperatures, which are considered warm and relaxing, may be specified for homes and restaurants where the goal is to feel at ease and there is generally no reason to be on high alert. The same fixtures would not be suitable for a commercial and industrial (C&I) environment since the effect from the lights would be counterproductive. Instead, the fixtures in C&I settings are often designed with high color temperatures that can increase awareness and energize. These spaces rely heavily on visibility in order to perform high-precision manufacturing tasks. LED flood light in spaces in which people are expected to concentrate for long periods of time, such as classrooms and offices, are typically designed to have a neutral color temperature so as not to be over- or under-stimulating. When it comes to specifics like a warehouse facility or a laboratory, they differ quite a bit. There are many aspects of the two workspaces that contribute to the lighting choices. For example, the core differentiating features of a warehouse facility is overall building design, ceiling height, and loading capability. Warehouses are also the largest industrial real estate category, which sets it apart in terms of number of fixtures and light levels. To maximize space utilization, most warehouses employ rows of tall shelving, which results in narrow aisles that are challenging to light, with a "cavernous" effect. In designing a lighting solution, the top priority is visibility as it correlates to employee morale, productivity, and reduction in error, which in turn decreases cost. While working with precision and delicate materials in a laboratory, visibility is paramount but for different tasks and in a completely different environment. Lighting for a laboratory would be designed to be extremely bright for the essential work as well as to contribute to the perception of cleanliness and making the space look sterile. Even if two light sources have the same correlated color temperature, the color rendering index (CRI), which is used to describe how faithfully the light source renders the color of objects, may still differ. CRI is especially important when designing lighting for places such as grocery stores and other retail locations where the product appearance greatly influences the business. The same strong light in a retail store that favorably accentuates the merchandise and influences customers to purchase more may be fatiguing in an office space. Controls are key to lighting success Controls are paramount when discussing LED canopy light design and product selection. Lighting controls are integrated, programmable systems that allow fixtures to deliver the correct levels of light at the correct time to best maximize efficiency. They can practically be broken down into levels that allow options for managing lighting systems. The first level can be described as relying on manual adjustment in which users can manage individual programmed occupancy sensors or non-programmable ceiling sensors. On this basic tier of controls, there is no ability to control lighting levels beyond a simple wall dimmer switch. Tier two allows for wireless integration directly from the fixture to a device. This level of controls can include sensors that have the capability to identify occupancy and vacancy of rooms and change levels based on select settings. In other words, unoccupied rooms will reduce light levels by a certain amount to conserve energy. The second level of controls also allow for high-end trimming or output adjustment of lights. Since LED fixtures typically produce higher lumen output than the fixtures they replace, the fixture output can be raised to match the standard needs for the space. Along with this, the trim can account for the LED's degradation over time and provide the originally desired light level. The low-end trim defines the lowest light level and ensures that the lights do not turn off when dimmed to the lowest capability. This is important for datacenter facilities, for example, as they contain rows of equipment that can obscure a person from motion sensor control. If the system goes into an unoccupied mode, the trim prevents all the lights from turning off and creating a safety hazard. The design may include that the trim be 10%, which would provide visibility even if the sensors are obscured and the lights are not at the optimal levels. Additionally, datacenters often control lighting by grouping fixtures and programming different sets based on various needs by using individual auxiliary sensors. This allows for control concurrency and can be regrouped depending on the layout of the space. The highest level of controls includes all the benefits mentioned previously in the second level, with the added benefit of being integrated directly into the building management system. In other words, a building manager could potentially have its HVAC system respond in direct relation to the occupancy sensor used for the LED lighting system, which would provide much more granular control of the building's total mechanical system. Depending on what is needed in the space, controls can be used as a powerful means to customize lighting further than initial product selection and installations.

Fecha de Publicación: 13-10-21

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