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Can Liquid Nails Bond Wood To Metal?

Descripción: Can Liquid Nails Bond Wood To Metal?     It’s a common household problem. However, you have another problem. You have a wooden bathroom door and a metal knob. What’s the quickest way to reattach the two surfaces? Can you trust your tube of liquid nails to do the job?     Liquid Nails can bond wood to metal. You can use some variations of liquid nails in construction projects and home improvement projects to bond wood and metal. They have a potent formula that performs in all weather conditions.      Adhesives are a fast and easy solution to most household and construction projects. Most times, you need to bond similar items such as wood on wood or plastics. In other cases, you are faced with the task of joining different surfaces together.      We look at whether liquid nails, a polyurethane adhesive, sticks to their word in a market awash with adhesives. Let’s find out if liquid nails heavy duty can bond wood to metal.      "Liquid Nails" (Liquid Nails) - construction adhesive, which is suitable for connecting all sorts of things by gluing. It is so called because when it is used, parts and surfaces are very firmly glued to each other, as if nails are connected. "Liquid nails" are a mixture of polymers and rubber. They are supplied to the market in the form of tubes of various capacities from 200 to 900 ml. For ease of application and uniform dosing, experts recommend using a construction pistol. How to choose it correctly, and what to look for, will be discussed in the article.     Rechargeable devices are good for their autonomy. They function with a Li-Ion battery. Thanks to the handle, the output of the adhesive is provided, and its speed can also be adjusted - the harder you press, the more glue comes out. The only negative is that you often need to charge the battery or change batteries.     Electric gun It differs from the wireless analogue only in the absence of a battery. The rest of the functionality is the same. Apply them an adhesive substance is obtained quickly and economically. Usually such devices are used by specialists. There is a lot of such a unit, so for use in the home, when there is no large scope of work, the purchase is inappropriate. Insert the composition into the gun is also quite difficult.     If Liquid Nails has bonded to your drywall and you want to remove it, apply heat or a solvent before scraping. This process will make removal easier and reduce damage to the drywall surface. Use a heat gun to soften the Liquid Nails or apply mineral spirits, petroleum jelly, or a similar compound to the dried adhesive. Once the Liquid Nail Glue has softened, scrape it off your drywall. If there is any damage after removal, patch your drywall with joint compound before painting.     Liquid Nails and other construction adhesives won’t irreparably ruin drywall. Construction adhesives bond to the drywall’s paper surface but will not penetrate any deeper than the surface. This means that if you use the right methods to remove Liquid Nails, the damage will be minimal.     Liquid Nails won’t ruin drywall because it only bonds to the paper surface of drywall.     If you’ve removed paneling or a wall fixture that was secured to drywall with Liquid Nails, you’ll probably be left with a bumpy residue of adhesive that won’t budge. Don’t panic. You can get rid of the adhesive and make your walls beautiful again. Just try these techniques.     Heat Gun or Blow Dryer     In many cases, heat will return hardened Liquid Nails to a softer consistency. Use a construction-grade heat gun or a blow dryer to heat the Liquid Nails. Once it begins to change to a putty-like consistency, use a scraper or putty knife to peel the Liquid Nails from your drywall slowly.     Use this heat gun or a blow dryer to heat up the dried Liquid Nails.     As the Liquid Nails changes to a putty-like consistency, use a scraper to remove it from your drywall. These heat tools are safe to use with drywall and will not cause damage to your walls.     This method is safe to use because drywall is very heat-resistant. The water in gypsum remains in an unevaporated state until temperatures reach 176°F (80°C). Only at temperatures above this point will the water begin to evaporate, increasing the chance of damage to the drywall. You can thus use a heat gun or blow dryer to heat residual construction adhesive without posing a threat to your drywall.     Changing your stair treads is a small but powerful way to update your home. With all the construction adhesives on the market, the household name of liquid nails for flooring comes to mind first, but is it suitable for stair treads? We’ve taken a look into the inner workings of adhesives to find out for you! Liquid Nails’ brand name is not the first recommended adhesive for stair treads due to its high water content. The higher the moisture levels, the more chances of warping as it dries. A polyurethane glue, such as Loctite PL Premium, is a highly recommended adhesive.     Since the stair treads, or the surface of your stairs, receives a lot of foot traffic, you’ll want to make sure it’s properly installed. We have insider tips and tricks on installing the strongest tread and looking at how to finish them with stains. Keep reading to learn these processes and more!     In particular, Liquid Nails have low VOC but are solvent-based and can cause warping to wood. VOC, or volatile organic compound, is the odor often associated with strong adhesives. The higher the VOC, the more intense the smell, which will require more airflow to reduce breathing it in.     There is also a long curing time to Liquid Nails that can extend your project longer than desired. Liquid Nails can be a good choice for smaller woodworking projects that require a strong bond, but it is better to use a poly construction glue for home improvement. If you only have Liquid Nails available near you, make sure it has low VOC and is not water-based. Then do a test with two pieces of wood to see how it interacts.     To begin, there are four main parts of stairs. The first is the base, known as the stinger. This is the full wooden cut-out board that acts as a ground to lay the treads on. Next are the stairs risers. These are the vertical faces of the stairs that meet the back and then the front of each tread.     Of course, then we have the tread itself, which is the actual stepping surface. Finally, there are the stairs nosing. The nosing is the extra bit of stair tread that over hands above the riser. You can also add a cove molding, which goes over the joint of the riser and tread. It looks similar to adding crown molding to your walls. There are a few extra teams for their build, but these are the main components.     Start by ensuring that the stair tread and sub-tread surfaces, if applicable, are clean of any dust or debris. When working without a stair sub-tread, put globs of glue about 3-4 inches apart on the top of the risers. If there is any glue spillage, you can add a cove molding underneath the treads nosing to hide it, and dress up the stairs. A cove molding is like a skirt underneath the nosing to mask the contact point of the wood.     Subtreads are typically seen on fully closed-in stairs, such as new construction and homes with no basements. They are often made of plywood and are the unfinished version of your staircase. When you have these to work with, you’ll place two rows of quarter-sized globs of adhesive 5-6 inches apart. You’ll want one row in the front and the second towards the back.     Nails are absolutely recommended to use alongside adhesives. While adhesives alone have a strong grip, nails act as a clamping feature to hold the wood to the glue. The pressure from the nails helps reduce the chance of the treads shifting.     Safety is a huge concern when constructing stairs. There is an extra wooden piece that you can add to help strengthen the treads. Known as a glue block, these are 3-4 inch triangular or square parts that go underneath the stairs. You’ll want to install these at any instance wood touches wood.     Glue blocks can be installed with just glue, and often 2 or 3 are placed on the underside where the riser meets the tread. The blocks, along with the staircases skirtboard, should be sealed with a fill caulk. After you put a line down, smooth it out and make sure no small holes appear. Sealing both will help keep moisture out and give the stairs a clean, finished look.     Should I Stain Stair Treads Before Installation?     Yes! Staining your treads before installing them means you’ll be able to see how the stain looks once it drys. You’ll save yourself the headache of trying to restain or remove your new stairs. Also, if you’ve never stained wood before, a good practice run will help you determine how much stain is needed and the best technique to use.     The wood should be totally dry and away from moisture before staining. One of the biggest causes of warping is when the wood planks have different moisture levels throughout. Drier parts of the wood will dry faster after the stain is applied and will tighten at a different rate than the slightly more wet areas.     Along with seeing how the stain will look, for any odd reason, if there is warping, you’ll be able to fit your cut treads again into the stingers to make sure it still fits. Staining is a great way to seal your treads and give them a protective coat against heavy usage.     While liquid nails mirror may not be the first recommendation for installing stair treads, you have other options. Polyurethane adhesives with low VOC will give your stair joints the strength they need. You should use finishing nails alongside an adhesive to act as a pressure hold while the glue dries. Taking time to revamp your staircase will make a huge impact on the quality of your home.

Fecha de Publicación: 17-09-21

Basic electrical quantities: current, voltage, power

Descripción:   Basic electrical quantities: current, voltage, power     Voltage and current are the cornerstone concepts in electricity. We will create our first mental models for these basic electrical quantities. We will also talk about power, which is what happens when voltage and current act together.     The concept of electricity arises from an observation of nature. We observe a force between objects, that, like gravity, acts at a distance. The source of this force has been given the name charge. A very noticeable thing about electric force is that it is large, far greater than the force of gravity. Unlike gravity, however, there are two types of electric charge. Opposite types of charge attract, and like types of charge repel. Gravity has only one type: it only attracts, never repels.     Conductors are made of atoms whose outer, or valence, electrons have relatively weak bonds to their nuclei, as shown in this fanciful image of a copper atom. When a bunch of metal atoms are together, they gladly share their outer electrons with each other, creating a "swarm" of electrons not associated with a particular nucleus. A very small electric force can make the electron swarm move. Copper, gold, silver, and aluminum are good conductors. So is saltwater.     There are also poor conductors. Tungsten—a metal used for light bulb filaments—and carbon—in diamond form—are relatively poor conductors because their electrons are less prone to move.     Insulators are materials whose outer electrons are tightly bound to their nuclei. Modest electric forces are not able to pull these electrons free. When an electric force is applied, the electron clouds around the atom stretch and deform in response to the force, but the electrons do not depart. Glass, plastic, stone, and air are insulators. Even for insulators, though, electric force can always be turned up high enough to rip electrons away—this is called breakdown. That's what is happening to air molecules when you see a spark.     Semiconductor materials fall between insulators and conductors. They usually act like insulators, but we can make them act like conductors under certain circumstances. The most well-known semiconductor material is Silicon (atomic number 141414). Our ability to finely control the insulating and conducting properties of silicon allows us to create modern marvels like computers and mobile phones. The atomic-level details of how semiconductor devices work are governed by the theories of quantum mechanics.     The online monitoring equipment installed on the high-voltage power bus is supported by reliable and stable DC power, which cannot be obtained from industrial low-voltage AC power or chemical battery. This paper presents a circuit based on the principle of electromagnetic induction to obtain low-voltage low-power DC power supply from high voltage power supply bus. The circuit consists of energy-acquired coil, the rectifier and regulator circuit, and the shunt coils. This power supply can work with small current in the bus, also it can output stable DC voltage in the case of large current in the bus by starting shunt coil. The experimental data indicates that the output voltage of the power supply are 3.3 V and 5 V, the output power is greater than 120 mW and the bus starting current is less than 5A, all these can suffice for the online monitoring equipment.     With the rapid development of the world’s aerospace technologies, a high-power and high-reliability space high-voltage power supply is significantly required by new generation of applications, including high-power electric propulsion, space welding, deep space exploration, and space solar power stations. However, it is quite difficult for space power supplies to directly achieve high-voltage output from the bus, because of the harshness of the space environment and the performance limitations of existing aerospace-grade electronic components. This paper proposes a high-voltage power supply module design for space welding applications, which outputs 1 kV and 200 W when the input is 100 V. This paper also improves the efficiency of the high-voltage converter with a phase-shifted full-bridge series resonant circuit, then simulates the optimized power module and the electric field distribution of the high-voltage circuit board.     The flexible combination of power supply modules for different space high-voltage applications is a well approach to solve the design problems of space high voltage rectifier block. Power supply modules can solve the problems in performance limitations of aerospace-grade devices in space high-voltage applications, and make it easier to carry out insulation protection. Therefore, space power module is very important in space high-voltage systems.     This paper proposes a space high-voltage power module with high boost ratio and a new improvement module to improve the efficiency.     China is the global test bed for ultra-high voltage (UHV) transmission lines, a technology that can carry electricity across vast distances with much greater efficiency than the high voltage lines that you’re probably used to seeing.     Since 2006, it’s built 19 of these multi-billion-dollar lines, stretching almost 30,000 kilometres and supplying 4% of national electricity demand. For comparison, no other country has a single UHV line in full commercial operation.     But China’s enthusiasm for UHV is waning. The technology is beset by conflicts of interest between grid companies and central and local governments. The lines themselves are underperforming, and more recent projects are coming online amid a period of electricity generation overcapacity.     This means that approvals for new lines have slowed, and grid companies are unlikely to meet their targets for new ones.     Chinese grid companies have pursued Ultra High Voltage projects to solve a logistical dilemma: coal, hydro, wind, and solar resources are concentrated in the interior, but the heaviest energy demand is along the urbanised east coast.     In normal high voltage rectifier assembly, a lot of the power is lost as it’s moved across China’s enormous terrain. The benefit of UHV lines is that they have dramatically reduced losses.     China has deployed two types of UHV line. Direct current (UHVDC) lines suit transmission from A to B over distances of more than 1,000 kilometres; whereas alternating current (UHVAC) lines work better over slightly shorter distances but permit branching links along the way.     Grid companies have been keen adopters, with State Grid, which covers 88% of China’s territory, especially interested. Its 2013-2020 construction plan envisioned six AC and 13 DC lines by 2013, and 10 AC and 27 DC lines by 2020. In Inner Mongolia alone, company officials spoke of 11 lines running from the province’s coal and renewable hotspots by 2020.     But rollouts have slowed, and few analysts expect State Grid will deliver on its 2020 target. In fact, its national UHV backbone scheme, which is the centrepiece of its UHVAC ambitions, looks unlikely to happen anytime soon.     Sparks fly     State Grid’s UHV plans suggested remarkable ambition, but did not always align with those of central and provincial policymakers.     Central officials have clashed with State Grid planners on its backbone scheme, which envisions a lattice of six UHVAC lines to synchronise grids that are currently in State Grid’s territory. But officials worry about nationwide blackouts cascading across these interconnected grids. Analysts suggest that State Grid has shelved the backbone plan for now and is focusing on UHVAC lines within individual grids instead.     Meanwhile, the economic case for new UHVDC lines from the interior has weakened amidst slowing growth in electricity demand.     National demand growth averaged 11.7% from 2003-12 but fell to 4.5% in 2012-17, bottoming out at 0.5% in 2015. This drop has deepened overcapacity in China’s power sector, which according to Bloomberg New Energy Finance was 35% in 2016.     Pervasive overcapacity means less need for new transmission projects.     China’s “Priority Transmission Lines for Air Pollution Prevention”, a scheme announced in 2014 that included the construction of nine UHV lines, is set for completion this year. National Energy Administration (NEA) officials said in December 2017 that this scheme “can satisfy electricity demand for the country’s main power consumption regions before 2020”.     Unsurprisingly, then, approvals for new UHV projects – which take 3-4 years to construct – have been slow, with just one project approved in 2016, and two in 2017.     Local tensions     Certain regional governments targeted for UHV projects have also been sceptical.     Provinces get larger boosts to gross domestic product (GDP), employment, and revenue from building their own power plants rather than importing power from other provinces. Even new lines with central government backing have sometimes failed to get provincial acceptance.     For example, the UHVDC Sichuan Number Four line would take Sichuan hydropower to Jiangxi province, and was singled out for construction in the 13th Five-Year Plan (2016-2020). But as NEA officials noted last autumn, Jiangxi does not want this power. The province is bringing more coal-fired power plants online in 2018 so wants to delay the new line until after 2025. Hubei province is also reluctant to accept long-debated new lines from north-west China.     Disappointing gains     Grid companies have their own reasons for being cautious about new Ultra High Voltage lines. Revenues from these mega-projects depend on the amount of power they can transmit. But utilisation of existing lines has been lower than expected, with non-hydro lines performing particularly badly.     What’s more, the impact of UHV on renewable energy “curtailment” in inland China has also been disappointing, undermining the case for investment. Curtailment refers to energy that never reaches the grid and is wasted, for reasons including a lack of transmission capacity or quotas for coal-power consumption.     China’s UHV lines transmit wind and solar power in combination with coal power, which remains the major electricity source. Nonetheless, even a minority share of UHV transmission capacity can still take sizeable loads of renewables from China’s interior to coastal markets. Backers of UHV lines have jumped on this point when championing the technology.     Yet after a decade of UHV development, renewable curtailment levels remain high, especially in north-western regions. National curtailment rates in 2017 were 12% for wind and 6% for solar, several percentage points below their 2016 peaks. Still, China has room for improvement; in Europe, curtailment rates in countries with high levels of wind-power production have been consistently below 5%.     Analysis by environmental researcher Darrin Magee and geographer Thomas Hennig suggests that in 2015, curtailment in Yunnan reached 95 terawatt hours (TWh) – more than six times the reported rate, and enough to power Portugal and Singapore combined for one year.     Lagging wind and solar     Ultra high voltage multiplier lines successfully transported 172.5 TWh of renewable energy in 2016, or 3.2% of national power consumption. However, 93% of that power came from five lines used for hydropower only.     Some of China’s non-hydro lines have relied less on renewables than supporters had hoped. Caixin Energy reports that, according to experts at State Grid, renewable shares in lines planned to take a coal-renewable mix should target 30%. Three such lines were in operation for at least part of 2016. Their performance was uneven. Ningdong-Zhejiang carried 29% renewables, and the Southern Hami-Zhengzhou line’s share was at 23%, but Ximeng-Jinan took none at all.     The Zhebei-Fuzhou line was framed initially as a vehicle for nuclear and wind consumption but did not take any wind in 2016. Reports are unclear on whether it has since added wind to its power mix – though it has added coal.     It is hoped that these shortfalls will be temporary. One non-hydro UHV line that launched in 2017 has been relying on coal because the renewable projects planned to accompany it faced construction delays. Overall transmission volumes increased significantly for China’s first UHV lines in their initial five years. Several new UHV lines that take renewables have also come online since mid-2016.     But the shrinking space for new UHVDC projects is a persistent concern for Western provinces, where rapid capacity additions in renewable energy has left long-distance transmission infrastructure struggling to keep pace.     Power sector reforms     UHV is certainly not solely to blame for renewable curtailment problems in the interior. They point to a wider set of challenges facing China’s power sector, which are the focus of reform initiatives launched in 2015. These reforms have included some UHV-specific measures. But many hindrances to the development of UHV lines are best addressed through more comprehensive power sector reforms.     These include power trade markets to make it easier for coastal provinces to buy power from the interior (and locally) at short-notice; measures to strengthen the competitive position of long-distance clean energy against local coal plants; and reforms to reduce disputes around grid planning between central government and provinces.     These reforms are at an early stage. But while enthusiasm for UHV in China is fizzling, the technology will still have a role in the country’s renewable transition. How successful the reforms are will determine what kind of a role that is.    

Fecha de Publicación: 17-09-21

Preparation of activated carbon from biomass and its’ applications in water and gas purification

Descripción: Preparation of activated carbon from biomass and its’ applications in water and gas purification     Due to its versatility and wide range of applications, activated carbon is widely used as contaminant removal media. Recent research have focused on enhancing the effectiveness of activated carbon by modifying their specific properties in order to enable the carbon to develop affinity for certain contaminants. In view of this, a comprehensive list of literatures on chemical, physical and biological modification techniques of activated carbon pertaining to enhancement of contaminant removal from aqueous solutions was compiled and reviewed. Acidic treatment to introduce acidic functional groups onto surface of coal based activated carbon was by far, the most studied technique. It was apparent from the literature survey that the beneficial effects of specific modification techniques on activated carbon adsorption of targeted contaminant species from aqueous solutions were profound, with some studies reported increase of contaminant uptake factors of more than 2. Concurrently, considerable decreases associated with certain contaminant uptakes can also occur depending on the technique used.     Without pure water, it is impossible to survive for any living beings. The ratio of freshwater on our planet is very poor and the demand is increasing with time for the growing population. Furthermore, water is being contaminated by industrial and agricultural activities, pharmaceuticals, technocratic civilization, pesticides, garments, global changes etc. In addition to this, environmental pollution and global warming are swelling due to the greenhouse and harmful gases generated from the dumping and burning of fossil fuel. Addressing these problems, it is necessary to find out the cost-effective and environmental friendly processes to purify the contaminated water and air. Activated carbons (ACs) are one of the best solutions for removing the pollutants from aqueous and atmosphere as it is the carbonaceous materials with a high degree of porosity, well-developed surface area, and distinguished functional groups which are required for elimination of contaminants. The preparations of activated carbon are easy and safe processes, mainly from the pyrolysis or gasification of biomass with heat and/or chemicals. The recycling and regeneration of bituminous coal based activated carbon after use are also essential for resource maintenance and environmental safety. Thus, AC can protect the ecosystem in a double direction by purifying the water and air from the pollutants.     As the world’s population continues to grow, the demand for water increasing by 1% annually (WWAP/UN-Water, 2018). The population increase corresponds to the economic growth and development leading to rise in the use of chemical compounds, industrial compounds, agricultural wastes which pose the risk of polluting the existing water sources (Mohammad Razi, Al-Gheethi, Al-Qaini, and Yousef, 2018; Oladipo, Ifebajo, Nisar, and Ajayi, 2017; Qaisrani, Shams, Zhenren, Reza, and Zainuddin, 2018). It has reported that 663 million people have lacked access to clean water and 2.2 million deaths occurring due to diarrhea caused by inadequate sanitation and ingestion of contaminated potable water (Huang et al., 2018). The river, lake, and groundwater sources are contaminated due to fertilizers, pesticides, antibiotics, dyes, heavy metals from the industry which results in diseases like cancer, skin defect, kidney damage, liver problems, etc. (Ahmad and Danish, 2018). On the other hand, the burning of fossil fuel generates the greenhouse (GHG) and harmful gases like CO2, CH4, H2S, NO2 to the environment which are increasing with current energy demand for the rapid economic development (Ahmed, Abu Bakar, Azad, Sukri, and Mahlia, 2018a). Therefore, it is highly desirable to find the cheap and environmentally friendly adsorbent to get rid of the pollutants from water and air.     Of the above techniques, adsorption is one of the most popular methods used for the elimination of contaminants from wastewater due to its features of cost-effective, easy to operate, environment-friendly, low health risk, and non-destructive process (Balasundram et al., 2017; Oladipo and Gazi, 2015; Oladipo and Ifebajo, 2018). The addition of activated carbon (AC) in the adsorption process aids in the removal of a wide range of contaminants and carcinogenic compounds such as pharmaceuticals, metallic and non-metallic pollutants, dye and even taste and odor from aqueous solutions (Din, Ashraf, & Intisar, 2017). In comparison with other adsorbents like zeolite, clays, and polymers, AC shows better performance and stability in terms of adsorption (Regti, Laamari, Stiriba, and El Haddad, 2017). Recently, the pollutant gas adsorption by activated carbon has been recognized as a promising technology for the attraction mechanism between the pollutant and the surface functional groups (Le-Minh, Sivret, Shammay, and Stuetz, 2018). Production of AC from biomass can be seen as advantageous in two ways, firstly, it can prevent the production of CO2 by fixing the carbon and secondly, the AC can go into the soil naturally (Danish and Ahmad, 2018).     AC is carbonaceous material with an amorphous structure solid which has a high degree of porosity and well-developed surface area with numerous oxygenated functional groups such as carboxylic acids, phenols, carbonyls and lactones (Benedetti, Patuzzi, and Baratieri, 2018). The pores present on the AC surface are of significant importance and they exist in three forms: microspores, mesopores, and macropores (Jodeh, Abdelwahab, Jaradat, Warad, and Jodeh, 2016). Except for macropores that contribute the least contribution, the other pores contribute to the increase of the surface area and their presence on carbons is vital as they are the main source of driving the adsorption of gases and. In addition, functional groups also help promote adsorption capabilities (Elsayed et al., 2017). These distinctive characteristics make AC a versatile substance material that can be used not only as an adsorbent in water and gases but also as a catalyst or co-catalyst for the removal of pollutants from gases, liquids as well as the recovery of chemicals (Afif et al., 2019). Most studies have shown satisfactory results of ACs, specifically the effectiveness of removing organic compounds like dye, phenolic compounds, and inorganic compounds. They are also used in the field of the pharmaceutical industry to get rid of ingested toxins from the human body, recovery of gold, silver, and other metals (Vences-Alvarez et al., 2017). They are used as catalysts and co-catalyst in the gas mask filter company, food industries, chemical industries and automobile pollution control companies (Danish and Ahmad, 2018).     Usually, ACs are produced from finite resources such as coal, lignite, peat, petroleum residue materials that are expensive and required intensive regeneration (Yahya et al., 2018). It is reported that the demand for AC is estimated to increase by up to 2.1 million metric tons by the year 2018 (Maneerung et al., 2016). The high demand and the necessities have led to the discovery of cheaper, environmental-friendly and sustainable resources for the production of AC like biochar from thermal treatment of biomass. The primary sources of AC are agricultural waste, sewage, municipal waste, industrial waste, forestry residue, acacia species, Imperata cylindrica(Ahmed et al., 2018a, Ahmed, Parvaz, Johari, and Rafat, 2018b; Danish and Ahmad, 2018 ). Acacia species are known as the most invasive and they have adverse effects on other trees, and thus, threatens the biodiversity seriously (Hidayat, Abu Bakar, Yang, Phusunti, and Bridgwater, 2018; Islam, Mohamad, and Azad, 2019). A total of 1350 different types of acacia trees are known to exist in the world, which can grow in any climate (Ahmed, Hidayat, et al., 2018c; Radenahmad, Rahman, Morni, and Azad, 2018; Reza et al., 2019 ). Improvements in biofuel technology have developed the new technique to manage these invasive acacia trees to convert them into biochar (Alhinai, Azad, Bakar, and Phusunti, 2018) which can produce wood based activated carbon.     For activated carbon, biochar is the primary source which can be produced from the thermochemical conversion of biomass like pyrolysis or gasification (Odetoye, Abu Bakar, and Titiloye, 2019; Radenahmad et al., 2020). Through slow pyrolysis, a higher amount of biochar can be produced from various types of precursors, typically biomass as a feedstock under a range of processes and operating conditions (Reza et al., 2020). Pyrolysis/gasification is the process to generate biochar, bio-oil, and biogas from biomass which has different properties than the parent biomass (Abu Bakar, 2013; Odetoye, Onifade, AbuBakar, and Titiloye, 2013). Bio-oil can be used as energy after refinement (Odetoye, Afolabi, Abu Bakar, and Titiloye, 2018). Biogas is the combination of different gases that can be used as fuel in a fuel cell (Abdalla et al., 2018; Afif et al., 2016; Afroze et al., 2020b, 2020a, 2019; Radenahmad et al., 2016). Finally, the solid residue is the biochar which can be converted into activated carbon (Morni et al., 2018). Using the same precursor, different types of ACs can be produced by activating agents under different operating conditions (Yusuff, 2019). Activated carbon can be produced by physical, chemical, physiochemical and microwave-assisted activation of biochar and biomass. Physical activation consists of heat and gas (steam, CO2, N2 or mixture), chemical activation is done by chemical agents (acid, base, metal oxide, alkaline metal), physiochemical activation involves heat and chemical and microwave-assisted activation is by microwave radiation (Ao et al., 2018). The activation depends on particle size, retention time, impregnation ratio, procedure configuration, activation period, properties of the precursor, and chemical substances. To further improve the features of AC, researchers have been performing research studies for producing much better AC via loading nanoparticles on the surface of this material which may be used in the removal of organic and inorganic compounds from aqueous solutions more efficiently (Lakshmi et al., 2018).     The present paper reviews the efficiency of different types of activation processes of activated carbon from biomass. The adsorption capacity of contaminants and pollutants from water and air has been described elaborately to get pure water with clean air. The recycling/regeneration and handling process of Saw Dust Activated Carbon is also illustrated.     2. Preparation of activated carbon     For the preparations of shell activated carbon, two basic steps are maintained. The first one is the carbonization and the second one is the activation. Carbonization is done through the pyrolysis/gasification at a higher temperature in an inert atmosphere to produce the biochar (Odetoye et al., 2019). In this stage, the carbon content of the carbonaceous substance was prepared by removing the volatile matter through thermal degradation (Radenahmad et al., 2020). The temperature, the heating rate, the nitrogen gas flow rate and the residence time are the significant parameters in this stage. As the achieved biochar reveals low adsorption ability, an activation process is essential to improve the pore volume, the pore diameter and the surface area (X. Yang et al., 2019). In the activation process, initially, the disorganized carbon was eliminated, exposed the lignin to the activating agents and developed the microporous structure. Finally, the existing pores are widened to a large size by burning of the walls between the pores. This raises the intermediate pores and macro-porosity which reduces the volume of micro-pores. Depending on the type of activation, activation can be a process prior to carbonization or subsequent to carbonization for the elimination of deposited tarry substances in biochar that can help to enhance the porosity and to provide high surface areas for the ACs (Ukanwa et al., 2019).     

Fecha de Publicación: 17-09-21

Auto-disable syringes are not for needle programmes

Descripción: Auto-disable syringes are not for needle programmes     WHO and its partners recommend the use of auto-disable syringes, "bundled" with the supply of vaccines when donor dollars are used, in all mass immunization campaigns, and also strongly advocate their use in routine immunization programmes. Because of the relatively high price of auto-disable syringes, WHO's Technical Network for Logistics in Health recommends that activities be initiated to encourage the transfer of production technology for these syringes as a means of promoting their use and enhancing access to the technology. The present article examines factors influencing technology transfer, including feasibility, corporate interest, cost, quality assurance, intellectual property considerations, and probable time frames for implementation. Technology transfer activities are likely to be complex and difficult, and may not result in lower prices for syringes. Guidelines are offered on technology transfer initiatives for auto-disable syringes to ensure the quality of the product, the reliability of the supply, and the feasibility of the technology transfer activity itself.     UNICEF is working to buy 1 billion syringes by the end of 2021 for COVID-19 vaccination efforts in countries participating in the COVAX Facility.  Although the vaccines secured by the Facility may vary in their formulation and storage requirements, the syringes will all be of the auto-disable (AD) type, approved by the World Health Organization.      AD syringes are recommended for immunization programmes because they are designed to prevent re-use by locking automatically after a single use. They are the best way of ensuring that people receive their shots safely, without a risk of contracting an infection due to contaminated needles. The AD syringes bought for this immense operation are similar to those routinely procured and delivered by UNICEF for the vaccination of children worldwide.     Joint efforts for safe injection     Until a few decades ago, children were vaccinated using safety syringe, which exposed them to the risk of transmission of bloodborne diseases like Hepatitis B and HIV. “Sometimes, these used syringes were resold and reused, and we have encountered instances of children using them as toys”, tells Robin Nandy, UNICEF Chief of Immunization.     According to a study sponsored by WHO in 2014, up to 1.7 million people contracted hepatitis B, up to 315 000 with hepatitis C, and 33,800 with HIV through unsafe injections.     The situation started to improve in 1999, when UNICEF, the World Health Organization and the United Nations Population Fund (UNFPA) jointly called for the improvement in injection safety standards. In a statement, the organizations noted that AD syringes were already available and affordable and declared that they should be the device of choice for administering vaccines in both routine services and during mass campaigns.     Since then, several initiatives have driven progress in injection safety for immunization. An example of collective advocacy was taken by the Measles and Rubella Initiative (M&RI), launched in 2001 and led by the American Red Cross, the United Nations Foundation, the U.S. Centers for Disease Control and Prevention, UNICEF and the World Health Organization. The partnership required that safe injection equipment, including AD syringes, were used as part of the support they provided countries to carry out vaccination campaigns. With the support of major donors, UNICEF has been playing a key role in the global effort for safe injection. The number of auto disable syringe UNICEF procured grew from 11 million in 1997 to around 600-800 million per year. UNICEF is also the world’s largest buyer of AD syringes, procuring 40% of the global market. This growth has been accompanied by a significant price drop. Three decades ago, UNICEF paid US$ 0.12 per unit of an AD syringe. The price has since fallen to US$ 0.03 per unit.     “All these developments have been the result of a global programmatic decision to use AD syringes for immunization supported by a variety of stakeholders”, says Robert Matthews, head of the Medical Devices Unit in UNICEF Supply Division. He explains that a number of elements, including funding from donors like Gavi and M&RI, have helped influence and shift the market away from traditional disposable reusable syringes towards the use of AD syringes for immunization.   Through COVAX, UNICEF is keeping its commitment to safe injection by exclusively buying AD syringes for the COVID-19 vaccination. “With safe injection equipment we strive to guarantee that the good intention embodied in the vaccine does not do harm”, says Robert.     As you may have seen in the media recently, the World Health Organisation (WHO) has launched new guidelines on medical injections and a global campaign to switch all medical and vaccination injections to syringes that cannot be used more than once. These "safety-engineered syringes" may, for example, include a weak spot in the plunger that causes it to break if the user attempts to pull back on the plunger after the injection. Others have a metal clip that blocks the plunger so it cannot be moved back, while in others the needle retracts into the luer slip type syringe barrel at the end of the injection. Using these syringes in medical settings will, according to WHO, protect millions of people from becoming infected with HIV, hepatitis and other diseases through the re-use of unsterile equipment by doctors and medical staff, especially in the poorest health systems in the world. Their ambitious aim is that every country should have transitioned to these new syringes by 2020.     However, these recommendations and this campaign explicitly do not apply to needle and syringe programmes for people who inject drugs (the population most impacted by HIV, hepatitis and other diseases transmitted through contaminated injecting equipment). It has been demonstrated and proven on many occasions that these auto-disable syringes are unsuitable, ineffective and undesirable in these programmes – clients simply do not like them, they are often harder to use, and they cost more. For example, drug preparation and injection amongst people who inject drugs routinely involves more than one retraction or depression of the syringe plunger, making auto-disable syringes inappropriate. Several peer-reviewed studies have also documented the inadequacy of auto-disable syringes for people who inject drugs – see this informative briefing from the USA's Harm Reduction Coalition for more information.     As a result, and after intensive lobbying by the NNEF and other civil society partners around the world, the WHO guidelines (available here) include the clear exemption that health systems must set "policies and standards for procurement, use and safe disposal of disposable syringes in situations where they remain necessary as described above, including in syringe programmes for people who inject drugs". Similar disclaimers appear in the accompanying leaflet and press release – but this has not been picked up in the media reporting, such as the recent BBC article.     So in short, auto-disable or auto-retract syringes remain unsuitable for needle and syringe programmes. Of course, the message must continue to be that every syringe is intended to be single use, and programmes should continue to use low dead space syringes as before. But these new guidelines from WHO should not change the way that we work     Injection is one of the important health care procedures used globally to administer drugs. Its unsafe use can transmit various blood borne pathogens. This article aims to review the history and status of injection practices, its importance, interventions and the challenges for safe injection practice in developing countries. The history of injections started with the discovery of syringe in the early nineteenth century. Safe injection practice in developed countries was initiated in the early twentieth century but has not received adequate attention in developing countries. The establishment of “Safe Injection Global Network (SIGN)” was an milestone towards safe injection practice globally. In developing countries, people perceive injection as a powerful healing tool and do not hesitate to pay more for injections. Unsafe disposal and reuse of contaminated luer lock type syringe is common. Ensuring safe injection practice is one of the greatest challenges for healthcare system in developing countries. To address the problem, interventions with active involvement of a number of stakeholders is essential. A combination of educational, managerial and regulatory strategies is found to be effective and economically viable. Rational and safe use of injections can save many lives but unsafe practice threatens life. Safe injection practice is crucial in developing countries. Evidence based interventions, with honest commitment and participation from the service provider, recipient and community with aid of policy makers are required to ensure safe injection practice.     Auto-disable syringe has a mechanism to immobilize the plunger or block the needle or cause the syringe to leak when a second injection is attempted hence it cannot be reused. The needle is also fixed permanently in the syringe to prevent the reuse of the needle as well. Mandatory use of auto-disable syringes for vaccination is a good step for ensuring injection safety. But associated cost and safe disposal is a serious limitation for developing countries. Although auto-disable syringe cannot be reused, the exposed needle can be risky. Moreover disposal of auto-disable syringe is also a challenge in developing countries where the infrastructure for disposal is lacking. Despite the growing awareness about the need of safe health care waste management (including disposal of injectable), compliance is lacking. So, pros and cons of each intervention, in context to the implementation region and resources should be analysed before implementation.   The healthcare workers (front line workers) should be actively involved in the planning, implementation and evaluation of new technologies and other changes in the practice, for the practical and successful implementation.     Injections have saved many lives but at the same time carry the risk of infections. So the current concern is how to make this practice more safe and beneficial in developing nations? Various strategies such as educational, managerial and regulatory have been discussed but challenges have to be overcome for their successful implementation. Rational use of injections, proper management and disposal of injectable products can lead to safe injection practice and for this honest commitment and participation is required from service provider, recipient and community with support from policy makers. More research to understand the problem in individual countries and regions is required to develop evidence based interventions. Auto-disable syringes are not for needle programmes     WHO and its partners recommend the use of auto-disable syringes, "bundled" with the supply of vaccines when donor dollars are used, in all mass immunization campaigns, and also strongly advocate their use in routine immunization programmes. Because of the relatively high price of auto-disable syringes, WHO's Technical Network for Logistics in Health recommends that activities be initiated to encourage the transfer of production technology for these syringes as a means of promoting their use and enhancing access to the technology. The present article examines factors influencing technology transfer, including feasibility, corporate interest, cost, quality assurance, intellectual property considerations, and probable time frames for implementation. Technology transfer activities are likely to be complex and difficult, and may not result in lower prices for syringes. Guidelines are offered on technology transfer initiatives for auto-disable syringes to ensure the quality of the product, the reliability of the supply, and the feasibility of the technology transfer activity itself.     UNICEF is working to buy 1 billion syringes by the end of 2021 for COVID-19 vaccination efforts in countries participating in the COVAX Facility.  Although the vaccines secured by the Facility may vary in their formulation and storage requirements, the syringes will all be of the auto-disable (AD) type, approved by the World Health Organization.      AD syringes are recommended for immunization programmes because they are designed to prevent re-use by locking automatically after a single use. They are the best way of ensuring that people receive their shots safely, without a risk of contracting an infection due to contaminated needles. The AD syringes bought for this immense operation are similar to those routinely procured and delivered by UNICEF for the vaccination of children worldwide.     Joint efforts for safe injection     Until a few decades ago, children were vaccinated using safety syringe, which exposed them to the risk of transmission of bloodborne diseases like Hepatitis B and HIV. “Sometimes, these used syringes were resold and reused, and we have encountered instances of children using them as toys”, tells Robin Nandy, UNICEF Chief of Immunization.     According to a study sponsored by WHO in 2014, up to 1.7 million people contracted hepatitis B, up to 315 000 with hepatitis C, and 33,800 with HIV through unsafe injections.     The situation started to improve in 1999, when UNICEF, the World Health Organization and the United Nations Population Fund (UNFPA) jointly called for the improvement in injection safety standards. In a statement, the organizations noted that AD syringes were already available and affordable and declared that they should be the device of choice for administering vaccines in both routine services and during mass campaigns.     Since then, several initiatives have driven progress in injection safety for immunization. An example of collective advocacy was taken by the Measles and Rubella Initiative (M&RI), launched in 2001 and led by the American Red Cross, the United Nations Foundation, the U.S. Centers for Disease Control and Prevention, UNICEF and the World Health Organization. The partnership required that safe injection equipment, including AD syringes, were used as part of the support they provided countries to carry out vaccination campaigns. With the support of major donors, UNICEF has been playing a key role in the global effort for safe injection. The number of auto disable syringe UNICEF procured grew from 11 million in 1997 to around 600-800 million per year. UNICEF is also the world’s largest buyer of AD syringes, procuring 40% of the global market. This growth has been accompanied by a significant price drop. Three decades ago, UNICEF paid US$ 0.12 per unit of an AD syringe. The price has since fallen to US$ 0.03 per unit.     “All these developments have been the result of a global programmatic decision to use AD syringes for immunization supported by a variety of stakeholders”, says Robert Matthews, head of the Medical Devices Unit in UNICEF Supply Division. He explains that a number of elements, including funding from donors like Gavi and M&RI, have helped influence and shift the market away from traditional disposable reusable syringes towards the use of AD syringes for immunization.   Through COVAX, UNICEF is keeping its commitment to safe injection by exclusively buying AD syringes for the COVID-19 vaccination. “With safe injection equipment we strive to guarantee that the good intention embodied in the vaccine does not do harm”, says Robert.     As you may have seen in the media recently, the World Health Organisation (WHO) has launched new guidelines on medical injections and a global campaign to switch all medical and vaccination injections to syringes that cannot be used more than once. These "safety-engineered syringes" may, for example, include a weak spot in the plunger that causes it to break if the user attempts to pull back on the plunger after the injection. Others have a metal clip that blocks the plunger so it cannot be moved back, while in others the needle retracts into the luer slip type syringe barrel at the end of the injection. Using these syringes in medical settings will, according to WHO, protect millions of people from becoming infected with HIV, hepatitis and other diseases through the re-use of unsterile equipment by doctors and medical staff, especially in the poorest health systems in the world. Their ambitious aim is that every country should have transitioned to these new syringes by 2020.     However, these recommendations and this campaign explicitly do not apply to needle and syringe programmes for people who inject drugs (the population most impacted by HIV, hepatitis and other diseases transmitted through contaminated injecting equipment). It has been demonstrated and proven on many occasions that these auto-disable syringes are unsuitable, ineffective and undesirable in these programmes – clients simply do not like them, they are often harder to use, and they cost more. For example, drug preparation and injection amongst people who inject drugs routinely involves more than one retraction or depression of the syringe plunger, making auto-disable syringes inappropriate. Several peer-reviewed studies have also documented the inadequacy of auto-disable syringes for people who inject drugs – see this informative briefing from the USA's Harm Reduction Coalition for more information.     As a result, and after intensive lobbying by the NNEF and other civil society partners around the world, the WHO guidelines (available here) include the clear exemption that health systems must set "policies and standards for procurement, use and safe disposal of disposable syringes in situations where they remain necessary as described above, including in syringe programmes for people who inject drugs". Similar disclaimers appear in the accompanying leaflet and press release – but this has not been picked up in the media reporting, such as the recent BBC article.     So in short, auto-disable or auto-retract syringes remain unsuitable for needle and syringe programmes. Of course, the message must continue to be that every syringe is intended to be single use, and programmes should continue to use low dead space syringes as before. But these new guidelines from WHO should not change the way that we work     Injection is one of the important health care procedures used globally to administer drugs. Its unsafe use can transmit various blood borne pathogens. This article aims to review the history and status of injection practices, its importance, interventions and the challenges for safe injection practice in developing countries. The history of injections started with the discovery of syringe in the early nineteenth century. Safe injection practice in developed countries was initiated in the early twentieth century but has not received adequate attention in developing countries. The establishment of “Safe Injection Global Network (SIGN)” was an milestone towards safe injection practice globally. In developing countries, people perceive injection as a powerful healing tool and do not hesitate to pay more for injections. Unsafe disposal and reuse of contaminated luer lock type syringe is common. Ensuring safe injection practice is one of the greatest challenges for healthcare system in developing countries. To address the problem, interventions with active involvement of a number of stakeholders is essential. A combination of educational, managerial and regulatory strategies is found to be effective and economically viable. Rational and safe use of injections can save many lives but unsafe practice threatens life. Safe injection practice is crucial in developing countries. Evidence based interventions, with honest commitment and participation from the service provider, recipient and community with aid of policy makers are required to ensure safe injection practice.     Auto-disable syringe has a mechanism to immobilize the plunger or block the needle or cause the syringe to leak when a second injection is attempted hence it cannot be reused. The needle is also fixed permanently in the syringe to prevent the reuse of the needle as well. Mandatory use of auto-disable syringes for vaccination is a good step for ensuring injection safety. But associated cost and safe disposal is a serious limitation for developing countries. Although auto-disable syringe cannot be reused, the exposed needle can be risky. Moreover disposal of auto-disable syringe is also a challenge in developing countries where the infrastructure for disposal is lacking. Despite the growing awareness about the need of safe health care waste management (including disposal of injectable), compliance is lacking. So, pros and cons of each intervention, in context to the implementation region and resources should be analysed before implementation.   The healthcare workers (front line workers) should be actively involved in the planning, implementation and evaluation of new technologies and other changes in the practice, for the practical and successful implementation.     Injections have saved many lives but at the same time carry the risk of infections. So the current concern is how to make this practice more safe and beneficial in developing nations? Various strategies such as educational, managerial and regulatory have been discussed but challenges have to be overcome for their successful implementation. Rational use of injections, proper management and disposal of injectable products can lead to safe injection practice and for this honest commitment and participation is required from service provider, recipient and community with support from policy makers. More research to understand the problem in individual countries and regions is required to develop evidence based interventions.

Fecha de Publicación: 17-09-21

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