Civil Rights
Movements, leaders, victories and the continuing fight for equality.
q2K BHP
Black History Portal
THE BHP WIRE —
HIDDEN TRUTHS
What's New!
Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
Mansa Musa was the ruler of the Mali Empire in West Africa. Details recorded here should be sourced; unknown information is left blank.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Hydrogel agriculture technology uses insoluble gel-forming polymers to improve the water-holding properties of different soils, such as clays and sandy loams. This can increase water-holding and water use (up to 85% for sand), improve soil permeability, reduce the need for irrigation, reduce compaction, soil erosion, and leaching, and improve plant growth.
Desertification and lack of water threaten agriculture in many arid and semi-arid regions of the world; these may be mitigated with hydrogels.[1]
Hydrogels are hydrophilic crosslinked polymers that form three-dimensional molecular networks which can absorb and hold great amounts of water.[2]
Different types may be suitable for agricultural use. A starch-based (grafing) hydrogel is biodegradable and cheap, and can be modified to adjust its ability to hold water.[3] Cross-linked acrylic acid polymer hydrogels are commercially available; they are effectively insoluble[4] but slowly break down releasing toxic acrylamide.[5]
Hydrogels of different kinds could be useful in agriculture, reducing drought stress in plants, making better use of irrigation water and fertilizer.[6][7][8]
Superabsorbent hydrogel polymers can in principle influence soil permeability, density, structure, texture, evaporation and infiltration rates of water through soils.[7] They can also allow pesticides to be released slowly over a long period, increasing effectiveness and reducing side-effects such as pesticide runoff. There has therefore been considerable research interest into the possible use of hydrogels in agriculture.[9] For example, a hydrogel based on gum tragacanth increases the water content of clay soil by up to 5.35% and of sandy loam by up to 5.5%; it could also be used to release calcium chloride slowly over a prolonged period.[10]
Suitably prepared hydrogels can simultaneously supply and slowly release pesticides (such as herbicides) in the soil, and increase a sandy soil's retention of water. Hydrogels developed for this purpose include polymers of oligooxyethylene methacrylate, linked by ionic and covalent bonds to a herbicide such as 4-chloro-2-methylphenoxyacetic acid (CMPA). Other hydrophilic polymers studied have been made from a variety of different acrylate monomers to release the pesticides 2,4-D and CMPA. These offer different combinations of pesticide release rate and soil water retention. Hydrogels can also be used to encapsulate the insecticide cypermethrin and the fungicide copper sulphate. Superabsorbent polymers can be used to release phosphate fertiliser slowly, by making an ester bond between polyvinyl alcohol and phosphoric acid. A polymer/clay superabsorbent composite material made by attaching acrylamide to finely powdered attapulgite (a fuller's earth clay) shows promise for its excellent water retention and low cost compared to polyacrylamide hydrogel.[8]
Recent research has introduced biodegradable cellulose-based superabsorbent hydrogels that significantly improve water retention in sandy soils, offering a sustainable solution for agricultural water management.[11]
In 2015, the Indian Agriculture Research Institute (IARI) reported the development of a novel hydrogel for agricultural use. It was intended to help farmers to cope with drought, making efficient use of water in arid and semi-arid regions of India. the product is to be commercialized by the Ministry of Science and Technology's National Research Development Corporation (NRDC) in collaboration with a company based in Chennai, Reliance Industries Limited.[12]
{{cite journal}}: CS1 maint: periodical has ISBN (link)Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
A hydrogel is a biphasic material, a mixture of porous and permeable solids and at least 10% of water or other interstitial fluid. The solid phase is a water insoluble three dimensional network of polymers, having absorbed a large amount of water or biological fluids. Hydrogels have several applications, especially in the biomedical area, such as in hydrogel dressing. Many hydrogels are synthetic, but some are derived from natural materials. The term "hydrogel" was coined in 1894.
Hydrogel fiber is a hydrogel made into a fibrous state, where its width is significantly smaller than its length. The hydrogel's specific surface area at fibrous form is larger than that of the bulk hydrogel, and its mechanical properties also changed accordingly. As a result of these changes, hydrogel fiber has a faster matter exchange rate and can be woven into different structures. As a water swollen network with usually low toxicity, hydrogel fiber can be used in a variety of biomedical applications such as drug carrier, optical sensor, and actuator. But the production of hydrogel fiber can be challenging as the hydrogel is crosslinked and can not be shaped into a fibrous state after polymerization. To make hydrogel into a fibrous state, the pregel solution must be made into fibrous form and then crosslinked while maintaining this shape.
Hydrogel agriculture technology uses insoluble gel-forming polymers to improve the water-holding properties of different soils, such as clays and sandy loams. This can increase water-holding and water use (up to 85% for sand), improve soil permeability, reduce the need for irrigation, reduce compaction, soil erosion, and leaching, and improve plant growth. Desertification and lack of water threaten agriculture in many arid and semi-arid regions of the world; these may be mitigated with hydrogels.
Hydrogel dressing is a medical dressing based on hydrogels – flexible, three-dimensional hydrophilic structures. The insoluble hydrophilic structures absorb polar wound exudates and allow oxygen diffusion at the wound bed to accelerate healing. Hydrogel dressings can be designed to prevent bacterial infection, retain moisture, promote optimum adhesion to tissues, and satisfy the basic requirements of biocompatibility. Hydrogel dressings can also be designed to respond to changes in the microenvironment at the wound bed. Hydrogel dressings should promote an appropriate microenvironment for angiogenesis, recruitment of fibroblasts, and cellular proliferation. Hydrogels respond elastically to applied stress; gels made from materials like collagen exhibit high toughness and low sliding friction, reducing damage from mechanical stress. Hydrogel dressings should possess mechanical and physical properties similar to the 3D microenvironment of the extracellular matrix of human skin. Hydrogel wound dressings are designed to have a mechanism for application and removal which minimizes further trauma to tissues. Hydrogel dressings can be sorted into three categories: synthetic, natural, and hybrid. Synthetic hydrogel dressings have been produced using biomimetic extracellular matrix nanofibers such as polyvinyl alcohol (PVA). Self-assembling designer peptide hydrogels are another type of synthetic hydrogel in development. Natural hydrogel dressings are further subdivided into either polysaccharide-based (e.g. alginates) or proteoglycan- and/or protein-based (e.g. collagen). Hybrid hydrogel dressings incorporate synthetic nanoparticles and natural materials.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.
