|
Dichlorodiphenyltrichloroethane
Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. DDT was first synthesized in 1874 by the Austrian chemist Othmar Zeidler. DDT's insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939. DDT was used in the second half of World War II to limit the spread of the insect-borne diseases malaria and typhus among civilians and troops. Müller was awarded the Nobel Prize in Physiology or Medicine in 1948 "for his discovery of the high efficiency of DDT as a contact poison against several arthropods". By October 1945, DDT was available for public sale in the United States. Although it was promoted by government and industry for use as an agricultural and household pesticide, there were also concerns about its use from the beginning. Opposition to DDT was focused by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Impact Of Pesticides
The environmental effects of pesticides describe the broad series of consequences of using pesticides. The unintended consequences of pesticides is one of the main drivers of the negative impact of modern industrial agriculture on the environment. Pesticides, because they are toxic chemicals meant to kill pest species, can affect non-target species, such as plants, animals and humans. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, because they are sprayed or spread across entire agricultural fields. Other agrochemicals, such as fertilizers, can also have negative effects on the environment. The negative effects of pesticides are not just in the area of application. Runoff and pesticide drift can carry pesticides into distant aquatic environments or other fields, grazing areas, human settlements and undeveloped areas. Other problems emerge from poor production, transport, storage and disposal practices.Tashkent (199 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallinity
Crystallinity refers to the degree of structural order in a solid. In a crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ..., the atoms or molecules are arranged in a regular, periodic manner. The degree of crystallinity has a big influence on hardness, density, Transparency and translucency, transparency and diffusion. In an ideal gas, the relative positions of the atoms or molecules are completely random. Amorphous materials, such as liquids and glasses, represent an intermediate case, having order over short distances (a few atomic or molecular spacings) but not over longer distances. Many materials, such as glass-ceramics and some polymers, can be prepared in such a way as to produce a mixture of crystalline and Amorphous solid, amorphous regions. In such cases, crystall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector Control
Vector control is any method to limit or eradicate the mammals, birds, insects or other arthropods (here collectively called " vectors") which transmit disease pathogens. The most frequent type of vector control is mosquito control using a variety of strategies. Several of the " neglected tropical diseases" are spread by such vectors. Importance For diseases where there is no effective cure, such as Zika virus, West Nile fever and Dengue fever, vector control remains the only way to protect human populations. However, even for vector-borne diseases with effective treatments the high cost of treatment remains a huge barrier to large amounts of developing world populations. Despite being treatable, malaria has by far the greatest impact on human health from vectors. In Africa, a child dies every minute of malaria; this is a reduction of more than 50% since 2000 due to vector control. In countries where malaria is well established the World Health Organization estimates countr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Study of structure determines their structural formula. Study of properties includes physical and chemical properties, and evaluation of chemical reactivity to understand their behavior. The study of organic reactions includes the chemical synthesis of natural products, drugs, and polymers, and study of individual organic molecules in the laboratory and via theoretical ( in silico) study. The range of chemicals studied in organic chemistry includes hydrocarbons (compounds containing only carbon and hydrogen) as well as compounds based on carbon, but also containing other elements, especially oxygen, nitrogen, sulfur, phosphorus (i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Properties Of Water
Water () is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, which is nearly colorless apart from an inherent hint of blue. It is by far the most studied chemical compound and is described as the "universal solvent" and the "solvent of life". It is the most abundant substance on the surface of Earth and the only common substance to exist as a solid, liquid, and gas on Earth's surface. It is also the third most abundant molecule in the universe (behind molecular hydrogen and carbon monoxide). Water molecules form hydrogen bonds with each other and are strongly polar. This polarity allows it to dissociate ions in salts and bond to other polar substances such as alcohols and acids, thus dissolving them. Its hydrogen bonding causes its many unique properties, such as having a solid form less dense than its liquid form, a relatively high boiling point of 100 °C for its molar mass, and a high heat capacity. Water is amphoteric, meani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solubility
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubility of a substance in a specific solvent is generally measured as the concentration of the solute in a saturated solution, one in which no more solute can be dissolved. At this point, the two substances are said to be at the solubility equilibrium. For some solutes and solvents, there may be no such limit, in which case the two substances are said to be " miscible in all proportions" (or just "miscible"). The solute can be a solid, a liquid, or a gas, while the solvent is usually solid or liquid. Both may be pure substances, or may themselves be solutions. Gases are always miscible in all proportions, except in very extreme situations,J. de Swaan Arons and G. A. M. Diepen (1966): "Gas—Gas Equilibria". ''Journal of Chemical Physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrophobe
In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thus, prefer other neutral molecules and nonpolar solvents. Because water molecules are polar, hydrophobes do not dissolve well among them. Hydrophobic molecules in water often cluster together, forming micelles. Water on hydrophobic surfaces will exhibit a high contact angle. Examples of hydrophobic molecules include the alkanes, oils, fats, and greasy substances in general. Hydrophobic materials are used for oil removal from water, the management of oil spills, and chemical separation processes to remove non-polar substances from polar compounds. Hydrophobic is often used interchangeably with lipophilic, "fat-loving". However, the two terms are not synonymous. While hydrophobic substances are usually lipophilic, there are exception ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicofol
Dicofol is an organochlorine pesticide that is chemically related to DDT. Dicofol is a miticide that is very effective against spider mite. One of the intermediates used in its production is DDT. This has caused criticism by many environmentalists; however, the World Health Organization classifies dicofol as a Level II, "moderately hazardous" pesticide. It is known to be harmful to aquatic animals, and can cause eggshell thinning in various species of birds. Difference between dicofol and DDT Dicofol is structurally similar to DDT. It differs from DDT by the replacement of the hydrogen (H) on C-1 by a hydroxyl (OH) functional group. One of the intermediates used in its production is DDT. Chemistry Dicofol is usually synthesized from technical DDT. During the synthesis, DDT is first chlorinated to an intermediate, Cl-DDT, followed by hydrolyzing to dicofol. After the synthesis reaction, DDT and Cl-DDT may remain in the dicofol product as impurities. * Formula: C14H9Cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acaricide
Acaricides are pesticides that kill members of the arachnid subclass ''Acari'', which includes ticks and mites. Acaricides are used both in medicine and agriculture, although the desired selective toxicity differs between the two fields. Terminology More specific words are sometimes used, depending upon the targeted group: * "Ixodicides" are substances that kill ticks. * "Miticides" are substances that kill mites. *The term scabicide is more narrow, and refers to agents specifically targeting '' Sarcoptes''. *The term "arachnicide" is more general, and refers to agents that target arachnids. This term is used much more rarely, but occasionally appears in informal writing. As a practical matter, mites are a paraphyletic grouping, and mites and ticks are usually treated as a single group. Examples Examples include: * Permethrin can be applied as a spray. The effects are not limited to mites: lice, cockroaches, fleas, mosquitos, and other insects will be affected. * Ivermectin c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methoxychlor
Methoxychlor is a synthetic organochloride insecticide, now obsolete. Usage Methoxychlor was used to protect crops, ornamentals, livestock, and pets against fleas, mosquitoes, cockroaches, and other insects. It was intended to be a replacement for DDT, but has since been banned for use as a pesticide based on its acute toxicity, bioaccumulation, and endocrine disruption activity. The amount of methoxychlor in the environment changes seasonally due to its use in farming and foresting. It does not dissolve readily in water, so it is mixed with a petroleum-based fluid and sprayed, or used as a dust. Sprayed methoxychlor settles on the ground or in aquatic ecosystems, where it can be detected in sediments. Its degradation may take many months. Methoxychlor is ingested and absorbed by living organisms, and it accumulates in the food chain. Some metabolites may have unwanted side effects. Banned The use of methoxychlor as a pesticide was banned in the United States in 2003 and in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Fish And Wildlife Service
The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people." Among the responsibilities of the USFWS are enforcing federal wildlife laws; protecting endangered species; managing migratory birds; restoring nationally significant fisheries; conserving and restoring wildlife habitats, such as wetlands; helping foreign governments in international conservation efforts; and distributing money to fish and wildlife agencies of U.S. states through the Wildlife Sport Fish and Restoration Program. The vast majority of fish and wildlife habitats are on state or private land not controlled by the United States government. Therefore, the USFWS works closely with private groups su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contiguous United States
The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii (also the last ones admitted to the Union), and all other offshore insular areas, such as American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands. The colloquial term "Lower48" is used also, especially in relation to just Alaska (Hawaii is farther south). The related but distinct term continental United States includes Alaska (which is also on the continent of North America but separated from the 48 states by British Columbia and Yukon of Canada), but excludes the Hawaiian Islands and all U.S. territories in the Caribbean and the Pacific. The greatest distance (on a great-circle route) entirely within the contiguous U.S. is 2,802 miles (4,509 km), between Florida and the State of Washington; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
