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Lead–crime Hypothesis
The lead–crime hypothesis is a research area that involves a study of the correlation between elevated blood lead levels in children and increased rates of crime, delinquency, and recidivism later in life. Lead is widely understood to be highly toxic to multiple organs of the body, particularly the brain. Individuals exposed to lead at young ages are more vulnerable to learning disabilities, decreased I.Q., attention deficit hyperactivity disorder, and problems with impulse control, all of which may be negatively impacting decision making and leading to the commission of more crimes as these children reach adulthood, especially violent crimes. Proponents of the lead–crime hypothesis argue that the removal of lead additives from motor fuel, and the consequent decline in children's lead exposure, explains the fall in crime rates in the United States beginning in the 1990s. This hypothesis also offers an explanation of the earlier rise in crime in the preceding decades as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Pump Lead Warning
Gas is one of the four fundamental state of matter, states of matter (the others being solid, liquid, and plasma (physics), plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), chemical element, elemental molecules made from one type of atom (e.g. oxygen), or chemical compound, compound molecules made from a variety of atoms (e.g. carbon dioxide). A gas mixture, such as Earth's atmosphere, air, contains a variety of pure gases. What distinguishes a gas from liquids and solids is the vast separation of the individual gas Particle, particles. This separation usually makes a colourless gas invisible to the human observer. The gaseous state of matter occurs between the liquid and plasma states, the latter of which provides the upper temperature boundary for gases. Bounding the lower end of the temperature scale lie degenerative quantum gases which are gaining increasing attention. High-density atomic gases super-cooled to very low temperatures are c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Socioeconomic Status
Socioeconomic status (SES) is an economic and sociological combined total measure of a person's work experience and of an individual's or family's economic access to resources and social position in relation to others. When analyzing a family's SES, the household income, earners' education, and occupation are examined, as well as combined income, whereas for an individual's SES only their own attributes are assessed. Recently, research has revealed a lesser recognized attribute of SES as perceived financial stress, as it defines the "balance between income and necessary expenses". Perceived financial stress can be tested by deciphering whether a person at the end of each month has more than enough, just enough, or not enough money or resources. However, SES is more commonly used to depict an economic difference in society as a whole. Socioeconomic status is typically broken into three levels (high, middle, and low) to describe the three places a family or an individual may fal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organolead Chemistry
Organolead compounds are chemical compounds containing a chemical bond between carbon and lead. Organolead chemistry is the corresponding science. The first organolead compound was hexaethyldilead (Pb2(C2H5)6), first synthesized in 1858.''Main Group Metals in Organic Synthesis'' Yamamoto, Hisashi / Oshima, Koichiro (eds.) 2004 Sharing the same group with carbon, lead is tetravalent. Going down the carbon group the C–''X'' (''X'' = C, Si, Ge, Sn, Pb) bond becomes weaker and the bond length larger. The C–Pb bond in tetramethyllead is 222 pm long with a dissociation energy of 49 kcal/ mol (204 kJ/mol). For comparison the C–Sn bond in tetramethyltin is 214 pm long with dissociation energy 71 kcal/mol (297 kJ/mol). The dominance of Pb(IV) in organolead chemistry is remarkable because inorganic lead compounds tend to have Pb(II) centers. The reason is that with inorganic lead compounds elements such as nitrogen, oxygen and the halides have a much higher electronegativity than le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ) * ''particle radiation'', such as alpha radiation (α), beta radiation (β), proton radiation and neutron radiation (particles of non-zero rest energy) * '' acoustic radiation'', such as ultrasound, sound, and seismic waves (dependent on a physical transmission medium) * ''gravitational wave, gravitational radiation'', that takes the form of gravitational waves, or ripples in the curvature of spacetime Radiation is often categorized as either ''ionizing radiation, ionizing'' or ''non-ionizing radiation, non-ionizing'' depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volt, eV, which is enough to ionize atoms and molecules and break ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaded Gasoline
Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb( C2H5)4. It is a fuel additive, first being mixed with gasoline beginning in the 1920s as a patented octane rating booster that allowed engine compression to be raised substantially. This in turn increased vehicle performance and fuel economy. TEL was first synthesised by German chemist Carl Jacob Löwig in 1853. American chemical engineer Thomas Midgley Jr., who was working for General Motors, was the first to discover its effectiveness as an antiknock agent in 1921, after spending several years attempting to find an additive that was both highly effective and inexpensive. Concerns were later raised over the toxic effects of lead, especially on children. On cars not designed to operate on leaded gasoline, lead and lead oxides coat the catalyst in catalytic converters, rendering them ineffective, and can sometimes foul spark plugs. Starting in the 1970s, many count ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Paint
Lead paint or lead-based paint is paint containing lead. As pigment, lead(II) chromate (, "chrome yellow"), lead(II,IV) oxide, (, "red lead"), and lead(II) carbonate (, "white lead") are the most common forms.. Lead is added to paint to accelerate drying, increase durability, maintain a fresh appearance, and resist moisture that causes corrosion. It is one of the main health and environmental hazards associated with paint. Lead paint has been generally phased out of use due to the toxic nature of lead. Alternatives such as water-based, lead-free traffic paint are readily available. In some countries, lead continues to be added to paint intended for domestic use, whereas countries such as the United States and the United Kingdom have regulations prohibiting its use. However, lead paint may still be found in older properties painted prior to the introduction of such regulations. Although lead has been banned from household paints in the United States since 1978, it may still be f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Glass
Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40% (by weight) lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO. Lead glass is often desirable for a variety of uses due to its clarity. The term ''lead crystal'' is, technically, not an accurate term to describe lead glass, because glass lacks a crystalline structure and is instead an amorphous solid. The use of the term ''lead crystal'' or just "crystal" remains popular for historical and commercial reasons, and because "lead" sounds toxic to consumers. It is retained from the Venetian word ''cristallo'' to describe the rock crystal imitated by Murano glassmakers. This naming convention has been maintained to the present day to describe decorative hollow-ware. Lead crystal glassware was formerly used to store a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedanius Dioscorides
Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of ''De materia medica'' (, On Medical Material) —a 5-volume Greek encyclopedia about herbal medicine and related medicinal substances (a pharmacopeia), that was widely read for more than 1,500 years. For almost two millennia Dioscorides was regarded as the most prominent writer on plants and plant drugs. Life A native of Anazarbus, Cilicia, Asia Minor, Dioscorides likely studied medicine nearby at the school in Tarsus, Mersin, Tarsus, which had a pharmacological emphasis, and he dedicated his medical books to Laecanius Arius, a medical practitioner there. Though he writes he lived a "soldier's life" or "soldier-like life", his pharmacopeia refers almost solely to plants found in the Greek-speaking eastern Mediterranean, making it likely that he served in campaigns, or travelled in a civilian ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicander
Nicander of Colophon ( grc-gre, Νίκανδρος ὁ Κολοφώνιος, Níkandros ho Kolophṓnios; fl. 2nd century BC), Greek poet, physician and grammarian, was born at Claros (Ahmetbeyli in modern Turkey), near Colophon, where his family held the hereditary priesthood of Apollo. He flourished under Attalus III of Pergamum. He wrote a number of works both in prose and verse, of which two survive complete. The longest, '' Theriaca'', is a hexameter poem (958 lines) on the nature of venomous animals and the wounds which they inflict. The other, '' Alexipharmaca'', consists of 630 hexameters treating of poisons and their antidotes. Nicander's main source for medical information was the physician Apollodorus of Egypt. Among his lost works, '' Heteroeumena'' was a mythological epic, used by Ovid in the ''Metamorphoses'' and epitomized by Antoninus Liberalis; '' Georgica'', of which considerable fragments survive, was perhaps imitated by Virgil. The works of Nicander were pra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead(II) Acetate
Lead(II) acetate (Pb(CH3COO)2), also known as lead acetate, lead diacetate, plumbous acetate, sugar of lead, lead sugar, salt of Saturn, or Goulard's powder, is a white crystalline chemical compound with a slightly sweet taste. Like many other lead compounds, it is toxic. Lead acetate is soluble in water and glycerin. With water it forms the trihydrate, Pb(CH3COO)2·3H2O, a colourless or white efflorescent monoclinic crystalline substance. The substance is used as a reagent to make other lead compounds and as a fixative for some dyes. In low concentrations, it is the principal active ingredient in progressive types of hair colouring dyes. Lead(II) acetate is also used as a mordant in textile printing and dyeing, and as a drier in paints and varnishes. It was historically used as a sweetener and preservative in wines and in other foods and for cosmetics. Production Lead acetate can be made by boiling elemental lead in acetic acid and hydrogen peroxide. This method will also work ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engineering is the field dedicated to controlling and preventing corrosion. In the most common use of the word, this means electrochemical oxidation of metal in reaction with an oxidant such as oxygen, hydrogen or hydroxide. Rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. This type of damage typically produces oxide(s) or salt(s) of the original metal and results in a distinctive orange colouration. Corrosion can also occur in materials other than metals, such as ceramics or polymers, although in this context, the term "degradation" is more common. Corrosion degrades the useful properties of materials and structures including strength, appearance and permeability to liquids and gases. Many structural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Civilization
A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). Civilizations are intimately associated with additional characteristics such as centralization, the domestication of plant and animal species (including humans), specialization of labour, culturally-ingrained ideologies of progress, monumental architecture, taxation, societal dependence upon farming, and expansionism. Historically, a civilization has often been understood as a larger and "more advanced" culture, in implied contrast to smaller, supposedly less advanced cultures. In this broad sense, a civilization contrasts with non-centralized tribal societies, including the cultures of nomadic pastoralists, Neolithic societies or hunter-gatherers; however, sometimes it also contrasts with the cultures found within civilizations themselv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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