Abstract It also discussed its structure, and procedures, relating to its accreditation program through participating states and bodies. Other areas examined include on-site lab assessment procedure, lab accreditation process, fees, and lab quality systems. It also discussed the various methods used for environmental analysis, and finally addressed the growing issue of indoor air pollution in the United States.
Abstract It proceeds to discuss the types of chemical weapons, their physical and chemical properties and the significance of their usage. The paper also discusses the cut in the US Budget within the context of chemical weaponry and the influence of threats post-Gulf War and September 11 period.
Abstract This ten-page undergraduate paper addresses the effects of various gases like Oxygen, Nitrogen, Helium, Argon, Carbon Monoxide and Carbon Dioxide on divers under pressure. Also discussed would be the concepts of partial pressure and the bends followed by medical problems associated to pressure changes. Laws pertaining to pressure will be discussed too.
Abstract This essay talks about the biochemical nature of the enzyme lactase. It talks about it production, the reaction it catalyzes and the physiological effects of this enzyme, in particular the physiological effects of a deficiency of lactase.
From the Paper "Lactose is a disaccharide that is the principal carbohydrate found in milk and other dairy products. To digest lactose the enzyme lactase is required to catalyse the hydrolysis reaction to produce the monosaccharides glucose and galactose. This enzyme is usually present at birth but often decreases in activity as the child matures. The condition where an individual has a deficiency of lactase is known as lactose intolerance and produces symptoms such as nausea, cramps, bloating, gas, and diarrhea.
Abstract The mitsunobu reaction, discovered in 1967, involves the stereospecific reaction of an alcohol and a carboxylic acid in the presence of triphenylphosphine and diethyl azodicarboxylate (DEAD) to give an ester. This paper provides an overview of this chemical reaction and presents explanations via numerous diagrams and figures.
From the Paper "In 1976, it was found that the formation of nitriles is also easily reached when cyanide is used as a nucleophile under Mitsunobu conditions.10 Recently, however, acetone cyanohydrin has been used as a source of hydrogen cyanide for this reaction (see figure 7). With a comparable yield and a less toxic reagent, acetone cyanohydrin is a suitable replacement for HCN.11 In this system, similar to other Mitsunobu systems, sterically hindered secondary alcohols tend to give poor yields."
Abstract This paper examines Fragile X syndrome, also known as Martin-Bell syndrome, one of the most frequently inherited forms/causes of mental retardation. It looks at how the disorder is derived from a genetically inherited, single-gene mutation and how individuals who have Fragile X syndrome have symptoms that are resultant from a mutated gene on the X chromosome. It provides a short introduction, the genetics behind the disease, the mechanisms of the protein production and lack of therapy, diagnosis and symptoms.
From the Paper "The cause of Fragile X all boils down to a change in a single gene: an alteration in the Fragile X Mental Retardation 1 (FMR1) gene. The mutation inactivates the FMR1 gene, which in turn interferes with the process involved in regulating FMRP protein content. This gene is located on the X chromosome, hence the name Fragile X syndrome. Current research indicates that the FMRP protein assists in cellular communication.3 The sex chromosome alleles for males and females are XY and XX, respectively. This establishes an understanding that Fragile X syndrome, involving the X chromosome, is a sex-linked trait. Since males and females contain either one or two X chromosomes, either can pass on the mutated gene to their offspring."
Tags: chromosome, mental, retardation, martin-bell, protein, x, y
Abstract This paper describes dark energy, or anti-gravity, and debates theories of universe expansion, touching on Einstein's theory of relativity and cosmological constant. It also talks about the equation of state of the universe and its impact on universe expansion or contraction. It looks at how there are many theories about dark energy from the quintessence theory and the topological defect theory to the cosmological constant theory. It explains that, by analyzing the equation of state of this energy and evaluating current theories, scientists can construe a plausible theory for the fate of the universe.
From the Paper "Physicists started negotiating and theorizing about the possibility of a dark energy around the turn of the century. One generally un-disproved theory from that time is that which relates the equation of state to the "cosmological constant". The cosmological constant (often called lambda) was proposed by Einstein in 1917 to make the universe unchanging in his equations (5). He was generally unsure of this idea, and rejected this theory shortly after it was determined that the universe is perpetually growing. However, his idea of a cosmological constant is currently applied to the universe in a slightly different way, setting the equation of state constant (5)(4). The current theories of dark energy date back to 1998 when supernovae were discovered to be dimmer than expected."
A paper analyzing the physical and chemical properties of the lead (II) and lead (IV) halide compounds. Comparisons between compounds and applications are also discussed.
Abstract After a brief historical introduction to lead compounds, it explains what +2 and +4 cations are and examines their uses. The physical and chemical properties of the lead (II) halides are also discussed, with mention of "mixed" halides (e.g., PbFCl).
Outline
An Introduction to Lead
General Lead Dihalide Trends
Mixed Lead Halides
Lead Chloride
Lead Bromide
Lead Iodide
Lead Fluoride
Lead Tetrahalides
Lead Tetrafluoride
Lead Tetrachloride
Possible Lead Halide Application
From the Paper "Lead, located at the bottom of group IVA on the periodic table is well known for being a massive (atomic mass is 207.2 amu) and dense element. The density characteristics associated with lead arise from its rather compact structure despite its large size. This occurs in accordance to the periodic trend that atom size decreases as one moves left to right across a period. This trend, in conjunction with the massive properties found among the period six elements, accounts for the elements ranging from osmium to lead in that row being the densest (osmium does have the largest density) known to exist."
Abstract This paper discusses how magnesium chloride has become the de-icer of choice in snowy regions such as Colorado and how supporters of the product claim that magnesium chloride is an environmentally safer option for de-icing than some of its predecessors, namely, sodium chloride. It examines how the use of magnesium chloride in liquid and modified cold-pressed form has been shown to be highly effective as a tool for de-icing in Colorado. It also looks at how supporters of the use of magnesium chloride in Colorado have stated that the de-icer has proven beneficial to the environment, while others claim the use of magnesium chloride has been shown to possibly increase electrical outages and pole fires, as well as corrosion.
From the Paper "Another environmental issue facing Coloradoans resulting from the use of magnesium chloride is corrosion. The use of sodium chloride or rock salt in the past presented a much greater problem in this respect. Magnesium chloride however, is also by nature corrosive; however proponents of its use point out those chemical agents are added to it to minimize the corrosive effects (Pavek, 2002). Highway departments in the state of Colorado have noticed that the use of magnesium chloride as a de-icer has reduced much of the major corrosion on trucks and equipment, as well as steel enforced bridges compared to sodium chloride (Pavek, 2002). However, some reports are also indicating that aluminum components and electrical components in their vehicles are actually showing increased evidence of corrosion at a more rapid rate (Pavek, 2002)."
Abstract This work provides information on the properties of ionic liquids and explores how these unique properties can be used to conduct experiments that would not be possible without ionic liquids. The paper also examines the future potential of ionic liquids.
From the Paper "One of the principal driving forces for research in this area is the need to find replacements typical solvents because they are environmentally damaging. This is because they are used in large amounts and they are volatile. Ionic liquids are different from conventional liquids. They are not composed of molecules, polar like water or acetone, or even non-polar like benzene. These liquids are composed of ions. This class of compounds came into being since the 1980s. Since these are liquids, they have the potential to behave as solvents. Which means that potentially there are a million possible solvents that can be created. By combining different anions and cations, it is possible to create a huge library of different ionic liquids each with specific properties. There are at best, 300 organic solvents that are in use in chemical and pharmaceutical industry, today."
Abstract This paper explains that there are are two major types of water pollution treatment: physical and chemical. The paper goes on to explain the various methods of physical treatment, including filtration and air- or steam-stripping. Chemical treatments are for killing microbes in the case of bacterial pollution, but they may be used for altering the chemical makeup of the water to render it less harmful in the case of chemical pollution.
Contents
Three Major Problems
Sediments
From the Paper "Chemical treatments, generally, are for killing microbes in the case of bacterial pollution, but they may be used for altering the chemical makeup of the water to render it less harmful in the case of chemical pollution. Often, this sort of treatment is used to remove metal compounds from the water. Various materials such as dissolved iron or aluminum salts may be added to help the material to be removed either float or settle, again, depending on how it is to be ultimately removed.
Often, organic chemicals in water can be chemically destroyed by adding ozone or hydrogen peroxide. The ozone may also kill harmful bacterial, or chlorine may be added to do this. But of course, excess chlorine itself is harmful to aquatic life, so sulfur dioxide may then need to be added to make the "pure" water safe for discharge. Finally, chemicals may be added to water in a treatment system to help create thicker "sludge" so that the remaining water may be more easily removed."
Abstract A research paper on Equine Nutritional Secondary Hyperparathryroidism (NSH). Discusses causes of the disease, clinical symptoms, diagnosis, treatment, and prevention. The paper includes many references from medical and veterinary journals, Internet sites, and research on the topic. The writer also interviewed some experts in the field to gain an understanding on this disease.
From the Paper "Calcium and phosphorus, two very important minerals, make up approximately 70% of the total mineral content in the equine body. Most people, including young children, have seen the milk commercials on television that inform their viewer of the important role that calcium plays in creating strong, healthy bones. Calcium plays this role in many species and is especially important in large breed animals such as the horse, who is often asked to perform hard work and athletically challenging tasks. In addition to creating strong bones in the equine body, calcium is also important for several metabolic functions such as nerve conductions and muscle contractions. Without a sufficient amount of calcium, the horse's bones would grow weak and he would be at greater risk for injury. Due to the importance of these vital functions of calcium, the equine's body closely regulates the levels of calcium in the bloodstream. Vitamin D and hormones such as the parathyroid hormone (PTH) play an important part in maintaining adequate calcium levels in the blood stream. When there is not enough calcium in the horse's diet the PTH begins to break down calcium from the bones, which store 99% of the body's calcium, and moves it into the bloodstream. When there is a long-term deficiency of calcium in the equine's diet, significant re-absorption of bone can occur, which can lead to decreased bone strength and density, or abnormal bone formation. Many racetrack injuries, laminitis, and tendonitis have been attributed to inadequate calcium in the diet of young racehorses. Even if there is adequate calcium, a large concentration of other minerals such as phosphorus will decrease the absorption of calcium. Thus, there must be a balanced ratio of these minerals. If improper Ca:P levels in the diet continue for an extended period of time, serious problems such as nutritional secondary hyperparathyroidism will develop.
