From the Paper "Peptides were first synthesized around the turn of the century. During the following decades, the compounds found many applications. At present, both solid and liquid phase methods may be used to chemically formulate peptides. The formation of a peptide bond requires both activation and protection. Although these processes have a long history, researchers continue to search for better coupling reagents and improved protecting group strategies.
Curtius (1881) and Fischer (1902) were the first to synthesize simple peptide derivatives (2:1-8). About that time, Hofmeister (1902) and Fischer (1906) additionally recognized that proteins actually consist of amino acids linked together by amide bonds. Subsequent peptide research generally involved the..."
From the Paper "Compared to most other materials, plastics have been introduced relatively recently. In fact, many of the major developments in plastics technology have occurred over the last 50 years. One plastic that currently finds widespread application in the construction industry is polyvinyl chloride (PVC). Although PVC has been around for over 100 years, it wasn't developed commercially until about the 1930s. The pure resin consists of a linear polymer. The compound's chlorine atoms cause considerable inter-chain attraction. Hence, in its pure state, the material is hard and rigid. With modifying agents, however, PVC can be softened to produce an entire array of flexible products. Indeed, the substance may be the most versatile of the plastics. PVC is currently found in cable..."
From the Paper "Many fundamental concepts in chemistry can be traced back to Friedrich W"hler. A mild-mannered scientist, W"hler's discoveries revolutionized the understanding of organic chemicals. His artificial synthesis of urea eventually led to the overthrow of the theory of vitalism. In addition, W"hler contributed to ideas on isomerism and organic radicals. His work has ultimately had a great influence on the development of many fields of scientific endeavor.
A quiet, gentle person, Friedrich W"hler combined his "passion for chemistry" with a "great love of the open air, the beauties of nature and of all living things" (Findlay, 1965, pp. 323-324). Indeed, that branch of chemistry dealing with compounds of carbon is widely considered to have been started by..."
From the Paper "Organic chemistry is the study of carbon compounds. Carbon compounds are central to the existence of every life form on earth. They make up the muscles of animals and human, the stems and leaves of plants, the molecules that transfer genetic information, protective clothing, hydrocarbons that breakdown to provide the energy for transport, and perhaps most important the food products for nutrition. In this paper, aspects of the relationship between organic chemistry and the three major food groups - carbohydrates, lipids and proteins - are explored.
An enormous amount of time and energy is spent preparing and eating the food that sustains and maintains human health. Consuming food is pleasurable and culturally significant, as exemplified by the holiday meals at Christmas, Hanukah, and the celebrations at wedding receptions. As a result of the abundance.."
Abstract Examines the structure, chemistry and biological activity, focusing on antioxidant and anti-carcinogenic properties in animal systems.
From the Paper "Beta Carotene
The carotenoids as a group, and specifically the beta carotenes, are known to serve a variety of functions in living cells. Presented here is an overview of the structure, chemistry, and biological activity of beta carotene, with emphasis on its capacity as an antioxidant and anti-carcinogen in animal systems.
Beta carotene is a member of a class of pigments called carotenoids, which occur naturally in plants and are found as well in animals. A precursor of vitamin A, also called provitamin A, it is found as an orange-red pigment in terrestrial plants, algae and some marine mammals. After purification, it appears as ruby-red crystals, easily oxidized on contact with air, with MP 184 degrees, MW 536.44. It is insoluble in water, slightly soluble in alcohol, soluble in chloroform, carbon disulfide, ether and benzene. Its ..."
Abstract Matrix management is associated with a matrix organizational form. A matrix form of organization is an organizational structure with two or more (a) channels of command, (b) lines of budget authority, (c) sources of performance reward, and (d) so forth.
From the Paper "Methods of Reducing Porosity In Brass
Introduction. Matrix management is associated with a matrix organizational form. A matrix form of organization is an organizational structure with two or more (a) channels of command, (b) lines of budget authority, (c) sources of performance reward, and (d) so forth. A lack of maximal density, or some porosity, must exist in the metals' lattice structure or must be introduced in the alloying process. Explored here are methods metallurgists may use to minimize porosity in brass.
Brass. A useful alloy of two metals, copper and zinc (9:166), brass has been formed for cultural uses and ornamentation since the 13th century BC (1:9). The term, brass, indicates any of an infinite possible set of mixes of "copper-..."
From the Paper "Effects of Alcohol on Taste and Smell
Introduction
The purpose of this paper is to examine the effects of alcohol on people's perception of taste and smell. The paper begins with a brief description of the impacting factor (alcohol) and how it operates. It then goes on to discuss the affects of alcohol at the first and second levels of perception of taste and smell. The final section of the paper presents a several conclusions formulated on the basis of the reviewed literature.
The Impacting Factor: Alcohol
Definition and Operation
Alcohol is the term used to refer to any class of organic compounds characterized by one or more hydroxyl (OH) groups attached to..."
Abstract This paper examines how fundamental the principles of thermodynamics are to pharmacy. The paper covers the topics of Gibbs free energy change, heat of formation, partial molar free energy, energy change and entropy, and discusses how all these are important in pharmaceutics in deciding drug delivery and dosage form. The paper presents the reader with a clearer insight into how important the above are, with extensive explanations into the three laws of thermodynamics and how they all help the modern day pharmaceutical scientist. Many of the complicated calculations involved in thermodynamics are exemplified through examples.
From the Paper "A pharmacist is regarded as a professional scientist. Thus he is expected to know more than ever, is a thorough knowledge of thermodynamics. This discipline forms a rudimentary backbone of most of the material sciences as many other disciplines do "borrow" heavily from this. 1,3 In studying thermodynamics, it attempts to integrate the factual knowledge of pharmacy and it aids the pharmaceutical scientist to predict the solubility, stability, feasibility, compatibility and biological action of drug products fairly accurately. Processes such as partitioning of solutes between immiscible solvents, the solubility of drugs, micellisation and drug-receptor interaction can all be treated in thermodynamic terms. 1Thermodynamics is concerned with the quantitative relationships between heat and other forms of energy, including mechanical, chemical, electric and radiant energy. 1The main feature to remember in the study of thermodynamics is that it is not possible to know the absolute value of the energy of a system but it is possible to record changes in energy that happen when a system undergoes transformation."
Abstract This paper discusses how ever since the "Thalidomide" incidence last century there has been an ever-increasing amount of resources injected into optical isomeric research and in attaining pure enantiomeric products. It shows how due to different stereochemical characteristics, different isomers will have different interactions with biological receptors in the body, giving rise to different actions. A resultant undesirable effect is therefore inherently possible upon the consumption of chiral drugs, for that reason it is imperative that the end drug mixture is as entiomerically pure as possible. It describes the 3 basic methodologies for single enantiomers: chirality pool, kinetic resolution and asymmetric synthesis and examines the basis of and the techniques of separating them.
From the Paper "One way of the use of chirality pool molecules merely requires the maintenance of pre-existing chirality throughout a synthesis, with transformation of other parts of the molecule by formation of new chemical bonds or inter-conversion of functional groups. Otherwise, utilising chirality pool can afford a so-called "control element" for the creation of new stereogenic centres by "substrate-directable" reactions. Such reactions may involve complete transfer of chirality from one region to another intra-molecularly.[1]"
From the Paper "The history of chemistry involves a journey from its magical and mythological origin to the highly complex and analytical science that it is today. Chemistry, the science which explains the composition of matter and the changes that different forms of matter undergo, did not gain much momentum until the seventeenth century. Prior to the 1600s, the study of chemistry languished in a pre-scientific period, suffering from some prominent misconceptions and untenable theories. Advances made in the nineteenth and twentieth centuries have brought chemistry to such an advanced state that we are able to examine the composition of material on an atomic, and even a sub-atomic level.
Beginning with the use of fire, humans have observed the transformation of matter. Fire burns wood to produce ash, and meat becomes cooked over flame. These changes, known to..."
An overview of the major concerns of this scientific field including chemical change, classification of matter, laws, gases, atomic mass, formulas, periodic table, ionic compounds, acids and bases.
3,600 words (approx. 14.4 pages), 3 sources, 1992, $ 127.95
From the Paper "Chemistry is a branch of science that is used to explain and reveal the composition, structure, and properties of substances and to demonstrate the changes that they can undergo. For example, interaction with other materials can cause substances to acquire different properties, such as a change in physical form. Therefore, a large part of chemistry is observation--before, during, and after change takes place. There are three fields of study in chemistry--organic, inorganic, and physical chemistry. Organic chemistry deals with the study of compounds made up from carbon forms, such as those found in living beings. Inorganic chemistry covers compounds not found in plants or animals and therefore classed as inorganic (noncarbon compounds). Physical chemistry addresses the actions of chemistry that are resolved using the laws of physics."
Arsenic has always had an evil reputation. Its use as a homicidal and suicidal agent is widely known. In addition, more recently, its potential for causing harm in the environment is being realized. Abundant studies establish a relationship between arsenic and certain types of cancer. As a contaminant in drinking water, it poses a significant threat to human health.
The alchemists' symbol for arsenic is a coiled serpent (Levander et al., 1977, p. 1). The chemical is famous for its poisonous attributes. Less well.known, however, is the fact that arsenic has also been used as a therapeutic "tonic." For hundreds of years, patients received arsenic for conditions ranging from acute infections to epilepsy, and asthma (Bickley & Papa, 1989, p. 378). Furthermore, both inorganic and organic..."
From the Paper "Only relatively recently has importance of free radicals gained widespread acceptance. This may be the result of the compounds' inherent intangibility. They are generally short.lived, hard to work with, and difficult to study. Regardless though, it is now confirmed that low levels of free radicals are normally produced as a consequence of metabolic activity. It is also known that the compounds serve as potent biochemical mediators in a number of physiologic roles. However, their great catabolic potential does require focus and control. Unrestrained free radicals can significantly damage biological systems. To counteract such deleterious effects, defenses have evolved. Under normal circumstances, animal cells typically maintain an intricate balance between the generation of free
From the Paper "A common eukaryotic enzyme, calcium-dependent ATPase has been extensively investigated. The ion-transport enzyme uses energy derived from the hydrolysis of adenosine triphosphate (ATP) to move Ca2+ against a concentration gradient. Innumerable techniques have been applied to Ca2+-ATPase analyses. These have included proteolytic, genetic, immunologic, and molecular approaches.
Calcium-dependent ATPase was first isolated in 1970 (3:696-700). This heterogenous family of enzymes can be broadly subdivided into two separate groups. The plasma membrane Ca2+-ATPase occurs in most eukaryotic tissues. This 140-kDa enzyme binds calmodulin and is stimulated by calcium ion (10:285-297). Although it may be derived from plants, yeasts, or, for example,
Dichlorodiphenyl trichloroethane (DDT) is a nonsystemic contact insecticide. The compound has been employed against a variety of pests. Although DDT can be used to combat insect-transmitted disease, it's most common application is in agriculture. The chemical was widely utilized across the globe from World War II up until 1972. In that year, concern over the potential threat of environmental damage eventually caused the United States to restrict its use.
An organochlorine, DDT's chemical formula is C14H9Cl5. The compound can be variously described. In addition to dichlorodiphenyl trichloroethane, it is also known as the following: (1) p,p'-DDT; (2) 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane; and (3) 4,4'DDT. There are actually three ..."
