| Papers [49-60] of 299 :: [Page 5 of 25] | | Go to page : <— 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 —> | |
|
|
Chemical Polarity, 2004.
An overview of the importance of polarity in bond formation.
1,956 words (approx. 7.8 pages), 6 sources, MLA, $ 62.95
»
Click here to show/hide summary
Abstract
This paper examines polarity, the unequal distribution of charges, and how bond formation and, hence, compound formation largely depends on it. It looks at how all properties of chemical compounds largely stem from their relative polarities and how life would not exist without elemental polarities. It provides a basic explanation of the different types of bonding between elements, such as ionic and covalent, as well the importance of these bonds in the creation of biochemical structures, such as proteins and DNA.
From the Paper
"Therefore, any molecule or ion (simple of complex) that has an internal unequal distribution of charges is a polar molecule. This is the definition of polarity. Since bond breaking or bond formation and chemical reactions occur by means of electron transfer, the availability (or lack thereof) of electrons and the ease in which one bond can break and another form depends on the polarities of the compounds involved. Every chemical reaction and every pharmaceutical product created depends on polarities and electron density distributions. Here is an example of electron transfer: nucleophilic substitutions reactions."
| |
|
Witchcraft and Science, 2004.
Compares the Salem witch trials to the experience of those in modern society who are attempting to break into a career field dominated by one particular caste.
4,423 words (approx. 17.7 pages), 12 sources, APA, $ 116.95
»
Click here to show/hide summary
Abstract
This paper compares at the experience of women accused of witchcraft in Europe in the 17th century to the experience of women in contemporary society trying to break into the field of science. The paper contends that women of the 17th century, who practiced medicine through their knowledge of herbs and natural healing methods, were perceived as a threat to the male-dominated field of medicine and society at large. It is also argued in this paper that women in science today are faced with the same set of beliefs and barriers that held the women of the 17th century back from their equal status.
From the Paper
"Whenever one group of people obtain a majority interest in social order over another particular group, or over all other groups, the cries of outrage and abuse will soon be heard from both the dominant and the oppressed. The oppressed people of the group often have a legitimate point of contention. Possibly they were not the fastest to secure economic prominence, and therefore as the poor, they now need assistance to keep up with the leaders. Perhaps they simple lost a number of competitions, and became the follower rather than the leaders. In any case, those who are now in the position of following eventually begin to question the established social order. In order to bring about change, they often cry ?discrimination? or ?prejudice? of some other emotionally charged epithet in order to gain the public?s support for their self induced plight."
| |
|
Chromatography, 2004.
An overview of chromatography and outline of its history.
803 words (approx. 3.2 pages), 3 sources, MLA, $ 28.95
»
Click here to show/hide summary
Abstract
This paper looks at chromatography, an analytical technique based on the principle of selective adsorption that is used for the chemical separation of mixtures and substances. It examines how it is an important field of chemistry, which deals with the separation of pure substances from complex mixtures, and is widely used in the analysis of foods, drugs, blood, petroleum products, and radioactive-fission products. It also examines how variants of ?column? chromatography have been developed since its discovery in 1906, including partition, liquid, paper, thin-layer, and gas-liquid chromatography.
From the Paper
"Chromatography was discovered in 1906 by the Russian botanist Mikhail Tswett who first coined the term (derived from the Latin for ?color writing?). The technique used by Tswett for separating the pigments (chlorophyll) of plants consisted of pouring petroleum-ether extract of green leaves over a column of powdered calcium carbonate in a vertical glass tube. As the solution seeped through the column the individual components of the mixture moved downward at different rates of speed, and the column became marked with horizontal bands of colors. Tswett did not enjoy a happy relationship with fellow scientists of his time, as they derided his results, and his technique, with Tswett responding in kind. As a result, it wasn?t until the 1930s that his methods were accepted as a breakthrough in chromatography."
| |
|
Sweetening Natural Gas, 2004.
Describes the most chemical process most commonly used for sweetening natural gas.
7,305 words (approx. 29.2 pages), 19 sources, MLA, $ 162.95
»
Click here to show/hide summary
Abstract
This paper begins by illustrating the process most commonly used to remove hydrogen sulfide from natural gas. The paper then goes on to describe an alternative method used for the removal of hydrogen sulfide and describes the benefits of this method, as well as some of the problems associated with it. Additionally, the paper points out that the water content of natural gas is an important engineering consideration concerning the sweetening process and presents an overview of the properties of pure acid gases and water and hydrogen sulfide. The paper then goes on to outline and explain additional processes and engineering considerations concerning the removal of hydrogen sulfide and includes some cost estimates and comparisons of the processes.
Properties of H2S and CO2
Vapor / Liquid Properties of Pure Compounds
Vapor / Liquid Phase Behavior
Acid Gas Compression and Dehydration
Metallurgy
Acid Gas Dehydration
Acid Gas Injection Facilities
Cost Comparisons with Small Scale Sulfur Recovery Options
Operating Costs
From the Paper
"Sour natural gas contains hydrogen sulfide (H2S), which has to be removed to meet specifications for sales gas. Sour natural gas also contains carbon dioxide (CO2). The removal of CO2 and H2S, usually called acid gases, from sour natural gas is generally accomplished by means of a regenerative solvent. There are several amine solvents used for this purpose. Upon regeneration of the solvent, the acid gases are liberated, and are usually sent to a modified Claus plant, where the H2S is converted to elemental sulfur (Canjar & Manning 1967). The acid gas stream to the modified Claus plant consists of H2S, CO2, water vapor and minor amounts of hydrocarbon gas."
| |
|
Wine Making, 2004.
An overview of the process of wine fermentation.
879 words (approx. 3.5 pages), 3 sources, MLA, $ 31.95
»
Click here to show/hide summary
Abstract
This paper looks at how wine making is an ancient but evolving art and science and how only recently have vintners and scientists alike been able to understand and, therefore, control the actions of yeast on the fermentation process. It discusses the whole fermentation process from the different stages of fermentation to the different strains of yeasts and catalysts used.
From the Paper
"Fundamentally, fermentation occurs when sugars are transformed into alcohol, carbon dioxide, and some chemical by-products. In the case of wine, the carbon dioxide is released. The entire process involves no fewer than thirty chemical reactions (Peynaud 94). Yeast catalyzes fermentation. During the initial stage of wine fermentation, which lasts up to one week, the winemaker will leave the vessel open to the air. Thus, primary fermentation is aerobic, which allows the yeast to multiply in number instead of getting to work on the conversion of sugars into alcohol. Especially within the first few days of fermentation, yeasts concentrate almost all their energy on reproduction. Biologically, winemaking yeasts reproduce by budding or by the formation of spores. Saccharomyces yeasts reproduce by budding."
| |
|
Preservation of Library Materials, 2002.
A look into the technology behind the preservation of paper library materials.
2,314 words (approx. 9.3 pages), 5 sources, MLA, $ 71.95
»
Click here to show/hide summary
Abstract
This paper discusses the importance and value of the preservation of library materials. It then discusses how this is done, including the technological process. The writer further examines how this process has evolved and advanced over time.
From the Paper
"Since the beginnings of the library system in the United States, many methods have been devised for the preservation of library materials, such as books, manuscripts, autographs and related ephemera, prints, maps, paintings, photographs, movie film, sound recordings and videotape/DVD's. Some of these specialized techniques have been highly successful, while others have often failed to preserve certain items in their original, pristine conditions. As Caroline Horton points out, items of special value held in library collections "require the skills of trained conservators, for the vast majority of materials deteriorate rapidly" (167), not to mention the skills and talents required to preserve common items that are usually part of the circulating system of any public or academic library."
| |
|
Androstenedione, 2002.
An examination of the chemical makeup of the drug androstenedione and a discussion of the pros and cons of its use.
1,537 words (approx. 6.1 pages), 10 sources, MLA, $ 50.95
»
Click here to show/hide summary
Abstract
This paper looks at the muscle building synthetic hormone called androstenedione or androstenediol, also nicknamed ?andro? which became the first in a list of performance-enhancing substances called pro-hormones. It is called a pro-hormone because it is a precursor to testosterone and metabolizes directly into testosterone and is commonly used by athletes. It analyzes the so called beneficial effects which make ?andro? attractive to males of different persuasions with (mostly) cosmetic, non life threatening problems and how research has shown that the negative effects far outweigh the potential benefits. It looks at how aggressive behavior, mood swings and bad moods are commonly reported side effects of androstenedione as well as hair loss, blurred vision, acne, enlarged breasts, shrunken testicles and rarely, liver cancer.
From the Paper
"Androstenedione is also naturally produced by the adrenal gland in humans. Androstenedione was first synthesized in 1935. (Ruzicka and Wettstein, 1935) In 1936, world expert on steroid hormones, Dr. Charles Kochakian, was the first to show that androstenedione produced both androgenic and anabolic effects. But the anabolic effects were significant only in castrated dogs, and even then were much weaker than effects of testosterone. (Kochakian and Murlin, 1936) Its variants are commonly found in the pollen of Scotch pine trees. Androstenedione, when taken orally, will increase blood levels of both Androstenedione and testosterone. According to the German patent given for Androstenedione, 50mg given orally to men raised plasma testosterone levels up to 20 per cent; 100mg raised levels higher than 35 per cent. Blood levels start rising about 15 minutes after oral administration and stay elevated for around three hours."
| |
|
Air Pollution, 2002.
An examination of the effect of different gases on the quality of air and on the population's health.
11,025 words (approx. 44.1 pages), 2 sources, MLA, $ 217.95
»
Click here to show/hide summary
Abstract
This paper provides a detailed analysis of several gases and chemicals which are present in the air we breathe and how these are causing adverse effects on our health. It explains that air pollution created by humans is the most dangerous and discusses possible ways to reduce this phenomena.
Outdoor Air Pollution
Ozone
Nitrogen Dioxide
Sulphur Dioxide
Acid Aerosols
Particulates
Air Toxics
Carbon Monoxide
Lead
Asbestos
Asbestos: Health and Exposure
Potential Effects of Outdoor Air Pollution on Health
War: Detrimental Consequences and Air Pollution
War Gases
Classification of War Gases
Asphyxiants (Irrespirable Gases)
Sewer Gas
Emphysema
From the Paper
"The air that surrounds us is a mixture of 78 percent nitrogen; 21 percent oxygen; less than 1 percent of carbon dioxide, argon, and other gases; and varying amounts of water vapor. Any other particles, gases or unoriginal constituents hanging in the air which are not part of its original composition are called ?Pollutants? and this kind of air is called
Polluted Air. Even inhaling small amounts of such air pollutants can have serious effects on one?s health and leads to environmental problems. We can see some air pollutants such as the reddish-brown haze in smog; however, other air pollutants, including some of the most dangerous, are invisible.
Air pollution can be natural or human-made. Air pollution occurs naturally during volcano eruptions, forest fires, or dust storms. This has been an occasional problem for humans. However, during the past hundred years, air pollution created by humans has become a major, persistent problem."
| |
|
Organic Chemistry, 2002.
An explanation of the makeup of different hydrocarbons.
1,719 words (approx. 6.9 pages), 6 sources, MLA, $ 55.95
»
Click here to show/hide summary
Abstract
This paper discusses the differences between organic and inorganic chemistry and provides a brief insight into organic chemistry and the family of the hydrocarbons. It looks at how the salient point to remember in the formation of compounds (everything else flows from there) that drives chemical processes is the need to complete the valence or the atomic shell of each element?s inherent instability. It shows how inorganic and organic chemistry are the results of variable approaches to solving the instability and how this then results in the formation of the stable compounds that the world we live in and the universe at large need to survive.
From the Paper
"The arrangement of the four electrons around the carbon lend it a tetrahedral (equal on four sides in three dimensions) geometry. The simplest organic compound is methane (inflammable gas found in sewers and coal mines) where a single carbon atom is covalently linked to four hydrogen atoms. In this way, each hydrogen atom can claim two electrons needed to complete its shell (its own and one from carbon). The four carbon electrons and one each from the four hydrogen atoms complete its shell of eight. If one considers a chain of carbon atoms linked together carbon to carbon (C-C) with associated carbon to hydrogen (C-H) bonds, an organic molecule is formed. These compounds are straight chains, rings, or chains with cross- links and branches."
| |
|
Biologically-Active Natural Products, 2002.
This paper discusses the isolation and structural determination of biologically-active natural products by using various chromatographic techniques.
8,750 words (approx. 35.0 pages), 35 sources, APA, $ 183.95
»
Click here to show/hide summary
Abstract
This paper explains that nature acts as a pharmacy, offering us products, from the forest pharmacy and the pharmacy below water, with which we can heal ourselves: For example, aspirin, quinine, cyclosporins, and penicillin. This paper details the techniques that are available to researchers, to collect samples of natural products from the wild in a systematic manner, to extract compounds from these samples, to isolate the biologically-active compounds within these extracts, to characterize the biologically-active compounds chemically in terms of their structure, to evaluate the biologically-active compounds biologically, to determine potentially useful therapeutic effects and finally the methodology necessary to take these compounds to clinical trial. The author stresses the importance of finding new and more effective drugs to fight against bacterial infections and cancer. Outline.
Table of Contents
Introduction
Nature?s Pharmacopeia.
The Isolation of Biologically-Active Compounds and their Extraction Identification: Techniques
Introduction
Chemical Extraction
Biological Evaluation
Chemical Analysis
Chromatography
Solid Phase Extraction
Paper Chromatography
Thin Layer Chromatography
Flash Chromatography
High Performance Liquid Chromatography
Central Counter Current Chromatography
Determining the Chemical Structure of Compounds Isolated by Chromatography
Nuclear Magnetic Resonance
Mass Spectrometry
Drug Development
Examples of the Isolation and Identification
An Example of Extraction, Isolation and Chemical Characterization of Biologically-Active Compounds from Larch Wood
Biologically-active Compounds from Marine Organisms
What Compounds Have Been Isolated From Marine Organisms?
Biologically-Active Anti-Cancer Compounds ? Testing for Human Safety
Conclusion
From the Paper
"Chromatography is the process whereby two or more compounds or ions are separated through the distribution of the compound or ion between two phases, one that is mobile and the other which is stationary. These two phases can be of any combination: liquid-liquid, solid-solid, solid-liquid or gas-liquid, gas-gas, or gas-solid. There are many specific techniques for chromatography, some of which will be described below, and all follow the same basic principles. All forms of chromatography involve a rapid and dynamic equilibrium of molecules between the two phases, either free ? mobile - or absorbed ? stationary. Molecules will constantly move back and forth between the free and absorbed states, with millions of molecules absorbing and desorbing every second. The equilibrium between these states depends on three factors: the polarity and size of the molecule, the polarity of the stationary phase, and the polarity of the solvent. Thus, three different variables can be changed in chromatography, which can change the equilibrium between the stationary and mobile phases: this allows one to choose mobile and stationary phases that will separate just about any combination of compounds."
| |
|
Isolation of Esherichia coli Bacteriophages from Sewage, 2002.
This paper is a laboratory experiment using sewer water, which contains a large concentration of E.coli, to locate the bacteriophage to be isolated.
1,215 words (approx. 4.9 pages), 2 sources, $ 41.95
»
Click here to show/hide summary
Abstract
This paper reports on an experiment in which, using sewage water to locate the E.coli bacteriophage, the bacteriophage was isolated from the original culture and placed in an enriched medium to grow and reproduce. The author continues that each one of the plaques represents a viron from the original culture, and, by counting the plaques, they were able to determine the concentration of bacteriophages in the culture. The author reports that findings among the different lab groups differed significantly, but this could be explained by the fact that the experiments were performed on separate days a week apart.
Table of Contents
Abstract
Introduction
Materials and Methods
Results
Discussion
From the Paper
"E.coli was grown for 48 hrs in TSB tubes at 37degrees C by the lab assistant. (Sewage from the Cheney Sewage Works.) The sewage was then centrifuged and the bacteria containing portion was filtered using a 100 mL filter apparatus. I picked up my E.coli and filtered sewage from the lab assistant. Next, I gathered 7 plates of triptocase soy agar. These were labeled 1x10^-3 to 1x10^-9 and placed into the incubator to bring their temperature up to that of the bacteria/phage solution to be added later. 9 Eppendorf tubes were labeled 1x10^-1 to 1x10^-9, these were then set aside. Sterile saline was then gathered and using a Beckman autopipetter. I transferred 900 uL of sterile saline into each Eppendorf tube."
| |
|
The Periodic Table, 2002.
A brief look at the history and components of the chemistry periodic table. Includes a chart.
1,052 words (approx. 4.2 pages), 3 sources, MLA, $ 36.95
»
Click here to show/hide summary
Abstract
This paper begins by providing background information about the history and development of the periodic table. It mentions the first component discovered and the main people involved in developing and compiling the table in the mid-1800s. The paper then analyzes different families or groups in the periodic table - hydrogen, metals, noble gases, non metals and transition metals.
From the Paper
"The organization of the modern periodic table is perhaps one of the most significant tasks undertaken in chemistry. From this chart, we see the common properties of certain elements as well as glimpse into the atomic structure of the atom. It is the purpose of this paper to introduce the periodic table and briefly discuss its parts."
|
|
|
