| Papers [267-280] of 299 :: [Page 20 of 22] | | Go to page : <— 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 —> | |
|
|
The Benefits and Uses of the Plant St. John's Wort, 2001.
An in-depth look at the composition, uses and effects of the plant such as clinical effectiveness.
1,210 words (approx. 4.8 pages), 5 sources, £ 25.95
»
Click here to show/hide summary
Abstract
This paper takes an in-depth look at the composition, uses and effects of St. John's Wort. The author explains the benefits of using St. John's Wort in clinical effectiveness such as treatment of depression, relaxant effects, antiviral and antibacterial actions, and treatment of burns and minor skin wounds.
From the Paper
"St. John's wort, or Hypericum perforatum, is an aromatic perennial native to Europe, parts of Asia and Africa, and the Western United States. It produces yellow flowers which bloom especially bright on June 24, the traditional birthday of St. John the Baptist, hence the name "St. John's wort". St. John?s wort is also known as "goat weed" or "klamath weed". The leaves and flowering tops of the plant yield about 0.1% hypericin, pseudohypericin, and related naphthodianthrones. Flavonoids such as amentoflavone, luteolin, kaempferol, and quercetin and the glycosides hyperoside and rutinoside have also been identified in Hypericum perforatum. "
| |
|
Electromagnetic Fields and their Effects on Health, 2000.
A look at current issues in toxicology such as EMF's and their effects on human health.
2,160 words (approx. 8.6 pages), 8 sources, £ 41.95
»
Click here to show/hide summary
Abstract
An in depth look at electromagnetic fields and their effects on health aspects such as breast cancer, leukemia, tumors and increase in hormone levels. The author argues that no clear evidence shows that EMF's do cause human health defects, yet many studies have proved to be inconclusive making EMF's potential harmful products that need further investigation.
From the Paper
"Electromagnetic fields, or EMF's, are invisible lines of force that surround all electronic devices and wiring. Researchers have explored the question of whether low- frequency electromagnetic fields can cause breast cancer, among other types of cancer, for roughly two decades now. Numerous studies have been conducted attempting to discover a link between EMF's and breast cancer, but most have been inconclusive(Rembert, 1997). They have neither come up with solid support for the hypothesis that EMF's cause breast cancer, nor managed to put it to rest(Taubes, 1997). There is no conclusive scientific evidence at this time showing a direct link between EMF's and breast cancer."
| |
|
Using Plants to Fertilize Plants, 2001.
A look at alternatives to chemical fertilizers.
2,068 words (approx. 8.3 pages), 8 sources, £ 39.95
»
Click here to show/hide summary
Abstract
This is a detailed and illustrated paper on using organic fertilizers instead of chemical fertilizers on plants. Results of experiments concerning this topic are included with the paper.
From the Paper
"Organic fertilizers can provide enough nutrients to plants, that is the reason why the plants can grow well. Also the organic fertilizers can change the structure of soil and create a good drainage system, and well-ventilated environment which can be a better place for microorganisms to survive. The organic fertilizers contribute a lot to the growth of plants, but they still have some disadvantages. If one adds too much organic fertilizers, the plants will die because the concentration of organic fertilizers is very high."
| |
|
The Atropine Molecule, 2000.
A look at the uses and structure of the Atropine plant.
1,355 words (approx. 5.4 pages), 5 sources, £ 27.95
»
Click here to show/hide summary
Abstract
This paper looks at Atropine the plant as drug and medicine under the following headings: Discovery, Extraction from its Natural Sources, Uses, Side Effects, Description of Structure.
From the Paper
"The medicinal properties of Atropine were discovered through Shamans or ?Medicine Men?. It is not known exactly when it was discovered, but the first recorded use of it was in 1676 when a group of soldiers in Jamestown went insane upon ingestion of the plant that contains Atropine along with other Tropane alkaloids. In 1968, over-the-counter remedies for asthmatic difficulties were banned after people began to use them recreationally."
| |
|
Vitamin B12 Model Compounds, 2000.
An experimental analysis for the purposes of studying cobalamins, a coenzyme of vitamin B12.
1,405 words (approx. 5.6 pages), 4 sources, £ 28.95
»
Click here to show/hide summary
From the Paper
"Three derivatives of cobaloximes 1 containing substituted alkyl groups linked to the cobalt atom were prepared. Cobaloximes are cobalt(III) complexes in which two dimethylgloxime anions chelate the metal and form hydrogen bonds to each other1. This results in a planar tetrahedral group surrounding the cobalt with two axial groups. One axial group is the base pyridine and the second axial group is an alkyl group. In this reaction the pH of the solution determined which derivative was prepared. The oxidative addition of the acrylonitrile ligand 2 to the reduced cobaloximes in neutral solution produced the alpha derivative. In basic solution the beta derivative was formed. The third derivative was formed with the deprotonation of the beta derivative, which then underwent oxidative addition to form the trans derivative. The spectra of the cobaloximes derivatives were recorded using infrared and 1H NMR. The spectra were in agreement with the proposed structures of the derivatives."
| |
|
Magnetism, 2000.
An experimental analysis of magnetic susceptibility.
1,543 words (approx. 6.2 pages), 4 sources, £ 30.95
»
Click here to show/hide summary
From the Paper
"The synthesis of a magnetic susceptibility standard proved to be Hg[Co(NCS)4] through mercury analysis and magnetic measurements. Magnetic susceptibility characterization of four nickel(II) complexes, Ni(Et2en)2Cl2-2H20, Ni(Et2en)2(NCS)2, Ni(Et2en)2(NO3)2, and Ni(Et2en)2I2, is reported. Et2en is a bidentate ligand, which is bonded strongly to the Ni(II) metal center.
Ni(Et2en)2Cl2-2H2O and Ni(Et2en)2(NCS)2 were both paramagnetic with two unpaired electrons and had Ueff values of 3.17 B.M. and 3.20 B.M., respectively. Ni(Et2en)2(NO3)2 and Ni(Et2en)2I2 were both diamagnetic with no unpaired electrons and had Ueff values of 1.80 B.M. and 1.71 B.M., respectively. The color of the compounds correlates with their magnetic properties, where blue to violet compounds are paramagnetic and yellow to red complexes are diamagnetic."
| |
|
Stereochemistry, 2000.
Stereochemistry of Co III trien X2 complexes and resolution of the Trien Co III enantiomers.
1,238 words (approx. 5.0 pages), 3 sources, £ 25.95
»
Click here to show/hide summary
From the Paper
"In this experiment three Co(III)trienX2 complexes were prepared. These complexes were cis-alpha-[Co(trien)Cl2]Cl 1, cis-beta-[Co(trien)Cl2]Cl-0.5H2O 2, and trans-[Co(trien)Cl2]Cl-1.5H2O 3. The trien ligand is a tetradentate ligand, which is a strong field ligand. Once the trien ligand is coordinated to the metal the molecule's energy is lowered due to the chelate effect. The three complexes were studied using infrared and UV/Visible spectroscopy.
Also prepared in this experiment was the cation [Co(en)3]3+ which has two enantiomers. The ligand ethylenediamine is a strong field ligand, which is bidentate. This ligand also lowers the energy of the molecule through the chelate effect. The chelate rings remove a center of inversion, which removes the chance of an improper rotation axis and leads to an optically active molecule. The optical purity of the two enantiomers was calculated by measuring their specific rotation using a polarmetry apparatus."
| |
|
Solid-Liquid Phase Diagram, 2001.
An experiment using a procedure known as thermal anaylsis.
1,820 words (approx. 7.3 pages), 3 sources, £ 35.95
»
Click here to show/hide summary
From the Paper
"A solid-liquid phase diagram was constructed for a naphthalene - diphenylamine system. The phase diagram was constructed using the procedure known as thermal analysis. Thermal analysis allows for the determination of phase boundaries. A graph of the phase boundaries was then plotted versus mole fraction of naphthalene. From the graph the eutectic composition of the system was determined to be 0.39 + 0.1 moles of naphthalene and 0.61 + 0.1 moles of diphenylamine. The ln of mole fractions of naphthalene were then plotted versus 1/Temperature and from these graphs the heat of fusion and melting temperature for Ha and Hb were determined to be 99.49 + 2.0 KJ/mol and 17.38 KJ/mol, respectively. The Ta and Tb were determined to be 29.0 + 2.0 oC and 81.4 + 2.0 oC, respectively."
| |
|
Scientific Experiment on Polyvinyl Alcohol, 2001.
Determination of the molecular weight of polyvinyl alcohol by viscosity.
1,244 words (approx. 5.0 pages), 2 sources, £ 25.95
»
Click here to show/hide summary
From the Paper
"Cleaved and uncleaved solutions of PVOH were involved in viscosity measurements. These measurements were undertaken so as to determine the molecular weight of the PVOH solutions. The apparatus constant for the Ostwald viscometer was calculated to be 1.435 x 10-4. The specific viscosity was also determined and used to plot graphs of hsp/c vs. c, and 1/c ln h/ho vs. c. From these plots the intrinsic viscosity was extrapolated to a concentration of zero.
The values of the molecular weights were averaged and reported for both the uncleaved and cleaved product. The values obtained for Mv were 26,731.3 g/mol and 4615.4 g/mol, respectively. The values obtained for Mn were 14145.6 g/mol and 2442 g/mol, respectively. The values obtained for D for all the graphs was 5.89 x 10-3."
| |
|
Liquid-Vapour Equilibrium of Acetone and Cyclohexane, 2000.
Analysis of a lab experiment on acetone and cyclohexane.
1,188 words (approx. 4.8 pages), 3 sources, £ 24.95
»
Click here to show/hide summary
From the Paper
"A phase diagram was constructed for an acetone - cyclohexane system. The phase diagram was constructed from the simple distillation of acetone and cyclohexane. Samples were taken of the liquid phase and vapour phase of both components. The refractive index was then determined for each sample. The data from the refractive index then allowed for the construction of the phase diagram. As determined from the phase diagram the boiling point of the azeotrope was 53oC and the percent mole composition of the azeotrope was 67.0 + 2.0% acetone and 33.0 + 2.0% cyclohexane."
| |
|
Cyanazine, 2000.
Extensive and illustrated examination of cyanazine.
2,486 words (approx. 9.9 pages), 13 sources, £ 45.95
»
Click here to show/hide summary
Abstract
This paper takes a look at the applications, characterization, adverse effects and toxicity of cyanazine.
From the Paper
"The use of herbicides has led to their detection in various parts of our environment. One particular herbicide, which has been found in our water, is cyanazine. The detection of cyanazine in our lakes and sources of drinking water is of great importance because it has the potential to affect numerous organisms and biological systems. Cyanazine is a selective herbicide, which is used to control annual grass and broadleaf weeds in a variety of crops1. Cyanazine is a member of the triazine herbicide family, and has been in use since 19713. At one time cyanazine was the fourth most widely used synthetic chemical pesticide in the United States3. Cyanazine may be released into the atmosphere by the application of the herbicide to a field or by vapor drift or through precipitation. Cyanazine once released to the environment will readily partition to water where it may be found in sources of drinking water."
| |
|
Analysis of Organotin Compounds, 1999.
A look at the chemicals used to make plastics and other important products.
1,883 words (approx. 7.5 pages), 1 source, £ 36.95
»
Click here to show/hide summary
From the Paper
"In recent years attention has been focused on the need to analyze organotin compounds. When tin is combined with materials that contain carbon, it is called an organotin compound and it is used to make plastics, food packages, plastic pipes, pesticides, paints, and pest repellents. Organotin compounds, specifically tributyltin and triphenyltin, should be regarded as highly toxic and when used in marine environments lead to severe problems for the local wildlife."
| |
|
Solubility and Ionic Strength, 2001.
A laboratory analysis concerning the solubilities of various solutions containing different ionic strengths.
1,722 words (approx. 6.9 pages), 2 sources, £ 33.95
»
Click here to show/hide summary
From the Paper
"Determined in this experiment were the solubilities and mean activity coefficients of various solutions containing different ionic strengths. These measurements were achieved by the simple distillation of calcium iodate solutions against thiosulphate and a starch indicator. The data obtained from these results led to the determination of the concentrations of the calcium salt, the concentration of the iodate salt, C, u, u1/2 and [2A(u)1/2]/[1 + B(u)1/2]. A plot of log10C versus [2A(u)1/2]/[1 + B(u)1/2] allowed for the calculation of K. The value of K obtained was 1.0789 x 10-6 + 0.0037. Three different values of the mean activity coefficients were tabulated. From the tabulated values it was observed that the experimental values were larger than the theoretical values."
| |
|
Absorption of Acetic Acid from Solution, 2001.
An experiment concerning the the Langmuir Isotherm.
1,522 words (approx. 6.1 pages), 2 sources, £ 30.95
»
Click here to show/hide summary
Abstract
The objective of this experiment was to determine the adsorption of various acetic acid solutions onto charcoal. This experiment obeyed the Langmuir isotherm because the plot of C/N versus C proved to be linear. This shows that the adsorption equilibrium is essentially ideal and there is a definite set of sites of adsorption.
|
|
|
