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Chemicals such as some pesticides are not easily subjected to biodegradation due to their halogen content. A method to remove these halogens would produce products easier to biodegrade. Under anaerobic conditions, cobinamide, abiosynthetic precursor of vitamin B-12, is an effective catalyst in the dechlorination of Lindane (hexachlorocyclohexane). We are testing as catalyst several bacterial extracts from vitamin B-12 producer organisms. These extracts contain a mixture of several corrinoids. The purpose of these tests is to determine which extracts are the most effective in reducing CCI4 and other organohalides.
The mixture used for these assays is: 0.5 M aqueous Tris anaerobic buffer (pH 9.0), corrinoid extract (25 or 50 nmol), 0.1m DTT, and Dioxane (50% v/v). All reagents total 1.0 ml and are crimped sealed in a vial and incubated at room temperature in the dark from 10 to 60 minutes. The solutions are extracted with cold pentane and back extracted with 2% aqueous NaCl. The products are analyzed by gas chromatography. From 20% to 40% of the products have been identified as CHC13. Other possibilities not detected by our G.C. method are CH2 C12 and CH3-C1. [Supported by NIH-GM-08043.]
One of the interesting aspects in the car racing business is how to make the automobile lighter, stronger and faster. There are hardly any dramatic and stunning changes occurring at once, rather the evolution of these vehicles goes almost unnoticed. A clear example of this is my research, although it is a very interesting and challenging project the outcome will not be tangible in a sense.
I have chosen to investigate the possibility of optimizing the performance or substituting the material being used on a shaft for another that is lighter and/or stronger. The drive shaft is used for Indy Racing cars and is under great torsional stress. The shaft is driven by an 800 HP engine at 13,500 rpm. It is subjected to 1,500 to 2,000 lbf (pounds-force) of torsional stress.
The metal being used is known as 300 M, the shaft is one foot and a half in length with a diameter of .825. In recent tests a line has been drawn along the shaft to see how much it actually twists, the results being that it has actually twisted twice around itself making the necessity to replace it important.
There are a number of alternate materials, although I will specifically concentrate on comparing 300 M with two metals. One is known as Aermet 100, this metal is relatively new and therefore expensive, the other alternative is 434O, a metalthat is more common but is also known for its strength. We are interested in the mechanical properties of the metals and how they behave under certain conditions.
Activated carbons are one of the principal absorbents used in wastewater treatment. These adsorbents consist of microcrystalline material made by thermal decomposition of wood, vegetable shells and coal. Its surface consists ofseveral pores which are used for adsorption. The use of activated carbon for removing dissolved organics from drinking water and wastewater has long been known as being feasible. Thus, the pore size distribution on the surface of activated carbon and the equilibrium isotherms of four types of carbon are investigated. This information is used to optimize the design and use of activated carbon columns for treatment in industrial and municipal wastewater.
The instability of a plasmid (8.5 kb) carrying chloramphenicol (Cm) resistance in Lactobacillus was investigated. Besides this plasmid, the strain also carried two other plasmids of 10.6 and 6.5 kb sizes. When the bacterial culture was treated with acriflavine, 13 to 18 percent of the population showed sensitivity to Cm. All the sensitive variants were isolated, purified and tested for sensitivity to Cm by plating 0.1 mL overnight culture on MRS agar plates containing 30 microgram of Cm per milliliter. The parental strain was a maltose fermenter. So all the Cm-sensitive strains were tested for their ability to ferment maltose. Twenty-eight percent of the Cm-sensitive variants showed loss of the ability to ferment maltose. The loss of maltose fermenting ability of the strain can come by mutation of the gene that is on the bacterial chromosome.Acriflavine is a mutagenic agent. However the frequency of a single mutation is too high to account for the chemical mutagenesis. The other possibility is the effect of plasmid DNA. Experiments are under way to show how the plasmid can affect the expression of chromosomal encoded genes.
Clay beds are important to waste disposal sites because they can be manipulated to give a network of small pores which retard the flow of water and pollutants in water. In addition, they have swelling and shrinking properties which allow for the transport of pollutants. For example, porous, non-swelling clays such as Cologned (Ga) have holes or pores which enable diffusion of pollutants between non-uniform particles. Similarly, a swelling clay like Standard Wyoming Calcium Montmorillonite (SWy) allows pollutants between particles. However, because SWY particles swell, pollutants also have the option of moving into the particle. This investigation is important because knowledge of how pollutants diffuse through clay beds will aid in building better waste disposal sites.
In this investigation, Cologned and Standard Wyoming Calcium Montmorillonite clay were studied with clay-modifi edelectrodes and in different concentrations of a Ruthenium hexamine chloride solutions. The method for preparation of clay-modified electrodes was followed for this investigation as explained previously (Stein and Fitch). Single and two componentclay suspension contained only one clay type. The two component clay suspension contained a mixture of the two clays. The following percentages of two component clay suspensions were studied: 25/75 of KGa and SWy, and 75/25 of KGaand SWy, respectively. Experiments were performed on the single component clay suspension and the two component clay suspension in triplicate for 45 minutes.
Our investigation of a mixture of these clay types found a difference in response to low and high concentrations of the Ruthenium hexamine chloride solution. Also, the amount of each clay type determined the amount of transport of the complex through the clay.
A number of strains of Leuconostoc species from our culture collection were tested for the antagonistic effect again stlactic acid bacteria. One strain showed high activity against a strain of Lactobacillus. The Leuconostoc strain was then grown overnight in (16-18h) in MRS broth at 30 C. Cells were harvested by centrifugation. The pH of the supernatant (4.1) was adjusted to 2.0, 7.0 and 11.0 with Hol or NaOH. All four samples were filter sterilized and kept at 4 C. They were then tested on the tester strain. All except the sample at pH 11.0 showed zones of inhibition indicating that inhibition of the tester strain is independent of pH and the activity is destroyed by highly alkaline pH. The loss of activity was irreversible since the readjustment of the pH to 7.0 did not restore the activity. Heat treatment (autoclave for 15 min.) did not affect theactivity of the filtrate. The activity was also completely destroyed by incubation of the filtrate with pronase, trypsin, alpha-chemotrypsin and papain suggesting that filtrate contains some protein or protein complex and is a bacteriocin. Plasmid and genetic characterization showed that a plasmid encodes the bacteriocin production gene. Experiments are under way to characterize this protein and the genes involved in the production of bacteriocin.
Aircraft flying at high angles of attack experience strong forces which may cause the pilot to lose control of the aircraft. Experiments in a wind tunnel with a stationary model have demonstrated the ability to control the side force with very low levels of suction. The same type of side force will cause an aircraft model in a wind tunnel to rotate on a sting, which is known as the coning motion. The same suction techniques were employed to control the rotation of the coning motion model with a tangent o-give type nose cone. Suction was applied through two holes located at the tip of the nose cone. Several experiments were performed involving different control settings and different wind tunnel speeds to explore and analyze the feedback from the model. The rotating rate data was acquired with an optical encoder located at the end of the shaft. The encoder measures angular velocity and angular acceleration. Two pressure transducers located at the nose cone provide the feedback signal to the control computer, which adjusts the suction in order to control the motion of the model.
This presentation of in-situ synthesis of silver sheathed superconducting T1-1223 tape contains several attemptable goals that must be reached in order to optimize the processing conditions for Tl-1223. Various synthesis routes were explored during the precursor synthesis. After mastering the precursor synthesis, the time, temperature and pressure variables were varied. These variables are crucial in reaching the superconducting phase. When the superconducting phase is reached, this work will address the lack of grain connectivity and the inherent "weak link" conditions that are prevalent in this compound. We shall present structural and electronic results in the studies so far carried out.
Vitamin B 12 belongs to a family of macrocyclic organics containing cobalt, called the corrinoids. We are studying epimers in this family. Epimers are stereoisomers differing in configuration at one carbon. In the 13-epicorrinoids, the side chain "e"attached to ring carbon #13 is projected up instead of down. We are interested in preparing and isolating neovitamin B12 (the B12 epimer at carbon #13) for use in studying the stereochemistry of this compound and of the related vitamin B12 precursors. The epimers were prepared following published methods (Bonnet, 1971) by dissolving vitamin B 12 in highly acidic solvents followed by purification using descending paper chromatography after reaction work up. The fractions were characterized using TLC, ascending paper chromatography and analytical electrophoresis. In the future, neovitamin B 12 will be converted to neocobyric acid, a precursor analog, for further study. [Supported by NIH-GMS-08043.]
Synthesizing uniform batches of the cuprate superconductor Yttrium Barium Copper Oxide is crucial in studying the surface properties of this material. The results of synthesizing several batches under varying conditions are reported. The surfaces of the batches were characterized using X-Ray Powder Diffractometry, Magnetic susceptibility (SQUID), Scanning Electron Microscopy (SEM), Nuclear Magnetic Resonance (NMR) and lodometric titration (for oxygen content).
Surface modification of the superconductor electrodes was carried out and cyclic voltametry was employed to study the efficiency of the redox-active adsorption process. We found preliminary evidence that the larger the substrate's crystal grain size the more ideal the electrochemical response.
In an attempt to find solutions to critical current density enhancement in Bi-2212 (Bi2 Sr2 Cal Cu2 Obl6), we have systematically substituted two different elements Niobium and Tantalum in different amounts. This was done in the hopes of finding pinning centers for the fluxoids. One result shows that Niobium exists in quantities as small as 0.05 grams.
