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Articles 2731 - 2757 of 2757

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Report On Water Pollution Problems In Las Vegas Wash And Las Vegas Bay, Environmental Protection Agency Nov 1971

Report On Water Pollution Problems In Las Vegas Wash And Las Vegas Bay, Environmental Protection Agency

Publications (WR)

This report was prepared by the Federal Water- Quality Administration, Pacific Southwest Region, now the Environmental Protection Agency (EPA), Region IX, at the request of the State of Nevada, Department of Health, Welfare, and rehabilitation. In a letter, dated December 5, 1969, this agency asked for technical assistance, as authorized by the Federal Water Pollution Control Act, in developing discharge standards appropriate for Las Vegas Bay, Lake Mead, and the Lower Colorado River. The subsequent study was performed by EPA from January through August, 1970. The establishment of Nevada State Water Quality Standards for these waters will enable responsible officials …


A Conceptual Draft Of A Dynamic Hydro-Biological Model For Lake Mead, L. G. Everett, Bureau Of Reclamation Apr 1971

A Conceptual Draft Of A Dynamic Hydro-Biological Model For Lake Mead, L. G. Everett, Bureau Of Reclamation

Publications (WR)

Food and energy transformation in an aquatic system must be understood in order to develop a simulation approach. This report provides a comprehensive study of an aquatic ecosystem. The objectives of this report are to show: (1) the biological relationships in an aquatic system (2) the role of nutrients in the biological cycle (3) the role of abiotic factors in a limnetic environment (4) the status of the art of "Eutrophication modeling".


Micronutrients And Biological Patterns In Lake Mead, Hasan K. Qashu, Lorne G. Everett, J. S. Carlson, Bureau Of Reclamation Jan 1971

Micronutrients And Biological Patterns In Lake Mead, Hasan K. Qashu, Lorne G. Everett, J. S. Carlson, Bureau Of Reclamation

Publications (WR)

Progressive increases in concentration of dissolved solids in the Colorado River water from Lake Powell to Imperial Dam seem to alter plankton dynamics and biological productivity of the river. Also, changes in biological productivity and micronutrients concentrations occur within the same reservoir. Development of a digital simulation model to predict micronutrients concentrations and biological productivity is necessary for diagnosing changes in plankton population and effluent-carrying capacity of the system. The objectives of the study are: (1) to determine trace metal balance at different locations in Lake Mead, (2) to measure biological productivity and conduct plankton population counts at each sampling …


High-Pressure Phase Studies On Sodium–Potassium Alloys, D. Ray Anderson, J. Bevan Ott, Rex J. Goates, H. Tracy Hall Jan 1971

High-Pressure Phase Studies On Sodium–Potassium Alloys, D. Ray Anderson, J. Bevan Ott, Rex J. Goates, H. Tracy Hall

Faculty Publications

The solid–liquid phase diagrams were investigated to 60 kbar for elemental sodium, potassium, and various sodium–potassium alloys. The data for Na and K are in general agreement with those of earlier workers. In the alloy system the temperatures of both the peritectic and eutectic halts increase as the pressure increases, but with different slopes, so that the two invariant points merge at approximately 35 kbar. Above this pressure, two halts are again observed. One increases with increasing pressure, and the other decreases with increasing pressure up to 55 kbar, where it abruptly starts increasing again. Melting points for samples in …


The Enzymatic Oxidation Of Aldehydes By Xanthine Oxidase, Duane Beal Gregory Jun 1970

The Enzymatic Oxidation Of Aldehydes By Xanthine Oxidase, Duane Beal Gregory

All Master's Theses

As early as sixty years ago, the existence of an enzyme from mammalian tissues which catalyzed the oxidation of xanthine and hypoxanthine was recognized. The name given the enzyme was derived from its earliest recognized action, hence xanthine oxidase. Although little is known about the biological functions of the enzyme, the high affinity shown for xanthine and hypoxanthine may indicate that these are the most significant substrates biologically.


Asymptotic Evaluation Of Wkb Matrix Elements. Ii. Use Of Langer's Uniform Asymptotic Wavefunctions, Wesley D. Smith, Russell T. Pack Feb 1970

Asymptotic Evaluation Of Wkb Matrix Elements. Ii. Use Of Langer's Uniform Asymptotic Wavefunctions, Wesley D. Smith, Russell T. Pack

Faculty Publications

An improvement in a previous procedure for the analytic asymptotic evaluation of integrals arising in the quantum-mechanical theory of inelastic molecular collisions is presented. The integrals are evaluated using Langer's uniform asymptotic wavefunctions and the higher-order saddle-point or steepest-descents method. It is found that the Langer functions give no better results than WKB functions, but the higher-order steepest-descents corrections produce a marked improvement. The result is a simple method for evaluating a large class of integrals with an error of 0.1%-2.1%.


Quasilattice Interpretation Of The Thermodynamic Properties Of Mixing Of Binary Alkali-Metal Systems, J. Bevan Ott, J. Rex Goates Nov 1969

Quasilattice Interpretation Of The Thermodynamic Properties Of Mixing Of Binary Alkali-Metal Systems, J. Bevan Ott, J. Rex Goates

Faculty Publications

Quasilattice theory was applied to heats of mixing in the six systems formed from the binary combinations of Na, K, Rb, and Cs. The alkali-metal systems are particularly well suited for a critical test of the quasi-crystalline assumption since the theoretical model for these systems is relatively simple and the thermodynamic data are fairly complex. Very good fits of the heat-of-mixing data were achieved by assuming that the larger atom in the binary system covered multiple sites on the quasilattice. The values of the empirically determined constants appear to fit the physical significance accorded to them by the quasilattice model. …


A Study Of Folic Acid Dependent Reactions In Bovine Brain, Dillard Spencer Broderick Aug 1969

A Study Of Folic Acid Dependent Reactions In Bovine Brain, Dillard Spencer Broderick

Theses and Dissertations

The enzymatic interconversion of serine to glycine and N5, N10-methylene tetrahydrofolate to N5 -methyl tetrahydrofolate have been studied in a cell-free system derived from bovine brain. A partial purification of serine transhydroxymethylase and N5, N10 -methylene tetrahydrofolate reductase has been achieved by ammonium sulfate fractionation, protamine sulfate fraction, and by various column chromatography procedures. The two enzymes studied catalyze sequentially the reductive transfer of the hydroxymethyl group of serine to the N5 position of tetrahydrofolate forming N5 -methyl tetrahydrofolate. The products of these reactions were assayed by the incorporation of C14 from a one-carbon precursor i.e., L-beta-(C14)-serine, or N5 -methyl …


Superphosphate For Wheatbelt Pastures : Rates Of Application, Walter Jacob Cox Jan 1969

Superphosphate For Wheatbelt Pastures : Rates Of Application, Walter Jacob Cox

Journal of the Department of Agriculture, Western Australia, Series 4

BECAUSE Western Australian soils are low in phosphorus, frequent applications of superphosphate are required for both crop and pasture production. The recommended rates are determined from the results of field experiments that test different quantities of super and measure the extra yield.

This article discusses the recommended rates of superphosphate in relation to soil type and superphosphate history. Methods of application and time of topdressing are also discussed.


Expectation Values Of Simple Correlated Helium-Atom Wavefunctions, Thomas P. Tsien, Russell T. Pack Nov 1968

Expectation Values Of Simple Correlated Helium-Atom Wavefunctions, Thomas P. Tsien, Russell T. Pack

Faculty Publications

In this Note we present the results of a calculation of the expectation values of a number of one- and two electron properties of the ground-state helium atom using two very simple correlated wavefunctions.


Isolation And Partial Characterization Of The Toxic Substance From Eremocarpus Setigerus Benth, Shuliang Lee May 1968

Isolation And Partial Characterization Of The Toxic Substance From Eremocarpus Setigerus Benth, Shuliang Lee

Loma Linda University Electronic Theses, Dissertations & Projects

The work on the active substance of Eremocarpus setigerus Benth has been previously performed by Naito and Noller. However, the investigation was not complete. Therefore we isolated and tested this substance by steam distillation and thin layer chromatography technique. A yellow sticky toxic substance was isolated with Rf values of 0.15 in benzene system and 0.57 in benzene-absolute ethanol (95:5 v/v) system.

The toxic substance which is free of halogen, nitrogen, and sulfur, is soluble in ethyl ether, ethanol, and concentrated sulfuric acid. It has a maximum absorption in the ultraviolet region that indicates the presence of unsaturation. Its infrared …


The Function And Use Of Sulphur Dioxide In West Australian Winemaking, D Mann Jan 1968

The Function And Use Of Sulphur Dioxide In West Australian Winemaking, D Mann

Journal of the Department of Agriculture, Western Australia, Series 4

THE judicious use of sulphur dioxide is perhaps the most important of the fundamentals of winemaking in a hot climate.

Western Australia's vintage, centred in the Swan Valley just a few miles north-east of Perth, is subjected to some of the highest summer temperatures experienced by a quality wine producing district.

In this environment, it is important to make good use of sulphur dioxide to avoid wine spoilage.


The Role Of Thiamine Pyrophosphate In Regulating The Level Of Gamma-Aminobutyric Acid In The Central Nervous System, Bryant L. Adams Aug 1965

The Role Of Thiamine Pyrophosphate In Regulating The Level Of Gamma-Aminobutyric Acid In The Central Nervous System, Bryant L. Adams

Theses and Dissertations

The level of gamma-aminobutyric acid in the brains of white rats suffering from thiamine deficiency symptoms resulting from pyrithiamine or oxythiamine antagonism of thiamine or from thiamine deprivation was measured. The level of this amino acid was 17.5% lower in the brains of pyrithiamine-treated rats and 20.0% lower in the brains of thiamine-deprived rats than in the control rats. Daily injections of ten times the required amounts of vitamin B6 in rats treated with pyrithiamine or oxythiamine or by thiamine deprivation had no effect on the level of brain gamma-aminobutyric acid or on the psiological behavior of these rats. The …


Studies Of Rat Brain Thiamine Pyrophosphokinase, Lavell Rolfson Johnson Aug 1965

Studies Of Rat Brain Thiamine Pyrophosphokinase, Lavell Rolfson Johnson

Theses and Dissertations

The enzyme ATP:thiamine pyrophosphotransferase (thiamine pyrophosphokinaseJ was purified from acetone powders which were prepared from rat brains up to the chromatography on alumina C_γ step by a modified procedure that Mano (Y. Mano, J. Biochem., 42, 283 (1960)] developed for the purification of the rat liver thiamine pyrophosphokinase. The enzyme was purified 12 fold over that in the original extract of the acetone powder. A spectrophotometric assay for the brain thiamine pyrophosphokinase was developed utilizing brewer's yeast apotransketolase. The transketolase assay was able to detect less than 10^-11 moles of thiamine diphosphate, which was synthesized by the kinase, in the …


Water Chemistry Survey Of Boulder Basin, Lake Mead, P. R. Tramutt, Bureau Of Reclamation Jun 1965

Water Chemistry Survey Of Boulder Basin, Lake Mead, P. R. Tramutt, Bureau Of Reclamation

Publications (WR)

The survey results indicate that the impoundment of water behind Hoover Dam has not adversely affected the dissolved oxygen (DO) content and that water quality and DO content were uniform regardless of depth. The study made in April-May 1964 will provide water quality data of Lake Mead prior to releases from Lake Powell as a basis for evaluating Lake Powell's effect on water quality and limnology of Lake Mead. The performance of a DO analyzer was tested and found unsatisfactory at depths below 150 ft. Parameters tested by standard chemical analyses of water samples in the Denver Laboratory and by …


The Vitamin B1-Sparing Action Of Sorbitol, Gisela Eleanor Bethsold Jun 1960

The Vitamin B1-Sparing Action Of Sorbitol, Gisela Eleanor Bethsold

Theses and Dissertations

The present study was initiated to determine the effect sorbitol has upon the enzymatic functions of thiamin; specifically, what effect sorbitol bas upon the alpha-ketoglutarate and pyruvate dehydrogenases activities of rat liver mitochondria. In addition, the effect of varying the dietary sorbitol concentration on the development of an athiaminosis was studied, particularly the effect on growth rate.


Preliminary Report: Monolayer Behavior Studies, 1959, Bureau Of Reclamation Jan 1960

Preliminary Report: Monolayer Behavior Studies, 1959, Bureau Of Reclamation

Publications (WR)

During the fall of 1959, monolayer behavior studies were made on two lakes in the southwest; Boulder Basin of Lake Mead, Nevada, and Lake Sahuaro near Phoenix, Arizona. These studies were made to evaluate the effect of geographical and climatological conditions on movement and behavior of monolayers. The Lake Sahuaro tests also were used to provide data for design and development of improved methods of application and maintenance of a film on this lake in anticipation of full scale, evaporation-reduction tests to be performed there during the summer of I960. The Lake Mead studies produced the following general points of …


Comprehensive Survey Of Sedimentation In Lake Mead, 1948-49, W. O. Smith, C. P. Vetter, G. B. Cummings, U.S. Bureau Of Reclamation Jan 1960

Comprehensive Survey Of Sedimentation In Lake Mead, 1948-49, W. O. Smith, C. P. Vetter, G. B. Cummings, U.S. Bureau Of Reclamation

Publications (WR)

Reservoirs are becoming an increasingly prominent feature of the American landscape. Built for flood mitigation and to change a fluctuating river into a dependable source of water for irrigation, power, and other purposes, they are predestined, like natural lakes, to be destroyed sometime following their creation. Sedimentation sooner or later robs most lakes and reservoirs of their capacity to store water. The significance of sedimentation in the life of Lake Mead, the largest artificial reservoir in the world, was realized when the plan for the reservoir was conceived, and an aerial survey of the floor was made in 1935 before …


Studies On The Biological Oxidation Of Ferrous Iron And Chalcopyrite, Loral Alvin Decker Aug 1959

Studies On The Biological Oxidation Of Ferrous Iron And Chalcopyrite, Loral Alvin Decker

Theses and Dissertations

The purpose of this investigation was to determine the effectiveness of the leaching streams from waste copper ore dumps as a nutrient solution for subsequent biological oxidation and solubilization of sulfide minerals. The copper in the leaching streams is precipitated by displacement with iron. As a result of this procedure the solution is high in ferrous iron concentration and has a pH of near 3.7. The bacteria in the leaching streams are capable of oxidizing ferrous iron to the ferric state and sulfide minerals to sulfates. The effects of temperatures, pH, urea, and aeration rate on the oxidation of the …


A Study Of Three Photochemical Activities Of Chloroplasts, Jimmy W. Hinkson Apr 1958

A Study Of Three Photochemical Activities Of Chloroplasts, Jimmy W. Hinkson

Theses and Dissertations

Chloroplasts of sugar beet leaves were subjected to treatment by heating, by incubation at pH 8.5 and pH 5.5, by incubation in ion low water, by sonic oscillation, by digestion with enzymes (lysozyme, pancreatin, and lipase), by extraction with digitonin, and by chemical compounds including 8-hydroxy-quinoline, sodium azide, zinc sulfate, phenyl mercuric acetate, potassium cyanide, 1-allylthiourea, 2,4-dinitrophenol, thymol, and p-chloromercuribenzoate. A comparative study was made of the effects of these treatments upon three photochemical reactions (the photoreduction of 2,6- dichlorophenol indophenol, the photoreduction of indigo carmine in the presence of a couple composed of 2,6-dichlorophenol indophenol and ascorbic acid, and …


Chemosynthetic Microorganisms In Leaching Sulfide Minerals, A. Keith Jameson Jul 1957

Chemosynthetic Microorganisms In Leaching Sulfide Minerals, A. Keith Jameson

Theses and Dissertations

This investigation showed that a single bacterium was capable of sulfide oxidation in exposed ore bodies. This single bacterium was isolated and characterized. It exhibited different characteristics than any previously known organism. It was found to be a chemosynthetic autotroph. An optimum nutrient concentration was determined for pyrite oxidation. The nutrient concentration was determined for pyrite oxidation. The nutrient contains only a source of phosphate and nitrogen. Urea was found to be a better source of nitrogen than ammonium sulfate which had previously been used. The effect of various organic compounds on the oxidation of pyrite was observed. Glucose and …


Oxidation Of Molybdenite With The Aid Of Microorganisms, Ralph Anderson Aug 1956

Oxidation Of Molybdenite With The Aid Of Microorganisms, Ralph Anderson

Theses and Dissertations

This work represents a study on the biological oxidation of molybdenite, MoS2. The principal objective of this study was to investigate the possibility of the biological oxidation of molybdenite, to determine the physical and chemical conditions under which the oxidative process occurs, and to develop a strain of bacteria or alter the activity of the microorganisms by acclimatization to increase their activity on sulfide minerals, in particular molybdenite. Minerals used in this study were pyrite (FeS2), chalcopyrite (CuFeS2), molybdenite concentrate, and molybdenite ore. The microorganisms used in this investigation were autotrophic bacteria obtained from the leaching streams of Bingham Canyon, …


Photo-Oxidations Sensitized By Physiologically Important Substances, Ernel D. Ihnen Jun 1956

Photo-Oxidations Sensitized By Physiologically Important Substances, Ernel D. Ihnen

Theses and Dissertations

A study of the photo-oxidation of the 2,6-dichlorophenol indophenol-ascorbic couple was undertaken with a view to investigating the postulated mechanism of oxidation by a component of the oxygen evolving sequence operative in photosynthesis. A spectrophotometric method for the measurement of the progress of photo-oxidation was developed. Temperature and pH dependence were determined and the effect of various common inhibitors and physiological substances tested. None of the common Hill reaction inhibitors were effective in the ascorbic acid photo-oxidation in the system used. KCN and catalase as well as a few other high molecular weight proteins were able to inhibit dark auto-oxidation …


The Chromatographic Purification Of Human Red Blood Cell Acetylcholinesterase, Richard P. Dunkley May 1954

The Chromatographic Purification Of Human Red Blood Cell Acetylcholinesterase, Richard P. Dunkley

Theses and Dissertations

A process of column chromatography of human erythrocyte acetylcholinesterase, using a cationic exchange resin, was investigated as a possible method for the primary partial purification of the enzyme on a large scale. The investigation was based, first; on a detailed study of the enzymatic stability to variation in hydrogen-ion and salt concentrations for periods of time extending to forty eight hours and, second; on an investigation of the degree of adsorption by the resin of the enzyme at various pH values within the pH range of enzyme stability. A method for the analysis of the enzyme activity of large numbers …


Biological Oxidation Of Copper Sulfide Minerals, Delmar Boyd Davis Dec 1953

Biological Oxidation Of Copper Sulfide Minerals, Delmar Boyd Davis

Theses and Dissertations

This work represents a study of the biological oxidation of copper sulfide minerals. The principal objective of the study was to determine the extent of bacterial oxidation on copper containing sulfide minerals. It was also desired to determine if the bacteria could oxidize copper sulfides in the absence of iron. A better understanding of the nitrogen requirements of the organisms was desired. Minerals used in this study were Bingham Canyon Float Concentrate, chalcopyrite, covellite, calcocite, bornite, tetrahedrite, and reagent grade copper sulfide. The bacteria used were obtained from the mine waters of Bingham Canyon, Utah. To study the problem the …


A Study Of Factors Influencing The Hydrolysis Of Corn Amylopectin By Barley Malt Enzymes., Thelma Munsey Back 1918-2006 Jan 1945

A Study Of Factors Influencing The Hydrolysis Of Corn Amylopectin By Barley Malt Enzymes., Thelma Munsey Back 1918-2006

Electronic Theses and Dissertations

No abstract provided.


A Study Of The Kjeldahl Method And A Modification For The Determination Of Nitrogen In Alcoholic Distillates., Margie M. Miller Jan 1940

A Study Of The Kjeldahl Method And A Modification For The Determination Of Nitrogen In Alcoholic Distillates., Margie M. Miller

Electronic Theses and Dissertations

No abstract provided.