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Articles 931 - 953 of 953

Full-Text Articles in Chemistry

Drop-Box Technique For Quantitative Sampling Of Macrofauna And Aquatic Plants At Restored And Natural Wetlands, J. Douglas Oliver, Andrew J. Leslie, William M. Bartodziej Jan 1991

Drop-Box Technique For Quantitative Sampling Of Macrofauna And Aquatic Plants At Restored And Natural Wetlands, J. Douglas Oliver, Andrew J. Leslie, William M. Bartodziej

Faculty Publications and Presentations

No abstract provided.

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Activator-Inhibitor Control Of Tissue Growth, John A. Adam Jan 1991

Activator-Inhibitor Control Of Tissue Growth, John A. Adam

Mathematics & Statistics Faculty Publications

This note develops a simple model for the competition between activator and inhibitor control mechanisms in one-dimensional tissue growth. The pedagogic usefulness of such a model is that it is easily accessible to undergraduate applied mathematicians and is suggestive of behavior known to occur in more realistic biological systems (e.g., some types of cancer). The limitations of the model are obvious and can provide a basis for discussion of the applicability of complementary levels of description in mathematical modeling.

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Mounting Sex Pheromone: A Novel Pheromone Responsible For Mate Recognition In The Ixodidae, Jgc Hamilton Jul 1989

Mounting Sex Pheromone: A Novel Pheromone Responsible For Mate Recognition In The Ixodidae, Jgc Hamilton

Theses and Dissertations in Biomedical Sciences

Cholesterol oleate was demonstrated to be the cuticular contact sex pheromone of Dermacentor variabilis. This pheromone which has been termed the Mounting Sex Pheromone (MSP) was also demonstrated to be present on the surface of D. andersoni, Amblyomma maculatum and A. americanum. This contact sex pheromone enables males excited and attracted by 2,6-dichlorophenol to identify the female as a potential mating partner. The MSP is the second in the series of three sex pheromones guiding the hierarchy of behavioral responses which constitute tick courtship behavior. Tests with D. variabilis and D. andersoni showed that this pheromone …

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Residual Influence Of Macronutrient Enrichment On The Aquatic Food Web Of An Okefenokee Swamp Abandoned Bird Rookery, J. Douglas Oliver, Steven A. Schoenberg Jan 1989

Residual Influence Of Macronutrient Enrichment On The Aquatic Food Web Of An Okefenokee Swamp Abandoned Bird Rookery, J. Douglas Oliver, Steven A. Schoenberg

Faculty Publications and Presentations

We present evidence for residual nutrient enrichment of diverse components of a blackwater marsh, by a biotic component of the ecosystem itself. Thousands of nesting white ibis (Eudocimus albus) that foraged over a 20-km radius fertilized a rookery with guano within Okefenokee Swamp. Georgia. USA. One to two yr after the birds abandoned it. this marsh showed continued enrichment effects. Elevated available phosphorus in sediments, as measured by equilibrium phosphate concentration, contributed to enhanced biomass of phytoplankton in the overlying water column. Planktivorous fish were greater in biomass than at reference sites. Experimental phosphorus and nitrogen fertilization of enclosures at …

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Limnological Monitoring Data For Lake Mead During 1987: Technical Report No. 20, Larry J. Paulson Jan 1988

Limnological Monitoring Data For Lake Mead During 1987: Technical Report No. 20, Larry J. Paulson

Publications (WR)

Limnological monitoring was conducted in Las Vegas Bay and Boulder Basin from April to December of 1987. The purpose of the monitoring was to (i) document possible changes in water quality resulting from decreased phosphorus loading in Las Vegas Wash, and (ii) establish a data base for evaluating the adequacy of water quality standards.

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Lake Mead Cover Enhancement Project, Jennifer Stevens Haley, Suzanne Leavitt, Larry Paulson, Donald H. Baepler Jul 1987

Lake Mead Cover Enhancement Project, Jennifer Stevens Haley, Suzanne Leavitt, Larry Paulson, Donald H. Baepler

Publications (WR)

Ninety-three wildlife agencies were surveyed for information on their attempts to improve fish habitat. In addition, an annotated bibliography including over 100 summaries was completed on: 1. largemouth bass cover requirements and preferences, 2. use and effectiveness of artificial cover, 3. aquatic plant introduction and species requirements for germination and establishment, 4. terrestrial plant introduction and species requirements for germination and establishment, and 5. nutrient exchange between sediment, aquatic plants, and water. A reconnaissance of existing terrestrial and aquatic vegetation was completed in June 1986 including the production of a video tape of the Nevada shoreline of Lake Mead. Cover …

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Comparison Of Three Methods For Sampling Fishes And Macroinvertebrates In A Vegetated Wetland, B. J. Freeman, H. S. Greening, J. Douglas Oliver Jan 1984

Comparison Of Three Methods For Sampling Fishes And Macroinvertebrates In A Vegetated Wetland, B. J. Freeman, H. S. Greening, J. Douglas Oliver

Faculty Publications and Presentations

Three methods of sampling fishes, two seining methods and a drop trap method, were evaluated in heavily vegetated freshwater habitats. The portable drop trap method, which utilized a 1 x 1 m-sq. trap, collected significantly more macroinvertebrates and fish per unit area than did the seining methods. The meter square drop trap offered the additional advantages of a greater number of animals per unit effort and an integrated sample of vegetation, macroinvertebrates and fish in a given area. A 90% (s.d.= 7.4%) recovery of tagged fishes released into the traps in different habitats showed the m2 drop trap to be …

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The Combined Effect Of Cu And Zn On Selenastrum Capricornutum, Helmer Colonia-Roque May 1983

The Combined Effect Of Cu And Zn On Selenastrum Capricornutum, Helmer Colonia-Roque

Dissertations and Theses

It has been demonstrated that the toxicity of heavy metals depends on their chemical speciation and can be related to their free ion activities, rather than the total metal concentrations. The objective of this study was to determine the effect of combined free ions of zinc and copper on the toxicity to the green alga Selenastrum capricornutum. This alga was grown in a defined medium, under controlled laboratory conditions, with a varying range of zinc and copper concentrations. The growth rate of the alga was inhibited at pZn = 5.93 or at pCu = 7.24. The results suggest that …

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Organic N-Chloramines: Chemistry And Toxicology, Frank E. Scully, Jr., Maxwell A. Bempong Jan 1982

Organic N-Chloramines: Chemistry And Toxicology, Frank E. Scully, Jr., Maxwell A. Bempong

Chemistry & Biochemistry Faculty Publications

The stability of aqueous solutions of organic N-chloramines, suspected of contaminating chlorinated water, has been studied. Two factors influence the decomposition of solutions of N-chloropiperidine and N-chlorodiethylamine: a spontaneous decomposition and photodecomposition. Since solutions of these compounds are relatively long-lived, a need for an analytical method for their identification is discussed. A new method is described which involves reaction of organic N-chloramines with arenesulfinic acid salts. The method gives high yields of stable arenesulfonamides. Several toxicological studies of N-chloropiperidine are described. The compound is mutagenic by Ames assay in Salmonella typhimurium strain TA 100 and does not require metabolic activation …

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Influence Of Las Vegas Wash Density Current On Nutrient Availability And Phytoplankton Growth In Lake Mead, John R. Baker, Larry J. Paulson Jun 1980

Influence Of Las Vegas Wash Density Current On Nutrient Availability And Phytoplankton Growth In Lake Mead, John R. Baker, Larry J. Paulson

Publications (WR)

Density currents are commonly formed in reservoirs because of temperature or salinity induced density differences between inflowing and receiving waters. Anderson and Pritchard (1951) were among the first to demonstrate this in their investigations of density currents in Lake Mead. They found that the Colorado River formed an underflow in Lake Mead during the winter, an overflow in the spring and an interflow in the summer and fall. Wunderlich and Elder (1973) have since described the hydromechanics of these types of flow patterns, and density currents have been reported for several other large reservoirs (Carmack et al. 1979, Johnson and …

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The Kinetics Of Solvent Reorientation In Hydroxylated Solvents From The Exciting-Wavelength Dependence Of Chromophore Emission Spectra, John Milton, Robert M. Purkey, William C. Galley Jun 1978

The Kinetics Of Solvent Reorientation In Hydroxylated Solvents From The Exciting-Wavelength Dependence Of Chromophore Emission Spectra, John Milton, Robert M. Purkey, William C. Galley

WM Keck Science Faculty Papers

The disappearance of the exciting-wavelength dependence of the phosphorescence spectra of polar, aromatic chromophores in supercooled glycol–water mixtures is utilized to monitor the kinetics of solvent reorientation. Reorientation times in the nanosecond to second range are obtained for (3:2 v/v) glycerol–water and (1:1 v/v) ethylene glycol–water at 140–240 °K. The results suggest that the process is one involving a cluster of solvent molecules and in which the chromophore plays a relatively passive role. Steady-state data and direct measurements of phosphorescence shifts as a function of time indicate that the solvent reorientation process is nonexponential in nature. The decay function derived …

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Biological And Chemical Evaluation Of The Aquatic Environment Of Selected Undeveloped Kentucky Lake Embayments, Marshall Gordon, Morgan E. Sisk Dec 1976

Biological And Chemical Evaluation Of The Aquatic Environment Of Selected Undeveloped Kentucky Lake Embayments, Marshall Gordon, Morgan E. Sisk

KWRRI Research Reports

This report describes research involving biological and chemical analysis of two undeveloped embayments on Kentucky Lake, namely Anderson and Vickers Bays. Field and laboratory studies were made to assess current biotic standing crops, limnological conditions, levels of inorganic and organic pollutants in the embayments.

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Electrochemical Machining (Ecm) With Alternating Current, S. J. Shine Jan 1975

Electrochemical Machining (Ecm) With Alternating Current, S. J. Shine

Tanzania Journal of Science

Electrochemistry has had several practical uses in industry for a long time; but one of the more recent applications is the machining of metals. Direct current ECM has been applied in industry for the last two decades. However, ECM with alternating current is still in the early stage of research and development. This paper shows that ECM with normal a.c supply is feasible and practicable if special tools are used. ECM with d.c. is first introduced to provide a better insight for the machining with a.c.

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Final Report On Interrelationships Between Chemical, Physical And Biological Conditions Of The Waters Of Las Vegas Bay Of Lake Mead, James E. Deacon, Richard W. Tew Jan 1973

Final Report On Interrelationships Between Chemical, Physical And Biological Conditions Of The Waters Of Las Vegas Bay Of Lake Mead, James E. Deacon, Richard W. Tew

Publications (WR)

This program was a status study of the interaction between Las Vegas Wash, an enriched stream, and Las Vegas Bay, a wedge shaped arm of one of the world's deeper reservoirs. The program centered primarily on identification and counting of planktonic algae from several points in Las Vegas Bay. Additional work on nutrient enrichment of water samples was conducted to aid in interpretation of algal distribution related to nutrient input. Examination of a variety of physical, chemical, and biological parameters, both at many surface points in the bay, as well as in vertical profile, was also accomplished and further aided …

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Some Aspects Of Mercury Accumulation By The Purple Shore Crab Hemigrapsus Nudus Dana (Crustacea: Decapoda), Ralph Gene Swanson Jan 1973

Some Aspects Of Mercury Accumulation By The Purple Shore Crab Hemigrapsus Nudus Dana (Crustacea: Decapoda), Ralph Gene Swanson

University of the Pacific Theses and Dissertations

The present study has attempted to investigate some of the more basic questions concerning the toxicity and accumulation of mercury in the purple shore crab, Hemigrapsus nudus. This rocky intertidal denizen is found in abundance along the entire Pacific coast of the United States from Sitka, Alaska, to the Gulf of California where it dominates the mid-tide pool region. Local specimens were collected just north of the Pacific Marine Stations, Dillon Beach, Marin County, California. The animal is hearty and can be kept in a state of good health for long periods of time in the laboratory with minimum care …

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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 …

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The Effects Of Herbicides On Three Soil Inhabiting Blue Green Algal Species, Lee C. Darlington Aug 1969

The Effects Of Herbicides On Three Soil Inhabiting Blue Green Algal Species, Lee C. Darlington

All Master's Theses

The object of this study was to examine the effects of varying concentrations of 2, 4-D, Dalapon, and Tordon on the growth of several nitrogen-fixing blue-green algal species obtained from soil samples and grown under culture conditions in the laboratory.

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The Value Of Including Chemistry Content In The Study Of High School Biology, Ramon Duane Buckley Jan 1957

The Value Of Including Chemistry Content In The Study Of High School Biology, Ramon Duane Buckley

Dissertations and Theses @ UNI

The purpose was to evaluate the effect of including some definite chemistry content in high school biology. This evaluation was made by comparing outcomes of instruction in two different groups of a high school biology course. The two groups were equated in terms of the intelligence quotients, the sex, and the previous achievement in biology of the class members. The comparative gains in factual knowledge were measured by means of an evaluation test. The comparative gains in appreciations and interests in biology were measured with a questionnaire.

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Activity Of Papain On Gelatin Mixtures, Edward J. Ruschmann Jul 1941

Activity Of Papain On Gelatin Mixtures, Edward J. Ruschmann

Bachelors’ Theses

Within the Marquette chemical laboratories under the direction and supervision of Dr. John R. Koch, professor and head of the Chemistry Department, many noteworthy advances in enzyme chemistry have been achieved. A new type all glass, single unit viscometer was developed and perfected by Koch and now is the basis of the study of enzyme activity by viscometric methods. The use of this viscometer is not limited solely to work in these laboratories but has also been used with great success in bating and brewing.

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The Effects Of A Carbohydrate Deficient Diet On The Mouse, Walter Rudolph Sala May 1941

The Effects Of A Carbohydrate Deficient Diet On The Mouse, Walter Rudolph Sala

Bachelors’ Theses

Deficient diets have been used extensively as the basis for zoological experiments concerning the metabolism, and dietary requirements of individual animals. The majority of this work has been carried on with the rat as the subject, and resulting external physical variations as the experimental aim. The writer used the mouse as his subject, but, since no literature was available concerning this animal, a few similar experiments performed on the rat will be cited.

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Scholasticism An Intellectual Basis And Unifying Principle Of Modern Science, Alice V. Johnson Jul 1929

Scholasticism An Intellectual Basis And Unifying Principle Of Modern Science, Alice V. Johnson

Electronic Theses and Dissertations

Amid the almost uninterrupted disintegration of systems during the last three centuries, the philosophy of St. Thomas has alone been able to stand the shock of criticism; it alone has proved sufficiently solid and comprehensive to serve as an intellectual basis and unifying principle for all the new facts and phenomena brought to light by modern science.

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The Alcohols, Charles E. Baker Jan 1894

The Alcohols, Charles E. Baker

Manuscript Thesis Collection

A study of Alcohols and the human body's reactions to them.

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Human Complement Protein C8: The “Hole” Story, James M. Sodetz Jan 1012

Human Complement Protein C8: The “Hole” Story, James M. Sodetz

Journal of the South Carolina Academy of Science

No abstract provided.

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