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Articles 2701 - 2730 of 3135

Full-Text Articles in Physical Sciences and Mathematics

Determination Of Hammett Pyridine 3-Aza And 4-Aza Replacement Constants By 1h Nmr Studies Of Amide Systems, Frank L. Setliff, Nikhil G. Soman, Alan D. Toland Jan 1993

Determination Of Hammett Pyridine 3-Aza And 4-Aza Replacement Constants By 1h Nmr Studies Of Amide Systems, Frank L. Setliff, Nikhil G. Soman, Alan D. Toland

Journal of the Arkansas Academy of Science

Values for Hammett pyridine 3-aza and 4-aza replacement constants were obtained by correlation of the amide proton chemical shifts (in DMSO) of some N-(3-pyridyl)-and N-(4-pyridyl)-dichloronicotinamides, benzamides and acetamides with those of their N-(substituted phenyl) amide analogs using standard Hammett a values

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Sinkhole Excavations In Peccary Cave, Newton County, Arkansas, Kenneth M. Ball, Leo Carson Davis Jan 1993

Sinkhole Excavations In Peccary Cave, Newton County, Arkansas, Kenneth M. Ball, Leo Carson Davis

Journal of the Arkansas Academy of Science

No abstract provided.

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Rapid Reduction Of Nitrate Ion In Rain Water, David M. Chittenden Ii Jan 1993

Rapid Reduction Of Nitrate Ion In Rain Water, David M. Chittenden Ii

Journal of the Arkansas Academy of Science

No abstract provided.

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Arkansas Agricultural Chemical Ground-Water Management Plan, Gerald King, Darryl Little, Tim Jessup, Charles Armstrong Oct 1992

Arkansas Agricultural Chemical Ground-Water Management Plan, Gerald King, Darryl Little, Tim Jessup, Charles Armstrong

Arkansas Water Resources Center Technical Reports

The Arkansas Agricultural Chemical Ground-Water Management Plan (SMP) is based on the Draft State Pesticide Ground- Water Management Plan Guidance and The Pesticides and Ground-Water Protection Strategy prepared by the U.S. Environmental Protection Agency (EPA). The need for a plan to protect ground water from contamination by agricultural chemicals and agents arises from evidence nationwide that using these chemicals can, in some instances, lead to contamination. In February 1988, EPA proposed a strategy to regulate certain pesticides by prohibiting their use in areas vulnerable to leaching unless a state develops and implements an acceptable management plan. The advantage of a …

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Relationship Between Ground And Surface Water Quality In Karst Systems, Richard L. Meyer Sep 1992

Relationship Between Ground And Surface Water Quality In Karst Systems, Richard L. Meyer

Arkansas Water Resources Center Technical Reports

Springs in Northwest Arkansas may originate from relatively small fractures in rock strata or from cave systems. The water emerging from these springs is frequently used as water sources for plants, animals and humans. The quality of the ground water source and the emerging water are uncertain and frequently unknown. In addition, the opportunity to monitor changes in water quality during flow from origin (water entering the cave) to emergence is uncommon. Cave systems with definable drainage basins and accessible sampling points near the midpoint of the cave are also uncommon. Examining the interface between the quality of surface water …

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Fact Sheet No.2: Water Quality And Poultry Disposal Pits, T. C. Daniel, D. R. Edwards, D. J. Nichols, K. F. Steele, Steve Wilkes Jul 1992

Fact Sheet No.2: Water Quality And Poultry Disposal Pits, T. C. Daniel, D. R. Edwards, D. J. Nichols, K. F. Steele, Steve Wilkes

Arkansas Water Resources Center Technical Reports

Disposing of poultry that die during grow out is a serious management problem for poultry producers in Northwest Arkansas and across the country. Poultry disposal can affect water quality and the health of wildlife, livestock and people.

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Arkansas Agricultural Chemical Ground-Water Management Plan - Appendices, Gerald King, Darryl Little, Tim Jessup, Charles Armstrong Jul 1992

Arkansas Agricultural Chemical Ground-Water Management Plan - Appendices, Gerald King, Darryl Little, Tim Jessup, Charles Armstrong

Arkansas Water Resources Center Technical Reports

The Arkansas Agricultural Chemical Ground-Water Management Plan (SMP) is based on the Draft State Pesticide Ground- Water Management Plan Guidance and The Pesticides and Ground-Water Protection Strategy prepared by the U.S. Environmental Protection Agency (EPA). The need for a plan to protect ground water from contamination by agricultural chemicals and agents arises from evidence nationwide that using these chemicals can, in some instances, lead to contamination. In February 1988, EPA proposed a strategy to regulate certain pesticides by prohibiting their use in areas vulnerable to leaching unless a state develops and implements an acceptable management plan. The advantage of a …

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Gis Characterization Of Beaver Watershed, H. D. Scott, J. M. Mckimmey Jun 1992

Gis Characterization Of Beaver Watershed, H. D. Scott, J. M. Mckimmey

Arkansas Water Resources Center Technical Reports

Beaver Reservoir watershed is located in Northwest Arkansas including portions of Madison, Washington, Benton, Carroll, Franklin and Crawford counties. This watershed is important to the Northwest Arkansas region because it supplies most of the drinking water for the major towns and cities, and several rural water systems. The watershed consists of 308,971 ha with elevations ranging from approximately 341 m to 731 m above mean sea level. It includes the Springfield Plateau and the Boston Mountains provinces within the Ozark Plateau physiographic region. There are approximately 581 km of streams, 532 km of shore line, and 3712 km of roads …

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Evaluation Of The Water Quality Impacts Of Land Application Of Poultry Litter, T. C. Daniels, D. R. Edwards Jun 1992

Evaluation Of The Water Quality Impacts Of Land Application Of Poultry Litter, T. C. Daniels, D. R. Edwards

Arkansas Water Resources Center Technical Reports

Evaluating the effect of land application of animal waste on water quality is fraught with inherent variability due to differing infiltration rates, slope, rainfall intensity and etc . Simulated rainfall technology has been used in erosion research for decades. Generally, this technology is used on plots of sufficient size (25 x 5 m) to develop rill and interrill erosion. The object of this investigation was to adapt and modify existing rainfall simulation technology used in soil erosion research for use in evaluating water quality impacts of land application of animal waste, and to test, evaluate and demonstrate it's scientific validity. …

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Effect Of Land Application Of Poultry Waste On Pesticide Loss, T. C. Daniel, D. R. Edwards Jun 1992

Effect Of Land Application Of Poultry Waste On Pesticide Loss, T. C. Daniel, D. R. Edwards

Arkansas Water Resources Center Technical Reports

The poultry industry in Arkansas is a large, concentrated, growing industry that produces a high volume of fecal waste. Most of this waste is surface applied as pasture fertilizer. Pesticides are commonly used in the poultry industry for fly and litter beetle contro land are often a component of the surface-applied poultry waste. No information exists in the scientific literature regarding the transport of this pesticide component to nearby water supplies.Our research focused on cyromazine, a feed-through larvicide used to control flies in caged-layer hen houses. Tetrachlorvinphos and carbaryl are also used in poultry waste, but these pesticides have a …

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Arkansas Rice Research Studies 1991, B. R. Wells Jun 1992

Arkansas Rice Research Studies 1991, B. R. Wells

Arkansas Agricultural Experiment Station Research Series

The research reports in this publication represent one year of results; therefore, these results should not be used as a basis for longterm recommendations. Several research reports in this publication dealing with soil fertility also appear in Arkansas Soil Fertility Studies 1991, Arkansas Agricultural Experiment Station Research Series 421. This duplication is the result of the overlap in research coverage between the two series and our effort to inform Arkansas rice producers of all the research being conducted with funds from the rice check-off.

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Arkansas Soil Fertility Studies 1991, Wayne E. Sabbe May 1992

Arkansas Soil Fertility Studies 1991, Wayne E. Sabbe

Arkansas Agricultural Experiment Station Research Series

Contained within this publication are progress reports on the specific aspects of the soil fertility program at the University of Arkansas in 1991. In most instances, the reports are not final reports, but they may contain data from several years. Further details on each report can be obtained from the respective project leaders.

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Reconnaissance Survey Of Nitrate Concentrations In Ground Water In Howard And Pike Counties, Arkansas, Travis Thornton, Kenneth F. Steele Feb 1992

Reconnaissance Survey Of Nitrate Concentrations In Ground Water In Howard And Pike Counties, Arkansas, Travis Thornton, Kenneth F. Steele

Arkansas Water Resources Center Technical Reports

In recent years, the rapid growth of poultry and hog production in Arkansas has caused concern regarding nitrate contamination of the ground water. In the study area of Pike and Howard Counties, the number of hogs has increased from 3,300 hogs in 1970 to 75,000 hogs in 1990. Poultr¥ production for the area has increased from 38,933,000 per year 1n 1970 to 62,774,000 per year in 1990. As animal production increases, so does the amount of animal waste that must be disposed. Hog production is of particular concern. Typical hog operations store concentrated animal waste in lagoons prior to land …

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Fact Sheet No.1: Nonpoint Source Pollution And Water Quality Of Northwest Arkansas, T. C. Daniel, D. R. Edwards, D. C. Wolf, K. F. Steele, M. J. Cochran Jan 1992

Fact Sheet No.1: Nonpoint Source Pollution And Water Quality Of Northwest Arkansas, T. C. Daniel, D. R. Edwards, D. C. Wolf, K. F. Steele, M. J. Cochran

Arkansas Water Resources Center Technical Reports

Preservation of a clean, safe, and biologically diverse environment can capture public attention as few other issues can. Indeed, recent international cooperative efforts indicate that there is an increasing global desire to pass on to future generations an environment at least equal in quality to the one we inherited.

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Phytoplankton Community Abundance And Diversity In Dardanelle Reservoir, Arkansas, 1981-1990, John D. Rickett, Robert L. Watson Jan 1992

Phytoplankton Community Abundance And Diversity In Dardanelle Reservoir, Arkansas, 1981-1990, John D. Rickett, Robert L. Watson

Journal of the Arkansas Academy of Science

Phytoplankton samples were collected quarterly from 1981-1990 at five stations representing discharge water from Arkansas Nuclear One, a nuclear generating station, and four "control" or "dispersal evaluation" stations. Seventy-five taxa representing five divisions were identified and enumerated. Community structure was evaluated using abundances, number of taxa, and Margalef's Richness, Shannon's Heterogeneity and Pielou's Evenness indices. No long-term trends were identified, but the beginning of cyclic variations, with a 7-year periodicity, in abundance, number of taxa, and Shannon's and Pielou's indices were apparent. Margalef's index values were constant during most of the study period. For all samples, t-tests and Mann-Whitney U …

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Bacteriological Water Quality Of Beaver Reservoir, Arkansas, Jimmy D. Bragg, Mark E. Clark Jan 1992

Bacteriological Water Quality Of Beaver Reservoir, Arkansas, Jimmy D. Bragg, Mark E. Clark

Journal of the Arkansas Academy of Science

Beaver Reservoir water quality was determined through enumeration of Total coliforms and Fecal coliforms bacterial parameters at selected locations during 1991. Several areas of the reservoir contained high numbers of indicator bacteria, suggesting excessive fecal contamination. Significant numbers of salmonella-like bacteria were also cultured on SS agar, and several strains were serotyped positive for Salmonella antigens.

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Hammett Correlations In The 1H Nmr Spectra Of Some N-Arlydihalonicotinamides, Frank L. Setliff, Nikhil G. Soman, Jody Z. Caldwell, Debra L. Rogers Jan 1992

Hammett Correlations In The 1H Nmr Spectra Of Some N-Arlydihalonicotinamides, Frank L. Setliff, Nikhil G. Soman, Jody Z. Caldwell, Debra L. Rogers

Journal of the Arkansas Academy of Science

Excellent linear correlations of amide proton chemical shifts (Snh) (in DMSO-d6 ) with Hammett substituent constants (5) for a series of 4-substituted anilides of four dihalonicotinic acid systems were observed. Dihalonicotinanilides with chlorine in the pyridine 2 - position exhibited a more positive slope in a Hammett plot of S^H vs - aR- where R is the substituent in the 4 position of the benzene ring. This observation is explained in terms of the inductive effect of chlorine which results in a slightly more acidic amide proton, which in turn causes an enhanced hydrogen bonding tendency to solvent. Four disubstituted …

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Model For The Co Poisoning Of Hydrodesulfurization Catalysts. Synthesis And Structure Of {Ru(Co)[Pph2sc12h7)]2cl2}.2ch2br2, Mark Draganjac, Thomas B. Rauchfuss, Arnold L. Rheingold Jan 1992

Model For The Co Poisoning Of Hydrodesulfurization Catalysts. Synthesis And Structure Of {Ru(Co)[Pph2sc12h7)]2cl2}.2ch2br2, Mark Draganjac, Thomas B. Rauchfuss, Arnold L. Rheingold

Journal of the Arkansas Academy of Science

The treatment of {Ru[(PPh2SC12H7)]2Cl2} with CO at ambient conditions results, after work up, in the isolation of the monocarbonylated species {Ru(CO)[(PPh2SC12H7)]2Cl2}, I. Crystals of I(C51H38Br4Cl20P2RuS2; F.W. = 1284.6) are triclinic; Ppa= 11.587(3), b = 13.010(4), c = 17.309(4) A, a = 93.32(2)°, p = 106.51(2)°, y = 91.29(2)°; Z= 2; V=2495(1) A';d^,. = 1.709 gem 1 X(MoKa) = 0.71073 A, = 37.7 cm 1 ;R =0.0748; Rw = 0.0714 for 4141 unique reflections. The geometry about the Ru(II) center is pseudooctahedral, with the phosphine ligands in the trans configuration. The Ru-S bond distance is 2.425(3) A.

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Schroedinger Equation With Spherically Averaged Potentials, C. A. Hughes Jan 1992

Schroedinger Equation With Spherically Averaged Potentials, C. A. Hughes

Journal of the Arkansas Academy of Science

Using a method adapted from few—body hyperspherical techniques, an approach to the solution of the Schroedinger equation with nonspherical potentials is discussed. The method is to spherically average the potential over spherical angles and then solve the resulting set of coupled differential equations. A discussion of how this method is applied to the Stark effect is presented.

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Zooplankton Community Abundance And Diversity In Dardanelle Reservoir, Arkansas, 1981-1990, John D. Rickett, Robert L. Watson Jan 1992

Zooplankton Community Abundance And Diversity In Dardanelle Reservoir, Arkansas, 1981-1990, John D. Rickett, Robert L. Watson

Journal of the Arkansas Academy of Science

Zooplankton samples were collected quarterly from five stations representing the discharge bay and four "control" or "dispersing impact" stations. Rotifers dominated all samples numerically and by the number of taxa. All major groups (Rotifera, Cladocera, Copepoda, and Protozoa) exhibited greatest abundances during the summer. Quarterly variations in abundance and number of taxa were documented. Except for an increase in taxonomic analysis detail between 1981 and 1984 resulting in several more taxa added to the list, no long-term increases, declines or repeating cycles were apparent. Margalef's Richness Index reflected this change and showed a long-term increase with evidence of a 5- …

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Development Of Organic Mud Mounds In A Mixed Carbonate-Siliciclastic Depositional Environment, John M. Ryan, Doy L. Zachry Jan 1992

Development Of Organic Mud Mounds In A Mixed Carbonate-Siliciclastic Depositional Environment, John M. Ryan, Doy L. Zachry

Journal of the Arkansas Academy of Science

Organic carbonate mud mounds in the Prairie Grove Member of the Hale Formation developed on a shallow shelf swept by competent tidal currents. The mounds were stabilized by crustose red algae and fostered a sheltered setting where phylloid algae and marine invertebrates could thrive. The mounds supplied skeletal sediment locally to the intermound areas as well as regionally along the stable platform. This sediment mixed with quartz sand to form a major mixed carbonate-siliciclastic system in northwestern Arkansas.

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4-Substituted Anilides Of 2,6- And 5,6- Dichlorolicotinic Acid. Potential Agricultural Agents, Frank L. Setliff, Nikhil G. Soman Jan 1992

4-Substituted Anilides Of 2,6- And 5,6- Dichlorolicotinic Acid. Potential Agricultural Agents, Frank L. Setliff, Nikhil G. Soman

Journal of the Arkansas Academy of Science

A series of 4-substituted anilides of 2,6- and 5,6 dichloronicotinic acid were prepared. The acids were first converted to their acid chlorides, which were in turn treated with the appropriate 4-substituted aniline in chloroform. A total of 16 anilides was thus prepared, and their structures confirmed. These compounds were prepared for testing as possible herbicidal, pesticidal or fungicidal agents

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Effect Of Aerosols On Climate Change, Haiyin Sun, Malay K. Mazumder Jan 1992

Effect Of Aerosols On Climate Change, Haiyin Sun, Malay K. Mazumder

Journal of the Arkansas Academy of Science

A modified two-stream approximation is presented, which includes the effect of solar zenith angle and is applicable to study the effect of aerosols on both regional and global climate changes. More realistic results are derived. A reasonable critical value of 0.8 for aerosol single scattering albedo to determine whether the aerosols will heat or cool the climate is derived

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Development Of A Variable Wavelength Flame Infrared Emission Gas Chromatography Detector, Weiqun Zhang, M. Keith Hudson, Mokhtar Mofidi Jan 1992

Development Of A Variable Wavelength Flame Infrared Emission Gas Chromatography Detector, Weiqun Zhang, M. Keith Hudson, Mokhtar Mofidi

Journal of the Arkansas Academy of Science

No abstract provided.

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Comparison Of Two Models For Breakdown Waves, Debra Burris, Mostafa Hemmati Jan 1992

Comparison Of Two Models For Breakdown Waves, Debra Burris, Mostafa Hemmati

Journal of the Arkansas Academy of Science

In this paper, the two theories concerning the propagation of breakdown waves are compared. The two theories are as follows: 1. The photoionization theory, in which the driving force of the propagation is the electromagnetic radiation from the hot gas generated at the electrode with the greatest potential gradient. 2. The electron fluid dynamical theory, in which the driving force of the propagation is the partial pressure of the high temperature electron gas generated in the neighborhood of the pulsed electrode. Successes in explaining the experimental data will be compared.

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Scf-Mo And Monte Carlo Calculations Of Poly (Dimethylsiloxane), Shannon H. Brownfield, Jerry A. Darsey Jan 1992

Scf-Mo And Monte Carlo Calculations Of Poly (Dimethylsiloxane), Shannon H. Brownfield, Jerry A. Darsey

Journal of the Arkansas Academy of Science

Self-consistent-field molecular orbital calculations are being used more and more extensively in determining the energies and properties of various confirmations of polymers. We are using the semi-quantum mechanical procedure MNDO (moderate neglect of differential overlap) to obtain various rotational conformations states of poly(dimethylsiloxane) (PDMS). Before calculation of these states, the molecule is geometrically optimized by using the ab initio procedure Guassian 86 at the 3-21G basis set level. Generations of 144 rotational states by rotating about two bonds simultaneously in increments of 30° were created. A potential energy surface was created from which Monte Carlo generated several polymer characteristics including …

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Using Physical, Chemical And Biological Indicators To Assess Water Quality On The Ouachita National Forest Utilizing Basin Area Stream Survey Methods, J. Alan Clingenpeel, Betty G. Cochran Jan 1992

Using Physical, Chemical And Biological Indicators To Assess Water Quality On The Ouachita National Forest Utilizing Basin Area Stream Survey Methods, J. Alan Clingenpeel, Betty G. Cochran

Journal of the Arkansas Academy of Science

The Ouachita National Forest (ONF) has developed a series of Best Management Practices (BMP's) designed to protect water quality and associated beneficial uses (fisheries, municipal water supplies, etc.). A monitoring program is necessary to document the effectiveness of that protection. The Basin Area Stream Survey (BASS) methodology provides a monitoring link from BMP's to the aquatic ecosystems. The goal of BASS is to identify the physical, chemical and biological characteristics of a stream in a format that will allow comparisons with other streams, and indicate when a stream is being impacted. Six index streams within two ecoregions were selected and …

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Evaluation Of Water Quality Data - Beaver Lake - Table Of Contents Through Section Iii, (Part I), James W. Moore Sep 1991

Evaluation Of Water Quality Data - Beaver Lake - Table Of Contents Through Section Iii, (Part I), James W. Moore

Arkansas Water Resources Center Technical Reports

No abstract provided.

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Evaluation Of Water Quality Data - Beaver Lake - Appendices C - K, (Part Iv), James W. Moore Sep 1991

Evaluation Of Water Quality Data - Beaver Lake - Appendices C - K, (Part Iv), James W. Moore

Arkansas Water Resources Center Technical Reports

No abstract provided.

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Evaluation Of Water Quality Data - Blue Mountain Lake, James W. Moore Sep 1991

Evaluation Of Water Quality Data - Blue Mountain Lake, James W. Moore

Arkansas Water Resources Center Technical Reports

No abstract provided.

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