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Articles 31471 - 31500 of 34554

Full-Text Articles in Physical Sciences and Mathematics

Thermochemistry Of A Structurally Defined Aldol Reaction., Edward Arnett, Franklin Fisher, Michael Nichols, Anthony Ribeiro Jan 1989

Thermochemistry Of A Structurally Defined Aldol Reaction., Edward Arnett, Franklin Fisher, Michael Nichols, Anthony Ribeiro

Michael A Nichols

No abstract provided.


The Activation Of Carbon-Fluorine Bonds By Oxidative Addition At Tungsten(O): An Electrochemical Study, Andrea Russell, Carolyn Osterberg, Daniel Blackwood, Mark Anderson, Thomas Richmond, Stanley Pons Jan 1989

The Activation Of Carbon-Fluorine Bonds By Oxidative Addition At Tungsten(O): An Electrochemical Study, Andrea Russell, Carolyn Osterberg, Daniel Blackwood, Mark Anderson, Thomas Richmond, Stanley Pons

Mark R. Anderson

We have investigated the anodic oxidation reactions of W(CO)4Et,F5 (I), where Et,F5 is the ligand N,N'-bis(pentafluorophenylidine)ethylenediamine, by cyclic voltammetry and infrared spectroelectrochemistry. The results in both acetonitrile and methylene chloride indicate an ece type mechanism, with the product of the first electron transfer stabilized by the more coordinating solvent.


Estimating Vaporization Enthalpies Of Organic Compounds With Single And Multiple Substitution, James S. Chickos, Donald G. Hesse, Joel F. Liebman Jan 1989

Estimating Vaporization Enthalpies Of Organic Compounds With Single And Multiple Substitution, James S. Chickos, Donald G. Hesse, Joel F. Liebman

James Chickos

No abstract provided.


Rotoreflected Double-Beam Thermal Lens Spectrometry And Simultaneous Thermal Lens And Fluorescence Detection For High Performance Microbore Liquid Chromatography, Steven Craig Hall Jan 1989

Rotoreflected Double-Beam Thermal Lens Spectrometry And Simultaneous Thermal Lens And Fluorescence Detection For High Performance Microbore Liquid Chromatography, Steven Craig Hall

Dissertations

No abstract provided.


Multinuclear Magnetic Resonance Studies Of Lithium Binding And Transport In Human Erythrocytes, Maryceline Tiausas Espanol Jan 1989

Multinuclear Magnetic Resonance Studies Of Lithium Binding And Transport In Human Erythrocytes, Maryceline Tiausas Espanol

Dissertations

No abstract provided.


Synthesis And Study Of N-(4-Nitrobenzofurazan)-Monoaza-18-Crown-6: A Metal Sensitive Fluorophore, Shelley A. Krause Jan 1989

Synthesis And Study Of N-(4-Nitrobenzofurazan)-Monoaza-18-Crown-6: A Metal Sensitive Fluorophore, Shelley A. Krause

Dissertations

No abstract provided.


Structural And Functional Studies Of The Plant Lectin Peanut Agglutinin, Eugene J. Zaluzec Jan 1989

Structural And Functional Studies Of The Plant Lectin Peanut Agglutinin, Eugene J. Zaluzec

Dissertations

No abstract provided.


Rotational Experiments., C. K. Revell Jan 1989

Rotational Experiments., C. K. Revell

Experimental Summaries - Plant Research

Trial 82M47

a. Subterranean clover.

Subterranean clover rotation trial
Merredin Research Station.

Trial 88ME83

b. Santiago burr medic

Rotational systems for burr medic
Merredin.

Trial 89N29

Rotational systems for burr medic.
Newdegate Research Station.


Pasture Deterioration Trial, J. W. Bowden, R. J. Lunt Jan 1989

Pasture Deterioration Trial, J. W. Bowden, R. J. Lunt

Experimental Summaries - Plant Research

Trial 89NA61

Location: Duranillin

In this site we would expect a very large response (40 to 50% ) to phosphorus.

History:

The site was chosen because of the patchy and poor pasture production. The poor areas tend to have more suckling clover than the good areas. The pasture was legume dominant.

Treatments were applied on April 16, 1989.


Pasture Species Investigations., D. A. Nicholas Jan 1989

Pasture Species Investigations., D. A. Nicholas

Experimental Summaries - Plant Research

Trial 87V7, 87MT52, 87MA31

Selection of subclover cultivars - mid to late maturing.

To select in the field subterranean clover cultivars of mid to late maturity having superior persistence and productivity.

Location: Vasse Research Station, Mount Barker Research Station, Wilgarup.


Cultivar Evaluation On Low Rainfall Heavy Textured Soils., Bradley Nutt Jan 1989

Cultivar Evaluation On Low Rainfall Heavy Textured Soils., Bradley Nutt

Experimental Summaries - Plant Research

a. Trial 88GE34

Cultivar evaluation in machine sown plots.
Location: NMRS

The higher seed yield of Serena compared to the other cultivars resulted in better early forage .production as well a legume dominated pasture.

b. Trial 88TS 63 and 88TS 65

Wheat yields following pastures.
Location: 88TS63 - Perenjori and 88TS65 - Three Springs.

There was no response to nitrogen in either biological yield or grain yield of wheat sown over volunteer based pasture at the Three Springs site. All pasture treatments resulted in similar wheat yields except for Sava because of poor control of the snail medic under the …


Aphid Tolerance Evaluation In Annual Medics., Bradley Nutt Jan 1989

Aphid Tolerance Evaluation In Annual Medics., Bradley Nutt

Experimental Summaries - Plant Research

Trial 89GE61

Location: East Chapman

Out of the 100 lines tested, 30 experimental lines were less affected (in terms of seed yield) by aphid damage than c.v. Parabinga.


Soil-Plant-Sheep Organochlorine Pesticide Research, Tony Albertsen Jan 1989

Soil-Plant-Sheep Organochlorine Pesticide Research, Tony Albertsen

Experimental Summaries - Plant Research

1. Soil O/C decay (5812)

Locations: Brookhampton, Carbunup, Dardanup, Denmark, Donnybrook, Goodwood, Jindong, Kirrup, Manjimup, Pemberton, Redmond.

To determine the rate of decay of soil Dieldrin.

2. Soil profile distribution of O/Cs (5812) (88AL21/1)

To determine the distribution of O/cs at 1 cm intervals down the soil profile.

3. Soil decontamination of O/Cs (5812)

To assess practical and economic techniques for decontaminating soil Dieldrin residues.

4. The accumulation and rundown of Dieldrin in wethers. (5841)

To determine the relationship between the levels of Dieldrin contamination in soil, pasture, sheep body and wool fat.

5. Surface drainage trial 86V1/5164

Efficient surface …


Tactical Nitrogen Decisions For Wheat (And N Rates Trials), J. W. Bowden, R. J. Lunt Jan 1989

Tactical Nitrogen Decisions For Wheat (And N Rates Trials), J. W. Bowden, R. J. Lunt

Experimental Summaries - Plant Research

Trial 89NO77 (89NO76)

Location: Grass Valley.

History: 1984 Lupins.

1985/86 pasture legumes and about 100 kg super/ha.

1987 Wheat yield of 2.8 t/ha using 45 kg DAP/ha and 60 of urea 2-4 WAS.

1988 Gungurru lupins (27 kg/ha seed) yielding 1.9 t/ha using 80 kg super/ha.

Tactical nitrogen trials - summary of treatments required.

Trial 89NO77

Location: Meckering

Treatments existed of nitrogen and urea. Nitrogen was not applied at seeding. Urea was applied at seeding.

Trial 88No77

Tactical nitrogen trials. - summary of observations.

Location: Grass Valley.

Trial 89NO76

Hand harvest 23/11/1989.
Yield components for copper sufficient plots reps. I …


Organic Geochemical And Petrographic Analysis Of Pure Macerals From The Ohio Shale, Michael A. Kruge, Susan M. Rimmer, John C. Crelling Jan 1989

Organic Geochemical And Petrographic Analysis Of Pure Macerals From The Ohio Shale, Michael A. Kruge, Susan M. Rimmer, John C. Crelling

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Recent advances now permit the separation of coal into constituent macerals of high purity using density gradient centrifugation (DGC). With the availability of pure macerals, the chemical structure of each can be investigated separately, without the interactive interference of the other macerals or mineral matter. The present study is a preliminary effort applying these methods to the study of oil shale kerogen.

We have used a sample from the Huron Member of the Upper Devonian Ohio Shale from Logan County, Ohio. Whole rock petrographic examination revealed intact Tasmanites, telalginite of unknown derivation and a weakly fluorescing matrix. Pyrite is abundant, …


The Exchange Potential In Path Integral Studies: Analytical Justification, Randall W. Hall Jan 1989

The Exchange Potential In Path Integral Studies: Analytical Justification, Randall W. Hall

Collected Faculty and Staff Scholarship

We present analytical justification for our previously described exchange pseudopotential. We show how the fermi quantum partition function can be constructed from the Boltzmann (distinguishable particle) wave functions if the states that correspond to like‐spin electrons occupying the same quantum state are excluded. A class of weighting functions that satisfy this constraint approximately is discussed. Our previous pseudopotential falls under this class. Essentially, our pseudopotential forces the unwanted states to have high energy and, hence, to make negligible contribution to the partition function. Exchange potentials of the form discussed in this article should be useful for studying systems where the …


Intrinsic Reaction Coordinate Calculations For Very Flat Potential Energy Surfaces: Application To Singlet Si2h2 (Disilenylidene) Isomerization, Shiro Koseki, Mark S. Gordon Jan 1989

Intrinsic Reaction Coordinate Calculations For Very Flat Potential Energy Surfaces: Application To Singlet Si2h2 (Disilenylidene) Isomerization, Shiro Koseki, Mark S. Gordon

Mark S. Gordon

Si2H2 is an important species that may appear in the chemical vapor deposition of silicon. This paper reports an intrinsic reaction coordinate (IRC), or a minimum energy path (MEP), of the isomerization from silasilene to bridged disilyne obtained by using the local cubic and quadratic approximations. These. new approximations generate a correct IRC for this isomerization, while some conventional methods fail to predict a reasonable IRC because of the very flat potential energy surface. This reaction path bifurcates to two identical IRCs to reach bridged disilyne. The activation energy for this isomerization is predicted to be less than 3 kcalfmol. …


Transition State Structure, Barrier Height, And Vibrational Frequencies For The Reaction Cl+Ch4→Ch3+Hcl, Thanh N. Truong, Donald G. Truhlar, Kim K. Baldridge, Mark S. Gordon, Rozeanne Steckler Jan 1989

Transition State Structure, Barrier Height, And Vibrational Frequencies For The Reaction Cl+Ch4→Ch3+Hcl, Thanh N. Truong, Donald G. Truhlar, Kim K. Baldridge, Mark S. Gordon, Rozeanne Steckler

Mark S. Gordon

We have carried out a b i n i t i o calculations using second‐ and fourth‐order Mo/ller–Plesset perturbation theory, scaled electron correlation, and several basis sets for the reaction Cl+CH4→CH3+HCl. We found that including electron correlation is essential for obtaining accurate barrier heights and vibrational frequencies. Furthermore, scaling the correlation energy further improves the barrier height predictions provided that the basis set being used is correlation balanced for both bonds involved in the reaction. Geometries and transition state frequencies calculated at the MP2 and MP‐SAC2 levels with the most extensive and best balanced basis set are in good agreement …


Friedrich Wöhler, John Alfred Heitmann Jan 1989

Friedrich Wöhler, John Alfred Heitmann

History Faculty Publications

Friedrich Wöhler synthesized urea in 1828 and thus first demonstrated that organic materials, heretofore believed to possess a vital force, need not be made exclusively within living organisms. He also isolated aluminum metal in 1827 and discovered the elements beryllium and yttrium.


Electron Affinity Of Chlorine Dioxide, Lucia M. Babcock, Thomas C. Pentecost, W. H. Koppenol Jan 1989

Electron Affinity Of Chlorine Dioxide, Lucia M. Babcock, Thomas C. Pentecost, W. H. Koppenol

Peer Reviewed Articles

The flowing afterglow technique was used to determine the electron affinity of chlorine dioxide. A value of 2.37 ± 0.10 eV was found by bracketing between the electron affinities of HS° and SF4 as a lower limit and that of NO2 as an upper limit. This value is in excellent agreement with 2.32 eV predicted from a simple thermodynamic cycle involving the reduction potential of the C102/C102- couple and a Gibbs hydration energy identical with that of SO2-.


Identification Of A Variant Form Of The Human Estrogen Receptor With An Amino Acid Replacement, T. Garcia, M. Sanchez, J. L. Cox, P. A. Shaw, J. B. A. Ross, S. Lehrer, B. Schachter Jan 1989

Identification Of A Variant Form Of The Human Estrogen Receptor With An Amino Acid Replacement, T. Garcia, M. Sanchez, J. L. Cox, P. A. Shaw, J. B. A. Ross, S. Lehrer, B. Schachter

Chemistry and Biochemistry Faculty Publications

Estrogen receptor (ER) is a ligand-dependent transcriptional regulator. ER protein has several functionally distinct regions, including a DNA-binding domain in its midportion, a ligand binding domain in the carboxy terminal region, and at least one domain, in the amino terminal region, that influences the magnitude of transcriptional enhancement (1,2). We now report the sequence of a frequently occurring ER genetic variant that carries two point mutations in the region of the gene encoding the amino terminal domain of the protein.


The Effect Of Seed Origin And Seed Phosphorus On The Growth Of Lupins, M. M. Riley, M. D. Bolland, K. Adcock Jan 1989

The Effect Of Seed Origin And Seed Phosphorus On The Growth Of Lupins, M. M. Riley, M. D. Bolland, K. Adcock

Experimental Summaries - Plant Research

Trial: 89SC20

Location: South Carrabin Research Station, Hayden paddock.

The effects of superphosphate and fertilizer on seeds planted over a 21 week period.


Effect Of Seed Phosphorus, Seed Size And Seedling Density On The Growth Of Lupins., M. M. Riley, M. D. Bolland, K. Adcock Jan 1989

Effect Of Seed Phosphorus, Seed Size And Seedling Density On The Growth Of Lupins., M. M. Riley, M. D. Bolland, K. Adcock

Experimental Summaries - Plant Research

Trial 89SC22

Location: South Carrabin Research Station, Hayden paddock.

Effect of seed phosphorus concentration, fertilizer P level, seed size and seeding rate on plant counts at 6 to 21 weeks.


Mössbauer Effect Studies Of Nd₂Fe₁₄₋ₓsiₓb And Y₃Fe₁₄₋ₓsiₓb, Oran Allan Pringle, Gary J. Long, G. K. Marasinghe, William Joseph James, Antoni T. Pedziwiatr, W. E. Wallace, Fernande Grandjean Jan 1989

Mössbauer Effect Studies Of Nd₂Fe₁₄₋ₓsiₓb And Y₃Fe₁₄₋ₓsiₓb, Oran Allan Pringle, Gary J. Long, G. K. Marasinghe, William Joseph James, Antoni T. Pedziwiatr, W. E. Wallace, Fernande Grandjean

Physics Faculty Research & Creative Works

No abstract provided.


The Nitrogen Response Of Wheat Crops Following Lupins, I C. Rowland, Mel Mason, John Hamblin Jan 1989

The Nitrogen Response Of Wheat Crops Following Lupins, I C. Rowland, Mel Mason, John Hamblin

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

One of the many benefitsof growing narrow-leaved lupins in a crop rotation (Rowland et al 1988) in the increased yield of the following cereal crop as a result of the improved nitrogen level of the soil.

This article reports the results from 41 wheat/lupin rotation trials involving a range of nitrogen rates throughout the Western Australian agricultural area between 1978 and 1987. These trials allowed scientists to assess the interaction of nitrogen fertilization with previous cropping history and to estimate some of the contribution of the nitrogen and other effects of lupins within the crop rotations. The results provide some …


Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood Jan 1989

Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Relation between Dry Diameter (Xo) and Critical Supersaturation (Sc) for Atmospheric Submicron Aerosol Particles is Investigated. the Particles Are Passed through an Electrostatic Aerosol Size Classifier, and Then through an Isothermal Haze Chamber. Results Are Reported in Terms of an Apparent Volume Fraction of Soluble Material, Εv, Defined Such that for Particles Composed Only of Ammonium Sulfate and Water Insoluble Compounds, Εv is the Actual Volume Fraction of Soluble Material. the Probability Distribution of Εv is Found to Be Approximately Gaussian in the Εv Range 0.2 to 1.3. the Mean Εv is 0.5, for Electrostatic Aerosol Classifier Settings of …


A Theoretical Study Of Models For X2y2 Zintl Ions, Robert J. Cave, Ernest R. Davidson, Philippe Sautet, Enric Canadell, Odile Eisenstein Jan 1989

A Theoretical Study Of Models For X2y2 Zintl Ions, Robert J. Cave, Ernest R. Davidson, Philippe Sautet, Enric Canadell, Odile Eisenstein

All HMC Faculty Publications and Research

Ab initio and extended Hückel calculations have been used to discuss the bonding scheme in X₂Y₂ neutral and ionic main group clusters. A qualitative analysis suggests that two different electron counts, 20 and 22, are possible for the butterfly structures of these systems. This results from two orbital crossings in the correlation diagram for the tetrahedral (T_d) -> butterfly (C_2v) -> square-planar (D_2h) transformation. Detailed ab initio computations substantiate this analysis and show that the 20-electron butterfly structure becomes increasingly favored over the tetrahedral one in X₂Y₂ clusters when the 2 atoms have increasing electronegativity difference. …


Morning Increase In Onset Of Ischemic Stroke, John R. Marler, Thomas R. Price, Gregory L. Clark, James E. Muller, Thomas Robertson, Jay P. Mohr, Daniel B. Hìer, Philip A. Wolf, Louis R. Caplan, Mary A. Foulkes Jan 1989

Morning Increase In Onset Of Ischemic Stroke, John R. Marler, Thomas R. Price, Gregory L. Clark, James E. Muller, Thomas Robertson, Jay P. Mohr, Daniel B. Hìer, Philip A. Wolf, Louis R. Caplan, Mary A. Foulkes

Chemistry Faculty Research & Creative Works

The Time of Onset of Ischemic Stroke Was Determined for 1,167 of 1,273 Patients during the Collection of Data by Four Academic Hospital Centers between June 30, 1983, and June 30, 1986. More Strokes Occurred in Awake Patients from 10:00 Am to Noon Than during Any Other 2-Hour Interval. the Incidence of Stroke Onset Declined Steadily during the Remainder of the Day and Early Evening. the Onset of Stroke is Least Likely to Occur in the Late Evening, Before Midnight. © 1989 American Heart Association, Inc.


Determinants Of Early Recurrence Of Cerebral Infarction: The Stroke Data Bank, R. L. Sacco, M. A. Foulkes, J. P. Mohr, P. A. Wolf, D. (Daniel) B. Hier, T. R. Price Jan 1989

Determinants Of Early Recurrence Of Cerebral Infarction: The Stroke Data Bank, R. L. Sacco, M. A. Foulkes, J. P. Mohr, P. A. Wolf, D. (Daniel) B. Hier, T. R. Price

Chemistry Faculty Research & Creative Works

We Studied 1,273 Patients with Ischemic Cerebral Infarction Who Were Entered into the Stroke Data Bank, a Prospective, Observational Study Involving Four University Hospitals and the Biometry and Field Studies Branch of the National Institute of Neurological Disorders and Stroke. Forty Patients Had Non-Iatrogenic Recurrent Stroke within 30 Days after the Index Cerebral Infarction. using Life Tables, the 30-Day Cumulative± SE Risk of Early Recurrence for All Infarctions Was 3.3±0.4%. the Risk of Early Recurrence Was Greatest for Atherothrombotic Infarction (7.9±2.2%, Eight of 113 Patients) and Least for Lacunar Infarction (2.2±1.2%, Eight of 337 Patients). Both Cardioembolic Infarction (4.3±0.9%, 10 …


Predictors Of Survival In Clinically Diagnosed Alzheimer's Disease And Multi-Infarct Dementia, Daniel B. Hier, Joshua D. Warach, Philip B. Gorelick, Joseph Thomas Jan 1989

Predictors Of Survival In Clinically Diagnosed Alzheimer's Disease And Multi-Infarct Dementia, Daniel B. Hier, Joshua D. Warach, Philip B. Gorelick, Joseph Thomas

Chemistry Faculty Research & Creative Works

No abstract provided.