Showing papers by "University of North Texas published in 1973"
TL;DR: Rodríguez et al. as mentioned in this paper investigated crystal formation by soil bacteria cultured on solid media and found that they can form aragonite (a form of CaCO3) crystals in cultures of Pseudomonas.
Abstract: CERTAIN bacteria form crystals from the solutes in their aqueous environment, and some authors have associated this activity with the extensive deposits of CaCO3 in such places as the Grand Bahama, in spite of the belief that physicochemical effects, such as rapid changes in pH, salinity and temperature, are responsible1–4. Drew5 isolated a denitrifying bacterium able to form CaCO3 crystals in liquid media and named it “Bacterium calcis” (later named Pseudomonas calcis6). Greenfield7 obtained aragonite (another form of CaCO3) crystals in cultures of Pseudomonas in an artificial seawater medium containing Na2CO3 or (NH4)2CO3. Buck and Greenfield reported the same result with marine yeast, and claimed that calcium crystals resulted from the accumulation of calcium deposits on the surface of the cells8. McCallum and Guhathakurta9 observed calcium carbonate deposition by marine bacteria isolated from Bahama Island sediments, and when these were cultured in different media aragonite crystals formed. Shinano10 described many marine bacteria able to form crystals in liquid media. Ramos-Cormenzana11 has also reported crystal formation by soil bacteria in solid media. This, together with the knowledge that previous research concerned only marine bacteria in liquid media, stimulated us to investigate crystal formation by soil bacteria cultured on solid media.
545 citations
TL;DR: In this paper, the 1,4-addition product of t-butyllithium and 1,3-butadiene, has been studied by PMR and UV methods in several ether solvents.
47 citations
40 citations
TL;DR: Effects of temperature on the rates of ingestion, egestion, assimilation, respiration and production indicate that the optimal temperature range for E. bislineata is 15–20°C.
38 citations
TL;DR: The K-shell ionization cross sections for Fe, Co, Cu, Zn, Ga, Ge, and As were measured for proton impact in the range 05 to 20 MeV as discussed by the authors.
Abstract: The K-shell ionization cross sections for Fe, Co, Cu, Zn, Ga, Ge, and As were measured for proton impact in the range 05 to 20 MeV The cross sections were found to be 242 plus or minus 23, 173 plus or minus 15, 941 plus or minus 78, 20 MeV These measurements agree to within less than 17% with predictions of the binary-encounter approximation Predictions of the plane-wave Born approximation exceed the measured values by approximately a factor of Z at the maximum deviation Corrections suggested by Brandt et al account for this discrepancy These measurements also indicate a trend for the measured ionization cross sections to drop below the theoretical predictions for low projectile energies (auth) Closed-form expressions for multiple-ionization crcas sections are developed in the semiclassical Coulomb approximation at low velocities The approximate expression for the Coulomb ionization probability, given by Brandt, Jones, and Kraner, is used to compute multiple-ionizaation cross sections These approximate cross sections are evaluated in closed form Results for multiple-K-, multiple-L-shell-ionization cross sections are given explicitly and compared to the full semiclassical-approximation theory and to experiment (auth)
37 citations
TL;DR: Calculation of Forage Ratios and Ivlev's Electivity Index indicated positive selection or election for baetid mayflies (Isonychia), Hydropsyche and Simulium and somewhat misleading negative selection was indicated by the indices for Cheumatopsyche.
Abstract: Corydalus cornutus L. larvae ingested larvae of Simulium (25.8%). Cheumatopsyche (23.9%), and Hydropsyche (l9.0%) with greatest frequency. Chironomidae larvae and Simulium pupae were ingested at 6.8% frequency, and 17 other aquatic insect food groups were ingested at lower frequencies. There was little diurnal periodicity in feeding, except that Hydropsyche larvae appeared to he ingested at higher rates after dusk. Calculation of Forage Ratios and Ivlev's Electivity Index indicated positive selection or election for baetid mayflies (Isonychia), Hydropsyche and Simulium. Because of abundance of Cheumatopsyche in the environment and a functional response in its predator-prey interaction with C. cornutus, somewhat misleading negative selection was indicated by the indices for Cheumatopsyche. Chironomids were taken at random or were slightly preferred February-April but were highly preferred in May. Simulium larvae were positively selected except in April; Electivity Index for them in May was maximum (1.0), and a high Forage Ratio (33) was determined.
34 citations
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TL;DR: The dietary overlap was significant for both species for winter months, but spring diets were dissimilar, and the significance of dietary overlap and degree of competition in P. hispidus and D. ordii is discussed.
Abstract: Winter and spring diets of Perognathus hispidus and Dipodomys ordii were analyzed and compared to food availability at three collecting sites in the mesquite-grasslands of west-central Texas. Important winter foods of P. hispidus were Prosopis juliflora, Helianthus annuus, Mammalaria sp., Artemisia ludoviciana , and Opuntia lindheimeri . Spring foods of P. hispidus included Prosopis juliflora, Gaillardia pulchella, Opuntia lindheimeri , carabid beetles, and Andropogon hallii . Insects made up 13.9 per cent of the spring diet. Major foods were selected for in amounts greater than expected on the basis of availability. Important winter foods of D. ordii were unidentified dry stems, Paspalum stramineum , and Prosopis juliflora . Insects made up 8.0 per cent of the winter diet. Major components of the spring diet of D. ordii were Andropogon hallii, Ambrosia artemisifolia, Prosopis juliflora , and Gaillardia pulchella ; insects and other arthropods made up 18.3 per cent of the spring diet. Few foods in the winter and spring diets of D. ordii were selected for. Both species of rodents exhibited little seasonal variation in food habits. The dietary overlap was significant for both species for winter months, but spring diets were dissimilar. The significance of dietary overlap and degree of competition in P. hispidus and D. ordii is discussed.
24 citations
TL;DR: In this paper, a 2 MV Van de Graaff was used to provide the protons and the X-ray energy spectra were measured with a high resolution Si(Li) detector.
22 citations
TL;DR: In this paper, collision diameters for some select transitions in the rotational spectrum of H 2 CO have been determined using pressure broadening of the spectral lines using pressure range from 0.001 Torr to 0.1 Torr.
TL;DR: The results of this study agree with earlier studies which indicate that massed group desensitization is an efficient and efficacious procedure for the reduction of anxiety based disorders.
Abstract: 30 test-anxious nursing students were randomly assigned to either a massed desensitization, placebo, or control group. All treatment was applied in 3 2-hr. and 20-min. sessions over an 8-day period. The massed group desensitization sessions began with 20 min. of recorded relaxation instructions. The remainder of the sessions consisted of Ss visualizing items from a test-anxiety hierarchy while concentrating on remaining relaxed. The placebo group sessions began with 20 min. of a recorded presentation on the merits of good study techniques, concentration, learning, and personal efficiency. Lectures on these topics comprised the remainder of the sessions. The control Ss merely received the pre- and post-treatment measures. A significant difference (p.01) was obtained on the posttest measure between the massed desensitization group and the placebo group and between the massed desensitization and control groups. The results of this study agree with earlier studies which indicate that massed group desensitizat...
TL;DR: From peptide maps and their autoradiograms, it is concluded that the primary structure adjacent to the glutamyl residue is the same as or similar to that found in triose phosphate isomerases from rabbit and chicken muscle and from yeast.
TL;DR: The title compound (NpAMg) is prepared by the reaction of anhydrous magnesium chloride with neopentylallyllithium in n-pentane solvent as mentioned in this paper.
TL;DR: In this article, the absorption spectra of TiCl 4, VCl 4 and SnCl 4 were compared with applicable theoretical results and available photoelectron data, and it was concluded that the higher energy transitions are due to the chlorine non-bonding electrons.
TL;DR: In this article, a series of new coordination complexes of oxovanadium(IV) and oxovadium(V) with tridentate ONO donor ligands are synthesized and characterized.
Abstract: A series of new coordination complexes of oxovanadium(IV) and oxovanadium(V) with tridentate ONO donor ligands are synthesized and characterized. The oxovanadium(IV) complexes are of the type: (i) VOL (H2O), (ii) VOL (py)2, (iii) VOL (ophen), (iv) VOL'·XH2O and (v) VOL' (ophen) (where LH2=2-hydroxynaphthylidene-amino acid, a tridentate dibasic ligand with ONO donor atoms; py=pyridine; ophen=orthopenanthroline; L'H2=2-hydroxynaphthylidene-orthoaminophenol). The oxovanadium(V) complexes are of the type: (i) VO(OCH3)L°CH3OH and (ii) [VO(OH)L]2. The VOL (H2O), VOL (py)2, VOL (ophen) and VOL' (ophen) complexes have normal magnetic moments (μ eff =1.70–1.74 BM) at room temperature. The VOL'·XH2O complexes exhibit subnormal magnetic moments at room temperature and at lower temperatures. Electron spin resonance data of VOL'·XH2O are reported. The oxovanadium(V) complexes are diamagnetic. Electrolytic conductance measurements indicate they are nonelectrolytes. Electronic spectra, infrared spectra and mole...
TL;DR: In this article, the relative yields of the cis -and α-neopentallyl isomers apparently depend on the steric bulk as well as the strength of the acid, and the degree of rearrangement observed from a series of ketones also is a function of the size of the ketone.
TL;DR: There was a marked difference in the toxicity of Dibrom to golden shiners between flowing and static systems but this was not statistically significant at the 95% confidence level.
Abstract: The respiratory activity of three aquatic animals, selected from different pollution index classifications, was examined in the presence of sublethal concentrations of Dibrom, a commonly used, broad spectrum, organophosphate insecticide. The oxygen consumption of Hydroperla crosbyi (Needham and Claassen), Corydalus cornutus L. and Notemigonus crysoleucas (Mitchill) was measured in a specially designed flowing-water respirometer, housed in an environmental chamber. The acute toxicity of Dibrom, measured as 24-hr LC50's for these animals, was compared in both static and flowing-water bioassays and found to be significantly more toxic to both the hell-grammites and stoneflies in the flowing system (LC50: 6.8 ppm and 11.4 ppb, respectively) than in the static bioassay (LC50:9.5 ppm and 16.0 ppb, respectively). There was a marked difference in the toxicity of Dibrom to golden shiners between flowing and static systems but this was not statistically significant at the 95% confidence level. Sublethal Di...
TL;DR: In this paper, the authors focused on the blind application of systematic desensitization to common fears as a means for preventing the occurrence of potential, and highly probable anxiety, by using an anxiety hierarchy of irrelevant scenes.
TL;DR: In this paper, an abbreviated account of the application of group implosive therapy with subjects who experienced test anxiety and related discomforts was given, while suggesting that group implosion may be an effective behavior therapy technique, were not conclusive.
TL;DR: It is concluded that the enzyme is a typical Class I, Type A muscle aldolase, and is suprisingly similar to the muscle a Aldolase of vertebrate origin.
Abstract: 1.
1. Fructose-1,6-diphosphate aldolase has been purified from the muscle tissue of the roundworm, Ascaris suum.
2.
2. The 157-fold purified enzymes exhibits a specific activity of 10·2 units/mg of protein and was judge to be homogeneous by the criteria of analytical ultracentrifugation, zone electrophoresis and rechromatography.
3.
3. Concomitant with the homogeneity studies the following physical parameters were established: S020,wW=7·98x10−13sec; D20,ww=4·43x10−7cm2/sec; Strokes' radius=46·4 A; f/f0=1·29.
4.
4. Sedimentation velocity and sedimentation equilibrium ultracentrifugation and analytical gel filtration yielded a molecular weight of 158,000±4000 for the native enzymes. The subunit molecular weight in 6 M guanidinium chloride or 0·1% sodium dodecyl sulfate is 41,000. Therefore, the enzyme is a tetramer.
5.
5. The apparent Michaelis constants determined for FDP and F1P were 6x10−5M and 3x10−2M, respectively. The catalytic ratio (FDP/F1P) was 42. The enzymes was unaffected by EDTA or potassium ions.
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6. It is concluded that the enzyme is a typical Class I, Type A muscle aldolase, and is suprisingly similar to the muscle aldolase of vertebrate origin.
TL;DR: In this paper, the vapor phase absorption spectra of PF3, PF2Cl, PFCl2, and PCl3 were reported in the vacuum ultraviolet spectral region 2400-1200 A.
TL;DR: In this article, the authors investigated the kinetics and mechanism of reactions of (2,2′-dipyridyl)W(CO)4 with SnCl4, (C6H5)SnCl3, (n-C4H9)snCl3 and (c6H 5)2SnCl2 with GeI4.
Abstract: The kinetics and mechanism of reactions of (2,2′-dipyridyl)W(CO)4 with SnCl4, (C6H5)SnCl3, (n-C4H9)SnCl3 and (C6H5)2SnCl2, and of (o-phenanthroline)Mo(CO)4 with GeI4 have been investigated employing stopped flow and conventional kinetic techniques. The oxidizing agent-dependent rate laws are encompassed in a mechanism which involves reversible addition of two successive molecules of the oxidant to the substrate, followed by other, rapid, steps. For the reaction of (C6H5SnCl2 with (dipy)W(CO)4 at 95–115°, a parallel reaction path probably involving rate-determining dissociation of CO was also observed. Rates were found to be very sensitive to the nature of the substituents bonded to the Group IV-A metal, being greatest for electron-withdrawing substituents. Different rate laws were observed for reactions which yielded products of different stereochemistries.
TL;DR: The usefulnes of Sigmodon arizonae as a laboratory animal for cytogenetic studies is substantiated and the procedure for obtaining G-bands on chromosomes of mammals is outlined.
Abstract: A procedure for obtaining G-bands on chromosomes of mammals is outlined. The procedure was utilized in an investigation of the idiogram and banding pattern of the mitotic chromosomes of the cotton rat, Sigmodon arizonae. The diploid number of this species is 22, and each pair of homologues is easily separated on the basis of size, centromeric position, and banding pattern. The autosomes are represented by four pairs of large submetacentric chromosomes, three pairs of medium to small submetacentric chromosomes, two pairs of large subtelocentric chromosomes and one pair of small acrocentric chromosomes. The X chromosome is acrocentric and averages from 5.42% to 5.46% of the haploid female complement. The Y chromosome is a minute acrocentric and easily separated from the smallest acrocentric autosome. The usefulnes of Sigmodon arizonae as a laboratory animal for cytogenetic studies is substantiated.
TL;DR: These findings are discussed with respect to the proposal that separate binding sites (catalytic and allosteric sites) exist on the quaternary enzyme protein, and that various effectors (including certain tryptophan and phenylalanine analogs), exert a modulating influence on the substrate binding and on the consequent catalysis at the catalytic sites.
TL;DR: Normative MMPI data for 85 clergymen entering counseling training at a state hospital were computed and the mean M MPI scores of Ss were similar to those reported previously for male marriage counselors.
Abstract: Normative MMPI data for 85 clergymen entering counseling training at a state hospital were computed. Basically, the mean MMPI scores of Ss were similar to those reported previously for male marriag...
TL;DR: A comparative study has been made of the ability of metal ions to catalyze the Lobry de Bruyn-Alberda van Ekenstein transformation and an analytical enzymic assay system was developed to monitor the rates of isomerization of hexose and triose phosphates.