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Showing papers by "United States Department of Energy published in 1983"


Journal ArticleDOI
TL;DR: In this article, the surface energy per surface atom is proportional to the cohesive energy per bulk atom, and a simple relationship between adsorbate-substrate vibrational stretch frequencies and their desorption energies follows from the universal relationship.
Abstract: Binding-energy-distance relations for metallic systems are shown to exhibit a universal behavior under a simple two-parameter scaling. All currently available ab initio calculations for the cohesion and adhesion of metals, as well as the chemisorption of gas atoms on metal surfaces, are shown to be determined by this single relation. Further, the energetics of diatomic molecules are determined by the same relation, despite the existence of strong volume-dependent forces for metals. These findings suggest a commonality of metallic bonding and a close relationship between molecular and metallic bonding. The universal nature of binding-energy-distance relations implies relations between seemingly disparate physical phenomena. As an example we show that the surface-binding-energy relation can be approximately expressed in terms of the bulk quantities. This leads to an explanation of the well-known empirical result that the surface energy per surface atom is proportional to the cohesive energy per bulk atom. Also, a simple relationship between adsorbate-substrate vibrational stretch frequencies and their desorption energies follows from the universal relationship.

483 citations


Journal ArticleDOI
TL;DR: In this article, a self-consistent pseudopotential method was used to calculate the equilibrium ground-state properties of transition metals Mo and Nb and obtain equilibrium lattice constants, cohesive energies, and bulk moduli which are in excellent agreement with experiment.
Abstract: We have used a self-consistent pseudopotential method to calculate the equilibrium ground-state properties of the transition metals Mo and Nb. From our calculations we obtain equilibrium lattice constants, cohesive energies, and bulk moduli which are in excellent agreement with experiment.

412 citations


Journal ArticleDOI
TL;DR: The mouse sperm morphology test has potential use for identifying chemicals that induce spermatogenic dysfunction and perhaps heritable mutations, and is found to be highly sensitive to germ-cell mutagens.
Abstract: The literature on the mouse sperm morphology test and on other sperm tests in nonhuman mammals was reviewed (a) to evaluate the relationship of these tests to chemically induced spermatogenic dysfunction, germ-cell mutagenicity, and carcinogenicity, and (b) to make an interspecies comparison to chemicals. A total of 71 papers were reviewed. The mouse sperm morphology test was used to assess the effects of 154 of the 182 chemical agents covered. 4 other murine sperm tests were also used: the induction of acrosomal abnormalities (4 agents), reduction in sperm counts, (6 agents), motility (5 agents), and F1 sperm morphology (7 agents)). In addition, sperm tests for the spermatogenic effects of 35 agents were done in 9 nonmurine mammalian species; these included analyses for sperm count, motility, and morphology, using a large variety of study designs. For the mouse sperm morphology test, 41 agents were judged by the reviewing committee to be positive inducers of sperm-head shape abnormalities, 103 were negative, and 10 were inconclusive. To evaluate the relationship between changes in sperm morphology and germ cell mutagenicity, the effects of 41 agents on mouse sperm shape were compared to available data from 3 different mammalian germ-cell mutational tests (specific locus, heritable translocation, and dominant lethal). The mouse sperm morphology test was found to be highly sensitive to germ-cell mutagens; 100% of the known mutagens were correctly identified as positives in the sperm morphology test. Data are insufficient at present to access the rate of false positives. Although it is biologically unclear why one might expect changes in sperm morphology to be related to carcinogenesis, we found that (a) a positive response in the mouse sperm morphology test is highly specific for carcinogenic potential (100% for the agents surveyed), and (b) overall, only 50% of carcinogens were positive in the test (i.e., sensitivity approximately equal to 50%). Since many carcinogens do not produce abnormally shaped sperm even at lethal doses, negative findings with the sperm test cannot be used to classify agents as noncarcinogens. We conclude that the mouse sperm morphology test has potential use for identifying chemicals that induce spermatogenic dysfunction and perhaps heritable mutations. Insufficient numbers of chemicals agents have been studied by the other sperm tests to permit similar comparisons. A comparison of 25 chemicals tested with sperm counts, motility, and morphology in at least 2 species (including man, mouse and 9 other mammals) demonstrated good agreement in response among species. With further study, interspecies comparisons of chemically induced sperm changes may be useful for predicting and evaluating human effects.

396 citations


Journal ArticleDOI
TL;DR: There is a reasonably good correlation between the results of the cell transformation systems and in vivo carcinogenesis, however, the many deficiencies of the EPA Merged Carcinogen List preclude definitive comparisons.
Abstract: The literature on cell transformation by chemical carcinogens has been critically reviewed. This subject is highly relevant to carcinogenesis in vivo, because the phenotypic changes that are collectively referred to as cell transformation usually involve the acquisition of tumorigenicity on inoculation into suitable rodent hosts. The systems chosen for review fall into 3 categories: cell strains (cells with a limited lifespan); cell lines (cells with an unlimited lifespan); and oncogenic viral-chemical interactions involving cells (Fischer rat embryo cells expressing an endogenous retrovirus, mouse embryo cells expressing the AKR leukemia virus, chemical enhancement of a simian adenovirus, SA7 transformation of Syrian hamster or rat embryo cells). Of the entire literature reviewed, 117 papers have been accepted for data abstraction by pre-defined criteria; these include 41 references to cell strains, 40 in cell lines, and 38 in viral-chemical interactions including cells. Because different systems have been reviewed, it would be meaningless to group all the compounds. The overall summary of the systems is as follows (many compounds have been tested in more than one system and, hence, are duplicated in these totals). (Chart: see text) In general, there is a reasonably good correlation between the results of the cell transformation systems and in vivo carcinogenesis. However, the many deficiencies of the EPA Merged Carcinogen List preclude definitive comparisons. Moreover, a number of 'false negatives' were obtained in systems that did not employ external metabolic activation. Further validation of all systems is required, but it seems very probable that several cell transformation systems will become valuable in assaying (with reasonable time and cost) the carcinogenic potential of environmental chemicals.

220 citations


Journal ArticleDOI
TL;DR: There is strong evidence that human sperm tests can be used to identify chemicals that affect sperm production, but because of the limited understanding of underlying mechanisms, the extent to which they can detect mutagens, carcinogens or agents that affect fertility remains uncertain.
Abstract: To evaluate the utility of sperm tests as indicators of chemical effects on human spermatogenesis, the literature on 4 sperm tests used to assess chemically induced testicular dysfunction was reviewed. The tests surveyed included sperm count, motility, morphology (seminal cytology), and double Y-body (a fluorescence-based test thought to detect Y-chromosomal nondisjunction). There were 132 papers that provided sufficient data for evaluation. These reports encompassed 89 different chemical exposures: 53 were to single agents; 14 to complex mixtures; and 22 to combinations of 2 or more identified agents. Approximately 85% of the exposures were to experimental or therapeutic drugs, 10% were to occupational or environmental agents, and 5% were to drugs for personal use. The most common sperm parameter studied was sperm count (for 87 of the 89 exposures reviewed). Sperm motility was evaluated for 59 exposures, morphology for 44, and double Y-bodies for only 4. The 89 exposures reviewed were grouped into 4 classes: those which adversely effected spermatogenesis, as measured by one or more of the sperm tests (52); those suggestive of improving semen quality (11); those showing inconclusive evidence of adverse effects from exposure (14); and those showing no significant changes (12). Since the reviewed reports had a large variety of study designs, and since every attempt was made to include all reports with interpretable data, these classifications were based on reviewing committee decisions rather than on uniform statistical criteria. This review gives strong evidence that human sperm tests can be used to identify chemicals that affect sperm production, but because of our limited understanding of underlying mechanisms, the extent to which they can detect mutagens, carcinogens or agents that affect fertility remains uncertain. For the very few agents studied with both human and mouse sperm tests, similar test-responses were seen; thus sperm tests in mice and other laboratory mammals may have a potential role in hazard identification. An overall comparison of the 4 human sperm tests suggests that no one test is biologically more responsive than another; all of them may thus be needed when testing for chemically induced changes from agents of unknown activity. This review also gives evidence that sperm tests can be used to assess the extent and the potential reversibility of induced spermatogenic damage. The reviewing committee recommends further studies to determine (a) the dose-response characteristics of the human sperm tests, (b) details of the reversibility of induced changes with time after exposure, (c) the relative responses in the 4 sperm tests in exposed individuals, (d) the mechanism of action, (e) the biological and genetic implications of chemically induced effects, and (f) the comparison of responses among different species for risk assessment. The reviewing committee outlines specific considerations for planning new sperm studies on chemically exposed men.

183 citations


Journal ArticleDOI
TL;DR: In this article, the authors established bounds on the number of modes which determine the solutions of the Navier-Stokes equations in 2-dimensional Rayleigh-Benard convection.

180 citations


Journal ArticleDOI
TL;DR: The test for sex-linked recessive lethals in Drosophila melanogaster has been used to detect induced mutations since 1927 and there were sufficient data available in the literature for analysis; 198 compounds were found to be positive and 46 negative at the highest concentration tested.
Abstract: The test for sex-linked recessive lethals (SLRL) in Drosophila melanogaster has been used to detect induced mutations since 1927. The advantage of the test for both screening and hazard evaluation is its objectivity in testing for transmissible mutations in the germ cells of a eukaryote. Statistical criteria for both positive and negative mutagenicity at the highest concentration tested under a particular exposure condition were developed by the Work Group, and a recommended protocol for future testing was agreed upon. For 421 compounds there were sufficient data available in the literature for analysis; 198 compounds were found to be positive and 46 negative at the highest concentration tested. Most experiments had been done for objectives of pure research rather than for deliberately screening for mutagenicity, although many of the 421 chemicals were selected for testing because of suspected mutagenicity. Therefore, the statement of 198 positive and 46 negative should not be taken as an example of the proportion of mutagens in the environment. In three sets of experiments with D. melanogaster that were done specifically for screening, one involving 40 compounds for the Environmental Protection Agency (EPA), the others involving 13 for the Food and Drug Administration (FDA), only 6 mutagens were discovered. After completion of the classification of compounds according to their response in the SLRL test, the compounds were classified as to their carcinogenic response according to the list of Griesemer and Cueto (1980). There were 62 compounds that could be classified as positive or negative for both carcinogenesis and mutagenesis. Of the 62 compounds, there was agreement between the carcinogenesis and mutagenesis classification in 56 (50 positive and 6 negative), or 90% would have been correctly classified as to carcinogenesis from only the SLRL test. Because of inadequate sample size, 177 compounds could not be classified as positive or negative according to the statistical criteria established by the Work Group. This large number of inadequately tested compounds reflects the fact that many of the experiments were not done for screening. Further work is needed on the compounds with inadequate sample size.(ABSTRACT TRUNCATED AT 400 WORDS)

157 citations


Journal ArticleDOI
TL;DR: The utility of unscheduled DNA synthesis (UDS) testing for screening potentially hazardous chemicals was evaluated using the published papers and technical reports available to the UDS Work Group and suggested protocols and evaluation criteria suitable for measuring and evaluating UDS by autoradiography in primary rat hepatocytes and diploid human fibroblasts and by the LSC approach.
Abstract: The utility of unscheduled DNA synthesis (UDS) testing for screening potentially hazardous chemicals was evaluated using the published papers and technical reports available to the UDS Work Group. A total of 244 documents were reviewed. Based on criteria defined in advance for evaluation of the results, 169 were rejected. From the 75 documents accepted, results were reviewed for 136 chemicals tested using autoradiographic approaches and for 147 chemicals tested using liquid scintillation counting (LSC) procedures; 38 chemicals were tested by both approaches to measure UDS. Since there were no documents available that provided detailed recommendations of UDS screening protocols or criteria for evaluating the results, the UDS Work Group presents suggested protocols and evaluation criteria suitable for measuring and evaluating UDS by autoradiography in primary rat hepatocytes and diploid human fibroblasts and by the LSC approach in diploid human fibroblasts. UDS detection is an appropriate system for inclusion in carcinogenicity and mutagenicity testing programs, because it measures the repair of DNA damage induced by many classes of chemicals over the entire mammalian genome. However, for this system to be utilized effectively, appropriate metabolic activation systems for autoradiographic measurements of UDS in human diploid fibroblasts must be developed, the nature of hepatocyte-to-hepatocyte variability in UDS responses must be determined, and the three suggested protocols must be thoroughly evaluated by using them to test a large number of coded chemicals of known in vivo mutagenicity and carcinogenicity.

105 citations


Journal ArticleDOI
TL;DR: In this paper, a binding energy relation between diatomic molecules and metals was found, which accurately describes adhesion, cohesion, and chemisorption on metals, and revealed a commonality between the molecular and metallic bond.
Abstract: Potential-energy relations involving a few parameters in simple analytic forms have been found to represent well the energetics of a wide variety of diatomic molecules. However, such two-atom potential functions are not appropriate for metals. It is well known that, in the case of metals, there exist strong volume-dependent forces which can never be expressed as pairwise interactions. The present investigation has the objective to show that, in spite of the observation concerning metals, a single binding-energy relation can be found which accurately describes diatomic molecules as well as adhesion, cohesion, and chemisorption on metals. This universality reveals a commonality between the molecular and metallic bond.

87 citations


Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of the proton spin-lattice and spin-spin relaxation times in yttrium and lanthanum dihydrides containing controlled levels of gadolinium as low as 50 ppm was investigated.
Abstract: Measurements are reported of the temperature dependence of the proton spin-lattice and spin-spin relaxation times ${T}_{1}$ and ${T}_{2}$ in yttrium and lanthanum dihydrides containing controlled levels of gadolinium as low as 50 ppm. The results demonstrate unambiguously that paramagnetic ions in concentrations so low as to have heretofore been regarded as insignificant have marked effects on the magnitude, frequency dependence, and temperature dependence of ${T}_{1}$ and to a lesser extent on ${T}_{2}$, and on the electronic structure and hydrogen diffusion parameters derived therefrom. The ${\mathrm{Gd}}^{3+}$ ion contributes an additional spin-lattice relaxation rate ${T}_{1p}$, which in these hydrides arises entirely from the dipolar coupling between impurity and proton moments. Proton magnetization is transported to the relaxation centers by spin diffusion at low temperatures and by hydrogen-atom diffusion at intermediate and high temperatures. The rate ${R}_{1p}$ is directly proportional to Gd-ion concentration at both low and high temperatures, but in the atom diffusion regime ${R}_{1p}$ is 20-25 times greater than for spin diffusion. The impurity-induced relaxation is shown to have profound effects on the apparent nuclear-nuclear dipolar relaxation rate ${R}_{1d}$ associated with hydrogen diffusion. At impurity levels as low as 10 ppm Gd, a secondary minimum appears in the temperature dependence of ${T}_{1}$ which may be readily misinterpreted in terms of a second motional process with lower activation energy. Even lower impurity levels yield a characteristic "slope-change" effect, which may be construed as indicating a change in the activation energy for hydrogen diffusion. At low temperatures ${R}_{1p}$ interferes with the determination of the conduction-electron contribution ${R}_{1e}$ and the Korringa product ${T}_{1e}T$. Separation of ${R}_{1e}$ and ${R}_{1p}$ is complicated by the fact the ${R}_{1p}$ is not temperature independent as has typically been assumed. Methods of achieving this separation are discussed, and it is shown experimentally that this difficulty can be circumvented by replacing the major part of the hydrogen with deuterium, thereby inhibiting spin diffusion. Measurement of ${T}_{1}$ as a function of resonance frequency and of ${T}_{2}$ can also be of value in separating the various sources of relaxation.

84 citations


Journal ArticleDOI
TL;DR: In this paper, the Hellmann-Feynman theorem is used to calculate the interatomic forces arising from the electronic response to a particular phonon distortion, which helps in visualizing the complicated microscopic interactions responsible for phonon anomalies.
Abstract: It is now possible to calculate accurately vibrational frequencies for transition metals entirely from first principles using the frozen-phonon approach. In addition, the interatomic forces arising from the electronic response to a particular phonon distortion can be calculated by making use of the Hellmann-Feynman theorem. Analysis of these forces helps in visualizing the complicated microscopic interactions responsible for phonon anomalies. The techniques and analysis are demonstrated for the important longitudinal ($\frac{2}{3}$,$\frac{2}{3}$,$\frac{2}{3}$) phonon in Mo, Nb, and bcc Zr. The stiffening of this mode as the electron-per-atom ratio increases from Nb to Mo is shown to arise from a development of directional bonding. The precipitous dip in this mode for the high-temperature bcc phase of Zr and the instability of bcc Zr towards the formation of the $\ensuremath{\omega}$ phase are related to the $d$-electron screening and details of the electronic structure.

Journal ArticleDOI
TL;DR: The correlation of the TK locus assay results with the carcinogenicity data revealed that 2 agents were definite false positives, while benzo[e]pyrene was a questionable false negative, and the assay is of value in the battery approach to mutagenicity/carcinogenicity screening.
Abstract: The predominant test system uses a near-diploid L5178Y mouse lymphoma cell line and is based on the quantitation of forward mutations occurring at the heterozygous thymidine kinase (TK) locus (TK+/- leads to TK-/-). (Other markers, such as ouabain- or methothrexate-resistance and alanine independence, in other L5178Y mouse lymphoma cells were also examined, but our criteria for the acceptability of data or the paucity of data considerably reduced the value of these mutagenesis test systems to this study.) The biochemical basis for the L5178Y/TK+/- assay depends on the ability of TK-competent cells to phosphorylate 5-bromo-2'-deoxyuridine or trifluorothymidine. The phosphorylated product or its metabolites kill these cells, thus, medium containing 5-bromo-2'-deoxyuridine or trifluorothymidine is capable of selecting for cells that are lacking the TK enzyme (TK-/-). TK-/- cells eventually give rise to a bimodal distribution of colony sizes. The relative proportion of small and large colonies appears to be characteristic of the mutagen, its dose, and the length of the expression period. A total of 108 references were reviewed and 48 chemical agents were evaluated. Of these, in vivo carcinogenicity data existed for 44 and covered a wide variety of chemical classes (43 compounds) and a complex mixture. In this system, 39 agents were positive, 1 was negative, and 4 yielded inconclusive results. The 44 test substances evaluated were insufficient to single out agents or agent classes for which the assay was particularly well suited; however, with the exception of thymidine analogs, the system seems to be versatile. The correlation of the TK locus assay results with the carcinogenicity data revealed that 2 agents were definite false positives (sodium azide and methotrexate) and 1 agent was a definite false negative (1,1-dimethylhydrazine). Further evaluation suggested that 4-acetylaminofluorene and diphenylnitrosamine were questionable false positives, while benzo[e]pyrene was a questionable false negative. (The term questionable was used to imply uncertainties concerning the mutagenicity and/or carcinogenicity data). Thus, the assay is of value in the battery approach to mutagenicity/carcinogenicity screening.

Journal ArticleDOI
TL;DR: Experimental piston-displacement equations of state are given for sodium, potassium, and rubidium to 20 kbar for temperatures from 4 K to just below the melting line in each case.
Abstract: Experimental piston-displacement equations of state are given for sodium, potassium, and rubidium to 20 kbar for temperatures from 4 K to just below the melting line in each case. Except for sodium at high pressures, where the low-temperature bcc-hcp martensitic transition appears to cause problems, these data can be represented by a room-temperature pressure-volume reference function and a thermal pressure which is a function of temperature only. In addition, these three solids appear to obey a reduced equation of state at both 4 K and room temperature, for which $\frac{V}{{V}_{0}}$ is a common function of $\frac{P}{{B}_{0}}$. A modification of the second-order Murnaghan equation which is well behaved at large compressions is used to extrapolate these results to 40 kbar for comparison with higher-pressure, room-temperature results. These data are compared with other high-pressure equation-of-state experiments and are extrapolated to $P=0$ to obtain thermal expansions and isothermal bulk moduli, which in turn are compared with results from other measurements. These comparisons and those with theoretical calculations show, on the whole, satisfactory agreement. The elementary form for the temperature-dependent equation of state is in agreement with a previous suggestion that the Gr\"uneisen parameter is temperature independent and is a linear function of the volume for temperatures greater than the Debye temperature. The 295-K Gr\"uneisen parameters for these solids, as deduced from the high-pressure results, are 1.24 for sodium and potassium and 1.26 for rubidium.

Journal ArticleDOI
TL;DR: In this paper, positive ions were extracted from the axial channel of an inductively coupled plasma (ICP) in which the outer gas flow was Ar, N2, or a mixture of Ar and N2.
Abstract: Positive ions were extracted from the axial channel of an inductively coupled plasma (ICP) in which the outer gas flow was Ar, N2, or a mixture of Ar and N2. Addition of N2 to the outer gas decreases the electron number density (ne) in the axial channel. Ar+2, O2+, and ArH+ react with N-containing species in the plasma and/or during the ion extraction process. Ar+ remains abundant even if there is no Ar in the outer gas, which indicates the probable occurrence of charge transfer reactions between N2+ and Ar. The present work corroborates two general concepts upon which several theories of the origin of suprathermal ionization in ICPs are based: (a) species are physically transported from the induction region to the axial channel; and (b) these species may react with and ionize neutral species in the axial channel. Ionization temperatures (Tion) measured from the ratio Cd+/I+ were 5750 to 6700 K for a N2 outer flow ICP at a forward power of 1.2 kW. This Tion range is significantly below that obtained for an Ar outer gas ICP under otherwise similar operating parameters.

Journal ArticleDOI
TL;DR: In this paper, a 46-parameter modified valence force field was determined for pyridine and its deuterium and methyl derivatives, and the average error between the 777 observed and calculated frequencies is 7.8 cm−1 or 0.98%.

Journal ArticleDOI
TL;DR: In this paper, the authors measured elastic and inelastic scattering of 24 Mg+24 Mg in 100 keV steps over the bombarding energy range 84 −100 MeV.

Patent
04 Jan 1983
TL;DR: In this paper, a method of and apparatus for testing the integrity of individual filters or filter stages of a multistage filtering system including a diffuser permanently mounted upstream and/or downstream of the filter stage to be tested for generating pressure differentials to create sufficient turbulence for uniformly dispersing trace agent particles within the airstream upstream and downstream of such filter stage.
Abstract: A method of and apparatus for testing the integrity of individual filters or filter stages of a multistage filtering system including a diffuser permanently mounted upstream and/or downstream of the filter stage to be tested for generating pressure differentials to create sufficient turbulence for uniformly dispersing trace agent particles within the airstream upstream and downstream of such filter stage. Samples of the particle concentration are taken upstream and downstream of the filter stage for comparison to determine the extent of particle leakage past the filter stage.

Journal ArticleDOI
01 Jun 1983-Fuel
TL;DR: The distributions of nitrogen compounds in crude and hydrotreated shale oil products have been determined as mentioned in this paper, and the nitrogen compound types in these fractions were characterized by i.r. spectroscopy, differential potentiometric titration, and high-resolution m.s.

Journal ArticleDOI
01 Apr 1983-Fuel
TL;DR: In this article, electron spin resonance studies of the early stages of carbonization of a high-volatile A bituminous coal have been used to detect and quantify transient free radicals present in the coal pyrolysate.

Patent
29 Nov 1983
TL;DR: In this article, a servo controller is used to regulate switching in response to the load current to maintain a selected load current, which is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller.
Abstract: A power supply for driving an inductive load current from a dc power supplyhrough a regulator circuit including a bridge arrangement of diodes and switching transistors controlled by a servo controller which regulates switching in response to the load current to maintain a selected load current. First and second opposite legs of the bridge are formed by first and second parallel-connected transistor arrays, respectively, while the third and fourth legs of the bridge are formed by appropriately connected first and second parallel connected diode arrays, respectively. The regulator may be operated in three "stages" or modes: (1) For current runup in the load, both first and second transistor switch arrays are turned "on" and current is supplied to the load through both transistor arrays. (2) When load current reaches the desired level, the first switch is turned "off", and load current "flywheels" through the second switch array and the fourth leg diode array connecting the second switch array in series with the load. Current is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller. (3) Rapid current rundown is accomplished by turning both switch arrays "off", allowing load current to be dumped back into the source through the third and fourth diode arrays connecting the source in series opposition with the load to recover energy from the inductive load. The three operating states are controlled automatically by the controller.

Journal ArticleDOI
TL;DR: In this article, rotational bands have been found in the Y ground bands with small values of 0.3-0.4 and imply that these nuclei are among the most deformed known.
Abstract: Six rotational bands have been found in $_{39}^{99}\mathrm{Y}_{60}$, $_{39}^{101}\mathrm{Y}_{62}$, $_{38}^{99}\mathrm{Sr}_{61}$, and $_{40}^{101}\mathrm{Zr}_{61}$. All bands have small and very similar values of $\frac{{\ensuremath{\hbar}}^{2}}{2\mathcal{I}}$ that indicate deformations of \ensuremath{\sim} 0.3-0.4 and imply that these nuclei are among the most deformed known, with $\mathcal{I}\ensuremath{\sim}0.8{\mathcal{I}}_{\mathrm{rigid}}$. Relative strengths of intraband $\ensuremath{\gamma}$ transitions suggest Nilsson orbital assignments of $\ensuremath{\pi}\frac{5}{2}[422]$ for the Y ground bands.

Journal ArticleDOI
TL;DR: In this paper, a new burn-probe sequence was used with non-photochemical hole burning to study the optical dephasing of impurities in polymer films, and a burn time dependence of hole width was observed and discussed.

Journal ArticleDOI
TL;DR: In this paper, threshold voltages and other basi c breakdown characteristics, spanning times from microseconds to cable life expectancy, were determined for crosslinked inked polyethyene ( XLPE) and ethylene propylene rubber (EPR) cables.
Abstract: Threshold voltages and other basi c breakdown characteristics, spanning times from microseconds to cable life expectancy, were determined for cross-linked inked polyethyene ( XLPE) and ethylene propylene rubber (EPR) cables. These results are based upon measurements of 60Hz, high frequency, impulse, and impulse with d.c. bias voltages.

Journal ArticleDOI
TL;DR: Inelastic neutron scattering techniques have been used to study the temperature dependence of the phonon dispersion curves of bcc Mo as discussed by the authors, and it has been shown that with increasing temperature, the largest relative decrease in phonon frequencies occurs for the Ω( √ √ n)-branch in the vicinity of the $H$ point in the Brillouin zone.
Abstract: Inelastic neutron scattering techniques have been used to study the temperature dependence of the phonon dispersion curves of bcc Mo. We find that, with increasing temperature, the largest relative decrease in phonon frequencies (\ensuremath{\sim}12%) occurs for the $\mathrm{L}[\ensuremath{\xi}\ensuremath{\xi}\ensuremath{\xi}]$ branch in the vicinity of $\ensuremath{\xi}=\frac{2}{3}$. The phonon frequencies in the vicinity of the $H$ point in the Brillouin zone, on the other hand, increase slightly with increasing temperature. As a result, at high temperatures, the anomalous drop in the phonon frequencies at $H$ decreases in magnitude and the $\mathrm{L}[\ensuremath{\xi}\ensuremath{\xi}\ensuremath{\xi}]$ branch develops a dip at $\ensuremath{\xi}=\frac{2}{3}$. The experimental results also indicate that the phonon anomaly in the vicinity of point $N$ is less pronounced at high temperatures. For the purpose of comparison with the experimental results, we have performed first-principle "frozen-phonon" calculations for the longitudinal-phonon frequencies of Mo at the ($\frac{2}{3}$,$\frac{2}{3}$,$\frac{2}{3}$) and $H$ points of the Brillouin zone. The results show that thermal expansion and anharmonicity can account for the temperature dependence of the ($\frac{2}{3}$,$\frac{2}{3}$,$\frac{2}{3}$) longitudinal-phonon frequency. For the $H$ phonon, on the other hand, the thermal expansion and anharmonicity terms cannot account for the observed frequency shift and we suggest that the contributions arising from the electron-phonon renormalization and the thermal disorder of the lattice must be included.

Journal ArticleDOI
TL;DR: In this article, the effects of this correlation on the mixed-valent properties of Ce systems were discussed and it was suggested that the double-peak $4f$ photoemission spectra of Ce and Th indicate strong $d\ensuremath{-}f$ correlation.
Abstract: In a recent paper it was suggested that the double-peak $4f$ photoemission spectra of Ce and ${\mathrm{Ce}}_{0.9}$${\mathrm{Th}}_{0.1}$ indicate strong $d\ensuremath{-}f$ correlation. This paper discusses the effects of this correlation on the mixed-valent properties of Ce systems. In the impurity-lattice approximation, which is valid at high temperatures, the $f$-electron spectrum has the well-known x-ray-edge singularity at the Fermi level. The inclusion of $d\ensuremath{-}f$ hybridization adds fine structures to the spectrum near the Fermi level. Furthermore, the singularity can account for the Kondo-type resistivity and specific-heat anomalies without the need to invoke spin-flip scattering.

Journal ArticleDOI
TL;DR: In this paper, computer simulations were used to study the propagation of cracks coated with thin solid films in a 2D triangular Lennard-Jones solid and the key parameter investigated was the mismatch in the interatomic distances of the film and the substrate (the eleastic moduli were kept the same).

Patent
22 Mar 1983
TL;DR: In this article, the halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of water or polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent.
Abstract: A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contacting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible compound, such as, water or a polyhydroxy compound, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of water or polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the water or polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds and the low polar or nonpolar solvent are separated by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered from recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced.

Journal ArticleDOI
TL;DR: The results indicate that deactivation from S3 → S2 → S1, thought to be the dominant pathway in chloroplasts, is not the case for PS II preparations, and it was demonstrated that the ratio of S1 to S0 can be set by previously developed techniques, that S0 is formed mostly from activated S3 (S4), and that both S0 and S1 are stable in the dark.

Patent
12 Oct 1983
TL;DR: In this article, a method whereby silicon carbide-bonded SiC fiber composites are prepared from carbon-bunded C fiber composite material is disclosed, which can be used for fabricating dense, high-strength high-toughness SiC composites or as thermal insulating materials in oxidizing environments.
Abstract: A method whereby silicon carbide-bonded SiC fiber composites are prepared from carbon-bonded C fiber composites is disclosed. Carbon-bonded C fiber composite material is treated with gaseous silicon monoxide generated from the reaction of a mixture of colloidal silica and carbon black at an elevated temperature in an argon atmosphere. The carbon in the carbon bond and fiber is thus chemically converted to SiC resulting in a silicon carbide-bonded SiC fiber composite that can be used for fabricating dense, high-strength high-toughness SiC composites or as thermal insulating materials in oxidizing environments.

Journal ArticleDOI
01 Sep 1983-Fuel
TL;DR: An electron beam technique has been developed for the direct determination of organic sulphur in coal, using a scanning electron microscope coupled with an energy-dispersive X-ray analysis system with quantitative data reduction capabilities as mentioned in this paper.