bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relative Efficiencies of Quenching of Mercury Resonance Radiation and Their Temperature Independence. Mechanism of Mercury Photosensitized Decomposition of Saturated Hydrocarbons
Authors: Cvetanović R. J. 
Published: April 2005

Relative over-all efficiencies of quenching of mercury resonance radiation have been determined for N2O, n-C4H10, C2H6, and C2H4 by studying the binary mixtures of each of the hydrocarbons with nitrous oxide at 23° and 120°C. For N2O and n-C4H10 the relative efficiency of quenching to the ground state as well as the fractions of quenching to the ground and to the metastable 6(3P0) state of mercury for each of the two compounds have also been determined. Temperature independence of the primary quenching processes has been demonstrated.
A proposed mechanism of quenching by saturated hydrocarbons, based on additional experimental information obtained with n-butane alone and its mixtures with nitrous oxide, interprets fully the experimental facts and in particular accounts for the repeatedly observed low quantum yields of hydrogen formation.
Theory of Dielectric Relaxation for a Single-Axis Rotator in a Crystalline Field. II
Authors: Hoffman John D. 
Published: April 2005

Previous work on the relaxation times associated with a polar single-axis rotator where the dipole may occupy three or four orientational sites by turning in a lattice point has been extended to include the more general case where the energies of the sites (as well as the intervening barriers) are all different. The results for these more general models tend to confirm the view that the presence of barriers of different magnitudes between the equilibrium orientations of a dipole can be the source of a set of discrete dielectric relaxation times.
The dielectric properties of some specialized three- and four-position models are then considered in detail. A very narrow or an extremely wide set of relaxation times can be obtained depending on the nature of the barrier system, and accordingly, a wide range of dielectric behavior can be accommodated. Despite the wide range of behavior, certain qualitative features (noted in Sec. VII in italics) appear to persist in many of the models. These features may be useful in applying the theory in a general way.
The equations given will facilitate the calculation of the properties of three- and four-position models not already considered.
Use of Molecular Quantum-Mechanical Approximations Exemplified in the Energy Calculation of the H3— System
Authors: Barker Roland S. , Eyring Henry , Baker Don A. , Thorne Charles J. 
Published: April 2005

Certain approximations of molecular quantum mechanics are examined. The size of the resultant error due to approximate methods for specific multicenter integral evaluations are cited. Examination of the Sklar approximate multicenter electron repulsion formula together with the generalizations and extensions of Vroeland and Löwdin allow application of the underlying approximation principle to three center nuclear attraction integrals. Specific approximate formulation of these integrals is given.
The accumulation of computational errors arising from the many individual integral approximations in the energy evaluation of the linear H3— system is specifically examined. The ground state energy of this system found from the Heitler-London and Wang-like treatments were — 70 kcal/mole and — 84 kcal/mole for the Sklar type approximations, — 1 kcal/mole and — 19 kcal/mole for the Mulliken type approximations, and — 26 kcal/mole and — 41 kcal/mole for exact integral evaluations.
It is concluded that the Sklar type approximations, while preferable to the Mulliken type in a few specific evaluations lead like that formulation to considerable discrepancy between the over-all energy obtained for a polyatomic system. The Sklar approximations have the further disadvantage of requiring two-center integral evaluations not needed in the over-all energy calculations. However, both the Sklar and the Mulliken approximations do give a rapid method for evaluating ``best'' distance and effective charge parameters for use with more extensive exact integral variational method calculations.
Proton Magnetic Resonance of the CH3 Group. III. Reorientation Mechanism in Solids
Authors: Powles J. G. , Gutowsky H. S. 
Published: April 2005

The proton magnetic resonance absorption has been reported to change with temperature in a manner suggesting hindred C3 rotational motions of the CH3 groups in several solid compounds. In this paper, the reorientation mechanism is considered more closely. The second moments of the absorption lines are calculated as a function of temperature for three types of motion. Similar predictions are obtained for two classical models, a Brownian type rotation by random angles and a random jumping between fixed positions 2π/3 apart. The results are different for the third model, a quantum-mechanical tunnel effect, for which approximate calculations are given.
The experimental data for methyl chloroform, 2,2-dinitropropane, and 2-chloro-2-nitropropane can be fitted either to a classical model or to the tunnel effect by adjusting the potential barrier to the reorientations. However, the activation energies for classical rotation are low, about 2.2 kcal mole—1 and the observed frequency factors of 107 are unexplained. The tunnel effect gives larger barriers, about 5 kcal, and the predicted frequency factors agree well with experiment. In the case of 2,2-dichloropropane a classical motion is indicated by the large frequency factor of 1012.
Dissociation of Solid SrO by Impact of Slow Electrons
Authors: Moore George E. 
Published: April 2005

Dissociation of solid SrO by impact of electrons having energy below 400 v was measured by a mass spectrometer method. Positively and negatively charged dissociation products were observed with equal sensitivity; no uncharged products were observed with an arrangement having poorer sensitivity. The fundamental dissociation products are Sr+, Sr++, and O+ with essentially no O−. Surface impurities such as CO, Cl, F, and H were also abundant. The only source of chlorine found was an impurity in the original SrCO3, of about 1 part in 105. However, its abundance in the ion current is about equal to that of oxygen, and the yields of Cl+ and Cl− are about equal. All particles must come essentially only from the surface layers.
Yields of Sr+ and Sr++ increase with the square of electron density; yields of O+, Cl+, and Cl− increase, respectively, with the 1.5, 1.0, and 1.0 power of electron current density. The process is quite inefficient, the impact of 107 electrons giving about 1 fundamental dissociation product for 20 to 30 ma per cm2 of bombarding current. Yields are independent of electron energy from slightly above threshold to beyond 200 v, above which they decline slowly. Yields increase slightly with temperature, corresponding to activation energies of a few tenths of a volt.
At least some of the chlorine on the surface probably exists in the uncharged form; threshold energies are too low to convert a Cl− on the surface to a Cl+ in the vacuum. Removal of O+, Sr+, and Sr++ ions is discussed in terms of a crystal composed of singly charged Sr+ and O− ions; a process involving two incoming electrons in rapid succession on a minute area is apparently required for removal of an O+, Sr+, or Sr++ ion.
Magnetic Annealing in Perminvar. I. Structural Origin
Authors: Heidenreich R. D. , Nesbitt E. A. , Burbank R. D. 
Published: April 2005

This paper deals with the results of an electron diffraction investigation of the structure of soft magnetic materials which exhibit magnetic annealing. The property of heat treatment in a magnetic field has been found to depend upon the oxygen content present as an impurity and is associated with distinct diffraction phenomena. A structural model based on an interpretation of diffraction results, magnetic properties, and oxygen content is presented.
The pertinent conclusions from this study are:
1. The ability of soft magnetic alloys containing Fe, Co, and Ni to exhibit magnetic annealing properties is due to oxygen present as an impurity.
2. An oxygen content of about 0.001% is sufficient to produce magnetic annealing with the proper heat treatment. An alloy containing only 0.0001% oxygen fails to respond to field heat treatment or is ``dead.''
3. The oxygen impurity produces magnetic activity in the alloy crystal (with proper heat treatment) by condensing into the (111) planes of the crystal, thus giving rise to a stacking disorder or fault. The term ``impurity fault'' has been introduced to describe this structural irregularity.
4. The oxygen impurity faults are presently thought to be aligned by magnetic annealing and are intimately connected with field heat treatment properties. If sufficient oxygen is available in the crystal, the faults thicken and organize to yield metal oxides.
Band Structure Parameters Deduced from Tunneling Experiments
Authors: Hall R. N. , Racette J. H. 
Published: April 2005

Measurements of the voltage and temperature dependence of tunneling in Ge and GaSb are presented which confirm the close proximity of the (000) and (111) conduction band edges in these materials. In the case of Ge, the energy separation of these edges is found to increase with increasing donor concentration.
Tunneling in the indirect semiconductor GaP shows no evidence for indirect (phonon-assisted) tunneling transitions. It is believed that tunneling in the junctions which we studied proceeds via deep-level impurities rather than between conduction and valence bands directly, thereby eliminating the requirement of wave number conservation.
Revised values for the zone-center longitudinal optical phonon energies as deduced from tunneling data in 3–5 and lead salt semiconductors are presented.
Recent Studies of Bismuth Telluride and Its Alloys
Authors: Goldsmid H. J. 
Published: April 2005

This paper reviews the work which has been carried out in these Laboratories during the past two years on single crystals of bismuth telluride and its alloys.
The combination of experiments on Faraday rotation with those performed previously on galvanomagnetic effects has established that there are 3- and 6-valley band structures associated with p- and n-type Bi2Te3, respectively. However, observations of the anisotropy ratio for the electrical conductivity and of the galvanomagnetic coefficients for heavily doped n-type material have shown that the shape of the equal-energy surfaces is dependent on carrier concentration. Similar conclusions have been drawn from the behavior of the Seebeck coefficient at low temperatures.
Measurements on Bi2Te3 at low temperatures and on alloys of Bi2Te3 have shown that the lattice thermal conductivity is particularly sensitive to the substitution of atoms of I, Se, or S for those of Te. It has also been shown that the anisotropy ratio for the lattice thermal conductivity is almost the same for the alloys as for pure Bi2Te3.
Some Electrical and Optical Properties of ZnSe
Authors: Aven M. , Marple D. T. F. , Segall B. 
Published: April 2005

Single crystals of ZnSe have been prepared by the vapor growth technique and optical and electrical measurements on these crystals are reported. Analysis of the reststrahlen reflection peak gives 0.026 ev for the transverse optical phonon energy. The longitudinal optical phonon energy is 0.031 ev as calculated from the transverse phonon energy, the static dielectric constant, ε0=8.1±0.3, and the high-frequency dielectric constant, ε∞=5.75±0.1. The effective ionic charge calculated from the Szigetti formula is 0.7±0.1. Exciton absorption peaks associated with the valence and conduction bands in the vicinity of Γ were observed at liquid hydrogen temperature with the principal peak at 2.81±0.01 ev. The exciton reduced mass 0.1 m0 combined with the room temperature electron-to-hole mobility ratio of 12, obtained by preliminary transport measurements on n- and p-type ZnSe gives tentative values of 0.1 m0 and 0.6 m0 for the electron and hole masses, respectively.
Reflectance was determined by various methods in the range 0.025 to 14.5 ev photon energy and was analyzed by the Kronig-Kramers inversion method to obtain the optical constants in the 1 to 10 ev range. A number of peaks appear in the imaginary part of the dielectric constant.
The first set of peaks, 2.7 and 3.15 ev, are believed to be due to exciton and interband transitions at Γ with a spin-orbit valence band splitting of 0.45 ev. The second set of peaks, 4.75 and 5.1 ev, are tentatively assigned to transitions at L with a spin-orbit splitting of 0.35 ev. Other peaks are observed at higher energies.
Vacancy Pairs and Dislocations in Ionic Crystals
Authors: Kurosawa Tatsumi 
Published: April 2005

(1) We have calculated the binding energy of vacancy pairs in NaCl and the other five alkali halide crystals. The calculations is improved at several points compared with that by Reitz and Gammel. The calculated values of the binding energy are considerably smaller than e2/ka and differ from the result by Reitz and Gammel; for instance, 0.44 ev in NaCl, 0.37 ev in NaBr, and 0.58 ev in KCl crystals.
(2) As the first step of the systematic investigations of dislocation problems, we have calculated the core energy and the Peierls-Nabarro critical yield stress of the edge dislocation for slip in the (110) plane in NaCl type crystal [the Burgers vector is a (110)]. If we write the energy of the dislocation at the center of a cylinder with radius R as K ln (R/R0), R0 is about 1 A in most of the alkali halide crystals. The results of the calculation concerning the Peierls-Nabarro yield stress permit us to understand the well-known fact that LiF has much larger critical yield stress compared with the other alkali halide crystals.
Effects of Thermal-Mechanical Treatments on Faulting in Some fcc Alloys
Authors: Mikkola D. E. , Cohen J. B. 
Published: April 2005

An increase in stacking fault probability associated with a solute with the same atomic size but a higher valence than the solvent was found by comparing filed Ag and Ag-6 at. % Al. The stacking fault and twin fault probabilities in ordered Cu3Au, where the atoms differ in size only, were higher than for either pure Cu or Au after deformation at and below room temperature. The stacking fault probability was lower in filings of quenched Cu3Au and Cu-14.3 at. % Al alloys, than in slowly cooled specimens. There is a close correlation between measured fault probabilities and available data on fault energies and Fermi surface configurations.
Twin faults were found in Cu-base alloys deformed at room temperature as well as at low temperatures.
Stacking faults in filings of Cu-14.3 at. % Al annealed out in two stages. The second stage was associated with recrystallization, with an activation energy similar to that for interdiffusion in this system. Twin faults were more stable than stacking faults.
Fiber Texture and Magnetic Anisotropy in Evaporated Iron Films
Authors: Yelon A. , Asik J. R. , Hoffman R. W. 
Published: April 2005

The fiber texture and magnetic anisotropy of evaporated iron films have been studied as a function of film thickness. It is found that there are three textures present: [110], [111], and [221]. In thin films, the [111] texture is dominant. It is also found that the magnetic anisotropy is of the order of 2×104 ergs/cm3 for 350-A films and decreases with increasing thickness.
On the basis of this experiment and information from earlier experiments, several theories of the origin of magnetic anisotropy in films are examined, and shown to be inadequate for iron films. A theory for the origin of the anisotropy is proposed, based primarily on the magnetic energy associated with an array of vacancy needles. These vacancy needles can also qualitatively explain the resistivity anisotropy and dichroism observed by other workers.
Diffraction by a Half-Plane Perpendicular to the Distinguished Axis of a Uniaxially Anisotropic Medium
Authors: Przeździecki S. 
Published: April 2005

The solution to the three-dimensional problem of diffraction of a plane electromagnetic wave by a perfectly conducting half-plane embedded in a uniaxially anisotropic medium perpendicularly to the distinguished axis of the medium is presented.
A fundamental feature of the considered problem is its essentially vectorial character, i.e., its solution cannot be reduced to solving one scalar boundary-value problem for one function satisfying its second-order equation.
The solution has been constructed via a synthesis of the solutions to appropriate auxiliary scalar half-plane diffraction problems for two distinct wave equations. In connection with these auxiliary problems an examination of diffraction of inhomogeneous plane waves by a half-plane proved necessary.
A general approach to analysis of electromagnetic fields in uniaxially anisotropic media by splitting them into two component fields of TE and TM type with respect to the distinguished axis of the medium has been summarized in the form of a theorem.
IT Alignment in Supply Chain Relationships: A Study of Supplier Benefits
Authors: Sanders Nada R. 
Published: April 2005

SummaryDeployment of interorganizational information technology (IT) throughout supply chain networks has usually been championed by supply chain network leaders — large firms that typically dominate a supply chain network. In order to participate in a particular network, supplier firms must acquire the requisite IT enabling them to be technologically aligned with the network leader. This is an important decision for supplier firms that are typically smaller in size and must allocate larger portions of their budgets to acquire the necessary IT. This study evaluates the benefits gained by suppliers when investing in interorganizational IT that is aligned with their primary buyer or network leader. The findings show that IT alignment between supplier and buyer has a direct positive impact on both strategic and operational performance measures of the supplier. In addition, IT alignment impacts these performance measures indirectly as it encourages integration between firms.
Nicotine analogues: a review of tobacco industry research interests
Authors: Vagg Rosemary , Chapman Simon 
Published: April 2005

ABSTRACTAims  To explore the tobacco industry's interest and intentions driving its nicotine analogue research.Methods  Review of internal tobacco industry documents regarding nicotine analogues released as part of the Master Settlement Agreement between the tobacco industry and US state governments in 1998.Findings  The tobacco industry investigated nicotine analogues extensively. Four principal areas of interest are evident. First, research on tobacco products was directed towards greater understanding of nicotine pharmacology, how to screen for potential analogues and how to separate the central and peripheral effects of nicotine. Secondly, interest lay in the potential for analogues to replace nicotine in order to create more ‘desirable’ products and to circumvent anticipated nicotine regulation. Thirdly, interest lay in potential pharmaceutical applications for analogues such as treatments for neurological disorders. Finally, there was interest in the public relations potential of the therapeutic potential of analogues to reduce the demonization of nicotine, by allowing the industry to point to its beneficial uses.Conclusions  With tobacco product and nicotine regulation being increasingly advocated in tobacco control it is important to understand the industry's interests in the potential role of nicotine analogues. Initial interest included using analogues as a means to circumvent regulation, but evidence suggests these plans were discarded due to fear that this may have instigated regulation of tobacco products. Nicotine analogue research has led to potential therapeutic uses for Alzheimer's and Parkinson's diseases and alarmingly for the industry, to a potential vaccine to prevent nicotine addiction.Recommendations  Tobacco manufacturers should be obliged to declare all additives being used in tobacco products. Regulatory bodies should be aware that that there is a distinct possibility that the industry has discovered ways to circumvent future regulation of nicotine through the utilization of nicotine analogues. Any regulatory drafting should broaden the definition of nicotine in order to incorporate analogues into the scope of pharmacologically active substances being regulated.
HCV viremia is associated with drug use in young HIV‐1 and HCV coinfected pregnant and non‐pregnant women*
Authors: Nikolopoulou Georgia B. , Nowicki Marek J. , Du Wenbo , Homans James , Stek Alice , Kramer Francoise , Kovacs Andrea 
Published: April 2005

ABSTRACTAims  Vertical transmission of HCV is increased among HIV‐1/HCV coinfected women and is related to HCV viral load. In this study we assessed clinical and demographic factors associated with HCV viremia in a cohort of young pregnant and non‐pregnant mothers coinfected with HIV‐1.Design  A cross‐sectional clinic‐based study nested within a prospective cohort study.Methods  From 1988 to 2000, HIV‐1 + pregnant and non‐pregnant women with children followed in a large maternal, child and adolescent HIV‐1 clinic were evaluated for HCV infection using EIA 3.0. HCV RNA levels were determined for HCV antibody + women using polymerase chain reaction. Demographic and clinical characteristics between HCV‐RNA(+) and HCV‐RNA(–) women and between pregnant and non‐pregnant HIV‐1/HCV coinfected women were compared using univariate and multivariate analyses.Findings  Among 359 HIV‐1(+) women, 84 (23%) were HCV‐ab + and 49/84 (58%) had detectable HCV‐RNA in plasma. Median age was 31. CD4 counts, HIV‐1 RNA levels and demographic characteristics were similar for viremic and non‐viremic women and pregnant and non‐pregnant women. However, viremic women were more likely to report a history of (88% versus 43%; P < 0.001) or active injection drug use (AIDU) (83% versus 29%; P < 0.001). Logistic regression analysis showed that HCV viremia was associated significantly with AIDU (adjusted OR: 15.17; 95% CI: 3.56, 64.56) after adjusting for age, race, number of sexual partners, pregnancy status, CD4 counts and HIV‐1 viral load.Conclusion  In this cohort of young HIV‐1 and HCV coinfected women, HCV viremia was associated strongly with active injection drug use, perhaps due to reinfection or reactivation of HCV. Thus, careful evaluation for HCV infection and counseling related to drug use may be necessary.