bluuebunny/crossref_metadata_2025 huggingface dataset:
Primary prevention of secondary disorders: A proposal and agenda
Authors: Kessler Ronald C. , Price Richard H.
Published: January 2005

This paper calls for consideration of a new class of preventive interventions designed explicitly to prevent comorbidity of psychiatric disorders. Epidemiologic data show that successful interventions of this type could be extremely valuable, as up to half of lifetime psychiatric disorders and an even larger percent of chronic and seriously impairing disorders occur to people with a prior history of some other disorder. Furthermore, a review of etiologic hypotheses concerning the causes of comorbidity suggests that interventions aimed at primary prevention of secondary disorders might be feasible. However, more basic risk factor research is needed on the causes of comorbidity before we can make a clear assessment of feasibility and discover promising intervention targets. A number of methodological problems arise in carrying out this type of formative research. These problems are reviewed and suggestions are offered for solutions involving innovations in measurement, design, and data analysis.
Linking qualitative and quantitative methods in cross‐cultural survey research: Techniques from cognitive science
Authors: Hines Alice M.
Published: January 2005

Survey research with diverse cultural and ethnic minority groups is a complex and challenging endeavor that confronts the researcher with problems related to linguistic and conceptual equivalence and measurement as well as problems related to difficulties that respondents have with the sociocultural dimensions of the survey/interview process. One way to improve the quality of cross‐cultural surveys and to insure that the findings are culturally relevant and accurate is to combine qualitative and quantitative methods. This paper proposes that certain qualitative techniques from cognitive science, specifically cognitive anthropology and cognitive psychology, are particularly well suited to being combined with survey research. These techniques provide information corresponding to the underlying thought processes of respondents and enable researchers to better understand how different cultural and ethnic groups construe the world. The information obtained can be used improve the formulation of survey questions, design and structure questionnaire formats to coincide with the way particular groups organize concepts, and help researchers understand difficulties respondents may have with the survey/interview process. In addition, the techniques produce data that are easily codifiable and more manageable than traditional qualitative techniques including participant observation and in‐depth interviews.
Using focus groups to facilitate culturally anchored research
Authors: Hughes Diane , DuMont Kimberly
Published: January 2005

Scholars have acknowledged the need to anchor scientific knowledge about social and psychological processes in the norms, values, and experiences of the partticular population under study. This article describes how focus groups can be incorporated into the planning stages of a research pogram to facilitate these goals. After a brief overview of teh central components of focus group research, and example from a program of research involving dual‐earner African American families is used to as an illustration. The article describes how (a) the identification of cultural knowledge and (b)access to the language participants use to think and talk about a topic can help researchers formulate a conceptual framework, identify important constructs, and develop appropriate instruments for assessing constructs. Some strengths and limitations of focus group research are discussed.
Psychological aspects of genetic counseling. VII. Thoughts on directiveness
Authors: Kessler Seymour
Published: January 2005

Directiveness and nondirectiveness in genetic counseling are poorly understood on the operational level, and information about what counselors allege they do and what actually is done in practice is lacking. Although they are often thought of as diametrically opposite approaches, when viewed as strategies of persuasion, their similarities become more apparent. Directive counselors attempt to influence the counselee's behavior, whereas nondirective ones attempt to influence the latter's thinking processes; there is need for both approaches. Directiveness may also sometimes occur because of inadequate interview skills. The case made for directiveness is discussed and critiqued, available research is reviewed, and suggestions for future studies are advanced.
A NEW SPECIES OF RHODODENDRON (ERICACEAE) FROM CHINA
Authors: GAO L.-M. , LI D.-Z.
Published: January 2005

A new species of Rhododendron (Ericaceae), R. truncatovarium (subgen. Azaleastrum), from Yunnan, SW China, is described and illustrated. Details of its pollen morphology are also provided.
NEW SPECIES IN ECHIDNOPSIS AND SECAMONE AND NEW RECORDS OF CEROPEGIA (APOCYNACEAE) FROM SOCOTRA
Authors: BRUYNS P. V.
Published: January 2005

The new species Echidnopsis inconspicua (Apocynaceae–Asclepiadoideae) and Secamone cuneifolia (Apocynaceae–Secamonoideae) are described from Socotra. An account of Echidnopsis is provided for the island, where five species are now known to occur. The first species of Ceropegia is recorded for Socotra.
FLORISTIC REPORTS FROM THE ISLAND OF LESVOS (GREECE) I. DICOTYLEDONES: ACERACEAE TO GUTTIFERAE
Authors: BAZOS I. , YANNITSAROS A.
Published: January 2005

Floristic and phytogeographical information is presented in the first of three papers on the flora of Lesvos (East Aegean, Greece). The taxa included here are dicotyledons and belong to families in alphabetical order from Aceraceae to Guttiferae. Of the 92 taxa (79 species, 12 subspecies and one variety) presented, two are new for Greece, five are new for the Aegean islands as a whole, four are new for the East Aegean Islands and 13 are new for Lesvos. New distribution localities on the island are also given for some interesting taxa. Furthermore, the presence of 13 taxa, reported by previous authors without specific collection data, is confirmed. Critical comments are made on 22 taxa whose presence needs confirmation or is considered doubtful or wrong. Chorological, ecological and taxonomic comments are made for the more interesting cases and distribution maps for certain taxa in Greece or Lesvos are given. Finally, the threats and conservation status of some rare and interesting taxa are briefly discussed.
Incoherent scatter radar study of photochemistry in the E‐region
Authors: Zhou Qihou H. , Morton Yu T.
Published: January 2005

The ionospheric E‐region from 100 km to 150 km is typically regarded as being in photo‐chemical equilibrium (PCE) state during daytime. Incoherent scatter radar observations at Arecibo show that PCE is not always valid. During July 31–Aug. 5, 1992, the vertical ion drift was observed to increase by 50 m/s over a ten kilometer altitude range. The large divergence resulting from the steep velocity gradient reduced the electron concentration by 30%, invalidating the generally held PCE. Observations of non‐PCE allow us to estimate the chemical loss rate. By assuming that the loss rate does not have a day‐to‐day variability, the dissociative recombination rate derived from the incoherent scatter radar (ISR) observation is about 1.0 × 10−7 cm3s−1, which is significantly lower than the laboratory rate of NO+, or O2+. The most plausible explanation for the discrepancy is that the relative concentration of O2+ and NO+ changed significantly when non‐PCE occurred.
Dynamics of subduction and plate motion in laboratory experiments: Insights into the “plate tectonics” behavior of the Earth
Authors: Bellahsen Nicolas , Faccenna Claudio , Funiciello Francesca
Published: January 2005

Three‐dimensional laboratory experiments have been designed to investigate the way slab‐bearing plates move during subduction inside the mantle. In our experiments a viscous plate of silicone (lithosphere) subducts under its negative buoyancy in a viscous layer of pure honey (mantle). Varying thickness, width, viscosity, and density of the plate and mantle, three characteristic modes of subduction are observed: a retreating trench mode (mode I), a retreating trench mode following a transient period of advancing trench (mode II), and an advancing trench mode (mode III). These modes are characterized by different partitioning of the amount of subduction into plate and trench motion. Our experiments show that the velocity of subduction can be modeled by the dynamic interaction between acting and resisting forces, where lithospheric bending represents 75–95% of the total resisting forces. However, our experimental results also show the impossibility to predict a priori the plate velocity only from the velocity of subduction without considering trench migrations. We find experimentally that the lithospheric radius of curvature, which depends upon plate characteristics (stiffness and thickness) and the mantle thickness, exerts a primary control on the trench behavior. Our results suggest that the complexity of the style of subduction could be controlled by geometrical rules of a plate bending inside a stratified mantle. The Earth system is in the crucial range for the interplay between the rigidity of the plate and the mantle stratification: this setting may be the responsible for the complexity of the past and present tectonic styles.
Crustal structure in Ethiopia and Kenya from receiver function analysis: Implications for rift development in eastern Africa
Authors: Dugda Mulugeta T. , Nyblade Andrew A. , Julia Jordi , Langston Charles A. , Ammon Charles J. , Simiyu Silas
Published: January 2005

Crustal structure in Kenya and Ethiopia has been investigated using receiver function analysis of broadband seismic data to determine the extent to which the Cenozoic rifting and magmatism has modified the thickness and composition of the Proterozoic crust in which the East African rift system developed. Data for this study come from broadband seismic experiments conducted in Ethiopia between 2000 and 2002 and in Kenya between 2001 and 2002. Two methods have been used to analyze the receiver functions, the H‐κ method, and direct stacks of the waveforms, yielding consistent results. Crustal thickness to the east of the Kenya rift varies between 39 and 42 km, and Poisson's ratios for the crust vary between 0.24 and 0.27. To the west of the Kenya rift, Moho depths vary between 37 and 38 km, and Poisson's ratios vary between 0.24 and 0.27. These findings support previous studies showing that crust away from the Kenya rift has not been modified extensively by Cenozoic rifting and magmatism. Beneath the Ethiopian Plateau on either side of the Main Ethiopian Rift, crustal thickness ranges from 33 to 44 km, and Poisson's ratios vary from 0.23 to 0.28. Within the Main Ethiopian Rift, Moho depths vary from 27 to 38 km, and Poisson's ratios range from 0.27 to 0.35. A crustal thickness of 25 km and a Poisson's ratio of 0.36 were obtained for a single station in the Afar Depression. These results indicate that the crust beneath the Ethiopian Plateau has not been modified significantly by the Cenozoic rifting and magmatism, even though up to a few kilometers of flood basalts have been added, and that the crust beneath the rifted regions in Ethiopia has been thinned in many places and extensively modified by the addition of mafic rock. The latter finding is consistent with models for rift evolution, suggesting that magmatic segments with the Main Ethiopian Rift, characterized by dike intrusion and Quaternary volcanism, act now as the locus of extension rather than the rift border faults.
A seismic hazard scenario in the Sikkim Himalaya from seismotectonics, spectral amplification, source parameterization, and spectral attenuation laws using strong motion seismometry
Authors: Nath Sankar Kumar , Vyas Madhav , Pal Indrajit , Sengupta Probal
Published: January 2005

In this paper, we present a seismic hazard map of the Indian Himalayan State of Sikkim, lying between Nepal and Bhutan Himalaya, in terms of horizontal peak ground accelerations with 10% exceedance probability over the next 50 years. These figures, the first for the region, were calculated through a stepwise process based on (1) an estimation of the maximum credible earthquake (MCE) from the seismicity of the region and Global Seismic Hazard Assessment Program considerations and (2) four seismotectonic parameters abstracted from accelerograms recorded at nine stations of the Sikkim Strong Motion Array, specifically installed for this study. The latter include (1) the frequency‐dependent power law for the shear wave quality factor, QS, (2) the site response function at each station using receiver function analysis and generalized inversion, (3) source parameterization of various events recorded by the array and application of the resulting relationships between M0 and MW, and corner frequency, fc and MW to simulate spectral accelerations due to higher‐magnitude events corresponding to the estimated MCE, and (4) abstraction of regional as well as site specific local spectral attenuation laws at different geometrically central frequencies in low‐, moderate‐, and high‐frequency bands.
Arginine-482 is not essential for transport of antibiotics, primary bile acids and unconjugated sterols by the human breast cancer resistance protein (ABCG2)
Authors: JANVILISRI Tavan , SHAHI Sanjay , VENTER Henrietta , BALAKRISHNAN Lekshmy , van VEEN Hendrik W.
Published: January 2005

The human BCRP (breast cancer resistance protein, also known as ABCG2) is an ABC (ATP-binding cassette) transporter that extrudes various anticancer drugs from cells, causing multidrug resistance. To study the molecular determinants of drug specificity of BCRP in more detail, we have expressed wild-type BCRP (BCRP-R) and the drug-selected cancer cell line-associated R482G (Arg482→Gly) mutant BCRP (BCRP-G) in Lactococcus lactis. Drug resistance and the rate of drug efflux in BCRP-expressing cells were proportional to the expression level of the protein and affected by the R482G mutation, pointing to a direct role of BCRP in drug transport in L. lactis. In agreement with observations in mammalian cells, the BCRP-R-mediated transport of the cationic substrates rhodamine 123 and tetramethylrosamine was significantly decreased compared with the activity of BCRP-G. In addition, BCRP-R showed an enhanced interaction with the anionic anticancer drug methotrexate when compared with BCRP-G, suggesting that structure/substrate specificity relationships in BCRP, as observed in eukaryotic expression systems, are maintained in prokaryotic L. lactis. Interestingly, BCRP-R exhibited a previously unestablished ability to transport antibiotics, unconjugated sterols and primary bile acids in L. lactis, for which the R482G mutation was not critical. Since Arg482 is predicted to be present in the intracellular domain of BCRP, close to transmembrane segment 3, our results point to a role of this residue in electrostatic interactions with charged substrates including rhodamine 123 and methotrexate. Since unconjugated sterols are neutral molecules and bile acids and many antibiotics are engaged in protonation/deprotonation equilibria at physiological pH, our observations may point either to a lack of interaction between Arg482 and neutral or neutralized moieties in these substrates during transport or to the interaction of these substrates with regions in BCRP not including Arg482.
Expression, purification, characterization and structure of Pseudomonas aeruginosa arylamine N-acetyltransferase
Authors: WESTWOOD Isaac M. , HOLTON Simon J. , RODRIGUES-LIMA Fernando , DUPRET Jean-Marie , BHAKTA Sanjib , NOBLE Martin E. M. , SIM Edith
Published: January 2005

The gene for NAT (arylamine N-acetyltransferase) from Pseudomonas aeruginosa (panat) has been cloned from genomic DNA, and the gene product (PANAT) expressed as an N-terminal histidine-tagged protein in Escherichia coli and purified via nickel ion affinity chromatography. The specific activities of PANAT against a broad range of substrates have been investigated and compared with those of other prokaryotic NAT enzymes. For most arylamine substrates identified, PANAT exhibits in vitro specific activities typically one order of magnitude greater than those of recombinant NAT enzymes from Mycobacterium smegmatis or Salmonella typhimurium. Among the substrates of PANAT so far identified are the anti-tubercular drug isoniazid, 5-aminosalicylate (a drug used in the treatment of inflammatory bowel disease), as well as important environmental pollutants such as 3,4-dichloroaniline and 2-aminofluorene. As well as acetylating common NAT substrates, PANAT is unique among the prokaryotic NATs so far studied in acetylating the folate precursor 4-aminobenzoic acid and the folate catabolite 4-aminobenzoylglutamate. The recombinant protein has been expressed in sufficient quantity to allow protein crystallization, and we have subsequently determined the 1.95 Å structure of PANAT by X-ray crystallography.
Rho GTPases and leucocyte-induced endothelial remodelling
Authors: MILLÁN Jaime , RIDLEY Anne J.
Published: January 2005

Leucocytes in the bloodstream respond rapidly to inflammatory signals by crossing the blood vessel wall and entering the tissues. This process involves adhesion to, and subsequent transmigration across, the endothelium, mediated by a cascade of interactions between adhesion molecules and stimulation of intracellular signalling pathways in both leucocytes and endothelial cells. This leads to changes in endothelial cell morphology that assist leucocyte extravasation, including endothelial cell contraction, intercellular junction disruption, increased permeability, remodelling of the endothelial apical surface and alterations in vesicle trafficking. Rho GTPases play a central role in many of the endothelial responses to leucocyte interaction. In this review, we discuss recent findings on leucocyte-induced alterations to endothelial cells, and the roles of Rho GTPases in these responses.
Arachidonic acid inhibits the store-operated Ca2+ current in rat liver cells
Authors: RYCHKOV Grigori Y. , LITJENS Tom , ROBERTS Michael L. , BARRITT Greg J.
Published: January 2005

Vasopressin and other phospholipase-C-coupled hormones induce oscillations (waves) of [Ca2+]cyt (cytoplasmic Ca2+ concentration) in liver cells. Maintenance of these oscillations requires replenishment of Ca2+ in intracellular stores through Ca2+ inflow across the plasma membrane. While this may be achieved by SOCs (store-operated Ca2+ channels), some studies in other cell types indicate that it is dependent on AA (arachidonic acid)-activated Ca2+ channels. We studied the effects of AA on membrane conductance of rat liver cells using whole-cell patch clamping. We found no evidence that concentrations of AA in the physiological range could activate Ca2+-permeable channels in either H4IIE liver cells or rat hepatocytes. However, AA (1–10 μM) did inhibit (IC50=2.4±0.1 μM) Ca2+ inflow through SOCs (ISOC) initiated by intracellular application of Ins(1,4,5)P3 in H4IIE cells. Pre-incubation with AA did not inhibit ISOC development, but decreased maximal amplitude of the current. Iso-tetrandrine, widely used to inhibit receptor-activation of phospholipase A2, and therefore AA release, inhibited ISOC directly in H4IIE cells. It is concluded that (i) in rat liver cells, AA does not activate an AA-regulated Ca2+-permeable channel, but does inhibit SOCs, and (ii) iso-tetrandrine and tetrandrine are effective blockers of CRAC (Ca2+-release-activated Ca2+) channel-like SOCs. These results indicate that AA-activated Ca2+-permeable channels do not contribute to hormone-induced increases or oscillations in [Ca2+]cyt in liver cells. However, AA may be a physiological modulator of Ca2+ inflow in these cells.
Statistical Mechanics of Cross-Linked Polymer Networks I. Rubberlike Elasticity
Authors: Flory Paul J. , Rehner John
Published: January 2005

A model is proposed for the structure of a cross-linked network, such as exists in a vulcanized rubber, which is amenable to statistical treatment. Expressions are derived for the structural entropy of the network, and for the entropy change on deformation. The latter is in agreement with the relationship derived by Wall and others by a different treatment.
The Electrostatic Contribution to Hindered Rotation in Certain Ions and Dipolar Ions in Solution. I
Authors: Hill Terrell L.
Published: January 2005

From experimentally determined dissociation constants and structural parameters, effective dielectric constants are calculated for a few substances. This allows in each case an estimate of the electrostatic contribution to hindered rotation. For dithionic acid, whose dissociation constants are not known, a reasonable DE must be assumed in order to make the same calculation for the various possible ionic species. The influence of these results on ionic equilibria in dithionic acid is then discussed in some detail.
Diffraction of X-Rays by Sodium Stearate at Room Temperature
Authors: McBain James W. , de Bretteville Alexander , Ross Sydney
Published: January 2005

The alpha-form of sodium stearate, originally reported by Thiessen and Stauff, and of which a sample was made available to us, has been re-examined and the data found to be in general conformity with those of the previous investigation. Re-examination of their monoclinic betaform of sodium stearate, obtained by heating the rhombic form above 54°C, yields a different set of data. A new, more stable, monoclinic form of sodium stearate has been examined and designated as the gamma-form.
Distance Correlations and Bose-Einstein Condensation
Authors: London F.
Published: January 2005

The correlation effect on the molecular distance distribution in a Bose-Einstein gas is calculated as a function of volume and temperature, particularly for the case of degeneracy (condensation) of the gas. It is shown that, under certain conditions in the condensed state, the density as seen from any one molecule appears, over a rather extended region around it, to be considerably larger than the true density. This result seems to have direct relation to the fact that the low temperature modification of liquid helium has a negative coefficient of thermal expansion.
Infra-Red and Raman Spectra of Polyatomic Molecules XIX. Acetaldehyde and Acetaldehyde-d4
Authors: Morris J. Carrell
Published: January 2005

The infra-red spectra of acetaldehyde and acetaldehyde-d4 have been measured between 3μ and 25μ. An analysis of the spectra has been made and values are suggested for the fundamental vibration frequencies of these molecules. These values are compared with the assignment for the propylene molecule, and a strong similarity is shown. The results have been used to calculate the height of the potential barrier restricting internal rotation in acetaldehyde, and a value of about 2000 cal. is deduced.
The Infra-Red Absorption Spectrum and Configuration of Cyclohexane
Authors: Rasmussen Robert S.
Published: January 2005

The infra-red absorption spectrum from 2 to 14.5μ was determined for cyclohexane vapor. The number of bands found in the 700–1350 cm−1 region confirms the chair structure (symmetry D3d) as the most stable at room temperature. The band envelopes are discussed and compare well with the theory of Gerhard and Dennison.
The Structure of Liquid Mercury
Authors: Campbell J. A. , Hildebrand J. H.
Published: January 2005

The structure of liquid mercury has been determined by means of the diffraction of monochromatic molybdenum Kα x-radiation at −38°, 0°, 50°, 100°, 150°, and 200°C. The position of the first peak remains quite constant at 3.00A but the number of atoms in this first coordination layer varies between 6.0 and 5.3, giving the lowest coordination number yet found for any monatomic element in its normal liquid range.
The Structure of Liquid Xenon
Authors: Campbell J. A. , Hildebrand J. H.
Published: January 2005

The structure of liquid xenon has been investigated by means of the diffraction of monochromatic silver Kα x-radiation. Patterns were obtained under three sets of conditions: (1) Temperature −110°C, pressure 1 atmos., specific volume 0.324 cc/g; (2) temperature −90°C, pressure 2.5 atmos., specific volume 0.339 cc/g; (3) temperature −90°C, pressure 130 atmos., specific volume 0.324 cc/g. The number of nearest neighbors varies from 9 to 10 and their distance from the central atom from 4.43A to 4.50A. It is found that, in liquid xenon, the structure is determined mainly by the specific volume, with the temperature giving a lesser effect.
The Magnetic Susceptibilities of Metals Dissolved in Liquid Ammonia
Authors: Freed Simon , Sugarman Nathan
Published: January 2005

Here are recorded data on the magnetic susceptibilities of potassium and of cesium dissolved in liquid ammonia at 240°K and 220°K. Also included are a few data on calcium and barium. These solutions throughout the entire range of concentrations were regarded as representing an electron gas. Such systems would permit the distributions of the magnetic moments of the electrons to be followed continuously from the degenerate region of the Fermi-Dirac statistics to those distributions where the quantum and classical statistics are indistinguishable. The general features of the magnetic behavior of a free electron gas were recognized, overlaid, however, by interactions characteristic of the environment of the electrons in the solutions. In the light of the magnetic susceptibilities as well as of other properties, a description is proposed for the structure of the solutions with special reference to the conduction electrons. Barium was found to dissociate into two electrons per gram atom and it is inferred that calcium dissociated likewise, but much greater dilutions would be required for a satisfactory demonstration. A method of considerable sensitivity and accuracy has been developed for measuring the magnetic susceptibilities of substances at low temperatures.
The Photographic Latent Image I. Lattice Energy and Related Quantities for a Hypothetical Silver Bromide Crystal Having the Cubic ZnS Type of Structure
Authors: Huggins Maurice L.
Published: January 2005

The usual NaCl type of structure (B1) for silver bromide is compared with a hypothetical structure for this substance of the cubic ZnS type (B3) with regard to certain quantities which are of importance in connection with the theory of the photographic latent image. These include: lattice energy, equilibrium distance between closest atoms, density, potential at interstitial positions, potential energy changes as an ion moves from its normal position to an interstitial position, and as an ion or electron moves from one interstitial position to another. The methods of calculation are outlined and the probable accuracy of the results discussed.
X-Ray Diffraction Investigation of Sodium Stearate from Room Temperature to the Melting Point
Authors: de Bretteville A. , McBain J. W.
Published: January 2005

Sodium stearate of the gamma-polymorphic form was photographed by Cu Kα x-rays in a powder camera at seven temperatures between room temperature and 301°C. The long spacing is constant up to 132°C, the transition temperature between the subwaxy and waxy phases, whereupon it continues to decrease markedly in length up to the melting point. The two most intense short spacings increase in length up to about the transition between the stable waxy crystalline phase to superwaxy phase at 167°C. Both lines then appear to coalesce to form a single line up to above the final melting point, from liquid crystal to liquid, at 288°C. The space lattice was assumed to be monoclinic over the whole temperature range studied, with hexagonal close packing of the chains themselves above 167°C, possibly as a result of molecular rotation of the chains about their axes.
On the Statistical Mechanics of Liquids, and the Gas of Hard Elastic Spheres
Authors: Rice O. K.
Published: January 2005

Because of the extreme complications arising from a direct deductive approach, the theory of the liquid state requires the use of a model involving simplifying assumptions. In this paper an attempt is made to formulate general principles which any such model must follow. The first step is a general discussion of ``communal'' entropy, arising from the sharing of available space by all the atoms. Arguments are advanced to support the contention that for a gas of hard elastic spheres the communal entropy is fully excited in each direction of space, and amounts in all to 3R per mole. The communal entropy of assemblages of atoms exerting normal attractive and repulsive forces (in particular, the Debye solid) is considered. The geometry, the equation of state, and the partition function for an assemblage of hard elastic spheres are considered in detail. By extension of these ideas, allowing for the type of force actually exerted on each other by real atoms, a general form of partition function for a monatomic liquid is set up. This partition function involves a sum of two parts, one corresponding to a vibrational motion expressed in terms of the Debye characteristic temperature of the solid, and the other being a translational term, each part carrying with it its own communal entropy.
The Charge Effect in Photographic Development: Role of the Gelatin
Authors: James T. H.
Published: January 2005

The approach of negatively charged developer ions to the surface of a silver bromide grain is opposed by charge barriers originating both with the gelatin and with the adsorbed bromide ions. It is shown that the effect of neutral salt upon the rate of development by negative ions results primarily from a depression of the gelatin charge barrier. The effect of salt upon the bromide barrier is relatively unimportant. On the other hand, a change in the bromide barrier is mainly responsible for certain other kinetic effects, such as the induction period in development and the accelerating action of phenosafranin.
Bromination of Hydrocarbons. I. Photochemical and Thermal Bromination of Methane and Methyl Bromine. Carbon-Hydrogen Bond Strength in Methane
Authors: Kistiakowsky G. B. , Van Artsdalen E. R.
Published: January 2005

The photochemical bromination of methane was studied in the temperature range 423–503°K and found to proceed through the following chain mechanism: (1)    Br2+hν=Br+Br(2)    Br+CH4=CH3+HBr(3)   CH3+Br2=CH3Br+Br(4)  CH3+HBr=CH4+Br(5) Br+Br+M=Br2+M.Bromination of methyl bromide is analogous and from 7.5 to 10 times more rapid in this temperature range. Hydrogen bromide inhibits bromination of methane but not of methyl bromide. Thermal bromination was studied at 570°K and found to follow the same mechanism as photochemical reaction, except that bromine atoms are produced thermally. The activation energy of photochemical bromination of methane is 17.8 kcal./mole and that of methyl bromide is 15.6 kcal./mole. Varying efficiencies of different molecules as third bodies in the homogeneous recombination of bromine atoms are discussed. Configurations of activated complexes have been assigned and by statistical mechanical calculations shown to be reasonable. Activation energies and other data have been combined to arrive at a value for the C–H bond strength in methane of 102 kcal./mole at room temperature.
The Tetrahedral X2YZ2 Molecular Model Part I. Classical Vibration Problem
Authors: Shaffer W. H. , Herman R. C.
Published: January 2005

Appropriate coordinates are set up from the standpoint of group theory for describing the normal modes of oscillation in such a manner that maximum factorization of the secular determinant is accomplished. The cubic and quartic portions of the anharmonic potential function are derived. The components of vibrational angular momentum are set down. The complete valence-type potential function is discussed; explicit relations are derived between the generalized force constants occurring in the secular determinant and the valence force constants for CH2D2.
Frequency Spectrum of Crystalline Solids. III. Body-Centered Cubic Lattices
Authors: Montroll Elliott W. , Peaslee David C.
Published: January 2005

This is a study of the dynamics of a Born-Karman atomic model of a body-centered cubic lattice developed with the assumption that only interactions between nearest and next nearest atomic neighbors are significant. The equations of motion of these systems are derived and the secular equations are given from which one can calculate the frequencies of the crystal's normal modes of vibration. From the secular equations the moments of the frequency spectrum are determined and by solving the ``moment problem'' the frequency spectrum itself is obtained as a function of the force constants of the lattice. There are two maxima of approximately equal height in the frequency spectrum. Asymptotic expressions are derived for the specific heat of a body-centered cubic lattice which are valid at high and low temperatures.
Theory of Molecular Size Distribution and Gel Formation in Branched Polymers II. General Cross Linking
Authors: Stockmayer Walter H.
Published: January 2005

A statistical calculation of the gel point and of the molecular size distribution is made for cross-linked high polymers of arbitrary initial size distribution. The weight-average polymerization degree of the cross-linked polymer depends only on the weight-average polymerization degree of the initial polymer and the degree of cross linking. The results obtained also apply to certain vinyl-divinyl copolymers. Polymerization degrees can be estimated from observations of the gel point.
An Approximate Relation Between Surface Tension and Concentration for Regular Solutions
Authors: Wales M.
Published: January 2005

An equation for the variation of surface tension with concentration in regular solutions is derived using Hildebrand's model and calculating the work per unit interfacial area required to separate a body of liquid reversibly into two infinitely removed parts. Spherical symmetry in shape and molecular field of both components is assumed. Values of a factor of deviation from the geometric mean relationship for intermolecular attraction between unlike non-polar molecular species are calculated both from surface tension and vapor pressure data. Values of the factor calculated from these two independent sources for a number of systems are in reasonable agreement. The linearity of surface tension with volume fraction in ideal systems is predicted, in agreement with experiment.
Vapor Pressures, Heats of Vaporization, and Entropies of Some Alkali Halides
Authors: Zimm Bruno H. , Mayer Joseph E.
Published: January 2005

Vapor pressures of crystalline KCl, KBr, KI, and NaCl have been measured in the pressure range of 10−1 to 10−7 mm by a surface ionization method. Heats and entropies of vaporization are calculated from the data. The heats of vaporization at 0°K and entropies at 298°K are also calculated. From the data, saturated KCl vapor is shown to be less than 2 percent associated at 800°K and the heat of dissociation of (KCl)2 is shown to be less than 47 kcal.
Raman Spectra of Amino Acids and Related Compounds I. The Ionization of the Carboxyl Group
Authors: Edsall John T.
Published: January 2005

Raman spectra have been determined for four amino acids and their hydrochlorides; for three fatty acids and chloracetic acid, and their sodium salts; and for several related compounds. The influence of the solvent water on the Raman spectra of aqueous solutions is discussed. The ``carbonyl'' frequency, lying near 1670 cm—1 in the pure fatty acids, shifts to 1720 cm—1 when they are dissolved in water. No shift is found for the corresponding frequency in methyl acetate or acetone. The presence of a charged NH3+ group on the carbon α to the carboxyl increases this frequency by about 20 cm—1. On ionization of the carboxyl group it is found that: (1) The ``carbonyl'' frequency vanishes in all cases investigated. The behavior of the amino acids in this respect is entirely consistent with their structure as zwitterions. (2) A group of lines in the region 1200–1420 cm—1 undergoes characteristic changes in position and intensity. (3) In most cases there is a powerful line in the region 750–930 cm—1 whose frequency increases by 20–40 cm—1 on ionization. The frequency of this line is decreased by about 50 cm—1 for each additional methyl group on the carbon atom adjoining the carboxyl. (4) Ionization markedly decreases the C–H frequency in formic acid, and also certain strong frequencies in methyl and ethyl amine.
Predissociation of the Oxygen Molecule
Authors: Flory Paul J.
Published: January 2005

In the emission spectrum of the oxygen molecule no bands in the Runge system, 3Σu—→3Σg—, having ν′>2 have ever been observed. The absence of these emission bands as well as evidence of broadened rotation lines in the ν′>2 absorption bands suggests that in the 3Σu— state vibration levels above the second undergo predissociation. Rassetti's observations of the fluorescence spectrum of oxygen as well as recent photochemical results support this conclusion. Although it cannot be said that any one of these lines of evidence provides rigorous proof that the oxygen molecule predissociates, collectively they present a convincing argument for the occurrence of predissociation. Radiationless transition from the 3Σu— state is doubtless to the 3IIu state formed from normal atoms. On the basis of the present interpretation the initial process in the photochemical reactions of oxygen caused by light in the region of Schumann-Runge band absorption is the formation of normal 3P atoms as a result of the predissociation, rather than the reaction of an optically excited molecule with a normal molecule as heretofore has been supposed.
The Crystal Structure of Polonium by Electron Diffraction
Authors: Rollier M. A. , Hendricks S. B. , Maxwell Louis R.
Published: January 2005

Electron diffraction photographs (λ=0.062A) were obtained from about 10—7 g of polonium that had been volatilized in a stream of hydrogen and condensed over an area of about 3 mm2 on a thin collodion film. Diffraction patterns were also obtained from bismuth and tellurium since it was expected that polonium would have a similar crystal structure. Analysis of these patterns shows that the structure of polonium closely resembles that of tellurium, the lattice being pseudohexagonal with a=4.25A, c=7.06A, or 14.12A, and the calculated density 9.39 assuming 3 Po in the pseudo unit of structure. The true lattice is probably monoclinic with a=7.42A, b=4.29A, c=14.10A and β quite close to 90°, a suggested value being β=92°; the calculated density for 12 Po in the unit of structure is 9.24. A structure, based upon the space group C23–C2, in which each polonium atom has four nearest neighbors gives moderate agreement between observed and calculated intensities of reflection.
The Photovoltaic Effect for Sodium
Authors: Gibney Robert B. , Dole Malcolm
Published: January 2005

Attempts to produce a photovoltaic effect with reversible electrodes made of an active metal photoelectrically sensitive to visible light, such as sodium, and dipping into a solution containing ions of the metal, met with no success provided the solvent and salt which formed the electrolyte were carefully dried before preparing the cells. Slight photovoltaic effects of the order of 0.5 mv or smaller were observed in the case of two cells known to contain traces of water, but these effects were probably due either to the water present or to the compound electrode Na/Na2O rather than to the pure metal. It is concluded that the energy supplied to the electrons by the visible light is not sufficient to bring about the transition of the electron from the metal to the solution.
The Free Energy of Electron Gas
Authors: Gordon A. R.
Published: January 2005

The energy and free energy of a semi-degenerate gas obeying the Fermi statistics are computed as functions of temperature and concentration. The significance of the deviation of the free energy from the limiting high temperature value is illustrated by calculating the degree of thermal ionization of potassium vapor under conditions of high electron concentration.
The Relative Atomic Weight of Oxygen in Water and in Air II. A Note on the Relative Atomic Weight of Oxygen in Fresh Water, Salt Water and Atmospheric Water Vapor
Authors: Dole Malcolm
Published: January 2005

Purified Lake Michigan water appears to be nearly exactly intermediate in density between purified Atlantic Ocean water and water condensed from the atmosphere. Within the experimental error the entire difference in density between fresh and salt water appears to be due to differences in the oxygen isotopic ratios. The bearing of these results on theories explaining the relatively large concentration of O18 in the atmosphere is discussed.
Kinetics of OH Radicals as Determined by Their Absorption Spectrum II. The Electric Discharge Through H2O2
Authors: Frost A. A. , Oldenberg O.
Published: January 2005

In order to study the kinetics of OH radicals in H2O2 the concentration of OH as a function of time is measured by the decay of the intensity of the OH absorption bands after interrupting an electric discharge through H2O2. For each snapshot a new supply of H2O2 is introduced into the absorption tube and partly decomposed into OH+OH by an electric discharge of brief duration. OH radicals disappear in H2O2 much more rapidly than in H2O. This indicates a bimolecular reaction OH+H2O2. The emission spectrum of OH shows abnormal rotation of OH even more strongly when excited in H2O2 than in H2O, the rotation being determined not by the temperature but by the simultaneous dissociation and excitation producing the OH radicals observed.
Solvent Action on Optical Rotatory Power
Authors: Beckmann Charles O. , Cohen Karl
Published: January 2005

A general theory of the optical rotatory power of liquids is developed. The method of C. G. Darwin, supplemented so that the fundamental quantities Sαβγ...† which appear there are related to the properties of the molecules comprising the medium, is followed. The optical properties of a molecule are given by a set of tensors σ′ αβγ.... The concept of deformation leads naturally to a simple relation between the σ′ αβγ...'s and the field acting on the molecule. The electrostatic field of the dipoles of the surrounding molecules is computed for the limiting cases of imperfect gases and dilute solutions, for molecules of simple geometrical configuration. This field is identified with the solvent field. For these idealized systems, the rotatory power of a molecule in various solvents is determined in terms of quantities characteristic of the solvents. The resulting equations are controlled by comparing with the behavior of actual liquids.
A Study of the Evaporation of Small Drops and of the Relationship Between Surface Tension and Curvature
Authors: Shereshefsky J. L. , Steckler Sylvia
Published: January 2005

The rates of evaporation of n-dibutyl phthalate droplets ranging from 3μ to 0.5μ in radius were measured in a Hoag type of Millikan's oil-drop apparatus under different conditions of vapor pressures. The data obtained are interpreted in two ways. One interpretation is based on an equation derived from Fourier's equation of diffusion; the results thus obtained show that the surface tensions of the droplets decrease with increasing curvature. The other is based on an equation derived on the basis of an assumption of a vapor film surrounding the evaporating droplet; the results obtained here lead to the validation of Lord Kelvin's equation. An explanation is also given for the abnormally high values of surface tension obtained by Woodland and Mack.
Effects of Isomerism on Infrared Absorption Spectra
Authors: Gordy Walter , Williams Dudley
Published: January 2005

The absorption spectra of four organic cyanides, two organic thiocyanates, and the corresponding isomers have been studied in the region from 1.0μ to 6.5μ. The intense band appearing near 4.4μ in the normal cyanides appears at a longer wave-length and with doubled intensity in the isocyanides, the variation in wave-length and intensity being nearly constant for all compounds. In the case of the thiocyanates the variation in wave-length of the 4.6μ band for the two configurations is less than in the cyanides, whereas the intensity differences are greater. No other bands in these organic compounds were appreciably affected by isomerism. In the absorption spectrum of aqueous solutions of hydrocyanic gas there appears an intense band at 4.75μ and also a less intense band at 4.95μ. The band at 4.95μ can be attributed to a small amount of the isomer HNC.
The Near Infrared Absorption Spectra of Acid and Basic Solutions
Authors: Barr E. S. , Plyler E. K.
Published: January 2005

The infrared absorption spectra of H2O and aqueous solutions of HCl, HBr, NaOH, KOH, ZnBr2, ZnCl2 and Na2CO3 have been measured from 1.5μ to 2.8μ. Bands were observed at 2.30μ and 2.45μ in hydroxides, at 2.30μ and 2.55μ in acids, and at 2.30μ, 2.45μ in hydrolyzing salts. The band at 2.30μ is produced by hydration and 2.45μ band by the OH ion.
The Homogeneous Unimolecular Decomposition of Gaseous Alkyl Nitrites V. The Decomposition of Methyl Nitrite at Low Pressures
Authors: Steacie E. W. R. , Calder D. S.
Published: January 2005

The decomposition of methyl nitrite has been investigated from 0.005 to 5.0 cm in the temperature range 210–240°C. In this region the rate falls off steadily with diminishing pressure. The reaction is appreciably heterogeneous at the lower pressures. The results are in satisfactory agreement with the previous observations of Steacie and Shaw at higher pressures. The fallingoff in rate with decreasing pressure is satisfactorily accounted for by the Rice-Ramsperger theory, assuming 13 degrees of freedom and a molecular diameter of 5.0×10—8 cm.
The Rate of Reaction of Deuterium with Hydrogen Chloride
Authors: Gross Ph. , Steiner H.
Published: January 2005

The reaction D2+HCl=HD+DCl has been investigated at temperatures from 765°K to 843°K. The reaction is almost entirely homogeneous, and, up to temperatures of the order of 830°K, bimolecular. The fraction which proceeds heterogeneously is determined in a vessel packed with tubes. The constant of the homogeneous bimolecular reaction can be represented by the following equation: Ko=6.27×1013×T12×e−26.200/T mole−1 cm3 sec.−1.At the maximum measured temperature of 843°K deviations were noticed which may have been due to atomic reaction.
Reactions Involving Hydrogen Molecules and Atoms
Authors: Hirschfelder J. , Eyring H. , Topley B.
Published: January 2005

The criticisms of Coolidge and James of activation energy calculations are discussed. It is pointed out that their criticisms of the original London proposal do not apply to the semi-empirical method which in its present form has little more than a formal resemblance to the original scheme. Until a satisfactory quantum-mechanical derivation of the semi-empirical method is provided, it must depend for acceptance on its usefulness and the fact that it is a reasonable interpolation formula for calculating the energies of polyatomic molecules from diatomic ones. The best surface for three hydrogen atoms is constructed and from it the rates of all the possible hydrogen-deuterium reactions are calculated by means of the general theory of absolute rates, these rates are found to be in excellent agreement with the experimental values. The transmission coefficient for reactions on this surface is investigated. Diagrams showing the angular dependence of the potential energy for an H and for a Cl atom approaching a hydrogen molecule are given.