bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single crystal vibrational spectra of some aqua complexes
Authors: James David W. , Whitnall Janette M. 
Published: May 2005

AbstractThe single crystal Raman spectra and powder infrared spectra have been determined for the isomorphous Tuttons salts K2Cu(H2O)6(SO4)2, K2Cu(H2O)6(SeO4)2, K2Zn(H2O)6(SO4)2 and K2Zn(H2O)6(SeO4)2. The symmetry distortion of the XO ions caused by unsymmetric hydrogen bonding produces both site and factor group splitting. All vibrations of the bound water are observed except those related to the water bending mode at 1600 cm−1. The libration modes show dependence on the MO bond distances and also the hydrogen bonding to the XO species.
Raman spectroscopic study of amorphous Te40As35Ge7Si18
Authors: Joshi N. V. 
Published: May 2005

AbstractThe Raman spectrum of the amorphous material Te40As35Si18Ge7 has been studied for the first time. It has been observed that the vibrational modes corresponding to the elemental amorphous material are present together with the modes belonging to the SiGe alloy system. The results suggest that this amorphous material demonstrates similarities to organic molecules where the presence and ordering of the neighbouring atoms have little effect on the eigenvalue of the vibrational mode of a particular group.
Raman tensor tables. MX3 molecules
Authors: Bote M. A. López , Montero S. 
Published: May 2005

AbstractFormulae for the absolute differential Raman scattering cross‐sections of fundamental modes of gases, liquids and solids as a function of the invariants of the Raman tensors are reviewed. Explicit expresslons for the Raman tensors of planar and pyramidal MX3 molecules are reported in terms of bond polarizability parameters. For the pyramidal MX3 Molecules the coefficients of these expressions cannot be summarized easily in simple formulae since they depend on the atomic masses and on the tribedral angle of the pyramid, but numerical values are tabulated for 27 molecules and ions. Several approximations of the bond polarizability model are briefly reviewed in connection with the expressions for the Raman tensors.
Laser Raman spectra of calf thymus histone complexes
Authors: Jutier Jean‐Jacques , Savoie Rodrigue , Pigeon‐Gosselin Marie , Nadeau Paul , Lewis Peter N. 
Published: May 2005

AbstractThe Raman spectra of aqueous solutions of calf thymus histone complexes H2A:H2B and H3:H4 have been recorded and are compared with those of the individual histones. The results show an increase of α‐helix content on formation of these complexes, at the expense of random‐coil conformation in H2A:H2B and β‐sheet structure in H3:H4. The α‐helix content is estimated to be 40% in H2A:H2B and 35% in the H3:H4 complex. The intensity ratios of the 850/830 cm−1 components of the tyrosine doublet in the spectra of both complexes are the averages of the values for the individual histones, suggesting that the environment of these residues is little modified on formation of the complexes. Variations in the intensity of the 1400 cm−1 carboxyl band has been observed to be associated with conformational changes, which is consistent with the notion that COO−/NH, NH interactions play a major role in histone‐histone complexation.
Lattice vibrations of crystalline titanium and tin tetrachlorides
Authors: Tse W. S. , Liang N. T. , Chen C. C. , Chang H. 
Published: May 2005

AbstractThe vibrational spectra of polycrystalline samples of titanium and tin tetrachlorides at 80 K have been investigated by Raman spectroscopic techniques. In the intramolecular region, isotopic and crystalline field splittings are observed, in substantial agreement with earlier work. In the lattice region, ten of the twelve Raman‐active lattice modes are observed. A simple model is suggested and used to distinguish the low‐frequency lattice translational from librational modes.
Vibrational Spectra of Pentachlorocyclopropane
Authors: Yeh Y. Y. , Wurrey C. J. 
Published: May 2005

AbstractInfrared spectra (4000–400 cm−1) of pentachlorocyclopropane have been recorded for all three of its physical states. A liquid‐phase Raman spectrum of this molecule has also been observed. Based on the Raman depolarization data, gas‐phase infrared band contours and expected group frequency correlations, it has been possible to propose an assignment for 20 of the 21 normal vibrations of pentachlorocyclopropane. This assignment agrees well with those proposed for hexachlorocyclopropane, the three isomeric tetrachlorocyclopropanes, 1,1‐dichlorocyclopropane and chlorocyclopropane. Further, the vibrational assignment for pentachlorocyclopropane has identified characteristic vibrational frequencies for the three CH(X) modes: CH stretch, 3040 cm−1; in‐plane CH bend, 1296 cm−1; and out‐of‐plane CH bend, 1088 cm−1.
Raman scattering and vibrational relaxation studies of N, N‐dimethylformamide
Authors: Purkayastha Anusree , Kumar Kamal 
Published: May 2005

AbstractThe Raman band of the amide I vibrational mode of N, N‐dimethylformamide was studied in the neat liquid and as a function of solvent concentration. The non‐coincidence effect (anisotropy shift) is explained in terms of transition dipole‐transition dipole interactions. The vibrational relaxation rate has been shown to be linearly dependent on the product of the density, viscosity and a dispersion energy‐dependent term, for which a theoretical basis is outlined.
Raman spectra of Pm2O3, PmF3, PmCl3, PmBr3 and PmI3
Authors: Wilmarth W. R. , Begun G. M. , Haire R. G. , Peterson J. R. 
Published: May 2005

AbstractRaman spectral data are presented for the sesquioxide and the trihalides (F, Cl, Br and I) of promethium. The Raman spectra of these lanthanide compounds are reported for the first time and are compared with those of the homologous lanthanide compounds. Tentative symmetry assignments have been made for the observed Raman‐active bands based on factor group analysis of their respective crystal structures and comparisons with the assigned Raman spectra of other lanthanide compounds. The characteristic band patterns of the Raman phonon spectra have been found to be very useful in determining the crystal structure of the respective promethium compounds.
Formation of p, p′‐azodibenzoate from p‐aminobenzoic acid on silver island films during surface‐enhanced Raman scattering
Authors: Venkatachalam R. S. , Boerio F. J. , Roth P. G. 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) from p‐aminobenzoic acid (PABA) adsorbed on silver island films was investigated. PABA reacted very quickly to form p,p′‐azodibenzoate when exposed to atmospheric moisture and laser light. This was evidenced by the appearance of a strong band near 1460 cm−1 and a strong doublet near 1150 cm−1 that were characteristic of the azodibenzoate. Exposure to a drier environment such as in a desiccator or a vacuum inhibited the reaction. It was concluded that the reaction of PABA to form the azodibenzoate involved two steps, the first being the hydrolysis of the amine and the second dimerization during exposure to laser light.
Frequency dependence of the memory and force autocorrelation functions and its use in separating homogeneous and inhomogeneous broadening. Application to methyl iodide
Authors: Wilde Richard E. , Yarwood J. 
Published: May 2005

AbstractSpontaneous Raman spectra of the n̈3 band of methyl iodide were recorded at 1 bar and 2 kbar at ambient temperature. These spectra yielded vibrational, memory and frequency autocorrelation functions. The frequency dependence of the memory function was shown to be identical with that of the force autocorrelation function. An autoregressive analysis of the memory function allowed the separation of the homogeneous and inhomogeneous second moments. This separation of second moments was compared with a theoretical separation of the homogeneous and inhomogeneous bandwidths.
Raman spectra of SiO2 gel glasses prepared from alkoxide, colloidal and amine silicate solutions
Authors: Bertoluzza A. , Fagnano C. , Morelli M. A. , Guglielmi M. , Scarinci G. , Maliavski N. 
Published: May 2005

AbstractThe Raman spectra of gels obtained from alkoxide, colloidal and amine silicate solutions are reported. The spectra are discussed in order to determine whether it is possible to introduce into the gel structures modifications that persist after thermal treatment.
Application of Raman spectroscopy to industrial membranes. Part 2–Perfluorosulphonic membrane
Authors: Bribes J.‐L. , El Boukari M. , Maillols J. 
Published: May 2005

AbstractThe Raman spectrum of a Nafion 117 membrane immersed in aqueous solution was recorded. Assignments are proposed for the fundamental vibrations observed for this material. The interaction of counter ions (cations) and also of sorbed electrolytes with the antagonist group SO3− of the membrane were studied. For this purpose, intensity measurements were made of selected appropriate signals versus the nature and type of counter ions (monovalent, divalent). The intensity of the symmetric stretching vibration band of the SO3− group can be used to monitor the variation of the conductivity of the membrane studied.
Infrared and Raman spectra of NH4Pr(SO4)2 and NH4La(SO4)2
Authors: Pradeep T. , Suresh G. , Pillai V. P. Mahadevan , Nayar V. U. 
Published: May 2005

AbstractRaman and IR spectra of NH4Ln(SO4)2 (Ln = Pr, La) were recorded and analysed. The observed bands indicate a centrosymmetric structure for the crystals. Two crystallographically independent SO2−4 groups exist in both compounds. The NH4+ groups form strong hydrogen bonds.
Conformational study of monothioformic acid, HC(O)SH
Authors: Védova C. O. Della 
Published: May 2005

AbstractInformation obtained from the Raman and infrared spectra of monothioformic acid, HC(O)SH, leads unambiguously to the existence of the molecule in two stable planar conformations, with the trans structure the most stable in the vapour phase. A concentration ratio of ca. 1:1 is found in the liquid. These differences between the concentration ratios in the two phases are interpreted in terms of different interaction forces operating in each phase. The interpretation of these results suggests that the carbonylsulphenyl compounds show mainly a syn conformation in the vapour phase.
Resonance Raman spectra of MnO3F and MnO3Cl
Authors: Varetti Eduardo L. 
Published: May 2005

AbstractThe resonance Raman spectra of MnO3F and MnO3Cl condensed at low temperature were obtained using a laser scanning technique to avoid sample decomposition. Harmonic wavenumbers and anharmonicity constants for the symmetric Mn–O stretching mode were determined.
Observation of morphology‐dependent input and output resonances in time‐dependent Raman spectra of optically levitated microdroplets
Authors: Schaschek K. , Popp J. , Kiefer W. 
Published: May 2005

AbstractUsing a highly efficient Raman set‐up, which allows a Raman spectrum to be recorded in less than 1 s, morphology‐dependent resonances in optically levitated microdroplets of water–glycerol mixtures were studied. In addition to the output resonances, where the Raman frequency coincides with an electromagnetic sphere resonance, input resonances could also be demonstrated. The latter are observed when the evaporating droplet reaches a radius which, together with the wavelength of the incident laser lgith, fulfils the resonance condition for the cavity modes of a sphere. Preliminary results for droplet size change during evaporation of a particular droplet in the micrometre range are presented.
Vibrational Raman optical activity of simple amino acids
Authors: Gargaro A. R. , Barron L. D. , Hecht L. 
Published: May 2005

AbstractThe vibrational Raman optical activity (ROA) spectra of the simple amino acids L‐serine, L‐cysteine, L‐valine, L‐threonine and L‐isoleucine in aqueous solution between 600 and 1600 cm−1 measured in backscattering are presented and discussed. Complete vibrational assignments are suggested for serine and cysteine and limited assignments for the others. Bands originating in Cα*H deformations and the symmetric CO2− stretch appear to provide the best signatures for stereochemical studies. The results show that ROA provides a new perspective on amino acid conformation in aqueous solution.
Application of chemometric methods in Raman spectroscopic studies of molten salt system containing MgCl2‐KCl: Experimental evidence for existence of Mg2Cl dimer and its Raman spectrum
Authors: Dai Sheng , Begun G. M. , Young J. P. , Mamantov G. 
Published: May 2005

AbstractInvestigation of the Raman spectra of the molten MgCl2‐KCl system by the use of factor analysis indicates that the melt is a two‐component system involving equilibrium between MgCl and Mg2Cl. The pure Raman spectra corresponding to these two species are recovered from the broad features via a self‐modeling method.
Raman and infrared spectra, vibrational assignment and ab initio calculations of trans‐2‐methyl‐2‐butenenitrile
Authors: Durig J. R. , Drew A. S. , Guirgis Gamil A. 
Published: May 2005

AbstractThe Raman (3100‐10 cm−1) and infrared (3100‐400 cm−1) spectra of trans‐2‐methyl‐2‐butenenitrile [trans‐CH3CH =C(CH3)CN] were recorded for the gas, liquid and solid phases. Additionally, the far‐infrared (370‐60 cm−1) spectrum of the gas was recorded. These data were interpreted on the basis that only the trans (two methyl groups trans to each other) isomer is present on purification. Only one of the methyl torsional fundamentals was observed and it corresponds to the methyl group on the same carbon atom as the cyano group. The experimental barrier to internal rotation is 610 ± 30 cm−1 (1.74 ± 0.09 kcal mol−1). The structure, infrared intensities, Raman activities, depolarization ratios and vibrational wavenumbers were determined from ab initio calculations using the RHF/3‐21G, RHF/6‐31G* and MP2/6‐31G* basis sets. These results are compared with those obtained for some related molecules.
Raman and infrared spectra, barriers to internal rotation, vibrational assignment and ab initio calculations of 1‐bromo‐2‐methylpropene
Authors: Durig J. R. , Eltayeb Saadia , Guirgis Gamil A. 
Published: May 2005

AbstractThe Raman spectra (3200‐20 cm−1) of the liquid and solid phases of 1‐bromo‐2‐methylpropene [BrHC=C(CH3)2] and the infrared (3200‐30 cm−1) spectra of the gas and solid were recorded. Additionally, qualitative depolarization values were obtained from the Raman spectrum of the liquid. All of the normal modes were assigned based on band contours, depolarization values, relative intensities and normal coordinate analysis. The torsional transition for the methyl group trans to the bromine atom was observed in the far‐infrared spectrum of the vapor at 167 cm−1, and from this wavenumber the barrier to internal rotation was calculated to be 641 cm−1 (1.83 kcal mol−1). Optimized structural parameters, barriers to internal rotation and the wavenumbers for the vibrational fundamentals were calculated using the RHF/STO‐3G*, RHF/LANL‐1DZ and/or MP2/LANL‐1DZ basis sets. All of the results are discussed and compared with the corresponding values obtained for some similar molecules.
High‐pressure Raman study of dense methane: CH4 and CD4
Authors: Wu Y. H. , Sasaki S. , Shimizu H. 
Published: May 2005

AbstractHigh‐pressure Raman spectra of liquid and solid CH4 and CD4 were measured up to 18 and 13 GPa, respectively, at 300 K in a gasketed diamond‐anvil cell. On the basis of visual observations under the polarizing microscope and changes in the Raman spectra, it was confirmed that there are only two solid phases (I and VII) for CH4 and CD4 at 300 K up to 18 GPa; no solid‐solid phase transition was found around 12 GPa, in contrast to earlier claims. In phase VII, some molecules are orientationally ordered, whereas others are orientationally disordered, just like the low‐temperature solid phases II, III, IV and V.
Thermodynamics, the structure of integral membrane proteins, and transport
Authors: Singer S. J. 
Published: May 2005

AbstractMembranes are structures whose lipid and protein components are at, or close to, equilibrium in the plane of the membrane, but are not at equilibrium across the membrane. The thermodynamic tendency of ionic and highly polar molecules to be in contact with water rather than with nonpolar media (hydrophilic interactions) is important in determining these equilibrium and nonequilibrium states. In this paper, we speculate about the structures and orientations of integral proteins in a membrane, and about how the equilibrium and nonequilibrium features of such structures and orientations might be influenced by the special mechanisms of biosynthesis, processing, and membrane insertion of these proteins. The relevance of these speculations to the mechanisms of the translocation event in membrane transport is discussed, and specific protein models of transport that have been proposed are analyzed.
Isolation of membrane vesicles with inverted topology by osmotic lysis of azotobacter vinelandii spheroplasts
Authors: Barnes Eugene M. , Bhattacharyya Pinakilal 
Published: May 2005

AbstractMembrane vesicles were prepared from Azotobacter vinelandii spheroplasts by lysis in either potassium phosphate (pH 7.0) or Tris1‐acetate (pH 7.8) buffers. These 2 types of preparations differ considerably in their properties: (1) Examination by scanning electron microscopy reveals that the Pi vesicles consist primarily of closed structures 0.6–0.8 μm in diameter with a rough or particulate surface similar to that of spheroplasts. The Tris vesicles are significantly smaller, 0.1–0.3 μm in diameter, and have a much smoother surface structure. (2) Antisera from rabbits immunized with A. vinelandii lipopolysaccharide antigen will agglutinate Pi vesicles but not Tris vesicles. (3) Tris vesicles have a fourfold higher specific activity of latent H+‐ATPase than Pi vesicles. After exposure to Triton X‐100 similar ATPase activities are observed for both types of vesicles. (4) Pi vesicles transport calcium in the presence of ATP or lactate at less than 30% of the rates observed for Tris vesicles. (5) Tris vesicles have less than 22% of the transport capacity of Pi vesicles for accumulation of labeled sucrose and less than 3% of the capacity for valinomycin‐induced uptake of rubidium observed during respiration. (6) Quinacrine fluorescence intensity is reduced by 30% during lactate oxidation and 20% during ATP hydrolysis by Tris vesicles. Under similar conditions, fluorescence in Pi vesicles is quenched by only 7% and less than 2%, respectively. These findings suggest that Pi vesicles have the normal orientation of the intact cell whereas Tris vesicles have an inverted topology.
Control of amino acid transport in the mammary gland of the pregnant mouse
Authors: Lobitz Cinda J. , Neville Margaret C. 
Published: May 2005

AbstractThe regulation of the uptake of the amino acid analog α‐aminoisobutyric acid was studied in diced mammary glands from pregnant mice. Stimulation of uptake by insulin was not prevented by inhibitors of protein synthesis; protein synthesis inhibitors decreased uptake by 20%; this response occurred more promptly in insulintreated tissues. Elimination of extracellular amino acids led to a substantial increase in transport which was not abolished by inhibitors of protein synthesis. These results indicate that insulin does not increase amino acid transport in this system by altering synthesis and degradation of transport protein. They are consistent with a model in which the activity of the existing amino acid transport protein is subject to negative feedback regulation from the intracellular amino acid pool.
Leucine binding protein and regulation of transport in E. coli
Authors: Oxender Dale L. , Anderson James J. , Mayo Mary M. , Quay Steven C. 
Published: May 2005

AbstractLeucine is transported into E. coli cells by high‐affinity transport systems (LIV‐I and leucine‐specific systems) which are sensitive to osmotic shock and require periplasmic binding proteins. In addition leucine is transported by a low‐affinity system (LIV‐II) which is membrane bound and retained in membrane vesicle preparations. The LIV‐I system serves for threonine and alanine in addition to the 3 branched‐chain amino acids. The LIV‐II system is more specific for leucine, isoleucine, and valine while the high‐affinity leucine‐specific system has the greatest specificity.A regulatory locus, livR at minute 22 on the E. coli chromosome produces negatively regulated leucine transport and synthesis of the binding proteins. Valine‐resistant strains have been selected to screen for transport mutants. High‐affinity leucine transport mutants that have been identified include a LIV‐binding protein mutant, livJ, a leucine‐specific binding protein mutant livK and a nonbinding protein component of the LIV‐I system, livH. A fourth mutant, livP, appears to be required only for the low‐affinity LIV‐II system. The existence of this latter mutant indicates that LIV‐I and LIV‐II are parallel transport systems. The 4 mutations concerned with high‐affinity leucine transport form a closely linked cluster of genes on the E. coli chromosome at minute 74.The results of recent studies on the regulation of the high‐affinity transport systems suggests that an attenuator site may be operative in its regulation. This complex regulation appears to require a modified leucyl‐tRNA along with the transcription termination factor rho. Regulation of leucine transport is also defective in relaxed strains.Among the branched‐chain amino acids only leucine produces regulatory changes in LIV‐I activity suggesting a special role of this amino acid in the physiology of E. coli. It was shown that the rapid exchange of external leucine for intracellular isoleucine via the LIV‐I system could create an isolucine pseudoauxotrophy and account for the leucine sensitivity of E. coli.
Relationship between thymidine transport and phosphorylation in Novikoff rat hepatoma cells as analyzed by a rapid sampling technique
Authors: Marz Richard , Wohlhueter Robert M. , Plagemann Peter G. W. 
Published: May 2005

AbstractIncorporation of thymidine into Novikoff rat hepatoma cells was analyzed with a rapid sampling technique which allowed collection of 12 time points in 20 sec. Transport was studied in the absence of metabolism by using either ATP‐depleted cells or a thymidine kinase negative subline. Transport was a rapid, saturable, nonconcentrative process with a Km of about 85 μM. The intracellular thymidine pool was also rapidly labeled in cells which phosphorylated thymidine, so that a group translocation process involving thymidine kinase can be ruled out. Under all conditions examined, phosphorylation, not the transport, of thymidine was the rate‐determining step in its incorporation into the acid‐soluble pool. Estimation of transport rates from total incorporation into cells which phosphorylate the substrate is invalid in this cell system and must be questioned in all instances.
Cholesterol levels and plasma membrane fluidity in 3T3 and SV101‐3T3 cells
Authors: Scandella Carl J. , Hayward James A. , Lee Nancy 
Published: May 2005

AbstractPolyene antibiotics such as filipin selectively inhibit wheat germ agglutinin‐induced agglutination of transformed and malignant cells compared to normal cells (Hatten ME, Burger MM: Biochemistry 18:739, 1979). Since filipin binds specifically to cholesterol, we measured cholesterol levels in 3T3 cells and SV101‐3T3 cells. SV101‐3T3 cells contained 50‐100% more cholesterol per cell than 3T3 cells. Both cell types were starved for cholesterol by growth in lipid‐depleted medium plus 25‐hydroxycholesterol. The cholesterol level of SV101‐3T3 cells decreased by 30‐50%, while the level in 3T3 cells remained constant. Filipin‐stained SV101–3T3 cells revealed bright patches of filipin under fluorescence microscopy. These patches were absent in 3T3 cells and in SV101–3T3 and 3T3 cells starved for cholesterol. We selectively labeled plasma membranes of these cells with a spin label analog of phosphatidylcholine. The spin label indicated differences in plasma membrane fluidity that may be related to the different cholesterol levels in 3T3 and SV101–3T3 cells.