bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman study of a phase transition in solid trifluoroiodomethane
Authors: Beardsall A. J. , Schlueter S. A. , Anderson A.
Published: May 2005

Raman spectra of solid trifluoroiodomethane are reported for both the lattice and internal mode regions for samples at temperatures between 12 and 130 K. A solid‐state phase transition at about 115 K is confirmed. Above this temperature, the spectra are characteristic of a disordered or highly anharmonic solid. At low temperatures, the spectra are compatible with an ordered, harmonic molecular crystal with a unit cell containing at least four molecules. Plausible assignments of all observed spectroscopic features are proposed.
Vibrational spectroscopic study of zinc tris(thiourea) sulphate, a new organometallic non‐linear optical crystal
Authors: Venkataramanan V. , Srinivasan M. R. , Bhat H. L.
Published: May 2005

Vibrational spectra of zinc tris(thiourea) sulphate (ZTS), a new semiorganic non‐linear optical crystal, were recorded to determine the symmetries of molecular vibrations. The observed Raman and infrared bands are assigned to molecular vibrations of thiourea, sulphate groups and Zn(thiourea)3SO4 tetrahedra. The Raman spectra are interpreted in the light of crystal structure data. Modifications in the IR spectra of thiourea due to metal complexations are discussed.
Vibrational spectra of [15N]glutamic acid and [2H4]glutamic acid
Authors: Navarrete J. T. López , Hernández V. , Ramírez F. J.
Published: May 2005

The infrared and Raman spectra of L‐glutamic acid, [2H4]‐L‐glutamic acid and [15N]‐L‐glutamic acid as solid samples were measured. The data obtained were used to propose a general assignment of the fundamental vibrational modes on the basis of the measured isotopic shifts and correlations with previous data reported for aspartic acid and other amino acids and related molecules.
Resonance Raman spectra of the O2 adducts of cobalt ‘picket‐fence’ porphyrin complexes of 3, 5‐dichloropyridine
Authors: Proniewicz Leonard M. , Golus Janusz , Nakamoto Kazuo , Kincaid James R.
Published: May 2005

Resonance Raman spectra are reported for the 16O2 and 18O2 adducts of cobalt porphyrin complexes with 3,5‐dichloropyridine (DCP) for three different ‘picket‐fence’ porphyrins. It is shown that the v(O—O) effectively couples with an internal mode of DCP giving rise to complicated spectral patterns. These spectral patterns were carefully analyzed to reveal the inherent wavenumbers of v(O—O) which are shown to vary as expected, given the known relative hydrogen bonding capabilities of the three different superstructured porphyrins.
Raman spectroscopic study of fourteen positional isomers of carboxylic acid esters with seventeen skeletal atoms
Authors: Mido Yoshiyuki , Kimura Tatsuo , Ishida Yoshiko , Matsuura Hiroatsu
Published: May 2005

The Raman spectra of 14 positional isomers of carboxylic acids esters with 17 skeletal atoms, CH3(CH2)m−1COO(CH2)n−1CH3(CmCOOCn) with m + n = 15 and m = 1—14, have been measured in the crystalline state at liquid nitrogen temperature. The relationship between the observed wavenumbers of the characteristic bands and the positions of the —C(=O)—O— group in the molecular chain was examined. All of the positional isomers of CmCOOCn with m + n = 15 exhibit a strong LAM‐1 band in the region between 147 and 136 cm−1. The LAM‐1 wavenumbers for the isomers which have the —C(=O)—O— group almost in the middle of the molecular chain are slightly higher (147—143 cm−1) than those for the isomers which have the same group almost at the end of the chain. In order to elucidate the observed LAM‐1 wavenumbers, the Raman spectra of two homologous series of esters, C5COOCn and C6COOCn, were examined. All isomers of CmCOOCn give a strong band at about 1135 cm−1 assignable to the k = 1 mode of the C—C stretching vibrations. Some of the isomers give an additional k = 1 band at about 1125 cm−1. The isomers of CmCOOCn, which exhibit the two k = 1 bands, have the —C(=O)—O— group almost in the middle of the molecular chain, and appear to give the LAM‐1 band at the higher wavenumbers. In the crystalline state all of the esters examined take the all‐trans conformation with the —C(=O)—O— group part incorporated.
Raman spectra of n‐butanoate ion (d0, 2‐d2, 3‐d2 and 4‐d3) in aqueous solution. Assignment to the conformers
Authors: Raada N. , Gaufrès R. , Bribes J.‐L. , Maillols J. , Montginoul C.
Published: May 2005

A vibrational study of the n‐butanoate ion in aqueous solution was undertaken. Four isotopic species (d0, 2‐d2, 3‐d2 and 4‐d3) of the potassium n‐butanoate were studied. A normal coordinate analysis was carried out, using the force fields established for the propanoate ion and for n‐butane, according to the moiety of the n‐butanoate ion being considered. The Raman spectra of aqueous solutions (2.5 M) and of the solid phases are described. A spectral subtraction method, which is discussed, was used in order to assign the observed bands, on the basis of their behaviour with temperature increase, to the trans and the gauche conformers. Finally, an assignment is proposed, taking into account all the experimental observations, for the four isotopic species, except in the δ(CH), v(CD) and v(CH) ranges.
Resonance Raman spectroscopy of bis(isomaleonitriledithiolato)nickelate(II) as a probe to the chromophore extension
Authors: De Mello M. T. S. , Ribeiro M. C. C. , Santos P. S.
Published: May 2005

The resonance Raman spectrum of bis(isomaleonitriledithiolato)nickelate(II) was investigated in order to assess the extent of the electronic delocalization within the chromophore. Previous results for the isomeric species bis(maleonitriledithiolato)nickelate(II) indicated an extensive delocalization involving the Ni—S, C=C and C≡N bonds. The present results conclusively indicate that in the case of [Ni(imnt)]2− the delocalization is much more restricted, which is in line with a previous suggestion concerning the marked difference in the two species concerning the stability towards oxidation. The resonance Raman results show a very pronounced enhancement of the v(Ni—S) and δ(ring) modes via the Albrech's A term, which is supported by the simulations undertaken using the transform method and the time‐dependent approach.
Structure of some arylazophenols and arylazonaphthols in the solid state: A resonance Raman study
Authors: Bajpai P. K. , Pal Biswajit , Baul T. S. Basu
Published: May 2005

A resonance Raman study of (2‐hydroxy‐5‐metheylphenylazo)benzene and (2‐hydroxynaphthylazo)benzene and their derivatives is presented. The characteristic modes in the azo and hydrazone forms are identified. Structures for both types of compounds in the solid state are proposed. It is shown that hydroxy substitution at the ortho position forms a hydrogen bond with the nitrogen atom of the azo group in arylazophenols. The effect of ring substitution on the characteristic modes is also discussed.
Vibrational molecular force field of model compounds with biological interest VI—harmonic dynamic of methyl α‐D‐mannoside in the crystalline state
Authors: Kouach‐Alix I. , Dauchez M. , Sekkal M. , Vergoten G.
Published: May 2005

A Urey—Bradley—Shimanouchi modified force field was used to establish a set of parameters for the potential energy function of methyl α‐D‐mannopyranoside, which is contained in the glycan part of glycoproteins. This force field was combined with an intermolecular potential energy function which includes Van der Waals interactions, electrostatic terms and an explicit hydrogen bond function. Raman and IR spectra of methyl α‐D‐mannopyranoside are presented. Good agreement was obtained between the observed and calculated vibration wavenumbers. The assignments of the observed vibration bands are compared with those in previous studies.
Raman intensity of K2MCl6 (M = Pt or Sn) by the modified many‐body model
Authors: Kanesaka Isao , Matsuda Toshiyuki , Morioka Yoshiyuki
Published: May 2005

The Raman intensity of K2MCl6 (M = Pt or Sn) was analysed using the many‐body model, which treats the interaction among induced dipoles. The result was satisfactory of K2PtCl6, but not for K2SnCl6. Some improvements to the model were made. It is concluded that the preferred method for analysing simultaneously the Raman intensity of internal and external modes in crystals is to use the many‐body model together with the ordinary method for covalent and/or coordination bonds.
Solvation of chloride ions in alcohols
Authors: Honshoh Masami , Kanno Hitoshi , Ueda Toyotoshi
Published: May 2005

Raman OH stretching spectra were measured for a range of alcoholic LiCl solutions in the glassy state. The sharp OH stretching Raman peak due to alcohol molecules weakly hydrogen bonded to chloride ions shifts to lower wavenumbers with an increase in the molecular weight of an alcohol. A simple model calculation suggests that the shift can be mainly ascribed to the change in the mass of an alkyl group of the alcohol rather than a change in the strength of the hydrogen bond.
Raman study of the kinetics of chloride—organic ion exchange across a membrane
Authors: Delimi R. , Maillols J. , Sandeaux R. , Sandeaux J. , Bribes J.‐L.
Published: May 2005

The combination of Raman spectrometry and radiotracer techniques allowed accurate measurements of ion‐exchange kinetics. The exchange of chloride for benzoate or benzenesulphonate ions was studied. These ions were selected as models to simulate the fouling of membranes, a major inconvenience frequently encountered in membrane processes, especially in bio‐industries. The experimental data were compared with the theoretical treatment proposed for two possible hypotheses, namely particle or film diffusion.
Effects of hydrogen bonding and side‐chain conformation on the Raman bands of tryptophan‐2,4,5,6,7‐d5
Authors: Maruyama Teruhiko , Takeuchi Hideo
Published: May 2005

Tryptophan‐2,4,5,6,7‐d5 (dTrp), in which all the carbon atoms of the indole ring are deuterated, is sometimes used for isotopic labelling of Trp residues in proteins and peptides. The vibrational wavenumbers of the deuterated indole ring were examined in the Raman spectra of eight crystals of dTrp derivatives and compared with the crystal structure and the indole N1‐H stretching wavenumber, a direct indicator of hydrogen bonding strength. The comparison has shown that the Wd4 mode around 1445 cm−1 and the Wd5 mode around 1410 cm−1 of dTrp increase in wavenumber with increase in the strength of hydrogen bonding at the indole N1H site. Another in‐plane vibration of the deuterated indole ring, Wd3, around 1520 cm−1 has been found to change in wavenumber as a function of the absolute value of the torsional angle |χ2, 1| about the Cα—Cβ—C3—C2 linkage. These marker bands of hydrogen bonding and conformation are expected to be useful in the structural analysis of proteins and peptides that are labelled with dTrp.
Electrochemical reduction of CO2 on silver as probed by surface‐enhanced Raman scattering
Authors: Ichinohe Y. , Wadayama T. , Hatta A.
Published: May 2005

Surface‐enhanced Raman scattering (SERS) spectroscopy was used to explore the electrochemical reduction of CO2 at a polycrystalline Ag electrode in KHCO3 aqueous solution saturated with CO2 at room temperature. Raman scattering from the oxidation‐reduction cycled Ag electrode suggests the formation of CO and HCOOH by CO2 reduction. At an electrode potential of 0.08 V (vs. Ag/AgCl), adsorbed CO gives rise to a C‐O stretch band at 2128 cm−1. This band decreases in intensity and shifts to higher wavenumber with an increase of negative potential in the range from 0.0 to − 0.24 V. A different potential dependence is observed for the C‐H stretch mode of adsorbed HCOO− (2870 cm−1 at − 0.8 V). The O‐C‐O antisymmetric and symmetric stretch modes of HCOO− observed at near 1550 and 1350 cm−1 decrease in intensity with increasing negative potential, presenting a striking contrast to the C‐H stretch mode. The SERS experiment with a CO2‐saturated KHCO3D2O solution is also described and discussed.
Structural characterization of some quinolin‐8‐ol‐containing azo dyes in solid and solution state as probed by resonance Raman, fourier transform IR and electronic spectroscopic techniques
Authors: Bajpai P. K. , Pal Biswajit , Baul T. S. Basu
Published: May 2005

Some 5‐(aryl)azoquinolin‐8‐ol derivatives were studied by resonance Raman, Fourier transform IR and electronic spectroscopic techniques. Analysis of vibrational and electronic spectra was used to determine the azo and hydrazone forms in both the solid and solution states. In the solid state, the compounds remain dominantly in one form and the characteristic bands due to each resonating form were identified. Various structural motifs for protonated, neutral and deprotonated states were proposed based on pH‐dependent studies. The effect of H‐bonding in stabilizing a particular type of structure is also discussed.
Raman spectroscopic study of complex formation between p‐cresol and propionitrile
Authors: Pemberton R. S. , Shurvell H. F.
Published: May 2005

Raman spectroscopy, together with factor analysis and band resolution techniques, was used to study complex formation in binary mixtures of p‐cresol and propionitrile in the concentration range 0.025‐0.651 mole fraction of p‐cresol. The envelope of the C  N stretching band of propionitrile in the Raman spectrum between 2300 and 2200 cm−1 was studied. Factor analysis indicated that there were only two linearly independent components in the band envelope. The appearance of a pseudo‐isosbestic point in the area normalized spectra supported this conclusion. For all concentrations, the C  N stretching band envelope was resolved into three components. These were assigned in turn to the free propionitrile, a 1:1 p‐cresol‐propionitrile complex and an overtone or combination mode of propionitrile which does not involve C  N stretching. The equilibrium constant Kc for the formation of the complex was determined at various mole fractions of p‐cresol. The calculated values of Kc exhibited a strong concentration dependence.
Effect of ethanol on SERS spectra of water in a 0.5 M KCl—water—silver electrode system
Authors: Choi Young‐Seok , Kim Jong‐Jean
Published: May 2005

The effect of ethanol on the surface‐enhanced Raman scattering (SERS) of water molecules in a 0.5 M KCI‐water‐silver electrode system was studied by observing changes in the SERS band of water as a function of the time of ethanol addition during the oxidation‐reduction cycle. Hydrogen bond breaking, the main role of ethanol, in the SERS system of water‐ethanol seems to be a necessary condition but not a sufficient condition for observing SERS of water. Surface adatoms of Ag0‐Cl− should also be available at the time of the hydrogen bond breaking by ethanol mixing.
Peculiar intensity distribution in the Raman spectra of copper organoacetylides
Authors: Garbuzova I. A. , Gol'ding I. R. , Schegolikhin A. N.
Published: May 2005

Raman spectra of polymeric photoconductive copper organoacetylides (RCCCu)x differ substantially from the spectra of other CuI or AgI compounds which lack photoconductive properties. Also, there is a significant redistribution of band intensities in the Raman spectra of the copper organoacetylides compared with the spectra of the parent acetylenes. The triple bond stretching vibration, v(CC), at ca 1950−1900 cm−1, v(C‐C) at ca 950−700 cm−1 and the lines at ca 600−500 cm−1, caused by deformations of angles between the multiple and single bonds, in the spectra of copper acetylide exhibit an increase in intensity by a factor of 10–100 compared with the spectra of parent acetylenes RCCH. The vibrational bands characteristic of the R substituent itself seem to be very weak in comparison with the unusually strong band of the acetylide in the lower Raman shift range. The origin of these unusual Raman intensities in copper organoacetylides is discussed.
Coherent nuclear motions in light‐harvesting pigments and dye molecules, probed by ultrafast spectroscopy
Authors: Chachisvilis Mirianas , Fidder Henk , Pullerits TÕNu , Sundström Villy
Published: May 2005

The temporal evolution of the transient absorption response of light‐harvesting antennae and dye molecules was studied. Using 40—90 fs pulses coherent nuclear motions were observed in intact membrane‐bound photosynthetic light‐harvesting pigment‐protein complexes, bacteriochlorophyll α monomer and dye molecules in solutions. Computer simulations based on the harmonic Franck—Condon approximation and the Langevin equation describe qualitatively well the wavelength dependence of the oscillations of the mode when exciting and probing in the blue side of the spectrum.
Solvent and frequency dependence of vibrational dephasing on femtosecond time‐scales
Authors: Vöhringer P. , Westervelt R. A. , Yang T.‐S. , Arnett D. C. , Feldstein M. J. , Scherer N. F.
Published: May 2005

The results of degenerate wavenumber third‐order polarization (pump‐probe) measurements of vibrational dephasing and relaxation in a variety of solvents are reported. The 20 fs duration pulses are sufficiently short to allow the preparation and detection of vibrational coherences (i.e. wavepackets) to 800 cm−1 oscillator wavenumber. The high quality of the pump‐probe data permits the unique determination of eight underdamped modes for the cyanine dye under study. The relaxation of the underdamped modes does not show a significant solvent dependence. The relaxation mechanisms that give rise to loss of vibrational coherence and to the solvent‐dependent relaxation of low‐wavenumber (<100 cm−1) modes are discussed. The wavenumber dependence of the vibrational dephasing rate varies with a scaled exponential dependence exp( —ω/ω0), or equally well with the inverse square of the vibrational wavenumber. The exponential form would imply that vibrational dephasing occurs by population relaxation. The latter form, however, may imply higher order coupling between the bath and solute through the solute vibrational anharmonicity such that the off‐diagonal contributions to the prepared wavepacket relax by pure dephasing. Exponentially decaying contributions to the pump—probe signal are found to arise from overdamped modes that are excited by the short laser pulses as opposed to a solvation response. The solvent‐dependent relaxation of these overdamped modes is determined to be similar to diffusive unimolecular barrier crossing dynamics observed in dense media.
Intermolecular vibrational coherence in molecular liquids
Authors: Lotshaw William T. , McMorrow Dale , Thantu Napoleon , Melinger Joseph S. , Kitchenham Robert
Published: May 2005

The femtosecond optical heterodyne detected optical Kerr effect/Raman‐induced Kerr effect (OHD OKE/RIKE) is described in detail with emphasis on the utility for investigating the intermolecular spectra and dynamics of liquids. The femtosecond dynamics of the liquids CS2, benzene and CCI4are addressed through a combination of conventional time‐domain kinetic and Fourier‐transform analyses, and the physical origin of the intermolecular intensity is addressed for each. The distinctions between the excitation mechanisms of the femtosecond OKE/RIKE and other continuous‐wave and picosecond Raman techniques are described. The distinctions between the dephasing mechanisms of intramolecular and intermolecular vibrational modes are discussed.
Scrimshaw: Real or fake? A fourier‐transform Raman diagnostic study
Authors: Edwards H. G. M. , Farwell D. W. , Seddon T. , Tait J. K. F.
Published: May 2005

The Fourier‐transform (FT) Raman spectra of genuine samples of scrimshaw are reported and compared with those of fake scrimshaw, ivory and human milk tooth. The major spectral features in all systems examined were assigned. The application of the FT‐Raman technique to the non‐destructive diagnostic identification of scrimshaw and simulated scrimshaw artefacts is demonstrated.
Raman study and lattice dynamics calculation of the misfit layer compound (PbS)1.12VS2
Authors: Sourisseau C. , Cavagnat R. , Fouassier M. , Tirado J. L. , Morales J.
Published: May 2005

The UV—visible (340—800 nm) and Raman spectra (10—900 cm−1) obtained using various laser exciting radiation of a powder sample of the misfit compound (PbS)1.12 VS2 were investigated. In agreement with x‐ray data, vibrational assignments are proposed for most of the internal and external modes of the ‘PBS’ and ‘VS2’ layered sublattices and they were extensively compared with those in the related titanium‐containing compound in order to appreciate the interactions due to the ‘PbS’ donor part of the structure. Owing to the incommensurate structure of (PbS)1.12 VS2, new slightly resonance exhanced Raman signals are detected and they can be explained by the k = O, ± q* selection rules (q* is the modulation vector) as in a previous study of (SnS)1.17 NbS2 and (PbS)1.18 TiS2 compounds. These observations are again confirmed by lattice dynamics calculations which reproduce the essential features of the experimental data and allow one to estimate the strength of interlayer interactions.
Property tensors and tensorial covariants of the 58 magnetic crystallographic point groups
Authors: Brandmüller J. , Illig D.
Published: May 2005

As shown in a previous paper, Neumann's principle allows one to calculate the forms of property tensors and tensorial covariants of classical point groups. A simple extension of this principle permits one to determine also the corresponding expressions for magnetic point groups. In this paper the results for the crystallographic point groups are given.
Determination of enantiomeric excess using Raman optical activity
Authors: Hecht Lutz , Phillips Anthony L. , Barron Laurence D.
Published: May 2005

A simple method for the determination of enantiomeric excess is described. It is based on depolarized Raman optical activity (ROA) measurements in right‐angle scattering employing the incident ciruclar polarization (ICP) modulation approach. The accuracy of this method was assessed utilizing α‐pinene as a chiral test compound. The four α‐pinene ICP ROA signals associated with the Raman bands observed at ca. 772, 787, 887 and 929 cm−1 were selected to establish a linear relationship between ROA signal strength and enantiomeric composition for a set of calibration mixtures containing both α‐pinene enantiomers. Using this relationship, a (+)‐α‐pinene sample content of 16.3% was determined for a blind mixture containing 83.6% (1S)‐( — )‐α‐pinene and 16.4% (1R)‐(+)‐α‐pinene. Similary, utilizing additional spectral subtraction procedures, a (+)‐α‐pinene sample content of 1.5% was estimated for a test mixture consisting of 50.1% (1S)‐( — )‐α‐pinene and 49.9% (1S)‐( — )‐trans‐pinane.
Raman tensor of adenine residue for the 1580 cm−1 vibration and its orientation in a biopolymer
Authors: Tsuboi Masamichi , Ueda Toyotoshi , Ushizawa Koichi , Nagashima Nobuya
Published: May 2005

The adenine residues of nucleic acids give a medium‐intensity Raman band around 1580 cm−1 and protonated adenine residue around 1560 cm−1. Each of them shows a peculiarly high degree of depolarization, α = 0.65, in aqueous solutions. A corresponding band, at 1562 cm−1, shows a high anisotropy in the single crystal of uridylyl‐(3′‐5′)‐adenosine (UpA). On the basis of the known structure of this crystal, and on the basis of the polarized Raman data (488.0 nm excitation), the shape and orientation of the Raman tensor associated with this 1562 cm−1 vibration have been determined: one of its principal axes (y‐axis) is directed along the long axis of the adenine residue and r1 = αxx/αzz = − 3 and r2 = αyy/αzz = 4. A general relationship has also been derived between the orientation angles (θ and χ) of the adenine residues with a uniaxial arrangement in a biopolymer and the anisotropy of the 1580 cm−1 Raman scattering intensity. This relationship has been used in a discussion of the orientation of the adenine residue in the poly(rA)·poly(rU) duplex fibre.
Picosecond transient Raman spectra of photoexcited 4‐dimethylamino‐4′‐nitrostilbene in polar solvents
Authors: Nakabayashi T. , Okamoto H. , Tasumi M.
Published: May 2005

Picosecond transient Raman spectra of photoexcited 4‐dimethylamino‐4′‐nitrostilbene in polar solvents (acetonitrile, acetone and benzonitrile) were observed and the decay kinetics of the observed Raman bands were analysed. The observed solvent dependences of the peak positions suggest that the transient Raman bands arise from a non‐radiative charge‐transfer (CT) state. Molecules in the vibrationally excited CT states were also observed by monitoring transient anti‐Stokes Raman scattering. These results indicate that a rapid non‐radiative transition occurs from the lowest allowed singlet state to vibrationally excited CT states.
Fourier transform Raman and fourier transform ir spectroscopic investigation of pyrazine adsorbed by sepiolite and bentonite from anatolia
Authors: Akyüz S. , Akyüz T. , Davies J. E. D. , Esmer K. , Özel A. Erbölükbaş
Published: May 2005

The adsorption of pyrazine by two different Anatolian sepiolites and by natural and ion‐exchanged (Fe, Co, Cu and Sn) bentonites was investigated by vibrational spectroscopy. The spectroscopic results indicate that the pyrazine molecules adsorbed on sepiolite and bentonites are coordinated to either surface hydroxyls by H‐bonding interaction (in the case of sepiolite) or to exchangeable cations (in the case of bentonites) through both nitrogen lone pairs as bidentate ligands. X‐ray diffraction patterns of the clays were also recorded and the basal spacings of pyrazine‐treated natural and ion‐exchanged bentonites were found to be around 14.7 Å. The results suggest that pyrazine molecules intercalate the interlayers of bentonite with a monolayer arrangement.
Effect of nafion on geometry and axial ligation in manganese (III) tetraphenylporphyrins
Authors: Maclean Angela L. , Armstrong Robert S. , Kennedy Brendan J.
Published: May 2005

Manganese(III) porphyrins were successfully incorporated into Nafion, wherein they are located in the ionic pockets of the polymer. The result of UV—visible spectroscopy indicate that at least one solvent molecule and the anion accompany the macrocycle into the membrane. The anion is only loosely associated with the porphyrin, but strongly coordinating solvents such as pyridine remain in the axial coordination sites. Dramatic changes which were observed in the electronic and resonance Raman spectra when THF and dioxane were used as incorporation solvents indicate that the geometry of the macrocyle also changes when in Nafion. Puckering of the porphyrin ring apparently occurs as it interacts with the restrictive environment in Nafion.
Raman spectroscopic study of the avidin—biotin complex
Authors: Fagnano C. , Fini G. , Torreggiani A.
Published: May 2005

Raman spectra of avidin, biotin and the avidin‐biotin complex were recorded. The percentages of secondary structure of avidin and the avidin‐biotin complex were obtained from the Raman spectra. The vibrational results indicate that, as a consequence of the interaction of avidin with biotin, the β‐sheet conformation percentage decreases and the α‐helical conformation percentage increases. Moreover, the interaction of avidin with biotin is also able to change slightly the tertiary structure of the protein. In fact, as a consequence of the binding of biotin, the hydrophobicity of the environment of Trp increases slightly according to the intensity increase of the 1360 cm−1 component. The intesity of all bands attributable to Trp residues increases with biotin binding, indicating that Trp is directly involved in the interaction. These results are in agreement with the results of UV measurements which indicate a red shift of the avidin Trp absorption bands as a consequence of the binding to biotin.
Vibrational study of eight‐membered titanium and germanium‐containing siloxane rings
Authors: Haoudi‐Mazzah A. , Dhamelincourt P. , Gnado J. , Mazzah Ahmed
Published: May 2005

By a condensation reaction of tBu2Si(OH)2(L) with titanium and germanium tetrahalides several eight‐membered titanium and germanium cyclosiloxane compounds were prepared in polar solvents. These were crystallized and identified by the usual physical techniques (1H, 13C and 29Si NMR spectroscopy, x‐ray diffraction and mass spectrometry). Raman and IR spectra were also recorded, which confirmed the structure obtained by x‐ray diffraction. The rings are well characterized by breathing modes which appear around 620–660 cm−1 and Si‐O‐M stretching‐bending modes which appear around 950–1000 cm−1. The vibrational modes characterizing the tert‐ butyl group are weakly coupled with those of the heterocycles. The corresponding observed bands are close to those observed for (L).
Conformational equilibria for 3‐methylstyrene: Raman and FTIR spectra and ab initio calculations
Authors: Meurisse I. , Ribeiro‐Claro P. J. A. , Teixeira‐Dias J. J. C. , Pouchan C.
Published: May 2005

The Raman spectra of liquid 3‐methylstyrene show pairs of bands whose temperature‐dependent intensities clearly suggest the occurrence of a conformational equilibrium. From these bands, assigned to cis and trans conformers, a trans‐cis energy difference of 0.8 + 0.2 kJ mol−1 was obtained for the liquid phase. On the other hand, ab initio calculations at the 3‐21G** and MP2/3‐21G* levels predict a cis form more stable than the trans form by less than 0.15 kJ mol−1, in good agreement with gas‐phase literature results.
Raman scattering investigation of the central peak in lead lanthanum zirconate—titanate‐x/95/5 ceramics with × = 0—4 mol% of La2O3
Authors: El‐Harrad I. , Becker P. , Carabatos‐Nédelec C. , Handerek J. , Ujma Z. , Dmytrow D.
Published: May 2005

It is demonstrated that in the ferroelectric phase of the PLZT‐x/95/5 ceramics the spontaneous polarization is the order parameter, the fluctuations of which are mainly responsible for the dielectric relaxations manifested in the Raman spectra by the appearance and the evolution of a central peak. For T >315°C, in the paraelectric phase, the spontaneous polarization fluctuations are substituted by the fluctuations of the appearing local concentration polarization. Above the Curie temperature, the thermally activated relaxation process gives an activation energy of 0.7 eV.
New method for obtaining Raman spectra of extremely small quantities of light‐absorbing substances adsorbed on silver from very dilute solutions
Authors: Macklin John W.
Published: May 2005

Micro‐Raman spectra of picogram to sub‐femtogram quantities of several chromophoric substances adsorbed from dilute solution on silver were measured and compared with similar measurements on some non‐chromophoric substances. The silver surface enhanced resonance Raman measurements require no redox roughening of the surface, sometimes no applied potential and only 1‐2 mW of defocused laser power. The new method by which silver surface enchancement is achieved requires contact of the surface with halide ion solution for several hours. The most astounding results thus far were achieved with 1, 1′‐diethyl‐2,2′‐cyanine iodide (2,2′‐cyanine). Raman spectra of the adsorbate from 20 ml of 1 × 10−17 M solution of the dye were measured using the method. Further characteristics of the phenomenon were obtained based on extensive Raman measurements on 2,2′‐cyanine. Some further details resulting from these measurements are described.
A comparative study of eggshell proteins in lepidoptera
Authors: Paul Miles , Kafatos Fotis C. , Regier Jerome C.
Published: May 2005

As a first step in the study of chorion composition, biochemical development and morphogenesis, we have studied the proteins of moth chorions (eggshells). We draw attention to the extensive similarities of these proteins in a variety of species. We also report that the eggshell proteins are deposited in succession, each with its characteristic time table. This phenomenon may be related to the morphogenesis of chorion.
Mitochondrial membranes and mutagenesis by ethidium bromide
Authors: Mahler Henry R. , Perlman Philip S.
Published: May 2005

The conversion of wild type (ρ+) to cytoplasmic petites (ρ−) in Saccharomyces cerevisiae, à mutation in mitochondrial DNA, can be brought about with high efficiency by low concentrations of ethidium bromide (EB). The rate and extent of mutagenesis and its expression can be influenced, and even reversed, by a number of genetic lesions, agents or treatments affecting mitochondrial structure and metabolism. Among them are incubation at 45°, exposure to Antimycin A, growth on different carbon sources and the presence or absence of 2 different gene products previously implicated in the repair of UV induced lesions in mitochondrial DNA. Based on these observations a model for EB mutagenesis is advanced which postulates a complex between mitochondrial DNA and the inner membrane as the target susceptible to modification by EB. This model predicts that altered membranes should lead to changes in the susceptibility of cells to the mutagenic action of EB. This prediction has been verified by comparing cells that contain one of 2 structurally quite distinct monounsaturated C18 fatty acids in their mitochondrial phospholipids: greater resistance to mutagenesis and ease of thermal protection is exhibited when cells – and mitochondria – contain oleic (Δ9cis, m.p. < 5°) rather than petroselinic (Δ6cis, m.p. 28°) acid in their phospholipids. As a corollary, studies on EB mutagenesis and mitochondrial DNA may be used as probes for the mitochondrial inner membrane to reveal some perhaps novel functions.
The effects of branched chain fatty acid incorporation into Neurospora crassa membranes
Authors: Brody Stuart , Allen Barry
Published: May 2005

Phytanic acid (3,7,11,15‐tetramethylhexadecanoic acid), an unusual branched chain fatty acid thought to disrupt the hydrophobic regions of membranes, can be incorporated into the lipids of growing Neurospora cultures. The phytanic acid must be supplied in a water soluble form, esterified to a Tween detergent (Tween‐Phytanic). This fatty acid and its oxidation product, pristanic acid, were found in both the phospholipid and neutral lipid fractions of Neurospora. In phospholipids of the wild‐type strain, phytanic acid was present to the extent of 4 to 5 moles percent of the fatty acids and pristanic acid, about 41 moles percent. The neutral lipids contained 42 and 4 moles percent of phytanic and pristanic acids respectively. By employing a fatty acid‐requiring mutant strain (cel−), the phytanic acid level was raised to a maximum of 16 moles percent in the phospholipids and to 63 moles percent in the neutral lipids. Under this condition, the level of pristanic acid was reduced to about 6 moles percent in phospholipids and 1 mole percent in the neutral lipids. The phytanic acid levels could not be further elevated by increased supplementation with phytanic acid or by a change in the growth temperature. In strains with a high phytanic acid content, the complete fatty acid distribution of the phospholipids and neutral lipids was determined. In the neutral lipids, phytanic acid appeared to replace the 18 carbon fatty acids, particularly linoleic acid.

The presence of phytanic acid in the phospholipids was confirmed by mass spectrometry, and by the isolation of a phospholipid fraction containing this fatty acid via silicic acid column chromatography. Most of the phytanic acid in phospholipids appeared to be in phosphatidylethanolamine, and 2 lines of evidence suggest that it was esterified to both positions of this molecule. In the fatty acid‐requiring mutant strain (cel−), the replacement by phytanic acid of 10 to 15% of the fatty acids in the phospholipid produced an aberrant morphological change in the growth pattern of Neurospora and caused this organism to be osmotically more fragile than the wild‐type strain. The lack of noticeable effect of the high levels of pristanic acid in the phospholipids suggests that it is not just the presence of the methyl groups in a branched chain fatty acid which leads to the altered membrane function in this organism.
The kinetics of colicin E3 induced fragmentation of Escherichia coli 16S ribosomal RNA in vivo
Authors: Samson A. C. R. , Senior B. W. , Holland I. B.
Published: May 2005

Fixation of colicin E3 to sensitive bacteria is followed, after a lag of 2 to 6 min, by the rapid degradation of all the RNA of the 30S ribosomal subunits, yielding a large 15.5S fragment and a smaller fragment, containing the 3′‐terminal end of the 16S RNA. The small RNA fragment which was estimated to consist of about 52 nucleotides, was retained within the 30S subunit in vivo and was subsequently recovered quantitatively without apparent further degradation. Kinetic studies of the cleavage of 16S RNA indicated that this is the primary and lethal effect of colicin E3 and the primary cause of the observed inhibition of protein synthesis in vivo. Small amounts of an RNA fragment, apparently identical in size to the small E3‐fragment, were also isolated from 30S particles obtained from untreated bacteria.
Studies on mixed micelles of triton X–100 and phosphatidylcholine using nuclear magnetic resonance techniques
Authors: Dennis Edward A. , Owens Jerry M.
Published: May 2005

The addition of the nonionic detergent Triton X‐100 to aqueous phosphatidyl‐choline dispersions converts the bilayer structures to mixed micellar structures containing Triton X‐100. High‐resolution nuclear magnetic resonance spectroscopy at 220 MHz was used to follow this conversion, and the general spectral characteristics of the mixed micelles are presented. The results are discussed in terms of the precise change in structure which occurs as Triton is mixed with the phospholipid bilayers, and it is concluded that, above a molar ratio of about 2:1 Triton to phospholipid, most or all of the phospholipid is in mixed micelles. The relevance of these results to the study of enzymes which require substrate in the form of micelles is discussed.
Structural studies on the organization of proteins in mitochondrial membranes using proteolytic enzymes
Authors: Pasquali Petronio , Landi Laura , Masotti Lanfranco , Lenaz Giorgio
Published: May 2005

Proteolytic enzymes, pronase and trypsin, digest protein in ETP and in SU‐particles (devoid of the soluble ATPase) at similar rates and to the same extents for intact and lipid‐depleted membranes, showing that lipids do not constitute a barrier to the action of the proteases. The rates and extents of hydrolysis are slightly depressed when membranes are reconstituted from lipid‐depleted particles and phospholipids. The hydrolysis rates for the various particles are not greatly enhanced by detergent solubilization nor by other denaturing treatments, indicating that the rates measured in absence of treatments are maximal under the conditions used. The circular dichroism spectra of pronase treated ETP are noticeably altered showing modification of the original conformation. Moreover, enzymic activities of mitochondria and submitochondrial particles are progressively affected by proteases according to their localization at, or near to, a given surface of the membrane. The matrix enzyme, malate dehydrogenase, is not apparently released from mitochondria during the initial incubation period. The results are tentatively discussed in terms of organization of lipids and proteins in the mitochondrial membrane.
Colicin Ia and Ib binding to Escherichia coli envelopes and partially purified cell walls
Authors: Konisky Jordan , Cowell Billie S. , Gilchrist Mary J.
Published: May 2005

The specific binding of 125 Iodine labelled colicin Ia and Ib to Escherichia coli cell envelopes and partially purified cell walls is demonstrated. Neither partially purified cytoplasmic membranes isolated from a wild type sensitive strain nor envelopes or cell walls prepared from an E. coli mutant known to be defective in the colicin I receptor could bind the colicins. Competition studies suggest that colicins Ia and Ib have a common bacterial receptor which resides in the bacterial cell wall.
Selective solubilization of proteins from red blood cell membranes by protein perturbants
Authors: Steck Theodore L. , Yu John
Published: May 2005

Isolated human erythrocyte membranes were exposed to a series of reagents known to modify or perturb proteins; these included sodium hydroxide, lithium diiodosalicylate, acid anhydrides, and organic mercurials. Each reagent liberated the same set of relatively polar polypeptides from the membrane, while the other, more hydrophobic species invariably remained associated with the membrane residue. The selective elution pattern was precisely that seen previously with 6 M guanidine hydrocloride. The released polypeptides, comprising half of the membrane protein mass, contained no carbohydrate; current evidence indicates that all of these components are confined to the cytoplasmic surface of the membrane. The residue contained all the lipids and all the glycoproteins. The latter are accessible to the outer membrane surface and, in at least two cases, seem to extend asymmetrically across the thickness of the membrane. Thus, the distinctive elution behavior which defines these two groups of polypeptides relates both to their chemical composition and their organizational disposition in the membrane.
Lateral diffusion of rhodopsin in the visual receptor membrane
Authors: Poo Mu‐ming , Cone Richard A.
Published: May 2005

If the rhodopsin on one side of an isolated rod outer segment is suddenly bleached, the rhodopsin on the other side can be observed with a microspectrophotometer to diffuse rapidly across the width of the rod. Uniform distribution is approached exponentially with a half‐time at 20°C of 23 ± 3 sec in rods isolated from mudpuppy (Necturus maculosus) retina and 35 ± 3 sec in rods isolated from frog (Rana catesbeiana) retina. These rods are 12 and 8 μ in diameter, respectively. Taking the geometry of the rod disk membranes into account, we obtain a lateral diffusion constant for rhodopsin in the disk membrane of (4.0 ± 1.5) × 10−9 cm2/sec for both mudpuppy and frog. No diffusion was observed if rods were first fixed with glutaraldehyde. The diffusion constant increased with temperature with a Q10 between 2 and 4 in the temperature range near 20°C. If the effective diameter of rhodopsin is assumed to be about 50 Å, the Stokes–Einstein relationship implies the effective viscosity for lateral diffusion of rhodopsin is about 2 poise. This value, as well as the Q10, are essentially the same as indicated by the rapid rotational diffusion of rhodopsin previously observed by flash photometry in frog rods.

Cone, R. A., Rotational Diffusion of Rhodopsin in the Visual Receptor Membrane, Nature (London) New Biology, 236:39 (1972).
The differentiation of rat liver endoplasmic reticulum membranes: Apo–cytochrome P450 as a membrane protein
Authors: Siekevitz Philip
Published: May 2005

The proteins of washed microsomal membranes from adult rat liver were solubilized by 2% SDS and electrophoresed on polyacrylamide gels. Confirming earlier reports, a large Coomassie‐Blue staining band in the ∼50,000 MW region was identified as cytochrome P450 by four criteria: similar electrophoretic mobility to a purified cytochrome P450 preparation, an increase in this band after in vivo phenobarbital administration, a decrease in this band after in vivo allylisopropylacetamide administration, and direct specific binding of added purified heme to this region of a washed, unfixed gel. Although cyt P450 is not spectrally evident until just at the time of birth of the rats, a large band in this region was detectable in gels of microsomal membrane protein at all times, from three days before birth onward; this band also bound added heme after membrane proteins from fetal rat liver microsomes were electrophoresed on the gels. The conclusion was that apo‐cyt P450 is present in microsomal membranes at these times during differentiation, and that, regarding this protein, during differentiation heme is bound to the apo‐protein already there, concomitant with a synthesis of more cyt P450 molecules. The process of differentiation of this membrane type is also discussed.
Multiple forms of porcine pancreatic phospholipase A2: Isolation and specificity
Authors: Tsao Francis H. C. , Cohen Herschel , Snyder William R. , Kézdy Ferenc J. , Law John H.
Published: May 2005

Porcine pancreatic phospholipase A2 was purified from commercial pancreatin by a method involving heat denaturation, trichloroacetic acid precipitation, and DEAE‐cellulose chromatography. Assaying the eluate of the chromatography step by a new titrimetric method using vegetable lecithin‐albumin emulsion as the substrate, several species of phospholipase A were found. Some of these went undetected when the conventional egg yolk emulsion assay was used. Two phospholipases A2 were isolated in a homogeneous form and shown to have similar chemical and physical properties. Catalytic specificity of the two enzymes differs remarkably toward lecithins in different emulsified states.
Genetic control of ribosome assembly
Authors: Sypherd Paul S. , Bryant Robert , Dimmitt Kathleen , Fujisawa Toshitaka
Published: May 2005

The assembly of E. coli ribosomes has been studied through the analysis of a new group of ribosome maturation mutants. These mutants, all blocked in a late stage in the maturation of 50S ribosomes, map at four different sites on the chromosome. These sites are distant from the known ribosomal protein sites at the str‐aro E region of the chromosome. The ribosome precursor particles of the mutants contain precursor‐type 23S RNA (p23 RNA) and 5S RNA. 43S particles of one of the mutants contain all but one of the normal complement of proteins. Precursor 43S particles from this mutant can be converted to particles with sedimentation values around 50S by incubation with extracts from either the wild‐type organism or from other mutants. This in vitro conversion process differs considerably from the process of ribosome reconstitution and indicates a role for extrinsic factors in the maturation of E. coli ribosomes.
The regulation of flagellar formation and function
Authors: Hilmen M. , Silverman M. , Simon M.
Published: May 2005

The basal structure of the flagellum controls both activity and assembly. In order to define the steps involved in these processes, genetic analysis was performed. Twenty genes were found to be required for the complete assembly and function of the organelle. FlaE controls the length of the hook, flaA is required both to maintain flagellar structure and for chemotaxis, and flaI plays a role in regulating the synthesis of the entire structure. Mutations mapping close to flal (the cfs mutations) release flagellar synthesis from control by catabolite repression.

The basal structure was purified and isolated. On SDS acrylamide gel electrophoresis, it contained at least six distinguishable components. One major band corresponded to the hook subunit with an apparent molecular weight of 42,000 daltons. The others had apparent molecular weights of 60,000, 40,000, 28,000, 25,000, and 18,000 daltons. The genes that correspond to these polypeptides have not been identified.

In exploring the role of the mot and che genes, assays were developed for the function of individual flagellar filaments. The filaments were found to rotate and rotation could be modulated by changing their direction. Chemotaxis results from the modulation of flagellar rotation. Using the rotation assay the response of nonmotile cells to attractants and repellents was followed.