3-Acetyl-6-chloro-1-ethyl-4-phenylquinolin-2(1H)-one

In the title compound, C19H16ClNO2, the dihedral angle between the plane of the phenyl substituent and 3-acetylquinoline unit is 75.44 (5)degrees. The crystal structure is stabilized by intermolecular C-H center dot center dot center dot O hydrogen bonds.

Laser Raman spectra of semicarbazide hydrobromide

Semicarbazide hydrobromide which is isomorphous with SEM.HCl, was expected to belong to a new family of ferroelectrics. Dielectric, thermal and other studies on these crystals have yielded results which show many peculiarities but not confirmed ferroelectricity in the low temperature phase. As such a Laser Raman spectrosocopic study of oriented singe crystals of SEM.HBr was made at 298°K and at 253°K. The results have been correlated with structural features and compared with SEM.HCl.

Thermodynamic and kinetic analysis of carbohydrate binding to the basic lectin from winged bean (Psophocarpus tetragonolobus)

A basic lectin (pI approximately 10.0) was purified to homogeneity from the seeds of winged bean (Psophocarpus tetragonolobus) by affinity chromatography on Sepharose 6-aminocaproyl-D-galactosamine. The lectin agglutinated trypsinized rabbit erythrocytes and had a relative molecular mass of 58,000 consisting of two subunits of Mr 29,000. The lectin binds to N-dansylgalactosamine, leading to a 15-fold increase in dansyl fluorescence with a concomitant 25-nm blue shift in the emission maximum. The lectin has two binding sites/dimer for this sugar and an association constant of 4.17 X 10(5) M-1 at 25 degrees C. The strong binding to N-dansylgalactosamine is due to a relatively positive entropic contribution as revealed by the thermodynamic parameters: delta H = -33.62 kJ mol-1 and delta S0 = -5.24 J mol-1 K-1. Binding of this sugar to the lectin shows that it can accommodate a large hydrophobic substituent on the C-2 carbon of D-galactose. Studies with other sugars indicate that a hydrophobic substituent in alpha- conformation at the anomeric position increases the affinity of binding. The C-4 and C-6 hydroxyl groups are critical for sugar binding to this lectin. Lectin difference absorption spectra in the presence of N-acetylgalactosamine indicate perturbation of tryptophan residues on sugar binding. The results of stopped flow kinetics with N- dansylgalactosamine and the lectin are consistent with a simple one- step mechanism for which k+1 = 1.33 X 10(4) M-1 s-1 and k-1 = 3.2 X 10(- 2) s-1 at 25 degrees C. This k-1 is slower than any reported for a lectin-monosaccharide complex so far. The activation parameters indicate an enthalpically controlled association process.

A one-step process for the preparation ofγ-Fe2O3

Abstract is not available.

Infrared spectra of some oxides of K2NiF4 and related structures

The i.r. spectra of some Ln2BO4 and LnSrBO4 compounds (Ln = La, Pr, Nd, Sm or Gd;B = Fe, Al, Co or Cu) with K2NiF4 or related structures have been studied in the range 800-300 cm−1. The BO6 octahedra in compounds with K2NiF4 structure are elongated. The assignment of the bands in terms of internal modes of sheets of bridged BO6 octahedra or square-planar BO4 sheets has been considered. The observed spectra are correlated with those of solid solutions of these oxides and of LnBO3 perovskites. Unusually high stretching frequencies found in some of the oxides are discussed in terms of the short B---O bonds in the basal plane and the Ln---O bonds along the c axis.

Infrared spectra of some oxides of K2NiF4 and related structures

The i.r. spectra of some Ln2BO4 and LnSrBO4 compounds (Ln = La, Pr, Nd, Sm or Gd;B = Fe, Al, Co or Cu) with K2NiF4 or related structures have been studied in the range 800-300 cm−1. The BO6 octahedra in compounds with K2NiF4 structure are elongated. The assignment of the bands in terms of internal modes of sheets of bridged BO6 octahedra or square-planar BO4 sheets has been considered. The observed spectra are correlated with those of solid solutions of these oxides and of LnBO3 perovskites. Unusually high stretching frequencies found in some of the oxides are discussed in terms of the short B---O bonds in the basal plane and the Ln---O bonds along the c axis.

Solvent effects on the structure of N-methylpyrrole as studied by nmr in nematic solvents

The proton NMR spectra of N-methylpyrrole oriented in the nematic phases of liquid crystals with positive and negative diamagnetic anisotropies and their mixtures are reported. Geometrical parameters derived from the spectra at the critical point in the mixture of liquid crystals with positive and negative diamagnetic anisotropies, where macroscopic diamagnetic anisotropy vanishes, are similar to those obtained in the solvent with negative diamagnetic anisotropy. However, significant distortions in the molecular structure attributed to solvent effects have been observed in liquid crystals with positive diamagnetic anisotropy. The minimum energy conformation has one C---H of the methyl perpendicular to the ring.

Studies in metal-ammonia reduction. Part 4. Reduction and reductive methylation of 7-methoxy-3,4-dihydrophenanthren-1(2H)-one and 7-methoxy-1,2-dihydrophenanthren-4(3H)-one

Birch reduction and reductive methylations of the title compounds have been investigated. 7-Methoxy-3,4-dihydrophenanthren-1(2H)-one (2) yields the cis-3,4,9,10,11,12-hexahydro-derivative (15) while the 7-methoxy-1,2-dihydrophenanthren-4(3H)-one (5) is reduced to the corresponding 1,2,9,10-tetrahydro-derivative (7). The factors influencing the mechanism of the reduction process have been discussed. The reductive methylation products of the ketone (2) are useful substrates in the synthesis of 9-methyl steroids.

A rational approach to the synthesis of one-dimensional acoustic filters

The velocity ratio algorithm developed from a heuristic study of transfer matrix multiplication has been employed to bring out the relative effects of the elements constituting a linear, one-dimensional acoustic filter, the overall dimensions of which are fixed, and synthesize a suitable straight-through configuration for a low-pass, wide-band, non-dissipative acoustic filter. The potential of the foregoing approach in applications to the rational design of practical acoustic filters such as automotive mufflers is indicated.

Two-dimensional NMR spectra of oriented molecules

Abstract is not available.

Vibrations of a periodic rail-sleeper system excited by an oscillating stationary transverse force

The rail-sleeper system is idealized as an infinite, periodic beam-mass system. Use is made of the periodicity principle for the semi-infinite halves on either side of the forcing point for evaluation of the wave propagation constants and the corresponding modal vectors. It is shown that the spread of acceleration away from the forcing point depends primarily upon one of the wave propagation constants. However, all the four modal vectors (two for the left-hand side and two for the right-hand side) determine the driving point impedance of the rail-sleeper system, which in combination with the driving point impedance of the wheel (which is adopted from the preceding companion paper) determines the forces generated by combined surface roughness and the resultant accelerations. The compound one-third octave acceleration levels generated by typical roughness spectra are generally of the same order as the observed levels.

Vibration spectra of ferroelectric alkali trihydrogen selenites and the nature of the hydrogen bond potential in these crystals

Raman spectra of the ferroelectric LiH3 (SeO3)2 and NaH3(SeO3)2 and the anti-ferroelectric KH3 (SeO3)2 have been recorded at room temperature using a He-Ne and also an Ar-ion laser source. The infrared absorption spectra of these crystals and their deuterated analogues have been recorded in the region 400–4000 cm−1 both below and above the Curie temperature. From an analysis of the spectrum in the region 400–900 cm−1 it is concluded that (i) in LiH3 (SeO3)2 the protons are ordered in an asymmetric double minimum potential with a low barrier and the spectrum can be interpreted in terms of HSeO3− and H2SeO3 vibrations, (ii) in NaH3 (SeO3)2 all three protons occupy a single minimum potential at room temperature and below the transition temperature the groups HSeO3− and H2SeO3 are present, (iii) the proton at the inversion centre in KH3(SeO3)2 is in a broad troughed potential well and the low temperature spectrum is more likely to be due to H3SeO3+ and SeO32− species. This deviation of the spectrum from that of the previous two crystals is attributed to the difference in H-bond scheme and hence the absence of any cooperative motion of protons in this crystal.

Shape-Dependent Confinement in Ultrasmall Zero-, One-, and Two-Dimensional PbS Nanostructures

Spatial dimensionality affects the degree of confinement when an electron-hole pair is squeezed from one or more dimensions approaching the bulk exciton Bohr radius (alpha(B)) limit. The etectron-hole interaction in zero-dimensional (0D) dots, one-dimensional (1D) rods/wires, and two-dimensional (2D) wells/sheets should be enhanced by the increase in confinement dimensions in the order 0D > 1D > 2D. We report the controlled synthesis of PbS nanomateriats with 0D, 1D, and 2D forms retaining at least one dimension in the strongly confined regime far below alpha(B) (similar to 10 nm for PbS) and provide evidence through varying the exciton-phonon coupling strength that the degree of confinement is systematically weakened by the loss of confinement dimension. Geometry variations show distinguishable far-field optical polarizations, which could find useful applications in polarization-sensitive devices.

Re-examination of one-point methods of liquid limit determination

This Paper deals with the analysis of liquid limit of soils, an inferential parameter of universal acceptance. It has been undertaken primarily to re-examine one-point methods of determination of liquid limit water contents. It has been shown by basic characteristics of soils and associated physico-chemical factors that critical shear strengths at liquid limit water contents arise out of force field equilibrium and are independent of soil type. This leads to the formation of a scientific base for liquid limit determination by one-point methods, which hitherto was formulated purely on statistical analysis of data. Available methods (Norman, 1959; Karlsson, 1961; Clayton & Jukes, 1978) of one-point liquid limit determination have been critically re-examined. A simple one-point cone penetrometer method of computing liquid limit has been suggested and compared with other methods. Experimental data of Sherwood & Ryley (1970) have been employed for comparison of different cone penetration methods. Results indicate that, apart from mere statistical considerations, one-point methods have a strong scientific base on the uniqueness of modified flow line irrespective of soil type. Normalized flow line is obtained by normalization of water contents by liquid limit values thereby nullifying the effects of surface areas and associated physico-chemical factors that are otherwise reflected in different responses at macrolevel.Cet article traite de l'analyse de la limite de liquidité des sols, paramètre déductif universellement accepté. Cette analyse a été entreprise en premier lieu pour ré-examiner les méthodes à un point destinées à la détermination de la teneur en eau à la limite de liquidité. Il a été démontré par les caractéristiques fondamentales de sols et par des facteurs physico-chimiques associés que les résistances critiques à la rupture au cisaillement pour des teneurs en eau à la limite de liquidité résultent de l'équilibre des champs de forces et sont indépendantes du type de sol concerné. On peut donc constituer une base scientifique pour la détermination de la limite de liquidité par des méthodes à un point lesquelles, jusqu'alors, n'avaient été formulées que sur la base d'une analyse statistique des données. Les méthodes dont on dispose (Norman, 1959; Karlsson, 1961; Clayton & Jukes, 1978) pour la détermination de la limite de liquidité à un point font l'objet d'un ré-examen critique. Une simple méthode d'analyse à un point à l'aide d'un pénétromètre à cône pour le calcul de la limite de liquidité a été suggérée et comparée à d'autres méthodes. Les données expérimentales de Sherwood & Ryley (1970) ont été utilisées en vue de comparer différentes méthodes de pénétration par cône. En plus de considérations d'ordre purement statistque, les résultats montrent que les méthodes de détermination à un point constituent une base scientifique solide en raison du caractère unique de la ligne de courant modifiée, quel que soit le type de sol La ligne de courant normalisée est obtenue par la normalisation de la teneur en eau en faisant appel à des valeurs de limite de liquidité pour, de cette manière, annuler les effets des surfaces et des facteurs physico-chimiques associés qui sans cela se manifesteraient dans les différentes réponses au niveau macro.