Comparative Study of Vocal Communication in Two Asian Leaf Monkeys, Presbytis johnii and Presbytis entellus

This paper presents comparative data on the vocal communication of two Asian leaf monkeys, the Nilgiri langur (Presbytis johnii) and South Indian common langur (Presbytis entellus), based on sound recordings and behavioural observations of free-ranging groups. Spectrographical analyses revealed a repertoire of 18 basic patterns for Nilgiri langurs, and 21 basic patterns for common langurs. The repertoires of the two langur species consist of both discretely structured vocal patterns, in which alterations of the physical parameters are restricted to intra-class variation, and those in which structural variations cause intergradation between different sections of the repertoire. Qualitative assessments of group scans indicate that in both species vocal behaviour is characterized by pronounced sex-differences in the use of the different elements of the vocal repertoire. Comparison of data available from different populations of P. entellus suggests population-specific modifications on both structural and behavioural levels. Moreover, characteristic elements of the vocal systems of the two Asian species demonstrate striking similarities to those described for the African black-and-white colobus.

Phase diagram and dielectric studies of binary organic materials

The phase equilibrium studies of organic system, involving resorcinol (R) and p-dimethylaminobenzaldehyde (DMAB), reveal the formation of a 1:1 molecular complex with two eutectics. The heat of mixing, entropy of fusion, roughness parameter, interfacial energy, and the excess thermodynamic functions were calculated based on enthalpy of fusion data determined via differential scanning calorimetric (DSC) method. X-ray powder diffraction studies confirm that the eutectics are not simple mechanical mixture of the components under investigation. The spectroscopic investigations (IR and NMR) suggest the occurrence of hydrogen bonding between the components forming the molecular complex. The dielectric measurements, carried out on hot-pressed addition compound (molecular complex), show higher dielectric constant at 320 K than that of individual components. The microstructural investigations of eutectic and addition compound indicate dendritic and faceted morphological features. (C) 2000 Elsevier Science B.V. All rights reserved.

High-Resolution Magic Angle Spinning Nmr-Studies Of P-31 And B-11 In Fast Ion Conducting Agi-Ag2o-P2o5 And Agi-Ag2o-B2o3 Glasses

Silver iodide-based fast ion conducting glasses containing silver phosphate and silver borate have been studied. An attempt is made to identify the interaction between anions by studying the chemical shifts of31P and11B atoms in high resolution (HR) magic angle spinning (MAS) NMR spectra. Variation in the chemical shifts of31P or11B has been observed which is attributed to the change in the partial charge on the31P or11B. This is indicative of the change in the electronegativity of the anion matrix as a whole. This in turn is interpreted as due to significant interaction among anions. The significance of such interaction to the concept of structural unpinning of silver ions in fast ion conducting glasses is discussed.

Crystallization Studies of ZrO2-SiO2 Composite Gels

Composite ZrO2-SiO2 powders were prepared using a gel route. Morphological and crystallographic features of ZrO2 particles formed during the heat treatment, and the particle sizes of the composites have been investigated. The following polymorphic changes have been observed during the heat treatment: amorphous -> metastable-cubic/tetragonal ZrO2 -> tetragonal ZrO2 -> monoclinic ZrO2. SiO2 crystallizes above 1273 K. The martensitic transformation of ZrO2 (t -> m) was observant in situ, when exposed to a high-energy electron beam. These results are important in the production of ZrO2-toughened ceramics of controlled microstructure.

ESR studies of X-irradiated strontium mixed calcium tartrate crystals

The electron spin resonance spectra of X-ray irradiated single crystals of strontium doped calcium tartrate tetrahydrate (CST) with molecular formula Ca0.88Sr0.12C4H4O6.4H(2)O grown in gels has been investigated. Only one species of free radical but with two magnetically unequivalent sites was observed at room temperature. The free radical was found to be the result of the splitting of a C-II bond adjacent to both the hydroxyl and carboxyl groups. The a factor was found to be slightly anisotropic. Couplings with two H nuclei, believed to be the proton of the OH group attached directly to the unsaturated asymmetric carbon atom and the proton attached directly to the: other asymmetric carbon atom of the molecule were observed. The principal g-values were found to be 2.0030, 2.0017, 2.0027. The principal elements of the nuclear coupling are 7.45, 6.59, 4.28 and 8.56, 7.22, 18.71 G, respectively. The radical was found to be very stable. (C) 2000 Elsevier Science Ltd. All rights reserved.

Conformations of dehydrophenylalanine containing peptides: nmr studies of an acyclic hexapeptide with two delta Z-Phe residues

The conformation of an acyclic dehydrophenylalanine (delta Z-Phe) containing hexapeptide, Boc-Phe-delta Z-Phe-Val-Phe-delta Z-Phe-Val-OMe, has been investigated in CDCl3 and (CD3)2SO by 270-MHz 1H-nmr. Studies of NH group solvent accessibility and observation of interresidue nuclear Overhauser effects (NOEs) suggest a significant solvent-dependent conformational variability. In CDCl3, a population of folded helical conformations is supported by the inaccessibility to solvent of the NH groups of residues 3-6 and the detection of several NiH----Ni + 1H NOEs. Evidence is also obtained for conformational heterogeneity from the detection of some Ci alpha H----Ni + 1H NOEs characteristic of extended strands. In (CD3)2SO, the peptide largely favors an extended conformation, characterized by five solvent-exposed NH groups and successive Ci alpha H----Ni + 1H NOEs for the L-residues and Ci beta H----Ni + 1H NOEs for the delta Z-Phe residues. The results suggest that delta Z-Phe residues do not provide compelling conformational constraints.

A comparative study of superconducting LaBa2Cu3O7−δ and La3−xBa3+xCu6O14+δ

Based on X-ray diffraction and electron microscopy it is shown that oxides of the general formula La Ba2Cu3O7−δ become tetragonal when δ deviates slightly from 0. This tetragonal structure is similar to that of La3−xBa3+xCu6O14+δ, with a cubic perovskite subcell and triple periodicity. Electron micrographs of these tetragonal oxides show 90° microdomains. Orthorhombic LaBa2Cu3O7−δ with high Tc (not, vert, similar77 K) is found only when δ reverse similar, equals 0; this sample is subject to formation of twins. Fluorine substitution seems to favor superconductivity.

A comparative study of the magnetic and electrical properties of perovskite oxides and the corresponding two-dimensional oxides of K2NiF4

Electrical and magnetic properties of several oxide systems of K2NiF4 structure have been compared to those of the corresponding perovskites. Members of the La1−xSr1+xCoO4 system are all semiconductors with a high activation energy for conduction unlike La1−xSrxCoO3 (x ≥ 0.3) which is metallic; the latter oxides are ferromagnetic. La0.5Sr1.5CoO4 shows a magnetization of 0.5 μB at 0 K (compared to 1.5 μB of La0.5Sr0.5CoO3), but the high-temperature susceptibilities of the two systems are comparable. In SrO · (La0.5Sr0.5MnO3)n, both magnetization and electrical conductivity increase with the increase in n approaching the value of the perovskite La0.5Sr0.5MnO3. LaSrMn0.5Ni0.5(Co0.5)O4 shows no evidence of long-range ferromagnetic ordering unlike the perovskite LaMn0.5Ni0.5(Co0.5)O3; high-temperature susceptibility behavior of these two insulating systems is, however, similar. LaSr1−xBaxNiO4 exhibits high electrical resistivity with the resistivity increasing proportionately with the magnetic susceptibility (note that LaNiO3 is a Pauli-paramagnetic metal). High-temperature susceptibility of LaSrNiO4 and LaNiO3 are comparable. Susceptibility measurements show no evidence for long-range ordering in LaSrFe1−xNixO4 unlike in LaFe1−xNixO3 (x ≤ 0.35) and the electrical resistivity of the former is considerably higher. Electrical resistivity of Sr2RuO4 is more than an order of magnitude higher than that of SrRuO3. Some generalizations of the properties of two- and three-dimensional oxide systems have emerged from these experimental observations.

Crystal structure of 2-thiophene-2-yl-3(thiophene-2-carboxylideneamino)-1,2-dihydroquinazolin-4(3H)-one and the synthesis, spectral and thermal studies of its transition metal(II) complexes

The synthesis of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of a new ligand 2-thiophene-2-yl-3(thiophene-2-carboxylidene-amino)-1,2-dihydroquinazolin-4(3H)-one (TTCADQ) is described. The ligand and metal complexes were characterized by elemental analysis, conductivity measurements, spectral (u.v.-vis., i.r., 1D n.m.r., 2D hetcor and e.p.r.) and thermal studies. The formation of 1,2-dihydroquinazolin-4(3H)-one rather than hydrazone, in the reaction of aromatic aldehyde and o-aminobenzoylhydrazide is proved by single crystal X-ray diffraction and 2D hetcor n.m.r. studies. On the basis of elemental analysis, u.v.-vis.spectroscopy and magnetic moment studies, six coordinate geometry for all the complexes was proposed. The i.r. spectral studies reveal the bidentate behaviour of the ligand.