Determination of titanium in bauxite: A comparison of neutron activation analysis with the X-ray fluorescence method

The determination of the titanium content of bauxite samples of various origin was studied by thermal neutron activation and X-ray analysis. A²⁵²Cf-fission neutron source and a Ge(Li) detector as well as a³H exciting source and a Si(Li) detector were used in the investigations. Within equal measuring times and with a sample weight of 8 g the sensitivity of the activation method is 0.35 w% Ti with an absolute statistical error less than 10%, while that of the X-ray method is 0.06 w% Ti and the absolute statistical error does not exceed 5%.     

On some operators in multichannel scattering

We investigate the strong limit of an operator valued sequence used in other form in the nonrelativistic theory of multichannel scattering, and also some of its consequences.     

Synthesis of bridged carbocyclic systems related to diterpenes involving intramolecular cyclisation of diazomethyl ketones

The tricyclic dienediones 5,6 and 7 have been synthesised for entry into the ring systems of the tetracyclic diterpenes atisirene (1), phyllocladene (3) and hibaene (4) respectively.     

Propagation,reflection and transmission of waves under initial shear stresses

The paper deals with the study of propagation of Love waves and reflection as well as transmission of SH waves under initial shear stresses. The results have been computed taking two real media and presented graphically to compare with the initial stress-free cases.     

Metal complexes of pyrimidine-derived ligands—IV. synthesis,characterisation and coordinating properties of two guanidino pyrimidines: Ni(II) complexes with 2-guanidino-4,6-dimethyl pyrimidine and 2-phenyl guanidino-4,6-dimethyl pyrimidine—potential ligands or biological interest

Synthesis and spectroscopic characterisation (IR, mass, PMR) of 2-guanidino 4,6-dimethyl pyrimidine (GPym) and 2-phenyl guanidino 4,6-dimethyl pyrimidine (PG-Pym) are reported. Complexation of the title ligands with nickel(II) salts in moisture-free condition furnish complex species of the type: Ni(GPym)₂X₂[X = Cl, Br, SCN and NO₃] and Ni(PGPym)₂X₂ [X = Cl, Br, I and SCN]. Physico-chemical characterisation of the complex species have been made from molar conductance data, magnetic susceptibility measurements, electronic and vibrational spectra. Magnetic and electronic spectral features suggest a pseudo-octahedral environment of the central Ni(II) ion in all these complexes. IR spectra have furnished positive information regarding the bonding sites of the ligand molecules (namely, the pyrimidyl nitrogen and the imino nitrogen of the guanidine residue) and the mode of the attachment of the counterion(X) to the metal ion.     

Study on the disturbances of a piezoelectric disc with concentric electrodes

The radial displacement of an annular piezoelectric ceramic disc with concentric electrodes has been found with the help of transform calculus when the external periphery is subjected to a time-dependent force.1B, Bankim Chatterjee Street, Calcutta-12, West Bengal, India.The author is grateful to Dr. R. R. Giri of Jadavpur University for his kind help and guidance in the preparation of this paper.     

Development of a Computer Program to Predict the β-Lactamase Activity on the Basis of Ampicillin Fluorescence Values

Decrease in ampicillin fluorescence values (Ex. 385 nM, Em. 460 nM) were correlated with the increase in the pUC 19 plasmid-encoded -lactamase activity of Escherichia coli DH5. The fluorescence data were then utilized for the development of a computer program in MS DOS Q BASIC to predict the -lactamase activity.     

Nonorientable Manifolds, Complex Structures, and Holomorphic Vector Bundles

A generalization of the notion of almost complex structure is defined on a nonorientable smooth manifold M of even dimension. It is defined by giving an isomorphism J from the tangent bundle TM to the tensor product of the tangent bundle with the orientation bundle such that JJ=–Id _TM . The composition JJ is realized as an automorphism of TM using the fact that the orientation bundle is of order two. A notion of integrability of this almost complex structure is defined; also the Kähler condition has been extended. The usual notion of a complex vector bundle is generalized to the nonorientable context. It is a real vector bundle of even rank such that the almost complex structure of a fiber is given up to the sign. Such bundles have generalized Chern classes. These classes take value in the cohomology of the tensor power of the local system defined by the orientation bundle. The notion of a holomorphic vector bundle is extended to the context under consideration. Stable vector bundles and Einstein–Hermitian connections are also generalized. It is shown that a generalized holomorphic vector bundle on a compact nonorientable Kähler manifold admits an Einstein–Hermitian connection if and only if it is polystable.     

Helical supramolecular host with aquapores anchoring alternate molecules of helical water chains

Unprecedented 1D helical chains of hydrogen bonded water molecules, showing both handedness and anchored onto a helical supramolecular host formed from the self assembly of a dicopper(II) complex (1) containing pentadentate Schiff base (L) and p-hydroxycinnamate in 1.2H(2)O, propagate along the crystallographic 2(1)-screw axis and the compound shows two endotherms due to loss of water molecules at 61.5 and 88.5 degrees C in the differential scanning calorimetry giving an overall change of enthalpy value of approximately 36 kJ mol(-1) per water molecule.