Light quark mass differences and charge symmetry breaking in hyperon-nucleon interaction

Quantum chromodynamics based isovector isoscolar particle mixing arising out of isospin violating quark mass differences has been used to construct a new charge-symmetry breaking Λ-N interaction element. It appears that vector meson exchanges between N and a physical Λ rather than pseudoscalar exchanges provide the largest contribution to explain the binding energy difference between the mirror hyper-nuclei _ΛHe⁴ and _ΛH⁴. Prediction of the model to Λn and Λp scattering lengths have been compared with those obtained from the combined analysis of ΛN scattering and s-shell hyperfragment data. We find satisfactory agreement of our results.     

BINDING OF HEMATOPORPHYRIN DERIVATIVE TO HUMAN SERUM ALBUMIN

Abstract Dialysis of hematoporphyrin derivative fraction A (HpD-A) off human serum albumin at 38°C followed the Hill equation for cooperative binding with saturation at 5 to 8. 600 dalton porphyrin units. Approximately 15% of the HpD-A was free for concentrations typical of human serum in photoradiation therapy. Possible structures of the tumor-localizing and -photosensitizing component in HpD-A are considered. Of these, a folded-over, covalent dimer appears to be more consistent with the photophvsical properties.     

Scalar variational analysis of single mode,graded-core,W-type fibres

A scalar variational analysis for the fundamental mode of a graded-core, W-type fibre based on single and two parameter trial fields has been presented. Comparison with the exact numerical results shows that the two parameter trial field estimates the propagation characteristics accurately.On study leave from Physics Department, G.M. College, Sambalpur-768004, India.     

Studies on the reaction products of bis(2-furanthiocarboxyhydrazidato)m(II) with pyridine-2- and -4-carboxaldehydes

Condensation of bis(2-furanthiocarboxyhydradatometal(II), M(fth)₂; [M (II) = Mn, Fe, Co, Ni, Cu and Zn] with pyridine-2- and -4-carboxaldehydes gave complexes of the formula M(pfth)₂ [pfth? = pyridine-2-carboxaldehyde-2-furanthiocarboxyhydrazonato], Ni(Ifth)₂, Zn(Ifth)₂, Cu(Ifth) and Co(Ifth)₃, (Ifth? = pyridine-4-carboxaldehyde-2-furanthiocarboxyhydrazonato). The magnetic and electronic spectral studies coupled with photoacoustic or Mössbauer spectra suggested octahedral geometry for the M(II) complexes with low-spin states for Co(Ifth)₃ and Fe(pfth)₂. IR and ¹H NMR spectral studies of diamagnetic complexes suggested bonding through “azomethine” nitrogen and “thiolo” sulphur. IR spectra also showed the involvement of pyridine ring nitrogen in coordination in all the complexes except Cu(Itfh), Co(Ifth)₃, and Zn(Ifth)₂. Some of the compounds possessed antimicrobial activity.     

THE POSSIBLE PRESENCE OF A THIRD INTERMEDIATE FOR IODOPSIN AT -195°C*

Abstract— From the theoretical analysis of the time variation of the change in absorbance of chicken iodopsin solution (at—195°C), the formation of a new intermediate during bleaching has been suggested.     

Magnetic phase diagram of anisotropic layered superconductors via magnetization measurements forH‖c in Bi2212

The Bi₂Sr₂CaCu₂O₈ system is viewed as an archetypal of superconductors modelled as Josephson coupled CuO₂ bilayers. The isothermal and temperature dependent DC and AC magnetization measurements forH‖c in a single crystal of Bi2212 have been performed. Qualitative changes are observed to occur over a narrow range of temperature values before reaching the superconducting-normal transition. The observed behaviour can be ascribed to the rapid variation in the strength of the coupling between the superconducting CuO₂ planes (i.e., bilayers in the case of Bi2212). Strongly coupled planes behave like a 3D superconductor, whereas weakly coupled planes have a two component response attributable to 2D planes and interplanar couplings. We believe that this paper is a plethora of new findings. Our observations imply that resistivity across the planes becomes zero earlier than that within the planes. A new line (designated asH _2D(T)) above which the change in the electromagnetic response is dominated by quasi 2D-planes has been determined for the first time. This paper also contains the first observation of Differential Diamagnetic Effect (DDE) in the In-phase AC susceptibility data which signals the onset (atT _2D(H)) of dominance of response from 2D-planes. In addition to a host of interesting thermomagnetic history effects which are a consequence of interplay between the diamagnetic responses from the two components, a comparison of irreversibility lines (of the 3D state) determined by different methods on the same specimen of a HTSC is also being presented for the first time. We have come across Paramagnetic Meissner Effect (PME), first recognized in ceramic samples of Bi2212, in the temperature region of dimensional crossover in our single crystal sample, whichinter-alia confirms our labelling of the two component behaviour. A schematic phase diagram summarizing the various transformations that can occur nearT _c in the electromagnetic response of an anisotropic layered system has been drawn.     

Static and thermophysical properties of chalcogenide crystals with NaCl structure

In the present communication an analysis of interionic potentials in fourteen chalcogenide crystals has been performed. This interionic potential has been used to predict the values of cohesive energy, isothermal bulk modulus and the pressure derivatives of bulk modulus in the solids under study. The many body interaction (MBI) effects have been taken into account within the framework of Hafemeister Zarht potential. Instead of using BM potential the Hafemeister-Zarht (HZ) type short range overlap potential has been considered between nearest as well as between next nearest neighbour ions. The short-range interactions, effective up to second neighbours are treated by considering the hardness parameter as an ionic property. The hardness parameter ρ_ij is evaluated using the data on overlap integrals. The results achieved in the present study are generally in good agreement with available experimental data. Values of cohesive energy, bulk modulus and its pressure derivatives calculated by previous investigators have also been shown for the sake of comparison.     

On microbending loss calculations in single mode fibers with arbitrary index profiles

We present an analytical method to evaluate the auxiliary function and spot sizes determining microbending loss in single mode fibers with arbitrary refractive index profiles. Comparison with the exact numerical results shows that the present method gives very accurate results for spot sizes. The method is simple and requires relatively less computational effort.