New algorithms for constrained minimax optimization

A constrained minimax problem is converted to minimization of a sequence of unconstrained and continuously differentiable functions in a manner similar to Morrison's method for constrained optimization. One can thus apply any efficient gradient minimization technique to do the unconstrained minimization at each step of the sequence. Based on this approach, two algorithms are proposed, where the first one is simpler to program, and the second one is faster in general. To show the efficiency of the algorithms even for unconstrained problems, examples are taken to compare the two algorithms with recent methods in the literature. It is found that the second algorithm converges faster with respect to the other methods. Several constrained examples are also tried and the results are presented.     

Macrocyclic paracyclophane synthesis

Macrocyclic stilbene derivatives are prepared using strong base to couple the terminal carbons of 1,12-bis-[4-chloromethylphenyl]-dodecane and its homologs.     

Leptodermous expansion of nuclear ground state energies and the anomaly in the nuclear curvature energy

The leptodermous expansion of the total ground state energy of a nucleus into volume, surface, curvature and gauss curvature contributions has been studied starting from a semi-classical energy density formalism of extended Thomas Fermi type. A numerical procedure was used to obtain the surface energy and curvature energy contributions from surface moments of energy density profilesH(r) for a sequence of nuclei withN=Z and neglecting the coulomb interaction for the three Skyrme forces. A transition to the liquid drop model type expansion in increasing powers ofA ^−1/3 is then made, taking into account the dependence of the central density and the surface structure on the mass of the nucleus. It is found that there is no inconsistency between the curvature contribution to the total energy in the leptodermous expansion and theA ^−1/3 term contribution in the liquid drop model expansion. It has been shown that the earlier apparent anomaly between the above two methods arises due to the use of semi-infinite approximation and the mass dependence of the central density and the surface structure of finite nuclei.     

A new approach to irreversibility from maximum entropy estimation

This paper deals with the study of some irreversible processes like slow heating of a thermodynamic system or of inhomogeneity, i.e. spatially local equilibrium in it, based on the principle of maximum entropy estimation, in a stochastic model.     

DNA damage by fasicularin

Fasicularin is a structurally novel thiocyanate-containing alkaloid isolated from the ascidian Nephteis fasicularis. Early biological experiments suggested that this compound's cytotoxic properties may stem from its ability to damage cellular DNA. Sequence gel analysis reveals that treatment of a 5'-32P-labeled DNA duplex with fasicularin in pH 7.0 buffer causes strand cleavage selectively at guanine residues. Further experiments indicate that production of these base-labile lesions in DNA involves alkylation of guanine residues by a fasicularin-derived aziridinium ion. This work reveals fasicularin as the first natural product found to generate a DNA-alkylating aziridinium ion via a mechanism analogous to the clinically used anticancer drugs mechlorethamine, melphalan, and chlorambucil.     

Electrical and magnetic properties of antimony sulphide (Sb2S3) crystals and the mechanism of carrier transport in it

The principal magnetic susceptibilities, electrical conductivities and thermoelectric powers of Sb₂S₃ single crystals have been studied in the temperature range 100–550 K. An analysis of the results on the basis of its anomalous crystal structure and of the proposition of the hopping process of conduction at higher temperatures, account for the discrepancy between findings from magnetic and electrical observations.     

On a study of the superposition effect of diffracted X-rays by a liquid column and the optimum thickness for X-ray diffraction

A measure of intensity due to the superposition of diffracted X-rays from elementary regions in the line of X-ray path has been calculated on the basis of Gaussian distribution of intensity from every element. This gives the optimum thickness for maximum intensity implicitly by the relation. Μt₀=α?′(αt₀)/?(αt₀) where ? is the error integral and α is a characteristic of the liquid which determines the Gaussian distribution form for the particular liquid. Good agreement between the theoretical relations and the experimental values have been observed.