Mössbauer and magnetic studies of the system Li0.35 + 0.5t Zn03Ti t Fe2.35 − 1.5t O4

Mössbauer and magnetic investigations were carried out on a series of Li-Zn-Ti ferrites with compositional formula Li_035?+?0.5t Zn₀₃Ti _t Fe_2.35???1.5t O₄. Mössbauer spectra were taken at room temperature and analysed to yield information on hyperfine properties like isomer shift, quadrupole splitting and nuclear magnetic fields. Magnetic properties like Curie temperature and saturation magnetization have also been studied. The magnetic properties were observed to fall with increased values of ‘t’. The results obtained and the mechanisms involved are discussed.     

A facile approach to chiral 1,4-benzodioxane toward the syntheses of doxazosin,prosympal, piperoxan,and dibozane

The process describes the concise synthesis of (R/S)-enantiomers of doxazosin, an antidepressant drug and α-adrenergic receptor antagonists like prosympal, piperoxan, and dibozane in practical yields from easily available (R)-2,3-O-cyclohexylidene-d-glyceraldehyde and (S)-3-(benzyloxy)propane-1,2-diol.     

An Efficient Approximation Algorithm for Minimizing Makespan on Uniformly Related Machines

We give a new and efficient approximation algorithm for scheduling precedence-constrained jobs on machines with different speeds. The problem is as follows. We are given n jobs to be scheduled on a set of m machines. Jobs have processing times and machines have speeds. It takes p_j/s_i units of time for machine i with speed s_i to process job j with processing requirement p_j. Precedence constraints between jobs are given in the form of a partial order. If j k, processing of job k cannot start until job j's execution is completed. The objective is to find a non-preemptive schedule to minimize the makespan of the schedule. Chudak and Shmoys (1997, “Proceedings of the Eighth Annual ACM-SIAM Symposium on Discrete Algorithms (SODA),” pp. 581–590) gave an algorithm with an approximation ratio of O(log m), significantly improving the earlier ratio of due to Jaffe (1980, Theoret. Comput. Sci.26, 1–17). Their algorithm is based on solving a linear programming relaxation. Building on some of their ideas, we present a combinatorial algorithm that achieves a similar approximation ratio but runs in O(n³) time. Our algorithm is based on a new and simple lower bound which we believe is of independent interest.     

Approximation Algorithms for Dispersion Problems

Given a collection of weighted sets, each containing at most k elements drawn from a finite base set, the k-set packing problem is to find a maximum weight sub-collection of disjoint sets. A greedy algorithm for this problem approximates it to within a factor of k, and a natural local search has been shown to approximate it to within a factor of roughly k − 1. However, neither paradigm can yield approximations that improve on this.We present an approximation algorithm for the weighted k-set packing problem that combines the two paradigms by starting with an initial greedy solution and then repeatedly choosing the best possible local improvement. The algorithm has a performance ratio of 2(k + 1)/3, which we show is asymptotically tight. This is the first asymptotic improvement over the straightforward ratio of k.     

Dissociation energy of diatomic molecules — comment on the work of Kaur and Mahajan

When observed spectrum of a diatomic molecule is expressed in terms of the Dunham coefficients Y ₀₀, Y ₁₀, Y ₂₀, Y ₀₁ and Y ₁₁ only, dissociation energy of the molecule is given by Y ₀₀+Y ₁₀ ² /(−4Y ₂₀). Kaur and Mahajan [1] have used the Dunham coefficients Y ₁₀, Y ₂₀, Y ₀₁, and Y ₁₁, for 15 vibrational states of 12 diatomic molecules (Y ₀₀ is zero for the cases accounted for), but their dissociation energy cannot be reproduced by the expression Y ₁₀ ² /(−4Y ₂₀). Probable reason for the discrepancy has been discussed.     

Microstructure, magnetic and magnetoimpedance properties in electrodeposited NiFe/Cu and CoNiFe/Cu wire with thiourea additive in plating bath

Magnetic thin films of NiFe and CoNiFe alloys were electrodeposited from three different deposition baths onto copper wires of 100-μm diameter. The magnetic and magnetoimpedance (MI) properties of the samples along with their microstructure were investigated as a function of thiourea additive concentrations (C_T) in the plating bath. For all intermediate frequencies, the MI ratio increased with thiourea concentration in plating bath up to a critical concentration of 80 mg/l and then decreased considerably. The change in MI with thiourea concentration in electrodeposition bath was attributed to the grain size reducing action of thiourea, which in turn enhances the soft magnetic properties of the films. At higher concentration of thiourea, the sulfur inclusion increased the magnetic softness and MI value enhanced considerably. The origin of MI lies in the combined effect of domain wall motion and spin rotation, which contributes to permeability. Inductance spectroscopy (IS) was used to evaluate the magnetic characteristic of the samples by modeling coated wires in terms of equivalent electrical circuit; namely parallel LR (inductance and resistance) circuit in series with series LR circuit. The domain wall motion was found to be greatly affected by thiourea addition in the bath, which was revealed through the study of variation of these circuit parameters. The domain wall motion thereby affects the magnetic softness of samples, which is reflected in the MI enhancement.     

Structural,thermal, and ion dynamics studies of PVA-CS-NaI-based biopolymer electrolyte films

Journal of Solid State Electrochemistry - A series of biopolymer blend electrolytes (BPBEs) based on ((100-x)PVA-xCS)-NaI, viz. BPBE-1 to BPBE-5 (x = 10, 20, 30, 40, 50 in wt%), respectively, were...