Effect of energy dependence of primary beam divergence on the X-ray standing wave characterization of layered materials.

Incident primary beam divergence is a source of systematic error in X-ray standing wave (XSW) characterization of single and multilayer thin films. Primary beam divergence significantly alters the XSW profile of a layered material and can lead to large errors when used with higher excitation energies. The present study suggests that when one uses Mo-Kalpha excitation, the primary beam divergence should be in range of 0.005(0). On the other hand, in the case of Cu-Kalpha excitation, primary beam divergence can be relaxed up to 0.01(0).     

Sample preparation for evaluation of detection limits in X-ray fluorescence spectrometry.

The influence of analyte mass concentration on determination of detection limits in X-ray fluorescence spectrometry has been investigated experimentally. Both the total reflection X-ray fluorescence (TXRF) and the conventional energy-dispersive X-ray fluorescence techniques have been used to derive the dependence of analyte mass concentration on the values of detection limits. Results obtained indicate that values of detection limits are optimum, or in other words, they are closer to the true detection limit of the technique, when analyte concentrations are in the range of 10 times of the detection limit.     

Directional couplers in trapped image guide configuration

Dispersion characteristics and wave impedance of trapped coupled image guides are computed by using mode matching techniques. Dispersion curves for trapped coupled image guide are plotted for various dielectric materials and dimensional parameters. The hybrid directional couplers in the above configuration have been theoretically designed by computing the normalization propagation constant.     

Theoretical and experimental vibration analysis of an oblique space frame

This paper has the general objectives of relating analytical and experimental techniques for analysis of indeterminate spatial frames under dynamic loading. The model used has been made as general as possible to explore validity for nonstereotyped configurations. A highly redundant oblique four-bar space frame was selected having a lowest natural frequency of 42.1 cps. Recent success of the finite-element-matrix method and progress in the field of nonlinear optimization provides a rational basis for the synthesis of space frames; however, the validity of the discretization, both for strength-stiffness analysis and dynamic analysis, has not been explored for this type of configuration. The flexibility influence coefficients, the natural frequencies and the steady-state vibration amplitudes were experimentally determined and compared with theoretical values. Influence coefficients had an “error” of between four and 10 percent; the six lowest natural frequencies were in agreement within 15 percent when rotary inertia was considered. Steady-state amplitudes were in good agreement at frequencies not too close to resonance.     

Modeling the depletion of dissolved oxygen in a water body located near a city

Water bodies located nearby cities are much prone to pollution, especially in the developing countries, where effluents treatment facilities are generally lacking. The main reason for this phenomenon is the increasing population in the cities, and the large number of industries located near them. This leads to generation of huge amounts of domestic and industrial sewage that is discharged into the water bodies, increasing their organic pollutant load and resulting in the depletion of dissolved oxygen. In this paper, we propose a mathematical model for this situation, focusing especially on the resulting quality of the water, determined by the level of dissolved oxygen. The model also accounts for resources needed for the population survival and for the industrial operations. In addition, we describe also the decomposition of organic pollutants by bacteria in the aquatic medium. Feasibility conditions and stability criteria of the system's equilibria are determined analytically. The results show that human population and industries are relevant influential factors responsible for the increase in organic pollutants and the decrease in dissolved oxygen in the water body, in the sense that they may exert a destabilizing effect on the system. The numerical simulations confirm the analytical results. Copyright © 2016 John Wiley & Sons, Ltd.     

Fuzzy goal programming for inventory management: A bacterial foraging approach

An efficient inventory planning approach in today’s global trading regime is necessary not only for increasing the profit margin, but also to maintain system flexibility for achieving higher customer satisfaction. Such an approach should hence be comprised of a prudent inventory policy and clear satisfaction of stakeholder’s goals. Relative significance given to various objectives in a supply chain network varies with product as well as time. In this paper, a model is proposed to fill this void for a single product inventory control of a supply chain consisting of three echelons. A generic modification proposed to the membership functions of the fuzzy goal-programming approach is used to mathematically map the aspiration levels of the decision maker. The bacterial foraging algorithm has been modified with enhancement of the algorithms’ capability to map integer solution spaces and utilised to solve resulting fuzzy multi-objective function. An illustrative example comprehensively covers various decision scenarios and highlights the underlying managerial insights.     

Synthesis and α‐glucosidase inhibitory,DPPH scavenging activity of substituted 2‐oxo‐2H‐chromen‐7‐yl‐dihydrogen phosphate derivatives

Series of phosphorylated coumarin derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were synthesized by Pechmann condensation, phosphorylation, and debenzylation reactions in very good yields. Thus, synthesized compounds ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were evaluated for their α‐glucosidase and 1,1‐diphenyl‐2‐picrylhydrazyl scavenging activities; few compounds showed moderate to good activity. J. Heterocyclic Chem., 00 , 00 (2011).     

Synthesis of BF2 complexes of prodigiosin type oligopyrroles

We developed a simple, facile route for the synthesis of BF(2) complexes of prodigiosin type oligopyrroles and their cholesterol conjugates. This route gives an access to synthesize any desired meso-aryl-substituted 3-pyrrolyl BODIPYs which were not easily accessible earlier.     

Enantioselective formal hydration of α,β-unsaturated acceptors: asymmetric conjugate addition of silicon and boron nucleophiles

The direct enantioselective 1,4-addition of water to α,β-unsaturated acceptors is an open challenge in asymmetric catalysis. Enantioselective conjugate addition of either silicon or boron nucleophiles and subsequent enantiospecific oxidative degradation of the carbon-element bond represents, however, an attractive detour. A single extra step thereby enables an indirect enantiocontrolled construction of (in a broader sense) aldols from α,β-unsaturated carbonyl and carboxyl compounds. While that strategy had been obvious for a long time, it was recent stunning progress in transition metal-catalysed activation of interelement linkages that brought about the solution to that long-standing problem. A concise introduction of existing protocols for stereoselective 1,4-addition of oxygen nucleophiles is followed by a comprehensive summary of the recent rapid advances in transition metal-catalysed (and metal-free) asymmetric conjugate transfer of nucleophilic silicon and boron onto α,β-unsaturated acceptors.     

Gas chromatography-electron ionization-mass spectrometry analysis of O,O'- dialkyl methylphosphonites for verification analysis of the Chemical Weapons Convention

Gas chromatography-mass spectrometry (GC-MS) analysis of O,O'-dialkyl methylphosphonites (DAMPs) was carried out with a view to developing a database and understanding the mechanism of fragmentation. DAMPs are included in the list of schedule 2B4 chemicals of the Chemical Weapons Convention. GC-MS analysis of DAMPs and their deuterated analogs revealed that their fragmentations were dominated by α-cleavages, alkenyl radical loss and hydrogen rearrangements. Based on fragment ions of deuterated analogs and density functional theory calculations, the fragmentation routes were rationalized.