Time dependent argon glow discharge treatment of Al-alloy samples

Aluminium alloy ultra-high vaccum system provides a convenient tool to access the UHV region due to short pump down time, its reduced weight, low cost etc. For UHV systems, aluminium and its alloys are preferred materials to stainless steel. A cylincrical discharge chamber of SS 304 with various ports on it, evacuated by turbomolecular pumping unit is used in the experimental system. A hollow cathode de glow discharge in argon for different time durations is used to treat chemically cleaned ASA 6063 aluminium alloy samples, keeping all other parameters constant. The scanning electron microscope (SEM) is used to examine processed surfaces and to study topographical features. The energy dispersive microanalysis by X-rays (EDX) is used to determine the elemental composition of the samples. The results indicate the physical sputtering taking place in Ar GDC. The etched area increases with discharge time duration. The EDX spectrum shows the inconsistency in weight percentage of various elements of Al-alloy.     

Weak convergence to a Markov process: The martingale approach

Summary In this article, we obtain some sufficient conditions for weak convergence of a sequence of processes {X _n } toX, whenX arises as a solution to a well posed martingale problem. These conditions are tailored for application to the case when the state space for the processesX _n ,X is infinite dimensional. The usefulness of these conditions is illustrated by deriving Donsker's invariance principle for Hilbert space valued random variables. Also, continuous dependence of Hilbert space valued diffusions on diffusion and drift coefficients is proved.Research supported by National Board for Higher Mathematics, Bombay, IndiaPart of the work was done at University of California, Santa Barbara, USA     

1,2-Benzisoxazole-3-acetamide derivatives as dual agents for DPP-IV inhibition and anticancer activity

Abstract

Herein, we have designed various benzisoxazole acetamide derivatives with and without glycine spacer as DPP-IV inhibitors. Compounds 9a–d and 11a–e were synthesized and screened for their in vitro DPP-IV inhibition. Compounds 11a and 11c showed moderate activity for DPP-IV inhibition, whereas other remained inactive at 25–200?µM concentrations. DPP-IV inhibition can be a good strategy for modulating diabetes and cancer; hence, we have screened compounds 9a–d and 11a–e for their anticancer activity using MTT assay against A549 and MCF7 cell lines. Compounds 9a–d without glycine spacer have shown good anticancer activity compared to compounds 11a–e with glycine spacer. Compound 9b has shown moderate activity with IC₅₀ values 4.72?±?0.72 and 4.39?±?0.809?µM against A549 and MCF7 cell lines, respectively. Interestingly, compound 9c with cyano group has shown very good anticancer activity with IC₅₀ 2.36?±?0.34?µM against MCF7 cell line as compared to fluorouracil with IC₅₀ 45.04?±?1.02?µM.     

The effect of crucible movement in Bridgman-Stockbarger technique

The effect of the crucible movement on the growth of large size alkali halide crystals effected in a ceramic crucible by B-S technique is investigated. From the studies carried out it follows that the crucible movement adversely affects the thermal conditions in the furnace resulting in a defective growth. To circumvent the problems faced suitable modification of the conventional B-S technique yielding good crystals is suggested.     

Orbital analysis of bonding in diarylhalonium salts and relevance to periodic trends in structure and reactivity

Diarylhalonium compounds provide new opportunities as reagents and catalysts in the field of organic synthesis. The three center, four electron (3c–4e) bond is a center piece of their reactivity, but structural variation among the diarylhaloniums, and in comparison with other λ³-iodanes, indicates that the model needs refinement for broader applicability. We use a combination of Density Functional Theory (DFT), Natural Bond Orbital (NBO) Theory, and X-ray structure data to correlate bonding and structure for a λ³-iodane and a series of diarylchloronium, bromonium, and iodonium salts, and their isoelectronic diarylchalcogen counterparts. This analysis reveals that the s-orbital on the central halogen atom plays a greater role in the 3c–4e bond than previously considered. Finally, we show that our revised bonding model and associated structures account for both kinetic and thermodynamic reactivity for both acyclic phenyl(mesityl)halonium and cyclic dibenzohalolium salts.

A revised bonding model for diarylhalonium salts, that involves partial s-orbital contribution, provides new insight into periodic trends in structure and reactivity.     

Measure free martingales

We give a necessary and sufficient condition on a sequence of functions on a set Ω under which there is a measure on Ω which renders the given sequence of functions a martingale. Further such a measure is unique if we impose a natural maximum entropy condition on the conditional probabilities.     

On Interacting Systems of Hilbert-Space-Valued Diffusions

A nonlinear Hilbert-space-valued stochastic differential equation where L ^-1 (L being the generator of the evolution semigroup) is not nuclear is investigated in this paper. Under the assumption of nuclearity of L ^-1 , the existence of a unique solution lying in the Hilbert space H has been shown by Dawson in an early paper. When L ^-1 is not nuclear, a solution in most cases lies not in H but in a larger Hilbert, Banach, or nuclear space. Part of the motivation of this paper is to prove under suitable conditions that a unique strong solution can still be found to lie in the space H itself. Uniqueness of the weak solution is proved without moment assumptions on the initial random variable. A second problem considered is the asymptotic behavior of the sequence of empirical measures determined by the solutions of an interacting system of H -valued diffusions. It is shown that the sequence converges in probability to the unique solution Λ ₀ of the martingale problem posed by the corresponding McKean—Vlasov equation. Accepted 4 April 1996     

A finitely additive white noise approach to nonlinear filtering

An approach to nonlinear filtering theory is developed in which finitely additive white noise replaces the Wiener process in the observation process model. The important case when the signal is a Markov process independent of the noise is investigated in detail. The theory turns out to be simpler than the current theory based on the stochastic calculus. Stochastic partial differential equations are replaced by partial differential equations in which the observation (in the finitely additive set up) occurs as a parameter. Theorems on existence and uniqueness of solutions are obtained. The white noise approach has the advantage that it provides a robust solution to the filtering problem. Furthermore, the robust theory based on the Ito calculus can be recovered from the results of this paper.