Potential anticonvulsants. VII. Synthesis of 5′-methylspiro[3H-indole-3,2′-thiazolidine]-2,4′(1H)-diones

The title compounds have been prepared, by the cyclocondensation of thiolactic acid with isatin-3-imines. 5′-Methyl-3′-phenyl-spiro[3H-indole-3,2′-thiazolidine]-2,4′(1H)-dione has been subjected to the Mannich condensation to give 1-substituted derivatives. With one exception, all of the products were inactive in an anticonvulsant screen.     

Transmission of surface acoustic waves through the interface based on discontinuity of electrical boundary conditions on surface of potassium niobate

This paper presents theoretical investigation of the propagation of surface acoustic waves (SAWs) across the boundary between metallized (electrically shorted) and unmetallized (electrically open) regions on the surface of potassium niobate crystals. Potassium niobate is a very strong piezoelectric material and has the interesting property that only one type of SAW, namely a Rayleigh wave, can exist on unmetallized surface, where as two types of SAWs, namely Rayleigh and Bleustein-Gulyaev (BG), can exist on a metallized surface. Analysis shows that the Rayleigh wave propagates through the interface with very little change in amplitude or polarization. On the other hand, almost total reflection of the BG wave is expected. Details of the theoretical analysis and calculated results will be presented.     

Development of an In Situ Evaporation System for the Preconcentration of Anionic Impurities in High Purity Water

A simple, inexpensive dual vessel evaporating system has been developed to avoid contamination that may arise from the laboratory environment. A 200-fold preconcentration was achieved by the evaporation of 100 mL Milli-Q water on a water bath for 6 h and subsequent analysis was carried out by ion chromatography (IC). The detection limits achieved were 1, 2 and 11 ng L^?1 for fluoride, chloride, and nitrate, respectively. Accuracy, based on spiked recovery data, was 93–103% and precision, in terms of relative standard deviation on five replicates, ranged from 4 to 7%.     

Solid-phase synthesis of tertiary-amino linked benzamides: a versatile method for forming C-N bonds with electron-rich and electron-poor anilines

There currently are a wide variety of methods for forming C-N bonds on solid support. Two preferred methods are reductive aminations with resin bound amines or aldehydes as well as standard alkylation strategies. We herein disclose the scope and application of the Mitsunobu reaction of 2,4-dinitro-N-phenylbenzenesulfonamides derived from both electron-rich and electron-poor anilines as a practical and versatile addition to the repertoire of solid phase C-N bond forming reactions.     

Evaluation of co-polyaniline nanocomposite thin films as humidity sensor

Spin coated films of Co-Polyaniline nanocomposite are evaluated for their transmission properties using He-Ne laser for humidity sensing. The thickness (17-29 microm) of the films is varied by multiple deposition of Co-Polyaniline nanocomposite on a glass substrate. The samples exhibit typically two to three regions in their sensitivity curve when tested in the relative humidity (RH) range of 20-95%. The sensitivity ranges from 0.1 mV/%RH to 12.26 mV/%RH for lower to higher thickness. The sensors show quick response of 8s (20-95%RH), and a recovery time of 1 min (95-20%RH) with good repeatability, reproducibility and low hysteresis effect. The sensitivity of the sensor increases with humidity and thickness. Material characterization is done by X-ray diffraction (XRD), scanning electron micrograph (SEM) and Fourier transform infra-red spectroscopy (FTIR).     

On Bipartite and Multipartite Clique Problems

In this paper, we introduce the maximum edge biclique problem in bipartite graphs and the edge/node weighted multipartite clique problem in multipartite graphs. Our motivation for studying these problems came from abstractions of real manufacturing problems in the computer industry and from formal concept analysis. We show that the weighted version and four variants of the unweighted version of the biclique problem are NP-complete. For random bipartite graphs, we show that the size of the maximum balanced biclique is considerably smaller than the size of the maximum edge cardinality biclique, thus highlighting the difference between the two problems. For multipartite graphs, we consider three versions each for the edge and node weighted problems which differ in the structure of the multipartite clique (MPC) required. We show that all the edge weighted versions are NP-complete in general. We also provide a special case in which edge weighted versions are polynomially solvable.     

Composition dependent model for the prediction of syngas ash deposition in turbine gas hotpath

An improved physical model to predict flyash deposition is developed and discussed in this paper. This model differs from its predecessor ( [Rozati et al., in press] and [Sreedharan and Tafti, 2009] by accounting for deposition of syngas ash particles below the ash softening temperature. The modified deposition model is based on the critical viscosity approach. To test this model, deposition of ash particles impacted on a flat, 45° wedge shape geometry is computed and the results obtained from the numerical model are compared to Crosby et al. (2007). Large Eddy Simulation (LES) is used to model the flow field and flyash particles are modeled using a discrete Lagrangian framework. Results quantify deposition for 4 μm particles of various ash composition samples. Most of the deposition occurs at the stagnation region of the target plate. At 1456 K, out of all the ash samples considered in this study, WY and ND ash sample show the highest capture efficiency (15%) and KL1 ash sample exhibits the lowest capture efficiency (0.02%). In general, capture efficiencies for all ash samples followed an exponential trend with temperature. Additionally, this model is also compared to results obtained from the flat plate deposition experiments conducted here at Virginia Tech using PVC particles (Wood et al., 2010). In the case of PVC particles, the sticking probability in the deposition model assumed an exponential increase in deposition rate with temperature and was calibrated with one experimental data point. The results obtained from this model for PVC particles showed excellent agreement with the experimental measurements over a range of temperatures.     

Application of ring-rearrangement metathesis in organic synthesis: A grand design

In this report, we compiled various strategies involving a ring-rearrangement metathesis as a key step to assemble diverse molecules. Popular name reactions such as Grignard reaction, Overman rearrangement, Fischer indolization, Beckmann rearrangement and Diels–Alder reaction were used in combination with ring-rearrangement metathesis to construct complex targets. Additionally, CH activation and RRM strategy has been used to assemble azacycles. In some instances, the ring-rearrangement metathesis was expected to occur; however, ring-opening metathesis products were realized. These methods were included in the miscellaneous section. We anticipate that the lessons learned here are useful in designing complex polycyclic and heterocyclic targets suitable for biological and material science applications. Beside our work, we have also included others work as a background information.     

Molecular Tailoring Approach for the Estimation of Intramolecular Hydrogen Bond Energy

Hydrogen bonds (HBs) play a crucial role in many physicochemical and biological processes. Theoretical methods can reliably estimate the intermolecular HB energies. However, the methods for the quantification of intramolecular HB (IHB) energy available in the literature are mostly empirical or indirect and limited only to evaluating the energy of a single HB. During the past decade, the authors have developed a direct procedure for the IHB energy estimation based on the molecular tailoring approach (MTA), a fragmentation method. This MTA-based method can yield a reliable estimate of individual IHB energy in a system containing multiple H-bonds. After explaining and illustrating the methodology of MTA, we present its use for the IHB energy estimation in molecules and clusters. We also discuss the use of this method by other researchers as a standard, state-of-the-art method for estimating IHB energy as well as those of other noncovalent interactions.     

Semi-analytical solution for a system with clearance nonlinearity and periodic excitation

Many dynamical systems such as gears, tire-pavement, automotive brakes, and cam-follower have clearance nonlinearity and excitation, which are periodic in nature. It is essential to accurately predict the steady-state response of these systems using contact-mechanics-based model for understanding their nonlinear dynamic behavior. Among the methods available to theoretically solve the system’s nonlinear governing equation(s), a semi-analytical technique such as the harmonic balance method (HBM) is preferred over numerical approaches for various reasons, including accuracy. An HBM formulation that can predict the fundamental, sub-, and super-harmonic solutions is presented here. As multiple variants of HBM exist in the literature, this work focuses on comparatively evaluating the most appropriate variant for the system under consideration. Since the system has multiple discontinuities in terms of contact stiffness and damping forces, these have to be smoothed precisely to be utilized in the HBM. Hence, a novel smoothing function was proposed and evaluated against other existing smoothing functions in literature based on various criteria. Next, the most applicable HBM variant was selected with reference to steady-state solutions from numerical methods. The predictions from the selected HBM variant were validated against the results furnished in the literature for a similar system. Finally, the nonlinear frequency response of the system with multiple discontinuities was estimated using the selected HBM and found to be in good agreement with numerical results.