Resistivity and temperature coefficient of resistivity of tin films

The electrical resistivity and the temperature coefficient of resistivity of tin films (490 to 5000 Å) deposited onto glass substrates at room temperature (30° C) were measured in situ in the temperature range 30 to 150° C. It is concluded that Mayadas-Shatzkes theory reproduces the experimental observations more faithfully than Fuchs-Sondheimer's theory.     

Hierarchical vectorization of electrical drawings in document images by connectivity analysis of symbols and super-components

A novel integrated technique is proposed for hierarchical vectorization of electrical drawings in document images. Its first step includes recognition of different electrical symbols and their interconnections based on morphological operations and geometric analysis in three well-distinguished subspaces. This is followed by a hierarchical analysis for detecting the (series-or parallel-connected) super-components in an iterative manner. Finally a compact collection of circuit adjacency lists is produced, which are reduced further by binary encoding. Reconstruction algorithm has also been explained to merit the overall efficacy of the vectorization. Experimental results have been furnished to demonstrate its efficiency and robustness.     

A reliable technique to determine the local mechanical properties at the nanoscale for cementitious materials

A Hysitron Triboindenter has been used to determine the mechanical properties of hardened cement paste and cement paste at the early age. This technique provides an in-situ scanning probe microscopy (SPM) imaging facility that allows pre and post-test observation of the sample. The same probe is used to indent and image eliminating the complicated situation of locating the same area with different instruments or coupling two different instruments, such as a SEM and a nanoindenter to work together. This paper presents preliminary results of experiments performed on hardened cement paste and cement paste at the early age.     

Model reduction and controller design for a nonlinear heat conduction problem using finite element method

The mathematical models for dynamic distributed parameter systems are given by systems of partial differential equations. With nonlinear material properties, the corresponding finite element (FE) models are large systems of nonlinear ordinary differential equations. However, in most cases, the actual dynamics of interest involve only a few of the variables, for which model reduction strategies based on system theoretical concepts can be immensely useful. This paper considers the problem of controlling a three dimensional profile on nontrivial geometries. Dynamic model is obtained by discretizing the domain using FE method. A nonlinear control law is proposed which transfers any arbitrary initial temperature profile to another arbitrary desired one. The large dynamic model is reduced using proper orthogonal decomposition (POD). Finally, the stability of the control law is proved through Lyapunov analysis. Results of numerical implementation are presented and possible further extensions are identified.     

Reducing the Computational Effort for Performing Linear Optimization in the Lower-Bound Finite Elements Limit Analysis

This study describes a technique for reducing the computational effort for performing linear optimization while solving any geotechnical stability problem with the use of the lower bound finite-element limit analysis. In the proposed method, a lower order polygon is initially used to model the Mohr-Coulomb yield function; the order of the polygon refers to its total number of sides. The initial solution is used to identify the governing side of the yield polygon that lies nearest to the point defining the existing stress state. Subsequently, this governing side of the linearized yield polygon is replaced with a number of the relevant sides of the higher order polygon. Because all the sides of the higher order polygon for imposing the linearized yield constraints do not enter the formulation, the associated computational effort becomes much smaller. With the proposed algorithm, the collapse loads were determined for smooth and rough strip footing, and the computational results were found to be quite convincing.     

Gastrointestinal delivery of glipizide from carboxymethyl locust bean gum–Al3+–alginate hydrogel network: In vitro and in vivo performance

Sodium alginate and carboxymethyl locust bean gum (CMLBG) were reticulated in an aqueous solution of AlCl₃, and this novel interpenetrating network (IPN) hydrogel encapsulated about 93–98% glipizide. The degree of reticulation in the spherical IPN beads was confirmed by Fourier transform infrared spectroscopy, elemental analysis, neutralization equivalent determination, tensile strength testing, and differential scanning calorimetry analysis. An increase in the CMLBG weight ratio and the degree of crosslinking in the IPN was found to increase mean dissolution time of the encapsulated drug. The dissolution efficiency was found to be much higher in the medium at pH 7.4 than at pH 1.2. The swelling of IPN depended on the pH of the medium, and accordingly, monitored the drug release for a period of 8 h. The anomalous drug transport mechanism was presumed to be operative. High performance liquid chromatography (HPLC) analysis showed the drug's stability in the IPN during encapsulation. The IPN showed significant hypoglycemic activity on male Wistar rats for up to 10 h. This could be beneficial for diabetic patients for achieving control over blood glucose levels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

An Efficient Recyclable Polymer Supported Copper(II) Catalyst for C–N Bond Formation by <Emphasis Type=Italic>N</Emphasis>-Arylation

Abstract  

Polymer supported Cu(II) catalyst was prepared, characterized and employed for the N-arylation and amination reaction of N–H heterocycles with aryl halides as well as arylboronic acids to afford the corresponding coupled products in good to excellent yields. This catalyst can be used several times with consistent catalytic activity.     

Efficient liquid phase oxidation of olefins and aromatic alcohol catalyzed by reusable polymer anchored Schiff base complexes

BACKGROUND: Heterogenization of homogeneous catalyst has become an interesting process for the catalytic oxidation of olefins and aromatic alcohol. This may provide a new kind of catalyst that is not only friendly to the environment but also exhibits higher thermal and chemical stabilities. RESULTS: Polymer anchored Schiff‐base complexes of iron(III), copper(II) and cobalt(II) have been synthesized and characterized. The catalytic potential of these complexes has been tested for the oxidation of cyclohexene. The effect of varying solvent, oxidant, substrate oxidant molar ratio, temperature and catalyst amount has been studied. Under optimized reaction conditions 91, 88 and 81% conversion of cyclohexene was obtained with Fe(III), Cu(II) and Co(II) catalysts, respectively. Moreover, the oxidation of other substrates, such as styrene, benzylalcohol, toluene and 1‐hexene were also efficiently carried out by these catalysts. CONCLUSION: The immobilized complexes showed excellent catalytic activity along with high selectivity for the oxidation of olefins and alcohols. The catalysts can be recycled more than five times without any noticeable loss of catalytic activity. Copyright © 2009 Society of Chemical Industry