Effect of High-Pressure Processing on Physical, Biochemical, and Microbiological Characteristics of Black Tiger Shrimp (Penaeus monodon)

The effect of high-pressure processing on quality and shelf life of black tiger shrimp was studied. Shrimp was high-pressure processed at selected pressure levels of 100, 270, and 435 MPa for 5 min at room temperature (25?±?2 °C). Changes in physical, biochemical, and microbiological characteristics after processing and during subsequent chilled storage were examined for 35 days. After processing significant (P?<?0.05) increase in moisture content and parallel reduction in protein content was observed. No significant changes were observed in TVB-N and TMA-N levels of shrimp after processing; however, these significantly increased with storage. Whiteness index increased with pressure intensity imparting brighter and mildly cooked appearance. Pressure-induced hardening effect was observed, which showed decreasing trend during storage. The treated samples maintained lower viable counts throughout the storage, thus having better microbial quality than untreated sample. Shelf life was extended to 15 days in shrimp treated at 435 MPa compared with 5 days in untreated sample. Pressure treatment of 435 MPa was found to be most effective in preserving the quality and extending the shelf life of black tiger shrimp.     

Carboxymethyl guar: Its synthesis and macromolecular characterization

Guar gum was partially carboxymethylated by the reaction of the base polysaccharide with the sodium salt of monochloroacetic acid in presence of sodium hydroxide. The resulting products (carboxymethyl guar with different degrees of substitution) were characterized by a variety of material characterization techniques, such as intrinsic viscosity measurement, determination of molecular weight, elemental analysis, thermal analysis, ¹³C‐NMR spectra, and Fourier transform infrared analysis. Various grades of carboxymethyl guar gum, which were synthesized in the laboratory, were studied for their suitability as flocculants and viscosifiers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Review and comparative evaluation of symbolic dynamic filtering for detection of anomaly patterns

Symbolic dynamic filtering (SDF) has been recently reported in literature as a pattern recognition tool for early detection of anomalies (i.e., deviations from the nominal behavior) in complex dynamical systems. This paper presents a review of SDF and its performance evaluation relative to other classes of pattern recognition tools, such as Bayesian Filters and Artificial Neural Networks, from the perspectives of: (i) anomaly detection capability, (ii) decision making for failure mitigation and (iii) computational efficiency. The evaluation is based on analysis of time series data generated from a nonlinear active electronic system. This work has been supported in part by the U.S. Army Research Laboratory and the U.S. Army Research Office under Grant No. W911NF-07-1-0376, by the U.S. Office of Naval Research under Grant No. N00014-08-1-380, and by NASA under Cooperative Agreement No. NNX07AK49A.     

Optimal Weld Parameters, Weld Microstructure, Mechanical Properties, and Hydrogen Absorption: An Effective Analysis

Weld bead-in-grooves were deposited on low alloy, high strength steel plates (ASTM A 517 Grade “F”) with a commercial flux-cored filler wire, Auto-MIG 420, at different welding conditions. Microstructure and mechanical properties of welds were characterized by means of optical microscopy, SEM, TEM, EPMA, microhardness measurements, tensile tests, and Charpy impact tests. Hydrogen content of weld metals in as-weld condition and after exposing in simulated service condition was measured by LECO Gas Analyzer. Microstructure of weld metals consisted primarily of lath martensite with small amount of M-A constituents (Martensite-Austenite alternating layers). For some particular welding conditions, such as higher heat input and lower preheat temperatures etc., acicular ferrite is observed with lath martensite. Welds consisting of acicular ferrite in the microstructure showed improved mechanical properties as well as lower hydrogen absorption. The study provides guidelines for selecting proper welding conditions, which results in lower propensity to absorb hydrogen during service, as well as better mechanical properties. Necessity of post-weld heat treatment processes, which is mainly performed to achieve toughness, may be reduced; consequently saving cost and time of the welding process.     

Electronic states of organic semiconductors vis-à-vis interactions between molecules in a submonolayer through time-restricted electrostatic assembly

We have made in-depth studies to revisit time-restricted layer-by-layer (LbL) electrostatic assembly process of a couple of organic molecules. The studies have been made in relation to electronic states of metal phthalocyanines. We show that by shortening dipping time for adsorption of the active molecules, mass adsorbed in each monolayer can be decreased and hence intermolecular spacing between the molecules can be increased. We have characterized the (sub)monolayers deposited on an electrode with scanning tunneling microscope tip to record tunneling current through the molecules. Results show that the highest occupied molecular orbitals and lowest unoccupied molecular orbitals, and also the difference between the orbitals, that is, the transport gap of the molecules in a (sub)monolayer depends on the dipping time of LbL assembly or molecule-to-molecule separation. We show that interactions between molecules in a monolayer decrease the transport gap of the metal phthalocyanines.     

Relationship between normal load and dynamic co-efficient of friction on rock-rubber wear mechanism

In this study, rubber compounds were produced in varying proportions of carboxylated acrylonitrile butadiene rubber (XNBR) and natural rubber (NR) and the parameters such as cure characteristics, wear behavior against various surfaces at different normal loads, and frictional works were tested. The tensile strength and dynamic co-efficient of friction of sample containing 80 wt.% of XNBR was high compared to other samples by 2% and 10% respectively. The results of XNBR and NR vulcanizates under normal pressure ranging from 43 to 118 kPa were reported. Based on these results the relationship between normal load and dynamic co-efficient of friction has been proposed. It was also observed that sample containing 80 wt.% of XNBR exhibits lesser volume loss than compared to other samples.     

Progressive cutting tool wear detection from machined surface images using Voronoi tessellation method

Tool condition monitoring by machine vision approach has been gaining popularity day by day since it is a low cost and flexible method. In this paper, a tool condition monitoring technique by analysing turned surface images has been presented. The aim of this work is to apply an image texture analysis technique on turned surface images for quantitative assessment of cutting tool flank wear, progressively. A novel method by the concept of Voronoi tessellation has been applied in this study to analyse the surface texture of machined surface after the creation of Voronoi diagram. Two texture features, namely, number of polygons with zero cross moment and total void area of Voronoi diagram of machined surface images have been extracted. A correlation study between measured flank wear and extracted texture features has been done for depicting the tool flank wear. It has been found that number of polygons with zero cross moment has better linear relationship with tool flank wear than that of total void area.     

Immobilization and the conformational study of phospholipid and phospholipid-protein vesicles

The present work demonstrates the immobilization of phospholipids and phospholipids-protein vesicles on solid substrate by simple drop-cast technique. We have also studied the structural and conformational transition of protein (OVA) molecules when they are loaded in immobilized vesicles of DPPC. High-resolution FE-SEM imaging is used to study the structural aspects of the immobilized vesicles of DPPC and OVA loaded DPPC. FTIR analyses of amide bands are being used to inspect the extent of the conformational transitions of β-sheet to α-helix of OVA in immobilized DPPC vesicles. Immobilized OVA-DPPC vesicles provide the structure of individual OVA molecule attached with DPPC, without aggregation amongst them.     

Revisiting Stress Corrosion Cracking of Steel in Caustic Solutions for Developing Cracking Susceptibility Diagrams for Improved Applicability

Stress corrosion cracking tests were conducted using Bayer solutions of different chemistry at different temperatures for extraction of alumina from bauxite ores. The validity of the commonly used caustic cracking susceptibility (CS) diagram for steels exposed to plain caustic solutions was assessed by testing the notched and precracked specimens. This study presents first results toward the development of a model susceptibility diagram for actual Bayer solutions, and for improved applicability of the traditional plain caustic diagram. For mechanistic understanding of caustic cracking, tests were also carried out under imposed electrochemical conditions.