Preparation of nanosilica reinforced waterborne silylated polyether adhesive with high shear strength

Waterborne adhesives are extremely environment‐friendly but unfortunately deficient in mechanical properties. In this article, nanosilica, stemming from tetraethyl orthosilicate (TEOS), silica sol, and/or fumed silica powder, was employed to reinforce the waterborne silylated polyether adhesives. Effects of TEOS content, silica sol content, and the type and content of fumed silica on the shear strength of the adhesive were investigated using a scanning electronic microscope and an electronic instron tester and the strengthening mechanisms of different silica source were discussed. All the shear strengths of silylated polyether adhesives first increased and then decreased as TEOS content, silica sol content or fumed silica content increased. Colloidal silica particles was less efficient than fumed silica particles for reinforcing the polyether adhesive but can increase the shear strength of hydrophobic fumed silica embedded adhesive. Comparing the adhesives with the hydrophilic fumed silica (HS‐5) or the extremely hydrophobic fumed silica (TS‐720), the adhesive with moderate hydrophobic fumed silica (TS‐610) had the highest shear strength. The maximal shear strength of 2.5 MPa was achieved when TEOS, silica sol, and fumed silica were combined. It seemed that TEOS, silica sol, and fumed silica played crosslinking (with polyether chain), dispersing (for fumed silica), and reinforcing roles on waterborne adhesive, respectively. This reinforcing mechanism opened a new way to fabricate waterborne adhesives (or coatings) with high performances. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Stearic acid grafted chitosan/epoxy blend surface coating for prolonged protection of mild steel in saline environment

Chitosan (CS) is a promising candidate for green anticorrosive coating owing to its film forming nature, complexation with metals, biocompatibility, and varied surface functionalization. This paper illustrates the surface properties of chitosan film which is modified by grafting with stearic acid via a water-soluble coupling agent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The interaction between chitosan and stearic acid were investigated theoretically by Gaussian 09 package. The purified co polymeric films so formed were characterized by FTIR-ATR, NMR, XRD, TGA, CHNSO, SEM, AFM and EDX techniques. Stearic acid grafted CS film was developed on mild steel surface via dip coating technique and investigated for its corrosion resistance in 3.5% NaCl via electrochemical techniques. EIS measurements and potentiodynamic polarization studies have proven that the grafted CS when blended with epoxy resin offers better corrosion protection to mild steel in saline environment. The coating offers prolonged protection for the metal surface with enhanced barrier properties and hydrophobic nature.     

Magnetic field analysis of induction motor for optimal cooling duct design

It is important to understand the leakage flux distributions to get a better design of induction motors. Computer simulation using the finite element method (FEM) is an important tool for achieving this objective. This paper presents a method for calculating the steady-state leakage flux distributions in induction motors. FEM is used here to study the field behavior of an induction motor in terms of magnetic vector potential (MVP), which allows the easy determination of flux and flux density. Because of complexity of the domain, triangular elements, due to their flexibility to fit in any irregular geometry are used. With the help of MVP distribution obtained use of these elements have been made to study the effect of shape of the cooling duct on the rotor laminations of an induction motor. An optimum modified shape of ventilating hole is thus obtained without having any adverse effect on MVP and flux density.     

Leakage reduction through optimization of regular layout parameters

Regular layouts that follow restrictive design rules are essential to robust CMOS design in order to alleviate many manufacturing induced effects, such as the effect of non-rectangular gate (NRG) due to sub-wavelength lithograph. NRG dramatically increases the leakage current by more than 15X compared to that of ideal physical layout. To mitigate such a penalty, we developed a technique to optimize regular layout through restrictive design rule parameters and to benchmark post-lithography circuit performance. We propose a procedure to systematically optimize key layout parameters in regular layout to minimize the leakage energy with minimal over head to active energy, circuit speed and area. The proposed layout optimization technique is demonstrated with a 65 nm technology and projected for 45 nm and 32 nm technology nodes. Experimental results show that more than 70% reduction in leakage can be achieved with area penalty of ～10% and 9–12% overhead on circuit speed and active energy.     

Antibacterial properties of polypropylene textiles modified by poly(2-(N,N-dimethyloamino ethyl) methacrylate)

Polypropylene nonwoven fabrics samples were modified using poly(2-(N,N-dimethyloamino ethyl) methacrylate) (PDAMA) and silver-containing layers. The structure of the material after modification was confirmed using scanning electron mocroscope, energy-dispersive X-ray spectroscopy, Fourier Transfer Infrared Spectroscopy (FTIR), and electro-kinetic measurements. It was found that samples with external PDAMA layers have excellent activity against Staphylococcus aureus under dynamic contact conditions. In contrast, samples finished with deposited silver showed little antimicrobial effect. Antibacterial tests conducted under static conditions showed no antibacterial activity irrespective of the deposited layers.     

DETERMINATION OF CALCIUM IN A FERMENTATION PROCESS BY PROTON-INDUCED X-RAY EMISSION

□ Proton-induced X-ray emission (PIXE) was used to study submerged fermentation of ethanol from jaggery using Saccharomyces cerevisiae as the organism. The effect of CaCO₃ as a mineral source for the fermentation process was studied and its activity was monitored. A 3 MeV proton beam obtained from a tandem type pelletron accelerator was used for the multielemental analysis to characterize the calcium uptake in fermentation process. Along with the characterization of Ca, K, Fe, Cr, Co, Ni, Cu, and Zn were also identified in this fermentation process, which may be useful to interpret the various metabolic conditions and studying the impact of these elements. The rate of uptake of calcium by the organism was found to be highest at 14 mg/L supplementation, which was contributed to the final ethanol concentration of 57.8 g/L. A maximum uptake rate of 0.304 mg/L/hr was noticed for CaCO₃ at 14 mg/L supplementation. The present work demonstrates the suitability of PIXE for the determination of various elements in fermentation processes.     

Multiple learning parameters differentially regulate olfactory generalization.

Sensory representations depend strongly on the descending regulation of perceptual processing. Generalization among similar stimuli is a fundamental cognitive process that defines the extent of the variance in physical stimulus properties that becomes categorized together and associated with a common contingency, thereby establishing units of meaning. The olfactory system provides an experimentally tractable model system in which to study the interactions of these physical and psychological factors within the framework of their underlying neurophysiological mechanisms. The authors here show that olfactory associative learning systematically regulates gradients of odor generalization. Specifically, increasing odor-reward pairings, odor concentration, or reward quality--each a determinant of associative learning--significantly transformed olfactory generalization gradients, each narrowing the range of variance in odor quality perceived as likely to share the learned contingency of a conditioned odor stimulus. However, differences in the qualitative features of these three transformations suggest that these different determinants of learning are not necessarily theoretically interchangeable. These results demonstrate that odor representations are substantially shaped by experience and descending influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Digital infarction in a hemodialysis patient due to embolism from a thrombosed brachial arteriovenous fistula

Acute onset of digital ischemia and infarction is an unusual complication in patients undergoing hemodialysis. This is a report of a patient on regular hemodialysis who presented with acute distal extremity ischemia, progressing to digital infarction and on evaluation was found to have thrombosis of brachial arteriovenous fistula with embolization to the distal arteries causing digital artery occlusion.