Effect of mastication on molecular weight and molecular weight distribution of EPDM polymer and SBR

EPDM and SBR were masticated on an open mill. The temperature range of mastication for EPDM was 68–480°F. SBR was milled at 170–200°F. The gel-permeation chromatography analyses were made on the masticated samples. For EPDM at 68°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is nonrandom. At constant mastication time between 182 and 315°F, there is little change in molecular weight. Mastication for 18 min at 480°F broadens the molecular weight distribution; the degradation is random. For SBR at 170–200°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is also nonrandom. Nonrandom degradation for both EPDM and SBR results in a narrowing of the molecular weight distribution, without build-up of low molecular weight molecules, and without a shift in the peak molecular weight. This is contrary to nonrandom degradation of natural rubber where a shift in the peak molecular weight occurs with mastication time.     

Natural plant enzyme inhibitors. Isolation and characterisation of two α-amylase inhibitors from Colocasia antiquorum tubers

Two α-amylase inhibitors I-1 and I-2, were purified to homogeneity from Colocasia antiquorum tubers by extraction with 0.02m phosphate buffer pH 7.6, treatment with diethyl amino ethyl-cellulose, ammonium sulphate fractionation, chromatography on Sephadex G-50 and chromatography on phenyl sepharose CL-4B. Both the inhibitors were basic proteins. I-1 alone contained carbohydrates to the extent of 5.4%. The molecular weights of I-1 and I-2 were found to be about 14 300 and 12 500, respectively, by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The inhibitors inactivated human salivary, human pancreatic and hog pancreatic amylases but they had no action on Bacillus subtilis and Aspergillus oryzae amylases and resisted attack by pepsin, trypsin, chymotrypsin and pronase. Chemical modification of amino groups and guanidino groups of I-1 and I-2 resulted in loss of inhibitory activities. Formation of enzyme inhibitor complexes between hog pancreatic amylase, I-1 and I-2 were demonstrated by gel chromatography on Sephadex G-100. Total amylase inhibitory activity in Colocasia tubers decreased gradually during plant growth.     

An alternate form of the ramberg-osgood formula for matrix displacement analysis

A new stress-strain law, which is a three parameter representation of stress in terms of strain has been proposed for the matrix displacement analysis of structures made of non-hookean materials. This formula has been utilized to study three typical problems. These studies brought out the effectiveness and suitability of this law for matrix displacement analysis.     

Process Intensification of Biodiesel Production Using a Tubular Micro-Reactor (TMR): Experimental and Numerical Assessment

The aim of this paper is to present an alternative to conventional biodiesel production by taking advantage of the flow patterns formed in micro-reactors. Biodiesel production was carried out 15 times faster in a tubular micro-reactor (TMR) than a well-mixed batch reactor (BR), achieving conversions up to ～99% with 4?min of residence time. The experimental results were analyzed using dimensionless numbers and computational fluid dynamics (CFD) simulations. The CFD results showed that under the conditions used in the present study, the slug flow pattern can be expected, and this could explain the high conversion (>90%) reached in the TMR without using high methanol-oil molar ratios. The internal movement (auto-mixing) in the slug enhanced the mass transfer. Moreover, CFD simulations showed that at low conversion (<25%), the internal velocity of the oil slug will be the key factor related to the reactor performance.     

Preparation,Characterization and Assessment of the Novel Gelatin–tamarind Gum/Carboxymethyl Tamarind Gum-Based Phase-Separated Films for Skin Tissue Engineering Applications

The current study delineates the development of novel gelatin–tamarind gum/carboxymethyl tamarind gum-based phase-separated films for probable skin tissue engineering applications. Polyethylene glycol was used as plasticizer. The films were characterized thoroughly using mechanical tester and impedance analyzer. Cell proliferation ability and drug release properties of the films were investigated. Mechanical studies indicated composition-dependent stress relaxation properties. Polysaccharide containing films supported better proliferation of human keratinocytes as compared to control. Drug-loaded films showed good antimicrobial properties against Escherichia coli. Analysis of the results indicated that the prepared films may be tried as matrices for skin tissue engineering.     

Isolation and identification of the causative factors responsible for color fixation in rice bran oil

To understand the chemical nature of the dark coloring constituents responsible for color fixation in rice bran oil, crude and dewaxed rice bran oils of 6.8% free fatty acids were fractionated on a silica gel column to get a dark-colored material (0.57% of the oil). Thin-layer chromatographic analysis of the material showed a spot corresponding to monoglycerides, but there were no spots corresponding to other glycerides. It contained traces of phosphorus (<0.1 ppm, which is equivalent to 2.5 ppm phospholipids) and iron (1.3 ppm) that could not be attributed to phospholipids or to any iron-complex. Upon saponification it yielded 12% nonsaponifiable matter. Gas-liquid chromatographic analysis of the saponifiable matter (after acidification and methylation of fatty acids) showed the presence of palamitic, oleic and linoleic acids. Further, on the basis of comparison with spectroscopic data of synthetic monoglyceride, the constituent was characterized to be a mixture of monoglycerides with side chains of oxidized unsaturated fatty acids.     

Preparation and Pretreatment Temperature Influence on Iron Species Distribution and N2O Decomposition in Fe–ZSM-5

Fe–ZSM-5 catalysts are prepared by FeCl₃ sublimation between 320 and 850 °C. The catalysts are characterised by XRD, H₂–TPR, NH₃–TPD, NO adsorption by DRIFTs, and catalytic activity is evaluated for N₂O decomposition. The influence of high temperature (850 °C) and pretreatment environment (air, He, He+H₂O and H₂) on the nature of iron species in Fe–ZSM-5 is further investigated by DRIFTs. High temperature FeCl₃ sublimation results in decreased FeO_x formation, easily reducible and narrow distribution of iron species in close proximity to alumina in Fe–ZSM-5. High temperature FeCl₃ sublimation or pretreatment results in isolated hydroxylated iron species, –Fe(OH)₂, which are not significant in Fe–ZSM-5 prepared by 320 °C FeCl₃ sublimation followed by calcination below 600 °C. Fe–ZSM-5 prepared by high temperature FeCl₃ sublimation show high N₂O decomposition activity and the improved performance can be correlated to –Fe(OH)₂ species in close proximity to alumina.     

Potential rare-earth modified CeO2 catalysts for soot oxidation part II: Characterisation and catalytic activity with NO + O2

Ceria (CeO₂) and rare-earth modified ceria (CeReO_x with Re = La³⁺, Pr^3+/4+, Sm³⁺, Y³⁺) supports and Pt impregnated supports are studied for the soot oxidation under a loose contact with the catalyst with the feed gas, containing NO + O₂. The catalysts are characterised by XRD, H₂-TPR, DRIFT and Raman spectroscopy. Among the single component oxides, CeO₂ is significantly more active compared with the other lanthanide oxides used in this study. Doping CeO₂ with Pr^3+/4+ and La³⁺ improved, however, the soot oxidation activity of the resulting solid solutions. This improvement is correlated with the surface area in the case of CeLaO_x and to the surface area and redox properties of CePrO_x catalyst. The NO conversion to NO₂ over these catalysts is responsible for the soot oxidation activity. If the activity per unit surface area is compared CePrO_x is the most active one. This indicates that though La³⁺ can stabilise the surface area of the catalyst in fact it decreases the soot oxidation activity of Ce⁴⁺. The lattice oxygen participates in NO conversion to NO₂ and the rate of this lattice oxygen transfer is much faster on CePrO_x. In general, the improvement of the soot oxidation is observed over the Pt impregnated CeO₂ and CeReO_x catalysts, and can be correlated to the presence of Pt°. The surface reduction of the supports in the presence of Pt occurred below 100 °C. The surface redox properties of the support in the Pt catalysts do not have a significant role in the NO to NO₂ conversion. In spite of the lower surface area, the Pt/CeYO_x and Pt/CeO₂ catalysts are found to be more active due to larger Pt crystal sizes. The presence of Pt also improved the CO conversion to CO₂ over these catalysts. The activation energy for the soot oxidation with NO + O₂ is found to be around 50 kJ/mol.     

Solution and solid‐state blend compatibility of poly(vinyl alcohol) and poly(methyl methacrylate)

The blend miscibility of poly(vinyl alcohol) and poly(methyl methacrylate) in N,N′‐dimethylformamide solution was investigated by viscosity, density, ultrasonic velocity, refractive index, and UV and fluorescence spectra studies. Differential scanning calorimetry and scanning electron microscopy were used to confirm the blend miscibility in the solid state. Blends were compatible when the concentration of poly(vinyl alcohol) was greater than 60 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2415–2421, 2006     

ZBFR: zone based failure recovery in WSNs by utilizing mobility and coverage overlapping

Wireless sensor networks are more prone to failures as compared to other traditional networks. The frequent faults and failures sometime create large holes causing loss of sensing and connectivity coverage in the network. In present work, a zone based failure detection and recovery scheme is presented to reliably handle such node failures. We first propose a consensus and agreement based approach to elect a suitable monitor node called as zone monitor (ZM). ZM is responsible for coordinating failure recovery activities and maintaining desired coverage within a zone. In order to overcome failure overhead due to false failure detection, a consensus is carried out amongst neighboring nodes of a suspicious node to confirm the correct status with high accuracy. On confirmation of a node failure, the impact of resulting hole on coverage is analyzed and if impact exceeds beyond a particular threshold, a recovery process is initiated. The recovery process utilizes backup nodes having overlapping sensing coverage with failed node and may also relocate some nodes. Firstly a backup node is probed and activated if available. If no backup node is found, the solution strives to recover coverage jointly by recursively relocating some mobile nodes and probing backup nodes. The proposed scheme is analyzed and validated through NS-2 based simulation experiments.