Physical properties of aliphatic polycarbonates made from CO2 and epoxides

A homologous series of aliphatic polycarbonates with different side‐chain lengths was synthesized by ring‐opening polymerization of terminal epoxides with CO₂ using zinc adipionate as catalyst [patented process of Empower Materials (formerly PAC Polymers Inc.)]. Additionally, a polycarbonate was made having a cyclohexane unit in its backbone, together with a terpolymer having both cyclohexane and propylene units. After characterization of thermal properties the aliphatic polycarbonates were found to be completely amorphous. Polycarbonates derived from long‐chain epoxides showed a glass‐transition temperature (T_g) below room temperature, whereas polycarbonates derived from cyclohexene oxide showed a T_g of 105°C, the highest yet reported for this class of polymers. The initial decomposition temperature of the polymers in air and nitrogen atmospheres was found to be less than 300°C. The mechanical properties and the dynamic mechanical relaxation behavior of the polymers were also reported. The effect of the chemical structure on the physical properties of aliphatic polycarbonates was discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1163–1176, 2003     

Modelling arsenic(III) adsorption from water by sulfate‐modified iron oxide‐coated sand (SMIOCS)

A medium developed by coating BaSO₄ and Fe on quartz sand known as sulfate‐modified iron oxide‐coated sand (SMIOCS) was evaluated for the removal of arsenic(III) from simulated water with an ionic strength of 0.01 M NaNO₃ during batch studies. The medium was characterised for BET surface area, alkali‐resistance, acid‐resistance and the presence of iron and barium on the coated surface. Two simplified kinetic models, ie active available site (AAS) and chemical reaction rate models, were tested to investigate the adsorption mechanisms. The values of rate constants for both the models were found to decrease with increasing As(III) concentrations in the solute. The inverse relationship of rate constants of the reaction rate model with BET surface area showed that As(III) adsorption on SMIOCS was not due to physisorption but to chemisorption. A study of the effect of solute temperature showed that the adsorption of As(III) on SMIOCS media was due to chemisorption. The results of isothermal studies conducted at different pH values showed that adsorption data satisfied both the Langmuir and the Freundlich isotherm models. The adsorption of As(III) on the medium was pH dependent and maximum removal was observed in the pH range of 7–9. © 2002 Society of Chemical Industry     

Development of a mushroom-whey soup powder

Summary Mushroom‐whey soup powder was prepared by cooking mushroom with concentrated cheese whey and blending. The seasonings (onion, garlic and ginger) were fried separately in hydrogenated fat, and cornflour was added if thickening was desirable. After the addition of salt and a further quantity of concentrated whey, the soup mix was again blended. It was then spray‐dried to produce a mushroom‐whey soup powder. The physico‐chemical properties of the soup powder, such as moisture content, loose and packed bulk density, wettability, insolubility index, thiobarbituric acid and hydroxy methyl furfural content, increased during storage. However, dispersibility and reflectance value decreased during storage. The soup powder reconstituted well when boiled in water for 2 min. The reconstituted soup was considered acceptable, with an overall acceptability score of 7.1 on a nine‐point hedonic scale, after 8 months of storage of the soup powder at 30 °C when packed in metalized polyester.     

Estimation of Soil Erosion for a Himalayan Watershed Using GIS Technique

The fragile ecosystem of the Himalayas has been an increasing cause of concern to environmentalists and water resources planners. The steep slopes in the Himalayas along with depletedforest cover, as well as high seismicity have been major factors in soil erosion and sedimentation in river reaches. Prediction ofsoil erosion is a necessity if adequate provision is to be madein the design of conservation structures to offset the ill effects of sedimentation during their lifetime.In the present study, two different soil erosion models, i.e. theMorgan model and Universal Soil Loss Equation (USLE) model, have been used to estimate soil erosion from a Himalayan watershed.Parameters required for both models were generated using remotesensing and ancillary data in GIS mode. The soil erosion estimated by Morgan model is in the order of 2200 t km^-2 yr^-1 and is within the limits reported for this region.The soil erosion estimated by USLE gives a higher rate. Therefore, for the present study the Morgan model gives, for area located in hilly terrain, fairly good results.     

A graphical interpretation of dependency structures in relational data bases

The designer of a relational data base must use dependency structures of data to model semantic situations that arise in data. He must further ensure that these dependencies are not violated during operations on the data base. In this paper we study a subclass of dependencies, namely, root-dependencies and introduce a common graphical picture (S-diagram) for all of them. This effort offers a possible application of graph theory to the study of relational data bases. The S-diagram offers a pictorial insight to all the root-dependencies. We also discuss, briefly, other possible uses of our work such as automatic constraint checking and recovery of data in a damaged data base.     

Nachweis von ω-Aminocarbonsäuren und Carbonylverbindungen in thermooxidativ abgebautem Polycaprolactam

After oxidation and subsequent hydrolysis homologous series of alkyl amines and ω-amino carboxylic acids were proved to be further degradation products of polycaprolactam. The formation of these substances cannot be explained by an attack on the N-vicinal methylene group which is the most reactive site of this polymer. Considering the low and nearly equal amount of nitrogen containing degradation products a statistical attack on the remaining methylene groups takes place besides the preferred N-vicinal reaction. The CO-vicinal site is not particularly activated. The formation of likewise isolated substances with carbonyl groups cannot be explained by a uniform mechanism.     

Mesoporous (Cr)MCM-41 and (Cr)MCM-48 Molecular Sieves: Promising Heterogeneous Catalysts for Liquid Phase Oxidation Reactions

Chromium-containing mesoporous MCM-41 and MCM-48 silicate molecular sieves were synthesized and characterized. Unlike the chromium-containing microporous materials, the mesoporous analogues show significant activity for the chosen (ethylbenzene oxidation) reaction even after several recycling or washing treatments.     

Fabrication and characterization of tungsten and graphite based PFC for divertor target elements of ITER like tokamak application

The development of the fabrication technology of macro-brush configuration of tungsten (W) and carbon (graphite and CFC) plasma facing components (PFCs) for ITER like tokamak application is presented. The fabrication of qualified joint of PFC is a requirement for fusion tokamak. Vacuum brazing method has been employed for joining of W/CuCrZr and C/CuCrZr. Oxygen free high conductivity (OFHC) copper casting on W tiles was performed followed by machining, polishing and ultrasonic cleaning of the samples prior to vacuum brazing. The W/CuCrZr and graphite/CuCrZr based test mockups were vacuum brazed using silver free alloys. The mechanical shear and tensile strengths were evaluated for the W/CuCrZr and graphite/CuCrZr brazed joint samples. The micro-structural examination of the joints showed smooth interface. The details of fabrication and characterization procedure for macro-brush tungsten and carbon based PFC test mockups are presented.     

Healthcare Data Encryption Technique Using Hybrid Cellular Automata in IoT Networks

Wireless Personal Communications - In this article, we secure the healthcare data using low complexity hybrid cellular automata (CA) algorithm while enabling remote monitoring of patients using IoT...