Grinding-induced rapid,convenient and solvent free approach for the one pot synthesis of α-aminophosphonates using aluminium pillared interlayered clay catalyst

An easy to prepare aluminium pillared interlayered clay (PILC) has been developed as a stable, recyclable and heterogeneous catalyst to promote the one-pot three component synthesis of α-aminophosphonates under solvent-free conditions using grindstone chemistry. Utilization of mild reaction conditions, clean conversion and greater selectivity under grinding conditions along with effortless separation, and purification of reaction products make this process extra attractive.     

FUEL ETHANOL PRODUCTION FROM AGRICULTURAL L1GNOCELLULOSIC FEEDSTOCKS - A REVIEW

ABSTRACT

Over the past three decades significant efforts have been made towards the conservation of fossil-based fuels and the exploration and exploitation of new renewable sources. The focus primarily has been on the outlook for alternatives to the petroleum products. In this spectrum alcohol manufacture from biomass has attracted a large attention all over the world which could be used as an alternative source to petrol or in blends with petrol

The National Research Council (NRC) has substantially emphasized on the reduction of CO₂ emissions and the other so-called green house gases. The NRC committee also recommends better evaluations of the processes for converting the biomass / lignocellulosic wastes to ethanol that will lessen the U.S. dependence on foreign oil. Among the factors behind the move to bio-based materials are the environmental concerns, the availability of abundant, renewable agricultural and forest resources that are both inexpensive and under-utilized.     

Starch‐based biocomposite films reinforced with cellulose nanocrystals from garlic stalks

The study was conducted to reinforce starch‐based biocomposite films using cellulose nanocrystals (CNCs) from garlic stalks. An average yield of 4.6% by mass based from air‐dried garlic stalks was obtained through alkali delignification, acid hydrolysis and sonication. The isolated CNCs are spherical and have an average diameter of 35 nm and crystallinity of 62%. Fourier transform infrared spectra correspond to the structure of cellulose, but some absorption bands corresponding to hemicelluloses were also noticed. Starch‐based biocomposite films with varying amount of the isolated CNCs as reinforcing filler were prepared by solution casting and evaporation method. Scanning electron micrographs of the films showed homogeneous dispersion of CNC in the starch matrix. Improvement in tensile strength and modulus was at maximum when the starch to CNC ratio is 100:5. The thermal stability of the films, on the other hand, decreased with the addition of CNC. Finally, CNC‐reinforced films had lower moisture uptake than nonreinforced films. POLYM. COMPOS. 34:1325–1332, 2013. © 2013 Society of Plastics Engineers     

Silicon field effect transistors as dual-use sensor-heater hybrids

We demonstrate the temperature mediated applications of a previously proposed novel localized dielectric heating method on the surface of dual purpose silicon field effect transistor (FET) sensor-heaters and perform modeling and characterization of the underlying mechanisms. The FETs are first shown to operate as electrical sensors via sensitivity to changes in pH in ionic fluids. The same devices are then demonstrated as highly localized heaters via investigation of experimental heating profiles and comparison to simulation results. These results offer further insight into the heating mechanism and help determine the spatial resolution of the technique. Two important biosensor platform applications spanning different temperature ranges are then demonstrated: a localized heat-mediated DNA exchange reaction and a method for dense selective functionalization of probe molecules via the heat catalyzed complete desorption and reattachment of chemical functionalization to the transistor surfaces. Our results show that the use of silicon transistors can be extended beyond electrical switching and field-effect sensing to performing localized temperature controlled chemical reactions on the transistor itself.     

Electrical resistance measurement methods and electrical characterization of poly(3,4‐ethylenedioxythiophene)‐coated conductive fibers

Textile fibers and yarns of high conductivity, and their integration into wearable textiles for different electronic applications, have become an important research field for many research groups throughout the world. We have produced novel electrically conductive textile yarns by vapor‐phase polymerization (VPP) of a conjugated polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT), on the surface of commercially available textile yarns (viscose). In this article, we have presented a novel setup for electrical resistance measurements, which can be used not only for fibrous structures but also for woven structures of specific dimensions. We have reported a two‐point resistance‐measuring method using an already manufactured setup and also a comparison with the conventionally used method (so‐called crocodile clip method). We found that the electrical properties of PEDOT‐coated viscose fibers strongly depend on the concentration of oxidant (FeCl₃) and the doping (oxidation) process of PEDOT. To evaluate the results, we used mass specific resistance values of PEDOT‐coated viscose yarns instead of normal surface resistance values. The voltage–current (V–I) characteristics support the ohmic behavior of coated fibers to some extent. Monitoring of the charging effect of the flow of current through conductive fibers for prolonged periods of time showed that conductivity remains constant. The change in electrical resistance values with increase in the length of coated fibers was also reported. The resistance‐measuring setup employed could also be used for continuous measurement of resistance in the production of conductive fibers, as well as for four‐point resistance measurement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Optimization of lead removal from aqueous solution by micellar-enhanced ultrafiltration process using Box-Behnken design

The main objective of this research was to use Box-Behnken experimental design (BBD) and response surface methodology (RSM) for optimization of micellar-enhanced ultrafiltration (MEUF) to remove lead ions from synthetic wastewater using spiral-wound ultrafiltration membrane. The critical factors selected for the examination were surfactant concentration, molar ratio of surfactant to metal (S/M) and solution pH. A total of 17 experiments were accomplished towards the construction of a quadratic model for both target variables. The experimental results were fitted with a second-order polynomial equation by a multiple regression analysis, and more than 95%, 93% of the variation could be predicted by the models for lead rejection and permeation flux, respectively. The optimum condition was found by using the obtained mathematical models. Optimization indicated that in C _SDS =2mM, pH=6.57 and S/M= 9.82 maximum flux and rejection efficiency can be achieved, simultaneously.     

Study of single silicon quantum dots' band gap and single-electron charging energies by room temperature scanning tunneling microscopy

Scanning tunneling spectroscopy in the shell-filling regime was carried out at room temperature to investigate the size dependence of the band gap and single-electron charging energy of single Si quantum dots (QDs). The results are compared with model calculation. A 12-fold multiple staircase structure was observed for a QD of about 4.3 nm diameter, reflecting the degeneracy of the first energy level, as expected from theoretical calculations. The systematic broadening of the tunneling spectroscopy peaks with decreasing dot diameter is attributed to the reduced barrier height for smaller dot sizes and to the splitting of the first energy level.     

Modification of bean starch by γ-irradiation: Effect on functional and morphological properties

Starches isolated from Red, White, Yellow and Black Kidney beans were treated by γ-irradiation doses of 5, 10 and 20 kGy. Physicochemical, morphological and pasting properties of irradiated bean starches were investigated. Microscopic observation under scanning electron microscope (SEM) showed that some of the bean starch granules were destroyed by γ-irradiation and the breakage was greater at a higher dose (20 kGy). Physicochemical properties differed significantly and showed strong dose-dependent relationship. Carboxyl content, solubility, water absorption capacity and transmittance increased, whereas swelling power, apparent amylose content, syneresis and pasting properties decreased upon the irradiation of kidney bean starch. Radiation doses were positively correlated with water absorption capacity and solubility index and negatively correlated with swelling index, peak viscosity, trough viscosity, breakdown and final viscosity. There were high positive correlations between pasting properties. X-ray diffraction pattern remained same upon irradiation but a decrease in crystallinity was observed with increasing irradiation dose.     

Impact of irregular geometries on low-k dielectric breakdown

Backend geometries on chips contain a wide variety of features. We are developing a full-chip reliability simulator for low-k dielectric breakdown that takes into account the vulnerable area, linewidth, vias, and line edge roughness. The simulator provides a link between test structure results and predictions of chip dielectric lifetime. However, these factors may not be sufficient for large chips with a wider variety of features. In this paper, we analyze data from backend dielectric test structures with irregular geometries to determine if more layout features need to be added to a full-chip reliability simulator for low-k dielectric breakdown.