Depolymerization of nylon 6 waste fibers

The depolymerization of nylon 6 was carried out with various solvents, such as formic acid, hydrochloric acid, and sulfuric acid, followed by heating under reflux for different times. From the polymer dissolved and refluxed in formic acid, degradation products with different ranges of molecular weights were collected by fractional precipitation, with small lots of distilled water added as a nonsolvent. The characterization of different fractions was carried out by the measurement of the viscosity‐average molecular weight, the number‐average molecular weight, and the number of amino end groups. The presence of the monomer, aminocaproic acid, was confirmed by thin‐layer chromatography in the case of hydrochloric acid treated nylon 6. With a strongly acidic ion‐exchange resin, the monomer was separated in its purest form, and the melting point was noted. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 186–190, 2006     

Cefuroxime axetil in the treatment of Salmonella typhi infection (enteric fever) in adults

A study to evaluate the efficacy and safety of Cefuroxime Axetil in enteric fever was carried out in 30 adult hospitalised patients of either sex. A positive blood culture for S. typhi and sensitivity to cefuroxime axetil were confirmed prior to treatment. On admission, the baseline signs and symptoms were recorded and treatment initiated with cefuroxime axetil in a dose of 500 mg bd; which was continued for 7 days after normalization of temperature. The various clinical parameters were followed up daily during the treatment period and discharge permitted on normalization of temperature. Blood culture for S. typhi was repeated 3 days after stopping treatment. Follow-up Widal, stool and urine cultures were done wherever possible to check for relapse or carrier state. All the patients responded clinically to treatment and had bacteriologically negative blood cultures by the end of 14 days treatment. 87% of the patients responded within 7 days of treatment of which 60% were graded as Excellent responders as they responded within 4 days itself; while 13% took a longer time to respond. There were no relapses or carrier state as indicated by negative follow-up stool cultures. Only one patient reported a side-effect of mild headache confirming the safety of the drug. We conclude that Cefuroxime axetil in a dose of 500 mg bd is an effective and safe drug in the treatment of multi drug resistant enteric fever.     

Deterioration of metal–organic framework crystal structure during fabrication of poly(l‐lactic acid) mixed‐matrix membranes

Poly(l ‐lactic acid) (PLLA) and metal–organic framework (MOF) mixed‐matrix membranes were prepared by melt extrusion of PLLA with 5% (w/w) of either activated or water‐saturated Cu₃(BTC)₂ (Cu₃(C₉H₃O₆)₂(H₂O)₃·xH₂O, HKUST‐1). The morphology and the stability of injection‐molded samples were evaluated using thermogravimetric analysis, differential scanning calorimetry, gel permeation chromatography, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The presence of activated and saturated MOF crystals increased the cold crystallization onset temperature as compared to neat PLLA. This can be attributed to the MOF crystals incorporated in the PLLA matrix, which decreased the mobility of PLLA and thus impeded the crystallization process. According to the XRD results, the activated MOF crystals were successfully incorporated into the PLLA matrix without altering the crystal structure of the MOF. Moreover, the findings from permeability and tensile tests as well as SEM imaging indicated good interfacial interactions between PLLA and activated MOF. However, during melt extrusion of PLLA with saturated MOF, water molecules from the saturated MOF altered the MOF crystal structure and contributed to the degradation of the PLLA polymer by reducing its molecular weight by around 21%. © 2013 Society of Chemical Industry     

Energy policies and the greenhouse effect: A study of national differences

Country studies emphasize large national differences in underlying attitudes towards energy and the greenhouse effect. Technical opportunities for limiting CO₂ emissions exist in all countries, but the type of abatement policies that are feasible, the extent to which they can be effectively implemented and their likely impacts vary widely. The potential for curtailing emissions is determined by factors including: the stage of a country's development; the character of its economic system and philosophy; its political culture; and the nature of its energy infrastructure, institutions and attitudes, all of which are determined by the past and current availability of cheap domestic technology and costs, but about culture, about technology and costs, but about culture, institutions and politics in the broadest sense.     

Four-legged intelligent mobile autonomous robot

This paper presents the design and development of a four-legged mobile robot with intelligent sensing and decision-making capabilities. Multiple sensors with embedded knowledge bases and learning capabilities are used in a novel approach towards environmental perception and reaction. These sensors continuously monitor the environment as well as their own operating parameters. Priority is given to any one or a group of sensors based on prevailing environmental conditions. Intelligent sensing is shown to be the key towards a high degree of autonomy for a mobile robot. Nicknamed Flimar, this robot has the ability to function at varying degrees of intelligence made possible by an object-oriented architecture with embedded intelligence at various levels. This architecture is shown to be conducive towards incremental learning. Each of the four legs has three degrees of freedom, i.e. Flimar has a total of 12 motors on its four legs. Flimar can walk and turn without dragging or skidding, and also turns about its center of gravity with a zero radius. Flimar responds to light, sound and touch in different ways, based on prevailing environmental conditions. The overall goal of the paper is to present a novel walking principle and control architecture for a walking robot.     

Development and Application of a Watertable Model for the Assessment of Waterlogging in Irrigated Semi-arid Regions

Direct measurement of groundwater recharge is nearly impossible. So there are various direct and indirect methods and sophisticated models have been used for its estimation. However, the use of multiple approaches has been recommended to estimate the groundwater recharge since each individual approach is associated with some limitations. In many cases, different approaches complement each other and help refine the conceptual model of recharge processes. In this study, a simple watertable model, which is a combination of the groundwater budget and watertable fluctuation, was developed. The model is unique, simple, cost effective, and easy to apply. The model requires input parameters that are readily available or obtainable and which can be accurately measured. The model was applied to estimate the seasonal long?Cterm (30?years, e.g., from 1981 to 2011) groundwater recharge of a canal command located in Jhajjar district of Haryana State (India), where watertable is rising. The results were analysed to provide an overview of the process dynamics that led to watertable rise in the command area. The calculated watertable depths reasonably matched with the observed ones for all the seasons which were confirmed by the high R?Csquared value of 0.963. The mean error and root mean squared error were low at ?C0.0068 and 0.2548?m, respectively, while the model efficiency was 0.83. Different water management alternatives were studied to examine the effect of variation in model parameters on its output. Among the alternatives studied, increased tubewell draft had a higher impact on the overall water balance followed by reduced rice area and canal lining, respectively.     

Immediate detection of predicates in pervasive environments

An important problem in pervasive environments is detecting predicates on sensed variables in an asynchronous distributed setting to determine context and to respond. We do not assume the availability of synchronized physical clocks because they may not be available or may be too expensive for predicate detection in such environments with a (relatively) low event occurrence rate. We address the problem of detecting each occurrence of a global predicate, at the earliest possible instant, by proposing a suite of three on-line middleware protocols having varying degrees of accuracy. We analyze the degree of accuracy for the proposed protocols. The extent of false negatives and false positives is determined by the run-time message processing latencies.     

Compact high-order schemes for the Euler equations

An implicit approximate factorization (AF) algorithm is constructed, which has the following characteristics.

Novel back‐channel‐etch process flow based a‐IGZO TFTs for circuit and display applications on PEN foil

In this study, we report high‐quality amorphous indium–gallium–zinc‐oxide (a‐IGZO) thin‐film transistors (TFTs) fabricated on a polyethylene naphthalate foil using a new back‐channel‐etch (BCE) process flow. The BCE flow allows a better scalability of TFTs for high‐resolution backplanes and related circuits. The maximum processing temperature was limited to less than 165 °C in order to ensure good overlay accuracy (<1 µm) on foil. The presented process flow differs from the previously reported flow as we define the Mo source and drain contacts by dry etch prior to a‐IGZO patterning. The TFTs show good electrical performance, including field‐effect mobilities in the range of 15.0 cm²/(V·s), subthreshold slopes of 0.3 V/decade, and off‐currents <1.0 pA on foil. The threshold voltage shifts of the TFTs measured were less than 1.0 V after a stressing time of 10⁴ s in both positive (+1.0 MV/cm) and negative (?1.0 MV/cm) bias directions. The applicability of this new BCE process flow is demonstrated in a 19‐stage ring oscillator, demonstrated to operate at a supply voltage of 10 V with a stage delay time of 1.35 µs, and in a TFT backplane driving a 32 × 32 active‐matrix organic light‐emitting diode display.     

Low power highly sensitive platform for gas sensing application

This paper reports a low power miniaturized MEMS based integrated gas sensor with 36.84 % sensitivity (ΔR/R₀) for as low as 4 ppm (NH₃) gas concentration. Micro-heater based gas sensor device presented here consumes very low power (360 °C at 98 mW/mm²) with platinum (Pt) micro-heater. Low powered micro-heater is an essential component of the metal oxide based gas sensors which are portable and battery operated. These micro-heaters usually cover less than 5 % of the gas sensor chip area but they need to be thermally isolated from substrate, to reduce thermal losses. This paper elaborates on design aspects of micro fabricated low power gas sensor which includes ‘membrane design’ below the microheater; the ‘cavity-to-active area ratio’; effect of silicon thickness below the silicon dioxide membrane; etc. using FEM simulations and experimentation. The key issues pertaining to process modules like fragile wafer handling after bulk micro-machining; lift-off of platinum and sensing films for the realization of heater, inter-digitated-electrodes (IDE) and sensing film are dealt with in detail. Low power platinum microheater achieving 700 °C at 267 mW/mm² are fabricated. Temperature calculations are based on experimentally calculated thermal coefficient of resistance (TCR) and IR imaging. Temperature uniformity and localized heating is verified with infrared imaging. Reliability tests of the heater device show their ruggedness and repeatability. Stable heater temperature with standard deviation (σ) of 0.015 obtained during continuous powering for an hour. Cyclic ON–OFF test on the device indicate the ruggedness of the micro-heater. High sensitivity of the device for was observed for ammonia (NH₃), resulting in 40 % response for ~4 ppm gas concentration at 230 °C operating temperature.