Dopant profile and gate geometric effects on polysilicon gatedepletion in scaled MOS

Polysilicon depletion effects show a strong gate length dependence according to experimental p-channel MOS capacitance-voltage (C-V) data. The effect can be influenced not only by gate geometries, but also by dopant profiles in poly-gates. These effects have been modeled and verified using device simulation. Nonuniform dopant distributions in the vertical and lateral direction in the poly-gate cause additional potential drops. The potential drop in the poly-gate becomes critical as the gate geometry is scaled down due to edge and corner depletions resulting from fringing electric fields     

Palladium/Carbon Catalyzed Hydrogen Transfer Reactions using Magnesium/Water as Hydrogen Donor

Results on nonlinear phenomenon (NLP) in the liquid phase hydrogenation of methyl benzoylformate (MBF) and pyruvaldehyde dimethyl acetal (PA) on chiral Pt-cinchona catalyst are reported for the first time (enantiomeric excess 90–95%). The new data support the conclusions of the NLP studies on ethyl pyruvate (EP) and ketopantolactone (KPL). Namely, the order of the adsorption strengths of the parent cinchona alkaloids are: CD > CN > QN ~ QD and the results of the NLP measurements indirectly verify the so-called 1:1 model of enantioselection. The new data, however, call attention to a new, substrate and modifier dependent phenomenon, which necessitates further experiments for a better understanding of the mechanism of the Orito reaction.     

Superoxide produced in the heme pocket of the beta-chain of hemoglobin reacts with the beta-93 cysteine to produce a thiyl radical

The role of the beta-93 cysteine residue in the hemoglobin autoxidation process has been delineated by electron paramagnetic resonance. At low temperatures (8 K) after incubation at 235 K, free radical signals were detected. An analysis of the free radical spectrum produced implies that, besides the superoxide radical expected to be formed during autoxidation, an isotropic free radical is produced with a giso of 2.0133. This g value is consistent with that expected for a sulfur radical. Blocking the beta-93 sulfhydryl group with N-ethylmaleimide was found to eliminate the formation of the isotropic radical, but not the superoxide. This finding confirms the assignment of the isotropic radical as a thiyl radical originating from the oxidation of the cysteine SH group. A kinetic analysis of the time course for the formation of both the superoxide and thiyl radicals is consistent with a reversible electron transfer process between superoxide in the heme pocket of the beta-chains and the cysteine residue. This reaction is expected to produce both a thiyl radical and a peroxide. Direct evidence for peroxide production comes from the detection of a transient Fe(III) heme peroxide complex. The significance of the electron transfer process producing a thiyl radical is discussed. It is shown that the formation of the thiyl radical decreases the rate of autoxidation for the beta-chain and reduces heme degradation attributed to the reaction of superoxide with the heme. The insights gained from these low-temperature studies are believed to be relevant to room-temperature autoxidation.     

Shocks and high velocity deformation

The shock Hugoniot curves of a large number of materials up to a few Mbar have been obtained experimentally. Metallurgical examination and physical measurements on metallic and other samples recovered after shock loading up to several 100 kbar indicate the existence of large concentrations of point, line and planar defects. Dislocation mechanisms have been invoked to explain shock wave propagation and the phenomena related to the quick homogenisation of stress and strain behind the shock front. Computer simulation models using molecular dynamics calculations have also been used to understand some aspects of shock wave propagation at an atomistic level. For very strong shocks, the material is expected to melt under shock heating, but the experimental evidence regarding this is inconclusive. A combination of shock temperature measurement and theory may be able to answer this question.     

Design of controller using variable transformations for a nonlinear process with dead time

In this work, a globally linearized controller (GLC) for a first-order nonlinear system with dead time is proposed. This is similar to the GLC proposed by Ogunnalke [Ind. Eng. Chem. Process. Des. Dev. 25, 241-248 (1986)] for nonlinear systems without dead time. Two methods are proposed. One is based on the Smith prediction from the model in the transformed domain and the other is based on Newton's extrapolation method. The simulation study is made on the conical tank level process and the results are compared with those obtained using a conventional PI controller and the Smith PI controller based on the transfer function model about the operating point 39%. Finally, experimental results on the laboratory conical tank level process are also given.     

Effect of Variation in Matrix Constitution on the Work Hardening Behavior of a Peak Age Hardened SiC Reinforced Aluminum Based Metal-Matrix Composite

An understanding of the work hardening behavior of particulate reinforced metal -matrix composites is crucial in optimizing the parameters for deformation processing of these materials. In the case of particulate reinforced composites with an age hardenable aluminum alloy matrix, the microstructure and mechanical properties can be altered by a suitable aging treatment as well as by changing the content of alloying elements in the matrix. In this study MMCs with different levels of Cu in the matrix were prepared and aged to peak hardness. A modified continuum model was then used to relate the work hardening behavior of the composites to microstructural parameters. The model is shown to be accurate for all the composite materials investigated in the present study.     

Spreading and interlayer formation at the copper-copper oxide/polycrystalline alumina interface

Spreadability and reaction layer growth rates of copper-oxygen alloys on polycrystalline alumina were measured above the melting point of copper to better understand the direct bonding process. Spreading was measured as a function of composition and temperature by monitoring the diameter of molten droplets as a function of time. As the oxygen content of the melt increased from 0 to 3 wt pct, the spreading diameter increased linearly, at fixed time and temperature. Constant diameters were observed for oxygen compositions between approximately 3 and 6 wt pct. The diameters again increased linearly for oxygen concentrations greater than 7 wt pct. This behavior was explained by reference to the copper-oxygen binary phase equilibrium. An interfacial product was identified to be the complex oxide, CuA10₂. A detailed investigation of the interlayer growth kinetics was performed to understand the fundamental phenomena controlling the spreading rates. The growth rate of the CuAlO₂ phase and the spreading rate were simultaneously measured for alumina in contact with a copper-2 wt pct oxygen alloy drop as a function of temperature. The reaction layer thickening was found to be diffusion controlled, with an apparent activation energy of 309 kJ/mol, and the spreading rate did not correlate with the thickening rate. Formerly Research Associate, Center for Welding and Joining Research, Department of Metallurgical and Materials Engineering     

Hypoglycaemic and Hypolipidaemic Effects of Withania somnifera Root and Leaf Extracts on Alloxan-Induced Diabetic Rats

Withania somnifera is an important medicinal plant, which is used in traditional medicine to cure many diseases. Flavonoids were determined in the extracts of W. somnifera root (WSREt) and leaf (WSLEt). The amounts of total flavonoids found in WSREt and WSLEt were 530 and 520 mg/100 g dry weight (DW), respectively. Hypoglycaemic and hypolipidaemic effects of WSREt and WSLEt were also investigated in alloxan-induced diabetic rats. WSREt and WSLEt and the standard drug glibenclamide were orally administered daily to diabetic rats for eight weeks. After the treatment period, urine sugar, blood glucose, haemoglobin (Hb), glycosylated haemoglobin (HbA1C), liver glycogen, serum and tissues lipids, serum and tissues proteins, liver glucose-6-phosphatase (G6P) and serum enzymes like aspartate transaminase (AST), alanine transaminase (ALT), acid phosphatase (ACP) and alkaline phosphatase (ALP) levels were determined. The levels of urine sugar, blood glucose, HbA1C, G6P, AST, ALT, ACP, ALP, serum lipids except high density lipoprotein-bound cholesterol (HDL-c) and tissues like liver, kidney and heart lipids were significantly (p < 0.05) increased, however Hb, total protein, albumin, albumin:globulin (A:G) ratio, tissues protein and glycogen were significantly (p < 0.05) decreased in alloxan-induced diabetic rats. Treatment of the diabetic rats with WSREt, WSLEt and glibenclamide restored the changes of the above parameters to their normal level after eight weeks of treatment, indicating that WSREt and WSLEt possess hypoglycaemic and hypolipidaemic activities in alloxan-induced diabetes mellitus (DM) rats.     

Recent Advances in Poly (Amide-B-Ethylene) Based Membranes for Carbon Dioxide (CO2) Capture: A Review

Polyamide-b-ethylene (Pebax) is a promising material for membrane-based gas separation application with excellent CO₂ capturing potential. Pebax is a rubbery elastomer which offers good mechanical support with its hard crystalline phase and excellent gas transport through its amorphous polyether phase. This review article includes recent advances in Pebax based membrane synthesis, solvent selection for membrane synthesis, compatible fillers with Pebax matrix and the improved gas separation performance of the prepared membranes. The literature review shows that Pebax based membranes are a good candidate for separation of CO₂ from flue gases and can be used for commercial applications.