TCAD-based statistical analysis and modeling of gate line-edge roughness effect on nanoscale MOS transistor performance and scaling

The effects of line edge roughness (LER) of nanometer scale gate pattern on the MOS transistor parameter fluctuations and their technology scaling are investigated using the simplified modeling and statistical analysis based on two-dimensional technology CAD (TCAD) tools. From the simple statistical analysis, it is shown that the gate patterns without appropriate LER may cause severe device parameter and performance fluctuations in highly scaled nanometer technologies, resulting in a negative average threshold voltages shift, a subthreshold slope degradation, an unrealistic effective channel length extraction and an exponential increase in off-state leakage current due to LER-induced inhomogeneous channel potential. The characteristics of the average off-state leakage current and the threshold voltage uncertainty as a function of technology scaling provide a useful guideline for advanced gate patterning process and demand much tighter control of LER less than 3-5 nm for a successful CMOS scaling into deep nanometer scale physical gate length regime below 50 nm.     

Lipase‐catalyzed ethanolysis of soybean oil in a solvent‐free system using central composite design and response surface methodology

BACKGROUND: In this work we describe the synthesis of ethyl esters, commonly known as biodiesel, using refined soybean oil and ethanol in a solvent‐free system catalyzed by lipase from Thermomyces lanuginosus. Central composite design and response surface methodology (RSM) were employed to optimize the biodiesel synthesis parameters, which were: reaction time, temperature, substrate molar ratio, enzyme content, and added water, measured as percentage of yield conversion. RESULTS: The optimal conditions obtained were: temperature, 31.5 °C; reaction time, 7 h; substrate molar ratio, 7.5:1 ethanol:soybean oil; enzyme content, 15% (g enzyme g⁻¹ oil); added water, 4% (g water g⁻¹ oil). The experimental yield conversion obtained under these conditions was 96%, which is very close to the maximum predicted value of 94.4%. The reaction time‐course at the optimal values indicated that 5 h was necessary to obtain high yield conversions. CONCLUSION: A high yield conversion was obtained under the optimized conditions, with relative low enzyme content and short time. Comparison of predicted and experimental values showed good correspondence, implying that the empirical model derived from RSM can be used to adequately describe the relationship between the reaction parameters and the response (yield conversion) in lipase‐catalyzed biodiesel synthesis. Copyright © 2008 Society of Chemical Industry     

Comparative Study of Multiencoding Schemes for OCDM Using a Single Multiport Optical Encoder/Decoder

We analyse the performance of multicode shift keying modulation in an optical code-division multiplexing network scenario and demonstrate the effectiveness of using a single multiport optical encoder/decoder as a source coding element. We assign a set of codes to each user, and numerically evaluate the system performances, in terms of bit-error rate and spectral efficiency     

Management of Cirrhotic Ascites under the Add-on Administration of Tolvaptan

Tolvaptan is a recently available diuretic that blocks arginine vasopressin receptor 2 in the renal collecting duct. Its diuretic mechanism involves selective water reabsorption by affecting the water reabsorption receptor aquaporin 2. Given that liver cirrhosis patients exhibit hyponatremia due to their pseudo-aldosteronism and usage of natriuretic agents, a sodium maintaining agent, such as tolvaptan, is physiologically preferable. However, large scale studies indicating the patients for whom this would be effective and describing management under its use have been insufficient. The appropriate management of cirrhosis patients treated with tolvaptan should be investigated. In the present review, we collected articles investigating the effectiveness of tolvaptan and factors associated with survival and summarized their management reports. Earlier administration of tolvaptan before increasing the doses of natriuretic agents is recommended because this may preserve effective arterial blood volume.     

In vitro ferredoxin-dependent desaturation of fatty acids in cyanobacterial thylakoid membranes

Thylakoid membranes isolated from the cyanobacterium Synechocystis sp. strain PCC6803 were capable of desaturating the acyl groups in monogalactosyl diacylglycerol. This desaturation reaction required the reduced form of ferredoxin.     

Two cases of mediastinitis as a complication of odontogenic infection and tonsillitis

We experienced two cases of descending necrotizing mediastinitis with different etiology. Case 1: A 59-year-old woman presented with chief complaints of dyspnea and swallowing disturbance. She had been diagnosed as having tonsillitis one week before. She was very pyrexic, and laboratory examination indicated acute inflammation. Chest X-ray and CT-scan showed enlargement of the mediastinum and pleural effusion. We diagnosed the mediastinitis to be a complication of tonsillitis. Case 2: A 54-year-old man had a tooth extracted 3 weeks prior to admission. His chief complaints were craniomandibular disturbance and neck swelling. Laboratory examination disclosed multiple organ failure and DIC. Chest X-ray and CT-scan showed enlargement of the mediastinum and pleural effusion. We diagnosed the mediastinitis in this case to be a consequence of an odontogenic infection following tooth extraction. Both patients received continuous drainage and irrigation of the abscesses and recovered in about 2 months. Case 1 showed an impaired glucose tolerance after recovery from mediastinitis. Although the main causes of mediastinitis are cardiac surgery and esophageal perforation, our cases demonstrate that mediastinitis may occur as a complication of deep neck infection.     

Micro-raman characterization of molecular-beam epitaxial ge heterolayers on Si substrates

Molecular-beam epitaxial germanium heterolayers on silicon are characterized by micro-Raman spectroscopy. The samples are angle-lapped to probe the near-interface region. A small positive shift in the germanium phonon frequency is observed near the interface compared with the surface of the 1 μm thick layer. This indicates that the misfit stress is not relaxed completely in the as-grown layers. The samples are annealed at 700°C, a temperature higher than the growth temperature, and then the germanium peak shifts toward lower frequency near the interface. This would be due to both thermal stress and formation of an interfacial alloy layer by the interdiffusion. After annealing at 850°C, the germanium peak shifts downward further because of the interdiffusion, and the peak due to the Si−Ge vibration is clearly observed near the interface.