The structure and mechanical properties of sheets prepared from bacterial cellulose

A sheet obtained from bacterial cellulose had a remarkably high modulus of elasticity as reported in Part 1 of this series. The Young's modulus of a sheet prepared by squeezing and drying a gel-like pellicle of bacterial cellulose was found to be > 15 G Pa. In addition, it has been found that treatment of the gel-like pellicles or dried sheets of bacterial cellulose with alkaline and/or oxidative solutions improves the mechanical properties significantly, and the Young's modulus of the resulting sheets approaches 30 G Pa. In this paper, improvement of the mechanical properties of bacterial cellulose sheets by the removal of impurities is investigated and the applicability of bacterial cellulose to diaphragms of electroacoustic transducers is discussed.     

Tocopherol distribution and oxidative stability of oils prepared from the hypocotyl of soybeans roasted in a microwave oven

Whole soybeans (Glycin max L.) were roasted by exposure to microwaves at a frequency of 2,450 MHz, and their hypocotyls were separated from other tissues (seed coat and cotyledons). The quality characteristics and composition in the hypocotyl oils were studied in relation to their tocopherol distributions and were evaluated as compared to an unroasted oil sample. Only minor increases (P<0.05) in chemical and physical changes of the oils, such as carbonyl value, anisidine value and color development, occurred with increased roasting time. Significant decreases (P<0.05) were observed in the amounts of phospholipids in the oils after microwave roasting. Nevertheless, compared to the original level, more than 80% tocopherols still remained after 20 min of roasting. These results suggest that the exposure of soybeans to microwaves for 6 to 8 min caused no significant loss or changes in the content of tocopherols and polyunsaturated fatty acids in the hypocotyls. Therefore, a domestic microwave oven would be useful as a simple and quick means for preparing hypocotyl oil of good quality.     

Testing Method for the Johnson–Mehl–Avrami Equation in Kinetic Analysis of Crystallization Processes

The kinetics of crystallization processes in solids are usually described by the Johnson–Mehl–Avrami equation. One of the most popular methods to test the applicability of this equation is based on a double logarithmic plot of fraction crystallized (α). However, such plot is not very sensitive to small changes in α, and its reliability is rather limited. A simple and convenient testing method based on rate data (dα/d t ) is proposed. The method can be applied to virtually any type of kinetic data obtained under isothermal or nonisothermal conditions.     

Left ventricular function and coagulation activity in healed myocardial infarction

We investigated the plasma levels of molecular markers for the thrombotic and fibrinolytic status in patients with healed myocardial infarction to determine the relation between left ventricular (LV) function and coagulation activity. Our findings demonstrated that the coagulation activity was increased in patients with healed myocardial infarction along with LV dysfunction, suggesting that anticoagulant therapy is considered in patients with severe LV dysfunction to prevent systemic thromboembolism.     

Risk assessment for liquid hydrogen fueling stations

In recent years, consumers calling for the protection of the environment on a regional and global scale are demanding the use of vehicles that do not emit harmful exhaust. It is anticipated that one response to this demand is the widespread use of fuel cell vehicles (FCVs). In order to achieve this, it is necessary to provide hydrogen fueling stations where FCVs can refuel.     

Intra-pellet neutron flux distribution measurements in LWR critical lattices

We have developed inexpensive and easy-handling measurement methods on intra-pellet neutron flux. A foil activation method with metallic foils, which were fabricated by punching out technique and etching technique to reduce fabrication error and positioning error, was used for the intra-pellet neutron flux distribution measurement. The developed method was applied to measure intra-pellet neutron flux distributions in a reduced–moderation light water reactor (LWR) lattices, and uncertainty of the distributions was estimated to be 1% to 2%. Measured values were analyzed with a continuous energy Monte Carlo code. Comparison of measurements and analyses revealed that the developed method is useful for the validation of an advanced fuel design method considering neutron behavior in fuel pellets.     

High-temperature oxidation process of intermetallic compound Ti-42 at% Al

The oxidation process of two-phase (Ti₃Al and TiAl) intermetallic compound, Ti-42 at% Al, in air at 1073 and 1273 K has been investigated. The oxidation at 1273 K is much faster than that at 1073 K; however, the oxidation kinetics are similar. During heating up, TiO₂ scale forms initially on the compound surface at about 973 K, and then Al₂O₃ scale forms at about 1273 K. For the isothermal heating, TiO₂ scale slowly grows up at 1073 K, while at 1273 K both TiO₂ and Al₂O₃ scales grow up drastically. The outer oxide scale consists of TiO₂ and the inner one consists of a mixture of TiO₂ and Al₂O₃. The volume of Al₂O₃, which forms after TiO₂ formation at the initial stage of oxidation, is larger at an area adjacent to the oxide-compound interface.     

Optimization of HfSiON using a design of experiment (DOE) approach on 0.45 V Vt Ni-FUSI CMOS transistors

We report for the first time that the optimization of a HfSiON process on Ni-FUSI devices is best tackled using a design of experiments (DOE [Myers RH, Montgomery. Response surface methodology. New York, DC: Wiley; 1995]) approach. We show that a DOE allows for directly linking process parameters to relevant short channel performance metrics. By tuning the SiO₂ thickness, HfSiO thickness, Hf concentration, nitridation parameters and by using response surface modeling (RSM), we report an improvement of 12%/17% in nMOS/pMOS drive current (I_dsat 600/255 uA/μm at I_off = 20 pA/μm and V_dd = 1.1 V) over our reference process. In parallel, we demonstrate that by selecting the right parameters, plasma nitridation can outperform thermal nitridation with NH_3. We believe that this new approach will be useful for device engineers and can be easily applied.