Time-dependent dielectric breakdown (TDDB) distribution in n-MOSFET with HfSiON gate dielectrics under DC and AC stressing

This paper discusses time-dependent dielectric breakdown (TDDB) in n-FETs with HfSiON gate stacks under various stress conditions. It was found that the slope of Weibull distribution of T_bd, Weibull β, changes with stress conditions, namely, DC stress, unipolar AC stress and bipolar AC stresses. On the other hand, the time evolution component of stress-induced leakage current (SILC) was not changed by these stresses. These experimental results indicate that the modulation of electron trapping/de-trapping and hole trapping/de-trapping by stress condition changes the defect size in high-k gate dielectrics. Therefore, the control of injected carrier and the characteristics of trapping can provide the steep Weibull distribution of T_bd, leading to long-term reliability in scaled CMOS devices with high-k gate stacks.     

Induction of salt tolerance in Bacillus subtilis IFO 3025

Salt tolerance was induced in Bacillus subtilis IFO 3025 cells when a moderate osmotic stress was imposed by incubation in the presence of compatible solutes and 0.5 M NaCl or 0.8 M sorbitol. The optimum condition for inducing salt tolerance was observed when the cells were incubated in a solution containing 5 mM glutamate, 2.5 mM KCl, and 0.5 M NaCl or 0.8 M sorbitol. After 60 min incubation, the cells were able to form colonies on an agar plate with high salinity. It was confirmed that the cells acquired salt tolerance by accumulating glutamate and potassium ions in the cytoplasm as the main solute and ion, respectively.     

Evaluation of dioxin-like activities in settled house dust from Vietnamese E-waste recycling sites: relevance of polychlorinated/brominated dibenzo-p-dioxin/furans and dioxin-like PCBs

Few studies have investigated the human exposure to the ensemble of dioxin-related compounds (DRCs) released from uncontrolled e-waste recycling, especially from a toxic effect standpoint. This study evaluated the TCDD toxic equivalents (TEQs) in persistent extracts of settled house dust from two Vietnamese e-waste recycling sites (EWRSs) using the Dioxin-Responsive Chemically Activated LUciferase gene eXpression assay (DR-CALUX), combined with chemical analysis of PCDD/Fs, DL-PCBs, PBDD/Fs, and monobromo PCDD/Fs to determine their TEQ contribution. The CALUX-TEQ levels in house dust ranged from 370 to 1000 pg g(-1) in the EWRSs, approximately 3.5-fold higher than in the urban control site. In EWRS house dust, the concentrations of the unregulated PBDFs were 7.7-63 ng g(-1), an order of magnitude higher than those of regulated DRCs (PCDD/Fs and DL-PCBs), and PBDFs were also principal CALUX-TEQ contributors (4.2-22%), comparable to PCDD/Fs (8.1-29%). The CALUX-TEQ contribution of DRCs varied, possibly depending on thermal processing activities (higher PCDD/F-TEQs) and PBDE content in the waste (higher PBDF-TEQs). However, the percentage of unknown dioxin-like activities was high in all dust samples, indicating large contribution from unidentified DRCs and/or synergy among contaminants. Estimates of TEQ intake from dust ingestion suggest that children in the EWRSs may be adversely affected by DRCs from dust.     

Fabrication of flat micro‐gap electrodes for molecular electronics

Recently, organic molecular electronic devices such as molecular thin‐film transistors have received considerable attention as possible candidates for next‐generation electronic and optical devices. This paper reports on fabrication technologies of flat metallic electrodes on insulating substrates with a micrometer separation for high‐performance molecular device evaluation. The key technologies of fabricating planar‐type electrodes are the liftoff method by the combination of bilayer photoresist with overhang profile, electron beam evaporation of thin metal (Ti and Au) films, and SiO₂‐CMP (Chemical Mechanical Polishing) method of CVD (Chemical Vapor Deposition)‐deposited TEOS (tetraethoxysilane)–SiO₂ layer. The raggedness of the electrode/insulator interface and the electrode surface of the micro‐gap electrodes were less than 3 nm. The isolation characteristics of fabricated electrodes were on the order of 10¹³ ohms at room temperature, which is sufficient for evaluating electronic properties of organic thin‐film devices. Finally, pentacene FET (Field Effect Transistor) characteristics are discussed fabricated on the micro‐gap flat electrodes. The mobility of this FET was 0.015 cm²/Vs, which was almost on the order of the previous results. These results suggest that high‐performance organic thin‐film transistors can be realized on these advanced electrode structures. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 39–46, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20152     

Gas-storage ice grown from water containing microbubbles

Gas-storage ice is the ice that contains various functional gas pores, and can be produced by freezing water in which a desired gas is dissolved. In this conventional method, however, the gas content in the ice is limited by the gas solubility in water. To overcome this limitation, we developed a method to produce gas-storage ice from water in which microbubbles of a desired gas are dispersed, and then obtained images of the structural features of pores formed in the ice prepared using this microbubble method. The images clarified the interaction between a microbubble arriving at an ice–water interface and an existing pore already formed in the ice. The air content in ice prepared using the microbubble method was higher than that prepared using the conventional method, and was about three times higher than the solubility of air in water.     

Endometrial cytology in postmenopausal hormone replacement therapy

INTRODUCTION: The purpose was to examine whether health-promotion programs offered by California health plans are a serious attempt to improve health status or a marketing device used in an increasingly competitive marketplace. The research examined differences in the coverage, availability, utilization, and evaluation of health-promotion programs in California health plans. METHODS: A mail survey was done of the 35 HMOs (86% response) and 18 health insurance carriers (83% response) licensed to sell comprehensive health insurance in California in 1996 (some plans sell both HMO and PPO/indemnity products). The final sample included 30 commercial HMOs and 20 PPO and indemnity plans. The 1996 California Behavioral Risk Factor Survey (BRFS) of 4,000 adults was used to estimate population participation rates in health-promotion programs. RESULTS: California's HMOs in 1996 offered more comprehensive preventive benefits and health-promotion programs compared to PPO and indemnity plans. HMOs relied on a more comprehensive set of health-education methods to communicate health information to members and were more likely to open their programs to the public. HMOs are also more likely to have developed relationships with community-based and public health providers. Participation in health-promotion programs is low (2%-3%), regardless of plan type, and most health plans limit evaluations to assessment of member satisfaction and utilization. Only 35%-45% of HMOs, and no PPO/indemnity plans, assess the impact of health-promotion programs on health risks and behaviors, health status, or health care costs. CONCLUSION: For the majority of California's PPO and indemnity plans, health promotion is not an integral part of their business. For the majority of HMOs, health-promotion programs are offered primarily as a marketing vehicle. However, a substantial minority of HMOs offer health-promotion programs to achieve other organizational goals of health improvement and cost control.     

PHoM – a Polyhedral Homotopy Continuation Method for Polynomial Systems

PHoM is a software package in C++ for finding all isolated solutions of polynomial systems using a polyhedral homotopy continuation method. Among three modules constituting the package, the first module StartSystem constructs a family of polyhedral-linear homotopy functions, based on the polyhedral homotopy theory, from input data for a given system of polynomial equations f(x)=0. The second module CMPSc traces the solution curves of the homotopy equations to compute all isolated solutions of f(x)=0. The third module Verify checks whether all isolated solutions of f(x)=0 have been approximated correctly. We describe numerical methods used in each module and the usage of the package. Numerical results to demonstrate the performance of PHoM include some large polynomial systems that have not been solved previously.AMS Subject Classification: Primary: 65H10 system of equations, secondary: 65H20 global methods, including homotopy approaches.     

Adsorption of tetrakis(p-sulfonatophenyl)porphyrin on kaolinite

The surface modification of kaolinite to introduce the adsorption sites for anionic species was reported. The introduction of an anion exchange site was as follows; intercalation of 2-aminoethanol into kaolinite by using dimethyl sulfoxide-kaolinite intercalation compound as a precursor and subsequent hydrochlorination of 2-aminoethanol-kaolinite in 1,4-dioxane. The hydrochlorination of 2-aminoethanol-kaolinite was confirmed by the increase in the basal spacing (0.2 nm, corresponding to the diameter of chlorine) and the appearance of the infrared absorption bands due to ammonium groups. The modified kaolinite adsorbed an anionic dye, tetrakis(p-sulfonatophenyl)porphyrin, from a N,N-dimethylformamide solution. Initial slope of the adsorption isotherm of tetrakis(p-sulfonatophenyl)porphyrin on the hydrochlorinated 2-aminoethanol-kaolinite was steep, showing strong adsorbate-adsorbent interactions. The gallery height after the adsorption of tetrakis(p-sulfonatophenyl)porphyrin was close to the thickness of the porphyrin ring, suggesting that tetrakis(p-sulfonatophenyl)porphyrin was intercalated as a monomolecular layer and that chlorine simultaneously deintercalated.