Effective cleaning of hexagonal boron nitride for graphene devices

Hexagonal boron nitride (h-BN) films have attracted considerable interest as substrates for graphene. ( Dean, C. R. et al. Nat. Nanotechnol. 2010 , 5 , 722 - 6 ; Wang, H. et al. Electron Device Lett. 2011 , 32 , 1209 - 1211 ; Sanchez-Yamagishi, J. et al. Phys. Rev. Lett. 2012 , 108 , 1 - 5 .) We study the presence of organic contaminants introduced by standard lithography and substrate transfer processing on h-BN films exfoliated on silicon oxide substrates. Exposure to photoresist processing adds a large broad luminescence peak to the Raman spectrum of the h-BN flake. This signal persists through typical furnace annealing recipes (Ar/H(2)). A recipe that successfully removes organic contaminants and results in clean h-BN flakes involves treatment in Ar/O(2) at 500 °C.     

Performance Analysis of Mixed-Base Modulation System

In this paper the performance of the mixed-base modulation (MBM) system is analyzed for the case where the input signal is a sample function of a Gaussian random process and an optimum stretching is employed. The comparison of theoretical performance of the MBM system with that of other common modulation schemes such as FM and PCM/PSK shows that it provides performance much better than that of those schemes where the same bandspread factor is employed.     

Interface state generation mechanism in n-MOSFET's

Uniform carrier injection into the channel of n-MOSFETs generates two types of interface states, depending on the oxide electric field: One is linearly proportional to the injected electron density (Type I), while the other shows a half-power dependence (Type II). Charge-pumping measurements in the temperature range of 77K and 263K show that the type I interface states are located in the mid-gap, while the type II interface states are uniformly distributed in wide energy range. Holes generated at the gate/SiO₂ interface or in the oxide are found to be responsible for the type I interface states, while hydrogen or hydrogen compounds diffusing from the interface cause the type II interface states.     

A 500-MHz pipelined burst SRAM with improved SER immunity

This paper describes a 0.25-μm, 64 K×36 bit pipelined burst SRAM using a 6.156-μm² cell. It realizes over 500-MHz operation using a lower cost double metal process, Internal 16 K×144 organization by T-shaped bit line array reduces 20% of latency, 20% of active power, and 8.5% of die size. The low power also enables us to use lower cost thin quad flat type packages. Our solution to the soft error problem, a shallow triple well structure and four-transistor cell with stacked capacitor, improved soft error rate by 3.5 orders of magnitude compared with the conventional SRAM cell     

Stability of free convection with uniform suction or injection from a vertical flat plate subjected to a constant wall heat flux

Summary A theoretical study is presented for the stability characteristics of the laminar free convection boundary layer flow along a vertical porous (permeable) flat plate subjected to a constant heat flux. The disturbance equations are solved numerically on the basis of the linear stability theory for a wide range of values of the modified Grashof number,G, and some values of the suction or injection parameterX when the Prandtl number, Pr, is 0.73 (air). These solutions indicate the important role of the parametersG andX on the flow and heat transfer characteristics. It is found that the present results are in very good agreement with those from the open literature.     

Visible Light Irradiation of [60]Fullerene Causes Killing and Initiation of Transformation in Balb/3T3 Cells

Cell transformation in vitro is a model of carcinogenesis in vivo. Two-stage transformation assay increases the sensitivity of cells to chemicals and permits detection of carcinogens acting as initiating agents. [60]Fullerene (C₆₀) was cytotoxic in BALB/3T3 cells when it was irradiated by visible light, but not without light irradiation. Under conditions when C₆₀ was cytotoxic, it acted as an initiating agent for cell transformation, but it did not act as a complete transforming agent. the initiating activity of visible-light-irradiated C₆₀ was statistically significant in a modified two-stage transformation assay including a procedure for replating cells treated by C₆₀ and light, but it was equivocal in the standard two-stage transformation assay.     

Experimental verification of fuzzy excitation control system formulti-machine power system

A fuzzy excitation control system (FECS), based on the fuzzy theorem and having the function of both AVR and PSS, was established to improve power system stability. This paper includes the results of experiments of the FECS on the AC/DC power system simulator of the CRIEPI. The FECS is compared with the conventional quick-response excitation system with optimized PSSs on a 4-machine long distance fish-bone type power system and various system configurations. The results show that the FECS increases the power transfer limit more than 20 (%) without any parameter tuning     

A numerical integration method for long-term power system dynamic simulation

Large power system frequency/voltage fluctuations due to severe faults in trunk transmission lines or major generating units may trip-off other facilities and result in large-scale power system blackout. To prevent such blackout, development of an accurate and fast long-term power system dynamic simulation tool is required. With respect to the development stage, selection of a numerical integration method available for step-size adjustment, and the development of a scheme for the adjustment are principal subjects. The trapezoidal and the second-order Gear methods were selected as possible candidates for the step-size adjustment from the viewpoint of numerical stability. The trapezoidal method is selected from the viewpoint of accuracy and applicability to power system dynamic simulations. A new scheme for the automatic step-size adjustment is proposed for the trapezoidal method to achieve fast simulation of the long-term power system dynamics. The validity of the proposed scheme is verified through simulation studies on a single-machine-to-infinite bus system.     

cDNA cloning and expression of a novel serine protease, TLSP

A cDNA for a putative novel serine protease, TLSP, was cloned from human hippocampus cDNA with polymerase chain reaction based strategies. The putative amino acid sequence of TLSP is similar to the trypsin-type serine proteases. TLSP mRNA is expressed in keratinocytes. Overexpressed TLSP protein in neuro2a cells was detected in culture medium.     

Oxidation of intermetallics – Japanese activity

Oxidation studies on intermetallic compounds carried out in Japan in the last ten years have been summarized and critically reviewed. The major effort was expended to improve the oxidation resistance of TiAl-base materials. The methods tried include alloying additions, surface treatments and combinations of the both. Alloying additions to TiAl were more closely reviewed here. An excellent oxidation resistance was obtained owing to the formation of Al₂O₃ scales by alloying additions of 0.2Zr, 0.2Hf or 500 ppm Cl, and by Nb-ion implantation. Preoxidation under reduced oxygen pressures also resulted in the formation of protective Al₂O₃ scales. Ceramic coatings and MCrAlY type coatings showed some improvement in the oxidation resistance. Studies on other aluminides of current interest arc relatively few. On the other hand, studies on suicides arc becoming more active than before, though still few in comparison with TiAl-base materials. In the concluding remarks directions for future studies are shown.