140 research outputs found

    Design methodology for electron-trap memory cells

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    It is widely known that the decreasing feature size facilitated vast improvement in semiconductor-based design. But this improvement will eventually come to an end. The MOS transistor itself cannot overcome its limits dictated by its operating principle. In order to ensure further feature size reduction, the field of single-electronics has been developed. Single Electron Tunneling (SET) technology offers the ability to control the transport and position of a single or a small number of electrons. In this thesis we investigate the implementation of arithmetic operations in SET technology. In particular we focus on design methodologies for SET based Electron-Trap which is a basic memory cell that has been recently fabricated. Given a circuit topology and the corresponding targeted behaviour, the proposed methodology assists the circuit designer in deriving the circuit parameters in an analytical way. The methodology is based on the mathematical description of the tunnel junctions in the circuit. Moreover the method allows for the analysis of reliability issues

    Mechanism of the fcc-hcp Phase Transformation in Solid Ar

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    We present an atomistic description of the {\it fcc}--to--{\it hcp} transformation mechanism in solid argon (Ar) obtained from transition path sampling molecular dynamics simulation. The phase transition pathways collected during the sampling for an 8000--particle system reveal three transition types according to the lattice deformation and relaxation details. In all three transition types, we see a critical accumulation of defects and uniform growth of a less ordered transition state, followed by a homogeneous growth of an ordered phase. Stacking disorder is discussed to describe the transition process and the cooperative motions of atoms in \{111\} planes. We investigate the nucleation with larger system. In a system of 18000--particles, the collective movements of atoms required for this transition are facilitated by the formation and growth of stacking faults. However the enthalpy barrier is still far beyond the thermal fluctuation. The high barrier explains previous experimental observations of the inaccessibility of the bulk transition at low pressure and its sluggishness even at extremely high pressure. The transition mechanism in bulk Ar is different from Ar nanoclusters as the orthorhombic intermediate structure proposed for the latter is not observed in any of our simulations.Comment: 25 pages, 12 figures, journal supplementary included as appendi

    Heat and Mass Transfer in Outward Convex Corrugated Tube Heat Exchangers

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    Heat and mass transfer in outward convex corrugated tube heat exchangers is of significant importance for the optimization, fabrication, and application of outward convex corrugated tube heat exchangers. This chapter gives a deep investigation of the heat and mass transfer in outward convex corrugated tube heat exchangers. Based on the experimental setup developed, the performances of a novel outward convex corrugated tube heat exchanger are presented. Simulation methods are then used to detail the heat and mass transfer at tube side and shell side of the outward convex corrugated tube heat exchanger, and these include the flow structure, temperature distribution, and turbulence kinetic energy. Heat and mass transfer enhancements of the outward convex corrugated tube heat exchanger are also studied, and they are from tube side, shell side, and overall system aspects. Finally, multi-objective optimization of the outward convex corrugated tube heat exchanger is conducted to obtain the optimal performances through using Response Surface Methodology (RSM) and Non-dominated Sorting Genetic Algorithm (NSGA-II). Main conclusions and future outlook are then briefly stated and summarized. We firmly believe that the contents presented in this chapter can not only enrich the knowledge of heat exchangers but also develop methods for studying heat exchangers

    Research Progress of Vitamin D and Pathogenesis of Bronchial Asthma

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    At present the incidence of bronchial asthma on the rise, its pathogenesis and the genetic immune and the relationship between social environment and other aspects are inseparable the activity of vitamin D (Vit D) in the body in the form of 1, 25 - (OH) 2 d3, mainly involved in bone metabolism and calcium absorption in addition to this, a growing number of studies show that in Vit D plays an important role in the pathogenesis of bronchial asthma, play a role in the immune function of bronchial asthma growth hormone sensitivity adjustment and airway remodeling in this paper, the development of a variety of mechanisms, such as Vit D. Review the possible mechanisms affecting bronchial asthma, hoping to provide adjuvant treatment for patients with bronchial asthma, discover new treatment approaches, and improve the quality of life for patients

    Microwave‐Assisted Pyrolysis of Biomass for Bio‐Oil Production

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    Microwave‐assisted pyrolysis (MAP) is a new thermochemical process that converts biomass to bio‐oil. Compared with the conventional electrical heating pyrolysis, MAP is more rapid, efficient, selective, controllable, and flexible. This chapter provides an up‐to‐date knowledge of bio‐oil production from microwave‐assisted pyrolysis of biomass. The chemical, physical, and energy properties of bio‐oils obtained from microwave‐assisted pyrolysis of biomass are described in comparison with those from conventional pyrolysis, the characteristics of microwave‐assisted pyrolysis as affected by biomass feedstock properties, microwave heating operations, use of exogenous microwave absorbents, and catalysts are discussed. With the advantages it offers and the further research and development recommended, microwave‐assisted pyrolysis has a bright future in production of bio‐oils that can effectively narrow the energy gap and reduce negative environmental impacts of our energy production and application practice

    LQTS Gene LOVD Database

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    The Long QT Syndrome (LQTS) is a group of genetically heterogeneous disorders that predisposes young individuals to ventricular arrhythmias and sudden death. LQTS is mainly caused by mutations in genes encoding subunits of cardiac ion channels (KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2). Many other genes involved in LQTS have been described recently (KCNJ2, AKAP9, ANK2, CACNA1C, SCNA4B, SNTA1, and CAV3). We created an online database (http://www.genomed.org/LOVD/introduction.html) that provides information on variants in LQTS-associated genes. As of February 2010, the database contains 1738 unique variants in 12 genes. A total of 950 variants are considered pathogenic, 265 are possible pathogenic, 131 are unknown/unclassified, and 292 have no known pathogenicity. In addition to these mutations collected from published literature, we also submitted information on gene variants, including one possible novel pathogenic mutation in the KCNH2 splice site found in ten Chinese families with documented arrhythmias. The remote user is able to search the data and is encouraged to submit new mutations into the database. The LQTS database will become a powerful tool for both researchers and clinicians. © 2010 Wiley-Liss, Inc
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