Nanoelectronic Circuit Architectures Based on Single-Electron Turnstiles

Single-electron devices (SEDs) have ultra-low power dissipation and high integration density, which make them promising candidates as basic circuit elements of the next generation VLSI circuits. In this paper, we propose two novel circuit single-electron architectures: the single-electron simulated annealing algorithm (SAA) circuit and the single-electron cellular neural network (CNN). We used the MOSFET-based single-electron turnstile [1] as the basic circuit element. The SAA circuit consists of the voltage-controlled single-electron random number generator [2] and the single-electron multiple-valued memories (SEMVs) [3]. The random-number generation and variable variations in SAA are easily achieved by transferring electrons using the single-electron turnstile. The CNN circuit used the floating-gate single-electron turnstile as the neural synapses, and the number of electrons is used to represent the cells states. These novel circuits are promising in future nanoscale integrated circuits.

Self-assembled 3D Architectures of LuBO3 : Eu3+: Phase-selective synthesis, growth mechanism, and tunable luminescent properties

Rhombohedral-calcite and hexagonal-vaterite types of LuBO:Eu3+ microparticles with various complex self-assembled 3D architectures have been prepared selectively by an efficient surfactant- and template-free hydrothermal process for the first time. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction, photoluminescence, and cathodoluminescence spectra as well as kinetic decays were used to characterize the samples.

Architectures of Strontium Hydroxyapatite Microspheres: Solvothermal Synthesis and Luminescence Properties

Strontium hydroxyapatite (Sr-5(PO4)(3)OH, SrHAp) microspheres with 3D architectures have been successfully prepared through a efficient and facile solvothermal process. The experimental results indicate that the SrHAP microspheres are composed of a large amount of nanosheets, which are assembled in a radial form from the center to the surface of the microspheres. The as-obtained SrHAp samples show an intense and bright blue emission from 350 to 570 nm centered at 427 nm (CIE coordinates: x = 0.153, y = 0.081; lifetime: 9.2 ns; quantum efficiency: 31%) under long-wavelength UV light excitation (344 nm). This blue emission might result from the CO2 center dot- radical impurities in the crystal lattice. Furthermore, the surfactants CTAB and trisodium citrate have an obvious impact on the morphologies and the luminescence properties of the products, respectively.

Hydrothermal Synthesis and Luminescent Properties of Novel Ordered Sphere CePO4 Hierarchical Architectures

The ordered-sphere CePO4 hierarchical architectures have been successfully synthesized by a simple hydrothermal method through the controlled growth of the CePO4 nanorods and self-assemble hierarchical structure under various reaction conditions. The evolution of the morphology of the samples has been investigated in detail. It was found that the coexistence of citric acid and cetaltrimethylammonium bromide in the reaction system plays an important role in the formation of the spherical CePO4 hierarchical architectures. A possible mechanism of the formation and growth of the hierarchical structure was suggested according to the experimental results and analysis. The effects of the reaction time as well as the variation of the morphologies on the luminescent properties of the products were also studied.

Synthesis and Luminescence Properties of Sheaflike TbPO4 Hierarchical Architectures with Different phase Structures

Sheaflike terbium phosphate hydrate hierarchical architectures composed of filamentary nanorods have been fabricated by a hydrothermal method. The X-ray diffraction patterns and thermogravimetric/differential thermal analysis investigations reveal that the obtained terbium phosphate hydrate has a structural formula of TbPO4 center dot H2O, which can be readily indexed to the hexagonal phase GdPO4 center dot nH(2)O in JCPDS file 39-0232. The evolution of the morphology of the products has been investigated in detail. It is found that the addition of CTAB and Na2H2L (disodium ethylenediamine tetraacetate) plays an important role in controlling the final morphology of the products. A possible formation mechanism of the sheaflike architectures was proposed according to the experimental results and analysis. In addition, the phase structure of the product changes to monoclinic phase when it is annealed at 750 degrees C for 2 h in N-2-H-2 atmosphere. Tetragonal chase TbPO4 can be obtained when annealed temperature increases to 1150 degrees C.

Facile shape-controlled synthesis of luminescent europium benzene-1,3,5-tricarboxylate architectures at room temperature

The large-scale synthesis of the metal-organic framework Eu(1,3,5-BTC)center dot 6H(2)O nanocrystallites with delicate morphologies such as sheaflike, butterflylike, and flowerlike superstructures composed of nanowires have been realized via a simple solution phase method at room temperature. Time-dependent experiments indicate that these superstructures were constructed by the splitting crystal growth mechanism, as has been noted in some minerals in nature. The synthetic parameters such as reaction time, concentration and molar ratio of reactants, surfactant, and reaction temperature all affected the morphology of the Eu(1,3,5-BTC)center dot 6H(2)O architectures. These well-arranged architectures exhibit red emission corresponding to the D-5(0) -> F-7(2) transition of the Eu3+ ions under UV light excitation, and the lifetime is determined to be about 0.22 ms.

Supramolecular architectures, photophysics, and electroluminescence of 1,3,4-oxadiazole-based iridium(III) complexes: From mu-dichloro bridged dimer to mononuclear complexes

One mu-dichloro bridged diiridium complex and three mononuclear iridium(III) complexes based on the 1,3,4-oxadiazole derivatives as cyclometalated ligands and acetylacetonate (acac) or dithiolates O,O'-diethyldithiophosphate (Et(2)dtp) or N,N'-diethyldithiocarbamate (Et(2)dtc) as ancillary ligands have been synthesized and systematically studied by X-ray diffraction analysis. The results reveal that three mononuclear complexes all adopt distorted octahedral coordination geometry around the iridium center by two chelating ligands with cis-C-C and trans-N-N dispositions, which have the same coordination mode as the diiridium dimer. The dinuclear complex crystallizes in the monoclinic system and space group C2/c, whereas three mononuclear iridium complexes are all triclinic system and space group P(1) over bar. In the stacking structure of the dimer, one-dimensional tape-like chains along the b-axis are formed by hydrogen bondings, which are strengthened by pi stacking interactions between phenyl rings of 1,3,4-oxadiazole ligands. Then these chains assemble a three-dimensional alternating peak and valley fused wave-shape structure. In each stacking structure of three mononuclear complexes, two molecules form a dimer by the C-H center dot center dot center dot O hydrogen bondings, and these dimers are connected by pi stacking interactions along the b-axis, constructing a zigzag chain.

Structure characterization and physical properties of a complex with supramolecular architectures Co-2(2,6-DPC2Co(H2O)5 center dot 2H(2)O (DPC=2,6-pyridinedicarboxylate)

Reaction of 2,6-pyridinedicarboxylic with CoCl2 . 6H(2)O in aqueous solution give rise to a three-dimensional Complex CO2(2,6-DPC)(2)Co(H2O)(5).2H(2)O (DPC = 2,6-pyridinedicarboxylate) 1. It has been characterized by elemental analyses, infrared spectra (IR) spectrum, thermogravimetric (TG) analysis, EPR spectrum, and single crystal X-ray diffraction. The complex crystallizes in the P2(1)/c space group with a = 8.3906(3) Angstrom, b = 27.4005(8) Angstrom, c = 9.6192(4) A, alpha = 90.00degrees, beta = 98.327(2)degrees, gamma = 90.00degrees, V = 2188.20(14) Angstrom(3), Z = 4. There are two types of cobalt environments: Co(1) is coordinated by four oxygen atoms from four carboxyl groups and two nitrogen 2 atoms which are all from pdc(2). Co(2) is coordinated by six oxygen atoms, five from coordinated water molecules and one from a carboxyl of pdc(2) - of which the other oxygen atom is linked to the Co(1). The extensive intermolecular hydrogen bonds are formed in the crystal by means of the five coordinated water molecules.

中国古建筑结构力学研究进展

中国古代建筑是中国古代文化的宝贵遗产.力学的多样性也反映在古建筑结构力学研究.西安交通大学从1982年开始,对以西安明代箭楼、城楼和宁波宋代保国寺等国家重点保护文物为代表的木结构建筑,以唐代大雁塔、小雁塔等国家重点保护文物为代表的古代高层建筑,和以国家重点保护文物西安古城墙为代表的砖-土结构以及钟楼、鼓楼等中国城市的代表性古建筑的结构力学特性进行了一系列研究.得到关于古建筑结构(如斗拱、结构非线性、榫卯节点的接触力学特性、地宫、古代夯土、古塔基础、古城墙等)力学特性的新认识.本文对此进行小结,同时也介绍近年来的其它学者的一些研究.

High-Strength Composite Fibers: Realizing True Potential of Carbon Nanotubes in Polymer Matrix through Continuous Reticulate Architecture and Molecular Level Couplings

Carbon nanotubes have unprecedented mechanical properties as defect-free nanoscale building blocks, but their potential has not been fully realized in composite materials due to weakness at the interfaces. Here we demonstrate that through load-transfer-favored three-dimensional architecture and molecular level couplings with polymer chains, true potential of CNTs can be realized in composites as Initially envisioned. Composite fibers with reticulate nanotube architectures show order of magnitude improvement in strength compared to randomly dispersed short CNT reinforced composites reported before. The molecular level couplings between nanotubes and polymer chains results in drastic differences in the properties of thermoset and thermoplastic composite fibers, which indicate that conventional macroscopic composite theory falls to explain the overall hybrid behavior at nanoscale.

Analog-digital and digital-analog converters using single-electron and MOS transistors

This paper proposes two kinds of novel single-electron analog-digital conversion (ADC) and digital-analog conversion (DAC) circuits that consist of single-electron transistors (SETs) and metal-oxide-semiconductor (MOS) transistors. The SET/MOS hybrid ADC and DAC circuits possess the merits of the SET circuit and the MOS circuit. We obtain the SPICE macro-modeling code of the SET transistor by studying and fitting the characteristics of the SET with SPICE simulation and Monte Carlo simulation methods. The SPICE macro-modeling code is used for the simulation of the SET/MOS hybrid ADC and DAC circuits. We simulate the performances of the SET/MOS hybrid 3-b ADC and 2-b DAC circuits by using the H-SPICE simulator. The simulation results demonstrate that the hybrid circuits can perform analog-digital and digital-analog data conversion well at room temperature. The hybrid ADC and DAC circuits have advantages as-follows: 1) compared with conventional circuits, the architectures of the circuits are simpler; 2) compared with single electron transistor circuits, the circuits have much larger load capability; 3) the power dissipation of the circuits are lower than uW; 4) the data conversion rate of the circuits can exceed 100 MHz; and 5) the resolution of the ADC and DAC circuits can be increased by the pipeline architectures.

Double synaptic weight neuron theory and its application

In this paper, a novel mathematical model of neuron-Double Synaptic Weight Neuron (DSWN)(l) is presented. The DSWN can simulate many kinds of neuron architectures, including Radial-Basis-Function (RBF), Hyper Sausage and Hyper Ellipsoid models, etc. Moreover, this new model has been implemented in the new CASSANN-II neurocomputer that can be used to form various types of neural networks with multiple mathematical models of neurons. The flexibility of the DSWN has also been described in constructing neural networks. Based on the theory of Biomimetic Pattern Recognition (BPR) and high-dimensional space covering, a recognition system of omni directionally oriented rigid objects on the horizontal surface and a face recognition system had been implemented on CASSANN-II neurocomputer. In these two special cases, the result showed DSWN neural network had great potential in pattern recognition.

Discussion on the basic mathematical models of neurons - Double synaptic weight neuron in general-purpose neurocomputer, theory and application

Based on the introduction of the traditional mathematical models of neurons in general-purpose neurocomputer, a novel all-purpose mathematical model-Double synaptic weight neuron (DSWN) is presented, which can simulate all kinds of neuron architectures, including Radial-Basis-Function (RBF) and Back-propagation (BP) models, etc. At the same time, this new model is realized using hardware and implemented in the new CASSANN-II neurocomputer that can be used to form various types of neural networks with multiple mathematical models of neurons. In this paper, the flexibility of the new model has also been described in constructing neural networks and based on the theory of Biomimetic pattern recognition (BPR) and high-dimensional space covering, a recognition system of omni directionally oriented rigid objects on the horizontal surface and a face recognition system had been implemented on CASSANN-H neurocomputer. The result showed DSWN neural network has great potential in pattern recognition.

Advances in high power semiconductor diode lasers - art. no. 682402

High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. the latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect,. different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.