A Scalable Parallel Algorithm for Reachability Analysis of Very Large Circuits

This paper presents a scalable method for parallelizing symbolic reachability analysis on a distributed-memory environment of workstations. We have developed an adaptive partitioning algorithm that significantly reduces space requirements. The memory balance is maintained by dynamically repartitioning the state space throughout the computation. A compact BDD representation allows coordination by shipping BDDs from one machine to another. This representation allows for different variable orders in the sending and receiving processes. The algorithm uses a distributed termination protocol, with none of the memory modules preserving a complete image of the set of reachable states. No external storage is used on the disk. Rather, we make use of the network, which is much faster.We implemented our method on a standard, loosely-connected environment of workstations, using a high-performance model checker. Initial performance evaluation of several large circuits shows that our method can handle models too large to fit in the memory of a single node. The partitioning algorithm achieves reduction in space, which is linear in the number of workstations employed. A corresponding decrease in space requirements is measured throughout the reachability analysis. Our results show that the relatively slow network does not become a bottleneck, and that computation time is kept reasonably small.     

Effect of Bilayer Phospholipid Composition and Curvature on Ligand Transfer by the α-Tocopherol Transfer Protein

We report here our preliminary investigations on the mechanism of α-TTP-mediated ligand transfer as assessed using fluorescence resonance energy transfer (FRET) assays. These assays monitor the movement of the model α-tocopherol fluorescent derivative ((R)-2,5,7,8-tetramethyl-chroman-2-[9-(7-nitro-benzo[1,2,5]oxadiazol-4-yl amino)-nonyl]-chroman-6-ol; NBD-Toc) from protein to acceptor vesicles containing the fluorescence quencher TRITC-PE. We have found that α-TTP utilizes a collisional mechanism of ligand transfer requiring direct protein–membrane contact, that rates of ligand transfer are greater to more highly curved lipid vesicles, and that such rates are insensitive to the presence of anionic phospholipids in the acceptor membrane. These results point to hydrophobic features of α-TTP dominating the binding energy between protein and membrane. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. An erratum to this article can be found at     

Closed channel fabrication using micromolding of metallic glass

Casting and molding are attractive options for low cost mass production. Metallic glasses may avoid many of the problems associated with micromolding of metals such as high temperatures and pressures, costly mold production, and shrinkage due to crystallization. In this study, we have produced 100 μm², enclosed channels in metallic glass using a novel multilayer Si stack micromolding process. Scanning electron microscope (SEM) images of the enclosed channels are provided to verify that the closed channels extended through the sample.     

Application of the concentration-dependent surface diffusion model on the multicomponent fixed-bed adsorption systems

The ability of bone char to adsorb three metal ions, namely, cadmium, copper and zinc, from effluents in fixed beds has been studied. Two binary metal ion sorption systems, Cd+Cu and Cu+Zn, have been investigated. The variables studied include metal ion solution flowrate, initial metal ion concentration, and bone char particle size bed height. The experimental breakthrough curves for each binary system were measured at five bed heights.A multicomponent film-surface diffusion model has been developed to predict the breakthrough curves by incorporating the IAS for both the Langmuir and the Sips equations, since they both correlate the single component equilibrium isotherm data well. A novel development is the modification of the solution methodology, previously restricted to a constant diffusivity, to incorporate a variable diffusivity correlated with adsorbent coverage by the constant self-diffusivity. The self-diffusivities for the metal ions have been evaluated.     

Choice coordination with limited failure

The Choice Coordination Problem requiresn asynchronous processes to reach a common choice of one out ofk possible alternatives. Processes communicate viak shared variables. Up tot, t, of the processes may fail to operate by suddenly quitting the protocol. Rabin (1982) presented lower and upper bounds for the extreme caset=n–1. We present deterministic and randomized algorithms for arbitraryt using an alphabet of sizeO(t ²). A semi-synchronous model is also studied. A reduction to a consensus problem proves the necessity to assume some powerful atomic shared-memory operations.     

Low-Speed Atomistic Simulation of Stick–Slip Friction using Parallel Replica Dynamics

Atomic stick–slip friction has been predicted by molecular dynamics simulation and observed in experiments. However, direct quantitative comparison of the two has thus far not been possible because of the large difference between scanning velocities accessible to simulations and experiments. In general, the slowest sliding speeds in MD simulations are at least five orders of magnitude larger than the upper limit available to experimentalists. To take a step toward bridging this gap, we have applied parallel replica dynamics, an accelerated molecular dynamics method, to the simulation of atomic stick–slip. The method allows molecular simulations to run parallel in time in order to extend their duration, thereby enabling lower scanning velocities. We show here that this method is able to predict atomic stick–slip friction accurately and efficiently at scanning speeds several orders of magnitude slower than standard molecular dynamics simulations. The accuracy and usefulness of this method is illustrated by correct prediction of the logarithmic dependence of friction on velocity.     

绿色电镀技术系统示范项目

根据生产实践和现场数据,详细介绍了安美特公司配合中国环境保护产业协会和中国表面工程协会共同启动的"绿色电镀技术示范项目"的实施状况.该示范项目的核心内容是包括前处理、锌合金电镀及后处理在内的防腐蚀镀层组合实用技术.经被试点电镀企业投放于大生产实践的长期使用,该示范项目取得了上佳的环境和经济效益:单位水耗降低了85%,单位能耗降低了65%;电镀废水中COD减少了50%,电镀速率提高了50%,产品一次合格率从90%提高到98%;钝化液中锌杂质削减了65%～95%,铁杂质削减了85%～95%,而且彻底杜绝了锌镍合金电镀过程中氰化物的产生.     

Quantum‐Dot‐Functionalized Poly(styrene‐co‐acrylic acid) Microbeads: Step‐Wise Self‐Assembly,Characterization, and Applications for Sub‐femtomolar Electrochemical Detection of DNA Hybridization

A novel nanoparticle label capable of amplifying the electrochemical signal of DNA hybridization is fabricated by functionalizing poly(styrene‐co‐acrylic acid) microbeads with CdTe quantum dots. CdTe‐tagged polybeads are prepared by a layer‐by‐layer self‐assembly of the CdTe quantum dots (diameter = 3.07 nm) and polyelectrolyte on the polybeads (diameter = 323 nm). The self‐assembly procedure is characterized using scanning and transmission electron microscopy, and X‐ray photoelectron, infrared and photoluminescence spectroscopy. The mean quantum‐dot coverage is (9.54 ± 1.2) × 10³ per polybead. The enormous coverage and the unique properties of the quantum dots make the polybeads an effective candidate as a functionalized amplification platform for labelling of DNA or protein. Herein, as an example, the CdTe‐tagged polybeads are attached to DNA probes specific to breast cancer by streptavidin–biotin binding to construct a DNA biosensor. The detection of the DNA hybridization process is achieved by the square‐wave voltammetry of Cd²⁺ after the dissolution of the CdTe tags with HNO₃. The efficient carrier‐bead amplification platform, coupled with the highly sensitive stripping voltammetric measurement, gives rise to a detection limit of 0.52 fmol L^?1 and a dynamic range spanning 5 orders of magnitude. This proposed nanoparticle label is promising, exhibits an efficient amplification performance, and opens new opportunities for ultrasensitive detection of other biorecognition events.     

Determination of vertical daylight illuminance under non-overcast sky conditions

In a dense urban region in which high-rise buildings are packed inside limited land areas, the daylight components reflected from ground and surrounding buildings play significant roles in daylighting design. The natural light available in an interior strongly depends on the amount of daylight reaching the window facades. Lately we proposed a calculation procedure, presented in form of simple mathematical expressions and diagrams, to determine the daylight illuminance on a vertical plane under overcast skies. This paper extends the study to non-overcast sky conditions. The performance of the proposed method was evaluated by comparison with the daylight illuminance simulated by a lighting software, namely RADIANCE, and with measurements under real skies. It was found that the data estimated by the proposed method were in good agreement both with the values simulated by RADIANCE and with the measured results. The paper offers to architects and building engineers a useful tool for estimating the daylight illuminance and in particular for determining and assessing various daylighting schemes and concepts during design and construction stages.     

Single Nanoparticle Magnetic Spin Memristor

There is an increasing demand for the development of a simple Si‐based universal memory device at the nanoscale that operates at high frequencies. Spin‐electronics (spintronics) can, in principle, increase the efficiency of devices and allow them to operate at high frequencies. A primary challenge for reducing the dimensions of spintronic devices is the requirement for high spin currents. To overcome this problem, a new approach is presented that uses helical chiral molecules exhibiting spin‐selective electron transport, which is called the chiral‐induced spin selectivity (CISS) effect. Using the CISS effect, the active memory device is miniaturized for the first time from the micrometer scale to 30 nm in size, and this device presents memristor‐like nonlinear logic operation at low voltages under ambient conditions and room temperature. A single nanoparticle, along with Au contacts and chiral molecules, is sufficient to function as a memory device. A single ferromagnetic nanoplatelet is used as a fixed hard magnet combined with Au contacts in which the gold contacts act as soft magnets due to the adsorbed chiral molecules.