Background Limited Performance of Long Wavelength Infrared Focal Plane Arrays Fabricated From M-Structure InAs–GaSb Superlattices

The recent introduction of a M-structure design improved both the dark current and R₀ A performances of type-II InAs-GaSb photodiodes. A focal plane array fabricated with this design was characterized at 81 K. The dark current of individual pixels was measured between 1.1 and 1.6 nA, 7 times lower than previous superlattice FPAs. This led to a higher dynamic range and longer integration times. The quantum efficiency of detectors without antireflective coating was 74%. The noise equivalent temperature difference reached 23 mK, limited only by the performance of the testing system and the read out integrated circuit. Background limited performances were demonstrated at 81 K for a 300 K background.     

Size and morphology-controlled synthesis of mesoporous hydroxyapatite nanocrystals by microwave-assisted hydrothermal method

We report the rapid microwave-assisted hydrothermal synthesis of mesoporous hydroxyapatite (HAp) nanocrystals with controlled size, morphology, and surface area using various organic modifiers as regulators. The products were analyzed for their crystalline nature, phase purity, morphology, particle size and pore size distribution. Results indicated that ascorbic acid, cetyltrimethyl ammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) play an important role to obtain needle like, rod like and fiber like mesoporous HAp nanocrystals with different specific surface area by controlling growth habit of HAp along c-axis. In addition, the prepared samples were B-type carbonated HAp similar to bone minerals. Therefore, the present approach can be a promising way to obtain precursor for making tissue engineering scaffolds, drug/protein delivery carriers and bone fillers with tunable characteristics.     

Modular argumentation for modelling legal doctrines in common law of contract

To create a programming environment for contract dispute resolution, we propose an extension of assumption-based argumentation into modular assumption-based argumentation in which different modules of argumentation representing different knowledge bases for reasoning about beliefs and facts and for representation and reasoning with the legal doctrines could be built and assembled together. A distinct novel feature of modular argumentation in compare with other modular logic-based systems like Prolog is that it allows references to different semantics in the same module at the same time, a feature critically important for application of argumentation in legal domains like contract dispute resolution where the outcomes of court cases often depend on whether credulous or skeptical modes of reasoning were applied by the contract parties. We apply the new framework to model the doctrines of contract breach and mutual mistake.     

B311毛纺精梳机牵伸值的精确计算

本文利用计算机辅助分析的方法,对毛纺精梳机中的喂给机构和拔取机构进行了运动分析,精确求出每一瞬时的牵伸值,为改进机构,提高产品质量提供了依据。     

三角胶带传动动态应力应变测定的研究

三角胶带动态应力应变的试验装置和测量,目前,只能测定带速在2.5米/秒以下(转速最高为350转/分)的传动,与实际中一般应用5米/秒以上的情况尚有距离。本文为提高带速,新设计了简便易行的试验装置。其试验带速达7.5米/秒(转速为1000转/分),甚至可达更高速度。同时,自行设计了专用的测量电路,满足了本试验的需要。文中首次把大应变量金属丝应变片应用于三角胶带测试。由于试验带速的提高,满足了三角胶带实际工作要求,有助于深入研究带的疲劳强度和寿命。     

Disruption of ergosterol biosynthesis,growth, and the morphological transition in <Emphasis Type="Italic">Candida albicans</Emphasis> by sterol methyltransferase inhibitors containing sulfur at C-25 in the sterol side chain

The sterol substrate analog 25-thialanosterol and its corresponding sulfonium salt were evaluated for their ability to serve as antifungal agents and to inhibit sterol methyltransferase (SMT) activity in Candida albicans. Both compounds inhibited cell proliferation, were fungistatic, interrupted the yeastlike-form to germ-tube-form transition, and resulted in the accumulation of zymosterol and related Δ²⁴-sterols concurrent with a decrease in ergosterol, as was expected for the specific inhibition of SMT activity. Feedback on sterol synthesis was evidenced by elevated levels of cellular sterols in treated vs. control cultures. However, neither farnesol nor squalene accumulated in significant amounts in treated cultures, suggesting that carbon flux is channeled from the isoprenoid pathway to the sterol pathway with minor interruption or redirection until blockage at the C-methylation step. Activity assays using solubilized C. albicans SMT confirmed the inhibitors impair SMT action. Kinetic analysis indicated that 25-thialanosterol inhibited SMT with the properties of a time-dependent mechanismbased inactivator K _i of 5 =gmM and apparent k _inact of 0.013 min⁻¹, whereas the corresponding sulfonium salt was a reversible-type transition state analog exhibiting a K _i of 20 nM. The results are interpreted to imply changes in ergosterol homeostasis as influenced by SMT activity can control growth and the morphological transition in C. albicans, possibly affecting disease development.     

Development of novel 1,2,3,4-tetrahydroisoquinoline derivatives and closely related compounds as potent and selective dopamine D3 receptor ligands

Based on N-alkylated 1,2,3,4-tetrahydroisoquinoline derivatives, which are structurally related to the partial agonist BP 897, a series of novel, selective dopamine D3 receptor antagonists has been synthesised. Derivatisation included changes in the arylamide moiety and the tetrahydroisoquinoline substructure leading to compounds with markedly improved selectivities and affinities in the low nanomolar concentration range. From the 55 structures presented here, (E)-3-(4-iodophenyl)-N-(4-(1,2,3,4-tetrahydroisoquinolin-2-yl)butyl)acrylamide (51) has high affinity (Ki(hD3)=12 nM) and a 123-fold preference for the D3 receptor relative to the D2 receptor subtype. Its pharmacological profile offers the prospect of a novel radioligand as a tool for various dopamine D3-receptor-related in vitro and in vivo investigations.     

Investigation of a metal-ionic conductor interface in thin film samples using X-ray photoelectron spectroscopy and electrical measurements

The surface of an evaporated thin film of the ionic conductor β-PbF₂ was analysed using X-ray photoelectron spectroscopy (XPS). The results were compared with those obtained from nuclear and secondary ion mass spectrometry measurements. An analysis of the Au-β-PbF₂ interface shows the presence of a thin layer of partly oxidized metallic lead. Part of this interfacial lead diffused across the gold film towards the external surface where it became bound to oxygen. An electrical analysis of the interface was performed by studying the capacitance as a function of the surface potential. The differences between experimental and calculated values are discussed in the light of the XPS measurements.     

A Comprehensive Approach for Estimating Hydraulic Quantities in a Multi-branched Estuarine System

Despite many previous investigations, there is no theoretically justifiable equation to determine the freshwater discharge, tidal velocity, and salinity in a complex estuary that contains several branches. In this study, the longitudinal distributions of freshwater and salinity concentration in multi-branched estuaries are investigated using a mathematical model, considering the energy balance by frictional head loss and the salt balance by diffusion and advection in a one-dimensional steady-state condition. We attempt to obtain the time-mean freshwater discharge rate quantitatively at a junction where the main flow separates into two branches. The salinity distribution along each branch is calculated by following the dispersion coefficient equation previously proposed for a single estuary. The salinity field is divided into the near-coast region and the upstream region, because in each segment the inland velocity varies according to the tidal flux. For computing the tidal velocity, we propose the Burgers equation and the Hoph-Cole transformation. The theoretical results obtained by these equations were found to be in good agreement with a set of observed data in the Red River estuary system.