Preferential antibody recognition of structurally distinct HIV-1 gp120 molecules

We have developed an assay, using a biosensor matrix and surface plasmon resonance, that rapidly and reproducibly measures antibody reactivity to human immunodeficiency virus type 1 (HIV-1) gp120 in various structural conformations. In particular, antibodies displaying preferential reactivity to a CD4-binding competent ("native," rgp120) or CD4-binding incompetent ("reduced," rcmgp120) monomeric gp120 molecule were distinguished. This technique has advantages over conventional enzyme-linked immunosorbent assay (ELISA) methodology in which it is difficult to control the concentration of protein adsorbed to the ELISA wells and a significant disruption of protein structure occurs on adsorption. A population of gp120 molecules that lacked CD4 receptor binding capacity and bound antibodies specific for reduced gp120 was found in several native gp120 preparations. The relative amount of this CD4-binding incompetent population varied among the various preparations studied. This presence of CD4-binding incompetent molecules within various native recombinant gp120 preparations may have implications for HIV-1 envelope vaccine development. By measuring antibody-binding ratios, several monoclonal antibodies were identified, which, although elicited by immunization with various native gp120 preparations, bound specifically to reduced gp120. The ability to screen antibody specificity against HIV-1 envelope proteins with different conformations will assist in determining the quality of antibodies induced by various HIV-1 envelope vaccine candidates.     

Experimental study of screw connections in CFS-calcium silicate board wall panels

Cold-formed steel (CFS) wall panels with different board materials are used extensively in residential and commercial buildings to resist lateral loads by in-plane shear, in addition to helping the studs resist gravity loads. Generally the screw connection between the board and CFS skeleton frame, which experience shear, dictates the behaviour and strength of such panels. In this paper, details of an experimental study on behaviour and strength of the screw connections between the cold-formed steel profiles and calcium silicate boards, under monotonic and cyclic shear loading, are presented. The objectives of the experimental study are: (a) to develop a new test procedure that realistically represents the behaviour and failure of screw connections in CFS wall panels; (b) to investigate the effect of edge distance of the screws and thickness of the boards on behaviour and strength; (c) to study behaviour under monotonic and cyclic loading; (d) to develop the values of the important parameters that determine the load–deformation behaviour of the screw connection in such wall panels under in-plane shear; and (e) to develop design equation to evaluate the ultimate shear strength and its resistance factor required in load resistance factor design (LRFD).     

Hydrocarbon sorption properties of pure silica MCM-22 type zeolite

The adsorption properties of the MWW compositional end member, ITQ-1, have been explored empirically and via computer simulation using n-hexane, 3-methylpentane, 2,3-dimethylbutane, p-xylene and ethylbenzene as adsorbate probes. n-Hexane and 3-methlypentane diffuse rapidly and both have a sorption limit of four molecules per unit cell, three of which are in the large channel cavities. 2,3-dimethylbutane sorbs more slowly through the 10-ring windows; the limiting three molecules per unit cell are all in the large cavities. The two aromatics adsorb in both channel systems, with p-xylene diffusing rapidly and ethylbenzene more slowly but much faster than 2,3-dimethylbutane. No clear distinction between intra- and extra-crystalline adsorption was observed. Computer modeling indicated distinctions between the two channel systems.     

Enhancement of biogas generation during co-digestion of tannery solid wastes through optimization of mix proportions of substrates

Tanneries in India face the twin problems of managing process solid waste and treatment of effluent plant sludge. The present study covered (i) significance of optimization of mix proportions of substrates i.e., fleshings (F) and the primary sludge (PS) and secondary sludge (SS) generated during treatment of tannery wastewater (ii) residence time during co-digestion for enhancement of biogas generation and (iii) digestate analysis. Maximum biogas generation of 385 mL/g of VS_added was observed for the mix proportion of 1.00:2.70:0.30 (F:PS:SS) and a residence time of 45 days during co-digestion of tannery solid wastes. Biogas generation was enhanced by increasing the proportion of PS to SS. After digestion, secondary metabolites i.e., primary, secondary, and tertiary alcohols, amino acids, methane, and ammonia were observed from FT-IR analysis. The exothermic reaction was observed at around 175 °C and when C/N ratio of digestate was around 8.0.     

Combined advanced oxidation and biological treatment of tannery effluent

During leather processing in tanneries, considerable amount of wastes with organic and inorganic pollutants are generated. For removal of these pollutants and recovery of water, biological treatment methods and reverse osmosis (RO) based membrane technologies are adopted. While recovering water from treated tannery effluent using RO membranes, presence of residual organics, dye molecules, and other impurities in the effluent have been reported as the major drawback which leads to membrane fouling and failure. In this study, an attempt was made to improve the quality of the treated tannery effluent by subjecting the secondary treated tannery effluent by ozonation alone and ozonation of primary and secondary treated tannery effluent followed by aerobic biological Sequential Batch Reactor (SBR). Maximum color reduction of 98% at pH value of 12 with ozonation alone was observed for secondary treated tannery effluent. Ozonation of secondary treated tannery effluent followed by further biological treatment in aerobic SBR increased the chemical oxygen demand (COD) removal rate and resulted in COD values less than 300 mg/L. In case of primary treated tannery effluent, maximum COD reduction of 64% was achieved in SBR.     

Effect of Pricing Intervals on Congestion-Sensitivity of Network Prices

One of the key issues for implementing congestion pricing is the pricing granularity (i.e. pricing interval or time-scale). The Internet traffic is highly variant and hard to control without a mechanism that operates on very low time-scales, i.e. on the order of round-trip-times (RTTs). However, pricing naturally operates on very large time-scales because of human involvement. Moreover, structure of wide-area networks does not allow frequent price updates for many reasons, such as RTTs are very large for some cases. In this paper, we investigate the issue of pricing granularity and identify problems. We first focus on how much level of control over congestion can be achieved by congestion pricing. To represent the level of control over congestion, we use correlation between prices and congestion measures. We develop analytical and statistical models for the correlation. In order to validate the correlation model, we develop packet-based simulation of our congestion pricing scheme Dynamic Capacity Contracting. We then present the fit between simulation results of the pricing scheme and the correlation model. The correlation model reveals that the correlation degrades at most inversely proportional to an increase in the pricing interval. It also reveals that the correlation degrades with an increase in mean or variance of the traffic. Secondly, we discuss implications of the correlation model. According to the model and simulation results, we find that control of congestion by pricing degrades significantly as pricing granularity increases.     

Accumulation-based congestion control

This paper generalizes the TCP Vegas congestion avoidance mechanism and uses accumulation , buffered packets of a flow inside network routers, as a congestion measure based on which a family of congestion control schemes can be derived. We call this model Accumulation-based Congestion Control (ACC), which fits into the nonlinear optimization framework proposed by Kelly. The ACC model serves as a reference for packet-switching network implementations. We show that TCP Vegas is one possible scheme under this model. It is well known that Vegas suffers from round trip propagation delay estimation error and reverse path congestion. We therefore design a new Monaco scheme that solves these problems by employing an out-of-band, receiver-based accumulation estimator, with the support of two FIFO priority queues from the (congested) routers. Comparisons between these two schemes demonstrate that Monaco does not suffer from the problems mentioned above and achieves better performance than Vegas. We use ns-2 simulations and Linux implementation experiments to show that the static and dynamic performance of Monaco matches the theoretic results. One key issue regarding the ACC model in general, i.e., the scalability of bottleneck buffer requirement, and a solution using a virtual queueing algorithm are discussed and evaluated.     

软件无线电：总体设计思路和数字硬件选择探讨

This paper reviews the requirements for Software Defined Radio (SDR) systems for high-speed wireless applications and compares how well the different technology choices available- from ASICs, FPGAs to digital signal processors (DSPs) and general purpose processors (GPPs) - meet them.     

Strength of cold-formed lipped channel beams under interaction of local,distortional and lateral torsional buckling

Cold-formed thin-walled lipped channel steel beams may undergo buckling modes such as short half-wavelength local buckling, intermediate half-wavelength distortional buckling and long half-wavelength lateral-torsional buckling or a combination of these before failure. ABAQUS software based on finite element analysis is used to analyse the interaction behaviour of these buckling modes in this study. The finite element model, after calibration with experimental results available in the literature, is used to perform parametric studies, to evaluate the behaviour and strength of such beams under different types of interactions due to variation of material and member properties. The large volume of synthetic data thus generated over a range of failure modes along with the available test results are used to evaluate different equations for calculating the strength of such cold-formed lipped channel beams. Based on the comparison, a method for the design of lipped channel beams failing under the interaction of local, distortional and overall lateral torsional buckling is recommended.