The Social Integration of a Myrmecophilous Spider Does Not Depend Exclusively on Chemical Mimicry

Numerous animals have evolved effective mechanisms to integrate into and exploit ant societies. Chemical integration strategies are particularly widespread among ant symbionts (myrmecophiles), probably because social insect nestmate recognition is predominantly mediated by cuticular hydrocarbons (CHCs). The importance of an accurate chemical mimicry of host CHCs for social acceptance recently has been demonstrated in a myrmecophilous silverfish. In the present study, we investigated the role of chemical mimicry in the myrmecophilous spider Gamasomorpha maschwitzi that co-occurs in the same host, Leptogenys distinguenda, as the silverfish. To test whether spiders acquire mimetic CHCs from their host or not, we transferred a stable isotope-labeled hydrocarbon to the cuticle of workers and analyzed the adoption of this label by the spiders. We also isolated spiders from hosts in order to study whether this affects: 1) their chemical host resemblance, and 2) their social integration. If spiders acquired host CHCs, rather than biosynthesizing them, they would be expected to lose these compounds during isolation. Spiders acquired the labeled CHC from their host, suggesting that they also acquire mimetic CHCs, most likely through physical contact. Furthermore, isolated spiders lost considerable quantities of their CHCs, indicating that they do not biosynthesize them. However, spiders remained socially well integrated despite significantly reduced chemical host similarity. We conclude that G. maschwitzi depends less on chemical mimicry to avoid recognition and aggressive rejection than the silverfish previously studied, suggesting that the two myrmecophiles possess different adaptations to achieve social integration.     

高纯度二甲基二烯丙基氯化铵的制备

以二甲胺和烯丙基氯为原料,制备高纯度二甲基二烯丙基氯化铵(DMDAAC).将第一阶段(叔胺化反应)分两步投料:第一步是二甲胺与烯丙基氯按物质的量的比为1∶0.5投料;第二步是继续滴加烯丙基氯和氢氧化钠,投料比为n(二甲胺)∶n(烯丙基氯)∶n(氢氧化钠)=1∶0.5∶1.采用气相色谱和pH酸度计监控传统一步法与该合成方法,并以聚合产物聚二甲基二烯丙基氯化铵(PDMDAAC)的特征粘度衡量DMDAAC聚合性能.结果表明,第一阶段体系维持pH≤l1,该合成方法所得DMDAAC中各杂质的含量均下降了60％ ～ 70％,季胺化反应控制在6h为宜,PDMDAAC特征粘度稳定在1.6 ～2.2 dL/g,DMDAAC聚合性能较好.     

Analysis of pork adulteration in commercial meatballs targeting porcine-specific mitochondrial cytochrome b gene by TaqMan probe real-time polymerase chain reaction

A test for assessing pork adulteration in meatballs, using TaqMan probe real-time polymerase chain reaction, was developed. The assay combined porcine-specific primers and TaqMan probe for the detection of a 109 bp fragment of porcine cytochrome b gene. Specificity test with 10 ng DNA of eleven different species yielded a threshold cycle (Ct) of 15.5 ± 0.20 for the pork and negative results for the others. Analysis of beef meatballs with spiked pork showed the assay can determine 100-0.01% contaminated pork with 102% PCR efficiency, high linear regression (r(2) = 0.994) and ≤ 6% relative errors. Residuals analysis revealed a high precision in all determinations. Random analysis of commercial meatballs from pork, beef, chicken, mutton and goat, yielded a Ct between 15.89 ± 0.16 and 16.37 ± 0.22 from pork meatballs and negative results from the others, showing the suitability of the assay to determine pork in commercial meatballs with a high accuracy and precision.     

考虑频率相关参数的直流输电线路故障特征分析

目前高压直流输电线路利用行波波头的上升速率构成保护判据,由于长距离线路频率相关特性对高频信号的衰减作用较强,导致保护的灵敏性不足。利用零极点法分析线路故障暂态信号的频率特性,发现故障电气量的高频分量中包含位置主频和边界主频。高频暂态量由边界主频和位置主频共同作用产生。区内、外故障的特征差异取决于反射系数频率特性的通带和透射系数频率特性的阻带,因此特征频带应为透射系数阻带的截止频率与反射系数通带的最高频率间的频带。由PSCAD仿真结果证明,区内、外故障时电流在此特征频带内差异明显。     

Enhanced optical and electrical stability of thermally carbonized porous silicon

In the current paper, the intrinsic instability of physical properties of porous silicon (PS) was minimized using a thermal carbonization (TC) method. A typical PS showed an obvious quenching of its photoluminescence (PL) properties under long-term laser radiation. To resolve this problem, an ultra-thin stabilizing layer was grown on the porous structure under an acetylene gas flow. During the TC process at high temperatures, carbon atoms were detached from the acetylene molecules and dissolved in the porous structure. Thermally carbonized PS (TC-PS) layer changed the PL peak position of PS slightly due to the formation of Si–C species on porous surface after acetylene exposure. The effects of TC-PS layer in electrical properties of fabricated photodetectors were studied. The photocurrent of freshly prepared PS decreased under prolonged green laser radiation (532 nm, 5 mW), but the TC-PS sample showed more stable electrical characteristics under the same conditions.     

基于1553B总线的仿真测试软件的设计与实现

主要阐述了1553B总线的特点,数据结构总线特性。结合Condor公司的PCMCIA接口的PCCARD-1553B板卡和支持此板卡的源代码级API函数,给出一个通用1553B总线接口总线控制器端仿真测试软件的设计思想、方法和详细过程。该软件已应用于对特定航电设备的测试工作,稳定可靠、适应性强,可满足不同的测试需求。     

The behaviour of adhesively bonded beams versus their welded equivalent

The study aims to produce a design guide for the calculations of stresses and deflections of adhesively bonded beams fabricated from steel adherends using a structural epoxy adhesive. Such design calculations already exist for welded but not for bonded beams. Small models based on beams with a T-section profile, at various beam lengths, are formulated. A key to these calculations is the determination of the adhesive/adherend interface factors/coefficients, to correct the estimated values of stress and deflection from three-point bending conditions. This article presents the methodology for evaluating bonded beams in relation to equivalent welded (solid) beams. This includes mechanical testing, an analytical method based on beam and sandwich theory, and finite element techniques. Results from these techniques are presented and compared and values of the coefficients for T-section beams are determined.     

Preparation of carboxymethyl sago pulp hydrogel from sago waste by electron beam irradiation and swelling behavior in water and various pH media

Solutions of carboxymethyl sago pulp (CMSP) of various degree of substitution were irradiated with electron beam of various radiation doses. The gelation dose (D_g) and p_o/q_o ratio (p_o is degradation density, q_o is crosslinking density) is dependent on CMSP concentration and degree of substitution. In the range of concentrations of 10% to 80% (w/v) CMSP with degree of substitutions of 0.4, 0.6, and 0.8, the p_o/q_o ratio decreases with increasing %CMSP showing that crosslinking processes are dominating and increasing the gel network of the CMSP hydrogel. The fourier transform infrared spectra of CMSP hydrogels of degree of substitutions of 0.4, 0.6, and 0.8 with percentage of gel fractions 25, 35, and ≥ 40 show differences in the intensity of the absorption bands at 1020–1100, 1326, and 1422 cm^?1 with different degree of substitutions and percentage of gel fraction (%GF) that correspond to different extents of chain scission and crosslinking. The swelling behavior in water shows that CMSP hydrogels could absorb 3500–5300% of water by 1 g of CMSP hydrogel. The ability to absorb water increases with the decrease of degree of substitution and %GF of the CMSP hydrogels. It is also observed that the optimum pH for swelling CMSP hydrogel is at pH 7. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

无线传感器网络k点连通可靠性的研究

无线传感器网络的出现引起了人们的广泛关注,由于无线传感器网络的节点不是预先定位而是随机撒放,那么如何保证一定区域内的传感器节点在满足连通可靠性要求的情况下连结成一张网络?而若干次随机抛撒所形成网络的连通度的平均值与网络的节点个数、节点的通讯半径之间又有何关系?通过计算机仿真模拟试验,给出了网络的k(k>0)连通度概率分布曲线;引入了连通度的数学期望概念来描述若干次抛撒所形成网络的连通度k的平均值,给出了其随网络节点个数、节点通讯半径变化的回归方程;给出了无线传感器网络k点连通概率曲线和3点连通的经验公式;分析了边界节点对网络连通度的影响.这些对无线传感器网络节点个数和节点通讯半径的选择、系统冗余设计等都具有重要的指导意义或参考价值.     

Effects of cold setting adhesives on properties of laminated veneer lumber from oil palm trunks in comparison with rubberwood

In this study, the properties of laminated veneer lumber (LVL) made from oil palm trunks (OPT) were evaluated in comparison with rubberwood using cold setting adhesives, namely, emulsion polymeric isocyanate (EPI) and polyvinyl acetate (PVAc). The evaluations were based on either dry or after cold water, hot water and cyclic pre-treatment. The density of the OPT LVL was slightly higher than that of solid OPT. Thickness swelling and water absorption of OPT LVL were greater than of rubberwood LVL. Pre-treatment increased the water absorption and thickness swelling. The OPT LVL bonded with EPI without toluene showed greater water absorption and thickness swelling than EPI with toluene. Pre-treatment significantly reduced the tensile strength of OPT LVL. The OPT LVL bonded with EPI without toluene showed higher tensile shear strength, but a greater reduction of tensile shear strength after pre-treatment, than the OPT LVL bonded with EPI and toluene. The PVAc adhesive had greater wettability than the EPI. The EPI without toluene showed a lower contact angle than the EPI with toluene. The loose side of the OPT veneer was found to have greater wettability than the tight side.