Dark spatial solitons sequence in the biased centrosymmetric photorefractive crystal

We theoretically investigate the evolution of dark screening spatial solitons originating from the quadratic electro-optic effect in biased centrosymmetric photorefractive (CP) crystal by using beam propagation method (BPM). The results indicate that the multiple dark solitons sequence can be obtained in the CP crystal with the odd or even initial conditions. If the initial width of the dark notch is smaller, only a fundamental soliton or a Y-junction soliton pair is generated. When the initial width of the dark notch and the bias electric field are increased, the multiple dark spatial solitons sequence is formed, which realized a progressive transition from a low-order soliton to a higher-order solitons sequence in both odd and even conditions. The solitons characteristic is similar to that of screening solitons in the non-centrosymmetric photorefractive (NCP) crystals.     

液化气体长管拖车与压缩气体长管拖车的异同探讨

主要针对液化气体长管拖车和压缩气体长管拖车在适用标准、制造和结构形式、安全装置的设置、充装和使用以及安全泄放面积计算等方面进行了论述。结果表明:液化气体长管拖车和压缩气体长管拖车在适用标准、制造和结构形式以及安全装置是否设置方面是相同的,但是在充装系数选择以及充装使用和安全泄放面积的计算方面是不同的。     

Isolation and characterization of seven quorum quenching bacteria for biofouling control in MBR

Recently, interspecies quorum quenching (QQ) by bacteria has been reported as a novel approach in biofouling control in membrane bioreactor (MBR) for wastewater treatment. In this study, seven QQ bacteria, named RO1 to RO7, were isolated from fouling reverse osmosis (RO) membrane and were encapsulated in the microbial filters for biofouling control in MBR. Results showed that all isolates have extracellular QQ activity, and RO1 to RO6 were characterized as heat-stable enzymatic degradation of N-acyl homoserine lactones (AHLs), while RO7 was mainly pH-dependent. Analysis of the 16S rRNA gene indicated that RO7 was a species of Pseudomonas sp., others belonged to the species of Bacillus, Stenotrophomonas maltophilia and Delftia tsuruhatensis, respectively. Then, the microbial filters encapsulated each isolate were applied in a laboratory-scaled MBR and proved the substantial inhibition effect on membrane biofouling except for RO7, indicating that QQ bacteria employing enzymes to degrade AHLs have great potential in biofouling control in MBR.     

活化温度对兰炭基活性炭结构与性能的影响

以兰炭末为原料采用KOH高温活化法制备活性炭,重点研究了活化温度对活性炭结构与性能的影响。采用SEM、红外光谱对活性炭的表面形貌及表面结构进行表征。研究表明,随着活化温度的升高,活性炭的收率逐渐减小,碘吸附值先增大后减小。当活化温度为800℃时,活性炭的收率为70%,碘吸附值最大可达到733.482mg/g。SEM及FT-IR分析表明,高温下KOH的扩孔作用主要由表面向活性炭的内部纵深发展,最终会使活性炭形成规则的层状、蜂窝状孔隙结构,并且表面含有大量的羟基、羰基等活性基团。     

浅谈环氧沥青材料研究应用现状

由于环氧沥青材料的优异特性,对该材料的研究已成为各国研究人员的焦点。本文介绍了环氧沥青的应用背景、定义及其混合料性能;概述了国内外在环氧沥青材料研究领域的现状与进展;指出了该材料在应用发展中可能存在的问题并给出相应的建议。     

Web‐Like Interconnected Carbon Networks from NaCl‐Assisted Pyrolysis of ZIF‐8 for Highly Efficient Oxygen Reduction Catalysis

The oxygen reduction reaction (ORR) is under intense research due to its significance in energy storage and conversion processes. Recent studies show that interconnected and hierarchically porous structures can further enhance ORR kinetics as well as catalyst durability, but their preparation can be quite time and/or chemical consuming. Here, a simple approach is reported to prepare such complex structures by pyrolyzing composites containing NaCl and ZIF‐8. The templating effect of molten NaCl connects ZIF‐8 particles into web‐like carbon networks. During ORR activity measurements, it achieves a 0.964 V onset potential and a 38 mV dec^?1 Tafel slope, which are comparable to those of the benchmark Pt/C (0.979 V and 40 mV dec^?1). Due to the metal‐free feature, this catalyst exhibits a 16 mV shift in half‐wave potential after a 10 000‐cycle durability test, which is only 60% of that of Pt/C. The catalyst is also tested in Zn–air batteries and the assemblies are able to work at above 1.2 V for 140 h, which triples the life held by those with Pt/C. This study demonstrates a facile strategy to prepare metal‐free ORR catalysts with interconnectivity and hierarchical porosity, and proves their great potentials in ORR catalysis and Zn–air batteries.     

无线网技术的区域家庭防盗报警系统

设计了一种新的区域家庭智能防盗报警系统,利用单片机控制技术、无线传感器网络技术和GSM移动通信技术,实现具有联网功能的区域智能防盗报警系统。无线防盗报警探头采用红外热释电传感器和振动传感器双重监测原理确认盗贼是否入侵,并以无线数据传输方式将报警信息传送给家庭报警主机,家庭报警主机再将报警信息通过短信的方式发送到用户手机、小区或地区报警主机上。报警信息发送及时,准确可靠。家庭报警主机可以设置无线防盗报警探头的数量和安装位置等信息,还可以设置报警用户电话、小区或地区报警中心电话。整个报警网络大小可以灵活配置,而且传感器采用无线方式布局,不需室内布线。     

Effects of Perceived Interactivity,Perceived Web Assurance and Disposition to Trust on Initial Online Trust

We developed an interdisciplinary model to examine how online consumers' perceived interactivity, perceived Web assurance and disposition to trust affect their initial online trust. Perceived interactivity is theorized as an interpersonal‐based antecedent, disposition to trust as a personality‐based antecedent, and perceived Web assurance as an institution‐based antecedent to initial online trust. Results indicate that both consumers' perceived interactivity and perceived Web assurance positively influence their initial online trust. Therefore, it is of importance that e‐vendors make efforts to enhance online consumers' perceived interactivity of their Web sites as well as addressing consumers' major trust concerns by adopting third‐party Web assurance seals.     

可持续性住宅设计的低技术策略——巴特罗之家(Casa Batllo)自然通风设计的启示

在新时期倡导节能和环保的可持续性发展观的背景下,针对住宅建筑的经济性原则和高新技术的高成本问题,提出多管齐下、从低技术创新的角度来回应建筑的可持续性设计问题,实现生态住宅的可消费性。通过对早期生态住宅的典范——巴特罗公寓通风设计的研析,展示了低技术策略的创造性价值和非常规思路;同时通过重新审视自然通风这一传统技术的现实意义及其在现代生态住宅设计中的应用潜力,借鉴巴特罗公寓的创新启示,提倡在当代可持续性住宅设计中进一步拓展低技术思路。