Corrosion inhibition of triethanolammonium bromide mono- and dibenzoate as cationic inhibitors in an acidic medium

A weight loss technique was used to determine the corrosion inhibition efficiency of synthesized alkyl mono-and dibenzoate triethanolammonium bromide derivatives (TEAMB, TEADB) in an acidic medium (2 N HCl) at different doses (50, 100, and 200 ppm). The results showed that monoderivatives had a higher corrosion inhibition efficiency than diderivatives. The results were correlated with several factors, including the alkyl chain length of the hydrophobic chains, interfacial tension (IT), critical micelle concentration (CMC), and adsorption free energy of these inhibitors. Increasing the geometric length of the alkyl chains in the synthesized inhibitors had an increasing effect on their corrosion inhibition efficiency, whereas decreasing the CMC and IT had an increasing effect on their tendency toward corrosion inhibition. The number of hydrophobic chains attached to the inhibitor molecules had a vital influence on their efficiency as corrosion inhibitors.     

Drug self-assembly: A phenomenon at the nanometer scale with major impact in the structure–biological properties relationship and the treatment of disease

Under water-rich conditions, small amphiphilic and hydrophobic drug molecules self-assemble into supramolecular nanostructures. Thus, substantial modifications in their interaction with cellular structures and the ability to reach intracellular targets could happen. Additionally, drug aggregates could be more toxic than the non-aggregated counterparts, or vice versa. Moreover, since self-aggregation reduces the number of effective “monomeric” molecules that interact with the target, the drug potency could be underestimated. In other cases, the activity could be ascribed to the non-aggregated molecule while it stems from its aggregates. Thus, drug self-assembly could mislead from drug throughput screening assays to advanced preclinical and clinical trials. Finally, aggregates could serve as crystallization nuclei. The impact that this phenomenon has on the biological performance of active compounds, the inconsistent and often controversial nature of the published data and the need for recommendations/guidelines as preamble of more harmonized research protocols to characterize drug self-aggregation were main motivations for this review. First, the key molecular and environmental parameters governing drug self-aggregation, the main drug families for which this phenomenon and the methods used for its characterization are described. Then, promising nanotechnology platforms investigated to prevent/control it towards a more efficient drug development process are briefly discussed.     

Adopt,adapt, abandon: Understanding why some young adults start,and then stop,using instant messaging

Instant messaging (IM) has become a popular and important mode of staying in touch for teens and young adults. It allows for easy, frequent and lightweight interaction that contributes to building and sustaining friendships, as well as coordinating social activities. Despite the initial appeal of IM, however, some have found it too distracting and have changed their usage or abandoned it. I interviewed 21 former users of IM about their adoption, usage and eventual abandonment of the technology. Results show that participants were initially attracted to features of IM that enabled them to maximize their use of leisure time via easy and frequent interaction with their friends, but that, in a different usage context, these same features became distracting and annoying. Participants adapted their behavior to avoid these drawbacks, but IM did not support these adaptations effectively. In particular, IM did not allow for control over interruptions, which became more important as their contact lists grew and social time became scarce; and they ultimately abandoned the technology. These results point to a need for understanding use beyond adoption, and a theoretical and practical focus on understanding the adaptation and changing utility that accompany long-term usage of technologies.     

Experiencing flow with instant messaging and its facilitating role on creative behaviors

The goal of this study is to explore how experiencing flow with IM, an Internet-based communication technology, can facilitate an individual’s perception on creativity. We argue that certain capabilities in IM, telepresence and perceived control, provide users a means to experience flow. We further investigate whether flow and its outcomes, positive affect and exploratory behavior have any influence on the perception of creativity of the users. Using an online survey with 207 observations we found that user’s perceived control over the technology and its ability to transport the user to a virtual environment were shown to facilitate the experience of flow. We found that flow in itself does not influence perceived expected creativity in its users but does indirectly influence perceived expected creativity through exploratory behavior and positive affect. From these initial findings we believe that our study provides implications for both users and designers on IT. Furthermore, managers can apply the findings during implementation and use of interactive information technologies for communications in the workplace.     

荧光探针法研究结构明确的BzO-PDMAEMA均聚物水溶液性质

通过氧阴离子聚合合成了一系列不同相对分子质量的结构明确的BzO—PDMAEMA，用芘作为荧光探针研究了BzO—PDMAEMA在水溶液中的胶束化行为，发现CMC值与用表面张力法测得的结果相一致，即随BzO—PDMAEMA相对分子质量的增加而减小，但荧光探针法测得的CMC值稍大；LCST值则随相对分子质量的增加而增加。     

网络交际与语言学研究新视角

计算机网络不仅为人类提供了一种新型的交流工具,而且为人类交往开辟了新的空间。网络交际具备全球性、跨文化性、双向互动和平等性、信息资源的共享性、虚拟性、语言符号的丰富性等特征。网络交际的普及向传统语言学提出了挑战,推动着现代语言学的嬗变、重构和创新。本文拟从网络交际的历史发展和特点出发探讨网络时代语言学研究的新领域和新视角。     

Development of a Net Shape Manufacturing Method for Ventilated Brake Discs in Single Piece Design

Carbon fibre reinforced ceramic matrix composites (CMC), originally developed for lightweight heat shields of spacecraft, are used for high performance brake discs in sports cars from different manufacturers. In contrast to the CMC materials for space applications, based on woven fabrics and costly manufacturing methods, these low cost friction materials are produced by liquid silicon infiltration of porous Carbon/Carbon (C/C) preforms, based on short fibre reinforced CFRP green bodies manufactured via warm press technique. In this work, different manufacturing methods for ventilated CMC brake discs are compared to each other, and the development of a new technology for the manufacture of single piece C/C‐SiC brake discs in net shape technique is presented.     

Non-Newtonian Fluids in Spout-Fluid Beds: Mass Transfer Coefficient at Low Reynolds Numbers

Following on from the work of Anabtawi et al. (2003), this study examined how the volumetric liquid-phase mass transfer coefficient, k_La, of oxygen in air in three-phase spout-fluid beds was affected by varying the system parameters of bed height, bed diameter, gas velocity, and liquid velocity. The liquid used was 0.1% CMC solution, displaying a pseudo-plastic rheology, with 1.75 mm glass spheres as packing. The values of the Sherwood number were lower than in previous studies (Anabtawi et al., 2003), in the range 9,000-186,000. Gas velocity had a similar effect on k_La as in a bubble column, with results also giving good agreement with previous work on two-phase and three-phase spouted bed systems. The correlation obtained for the effect of liquid velocity on k_La compared well with that of Schumpe et al. (1989). An increase in the height of packing increased k_La to the power of 0.319, with an increase in column diameter also causing an increase in k_La, which is in agreement with the results of Akita and Yoshida (1973).     

纳米纤维素增强CMC/SiO2复合膜的性能研究

近年来膜技术不断在各个领域渗透,并且应用越来越广,成分单一的膜已经不能满足各领域的需求,尤其在航空航天、军事和国防等特殊领域,对所应用的膜的性能标准更高,通过将两种以上成分复合,使膜功能互补和优化,制备出性能优异的复合膜是当今时代发展的必然趋势。本工作研究将羧甲基纤维素（CMC）与SiO2纳米颗粒和纳米纤维素(CNF)混合,制备出具有较好的耐热性和机械强度的纳米复合薄膜。该复合膜可以在物质分离、生物传感器等方面被深入研究并加以应用。     

低临界胶束浓度PEGMA-b-PCL的制备及其 药物缓释性能

以ε-己内酯（ε-CL）为疏水链段,聚乙二醇甲醚甲基丙烯酸酯（PEGMA）为亲水链段,4-氰基-4-[(十二烷基硫基硫羰基)硫基]戊酸（CDPA）为可逆加成-断裂链转移（RAFT）试剂,在以甲苯为溶剂、N2氛围、80 ℃、反应24 h的条件下,通过RAFT聚合法制备了两嵌段聚合物PEGMA-b-PCL。将其自组装为胶束用作纳米药物载体,并以姜黄素（Cur）为胶束负载药物。考察了两嵌段聚合物结构、分子量及分布,表征了胶束载体粒径、形貌,测试了胶束载体的载药和释药性能。结果表明,不同嵌段聚合物相对分子质量范围为478~7318,此类聚合物具有较低的临界胶束浓度（CMC）,在常规条件下（pH=7.4）其范围为0.920~1.600 μg/mL。胶束载体粒径范围为:68.34~186.30 nm。当n(CDPA)∶n(ε-CL)=1∶200时,胶束载药量和包封率最高,可达12.05%和75.26%。在不同pH值环境下,药物缓释性能可达15 d,其中pH=5.0时释药量可达35.38%。