Preparation and characterization of methoxy‐poly(ethylene glycol) side chain grafted onto chitosan as a wound dressing film

Chitosan has received extensive attention as a biomedical material; however, the poor solubility of chitosan is the major limiting factor in its utilization. In this study, chitosan‐based biomaterials with improved aqueous solubility were synthesized. Two molecular weights (750 Da and 2000 Da) of methoxypoly(ethylene glycol) (mPEG) were grafted onto chitosan (mPEG‐g‐chitosan) to form a ～100‐μm‐thick plastic film as a wound dressing. The chemical structures of the mPEG‐g‐chitosan copolymers were confirmed using Fourier transform infrared spectroscopy (FTIR), and the thermal properties were characterized using thermogravimetry analysis (TGA). Their microstructures were observed using scanning electron microscopy (SEM). The other properties were analyzed via the swelling ratio, tensile strength, elongation, and water vapor transmission rate (WVTR). Biocompatibility evaluations through biodegradability, cytotoxicity, and antimicrobial effect studies were also performed. The obtained mPEG‐g‐chitosan copolymers were soluble in slightly acidic aqueous solutions (pH～6.5) at a concentration of 10 wt %. The optimal mPEG‐g‐chitosan hydrogels had swelling ratios greater than 100% and WVTRs greater than 2000 g/m²/day. Their performance against Staphylococcus aureus will be subjected to further improvements with respect to medical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42340.     

Knowledge contribution in information system development teams: An empirical research from a social cognitive perspective

The extent of knowledge contribution is the key to the success of system development projects. Knowledge contribution refers to the knowledge that is provided to increase a team's efficiency and achieve its goal. This study proposes a research model exploring factors that influence the extent of knowledge contribution from a social cognitive perspective. These factors include the team relationship commitment, team relationship norms, and awareness of expertise location. Additionally, this study argues that a team's awareness of expertise location mediates the effects of affective commitment and relationship norms on knowledge contribution. The result shows that the awareness of expertise location plays a crucial mediating role in the relationships between the two socially prescribed motivations and knowledge contribution. Moreover, team relationship commitment has an important impact on team established relational norms.     

硫脲浸出液活性炭负载洗脱研究

从硫脲浸出液中活性炭负载洗脱金是比较困难的,目前在这方面发表的文献并不很多。本文着重研究并讨论了从负载活性炭上洗脱金的不同方法,包括酸性硫脲有机溶液和非有机洗脱液。研究了丙酮、乙腈、丁醇、乙二醚和乙醇5种有机溶剂。研究了不同的硫脲、硫酸和有机溶剂的浓度和温度对洗脱的影响。试验表明了这5种有机溶剂对金的洗脱能力按如下顺序排列: 丁醇>乙腈>乙二醚>乙醇>丙酮当采用5%丁醇,50～100g/L硫脲和50～100g/L硫酸,温度40～60℃时,金的洗脱率可达98～99%,此时活性炭含金降至0.10mg/g以下。对于非有机洗脱液,像硫化钠和硫代硫酸钠,研究表明金的洗脱率主要取决于溶液的浓度和温度,在室温时,1～2mol的硫化钠溶液可以洗脱99%的金。如果溶液的浓度降低至0.5mol,则温度需升至80℃以上才可能获得相同的洗脱率。     

Highly sensitive electrochemical sensor based on zirconium oxide-decorated gold nanoflakes nanocomposite 2,4-dichlorophenol detection

Journal of Applied Electrochemistry - In this study, a sensitive and selective electrochemical sensor based on a zirconia oxide-decorated gold nanoflake nanocomposite-modified glassy carbon...     

昆明住宅冬季室内环境状况调查分析

室内环境问题是21世纪研究的重点和热点.为此,2004年笔者对一百余户家庭进行了“关于昆明市冬季室内环境状况”的问卷调查和室内温湿度现场测试,调查数据显示冬季昆明室内温度15℃左右,相对湿度56.3%RH,超过半数的居住者对冬季住宅室内环境状况感觉满意和无所谓.     

Temperature Change of Light Induced Explosion of explosive material

A theoretical analysis based on the adiabatic consideration of one- dimensional model for initiation of explosive materials by intense light is performed. An expression is obtained which can be used to calculate the explosion temperature.