In vitro and in vivo investigation of bacterial cellulose dressing containing uniform silver sulfadiazine nanoparticles for burn wound healing

Silver sulfadiazine(SSD) particles in homogeneous dispersion state were prepared by an ultrasonic method and then nano- and microparticles were separated using centrifugation. SSD particles with narrow size distribution were impregnated with bacterial cellulose(BC) to produce BC–SSD composite membrane used as burn wound dressing. A scanning electron microscope(SEM) was used to examine the surface morphology of BC–SSD membranes. The incorporation of SSD in BC–SSD was confirmed by X-ray diffraction(XRD). Antimicrobial tests in vitro indicated that BC–SSD showed excellent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The effects of BC–SSD on burn wound healing were assessed by rat models. The comparative study confirmed that the wound treated with BC–SSD showed high healing rate. The bacteria count in BC–SSD group was far less than control group. Histological analysis showed that epithelialization progressed better in wound treated with BC–SSD. These values demonstrated that the BC–SSD composite membrane could be a promising wound dressing for burn.     

低pH值下DACMC的制备、结构及热性能

在低pH值条件下采用NaIO4氧化羧甲基纤维素(CMC),制备了二醛羧甲基纤维素(DACMC),通过FT-IR、13C NMR、XRD和AFM等研究了pH值对NaIO4氧化CMC程度的影响,以及pH值对DACMC结晶结构、形貌结构、热稳定性的影响.结果表明:pH值对NaIO4氧化CMC的程度有显著的影响,但缺乏规律性,当pH值为1.5时其氧化程度最高(醛基含量最大为54.35%);FT-IR和13C NMR结果证实了在CMC分子链上有羰基产生;DACMC的结晶度均大于CMC,且随反应体系pH值的增加而增大;由于失水葡萄糖环的断裂,DACMC的分子链更加柔软,相互缠结得更加紧凑、规整,表面Z向尺寸随着醛基含量的增大而降低;DACMC的热稳定性差于CMC,pH=1.5的条件下制备的DACMC的热稳定性最差.     

一种快速、经济、有效纯化人工合成寡核苷酸片段的方法

采用DEAE-52纤维紊小柱，纯化了7个人工合成的寡核苷酸引物．纯化效果栗用岛津(uy-265)分光光度计扫描，8mol／L尿素-12%聚丙烯酰胺凝胶电泳及自提的模板DNA经PCR检测．该法分传统的HPLC法及PAGE法相比，具有快速、经济、有效的优越性。     

热致性羟丙基纤维素液晶的超分子结构

本文对热致性羟丙基纤维素液晶的超分子结构,用多种实验方法进行了研究。结果表明,它们为胆甾型液晶,在一定的温区内形成有序微区结构。在切应力作用下,微区进而发生形变和取向,甚至破坏和重组而生成原纤和微纤结构。原纤和微纤的尺寸分别为几个μm 和几百 nm.微纤是由高度取向的棒状分子链所组成,在晶区它们与剪切方向成28°夹角。这一结构模型能很好地解释条状织态结构及激光小角光散射的 H_V 图像特征。     

D1-1-113井CO2增能压裂施工分析

介绍了CO2酸性环境交联压裂液体系、工艺特点及压裂施工情况,并通过对压裂后产量的分析,总结了该工艺成功的经验和存在的不足。     

纤维素纳米晶对胶凝复合材料耐酸性能的影响

Acid mine drainage presents an important threat to cementitious structures. This study is aimed at investigating the effect of cellulose nanocrystals (CNCs) on the acid resistance of cementitious composites. CNCs were added to mortar mixtures as additives at cement volume ratios of 0.2vol%, 0.4vol%, 1.0vol%, and 1.5vol%. After 28 d of standard curing, the samples were immersed in a sulfuric acid with a pH value of 2 for 75 d. The unconfined compressive strength (UCS) test, the density, water absorption, void volume test, and thermogravimetric analysis were carried out to investigate the properties of CNC mixtures before sulfuric acid immersion. It was found that the addition of CNC reduced the volume of permeable voids and increased the hydration degree and mechanical strength of the samples. Changes in mass and length were monitored during immersion to evaluate the acid resistance of mixtures. The mixture with 0.4vol% CNC showed a reduced mass change and length change indicating its improved acid resistance.     

纤维素与木质素共热解行为研究及产物分析

利用热重分析仪和居里点裂解-气相质谱联用仪进行纤维素和木质素共热解实验,研究纤维素和木质素共热解过程中的相互作用及热解产物分布情况.结果表明:纤维素与木质素共热解过程中存在明显的相互作用,与热解温度和混合比例具有一定相关性.纤维素质量分数较低(30%)时,木质素和纤维素共热解时促进残渣的形成,而抑制了气相产物的形成,并提高了酚的相对产率;纤维素质量分数较高(70%)时,木质素和纤维素在共热解过程中相互促进,抑制了固体残渣的形成和非芳基化合物的形成.在低温区(200～320℃),木质素易活化产生小分子,与纤维素共热解时形成相互促进的作用加速了热失重过程;在高温区,纤维素与木质素共热解促进了残渣的形成,抑制了热解过程.     

从流变数据预测纤维素的多分散指数■_z/■_w

简单介绍了Llorens提出的关于从聚合物熔体的流变数据预测多分散指数Mz/Mw的方法,并用Llorens的方法计算了纤维素的多分散指数。将计算的值与GPC测定结果进行对比证明了该法对比较不同纤维素的分散指数具有一定的参考价值。     

Synthesis of CaCO3 crystals using hydroxypropylmethyl cellulose hydrogel as template

Calcium carbonate crystallization was performed in hydrogel of hydroxypropylmethyl cellulose (HPMC). Results showed that the polyhydroxy functionalities in HPMC gel network facilitated the nucleation of aragonite which was not found in experiment without HPMC hydrogel and in experiment using methylcellulose (MC) hydrogel as template. On the other hand, due to the unique assembly of the macromolecules in HPMC hydrogel network, which was different from other hydrogels used in some previous reports, particular crystal morphology, corncob-like CaCO_3, was obtained for the first time.