聚乳酸/可再生胶原-纤维素复合材料的制备

通过超分子组装的方式制备了多孔胶原/纤维素气凝胶,再通过真空浸渍法与聚乳酸(PLA)复合,经固化后得到完全填充的PLA/胶原-纤维素三维复合材料。首先利用红外光谱分析了多孔胶原/纤维素气凝胶的结构特性,当胶原和纤维素质量比为7∶3时,制备的三维多孔气凝胶最好。由于胶原蛋白和纤维素优异的可降解、可再生能力,进一步以胶原和纤维素质量比为7∶3的样品为研究对象,探讨其溶解再生能力,发现胶原/纤维素气凝胶有优异的溶解再生性能,溶解后胶原/纤维素气凝胶结晶性能基本保持稳定。将溶解再生前后的气凝胶与PLA复合,获得的PLA/胶原-纤维素三维复合材料具有质量轻、密度低、热稳定性好、弹性强等优异性能。研究发现经过100圈循环,PLA/胶原-纤维素复合材料在20 kPa应力作用下压缩形变为19.74%,形变量与初始样品的形变量基本相同。溶解再生后的PLA/胶原-纤维素复合材料其压缩回弹性稍有下降,经过100圈循环其形变量为初始样品形变量的94.1%。

纳米原纤化纤维素物化特性表征

纳米原纤化纤维素(Nanofibrillated Cellulose,NFC)是一种新型纳米纤维素材料,应用前景极为广阔.分析表征了国产NFC产品的微观形貌、比表面积、保水值、聚合度、表面电荷性能、分散稳定性、化学结构、结晶结构、热稳定性等物化特性,并与常规纤维素纤维进行对比.结果表明:NFC为细丝状和带状共混网络状结构,柔顺性好,绝大部分细丝或带状物直径为10~60nm,形态和尺寸与普通纤维素纤维有很大区别.NFC表面带负电荷,在水介质中分散稳定性极好,阳电荷需求量为31.6μmol·g^(-1),Zeta为-45mV;比表面积为35.79m2/g;保水值为637.36%;聚合度为693;结晶度为59.87%.红外光谱、XRD和热重等分析表明NFC仍保留天然纤维素的化学结构和结晶结构特点.

细菌纤维素/胶原蛋白多孔微球的制备及性能

利用Malaprade反应原理,以高碘酸钠为氧化剂,对细菌纤维素(Bacterial cellulose,BC)进行氧化,制备2,3-二醛细菌纤维素(2,3-dialdehyde bacteria cellulose,DABC).利用希夫碱反应使DABC中的-CHO-与胶原蛋白(collagen,COL)中的-NH2反应,制备CDABC复合材料.采用反相悬浮再生法将CDABC制备成BC/COL多孔微球.以BC/COL多孔微球载药率为指标,采用单因素及正交实验研究CDABC质量分数、十六烷/(CDABC/IL)比例、乳化时间及乳化温度等因素对微球制备影响.利用FT-IR、XRD、TG及SEM对BC、DABC、CDABC、BC/COL多孔微球的化学基团、结晶度、热性能及表面形貌进行分析.结果表明:BC/COL多孔微球制备最优工艺为:乳化温度35℃,乳化时间5h,十六烷∶(CDABC/IL)=10∶1,CDABC质量分数4%.在此工艺下制备BC/COL多孔微球载药率为254 mg/g.FT-IR、XRD、TG及SEM检测结果表明,BC氧化、CDABC复合均能成功进行,且复合作用对材料的形貌、结晶度及热性能均有一定改善作用.采用反相悬浮再生法能够成功制备BC/COL多孔微球,可为后续药物的负载提供条件.

胶原水解产物-羧甲基纤维素聚电解质络合物的溶胀及可塑性

胶原水解产物-羧甲基纤维素聚电解质络合物的溶胀性和可塑性是对其应用来说十分.其中,这种材料的溶胀性除受到溶液pH值、离子强度、反离子种类的影响外,还受到材料本身交联网络密度的影响;其成膜的可塑性则主要受其成分的影响.本论文主要讨论反应条件和络合稳定化方式对胶原水解产物-羧甲基纤维素聚电解质络合物的溶胀性及其成膜的可塑性的影响.

纳米纤维素的应用研究及潜在市场分析

纳米纤维素是一种生物纳米材料,它取之于丰富的可再生资源,具有生物可降解性能,低的环境、健康和安全风险。近来纳米纤维素研究与开发取得了长足进展,其低成本、低密度、优良的物理和力学性能受到业内的注意。简要介绍了纳米纤维素技术状况,应用研究进展及业已十分清晰的潜在市场。

利用三辊研磨仪二维化法分散制备部分纤维化纤维素增强聚丙烯

从廉价的纸浆纤维中获得了部分原纤化纤维素(pFC),并通过三辊研磨仪加工制备了纤维增强复合材料。通过三辊研磨机加工的方法,利用强剪切力实现了纤维在疏水性基材聚丙烯(PP)中的良好分散,并通过Micro-CT图像和光学显微镜证实了分散性。在纤维含量为50%时,复合材料的拉伸强度和弹性模量的增加分别超过70%和140%。与纯PP相比,添加纤维素可将复合材料的热膨胀系数(CTE)从平均140×10-6 K-1降低到40×10-6 K-1。差示扫描量热法(DSC)测试结果显示,与PP相比该复合材料具有稍低的结晶温度和稍高的熔融温度。热重分析(TGA)结果表明,pFC和PP在复合物中为完全为两相,并且pFC的热稳定性低于PP。该研究展示一种以提高pFC增强PP复合材料中纤维的分散度的复合材料制备方法,同时该复合材料对于天然可再生材料的利用以及提高PP的工程应用价值提供了一条思路。

多元共混改性绝缘纸的制备及绝缘性能

为了研究有机填料和无机填料的共同作用对绝缘纸性能的影响,利用纳米原纤化纤维素包覆经盐酸多巴胺表面处理后的纳米二氧化钛(TiO_(2)),得到多元共混填料(PDA-TiO_(2)@NFC),然后将多元共混填料填充到纤维素绝缘纸中,制备了不同多元共混填料浓度改性的三明治结构绝缘纸,探究了多元共混填料改性绝缘纸的最佳浓度,分析了不同多元共混填料浓度改性绝缘纸的抗张强度、直流体积电阻率、击穿特性和空间电荷。结果表明:当多元共混填料浓度为0.5%时,改性绝缘纸的抗张强度相对于未改性绝缘纸提升了17.90%,油浸纸的交、直流击穿强度均提升了17%以上,并且能有效抑制空间电荷的注入,对直流体积电导率的影响不甚明显。利用此种方法制备的三明治结构绝缘纸,力学性能和电气强度提升效果显著,为协同提升绝缘纸的各项性能提供了参考。

四妙勇安汤加减治疗下肢动脉硬化闭塞症患者的疗效和其部分机制

目的:探讨四妙勇安汤加减治疗下肢动脉硬化闭塞症患者的疗效和其部分机。方法:选取2015年1月至2017年12月商丘市第一人民医院收治的下肢动脉硬化闭塞症患者120例,按照随机数字表法随机分为对照组和观察组,每组60例。分别进行西医常规基础治疗和清洁换药,对照组加以盐酸法舒地尔注射液静脉滴注治疗,观察组在对照组基础上加用四妙勇安汤口服。分别在治疗前和治疗4周后,对2组患者的临床症状、炎性指标、血液流变学等情况进行对比评估,并进行统计分析。结果:4周治疗后,2组肿瘤坏死因子-α(TNF-α)、白细胞介素-18(IL-18)、全血黏度、血浆黏度、纤维素原水平均较治疗前明显降低,差异有统计学意义(P <0. 05),且观察组的改善优于对照组,差异有统计学意义(P <0. 05);2组踝肱指数(ABI)及趾肱指数(TBI)均明显提高,差异有统计学意义(P <0. 05),且观察组的提高优于对照组,差异有统计学意义(P <0. 05); 2组患者临床症状在溃疡面积、溃疡深度、肉芽生长、溃疡炎肿、疼痛等方面评分均明显降低,差异有统计学意义(P <0. 05),观察组的改善优于对照组,差异有统计学意义(P <0. 05)。结论:四妙勇安汤加减治疗下肢动脉硬化闭塞症可取得良好的临床疗效,这可能与改善患者血液流变,清除炎性反应递质有关。

Investigation on Risk Factors of Cerebrocardiac Vascular Thrombotic Diseases in Patients with Obstructive Sleep Apnea Hypopnea Syndrome

Objective: To observe the risk factors of thrombosis in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).Methods: From February 2001 to April 2003, 24 patients with moderate and severe OSAHS (OSAHS group) and 19 healthy adults (control group) were recruited. Their blood samples were drawn at 6∶00 and 16∶00 respectively for testing hemocrit, platelet aggregation (PAG), whole blood viscosity (WBV), prothrombin time (PT), activated partial thromboplastin time (APTT), plasma fibrinogen (Fng) and endothelin (ET).Results: There was a significantly higher hemocrit, WBV, Fng and ET as well as a significant shortening of PT and APTT at 6∶00 than that at 16∶00 in OSAHS group. However, there was no significant difference in all testing items between 6∶00 and 16∶00 in control group. The hemocrit, WBV, PAG, plasma Fng and ET were significantly higher, and PT and APTT were obviously shorter at 6∶00 in OSAHS group than those at 6∶00 in control group. A higher hemocrit, PAG, plasma Fng and ET, a longer PT and APTT were observed at 16∶00 in OSAHS group, compared with those at 16∶00 in control group.Conclusion: In OSAHS patients there were striking risk factors of thrombosis, which is more remarkable in the early morning than in the afternoon.

Ultrasonic-Vibration-Assisted Pelleting of Switchgrass:Effects of Ultrasonic Vibration

Biofuels produced from cellulosic biomass can be used to replace petroleum-based transportation fuels. However, the manufacturing cost of cellulosic biofuels is still high, partly due to the low density of cellulosic feed-stocks. Pelleting of cellulosic feedstocks can increase their density, making their transportation and storage as well as biofuel conversion more efficient and, therefore, reducing the overall cost of biofuel manufacturing. It has been shown that ultrasonic-vibration-assisted (UV-A) pelleting, without using high-temperature steam and binder materials, can produce pellets with density comparable to that produced by conventional pelleting methods. Furthermore, the sugar yield of biomass (wheat straw) processed with UV-A pelleting is 20% higher than that of biomass pelleted without ultrasonic vibration. This paper reports an experimental investigation of UV-A pelleting of switchgrass. The influences of ultrasonic vibration on pellet density, stability, durability, and pelleting force are discussed. It is concluded that pellets processed with ultrasonic vibration had higher density and stability than those processed without ultrasonic vibration, they were more durable than those processed without ultrasonic vibration, and pelleting force with ultrasonic vibration was lower than that without ultrasonic vibration.

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

Efficient and Comprehensive Utilizatio℃n of Hemicellulose in the Corn Stover

Pretreatment of the corn stover powder by dilute sulphuric acid （solid-liquid ratio 1 ： 20） at 130 for 30 min was carried out with 89.09% of the hemicellulose removed. After filtration, the xylose-rich corn stover pretreatment liquid, whose fermentable sugar was from hemicellulose hydrolysis only, consisting of 81.16% xylose and 15.27% glucose, was used to cultivate genetic recombinant Escherichia coli BL21 with human-like collagen （HLC） expression enhanced by 50.00% and 63.71% xylose consumption.

Application of cellulase in producing reducing sugar with waste lignocellulosic

The cellulase expands the use of waste lignocellulosic and improves the feasibility of ethanol production with waste lignocellulosic. In this paper the types, mechanisms of cellulase and its application in reducing sugar production were presented in detail. The strains that produce cellulase and methods for improving the cellulase activity in reducing sugar production with waste lignocellulosic were described.

Soil Cellulase Activity and Fungal Community Responses to Wetland Degradation in the Zoige Plateau, China

Four soil types(peat, marsh, meadow, and sandy) in the Zoige Plateau of China are associated with the severity of wetland degradation. The effects of wetland degradation on the structure and abundance of fungal communities and cellulase activity were assessed in these 4 soil types at 3 depths using DGGE(Denatured Gradient Gel Electrophoresis), q PCR(Quantitative Real-time PCR),and 3,5-dinitrosalicylic acid assays. Cellulase activity and abundance of the fungal community declined in parallel to the level of wetland degradation(from least to most disturbed). DGGE analysis indicated a major shift in composition of fungal communities among the4 soil types consistent with the level of degradation.Water content(WC), organic carbon(OC), total nitrogen(TN), total phosphorus(TP), available nitrogen(AN), and available phosphorus(AP) were strongly correlated with cellulase activity and the structure and abundance of the fungal community.The results indicate that soil physicochemical properties(WC, OC, TN, TP, AN, and AP), cellulase activity, and diversity and abundance of fungal communities are sensitive indicators of the relative level of wetland degradation. WC was the major factorinvolved in Zoige wetland degradation and lower WC levels contributed to declines in the abundance and diversity of the fungal community and reduction in cellulase activity.

Synthesis and Neuroprotective Activity of Novel C4, C7 Derivatives in Tetracycline Series

Since the discovery of the tetracycline in 1953, numerous natural andsemisynthelic tetracyclines have been reported with broad spectrum antibacterial activity .Doxycycline 1 and minocycline 2 are semisyn-thetic second-generation tetracyclines that exertanti-inflammatory effects. These effects appear completely separate and distinct fromtheirantimicrobial actio. Minocycline and doxycycline are absorbed rapidly and show higher brainpenetrability than other tetracyclines. During recent years, doxycycline and minocycline have shownto have neuroprotective effects in models of global and focal ischemia . The neuroprotective effectsare assumed to result from the inhibition of microglia activation. Furthermore, from an in vitrostudy, it was reported that minocycline induces neuroprotection against NMDA-induced neurotoxicityby inhibiting p38 MAP ki-nase activity in microglia . However, neuroprotective mechanisms andstructure-activity relationships of these compounds in neurons are unclear.

Effect of Acupuncture on Plasmic Levels of Insulin,Glucagon and Hypercoagulability in NIDDM Complicated by Acute Cerebral Infarction

Twenty-one cases of acute cerebral infarction secondary to NIDDM were treated with acupuncture and conventional therapy, and compared with 16 cases treated with conventional therapy alone. The results showed that acupuncture was more effective in reducing insulin and glucagon levels (P

Effects of quercetin on hepatocyte stimulating factor production by mouse peritoneal macrophages

Objective: To study the effects of quercetin on hepatocyte stimulating factor production from mouse peritoneal macrophages. Methods: Hepatocyte stimulating factor was evaluated by the amount of fibrinogen synthesized in Hep3B cells. Interleukin-6 activity was measured by B9 cell proliferation methyl thiazolyl tetrazolium colorimetric method. Hep3B cell supernatant fibrinogen was quantitated with ELISA. Results: LPS induced the synthesis of hepatocyte stimulating factor in mouse peritoneal macrophages, and hepatocyte stimulating factor promotes the synthesis of fibrinogen from Hep3B cells. Quercetin(5 to 40μmol/ L) inhibited the synthesis of hepatocyte stimulating factor stimulated by LPS. Quercetin(5 to 20μmol/ L) inhibited release of interleukin-6 from mouse peritoneal macrophages induced by 0. 5 g/ L fibrin fibrinogen degradation products. Conclusion: Quercetin inhibits the synthesis of hepatocyte stimulating factor in macrophages.

Effects of Basic Fibroblast Growth Factor and Insulin-like Growth Factor on Cultured Cartilage Cells from Skate Raja porasa

Effects of basic fibroblast growth factor (bFGF) and insulin like growth factor II (IGF II) on cartilage cells from proboscis of skate, Raja porasa Günther, were investigated in this study. The cartilage cells were cultured in 20% FBS supplemented MEM medium at 24℃. Twelve hours after culture initiation, the cartilage cells were treated with bFGF and IGF II at different concentration combinations. It was found that 20 ng/ml of bFGF or 80 ng/ml of IGF II was enough to have obvious stimulating effect on the growth and division of skate cartilage cells. Test of bFGF and IGF II together, revealed that 20 ng/ml of bFGF and 80 ng/ml of IGF II together had the best stimulating effect on the growth and division of skate cartilage cells. The cartilage cells cultured could form a monolayer at day 7.

富有传奇色彩的甘薯

甘薯的名字实在太多了，如红苕、山芋、番薯、红薯、白薯、地瓜和金薯等。它的故乡在南美洲，十六世纪末才“落户”中国，在我国的大江南北皆有其踪迹。它确是目前世界上驰名的健康食品。还有许多传奇色彩的故事。

Superior Au-adsorption performance of aminothiourea-modified waste cellulosic biomass

Waste cellulosic biomass obtains various applications due to low-cost and eco-benign characteristics.A general strategy is proposed for waste cellulosic biomass to be modified with dialdehyde functional groups as intermediates through periodate partial oxidation.Finally,aminothiourea-modified waste cellulosic biomass can be prepared through Schiff reaction.Waste corn stalk,cotton and paper as typical precursors,were used to prepare cellulosic biomass,abbreviated as AT-S,AT-C and AT-P,respectively,and their adsorption behaviors of Au(III)from the hydrochloric acid medium were investigated.The pseudo-second kinetics equation as well as the Langmuir isotherm equation can be used to depict the adsorption process,and the maximum adsorption capacities of Au(III)are21.4,19.0and3.28mol/kg for AT-S,AT-C and AT-P at298K,respectively.The adsorption capacities of Au(III)on aminothiourea modified corn stalk(AT-S)is almost357times greater than that of raw corn stalk.To the best of our knowledge,AT-S has the highest adsorption capacity towards Au(III).AT-S also displays a superior separation selectivity towards Au(III)in the presence of Cu(II),Ni(II),Co(II),Pt(VI),Pd(II)and Rh(III).Furthermore,the characterization analysis of XRD,TG,SEM,TEM and FTIR confirms that AuCl4– has been reduced to elemental Au nanoparticles and deposit onto the surface of the biomass.It shows a prospect for waste corn stalk to be used to adsorb Au(III)from liquid phase and the possible fabrication of gold nanoparticles by a general adsorption process without any reductant.