La_(0.7)Sr_(0.3)NiO_3/壳聚糖/聚吡咯/牛血红蛋白修饰玻碳电极的制备及构建过氧化氢传感器

在玻碳电极上修饰一层表面均匀的聚吡咯膜,然后利用钙钛矿和壳聚糖的复合膜来固定牛血红蛋白(Hb),制备出性能良好的过氧化氢生物传感器.采用循环伏安(CV)和扫描电镜对修饰电极进行了表征.该传感器对H2O2具有好的催化响应,且响应快.在优化的实验条件下,所制备的传感器对H2O2的线性范围为7.0×10-6～1.5×10-3mol/L,检测限为9.0×10-8mol/L.     

自组装壳聚糖接枝聚苯胺/葡萄糖氧化酶生物传感器的研究

合成了壳聚糖接枝聚苯胺，并采用静电自组装法制备了壳聚糖接枝聚苯胺／葡萄糖氧化酶生物传感器。讨论了温度、pH值、离子强度以及自组装膜层数对传感器电流响应的影响。制备的葡萄糖生物传感器检测范围为0．5mmol／L～16mmol／L，电流响应时间仅为5．2s。     

基于[C_(10)-mim~+]Br~-固定HRP于Au/石墨烯复合材料电极表面的新型H_2O_2酶生物传感器

利用长链离子液体特殊的性质,用其固定HRP于Au/graphene电极表面(Nafion/HRP/[C10-mim+]Br-/Au/Gr/GCE)组装成H2O2传感器。用透射电镜来表征Au/氧化石墨烯的形貌,金纳米颗粒很均匀的分散在石墨烯表面,并不存在团聚现像。电化学技术检测Nafion/HRP/[C10-mim+]Br-/Au/Gr修饰电极对H2O2的响应情况,显示修饰电极对H2O2有很好的响应,在H2O2浓度2.0×10-6~1.2×10-3 mol/L的范围内,还原电流与浓度存在线性关系(R=0.997),检测限为3.0×10-7 mol/L;另外传感器具有很好的稳定性和选择性,为生物分子的检测提供新方法。     

辣根过氧化物酶在多壁碳纳米管——壳聚糖膜中的电化学和生物传感性质

采用壳聚糖包裹的多壁碳纳米管膜固定辣根过氧化物酶(HaP)于玻碳电极表面,实现了HRP的直接电化学并以此酶膜制备了NO生物传感器.在磷酸缓冲溶液中固定在电极表面的HRP氧化还原式电位为-0.354 V(us.SCE),直接电子转移速率常数为4.24±1.02 s-1.研究结果表明,固定在电极表面的HRP能保持其对一氧化氮还原的生物电催化活性,该传感器在NO浓度为1.0×10-4~1.4×10-3 mol L-1范围内存在线性响应,响应时间小于11 s,NO的检出限为7×10-4 mol L-1.多壁碳纳米管特殊的电学性质和壳聚糖良好的生物相容性性使得构筑的HRP生物传感器呈现了良好的应用前景,尤其适用于痕量NO的检测.     

静电自组装PDDA/CMCNa聚电解质复合纳滤膜及其性

以聚丙烯腈(PAN)超滤膜为基膜,通过羧甲基纤维素钠(CMCNa)阴离子聚电解质和聚二甲基二烯丙基氯化铵(PDDA)阳离子聚电解质层层静电自组装(LbL)制备得到复合纳滤膜.考察了阴离子聚电解质溶液浓度、组装层数对膜表面荷电性、形貌和亲水性等的影响;同时研究了操作条件不同时该纳滤膜对罗丹明B染料分离性能变化.结果表明,CMCNa阴离子聚电解质浓度增大时,膜表面荷负电性和亲水性增强;当PDDA质量浓度为5.0 g/L,CMCNa的浓度为2.0 g/L,且组装4.0个派对层时,复合膜表面ζ电位约为 70 mV,其接触角约为30°;制备的(5 PDDA/2CMCNa)5.0-PAN复合纳滤膜,在25℃和0.60 MPa的操作条件下,对0.4×10-3 g/L的罗丹明B截留率达到90％,通量为42 L/(m2·h·MPa).     

银保护用自组装单分子膜的防腐蚀研究

用3-巯基丙基三甲氧基硅烷(3-MPS)在银电极表面制备了自组装单分子膜,研究了该组装膜在0.1mol/L NaOH中对银的防护作用.通过极化曲线、接触角及俄歇电子能谱等方法对组装膜的极化电阻、腐蚀电流及表面状况进行了研究表征,得到了最佳MPS组装液浓度为1×10-4mol/L和最佳组装时间为6 h下的腐蚀电位、腐蚀电流密度、极化电阻和缓蚀率等结果.     

碳纳米管/铁氰化镍/聚苯胺杂化膜对抗坏血酸的电催化氧化

采用循环伏安一步共聚法在碳纳米管修饰的铂基体上制备了立方体的铁氰化镍/聚苯胺/碳纳米管杂化膜;采用循环伏安法和计时电流法测试了杂化膜对抗坏血酸的电催化氧化性能;通过扫描电子显微镜(SEM)观察了杂化膜电极的表观形貌。结果表明,该电极对抗坏血酸具有较高的电催化氧化活性;在0.1 mol/L PBS和0.1 mol/L KNO3的溶液中,该杂化膜电极对抗坏血酸的催化氧化电流与其浓度在1×10-5～1.4×10-4mol/L呈良好的线性关系,相关性系数R=0.996 6,检出限为6.09×10-6mol/L,同时具有较高的灵敏度754.8 mA.M-1.cm-2,并采用计时电流法对抗坏血酸催化氧化的扩散系数和催化速率常数进行了研究。     

基于Pt-Pb纳米花的无酶葡萄糖传感器性能研究

利用超声恒电流沉积法在金电极表面制备了Pt-Pb纳米花,并将其用于构建无酶葡萄糖传感器,采用阻抗谱、循环伏安和差分脉冲伏安法研究了其电化学性能。SEM结果表明,当沉积电流为10mA时,电极表面形成Pt-Pb纳米花结构。电化学测试结果表明,该电极对葡萄糖具有很好的电催化性能,在含有氯离子的溶液中不会失活。Pt-Pb纳米花电极构建的无酶传感器对葡萄糖的线性响应范围为0.5×10-3～22×10-3 mol/L,灵敏度为3.68mA·cm-2·(mol/L)-1,检测限为24×10-6 mol/L。此外,传感器具有良好的选择性、重复性和稳定性。     

基于二氧化硅球腔阵列的葡萄糖传感器研究

在二氧化硅球腔阵列电极上,通过电沉积普鲁士蓝和直接吸附葡萄糖氧化酶,制备了一种新型葡萄糖生物传感器。该传感器对酶催化反应产物过氧化氢的选择性催化还原特性可实现对葡萄糖的检测,实验结果表明,传感器的最佳工作电位是－0．3V,测试溶液的最佳pH值为6．0。在选定的工作条件下,传感器的线性范围为2．49×10-5－2．42×10-3mol／L,检测极限值为7．2×10-6mol／L（S／N=3）,米氏常数为1．136mmol／L。该方法制备的生物传感器能有效降低干扰,具有潜在的应用价值。     

La0.7Sr0.36NiO3/壳聚糖/聚吡咯/牛血红蛋白修饰玻碳电极的制备及构建过氧化氢传感器

在玻碳电极上修饰一层表面均匀的聚吡咯膜,然后利用钙钛矿和壳聚糖的复合膜来固定牛血红蛋白(Hb),制备出性能良好的过氧化氢生物传感器.采用循环伏安(CV)和扫描电镜对修饰电极进行了表征.该传感器对H2O2具有好的催化响应,且响应快.在优化的实验条件下,所制备的传感器对H2O2的线性范围为7.0×10-6～1.5×10-3...     

卵磷脂对生物活性玻璃表面改性的研究

采用卵磷脂对生物活性玻璃粉体表面进行改性处理, 并研究了生物活性玻璃与卵磷脂的相互作用. 热分析(TG/DSC)、傅立叶变换红外光谱（FTIR）分析表明, 卵磷脂在生物活性玻璃表面附着,通过氢键等弱键相互作用. 表面改性后的生物活性玻璃粉体与壳聚糖复合后, 复合材料的力学强度与未处理的相比有明显提高. 扫描电子显微镜(SEM)结果显示, 经处理后的生物活性玻璃粉体在壳聚糖中分散均匀, 两者结合紧密, 表明卵磷脂改性可以有效地提高生物活性玻璃粉体与壳聚糖有机基质的界面结合强度.     

胆碱磷酰化偶联壳聚糖仿生衍生物的合成及表征

采用Antherton-Todd反应合成了两种胆碱磷酰化偶联壳聚糖衍生物——带双正电荷的N-二胆碱磷酰化偶联壳聚糖(N-PC+Cs)和两性的N-磷酸胆碱磷酰化偶联壳聚糖(N-PCCs),并用核磁共振波谱(NMR)和红外光谱(IR)表征其化学结构。由1H-NMR谱得到N-PC+Cs的取代度为30.9%,N-PCCs的取代度为32.6%。X射线衍射谱(XRD)和热分析的结果表明,与壳聚糖相比,N-PC+Cs和N-PCCs的结晶性和热稳定性都显著降低。水溶性试验表明,两种仿生衍生物在中性水溶液中都表现出良好的溶解性,有望用于药物/基因传输系统载体。     

钴锌合金在氯化胆碱-尿素离子液体中的电沉积行为

为探索新型的Co-Zn合金电镀工艺,在氯化胆碱-尿素离子液体中电沉积了钴锌合金镀层,探讨了阴极电位、Co(Ⅱ)/Zn(Ⅱ)浓度比、温度及时间等工艺参数对电沉积的影响,并对合金镀层性能进行了测试.结果表明:在氯化胆碱-尿素离子液体中,控制体系的组成和沉积条件,可得到表面均匀、附着力强、有金属光泽的非晶态Co-Zn合金镀层,其中Co的质量分数可达90%.     

Ionic-Liquid-Based Safe Adjuvants

Adjuvants play a critical role in the design and development of novel vaccines. Despite extensive research, only a handful of vaccine adjuvants have been approved for human use. Currently used adjuvants are mostly composed of components that are non-native to the human body, such as aluminum salt, bacterial lipids, or foreign genomic material. Here, a new ionic-liquid-based adjuvant is explored, synthesized using two metabolites of the body, choline and lactic acid (ChoLa). ChoLa distributes the antigen efficiently upon injection, maintains antigen integrity, enhances immune infiltration at the injection site, and leads to a potent immune response against the antigen. Thus, it can serve as a promising safe adjuvant platform that can help to protect against pandemics and future infectious threats.     

Development and characterization of phyto-vesicles of wedelolactone for hepatoprotective activity

Wedelolactone is isolated from the dried leaves of Eclipta alba (L.) and reported to be effective as a potential hepatoprotective, antibacterial and anti hemorrhagic. Pharmacokinetic studies of wedelolactone reveal its poor absorption through the intestine. The objective of the present study is to enhance bioavailability of wedelolactone by its complexation with phosphatidyl choline and then formulating it as phyto-vesicles for hepatoprotective activity. The complex of wedelolactone rich fraction was prepared with phosphatidyl choline and characterized on the basis of solubility, melting point, thin layer chromatography (TLC), UV, IR and NMR spectroscopy. The complex was further converted into phyto-vesicles and characterized. The hepatoprotective potential of phyto-vesicles was compared with complex, wedelolactone rich fraction and physical mixture of wedelolactone rich fraction and phosphatidyl choline by in vitro method. The results revealed that hepatoprotective activity is better in case of phyto-vesicles as compared to the complex, physical mixture and the wedelolactone itself. Enhanced bioavailability of the wedelolactone complex may be due to the amphiphillic nature of the complex, which greatly enhance the water and lipid solubility of the compound. The present study clearly indicates the superiority of phyto-vesicles over the complex and wedelolactone, in terms of better absorption and improved hepatoprotective activity.     

基于低共熔溶剂聚合物电解质染料敏化太阳能电池研究

以琼脂糖聚合物为基质, 1-甲基-2-吡咯烷酮(NMP)为溶剂, 由尿素、氯化胆碱合成的低共熔溶剂(DES)作为添加剂制备聚合物电解质用于制备准固态染料敏化太阳能电池(DSSC)。研究了尿素/氯化胆碱配比、低共熔溶剂添加量对聚合物电解质电化学性能及其DSSC光电性能的影响。研究结果表明: 随着尿素/氯化胆碱配比增加, 准固态电解质的导电性能增加, 尿素、氯化胆碱的配比为2:1时可获得最佳电导率7.24 mS/cm。对不同低共熔溶剂含量电解质进行离子电导率测试研究发现: 添加量为20wt%时, 电解质获得最佳电导率6.21 mS/cm。染料敏化太阳能电池的光电效率随低共熔溶剂含量的增加先增加后降低, 低共熔溶剂添加量为20wt%时, 获得最佳光电效率η=3.18%, 短路电流密度J_sc=10.28 mA/cm², 开路电压V_oc=0.59 V, 填充因子FF=0.51。     

Kinetics of swelling/shrinking rearrangement of a self-aggregated nanohydrogel at solid/liquid interfaces

The hydrogel nanoparticles (nanohydrogels) have great potentials in numerous biomedical applications. Biomembrane-mimetic self-assemble nanohydrogel MC _n (n repeated 2-methacryloyloyloxyethyl phosphoryl choline grafted cholesteryl group-bearing pullulan) was designed. In order to mimic the interfacial responses of fibrinogen at the hydrophobic/hydrophilic surfaces, MC _n molecules were controlled by the chain length of the decorated MPC in term(s) of n?=?0, 6.2, 14.3 and 180, respectively. The dynamic rearrangements of MC _n hydrogel molecular layer on the hydrophobic highly ordered pyrolytic graphite surface were observed by the atomic force microscopy. The results showed that there were biphasic transitions at the liquid/solid interfaces from the initial solute state to metastable state to the equilibrium state. The length of MPC branches, n, governed the changes of layer thickness to the equilibrium state appearing as swelling or shrinking. The time evolution of the thickness was fitted by a single exponential model, and the kinetics parameters of surface rearrangements to the equilibrium state were obtained.     

模具表面离子氮化工艺研究

研究了一种利用空气／甲烷混合气体对模具表面进行离子氮化的新工艺,分析了渗层的硬度、组织及物相。结果表明,通过加入甲烷气体,可以实现用空气直接进行离子氮化处理,通过调整甲烷流量,可以获得不同的渗氮硬度和物相。     

Report on ONR Workshop on Fracture Scaling

The paper reports on the discussions at the ONR Workshop on Fracture Scaling, held at University of Maryland in June 1999, under the chairmanship of Z.P. Baant and Y.D.S. Rajapakse. The workshop dealt with size effects in structural failure and scale bridging in mechanics of materials. The lectures at the Workshop were published in Volume 95 of this Journal. The objective of this paper is to present records and interpretations of the extensive discussions prepared by invited specialists. The records show which are the areas of disagreement among leading researchers and which are those where consensus has been reached.