Supercritical fluid‐assisted electroless metal plating onto aramid films: The influence of thermal treatment

Although the production of electro‐conductive aramid fibers is efficient, the method needs to be modified before it can be applied to aramid films. Whereas impregnation of an aramid film with a metal complex using supercritical CO₂ is achievable, the relatively low adhesion strength of the metal layer applied using electroless copper plating is problematic. To solve this problem, thermal treatment was conducted before, after, or both before and after electroless plating. The rationale for using thermal treatment to improve the adhesiveness of the plated layer was based on the findings that (1) an aramid film contains a significant amount of water (about 3.5 % w.o.f.), which might have a negative impact on adhesion; and (2) because an impregnated metal complex liberates metal catalyst by thermal decomposition during impregnation, a supplementary thermal action might liberate more catalyst and thereby improve adhesion. We found that thermal treatment improved adhesion of the metal layer to the aramid film. Moreover, we discovered that with respect to electroless copper plating, a short time‐lag was crucial to obtaining a thin and homogeneous metal layer with strong adhesion. In addition, we demonstrate the affinity of an aramid film for Pd(acac)₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polycarbonateurethane films containing complex of copper(II) catalyzed generation of nitric oxide

Nitric oxide (NO) is a well known potent antiplatelet agent, and its continuous release will effectively prevent the adhesion of platelets on artificial blood vessel walls. In this paper, polycarbonateurethane (PCU) with lipophilic Cu(II)‐complex (Cu(II)‐DTTCT) blending films were prepared and used as catalyst to generate NO from nitrite. The mechanical properties of PCU films blended with Cu(II)‐DTTCT were characterized by tensile strength measurement. The tensile stress and Young's modulus of PCU films blending with Cu(II)‐DTTCT increased, however, the elongation at break decreased compared with corresponding PCU films. The NO generation was investigated in vitro in the presence of NaNO₂ and ascorbic acid in PBS (pH = 7.4) at 37°C. The flux of NO generation was quantitatively measured by Griess assay. NO flux and velocity increased with the increase of NaNO₂ concentration, the concentration of ascorbic acid in PBS and the amount of Cu(II) in the films. The loss of Cu(II) from blending film surfaces was found during the in vitro NO generation experiments, which resulted in the decrease of NO flux in the second run. The PCU film could catalyze continually generation of NO for two days, which will provide a promising approach that enable endogenous NO generation on the surface of the medical devices. The generation of biologically active level of NO at the blood/polymer interface can reduce the risk of thrombosis on the implants. Polycarbonateurethane films with NO generation function may be used as high thromboresistant blood contacting materials or coating. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

复杂地基处理中化学灌浆及质量控制的研究

在修建高坝水库时,坝基断层处理常用到化学灌浆,化学灌浆是一项复杂的技术措施,为获取化学灌浆的技术参数,进行了分析研究;在前人的研究基础上,结合锦屏一级水电站中所做的化学灌浆试验,从地质条件、浆材性能、灌浆压力等影响灌浆质量的因素入手,对各自的作用机理及相互之间的关系进行了探讨;得到了使灌浆质量达到最高水平的一系列控制和调控灌浆的参数;分析结果表明,化学灌浆加固坝基基础,需采用最优参数组合及其严格的灌浆过程控制,该法是一项实用的坝基加固处理措施,可为复杂地基处理中化学灌浆的设计与施工提供参考依据。     

大规模UAV目标编队的局域世界演化模型

针对大规模UAV编队执行任务中的目标分配问题,提出了一种新的基于局域世界演化的网络模型。首先通过对复杂网络社团生成过程的分析,改进了局域世界选择策略,同时考虑目标威胁评估对单UAV的合作意愿的影响,改进了择优连接策略。最后对生成的网络进行社团识别,根据社团划分结果的不同处理方法,得到目标分配问题不同的解。仿真的结果表明,生成网络具有明显的社团结构,同时具有很好的动态扩展性。     

Graphene–Ruthenium Complex Hybrid Photodetectors with Ultrahigh Photoresponsivity

The maximum responsivity of a pure monolayer graphene‐based photodetector is currently less than 10 mA W^?1 because of small optical absorption and short recombination lifetime. Here, a graphene hybrid photodetector functionalized with a photoactive ruthenium complex that shows an ultrahigh responsivity of ≈1 × 10⁵ A W^?1 and a photoconductive gain of ≈3 × 10⁶ under incident optical intensity of the order of sub‐milliwatts is reported. This responsivity is two orders of magnitude higher than the precedent best performance of graphene‐based photodetectors under a similar incident light intensity. Upon functionalization with a 4‐nm‐thick ruthenium complex, monolayer graphene‐based photodetectors exhibit pronounced n‐type doping effect due to electron transfer via the metal?ligand charge transfer (MLCT) from the ruthenium complex to graphene. The ultrahigh responsivity is attributed to the long lifetime and high mobility of the photoexcited charge carriers. This approach is highly promising for improving the responsivity of graphene‐based photodetectors.     

太赫兹介电谱与组分含量的关系分析及应用

研究了固体有机样品的太赫兹介电谱与组分体积含量之间的关系。通过分析有效介质理论中的CRI(Complex Refractive Index)模型,得到样品的介电参数与组分体积含量的关系式。利用太赫兹时域光谱技术测得室温下两种氨基酸样品在0.5~2.7 THz的介电性质,样品的折射率、介电系数及介电损耗均随氨基酸体积含量增加而增大。选取氨基酸介电损耗谱特征峰位处的介电参数,根据CRI模型进行拟合,得到折射率与体积含量的线性关系式,介电系数和介电损耗与体积含量的二次函数关系式。研究结果有利于扩展太赫兹波段的定性定量分析手段,并对聚合物基复合材料制备有一定参考意义。     

塑料和聚合物的超声焊接

从塑料和聚合物的特性、塑料焊接方法分类、焊接的基本步骤、焊接特点方面介绍了塑料和聚合物的超声焊接。一般认为,超声焊接的研究内容主要是研究与超声有关的焊接声参数方面的问题。其实,在国外更多地是从材料方面研究焊件在焊接过程中物理性能的变化,对此做了较详尽的介绍。超声波在热塑性粘弹性介质中传播相对于金属介质来说有较大耗损,文中也介绍了测定粘弹性介质复杨氏模量的基本方法。     

Investigation of the mechanisms of improved oral bioavailability of bergenin using bergenin–phospholipid complex

Aim: The purpose of this study was to investigate the detailed mechanisms of oral absorption enhancement of bergenin (BN) using BN–phospholipid complex (BPC).

Methods: Multiple models such as ex vivo everted rat gut sac model and in vitro Caco-2 cell model were used. Meanwhile, the effect of chitosan on the enhancement of the permeability of BPC was evaluated.

Results: The limited absorption of BN was significantly improved in both ex vivo everted rat gut sac model and in vitro Caco-2 cell model when combined with phospholipid. The transport of BPC was uppermost 5.19-fold higher than that of BN. The results of ex vivo everted rat gut sac model showed that small intestine was a more suitable site for the absorption of BN and BPC than colon. Passive diffusion was the only way employed in the transport of BN, while BPC could transport across enterocytes by both passive diffusion and active transport which was found to be the clathrine-dependent receptor-mediated endocytosis. The absorption of BN was barely improved by the physical mixture of BN and phospholipid due to lack of stable intermolecular interactions. Moreover, the addition of chitosan could open the tight junctions of intestinal epithelial cells, thus significantly increasing the transport of BPC via paracellular route.

Conclusions: Totally different mechanisms, which led to the enhanced oral bioavailability, were utilized in the uptake and transport process of BPC compared with BN. These results would be of significance for the future development of oral delivery systems of BN.