微纳层叠聚丙烯腈凝胶流动特性的数值模拟研究

建立了层叠流道的三维模型和有限元网格模型，根据流变测试数据，采用Polymat对物料的黏度模型参数进行拟合，并利用Polyflow软件对聚丙烯腈（PAN）凝胶在层叠流道内的三维等温流动过程进行了数值模拟分析。研究发现，当入口流量增大时，层叠流道出口速度的不均匀性增加；沿流动方向流道内压力逐渐降低，并在出口处降低至同一最低值；流道进出口压力差与入口流量大小具有正相关性；在流道的中心截面上剪切速率分布均匀，波动较小。     

市政污泥与水泥生料混合热重及动力学分析

为研究水泥窑协同处置市政污泥的燃烧动力学特性,采用热重分析方法分别对市政污泥、煤和水泥生料及三者混合样品进行热动力学分析,求解了反应活化能和机理函数。结果表明:市政污泥燃烧有4个阶段,有机物分解和部分挥发分析出阶段活化能为69.87 kJ/mol、机理函数为(-ln(1-α))~4,剩余挥发分析出和固定碳燃尽阶段活化能为78.94 kJ/mol、机理函数为(-ln(1-α))~3;煤和水泥生料热重分析过程分为煤燃烧和生料分解2个阶段,反应活化能分别为43.58、118.21 kJ/mol,机理函数分别为(1-α)~(-1)-1、((1+α)~(1/3)-1)~2;市政污泥替代20%煤后,第1阶段活化能基本不变,机理函数由(1-α)~(-1)-1变为(1-2α/3)-(1-α)~(2/3),反应机理由"化学反应"变为"圆柱对称型三维扩散",第2阶段活化能降低,机理函数表达式由((1+α)~(1/3)-1)~2变为((1+α)~(-1/3)-1)~2,反应机理不变。     

浅谈高校图书馆资源共享

随着社会的发展，信息和文化资源大多来自于图书和网络，而高校图书馆有着丰富的藏书和网络资源，因此，高校图书馆网络资源的共建共享就是科学文化发展的必然结果。那么如何实现网络资源的共建共享，网络资源的共建共享又存在哪些问题，又该如何解决，本文在这里就简单的浅谈一下高校图书馆的资源共享。     

Rational Design of Polymeric Hybrid Micelles with Highly Tunable Properties to Co‐Deliver MicroRNA‐34a and Vismodegib for Melanoma Therapy

A polymeric hybrid micelle (PHM) system with highly tunable properties is reported to co‐deliver small molecule and nucleic acid drugs for cancer therapy; this system is structurally simple and easy‐to‐fabricate. The PHM consists of two amphiphilic diblock copolymers, polycaprolactone‐polyethylenimine (PCL‐PEI) and polycaprolactone‐polyethyleneglycol (PCL‐PEG). PHMs are rationally designed with different physicochemical properties by simply adjusting the ratio of the two diblock copolymers and the near neutral PHM‐2 containing a low ratio of PCL‐PEI achieves the optimal balance between high tumor distribution and subsequent cellular uptake after intravenous injection. Encapsulating Hedgehog (Hh) pathway inhibitor vismodegib (VIS) and microRNA‐34a (miR‐34a) into PHM‐2 generates the VIS/PHM‐2/34a co‐delivery system. VIS/PHM‐2/34a shows synergistic anticancer efficacy in murine B16F10‐CD44⁺ cells, a highly metastatic tumor model of melanoma. VIS/PHM‐2/34a synergistically attenuates the expression of CD44, a vital receptor indicating the metastasis of melanoma. Intriguingly, inhibiting Hh pathway by VIS is accompanied by downregulation of CD44 expression, revealing that Hh signaling might be an upstream regulator of CD44 expression in melanoma. Thus, co‐delivery of miR‐34a and VIS demonstrates great potential in cancer therapy, and PHM offers a structurally simple and highly tunable platform for the co‐delivery of small molecule and nucleic acid drugs in tumor combination therapy.     

High‐performance thermosets with tailored properties derived from methacrylated eugenol and epoxy‐based vinyl ester

A renewable chemical, eugenol, is methacrylated to produce methacrylated eugenol (ME) employing the Steglich esterification reaction without any solvent. The resulting ME is used as a low‐viscosity co‐monomer to replace styrene in a commercial epoxy‐based vinyl ester resin (VE). The volatility and viscosity of ME and styrene are compared. The effect of ME loading and temperature on the viscosity of the VE–ME resin is investigated. Moreover, the thermomechanical properties, curing extent and thermal stability of the fully cured VE–ME thermosets are systematically examined. The results indicate that ME is a monomer with low volatility and low viscosity, and therefore the incorporation of ME monomer in VE resins allows significant reduction of viscosity. Moreover, the viscosity of the VE–ME resin can be tailored by adjusting the ME loadings and processing temperature to meet commercial liquid molding technology requirements. The glass transition temperatures of VE–ME thermosets range from 139 to 199 °C. In addition, more than 95% of the monomer is incorporated and fixed in the crosslinked network structure of VE–ME thermosets. Overall, the developed ME monomer exhibits promising potential for replacing styrene as an effective low‐viscosity co‐monomer. The VE–ME resins show great advantages for use in polymer matrices for high‐performance fiber‐reinforced composites. This work is of great significance to the vinyl ester industry by providing detailed experimental support. © 2018 Society of Chemical Industry     

The Effect of Antibacterial Particle Incorporation on the Mechanical Properties,Biodegradability, and Biocompatibility of PLA and PHBV Composites

The composites based on polylactide (PLA) and poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with the addition of antibacterial particles: silver (Ag) and copper oxide (CuO) are characterized. Basic mechanical properties and biodegradation processes, as well as biocompatibility of materials with human cells are determined. The addition of Ag or CuO to the polymers do not significantly affect their mechanical properties, flammability, or biodegradation rate. However, several differences between the base materials are observed. PLA‐based composites have higher tensile and impact strength values, while PHBV‐based ones have a higher modulus of elasticity, as well as better mechanical properties at elevated temperatures. Concerning biocompatibility, each of the tested materials support the growth of fibroblasts over time, although large differences are observed in the initial cell attachment. The analysis of hydrolytic degradation effects on the structure of materials shows that PHBV degrades much faster than PLA. The results of this study confirm the good potential of the investigated biodegradable polymer composites with antibacterial particles for future biomedical applications.     

沥青组成与乳化沥青稳定性的灰熵关联研究

为研究乳化沥青储存稳定性与沥青组成及性质之间的关系,选用四种基质沥青,对其基本性质、四组分组成、元素组成和平均结构单元参数进行了分析。并分析了四种基质沥青制备的乳化沥青的储存稳定性。采用灰熵关联分析研究了乳化沥青储存稳定性与沥青的化学组成及基本性能之间的关系。结果表明:四组分组成中,胶质和沥青质含量是影响乳化沥青储存稳定性的最主要因素,胶质和沥青质含量越高,储存稳定性越好。元素组成中,杂原子含量是影响乳化沥青储存稳定性的最主要因素,杂原子含量越高,稳定性越好。然而,沥青的基本性质和平均结构单元参数与乳化沥青的储存稳定性之间没有明显的相关性。     

低成本CMOS阵列式高速成像系统

高速摄像是研究瞬间发生的物理和化学现象的重要手段之一.针对碰撞过程,提出了应用低成本CMOS阵列式成像传感器构建高速摄像系统.成像阵列由16个可更换的CMOS单元组成,接在主板上.为了进行同步控制,实验研究了CMOS传感器的工作时序;通过延时器,使阵列式火花源分时闪光,并在CMOS快门打开的时间段内完成.实验表明,该系统可以实现对碰撞等瞬间发生过程的拍摄,为相关研究提供基础.     

建筑结构的隔震、减振和振动控制

本文对国内外在建筑结构基础隔震、减振消能和振动控制研究和应用领域中的新进展做了综合评述。文中指出,由于基础隔震和减振消能技术已相对比较成熟,今后的研究可以集中在标准化、优化设计、细部构造、新产品的开发和完善(包括阻尼器和其它机构)等方面。新产品开发应该以低价、高效和高性能为目标。半主动控制及其在工程中的应用前景也比较看好,尽管控制机构和策略还有待进一步改进。相比之下主动控制技术由于其初始投资和维护费用都很高,至少在一般多层建筑中应用是不大可行的。此外,文中还指出跨学科的交叉研究和工业企业的参与对促进这些新技术和产品的进一步发展是十分重要的。     

硅烷偶联剂显著改善大粒径骨料混凝土性能的可能性

试验研究表明硅烷偶联剂能显著提高砂浆与花岗岩界面层的粘结强度。提出偶联剂可在水泥浆与骨料间形成化学键的初步见解 ,讨论偶联剂大幅度改善大粒径骨料混凝土性能的可能性