Radiation synthesis of PVP/CMC hydrogels as wound dressing

Carboxymethyl cellulose (CMC) and poly(N-vinyl pyrrolidone) (PVP) were blended to synthesize hydrogels by ⁶⁰Co γ-ray irradiation. A series of hydrogels were prepared with three compositions, i.e. PVP:CMC = 5:5, 6:4 and 7:3. The properties of the hydrogels such as gel fraction, gel strength, swelling behavior and moisture retention were investigated. Compared with pure PVP and CMC hydrogels, PVP/CMC blend hydrogels possessed improved gel strength, flexibility and transparency. As the content of PVP in PVP/CMC blend hydrogels increased, the gel fraction increased while the swelling rate decreased. The hydrogels with optimal properties were obtained in a composition of PVP/CMC = 6/4 with sterilization dose (25 kGy) and further characterized by FT-IR and SEM. Properties concerning the application of wound dressing were performed by comparison with a commercial hydrogel wound dressing to find a similar moisture retention capability and improved swelling rate. The improved properties as well as the cheapness of the materials suggest that PVP/CMC blend hydrogel can be good candidate as wound dressing.     

A ctivation measurement of neutron distribution in intermediate energy heavy ion target area

The distribution of neutrons produced by the reaction of 50MeV/u ^12C-ion on a thick Cu target are studied.The neutrons are measured with threshold activation detectors.Al.F,C,Al and In activation samples were used to measure neutrons with energy greater than 7,11,20,50MeV and thermal neutrons,respectively,The fluence rate,energy and angular distributions of neutrons,total neutron yield of 12C-ion and the emission rate in the forward direction of neutrons over 11 and 20MeV were obtained.     

面向在线率差异的SaaS订阅限额及资源配置组合优化

软件即服务（softuare as a service,SaaS）是一种让用户通过支付订阅费来获得软件访问权的云服务模式。由于其业务的多样性,用户对不同软件的在线访问率存在很大差异,所以不同软件所消耗的云计算资源也存在差异。为避免违反服务等级协议（service level agreement,SLA）而产生违约赔付的风险,SaaS运营商不仅要优化各种软件的计算资源配置,还要对各类软件的订阅量加以限额限制。在考虑SLA限制的基础上,构建了一个以收益最大化为目标的有资源约束的非线性整数规划模型。由于模型计算的复杂性,其无法在多项式时间内求解,所以设计了基于Q学习-粒子群（particle swarm optimizoction,PSO）的融合算法来求解该NP难题。该算法将Q-学习嵌入到PSO中,动态调整PSO参数,从而避免直接使用PSO时会面临的局部最优陷阱和计算效率低下的问题。仿真实验验证了在不同场景下模型及算法的有效性,结果表明该算法可在云计算资源有限的条件下,以较高的求解效率获得收益更高的订阅限额及资源配置方案。其中,当处于需求波动大的情境下时,运营商应尽可能降低软件的资源争用比,通过配置足量的虚拟机资源并设定严格的订阅限额来保障软件的服务质量,减少违约赔付成本;相反,当处于需求波动小的情境下时,运营商可以提高软件的资源争用比,通过放宽订阅限额来抢占更大的市场,实现收益最大化。     

上海市生活垃圾废塑料回收再利用现状及优化策略

在生活垃圾分类背景下上海市可回收物回收体系逐步完善,生活源废塑料回收再利用量获得极大提升。通过现场调研与统计资料分析,对当前上海市生活垃圾废塑料分类回收现状、再利用技术进行分析梳理,结果显示当前生活垃圾废塑料回收类别以PET、PP为主,分别占总回收量的45.3%和30.7%;另有近30%具有回收价值的废塑料未被回收,主要以PP和PET为主。在此基础上,提出需进一步完善分类回收标准与补贴政策、推动PET同级利用等回收技术创新、强化宣传教育与主体监管等优化策略,以期促进废塑料回收与再利用行业进一步发展。     

Performance of N95 elastomeric respirators in high humidity and high coal dust concentration environmentOA

High humidity and high dust concentration in deep coal mines may severely challenge the performance of respirators worn by coal miners.This paper aims at quantitatively evaluating the respirators used in deep coal mines and providing scientific guidance for the respiratory protection of miners.Based on the self-designed in-situ PM_2.5collector,controllable PM_2.5generator,human breathing simulator,and respirator simulation testing system,under the simulated deep mine working ...     

柔性直流输电技术在风电场并网中的应用探讨

柔性直流输电是在电压源换流器技术和全控型功率器件的基础上发展起来的,通过电压源换流器技术,可以控制系统中的无功功率、抑制并网公共点的电压波动。文章分析了电压源换流器（VSC）的基本模型,研究了换流站无功功率控制和电压控制策略对改善并网风电场电压稳定性的作用,阐述了风电场并网对电网的可靠性和稳定性等方面的影响。     

主题模式教学中的动机强度研究

本文采用定量的研究方法,从动机强度的角度分析了主题模式在大学英语教学中的效果.研究通过实验班和对照班学生动机强度层面的对比,发现主题模式教学对学生的动机强度产生了影响.学生在围绕主题开展的教学中更为主动地进行语言学习,尤其体现在听说能力方面.同时研究还发现学生在新模式下课堂教学的参与性更高,对教学环境更加满意.     

茶叶样品中微量元素分析方法的研究

采用HNO3-H2O2混合酸,密闭微波消解制样,ICP—AES、ICP—MS测定茶叶中P、Zn、Fe、Mn、Mg、Ca、B、Cr、Co、Ni、Cu、Mo、Cd、Pb等14种微量元素含量,建立了对植物样品中多种元素进行同时测定的方法。经国家植物标准物质验证,方法具有较好的准确性和重现性,操作流程短,检出限低,基体干扰小,RSD≤10％,加标回收率在90％～110％之间。可用于植物样品的批量分析。     

Research on theory and key technology of trusted computing platform security testing and evaluation

Trusted computing has become a new trend in the area of international information security, and the products of trusted computing platform begin to be used in application. Users will not use the products of information security, unless it goes through the testing and evaluation. Here we concentrate on the testing and evaluation problem of trusted computing platform, begin with constructing proper formalization model of trusted computing platform for testing, and establish a mathematical chain of trust model...     

基于PSA分析事故序列场内工作人员辐射风险研究

从总风险控制的角度,提出了事故工况下场内工作人员剂量与辐射风险接受准则,并建立了相应的评估方法。以典型压水堆核电厂为例,采用概率安全分析（PSA）的全范围事故序列进行验证评价,评估了典型压水堆核电厂事故后场内工作人员的辐射剂量与辐射致死风险。通过验证结果可知,事故后场内工作人员总的辐射致死风险远低于公众由于自然灾害、疾病、交通事故及不同行业的总死亡风险值;事故后工作人员在燃料厂房进行操作时的辐射致死风险占比最高,故工作人员在燃料厂房进行相关操作时,可提前制定相应的辐射防护措施来降低辐射风险;工作群组中其他人员和意外受照人员事故后辐射致死风险占比较高,可通过采用气面罩等方式对气载放射性进行防护以降低其辐射风险。相应的分析结果可为后续核电厂事故后处理方案的制定和事故后场内工作人员辐射防护措施的制定提供借鉴。