荧光光谱法测定啤酒中核黄素的含量

探讨了酸度和光降解作用对核黄素吸收和荧光光谱的影响.利用改进后的荧光光谱法测定了不同品牌啤酒样品中游离核黄素的含量,结果表明,所选啤酒样品中的核黄素含量在0.025 97～0.034 29μg/mL范围内.该方法操作简单、结果可靠,为定量测定基体复杂样品中的核黄素含量提供了新的方法.     

Construction of Larger Area Density-Uniform Plasma with Collisional Inductively Coupled Plasma Cells

The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma （ICP） cells were measured by a doubleprobe. The discharges of the ICP cells were shown to be independent of each other. Furthermore, the total plasma density at simultaneous multi-cell discharge was observed to be approximately equal to the summation of the plasma density when the cells discharge separately. Based on the linear summation phenomenon, it was shown that a larger area plasma with a uniform density and temperature profile could be constructed with multi-collisional ICP cells.     

莫斯科中国贸易中心工程防止结构连续倒塌设计

建筑抗倒塌问题近年来在欧美国家得到广泛关注。结合莫斯科中国贸易中心工程的防止结构连续倒塌设计,比较了国外一些相关设计规范和标准之间的相互关系,提出满足俄罗斯规范要求的防止连续倒塌设计计算方法,并将其与正常情况下的结构计算进行比较,找出其中带规律性的问题。     

Plasma Approach for Generating Ultra-Intense Single Attosecond Pulse

In our previous work,a plasma approach for single attosecond pulse (AP) generation was proposed.A few-cycle relativistic circularly polarized laser pulse will induce a single drastic oscillation of plasma boundary,from which high-order harmonics and furthermore an ultra-intense single AP can be generated naturally after it is reflected.Analytical model and simulations both demonstrate that the process is mostly efficient as the pulse duration is close to the plasma responding time.The effects of plasma density ramp are analyzed here,suggesting that the proposal is still quite efficient with appropriate density gradient in the ramp.At last,a combined approach is employed to obtain single AP with 30 fs incident laser.The relatively large-duration pulse is firstly shortened by a density dropping thin foil,and then reflected from an overdense plasma target.One-dimensional simulation shows that a 600 as single light pulse is generated with peak intensity of 3×1020W/cm2.     

柱前衍生化HPLC法测定蚯蚓中还原型谷胱甘肽(GSH)和半胱氨酸(CySH)

利用5,5'-二硫双-2-硝基苯甲酸(DTNB)为衍生化试剂,采用细胞破壁、衍生化为一体的同步衍生化提取方法,利用高效液相色谱法(HPLC)分别测定了蚯蚓中GSH、CySH含量。3次测定蚯蚓中GSH和CySH含量均值分别为0.632 2和0.860 0μmol/g,测定的加标回收率均值依次为100.8%和99.05%,检测限分别达5.43和4.96μmol/L。利用本方法可实现简便、选择性测定蚯蚓中GSH和CySH的含量。     

铝电解槽排烟管道平衡分析和调节措施

通过对铝电解槽排烟管道系统阻力变化和调节特性的分析,得出了槽盖板打开时电解槽出口管路阀门调节的方案,并提出一种提高电解槽排烟管道调节性能的改进措施:通过调整排烟管道的尺寸,使电解槽盖板打开时能自动保持其原有阻力损失基本不变,减少了调节工作量和调节误差。     

基于BIM的项目管理应用研究

房屋建筑建设过程历经规划设计、工程施工、竣工验收到交付使用,是一个漫长的过程,传统的项目管理模式下的设计碰撞问题、限额设计问题、繁琐冗长的算量过程及准确性问题、过多洽商变更问题、施工方案模拟问题、进度组织问题、竣工图的应用等问题均没有高效的解决方案。北京求实工程管理公司作为专业的项目管理公司,从自身的定位及项目管理服务范畴,利用计算机技术探索建立BIM建筑信息模型,探索BIM技术在项目管理领域的应用,旨在提升工程建设管理的效率,节约项目的成本。     

硒化蒲公英多糖的制备工艺及硒含量测定的研究

根据有机硒化合物的合成原理,以蒲公英多糖与亚硒酸钠为原料制备蒲公英硒多糖。利用单因素和正交实验探讨最佳工艺条件;利用HPLC法测定蒲公英硒多糖中的硒含量,并通过红外光谱和差示扫描量热法对硒多糖进行了初步表征。结果表明,最佳工艺条件为蒲公英多糖与亚硒酸钠质量比为1∶1.2,硝酸体积分数为0.3%,反应温度70℃,反应时间8h。蒲公英硒多糖的平均硒含量为3.79mg/g,平均收率为33.58%。红外光谱显示:蒲公英硒多糖中含有Se=O键和Se-C键,实现了蒲公英多糖的硒化,可为进一步的开发和利用提供良好的条件。     

Radio Frequency Underwater Discharge Operation and Its Application to Congo Red Degradation

Radio frequency(RF) underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz,and its application to organic degradation was investigated.The RF underwater discharge was observed to be generated within the bubble at electrode surface formed by RF and plasma heating.It was shown that the sizes of the bubbles and plasmas increased as the driving frequency and the input power went up.The breakdown voltage decreased rapidly with the increase of the water conductivity and driving frequency.Comparative experiments of the UV-VIS absorbance spectra of Congo Red solution before and after discharge suggested effective degradation of the organic dye due to the active species generated during the discharge,such as.OH,.O,.H,etc.revealed by optical emission spectroscopy.The results show that higher exciting frequency and lower conductivity of the solution are more effective for organic degradation.With the combination of Fourier Transform Infrared Spectroscopy(FT-IR) and Liquid Chromatography-Mass Spectrometry(LC-MS) data,one possible degradation process was proposed and the main conceivable components and structures of the products were also presented.     

SiO_2膜的孔径调节及疏水改性

以正硅酸乙酯为前驱体,添加聚丙烯酸[1](PAA)来增大SiO_2膜的孔径,并用聚合物溶液沉淀相转化法[2-3]对其进行疏水改性。通过热重分析(TG-DTG)、红外光谱(IR)、X射线衍射(XRD)、原子力显微镜(AFM)、比表面积(BET)以及接触角测量等对试样的热稳定性、化学组成、物相组成、比表面积及孔径分布、表面形貌和疏水性能等进行分析。结果表明,当PAA加入量为10%(体积分数,下同),800℃烧成后膜孔径可达53.73 nm。随PAA加入量增多,SiO_2膜孔径增大,但当加入量达到15%,800℃下焙烧时,膜表面开始出现裂纹;疏水改性后SiO_2膜的接触角的可增大至113°,但改性后的SiO_2膜孔洞明显较小,原因是涂覆于膜面的二甲基二乙氧化硅(DDS)堵塞了孔洞。可以得出在PAA加入量为10%~15%之间,600℃焙烧时,SiO_2膜可获得良好的疏水性。