HPLC法同时测定果汁饮料中曙红、荧光桃红、荧光素钠

建立了同时检测果汁饮料中曙红、荧光桃红、荧光素钠的高效液相色谱分析方法.果汁饮料样品经甲醇超声提取后,补足重量,静置15 min,过0.45 μm的微孔滤膜.采用Agilent Zorbax Plus SB-Aq柱(250mm×4.6mm,5μm)分离,以乙腈-NH4 H2 PO4溶液(0.05 mol/L,用H3PO...     

含湿量对微细腔内甲烷低温重整影响的热力学研究

为了实现微燃烧器内甲烷持续稳定燃烧,要求进一步深入研究原料气中含湿量变化对微细腔甲烷湿空气低温(小于973 K)重整反应的影响.于此,本文通过热力学方法分析了 0.1 MPa下一定温度时,恒定原料气流量和恒定空碳比两种工况中,含湿量在欠氧和低温环境中对微细腔甲烷自热重整反应中积炭、甲烷转化、产氢特性及反应过程的影响.结果表明:微细腔内甲烷质量流量一定时,随着含湿量增加,积炭逐渐减小,甲烷转化率先减小后增加,氢气则一直随之增加.体系中甲烷的转化以生成CO2为主,CO的选择率随含湿量增加先增加后减小,CO2选择率则一直增加;增加含湿量会使反应后体系中水的含量增加,也会促使反应过程中体系消耗的水量最终大于生成的水量.在含湿量不超过空气量的反应条件下,两种工况中反应前后水质量分数的变化量均在含湿量达280 g·kg-1后显示出体系以消耗水为主,且原料气中湿空气的含湿量均应满足最低为350 g·kg-1,才有利于反应过程中减少积炭产生和促进重整反应,当达到这一条件时,恒定的空碳比在获得较高的甲烷转化率和氢气产率上更具优势.     

羧酸系混凝土超塑化剂的作用机理及分子结构模型设计

简要讨论了羧酸系混凝土超塑化剂的作用机理和分子设计原理,并详细分析了各种不同超塑化剂分子结构模型与分散和保坍性能之间的关系,提出了新型超塑化剂的分子设计原则,设计了一种集大减水、高保坍、低掺量的分子结构模型,对模型进行了试验验证,结果证实了其分子设计原则的可行性。     

Neutron Irradiation Effect in Two-Dimensional Electron Gas of AlGaN/GaN Heterostructures

AlGaN/GaN heterostructures have been irradiated by neutrons with different fluences and characterized by means of temperature-dependent Hall measurements and Micro-Raman scattering techniques. It is found that the carrier mobility of two-dimensional electron gas （2DEG） is very sensitive to neutrons. At a low fluence of 6.13 × 10^15 cm^-2, the carrier mobility drops sharply, while the sheet carrier density remains the same as that of an unirradiated sample. Moreover, even for a fluence of up to 3.66 × 10^16 cm^-2, the sheet carrier density shows only a slight drop. We attribute the degradation of the figure-of-merit （product of ns×μ ） of 2DEG to the defects induced by neutron irradiation. Raman measurements show that neutron irradiation does not yield obvious change to the strain state of AlGaN/GaN heterostructures, which proves that degradation of sheet carrier density has no relation to strain relaxation in the present study. The increase of the product of ns × μ of 2DEG during rapid thermal annealing processes at relatively high temperature has been attributed to the activation of GeGa transmuted from Ga and the recovery of displaced defects.     

Hydrogen Sensors Based on AlGaN/AlN/GaN Schottky Diodes

Pt/AlGaN/AlN/GaN Schottky diodes are fabricated and characterized for hydrogen sensing. The Pt Schottky contact and the Ti/Al/Ni/Au ohmic contact are formed by evaporation. Both the forward and reverse currents of the device increase greatly when exposed to hydrogen gas. A shift of 0.3 V at 300 K is obtained at a fixed forward current after switching from N2 to 10%H2＋N2. The sensor responses under different concentrations from 50ppm H2 to 10%H2＋N2 at 373K are investigated. Time dependences of the device forward current at 0.5 V forward bias in N2 and air atmosphere at 300 and 373K are compared. Oxygen in air azcelerates the desorption of the hydrogen and the recovery of the sensor. Finally, the decrease of the Schottky barrier height and sensitivity Of the sensor are calculated.     

Micro Extrinsic Fiber-Optic Fabry-Perot Interferometric Sensor Based on Erbium- and Boron-Doped Fibers

Micro extrinsic Fabry-Perot interferometers （MEFPIs）, with cavity lengths of up to ~ 9 μm and maximum fringe contrast of ~19 dB, are fabricated by chemically etching Er- and B-doped optical fibers and then splicing the etched fiber to a single-mode fiber, for the first time to the best of our knowledge. The strain and temperature responses of the MEFPI sensors are investigated experimentally. Good linearity and high sensitivity are achieved. Such a type of MEFPI sensor is cost-effective and suitable for mass production, indicating its great potential for a wide range of applications.     

聚变实验堆真空室壳体成型模具设计及实验研究

参考ITER真空室制造规范,在常温下对中国聚变工程实验堆(CFETR)真空室壳体成型进行工艺预研。先根据成型经验公式计算出所研究壳体的成型模具尺寸范围,再利用有限元软件选择3组公式值附近的尺寸模拟了该成型工艺最佳模具尺寸参数,分析出最佳型面尺寸误差在±1.5mm内,并以此指导成型实验。测试了成型实验后工件减薄量、回弹量、变形率等参数,与模拟分析结果吻合度较高,验证了该成型模具设计的合理性。     

冷冻机油中轻烃含量测定

利用顶空色谱法,在顶空瓶中把冷冻机油中轻质组分抽提出来,取瓶中气相部分用气相色谱法快速测定,测定结果表明样品中轻组分大部分是C6组分.大于C7的组分很少,该方法快速准确,可以满足样品的快速检测.     

甲苯热解机理的AM1研究(Ⅰ)热力学分析

在实验的基础上,本文用Gaussian98程序包中AM1法UHF计算,对碳材料用碳前驱体甲苯的热裂解反应机理进行了研究。在对反应物,产物自由基的结构进行能量梯度法全优化的同时,计算了不同温度下的标准热力学参数（298－1073K）。热力学计算结果表明：（1）当甲苯的热裂解温度相对较低时（773K左右）,热力学计算结果首先支持苯环上甲基C－H键的断裂生成苯基自由基并继而生成联二甲苯的反应;随着温度的提高（达1073K时）,生成苯自由基和甲基自由基的反应比例将大生成苄基自由基的比例;该反应机理与实验结果基本一致。（2）采用Gaussian98程序包中AM1法中的UHF计算,较适合低级芳香烃热裂解反应机理的理论研究。