喹(噁)啉-2-羧酸标准物质的制备研究

建立了一种喹(噁)啉-2-羧酸(QCA)合成工艺路线,选择适当的方法对产品进行纯化,制备标准品候选物,并利用IR、UV、1 HNMR和MS技术对其进行定性鉴定.卡尔费休法和热重分析法分别用于水分和无机杂质的分析;建立优化了QCA主成分定值的高效液相色谱(HPLC)法,对含量进行测定;对喹(噁)啉-2-羧酸进行了均匀性、稳定性研究.结果表明,研制的喹(噁)啉-2-羧酸标准物质均匀性良好,稳定时间12个月,可以用于残留检测的定性和定量分析.     

Al-Zn-Mg-Cu合金新型等通道转角双向镦挤变形行为分析

以超高强度Al-Zn-Mg-Cu合金为研究对象,采用数值模拟和实验相结合的方法对其等通道转角双向镦挤过程进行分析。结果发现,变形过程可以分为近局部镦粗、剪切变形、最后填充三个阶段,变形结束后试样根据金属流动和网格畸变程度划分为小变形区、不变形区、剪切变形区、剧烈变形区。不同加载方式使变形区域发生不同程度偏移,上下冲头速度差越大,变形均匀性越差,速度比为1时可获得最大的应变量为3.97,且变形均匀性系数最低为1.89。同时,对不同路径下的多道次变形行为进行研究,发现4道次结束后,B路径比A路径变形更加均匀充分,其变形均匀性系数降低了29 %,剪切变形区占比提升了14 %。     

基于机器视觉的成形网透气量无损检测方法

本课题提出了一种无损、全方位的成形网透气量检测方法,该方法利用工业相机采集图片数据,通过大津法计算开孔率,并根据开孔率与透气量的关系计算透气量。针对织物52SSB网面进行测试,该方法测得结果与透气仪测得结果最大相对误差为0.33%,可实现无损、全方位检测。     

改性大豆分离蛋白-磷脂复合物对冰淇淋品质的影响

针对大豆分离蛋白(SPI)取代部分乳粉生产冰淇淋,产品膨胀率低、易融化、口感较硬和有豆腥味等问题,本实验采用超高压改性大豆分离蛋白(USPI)、大豆分离蛋白-磷脂复合物(SPI-PLW)和超高压均质改性大豆分离蛋白-磷脂复合物(USPI-PLW)分别替代乳粉生产冰淇淋,研究了不同改性条件的大豆蛋白对冰淇淋浆料的静态流变学、膨胀率、融化率、硬度和微观结构的影响。通过对比研究得出,以USPI-PLW为原料制作成的冰淇淋的各项标准都优于其它类型的大豆分离蛋白冰淇淋。USPI-PLW冰淇淋融化率为33.17%,膨胀率可达86.86%,较传统低脂冰淇淋融化率降低26.86%,膨胀率提高了94.84%,且储藏硬化后无较大冰晶,相对于传统冰淇淋口感更绵软。     

纯度标准物质HMX的制备及均匀性检验

以工业特级品HMX为基体,研究了HMX的纯化工艺,制备出军用纯度标准物质HMX.考察了用不同溶剂重结晶对HMX纯度的影响,选择用两种重结晶方法、分三步操作纯化HMX:首先用二甲基亚砜作溶剂,80℃溶解HMX,趁热过滤除去无机杂质和机械杂质后,用溶剂-非溶剂沉淀技术使HMX结晶析出;第二步以乙腈为溶剂重结晶纯化HMX,HMX的纯度达到99.60%以上;最后用MOS级无水乙醇煮洗,进一步去除有机杂质和溶剂残留.液相色谱分析、X射线粉末衍射分析和均匀性研究结果表明,所制备的纯度标准物质HMX纯度不小于99.70%,晶型为β型并且均匀性良好.     

Electrostatic Adsorption of a Colloidal Sintering Agent on Silicon Nitride Particles

Pressureless sintering of silicon nitride requires addition of sintering agents. The main part of this study was done in order to homogenize the distribution of sintering agents, in this case Y₂O₃, in a silicon nitride matrix. Colloidal 10-nm Y₂O₃ Particles were electrostatically adsorbed on Si₃N₄ particle surfaces. The adsorption was studied by X-ray fluorescence analysis and electrophoretic measurements. Addition of Y₂O₃ sol to a Si₃N₄ suspension decreased the viscosity of the suspension. The slip casting properties of Si₃N₄ suspensions with added Y₂O₃ sol were examined, and the homogeneity of Y₂O₃ in the green compacts was compared with conventionally prepared samples. An improved microstructural homogeneity was obtained when Y₂O₃ sol particles were adsorbed on the Si₃N₄ particle surfaces.     

Persistence Heterogeneity Testing in Panels with Interactive Fixed Effects

We consider large N,T panel data models with fixed effects, a common factor allowing for cross‐section dependence, and persistent data and shocks, which are assumed fractionally integrated. In a basic setup, the main interest is on the fractional parameter of the idiosyncratic component, which is estimated in first differences after factor removal by projection on the cross‐section average. The pooled conditional‐sum‐of‐squares estimate is consistent but the normal asymptotic distribution might not be centred, requiring the time series dimension to grow faster than the cross‐section size for correction. We develop tests of homogeneity of dynamics, including the degree of integration, that have no trivial power under local departures from the null hypothesis of a non‐negligible fraction of cross‐section units. A simulation study shows that our estimates and tests have good performance even in moderately small panels.     

碳热还原杂化前驱体合成SiC-TaC纳米复合粉体

以五氯化钽(TaCl5)、正硅酸乙酯(TEOS)和葡萄糖(C6H12O6 H2O)为原料制备了葡萄糖复合凝胶,凝胶经过450℃煅烧得到C-SiO2-Ta2O5杂化前驱体,通过碳热还原前驱体,于1200～1500℃合成了SiC-TaC纳米复合粉体,并用X射线衍射扫描电镜和能谱仪对产物进行表征。结果表明:凝胶中无定型的SiO2和Ta2O5可通过Si—O—Ta键合,均匀分布的Si—O—Ta—C长链使得杂化前驱体内部结合成为牢固的互穿网络结构;TaC于1200℃时得到,而SiC可在1400℃开始合成,反应可在1500℃完成。在不同的钽硅摩尔比下,SiC-TaC纳米复合粉体具有差异性形貌。当钽硅比约为0.02时,SiC与TaC纳米晶粒颗粒分布均匀,同质化明显。随着钽硅比的升高,SiC有从球状转变为纳米线状的趋势。     

注射成型中的熔体温度均匀性研究

注射成型中的熔体温度均匀性直接影响注射制品的最终质量，熔体温度均匀性的大小与螺杆设计，加工工艺条件关系密切，对不同工艺条件和螺杆几何参数时的轴向温差进行了测量，并讨论了轴向温差的形成机理及其与加工工艺条件和螺杆参数之间的关系。