溶液沉淀法制备ZnS-氟碳聚合物电纺纤维复合光催化材料

以含有羧基的氟碳聚合物电纺纤维毡为载体,采用均匀沉淀法于常温溶液中在纤维表面制备分布均匀、直径50 nm左右的硫化锌-氟碳聚合物电纺纤维复合光催化材料. 在紫外光照220 min时,对次甲基蓝降解的残留质量分数为0.03%,低于同等条件下的纳米ZnS粉体,重复5次光降解其仍具有较好的稳定性.     

聚合物分散液晶单体4,4′-二[6-(丙烯酰氧基)己氧基]联苯的合成

利用丙烯酰氯代替丙烯酸钾与4,4′-二(6-溴己氧基)联苯反应改进了制备4,4′-二[6-(丙烯酰氧基)己氧基]联苯(BAB6)的合成路线。改进前的反应温度较高,中间产物溶解度小,产物呈淡黄色,收率仅12.4%;改进后在室温反应,中间产物溶解度较高,产物呈白色,收率达到46.8%。采用1HNMR、13CNMR和元素分析对中间体和BAB6结构进行了表征。由改进后合成的单体,制备了具有快速响应的聚合物分散液晶(PDLC)膜,响应时间约2ms。扫描电子显微镜观察的结果表明,PDLC中形成了聚合物网络结构。     

Preparation and characterization of poly glycidyl methacrylete–zirconium dioxide–β-cyclodextrin composite matrix for separation of isoflavones through expanded bed adsorption

The specially prepared adsorbent is most important in realizing the expanded bed adsorption (EBA) process. In the present work, a novel poly glycidyl methacrylete–zirconium dioxide–β-cyclodextrin (PGMA–ZrO₂–β-CD) composite matrix for EBA has been first prepared. Wet density, water content and pore properties of the composite beads have been investigated, which shows good expansion and stability in EBA. The application of custom-made adsorbent has been investigated to recover isoflavones from soy molasses. The recovery is up to 90% and the purity of isoflavones obtained is 75.4%. Compared with the traditional purification processes, EBA has the advantage of high efficiency and integrality, which leads to large reduction in operation time and cost.     

Modeling and analyzing of torsional dynamics for helical gear pair considered double and three teeth drive-side meshing

Helical gears are generally considered to be more stable than spur gears. But rattling of the helical gear transmission is found in the engineering practice. The torsional dynamics equations of helical gear pair in high-speed railway gearbox are established in order to reveal the rattling mechanism of helical gear transmission. Double and three teeth pair drive-side meshing are considered. The multi-state meshing zone, load distribution rate and time-varying stiffness determined by contact ratio are analyzed and calculated. The dynamic characteristic transition process of the system is analyzed according to the bifurcation diagrams and the corresponding top Lyapunov exponent (TLE) diagrams, phase portraits, Poincaré maps and time history spectrums of dynamic meshing force based on the calculation of these parameters. The tooth disengagement, tooth back-side contact and their parameter range are found. This study can provide theoretical basis for rattling suppression and transmission stability improvement of helical gear pair.

     

二甲胺同步辐射光电离解离机理的质谱研究

利用同步辐射光源，结合飞行时间质谱，在超声射流冷却条件下研究了(CH_3) _2NH(DMA)的光电离解离机理。实验观察到四种主要离子(CH_3)_2NH·~+， CH_3NH~+CH_2，CH_2NH_2~+和CHNH~+，质荷比分别为m/z = 45，44，30和28。四种 离子的出现势（AE）分别为8.26，9.52，11.93和11.27 eV，其中分子电离热IP = （8.26 ± 0.01） eV，计算得到分子离子的生成热Δ_fH~o = 778.55 kJ/mol。 分析表明离子CH_3NH~+CH_2来自母体离子的α去H过程。其他碎片离子由后续逐级 解离去H反应以及脱CH_3通道生成。     

溶液沉淀法制备ZnS-氟碳聚合物电纺纤维光催化复合材料

利用含有羧基的氟碳聚合物电纺纤维为载体和模板材料,常温溶液条件下利用均匀沉淀法,在纤维表面负载硫化锌纳米粒子。通过控制反应条件,得到氟碳聚合物电纺纤维表面均匀分布、无团聚的直径在十几纳米左右的硫化锌-氟碳聚合物电纺纤维光催化复合材料。光催化复合材料的高比表面积和水中有机物富集能力使其在紫外光辐照条件下对次甲基蓝降解效率明显高于ZnS粉体。重复降解实验显示复合材料具有较好的稳定性和重复光催化能力。     

Study on safety characteristics of the spur gear pair considering time-varying backlash in the established multi-level safety domains

Nonlinear Dynamics - Multi-state meshing characteristics induced by backlash and contact ratio in the gear pair are an unsolved puzzle about its relationship to safety characteristics of the gear...     

用无机硅钛原料合成无铝Ti-β分子筛的研究

Ti-β zeolite has been successfully synthesized by using fumed silica and TiCl₃ as silicon and titanium sources respectively under the hydrothermal conditions.Because inorganic Si and Ti compounds instead of relative organic metal compounds were used in the synthesis of Ti-β ,and then a tedious hydrolysis procedure of organic metal compounds was avoided,the gelatin time was reduced,the synthesis process was simplified and easily reproduced.Importantly,the synthesized Ti-β zeolite,which was characterized by XRD, FT-IR, UV-Vis and DTA, didn't exist TiO₂ crystals and had a good quality.     

Dy3+离子掺杂的全色荧光粉Ca9La(PO4)7的制备及发光特性

采用高温固相法合成了Ca₉La(PO₄)₇:Dy³⁺发光材料. 荧光粉的晶体结构和微观尺寸由X射线粉末衍射(XRD)仪和扫描电子显微镜(SEM)测定. 光致激发和发射光谱发光揭示了材料的光学特性. 实验结果显示: Ca₉La(PO₄)₇:Dy³⁺能够有效吸收紫外-可见光(300-460 nm)而被激发, 呈现一系列的吸收峰. 样品在350 nm近紫外光激发下, 有较强的蓝光(481 nm)和黄光(573 nm)两个窄带发射, 混合成优质的白光发射, 该白光色坐标在国际照明委员会(CIE)色品图中分布在无色点D65 (0.313, 0329)周围. 随着掺杂Dy³⁺离子的摩尔分数的增加, 两种发射均发生浓度猝灭现象, Dy³⁺离子的最佳掺杂为0.05(摩尔分数), 电偶极-电偶极相互作用是主要的猝灭机理.     

Evolutionary mechanism of safety performance for spur gear pair based on meshing safety domain

Nonlinear Dynamics - Micro-vibrations in satellites mainly originate from the control moment gyroscope because of its mass imbalance, which seriously affect the image accuracy of high-resolution...