Study of time resolution by digital methods with a DRS4 module

A new Digital Pulse Processing(DPP) module has been developed, based on a domino ring sampler version 4 chip(DRS4), with good time resolution for La Br3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes(PMTs). Two PMTs were coupled with La Br3 scintillators and placed on opposite sides of a radioactive positron22 Na source for 511 ke V γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps(FWHM), obtained by the digital constant fraction discrimination(d CFD) method,which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography(PET) with time of flight(TOF), as well as for scintillation timing measurement,such as in TOF-?E and TOF-E systems for particle identification, with picosecond accuracy timing measurement.Furthermore, this module is more simple and convenient than other systems.     

基于“工程实践能力培养”的《化学工艺学》课程建设与教学实践

针对工程实践能力的培养,以《化学工艺学》课程建设为切入点,对教学内容与教材建设、教学模式与教学方法、教学队伍、考核内容及考核方法等方面的改革进行了理论和实践探索,取得了一定成效。编撰出版了工程特色突出、注重工程实践能力培养的普通高等教育"十二五"规划教材《化学工艺学》,创建并实践了集先进性、创新性和实用性于一体的"三型案例并用"教学法,探索实践了"将理论教学与毕业实习、化工仿真实训相结合"的能够强化工程实践能力培养的新型教学模式。     

等离子体条件下金属和金属氧化物对甲烷氧化反应的催化活性

The uses of methane, the major component in natural gas, have been investigated by many research groups throughout the world. A number of catalysts, single or binary, have been proposed for the oxidative coupling of CH4 with CO2 as the oxidant[1～6]. Binary metal-oxide catalysts, such as La2O3-ZnO and CaO-ZnO, showed higher C2 hydrocarbon selectivity (＞80%) with low CH4 conversion (＜6%) at high temperatures (750～850 ℃)[7～9].     

非平衡等离子体下乙烷脱氢反应的研究

在低温常压下,对脉冲电晕等离子体应用于乙烷脱氢反应进行了研究。考察了等离子体注入功率和添加气对反应的影响,并探讨了等离子体条件下乙烷脱氢反应的机理。研究结果表明：乙烷在脉冲电晕等离子体中可发生转化反应,主要产物是乙炔。乙烷转化率和乙炔收率随等离子提功率增加不断提高。添加气二氧化碳的加入提高了乙烷转化率,当体系中CO2浓度为50％时乙炔收率达到峰值。向反应体系中添加氢不仅促进了乙烷的转化,提高了乙炔选择性,且抑制了积碳的形成。     

等离子体作用下甲烷氢化偶联

在常温常压下,研究了脉冲放电等离子体及其协同催化剂强化CH₄氢化偶联反应.结果表明:脉冲电晕等离子体条件下,甲烷中引入氢气可以实现偶联,而且随着氢气引入量的增加甲烷的转化率以及C₂收率增大,积碳减少;脉冲电压和重复频率影响CH₄的转化;引入Ni/γ -Al₂O₃催化剂后可改善产物C₂烃的分布,等离子体法制备的Ni/γ -Al₂O₃催化剂性能优于化学法制备的Ni/γ -Al₂O₃催化剂.开辟了一条甲烷偶联新技术路线.     

有氧气氛下等离子体甲烷偶联反应的研究

近年来,非平衡等离子体应用于甲烷直接转化的研究备受关注,但多数研究工作采用的是低气压下微波或高频放电产生的非平衡等离子体[1－9].在常压下获得非平衡等离子体一般是通过脉冲电晕放电或介质阻挡放电产生的[10,11].Liu等[12]采用电晕放电（非脉冲）研究了CH4＋O2＋He(pCH4=2.03×104Pa,pO2=5.07×103Pa,He平衡)体系的甲烷偶联反应.　　如前文[13]所述,脉冲电晕等离子体是一种新型常压非平衡等离子体,其电子通过上升沿陡峭的窄脉冲电场加速而获得能量（1～20eV）.将其应用于甲烷偶联反应,不仅具有反应条件温和（常温常压）…     

蚕茧层中色氨酸的高效液相色谱测定法

本文建立了用高效液相色谱(HPLC)分析蚕茧层中色氨酸的方法,该法未见报道。蚕茧层由丝蛋白组成,丝蛋白是由十八种氨基酸组成。其中十七种氨基酸是用盐酸水解样品,采用氨基酸仪可同时测定。由于盐酸使色氨酸分解,不能测定。为补充测定色氨酸的简便、准确的方法,我们采用不分解色氨酸的碱法处理样品,用HPLC法分析色氨酸。为保护色谱柱,用超滤膜滤去大分子。对各种蚕茧层不同水解情况进行了考察,分析了柞蚕茧、桑蚕茧层中的色氨酸,结果与报道的比色法、荧光法相一致;还分析厂东北天蚕茧层中色氨酸,补充了尚未分析的数据。该法的精度、回收率都令人满意。也证明了虽然文献[1][5]方法复杂粗糙,但也是可行的。     

脉冲电晕等离子体作用下甲烷偶联反应--Ⅰ.无氧气氛下

在常温常压下,对脉冲电晕等离子体应用于甲烷无氧气氛下脱氢偶联反应进行了研究．考察了脉冲电压极性和等离子体注入能量对甲烷脱氢偶联反应的影响,并引入能量效率对等离子体能量与甲烷脱氢偶联反应的耦合进行了讨论．结果表明,正电晕的能量效率高于负电晕．在正电晕条件下,当脉冲重复频率为 ６６ Ｈｚ和能量密度为 １７８８ｋＪ／ｍｏｌ时,甲烷转化率可达４４．６％, Ｃ_２烃单程收率可达３１．６％,其中乙炔单程收率达３０．１％．甲烷转化率与能量密度Ｐ／Ｆ的关系满足－ｌｎ（１—Ｘ）＝ｋ（Ｐ／Ｆ）．在实验考察的能量范围内,Ｃ_2烃收率与能量密度Ｐ／Ｆ呈顺变关系,但能量效率随能量密度的增加而降低．     

等离子体条件下甲烷在CO_2存在下的脱氢偶联(英文)

在常温常压下,利用脉冲电晕等离子体研究了甲烷和二氧化碳的转化。在等离子体一催化反应装置上,测试了Ｐｄ／γ－Ａｌ２Ｏ３对甲烷偶联的催化活性。实验发现,在脉冲电晕等离子体作用下,甲烷和二氧化碳被转化为Ｃ２烃、ＣＯ、Ｈ２、Ｏ２、少量积碳和高碳烃;在等离子体条件下引入Ｐｄ／γ－Ａｌ２Ｏ３催化剂,能够有效地改善甲烷偶联产物Ｃ２烃的分布,有利于生成更高附加值的乙烯。     

Synthesis and Crystal Structure of a Novel Double Ladder-like Cadmium Coordination Polymer Constructed by Isophthalate and Imidazole

A novel double ladder-like cadmium coordination polymer with isophthalate as bridging ligands and imidazole as non-chelating capping ligands was obtained by a hydrothermal reaction. The crystal is of triclinic, space group P1 with a = 10.266（2）, b = 11.573（2）, c = 12.651（3） A, α = 89.95（3）, β= 74.64（3）,γ = 68.54（3）°, C50H44Cd4N12O18, Mr = 1550.57, V= 1341.1（5）A3, Dc = 1.920 g/cm3, F（000） = 764, p = 1.651 cm-1 and Z = 1. The final refinement gave R = 0.0342 and wR = 0.0738 for 5925 observed reflections with I 〉 2σ（I）. The crystal structure involves two different ladder-like chains, which are further connected to form a ladder-like double chain architecture via hydrogen bonding interactions, extending along the b axis. The weak interactions including hydrogen bonds and π-π staking interactions contribute to the alignment of the complex in the crystalline state.