10～100 MeV/u能区重离子反应机制的研究

把QMD模型扩展至10～100MeV/A能区，研究了该能区的重离子碰撞，并仔细检验了初始核在基态时传播的稳定性条件。~(40)Ca+~(40)Ca系统，在10 ～ 100MeV/A能区范围内研究了重离子反应机制随入射能量及碰撞参数的演化情况。我们发现，反应机制随能量的变化并不是突然的跃迁，而是一个连续的变化过程，不同的反应机制可以同时存在并发生竞争。在中心碰撞时，反应机制从全融合发展至非全融合，最后演化至碎裂机制。在周连碰撞时，随着入射能量的增加，根据我们提出的关于深部非弹碰撞和参加者－旁观者质量分布的判据，反应机制的可能变化趋势为从非完全融合或深部非弹碰撞到参加者－旁观者，最后发展至碎裂反应。我们知道，目前还没有人用QMD模型来研究过渡能区DIC机制的基本特征，我们还对~(20)(25Mev/A)+~(20)Ne系统周边碰撞时DIC机制的基本特征作了研究，计算结果表明：在中能区，DIC机制仍然存在，同时，在质量分布、旋转效应及能量损失方面具有低能时相同的特征，但与低能DIC的明显差别在于，出射的中间质量碎片已成为质量分布的主要部分，出射的轻粒子数目也相对增多。当碰撞参数小于7fm时，这里存在着不同反应机制的共存及竞争。根据质量分布随时间的演化情况，我们发现，中间质量碎片主要是由动力学过程中平均场涨落引起的动力学不稳定性造成的，统计衰变也贡献较小的一部分。由粗糙估计可以看出，25MeV/A时~(20)Ne+~(20)Ne系统的DIC机制仍然是一个趋向于平衡过程。相又于低能区，中能区的周边碰撞显得相当复杂

Determination of organophosphate and carbamate pesticides based on enzyme inhibition using a pH-sensitive fluorescence probe

A flow injection system for the determination of organophosphate and carbamate pesticides is described. A sensitive fluorescence probe was synthesized and used as the pH indicator to detect the inhibition of the enzyme acetylcholinesterase (ACNE). The percentage inhibition of enzyme activity is correlated to the pesticide concentration. Several parameters influencing the performance of the system are discussed. The detection limits of 3.5, 50, 12 and 25 mug/l for carbofuran, carbaryl, paraoxon and dichlorvos, in pure water, respectively were achieved with an incubation time of 10 min. A complete cycle of analysis, including incubation time, took 14 min. The detection system has been applied to the determination of carbofuran in spiked vegetable juices (Chinese cabbage and cole), achieving recovery values between 93.2 and 107% for Chinese cabbage juice and 108 and 118% for cole juice at the different concentration levels assayed. (C) 2004 Elsevier B.V. All rights reserved.

Study on conical columns with different conical angles for semi-preparative liquid chromatography

The dynamic flow profiles and separation performances in conically shaped preparative liquid chromatographic columns (inlet i.d. larger than outlet i.d.) with three different angles (7, 10 and 15degrees) were studied and compared with cylindrical column of the same length and internal volume. The shapes of dynamic flow profiles were studied by on-column visualization method. The transparent chromatographic columns made of polymethyl methacrylate (PMMA), packed with C-18 bonded silica, were immerged into a cubic pool filled with glycerol to eliminate the cylindrical and conical lens effect. The flow profiles of colored iodine solution in the columns were observed clearly using cyclohexane as mobile phase since the refractive indices of C-18, column wall and the mobile phase are very close. In the conical column of 15degrees (20-7 mm i.d.) the mobile phase in the central region migrated slower than in wall region as it moved toward the column outlet, while in the conical column of 7degrees (17-11 mm i.d.) the mobile phase in the central region migrated faster than in wall region just like in cylindrical column. We found that a plug-like flow profile was generated in the conical column of 10degrees (18-9 mm i.d.) during the whole migration process. A carmine and brilliant blue mixture was used as a probe to test the separation ability of the columns. The resolutions of the two compounds on the conical column of 7, 10, 15degrees and on the cylindrical column were 0.6, 1.57, 1.29 and 0.8, respectively. (C) 2003 Elsevier B.V. All rights reserved.

辅酶Q_(10)高产菌株的选育

以根癌土壤杆菌(Agrobacteriumtumefaciens)1.1416为出发菌株,考察了紫外线(UV)、1-甲基-3-硝基-1-亚硝基胍(NTG)和硫酸二乙脂(DES)对该菌株产生辅酶Q10能力的诱变效应,并结合辅酶Q10合成途径设计了快速筛选辅酶Q10高产菌株的模型。结果表明:NTG和DES交替诱变处理根癌土壤杆菌1.1416具有较好的诱变效果,筛选到的突变株AGR0619和AGR0610的辅酶Q10总产量分别提高了137.49%和156.07%。

共基质对10株细菌降解苯并芘的作用研究

从石油污染的污泥中分离驯化出10株细菌(SB01～SB10),利用生物摇床实验对其降解苯并芘(BaP)的效能进行试验,研究了有(或无)共基质(葡萄糖Glu,或菲PHE)对细菌降解BaP的影响,并采用ANOVA和Tukey多重比较进行分析。结果表明(,1)当以BaP为惟一碳源和能源且BaP初始浓度为50mg·L-1时(MS1),SB01的降解率最高,5d可降解31.0%;以Glu为共代谢基质时(MS2),SB09的降解率最高,可达36.9%;以PHE为共代谢基质时(MS3),SB01对BaP的降解率为46.0%。(2)Glu对SB01、SB02、SB03、SB07、SB10降解BaP有抑制作用,对SB01抑制作用最明显,使SB01的降解率降低了13.1%,Glu对SB05,SB08降解率无明显促进或抑制作用。(3)PHE对细菌降解BaP均表现出促进作用,对SB01的促进作用最明显,使其降解率提高15.0%。(4)Glu对SB09的促进作用大于PHE的促进作用,而对SB06,PHE的促进作用大于Glu。

共基质对10株细菌降解芘的作用

从石油污染的污泥中分离出10株细菌(SB01-SB10),研究了有(或无)共基质(葡萄糖Glu,或菲PHE)对细菌降解芘(PYR)的影响.结果表明:当以PYR为唯一碳源和能源时(MS1),SB01的PYR降解率最高,5d可降解30.4%;以Glu为共代谢基质时(MS2),SB09的PYR降解率最高,可达37.7%;以PHE为共代谢基质时(MS3),SB10的PYR降解率为50.2%.Glu抑制SB01、SB03对PYR的降解,对SB01抑制作用最明显,使SB01的PYR降解率降低7.9%;Glu对SB02、SB07、SB08、SB10降解率无明显促进或抑制作用.PHE对细菌降解PYR均有促进作用,对SB10的促进作用最明显,使其降解率提高29.8%.Glu与PHE对SB04和SB09降解PYR的促进作用无显著差异,而对其它各菌株而言,PHE对PYR降解的促进作用大于Glu.

曲面效应法优化辅酶Q_(10)发酵条件

以根癌土壤杆菌(Agrobacterium tum efaciens)1.1416的突变株AGR 0610为出发菌株,采用P lackett-Burm an设计法(P lackett-Burm an design,P-B)对影响AGR 0610发酵产辅酶Q10的相关因素进行了研究,选取到4种有显著效应的因素:糖蜜、大豆蛋白胨、玉米浆和蛋氨酸.再采用响应曲面法(response surface m ethodology,RSM)对这4种因素的最佳水平范围进一步探讨,得到二次回归方程,优化了培养基组成.当这4种因素分别取值为1.02%、0.49%、0.29%和0.34%时,辅酶Q10产量有最大预测值38.88 mg/L,并被实验所证实.图6表4参8

近10年来中国农村居民点用地时空特征

利用20世纪90年代中国1:10万土地利用动态变化数据,利用单元自动机和人工神经网络模型对中国农村居民点用地进行了区划。在此基础上,研究了90年代中国农村居民点用地动态变化时空格局。研究表明,农村居民点用地受区域位置、经济发展和国家政策的影响。90年代前5年,受沿海开放政策和经济高速发展的影响,长江三角洲、珠江三角洲和华北平原农村居民点用地扩展较快,中西部地区农村居民点用地扩展较慢;90年代后5年,在沿海地区经济发展速度放慢和国家实施耕地资源保护条例的情况下,沿海地区农村居民点用地扩张受到抑制,西部地区扩展加快。90年代中国经济体制处于由计划经济向市场经济转轨的过程中,农村居民点用地的动态变化格局受到经济发展和土地利用政策的深刻影响。

Mo掺杂对高纯Ce_(1-x)Nd_xO_(2-x/2)(x=0.10,0.15)体系烧结温度及晶界电性能的影响

用柠檬酸硝酸盐法制备高纯Ce1-xNdxO2-x/2(x=0.10,0.15)固溶体,加入摩尔分数为5%的Mo,研究了Mo掺杂对烧结温度、结构及电性能的影响.通过X射线衍射、电感偶合等离子体和场发射扫描电镜等手段对氧化物进行了结构表征,采用交流阻抗谱测试其电性能.柠檬酸硝酸盐法制备的前驱体经1450℃烧结24 h得到致密度大于96%的陶瓷材料;加入5%Mo,在1250℃下烧结8 h即可达到理想的致密度(>95%).加入Mo在烧结过程中可加快晶界迁移,促进晶粒生长,显著提高了晶界电导率.在600℃时Ce0.85Nd0.15O1.925的晶界电导率为2.56 S/m,加入Mo后材料的电导率增加到5.62 S/m.

Syntheses, crystal structures, visible and near-IR luminescent properties of ternary lanthanide (Dy3+, Tm3+) complexes containing 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1,10-phenanthroline

The ligands 4,4,4-trifluoro-1-phenyl-1.3-butanedione (Hbfa) and 1,10-phenanthroline (phen) were used to prepare ternary lanthanide (Ln) complexes [Dy(bfa)(3)phen and Tm(bfa)(3)phen]. Crystal data: Dy(bfa)(3)phen C(42)H(26)FqN(2)O(6)Dy, triclinic, P (1) over bar, a= 9.9450(6) angstrom, b = 14.0944(9) angstrom, c = 14.6043(9) angstrom, alpha = 82.104(1)degrees, beta = 87.006(1)degrees, gamma = 76.490(1)degrees, V = 1971.1(2)angstrom(3), Z = 2; Tm(bfa)(3)phen C42H26F9N2O6Tm, triclinic, P (1) over bar, a = 9.898(5)angstrom, b = 13.918(5)angstrom, c = 14.753(5)angstrom, a = 83.517(5)degrees, alpha = 86.899(5)degrees, gamma = 76.818(5)degrees, V = 1965.3(14)angstrom(3), Z = 2. The coordination number of the central Ln(3+) (Ln = Dy, Tm) ion is eight, with six oxygen atoms from three Hbfa ligands and two nitrogen atoms from the phen ligand.

Bis(2,2 '-bipyridine)(5,6-epoxy-5,6-dihydro-[1,10] phenanthroline)ruthenium: Synthesis and electrochemical and electrochemiluminescence characterization

In this work, an electrochemiluminescence (ECL) reagent bis(2,2'-bipyridine)(5,6-epoxy-5,6-dihydro-[1,10]phenanthroline)ruthenium complex (Ru-1) was synthesized, and its electrochemical and ECL properties were characterized. The synthesis of Ru-1 was confirmed by IR spectra, element analysis, and H-1 NMR spectra. For further study, its UV-vis absorption and fluorescence emission spectra were investigated. Ru-1 also exhibited quasi-reversible Ru-II/Ru-III redox waves in acetonitrile solution. The aqueous ECL behaviors of Ru-1 were also studied in the absence and in the presence of tripropylamine.

Facile synthesis of 9,10-diarylphenanthrenes and poly(9,10-diarylphenanthrene)s

One-pot reduction of 9,10-diaryl-9,10-dihydrophenanthrene-9,10-diols to 9,10-diarylphenanthrenes was achieved with Zn/H+ in acetic acid. Accordingly, various novel phenanthrenes and polyphenanthrenes with efficient blue emission were easily synthesized.