Multi-electron processes in 4.15-11.08 keV/u(13)C(6+) on argon collisions

The relative partial cross sections for C-13(6+)-Ar collisions at 4.15-11.08 keV/u incident energy are measured. The cross-section ratios sigma(2E)/sigma(SC), sigma(3E)/sigma(SC), sigma(4E)/sigma(SC) and sigma(5E)/sigma(SC) are approximately the constants of 0.51 +/- 0.05, 0.20 +/- 0.03, 0.06 +/- 0.03 and 0.02 +/- 0.01 in this region. The significance of the multi-electron process in highly charged ions (HCIs) with argon collisions is demonstrated (sigma(ME)/sigma(SC) as high as 0.79 +/- 0.06). In multi-electron processes, it is shown that transfer ionization is dominant while pure electron capture is weak and negligible. For all reaction channels, the cross-sections are independent of the incident energy in the present energy region, which is in agreement with the static characteristic of classic models, i.e. the molecular Coulomb over-the-barrier model (MCBM), the extended classical over-the-barrier (ECBM) and the semiempirical scaling laws (SL). The result is compared with these classical models and with our previous work of C-13(6+)-Ne collisions

Multi-electron processes in C-13(6+) ions with neon collisions in energy region 4.15-11.08 keV/u

The cross-section ratios of double-, triple-, quadruple-, and the total multi-electron processes to the single electron capture process sigma(DE)/sigma(SC), sigma(TE)/sigma(SC), sigma(QE)/sigma(SC) and sigma(ME)/sigma(SC)) as well as the relative ratios among reaction channels in double-electron active, triple-electron active and quadruple- electron active are measured in C-13(6+) -Ne collision in the energy region of 4.15-11.08 keV/u by employing position-sensitive and time-of-flight coincident techniques. It is determined that the cross-section ratios sigma(DE)/sigma(SC), sigma(TE)/sigma(SC), sigma(QE)/sigma(SC) and sigma(ME)/sigma(SC) are approximately the constants of 0.20 +/- 0.03, 0.16 +/- 0.04, 0.06 +/- 0.02 and 0.42 +/- 0.05. These values are obviously smaller than the predictions of the molecular Coulomb over-the-barrier model (MCBM) [J. Phys. B 23 (1990) 4293], the extended classical over-the-barrier model (ECBM) [J. Phys. B 19 (1986) 2925] and the semiempirical scaling laws (SL) [Phys. Rev. A 54 (1996) 4127]. However, the relative ratios among partial processes of DE, TE and QE are found to depend on collision energy, which suggests that the collision dynamics depends on the collision velocity. The limitation of velocity-independent character of ECBM, MCBM and SL is undoubtedly shown.

25MeV/u~(40)Ar~(15+)+~(209)Bi反应的裂变研究

本文首先回顾了重离子物理学的发展简史，并介绍了当前的一些关于重离子反应的理论方法，同时对于现在核物理的研究热点，热核的特性进行了概括性的叙述．由于裂变是作者工作的重点，因此在文章中，对裂变反应的理论也进行了介绍．为了能够清楚全面的说明我们的工作，本文对于实验装置和探测器也给出了详细的描述．最后，文章对25 MeVu Ar+Bi反应中的裂变进行了讨论．在这些讨论中，我们分析了反应中与裂变相关的数据，得到了碎片的质量，动能分布。同时运用与碎片相关联的4He粒子能谱提取了核温度和裂前裂后的4He粒子多重性，并利用这一数据计算了不同初始激发能下的裂点激发能和裂变时标.

2—酮基—L—古龙酸高产融合子15的形态学及生理生化特征的研究

由地衣芽孢杆菌（Ｂａｃｉｌｌｕｓｌｉｃｈｅｎｉｆｏｒｍｉｓ）Ｈ１９和２—酮基—Ｌ—古龙酸产生菌Ｓ１９的原生质体融合，得到了既能独立生长传代，又能产生２—酮基—Ｌ—古龙酸的１５号融合子。其菌落和菌体形态类似于Ｈ１９亲本，其生理生化特性也大多酷似Ｈ１９亲本而不同于Ｓ１９亲本。但其产生２—酮基—Ｌ—古龙酸的特性、乙醇氧化反应、石蕊牛奶产酸以及精氨酸双水解酶阴性等特点又酷似Ｓ１９亲本而不同于Ｈ１９亲本。其氧化酶反应、初始生长ｐＨ范围、苯丙氨酸和色氨酸脱氨酶反应则不同于双亲本。其菌体的氨基酸组份及含量也与双亲有一定差异。

Vc二步发酵新组合菌系B_(15-14)的筛选及其条件优化

筛选出了一组Vc二步发酵的新组合菌系(命名为B15-14),研究了环境因子对新菌系产酸的影响。结果显示:新组合菌系的最适底糖浓度为7%;温度为29~33℃,31℃为最适;适当增加通气量(20~30 mL装液量,250 mL三角瓶)有利于产酸;起始pH值范围为6.0~7.5;以B t菌做伴生菌时,发酵40 h就已达到终点,明显缩短了发酵时间。

北方农牧交错带耕地面积变化驱动力研究——以沽源县近15年为例

土地利用/土地覆被变化研究中,驱动力的研究是一个重要方面。从地理学的角度入手,将耕地面积变化的驱动因子归为降水量、经济、人口、技术、政策等方面,得到定量度量各驱动因子影响的多元线性模型,并用路径分析方法探讨驱动因子与耕地面积变化以及各驱动因子之间的关系。结论主要是:税费负担的加重会迫使农民开垦更多的耕地,取消农业税有利于生态建设;人口压力使得耕地面积扩大,不利于退耕还林草,因此要注意控制当地的人口数量;提高种植业人均纯收入水平,有利于控制开垦面积;在各驱动因子中,技术因素和经济因素对耕地面积变化最具影响。

Direct synthesis of Al-SBA-15 mesoporous materials via hydrolysis-controlled approach

Aluminum-substituted mesoporous SBA-15 (Al-SBA-15) materials were directly synthesized by a hydrolysis-controlled approach in which the hydrolysis of the silicon precursor (tetraethyl orthosilicate, TEOS) is accelerated by fluoride or by using tetramethyl orthosilicate (TMOS) as silicon precursor rather than TEOS. These materials were characterized by powder X-ray diffraction (XRD), N-2 sorption isotherms, TEM, Al-27 MAS NMR, IR spectra of pyridine adsorption, and NH3-TPD. It is found that the matched hydrolysis and condensation rates of silicon and aluminum precursors are important factors to achieve highly ordered mesoporous materials. Al-27 MAS NMR spectra of Al-SBA-15 show that all aluminum species were incorporated into the silica framework for the samples prepared with the addition of fluoride. A two-step approach (sol-gel reaction at low pH followed by crystallization at high pH) was also employed for the synthesis of Al-SBA-15. Studies show that the two-step approach could efficiently avoid the leaching of aluminum from the framework of the material. The calcined Al-SBA-15 materials show highly ordered hexagonal mesostructure and have both Bronsted and Lewis acid sites with medium acidity.

Demulsification of emulsions exploited by enhanced oil recovery system

Experimental data are presented to show the influence of the enhanced oil recovery system's components, alkali, surfactant, and polymer, on the demulsification and light transmittance of the water separated from the emulsions. Among which, the effects of surfactants, polyoxyethylene (10) alkylphenol ether (OP-10) and sodium petroleum sulfonate (CY-1) on emulsion stability, are the strongest of any component, the effects of polymer, hydrolytic polyacrylamide (HPAM) 3530S, on emulsion stability are the weakest. This research also suggests a possible emulsion minimization approach, which could be implemented in refineries utilizing microwave radiation. Compared with conventional heating, microwave radiation can effectively enhance the demulsification rate by an order of magnitude and increase the light transmittance of the water separated from the emulsions. The demulsification efficiency may reach 100% in a very short. time under microwave radiation.

凋落叶多样性对杉木幼苗生长及吸收~(15)N标记硫铵的影响

利用15N硫铵研究了凋落叶多样性对杉木幼苗生长及养分吸收的影响 .结果表明 ,凋落叶多样性的增加有利于盆栽杉木幼苗的生长 .杉木、火力楠、红栲和刺楸 4种凋落叶混合处理后 ,杉木幼苗的生长量最大 ;杉木、火力楠、刺楸 3种凋落叶混合处理后的杉木幼苗生长量次之 ,其它依次为杉木、火力楠、红栲 3种凋落叶混合处理 >杉木和刺楸凋落叶处理 >杉木和红栲凋落叶处理 >对照 >杉木和火力楠 2种凋落叶混合处理 >杉木凋落叶处理 .就杉木幼苗对硫铵氮的吸收率而言 ,不作任何处理的杉木幼苗吸收率最高 ,其次为杉木、火力楠、红栲和刺楸 4种凋落叶混合处理 ,其它依次为杉木、火力楠、刺楸 3种凋落叶混合处理和杉木、火力楠、红栲 3种凋落叶混合处理 >杉木和刺楸凋落叶处理 >杉木和红栲凋落叶处理>杉木和火力楠 2种凋落叶混合处理 >杉木凋落叶处理 .另外 ,用凋落叶处理后 ,土壤中硫铵氮的残留量比不作凋落叶处理的土壤多 ,硫铵氮的总回收量也比不作凋落叶处理的土壤大幅增加 ,而且凋落叶多样性的增加也会增加硫铵氮的残留量 .