Mn助剂对K-Co-Mo催化剂结构及CO加氢合成低碳醇性能的影响

通过溶胶-凝胶法合成了一系列Mn掺杂K-Co-Mo催化剂,并利用X射线衍射、N₂吸脱附、NH₃程序升温脱附、原位漫反射红外光谱以及X射线吸收谱等技术对催化剂的结构进行了表征.活性测试结果显示Mn掺杂催化剂比未掺杂催化剂表现更高的合成低碳醇的催化活性,尤其是C₂₊醇的选择性得到了明显的提高.醇产物分布偏离了ASF分布规律,甲醇的含量显著减少,乙醇成为主要醇产物.表征结果表明Mn助剂的加入增强了Co和Mo之间的相互作用,促进了醇生成活性中心Co-Mo-O物种的生成.显著减少了催化剂强酸性位的数量,促进了弱酸性位的产生,有利于醇产物的生成.助剂的加入有利于催化剂对CO的线性和桥式吸附,促进了醇产物的生成和碳链的增长,提高了催化剂对C₂₊醇的选择性.     

基于PSO算法的RoboCup2D机器人研究

对机器人体系结构、动作学习及行为的组织方式进行了研究,以演化计算为基本方法,以RoboCup2D为平台,设计了基于PSO算法的足球机器人的体系结构,解决感知、动作、和规划问题;在训练环境下,形成感知规则,优化感知相关参数,得到对信息高效快速的感知方法,并根据指定的粒度、功能、参数,对RoboCup2D机器人的原子动作进行了组合优化,得到一组带参数和执行效果描述的粒子动作;最后在赛场环境和任务驱动下,搜索粒子动作并进行组织规划,得到完成特定任务的机器人行为;RoboCup2D仿真实验表明,演化计算方法不仅能利用原子动作进行组合优化,得到适应于不同条件的粒子动作,而且能通过其在线搜索粒子动作,动态组成机器人行为;基于演化计算的足球机器人能更好地完成跑位、截球、带球、传球等任务,具有更强的适应性。     

北斗B1信号捕获跟踪算法的软件仿真研究

针对北斗B1频率的I支路信号,设计并实现了北斗软件接收机的基带处理部分。阐述了北斗B1频点信号的扩频体制和产生过程,并行码相位搜索捕获策略以及鉴相辅助跟踪环路,并设计了二阶数字环路滤波器,滤波器参数取ζ=0.707,B_n=25(Hz)。同时采用Matlab软件,仿真北斗中频数字信号,编码实现捕获跟踪算法,并分别通过对仿真信号和真实卫星信号的捕获跟踪,验证捕获跟踪算法的可行性,并提出锁频环辅助锁相环算法的改进思路。为进一步开展北斗软件接收机相关技术研究打下了基础。     

Enantiomeric separation of chiral pesticides by high performance liquid chromatography on cellulose tris-3,5-dimethyl carbamate stationary phase under reversed phase conditions

Twenty chiral pesticides were tested, of which seven samples were directly separated by HPLC using cellulose tris-3,5-dimethyl carbamate (CDMPC) chiral stationary phase under RP conditions. The influence of mobile phase composition and column temperatures from 0 degrees C to 40 degrees C on the separations were investigated. The mobile phases were methanol/water or ACN/water at a flow rate of 0.8 mL/min with UV detection at 230 or 210 nm. Epoxiconazole, terallethrin, benalaxyl, and diclofopmethyl were observed to obtain the baseline separation under suitable conditions and other pesticides pyriproxyfen, lactofen, and quizalofop-ethyl were separated partially. The retention factors (k) and selectivity factor (alpha) for the enantiomers of most investigated pesticides decreased upon increasing the temperature except for the selectivity factors (alpha) of pyriproxyfen in methanol/water. The ln alpha - 1/T plots for racemic chiral pesticides were linear at the range of 0-40 except for that of pyriproxyfen enantiomers in methanol/water and the chiral separations were controlled by enthalpy. Better separations were not always at low temperature. The elution orders of the eluting enantiomers were determined by a circular dichroism (CD) detector.     

Antibacterial thymol derivatives isolated from Centipeda minima

Two new monoterpenoids, 8,10-dihydroxy-9(2)-methylbutyryloxythymol (1) and 10-hydroxy-8,9-dioxyisopropylidene-thymol (2), together with five known thymol derivatives: 8,9,10-trihydroxythymol (3), thymol-beta-glucopyranoside (4), 9-hydroxythymol (5), 8,10-dihydroxy-9-isobutyryloxythymol (6), and 8-hydroxy-9,10-diisobutyryloxythymol (7), were isolated from Centipeda minima. Their structures were identified by means of spectroscopic analyses. Interestingly, compound 2 is not an extraction artifact according to a close HPLC examination of material after extraction by analytical MeOH at ambient temperature. The antibacterial activities of compounds 1-7 were evaluated against eight microbial strains by the agar dilution method.     

Intramolecular cycloaddition of azomethine ylides in the preparation of pyrrolidino[2',3':3,4]pyrrolidino[1,2- a]benzimidazoles

The parent pyrrolidino[2',3':3,4]pyrrolidino[1,2-a]benzimidazole heterocycle as well as a series of novel analogues have been synthesized utilizing a microwave-assisted intramolecular cycloaddition of azomethine ylides as the key transformation. A variety of diversity groups were added to explore the scope of this reaction and to provide a number of new compounds for biological screening.     

Optimisation of Hydrocortisone Production by Curvularia lunata

A new method for breeding the hydrocortisone overproducing strain Curvularia lunata by screening ketoconazole-resistance mutant was developed. A hydrocortisone overproducing mutant C. lunata KA-91 with ketoconazole-resistance marker was obtained from protoplasts treated with ultraviolet radiation. The hydrocortisone conversion rate of C. lunata KA-91 was increased by 42.1% compared to the original strain CL-114 at the substrate 17α-hydroxypregn-4-en-3, 20-dione-21-acetate addition concentration of 1.0 g/L. The by-products produced by KA-91 were fewer than those of the original strain. It was assumed that the higher cytochrome P450 content of ketoconazole-resistance mutant resulted in the increase of 11β-hydroxylation capacity. The culture conditions for biotransformation of 17α-hydroxypregn-4-en-3, 20-dione-21-acetate to hydrocortisone were optimized by response surface methodology. Plackett–Burman design was applied to elucidate the key factors affecting the hydrocortisone production, and the results indicated that glucose, initial pH, and glucose to total nitrogen sources ratio (ω) had significant effects on hydrocortisone production. Box–Behnken design was employed to search for the optimal parameters of those three key factors. According to the model, the trial checking at the optimal conditions showed a high hydrocortisone conversion rate of 82.67%.     

Tuning of redox properties of iron and iron oxides via encapsulation within carbon nanotubes

We report the tuning of the redox properties of iron and iron oxide nanoparticles by encapsulation within carbon nanotubes (CNTs) with varying inner diameters. Raman spectroscopy was employed to investigate the interaction of the encapsulated nanoparticles with the CNTs. A red shift of the Fe-O mode is observed in the nanoparticles deposited on the outer CNT surfaces with respect to bulk Fe2O3. However, this mode is found to be stepwise blue-shifted with decreasing inner diameter in the CNT-encapsulated Fe2O3 nanoparticles, suggesting an enhanced interaction of Fe2O3 with the inner CNT surface as its curvature increases. The autoreduction of the encapsulated Fe2O3 is significantly facilitated inside CNTs with respect to the outside nanoparticles. Interestingly, it becomes more facile with decreasing CNT channel diameter as evidenced by temperature programmed reaction, in situ XRD, and Raman spectroscopy. The oxidation of encapsulated metallic Fe nanoparticles on the other hand is retarded in comparison to that of the outside Fe particles as shown by in situ XRD and gravimetrical measurements with an online microbalance. We attribute this tunable redox behavior of transition metal nanoparticles inside CNTs to a particular electronic interaction of the encapsulates with the interior CNT surface, which stabilizes the metallic state of Fe.