Thrust generation and wake structure of wiggling hydrofoil

Marine animals and micro-machines often use wiggling motion to generate thrust. The wiggling motion can be modeled by a progressive wave where its wavelength describes the flexibility of wiggling animals. In the present study, an immersed boundary method is used to simulate the flows around the wiggling hydrofoil NACA 65-010 at low Reynolds numbers. One can find from the numerical simulations that the thrust generation is largely determined by the wavelength. The thrust coefficients decrease with the increasing wavelength while the propulsive efficiency reaches a maximum at a certain wavelength due to the viscous effects. The thrust generation is associated with two different flow patterns in the wake: the well-known reversed Karman vortex streets and the vortex dipoles. Both are jet-type flows where the thrust coefficients associated with the reversed Karman vortex streets are larger than the ones associated with the vortex diploes.

凹腔非定常特性的数值模拟

采用基于Menter SST两方程湍流模型的DES方法, 数值模拟开式凹腔在跨声速条件下的非定常流动特性.计算凹腔底部和后壁面上的点的声压级频谱以及总声压级, 证明在第二噪声模态上的声压级最大

MHD控制超声速边界层的理论研究和数值分析

对MHD(mechanisms of magnetohy drodynamics)控制超声速平板湍流边界层的机理进行了理论研究和数值模拟.理论上,采用等离子体低频近似碰撞频率模型,建立等离子体中电子和离子的力平衡方程,得到等离子体速度、极化电场以及边界层速度.数值上,通过空间HLLE格式、LU-SGS时间推进求解时均磁流体动力学湍流方程,其中湍流模型采用sst-kω双方程模型.研究结果表明:(1)边界层速度的理论结果和数值结果误差在7%范围内;(2)只有磁场而电场为零时,洛仑兹力起到减小摩阻的作用.施加电场后,洛仑兹力能够加速边界层低速区流体;(3)在边界层外层,越靠近壁面,作用参数越小;而在边界层近壁区黏性底层,虽然惯性力减小,但黏性力却迅速增加,因此越靠近壁面,作用参数反而越大,加速低速流的代价增加.

超临界态煤油等熵流动和超声速喷注研究

本文采用10组分替代模型和等熵假设数值分析了超临界态煤油的超声速流动特性，给出了煤油超声速流动的等熵线分布、马赫数与喷管面积关系、温度/压力随马赫数的变化等一系列结果。同时进行了相应的加热煤油的喷管流动实验，验证了数值分析的可靠性，并获得了超临界态煤油产生稳定的超声速流动的大致工作区间。本文还采用雷诺平均方法结合SST 湍流模型数值模拟了二维超声速气流（总温1500K，马赫数2.5）中超临界态煤油的超声速/声速喷射和混合过程，以及射流出口马赫数对提高穿透深度的作用。研究发现在相同的煤油流量条件下，煤油超声速射流比声速射流将产生更强的马赫桶结构，同时射流的穿透深度也有一定提高。

采用简化机理模拟乙烯在超声速气流中自点火燃烧过程

本文采用由CARM生成的11组分/7步反应简化机理对二维超声速气流中热乙烯横向喷射、自点火燃烧过程进行了非定常模拟。同时，计算采用了SST 湍流模型、涡耗散概念(EDC)燃烧模型以及ISAT积分算法等技术。数值研究了马赫数2.5、总温1800K来流中，不同当量比条件下乙烯的自点火燃烧过程。研究发现：乙烯首先在凹腔内着火；在当量比较低时，燃烧主要发生在凹腔下游，并且燃烧区域为超声速；随着当量比的提高，由于释热量的增加，使得燃烧室内气流发生热雍塞，乙烯在亚声速气流中燃烧，燃烧效率显著提高，燃烧主要发生在凹腔区。另外，采用总包反应模型计算的结果表明由于模型过于简单，使得燃烧效率偏高、总温偏大，与简化机理给出的结果差别显著。

何首乌炮制前后生物活性和化学成分的变化研究

何首乌为常用中药，由何首乌及含何首乌的中成药制剂所引起的不良反应也时见报道，科学阐明不良反应的物质基础并提出解决方案对何首乌的使用十分重要。本论文研究了何首乌炮制前后KM小鼠肝脏毒性基因表达谱、生物活性及化学成分的变化。所获结果支持何首乌炮制的目的是减毒、改性（改变药效），何首乌生、熟异治的观点。制首乌对抑郁症的效果显著优于生首乌，这与本草所记载的何首乌炮制后补肝肾、益精血，归肝、肾经一致。 主要结果如下： 1、 生、制首乌的毒理基因芯片研究结果 何首乌的不良反应主要表现在肝损害方面。本研究建立了生何首乌和制何首乌不同剂量的肝毒性作用模型，体重指标统计发现生何首乌各剂量组平均体重显著下降，中剂量组（10 g/kg.d）体重下降20 %，高剂量组（20 g/kg.d）体重下降42%，50%动物死亡，提示动物机体能量代谢障碍；基因芯片研究结果表明何首乌是CYP450的抑制剂，生何首乌相对于制何首乌CYP3A4、CYP4A5显著下调，导致毒性成分在体内的吸收增加，服用大剂量的生何首乌后产生明显的肝毒性；主要对以下六条Pathway产生影响：①PPAR signaling pathway，主要毒性靶基因有RXRB CYP7a1、Acadl、Apoa2、Cyp4a、 FABP2 、MAPKKK5等基因。②Calcium signaling pathway，主要毒性靶基因有CAMK2B、CACNA1F、S100A1、 F2R、Ryr1、Slc8a2、Camk4 ③Neuroactive ligand-receptor interaction，主要毒性靶基因有Chrm4、 Ntsr2 、 GABRR1、 GRIK3、F2R等基因。④Wnt signaling pathway，主要毒性靶基因有Daam2、Rac1 等基因。⑤Complement and coagulation cascades，主要毒性靶基因有F2R、Serpina1b、Cfi 、FGA等基因。⑥Oxidative hosphorylation，主要毒性靶基因有Atp5e、NDUFA1等基因。生何首乌毒性明显强于制首乌，且生何首乌水煎液的毒性大于生何乌首丙酮提取物的毒性，这一结果表明，何首乌主要的毒性成分很可能并不仅仅是传统所认为的以大黄素为代表的蒽醌类化合物，而是何首乌中大量存在的有效组分二苯乙烯苷与大黄素相互作用的结果，这一研究结果与前述的何首乌对肝药酶的影响是一致的。后续生、制首乌的化学成分差异研究表明，炮制后二苯乙烯苷含量明显降低：生首乌为5.512 %、清蒸制首乌为3.811 %、豆制首乌为3.538 %,大黄素的含量炮制后显著升高,生首乌为0.094 %、清蒸制首乌为0.119 %、豆制首乌为0.126 %。 2 生、制首乌药效差异研究结果 本文采用慢性中等强度不可预知应激刺激模型(chronic unpredictable mild stress, CUMS)和动物行为绝望实验法，研究生、制首乌抗抑郁活性的差异，制首乌（5 g/kg.d）与模型组相比有显著差异（P< 0.01），生首乌制首乌（5g/kg.d）与模型组相比无显著差异，这一结果表明制首乌抗抑郁活性显著优于生首乌。 本文比较了生、制首乌对四氧嘧啶糖尿病模型小鼠血糖的影响的差异，生首乌（5 g/kg.d）与模型组相比有显著差异（P< 0.01），制首乌（5 g/kg.d）与模型组相比无显著差异，这一结果表明生首乌降糖活性优于制首乌。这一结果与历代中医古书中生首乌治疗消渴症（糖尿病）的记载一致。 3生、制首乌化学成分差异的研究结果 本文选用HPLC-DAD指纹图谱技术结合药效成分含量测定来研究生、制首乌化学成分的差异。炮制后，何首乌中的主要化学成分并未消失，只是其含量发生了改变。炮制后二苯乙烯苷含量明显降低：生首乌为5.512 %、清蒸制首乌为3.811 %、豆制首乌为3.538 %,大黄素的含量炮制后显著升高,生首乌为0.094 %、清蒸制首乌为0.119 %、豆制首乌为0.126 %。 综上所述，炮制前后何首乌中二苯乙烯苷和大黄素含量比的变化可能是何首乌炮制减毒、改性的物质基础。 根据上述结果我们建立了生、制首乌的质量控制新模式。 In recent years, some adverse drug reactions (ADR) about some traditional Chinese medicine were reported at times. As a Chinese medicine most in use, the ADRs of Radix Polygoni multiflori (RPM) and the medicines containing the RPM were also mentioned. The resolution of the problems caused by the ADRs is very important for the use of the RPM as a medicine. The process (or preparation) is a significant feature for the clinical use of the Chinese medicine and an important technology for the safe use and good effect of the Chinese medicine. By processing, the toxicity of the Chinese medicine can be reduced, its properties can be changed and curative effect can be enhanced at the same time. The changes of the gene expression profiles for KM mice hepatotoxic effects, and the change of the biological activity and the chemical composition after being processed of the RPm were studied in the present dissertation. The RPm heatotoxicity mechanism and the toxicity target genes were explained on the gene level for the first time. With the antidepressant activity, and the hypoglycemic effect as the target, the differences on the pharmacodynamics between the processed RPm and unprocessed RPm, for the first time, were investigated. The results obtained show that the antidepressant activity of the processed RPM is far higher than the ones of unprocessed RPm. As we know, the results were reported for the first time. The quality control systems (QCS) for the processed and the unprocessed RPm were founded. The HPLC-DAD was used in the systems founded on the basis of the toxicology and the pharmacodynamics experiments. As we know, the OCSs were reported for the first time. The above-mentioned experimental results confirm that the unique process theory of the traditional Chinese medicine (TCM) used for the process of the Radix Polygoni multiflori (RPm) is correct, i.e after being processed the toxicity of the RPm decreases and its Pharmacodynamic effects change. It is known to author that there have been no similar reports in the literatures up to now. The main experimental results are summarized as follows: 1 The results on the mice toxicology gene chip for the unprocessed and processed RPm The KM mice hepatotoxic model caused by the RPm at the different dosages was established in the present study. The results obtained show that the mouse average body weight obviously decreased in the groups at the different dosages of the unprocessed RPm: the 10 g/kg.d .group decreased 20%; 20 g/kg.d. group decreased 42%, and 50% mice died at 20 g/kg.d. group. The main experimental results on the mice toxicology gene chip The RPm is the CYP450 inhibitor. As compared with the processd RPm, the CYP3A4, CYP4A5 of the unprocessed RPm demonstrate the marked downregulation, which leads to the increase of the poison absorbtion into the body with the result that the unprocessed RPm yields the marked hepatotoxication. The hepatotoxication was produced because the following 6 pathways were affected: ①PPAR signaling pathway, the chief toxicity target genes are RXRB, CYP7a1, Acadl, Apoa2, Cyp4a, FABP2 and MAPKKK5 etc. ②Calcium signaling pathway, the chief toxicity target genes are CAMK2B, CACNA1F, S100A1, F2R, Ryr1,Slc8a2 and Camk4 etc. ③Neuroactive ligand-receptor interaction, the chief toxicity target genes are Chrm4, Ntsr2, GABRR1, GRIK3 and F2R etc. ④Wnt signaling pathway, the chief toxicity target genes are Daam2, Rac1 etc. ⑤Complement and coagulation cascades, the chief toxicity target genes are F2R, Serpina1b, Cfi and FGA etc. ⑥Oxidative phosphorylation, the chief toxicity target genes are Atp5e, NDUFA1 etc. The above experimental results, for the first time , demonstrate on the gene level that the unprocessed Rpm toxicity is far stronger than the processed RPm one, and the toxicity of the water decoction of the unprocessed RPm is greater than the one of its acetone extracts, which shows that the chief toxicity components of the RPm are probably not only the anthraquinones, for example, the emodin, but the complex compounds produced by the interaction between the emondin and the stilbene glucoside which is the largest component of the unprocessed RPm. The result is accordance with the above effect of the RPm on the hepatic drugenzyme. Aftter being processed, in fact, the content of the stibene glucoside in the RPm markedly decreases. 2. The results on the pharmacodynamic differences between the unprocessed and processed RPm The results obtained show that the effects of processing on RPm pharmacodynamic behaviour received in the Chinese Material Medica are correct. It is known to author that this is the first experimental result in the research materials now available. The chief results are as follows: For the treatment of the antidepressant, the curative effect of the processed RPm is far better than the one of the unprocessed RPm. By contrast with the above results, the hypoblycemic effect of the unprocessed RPm is better than the one of the processed RPm. 3. The results on the Chemical Composition The results obtained by using HPLC-DAD fingerprint and by the determination of effective component content show that the main chemical components in the RPm after being processed do not disappear, but their contents change. The contents of the stilbene glucoside (SG) and emodin in the different samples were determined as follows: SG contents 5.512 % for the unprocessed RPm 3.811 % for the processed RPm (Steamed) 3.588 % for the processed RPm (black soybean) Emodin contents 0.094 % for the unprocessed RPm 0.119 % for the processed RPm (Steamed) 0.126 % for the processed RPm (black soybean) The combination of above experimental results on the toxicity, the pharmacodynamics and the chemical composition indicates that the changes of the content ratio of SG/emodin may be the substance base of the toxicity decrease and pharmacodynamic changes of the RPM by the processing.

超重元素的化学性质

对当前国际上超重元素化学性质实验研究的现状进行了综述,简单介绍了超重元素的合成方法和开展超重元素化学实验的技术路线。综述了超重元素Rf,Db,Sg的液相化学性质研究及Rf,Db,Sg,Bh,Hs和112号元素的气相化学性质研究的实验进展情况。最后介绍了我国在超重新核素合成方面所取得的成果,并展望了在超重元素化学性质研究方面的前景。

Liquid-liquid extraction of Pa-233(V) with Aliquat 336

The extraction of protactinium with Aliquat 336 (methyl-tri-caprylyl ammonium chloride) in toluene, cyclohexane and chloroform from HCl, HNO3, H2SO4, HClO4, HF and mixed HCl-HF media was investigated by radioactive tracer technique. Distribution ratios of protactinium between the aqueous solution and the organic phase were determined as a function of shaking time, concentrations of acid in aqueous solution phase, extractant concentration and type of diluents in the organic phase. Aliquat 336 can almost quantitatively extract protactinium from strong HCl solution. At the same time, small amounts of HF in HCl solutions have a strong effect on Pa distribution.

Solvent extraction study of protactinium(V) with methyl-iso-butyl carbinol and methyl-iso-butyl ketone

In order to study the extraction pattern of protactinium in different types of extracting agents and compare the similarity of patterns of extraction with dubnium and thereby unraveling its chemistry, solvent extraction of protactinium(V) with methyl-iso-butyl carbinol (MIBC) and methyl-iso-butyl ketone (MIBK) was studied using Pa-233 as a radiotracer. The extraction efficiencies of Pa were determined as a function of shaking time, concentrations of mineral acids, and extractant concentrations using the two extractants. The results show that MIBK is more suitable for the extraction of protactinium than MIBC in benzene. Furthermore, the effect of the F anion is also discussed.

beta-delayed fission of Ac-228

The basic process of an exotic decay mode namely P-delayed fission is simply introduced. The progress status of the study in the world is essentialized. The observation of P-delayed fission of Ac-228 is reported. The radium was radiochemically separated from natural thorium. Thin Ra sources in which Ac-228 was got through Ra-228 ->(beta-) Ac-228 were prepared for observing fission fragments from beta-delayed fission Ac-228. They exposed to the mica fission track detectors, and measured by an HPGe gamma-ray detector. The beta-delayed fission events of Ac-228 were observed and its beta-delayed fission probability was found to be (5 +/- 2) x 10(-12).

Production cross-section of Ra-230 in the reaction of 60 MeV/u O-18 ions with U-238

A thick natural uranium target was bombarded with a 60 MeV/u O-18 beam. The neutron-rich isotope Ra-230 as the target residue was produced through the multinucleon transfer reaction (U-238-4p-4n). The barium and radium fraction as BaCl2 precipitate were radiochemically separated first from the mixture of uranium and reaction products. Then, the radium fraction was separated from BaCl2 precipitate by using cation exchange technique. The gamma-ray spectra of the Ra fraction were measured using an HPGe detector. The production cross sections of Ra-230 were obtained by a combination of the radiochemical separation technique and off-line gamma-ray spectroscopy. The cross section of Ra-230 has been determined to be 66 +/- 20 mu b.

Angular dispersion and deflection function for heavy ion elastic scattering

The differential cross sections for elastic scattering products of F-17 on Pb-208 have been measured. The angular dispersion plots of ln(d sigma/d theta) versus theta(2) are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nuclear rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.

Production cross section of Th-236 in the interaction of U-238 with 60 MeV/u O-18 ions

The neutron-rich target-like isotope Th-236 has been produced in the U-238-2p multinucleon transfer reaction between a 60 MeV/u O-18 beam and natural U-238 targets. The activities of thorium were determined after radiochemical separation of Th from the mixture of uranium and reaction products. The Th-236 isotope was identified by the characteristic gamma-rays of 642.2, 687.6 and 229.6 keV. The production cross section of Th-236 was determined to be 250 +/- 50 mu b.