兰州重离子加速器深层治癌束流线真空系统

重离子深层治癌束流线从兰州重离子加速器冷却储存环(HIRFL-CSR)主环引出,利用能量为100MeV/u～430MeV/ u的碳离子束,开展治疗体内各种癌症的深层治癌研究。该束流线真空系统包括极高真空段、超高真空段和大气段,采用不同的真空获得方案和工艺路线,分别在极高真空段和超高真空段获得了8×10~(-10)Pa和1×10~(-6)Pa的真空度,并顺利实现了束流线的真空过渡,保证了HIRFL-CSR主环极高真空系统的安全运行;研制了适用于高频率扫描磁铁内放置的真空管道,消除了涡流对束流的影响;对隔离真空和大气的大尺寸膜窗材料进行了调研,选择高强度塑料膜(Hostaphan)和加强纤维膜(Kevlar)联合使用,既能让束流通过,又不会产生危害人体的中子,并能够有足够的强度抵御大气压力。该束流线真空系统的建成为重离子深层治癌的研究提供了良好的真空条件。

金丝桃素体外抗高致病性猪生殖与呼吸综合征病毒活性的研究

为研究金丝桃素体外对高致病性猪生殖与呼吸综合征病毒(PRRSV)活性的影响,以Marc-145细胞培养增殖的PRRSV为研究对象,通过噻唑蓝(MTT)比色法和观察细胞病变效应(CPE),测定吸光度值(D490nm)和半数细胞感染量(TCID50),以细胞存活率、病毒抑制率和TCID50为指标,评价不同剂量的金丝桃素体外抑制PRRSV活性的效应,并通过改变加药方式(同时、感染前、感染后给药),探讨其抗PRRSV的作用机制。结果表明,在PRRSV感染的同时加入金丝桃素,其细胞存活率和对PRRSV的抑制率略有升高,与PRRSV对照组和拉米夫定对照组相比,均有显著性差异(P<0.01)。在PRRSV感染前和感染后加入金丝桃素,其细胞存活率和对PRRSV的抑制率明显升高,且随药物浓度的增加而上升,与PRRSV对照组相比,有显著性差异(P<0.01),与拉米夫定对照组相比无统计学意义(P>0.05)。金丝桃素可使PRRSV的TCID50从6.1下降至4.15。证实,金丝桃素具有多环节体外抗PRRSV效应;不同浓度的金丝桃素表现出不同的抗PRRSV活性,并呈现剂量依赖关系。

ECR离子源束流引出与传输的研究(英文)

针对ECR离子源的束流引出及传输研究,在中国科学院近代物理研究所的LECR3离子源实验平台上开展了大量的实验.实验中研究了等离子体电极引出孔径、反射电极(抑制电极)偏压以及Glaser透镜等因素对束流引出与传输的影响.研究的重点是试图通过系列实验与分析来研究如何能更有效地引出强流离子束流并减小其在传输空间的损失.给出了实验的主要结果,结合这些数据对ECR离子源的束流引出与传输进行了较全面的分析,并综合这些实验结果与分析结果得出了该物理过程的一般物理图像.

扇聚焦回旋加速器(SFC)真空室改造

介绍了兰州重离子加速器的注入器SFC真空室的基本情况,为满足新建的放射性束流线RIBLL和冷却储存环CSR对HIRFL加速重离子的需要,对SFC真空室进行了改造。新真空室采用二次真空技术,在加速器中心平面真空度达到了8×10-6Pa。

Magnetostratigraphic dating of mammalian fossils in Junggar Basin；northwest China

IEECAS SKLLQG

HIRFL-CSR complex

The construction and commissioning of HIRFL-CSR were finished in 2007. From 2000 to 2005 the subsystem and key devices of CSR were successfully fabricated, such as magnet, power supply, UHV system, e-cooler, electric-static deflector with the septum of 0.1 mm, and the fast-pulse kicker with the rise time of 150 ns. After that the CSR commissioning activities were performed in 2006 and 2007, including the accumulation of those heavy ions of C, Ar, Kr and Xe by the combination of stripping injection (STI) or multiple multi-turn injection (MMI) and e-cooling with a hollow e-beam, wide energy-range synchrotron ramping by changing the RF harmonic-number at mid-energy, the beam stacking in the experimental ring CSRe, the RIBs mass-measurement with the isochronous-mode in CSRe by using the time-of-flight method, and the ion beam slow-extraction from CSRm.

Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL (invited)

There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e mu A of O7+, 505 e mu A of Xe20+ 306 e mu A of Xe27+, and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

New parameters of many-body potentials: studying the thermal and mechanical properties of noble metals

New parameters of nearest-neighbor EAM (1N-EAM), n-th neighbor EAM (NN-EAM), and the second-moment approximation to the tight-binding (TB-SMA) potentials are obtained by fitting experimental data at different temperatures. In comparison with the available many-body potentials, our results suggest that the 1N-EAM potential with the new parameters is the best description of atomic interactions in studying the thermal expansion of noble metals. For mechanical properties, it is suggested that the elastic constants should be calculated in the experimental zero-stress states for all three potentials. Furthermore, for NNEAM and TB-SMA potentials, the calculated results approach the experimental data as the range of the atomic interaction increases from the first-neighbor to the sixth-neighbor distance.

新一代多电荷态离子源的研究

离子源发展存在两大热点问题：其一强流高电荷态离子的产生；其二强流金 属离子的产生。为了获得强流高电荷态离子，我们设计制造了全超导 ECR 离子 源 SECRAL（Superconducting ECR ion source with Advanced design in Lanzhou） ， 该离子源采用了全新的超导磁体结构形式，工作于 18～28GHz 的微波频率。根据 scaling laws 和实验经验，我们确定了 SECRAL 离子源所需要的约束磁场场形， 并针对新的磁体结构设想，通过 TOSCA 程序进行了详细的计算，成功地设计出 满足我们场形要求的超导磁体物理模型。据此，我们进一步进行了超导磁体的力 学结构分析，为磁体机械工艺设计提供了参考依据，保证了超导磁体结构设计的 可靠性。源体建成后，经过一系列的测试和调束实验，不但验证了我们的设计和 分析是合理的、可靠的，而且创造了许多项束流调试的新世界纪录，我们分别获 得了 810 A eμ O7+ 、730 A eμ Ar 11+ 、220 A eμ Ar 14+ 、73 A eμ Ar 16+ 、483 A eμ Xe 20+ 等束 流。为了获得强流中低电荷态金属离子束，我们尝试探索一种原理、结构、工作 模式全新的离子源－外部电子注入PIG离子源（E-PIG） 。目前，我们基本按照我 们的初期设想设计建造了 E-PIG离子源，设计中采用了外部电子枪注入电子、空 心阴极、特殊的场形等手段来提高金属离子的电荷态和流强。经过初步的起弧调 试，我们发现在初期的设计中还存在一些问题亟待进一步整改。

Dynamics of excited m-dichlorobenzene

Dynamics of excited m-dichlorobenzene is investigated in real time by femtosecond pump-probe method, combined with time-of-flight mass spectrometric detection in a supersonic molecular beam. The yields of the parent ion and daughter ion C6H4CI+ are examined as a function of the delay between the 270 and 810 nm femtosecond laser pulses, respectively. The lifetime of the first singlet excited state S-1 of m-dichlorobenzene is measured. The origin of this daughter ion C6H4CI+ is discussed. The ladder mechanism is proposed to form the fragment ion. In addition, our experimental results exhibit a rapid damped sinusoidal oscillation over intermediate time delays, which is due to quantum beat effects.

大豆植株及大豆植株-土壤系统N_2O释放规律及其与光合作用的关系

为区分植物在土壤-植物系统N2O排放中的贡献,用封闭式箱法对田间栽培的大豆植株及土壤、大豆植株-土壤系统的N2O排放进行了测定,同时对影响N2O的排放的因素进行了分析。观测结果表明:田间栽培的大豆的N2O排放通量昼间变化模式是10∶30有一个排放高峰,153∶0有一个排放低谷,甚至表现为可吸收大气中的N2O;在生育期内,大豆植株有两个释放高峰,分别位于6月下旬和8月中旬。从6月下旬至8月末,大豆对土壤-植物系统N2O排放的贡献率约为25%～57%。大豆植株、大豆植株-土壤系统N2O排放通量与温度有一定的相关性,相关系数r2分别为0.4954和0.5357,大豆N2O的排放通量同光合速率有一定的相关性(r2=0.5944)。

高山林线形成机理及植物相关生理生态学特性研究进展

高山林线作为极端环境条件下树木生存的界限,由于其对气候变化的敏感性,在全球变化研究中得到了广泛关注。研究高山林线形成机理以及林线地带植物相关生理生态学特性成为预测未来气候变化条件下植被动态变化的出发点。对于高山林线形成机理研究主要关注两方面问题:(1)林线地带外界环境如何限制乔木生长和分布,其内在机理如何;(2)灌木及草本相对于乔木在林线地区有哪些生存优势,从乔木到灌木及草本生活型演变的功能及意义如何。综述了当前高山林线形成机理及相关生理生态特性的国内外最新研究成果,指出尽管温度(尤其是生长季低温)在全球尺度上能解释大部分高山区域林线的分布,但树木生长和生存受限的内在机理并没有弄清楚,目前主要存在"碳受限"以及"生长受限"假说两大争论焦点。另外,理论上受温度控制的高山林线对气候变化的响应表现出不同的模式,表明全球变化对林线分布和植被生长影响的复杂性和不确定性。因此,未来的研究应该关注影响林线地区植被生长的多种生理生态学过程,比如水分及养分利用过程,以及从乔木到灌木及草本生活型演变的功能意义,从而为林线形成机理以及对气候变化的响应提供更好的解释。

黑土区春小麦群体物质和能量积累研究

利用大田和实验室测定的方法,测定黑土区春小麦群体根、茎、叶、穗等物质和能量在整个生育期的积累过程,旨在为黑土区农业生态系统研究提供实测依据。结果表明,在整个生育期中,春小麦不同器官鲜物质积累的最大值出现的时期各异;除叶和20 cm以下根外,其它器官干物质累积均随生长发育而增加;各器官含水量差异较大,但都随生长而降低;每个器官能量的累积总量并不都是随生长发育而持续增长,且器官间单位干物质所含能量差异较大,变化范围为0.9×10~4 J·g~(-1)(根,孕穗期)至1.5×10~4 J·g~(-1)(叶,三叶期),根、秸秆、籽粒积累的能量分别为6.8×10~5、78.9×10~5和87.9×10~5 J·m~(-2),分别占总积累能量的3.9％、45.4％、50.7％。同实测法相比,计算法获得的秸秆能值高出31％。因此,测定法较计算法能更精确地反映能量在生态系统中的流动。