木薯良种南植188及其组培快繁研究

中国科学院华南植物研究所从1981年开始，先后从哥伦比亚国际热带作物研究中心引进去病毒的试管苗木薯品种25个，经应用生物工程技术进行试管苗微型繁殖和试管苗移栽成功，移栽成活率达95%以上。通过比较筛选试验，又从25个试管苗品种中选出了“南植188”木薯新品种，经连续试验证实，该新品种具有抗性强、叶色浓绿、植株高大、枝叶繁茂、结薯早、薯块大、纤维少、产量高等特点。在同等栽培和管理条件下，其单位面积产量比现植的面包木薯、竹叶薯等品种高60～150%，属于高产、优质、低毒的甜种类型。列入“星火计划”，在广州市和省内有关县进行南植188良种木薯苗的生产。

~(188)Tl的πh_(9／2)vi_(13／2)扁椭球转动带的旋称反转研究

利用能量为170MeV的35Cl束流,通过157Gd(35Cl,4n)熔合蒸发反应研究了188Tl的高自旋态能级结构．依据实验结果建立了188Tl基于πh9／2(?)vi13／2组态的转动带．根据双奇Tl核能级结构的相似性,指定了188Tlπh9／2(?)vi13／2扁椭球转动带的自旋值．结果表明在188Tl中,πh9／2(?)vi13／2扁椭球转动带在低自旋区具有旋称反转性质．利用包含了质子-中子剩余相互作用的准粒子-转子模型,定性地解释了πh9／2(?)vi13／2扁椭球转动带的低自旋区旋称反转现象．

双奇核~(188)Au的准粒子带结构研究

利用在束γ谱学实验技术,通过173Yb(19F,4nγ)反应布居了188Au的高自旋态,并对其准粒子带结构进行了研究．基于实验测量结果,对原有的双奇核188Au能级纲图做了较大的修改．通过系统性比较,对15+以上的能级结构进行了讨论．

Prolate and oblate shape coexistence in Pt-188

A standard in-beam gamma-spectroscopy experiment for Pt-188 is performed via the Yb-176(O-18, 6n) reaction at beam energies of 88 and 95 MeV, and the level scheme for (188) Pt is established. Prolate and oblate shape coexistence has been demonstrated to occur in Pt-188 by applying the projected shell model. The rotation alignment of i(13/2) neutrons drives the yrast sequence changing suddenly from prolate to oblate shape at angular momentum 10th, indicating likely a new type of shape phase transition along the yrast line in Pt-188.

Observation of a pi h(9/2) circle times nu i(13/2) oblate band in Tl-188

Excited states in Tl-188 have been studied experimentally using the Gd-157(Cl-35;4n) reaction at a beam energy of 170 MeV. A rotational band built on the pi h(9/2) x nu i(13/2) configuration with oblate deformation has been established for Tl-188. Based on the structure systematics of the oblate pi h(9/2) x nu i(13/2) bands in the heavier odd-odd Tl nuclei, we have tentatively proposed spin values for the new band in Tl-188. The pi h(9/2) x nu i(13/2) oblate band in Tl-188 shows low-spin signature inversion, and it can be interpreted qualitatively by the two-quasiparticle plus rotor model including a J-dependent p-n residual interaction.

Properties of the pi h(9/2)circle times nu i(13/2) oblate band in Tl-188

High spin states in Tl-188 have been investigated via the Gd-157(Cl-35,4n) reaction at beam energy of 170 MeV. A rotational band built on the pi h(9/2) circle times nu(13/2) configuration with oblate deformation has been established. Considering the similarity between the band structure observed in odd-odd Tl nuclei, spin values have been tentatively proposed for the new band in Tl-188. The pi h(9/2) circle times nu(13/2) oblate band in Tl-188 shows low-spin signature inversion, and it can be interpreted qualitatively by the two quasiparticle plus rotor model including a J-dependent p-n residual interaction.

Signature inversion in pi h(9/2) circle times nu i(13/2) oblate band of Tl-188

High-spin Level structure of Tl-188 has been studied via Gd-157 (Cl-35,4n) fusion-evaporation reaction at beam energy of 170MeV. A rotational band built on the pi h(9/2) circle times nu i(13/2) configuration with oblate deformation has been established. Spin values have been proposed to the pi h(9/2) circle times nu i(13/2) oblate band based on the similarities between the oblate band of Tl-188 and those in odd-odd Tl190-200. With the spin assignments, the low-spin signature inversion has been revealed for the pi h(9/2) circle times nu i(13/2) oblate band of Tl-188. The low-spin signature inversion can be interpreted qualitatively in the framework of the quasi-particles plus rotor model including a J dependent p-n residual interaction.

Study of quasiparticles bands in odd-odd Au-188

High-spin level structure of Au-188 has been studied via the Yb-173(F-19, 4n gamma) reaction using techniques of in-beam gamma-ray spectroscopy. Based on the experimental results, the level scheme of 188Au has been revised significantly. The previously reported positive parity levels have been modified and a new 20(+) level was proposed to feed the 18(+) states via two low-energy transitions. The existence of the 20(+) and the level structures above it are similar to those in the neighboring odd-odd Au-190,Au-192, therefore, the pi h(11/12)(-1)circle times-vi(13/2)(-2)h(9/2)(-1) configuration was assigned to the 20(+) state.

High-spin states in Au-188: Further evidence for nonaxial shape

The high-spin level structure of Au-188 has been investigated via the Yb-173(F-19,4n gamma) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new I-pi = 20(+) state associated with pi h(11/2)(-1) circle times nu i(13/2)(-2)h(9/2)(-1) configuration and two new rotational bands, one of which is built on the pi h(9/2) circle times nu i(13/2) configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around Au-188 for the pi h(9/2) circle times nu i(13/2) bands in odd-odd Au isotopes. Evidence for pi h(11/2)(-1) circle times nu i(13/2)(-1) structure of nonaxial shape with gamma < -70 degrees has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.

Piezoelectricity Of Zno Films Prepared By Sol-Gel Method

ZnO piezoelectric thin films were prepared on crystal substrate Si(111) by sol-gel technology, then characterized by scanning electron microscopy, X-ray diffraction and atomic force microscopy (AFM). The ZnO films characterized by X-ray diffraction are highly oriented in (002) direction with the growing of the film thickness. The morphologies, roughness and grain size of ZnO film investigated by AFM show that roughness and grain size of ZnO piezoelectric films decrease with the increase of the film thickness. The roughness dimension is 2.188-0.914 nm. The piezoelectric coefficient d(33) was investigated with a piezo-response force microscope (PFM). The results show that the piezoelectric coefficient increases with the increase of thickness and (002) orientation. When the force reference is close to surface roughness of the films, the piezoelectric coefficient measured is inaccurate and fluctuates in a large range, but when the force reference is big, the piezoelectric coefficient d(33) changes little and ultimately keeps constant at a low frequency.

Direct Numerical Simulation Of Three-Dimensional Richtmyer-Meshkov Instability

Direct numerical simulation (DNS) is used to study flow characteristics after interaction of a planar shock with a spherical media interface in each side of which the density is different. This interfacial instability is known as the Richtmyer-Meshkov (R-M) instability. The compressible Navier-Stoke equations are discretized with group velocity control (GVC) modified fourth order accurate compact difference scheme. Three-dimensional numerical simulations are performed for R-M instability installed passing a shock through a spherical interface. Based on numerical results the characteristics of 3D R-M instability are analysed. The evaluation for distortion of the interface, the deformation of the incident shock wave and effects of refraction, reflection and diffraction are presented. The effects of the interfacial instability on produced vorticity and mixing is discussed.

受限射流的数值模拟

对柱形燃烧室内的轴对称等温射流流场进行了数值模拟。回流是这类流场的普遍特征。它对于燃烧室火焰的稳定起着重要作用。本文研究了影响回流特征的多种因素。以压力-速度为主要变量,采用K-ε二方程湍流模型进行计算。计算方法的特征之一是膨胀流动的阶梯形边界表示法。结果包括回流区特征及预示的平均流线分布图。计算结果与实验资料相当吻合。这说明了此方法可用于燃烧室性能的分析。

应用于金属材料表面改性的离子注入技术

<正> 一、金属材料表面改性的经济意义和离子注入技术 巨大的经济意义始终是开展材料研究,提高金属材料表面抗磨、抗疲劳、耐腐蚀等性能的主要推动力。如在摩擦、磨损方面,1964年英国教育科研国务大臣邀请全国著名摩擦、润滑工程专家对全国进行了普查,并于1966年发表报告指出,英国如能运用摩擦学知识,每年可节约5.15亿英镑,美国国会在1975年度报告中也指出:由于摩擦、磨损造成的经济损失据估计约值1000亿美元,其中200亿是材料费,其它如零件表面的疲劳,腐蚀也是材料