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Effects of carbon ions irradiation on apoptosis and Bax/Bcl-2 expression of squamous cell in carcinoma of tongue
No full textIn order to investigate the effect of carbon ion irradiation on apoptosis and Bax/Bcl-2 expression inhuman tongue carcinoma cells, exponentially growing human tongue carcinoma cells (Tb) cultured in vitro were irradiated with 0, 0.5, 1.0, 2.0 or 4.0 Gy of 12C6+ ions respectively. Survival rate of irradiated cells at various doses were measured by MTT assay. The nucleus changes of apoptosis and necrosis of cells stained by Hochest/PI were observed through fluorescence microscope. The cell cycle changes were detected by flow cytometry (FCM). The expressions of Bax and Bcl-2 were detected by Western blot analysis. The results show that the viability of Tb cells decreases gradually with increment of irradiation doses of carbon ions. The proportions of apoptosis cells in the irradiated groups are significantly higher than those in the control group. There is a positive correlation between irradiation doses and retardation strength in G2 /M phase at 24 h after irradiation (P<0.05). And the expressions of Bax and bcl-2 are significantly up-regulated and down-regulated respectively by 12C6+ ion irradiation. It can be concluded from above that cell apoptosis induced by heavy ion with high-LET may be mediated through the Bax/Bcl-2 expression pathway. 探讨重离子辐照对人舌鳞癌Tb细胞的凋亡及Bax/Bcl-2蛋白表达的影响。采用0、0.5、1.0、2.0、4.0 Gy重离子束辐照人舌鳞癌 Tb 细胞，应用 MTT 法检测细胞存活，流式细胞技术检测细胞周期变化，Hoechst33258/PI 复染法观察 Tb 细胞凋亡形态，并采用 Western-blot 法检测 Bax/Bcl-2 蛋白表达情况。结果发现，Tb细胞经12C6+离子束辐照后存活率显著下降，呈剂量依赖性的生长抑制；Tb细胞呈现蓝色荧光浓集成团的凋亡形态，且凋亡比例随辐照剂量增加；G2/M 期细胞百分数随照射剂量增加而增加（P＜0.05） 。Western-blot结果显示 Bax 蛋白表达水平随辐照剂量逐渐上升，但在 4 Gy 组其表达不再增高，Bcl-2 蛋白在 1.0、2.0、4.0 Gy组随剂量增大呈下降趋势。以上结果提示重离子束辐照对 Tb 细胞有抑制作用，Bax/Bcl-2 蛋白表达是重离子治癌的机制之一
Collective Transverse Flow in Intermediate Energy Heavy-Ion Collisions
No full textWithin the hadronic transport model IBUU04, we study the density-dependent symmetry energy by using the neutron-proton differential flow from the Sn-132+Sn-124 reactions at beam energies of 200, 400, 600 and 800MeV per nucleon. The strong effect of the symmetry energy is shown at the incident beam energy of 400 MeV/A. The small medium-effect of the neutron-proton differential flow is also found. We also study the neutron-proton differential flows with impact parameters of 3, 5, 7 fm. It is found that in semi-central collisions the sensitivity of the neutron-proton differential flow to the symmetry energy is larger.National Natural Science Foundation of China 10575046
10775062
China Postdoctoral Science Foundation 533149211
Low-lying states of heavy nuclei within the nucleon pair approximation
No full textIn this article we perform systematic calculations on low-lying states of 33 nuclei with A=202-212, using the nucleon pair approximation of the shell model. We use a phenomenological shell-model Hamiltonian that includes single-particle energies, monopole and quadrupole pairing interactions, and quadrupole-quadrupole interactions. The building blocks of our model space include one J=4 valence neutron pair, and one J=4,6,8 valence proton pair, in addition to the usual S and D pairs. We calculate binding energies, excitation energies, electric quadrupole and magnetic dipole moments of low-lying states, and E2 transition rates between low-lying states. Our calculated results are reasonably consistent with available experimental data. The calculated quadrupole moments and magnetic moments, many of which have not yet been measured for these nuclei, are useful for future experimental measurements.National Natural Science Foundation of China 10575070
10675081
Research Foundation for Doctoral Program of Higher Education in China 20060248050
Scientific Research Foundation of Ministry of Education in China for Returned Scholars NCET-07-0557
Chinese Major State Basic Research Developing Program 2007CB81500
Systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses
No full textA systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses can help single out effects of the nuclear mean field on pion production. Based on simulations using the IBUU04 transport model, it is found that the pi(-)/pi(+) ratio in head-on collisions of Ca-48 + Ca-48, Sn-124 + Sn-124, and Au-197 + Au-197 at beam energies from 0.25 to 0.6 GeV/nucleon increases with increasing the system size or decreasing the beam energies. A comprehensive analysis of the dynamical isospin fractionation and the pi(-)/pi(+) ratio as well as their time evolution and spatial distributions demonstrates clearly that the pi(-)/pi(+) ratio is an effective probe of the high-density behavior of the nuclear symmetry energy.National Natural Science Foundation of China 10675148
10635080
10575071
10675082
MOE of China NCET-05-0392
Shanghai Rising-Star Program 06QA14024
SEM of China
National Basic Research Program of China 2007CB815004
US National Science Foundation PHY-0652548
PHY-0757839
Research Corporation 7123
Texas Coordinating Board of Higher Education 0035650004- 200
Study of nucleon resonances in a chiral quark model via eta productions
No full textIn this report we investigate eta-meson productions oil the proton via electromagnetic and hadron probes in a chiral quark model approach. The observables, such as, differential cross section and beam asymmetry for the two productions are calculated and compared with the experiment. The five known resonances S-11(1535) S-11(1650); P-13(1720) D-13(1520), and F-15(1680) are found to be dominant in the reaction mech-anisms in both channels. Significant, contribution from a new S-11 resonances are deduced. For the so-called "missing resonances", no evidence is found within the investigated reactions. The partial wave amplitudes for pi(-)p -> eta n are also presented
Digital Power Supply for Accelerator Researching and Design
No full text加速器高精度数字电源对提高现代加速器的性能指标、运行效率等至关重
要。本文针对加速器数字电源的特殊要求提出了基于 TMS320F2808 的加速器电
源数字化解决方案。
基于 H 桥拓扑结构的电源运行于倍频斩波模式时可以输出双极性的直流 / 脉
冲电流波形，很适合加速器系统四极铁、六极铁等运行的需要。本文主要内容 ：
① 分析了 H 桥倍频斩波模式的工作原理，利用状态平均法建立了电源的简化 模
式的连续电流模式小信号数学模型，分别用 matlab 仿真和实验对数学模型进 行
验证，实验和仿真数据证明了该数学模型的正确性。 ② 提出了以 TMS320F2808
为核心的数字电源调节器方案，方案拥有高速数据处理和实时运算能力、高速
高精度的数据采集能力、高分辨率的数字 PWM 输出等能力，电源样机的测试结
果表明电源性能基本满足加速器要求。
本文提出的加速器数字化电源解决方案为下一步研发更大功率高精度的加
速器数字电源提供了重要的参考资料
Modification of ZnO thin films induced by ion implantation/irradiation
No full text本论文首先制备了高质量的 ZnO 薄膜，然后在室温下进行40 keV N、80 keV N、
400 keV Xe、 1 MeV Bi 离子注入实验和 3.64 MeV Xe、 5 MeV Bi、 308 MeV Xe、 2.03 GeV
Kr 离子辐照实验，以及用 2.03 Gev Kr 离子辐照80 keV N离子注入的 ZnO 薄膜实验。
注入和辐照后的样品，用拉曼散射技术、X 射线衍射分析(XRD)、扫描电子显微镜
(SEM)、透射电子显微镜(TEM)、紫外可见光谱仪和霍尔效应仪对薄膜进行分析，主要
研究离子束作用下薄膜内缺陷和结构的变化规律。
1. ZnO 薄膜经过离子注入和辐照后，拉曼光谱在 130、184、274、470、510 和
578 cm-1处出现新峰(包)，其中位于 274 cm-1处的新峰只在 N离子注入的样品中出现。
2. 离子注入实验结果表明： 拉曼光谱中578 cm-1峰(Pn1)与 99 cm-1峰(E2Low)峰面积
比η1和274 cm-1峰(Pn2)与E2Low峰面积比η2， 随注入剂量φ的变化近似符合(1-e-φ)规律，
其中σ为损伤截面，根据离子束作用下缺陷的产生规律，274 cm-1峰可以归因于注入 N
离子与缺陷结合形成的稳定结构，578 cm-1峰则与离子轰击产生的缺陷有关。随着 N
和 Xe 离子注入量的增大，薄膜的晶格常数和压应力呈增大趋势，且晶格常数变化的
程度受注入元素化学活性的影响；Xe 离子注入量达到 5.0ⅹ1015Xe/cm2时，(002)衍射
峰出现明显的双峰结构，N离子注入量 5.0ⅹ1016Xe/cm2时，(002)衍射峰在低散射
角方向出现展宽。1MeV Bi 离子注入实验中，随 Bi 离子注入量增大 ZnO薄膜的电阻
率下降，载流子浓度增强，同时显示n 型传导特性。
3. 离子辐照实验结果表明：在相同的移位原子数下，308 MeV Xe 辐照后样品内
产生缺陷远大于 3.64 MeV Xe 离子辐照，但是在相同电子能量沉积密度下，两者有相
近的趋势；随着辐照剂量的增大，3.64 MeV Xe 和 5 MeV Bi 离子辐照的 ZnO薄膜，
晶格常数呈现先微小增大， 后减少的趋势， 308 MeV Xe和2.03 GeV Kr离子辐照的ZnO
薄膜，晶格常数总体上呈现减少的趋势。
4. 对于 80 keV N离子注入(5.0×1015，5.0×1016 N/cm2)的 ZnO薄膜，经过2.03 GeV
Kr 离子辐照后，随着辐照剂量的增强，薄膜内的缺陷呈现先减少后增大的趋势；高能
辐照后薄膜内N离子与缺陷结合形成的稳定结构与离子轰击产生缺陷的比值有不同程
度的增大
一种大功率开关电源整流桥与IGBT水冷板结构
No full text本实用新型涉及一种大功率开关电源整流桥与IGBT的水冷板，其结构特征是是将4个整流桥模块和2个IGBT模块一起安装在同一块紫铜板上，板芯中设置“S”形的水路通道。本实用新型克服了现有水冷板水路管道渗水、浇铸成本过高的缺陷，在铜板有限的空间内，水路畅通，使散热面积最大，达到很好的散热目的，满足了大功率开关电源性能要求，提高了电源的整体运行效率
Relationship between cellular radio-sensitivity and naked DNA damage in mammalian cells exposed to heavy ions
No full textThe relationship between deoxyribonucleic acid (DNA) damage and the cell death induced by (12)C ions irradiation was examined in four kinds of cells, Melanoma B 16, cervical squamous carcinoma HeLa, Chinese hamster V79 and hepatoma SMMC-7721. Cell survival was determined by a colonogenic assay, and the sensitivity was described by D(50) (the dose of radiation necessary to reduce the survival to 50%). For all cell lines, D(50) ranged from 0.74 Gy to 3.85 Gy, among them B 16 was the most radiosensitive to (12)C ions, and V79 and HeLa cells had almost the same radio-sensitivity, SMMC-7721 was the last. The induction of deproteinized DNA double-strand breaks induced by (12)C ions were measured by pulsed-field gel electrophoresis (PFGE), and the initial yield of the deproteinized DNA dsbs per unit dose was expressed as the DNA double break level (L). A linear dose-response curve was seen for initial DNA dsbs for all cell lines (slopes range from 0.40-0.98 (DSBs/100Mbp/Gy)). V79 was the steepest, B 16 was the last, There was an inverse relationship between the initial DNA dsb and D(50) if the B 16 cell line was not considered, but there was no relativity even excludes the B16 cell line. The present results indicate that there is no relationship between cellular sensitivity and initial DNA dsb, even exclude the effects of chromatin structure