利用离子注入~(15)N靶研究超低能区~(15)N(p,α)~(12)C核反应

描述了利用离子注入固体靶测量15N(p ,α) 12 C核反应微分截面的实验过程和方法 ,给出了在163keV≤Ec≤ 360keV能区 90°方向上的微分截面测量结果和激发函数曲线 ,并对该反应的基本特征进行了分析和描述。

用~(12)C离子模拟质子引起的单粒子效应

在理论分析的基础上 ,提出了一种利用兰州重离子加速器提供的高能 12 C离子模拟质子引起单粒子效应的途径 .在保证核反应机制是引起单粒子效应主要机制的前提下 ,用高能 12 C离子可以模拟质子在功率金属 -氧化物 -半导体场效应晶体管中引起的单粒子烧毁以及单粒子栅极击穿 ,获得质子单粒子效应的饱和截面 ,定性研究质子单粒子效应的角度效应 ,还可以作为高能质子单粒子效应实验前的预备实验 .该方法拓展了兰州重离子加速器加速的轻的重离子在单粒子效应实验研究方面的应用 ,对现阶段国内开展质子单粒子效应实验研究具有重要意义

质子滴线核~(12)N在~(28)Si靶上的核反应总截面测量

描述了 5 0 .4MeV/u的12 N和 42 .3MeV/u的13 N次级放射性束在2 8Si靶上引起的核反应总截面σr 实验研究 ,结果发现12 N的反应总截面σr 比其相邻同位素核13 N有着异常的增大 .这可能是核形变及核子对效应造成的 ,试验中的测量误差也不可忽视 .利用微观Glauber模型计算了12 N在2 8Si靶上的核反应总截面 ,并与实验结果做了比较 ,发现理论计算与实验结果拟合较好

~(12)C~(6+)注入小麦种子胚乳引起M_1代的变化

通过控制单核能大小 ,将 1 2 C离子注入小麦种子胚乳 ,结果引起 M1 代植株的较大变化。这些变化包括 :生物学性状的变异 ;根尖细胞染色体畸变率和微核率的显著提高 ;POD酶活性显著提高和 CAT酶活性、MDA含量和蛋白质含量的较大程度的下降等。本文也讨论了诱变胚乳对胚作用的可能机理

~(28)Si+~(12)C中的两体反应与全熔合反应

利用ΔE E望远镜系统测量了 1 56 3MeV2 8Si+ 12 C反应 (近对称系统 )中出射的Z =4— 1 4的产物元素的能谱和角分布 ,并由此给出了这些产物的胁变截面图 .从理论上计算了Z =4— 1 1产物的实验室系最可几动能分布E1(θ)和各元素的质心系的总动能分布Et(Z) ,指出了这些产物主要来自系统的两体反应过程 .还给出了该反应系统的全熔合截面值为 (980± 68)mb ,并指出从低能数据外推到此能量下的全熔合截面值与实验值之差主要归因于两体过程 .

Quasi-Elastic Scattering of C-16 from C-12 at 47.5 MeV/Nucleon

Differential cross sections for the quasi-elastic scattering of C-16 at 47.5 MeV/nucleon from C-12 target are measured. Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.

Flower color chimera and abnormal leaf mutants induced by C-12(6+) heavy ions in Salvia splendens Ker-Gawl.

The effect of C-12(6+) heavy ions bombardment on mutagenesis in Salvia splendens Ker-Gawl. was studied. Dose-response studies indicated that there was a peak of malformation frequency of S. splendens at 200 Gy. Abnormal leaf mutants of the bileaf, trileaf and tetraleaf conglutination were selected. Meanwhile, a bicolor flower chimera with dark red and fresh red flower was isolated in M1 generation of S. splendens. Random amplified polymorphic DNA (RAPD) analysis demonstrated that DNA variations existed among the wild-type, fresh and dark red flower shoots of the chimera. The dark red flower shoots of the chimera were conserved and cultivated at a large-scale through micropropagation. MS supplemented with 2.0 mg/L BA and 0.3 mg/L NAA was the optimal medium in which the maximum proliferation ratio (5.2-fold) and rooting rate (88%) were achieved after 6 weeks. Our findings provide an important method to improve the ornamental quality of S. splendens.

~(12)C~(6+)重离子束照射治疗复发性软组织肉瘤临床疗效探讨

目的: 应用我国自主研发的重离子加速器产生的12C6+重离子束治疗复发性软组织肉瘤,评价其高线性能量传递 (LET)及低 LET在临床应用中的优劣. 方法: 3例经病理证实为软组织肉瘤自愿接受重离子束照射的患者,其中 2例病变位于腹部,1例在背部. 所有患者均为手术复发 2次以上,最多达 6次,并经手术行常规放疗失败. 应用 80～100mev/u重离子束对 3例患者分别给予总剂量 72～120 GyE/6212 f照射,生物效应剂量 (RBE) =3. 结果:2例患者 3mo后病变完全消失,达临床治愈;1例缩小 75%,达临床部分缓解,总有效率为100%.治疗中及治疗后照射野皮肤无破溃等放射性损伤.结论:12C6+重离子束具有治疗精度高,疗程短,对肿瘤周围正常组织损伤小等特点. 特别在射线抗拒的难治性肿瘤中可达到常规放疗难以实现的疗效,具有很好的临床应用前景.

Cell cycle and apoptosis alteration of human hepatocarcinoma cells by subclinical-dose C-12(6+)-beam irradiation

Objective The purpose of this study is to investigate the effect of subdinical-dose C-12(6+)-beam irradiation on cell cycle and cell apoptosis in hepatocarcinoma cells. Materials and methods The HepG(2) cells were exposed to 0-2.0 Gy of either the C-12(6+) beam or a gamma-ray. Cell survival was detected by clonogenic assay. Cell cycle was determined by flow-cytometry analysis. The apoptosis was monitored by fluorescence microscope with DAPI staining. p53 and p21 expression were detected by Western blot. Results The G(0)/G(1) cells in the irradiated groups were significantly more than those in the control (P<0.05). The C-12(6+)-ion irradiation had a greater effect on the cell cycle of HepG(2) cells (including promoting G(1)-phase and G(2)-phase arrest) than gamma-ray irradiation. The apoptotic cells induced by C-12(6+) beam were significantly more numerous than those induced by gamma-ray (P<0.05). The carbon ions had a stronger effect on p53 and p21 expression than the gamma-ray irradiation. The survival fractions for cells irradiated by C-12(6+) beam were significantly smaller than those irradiated by gamma-ray (P<0.05).

Alleviation of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma-ray on male reproductive endocrine damages induced by subsequent high-dose irradiation

Irradiation has been widely reported to damage organisms by attacking on proteins, nucleic acid and lipids in cells. However, radiation hormesis after low-dose irradiation has become the focus of research in radiobiology in recent years. To investigate the effects of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma (gamma)-ray on male reproductive endocrine capacity induced by subsequent high-dose irradiation, the brains of the B6C3F(1) hybrid strain male mice were irradiated with 0.05 Gy of C-12(6+) ion or Co-60 gamma-ray as the pre-exposure dose, and were then irradiated with 2 Gy as challenging irradiation dose at 4 h after pre-exposure. Serum pituitary gonadotropin hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), testosterone, testis weight, sperm count and shape were measured on the 35th day after irradiation. The results showed that there was a significant reduction in the levels of serum FSH, LH, testosterone, testis weight and sperm count, and a significant increase in sperm abnormalities by irradiation of the mouse brain with 2 Gy of C-12(6+) ion or Co-60 gamma-ray. Moreover, the effects were more obvious in the group irradiated by C-12(6+) ion than in that irradiated by Co-60 gamma-ray. Pre-exposure with low-dose C-12(6+) ion or Co-60 gamma-ray significantly alleviated the harmful effects induced by a subsequent high-dose irradiation.

Chromosomal aberrations induced by C-12(6+) ions and Co-60 gamma-rays in mouse immature oocytes

The ovaries of Kun-Ming strain mice (3 weeks) were irradiated with different doses of C-12(6+) ion or Co-60 gamma-ray. Chromosomal aberrations were analyzed in metaphase II oocytes at 7 weeks after irradiation. The relative biological effectiveness (RBE) of C C-12(6+) ion was calculated with respect to Co-60 gamma-ray for the induction of chromosornal aberrations. The C-12(6+) ion and Co-60 gamma-ray dose-response relationships for chromosomal aberrations were plotted by linear quadratic models. The data showed that there was a dose-related increase in frequency of chromosomal aberrations in all the treated groups compared to controls. The RBE values for C-12(6+) ions relative to (CO)-C-60 gamma-rays were 2.49, 2.29, 1.57, 1.42 or 1.32 for the doses of 0.5, 1.0, 2.07 4.0 or 6.0 Gy, respectively. Moreover, a different distribution of the various types of aberrations has been found for C-12(6+) ion and Co-60 gamma-ray irradiations. The dose-response relationships for C-12(6+) ion and (CO)-C-60 gamma-ray exhibited positive correlations. The results from the present study may be helpful for assessing genetic damage following exposure of immature oocytes to ionizing radiation.

Effect of 80.55 MeV/u(12)C(6+) ions on radiosensitivity and cell cycle of human hepatoma cell lines

In this paper, the relationship between radiosensitivity, cell cycle alteration and the change of apoptosis in different human hepatoma cell lines irradiated by heavy ions were studied with the aim of building up the base data for clinical therapy. Exponentially growing hepatoma cell lines were irradiated by 80.55 MeV/u(12)C(6+) ions at a dose of 0 Gy, 0.5 Gy, 1 Gy, 2 Gy, 4 Gy and 8 Gy. The radiosensitivity was assessed by means of the colony-forming assay. The DNA content, the percentage of each cell-cycle phase and the apoptosis rate were obtained with flow cytometry methods. After the irradiation, the SF2 (survival fraction at 2 gray) of SMMC-7721 cells were evidently lower than that of HepG2 cells. The S phase arrest, G2/M phase arrest delay and the apoptosis in the two hepatoma cell lines varied with the increase of the dose and repair time. The heavy ions could obviously kill the human hepatoma cell lines. Compared to HepG2 cells, SMMC-7721 cells were more radiosensitive to C-12(6+) ions.

Induction of cytogenetic adaptive response in spermatogonia and spermatocytes by pre-exposure of mouse testis to low-dose C-12(6+) ions

To investigate the effects of pre-exposure of mouse testis to low-dose C-12(6+) ions on cytogenetics of spermatogonia and spermatocytes induced by subsequent high-dose irradiation. the testes of outbred Kun-Ming strain mice were irradiated with 0.05 Gy of C-12(6+) ions as the pre-exposure dose, and then irradiated with 2 Gy as challenging dose at 4 h after per-exposure. Poly(ADP-ribose) polymerase (PARPs) activity and PARP-1 protein expression were respectively measured by using the enzymatic and Western blot assays at 4 h after irradiation; chromosomal aberrations in spermatogonia and spermatocytes were analyzed by the air-drying method at 8 h after irradiation. The results showed that there was a significant increase in the frequency of chromosomal aberrations and significant reductions of PARP activity and PARP-1 expression level in the mouse testes irradiated with 2 Gy of C-12(6+) ions. However, pre-exposure of mouse testes to a low dose of C-12(6+) ions significantly increased PARPs activity and PARP-1 expression and alleviated the harmful effects induced by a subsequent high-dose irradiation. PARP activity inhibitor 3-aminobenzamide (3-AB) treatment blocked the effects of PARP-1 on cytogenetic adaptive response induced by low-dose C-12(6+) ion irradiation. The data suggest that pre-exposure of testes to a low dose of heavy ions can induce cytogenetic adaptive response to subsequent high-dose irradiation. The increase of PARP-1 protein induced by the low-dose ionizing irradiation may be involved in the mechanism of these observations. (C) 2008 Elsevier B.V. All rights reserved.

Pre-irradiation with low-dose C-12(6+) beam significantly enhances the efficacy of AdCMV-p53 gene therapy in human non-small lung cancer

The combination of ionizing radiation and gene therapy has been investigated. However, there are very few reports about the combination of heavy-ion irradiation and gene therapy. To determine if the pre-exposure to low-dose heavy ion beam enhances the suppression of AdCMV-p53 on non-small lung cancer (NSLC), the cells pre-irradiated or non-irradiated were infected with 20, 40 MOI of AdCMV-p53. Survival fraction and the relative biology effect (RBE) were determined by clonogenic assay. The results showed that the proportions of p53 positive cells in C-12(6+) beam induced AdCMV-p53 infected cells were more than 90%, which were significantly more than those in gamma-ray induced AdCMV-p53 infected cells. The pre-exposure to low-dose 12C6+ beam significantly prevented the G(0)/G(1) arrest and activated G(2)/M checkpoints. The pre-exposure to C-12(6+) beam significantly improved cell to apoptosis. RBEs for the C-12(6+)+ AdCMV-p53 infection groups were 30%-60%,20% -130% and 30%-70% more than those for the C-12(6+)_irradiated only, AdCMV-p53 infected only, and gamma-irradiation induced AdCMVp53 infected groups, respectively. The data suggested that the pre-exposure to low-dose C-12(6+) beam significantly promotes exogenous p53 expression in NSLC, and the suppression of AdCMV-p53 gene therapy on NSLC.