团簇碰撞中双团簇分子(Na_9)_2的形成研究

采用紧密结合分子动力学模型 ,对Na9+Na9碰撞系统在质心系中单原子的轰击能量为Ecm/n =0 .0 0 63eV的对心碰撞进行了研究。从动力学的观点对双团簇分子 (Na9) 2 的形成给予了证明 ,结合所谓“突然冷却”技术 ,鉴别出了所形成的 (Na9) 2 ,并给出了其结构性质

有限温度下Na4团簇的异构化

在紧密结合分子动力学模型基础上，对Ｎａ４的两种异构体Ｄ２ｈ和Ｃ２ｖ的结构性质随温度的变化进行了系统性研究。发现在低温时（温度Ｔ＜１００Ｋ），这两种异构体具有明显的不同；在较高温度时（温度Ｔ≥１００Ｋ），能够发现Ｃ２ｖ和Ｄ２ｈ两种异构体之间的转变；在更高温度时（温度Ｔ＝４００Ｋ），这两种异构体Ｃ２ｖ和Ｄ２ｈ都处于液态。Based on the tight binding molecular dynamics simulations, the structure properties of the two isomers of Na 4 with symmetries of D 2h and C 2v are systematically studied. It is found that these wo isomers present dramatically different properties at low temperatures ( T <100K) and the structure transitions between these two isomers with increasing the temperature. At temperature T =400K, both of these isomers are in the liquid like state.国家自然科学基金,中国科学院基金,国家教委基

Male infertility with chromosomal abnormalities. II. XX-male syndrome

We report two cases of the XX-male syndrome, and review the literature. The first case was a 31-year-old married man, a welder, complaining of infertility. His height was 158 cm, weight 82 kg and distance of extended hand 155 cm. The external genitalia showed a normal male type, but bilateral small testes and gynecomastia were noticed. The second case was a 32-year-old married man, a shopkeeper, complaining of infertility. His height was 165 cm, weight 60 kg and distance of extended hand 167 cm. No gynecomastia was noted. The external genitalia showed a normal male type, but bilateral small testes were noticed. In each case, azoospermia was identified in semen analysis. Urethrography revealed the prostatic utricle in the second case. The testicular biopsy specimens revealed hyalinization of seminiferous tubules and proliferation of Leydig cells. X chromatin was positive in buccal smears, and Y chromatin negative in cultured lymphocytes. Chromosomal analysis showed 46, XX karyotype in the first case and 46, XXp+ in the second case. H-Y antigen was positive in each case. Basal serum levels of LH and FSH were moderately elevated and the serum testosterone level was low. Serum levels of PRL, TSH, estradiol, GH, T3 and T4 were normal. An impaired response by testicular Leydig cells to hCG was observed. The LH and FSH responses to LH-RH were almost normal. Clomiphene citrate administration resulted in a decrease in the serum testosterone and gonadotropins levels. These results indicate hypergonadotropic hypogonadism secondary to testicular failure in both XX-males. Twenty-six cases of the XX-male syndrome have been cited in the Japanese literature. The clinical features and etiology of this syndrome are discussed

Synthesis of C-20 fullerene during Ar+ ion irradiation

Synthesized C-20 at the target surface of ultra high molecular weight polyethylene during Ar+ ion irradiation at room temperature was studied by high resolution transmission electron microscopy/electron diffraction, rime of flight mass spectroscopy, IR and Raman Spectroscopy. We believe that radiation-induced crystallites consist of caged C-20

激发态~(17)Ne双质子2p发射的实验

<正>在中国科学院近代物理研究所放射性束流装置RIBLL上完成了17Ne+197Au的实验,采用硅条探测器与CsI(Tl)+PIN探测器阵列进行运动学完全测量,研究了17Ne双质子发射的机制。实验选

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^