应用胰凝乳蛋白酶消化法比较冬季和夏季鲢鱼肉肌球蛋白的构造特性

以夏季和冬季鲢为研究对象,利用胰凝乳蛋白酶能水解羧基端含芳香族氨基酸残基肽键的特性,根据其特异性酶切部位,结合电泳手段来分析肌球蛋白的内部构造差异性。结果表明,与夏季样品相比,冬季鲢的肌原纤维蛋白经酶切生成的肌球蛋白头部S-1较长,在高温下分子量为165 ku的重酶解肌球蛋白HMM容易被再降解成小片段的135 ku HMM,呈现出冬季肌球蛋白的结构不稳定性。在不同温度下加热夏季和冬季肌球蛋白,其ATPase失活速度和酶解肌球蛋白生成S-1的产生量的减少速度呈现一致性,说明酶解生成的S-1只来源于有活性的肌球蛋白。同时,冬季肌球蛋白热变性温度较夏季肌球蛋白要低6 ℃,表明冬季肌球蛋白的不稳定性。     

Study of the THGEM detector with a reflective CsI photocathode

The THGEM detector without and with a CsI has been tested successfully. The optimal parameters of THGEM have been determined from eight samples. The UV photoelectric effect of the CsI photocathode is observed. The changing tendency related to the extraction efficiency (ε_extr) versus the extraction electric field is measured, and several electric fields influencing the anode current are adjusted to adapt to the THGEM detector with a reflective CsI photocathode.     

Design studies on the 4π γ-ray calorimeter for the ETF experiment at HIRFL-CSR

A high detection efficiency calorimeter which is used to detect γ-rays with energies from 1 MeV up to 10 MeV as well as light charged particles has been proposed. Design of the geometry, results of the crystal tests and Monte Carlo simulations are presented in this paper. The simulation results confirm that the calorimeter can obtain high detection efficiency and good energy resolution with the current designed geometry. And the calorimeter is competent for the future External Target Facility (ETF) experiments.     

Theoretical investigation of the Gamow-Teller transition across N=40 shell

The Gamow-Teller transitions for pf shell nuclei with proton number less than 40 and neutron number larger than 40 were believed to be blocked, due to the full filling of the neutron orbit. However, recent experimental research shows that the Gamow-Teller transitions for these kinds of nuclei are not blocked. In this paper, we systematically calculate the GT transition of pf shell nuclei ⁷⁶Se in different truncations, and the results are compared with experimental results. It is shown that, due to correlations, the believed blocked GT transition occurs, and the shell model calculations reproduce the experimental GT strength. In addition, the electron capture rates in a stellar environment are calculated and discussed.