Control and data acquisition system for collinear laser spectroscopy experiments

A control and data acquisition system was implemented for the recently developed collinear laser spectroscopy setup.This system is dedicated to data recording,storage,processing,monitoring of the beam intensity and energy,and visualization of various spectra.In comparison to the conventional resonance nuclear reaction system,the key technique is the precise synchronization of the detected counts with the actual scanning voltage(or probing laser frequency).The functions of the system were tested by measuring the hyperfine structure spectra of stable calcium(e.g.,^(40)Ca^(+))and radioactive potassium(e.g.,^(38)K)in the bunched and continuous modes,respectively.This system will be routinely applied and further improved in subsequent laser spectroscopy experiments on unstable isotopes at the Beijing Radioactive Ion-beam Facility(BRIF).

Effects of small interfering RNA targeting heparanase-1 combined with heparin on invasiveness of mouse hepatocellular carcinoma cell lines

Background and Objective:Heparanase-1 (HPA-1) can promote angiogenesis and metastasis of malignant tumors and plays an important role in the genesis and development of tumors.This study was to explore the effects of specific small interfering RNA (siRNA) targeting HPA-1 combined with heparin on invasiveness of mouse hepatocellular carcinoma cells.Methods:The expression of HPA-1 in Hca-F, Hca-P, and Hepa1-6 cells, which have high, low, and no metastatic potential, respectively, was analyzed by reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis and enzyme-linked immunosorbent assay (ELISA).After transfection with two specific siRNAs targeting HPA-1, siRNA-1 and siRNA-2, and treatment with heparin, invasiveness of Hca-F cells was observed by Matrigel invasion assay.Results:HPA-1 was negative in Hepa1-6 cells while positive in both Hca-F and Hca-P cells.The expression levels of both HPA-1 mRNA and protein were obviously higher in Hca-F cells than in Hca-P cells.HPA-1 proteins could be secreted into culture supernatant of Hca-F and Hca-P cells, and the amount of secreted HPA-1 detected by Western blot analysis was larger in Hca-F cells than in Hca-P cells (1.34±0.02 vs.0.60±0.01, P<0.001), which was consistent with the results of ELISA.Both siRNA-1 and siRNA-2 downregulated the expression of HPA-1 and the siRNA-2 did more efficiently.The number of invasive Hca-F cells treated with siRNA-2 or heparin alone was larger than that of Hca-F cells treated with combination of them (9±1 vs.4±1, P=0.013; 15±2 vs.4±1, P=0.008), but smaller than that of untreated Hca-F cells (9±1 vs.22±2, P=0.006; 15±2 vs.22±2, P=0.026).Conclusion:The combined application of specific siRNA targeting HPA-1 and heparin is more effective in inhibiting the invasiveness of mouse hepatoma cells.

Commissioning of a high-resolution collinear laser spectroscopy apparatus with a laser ablation ion source

Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility(BRIF)and the future High Intensity Heavy-ion Accelerator Facility(HIAF),we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system.The overall performance of this state-of-the-art technique was evaluated,and the system was commissioned using a bunched stable ion beam.The high-resolution optical spectra for the 4s ^(2)S_(1/2)→4p^(2)P_(3/2)(D2)ionic transition of ^(40;42;44;48)Ca isotopes were successfully measured.The extracted isotope shifts relative to ^(40)Ca showed excellent agreement with the literature values.This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonance ionization spectroscopy techniques.

二价阳离子诱导细胞膜融合的和频光谱研究

细胞膜融合是一种重要的基础生物学过程,细胞的很多生物学功能都涉及到细胞膜的融合.二价阳离子可以通过与带负电磷脂的结合诱导磷脂膜的融合,然而,其详细的分子学机制目前还不太清楚.本文应用表/界面敏感的和频振动光谱结合动态光散射实验研究了磷脂分子层对二价金属离子(如Ca^(2+)和Mg^(2+))暴露的响应.动态光散射实验测量的粒度分布结果显示Ca^(2+)可以诱导囊泡间融合,而Mg^(2+)的介导却不能导致磷脂膜的融合.为了应用和频光谱研究磷脂分子不同基团对金属离子的响应,本文设计了十八烷基三氯硅烷自组装单分子层/磷脂单分子层组成的混合模型膜系统进行和频振动光谱实验.实验发现,相比于Mg^(2+),Ca^(2+)与磷脂头部基团PO_(2)^(-)有更强烈地相互作用,会更容易诱导细胞膜融合.和频光谱实验还显示,虽然两种金属阳离子没有与磷脂中C=O基团直接连接.但是Ca^(2+)/Mg^(2+)-PO_(2)^(-)结合后,会造成C=O基团取向变化,且相较于Mg^(2+),Ca^(2+)会引起更大的取向变化.同时,和频光谱实验还证明由于Ca^(2+)-PO_(2)^(-)强相互作用,磷脂分子层通过二价金属离子桥连时,Ca^(2+)可以诱导磷脂表面脱水,这也能够减小细胞膜融合的阻碍.

Effect of boron on dissolution and repairing behavior of passive film on S31254 super-austenitic stainless steel immersed in H_(2)SO_(4) solution

The impact of boron on the dissolution and repairing behavior of passive films formed on S31254 super-austenitic stainless steel(SASS)was investigated.SASS was immersed in 0.5 mol/L of H_(2)SO_(4) for 0,2,6,10,and 14 days to explore the evolution of the passive film.The electrochemical impedance spectroscope(EIS),the Mott–Schottky analysis,and X-ray photoelectron spectroscope were utilized to analyze the semiconductor properties and compositions of the passive films.EIS showed a decrease and consequent increase over 14 days;the same pattern was observed for Cr_(2)O_(3) and Cr/Fe.However,the defect density of the passive film exhibited a reverse trend.The variation in film thicknesses indicated that the passive films possessed dissolution and repairing behavior.SASS passive film had a double-layer structure;the outer layer was found to be rich in Fe3+and Cr(OH)3,but low on Mo6+,while the inner layer was rich in Cr_(2)O_(3) and low in Mo4+.The addition of boron increased the corrosion resistance and could promote the efficiency of the passive film repair,likely by promoting the migration of Mox+,which promoted the repairing of the passive film.