Effect of calcium ions on the secondary structures of photosystem II and its relations with photoinhibition

Calcium ions play an important role in the oxygen-evolving process of photosystem II as demonstrated in many experiments. The changes of the secondary structures of PS II induced by the depletion of Ca²⁺ were reported. The results indicated that the removal of Ca²⁺ led to the transition of ahelix to turns and sheet structures. While Ca²⁺ was re-added to the media, only the structures changed to turns could be recovered. The protein conformational changes of PS II during the donor side photoinhibition induced by the depletion of ca²⁺ were also studied. This showed that the protein conformational changes differed between the control and Ca²⁺-depleted samples in a short period of illumination (within 10 min). However, the changes became similar when the illumination time was increased.     

Laser induced photoemission electron and the generation of high Rydberg states of atoms and molecules

Laser induced photoemission electron was produced by directing 532 nm and/or 355 nm onto stainless steel plate on a time of flight mass spectrometer. Multiple charged ions and high Rydberg states of atoms or molecules were successfully generated by impacts of the photoemission electrons. The high Rydberg states ( n ～40-100) thus produced were separated from ions, produced by direct electron impact ionization, by a 3 V DC electric field and then ionized by a delayed pulsed HV electric field in a ZEKE-PFI manner. Relationship between generation/property of high Rydberg states of atoms/molecules and experimental conditions could be investigated. Relationship between the electron accelerating voltage and high Rydberg states of Ar was described.     

电化学传感器及其在重金属检测中的应用

重金属污染因其具有持久性、生物富集性和毒性而备受关注.相比于传统检测重金属的方法,电化学传感器具有成本低、灵敏度高、操作简便、易携带等优点,更适于现场检测.文章从电化学传感器的构建原理出发,系统介绍了电化学传感器的种类、制备工作电极的材料以及用以修饰电极的各种材料,分析了用这些材料制备的电化学传感器在重金属检测中的优缺点,指出在实践过程中需要对工作电极和修饰材料进行选择和优化,耐用性强、微型化、自动化、多功能化将是电化学传感器今后的主要发展方向.     

农林废弃物吸附去除水中重金属的研究进展

农林废弃物作为一种可再生的生物质资源,在吸附重金属离子方面具有很强的开发潜能,可望用于回收工业污水中的重金属,但目前尚未得到充分利用.为了农林废弃物能够在重金属去除方面提供参考,结合国内外的研究状况,对农林废弃物去除重金属离子的研究进行综述.探讨农林废弃物作为吸附剂的吸附机理、有效结构、影响因素,并对后期的研究工作进行展望.     

6—30keV单电荷离子与H2分子碰撞的单电子剥离截面的测量

用增长率方法测量了６－３０ｋｅＶＨｅ＾＋，Ｎｅ＾＋，Ａｒ＾＋，Ｋｒ＾＋，Ｘｅ＾＋及Ｃｌ＾＋离子与Ｈ２分子碰撞的单电子剥截面，Ｈｅ＾＋的截面数量与他人数据一致，其他的截面数据在此之前未见报道。     

熔盐的内压与正负离子间距

液体内压的对应状态模型亦适用于熔融碱金属卤化物，模型中的特性常数ｂ正比于晶体中正、负离子间距，这使该模型能够预测熔融碱金属卤化物的内压，预测结果与实验值基本一致。     

General kinetic model of imperfect living polymerization (IV)

The living ionic polymerization with two active species was theoretically studied, presenting the expressions of the number- and weight-average degrees of polymerization and the polydispersity index. The numerical calculation shows that both steady state and non-steady state approaches result in the essentially same outcomes when the exchange rate between the two active species is larger than the rates of chain propagation; however, the steady state method leads to a larger error and only the non-steady state approach is valid if the exchange rate between the two active species is comparable to or smaller than propagation rates. In addition, the molecular weight distribution of the resulting polymer becams narrower with the value of κ_p, approaching to κ′_p, and with increasing M₀/I₀.     

金属离子与EDTA配位稳定性的拓扑指数法研究

根据元素键参数拓扑指数，并计算了５４ 种金属离子的拓扑指数，用于关联金属离子与ＥＤＴＡ配位稳定常数研究，得到了较好的线性相关性。     

Secondary ion mass spectrometry of high-sulfur coal: Observation and interpretation of polysulfur ions

The chemical state of sulfur existing in superhigh-sulfur coal has been studied with high-performance static secondary mass spectrometry. A species of polysulfur ions, as most reasonable mass spectrometric fragments of molecules of elemental sulfur or sulfurite, is observed and exactly determined through accurate mass analysis and isotopic pattern analysis. From the observation, the chemical form of elemental sulfur is considered to occur naturally in coal, particularly in its organic phases or maceral such as telocollinite.     

金属离子对R2工程菌纤维素酶的催化作用

研究了不同金属离子对纤维素酶活的影响。重点阐述了从R2工程菌分离纯化纤维素酶的方法。结果表明:Cu2+对酶活有一定的抑制作用,其余各种离子在一定浓度范围内对酶活都有促进作用;在Ca2+、Cu2+、Zn2+的实验中,Ca2+促进作用大于Zn2+;在K+、Na+、Li+的实验中,Li+促进作用明显;对于不同配比的K+、Na+、Li+的实验中,K+∶Na+∶Li+(1∶1∶2)的促进作用较明显。表明在反应中加入一定的金属离子对纤维素酶活有一定的促进作用。