Superoxide Stabilization and a Universal KO2 Growth Mechanism in Potassium–Oxygen Batteries

Rechargeable potassium–oxygen (K‐O₂) batteries promise to provide higher round‐trip efficiency and cycle life than other alkali–oxygen batteries with satisfactory gravimetric energy density (935 Wh kg^?1). Exploiting a strong electron‐donating solvent, for example, dimethyl sulfoxide (DMSO) strongly stabilizes the discharge product (KO₂), resulting in significant improvement in electrode kinetics and chemical/electrochemical reversibility. The first DMSO‐based K‐O₂ battery demonstrates a much higher energy efficiency and stability than the glyme‐based electrolyte. A universal KO₂ growth model is developed and it is demonstrated that the ideal solvent for K‐O₂ batteries should strongly stabilize superoxide (strong donor ability) to obtain high electrode kinetics and reversibility while providing fast oxygen diffusion to achieve high discharge capacity. This work elucidates key electrolyte properties that control the efficiency and reversibility of K‐O₂ batteries.     

Study on the electroreduction process of oxygen to superoxide ion by using acetylene black powder microelectrode

In this paper, the powder microelectrode technique was employed in studying the voltametric response of the O₂/₂⁻ couple, which demonstrated a nearly reversible redox process at an acetylene black powder microelectrode in N,N-dimethylformamide (DMF). A well-developed steady state current plateau for the electrochemical reduction of oxygen was obtained in this system. The electron transfer number (n) and heterogeneous electron transfer rate constant k _s were measured by steady-state voltametric response, and the results were 1.08, 3.4 × 10⁻³ cm s⁻¹, respectively. Additionally, the scavenging activity of O₂⁻ with biological antioxidant (ascorbic acid) was evaluated by cyclic voltammetry; IC₅₀ came to 5 × 10⁻⁴ mol/l. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 8, pp. 1040–1044. The text was submitted by the authors in English.     

以Co2＋掺杂纳米TiO2为光催化氧化剂的原位光致化学发光分析方法 研究及其应用

研究了Co2＋掺杂TiO2纳米粒子在光信号诱导下产生的超氧阴离子自由基在纳米粒子表面的吸附和解吸特性. 当以该纳米粒子为光催化氧化剂进行原位光致化学发光反应时, 光诱导产生的超氧阴离子自由基通过扩散穿过纳米粒子表面的双电层到达本体溶液, 与溶液中的化学发光试剂进行化学发光反应. 由于超氧阴离子自由基在纳米粒子表面的吸附、解吸和双电层效应, 使得光化学反应和其后的光生氧化剂的化学发光反应具有时间和空间的分辨特性. 将 Co2＋掺杂TiO2纳米粒子光致化学发光反应的特点与鲁米诺化学发光体系结合, 建立了一种原位光致化学发光反应的新方法, 并提出了一种基于纳米技术调控化学发光反应的新思路. 在最佳反应条件下, 该方法对格列本脲响应的线性范围为2.0×10－8～1.0×10－6 g•mL－1, 检出限为6×10－9 g•mL－1.     

金属酞菁激发态与氧的相互作用

比较了几种金属酞菁光敏产生单重态氧和超氧负离子的能力,结果表明它们产生¹O₂的能力与中心金属的电子结构有关,取决于三重态寿命和量子产率。顺序如下:Zn>Ga>Cu>H₂>Al>Co。产生O₂^·-的能力不仅与三重态寿命和量子产率有关,也与激发能和氧化还原电位有关。其顺序如下:Ga>Al>Cu>Zn。还研究了酪氨酸与镓酞菁激发态相互作用,酪氨酸猝灭镓酞菁荧光。在除氧条件光激发下,酪氨酸猝灭镓酞菁的激发三重态发生电子转移,检测到GaTSPc^-在560nm处的瞬态吸收,在氧的存在下进一步反应生成O₂^·-。     

Optical probes for detection and quantification of neutrophils’ oxidative burst. A review

Neutrophils, also known as polymorphonuclear leukocytes (PMN), are the most common type of white blood cells, comprising about 50-70% of all white blood cells. In the event of inflammatory processes, neutrophils display increased mobility, tissue influx ability, prolonged life span, and an increased phagocytic capacity, constituting the initial participants in the cellular defense of the organism. One of the most important defense systems of neutrophils corresponds to their ability to mediate a strong oxidative burst through the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). While oxidative burst is important for the elimination of invading microorganisms, the overproduction of ROS and RNS or the impairment of endogenous antioxidant defenses may result to detrimental effects to the host. The nature and the extent of ROS and RNS production by neutrophils in response to different stimuli is, consequently, a matter of extensive research, with scientific reports showing an enormous variability on the detection methodologies employed. This review attempts to provide a critical assessment of the most common approaches to identify and quantify reactive species formed during the neutrophils’ oxidative burst. The detection mechanisms and performance, as well as advantages and limitations of the different methodologies, are scrutinized, focusing on the use of fluorimetric, chemiluminometric and colorimetric probes.     

盐度对蛋白核小球藻生长、叶绿素荧光参数及代谢酶的影响

以蛋白核小球藻820为实验材料,研究了3种盐度(15、30、45)对其生长、叶绿素荧光参数和两种代谢酶活性的影响,以了解该小球藻对盐度的适应能力.结果表明,蛋白核小球藻820的生长随盐度增加而变慢;而油脂含量随盐度增加而升高.叶绿素荧光参数中的PSII最大光能转化效率(Fv/Fm)、PSII实际光能转化效率(ΦPSII)、光化学淬灭系数(qP)随盐度升高下降,而非光化学淬灭系数(NPQ)随盐度升高而上升.超氧化物歧化酶(SOD)活性变化大致趋势是低盐和高盐下活性较高,碳酸酐酶(CA)活性则随盐度升高而降低,第5 d时45盐度是30盐度培养的0.43倍.因此,认为高盐一定程度地抑制了蛋白核小球藻的生长、叶绿素荧光参数和CA活性,但是促进了总脂含量和抗氧化酶SOD活性的提高.     

Expression of a Hybrid Human Superoxide Dismutase with a High Affinity for Heparin

IntroductionCopper,zinc- superoxide dismutases(SODs;EC.1.15 .1.1) are essential plasmic enzymes which cat-alyze the dismutation of highly reactive superoxideradical anions to hydrogen peroxide and oxygen so thatthe generation and clearance of oxygen free radicalsare regulated[1— 3 ] . The studies show that oxygen freeradicals play important roles in aging and the regula-tion of nitrogen monoxide[4,5] .The failure of the prop-er regulation will lead to inflammation,ischemicreperfusion injury…     

Construction of Hybrid Enzyme from HEC-SOD and Cu,Zn-SOD

Human extracellular superoxide dismutase(hEC-SOD) is a secreted tetrameric protein involved in the protection of a human body from oxygen free radicals. Its three-dimensional structure has not been confirmed, hEC-SOD couldn′t be expressed in E.coll. We constructed a hybrid enzyme, which comprises the Nterminal and C-terminal domains from hEC-SOD, fused it to human Cu, Zn-SOD. The hybrid enzyme is expressed successfully in E. coli. Further, we analyzed the expression of hEC-SOD in E. coli by mRNA differential displaying.