Nickel/Chromium oxide/Zirconium oxide Catalysts for Hydrogen/Deuterium Isotopic Exchange

Catalysts composed of nickel and promoted with different metal oxides proved to be suitable for H/D isotropic exchange between hydrogen and water vapour. They loss their activity due to water condensation on their surfaces. Several nickel/chromium oxide/zirconium oxide catalysts of different composition were prepared by the coprecipitation technique. The liquid phase activity of these catalysts were followed using the hydrogen peroxide decomposition on their surfaces at different temperatures. The surface characteristics of the examined catalysts were followed by applying the BET method. The results were discussed and lead to the required catalyst composition which resists the water condensation on its surface during operation and has relatively high activity in the vapour phase H/D isotopic exchange reaction between hydrogen and water.     

铬胁迫对西红花叶片蛋白表达谱的影响

铬是植物的非必需元素,对植物的生长发育具有显著的抑制作用.采用双向电泳和质谱技术,研究了铬胁迫对西红花叶片蛋白表达的影响.通过质谱技术,成功鉴定出9个在铬胁迫后下调表达的蛋白,分别为细胞分裂循环蛋白48、ATP合成酶α亚基、核酮糖二磷酸羧化酶长链（2个）、未知蛋白、核酮糖二磷酸羧化加氧酶、蛋白酶体α亚基、铁蛋白和蛋白酶体β亚基;6个上调表达的蛋白,分别为蔗糖合酶、真核起始因子4A、α-1,4-葡聚糖蛋白合成酶、1-氨基环丙烷-1-羧酸氧化酶、异黄酮还原酶类似物IRL和未知蛋白.以上结果为研究植物响应铬胁迫的分子机制提供了参考.     

Trinuclear salphen–chromium(III)chloride complexes as catalysts for the alternating copolymerization of epoxides and cyclic anhydrides

Although the alternating copolymerization of epoxides and cyclic anhydrides is a promising route to aliphatic polyesters, improved catalysts are required to realize commercialization of this process. Herein, trinuclear chromium complexes of salicylaldimine, in conjunction with a nucleophilic cocatalyst, are demonstrated as excellent catalysts for epoxide/cyclic anhydride copolymerization, selectively affording perfectly alternating polyesters. The effect of the distance between the chromium species is investigated by varying the bridging skeleton in a series of trinuclear salphen–Cr(III)Cl complexes for obtaining different Cr–Cr distances. Trinuclear salphenCr(III)–complexes with Cr–Cr distances of approximately 7.3 Å are found to be efficient copolymerization catalysts, even at high temperatures and extremely low catalyst loadings. In particular, a high activity of 10,620 h⁻¹ is obtained for the copolymerization of cyclohexene oxide (CHO) and phthalic anhydride (PA) under a low catalyst loading (<0.01 mol%) at 100 °C. In situ infrared spectroscopy studies suggest that the activation energy of the trinuclear Cr(III)–salphen catalyst for CHO/PA copolymerization is 15 kJ mol⁻¹ lower than that of the corresponding mononuclear catalyst owing to an intramolecular synergistic effect among the metal atoms.     

Investigation the Effects of Green-Synthesized Copper Nanoparticles on the Performance of Activated Carbon-Chitosan-Alginate for the Removal of Cr(VI) from Aqueous Solution

In the present investigation, green nano-zerovalent copper (GnZVCu), activated carbon (AC), chitosan (CS) and alginate (ALG) nanocomposites were produced and used for the elimination of chromium (VI) from a polluted solution. The nanocomposites GnZVCu/AC-CS-alginate and AC-CS-alginate were prepared. Analysis and characterization were performed by the following techniques: X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The SEM analysis revealed that the nanocomposites are extremely mesoporous, which leads to the greatest adsorption of Cr⁺⁶ (i.e., 97.5% and 95%) for GnZVCu/AC-CS-alginate and AC-CS-alginate, respectively. The adsorption efficiency was enhanced by coupling GnZVCu with AC-CS-alginate with a contact time of 40 min. The maximum elimination of Cr⁺⁶ with the two nanocomposites was achieved at pH 2. The isotherm model, Freundlich adsorption isotherm and kinetics model and P.S.O.R kinetic models were discovered to be better suited to describe the exclusion of Cr⁺⁶ by the nanocomposites. The results suggested that the synthesized nanocomposites are promising for the segregation of Cr⁺⁶ from polluted solutions, specially the GnZVCu/AC-CS-alginate nanocomposite.     

Evaluation of Hypoglycemic Activity and Sub-Acute Toxicity of the Novel Biochanin A–Chromium(III) Complex

The novel biochanin A–chromium(III) complex was synthesized by chelating chromium with biochanin A (BCA). The structure of the complex was determined and the complex ([CrBCA₃]) was composed of chromium(III) and three ligands, and the chromium content was 55 μg/mg. The hypoglycemic activity of the complex was studied in db/db mice and C57 mice. The sub-acute toxicity test of the complex was carried out by the maximum limit method in KM mice. The hypoglycemic activity showed that the complex could reduce the weight of db/db mice and lower the fasting blood glucose and random blood glucose levels. The complex also improved the organ index, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) results of db/db mice, and some of the indicators were similar to those of the positive control group after treatment with the complex. The histopathology study showed significant improvements in the liver, kidney, pancreas and skeletal muscle compared with the diabetes model group. The complex also showed a significant improvement in serum biochemical indices and antioxidant enzyme activities, as well as glycogen levels. The sub-acute toxicity study showed that the complex did not cause death or any dangerous symptoms during the study. In addition, the sub-acute toxicity study showed that the complex had no significant effect on the serum biochemical indices, antioxidant capacity and organs of normal mice. This study showed that [CrBCA₃] had good hypoglycemic activity in vivo and had no sub-acute toxicity. This work provides an important reference for the development of functional hypoglycemic foods or drugs.     

Understanding the eighteen-electron rule

It is pointed out that the preferred closed-shell electron structures, such as those in typical high-symmetry 18-electron systems, are driven both by the bonding contributions to the centre and by the kinetic-energy (nodal-structure) terms in the ligand subsystem, L_n. The latter imposes a filling order s < p < d, even for the ML_n complex. Then the 18e principle can be right for the right reasons even without any np contributions at the central atom.     

Assembly structure convective—flow CO laser

This article describes a convective-flow CO laser composed of quartz tubes, nickel–chromium steel components, a copper heat exchanger, polytetrafluoroethylene tubes and other components. The method of vacuum sealing between quartz tubes and nickel–chromium steel pipes by polytetrafluoroethylene tubes enables the laser to operate with liquid nitrogen cooling. An output of 120 W has been obtained by adopting a non-selective cavity.     

非催化动力学光度法测定铬的研究

研究了在ＨＣｌ介质中，Ｃｒ（Ⅵ）氧化碘离子显色反应的动力学条件，建立了测定Ｃｒ（Ⅵ）的非催化动力学分析法。方法的灵敏度７．２７×１０－７ｇ·Ｌ－１，检测限５．３３×１０－６ｇ·Ｌ－１，测定范围２×１０－５～３×１０－４ｇ·Ｌ－１。用于测定标钢中的铬，测定值与标准值基本一致     

A Chromium Hydroxide/MIL‐101(Cr) MOF Composite Catalyst and Its Use for the Selective Isomerization of Glucose to Fructose

A metal–organic framework (MOF)‐based catalyst, chromium hydroxide/MIL‐101(Cr), was prepared by a one‐pot synthesis method. The combination of chromium hydroxide particles on and within Lewis acidic MIL‐101 accomplishes highly selective conversion of glucose to fructose in the presence of ethanol, matching the performance of optimized Sn‐containing Lewis acidic zeolites. Differently from zeolites, NMR spectroscopy studies with isotopically labeled molecules demonstrate that isomerization of glucose to fructose on this catalyst, proceeds predominantly via a proton transfer mechanism.