Synthesis and Characterization of Indium-borate Glass-ceramics Containing Ho0.01Ce0.74Zr0.25O1.995 Nanorods via Incorporation Method

Glasses in the system 5In₂O₃·94Na₂B₄O₇ were fabricated via melt quenching technique. The amorphous nature of the quenched glasses was confirmed by X‐ray powder diffraction studies, and the infrared spectra of the glasses show no boroxol ring formation in the structure of these glasses. Differential thermal analysis is shown glass transition temperature 696°C and crystallization temperature 1151°C. A cerium‐zirconium mixed oxide Ce_0.75Zr_0.25O₂ and Ho‐doped cerium‐zirconium mixed oxide were obtained by solid‐state method. Then glass powder and Ho‐doped cerium‐zirconium mixed oxide were mixed. The mixture was heated in a crucible. The glass‐ceramic sample was obtained by pouring the melts on stainless steel. Obtained samples were annealed at 450°C for 1 h to remove thermal strain. Differential thermal analysis for glass‐ceramic sample is shown glass transition temperature 668°C and crystallization temperature 1159°C. The scanning electron microscopy study for glass‐ceramic indicates that the crystallized glass consists of rod‐like crystals with average diameter of about 38 nm dispersed in the glassy regions.     

Jordan derivations of full matrix algebras

Let A be a unital associative ring and M be a 2-torsion free A-bimodule. Using an elementary and constructive method we show that every Jordan derivation from M_n(A) into M_n(M) is a derivation.     

Synthesis of soluble and thermally stable polyimides from unsymmetrical diamine containing 2,4,5-triaryl imidazole pendent group

A novel unsymmetrical diamine monomer containing triaryl imidazole pendant group, 4-[4-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy] benzene-1,3-diamine (DAI), was successfully synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5-diphenyl-1H-imidazol-2-yl)phenol, followed by palladium-catalyzed hydrazine reduction. The diamine monomer DAI polymerized with commercial available dianhydrides such as benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA) and bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) by using two step synthetic methods to obtain corresponding polyimides (PIs). PIs had inherent viscosity of 0.42-0.51 dL/g and exhibited excellent solubility in aprotic polar solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), pyridine and methyl sulfoxide (DMSO). PIs showed high glass transition temperatures between 230 and 320 °C, and they were fairly stable up to a temperature above 300 and 450 °C depending on the dianhydride monomer used for the PIs preparation.     

A simple and effective approach to the synthesis of rhodanine derivatives via three-component reactions in water

A facile and direct synthetic entry to rhodanine derivatives via the three-component coupling of carbon disulfide, primary amines, and acetylenic esters under neutral conditions in water is reported.     

Synthesis of organosoluble polyamides with bulky triaryl imidazole pendent group

New unsymmetrical diamine monomer containing triaryl imidazole pendent group,4-[4-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy] -1,3-benzenediamine,was synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5- diphenyl-1H-imidazol-2-yl)phenol,followed by palladium-catalyzed hydrazine reduction.This new monomer was further confirmed by FT-IR,~1H NMR and ~(13)C NMR.Novel polyamides having pendant triaryl imidazole group were prepared by the phosphorylation polycondensation of fou...     

Transformation of methane to synthesis gas over metal oxides without using catalyst

This article reviews a new developing method in the field of metal oxide reduction in chemical and metallurgical processes, which uses methane as a reducing agent. Commonly, coal is used as the reducing agent in the reduction of metal oxide and other inorganic materials; Metal producing factories are among the most intensive and concentrated source of greenhouse gases and other pollutants such as heavy metals, sulfur dioxide and fly ash. Thermodynamically, methane has a great reducing capability and can be activated to produce synthesis gas over a metal oxide as an oxygen donor. Metal oxide reduction and methane activation, two concurrent thermochemical processes, can be combined as an efficient and energy-saving process; nowadays this kind of technologies is of great importance. This new reduction process could improve energy efficiencies and significantly decrease greenhouse gas emission compared to the conventional process; furthermore, the produced gases are synthesis gas that is more valuable than methane. In this paper, thermodynamic studies and advantages of this promising method were discussed. The major aim of this article is to introduce methane as a best and environmentally friendly reducing agent at low temperature.     

Catecholthioether derivatives: preliminary study of in-vitro antimicrobial and antioxidant activities

In this research, synthesis, antimicrobial and antioxidant activities of a series of catecholthioethers having benzoxazole and tetrazole moieties are described. Antimicrobial activity was evaluated by minimum inhibitory concentration (MIC) assay. The synthesized compounds were tested in vitro against three Gram-positive bacteria including Staphylococcus aureus (clinical isolated), Staphylococcus aureus ATCC 25922, Enterococcus faecium (clinical isolated), and two Gram-negative bacteria including Klebsiella pneumoniae (clinical isolated) and Pseudomonas aeruginosa 27853 and the yeast Candida albicans in comparison with control drugs. Microbiological results indicated that the synthesized compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between 4-256 μg/ml. This shows compounds having tetrazole moiety were the most active against Gram-negative strains, whereas compounds having benzoxazole moiety were more active against Gram-positive ones. Also both of them showed significant antifungal activity against Candida albicans and had lower activity than the compared control drugs (Sulfamethoxazole and Fluconazole). The antioxidant activity was assessed using two methods, including, 1,1-biphenyl-2-picrylhydrazyl (DPPH) radical scavenging, and reducing power assays. Some of the catecholthioether derivatives showed antioxidant activity more than Trolox and butylated hydroxyanisole (BHA) as reference antioxidants.     

Bond dissociation of the dipeptide dialanine and its derivative alanine anhydride induced by low energy electrons

Dissociative electron attachment to dialanine and alanine anhydride has been studied in the gas phase utilizing a double focusing two sector field mass spectrometer. We show that low-energy electrons (i.e., electrons with kinetic energies from near zero up to 13 eV) attach to these molecules and subsequently dissociate to form a number of anionic fragments. Anion efficiency curves are recorded for the most abundant anions by measuring the ion yield as a function of the incident electron energy. The present experiments show that as for single amino acids (M), e.g., glycine, alanine, valine, and proline, the dehydrogenated closed shell anion (M-H)(-) is the most dominant reaction product. The interpretation of the experiments is aided by quantum chemical calculations based on density functional theory, by which the electrostatic potential and molecular orbitals are calculated and the initial electron attachment process prior to dissociation is investigated.     

Biomimetic epoxidation of alkenes with sodium periodate catalyzed by tetraphenylporphyrinatomanganese(III) chloride supported on multiwall carbon nanotubes

The biomimetic epoxidation of alkenes catalyzed by tetraphenylporphyrinatomanganese(III) chloride, [Mn(TPP)Cl], immobilized on multiwall carbon nanotubes modified with 4-aminopyridine and 4-aminophenol is reported. These heterogenized catalysts were used as efficient and reusable catalysts for epoxidation of a variety of cyclic and linear alkenes with sodium periodate under mild conditions. The catalysts, [Mn(TPP)Cl@amine-MWCNT], were characterized by physico-chemical and spectroscopic methods. The effect of ultrasonic irradiation on these catalytic systems was also investigated. The catalysts were reused several times without loss of their activity.     

LaZnxFe1-xO3 钙钛矿型纳米催化剂的制备、表征及其甲苯燃烧性能

 Nanostructured LaFeO3 and substituted LaZnxFe1-xO3 (x = 0.01, 0.05, 0.1, 0.2, and 0.3) perovskites were synthesized by the sol-gel auto-combustion method and used in the catalytic combustion of toluene. Their structures and surface properties were investigated by X-ray diffraction, Fourier transmission infrared spectroscopy, BET surface area, and scanning electron microscopy. Characterization data revealed that the total insertion of zinc into LaFeO3 takes place when x ≤ 0.1. However, ZnO segregation occurs to some extent, especially at x > 0.1. The performance of these perovskites was evaluated by toluene combustion. The catalytic activity of the catalysts increased substantially with an increase in zinc substitution. These results can be attributed to the cooperative effect between LaZnxFe1-xO3 and the zinc oxide phases. The relative concentration of these phases determines their oxygen activation ability and reactivity.