Polarographic Catalytic Wave of Lysozyme

Lysozyme(LE)isatypicalproteinwithwell-knownstrUcture.Itcontainsfourdisulfidebonds,andthreeofthemarewraPpedinsideLEmolecule.Thedisulfidebondbetweencys6andcysl27isexposedexternallyinthehydrophilicregi0n.ItwasfoundthatLEyieldedapolarograPhicwaveinO.2mollLNaAc~HAc(pH4.7)buffersolution.Therewereareductionwave(IP,c)andanoxidationwave(IP,a)inthecyclicvoltanunogram.ThepeakcurrentratiobetweenIP,aandIP,cwasl:l.ThepeakpotentialEP,cofthereductionwavewas-().53V(vs,SCE),andtheEP,aoftheoxidatio…     

Syntheses and Single-crystal Structures of Er3GexGeS7 （1/4≤x≤ 1/2）

As part of our systematic research on the acentric rare earth chalcogenides, the ErAlGeS5/KBr, Er3AgGeS7/KBr and Er6Ge3S14/KBr systems were investigated and three compounds belonging to the R6B2C2Q14 （R = rare earth, B = 6-coordinated element, C = 4-coordinated element, Q = S and Se） family were identified. These compounds crystallize in the P63 space group, and the crystal data are as follows： Er3Ge1/4GeS7, a = 9.6480（14）, c = 5.7920（12） A^°, Z = 2; Er3Ge0.382（8）GeS7, a = 9.6360（14）, c = 5.8460（12） A^°, Z = 2; Er3Ge1/2GeS7, a = 9.6061（13）, c = 5.8346（18）A^°, Z = 2. Single-crystal analysis indicated that the Er3GexGeS7 （x = 1/4, 0.382（8）, 1/2） structures consist of three types of building blocks： ErS7, GeS4 and GeS6 units. Er3MxGeS7 are deficient compounds with the B sites occupied partly by Ge（Ⅳ） and/or Ge（Ⅱ）.     

Catalytic synthesis of O-β-oxoalkylcarbamates

O- β -oxoalkyl-N,N-dialkyl carbamates are obtained, in one-step, by reaction of α -ethynyl alcohols, carbon dioxide and diethylamine, piperidine or pyrrolidine. The reaction is catalyzed by [RuCl₂(Norbornadiene)]_n.     

Heterogeneous Catalytic Ozonization of Sulfosalicylic Acid

This paper describes the potential of heterogeneous catalytic ozonization of sulfo-salicylic acid (SSal). It was found that catalytic ozonization in the presence of Mn-Zr-O (a modified manganese dioxide supported on silica gel) had significantly enhanced the removal rate (72%) of total organic carbon (TOC) compared with that of ozonization alone (19%). The efficient removal rate of TOC was probably due to increasing the adsorption ability of catalyst and accelerating decomposition of ozone to produce more powerful oxidants than ozone.     

Studies on Catalytic Conversion of Ethylene

FCC dry gas contains a large amount of ethylene.It is used by most of the refineries in China as fuel or simply burned in atmosphere.Few refineries make good use of the dry gas,so the precious ethylene resource in the dry gas is wasted.In this article,the possibility of catalytic conversion of ethylene to C_3,C_4,and some high molecular weight hydrocarbons in a fixed bed micro-reactor using LTB-1 catalyst,with pure ethylene as feedstock was studied.Effects of reaction temperature,reaction pressure,and feedstock flow rate,on the conversion of ethylene and the distribution of products were investigated to determine the proper reaction parameters to be used in practice.Good results indicate that this study may provide a new way of using the ethylene resource in the FCC dry gas.     

K β /K α X-ray intensity ratio in the region of 15≤Z≤22

The X-ray intensity ratioK /K has been measured by using a 10 mCi⁵⁵Fe source (MnK X-rays) and high resolution Si(Li) detector system coupled to a computer-controlled multichannel analyzer over the range of 15Z22. Corrections have been made to the measured relative intensities (K andK X-rays) for self-absorption in the sample, air, Be-window absorption and detection efficiency. The results are compared with those of other experiments and with the Scofield calculations.     

Effect of Composition of Superconducting Cuprates Bi2Sr2–xNdxCaCu2Oy(0≤ x ≤ 0.1) on their Electrophysical Characteristics and Catalytic Properties in Carbon Monoxide Oxidation

Theoretical and Experimental Chemistry - The effect of neodymium addition in the composition of complex bismuth cuprates Bi2Sr2–xNdxCaCu2Oy (0 ≤ x ≤ 0.1) on their structural and...     

Catalytic enantioselective synthesis of chiral γ-butyrolactones

A tandem catalytic asymmetric aldol reaction/cyclization of β,γ-didehydro-γ-lactones with aldehydes was achieved using chiral tin dibromide as a chiral precatalyst and sodium alkoxide as a base precatalyst. Optically active trans-β,γ-disubstituted γ-butyrolactones were selectively obtained in moderate to high yields with up to 99% ee from γ-aryl-substituted β,γ-didehydro-γ-butyrolactones and bulky aliphatic aldehydes.     

Selective Catalytic Reduction of NO with Methane

The removal of nitrogen oxides from exhaust gases has attracted great attention in recent years, and many approaches have been developed depending on the application. Methane. the main component of natural gas, has great potential as a NO reductant. In this paper, a number of catalysts previous reported for this catalytic reduction of NO have been reviewed, including a direct comparison of the relative activities and effective factors of the catalysts. Reaction mechanisnls have also been explored preliminarily.     

Catalytic Conversion of Methanol by Oxidative Dehydrogenation

This study investigates the effects of addition of oxygen on the oxidative dehydrogenation (ODH) of methanol when a fluorotetrasilicic mica ion-exchanged with palladium (Pd2 -TSM) was used as the catalyst. The reaction proceeded at a very low temperature in the presence of oxygen, and HCOOCH3 was obtained at high selectivity. By calculating the equilibrium conversion, it has been shown that substantial ODH took place for HCOOCH3 production. Consequently, this reaction would make dehydrogenation the dominant reaction at equilibrium. Not all the H dissociated from CH3OH was converted to H2O by oxidation. It has been shown that the H2O was not produced from oxidative dehydrogenation by the direct reaction of CH3OH and O2 when an attempt was made to carry out oxidative dehydrogenation using an isotope oxygen trace method in the gas phase. Therefore, when CH3OH was converted to CO2 and dehydrogenated to HCOOCH3, the C—O bonds were not dissociated.     

Catalytic enantioselective synthesis of β-trifluoromethyl pyrrolines

Enantioselective synthesis of β-trifluoromethylated pyrrolines has been developed by the organocatalyzed-conjugated addition of nitromethane to β-trifluoromethylated enones, followed by a nitro-reduction/cyclization/dehydration sequence in a one-pot procedure with 97-98% ees.     

Catalytic Acylation of Ethylidenecyclohexane over Zeolite Catalysts

Beak et al[1 ] reported that the acylation of ethylidenecyclohexane( EDC) using zincchloride as a catalyst gave 3 -( 1 -cyclohexenyl) -2 -butanone( CHB) in good yield.However,it is pity that they provided only little information about reaction conditions,and no information on comparison of activities of various catalysts. Itis well known thatconventional Zn Cl2 catalyst leads to a great number of environmental pollution,whichcould be mainly overcome by use of the solid catalysts as we have …     

Synthesis and Properties of Pr1-xRbxMnO3 (0.05≤x≤0.08) with Perovskite-Type Structure

Rb-substitued Pr_1-xRb_xMnO₃ (0.05≤x≤0.08) was successfully synthesized by solid state reaction. Powder X-ray diffraction showed that all the compounds were orthorhombic with the space group of Pnma. Spin glass behaviors were observed for all the compounds at low temperature, suggesting the competition between ferromagnetic and antiferromagnetic. The temperature dependence of the resistivity for the compound Pr_0.92Rb_0.08MnO_3.02 at 0 and 2 T magnetic field was also investigated. The compound shows semiconducting behavior, and the band gap is 0.3 eV. The maximum magnetoresistance is about 30% at 2 T magnetic field near 116 K.     

L X-ray intensity ratios of some elements in the region of 56≤Z≤83

L X-ray intensity ratios of Ba, La, Ce, Gd, Er, Yb, Ta, Au, Hg, Pb, Bi have been measured. The L shell elctrons are excited by 59.5 keV gamma-rays from ²⁴¹ Am and the L X-rays from samples are measured with a Si(Li) detector. The experimental values are compared with the theoretical values of the pure elements.     

Effect of Metallic Additives on Structure and Catalytic Properties of Supported NiPB/SiO_2 Catalyst

Supportedamorphousalloycatalystshavereceivedmuchattentioninrecentyearsbecausetheyshowlargersurfacearea,higherthermalstabilityandsuperiorcatalyticproperties'-'ascomparedwithultra-fineorrapidlyquenchedmetalmetalloidamorphousalloys.Preparation,characterizationandcatalyticperformanceofsupportedNiBcatalysthavebeenreportedbyseveralresearchgroups,however,onlyonepreparationmethodofsupportedamorphousalloycatalystcontainingNiPwasproposed"'whichwasfoundbyustobeunabletodepositNiPsufficientlyontosupport.…     

Influence of Preparation Conditions on the Catalytic Performance of MoNx/SBA-15 for Ammonia Decomposition

The influence of preparation conditions (e.g. H2-N2 ratios, final nitriding temperatures) on the performance of MoNx/SBA-15 catalysts for ammonia decomposition was investigated. The variation of catalytic activity with H2-N2 ratios may be attributed to the variation of surface compositions and particle sizes of the active components. The variation of nitriding temperatures leads to the formation of molybdenum nitride domains of varying compositions, which are responsible for the difference in their catalytic performance with respect to ammonia decomposition. At 923 K. ammonia could be completely decomposed using 15800 ml/h·gcat of GHSVNH,, which shows high performance for the catalytic decomposition of ammonia.     

Catalytic Mechanism of the “Noncatalytic” Autooxidation of Sulfite

Iron ions are shown to play a special role among transition metal ions in the oxidation of sulfite by oxygen. The thermodynamically favorable formation of chain carriers S : FeOH²⁺+ HSO₃ ^– Fe²⁺+ H₂O + , H _{r 298} ⁰ –250 kJ/mol accompanied by the regeneration of the active Fe(III) form in the reactions of Fe(II) with and HSO₅ ^–provides the efficient catalytic mechanism for sulfite consumption even at [Fe]₀ 10^–8mol/l. Any aqueous solution contains iron ions in this amounts. Thus, the noncatalytic oxidation of sulfite is in fact the catalytic reaction involving unavoidable microadmixtures of iron ions. Other transition metal ions (Mn²⁺, Co²⁺, etc.) can only enhance the catalytic effect of iron admixture.