Single‐atomic Co‐B_(2)N_(2)sites anchored on carbon nanotube arrays promote lithium polysulfide conversion in lithium-sulfur batteries

Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.

Efficient and Convenient Procedures for the Formation andCleavage of Steroid Acetals Catalysed by Montmorilloaite K 10

Acetalization of steroid ketones and cleavage of the acetals have ben carried out inexcellent yield under catalysis of montmorillonite K 10.

Catalytically Modified Pt/Catalysed TiO_2/SiC Devices for Hydrogen and Hydrocarbon Gas Sensing

In this paper the hydrogen and hydrocarbon gas sensing performance of the Pt/Catalysed TiO_2/SiC devices have been studied.The TiO_2 metal oxide thin films were catalytically modified employing Pt and Pd.The electrical properties of the fabricated devices were studied by measuring their capacitance-voltage (C-V),conductance-voltage (G-V) and dynamic response characteristics.The sensor's response as a function of operating temperature (25℃to 700℃) and concentrations less than 1% of the analyte gases have been investigated.The sensitivity of the Pt catalysed TiO_2 sensor was found to be superior when compared to TiO_2 catalysed with Pd.A voltage shift of 3.2 V for 1% propene at 420℃and 2.8 V for 1% hydrogen at 250℃in an ambient containing synthetic air was recorded for the Pt catalysed TiO_2 sensor.The response of Pt catalysed TiO_2 sensor was found to be approximately 4 times larger when compared to the non catalysed counterpart.

SYNTHESIS OF (~3H-METHYL) TRINITROTOLUENE AND ITS APPLICATION TO TOXICOLOGICAL STUDY

In this paper, (2H- methyl) toluene was prepared by catalysed halogen- tritium substitution method from benzyl bromide, then it was nitrated to produce (8H- methyl) trinitrotoluene. The tritiated product was purified by thin- layer chromatography. At last, the pure 3H- TNT was obtained with specific radioactivity of 3.77 GBq/mmol. Radiochemical purity was over 98% and the ultraviolet absorption spectrum of tritiated TNT was conformed with that of standard sample. Using 3H- TNT as a tracer, its toxicokinetics was sudied in rats. The results showed that the toxicokinetics characteristics of TNT were quickly absorbed into the blood, Vd】2L/kg.h, long T1/2β and fixed accumulation with four routes of administration, TNT and its metabolites were mainly excreted by the urine. The half- life of TNT in the urine were 1,1- 24h. A trace of radioactivity of 3H- TNT and its metabolites could be detected in the urine on 7th day after administration (9.25×106Bq/kg).

Constraint of Isomorphous Substitution in Magnetite on Its Catalytic Activity in Heterogeneous Fenton Reaction

In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some of the substituting cations, e.g. Cr3+, V3+ and Mn2+, improve the catalytic activity of magnetite in heterogeneous Fenton reaction through the enhancement of hydroxyl radical OH production and the pollutant adsorption.

The Synthesis and Characterisation of Polyaniline Catalysed and Doped by Squaric acid

Aniline was polymerized in dilute aqueous squaric acid and the polyaniline(PAn) was doped with 10 -1 10 -3 mol/L of squaric acid. The corresponding electrical conductivity of the PAn is 10 -1 10 -2 S·cm -1 . The solubility of the doped PAn has been improved in common polar organic solvents . The FTIR and UV-Vis spectra show that the PAn has the structure of both quinone and imine .

~3H—LABELLING OF BELLADONNA ALKALOIDS BY CATALYSED EXCHANGE WITH MICROWAVE EXCITATION

The ~3H-labelled belladonna alkaloids obtained by catalysed exchange method with microwave excitation was investigated. The specific activities of the labelled products Were 16—32 TBq/mol. More than 90% labelled positions of these ~3H-tracers were on phenyl rings. The radiochemical purity and chemical purity of crude products were both in 75—80%.

Stepwise Pyrolysis by LBCR Downstream to Enhance of Gasoline Fraction of Liquid Fuel from MMSW

Pyrolysis is one of the thermal cracking methods to convert hydrocarbon to liquid fuel.The quantity and quality of the process are dependent on several condition including temperature,reaction time,catalyst,and the type of reactor.Meanwhile,a gasoline fraction was maximum product to be considered in the pyrolisis process.Therefore,this study aims to increase the gasoline fraction in liquid fuel using stepwise pyrolysis with a long bed catalytic reactor downstream(LBCR).The LBCR downstream was equipped with the top and bottom outlet and the fed source was mixed municipal solid waste(MMSW).The activated natural dolomite at 500℃ was used to allow the repetition of the secondary cracking.Also,the reactor temperature was setup at around 200℃-300℃ and the pyrolizer was 400℃.To analyze the gasoline fraction and physical properties of liquid fuel,Gas Chromatography-Mass Spectroscopy(GC-MS)and ASTM standard were employed.The experimental results showed there was a significant increase in the gasoline fraction of liquid fuels compared to using direct catalytic cracking and absence of catalysts.By using a LBCR at 250℃,the liquid fuel obtained at top outlet(TO)and bottom outlet(BO)have 84.08 and 56.94 percent peak area of gasoline fraction(C5-C12),respectively.The average value(TO and BO)of the fraction at 250℃ by LBCR was 70.51 percent peak area and it was increased by about 93.6%and 51.14%compared to without catalyst and direct catalytic,respectively.Furthermore,pyrolytic liquid oils were found to have kinematic viscosity of 2.979 and 0.789 cSt,density of 0.781 and 0.782 g/cm^(3),and flash point<−5℃ for BO-250 and TO-250 liquid fuel,respectively.These results showed BO liquid fuel was comparable to diesel conventional fuel while TO liquid fuel was comparable to gasoline.Evidently,the presence of LBCR made a major contribution to generate multi secondary cracking and to produce more gasoline fraction from mixed MMSW feedstock,as well as to increase the physical properties of liquid fuel.

Adsorption of CO₂and H₂on Cu and Zn Micro-Cluster Surfaces Studied by Quantum Chemistry and Theory of Absolute Reaction Rates

Statistical mechanics and semi-empirical molecular orbital theory (PM6) are used to calculate the surface coverage of CO2 and H2 molecular species chemically adsorbed on the surface of Cu and Zn micro clusters. The calculation shows that CO2 is adsorbed well both on the surface of Cu and Zn micro clusters. Although H2 is adsorbed well on the surface of Zn micro clusters, H2 absorption on the surface of Cu micro clusters is much more limited in the pressure range of 20 - 100 atm and temperature range of 200 - 1000 K. Reaction rates are also estimated for some chemical adsorption process of H2 gas using theory of absolute reaction rates. It is found that the values of the reaction rate calculated in the present paper agree reasonably well with the experimental values.

Whole‑cell catalytic synthesis of trehalose by Corynebacterium glutamicum displaying trehalose synthase on its cell surface

Trehalose is a disaccharide with many applications in cosmetics,refrigeration,and food.Trehalose synthase is a significant enzyme in trehalose production.Escherichia coli is usually used to express this enzyme heterologously.Since E.coli is a pathogenic strain,we chose Corynebacterium glutamicum ATCC13032 as an engineering strain in this study for food safety reasons.Because of its poor permeability,we constructed two recombinant C.glutamicum strains using two anchor proteins,PorH,and short-length NCgl1337,to anchor trehalose synthase from Streptomyces coelicolor on the cell surface and synthesize trehalose directly from maltose.Studies on enzymatic properties indicated that NCgl1337S–ScTreSK246A had better enzyme activity and thermal stability than the free enzyme.After optimizing the whole-cell transformation,the optimal transformation condition was 35°C,pH 7.0,and OD600 of 30.Under this condition,the conversion rate of 300 g/L maltose reached 69.5%in a 5 L fermentor.The relative conversion rate was still above 75%after repeated five times.

A general and efficient Lewis acid catalysed Mukaiyama-aldol reaction of difluoroenoxysilanes and ketones

We report a general and highly efficient Mukaiyama-aldol reaction of ketones and difluoroenoxysilanes.While the reaction of aryl ketones worked efficiently in the presence of Bi(OTf)_3, that of aliphatic ketones required the use of Sc(OTf_)3. In addition, Sc(OTf)_3 was capable of achieving excellent 1,2-selectivity in the corresponding reaction of α,β-unsaturated ketones. This method provides a facile access to differently substituted β-hydroxy α,α-difluoro ketones, versatile synthons for difluomethylated tertiary alcohols.

Synthesis of Highly Regioregular, Head-to-Tail Coupled Poly(3-octylesterthiophene) via C―H/C―H Coupling Polycondensation

Highly regioregular, head-to-tail coupled poly（3-octylesterthiophene） was synthesized by the Pd-catalysed oxidative C--H/C--H coupling polycondensation. The regioregularity of polymer products was confirmed by the 1H-NMR technique. Furthermore, the effects of various reaction factors including polymerization temperature, solvents and catalysts etc. on the yield, molecular weight and structural regioregularity of the resultant polymers were systematically studied. The optical, electrochemical and crystallization properties of the resultant P3OET with different HT regioregularities in solution and film state were studied by UV-Vis and fluorescent spectroscopy, cyclic voltammetry and X-ray diffraction （XRD）, resepectively.