Thermodynamics for chemical vapor synthesis of Nb nanopowder in NbCl_5-H_2-Ar system

Thermodynamics for chemical vapor synthesis （CVS） of Nb nanopowder in NbCl5-H2-Ar system was investigated by using FactSage software. The validation experiments were conducted to confirm the thermodynamics points. The results indicate that under the atmospheric pressure, the reduction approach from NbCl5（g） to Nb（s） is a stage-wise process with the formation of complex sub-chlorides, and is controllable at low hydrogen ratio （mole ratio of n（NbCl5）：n（H2）＆lt;1：180） and low temperature （＆lt;1050 ＆#176;C）. Furthermore, a reasonable amount of inert loading gas is favorable to increase the reduction ratio of NbCl5 and the powder yield. The as-synthesized Nb nanopowder with the homogeneous size of 30-50 nm and the powder yield of 85% （mass fraction） is obtained by the CVS process under n（NbCl5）：n（H2）：n（Ar）=1：120：1 and 950 ＆#176;C with the NbCl5 reduction rate of 96.1%.

Synthesis and Characterization of Y-Doped Mesoporous CeO_2 Using A Chemical Precipitation Method

Using cetyltrimethylammonium bromide （CTAB） as the template agent, cerium nitrate as the cerium resource, yttrium nitrate as the yttrium resource, and ammonium carbonate as the precipitating agent, mesoporous CeO2 powders doped with different yttrium contents were successfully synthesized using a chemical precipitation method, under an alkalescent condition. Properties of the obtained samples were characterized and analyzed with X-ray diffraction （XRD）, energy dispersive analysis of X-rays （EDAX）, transmission electron microscopy （TEM）, infrared （IR） absorbance, and the BET method. For the prepared samples with 20% （molar ratio） Y-doped content, a BET specific surface area of 106. 6 m^2 · g^- 1, with an average pore size of3~27 nm were obtained. XRD patterns showed that the doped samples were with a cubic fluorite structure. TEM micrographs revealed that the doped samples showed a spherical morphology with a diameter ranging from 20 to 30 nm and a round pore shape. IR results indicated that the Ce-O-Ce vibration intensity decreased as the Y-doped content increased. N2 adsorption-desorption isotherms showed that the samples possessed typical mesopore characteristics. The average pore size of the samples decreased alter mesoporous CeO2 was doped with yttrium, and the average pore size decreased largely as the Y-doped content increased.

Synthesis of steel slag ceramics: chemical composition and crystalline phases of raw materials

Two types of porcelain tiles with steel slag as the main raw material （steel slag ceramics） were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, a-quartz, magnetite, and pyroxene crystals （augite and diopside） in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction （XRD） and electron probe X-ray microanalysis （EPMA） results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

Fischer–Tropsch synthesis using Co and Co-Ru bifunctional nanocatalyst supported on carbon nanotube prepared via chemical reduction method

We used a chemical reduction method to synthesize the catalysts of cobalt(Co) and cobalt-ruthenium(Co-Ru) bifunctional supported on carbon nanotubes(CNTs) for Fischer–Tropsch synthesis(FTS) in a fixedbed reactor. These Co-Ru/CNTs catalysts were synthesized with various weight proportions of Ru/Co(0.1 to 0.4 wt%) with keeping a fixed amount of cobalt(10 wt%). Moreover, for comparison purpose, CNTs supported Co-and Co(Ru)-based catalysts at same loading as the above catalysts were prepared through impregnation method. We characterize the present catalysts through the various techniques such as Energy–dispersive X-ray(EDX), Transmission Electron Microscopy(TEM), Brunauer–Emmett–Teller(BET),Hydrogen-Temperature-Programmed Reduction(H_2-TPR), Hydrogen-Temperature-Programmed Desorption(H_2-TPD) and O_2 titration. Thus using the chemical reduction method, a narrow particle size distribution was obtained so that the small cobalt particles were confined inside the CNTs. The Co-based catalyst prepared by impregnation was compared with the Co-Ru catalysts at the same loading. The results demonstrated that the use of chemical reduction method led to decrease the average Co oxide cluster size to8.7 nm so that the reduction enhanced about 24% and stabilized an earlier time at the stream. Among the prepared catalysts, the results indicated that the Co-Ru/CNTs catalysts demonstrated high catalytic activity with the highest long-chain hydrocarbons(C_(5+)), selectivity up to 74.76%, which was higher than those we obtained by the Co-Ru/γ-Al_2O_3(61._20%), Co/CNTs(43.68%) and Co/γ-Al_2O_3(37.69%). At the same time, comparing with those catalyst synthesized by impregnation, the use of chemical reduction led to enhancement of the C_(5+) selectivity from 59.30% to 68.83% and increment in FTS rate about 11% for the Co-Ru/CNTs catalyst.

Chemical synthesis of nanocrystalline ZrO_2-SnO_2 composite powders

ZrO_2-SnO_2 composite nanoparticles were prepared by heating the hydrateprecursors synthesized by the chemical co-precipitation reaction of ZrOCl_2 and SnCl_4. Theprecursors were examined by differential thermal analysis (DTA) and thermogravimetric analysis(TGA). The composite powder was characterized using X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and desorption isotherm (Barrett-Joyner-Halenda method). The average crystal sizeof the nanoparticle ranges from 15 to 30 nm for the sample containing 5%-25% ZrO_2 (mass fraction).Most of the pores in the ZrO_2-SnO_2 nanoparticles are about 10-20 nm in diameter. The compositepowder is promising for chemical sensors.

Preparation and characterization of calcium aluminate by chemical synthesis

Saturated Ca（OH）2 and AlCl3 solutions were used to synthesize calcium aluminate hydrate precipitates at room temperature; high purity calcium aluminate powders with stable phases were made by calcination of the precursors at a temperature as low as 1100℃. PSD and BET analysis revealed the particles with sizes ranging from submicrometer to several micrometers and with a specific area of 13 m^2/g. The measurement of hydraulic exotherm revealed that the exothennal rate is in peak for about 2 h. The exothermal quantities are 449.24 J/g at 12 h and 488.38 J/g at 24 h. Its strength development is quick and the 1 day curing strength is almost equal to 100% of the 3 days curing strength in the mortar test.

Synthesis of Cell Adhesive Motif RGD Tripeptide by a Novel Chemical Method and Its Purification

The cell adhesive motif RGD tripeptide was synthesized by using a novel chemical method. First, Gly-Asp（GD） was synthesized in two steps including the chloroacetylation of free L-aspartic acid and the ammonolysis of the chloroacetylated L-aspartic acid. The yield of chloroacetylated L-aspartic acid was 83.0%. For the ammonolysis of chloroacetylated L-aspartic acid, the yield of the ammonolyzed product was 92. 3%. Second, the coupling between Arg and Gly-Asp was carried out by using the NCA method. The maximum yield of RGD was about 50% at 0℃ and pH = 9. 5. The prepared RGD tripeptide was confirmed by using amino acid component analysis and mass spectrographic analysis.

Atomic Level Dispersed Metal–Nitrogen–Carbon Catalyst toward Oxygen Reduction Reaction: Synthesis Strategies and Chemical Environmental Regulation

For development and application of proton exchange membrane fuel cell(PEMFC) energy transformation technology, the cost performance must be elevated for the catalyst. At present, compared with noble metal-based catalysts, such as Pt-based catalysts, atomically dispersed metal–nitrogen–carbon(M–N–C) catalysts are popularity and show great potential in maximizing active site density, high atom utilization and high activity,making them the first choice to replace Pt-based catalysts. In the preparation of atomically dispersed metal–nitrogen–carbon catalyst, it is difficult to ensure that all active sites are uniformly dispersed, and the structure system of the active sites is not optimal. Based on this, we focus on various approaches for preparing M–N–C catalysts that are conducive to atomic dispersion, and the influence of the chemical environmental regulation of atoms on the catalytic sites in different catalysts. Therefore, we discuss the chemical environmental regulation of the catalytic sites by bimetals, atom clusters, and heteroatoms(B, S, and P). The active sites of M–N–C catalysts are explored in depth from the synthesis and characterization, reaction mechanisms, and density functional theory(DFT)calculations. Finally, the existing problems and development prospects of the current atomic dispersion M–N–C catalyst are proposed in detail.

Hydrothermal Synthesis,Crystal Structure,Spectrum Properties and Quantum Chemical Calculation of a Trinuclear Copper(Ⅱ) Complex with 3-(Pyridin-2-yl)-1,2,4-triazole

A three-dimensional framework copper（Ⅱ） coordination polymer with copper carbonate basic and 3-（pyridin-2-yl）-1,2,4-triazole （Hpt） has been hydrothemally synthesized.The complex （2,C14 H10 CuN8 ·3H2 O） crystallizes in tetragonal,space group P4 2 /n,a=2.08581（12）,b=2.08581（12）,c=0.72331（4） nm,M r=761.73,V=3.1468（3） nm 3,Dc=1.608 g/cm 3,Z=4,F（000）=1552,GOOF=1.07,R=0.0515 and wR=0.1689.Every asymmetric unit molecular structure of the complex is composed with one copper ion,one and half water molecules and two Hpt molecules.Each copper ion is coordinated with five nitrogen atoms from four Hpt molecules,forming a distorted square pyramidal geometry.The fluorescence spectrum analysis shows that the title complex at room temperature exhibits intense photoluminescence with maximum emission at 450 nm.The quantum chemistry calculation study on the complex has been performed.The stability,some frontier molecular orbital energies and composition characteristics of some frontier molecular orbitals of the complex have been investigated.

Thermodynamic Analysis and Synthesis Gas Generation by Chemical-Looping Gasification of Biomass with Nature Hematite as Oxygen Carriers

Thermodynamic parameters of chemical reactions in the system were carried out through thermodynamic analysis. According to the Gibbs free energy minimization principle of the system, equilibrium composition of the reactions of chemical-looping gasification (CLG) of biomass with natural hematite (Fe2O3) as oxygen carrier were analyzed using commercial software of HSC Chemistry 5.1. The feasibility of the CLG of biomass with hematite was experimental verified in a lab-scale bubbling fluidized bed reactor using argon as fluidizing gas. It was indicated the experimental results were consistent with the theoretical analysis. The presence of oxygen carrier gave a significant effect on the biomass conversion and improved the synthesis gas yield obviously. It was observed that the gas content of CO and H2 was over 70% in CLG of biomass. The reduced hematite particles mainly existed in form of FeO. It was showed that the reduction of natural hematite with biomass proceeds in a stepwise manner from Fe2O3 →Fe3O4→ FeO. Reduction product of natural hematite can be restored the lattice oxygen by oxidation with air.

Soft chemical synthesis and electrochemical properties of tin oxide-based materials as anodes for lithium ion batteries

A novel soft chemical approach was developed to synthesize tin oxide-based powders. The microstructure, morphology, and electrochemical performance of the materials were investigated by X-ray diffraction, scanning electron microscope and electrochemical methods. The results show that the particles of tin oxide-based materials form an interconnected network structure like mesoporous material. The average size of the particles is about 200 nm. The materials deliver a charge capacity of more than 570 mA·h·g-1. And the capacity loss per cycle is about 0.15% after being cycled for 30 times. The good electrochemical performance indicates that tin oxide-based materials are promising anodes for lithium ion batteries.

Soft chemical synthesis and luminescence properties of red long-lasting phosphors Y_2O_2S:Sm^(3+)

Sm3＋-activated Y2028 red phosphors were prepared by the combustion method and microemulsion method at the first time. X-ray characterization and electron diffraction show that, Y202S：Sm3＋, Ti4＋, Mg2＋ samples prepared by these two methods are pure hexagonal crystals in structure with a trivial change due to dopants. Scanning electron microscopy （SEM） results show that the product presents an almond-like sheet in uniform size. Under the excitation of 269 nm ultraviolet light, Y202S：Sm3＋ samples fabricated by these two methods exhibit three main groups of red emission lines located at 564, 604, and 656 nm, respectively, which are attributed to the transitions of 4G5/2 →6H5/2, 4G~/2 →6H7/2, 4G5/2 →6H9/2, respectively. The samples prepared by microemulsion are seven times higher in fluorescent emission intensity and half time longer in afterglow time than that prepared by combustion.

Progress in Chemical Synthesis of Peptides and Proteins

For the proteins that cannot be expressed exactly by cell expression technology (e.g., proteins with multiple posttranslational modifications or toxic proteins), chemical synthesis is an important substitute. Given the limited peptide length offered by solid-phase peptide synthesis invented by Professor Merrifield, peptide ligation plays a key role in long peptide or protein synthesis by ligating two small peptides to a long one. Moreover, high-molecular-weight proteins must be synthesized using two or more peptide ligation steps, and sequential peptide ligation is such an efficient way. In this paper, we reviewed the development of chemical protein synthesis, including solid-phase peptide synthesis, chemical ligation, and sequential chemical ligation. © 2017, The Author(s).

Chemical Synthesis and Magnetic Properties of Nanocrystalline (La_(0.67-X)Gd_X)Sr_(0.33)MnO_3 Using Amorphous Molecular Alloy as Precursors

A new route to synthesize nanosized crystalline of （La0.67-xGdx）Sr0.33MnO3 （X=0.05, 0.10, 0.15, 0.20） perovskite-type complex oxides at calcination temperature of 600-1000℃ using the amorphous molecular alloy as precursors was reported. The precursor could be completely decomposed into complex oxide at temperature below 500℃ according to the TGA and DTA results. XRD demonstrates that the decomposed species is composed of perovskite-type structure at calcination temperature of 600℃ for 2 h. The particle size that depends on the calcination temperature of the precursor is in a range of 30-120 nm as determined by transmission electron microscopy （TEM）. This method is effective and can be easily quantitatively controlled to synthesize nanosized perovskite-type complex oxides. The magnetic properties of （La0.67 xGdx）Sr0.33MnO3 nanocrystalline were preliminary studied.

Chemical synthesis of magnetic nanocrystals:Recent progress

Colloidal chemical synthesis of various types of magnetic nanocrystals is discussed with regard to recent discoveries. We first outline the chemical preparation of single-component magnetic nanocrystals with controlled size, shape, and uniformity based on several solution-phase methods, especially thermal decomposition and/or reduction method. Then we discuss the synthetic strategies of multi-component nanocrystals incorporating at least one magnetic component by manipulating heterogeneous nucleation and growth process. Toward the end, approaches for preparing hollow/porous magnetic nanocrystals are highlighted. We believe that the summarized chemical synthesis will pave the way for the future development of extraordinary magnetic nanocrystals.

Synthesis and Growth Mechanism of Carbon Filaments by Chemical Vapor Deposition without Catalyst

Carbon filaments with diameter from several to hundreds deposition of methane without catalyst. The morphology micrometers were synthesized by chemical vapor microstructure and mechanical properties of the carbon filament were investigated by scanning electronic microscopy, optical microscopy, X-ray diffraction and mechanical testing. The results show that the carbon filament is inverted cone shape and grows up along the gas flow direction. The stem of it is formed of annular carbon layers arranged in a tree ring structure while the head is made up of concentrical layers. The tensile strength of the carbon filament is increased after graphitization for the restructuring and growing large of graphene. The growth mechanism of carbon filament was proposed according to the results of two series of experiments with different deposition time and intermittent deposition cycles.

Synthesis, Crystal Structure,Characterization and Quantum Chemical Studies on 1N-Acetyl-3-(2,4-dichloro-5-fluoro- phenyl)-5-(p-methyl-phenyl)-2-pyrazoline

1N-Acetyl-3-（2,4-dichloro-5-fluoro-phenyl）-5-（p-methyl-phenyl）-2-pyrazoline has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray single-crystal diffraction. Ab intio calculations have been carded out for the compound by using both B3LYP and HF methods at the 6-31G^＊ basis set. The calculated results show that the predicted geometry can well reproduce the structural parameters. The electronic absorption spectra calculated by B3LYP/6-31G^＊ method are approximate to the experiments and the Natural Bond Orbital （NBO） analyses suggest that the above electronic transitions are mainly assigned to n→π^＊ and π→π^＊ transitions. CIS-HF/6-31G^＊ method is not suitable to predict the electronic spectra for the title compound. The calculation of the second order optical nonlinearity was carded out, giving the value of molecular hyperpolarizability equal to 2.194^＋ 10^-30 esu. On the basis of vibrational analyses, the thermodynamic properties of the compound at different temperature have been calculated, revealing the correlation between C p, m^0, S m^0, H m^0 and temperature.

Chemical synthesis and cloning of human calcitonin (hCT) cDNA

Chemical synthesis and cloning of human calcitonin (hCT) cDNA. Methods and Results:The cDNA sequence coding for human calcitonin (hCT) was divided into 6 fragments, synthesized by ABI 391 DNA synthesis instrument and cloned into PGEM7Z(+) vector following phosphorylation, annealing and ligation of the 6 fragments. The sequence of cloned hCT cDNA was proved to be the same as designed by double DNA sequencing. Conclusion: A reliable and forthright method of chemical synthesis and cloning of oligo-peplides cDNA (or gene) was provided in this study. This paper is a basic work for expression of hCT cDNA.

Chemical Oxidative Synthesis and Conductivity of Poly(3,4-ethylenedioxythiophene)

[Objective] This paper was to introduce the chemical oxidative synthesis process, properties and test methods of 3,4-ethylenedioxythiophene(EDOT). [Method] The poor water solubility of EDOT was solved by using polyethylene glycol 20000(PEG) as the surfactant. The monomer was polymerized by chemical oxidative synthesis. The product was analyzed and verified by infrared spectrum, X-ray diffraction, ultraviolet-visible absorption spectra.[Result] The conductivity of the product was the best when the mass ratio of PEG and EDOT was 1∶1. The effects of oxidant dose and reaction time on the conductivity and yield of the product showed certain regularity. [Conclusion] EDOT could be polymerized by PEG and FeCl3, and the polymerization product was PEDOT.

A FACILE CHEMICAL SYNTHESIS of PENTADEOXYRIBONUCLEOTIDE d-TGGGT via PHOSPHOTRIESTER METHOD

In this paper,we report the chemical synthesis of oligonucleotide d-TGGGT using phosphotriester method.The protected pentamer d-MmtTGibGibGibT(=p-ClC6H_4-O(O)P)was deblocked by treatment with concentrated ammonium hydroxide and 80% acetic acid.The pure d-TGGGT obtained by chromatorgraphy on DEAE-Sephadex A-25 and Q-Sepharose FF could be hydrolyzed completely and confirmed by base ratio.