Preparation and characterization of AgSt/AgCl composite grains

AgSt/AgCl composite grains were prepared by adding chloride ions to a mixed solvent in which silver stearate (AgSt) grains were dispersed under the condition of controlled pH value and characterized by SEM,XRD,UV and DSC.The results showed that AgSt/AgCl composite grains were composed of plate-like AgSt grains with small face-centered cubic AgCl particles formed on the surface of AgSt.UV spectra displayed a red shift of absorption for AgSt/AgCl relative to pure AgSt or AgCl.DSC showed a new thermal phase transition of AgSt/AgCl grains.     

Preparation and characterization of AgSt/AgC1 composite grains

AgSt/AgC1 composite gains were prepared by adding chloride ions to a mixed solvent in which silver stearate （AgSt） grains were dispersed under the condition of controlled pH value and characterized by SEM, XRD, UV and DSC. The results showed that AgSt/AgC1 composite grains were composed of plateqike AgSt grains with small face-centered cubic AgC1 particles formed on the surface of AgSt. UV spectra displayed a red shift of absorption for AgSt/AgC1 relative to pure AgSt or AgC1. DSC showed a new thermal phase transition of AgSt/AgC1 grains.     

Preparation and characterization of Fe_3O_4/Au composite particles

Colloid gold with different sizes has been widely used in immunoassay and nucleic acid detection mainly because of their properties for immobilization of biomolecules, such as antibodies and oligonucleo-tides, through chemical reactions via active group SH on the biomolecules. Magnetic particles modified with various chemical groups on their surface can not only exhibit good magnetic responsiveness to an external magnetic field but also immobilize biomolecules through these chemical groups. As…     

Preparation of γ-Al_2O_3 composite membrane and examination of membrane defects

A boehmite sol with a narrow particle size distribution and most probable diameter of 35 nm was prepared by peptization of boehmite suspension with HNO3 An unsupported γ-Al2O3 membrane made from the above sol possessed a narrow pore size distribution,with an average pore size of 4.8 nm and 320 m2/g specific surface area.A supported y-Al2O3 membrane produced by repeating dipping-drying-calcination procedure twice was proven to be defect-free by gas permeation measurements and SEM.     

Hydrogen sorption and hydrogen-induced phase separation in a nearly equiatomic NiZr amorphous alloy

The influence of hydrogen on some physical properties and on the micro-structure of a nearly equiatomic, melt-quenched NiZr amorphous alloy was investigated. Hydrogen absorption from the gas phase at 190 °C and 35–40 atm pressure was measured by weight as a function of the charging time. Considerable hydrogen absorption occurred only for charging times around 10 h and was completed within a few hours. The hydrogen content remained constant for a hydrogen-to-metal ratio of about one for prolonged charging. The room-temperature thermopower changed considerably upon hydriding and a local thermopower probe revealed that the activation time varies considerably along the ribbon length. It was found that, during further heat treatment in a hydrogen gas atmosphere after a hydrogen-to-metal ratio of approximately one was reached, the magnetic state of the amorphous NiZr samples changed progressively from paramagnetic to superparamagnetic. The density and size of the magnetic clusters, which were nickel-rich segregations induced by the hydriding process, were determined by magnetic and scanning transmission electron microscopic measurements. After desorbing hydrogen at elevated temperatures, magnetic measurements indicated the disappearance of the superparamagnetic clusters.     

Preparation and characterization of CoFe_2O_4/TiO_2 magnetic composite films

CoFe2O4/TiO2 magnetic composite films were prepared using the sol-gel method with tetrabutyltitanate and metallic chlorates as starting materials. The effects of heat treatment temperatures on micro- structures and on magnetic properties were studied. The microstructure and properties of the samples at different heat treatment temperatures were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, polarized microscopy and vibrating sample magnetometry. The results show that crystals of different substances grow up independently. Cobalt ferrite is evenly embedded into the titanium dioxide matrix in the prepared composite films. The magnetism of the composite films is enhanced with an increase of the heat temperature.     

Hydrogen and deuterium atoms in amorphous ZrNi alloys

The local environment of hydrogen and deuterium atoms dissolved in amorphous alloys with the composition ZrNi and Zr₂Ni was studied using neutron inelastic scattering and neutron diffraction techniques. The frequency distribution functions exhibit a broad peak at about 130 meV. Interatomic DNi and DZr correlations are observed in the radial distribution function curves at correlation lengths of 1.7 Å and 2.1 Å respectively for both alloy compositions. It is concluded that the majority of hydrogen and deuterium atoms in the amorphous alloys are trapped at holes in the tetrahedra which consist of three or four zirconium atoms. The maximum hydrogen content per metal atom can be explained by assuming a statistical configuration of the metal atoms.     

Preparation and characterization of AuPt alloy nanoparticle–multi-walled carbon nanotube–ionic liquid composite film for electrocatalytic oxidation of cysteine

Gold–platinum (AuPt) alloy particles were fabricated directly on multi-walled carbon nanotubes (MWNT)–ionic liquid (i.e., trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, [P_6,6,6,14][NTf₂]) composite coated glassy carbon electrode (GCE) by electrodeposition method. Scanning electron microscope image showed that they were well-dispersed nanocluster consisting of smaller nanoparticles, and their size was about 70 nm. X-ray diffraction experiment showed that they were single-phase alloy nanomaterial, and the calculated composition was consisting with that obtained by energy dispersive X-ray spectroscopy. The resulting modified electrode (i.e., AuPt–MWNT–[P_6,6,6,14][NTf₂]/GCE) presented high catalytic activity for the electrochemical oxidation of cysteine. The peak potential of cysteine shifted to 0.42 V (versus saturated calomel electrode) in 0.1 M H₂SO₄ and the peak current increased greatly in comparison with that on the corresponding Pt (or Au)–MWNT–[P_6,6,6,14][NTf₂]/GCE. Under the optimized conditions, the oxidation current of cysteine at 0.45 V was linear to its concentration in the range of 5.0 × 10⁻⁷ ∼ 4.0 × 10⁻⁵ M with a sensitivity of 43.8 mA M⁻¹.     

Preparation and characterization of composite membranes with Brønsted acidic ionic liquid

Poly-(vinyl alcohol) (PVA) proton-conducting composite membranes were prepared using succinic acid (SA) as a cross-linking agent and Brønsted acidic ionic liquid (BAIL) as a proton source. The incorporated BAILs resulted in a relatively high proton conductivity compared with PVA/SA membrane without BAILs. The proton conductivities of PVA/SA/BAIL composite membranes increased versus the BAIL content. In addition, the optimal resultant proton conductivity of PVA/SA/BAIL composite membrane under dry condition could reach 0.4 mS/cm at 140 °C, which was higher than that of PVA/sulfosuccinic acid (SSA) composite membrane (0.032 mS/cm), PVA/SSA/5-aminotetrazole membrane (0.022 mS/cm at 130 °C), and PVA/chlorosulfonic acid/glutaraldehyde membrane (0.0585 mS/cm at 90 °C) measured at the same condition. It was notable that the PVA/SA/BAIL composite membranes could reach high thermal stability up to 150 °C, which was higher than that of traditional PVA membranes (below 80 °C).     

Preparation and characterization of anticorrosion Ormosil sol–gel coatings for aluminum alloy

Organically modified silicate (Ormosil) coatings have been synthesized through the sol–gel method for corrosion protection of aluminum alloy. Silica-based unmodified coatings were also designed to investigate the effect of tetraethoxysilane (TEOS) content on the properties of the coatings. The surface morphology of the coatings was characterized by scanning electron microscopy. The corrosion resistance was evaluated by immersion test, electrochemical impedance spectroscopy and potentiodynamic polarization measurements. In addition, the surface potential differences of the coated samples were determined by scanning Kelvin probe. The results showed that a better corrosion resistance of unmodified coating was prepared by controlling the TEOS/EtOH/H₂O molar ratio of 0.109/1/1.52. Ormosil coatings provided excellent barrier properties and corrosion resistance in comparison with the unmodified sol–gel coatings. The Ormosil coating modified with triethoxyoctylsilane exhibited corrosion resistance properties superior to the other Ormosil coatings after exposure to 3.5 wt% NaCl solution for 10 days.     

Preparation and characterization of crosslinked chitosan-based nanofibers

Crosslinked chitosan-based nanofibers were successfully prepared via electrospinning technique with heat mediated chemical crosslinking followed.The structure,morphology and mechanical property of nanofibers were characterized by attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR),scanning electron microscopy(SEM),Instron machine,respec- tively.The results showed that,nanofibers exhibited a smooth surface and regular morphology,and tensile strength of nanofibers improved with increasing of triethylene glycol dimethacrylate(TEGDMA)content.     

Preparation and characterization of nitrogen-doped titanium dioxides

A type of high visible-light active titanium oxinitride(TiO2-xNx) powder was prepared by a simple proc-ess:the calcination of the hydrated titanium dioxide at the atmosphere of ammonia-argon using a tu-bular electric furnace at high temperatures. The hydrated titanium dioxide was synthesized as the precursor of TiO2-xNx using titanic acid as raw material,which came from sulfate technique of produc-ing titanium white. The effects of temperature and reaction time on the nitrogen content,grain size and crystal structure were studied. The visible-light activity and photocatalysis capability of the powder were also investigated.     

Preparation and characterization of cross-linked β-cyclodextrin polymer/Fe_3O_4 composite nanoparticles with core-shell structures

Cross-linkedβ-cyclodextrin polymer/Fe₃O₄ composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe₃O₄ nanoparticles inβ-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent.The morphology,structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy（TEM）,Fourier transform infrared（FTIR） spectrometry,X-ray diffraction（XRD） measurement,thermogravimetric analysis（TGA） and Vibrating sample magnetometry （VSM）,respectively.     

Preparation and characterization of perfluorosulfonic resin/titania hybrid transparent films

Preparation and characterization of perfluorosulfonic resin/titania organic-inorganic hybrid films were presented. The transparent hybrid films were prepared by hydrothermal treatment at low temperature of a mixed solution of tetrabutyl titanate and perfluorosulfonic resin with the help of acetylacetone. The characterization was carried out by SEM,XRD,FT-IR,UV-Vis and TGA. The results showed that the perfluorosulfonic resin/titania hybrid transparent films were composed of titania particles dispersed in the perfluorosulfonic resin matrix very well and the titania was of anatase phase. Its diameter de-creased with increasing weight ratio of titania to perfluorosulfonic resin.     

Mechanical and corrosion behavior of amorphous and crystalline electroless Ni–W–P coatings

Two types of electroless Ni–W–P coatings: nanocrystalline with low P and amorphous with higher P content are investigated. Scanning probe microscopy is applied to study their morphology. Textured nanocrystalline coatings consist of coarse pyramids built of nanometer thick lamellas. The surface morphology of amorphous coatings is much finer and uniform. Nanohardness of all coatings depends on W content. Microhardness is increasing during the heat treatment up to 350 °C due to nickel phosphide precipitation affected by tungsten also. The wear resistance of nanocrystalline Ni–W–P coatings is much higher than that of amorphous in spite of the similar tungsten content in both. Lower corrosion resistance of amorphous Ni–W–P coatings is found by weight loss method during long-term immersion in 5 % NaCl. Electrochemical tests by potentiodynamic polarization curves in two model corrosion media—solutions of 0.5 M H₂SO₄ and 5 % NaCl—are performed. The corrosion of bi-layered Ni–W–P/Ni–P and Ni–W–P/Ni–Cu–P deposits on mild steel is also investigated. The results prove that an electroless Ni–W–P coating on mild steel extremely improves its mechanical and corrosion behavior. It is demonstrated that in addition to deposit’s structure and composition, the distribution and chemical state of alloy ingredients are also responsible for its properties.     

Preparation, characterization, and catalysis of mecro-catalysts

Because catalysis by metals is a surface phenomenon, many technological catalysts contain small (typically nanometre-sired) supported metal particles with a large fraction of the atoms exposed. Many reactions, such as hydrocarbon hydrogenations, are structure-insensitive, proceeding at approximately the same rates on metal particles of various sizes provided that they are larger than 1 nm and show bulk-like metallic behavior. But the catalytic properties are not known when metal particles become so small that their sizes are indium clusters consisting of several indium atoms. Here the catalytic behavior of precisely defined clusters of just four and six indium atoms on solid supports is shown. It is found that the Ir4 and Ir6 clusters differ in catalytic activity both from each other and from metallic Ir particles.