锌-三氧化二铬复合镀层的特性

采用由氧化锌12g/L、氢氧化钠94 g/L、2-氨基-3-羧基吡啶4.2 g/L、四乙烯五胺17g/L、三乙醇胺2g/L、专利表面活性剂0.5 g/L及碳三氧化二铬(粒径2μm)0～ 11 g/L组成的镀液,于温度50℃、pH 6.5和电流密度4A/dm2的条件下,在低碳钢上电镀Zn-Cr2O3复合镀层.其显微硬度采...     

Electrochemical oxidation of boron containing compounds on titanium carbide and its implications to direct fuel cells

Electrochemical oxidation of sodium borohydride (NaBH₄) and ammonia borane (NH₃BH₃) (AB) have been studied on titanium carbide electrode. The oxidation is followed by using cyclic voltammetry, chronoamperometry and polarization measurements. A fuel cell with TiC as anode and 40 wt% Pt/C as cathode is constructed and the polarization behaviour is studied with NaBH₄ as anodic fuel and hydrogen peroxide as catholyte. A maximum power density of 65 mW cm⁻² at a load current density of 83 mA cm⁻² is obtained at 343 K in the case of borhydride-based fuel cell and a value of 85 mW cm⁻² at 105 mA cm⁻² is obtained in the case of AB-based fuel cell at 353 K.     

β-Cyclodextrin-Mediated Removal of Soy Phospholipids from the Air–Water Interface

Binding of soy phosphatidylcholine (PC) and phosphatidylinositol (PI) with β-cyclodextrin (βCD) was studied using a spread monolayer technique at the air–water interface. First, surface pressure (π) versus surface concentration (Γ) isotherms of both PC and PI were characterized by forming spread monolayers on an aqueous subphase. PC and PI monolayers reached saturation at Γ of 1.98 and 3.24 μmol/m², respectively, at 25 °C. Subsequently, desorption of PC or PI from the spread monolayer in the presence of 2–14 mM βCD in the subphase was studied by measuring changes in π of monolayer. This desorption was indicative of a complex formation between βCD and PC or PI. The amount of PC or PI bound to βCD was determined by converting the net change in π to Γ by using π–Γ isotherms. From the saturated monolayers at the air water-interface, approximately 30% of PC and 50% of PI could be removed by 14 mM βCD. It was calculated that the free energy change required to transfer a PL from the monolayer at air–water interface to the aqueous phase in presence of βCD was decreased by 6–7 kcal/mol. Hydrolysis of PC in the monolayer by phospholipase A₂ (PLA₂) improved extraction efficiency of βCD. By incorporating 2.29 μM PLA₂ and 10 mM βCD in subphase, up to 80% of PC monolayer could be desorbed from the air–water interface. These results are discussed in terms of the potential use of βCD to remove PLs bound to soy protein.     

Inverted emulsion polymerization route to polyaniline‐3D nanofiber network using sulfonated‐p‐cresol as novel dopant

Sulfonated‐p‐cresol (SPC) was used as novel dopant for the first time in the synthesis of polyaniline in 3D nanofiber networks (PANI‐3D). Polyaniline in 3D nanofiber network was prepared using organic solvent soluble benzoyl peroxide as oxidizing agent in presence of SPC and sodium lauryl sulfate (SLS) surfactant via inverted emulsion polymerization pathway. The influence of synthesis conditions such as the concentration of the reactants, stirring/static condition, and temperature etc., on the properties and formation of polyaniline nanofiber network were investigated. Polyaniline in 3D nanofiber network with 40–160 nm (diameter), high yield (134 wt % with respect to aniline used), and reasonably good conductivity (0.1 S/cm) was obtained in 24 h time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of nonprotein polymers on water‐uptake properties of fish protein‐based hydrogel

The effects of nonprotein polymers on the water‐swelling properties of fish protein‐based hydrogel were studied. Inclusion of carboxymethyl cellulose (CMC), poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), or guar gum at a 2.5% (w/w) level in an 80% ethylenediaminetetraacetic dianhydide (EDTAD)‐modified fish protein hydrogel (10% monomer concentration) significantly decreased the extent of water uptake of the hydrogel. Among these polymers, PVA exhibited the greatest inhibitory effect. The inhibitory effect of these polymers on the water uptake of fish protein hydrogel was apparently due to the thermodynamic incompatibility of these polymers with the fish protein gel network and the consequent effect on the extent of relaxation of the crosslinked polypeptide network. In contrast, inclusion of 60% EDTAD‐modified soy protein up to a level of 40% of the total protein in the gel did not affect the extent of the equilibrium water uptake of the gel. At higher levels, however, soy protein also decreased the amount of water uptake by the gel. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 45–51, 2002     

Proteomics analysis of carbon-starved Mycobacterium smegmatis: induction of Dps-like protein

Mycobacterium tuberculosis is a globally successful pathogen,infecting more than one third of total world's population. Thesebacteria have the remarkable ability to persist in the hostfor long periods of time unrecognized by the immune system andthen to re-emerge later in life causing the disease. The physiologyof such persistent or dormant bacilli is not very well characterized.Some evidence suggests that the dormant bacilli survive in anutrient-deprived state that is similar to the stationary phaseof the bacteria with respect to gene expression and physiology.Under this assumption we have studied the survival of Mycobacteriumsmegmatis in carbon starvation conditions as a model for mycobacterialpersistence. M.smegmatis, being a fast-growing strain, servesas a good model to study starvation responses. Using the two-dimensionalelectrophoresis-based proteomics approach, we identified a proteinwhich was found to be expressed preferentially under starvationconditions. This protein is homologous to a family of proteinscalled Dps (DNA binding Protein from Starved cells) that areknown to protect DNA under various kinds of environmental stressesand its existence has, so far, not been reported in mycobacteria.Upon expression and purification of this protein, we observedthat it has non-specific DNA-binding ability. Formation of acage-like dodecamer structure is a characteristic feature ofDps. Using comparative modelling we were able to show that Dpsfrom M.smegmatis could form a dodecamer structure similar tothe crystal structure of Dps from Escherichia coli.     

Cyclic voltammetric study of zinc and zinc oxide electrodes in 5.3 M KOH

The behaviour of zinc and zinc oxide in 5.3 M KOH in the presence of alkaline earth oxides, SnO, Ni(OH)₂ and Co(OH)₂ was examined by cyclic voltammetry. The influence of the alkaline earth oxides was compared with additives of established effects (Bi₂O₃, LiOH, Na₂CO₃ and CdO). The alkaline earth oxide each exhibits a distinct behaviour towards zincate. Whereas, a single process of interaction with zincate was shown by CaO; two modes of reaction were obtained with SrO and BaO. Solid solution formation was noticed with BeO and MgO. The other additives forming solid solution with ZnO were CdO, SnO. The ionic sizes of Ni(OH)₂ and Co(OH)₂ allow solid solution formation with Zn(OH)₂. Both Bi₂O₃ and Na₂CO₃ enter into complexation with zincate. LiOH forms two distinct zincates, of which one is an oxo zincate leaching the `hydroxyl' functionality. Cyclic voltammetry revealed the deposition of the oxide/hydroxide additives as metal prior to the onset of zinc deposition and the potential range for this additive metal deposition is almost the same for different additives (SnO, CdO, Ni(OH)₂). The beneficial action of these additives to zinc alkaline cells is associated with a substrate effect. The implication of this electrocatalytic deposition of metals on a zinc oxide electrode is also discussed.     

The hydrothermal synthesis and structure of a one-dimensional Fe(II)molybdophosphate

A new one-dimensional Fe(II)molybdophosphate of the formula, [(C₁₀H₈N₂)H₂]₂[Fe₄^(II)Mo₁₂^(V)(HPO₄)₆(PO₄)₂(H₂O)₈(OH)₆O₂₄]·8H₂O, (1), has been synthesized by employing hydrothermal methods and characterized by single crystal X-ray diffraction. The structure consists of a network of MO₆ (M = Fe, Mo) octahedra and (H)PO₄ tetrahedra linked through their vertices. The connectivity between the polyhedral units gives rise to one-dimensional chains with eight-membered apertures. The hydrogen bonded interactions between the chains form pseudo two-dimensional layers. Extensive hydrogen bonding also exists between the amine molecule, 4,4^′-bipyridine, water molecule and framework oxygen atoms. Crystal data for 1: monoclinic, space group = P2₁ (no. 4), a=12.549(3) (Å), b=23.496(5) (Å), c=14.551(3) (Å), β=114.87(3)°, , and Z=2.     

Studies on Silicon Containing Nano-hybrid Epoxy Coatings for the Protection of Corrosion and Bio-Fouling on Mild Steel

An epoxy nano-composite coating was developed using amine functionalized nZnO (in the amount of 2.5 %, 5.0 % and 7.5 wt %) as the dispersed phase and a commercially available epoxy resin as the matrix phase. The structural features of these materials were ascertained by FT-IR spectral studies. The anti-corrosive properties of the epoxy/nZnO hybrid coatings in comparison with a virgin coating were investigated by a salt spray test and electrochemical impedance spectroscopy technique. The surface morphology determined by SEM, indicates that nZnO particles were dispersed homogenously through the epoxy polymer matrix. The results showed improved antifouling and anticorrosive properties for epoxy-nZnO hybrid coatings.