Investigation of CO and formaldehyde oxidation over mesoporous Ag/Co3O4 catalysts

CO and formaldehyde(HCHO)oxidation reactions were investigated over mesoporous Ag/Co3O4 catalysts prepared by one-pot(OP)and impregnation(IM)methods.It was found that the one-pot method was superior to the impregnation method for synthesizing Ag/Co3O4 catalysts with high activity for both reactions.It was also found that the catalytic behavior of mesoporous Co3O4 and Ag/Co3O4 catalysts for the both reactions was different.And the addition of silver on mesoporous Co3O4 did not always enhance the catalytic activity of final catalyst for CO oxidation at room temperature(20 C),but could significantly improve the catalytic activity of final catalyst for HCHO oxidation at low temperature(90 C).The high surface area,uniform pore structure and the pretty good dispersion degree of the silver particle should be responsible for the excellent low-temperature CO oxidation activity.However,for HCHO oxidation,the addition of silver played an important role in the activity enhancement.And the silver particle size and the reducibility of Co3O4 should be indispensable for the high activity of HCHO oxidation at low temperature.     

Production of 89Sr-doped CdSe QDs@PAMAM as the radioanalytical-fluorescent indicator of renal injury and the preliminary application in diabetic nephropathy model

Journal of Radioanalytical and Nuclear Chemistry - An indicator with double tracers has been developed so as to improve the accuracy and stability of quantitative analysis of renal injury. The...     

Poly(2-hydroxyethyl acrylate) hydrogels containing hyper-branched poly(amidoamine) for sustained drug release

Hydrogels containing hyper-branched poly(amidoamine) (hb-PAMAM) microenvironments were suggested for the sustained release of ionizable drugs. For this purpose, a series of poly(2-hydroxyethyl acrylate) (PHEA) hydrogels containing hb-PAMAM (PHEA-hb-PAMAM) were prepared by copolymerization of 2-hydroxyethyl acrylate with acryl-terminated hb-PAMAM. The hb-PAMAM was synthesized by the Michael addition reaction of triacryloylhexahydro-1,3,5-triazine (TT) and piperzaine (PZ). By using nonionic Tegafur and ionizable salicylic acid (SA) as model drugs, the release mechanisms of drugs from PHEA-hb-PAMAM hydrogels were investigated. Compared with the release kinetic of Tegafur, the release rate of SA from the hydrogels was evidently slowed down. Moreover, the release rate of SA can be modulated by the addition of salt. This can be attributed to the ionic interaction of SA with hb-PAMAM microenvironments. By analyzing the release kinetics of SA from the hydrogels, it was found that the release of SA followed non-Fickian diffusion.     

Ignition and burning behaviors of automobile oil in engine compartment

Accidental leakage of automobile oils is of great inclination to initiate pool fires in engine compartment, with threats to induce the flashover of other components and flame penetration into the passenger compartment. This paper presents experimental results of the ignition and burning behaviors of a kind of automobile oils (automatic transmission oil) using a cone calorimeter. Measurements of oil temperature, ignition time, mass loss and heat release rate are performed at different external heat fluxes and initial fuel depths. The comparison between experimental and numerical oil temperature evolutions shows that the variations of the ignition time at different experimental conditions depend on the heat dissipation process inside the liquid phase. The steady mass burning rate is nearly independent of initial fuel depth and has a linear relation with external heat fluxes. In addition, the results indicate an increase in peak heat release rate by a large margin initially, followed by a relatively small margin under thicker initial fuel depths, while its variations are proportional to external heat fluxes. Correlations are also developed to determine the peak heat release rate as a function of the initial fuel depth.

     

Growth and spectral properties of Yb:Ca0.28Ba0.72Nb2O6 disordered crystal

The growth, XRD patterns, spectral properties, and fluorescence decays of Yb:Ca_0.28Ba_0.72Nb₂O₆ (Yb:CBN) with doping concentration of 1 at.% and 5 at.% were studied. The peak absorption cross-section and the emission cross-section were calculated. Larger Stark splitting of Yb:CBN offers the prospect of the quasi-four level laser operation.     

An Intrinsic Photothermal Liquid for Light Detection and Energy Storage

Photothermal materials (PTMs) have been intensively investigated in the fields of photothermal conversion. Superior to solid PTMs, liquid PTMs are leading the trends in satisfying the demands of high flexibility and easy recycling. Successful examples of liquid PTMs are mostly formulated by dispersing solid PTMs in solvents, but suffer from the problems of phase segregation and solvent pollution. In this work, a low-cost formulation is proposed, which involves an oxidative product of ethyl oleate by iodine. It is an intrinsic liquid PTM, preserving the fluidic nature as well as possessing considerable ability for photothermal conversion. In addition to understanding the mechanism of light absorption in the visible and even near infrared windows, two examples are presented to demonstrate the great potential of liquid PTMs in broad areas such as light sensing and energy storage.     

Octahedral Chiral‐at‐Metal Iridium Catalysts: Versatile Chiral Lewis Acids for Asymmetric Conjugate Additions

Octahedral iridium(III) complexes containing two bidentate cyclometalating 5‐tert‐butyl‐2‐phenylbenzoxazole ( IrO ) or 5‐tert‐butyl‐2‐phenylbenzothiazole ( IrS ) ligands in addition to two labile acetonitrile ligands are demonstrated to constitute a highly versatile class of asymmetric Lewis acid catalysts. These complexes feature the metal center as the exclusive source of chirality and serve as effective asymmetric catalysts (0.5–5.0 mol % catalyst loading) for a variety of reactions with α,β‐unsaturated carbonyl compounds, namely Friedel–Crafts alkylations (94–99 % ee), Michael additions with CH‐acidic compounds (81–97 % ee), and a variety of cycloadditions (92–99 % ee with high d.r.). Mechanistic investigations and crystal structures of an iridium‐coordinated substrates and iridium‐coordinated products are consistent with a mechanistic picture in which the α,β‐unsaturated carbonyl compounds are activated by two‐point binding (bidentate coordination) to the chiral Lewis acid.     

In Situ Synthesis and Characterization of Poly(aryleneethynylene)‐Grafted Reduced Graphene Oxide

Using highly soluble bromo‐functionalized reduced graphene oxide (RGBr) as a key graphene template for surface‐directing Sonogashira–Hagihara polymerization, a novel soluble poly(arylene‐ethynylene)‐grafted reduced graphene oxide, hereafter abbreviated as PAE‐g‐RGO, was prepared in situ. The entirely different electron distribution of LUMO and HOMO of PAE‐g‐RGO suggested the existence of a charge‐transfer (CT) state (PAE^.?–RGO^.+). The negative ΔG_CS value (?2.57 eV) indicates that the occurrence of the charge separation via ¹RGO* in o‐DCB is exothermic and favorable. Upon irradiation with 365 nm light, the light‐induced electron paramagnetic resonance (LEPR) spectrum of PAE‐g‐RGO showed a decrease in the spin‐state density owing to photoinduced intramolecular electron transfer events in this system. A sandwich‐type Al/PAE‐g‐RGO/ITO device showed representative bistable electrical switching behavior. The nonvolatile memory performance was attributed to the CT‐induced conductance changes, which was supported by molecular computation results and conductive atomic force microscopy (C‐AFM) images.