Photocurrent of TiO2 Photoelectrode Enhanced by Nafion Modification

Introduction Since Gratzel‘s group^[1-5] first fabricated the dye-sensitized solar cell (DSSC) by using mesoporous TiO2 electrodes in 1991, as a possible alternative to P-N junction inorganic silicon cells, DSSCs have attracted more and more attention[6-11] The photo-to-electricity conversion of DSSCs is achieved by means of ultrafast electronin jection into the conduction band of TiO2 from an photoexcited dye, subsequent dye regeneration and hole transportation to the counter electrode.     

Modification of polyethylene films by radiation grafting of glycidyl methacrylate and immobilization of β-cyclodextrin

Glycidyl methacrylate was grafted onto polyethylene films using a preirradiation method with γ rays. The effect of absorbed dose, monomer concentration, and reaction time on the degree of grafting was determined. The grafted samples were verified by FTIR-ATR spectroscopy. β-Cyclodextrin was immobilized onto polypropylene modified with glycidyl methacrylate, and the ability of the cavities of β-cyclodextrin to form inclusion complexes was demonstrated using the typically organic compound approach with m-toluic acid (3-MBA) as a probe.     

Surface Modification of Montmorillonites by Chlorosilanes

Montmorillonite was modified by chlorosilane derivatives (trimethylchlorosilane and tert-butyldimethylchlorosilane)based on the reaction between OH group and chlorosilane,Fourier-transformed infrared spectra(FTIR)confirmed that chlorosilanes did react with the OH groups of montmorillonite.The effect of reaction time and dispersing agents on the intercalation was studied by wide angle X-ray diffraction(WAXD) method.Further experiments proved that there is no reactive OH group on the surface of layers in the interlayer galleries of montmorillonite.The cation exchange capacity(CEC) of montmorillonites was measured.showing that after modification by chlorosilane derivatives,CEC values drastically decreased.The dispersibility measurements of montmorillonites were conducted.which showed that the dispersibility of modified montmorillonites both in H2O and toluene wer improved due to the decrease of attractions of particles and layers.     

Surface Modification of Nano-SiO_2 by Grafting PMMA/PBA

IntroductionThankstotheirsizesatnano level ,thenano particleshavesomenewandpreternaturalpropertiesdifferentfromnormalmaterials ,andtheycanbeappliedinmanyfieldssuchascatalysts,lightfiltration ,lightabsorbing ,medicine ,magneticmediumandnewmaterialsaswell.1,2Itisalsorecognizedasoneofthemostprosperousmateri alsinthe 2 1century .Nowadays ,scientistsandre searcherspaymoreattentiontopolymer nano inorganiccompounds,becausepolymeriseasytoprocess ,anditcanavoidtheoxidationandcoagulationofthenano parti …     

Kinetics of Inactivation of Aminoacylase I During Modification of Its Thiol Groups by DPDS and PCMB

The kinetics theory of the substrate reaction during modification of enzyme activity previously described by Tsou has been applied to a study on the kinetics of the course of inactivation of aminoacylase I by DPDS and PCMB.From the results obtained we have found that the inactivation reaction of aminoacylase I by DPDS is noncomplexing inhibition,and PCMB reaction is complexing inhibition.The microscopic constants for the reaction of the inactivator with free enzyme and the enzyme-substrate complex were determined.     

Surface Modification of Polypropylene by Ethylene Plasma and Its Induced β-Form in Polypropylene

This study aims to investigate the chemical structure and morphology of plasmapolymers produced by deposition of ethylene on the surface of polypropylene. The deposition films(sediments) of ethylene plasma on the surface of polypropylene are nonuniform, and the characterization results indicate the existence of hydroxyl groups and aldehyde(or ketone) groups in the sediments. The sediment of ethylene plasma on the polypropylene surface could induce the growth of β-form crystals in the surface layer of polypropylene.     

Modification of Nano-alumina Surface by Michael Addition Reaction

With recent interest in polymer-based nanocomposites, nano-alumina has receivedconsiderable attention because of their high hardness, high strength and good wearresistance. Improvements in mechanical, tribological, conductive and barrier propertiesof some…     

Surface Modification of Nano－SiO2 by Grafting PMMA／PBA

The surface of nano-SiO2 was modified by being encapsulated with hydroxy-propyl-methyl cellulose (HPMC), and then co-grafted with acrylates. The grafting conditions, such as pH of the medium, and initiator concentration have been studied. The modified nano-SiO2 particles were characterized by TEM, DSC and FT-IR spectra. TEM images show that the surface of the nano-particles has been successfully modified by a thick layer of film-like polymer in this way. The DSC results show that the decomposition temperature of modified nano-particles of SIO2 is 90 ℃ higher than that of grafted-on polymer. According to the FT-IR spectra, It is convinced that poly-methyl methacrylate ( PMMA ) and poly-acrylic butyl-ester ( PBA ) were co-grafted onto the surface of nano-SiO2.     

A Novel Method for Modification of SMPU by Micro-phase

A novel method of controlling the shape memory properties of shape memory polyurethane （SMPU） by addition of micro-phase separation promoters including 1-octadecanol （ODO） and liquid paraffin （LP） is reported. The results indicate that the strain recovery temperature and the strain modulus rate （Eg/Er） were increased significantly with addition of small amount of micro-phase separation promoters. Thus it can increase the shape memory fixity rate and other shape memory behaviors of SMPU.     

Modification of lymphocyte DNA synthesis by α1-antitrypsin

Purified human α1-antitrypsin (α1-AT) was shown to inhibit ³H-thymidine incorporation into mouse or human lymphocytes stimulated by various mitogens or by allogeneic cells. In the mouse, both B- and T-cell responses were affected. In the human, proliferative responses of peripheral blood lymphocytes, thymocytes and T-enriched tonsillar lymphocytes to phytohaemagglutinin were inhibited as well as that of tonsillar lymphocytes to Salmonella typhi-murium lipopolysaccharide. Spontaneous ³H-thymidine incorporation was moderately and inconstantly decreased, without evidence of altered cell viability. The inhibitory effect of α1-AT appears to be related to its protease inhibitory capacity. These data bring further evidence for the role of proteolytic enzymes in the early events of lymphocyte activation, and support the hypothesis that serum inhibitors of proteases may contribute to the modulation of the immune response.     

Efficient synthesis of β-enaminones and β-enaminoesters catalyzed by gold (I)/silver (I) under solvent-free conditions

An efficient method for the synthesis of β-enaminones and β-enaminoesters using a combination of [(PPh(3))AuCl]/AgOTf as catalyst has been developed. The reaction between 1,3-dicarbonyl compounds and primary amines was carried out under solvent-free conditions with low catalyst loading in good to excellent yields at room temperature.     

Enhancement of H2 Sensing Properties of In2O3-based Gas Sensor by Chemical Modification with SiO2

The sensitivity and selectivity to H2 of a new In203-based gas sensor were improved significantly by surface chemical modification. A dense layer of SiO2 near the surface of the porous In2O3 bead was formed by chemical vapor deposition (CVD) of diethoxydimethysilane (DEMS). The dense layer functioned as a molecular sieve, thereby the diffusion of gases with large molecular diameters, except for 1-12, was effectively controlled, resulting in a prominent selectivity and high sensitivity for H2. The working mechanism of the sensor was also presented.     

Synthesis of Azaphenanthrene Derivatives by Condensation of 2-Methyleneaminonaphthalene with Cyclic β-Diketones

2-Methyleneaminonaphthalene smoothly reacts with cyclic -diketones to afford azaphenanthrene derivatives in high yield. The dihydropyridine ring in the products can be oxidized to pyridine ring. The oxidation products, unlike their precursors and analogs having an aryl substituent in the -position with respect to the nitrogen atom, react with hydroxylamine at the carbonyl group to give the corresponding oximes and in some cases undergo Knoevenagel condensation with malononitrile. Hydrolysis of the condensation product yields the respective diamide.     

Epoxidation of olefins by β-bromoalkoxydimethylsulfonium ylides

Olefins can be converted to their respective epoxides in a one-pot procedure by dissolving the olefin in anhydrous DMSO, adding NBS to the reaction mixture to generate a β-bromoalkoxydimethylsulfonium ylide, and then adding DBU to the reaction mixture. A large variety of alkenes were successfully epoxidized with yields largely dependent on the structure of the alkene. Most importantly, the facial selectivity of this one-pot process is the opposite of that observed when using traditional epoxidizing reagents. Electron-poor alkenes are not epoxidized under these conditions.     

Syntheses of β-Mannopyranosedes by Enzymatic Approaches

Abstract

The transmannosylation activity of β-mannosidase from snail and β-galactosidase from Aspergillus oryzae was used for the synthesis of methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 1-hexyl, cyclohexyl, and 1-octyl β-D-mannopyranosides (3a-i), respectively. The regioisomeric specificities and wide substrate acceptance of this galactosidase are demonstrated. Thus, 4-nitrophenyl 4-O-(α-D-glucopyranosyl)-β-D-glucopyranoside (6), 4-nitrophenyl 2-O-(β-D-glucopyranosyl)-β-D-glucopyranoside (7), 4-nitrophenyl 2-deoxy-2N-acetyl-6-O-(2-deoxy-2-N-acetyl-β-D-glucopyranosyl)-β-D-glucopyranoside(8),4-nitropheny 13-O-(β-D-mannopyranosyl)-α-D-mannopyranoside (9), and 4-nitrophenyl 4-O-(β-D-mannopyranosyl)-β-D-mannopyranoside (10) were prepared by chemoenzymatic self-transfer reaction.     

Regulation of β-amylase activity by alkylresorcinols

The effects of two alkylresorcinols, namely, methylresorcinol (MR) and hexylresorcinol (HR), which are chemical analogues of the natural anabiosis factors of some bacteria, on the catalytic activity of β-amylase has been investigated. When water-soluble potato starch is used as a substrate, MR in a concentration ranging from 0.8 to 12.9 mmol/L raises the activity of β-amylase to 170%. HR at a concentration ranging from 0.05 to 0.35 mmol/L stimulates a weak increase in the activity of β-amylase to 115%. A further increase in the concentration (0.75 mmol/L) leads to inhibition by 50%. The interaction of MR with β-amylase allows one to increase the general yield of the hydrolysis products of potato and malt starch by 1.5 to 1.6 times, to enhance the rate of hydrolysis by 4 to 5 times, and to extend the temperature and pH ranges of catalysis. Non-competitive activation in the presence of MR and non-competitive inhibition in the presence of HR are observed upon determining the kinetic parameters of the starch hydrolysis by β-amylase modified with alkylresorcinols.     

Enhanced Photocatalytic Efficiency of TiO2 by Combining the Modification of Ag Nanoparticles with the Application of Anodic Bias

Ag-TiO2/TTO film electrode was used as photoanode to investigate the feasibility of a hybrid technology of Ag nanoparticles combined with the application of anodic bias.The results showed that the deposited Ag and applied anodic bias have an apparent additive effect.     

Synthesis of fluoroalkyl-containing β-hydroxyketones by reduction of the corresponding β-diketone derivatives

The rcgioselective synthesis of fluoroalkyl-containing P-hydroxyketones by the reduction of the salts of the corresponding -diketones with LiAlH₄ was proposed. This is the sole method for the synthesis of -hydroxyketones with two fluoroalkyl substituents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1493–1495, June, 1996.     

Concentration determination of I2 and I− formed by thermal and radiolytic decomposition of NaIO3

Journal of Radioanalytical and Nuclear Chemistry - As a part of the evaluation of radioactive iodine behavior under the severe accident condition of nuclear power plant, we measured the...     

Synthesis of β-Lactams by Convenient Annelation of Imines

2-Acyl-3-oxo-4,5-benzo-1,2-thiazoline 1,1-dioxide (3) provides good yield routes to monocyclic 3-lactams (6) and tricyclic β-lactams (7) from a variety of imines (4) and 1-substituted-3,4-dihydroisoquinolines (5).