Silica hollow sphere as mesoporous molecular sieve which had high various usability had been synthesized by the simple and inexpensive method from using a water/oil/water（W/O/W） emulsion *** silica hollow sphere as ...
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Silica hollow sphere as mesoporous molecular sieve which had high various usability had been synthesized by the simple and inexpensive method from using a water/oil/water（W/O/W） emulsion *** silica hollow sphere as the support of nickel catalyst was compared with a commercial porous silica for methane reforming reaction with carbon *** samples were characterized by N-adsorption and desorption,X-ray diffraction,H-temperature programmed reduction,Energy dispersive X-ray spectrometry,Transmission electron microscope,X-ray photoelectron spectroscopy and Thermal gravimetric *** catalytic performance of all catalysts was inquired at 750℃,atmospheric pressure and GHSV of 12500 ml·g·*** results showed that the metallic nickel supported on silica hollow sphere had smaller particle size and higher dispersion than the commercial porous ***,superior performance catalytic in methane reforming of the nickel catalyst was proposed based on the mesoporous structure in the hollow sphere,its easily passing of the reactants to spheres,particularly the amount of decreased carbon deposition.
Although various nanomaterials have been designed for biocatalysis, few of them can accelerate chemical reactions with high selectivity and stereocontrol, which remains them from being perfect alternatives to nature e...
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Although various nanomaterials have been designed for biocatalysis, few of them can accelerate chemical reactions with high selectivity and stereocontrol, which remains them from being perfect alternatives to nature enzymes. Herein, inspired by the natural enzymes, an enantioselective nanomaterial has been constructed, with gold nanoparticles (AuNPs) as active centers, chiral cysteine (Cys) as selectors for chiral recognition, and expanded mesoporous silica (EMSN) as a skeleton of the artificial enzyme. In the oxidation of chiral 3,4‐dihydroxy‐phenylalanine (DOPA), the nanozyme with d ‐Cys shows preference to l ‐DOPA while the artificial enzyme with l ‐Cys shows preference to d ‐DOPA. Subsequent calculation of apparent steady‐state kinetic parameters and activation energies together with molecular dynamics (MD) simulations showed that the different affinity precipitated by hydrogen bonding formation between chiral Cys and DOPA is the origin of chiral selectivity.
We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface‐functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil‐in‐w...
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We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface‐functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil‐in‐water emulsions, from which yolk–shell and dual‐shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li‐ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li‐ion anodes composed of 46 wt % of dual‐shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm −2 achieve an overall specific capacity higher than 600 mAh g −1 , which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si–C composites for Li‐ion batteries.
Correction for 'Molecular stacking dependent phosphorescence-fluorescence dual emission in a single luminophore for self-recoverable mechanoconversion of multicolor luminescence', Chem. Commun., 2016, DOI: .
Correction for 'Molecular stacking dependent phosphorescence-fluorescence dual emission in a single luminophore for self-recoverable mechanoconversion of multicolor luminescence', Chem. Commun., 2016, DOI: .
Retinitis Pigmentosa (RP) is a degenerative disease of the retina that leads to vision loss. Retinal prostheses are being developed in order to restore functional vision in patients suffering from RP. We conducted in-...
Retinitis Pigmentosa (RP) is a degenerative disease of the retina that leads to vision loss. Retinal prostheses are being developed in order to restore functional vision in patients suffering from RP. We conducted in-vivo experiments in order to identify strategies to efficiently stimulate the retina. We electrically stimulated the retina and measured electrically evoked potentials (EERs) from the superior colliculus of rats. We compared the strength of EERs when voltage-controlled and current-controlled pulses of varying pulse width and charge levels were applied to the retina. In addition to comparing EER strength, we evaluated improvement in power efficiency afforded by a high surface area platinum-iridium material. Voltage-controlled pulses were more efficient than current-controlled pulses when the pulses have a short duration (
This study is to investigate the main operating mechanism of zinc oxide layer of ZnO RRAM (Resistance Random Access Memory). This experiment prepared four types of ZnO RRAM under different thermal annealing temperatur...
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ISBN:
(纸本)9781509030729
This study is to investigate the main operating mechanism of zinc oxide layer of ZnO RRAM (Resistance Random Access Memory). This experiment prepared four types of ZnO RRAM under different thermal annealing temperatures, Keithley 4200 measurement system was used to measure the operating voltage and current under a high impedance state and a low resistance state into the dielectric layer transmission mechanism analysis. This study found that the operating mechanism of a zinc oxide layer under the low-resistance state is mainly ohm conduction state. However, the operating mechanism of a zinc oxide layer under the high-resistance state is Poole-Frenkel Emission.
The utilization of 5‐(hydroxymethyl)furfural (HMF) for the large‐scale production of essential chemicals has been largely limited by the formation of solid humin as a byproduct, which prevents the operation of stepw...
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The utilization of 5‐(hydroxymethyl)furfural (HMF) for the large‐scale production of essential chemicals has been largely limited by the formation of solid humin as a byproduct, which prevents the operation of stepwise batch‐type and continuous flow‐type processes. The reaction of HMF with 1,3‐propanediol produces an HMF acetal derivative that exhibits excellent thermal stability. Aerobic oxidation of the HMF acetal with a CeO 2 ‐supported Au catalyst and Na 2 CO 3 in water gives a 90–95 % yield of furan 2,5‐dicarboxylic acid, an increasingly important commodity chemical for the biorenewables industry, from concentrated solutions (10–20 wt %) without humin formation. The six‐membered acetal ring suppresses thermal decomposition and self‐polymerization of HMF in concentrated solutions. Kinetic studies supported by DFT calculations identify two crucial steps in the reaction mechanism, that is, the partial hydrolysis of the acetal into 5‐formyl‐2‐furan carboxylic acid involving OH − and Lewis acid sites on CeO 2 , and subsequent oxidative dehydrogenation of the in situ generated hemiacetal involving Au nanoparticles. These results represent a significant advance over the current state of the art, overcoming an inherent limitation of the oxidation of HMF to an important monomer for biopolymer production.
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