A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

Solid-supported metal catalysts have been widely used in industrial processes. The morphology of coated metal on the support is usually an important factor affecting the efficiency of the catalyst. In this study, a photocatalytic process is utilized to control the morphology of platinum particles deposited on titania (Degussa P-25). More specifically, the effect of pH on the morphology and the valence state of platinum nanoparticles was systemically investigated. It is found that, via a simple pH-controlled process, various states of platinum (Pt0, PtIIO, or PtIVO2) can be deposited onto the support directly at will. In this paper, the mechanism of morphology control and the key influencing factors at different pH regimes will be discussed. Followed by photodeposition, a H2 thermal treatment process was employed to convert the oxides into metal platinum with narrow size distribution and even coverage on the supporting titania. Various techniques such as transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive analysis of X-rays, and X-ray photoelectron spectroscopy were employed to characterize the prepared titania-supported platinum particles.

Supported metal catalysts have been used extensively in many current industrial processes. The morphology of coated metal on a support is usually an important factor affecting the efficiency of the catalyst. In this study, the investigation is focused on a photocatalytic process to coat silver clusters on titania (P-25 TiO2) with an emphasis on the morphology control of coated silver clusters. For the first time, the particle size and the deployment intervals of silver clusters are controlled with an innovative method that involves the in-situ formation of water-insoluble transitory species such as AgBr, AgCl, or Ag2O on the surface of titanium dioxide. Experimental results demonstrated that the transitory particles function as physical spacers, which temporarily occupy some of the active site on the titanium dioxide surface and act as reservoirs for Ag+ ions to keep the local Ag+ concentration on TiO2 extremely low. The silver clusters coated on titania are found to be stable in the spherical silver-3c syn crystalline form indicated by TEM, XRD, and XPS measurements.

Photocatalytic reduction of nitrite ions on silver-doped titania catalysts prepared by photodeposition and chemical reduction methods was investigated. With respect to the Ag/TiO 2 (C) catalyst prepared by the conventional chemical reduction method, the photoinduced synthesized Ag/TiO 2 (P) samples showed a more homogeneous silver morphology and narrow size distribution. For the first time, selective conversion of nitrite ions to nitrogen instead of ammonia was achieved on the Ag/TiO 2 (P) catalysts. A great influence of hole scavengers on the catalytic activity was observed and can be described as follows: H

Catalytic hydrogenation of nitrate (NO3 −) in water on Pd−Cu ensembles has been denoted as a promising denitridation method, but its hydrogenation selectivity remains challenging. In this study, the hydrogenation selectivity of nitrate on the Pd−Cu/TiO2 systems was discussed mainly concerning the size effect of Pd−Cu ensembles in a gas−liquid cocurrent flow system. Demonstrated by their TEM images, homogeneous morphologies as well as narrow size distributions of Pd−Cu ensembles on titania have been prepared by a facile photodeposition process, and the size of the ensembles was controlled and varied with the total metal loadings. The different XRD patterns and XPS spectra of Pd−Cu/TiO2 catalysts from their corresponding monometallic counterparts suggested the formation of Pd−Cu complex on the surface of TiO2. It is first indicated that the hydrogenation selectivity of nitrate generally depends on the size of active phase with critical size of approximately 3.5 nm, below which NO2 − becomes the predominant product instead of nitrogen. Ammonium production was increasing slowly throughout the reaction, but this can be efficiently restrained by bubbling CO2. The optimal catalytic activity and nitrogen selectivity of 99.9% and 98.3% respectively could be achieved on the Pd−Cu/TiO2 catalyst with average size of 4.22 nm under the modification of CO2 after approximately 30 min reduction. The catalytic activities of nitrite on several Pd−Cu bimetallic catalysts were examined to strongly depend on the size of active metal, as is well responsible for the observed distinct hydrogenation selectivity of nitrate.

A highly stereoselective [2,3]-sigmatropic rearrangement of sulfur ylide generated through Cu(I) carbene and allyl and propargyl sulfides by a double asymmetric induction approach that combines a chiral camphor sultam auxiliary and Cu(I) catalyst with chiral or achiral diimine ligands has been developed.

A new conceptional lithiophilic polymer-filler-reinforced gel polymer electrolyte was proposed and prepared to guide uniform Li-ion flux during the Li plating/stripping process.

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