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The deposition-precipitation and photoreduction methods were used to prepare a plasmonic photocatalyst Ag-AgI supported on mesoporous alumina (Ag-AgI/[Al.sub.2][O.sub.3]) and demonstrate its high and stable photocatalytic activity for the degradation and mineralization of toxic persistent organic pollutants. The high photosensitivity of noble metal NPs due to surface plasmon resonance could be useful for the development of new plasmonic visible-light-sensitive photocatalysts and photovoltaic fuel cells.

A single-step method is designed for rapid preparation of well-ordered organic-inorganic hybrid layered manganese oxide (LMO) nanocomposites under mild conditions. The results of the adsorption/exchange capacity tests on these hybrid materials have shown an adsorption/exchange efficiency of >99% by using acid phosphatase.

A new-generation Amber united-atom force field is developed for simulations involving highly demanding conformational sampling such as protein folding and protein-protein binding. The results have shown that the new united-atom force field is at least a factor of 200 more efficient than the Duan et al. all-atom force field for ab initio folding of the tested peptide.

Due to the excellent catalytic performance of manganese oxide (K-OMS-2) in a wide range of applications, incorporation of various dopants has been commonly applied for K-OMS-2 to acquire additional functionality or activities. However, the understanding of its substitution mechanism with respect to the catalytic performance of doped K-OMS-2 materials remains unclear. Here we present the structural distortion (from tetragonal to monoclinic cell) and morphological evolution in K-OMS-2 materials by doping hexavalent molybdenum. With a Mo-to-Mn ratio of 1:20 (R-1:20) in the preparation, the resultant monoclinic K-OMS-2 shows a small equidimensional particle size (∼15 nm), a high surface area of 213 m²g–1, and greatly improved catalytic activity toward CO oxidation with lower onset temperatures (40 °C) than that of pristine K-OMS-2 (above 130 °C). HR-TEM analyses reveal direct evidence of structural distortion on the cross-section of 2 × 2 tunnels with the absence of 4-fold rotation symmetry expected for a tetragonal cell, which are indexed using a monoclinic cell. Our results suggest that substitution of Mo6+ for Mn3+ (rather than Mn4+) coupled with the vacancy generation results in a distorted structure and unique morphology. The weakened Mn–O bonds and Mn vacancies associated with the structural distortion may be mainly responsible for the enhanced catalytic activity of monoclinic K-OMS-2 instead of dopant species. [ABSTRACT FROM AUTHOR]

Fe2O3 and/or Al2O3 were supported on mesoporous SBA-15 by wet impregnation and calcinations with AlCl3 and FeCl3 as the metal precursor and were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectra (FTIR) of adsorbed pyridine. Fe2O3/Al2O3@SBA-15 was found to be highly effective for the mineralization of ibuprofen aqueous solution with ozone. The characterization studies showed that Al-O-Si was formed by the substitution of Al3+ for the hydrogen of surface Si-OH groups, not only resulting in high dispersion of Al2O3 and Fe2O3 on SBA-15, but also inducing the greatest amount of surface Lewis acid sites. By studies of in situ attenuated total reflection FTIR (ATR-FTIR), in situ Raman, and electron spin resonance (ESR) spectra, the chemisorbed ozone was decomposed into surface atomic oxygen species at the Lewis acid sites of Al3+ while it was converted into surface adsorbed •OHads and O2•- radicals at the Lewis acid sites of Fe3+. The combination of both Lewis acid sites of iron and aluminum onto Fe2O3/Al2O3@SBA-15 enhanced the formation of •OHads and O2•- radicals, leading to highest reactivity. Mechanisms of catalytic ozonation were proposed for the tested catalysts on the basis of all the experimental information. [ABSTRACT FROM AUTHOR]

Two Ru(II) sensitizers TCR-1 and TCR-2 bearing four carboxy anchoring groups were prepared using 4,4',5,5'-tetraethoxycarbonyl-2,2'-bipyridine chelate and 4-(5-hexylthien-2-yl)-2-(3-trifluoromethyl-1H-pyrazol-5-yl)pyridine and 6-t-butyl-1-(3-trifluoromethyl-1H-pyrazol-5-yl)isoquinoline, respectively. Dissolution of these sensitizers in DMF solution afforded a light green solution up to 10-5 M, for which their color gradually turned red upon further dilution and deposition on the surface of a TiO2 photoanode due to the spontaneous deprotonation of carboxylic acid groups. These sensitizers were characterized using electrochemical means and structural analysis time-dependent density functional theory (TDDFT) simulation and were also subjected to actual device fabrication. The as-fabricated DSC devices showed overall efficiencies η = 6.16% and 6.23% versus their 4,4'-dicarboxy counterparts TFRS-2 and TFRS-52 with higher efficiencies of 7.57% and 8.09%, using electrolyte with 0.2 M LiI additive. Their inferior efficiencies are possibly caused by the combination of blue-shifted absorption on TiO2, inadequate dye loading, and the perpendicularly oriented central carboxy groups. [ABSTRACT FROM AUTHOR]

The occurrence and potential toxicity of synthetic musks in environmental media have aroused concerns for the impacts of these chemicals on ecosystems and human health. Here, we present the first method using ultra-performance liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry (UPLC-APPI-MS/MS) for analysis of the six most important synthetic musks. Analysis was performed on an API 3000 triple quadrupole equipped with a PhotoSpray APPI source. Two pairs of precursor/product ions are presented that are essential for confirmation. Chromatographic separation is completed in 7 min in the positive mode and 5.1 min in the negative mode. Furthermore, three dopant solutions (0.5% anisole in toluene, 0.5% 2,4-difluoroanisole (DFA) in bromobenzene, and 0.5% DFA in chlorobenzene) are compared in terms of sensitivity, linearity, precision, and accuracy. The best sensitivity is associated with 0.5% anisole in toluene as the dopant; all LODs are below 6 pg. The linear range is 5 to 500 ppb with fairly good precision and accuracy. This analytical method has also proven its applicability by analyzing real air samples. In summary, we present a fast, sensitive, and reliable UPLC-APPI-MS/MS method for six important synthetic musks; it can be readily applied to environmental studies. [ABSTRACT FROM AUTHOR]

The plasmon-induced photocatalytic inactivation of enteric pathogenic microorganisms in water using Ag-AgI/Al2O3 under visible-light irradiation was investigated. The catalyst was found to be highly effective at killing Shigella dysenteriae (S. dysenteriae), Escherichia coli (E. coli), and human rotavirus type 2 Wa (HRV-Wa). Its bactericidal efficiency was significantly enhanced by HCO3- and SO42- ions, which are common in water, while phosphate had a slightly positive effect on the disinfection. Meanwhile, more inactivation of E. coli was observed at neutral and alkaline pH than at acid pH in Ag-AgI/Al2O3 suspension. Furthermore, the effects of inorganic anions and pH on the transfer of plasmon-induced charges were investigated using cyclic voltammetry analyses. Two electron-transfer processes occurred, from bacteria to Ag nanoparticles (NPs) and from inorganic anions to Ag NPs to form anionic radicals. These inorganic anions including OH- in water not only enhanced electron transfer from plasmon-excited Ag NPs to AgI and from E. coli to Ag NPs, but their anionic radicals also increased bactericidal efficiency due to their absorbability by cells. The plasmon-induced electron holes (h+) on Ag NPs, O2∙-, and anionic radicals were involved in the reaction. The enhanced electron transfer is more crucial than the electrostatic force interaction of bacteria and catalyst for the plasmon-induced inactivation of bacteria using Ag-AgI/Al2O3. [ABSTRACT FROM AUTHOR]

A plasmonic photocatalyst Ag-AgI supported on mesoporous alumina (Ag-AgI/Al2O3) was prepared by deposition-precipitation and photoreduction methods. The catalyst showed high and stable photocatalytic activity for the degradation and mineralization of toxic persistent organic pollutants, as demonstrated with 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and trichiorophenol (TCP) under visible light or simulated solar light irradiation. On the basis of electron spin resonance, cyclic voltammetry analyses under a variety of experimental conditions, two electron transfer processes were verified from the excited Ag NPs to AgI and from 2-CP to the Ag NPs, and the main active species of O2·- and excited h+ on Ag NPs were involved in the photoreaction system of Ag-Agl/Al2O3. A plasmon-induced photocatalytic mechanism was proposed. Accordingly, the plasmon-induced electron transfer processes elucidated the photostability of Ag-Agl/Al2O3. This finding indicates that the high photosensitivity of noble metal NPs due to surface plasmon resonance could be applied toward the development of new plasmonic visible-light- sensitive photocatalysts and photovoltaic fuel cells. [ABSTRACT FROM AUTHOR]

The photodegradation of the widely used amine drugs including primary amine (mexiletine), secondary amine (propranolol, phenytoin), and tertiary amine (diphenhydramine, antipyrine) were investigated in the presence of nitrate and humic substances under simulated sunlight All of the amine drugs were photodegraded by nitrate due to the attackofhydroxyl radicals (˙OH). The bimolecular rate constants for the reaction between each amine drug and ˙OH ranged from (2.1 ± 0.2) × 109 to (8.7 ± 0.3) × 109 M-1 s-1. In contrast, only mexiletine, propranolol, and diphenhydramine were selectively photode-graded in the presence of humic substances (HS). Fulvic acid was a more efficient sensitizer than humic acid throughout The HS triplet states were verified to be main reactive species in the photochemical reaction. Furthermore, an electron transfer mechanism for the reaction with the HS triplet states was proposed on the basis of all information obtained under a series of experiments. The electron transfer from the nonbonding electrons on nitrogen (N-electrons) of the amine drugs to the excited ketone of the HS occurred. The availability of N-electrons and presence of hydrogen on carbon α of amine (α-hydrogen) were two key factors for the electron-transfer interaction. Moreover, the photoproducts were identified by GC-MS and the degradation pathways were proposed. The results strongly suggest the impact of humic substances on the photochemical fate of amine drugs in the natural waters. [ABSTRACT FROM AUTHOR]

Catalytic ozonation of five pharmaceutical compounds (PhACs)-phenazone, ibuprofen, diphenhydramine, phenytoin, and diclofenac sodium in alumina-supported manganese oxide (MnOx) suspension was carried out with a semicontinuous laboratory reactor. MnOx supported by mesoporous alumina (MnOx/MA) was highly effective in mineralizing the PhACs in aqueous solution. Fouriertransform infrared (FTIR) spectroscopy and in situ attenuated total reflection FTIR (ATR-FTIR) spectroscopy were used to examine the interaction of ozone with different catalysts under various conditions. The crucial active sites, surface oxide species at 1380 cm-1, were formed by the interaction of ozone with Lewis acid sites on the alumina surface. New surface hydroxyl groups at 2915 and 2845 cm-1 were produced by the interaction of the catalyst and ozone in aqueous suspension and became active sites in the presence of MnOx. The introduction of MnOx enhanced the formation and activation of surface hydroxyl groups, causing higher catalytic reactivity. On the basis of these findings, a reaction mechanism is proposed for the catalytic ozonation of PhACs in MnOx/MA suspension. [ABSTRACT FROM AUTHOR]

Optimization of the synthesis of nanosized silver particles by chemical reduction using formaldehyde in aqueous solution was carried out based on small-scale experimental data (with a 100 cc reaction mixture loaded in a 200 cc beaker and shaken in an isothermal shaker). Effects of the possible processing variables were achieved. In this study, the scale-up production (2 L or more of the reaction mixture) of nanosized silver particles is intended; however, for a scale-up system, the experiments generally require large and expensive resources. To obtain the optimal recipe and operating conditions using limited resources for a scale-up system, an algorithm for extending the identified model built from a small-scale system to a scale-up system was first developed through a numerical example. On the basis of the developed algorithm, 19 experiments were carried out in the scale-up system to achieve the objectives (minimum of the mean particle size of the silver colloid with or without the constraint of conversion of silver nitrate) of the synthesis of nanosized silver particles. With the modeling and optimization method proposed in this work, limited experiments were required, and most of the experiments can produce near on-specification products such that the off-specification products can be minimized. [ABSTRACT FROM AUTHOR]

Manganese oxide was supported on mesoporous zirconia (MnOx/ MZIW) by wet impregnation, drying, water washing, and calcinations with manganese acetate tetrahydrate as the metal precursor for the first time and was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier- transform infrared spectra (FTIR), temperature-programmed reduction (TPR), temperature-programmed oxygen desorption (O2-TPD), and UV-vis diffuse reflectance spectra (UV-vis DRS) measurements. The catalyst was found to be highly effective for the mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) aqueous solution with ozone. The characterization studies showed that nonstoichiometrically MnOx was highly dispersed on mesoporous zirconia by the strong interaction of the [Mn(H2O)6]2+ complex with surface hydroxyls of the support. Moreover, the multivalence oxidation states of MnOx enhanced the electron transfer, causing the higher catalytic reactivity. On the basis of all information obtained under different experimental conditions, MnOx/MZIW enhanced the mineralization of 2,4-D by the formation of ∙OH radicals resulting from the catalytic decomposition of ozone. [ABSTRACT FROM AUTHOR]

Fe0 was calcined in air at 200 °C and showed enhanced activity in three cycling runs for the degradation of acid red B (ARB) in the presence of H2O2 under UVA irradiation. Subsequently, the catalyst's activity was maintained effectively after 10 successive cycling experiments. Moreover, the catalyst was found to be highly effective for the degradation of nonbiodegradable azodyes ARB, reactive brilliant red X-3B, reactive red K-2G, cationic red X-GRL, and cationic blue X-GRL at neutral pH values. On the basis of characterization by X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectra, the surface layer of the catalyst was mainly composed of α-FeOOH and γ-Fe2O3, and the core was Fe0 (FeOxH2x-3/Fe0). FeOxH2x-3/Fe0was very easily recovered from the reaction system by magnetic separation. The degradation of azodyes came from the synergistic effect of the catalysis of galvanic cells and the oxidation of heterogeneous photo-Fenton reaction on the basis of all information obtained under different experimental conditions. By the total organic carbon and GC-MS analysis, the degradation process of ARB was shown to proceed with decolorization and naphthalene ring openings into CO2 and small organic acid. [ABSTRACT FROM AUTHOR]