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Biogenic silica has been considered as a potential feedstock for producing a variety of silicon-containing products. A new synthesis pathway of tetraethyl orthosilicate from silica that is contained in rice hull ash has been recently proposed. Requiring only one-step processing, it is expected to offer advantages over conventional routes which are derived from silicon metal. This study aims to investigate the optimal synthesis conditions for which this new technology can sustainably replace the conventional method. Experiments employing different reaction conditions are performed to provide the necessary information for a conceptual process design and an economic and environmental viability evaluation. The results obtained by comparison with a selected conventional process show that, under the optimal synthesis conditions, the new process can decrease the production cost and markedly reduce the high greenhouse gas emissions. The competitiveness of the new process is further examined with a sensitivity analysis considering fluctuations in key feedstock and utility prices and alternative sources of electricity supplied to the conventional process. The new synthesis technology shows high potential as a sustainable alternative to the conventional one. [ABSTRACT FROM AUTHOR]

The inactivation of Escherichia coli and MS2 coliphage by Cu(II) is found to be significantly enhanced in the presence of hydroxylamine (HA). The addition of a small amount of HA (i.e., 5-20 μM) increased the inactivation efficacies of E. coli and MS2 coliphage by 5- to 100-fold, depending on the conditions. Dual effects were anticipated to enhance the biocidal activity of Cu(II) by the addition of HA, viz. (i) the accelerated reduction of Cu(II) into Cu(I) (a stronger biocide) and (ii) the production of reactive oxidants from the reaction of Cu(I) with dissolved oxygen (evidenced by the oxidative transformation of methanol into formaldehyde). Deaeration enhanced the inactivation of E. coli but slightly decreased the inactivation efficacy of MS2 coliphage. The addition of 10 μM hydrogen peroxide (H2O2) greatly enhanced the MS2 inactivation, whereas the same concentration of H2O2 did not significantly affect the inactivation efficacy of E. coli Observations collectively indicate that different biocidal actions lead to the inactivation of E. coli and MS2 coliphage. The toxicity of Cu(I) is dominantly responsible for the E. coli inactivation. However, for the MS2 coliphage inactivation, the oxidative damage induced by reactive oxidants is as important as the effect of Cu(I). [ABSTRACT FROM AUTHOR]

Substituting biomass for fossil-based feedstock is a potential scenario of chemical production. To achieve sustainable production, various issues must be considered, such as the constraints of limited biomass resources, feasibility of production technologies, and competitiveness of bio-based chemical products. In this study, we developed a new framework for the design and assessment of bio-based chemical processes. Both monetary and nonmonetary indicators including production cost, energy consumption, environmental impact, and safety hazards are considered. The framework was applied to the design and assessment of both existing and emerging new bio-based processes producing potential platform chemicals from bioethanol. On the basis of the design and assessment results, the suitable biomass feedstock, a sustainable synthesis process, a competitive bio-based product, and an appropriate production scenario can be selected. Using data available at the conceptual design stage, the framework can be applied to synthesize high-potential bio-based chemical processes for future sustainability development. [ABSTRACT FROM AUTHOR]

This study demonstrated Escherichia coli inactivation by cupric ion (Cu[II]), focusing on intracellular generation and consumption of reactive oxygen species (ROS) including superoxide and hydroxyl radials. In the presence of Cu(II), intracellular superoxide levels of E. coli decreased in a concentration-dependent manner, indicating that superoxide radical was used to reduce Cu(II) to Cu(I) in cells. The variation in the hydroxyl radical level by adding Cu(II) was negligible. Molecular oxygen and hydroxyl radical scavengers did not affect the inactivation efficacy of E. coli by Cu(II), excluding the possibility that hydroxyl radicals induced by the copper-mediated reduction of oxygen contributed to the microbiocidal action of Cu(II). However, the inactivation of E. coli by Cu(II) was considerably inhibited and accelerated by a Cu(I)-chelating agent and a Cu(II)-reducing agent, respectively. Our results suggest that the microbiocidal action of Cu(II) is attributable to the cytotoxicity of cellularly generated Cu(I), which does not appear to be associated with oxidative damage by Cu(I)-driven ROS. [ABSTRACT FROM AUTHOR]

Recently, various attempts have been made for light-to-fuels conversion, often with limited performance. Herein we report active and lasting three-factored hierarchical photocatalysts consisting of plasmon Au, ceria semiconductor, and graphene conductor for hydrogen production. The Au@CeO 2 /Gr 2.0 entity (graphene outer shell thickness of 2.0 nm) under visible-light irradiation exhibits a colossal achievement (8.0 μmol mg cat -1 h -1 ), which is 2.2- and 14.3-fold higher than those of binary Au@CeO 2 and free-standing CeO 2 species, outperforming the currently available catalysts. Yet, it delivers a high maximum quantum yield efficiency of 38.4% at an incident wavelength of 560 nm. These improvements are unambiguously attributed to three indispensable effects: (1) the plasmon resonant energy is light-excited and transferred to produce hot electrons localizing near the surface of Au@CeO 2 , where (2) the high-surface-area Gr conductive shell will capture them to direct hydrogen evolution reactions, and (3) the active graphene hybridized on the defect-rich surface of Au@CeO 2 favorably adsorbs hydrogen atoms, which all bring up thorough insight into the working of a ternary Au@CeO 2 /Gr catalyst system in terms of light-to-hydrogen conversion.

Rare-earth (RE) phosphates often appear as an accessory phase in igneous or metamorphic rocks; however, these rocks are composed of myriad chemical elements and nuclides that interfere with the qualitative or quantitative analyses of the RE phosphates over a range of concentrations in the absence of a pretreatment. In addition, the limit of each analytical methodology constrains the approach as well as the usefulness of the results in geoscience applications. Here, we report the specific mineral characterization of RE-containing ores from Yen Phu mine, Vietnam, using a range of state-of-the-art spectroscopic techniques in conjunction with microscopy: Mössbauer spectroscopy, infrared microspectroscopy, time-resolved laser-induced fluorescence spectroscopy (TRLFS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Because the distribution of each element in the deposit differs, such combinatorial works are necessary and could lead to more plausible answers to questions surrounding the point of origin of RE elements. The results of our Mössbauer spectroscopic analysis indicate that the three ores sampled at different locations all contain magnetite-like, hematite-like, and iron(III) salts other than hematite. In addition, we confirmed the presence of phosphate around the grain boundary in the magnetite-like mineral phase by infrared microspectroscopic analysis. The present analytical findings of trace amounts of europium(III) using TRLFS suggest that the europium ions generate identical luminescence spectra despite being embedded in three different matrices of iron minerals. This demonstration highlights the benefits of combinatorial spectroscopic analyses to gain insights into the effects of the environment of REs on their solid-state chemistry and shows the potential utility of TRLFS as a resource mining tool. Further applications of this approach in the analytical screening of rocks and minerals are feasible., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

The cupric ion mediated inactivation of Escherichia coli was enhanced by the presence of hydrogen peroxide (H2O2), with increasing inactivation efficacy observed in response to increasing concentrations of H2O2. The biocidal activity of the Cu(II)/H2O2 system is believed to result from the oxidative stress caused by reactive oxidants such as the hydroxyl radical ((•)OH), cupryl species (Cu(III)), and the superoxide radical (O2(•-)), which are produced via the catalytic decomposition of H2O2. In E. coli cells treated with Cu(II) and H2O2, the intracellular level of (•)OH and Cu(III) increased significantly, leading to complete disruption of cell membranes. On the basis of experimental observations made using an (•)OH scavenger, copper-chelating agents, and superoxide dismutase, it is concluded that Cu(III) is the predominant species responsible for the death of E. coli cells. It was also found that the production of Cu(III) was promoted by the reactions of copper with intracellular O2(•-). MS2 coliphage was found to be even more susceptible than E. coli to the oxidative stress induced by the Cu(II)/H2O2 system.

Selective potentiators of glutamate response at metabotropic glutamate receptor subtype 5 (mGluR5) have exciting potential for the development of novel treatment strategies for schizophrenia. A total of 1,382 compounds with positive allosteric modulation (PAM) of the mGluR5 glutamate response were identified through high-throughput screening (HTS) of a diverse library of 144,475 substances utilizing a functional assay measuring receptor-induced intracellular release of calcium. Primary hits were tested for concentration-dependent activity, and potency data (EC(50) values) were used for training artificial neural network (ANN) quantitative structure-activity relationship (QSAR) models that predict biological potency from the chemical structure. While all models were trained to predict EC(50), the quality of the models was assessed by using both continuous measures and binary classification. Numerical descriptors of chemical structure were used as input for the machine learning procedure and optimized in an iterative protocol. The ANN models achieved theoretical enrichment ratios of up to 38 for an independent data set not used in training the model. A database of approximately 450,000 commercially available drug-like compounds was targeted in a virtual screen. A set of 824 compounds was obtained for testing based on the highest predicted potency values. Biological testing found 28.2% (232/824) of these compounds with various activities at mGluR5 including 177 pure potentiators and 55 partial agonists. These results represent an enrichment factor of 23 for pure potentiation of the mGluR5 glutamate response and 30 for overall mGluR5 modulation activity when compared with those of the original mGluR5 experimental screening data (0.94% hit rate). The active compounds identified contained 72% close derivatives of previously identified PAMs as well as 28% nontrivial derivatives of known active compounds.