Metal Single-Atom Cocatalyst on Carbon Nitride for the Photocatalytic Hydrogen Evolution Reaction: Effects of Metal Species

Single-atom (SA) catalysts exhibit high activity in various reactions because there are no inactive internal atoms. Accordingly, SA cocatalysts are also an active research fields regarding photocatalytic hydrogen (H₂) evolution which can be generated by abundant water and sunlight. Herein, it is investigated whether 10 transition metal elements can work as an SA on graphitic carbon nitride (g-C₃N₄; i.e., gCN), a promising visible-light-driven photocatalyst. A method is established to prepare SA-loaded gCN at high loadings (weight of ≈3 wt.% for Cu, Ni, Pd, Pt, Rh, and Ru) by modulating the photoreduction power. Regarding Au and Ag, SAs are formed with difficulty without aggregation because of the low binding energy between gCN and the SA. An evaluation of the photocatalytic H₂-evolution activity of the prepared metal SA-loaded gCN reveals that Pd, Pt, and Rh SA-loaded gCN exhibits relatively high H₂-evolution efficiency per SA. Transient absorption spectroscopy and electrochemical measurements reveal the following: i) Pd SA-loaded gCN exhibits a particularly suitable electronic structure for proton adsorption and ii) therefore they exhibit the highest H₂-evolution efficiency per SA than other metal SA-loaded gCN. Finally, the 8.6 times higher H₂-evolution rate per active site of Pd SA is achieved than that of Pd-nanoparticles cocatalyst.     

Effect of wall friction on variation of formwork pressure over time in self-consolidating concrete

In order to accurately predict the varying of formwork pressure over time, it is necessary to consider various factors influencing the development of formwork pressure. A prediction model has been previously proposed, but that model has some limitations in that only intrinsic material characteristics are taken into account. Extrinsic effects such as wall friction, formwork flexibility, and external temperature are excluded in the model. This study focuses on the wall friction effect as one of the extrinsic factors. First, by incorporating the intrinsic model and friction stress acting on the interface, a method of calculating formwork pressure considering the wall friction effect is suggested. To find out how much friction stress is acting on the interface and how it varies over time, formwork pressure tests were performed with circular column formworks having three different diameters. In these columns, the vertical pressure at the bottom and the lateral pressures were measured. To calibrate parameters of the intrinsic model for the same material as that used in the formwork pressure tests, additional tests were conducted with a specially designed apparatus that can exclude effects of extrinsic factors. From tests and analysis results, it was found that wall friction greatly affects the variation of formwork pressure over time. The newly suggested calculation method can give a good prediction of real formwork pressure.     

Bioavailability Studies and in vitro Profiling of the Selective Excitatory Amino Acid Transporter Subtype 1 (EAAT1) Inhibitor UCPH‐102

Although the selective excitatory amino acid transporter subtype 1 (EAAT1) inhibitor UCPH‐101 has become a standard pharmacological tool compound for in vitro and ex vivo studies in the EAAT research field, its inability to penetrate the blood–brain barrier makes it unsuitable for in vivo studies. In the present study, per os (p.o.) administration (40 mg kg^?1) of the closely related analogue UCPH‐102 in rats yielded respective plasma and brain concentrations of 10.5 and 6.67 μm after 1 h. Three analogue series were designed and synthesized to improve the bioavailability profile of UCPH‐102, but none displayed substantially improved properties in this respect. In vitro profiling of UCPH‐102 (10 μm ) at 51 central nervous system targets in radioligand binding assays strongly suggests that the compound is completely selective for EAAT1. Finally, in a rodent locomotor model, p.o. administration of UCPH‐102 (20 mg kg^?1) did not induce acute effects or any visible changes in behavior.     

Swelling behavior of polymeric membranes to metalworking fluids

In some working places, such as metal manufacturing or automotive services, mechanical hazards commonly occur along with chemical hazards, particularly metalworking fluids (MWFs). The presence of these chemicals could modify the properties of gloves made from polymeric materials and thus reduce their protective properties against chemical contamination (solvent, MWFs) and mechanical risks (puncture and cutting). This work focused on determining the swelling characteristics and the resistance of six polymeric membranes which were exposed to seven industrial MWFs. We found that the swelling tests can be used to classify the potential of coating polymers in descending order of their resistance to MWFs: nitrile, polyurethane > poly(vinyl chloride), neoprene > butyl, latex. The analysis by multiple linear regression showed, for the first time, that the density or the viscosity‐gravity constant of the fluid and Hansen's solubility parameters of the polymers have a significant impact on the swelling of polymer. For the first time, two new multiple regression models have been proposed, to predict the swelling phenomena of polymers under various MWFs with an accuracy of ≈80%. The effect of temperature on mechanical properties and morphology of material was also examined. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45717.     

Recovery and partial purification of thermophilic β-xylosidase derived from recombinant Bacillus megaterium MS941 by aqueous two-phase system

A polymer–salt-based aqueous two-phase system (ATPS) was developed for the effective extraction and purification of extracellular β-xylosidase from the fermentation broth of recombinant Bacillus megaterium MS941. The effect of molecular weight (MW) of polyethylene glycol (PEG), tie-line length (TLL), volume ratio (V_R), crude loading and pH on the recovery performance was evaluated. Under the optimal extraction conditions, β-xylosidase was successfully purified up to 23-fold with a recovery yield of 99% in the bottom salt-rich phase at PEG 4,000/potassium phosphate ATPS comprising TLL of 41.8, V_R of 2.3, crude loading (C_L) of 30% (w/w) at pH 6.     

Interfacial Properties of Extended-Surfactant-Based Microemulsions and Related Macroemulsions

Extended surfactants containing an intermediate-polarity spacer, such as polypropylene oxide, in between the hydrophilic head and the hydrocarbon tail are known to result in superior solubilization and low interfacial tension, though they exhibit slow kinetics. The present work seeks to evaluate both equilibrium and kinetic aspects of extended-surfactant-based micro- and macroemulsions. The interfacial morphology of the extended surfactant membrane, i.e., characteristic length (ξ) and interfacial rigidity (E _r) at optimum middle-phase microemulsion conditions, was characterized using the net-average curvature model. The results showed that extended surfactants resulted in a relatively rigid interfacial membrane compared with conventional surfactants having similar hydrocarbon chain length. In addition, both ξ and E _r parameters increased with the length of the polypropylene oxide spacer. Increasing E _r values correlated to the slow coalescence rates of extended surfactant emulsified systems. Two alternative approaches (the addition of combined linkers and co-surfactant) are shown to overcome the slow kinetics of coalescence while maintaining desirable high solubilization and low interfacial tension.     

Upgrading and dewatering of raw tropical peat by hydrothermal treatment

In this study, hydrothermal upgrading and dewatering of raw tropical peat derived from Pontianak, West Kalimantan-Indonesia was evaluated at temperatures ranging from 150 to 380 °C, a maximum final pressure of 25.1 MPa and a residence time of 30 min. The moisture content of the raw peat was approximately 90 wt.%. Raw peat was hydrothermally upgraded without the addition of water in the laboratory scale. The yield of the solid products was between 53.0 and 99.7 wt.% and the effective calorific value of hydrothermally dewatered peat was between 17,290 and 29,209 kJ/kg following hydrothermal upgrading. In addition, the oxygen content in the solid product was varied from 38.4 to 15.6 wt.% after upgrading, while the carbon content from 55.2 to 77.8 wt.%. The hydrothermally upgraded peat fuel product also had an equilibrium moisture content of 2.3 wt.% and a maximum equilibrium moisture content of 17.6 wt.%. Upgraded peat is characteristically resistant to moisture adsorption at high humidity, which makes it promising for fuel based combustion. The change in the carbon-functional groups and their properties, as determined by FTIR and ¹³C NMR, are discussed in terms of the hydrothermal upgrading and dewatering process.