The S-D transition and high-pressure phase stability of transition metals

Abstract

The recent discovery of a solid-solid phase change in shock-compressed Mo and the theoretical interpretation suggest valence d-electron density as a major influence on structural stability. The relationship of this experimental result to the transition metal structures and alloy phase diagrams will be discussed. Specific predictions will be presented for the locations and slopes of transition metal and transition metal alloy phase boundaries.     

Enhanced ethanol sensing properties of WO3 modified TiO2 nanorods

Pristine and WO₃ decorated TiO₂ nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO₂ NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO₂ NRs and thermally oxidised to obtain WO₃ nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO₂ NRs with WO₃.     

Phenolic compounds,essential oil composition,and antioxidant activity of Angelica purpurascens (Avé-Lall.) Gill

In this study, methanol extracts (MEs) and essential oil (EO) of Angelica purpurascens (Avé-Lall.) Gill obtained from different parts (root, stem, leaf, and seed) were evaluated in terms of antioxidant activity, total phenolics, compositions of phenolic compound, and essential oil with the methods of 2,2-azino-bis(3ethylbenzo-thiazoline-6-sulfonic acid (ABTS•⁺), 2,2-diphenyl-1-picrylhydrazil (DPPH•) radical scavenging activities, and ferric reducing/antioxidant power (FRAP), the Folin–Ciocalteu, liquid chromatography−tandem mass spectrometry (LC−MS/MS), and gas chromatography-mass spectrometry (GC−MS), respectively. The root extract of A. purpurascens exhibited the highest ABTS•⁺, DPPH•, and FRAP activities (IC₅₀: 0.05 ± 0.0001 mg/mL, IC₅₀: 0.06 ± 0.002 mg/mL, 821.04 ± 15.96 µM TEAC (Trolox equivalent antioxidant capacity), respectively). Moreover, EO of A. purpurascens root displayed DPPH• scavenging activity (IC₅₀: 2.95 ± 0.084 mg/mL). The root extract had the highest total phenolic content (438.75 ± 16.39 GAE (gallic acid equivalent), µg/mL)). Twenty compounds were identified by LC−MS/MS. The most abundant phenolics were ferulic acid (244.39 ± 15.64 μg/g extract), benzoic acid (138.18 ± 8.84 μg/g extract), oleuropein (78.04 ± 4.99 μg/g extract), and rutin (31.21 ± 2.00 μg/g extract) in seed, stem, root, and leaf extracts, respectively. According to the GC−MS analysis, the major components were determined as α-bisabolol (22.93%), cubebol (14.39%), α-pinene (11.63%), and α-limonene (9.41%) among 29 compounds. Consequently, the MEs and EO of A. purpurascens can be used as a natural antioxidant source.     

Microdetermination of carbon,hydrogen, nitrogen and oxygen in petroleum compounds with an automatic elemental analyzer

Summary The Perkin-Elmer Elemental Analyzer has been evaluated for the analysis of carbon, hydrogen, nitrogen and oxygen in typical petroleum samples. Comparison of the Elemental Analyzer results were made with carbon and hydrogen analyses by the Pregl method, oxygen by the Unterzaucher method, and nitrogen results from the automated micro Dumas Analyzer. The results obtained by the automated method were found comparable to those obtained by conventional methods. The automated method was found useful for the analysis of nitrogen in petroleum samples ranging from 0.05 to 0.1% N, a borderline level that presents difficulty for conventional methods. Samples of transformer oil containing known amounts of added phenol were analyzed for oxygen at the 0.2 to 1.0% O level.

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Zusammenfassung Der Verbrennungsautomat von Perkin-Elmer wurde für die Bestimmung von C, H, N und O in bestimmten Erdölprodukten verwendet und die Ergebnisse mit jenen des Preglschen Verfahrens, der Methode nachUnterzaucher bzw. mit den Resultaten der automatischen Dumas-Bestimmung verglichen. Die erhaltenen Werte sind mit denen konventioneller Methoden durchaus vergleichbar. Das automatische Verfahren ist für die Bestimmung des Stickstoffs in Erdölproben mit 0,05 bis 0,1% N gut geeignet, eine Größenordnung, die bei konventionellen Verfahren Schwierigkeiten bietet. Proben von Transformatorenöl, die bekannte Mengen Phenol enthielten, wurden auf ihren Sauerstoffgehalt analysiert, der zwischen 0,2 und 1,0% lag.

     

Modeling,Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices

An integrated cell for the solar‐driven splitting of water consists of multiple functional components and couples various photoelectrochemical (PEC) processes at different length and time scales. The overall solar‐to‐hydrogen (STH) conversion efficiency of such a system depends on the performance and materials properties of the individual components as well as on the component integration, overall device architecture, and system operating conditions. This Review focuses on the modeling‐ and simulation‐guided development and implementation of solar‐driven water‐splitting prototypes from a holistic viewpoint that explores the various interplays between the components. The underlying physics and interactions at the cell level is are reviewed and discussed, followed by an overview of the use of the cell model to provide target properties of materials and guide the design of a range of traditional and unique device architectures.