Ultrathin two-dimensional materials for photo- and electrocatalytic hydrogen evolution

Sustainable hydrogen production via photocatalytic, electrocatalytic, and synergetic photoelectrocatalytic processes has been regarded as an effective strategy to address both energy and environmental crises. Due to their unique structures and properties, emerging ultrathin two-dimensional (2D) materials can bring about promising opportunities to realize high-efficiency hydrogen evolution. This review presents a critical appraisal of advantages and advancements for ultrathin 2D materials in catalytic hydrogen evolution, with an emphasis on structure–activity relationship. Furthermore, strategies for tailoring the microstructure, electronic structure, and local atomic arrangement, so as to further boost the hydrogen evolution activity, are discussed. Finally, we also present the existing challenges and future research directions regarding this promising field.     

Channel-carrier mobility parameters for 4H SiC MOSFETs

In this paper, mobility parameters for enhancement-mode N-channel 4H SiC MOSFETs are extracted and implemented into 2-D device simulation program and SPICE circuit simulator. The experimental data were obtained from lateral N-channel 4H SiC MOSFETs with nitrided oxide–semiconductor interfaces, exhibiting normal mobility behavior. The presence of increasing interface-trap density (D_it) toward the edge of the conduction band is included during the 2-D device simulation. Using measured distribution of interface-trap density for simulation of the transfer characteristics leads to a good agreement with the experimental transfer characteristic.     

The influence of micronised particulates on the aerosolisation properties of pressurised metered dose inhalers

A fundamental study of the interactions between binary particulate formulations in HFA-based pressurised metered dose inhaler (pMDI) systems was undertaken. Differences in the surface energetics of lactose, mannitol and sibenadet hydrochloride were observed, which could be related to the degree of particle adhesion/cohesion, the sedimentation rate and the aerosolisation performance of formulations containing different mixtures of these components. In general, lactose was shown to be the most cohesive material and readily formed coarse aggregates with sibenadet hydrochloride which sedimented rapidly. This had the greatest effect on aerosolisation performance at high-lactose concentrations (and low-sibenadet hydrochloride concentrations), where heavily agglomerated particles were observed in collected samples of the emitted aerosol. A model, relating the adhesive and cohesive forces between the components in these systems has been proposed, which satisfactorily describes these phenomena. Furthermore, although the more energetic systems were shown to result in significantly decreased aerosol performance, the through-life performance was enhanced.     

Gluon matter plasma in the compact star core within a fluid QCD model

The structure of a compact star core filled with gluon matter plasma is investigated within the fluid-like QCD framework. The energy-momentum tensor, density and pressure relevant to gluonic plasma having the nature of a fluid bulk of gluon sea are derived within the model. It is shown that the model provides a new equation of state for the perfect fluid with only a single parameter of fluid distribution, ϕ(x). The results are applied to constructing the equation of state describing the gluonic plasma dominated compact star core. The equations of pressure and density distribution are solved analytically for a small compact star core radius. The phase transition of the plasma near the core surface is also discussed.     

Synthesis of polyblends from polypropylene and poly(R,S)‐β‐hydroxybutyrate,and their characterization

Blends of modified polypropylene (PP) with poly(R,S)‐β‐hydroxybutyrate (PHB) were prepared by casting polymer solutions, followed by compression molding into thin films. The modified polypropylene was obtained by oxidation with hydrogen peroxide. Oxidation of polypropylene produced new functional groups such as carbonyl and hydroxyl groups on the polymer chain, and a decrease in molecular weight and crystallinity of the polymers. Maximum crystallinity and mechanical properties of the polyblends were found with a PP/PHB ratio of 90/10 (w/w), and then decreased with increasing PHB content in the polyblends. Biodegradability of the polyblends was lower than that of bacterial and synthetic PHBs. Furthermore, an increase of PHB proportion in the polyblends resulted in highly non‐compatible polyblends. Hence only PHB and small parts of the polyblends were decomposed by microorganisms. Copyright © 2006 Society of Chemical Industry     

The Life Assessment of API 5L Grade B Geothermal Pipeline in Correlation with Corrosion under Insulation

The corrosion under insulation dominates metal loss in the case of API （American Petroleum Institute） 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and thermal cracking, did not serve a role as critical factors regarding to pipeline degradation during 26-years working operation. Actually, the header pipe diameter 32 inches and 40 inches require priority for inspection due to higher corrosion rate compared to smaller pipe diameters. By simulation method on similar heavy duty service condition in which the working pressure of 15 bars and temperature of 183 ℃, it was proved that corrosion rate will severely occur at corrosion rate more than 10 mpy in the pipe diameters of 20 inches, 32 inches and 40 inches. Further,condensation factor may contribute more significant in the case of corrosion under insulation. Practically, the metal loss at a half initial thickness requires priority for inspection, intensive maintenance or possible partial replacement.     

Agglomerate strength and dispersion of pharmaceutical powders

This study aims to investigate quantitatively the direct correlation between the mechanical strength of powder agglomerates and their dispersion into aerosols by a dry powder inhaler. Agglomerates of mannitol as a model drug-only formulation were prepared by a rolling method followed by exposure to various relative humidity (RH: 55%, 82%, 86% and 90%). The agglomerate strength was obtained from the compression of single agglomerates at a selected speed rate using an Instron testing machine. The dispersion performance (FPF_Loaded) was determined at flow rates of 60 and 100 l min^?1 using an Aeroliser^® coupled to a multistage liquid impinger. Results showed an inverse linear relationship between the agglomerate strength and the dispersion performance. An increase in strength from 3 to 183 kPa resulted in a significant drop (P<0.05) of 18% in the FPF_Loaded. Agglomerates containing ‘solid bridges’ exhibited higher strength (three to eight times) and lower FPF (5–15%, corresponding to 86% and 90% RH) compared to those containing ‘liquid bridges’. These results have provided direct information on the agglomerate strength and its quantitative relationship with powder aerosol performance.     

Utilization of Waste Materials for the Manufacturing of Better-Quality Wear and Corrosion-Resistant Steels

Metallurgical and Materials Transactions A - Decarburization of steels during heat treatment is a major problem for wear applications and for thin structural components as it often results in...     

Controllable proton and CO2 photoreduction over Cu2O with various morphologies

Simultaneous photocatalytic reduction of water to H₂ and CO₂ to CO was observed over Cu₂O photocatalyst under both full arc and visible light irradiation (>420 nm). It was found that the photocatalytic reduction preference shifts from H₂ (water splitting) to CO (CO₂ reduction) by controlling the exposed facets of Cu₂O. More interestingly, the low index facets of Cu₂O exhibit higher activity for CO₂ photoreduction than high index facets, which is different from the widely-reported in which the facets with high Miller indices would show higher photoactivity. Improved CO conversion yield could be further achieved by coupling the Cu₂O with RuO_x to form a heterojunction which slows down fast charge recombination and relatively stabilises the Cu₂O photocatalyst. The RuO_x amount was also optimised to maximise the junction's photoactivity.     

A high-sensitivity CMOS image sensor with gain-adaptive column amplifiers

A high-sensitivity CMOS image sensor using gain-adaptive column amplifiers is presented and tested. The use of high gain for the column amplifier reduces input-referred random noise, and when coupled with a column-based digital noise cancellation technique, also reduces fixed pattern noise. An experimental application of the circuit using 0.25-/spl mu/m CMOS technology with pinned photodiodes gave an rms random noise of 263 /spl mu/V and an rms fixed pattern noise of 50 /spl mu/V.