UV-enhanced sacrificial layer stabilised graphene oxide hollow fibre membranes for nanofiltration

Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m(−2) h(−1) bar(−1) for water, and 0.14 to 7.5 L m(−2) h(−1) bar(−1) for acetone, with an unchanged low molecular weight cut off (~250 Da)

Transition metal carbene complexes and platinum-catalyzed substitution of metal carbonyls

Transition metal carbene complexes have attracted a great deal of attention not only as a novel class of compounds but also as intermediates for organic synthesis. A series of transition metal cyclic dioxy and aminooxy carbene complexes were synthesized from ethylene oxide, and metal carbonyls catalyzed by bromide;Part of an effort in this thesis is to study the conversion of metal-dioxy carbene complexes into organic compounds and the synthesis of new dioxy and aminooxy carbene complexes. Investigations of reactions of the dioxycarbene ligand show that Fe(CO)[subscript]4(=[overline] COCH[subscript]2 CH[subscript]2 O) decomposes with evolution of CO[subscript]2 and ethylene, but reacts with oxidizing agents, Me[subscript]3NO or O[subscript]2, to produce ethylene carbonate. The reaction of Fe(CO)[subscript]4(=[overline] COCH[subscript]2 CH[subscript]2 O) with H[subscript]2 gas gives 1,3-dioxolane. Also, synthesis of Os[subscript]3(CO)[subscript]11(=[overline] COCH[subscript]2 CH[subscript]2 O), Os[subscript]3(CO)[subscript]10(=[overline] COCH[subscript]2 CH[subscript]2 O)[subscript]2 and derivatives of Re(CO)[subscript]4(Br)(=[overline] COCH[subscript]2 CH[subscript]2 NH) are reported. The x-ray structural characterization of a bis-dioxycarbene complex, Os[subscript]3(CO)[subscript]10(=[overline] COCH[subscript]2 CH[subscript]2 O)[subscript]2 is presented;The other part of this thesis deals with substitution reactions of metal carbonyls. Traditionally, such reactions are carried out under thermal and/or photochemical conditions; despite several commonly observed problems: low yields, mixtures of mono- to multi-substituted products and long reaction time. Here, two Pt(O) compounds, Pt(PPh[subscript]3)[subscript]4 and Pt(dibenzylideneacetone)[subscript]2 are reported to catalyze a variety of phosphine substitution of CO reactions in mono-, di-, and tri-nuclear metal carbonyl complexes. The benefits of these two Pt(O) catalyzed substitution reactions are high yields, almost quantitative recovery of the catalyst and only mono-substituted products

Normative Legitimacy in the Commercialization of Online Community Website

Many online community websites start their operation by a not-for-profit business model, which attracts a lot of users to engage in. The huge user base and heavy Internet traffic could generate revenue and wealth for the websites. When the online communities are becoming popular, entrepreneurs of the online community website may hope to commercialize the online community. Nevertheless, some of community participants are against the commercialization of the online community website, since they regard that the property of online community is belonged to users rather than website owners. Users may challenge the legitimacy in the commercialization process of online community, and argue that the online community should be owned by the public rather than by a company since the enormous community participants put effort in it and make the website a popular one. This study used two case studies of online communities to explain the normative legitimate issues in the entrepreneurship of online community

The association of HBV core promoter double mutations (A1762T and G1764A) with viral load differs between HBeAg positive and anti-HBe positive individuals: A longitudinal analysis

Background/Aims: Although there have been a few reports regarding the effect of basal core promoter (BCP) double mutations (A1762T and G1764A) on hepatitis B viral loads, the association remains uncertain. We aim to determine the association after controlling for HBeAg - a strong confounding factor.Methods: We selected randomly 190 individuals from a Chinese cohort of 2258 subjects for cross-sectional analysis and 56 of the 190 for longitudinal analysis of viral loads.Results: In multivariable analysis of the cross-sectional data, BCP double mutations are significantly associated with lower viral loads in HBeAg positive subjects but no difference was found in anti-HBe positive subjects. Triple mutations at nucleotide (nt) 1753, 1762 and 1764 and mutations between nt 1809 and 1817, precore stop mutation (nt 1896) and genotype are not associated with viral loads in either HBeAg or anti-HBe positive subjects. Analysis of the longitudinal data yielded similar results to the cross-sectional data. Viral loads differ significantly between individuals infected with wild-type and BCP double mutations prior to HBeAg seroconversion but this difference is lost after seroconversion.Conclusions: BCP double mutations are associated with lower viral loads in HBeAg positive individuals but have no effect on the viral loads of anti-HBe positive individuals. (C) 2008 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved

Dependence of the optical conductivity on the uniaxial and biaxial strains in black phosphorene

© 2018 American Physical Society. By using the Kubo formula, the optical conductivity of strained black phosphorene was studied. The anisotropic band dispersion gives rise to an orientation dependent optical conductivity. The energy gap can be tuned by the uniaxial and biaxial strains which can be observed from the interband optical conductivity polarized along the armchair (x) direction. The preferential conducting direction is along the x direction. The dependence of the intraband optical conductivity along the zigzag (y) direction on the Fermi energy and strain exhibits increasing or decreasing monotonously. However, along the x direction this dependence is complicated which originates from the carriers' inverse-direction movements obtained by two types of the nearest phosphorus atom interactions. The modification of the biaxial strain on the energy structure and optical-absorption property is more effective. The imaginary part of the total optical conductivity (Imσ) can be negative around the threshold of the interband optical transition by modifying the chemical potential. Away from this frequency region, Imσ exhibits positive value. It can be used in the application of the surface plasmon propagations in multilayer dielectric structures

Real-time counting of single electron tunneling through a T-shaped double quantum dot system

Real-time detection of single electron tunneling through a T-shaped double quantum dot is simulated, based on a Monte Carlo scheme. The double dot is embedded in a dissipative environment and the presence of electrons on the double dot is detected with a nearby quantum point contact. We demonstrate directly the bunching behavior in electron transport, which leads eventually to a super-Poissonian noise. Particularly, in the context of full counting statistics, we investigate the essential difference between the dephasing mechanisms induced by the quantum point contact detection and the coupling to the external phonon bath. A number of intriguing noise features associated with various transport mechanisms are revealed.Comment: 8 pages, 5 figure

LOQUAT: an open-source GPU-accelerated SPH solver for geotechnical modeling

Smoothed particle hydrodynamics (SPH) is a meshless method gaining popularity recently in geotechnical modeling. It is suitable to solve problems involving large deformation, free-surface, cracking and fragmentation. To promote the research and application of SPH in geotechnical engineering, we present LOQUAT, an open-source three-dimensional GPU accelerated SPH solver. LOQUAT employs the standard SPH formulations for solids with two geomechnical constitutive models which are the Drucker–Prager model and a hypoplastic model. Three stabilization techniques, namely, artificial viscosity, artificial pressure and stress regularization are included. A generalized boundary particle method is presented to model static and moving boundaries with arbitrary geometry. LOQUAT employs GPU acceleration technique to greatly increase the computational efficiency. Numerical examples show that the solver is convergent, stable and highly efficient. With a mainstream GPU, it can simulate large scale problems with tens of millions of particles, and easily performs more than one thousand times faster than serial CPU code

Use of omaha system in community nursing and transitional care

2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe