Spacer-induced forward osmosis membrane integrity loss during gypsum scaling

We demonstrated forward osmosis (FO) membrane integrity loss during gypsum scaling with the presence of membrane spacer. The gypsum scalant had preferential accumulation adjacent to membrane spacer where the needle-shape gypsum potentially compromised polyamide thin-film composite FO membrane integrity. However, the loss of FO membrane integrity cannot be sensitively detected by in situ measurements of membrane water and salt (NaCl) permeability coefficients. We, for the first time, employed membrane integrity challenge tests to reveal the impaired FO membrane integrity by fluorescent Rhodamine WT tracer and amine-modified latex nanoparticles, respectively. Challenge tests using Rhodamine WT tracer showed that membrane log removal value decreased to 3.5 after three scaling–cleaning cycles, which corresponded to a pinhole size of 0.06 μm2 on the FO membrane. This result was further corroborated by challenge test using latex nanoparticle where the particle size distribution in the permeate became wider and the average particle size increased over the three scaling–cleaning cycles. Both challenge tests were sensitive enough to identify impaired FO membrane integrity. Results reported here have significant implications for achieving better membrane spacer and module design, as well as demanding periodical monitoring of FO membrane integrity in water reuse

Time-dependent density functional theory quantum transport simulation in non-orthogonal basis

Basing on the earlier works on the hierarchical equations of motion for quantum transport, we present in this paper a first principles scheme for time-dependent quantum transport by combining time-dependent density functional theory (TDDFT) and Keldysh's non-equilibrium Green's function formalism. This scheme is beyond the wide band limit approximation and is directly applicable to the case of non-orthogonal basis without the need of basis transformation. The overlap between the basis in the lead and the device region is treated properly by including it in the self-energy and it can be shown that this approach is equivalent to a lead-device orthogonalization. This scheme has been implemented at both TDDFT and density functional tight-binding level. Simulation results are presented to demonstrate our method and comparison with wide band limit approximation is made. Finally, the sparsity of the matrices and computational complexity of this method are analyzed.published_or_final_versio

ZnO nanostructures prepared from ZnO:CNT mixtures

Due to its wide band gap (3.37 eV) and large exciton binding energy (60 meV), ZnO is of great interest for photonic applications. A number of different morphologies, such as nanobelts, nanowires, tetrapod nanostructures, tubular nanostructures, hierarchical nanostructures, nanobridges, nanonails, oriented nanorod arrays, nanoneedles, nanowalls, and nanosheets, were reported. A range of synthesis methods for fabrication of ZnO nanostructures was reported as well. A common method is evaporation from mixture of ZnO and carbon, which is usually in the form of graphite. In this work, we studied the morphology of the ZnO nanostructures fabricated from the mixture of ZnO (micron-sized and nanoparticles) and carbon (graphite, single-wall carbon nanotubes). When graphite and ZnO powders were used, tetrapod structures were obtained. If one of the reactants was nanosized, the diameter of the tetrapod arms was no longer constant. Finally, when both reactants were nanosized, novel morphologies were obtained. We studied the dependence of the morphology on the amount of starting material and the type of carbon used. The ZnO nanostructures were studied using field emission scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and X-ray diffraction. Growth mechanism and factors affecting the morphologies are discussed.published_or_final_versio

Career Experience of Asian Ethnicity Immigrants In Australia

The literature has shown that most immigrants reported a negative experience with their career in their newly adopted countries. In particular, they complained of loss in income and status, especially for those from non-English speaking countries. The Social Psychology literature has been shown that ethnic identity can influence an immigrant's perception of the fairness of organizational recruitment and job acceptance intention. However, little is known of the impact of immigrant's ethnic identity and how this impacts on their career experience. This is the subject of the current paper as we draw upon the literature on ethnic identity and social cognition career theory to examine the career experience 196 `visible racial minority' individuals in Australia. These individuals were immigrants from Asia (first generation Asian Australians) and Asian-born Australians (second generation Asian Australians) in Australia

Using 2x2 switching modules to build large 2-D MEMS optical switches

MEMS optical switch technology is one of the key technologies in wavelength division multiplexing (WDM) optical networks. Although the 2-D MEMS optical switch technology is mature, the commonly used crossbar architecture is not amenable to building large switches. In this paper, we propose a design of 2x2 switching modules, and use it to build large 2-D MEMS optical switches with architectures such as Spanke-Benes and Benes networks.published_or_final_versio

Time-dependent density functional theory for open systems with a positivity-preserving decomposition scheme for environment spectral functions

published_or_final_versio

Retarding viscous Rayleigh-Taylor mixing by an optimized additional mode

The Rayleigh-Taylor (RT) mixing induced by random interface disturbances between two incompressible viscous fluids is simulated numerically. The ensemble averaged spike velocity is found to be remarkably retarded when the random interface disturbances are superimposed with an optimized additional mode. The mode's wavenumber is selected to be large enough to avoid enhancing the dominance of long-wavelength modes, but not so large that its saturated spike and bubble velocities are too small to stimulate a growing effective density-gradient layer suppressing the long-wavelength modes. Such an optimized suppressing mode is expected to be found in the RT mixing including other diffusion processes, e.g., concentration diffusion and thermal diffusion.This work has been supported by the National Science Fund for Distinguished Young Scholars (Grant No. 11225209) and National Natural Science Foundation of China (Grants No. 11490553 and No. 11521091)

Preparation and analysis of a new bioorganic metallic material

Biofouling on metal surfaces is one of the main reasons for increased ship drag. Many methods have already been used to reduce or remove it with moderate success. In this study, a synthetic peptide has been utilized to react with 304 stainless steel aiming to generate a bioorganic stainless steel using a facile technique. After the reaction, white matter was found on the surface of the treated stainless steel via SEM, whilst the nontreated stainless steel had none. Elemental analysis confirmed that excessive N existed on the surface of the treated samples using an integrated SEM-EDS instrument, implying the presence of peptides binding on the surface of the bioorganic stainless steel. The FTIR spectra showed amide A and II peaks on the surface of the bioorganic stainless steel suggesting that either the peptides grafted onto the steel surface or the polypeptide composition accumulated on the steel samples. XPS analysis of the treated steel demonstrated that there was nitrogen bonding on the surface and it was a chemical bond via a previously unreported chemical interaction. The treated steel has a markedly increased contact angle (water contact angle of 65.7 ± 4.7° for nontreated steel in comparison to treated, 96.4 ± 2.1°), which supported the observation of the wettability change of the surface, i.e. the decrease of the surface energy value after peptide treatment. The changes of the surface parameters (such as, Sa, Sq, Ssk and Sku) of the treated steel by surface analysis were observed

Scalp acupuncture for acute ischemic stroke: a meta-analysis of randomized controlled trials

Scalp acupuncture (SA) is a commonly used therapeutic approach for stroke throughout China and elsewhere in the world. The objective of this study was to assess clinical efficacy and safety of SA for acute ischemic stroke. A systematical literature search of 6 databases was conducted to identify randomized controlled trials (RCTs) of SA for acute ischemic stroke compared with western conventional medicines (WCMs). All statistical analyses were performed by the Rev Man Version 5.0. Eight studies with 538 participants were included in the studies. The studies were deemed to have an unclear risk of bias based on the Cochrane Back Review Group. Compared with the WCM, 6 RCTs showed significant effects of SA for improving neurological deficit scores (P < 0.01); 4 RCTs showed significant effects of SA for favoring the clinical effective rate (P < 0.01) However, the adverse events have not been documented. In conclusion, SA appears to be able to improve neurological deficit score and the clinical effective rate when compared with WCM, though the beneficial effect from SA is possibly overvalued because of generally low methodology of the included trials. No evidence is available for adverse effects. Rigorous well-designed clinical trials are needed.published_or_final_versio