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Hangzhou, China

Zhuang Y.-Q.,Xiamen University | Ke X.,Xiamen University | Zhan X.-L.,Zhejang University | Luo Z.-H.,Xiamen University
Powder Technology

In the present study, the particle kinetics and physical mechanism of microemulsion polymerization of octamethylcyclotetrasiloxane (D4) were investigated by using dodecyldimethylbenzyl ammonium bromide (DBDA) as a surfactant and n-pentane as a cosurfactant. The light transparence of the emulsion, oil-water interfacial tension and the polymerization conversion as functions of the polymerization time were recorded. Furthermore, the particle sizes and their distributions in the process were measured by using dynamic light scattering technique (DLS). The results show that there does not exist constant-rate reaction period during the polymerization. The results of DLS show that the microemulsion polymerization can be distinguished as four steps, namely (I) the dispersion period, (II) the colloid formation and reaction period, (III) the colloid reaction period, and (IV) the agglomeration period. Corresponding physical models for each period were discussed. It has been found that the nucleation occurs mostly in the swollen-micelles and the polymerization occurs mostly in the new microlatex particles for the microemulsion polymerization of D4. © 2010 Elsevier B.V. Source

Yang J.,Zhejiang University | Ye J.J.,Zhejiang University | Zheng J.Y.,Zhejiang University | Wong I.,University of California at Los Angeles | And 4 more authors.
Journal of Heat Transfer

Micro-electromechanical systems and nano-electromechanical systems have attracted a great deal of attention in recent years. The flow and heat transfer behaviors of micromachines for separation applications are usually different from that of macro counterparts. In this paper, heat and mass transfer characteristics of rarefied nitrogen gas flows in microchannels are investigated using direct simulation Monte Carlo with improved pressure boundary conditions. The influence of aspect ratio and wall temperature on mass flowrate and wall heat flux in microchannels are studied parametrically. In order to examine the aspect ratio effect on heat and mass transfer behaviors, the wall temperature is set constant at 350 K and the aspect ratio of the microchannel varies from 5 to 20. The results show that as the aspect ratio increases, the velocity of the flow decreases, so does the mass flowrate. In a small aspect ratio channel, the heat transfer occurs throughout the microchannel; as the aspect ratio of the microchannel increases, the region of thermal equilibrium extends. To investigate the effects of wall temperature (Tw) on the mass flowrate and wall heat flux in a microchannel, the temperature of the incoming gas flow (Tin) is set constant at 300 K and the wall temperature varies from 200 K to 800 K while the aspect ratio is remained unchanged. Results show that majority of the wall heat flux stays within the channel entrance region and drops to nearly zero at the halfway in the channel. When Tw Source

Reith F.,University of Adelaide | Reith F.,CSIRO | Brugger J.,University of Adelaide | Brugger J.,South Australian Museum | And 13 more authors.
ISME Journal

Links between microbial community assemblages and geogenic factors were assessed in 187 soil samples collected from four metal-rich provinces across Australia. Field-fresh soils and soils incubated with soluble Au(III) complexes were analysed using three-domain multiplex-terminal restriction fragment length polymorphism, and phylogenetic (PhyloChip) and functional (GeoChip) microarrays. Geogenic factors of soils were determined using lithological-, geomorphological-and soil-mapping combined with analyses of 51 geochemical parameters. Microbial communities differed significantly between landforms, soil horizons, lithologies and also with the occurrence of underlying Au deposits. The strongest responses to these factors, and to amendment with soluble Au(III) complexes, was observed in bacterial communities. PhyloChip analyses revealed a greater abundance and diversity of Alphaproteobacteria (especially Sphingomonas spp.), and Firmicutes (Bacillus spp.) in Au-containing and Au(III)-amended soils. Analyses of potential function (GeoChip) revealed higher abundances of metal-resistance genes in metal-rich soils. For example, genes that hybridised with metal-resistance genes copA, chrA and czcA of a prevalent aurophillic bacterium, Cupriavidus metallidurans CH34, occurred only in auriferous soils. These data help establish key links between geogenic factors and the phylogeny and function within soil microbial communities. In particular, the landform, which is a crucial factor in determining soil geochemistry, strongly affected microbial community structures. © 2012 International Society for Microbial Ecology All rights reserved. Source

Ding X.,Zhejang University | Ding X.,University of Rochester | Yang D.-R.,University of Rochester | Yang D.-R.,Soochow University of China | And 9 more authors.
International Journal of Cancer

Testicular nuclear receptor 4 (TR4) plays protective roles against oxidative stress and DNA damage and might contribute to aging. Our recent clinical tumor tissue staining results showed higher expression of TR4 in prostate cancer (PCa) patients with high Gleason scores compared to the tissues with the low Gleason scores. In vitro migration/invasion assays after manipulation of the TR4 expression in PCa cells showed that TR4 promoted PCa cells migration/invasion. Mechanism dissection found that the CCL2/CCR2 signal plays the key role in the mediation of TR4-promoted PCa cells migration/invasion. Chromatin immunoprecipitation and Luciferase assays further confirmed TR4 modulation of CCL2 at the transcriptional level and addition of the CCR2 antagonist led to interruption of the TR4-enhanced PCa cells migration/ invasion. Finally, the orthotopic xenografted mice studies using the luciferase expressing CWR22Rv1 cells found that TR4 enhanced PCa metastasis and this increased metastasis was reversed when the CCR2 antagonist was injected into the mice. Together, these in vitro and in vivo results revealed a positive role of TR4 in PCa metastasis and demonstrated CCL2/CCR2 signaling as an important mediator in exerting TR4 action. This finding suggests that TR4 may represent a biomarker related to PCa metastasis and targeting the TR4-CCL2/CCR2 axis may become a new therapeutic approach to battle PCa metastasis. © 2014 UICC. Source

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