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Now showing items 49 - 64 of 70

  • Impact of Multi-Walled Carbon Nanotubes on Aquatic Species RID D-4848-2009

    Asharani, P. V.   Serina, N. G. B.   Nurmawati, M. H.   Wu, Y. L.   Gong, Z.   Valiyaveettil, S.  

    To understand the environmental impacts of carbon nanotubes (CNTs), the toxicity study was carried out with water-soluble multi-walled carbon nanotubes (MWCNTs) using zebrafish (Danio rerio) as a model system. Zebrafish embryos were treated with different concentrations of MWCNTs. Teratogenic effects were evaluated through changes in embryonic development after 24 hours post-fertilization (hpf), 48 hpf and 72 hpf. No observable effect concentration (NOEC) was at 40 mu g/mL. Lowest effect concentration (LOEC) of MWCNTs which caused significant phenotypic defects in zebrafish embryo was 60 mu g/mL. At concentration above 60 mu g/mL, slimy mucus like coating was observed around the embryo. At high concentrations, MWCNTs was found to be involved in the apoptosis, delayed hatching and formation of abnormal spinal chords. Thus, the toxicity of multi-walled carbon nanotubes is concentration dependent.
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  • Formation of GaAs/AlGaAs and InGaAs/GaAs nanorings by droplet molecular-beam epitaxy

    Gong, Z.   Niu, Z.C.   Huang, S.S.   Fang, Z.D.   Sun, B.Q.   Xia, J.B.  

    GaAs/AlGaAs lattice-matched nanorings are formed on GaAs (100) substrates by droplet epitaxy. The crucial step in the formation of nanorings is annealing Ga droplets under As flux for proper time. The observed morphologic evolution of Ga droplets during annealing does not support the hypothesis that As atoms preferentially react with Ga around the periphery of the droplets, but somehow relates to a dewetting process similar to that of unstable films. Photoluminescene (PL) test results confirm the quantum-confinement effect of these GaAs nanorings. Using similar methods, we have fabricated InGaAs/GaAs lattice-mismatched rings
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  • Microtubule formation from maternal tubulins during sea urchin embryogenesis: measurement of soluble and insoluble tubulin pools.

    Gong, Z.   Brandhorst, B.P.  

    The mass of tubulin protein in developing embryos of the sea urchin Lytechinus pictus was measured using a radiodilution immunoassay based on densitometric analysis of immunoprecipitated tubulins resolved electrophoretically. The tubulins constitute an average of 360 .+-. 35 pg per egg, or 0.66% of the total protein, and there is no significant change in their concentration during embryogenesis. The masses of soluble and polymerized tubulins were measured for extracts prepared under conditions that stabilize microtubules. In eggs, a maximum of 14% of the tubulin is insoluble, and this increases throughout embryogenesis to 67% at pluteus stage (72 hr). The concentration of tubulin in eggs is at least 500 .mu.g/ml, well above the critical concentration for tubulin assembly in vitro, yet microtubules have not been observed in eggs. The mass of newly synthesized tubulin, estimated from the mass of tubulin mRNA per embryo, accounts for a small fraction of the total tubulin by end of gastrulation but for over half of the tubulin by the 72-hr pluteus stage. These observations are consistent with a model in which the declining level of unpolymerized tubulin controls the stability of tubulin mRNA, providing an autogenous regulation of the ontogenetic pattern of tubulin synthesis during sea urchin embryogenesis.
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  • Hybrid organic/GaN photonic crystal light-emitting diode

    Herrnsdorf, J.   Guilhabert, B.   McKendry, J. J. D.   Gong, Z.   Massoubre, D.   Zhang, S.   Watson, S.   Kelly, A. E.   Gu, E.   Laurand, N.   Dawson, M. D.  

    Periodically nano-patterned organic films incorporating color converting light-emitting polymers have been integrated onto InGaN/GaN light-emitting diodes (LEDs). Polarized and strongly modified hybrid LED emission is observed due to the photonic crystal effect of the nano-pattern. Emission characteristics are appropriate for various applications, and fast modulation capability with an optical -3 dB bandwidth of 168 MHz is demonstrated. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757870]
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  • Identification of the novel HLA-B allele, HLA-B*39:42, in a Chinese individual

    Ni, L.   Shan, X.   Wang, L.   Zhixin, Z.   Gong, Z.  

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  • Modeling the Adhesive Contact Between Cells and a Wavy Extracellular Matrix Mediated by Receptor-Ligand Interactions

    Chong, B.   Gong, Z.   Lin, Y.  

    In this study, we examine the outstanding issue of how surface topology affects the adhesion between cells and the extracellular matrix (ECM). Specifically, we showed that the adhesive contact can be well described by treating the attraction as continuous along the interface if the wavelength of surface undulations is larger than a few microns. On the other hand, the discrete nature of cell-ECM interactions, i.e., adhesion is achieved through the formation of individual receptor-ligand bonds, must be taken into account for wavy surfaces with a much smaller characteristic length. Interestingly, it was found that, due to the interplay between substrate elasticity and stochastic breakage/reformation of molecular bonds, the strength of cell-ECM adhesion will reach its maximum when the surface roughness is of the order of 20-40 nm, in quantitative agreement with recent experiments. In addition, because of the bonding kinetics involved, the apparent adhesion energy was predicted to be strongly rate-dependent with increasing detaching speed between surfaces leading to a rapidly elevated work of separation, a phenomenon that has been widely observed in bio-adhesion.
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  • Uniform emission from matrix-addressable micro-pixellated InGaN light-emitting diodes

    Gong, Z.   Zhang, H.X.   Gu, E.   Dawson, M.D.  

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  • A hybrid equation approach for the solution of electromagnetic scattering problems involving two-dimensional inhomogeneous dielectric cylinders

    Gong, Z.   Glisson, A.W.  

    A numerical procedure for the solution of electromagnetic scattering problems involving inhomogeneous dielectric cylinders of arbitrary cross section is discussed. The cases of illumination by both transverse magnetic (TM) and transverse electric (TE) plane waves are considered. The scattering problems are modeled via a hybrid integral-equation/partial-differential-equation approach. The method of moments is applied to obtain a system of simultaneous equations that can be solved for the unknown surface current densities and the interior electric field. The interior region partial differential equation and the exterior region surface integral equation are coupled in such a manner that many existing surface integral equation computer codes for treating problems involving scattering by homogeneous dielectric cylinders can be modified easily to generate the block of the matrix corresponding to the surface current interactions. The overall system matrix obtained using the method of moments is largely sparse. Numerical results are presented and compared with exact solutions for homogeneous and inhomogeneous circular cylinders.
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  • On the characterization of fixed modes in decentralized control

    Gong, Z.   Aldeen, M.  

    Characterizations of decentralized fixed modes in terms of remnant zeros are presented in this technical note. A new criterion for testing the fixed modes is obtained. The new result can be used to derive an existing algebraic criterion, through a simple rank evaluation of certain matrices.
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  • Analysis of Image Combination Methods for Conjugate Breast Scintigraphy

    Williams, M. B.   More, M. J.   Stolin, A. V.   Proffitt, J.   Kross, B.   McKisson, J.   Majewski, S.   Kieper, D.   St. Saviour, T.   Welch, B. L.   Dinion, N. L.   Gong, Z.   Judy, P. G.  

    The main objective of the present study was to determine if combining the two images from a conjugate counting system might improve the contrast and signal-to-noise ratio (SNR) of small lesions in all regions of the breast compared to images from a single camera. Several methods for combining the opposing pixels of the two camera images were compared: multiplication, geometric mean, and summation. The image quality metrics measured were spatial resolution, lesion contrast and lesion SNR. These quantities were evaluated both theoretically and experimentally. A capillary phantom was used to measure the spatial resolution as a function of lesion depth and to assess the translation and angular offsets between the two cameras. An acrylic box phantom, with spherical lesions suspended inside, was used to evaluate contrast and SNR as a function of lesion position. Both theoretically and experimentally the spatial resolution in the product images was superior to that in the single images, geometric mean or summation images. Relative to the single camera images, the geometric mean or the summed images, the lesion contrast and SNR of the product images were superior, irrespective of lesion depth, and were more constant with changing lesion depth compared to the single camera images. These findings suggest that improved lesion detectability is possible by imaging simultaneously from both sides of the breast, and forming a combined image using pixel-by-pixel multiplication. This may be especially important if the location of the lesion within the breast is not known a priori.
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  • Enhanced laser proton acceleration by target ablation on a femtosecond laser system

    Liao, Q.   Wu, M. J.   Gong, Z.   Geng, Y. X.   Xu, X. H.   Li, D. Y.   Shou, Y. R.   Zhu, J. G.   Li, C. C.   Yang, M.   Li, T. S.   Lu, H. Y.   Ma, W. J.   Zhao, Y. Y.   Lin, C.   Yan, X. Q.  

    Proton acceleration during the interaction of an ultraintense (6 x 10(19) W/cm(2)) femtosecond (fs) laser pulse with a thin (2.5 mu m) foil target pre-ablated by a picosecond (ps) pulse is experimentally and numerically investigated. Enhancements in both proton cut-off energy and charge are observed with the target ablation due to a large number of energetic electrons generated from the preformed preplasma in front of the target. The enhanced proton beams are successfully collected at 4-9 MeV with +/- 4% energy spread and then transported to the irradiating platform. The results show that for the interaction between fs laser pulse and mu m-thickness target, proton energy and charge can be enhanced by target ablation using a ps laser pulse, which is valuable for application like cancer radiotherapy. Published by AIP Publishing.
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  • Risk factors for human rabies in China.

    Gong, Z.   He, F.   Chen, Z.  

    In China, we have witnessed an increasing incidence of rabies in recent years and the number of deaths ranked first among the 39 notifiable infectious diseases. We conducted a case-control study to identify risk factors for human rabies infection and disease to recommend prevention and treatment among people exposed to rabies. Exposure site, pre-exposure prophylaxis and post-exposure prophylaxis were significantly associated with rabies infection. Exposure site at upper limb and trunk or at lower limb were at lower risk as compared with head-exposed patients. The OR was 0.09(95% CI: 0.009-0.93) and 0.01(95% CI: 0.001-0.115) respectively. Pre-exposure prophylaxis (OR=0.05, 95% CI: 0.03-0.11) and post-exposure prophylaxis (OR=0.02, 95% CI: 0.01-0.40) were both protective factors as compared with no prophylaxis. For patients who had post-exposure prophylaxis, dose for the first injection and immunity procedure were significantly associated with rabies infection.
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  • Does alcohol increase breast cancer risk in African-American women? Findings from a case-control study.

    Chandran, U.   Zirpoli, G.   Ciupak, G.   McCann, S. E.   Gong, Z.   Pawlish, K.   Lin, Y.   Demissie, K.   Ambrosone, C. B.   Bandera, E. V.  

    Background: Alcohol is an important risk factor for breast cancer in Caucasian women, but the evidence in African-American (AA) women is limited and results are inconclusive. Methods: Associations between recent and lifetime drinking and breast cancer risk were evaluated in a large sample of AA women from a case-control study in New York and New Jersey. Multivariable logistic regression models provided odds ratios (ORs) and 95% confidence intervals (CIs). Results: There was no association between recent drinking and breast cancer risk, even when stratified by menopausal status or by hormone receptor status. A borderline decreased risk with increased lifetime consumption was found (OR=0.77; 95% CI: 0.58-1.03), which was stronger among women who drank when under 20 years of age (OR=0.65; 95% CI: 0.47-0.89), regardless of menopausal or hormone receptor status. Conclusion: Breast cancer risk associated with recent alcohol consumption was not apparent in AA women, while early age drinking seemed to decrease risk. This is the first investigation on recent and lifetime drinking in subgroups and drinking during different age periods in AA women. If findings are replicated, racial differences in biological pathways involving alcohol and its metabolites should be explored.
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  • Brilliant GeV gamma-ray flash from inverse Compton scattering in the QED regime

    Gong, Z.   Hu, R. H.   Lu, H. Y.   Yu, J. Q.   Wang, D. H.   Fu, E. G.   Chen, C. E.   He, X. T.   Yan, X. Q.  

    An all-optical scheme is proposed for studying laser plasma based incoherent photon emission from inverse Compton scattering in the quantum electrodynamic regime. A theoretical model is presented to explain the coupling effects among radiation reaction trapping, the self-generated magnetic field and the spiral attractor in phase space, which guarantees the transfer of energy and angular momentum from electromagnetic fields to particles. Taking advantage of a prospective similar to 10(23) W cm(-2) laser facility, 3D particle-in-cell simulations show a gamma-ray flash with unprecedented multi-petawatt power and brightness of 1.7 x 10(23) photons s(-1) mm(-2) mrad(-2)/0.1% bandwidth (at 1 GeV). These results bode well for new research directions in particle physics and laboratory astrophysics exploring laser plasma interactions.
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  • Total concentrations and speciation of heavy metals in soils of the Shenyang Zhangshi Irrigation Area, China

    Ratuzny, T.   Gong, Z.  

    The Shenyang Zhangshi Irrigation Area (SZIA) was used for the spreading of municipal and industrial waste water, which is an economic way of irrigating crops, recycling nutrients and water treatment. Long-term irrigation resulted in a severe metal contamination of soils. To identify the soil phases implicated in retaining the metals, sequential extractions were performed. The most predominant metal was cadmium which was mainly associated with mobile, easily soluble and easily reducible fractions. Copper was mainly associated with the residual, EDTA extractable and moderately reducible fractions. Lead was bound to organic matter and poorly crystalline Fe-oxides. Nickel and zinc were mainly associated with the residual and strongly reducible fractions. Although copper, lead, nickel and zinc concentrations were of minor importance mobile metal concentrations of these metals as well as of cadmium exceeded German trigger values for plant production and plant growth.
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  • Genome-wide identification of suitable zebrafish Danio rerio reference genes for normalization of gene expression data by RT-qPCR

    Xu, H.   Li, C.   Zeng, Q.   Agrawal, I.   Zhu, X.   Gong, Z.  

    In this study, to systematically identify the most stably expressed genes for internal reference in zebrafish Danio rerio investigations, 37 D. rerio transcriptomic datasets (both RNA sequencing and microarray data) were collected from gene expression omnibus (GEO) database and unpublished data, and gene expression variations were analysed under three experimental conditions: tissue types, developmental stages and chemical treatments. Forty-four putative candidate genes were identified with the c.v. <0.2 from all datasets. Following clustering into different functional groups, 21 genes, in addition to four conventional housekeeping genes (eef1a1l1, b2m, hrpt1l and actb1), were selected from different functional groups for further quantitative real-time (qrt-)PCR validation using 25 RNA samples from different adult tissues, developmental stages and chemical treatments. The qrt-PCR data were then analysed using the statistical algorithm refFinder for gene expression stability. Several new candidate genes showed better expression stability than the conventional housekeeping genes in all three categories. It was found that sep15 and metap1 were the top two stable genes for tissue types, ube2a and tmem50a the top two for different developmental stages, and rpl13a and rp1p0 the top two for chemical treatments. Thus, based on the extensive transcriptomic analyses and qrt-PCR validation, these new reference genes are recommended for normalization of D. rerio qrt-PCR data respectively for the three different experimental conditions. (C) 2016 The Fisheries Society of the British Isles
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