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Search Results: 1 - 10 of 299568 matches for " J. Gan "
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HIV Pol Inhibits HIV Budding and Mediates the Severe Budding Defect of Gag-Pol
Xin Gan, Stephen J. Gould
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029421
Abstract: The prevailing hypothesis of HIV budding posits that the viral Gag protein drives budding, and that the Gag p6 peptide plays an essential role by recruiting host-cell budding factors to sites of HIV assembly. HIV also expresses a second Gag protein, p160 Gag-Pol, which lacks p6 and fails to bud from cells, consistent with the prevailing hypothesis of HIV budding. However, we show here that the severe budding defect of Gag-Pol is not caused by the absence of p6, but rather, by the presence of Pol. Specifically, we show that (i) the budding defect of Gag-Pol is unaffected by loss of HIV protease activity and is therefore an intrinsic property of the Gag-Pol polyprotein, (ii) the N-terminal 433 amino acids of Gag and Gag-Pol are sufficient to drive virus budding even though they lack p6, (iii) the severe budding defect of Gag-Pol is caused by a dominant, cis-acting inhibitor of budding in the HIV Pol domain, and (iv) Gag-Pol inhibits Gag and virus budding in trans, even at normal levels of Gag and Gag-Pol expression. These and other data support an alternative hypothesis of HIV budding as a process that is mediated by the normal, non-viral pathway of exosome/microvesicle biogenesis.
New Achievements of Government Accounting Reform in China—“Governmental Accounting Standards—Basic Standards”  [PDF]
Fangping Gan
Modern Economy (ME) , 2016, DOI: 10.4236/me.2016.74050
Abstract: Through joint efforts, “Chinese Government Accounting Standards—Basic Standards” was finally officially promulgated on October 23, 2015. This is a great achievement of our government accounting reform and it has a significant influence on future reform in China. The purpose of this paper is introducing our first government accounting standards and by comparing, I find several ways to safeguard its implementation. My conclusion is that our future governmental accounting standards will be better and more fruitful.
First-principles study of graphene edge properties and flake shapes
Chee Kwan Gan,David J. Srolovitz
Physics , 2009, DOI: 10.1103/PhysRevB.81.125445
Abstract: We use density functional theory to determine the equilibrium shape of graphene flakes, through the calculation of the edge orientation dependence of the edge energy and edge stress of graphene nanoribbons. The edge energy is a nearly linear function of edge orientation angle; increasing from the armchair orientation to the zigzag orientation. Reconstruction of the zigzag edge lowers its energy to less than that of the armchair edge. The edge stress for all edge orientations is compressive, however, reconstruction of the zigzag edge reduces this edge stress to near zero. Hydrogen adsorption is favorable for all edge orientations; dramatically lowering all edge energies and all edge stresses. It also removes the reconstruction of the zigzag edge. Using the new edge energy data, we determine the equilibrium shape of a graphene sheet (with unreconstructed edges) to be hexagonal with straight armchair edges in the presence and absence of hydrogen. However, zigzag edge reconstruction produces graphene flakes with a six-fold symmetry, but with rounded edges. This shape is dominated by near zigzag edges. The compressive edge stresses will lead to edge buckling (out-of-the-plane of the graphene sheet) for all edge orientations, in the absence of hydrogen. Exposing the graphene flake to hydrogen dramatically decreases the buckling amplitude.
First-principles study of wurtzite InN$(0001)$ and $(000{\bar 1})$ surfaces
Chee Kwan Gan,David J. Srolovitz
Physics , 2006, DOI: 10.1103/PhysRevB.74.115319
Abstract: Density-functional calculations are used to study various plausible structures of the wurtzite InN $(0001)$ and $(000{\bar 1})$ surfaces. These structures include the unreconstructed surfaces, surfaces with monolayers of In or N, several possible coverages and locations of In or N adatoms and vacancies. The stable structure of the $(0001)$ surface under N-rich conditions is the unreconstructed, In-terminated, surface, while under In-rich conditions the stable surface has a 3/4 monolayer of In atoms. The stable structure of the InN $(000{\bar 1})$ surface corresponds to a full monolayer of In atoms in the atop sites (directly above the N atoms) over the entire range of accessible In (or N) chemical potential. The atomic structures of the low-energy structures are also discussed.
Experimental Study of Nonequilibrium Electrodeposition of Nanostructures on Copper and Nickel for Photochemical Fuel Cell Application
Rajesh K. Shanmugam,Bo J. Gan,Boya Zhang,Lusheng Su,Yong X. Gan
Journal of Nanotechnology , 2011, DOI: 10.1155/2011/727396
Abstract: To increase the performance of photochemical fuel cells, nonequilibrium electrodeposition has been performed on Cu and Ni to make photosensitive anodes. Processing parameters including electrolyte concentration, and electrode potential were studied using cyclic voltammetry. Scanning electron microscopy (SEM) and X-ray Spectroscopy (EDS) were performed to understand the formation of the nanostructures during the nonequilibrium deposition of copper fractals. An increase in the deposition rate was observed with the increase in electrolyte concentration (from 0.05?M to 1.0?M). Similar trend was found when the cathode potential was decreased from ?0.5?V to ?4.5?V. The effect of substrate material was also examined. Porous fractal structures on copper were achieved, while the deposited material showed high density of surface cracks on nickel. The fractal structures deposited on copper electrode with the increased surface area were converted into copper oxide by oxidation in air. Such oxide samples were made into anodes for photochemical fuel cell application. We demonstrated that an increase in the magnitude of open circuit output voltage is associated with the increase in the fractal surface area under the ultraviolet irradiation test conditions. However, the electrodeposited fractals on nickel showed very limited increase in the magnitude of open circuit voltage. 1. Introduction With the growing uncertainty about the availability of fossil fuels, a need to research on alternative energy sources has risen. Alternative energy resources are renewable and use the natural sources of energy, for example, solar radiation. Investing in technologies, that use alternative energy resources for high energy generation efficiency, has increased over the last two decades. Fuel cell is one of the most promising technologies in the future to generate electricity using the natural sources. One of the major efforts in fuel cell technology is to make high efficiency electrodes. Nanotechnology plays an important role in making highly active catalytic materials at electrodes. Nanotechnology typically consists of top-down and bottom-up processing technologies. Material deposition belongs to the bottom-up one, which can be achieved in different ways, including chemical vapor deposition (CVD) [1], molecular beam epitaxy (MBE) [2], closed space vapor transport technique [3], sonoelectrochemical method [4–6], chemical bath deposition, and electrodeposition. Electrodeposition offers advantages over competing technologies such as physical and chemical vapor deposition, in that it
Inter-shelf nutrient transport from the East China Sea as a major nutrient source supporting winter primary production on the northeast South China Sea shelf
A. Han,M. Dai,J. Gan,S.-J. Kao
Biogeosciences Discussions , 2013, DOI: 10.5194/bgd-10-3891-2013
Abstract: The East China Sea (ECS) and the South China Sea (SCS) are two major marginal seas of the north Pacific with distinct seasonal primary productivity. Based upon field observation in December 2008–January 2009 covering both the ECS and the northern SCS (NSCS) in wintertime, we examined southward long-range nutrient-transport from the ECS to the northeast SCS (NESCS) carried by the China Coastal Current (CCC) driven by the northeast prevailing monsoon. These nutrients escaped from the cold ECS shelf to refuel the primary production on the NESCS shelf where river-sourced nutrients were limited yet water temperature remained favorable. By coupling the field observation of nitrate + nitrite (DIN) with the volume transport of the CCC, we derived a first order estimate of DIN flux of ~ 1430 ± 260 mol s 1. This DIN flux was ~ 7 times the wintertime DIN input from the Pearl River, a primary riverine nutrient source to the NSCS. By assuming DIN was the limiting nutrient, such southward DIN transport would have stimulated ~ 8.8 ± 1.6 × 1011 gC of new production (NP), accounting for ~ > 58 ± 10% of the total NP or ~ 38 ± 7–24 ± 4% of primary production on the NESCS shelf shallower than 100 m.
Realization of Network Bypass Protecting Instrument Based on ARM-Linux  [PDF]
Yiming Gan, Mao Tian
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.44033
Abstract: With the control mode of value-added network services equipment changing from bypass intervention to serial control, in order to minimize the security problems which are caused by the failure of the network equipment, this paper proposes a stable, fast and intelligent network bypass protection system combined with the ARM embedded system—Linux platform. In practical application, the system can automatically skip the broken-down device node to protect the network to be unobstructed. With the features of fast response, stable operation, low power consumption, and the flexible of combination, the scheme is proved to have large practical value.
3-D Ultrastructure of O. tauri: Electron Cryotomography of an Entire Eukaryotic Cell
Gregory P. Henderson, Lu Gan, Grant J. Jensen
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000749
Abstract: The hallmark of eukaryotic cells is their segregation of key biological functions into discrete, membrane-bound organelles. Creating accurate models of their ultrastructural complexity has been difficult in part because of the limited resolution of light microscopy and the artifact-prone nature of conventional electron microscopy. Here we explored the potential of the emerging technology electron cryotomography to produce three-dimensional images of an entire eukaryotic cell in a near-native state. Ostreococcus tauri was chosen as the specimen because as a unicellular picoplankton with just one copy of each organelle, it is the smallest known eukaryote and was therefore likely to yield the highest resolution images. Whole cells were imaged at various stages of the cell cycle, yielding 3-D reconstructions of complete chloroplasts, mitochondria, endoplasmic reticula, Golgi bodies, peroxisomes, microtubules, and putative ribosome distributions in-situ. Surprisingly, the nucleus was seen to open long before mitosis, and while one microtubule (or two in some predivisional cells) was consistently present, no mitotic spindle was ever observed, prompting speculation that a single microtubule might be sufficient to segregate multiple chromosomes.
Adjusting wheal size measures to correct atopy misclassification
Zhang H,Karmaus W,Gan J,Bao W
International Journal of General Medicine , 2011,
Abstract: Hongmei Zhang1,*, Wilfried Karmaus1,*, Jianjun Gan2, Weichao Bao1,*, Yan D Zhao3, Dewi Rahardja3, John W Holloway5, Martha Scott4,5, Syed Hasan Arshad4,51Department of Epidemiology and Biostatistics, The University of South Carolina, Columbia, SC, USA; 2GlaxoSmithKline, Research Triangle Park, NC, USA; 3Department of Clinical Science and Simmons Cancer Center, UT Southwestern Medical Center, Dallas, TX, USA; 4The David Hide Asthma and Allergy Research Center, St Mary’s Hospital, Newport, Isle of Wight, UK; 5School of Medicine, University of Southampton, Southampton, UK *These authors contributed equally to this articlePurpose: Skin prick testing (SPT) is fundamental to the practice of clinical allergy identifying relevant allergens and predicting the clinical expression of disease. Wheal sizes on SPT are used to identify atopic cases, and the cut-off value for a positive test is commonly set at 3 mm. However, the measured wheal sizes do not solely reflect the magnitude of skin reaction to allergens, but also skin reactivity (reflected in the size of histamine reaction) and other random or non-random factors. We sought to estimate wheal sizes exclusively due to skin response to allergens and propose gender-specific cutoff points of atopy.Methods: We developed a Bayesian method to adjust observed wheal sizes by excluding histamine and other factor effects, based on which revised cutoff points are proposed for males and females, respectively. The method is then applied to and intensively evaluated using a study population aged 18, at a location on the Isle of Wight in the United Kingdom. To evaluate the proposed approach, two sample t-tests for population means and proportion tests are applied.Results: Four common aeroallergens, house dust mite (HDM), grass pollen, dog dander, and alternaria are considered in the study. Based on 3 mm cutoff, males tend to be more atopic than females (P-values are between 0.00087 and 0.062). After applying the proposed methods to adjust wheal sizes, our findings suggest that misclassifications of atopy occur more often in males. Revised allergen-specific cutoff values are proposed for each gender.Conclusion: To reduce the gender discrepancy, we may have two potentially convenient solutions. One way is to apply allergen-specific and gender-specific cutoff values following the proposed method. Alternatively, we can revise the concentration of allergens in the SPT solutions but keep the cutoff values unchanged, which may be more convenient to clinicians.Keywords: SPT, atopy, Bayesian method, joint modeling, misclassification
In vitro cytotoxicity and induction of apoptosis by silica nanoparticles in human HepG2 hepatoma cells
Lu X,Qian J,Zhou H,Gan Q
International Journal of Nanomedicine , 2011,
Abstract: Xun Lu2,3, Jiangchao Qian1, Huanjun Zhou2,3, Qi Gan2,3, Wei Tang1, Jingxiong Lu3, Yuan Yuan1,2, Changsheng Liu1–31State Key Laboratory of Bioreactor Engineering, 2Key Laboratory for Ultrafine Materials of Ministry of Education, 3Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai, People’s Republic of ChinaBackground: Silica nanoparticles have been discovered to exert cytotoxicity and induce apoptosis in normal human cells. However, until now, few studies have investigated the cytotoxicity of silica nanoparticles in tumor cells.Methods: This study investigated the cytotoxicity of 7–50 nm silica nanoparticles in human HepG2 hepatoma cells, using normal human L-02 hepatocytes as a control. Cell nucleus morphology changes, cellular uptake, and expression of procaspase-9, p53, Bcl-2, and Bax, as well as the activity of caspase-3, and intracellular reactive oxygen species and glutathione levels in the silica nanoparticle-treated cells, were analyzed.Results: The antitumor activity of the silica nanoparticles was closely related to particle size, and the antiproliferation activity decreased in the order of 20 nm > 7 nm > 50 nm. The silica nanoparticles were also cytotoxic in a dose- and time-dependent manner. However, the silica nanoparticles showed only slight toxicity in the L-02 control cells, Moreover, in HepG2 cells, oxidative stress and apoptosis were induced after exposure to 7–20 nm silica nanoparticles. Expression of p53 and caspase-3 increased, and expression of Bcl-2 and procaspase-9 decreased in a dose-dependent manner, whereas the expression of Bax was not significantly changed.Conclusion: A mitochondrial-dependent pathway triggered by oxidative stress mediated by reactive oxygen species may be involved in apoptosis induced by silica nanoparticles, and hence cytotoxicity in human HepG2 hepatic cancer cells.Keywords: silica nanoparticles, cytotoxicity, apoptosis, HepG2 cells, mitochondrial-dependent pathway, oxidative stress
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