Hua Zhang

Bio: Hua Zhang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Medicine & Graphene. The author has an hindex of 163, co-authored 1503 publications receiving 116769 citations. Previous affiliations of Hua Zhang include Shenzhen University & Zhengzhou University.

Establishment of channel networks in a digital elevation model of the prairie region through hydrological correction and geomorphological assessment

Abstract: Building channel networks in flat regions of digital elevation models (DEMs) is important for watershed delineation and hydrological modeling, particularly for areas with gently-sloped terrain, such as the Canadian Prairies Existing drainage analysis methods cannot effectively address the spatial correlations of elevation across the flat regions, and the quality of the DEM-derived channel network is mainly evaluated through visual inspection In this study a hydrological correction method is developed that integrates elevation information from both the existing digital channel network and the original DEM A set of geomorphological indices is then introduced for quantitative evaluation of DEM-derived channel networks from the perspectives of flow direction and drainage pattern Both the DEM correction and network assessment methods are implemented in a GIS environment Their performance is demonstrated through a case study in southern Saskatchewan, Canada The generated channel network is consistent with

Study on the mechanism of AMPK signaling pathway and its effect on apoptosis of human hepatocellular carcinoma SMMC-7721 cells by curcumin.

Abstract: OBJECTIVE Liver cancer is a common malignant tumor in the digestive system. Curcumin is a kind of phenolic pigment, which is extracted from herbage and has a plenty of physiological roles in anti-inflammation, anti-oxidation and anti-tumor. In our study, human hepatoma SMMC-7721 cell lines were selected and treated with curcumin to detect its effects on the apoptosis and AMPK signaling pathway. MATERIALS AND METHODS Human liver cancer cell strain SMMC-7721 was cultured and treated with different curcumin concentrations for different times followed by measuring the changes of cell proliferation activity and cycle by MTT and flow cytometry, respectively. Protein expression of Bcl-2, Bax and Caspase-3 were tested by Western blot, and the activation level of AMPK was also detected. RESULTS Different concentrations of curcumin could inhibit the proliferation of tumor cells in a dose-dependent manner. After 48 h inhibition by curcumin with a concentration of 40 mmol/L, the inhibitory effect was more obvious with statistically significant (p<0.05). The number of human liver cancer SMMC-7721 cells increased in G1 stage and decreased in S stage after treated with different concentrations of curcumin. During the G1 stage to the S stage, inhibition occurred and the effect of curcumin intervention group with 40 mmol/L was more evident than that of 10 mmol/L group, 20 mmol/L group and the control group with statistically significant (p<0.05). SMMC-7721 cell stains had been intervening by curcumin with concentrations of 10 mmol/L, 20 mmol/L and 40 mmol/L for 12 h, 24 h and 48 h, as the drug concentration increased, the reaction time prolonged, the protein expressions of Bcl-2 and Survivin were significantly decreased and Bax protein expression was significantly increased (p<0.05). CONCLUSIONS Curcumin decreased the proliferation activity of tumor cells, increased the cell quantities in G1 stage and decreased the cell numbers in S stage in human liver cancer SMMC-7721 cells. The Bcl-2 and Survivin proteins were downregulated and Bax protein was upregulated; furthermore, the AMPK signaling pathway was activated.

Glucose can reverse the effects of acute fasting on mouse ovulation and oocyte maturation.

Abstract: Food deprivation suppresses ovulation. Although nutritional elements are responsible for this suppression, it is not clear whether energy metabolism has any effect on oocyte development under these circumstances. The aim of the present study was to determine which nutritional element is responsible for the effect of acute fasting on mouse ovulation and how oocyte development is affected. The results demonstrate that 64 h food deprivation blocks mouse ovulation. This was reversed by glucose feeding, oil feeding or short-term feeding, all of which elevated serum glucose levels. Furthermore, 48 h food deprivation inhibited follicle-stimulating hormone-induced oocyte maturation in vitro. However, 48 h glucose feeding increased serum glucose levels and restored oocyte maturation. Food deprivation increased serum progesterone levels and decreased serum oestradiol levels. Food deprivation also impaired follicle development, caused the death of oocytes and attenuated glucose consumption by cumulus–oocyte complexes. Taken together, the results indicate that: (1) the suppression of ovulation by acute fasting may be due to the control of oocyte development; and (2) maintaining serum glucose concentrations at a certain level is important for normal ovulation.

Liquid Nanoparticles: Manipulating the Nucleation and Growth of Nanoscale Droplets

Abstract: By manipulating the nucleation and growth of solid materials, the synthesis of various sophisticated nanostructures has been achieved. Similar methodology, if applied to liquids, could enable the mass-production and control of ultra-small droplets at the scale of nanoparticles (10-18 L or below). It would be highly desirable since droplets play a fundamental role in numerous applications. Here we present a general strategy to synthesize and manipulate nanoscale droplets, similar to what has been done to solid nanoparticles in classic solution-synthesis. It was achieved by a solute-induced phase separation which initiates the nucleation of droplets from a homogeneous solution. These liquid nanoparticles have great potentials to be manipulated like their solid counterparts, borrowing from the vast methodologies of nanoparticle synthesis, such as burst nucleation, seeded growth, and co-precipitation. Liquid nanoparticles also serve as a general synthetic platform, to fabricate nanoreactors, drug-loaded carriers, and other hollow nanostructures with a variety of shell materials.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.