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Influence of the lithium content on the negative difference effect of Mg-Li alloys

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Journal of Materials Science & Technology 2020年第22期54卷 138-145页

作者： C.Q.Li D.k.Xu Z.R.Zhang E.H.Han School of Materials and Energy Guangdong University of TechnologyGuangzhou 510006China key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The so-called 'negative difference effect'(NDE) was often defined by the increasing rate of hydrogen evolution from magnesium(Mg) surface under anodic *** this work,a series of electrochemical tests and microstructure observations were performed to provide an evidence that the NDE of Mg-Li alloys can be retarded by increasing lithium ***,galvanostatic and potentiodynamic polarization experiments using Mg-xLi(x=4,7.5 and 14 wt%) alloys electrodes indicated that Mg-4 Li alloy maintained the enhancing NDE prior to anodic dissolution as that of conventional Mg ***,the emergence of β-Li phase weakened the NDE of duplex Mg-7.5 Li alloy at a low anodic current density,but it was still enhanced apparently after a high applied anodic value(more than 2 mA/cm^2).The surface observations,including the plane and cross-sectional morphologies,confirmed that the cracked surface film derived from the anodic dissolution resulted in the catalytic activity of NDE for Mg-4 Li and Mg-7.5 Li ***,the NDE of Mg-14 Li alloy was suppressed obviously after a prior applied anodic polarization,which was attributed to the persistent and integrated surface film which endured a higher level of applied anodic potential and current.

关键词： Mg-Li alloy Negative difference effect Electrochemical property Corrosion Anodic dissolution

Elastic and viscoelastic solutions to rotating functionally graded hollow and solid cylinders

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Applied Mathematics and Mechanics(English Edition) 2008年第12期29卷 1601-1616页

作者： A. M. Zenkour k. A. Elsibai D. S. Mashat Department of Mathematics Faculty of Science King Abdulaziz University Department of Mathematics Faculty of Education Kafr El-Sheikh University Department of Mathematics Faculty of Science Mansoura University

Analytical solutions to rotating functionally graded hollow and solid long cylinders are developed. Young＇s modulus and material density of the cylinder are assumed to vary exponentially in the radial direction, and Poisson＇s ratio is assumed to be constant. A unified governing equation is derived from the equilibrium equations, compatibility equation, deformation theory of elasticity and the stress-strain relationship. The governing second-order differential equation is solved in terms of a hypergeometric function for the elastic deformation of rotating functionally graded cylinders. Dependence of stresses in the cylinder on the inhomogeneous parameters, geometry and boundary conditions is examined and discussed. The proposed solution is validated by comparing the results for rotating functionally graded hollow and solid cylinders with the results for rotating homogeneous isotropic cylinders. In addition, a viscoelastic solution to the rotating viscoelastic cylinder is presented, and dependence of stresses in hollow and solid cylinders on the time parameter is examined.

关键词： rotating hollow cylinder solid shaft functionally graded materials

Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries

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Journal of Energy Chemistry 2019年第2期28卷 17-22页

作者： Maria k.Rybarczyk Yunming Li Mo Qiao Yong-Sheng Hu Maria-Magdalena Titirici Marek Lieder Gdansk University of Technology Chemical Faculty key Laboratory for Renewable Energy Beijing Key Laboratory for New Energy Materials and DevicesNational Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Queen Mary University London School of Materials Science & Engineering

Here,we report the synthesis of hard carbon materials(RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion *** studies show that the electrochemical properties of RHs are affected by the treatment temperatures,which determine the materials morphology,in particular,their degree of graphitization and extent of continuous channels(nanovoids).The latter are accessible to sodium ions and significantly contribute to charge storage capacity of the produced *** RHs obtained at 1600 °C deliver the highest reversible capacity of276 mAh g^(-1) mainly due to insertion of sodium ions into the *** work deepens the basic understanding of the influence of the carbonization temperature on the sodium storage mechanism.

关键词： Nanovoids in rice husk Sustainable energy storage Na-ion batteries

Cleavage of the Carboxyl-Terminus of LEACS2, a Tomato 1-Aminocyclopropane-l-Carboxylic Acid Synthase Isomer, by a 64-kDa Tomato Metalloprotease Produces a Truncated but Active Enzyme

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Journal of Integrative Plant Biology 2005年第11期47卷 1352-1363页

作者： Jian-Feng LI Robert QI Liang-Hu QU Autar k Mattoo Ning LI Department of Biology The Hong Kong University of Science and Technology Hong Kong SAR China key Laboratory of Gene Engineering of the Ministry of Education Zhongshan University Guangzhou 510275 China Department of Biochemistry The Hong kong University of Science and Technology Hong Kong SAR China Sustainable Agricultural Systems Laboratory United States Department of Agriculture-Agriculture Research Service Beltsville Maryland 20705-2350 USA

1-Aminocyclopropane-1-carboxylic acid （ACC） synthase （ACS） is the principal enzyme in phytohormone ethylene biosynthesis. Previous studies have shown that the hypervariable C-terminus of ACS is proteolytically processed in vivo. However, the protease responsible for this has not yet been identified. In the present study, we investigated the processing of the 55-kDa full-length tomato ACS （LeACS2） into 52-, 50- and 49-kDa truncated isoforms in ripening tomato （Lycopersicon esculentum Mill. cv. Cooperation 903） fruit using the sodium dodecyl sulfate-boiling method. Meanwhile, an LeACS2-processing protease was purified via multi-step column chromatography from tomato fruit. Subsequent biochemical analysis of the 64-kDa purified protease revealed that it is a metalloprotease active at multiple cleavage sites within the hypervariable C-terminus of LeACS2. N-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight analysis indicated that the LeACS2-processing metalloprotease cleaves at the C-terminal sites Lys^438, Glu^447, Lys^448, Asn^456, Ser^460, Ser^462, Lys^463, and Leu^474, but does not cleave the N- terminus of LeACS2. Four C-terminus-deleted （26-50 amino acids） LeACS2 fusion proteins were overproduced and subjected to proteolysis by this metalloprotease to identify the multiple cleavage sites located on the N-terminal side of the phosphorylation site Ser^460. The results indisputably confirmed the presence of cleavage sites within the region between the α-helix domain （H14） and Ser^460 for this metalloprotease. Furthermore, the resulting C-terminally truncated LeACS2 isoforms were active enzymatically. Because this protease could produce LeACS2 isoforms in vitro similar to those detected in vivo, it is proposed that this metalloprotease may be involved in the proteolysis of LeACS2 in vivo.

关键词： 1-aminocyclopropane-1-carboxylic acid synthase cleavage sites metalloprotease proteolytic processing.

Petrography and geochemistry of Jumara Dome sediments, kachchh Basin: Implications for provenance, tectonic setting and weathering intensity

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Chinese Journal Of Geochemistry 2014年第1期33卷 9-23页

作者： Ahmad A.H.M Noufal k.N Masroor Alam M Tavheed khan Department of Geology Department of civil Engineering ZH College of Engineering and Technology

In the kachchh Mainland, the Jumara Dome mixed carbonate-siliciclastic succession is represented by the Jhurio and Patcham formations and siliciclastic-dominating Chari Formation(Bathonian to Oxfordian). The Jumara Dome sediments were deposited during sea-level fluctuating, and were interrupted by storms in the shallow marine environment. The sandstones are generally medium-grained, moderately sorted, subangular to subrounded and of low sphericity. The sandstones are mineralogically mature and mainly composed of quartzarenite and subarkose. The plots of petrofacies in the Qt-F-L, Qm-F-Lt, Qp-Lv-Ls and Qm-P-k ternary diagrams suggest mainly the basement uplift source(craton interior) in rifted continental margin basin setting. The sandstones were cemented by carbonate, iron oxide and silica overgrowth. The Chemical Index of Alteration values(73% sandstone and 81% shale) indicate high weathering conditions in the source area. Overall study suggests that such strong chemical weathering conditions are of unconformity with worldwide humid and warm climates during the Jurassic period. Positive correlations between Al2O3 and Fe2O3, TiO2, Na2O, MgO, k2O are evident. A high correlation coefficient between Al2O3 and k2O in shale samples suggests that clay minerals control the major oxides. The analogous contents of Si, Al, Ti, LREE and TTE in the shale to PAAS with slightly depleted values of other elements ascribe a PAAS like source(granitic gneiss and minor mafics) to the present study. The petrographic and geochemical data strongly suggest that the studied sandstones/shales were deposited on a passive margin of the stable intracratonic basin.

关键词：大陆边缘盆地地球化学数据沉积物岩相学风化强度构造背景源区圆顶

NOx Change over China and Its Influences

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Advances in Atmospheric Sciences 2004年第1期21卷 132-140页

作者：刘煜 I.S.A.ISAkSEN J.k.SUNDET 何金海颜鹏 Chinese Academy of Meteorological Sciences Beijing 100081 Nanjiny Institute of Meteorology Nanjing 210044 Department of Geophysics University of Oslo Norway Nanjiny Institute of Meteorology Nanjing 210044 Chinese Academy of Meteorological Sciences Beijing 100081

A 3-D chemical transport model (OSLO CTM2) is used to investigate the impact of the increase of NOx emission over China. The model is capable to reproduce basically the seasonal variation of surface NOX and ozone over eastern China. NOx emission data and observations reveal that NOx over eastern China increases quite quickly with the economic development of China. Model results indicate that NOx concentration over eastern China increasingly rises with the increase of NOX emission over China, and accelerates to increase in winter. When the NOx emission increases from 1995 to its double, the ratio of NO2/NOx abruptly drops in winter over northern China. Ozone at the surface decreases in winter with the continual enhancement of the NOX level over eastern China, but increases over southern China in summertime. It is noticeable that peak ozone over northern China increases in summer although mean ozone changes little. In summer, ozone increases in the free troposphere dominantly below 500 hPa. Moreover, the increases of total ozone over eastern China are proportional to the increases of NOX emission. In a word, the model results suggest that the relationship between NOX and ozone at the surface would change with NOx increase.

关键词： NOX ozone OH

Interactive effects of reproductive assets and ambient predation risk on the threat-sensitive decisions of Trinidadian guppies

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Current Zoology 2016年第3期62卷 221-226页

作者： Jemma kATWAROO-ANDERSEN Chris k. ELVIDGE Indar RAMNARINE Grant E. BROWN Department of Biology Concordia University 7141 Sherbrooke St. West Montreal QC H4B 1R6 Canada Department of Life Sciences University of the West Indies St. Augustine Trinidad and Tobago

Threat-sensitive behavioral trade-offs allow prey animals to balance the conflicting demands of successful predator detection and avoidance and a suite of fitness-related activities such as forag- ing, mating, and territorial defense. Here, we test the hypothesis that background predation level and reproductive status interact to determine the form and intensity of threat-sensitive behavioral decisions of wild-caught female Trinidadian guppies Poecilia reticulata. Gravid and nongravid gup- pies collected from high- and low-predation pressure populations were exposed to serial dilutions of conspecific chemical alarm cues. Our results demonstrate that there was ＇no effect of reproduct- ive status on the response of females originating from a low-predation population, with both gravid and nongravid guppies exhibiting strong anti-predator responses to the lowest concentration of alarm cues tested. Increasing cue concentrations did not result in increases in response intensity. Conversely, we found a significant effect of reproductive status among guppies from a high- predation population. Nongravid females from the high-predation population exhibited a strong graded （proportional） response to increasing concentrations of alarm cue. Gravid females from the same high-predation population, however, shifted to a nongraded response. Together, these re- sults demonstrate that accrued reproductive assets influence the threat-sensitive behavioral deci- sions of prey, but only under conditions of high-ambient predation risk.

关键词： asset protection antipredator behavior fitness trade-offs ecological uncertainty chemical alarm cues.

Modulation of signal transduction pathways by natural compounds in cancer

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Chinese Journal of Natural Medicines 2015年第10期13卷 730-742页

作者： Alok Ranjan Neel M.Fofaria Sung-Hoon kim Sanjay k.Srivastava Department of Biomedical Sciences and Cancer Biology Center Texas Tech University Health Sciences Center Cancer Preventive Material Development Research Center College of Korean Medicine Department of Pathology Kyunghee University

Cancer is generally regarded as the result of abnormal growth of cells. According to World Health Organization, cancer is the leading cause of mortality worldwide. Mother nature provides a large source of bioactive compounds with excellent therapeutic efficacy. Numerous phytochemicals from nature have been investigated for anticancer properties. In this review article, we discuss several natural compounds, which have shown anti-cancer activity. Natural compounds induce cell cycle arrest, activate intrinsic and extrinsic apoptosis pathways, generate Reactive Oxygen Species(ROS), and down-regulate activated signaling pathways, resulting in inhibition of cell proliferation, progression and metastasis of cancer. Several preclinical studies have suggested that natural compounds can also increase the sensitivity of resistant cancers to available chemotherapy agents. Furthermore, combining FDA approved anti-cancer drugs with natural compounds results in improved efficacy. On the basis of these exciting outcomes of natural compounds against several cancer types, several agents have already advanced to clinical trials. In conclusion, preclinical results and clinical outcomes against cancer suggest promising anticancer efficacy of agents from natural sources.

关键词： Natural compounds Capsaicin Curcumin Diindolylmethane(DIM) Isothiocyanate Piperine Deguelin Cucurbitacin B Cancer

Comparison of the chloride channel activator lubiprostone and the oral laxative Polyethylene Glycol 3350 on mucosal barrier repair in ischemic-injured porcine intestine

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World Journal of Gastroenterology 2008年第39期14卷 6012-6017页

作者： Adam J Moeser Prashant k Nighot Birgit Roerig Ryuji Ueno Anthony T Blikslager Department of Population Health and Pathobiology College of Veterinary MedicineNorth Carolina State UniversityRaleigh NC 27606United States Department of Clinical Sciences College of Veterinary MedicineNorth Carolina State UniversityRaleigh NC 27606United States Sucampo Pharmaceuticals IncBethesda MD 20814United States

AIM： To investigate the effects of lubiprostone and Polyethylene Glycol 3350 （PEG） on mucosal barrier repair in ischernic-injured porcine intestine. METHODS： Ileum from 6 piglets （approximately 15 kg body weight） was subjected to ischemic conditions by occluding the local rnesenteric circulation for 45 min in vivo. Ileal tissues from each pig were then harvested and mounted in Ussing chambers and bathed in oxygenated Ringer＇s solution in vitro. Intestinal barrier function was assessed by measuring transepithelial electrical resistance （TER） and mucosal-to-serosal fluxes of ^3H-rnannitol and ^14C-inulin. Statistical analyses of data collected over a 120-min time course included 2-way ANOVA for the effects of time and treatment on indices of barrier function. RESULTS： Application of 1μmol/L lubiprostone to the rnucosal surface of ischemic-injured ileum in vitro induced significant elevations in TER compared to nontreated tissue. Lubiprostone also reduced mucosal-toserosal fluxes of ^3H-rnannitol and ^14C-inulin. Alternatively, application of a polyethylene laxative （PEG, 20 rnmol/L） to the mucosal surface of ischernic tissues significantly increased flux of ^3H-rnannitol and ^14C-inulin. CONCLUSION： This experiment demonstrates that lubiprostone stimulates recovery of barrier function in ischemic intestinal tissues whereas the PEG laxative had deleterious effects on mucosal repair. These results suggest that, unlike osmotic laxatives, lubiprostone stimulates repair of the injured intestinal barrier.

关键词： Intestinal ischemia Barrier function Permeability Laxative Polyethylene Glycol