This study is based on the Tong sheep obtained by the random sampling method of typical colonies in the central area of Baishui County in Shaanxi Province, China. An investigation was undertaken to clarify the gene co...This study is based on the Tong sheep obtained by the random sampling method of typical colonies in the central area of Baishui County in Shaanxi Province, China. An investigation was undertaken to clarify the gene constitution of blood protein and nonprotein types of Tong sheep. Twelve genetic markers were examined by starch-gel electrophoresis and cellulose acetate electrophoresis. Polymorphism in Tong sheep was found at the following 10 loci, transferrin (Tf), alkaline phosphatase (Alp), leucine aminopeptidase (Lap), arylesterase (Ary-Es), hemoglobin-β (Hb-β), X-protein (X-p), carbonic anhydrase (CA), catalase (Cat), malate dehydrogenase (MDH), and lysine (Ly), whereas, albumin (A1) and postalbumin (Po) loci were monomorphic. Genetic approach degree method and phylogenetic relationship clustering method were used to judge the origin and phylogenetic status of Tong sheep. Results from both methods maintained that Tong sheep belonged to the "Mongolia group", and Mongolia sheep was the origin of Tong sheep. This was also supported by the history of Tong sheep breeding. Compared to the phylogenetic relationship clustering method, the genetic approach degree method was more reliable for the extraction from East and South of Central Asia, and was more effective in reflecting the breeding course of Tong sheep.展开更多
Based on salient visual regions for mobile robot navigation in unknown environments, a new place recognition system was presented. The system uses monocular camera to acquire omni-directional images of the environment...Based on salient visual regions for mobile robot navigation in unknown environments, a new place recognition system was presented. The system uses monocular camera to acquire omni-directional images of the environment where the robot locates. Salient local regions are detected from these images using center-surround difference method, which computes opponencies of color and texture among multi-scale image spaces. And then they are organized using hidden Markov model (HMM) to form the vertex of topological map. So localization, that is place recognition in our system, can be converted to evaluation of HMM. Experimental results show that the saliency detection is immune to the changes of scale, 2D rotation and viewpoint etc. The created topological map has smaller size and a higher ratio of recognition is obtained.展开更多
To enhance the security of user data in the clouds,we present an adaptive and dynamic data encryption method to encrypt user data in the mobile phone before it is uploaded.Firstly,the adopted data encryption algorithm...To enhance the security of user data in the clouds,we present an adaptive and dynamic data encryption method to encrypt user data in the mobile phone before it is uploaded.Firstly,the adopted data encryption algorithm is not static and uniform.For each encryption,this algorithm is adaptively and dynamically selected from the algorithm set in the mobile phone encryption system.From the mobile phone's character,the detail encryption algorithm selection strategy is confirmed based on the user's mobile phone hardware information,personalization information and a pseudo-random number.Secondly,the data is rearranged with a randomly selected start position in the data before being encrypted.The start position's randomness makes the mobile phone data encryption safer.Thirdly,the rearranged data is encrypted by the selected algorithm and generated key.Finally,the analysis shows this method possesses the higher security because the more dynamics and randomness are adaptively added into the encryption process.展开更多
Based on the large-scale model tests, a simplified dam breach model for homogeneous cohesive dam due to overtopping failure is put forward. The model considers headcut erosion as one of the key homogeneous cohesive da...Based on the large-scale model tests, a simplified dam breach model for homogeneous cohesive dam due to overtopping failure is put forward. The model considers headcut erosion as one of the key homogeneous cohesive dam breaching mechanisms and we calculate the time-averaged headcut migration rate using an energy-based empirical formula. A numerical method is adopted to determine the initial scour position at the downstream slope in terms of the water head and dam height, and the broad-crested weir equation is utilized to simulate the breach flow. The limit equilibrium method is used to analyze the stability of breach slope during the breach process. An iterative method is developed to simulate the coupling process of soil and water at each time step. The calculated results of three dam breach cases testify the reasonability of the model, and the sensitivity studies of soil erodibility show that sensitivity is dependent on each test case's soil conditions. In addition, three typical dam breach models, NWS BREACH, WinDAM B, and HR BREACH, are also chosen to compare with the proposed model. It is found that NWS BREACH may have large errors for cohesive dams, since it uses a noncohesive sediment transport model and does notconsider headcut erosion, WinDAM B and HR BREACH consider headcut erosion as the breaching mechanism and handle well homogeneous cohesive dam overtopping failure, but overall, the proposed model has the best performance.展开更多
Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contrac...Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contraction. A prediction method of ground surface displacement was developed. The reliability of the presented method was validated through a comparison between theoretical results and results from engineering practice. Results show that the present method is effective. The effect of parameters on uplift displacement was illustrated under different grouting conditions. Through analysis, it can be known that the ground surface uplift is mainly caused by osmosis of slurry and the primary influence angle of stratum β determines the influence range of surface uplift. Besides, the results show that ground surface uplift displacement decreases notably with increasing depth of the grouting cavity but it increases with increasing diffusion radius of grout and increasing grouting pressure.展开更多
The CD80 (B7-1) costimulatory molecule is expressed on the surface of B cells and its expression is transcriptionally upregulated upon stimuli. To identify the region of murine CD80 promoter that direct cell type sp...The CD80 (B7-1) costimulatory molecule is expressed on the surface of B cells and its expression is transcriptionally upregulated upon stimuli. To identify the region of murine CD80 promoter that direct cell type specific gene expression, four promoters construct of CD80 gene were generated with DNA fragments fused to the GFP reporter gene. In the present study, significant promoter activity was detected with all four promoter constructs only in the murine B lymphocyte. Further, the CD80 promoter region extending from -3,005 bp to +273 bp in relation to the previously reported transcription start site, was identified as tissue specific region. Interestingly, the shortest 700 bp (-427/+273) of promoter fragment was sufficient to direct the CD80 gene expression. The level of CD80 expression was also found to be modulated by exogenous stimuli in B lymphocyte. Additionally, it was demonstrated that the CD80 gene expression is regulated at the level of transcription where the inducible CD80 gene transcript was detected in B lymphocyte with increasing time.展开更多
Combining a progressive tandem junction design with a unique Si nanowire(SiNW)framework paves the way for the development of high‐onset‐potential photocathodes and enhancement of solar hydrogen production.Herein,a r...Combining a progressive tandem junction design with a unique Si nanowire(SiNW)framework paves the way for the development of high‐onset‐potential photocathodes and enhancement of solar hydrogen production.Herein,a radial tandem junction(RTJ)thin film water‐splitting photo‐cathode has been demonstrated experimentally for the first time.The photocathode is directly fab‐ricated on vapor‐liquid‐solid‐grown SiNWs and consists of two radially stacked p‐i‐n junctions,featuring hydrogenated amorphous silicon(a‐Si:H)as the outer absorber layer,which absorbs short wavelengths,and hydrogenated amorphous silicon germanium(a‐SiGe:H)as the inner layer,which absorbs long wavelengths.The randomly distributed SiNW framework enables highly efficient light‐trapping,which facilitates the use of very thin absorber layers of a‐Si:H(~50 nm)and a‐SiGe:H(~40 nm).In a neutral electrolyte(pH=7),the three‐dimensional(3D)RTJ photocathode delivers a high photocurrent onset of 1.15 V vs.the reversible hydrogen electrode(RHE),accompanied by a photocurrent of 2.98 mA/cm^(2) at 0 V vs.RHE,and an overall applied‐bias photon‐to‐current effi‐ciency of 1.72%.These results emphasize the promising role of 3D radial tandem technology in developing a new generation of durable,low‐cost,high‐onset‐potential photocathodes capable of large‐scale implementation。展开更多
Using the technique of smooth filtering and cylindrical filtering,the initial vortex circulation and large-scale environmental field were separated from the background field.Then the separated initial vortex circulati...Using the technique of smooth filtering and cylindrical filtering,the initial vortex circulation and large-scale environmental field were separated from the background field.Then the separated initial vortex circulation was translated and reinserted in the location where it was observed.This led to the determination of a method of initial vortex relocation.For seven tropical cyclones at 23 points of measurement time in the years of 2006 and 2007,two schemes,either directly adding a tropical cyclone bogus model in the background or adding it after the relocation of the initial vortex in the background field,were employed.Simulation experiments were compared.The results showed that the mean errors of the simulated tropical cyclone tracks at 24 and 48 hours were both smaller with the scheme of adding tropical cyclone bogus model after the relocation of the initial vortex in the background field.The relocation method of the initial vortex decreases the error caused by the deviation of the initial tropical cyclone location in tropical cyclone models.The relocation method is conducive to improving the track forecast of tropical cyclone models and has a good perspective for operational application.展开更多
The authors have proposed a new of magnetic isotope theory of life on Earth. According to this theory the initial impetus for the beginning of the synthesis of organic compounds is the impact of electromagnetic radiat...The authors have proposed a new of magnetic isotope theory of life on Earth. According to this theory the initial impetus for the beginning of the synthesis of organic compounds is the impact of electromagnetic radiation from the sun and energy radioactive isotopes.展开更多
In the Dongting water system, the Carassius auratus(Crucian carp) complex is characterized by the coexistence of diploid forms(2n=100, 2n CC) and polyploid forms. Chromosomal and karyotypic analyses have suggested tha...In the Dongting water system, the Carassius auratus(Crucian carp) complex is characterized by the coexistence of diploid forms(2n=100, 2n CC) and polyploid forms. Chromosomal and karyotypic analyses have suggested that the polyploid C. auratus has a triploid(3n=150, 3n CC) and a tetraploid origin(4n=200), respectively. However, there is a lack of direct genetic evidence to support this conclusion. In this paper, analysis of the 5S r DNA chromosomal locus revealed that the 3n CC is of triploid origin. Analysis of the species-specific chromosomal centromere locus revealed that 3n CC individuals possess three sets of C. auratus-derived chromosomes. Our results provide direct cytogenetic evidence suggesting that individuals with 150 chromosomes are of autotriploid origin within the C. auratus complex. It marks an important contribution to the study of polyploidization and the evolution of vertebrates.展开更多
Objective: We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ven...Objective: We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Methods: Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Results: Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MVVT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, P〈0.05). However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. Conclusions: RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.展开更多
A correlation study between the observed surface morphology using high-resolution scanning electron microscopy(HRSEM) and the observed structural imperfections using transmission electron microscopy(TEM) has been cond...A correlation study between the observed surface morphology using high-resolution scanning electron microscopy(HRSEM) and the observed structural imperfections using transmission electron microscopy(TEM) has been conducted for a-plane Ga N. There are three different sized asymmetric surface pits: large pit of 500 nm–2 ?m in side length, medium pit of 50 nm in side length, and small pit with side lengths of less than 5 nm, which originate from incomplete island coalescence, screw dislocation, and partial dislocation(PD), respectively. Both screw dislocation and PD can produce pits on the free surface because they have a perpendicular line tension to the surface, which must remain in balance with the surface tension. The two types of dislocation lead to distinctive pit sizes because the PD has a smaller Burgers vector component along the dislocation line than the pure screw dislocation. A pit that is produced in the island-coalescing process is much larger than those caused by dislocations because island coalescence is a kinetic process that involves large-scale mass transportation, whereas the dislocation mediates the surface in the local area. These three types of surface pits sometimes interact with one another in space. The coalescence of the island determines the surface morphology at large scales, whereas the defects affect the details.展开更多
Seed-mediated growth is the most general way to controllably synthesize bimetal nano-heterostructures. Despite successful instances through trial and error were reported, the way for second metal depositing on the see...Seed-mediated growth is the most general way to controllably synthesize bimetal nano-heterostructures. Despite successful instances through trial and error were reported, the way for second metal depositing on the seed. namely whether the symmetry of resulted nano-heterostructure follows the original crystal symmetry of seed metal, remains an unpredictable issue to date. In this work, we propose that the ther- modynamic factor, i.e., the difference of equilibrium electrochemical potentials (corresponding to their Fermi levels) of two metals in the growth solution, plays a key role for the symmetry breaking of bimetal nano-heterostructures during the seed-mediated growth. As a proof-of-principle experiment, by revers- ing the relative position of Fermi levels of the Pd nanocube seeds and the second metal Au with changing the concentration of reductant (L-ascorbic acid) in the growth solution, the structure of as-prepared prod- ucts successfully evolved from centrosymmetric Pd@Au core-shell trisoctabedra to asymmetric Pd-Au hetero-dimers. The idea was further demonstrated by the growth of Ag on the Pd seeds. The present work intends to reveal the origin of symmetry breaking in the seed-mediated growth of nano-heterostructures from the viewpoint of thermodynamics, and these new insights will in turn help to achieve rational con- struction of bimetal nano-heterostructures with soecific functions.展开更多
Spin-polarized density functional theory (DPT) calculations are carried out to determine the site preference of H adsorption on Pd(100) surface and subsurface, We carefully scrutinize the energy difference between...Spin-polarized density functional theory (DPT) calculations are carried out to determine the site preference of H adsorption on Pd(100) surface and subsurface, We carefully scrutinize the energy difference between different patterns at θ=0.50 ML and confirm the LEED observation that surface adsorption can form c(2×2) ordering structure. On the contrary, we disclose that p(2×1) structure become more favorable than c(2×2) for subsurface adsorption. These site preferences are rationalized via an analysis of the layer and orbital resolved density of states. Furthermore, we propose that the interstitial charge as a key factor determining the preferred H adsorbed site.展开更多
Boron concentrations and isotope compositions have been measured for 93 water samples from the hot springs and drill-holes in the geothermal system in the Yunnan-Tibet Geothermal Belt(YTGB),China.Boron concentrations ...Boron concentrations and isotope compositions have been measured for 93 water samples from the hot springs and drill-holes in the geothermal system in the Yunnan-Tibet Geothermal Belt(YTGB),China.Boron concentrations range from 0.036–472.4ppm,and theδ11B values range from -16.0‰to 13.1‰,indicating the non-marine origin for each geothermal system.We observed a clear binary mixing relationship between the B concentrations and B isotope compositions in Tibet geothermal area.This relationship can be well explained by two sources,i.e.,marine carbonate rocks and magmatic rocks,for the Tibet geothermal water.No evidence supports a mantle contribution to B.In addition,we found that the precipitation only plays a dilution role for B of geothermal waters.δ11B values for the precipitation across the southern Tibetan Plateau area range from -6.0‰ to -6.8‰at least.Due to data scarcity in Yunnan geothermal area,we observed possible different boron sources from the Tibet geothermal system.Comparing it with other geothermal systems in the world,we found that the samples from YTGB have the lowestδ11B values and the largest range of B concentration,which might be related to their special geological background.On the whole,the world geothermalδ11B-Cl/B relation suggests a mixing process between marine and non-marine sources.Additionally,we suggest that B source of B-enriched geothermal waters is mainly from B-enriched crustal country-rocks,instead of mantle.展开更多
基金the International Cooperation Item of the National Natural Science Foundation of China (No. 30213009, 30310103007, 30410103150)Natural Science Foundation of Jiangsu Province of China (No. BK2007556)+1 种基金Basic Natura Science Foundation for Colleges and Universities Jiangsu Province (No. NK051039) the New Century Talent Project of Yangzhou University in China.
文摘This study is based on the Tong sheep obtained by the random sampling method of typical colonies in the central area of Baishui County in Shaanxi Province, China. An investigation was undertaken to clarify the gene constitution of blood protein and nonprotein types of Tong sheep. Twelve genetic markers were examined by starch-gel electrophoresis and cellulose acetate electrophoresis. Polymorphism in Tong sheep was found at the following 10 loci, transferrin (Tf), alkaline phosphatase (Alp), leucine aminopeptidase (Lap), arylesterase (Ary-Es), hemoglobin-β (Hb-β), X-protein (X-p), carbonic anhydrase (CA), catalase (Cat), malate dehydrogenase (MDH), and lysine (Ly), whereas, albumin (A1) and postalbumin (Po) loci were monomorphic. Genetic approach degree method and phylogenetic relationship clustering method were used to judge the origin and phylogenetic status of Tong sheep. Results from both methods maintained that Tong sheep belonged to the "Mongolia group", and Mongolia sheep was the origin of Tong sheep. This was also supported by the history of Tong sheep breeding. Compared to the phylogenetic relationship clustering method, the genetic approach degree method was more reliable for the extraction from East and South of Central Asia, and was more effective in reflecting the breeding course of Tong sheep.
基金Projects(60234030 ,60404021) supported by the National Natural Science Foundation of China
文摘Based on salient visual regions for mobile robot navigation in unknown environments, a new place recognition system was presented. The system uses monocular camera to acquire omni-directional images of the environment where the robot locates. Salient local regions are detected from these images using center-surround difference method, which computes opponencies of color and texture among multi-scale image spaces. And then they are organized using hidden Markov model (HMM) to form the vertex of topological map. So localization, that is place recognition in our system, can be converted to evaluation of HMM. Experimental results show that the saliency detection is immune to the changes of scale, 2D rotation and viewpoint etc. The created topological map has smaller size and a higher ratio of recognition is obtained.
文摘To enhance the security of user data in the clouds,we present an adaptive and dynamic data encryption method to encrypt user data in the mobile phone before it is uploaded.Firstly,the adopted data encryption algorithm is not static and uniform.For each encryption,this algorithm is adaptively and dynamically selected from the algorithm set in the mobile phone encryption system.From the mobile phone's character,the detail encryption algorithm selection strategy is confirmed based on the user's mobile phone hardware information,personalization information and a pseudo-random number.Secondly,the data is rearranged with a randomly selected start position in the data before being encrypted.The start position's randomness makes the mobile phone data encryption safer.Thirdly,the rearranged data is encrypted by the selected algorithm and generated key.Finally,the analysis shows this method possesses the higher security because the more dynamics and randomness are adaptively added into the encryption process.
基金Natural Science Foundation of China(Grant No.51379129,51539006,51509164)
文摘Based on the large-scale model tests, a simplified dam breach model for homogeneous cohesive dam due to overtopping failure is put forward. The model considers headcut erosion as one of the key homogeneous cohesive dam breaching mechanisms and we calculate the time-averaged headcut migration rate using an energy-based empirical formula. A numerical method is adopted to determine the initial scour position at the downstream slope in terms of the water head and dam height, and the broad-crested weir equation is utilized to simulate the breach flow. The limit equilibrium method is used to analyze the stability of breach slope during the breach process. An iterative method is developed to simulate the coupling process of soil and water at each time step. The calculated results of three dam breach cases testify the reasonability of the model, and the sensitivity studies of soil erodibility show that sensitivity is dependent on each test case's soil conditions. In addition, three typical dam breach models, NWS BREACH, WinDAM B, and HR BREACH, are also chosen to compare with the proposed model. It is found that NWS BREACH may have large errors for cohesive dams, since it uses a noncohesive sediment transport model and does notconsider headcut erosion, WinDAM B and HR BREACH consider headcut erosion as the breaching mechanism and handle well homogeneous cohesive dam overtopping failure, but overall, the proposed model has the best performance.
基金Project(51478478) supported by the National Natural Science Foundation of ChinaProject(IRT1296) supported by the Program for Changjiang Scholars and Innovative Research Team(PCSIRT) in University,China
文摘Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contraction. A prediction method of ground surface displacement was developed. The reliability of the presented method was validated through a comparison between theoretical results and results from engineering practice. Results show that the present method is effective. The effect of parameters on uplift displacement was illustrated under different grouting conditions. Through analysis, it can be known that the ground surface uplift is mainly caused by osmosis of slurry and the primary influence angle of stratum β determines the influence range of surface uplift. Besides, the results show that ground surface uplift displacement decreases notably with increasing depth of the grouting cavity but it increases with increasing diffusion radius of grout and increasing grouting pressure.
文摘The CD80 (B7-1) costimulatory molecule is expressed on the surface of B cells and its expression is transcriptionally upregulated upon stimuli. To identify the region of murine CD80 promoter that direct cell type specific gene expression, four promoters construct of CD80 gene were generated with DNA fragments fused to the GFP reporter gene. In the present study, significant promoter activity was detected with all four promoter constructs only in the murine B lymphocyte. Further, the CD80 promoter region extending from -3,005 bp to +273 bp in relation to the previously reported transcription start site, was identified as tissue specific region. Interestingly, the shortest 700 bp (-427/+273) of promoter fragment was sufficient to direct the CD80 gene expression. The level of CD80 expression was also found to be modulated by exogenous stimuli in B lymphocyte. Additionally, it was demonstrated that the CD80 gene expression is regulated at the level of transcription where the inducible CD80 gene transcript was detected in B lymphocyte with increasing time.
文摘Combining a progressive tandem junction design with a unique Si nanowire(SiNW)framework paves the way for the development of high‐onset‐potential photocathodes and enhancement of solar hydrogen production.Herein,a radial tandem junction(RTJ)thin film water‐splitting photo‐cathode has been demonstrated experimentally for the first time.The photocathode is directly fab‐ricated on vapor‐liquid‐solid‐grown SiNWs and consists of two radially stacked p‐i‐n junctions,featuring hydrogenated amorphous silicon(a‐Si:H)as the outer absorber layer,which absorbs short wavelengths,and hydrogenated amorphous silicon germanium(a‐SiGe:H)as the inner layer,which absorbs long wavelengths.The randomly distributed SiNW framework enables highly efficient light‐trapping,which facilitates the use of very thin absorber layers of a‐Si:H(~50 nm)and a‐SiGe:H(~40 nm).In a neutral electrolyte(pH=7),the three‐dimensional(3D)RTJ photocathode delivers a high photocurrent onset of 1.15 V vs.the reversible hydrogen electrode(RHE),accompanied by a photocurrent of 2.98 mA/cm^(2) at 0 V vs.RHE,and an overall applied‐bias photon‐to‐current effi‐ciency of 1.72%.These results emphasize the promising role of 3D radial tandem technology in developing a new generation of durable,low‐cost,high‐onset‐potential photocathodes capable of large‐scale implementation。
基金Natural Science Foundation of China (9101501190715031+2 种基金40875026)Team Project of Foundation of Natural Science of Guangdong Province(8351030101000002)Project of Science and Technology of Guangdong Province(2008B030303025)
文摘Using the technique of smooth filtering and cylindrical filtering,the initial vortex circulation and large-scale environmental field were separated from the background field.Then the separated initial vortex circulation was translated and reinserted in the location where it was observed.This led to the determination of a method of initial vortex relocation.For seven tropical cyclones at 23 points of measurement time in the years of 2006 and 2007,two schemes,either directly adding a tropical cyclone bogus model in the background or adding it after the relocation of the initial vortex in the background field,were employed.Simulation experiments were compared.The results showed that the mean errors of the simulated tropical cyclone tracks at 24 and 48 hours were both smaller with the scheme of adding tropical cyclone bogus model after the relocation of the initial vortex in the background field.The relocation method of the initial vortex decreases the error caused by the deviation of the initial tropical cyclone location in tropical cyclone models.The relocation method is conducive to improving the track forecast of tropical cyclone models and has a good perspective for operational application.
文摘The authors have proposed a new of magnetic isotope theory of life on Earth. According to this theory the initial impetus for the beginning of the synthesis of organic compounds is the impact of electromagnetic radiation from the sun and energy radioactive isotopes.
基金supported by the National Natural Science Foundation of China (31201987, 31430088, 31210103918)the Doctoral Fund of Ministry of Education of China (20124306120006)+4 种基金the Natural Science Foundation of Hunan Province (14JJ6008)Training Program of the Major Research Plan of the National Natural Science Foundation of China (91331105)the National Key Basic Research Program of China (2012CB722305)the Cooperative Innovation Center of Engineering and New Products for Developmental Biology (20134486)the Construct Program of the Key Discipline in Hunan Province, China
文摘In the Dongting water system, the Carassius auratus(Crucian carp) complex is characterized by the coexistence of diploid forms(2n=100, 2n CC) and polyploid forms. Chromosomal and karyotypic analyses have suggested that the polyploid C. auratus has a triploid(3n=150, 3n CC) and a tetraploid origin(4n=200), respectively. However, there is a lack of direct genetic evidence to support this conclusion. In this paper, analysis of the 5S r DNA chromosomal locus revealed that the 3n CC is of triploid origin. Analysis of the species-specific chromosomal centromere locus revealed that 3n CC individuals possess three sets of C. auratus-derived chromosomes. Our results provide direct cytogenetic evidence suggesting that individuals with 150 chromosomes are of autotriploid origin within the C. auratus complex. It marks an important contribution to the study of polyploidization and the evolution of vertebrates.
基金Project supported by the National Natural Science Foundation of China(Nos.30900604 and 81270004)the Shanghai Natural Science Foundation(No.11ZR1422800)+1 种基金the Medical Key Project of Shanghai Science and Technology Commission(No.12411952100)the New Outstanding Youth Program of Shanghai Municipal Commission of Health and Family Planning(No.XYQ2013105),China
文摘Objective: We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Methods: Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Results: Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MVVT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, P〈0.05). However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. Conclusions: RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.
基金supported by the National Natural Science Foundation of China(Grant Nos.11204009&61204011)Beijing Municipal Natural Science Foundation(Grant No.4142005)
文摘A correlation study between the observed surface morphology using high-resolution scanning electron microscopy(HRSEM) and the observed structural imperfections using transmission electron microscopy(TEM) has been conducted for a-plane Ga N. There are three different sized asymmetric surface pits: large pit of 500 nm–2 ?m in side length, medium pit of 50 nm in side length, and small pit with side lengths of less than 5 nm, which originate from incomplete island coalescence, screw dislocation, and partial dislocation(PD), respectively. Both screw dislocation and PD can produce pits on the free surface because they have a perpendicular line tension to the surface, which must remain in balance with the surface tension. The two types of dislocation lead to distinctive pit sizes because the PD has a smaller Burgers vector component along the dislocation line than the pure screw dislocation. A pit that is produced in the island-coalescing process is much larger than those caused by dislocations because island coalescence is a kinetic process that involves large-scale mass transportation, whereas the dislocation mediates the surface in the local area. These three types of surface pits sometimes interact with one another in space. The coalescence of the island determines the surface morphology at large scales, whereas the defects affect the details.
基金supported by the National Basic Research Program of China(2015CB93230)the National Key Research and Development Program of China(2017YFA0206801)+1 种基金the National Natural Science Foundation of China(21333008,21671163,21721001,and 21773190)the Fundamental Research Funds for the Central Universities(20720160026)
文摘Seed-mediated growth is the most general way to controllably synthesize bimetal nano-heterostructures. Despite successful instances through trial and error were reported, the way for second metal depositing on the seed. namely whether the symmetry of resulted nano-heterostructure follows the original crystal symmetry of seed metal, remains an unpredictable issue to date. In this work, we propose that the ther- modynamic factor, i.e., the difference of equilibrium electrochemical potentials (corresponding to their Fermi levels) of two metals in the growth solution, plays a key role for the symmetry breaking of bimetal nano-heterostructures during the seed-mediated growth. As a proof-of-principle experiment, by revers- ing the relative position of Fermi levels of the Pd nanocube seeds and the second metal Au with changing the concentration of reductant (L-ascorbic acid) in the growth solution, the structure of as-prepared prod- ucts successfully evolved from centrosymmetric Pd@Au core-shell trisoctabedra to asymmetric Pd-Au hetero-dimers. The idea was further demonstrated by the growth of Ag on the Pd seeds. The present work intends to reveal the origin of symmetry breaking in the seed-mediated growth of nano-heterostructures from the viewpoint of thermodynamics, and these new insights will in turn help to achieve rational con- struction of bimetal nano-heterostructures with soecific functions.
基金supported by the National Nature Science Foundation of China(21131005,20925103,21373167,21033006,21133004,21333008)the Fundamental Research Funds of Central Universities
文摘Spin-polarized density functional theory (DPT) calculations are carried out to determine the site preference of H adsorption on Pd(100) surface and subsurface, We carefully scrutinize the energy difference between different patterns at θ=0.50 ML and confirm the LEED observation that surface adsorption can form c(2×2) ordering structure. On the contrary, we disclose that p(2×1) structure become more favorable than c(2×2) for subsurface adsorption. These site preferences are rationalized via an analysis of the layer and orbital resolved density of states. Furthermore, we propose that the interstitial charge as a key factor determining the preferred H adsorbed site.
基金supported by National Natural Science Foundation of China(Grant Nos.41203012,41030317)China Geological Survey(Grant No.1212011085524)
文摘Boron concentrations and isotope compositions have been measured for 93 water samples from the hot springs and drill-holes in the geothermal system in the Yunnan-Tibet Geothermal Belt(YTGB),China.Boron concentrations range from 0.036–472.4ppm,and theδ11B values range from -16.0‰to 13.1‰,indicating the non-marine origin for each geothermal system.We observed a clear binary mixing relationship between the B concentrations and B isotope compositions in Tibet geothermal area.This relationship can be well explained by two sources,i.e.,marine carbonate rocks and magmatic rocks,for the Tibet geothermal water.No evidence supports a mantle contribution to B.In addition,we found that the precipitation only plays a dilution role for B of geothermal waters.δ11B values for the precipitation across the southern Tibetan Plateau area range from -6.0‰ to -6.8‰at least.Due to data scarcity in Yunnan geothermal area,we observed possible different boron sources from the Tibet geothermal system.Comparing it with other geothermal systems in the world,we found that the samples from YTGB have the lowestδ11B values and the largest range of B concentration,which might be related to their special geological background.On the whole,the world geothermalδ11B-Cl/B relation suggests a mixing process between marine and non-marine sources.Additionally,we suggest that B source of B-enriched geothermal waters is mainly from B-enriched crustal country-rocks,instead of mantle.