检索结果-南通市图书馆

Challenges in engineering the structure of ionic liquids towards direct air capture of CO_(2)

在线全文

学校读者我要写书评

暂无评论

Green Chemical Engineering 2021年第4期2卷 342-345页

作者： Zhenzhen Yang sheng dai Chemical Sciences Division Oak Ridge National LaboratoryOak RidgeTN37831USA Department of Chemistry Joint Institute for Advanced MaterialsThe University of TennesseeKnoxvilleTN37996USA

*** Man-made perturbations over emissions of greenhouse gas(GHG)bring tremendous negative impacts on the survival environment[1].CO_(2)accounts for~75%of global GHG impacts with others mainly composed of N_(2)O,CH_(4),and small fluorinated gas molecules[2].Deployment of“negative emission”technologies via direct air capture(DAC)of CO_(2)by engineered chemical reactions represents one of the most promising and distinct pathways to limit and alleviate the global warming trend[3].

关键词： Ionic liquid Carbon dioxide Direct air capture of CO_(2) Uptake capacity Reaction enthalpy

Turbulence properties in the solar convection envelope:properties of the overshooting regions

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2009年第5期9卷 585-595页

作者： qian-sheng Zhang Yan Li National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

We apply the turbulent convection model （TCM） to investigate properties of turbulence in the solar convective envelope, especially in overshooting regions. The results show TCM gives negative turbulent heat flux uτ＇T＇ in overshooting regions, which is similar to other nonlocal turbulent convection theories. The turbulent temperature fluctuation T＇T＇ shows peaks in overshooting regions. Most important, we find that the downward overshooting region below the base of the solar convection zone is a thin cellular layer filled with roll-shaped convective cells. The overshooting length for the temperature gradient is much shorter than that for element mixing because turbulent heat flux of downward and upward moving convective cells counteract each other in this cellular overshooting region. Comparing the models＇ sound speed with observations, we find that taking the convective overshooting into account helps to improve the sound speed profile of our nonlocal solar models. Comparing the p-mode oscillation frequencies with observations, we validated that increasing the diffusion parameters and decreasing the dissipation parameters of TCM make the p-mode oscillation frequencies of the solar model be in better agreement with observations.

关键词： convection - turbulence - Sun helioseismology

Two particular EA-type binaries in the globular cluster ω Centauri

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2013年第7期13卷 827-834页

作者： Kai Li sheng-Bang qian National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences University of Chinese Academy of Sciences

We analyzed the B and V light curves of two EA-type binaries V211 and NV358 for the first time using the Wilson-Devinney code. Our analysis shows that V211 is a typical Algol-type binary and NV358 is a well detached binary system. As the two binaries are definite members of ω Centauri due to their proper motion, we estimated their physical parameters, obtaining M1 = 1.13 4±0.03 M⊙, R1 = 0.98±0.01 R⊙, M2 = 0.33 ±0.01 M⊙ and R2 = 0.92 ±0.01 R⊙ forV211; M1 = 1.304-0.05 M⊙, R1 = 1.03±0.01 R⊙, M2 = 0.58±0.02 M⊙ and R2 = 0.78±0.01 R⊙ for NV358. On the color-magnitude diagram of ω Centauri, V211 is located in the faint blue straggler region and its primary component is more massive than a star at the main-sequence turnoff. Therefore, V211 is a blue straggler and was formed by mass transfer from the secondary component to the primary. The age of NV358 is less than 1.93 Gyr, indicating that it is much younger than the first generation of stars in ω Centaufi. Like NV364 in ω Centaufi, NV358 should be a second-generation binary.

关键词： galaxies: globular clusters: individual (ω Centauri) - stars: binaries:close - stars: binaries: eclipsing - stars: blue stragglers - stars: individual (V211 NV358)

Synthesis of High Molecular Weight Polyethylene and E-MA Copolymers Using Iminopyridine Ni(Ⅱ) and Pd(Ⅱ) Complexes Containing a Flexible Backbone and Rigid Axial Substituents

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第2期41卷 233-239页

作者： Yu-Dan Liao Qi Cai sheng-Yu dai School of Chemical and Environmental Engineering Anhui Polytechnic UniversityWuhu241000China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationAnhui UniversityHefei230601China

Suppressing the chain transfer reactions during polymerization in late-transition metal-catalyzed olefin polymerization systems is the key to obtaining high molecular weight polyolefin materials. In this work, two efficient strategies(“sandwich” and rotation-restricted strategies)to retard chain transfer reactions in ethylene(co)polymerization were employed for the iminopyridyl system. Herein, a family of iminopyridyl Ni(Ⅱ)and Pd(Ⅱ) complexes with a flexible backbone and rigid axial bulky aryl substituents were designed, synthesized and characterized. In ethylene polymerization, the iminopyridyl Ni(Ⅱ) and Pd(Ⅱ) catalysts using the two strategies exhibited reasonable activities and generated highly branched polyethylenes with high molecular weights, where catalysts with dibenzosuberyl substituents exhibited significantly higher activities and produced higher molecular weight polyethylene than catalysts with 8-arylnaphthalenyl substituent. A similar trend of activities and molecular weights was also found in the copolymerization of ethylene with MA using the Pd(Ⅱ) catalysts. Moreover, highly branched E-MA copolymers with moderate to high molecular weights and high incorporation ratios(up to 17.4 mol%) were generated with the two Pd(Ⅱ) catalysts. Most interestingly, as compared with the dibenzhydryl Ni(Ⅱ) and Pd(Ⅱ) catalysts, the catalysts using the two strategies exhibited a superior ability to retard the chain transfer reactions and generated polymers and copolymers with 1-2 orders of magnitude higher molecular weights during ethylene(co)polymerization.

关键词： Ni(Ⅱ)and Pd(Ⅱ) Suppressing chain transfer High molecular weight Ethylene(co)polymerization

Strong evidence for latitudinal diversity gradient in mosses across the world

在线全文

学校读者我要写书评

暂无评论

Plant Diversity 2024年第4期46卷 537-541页

作者： Hong qian Zun dai Jian Wang Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA Bryology Laboratory School of Life SciencesEast China Normal UniversityShanghai 200241China Shanghai Institute of Eco-Chongming(SIEC) 3663 Northern Zhongshan RoadShanghai 200062China

Species richness generally decreases with increasing latitude,a biodiversity gradient that has long been considered as one of the few laws in *** latitudinal diversity gradient has been observed in many major groups of *** plants,the latitudinal diversity gradient has been observed in vascular plants,angiosperms,ferns,and ***,a conspicuous latitudinal diversity gradient in mosses at a global or continental scale has not been observed until ***,we analyze a comprehensive data set including moss species in each band of 20° in latitude *** results show that moss species richness decreases strongly with increasing latitude,regardless of whether the globe is considered as a whole or different longitudinal segments(e.g.,Old World versus New World) are considered *** result holds when variation in area size among latitudinal bands is taken into ***'s correlation coefficient between latitude and species richness is-0.99 for both the Northern and Southern *** bryophytes are an extant lineage of early land plants and because mosses not only include most of extant species of bryophytes but also are important constituents of most terrestrial ecosystems,understanding geographic patterns of mosses is particularly important The finding of our study fills a critical knowledge gap.

关键词： Bryophyte Latitudinal diversity gradient Moss Species density Species diversity

Pure Total Flavonoids from Citrus paradisi Macfad InduceLeukemia Cell Apoptosis In Vitro

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Integrative Medicine 2017年第5期23卷 370-375页

作者： dai Tie-ying WANG Bo LIN sheng-yun JIANG Jian-ping WU Li-qiang qian Wen-bing Department of Hematology the First Hospital Affiliated to Zhejiang University of Traditional Chinese Medicine Department of Hematology the First Affiliated Hospital of Medical School of Zhejiang University

Objective： To investigate the potential effect of pure total flavonoids from Citrus paradisi Macfad peel（PTFC） on the proliferation and apoptosis of human myeloid leukemia cells Kasumi-1, HL-60 and K562, and the underlying mechanisms. Methods： PTFC was extracted from Citrus paradisi Macfad peel and was identified by high performance liquid chromatography. The effect of PTFC on the proliferation and apoptosis of leukemia cells were determined by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide, fluorescent microscopy and flow cytometry, respectively. The effect of PTFC on the expression levels of apoptosis-related regulators was determined by Western blot assay. Results： Treatment with PTFC inhibited leukemia cell proliferation in a dose-and time-dependent manner and triggered Kasumi-1 cell apoptosis. Treatment with PTFC significantly increased the levels of activated poly adenosine diphosphate-ribosepolymerase and caspase-3/-9, but reduced the levels of Mcl-1 expression in Kasumi-1 cells. However, PTFC did not obviously induce HL-60 cell apoptosis. Conclusion： PTFC inhibited leukemia cell proliferation and induced their apoptosis by modulating apoptosisrelated regulator expression in leukemia cells in vitro.

关键词： total flavonoids from Citrus paradisi Macfad human myeloid leukemia cells growth inhibition apoptosis Chinese medicine

Source wavefield reconstruction based on an implicit staggered-grid finite-difference operator for seismic imaging

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第5期19卷 2095-2106页

作者： Zhi-Ming Ren Xue dai qian-Zong Bao Chang'an University College of Geological Engineering and GeomaticsXi'anShaanxi710064China National Engineering Research Center of Offshore Oil and Gas Exploration Beijing100028China

Reverse time migration and full waveform inversion involve the crosscorrelation of two wavefields,propagated in the forward-and reverse-time directions,*** a result,the forward-propagated wavefield needs to be stored,and then accessed to compute the correlation with the backward-propagated ***-value methods reconstruct the source wavefield using saved boundary wavefields and can significantly reduce the storage ***,the existing boundary-value methods are based on the explicit finite-difference(FD)approximations of the spatial *** FD methods exhibit greater accuracy and thus allow for a smaller operator *** develop two(an accuracy-preserving and a memory-efficient)wavefield reconstruction schemes based on an implicit staggered-grid FD(SFD)*** former uses boundary wavefields at M layers of grid points and the spatial derivatives of wavefields at one layer of grid points to reconstruct the source wavefield for a(2M+2)th-order implicit SFD *** latter applies boundary wavefields at N layers of grid points,a linear combination of wavefields at M–N layers of grid points,and the spatial derivatives of wavefields at one layer of grid points to reconstruct the source wavefield(0≤N

关键词： Finite difference Reverse time migration Source wavefield reconstruction Implicit Staggered grid

Assessing the effects of vegetation and precipitation on soil erosion in the Three-River Headwaters Region of the Qinghai-Tibet Plateau,China

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2020年第5期12卷 865-886页

作者： HE qian dai Xiao'ai CHEN Shiqi College of Earth Science Chengdu University of TechnologyChengdu 610059China College of Foreign Languages and Cultures Chengdu University of TechnologyChengdu 610059China

Soil erosion in the Three-River Headwaters Region(TRHR)of the Qinghai-Tibet Plateau in China has a significant impact on local economic development and ecological *** and precipitation are considered to be the main factors for the variation in soil ***,it is a big challenge to analyze the impacts of precipitation and vegetation respectively as well as their combined effects on soil erosion from the pixel *** assess the influences of vegetation and precipitation on the variation of soil erosion from 2005 to 2015,we employed the Revised Universal Soil Loss Equation(RUSLE)model to evaluate soil erosion in the TRHR,and then developed a method using the Logarithmic Mean Divisia Index model(LMDI)which can exponentially decompose the influencing factors,to calculate the contribution values of the vegetation cover factor(C factor)and the rainfall erosivity factor(R factor)to the variation of soil erosion from the pixel *** general,soil erosion in the TRHR was alleviated from 2005 to 2015,of which about 54.95%of the area where soil erosion decreased was caused by the combined effects of the C factor and the R factor,and 41.31%was caused by the change in the R *** were relatively few areas with increased soil erosion modulus,of which 64.10%of the area where soil erosion increased was caused by the change in the C factor,and 23.88%was caused by the combined effects of the C factor and the R ***,the combined effects of the C factor and the R factor were regarded as the main driving force for the decrease of soil erosion,while the C factor was the dominant factor for the increase of soil *** area with decreased soil erosion caused by the C factor(12.10×10^3 km^2)was larger than the area with increased soil erosion caused by the C factor(8.30×10^3 km^2),which indicated that vegetation had a positive effect on soil *** study generally put forward a new method for quantitative assessment of the impacts

关键词： soil erosion vegetation cover rainfall erosivity Logarithmic Mean Divisia Index quantitative assessment Three-River Headwaters Region

Factors contributing to amphibian road mortality in a wetland

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2011年第6期57卷 768-774页

作者： Haijun GU qiang dai qian WANG Yuezhao WANG Chengdu Institute of Biology Chinese Academy of Sciences Chengdu 610041 China Graduate University of Chinese Academy of Sciences Beijing 100043 China

To understand road characteristics and landscape features associated with high road mortality of amphibians in Zoige Wetland National Nature Reserve, we surveyed road mortality along four major roads after rainfall in May and September 2007. Road mortality of three species, Rana kukunoris, Nanorana pleskei and Bufo minshanicus, was surveyed across 225 transects （115 in May and 110 in September）. Transects were 100 m long and repeated every two kilometers along the four major roads. We used model averaging to assess factors that might determine amphibian road mortality. We recorded an average of 24.6 amphibian road mortalities per kilometer in May and 19.2 in September. Among road characteristics, road width was positively associated with road morality for R. kukunori and B. minshanicus. Traffic volume also increased the road mortality of B. minshanicus in September. Of the landscape features measured, area proportions of three types of grassland （wet, mesic and dry） within 1 km of the roads, particularly that of wet grassland, significantly increased road mortality for R. kukunori and total mortality across all three species. To most effectively reduce road mortality of amphibians in the Zoige wetlands, we suggest better road design such as avoiding wet grasslands, minimizing road width, underground passes and traffic control measures. The implementation of pub- lic transit in the area would reduce traffic volume, and hence mortality

关键词： Amphibian Road mortality Zoige Wetland Rana kukunoris Nanorana pleskei Bufo minshanicus