检索结果-南通市图书馆

riparian Vegetation Dynamics Across Two Different Landscapes Along the river cauvery in the Kodagu region of Western Ghats

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2012年第3期9卷 351-361页

作者： c.SUNIL r.K.SOMASHEKAr B.c.NAGArAJA Department of Environmental Science Bangalore UniversityIndia

Decades of commercial planting and other anthropogenic processes are posing a threat to the riparian landscapes of the cauvery river basin, which supports a high floral diversity. Despite this, the habitats in the upstream sections of the river cauvery are still intact, as they are located in sacred groves. To understand the dynamism of riparian forests exposed to anthropogenic pressures, the upstream stretch of cauvery extending from Kushalanagara to Talacauvery （~102 km） was categorized into two landscapes： agro ecosystem and sacred （i.e. preserved）. The tree species were sampled using belt transects at 5 km intervals and the regeneration status of endemic species assessed using quadrats. A total of 128 species belonging to 47 families, and representing 1,590 individuals, was observed. Amongst them, 65% of unique species were exclusive to sacred landscapes. A rarefaction plot confirmed higher species richness for the sacred compared to the agro ecosystem landscapes, and diversity indices with more evenness in distribution were evident in sacred landscapes. A significant loss of endemic tree species in the agro ecosystem landscapes was found. Overall, this study demonstrates that an intense biotic pressure in terms of plantations and other anthropogenic activities have altered the species composition of the riparian zone in non-sacred areas. A permanent policy implication is required for the conservation of riparian buffers to avoid further ecosystem degradation and loss of biodiversity.

关键词： Western Ghats riparian vegetation cauvery river Sacred grove Agro ecosystemlandscape Diversity indices Endemic species.

Processing of rare earth concentrates

在线全文

学校读者我要写书评

暂无评论

rare Metals 2005年第3期24卷 210-215页

作者： Pamela Alex r.c. Hubli A.K. Suri Material Processing Division Bhabha Atomic Research Centre Trombay Mumbai-400085 IndiaMaterial Processing Division Bhabha Atomic Research Centre Trombay Mumbai-400085 IndiaMaterial Processing Division Bhabha Atomic Research Centre Trombay Mumbai-400085 India

The paper describes process details for extraction of rare earths from an intermediate grade concentrate of Madhya Pradesh region in India and a South African slag. The xenodme concentrate obtained from the former place was an intermediate grade （47%） rare earth phosphate containing both monazite and xenotime. The South African slag was a low-grade waste product typically containing only 4% of rare earths. The rare earth resource concentrates have been treated individually by different methods such as alkali fusion and alkali leaching to convert them into their mixed oxides. Both types of materials have been processed and greater than 98% solubilization of metal values has been achieved in the intermediate grade xenotime and 80% from the South African slag. The residue of xenotime hydroxide has been washed thoroughly to collect the sodium phosphate, as by-product and the slurry pH have been adjusted to separate rare earths from thorium effectively. Other impurities such as uranium and iron have been removed by precipitation of rare earths by oxalic acid. It has been possible to recover 〉95% yttrium along with other rare earth oxides.

关键词： xenotime slag fusion leaching calcining solubilization

Legumes from the Paleocene sediments of India and their ecological significance

在线全文

学校读者我要写书评

暂无评论

Plant Diversity 2023年第2期45卷 199-210页

作者： Harshita Bhatia Gaurav Srivastava r.c.Mehrotra Birbal Sahni Institute of Palaeosciences 53 University RoadLucknow 226007India Academy of Scientific and Innovative research(AcSIr) Ghaziabad 201002India

During the early Paleogene,greenhouse gases created warm global *** warm climates redistributed the habitat of marine and terrestrial biota *** the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate *** we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,Srivastava et Mehrotra ***.,and Parvileguminophyllum damalgiriensis Bhatia,Srivastava et Mehrotra ***.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast ***,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-Kohistan Arc during the early ***,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.

关键词： Fabaceae Global warming Fruits Damalgiri Tura rhynchosia

Growth Kinetics of Nanocrystals and Nanorods by Employing Small-angle X-ray Scattering (SAXS) and Other Techniques

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第4期24卷 615-627页

作者： Kanishka BISWAS Neenu VArGHESE c.N.r.rao chemistry and Physics of Materials Unit DST Nanoscience Unit and CSIR Centre of Excellence in ChemistryJawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India Solid State and Structural Chemistry UnitIndian Institute of ScienceBangalore 560012India chemistry and Physics of Materials Unit DST Nanoscience Unit and CSIR Centre of Excellence in ChemistryJawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India

In this article, we report the results of our detailed investigations of the growth kinetics of zero-dimensional nanocrystals as well as one-dimensional nanorods by the combined use of small angel X-ray scattering （SAXS）, transmission electron microscopy （TEM） along with other physical techniques. The study includes growth kinetics of gold nanocrystals formed by the reduction of HAucl4 by tetrakis（hydroxymethyl） phosphonium chloride in aqueous solution, of cdSe nanocrystals formed by the reaction of cadmium stearate and selenium under solvothermal conditions, and of ZnO nanorods formed by the reaction of zinc acetate with sodium hydroxide under solvothermal conditions in the absence and presence of capping agents. The growth of gold nanocrystals does not follow the diffusion-limited Ostwald ripening, and instead follows a Sigmoidal rate curve. The heat change associated with the growth determined by isothermal titration calorimetry is about 10 kcal·mol^-1 per I nm increase in the diameter of the nanocrystals. In the case of cdSe nanocrystals also, the growth mechanism deviates from diffusion-limited growth and follows a combined model containing both diffusion and surface reaction terms. Our study of the growth kinetics of uncapped and poly（vinyl pyrollidone）（PVP）-capped ZnO nanorods has yielded interesting insights. We observe small nanocrystals next to the ZnO nanorods after a lapse of time in addition to periodic focusing and defocusing of the width of the length distribution. These observations lend support to the diffusion-limited growth model for the growth of uncapped ZnO nanorods. a.c.r.ingly, the time dependence on the length of uncapped nanorods follows the L3 law as required for diffusion-limited Ostwald ripening. The PVP-capped nanorods, however, show a time dependence, which is best described by a combination of diffusion （L^3） and surface reaction （L^2） terms.

关键词： Growth kinetics Gold nanocrystals cdSe nanocrystals ZnO nanorods Small angle X-ray scattering Transmission electron microscopy Ostwald ripening and sigmoidal growth

SYNTHESIS,cHArAcTErIZATION AND PrOPErTIES OF OrGANOcLAYMODIFIED POLYSULFONE/EPOXY INTErPENETrATING POLYMEr NETWOrK NANOcOMPOSITES

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2008年第6期26卷 669-678页

作者： r.rajasekaran c.Karikalchozhan M.Alagar Department of chemistry St.Joseph's College of EngineeringChennai-600 119.India Department of chemical Engineering Anna UniversityChennai-600 025India

Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing *** mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM ***...

关键词： Nanocomposites Glass transition temperature Impact strength Interpenetrating networks (IPN) Polysulfone.

Mantle avalanches in a Venus-like stagnant lid planet

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2024年第5期8卷 686-702页

作者： Madeleine c.Kerr Dave r.Stegman Institute of Geophysics and Planetary Physics Scripps Institution of OceanographyUniversity of CaliforniaSan DiegoLa JollaCAUSA

Stagnant lid planets are characterized by a globe-encircling,conducting lid that is thick and strong,which leads to reduced global surface heat ***,the mantles of such planets can have warmer interiors than Earth,and interestingly,a pyrolitic mantle composition under warmer conditions is predicted to have a distinctly different mantle transition zone compared to the present-day Earth(Hirose,2002;Stixrude and Lithgow-Bertelloni,2011;Ichikawa et al.,2014;Dannberg et al,2022).Instead of olivine primarily transforming into its higher-pressure polymorphs such as wadsleyite and then ringwoodite,at pressures corresponding to 410 km and 520 km depth in Earth,respectively,it instead transforms into a mineral assemblage of wadsleyite,majorite,and ferropericlase(WMF),and then to majorite+ferropericlase(MF),before finally transforming into bridgmanite at pressures corresponding to 660 km depth in Earth(Stixrude and Lithgow-Bertelloni,2011;Ichikawa et al.,2014).convective motions in stagnant lid planets are dominated by small-scale instabilities(cold drips)forming within the mobile rheological sublayer under the rigid *** ASPEcT and a thermodynamic model of a pyrolitic mantle composition generated by HeFESTo,we show that under certain conditions,the small drips can pond atop the WMF-MF mineral phase *** barrier to convective flow arises from the WMF mineral phase assemblage having an effective negative thermal expansivity(Stixrude and Lithgow-Bertelloni,2022).Although large-scale downwellings that typically occur within mobile lid planets are able to pass through the WMF zone without difficulty(Dannberg et al.,2022;Li rP et al.,2024),the smaller and less negatively buoyant nature of downwelling drips in stagnant lid planets are more susceptible to these effects,which leads to an ephemeral layering of the *** numerical models show that in stagnant lid planets with mantle potential temperatures that exceed 1900 K,the smaller,cold drips from t

关键词： Venus mantle avalanches numerical modelling phase transitions

crustal reworking and orogenic styles inferred from zircon Hf isotopes:Proterozoic examples from the North Atlantic region

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2019年第2期10卷 417-424页

作者： c.J.Spencer c.L.Kirkland A.r.Prave r.A.Strachan V.Pease Earth Dynamics research Group The Institute of Geoscience Research (TIGeR)Department of Applied GeologyCurtin University centre for Exploration Targeting d curtin Node Department of Applied GeologyCurtin University Department of Earth and Environmental Sciences University of St Andrews School of Earth and Environmental Sciences University of Portsmouth Department of Geological Sciences Stockholm University

Zircon Hf evolutionary patterns are powerful tools to investiage magma petrogenesis and crustal evolution. The ^(176)Hf/^(177)Hf isotopic signature of a rock is particularly informative and can be used to derive an estimation of the time when mantle extraction and diagnose closed system reworking where successive samples through time define an Hf evolution array dependant on the source Lu/Hf ratio. However, many magmatic events require new mantle addition as the thermal impetus for melting pre-existing crust. In this situation, rather than simply reflecting reworking, the isotopic signature indicates mixing with contributions from both reworked crust and new radiogenic input. Different geodynamic settings have different propensities for either reworking or addition of new mantle-derived magma. Hence, Hf-time trends carry within them a record, albeit cryptic, of the evolving geodynamic environment as different tectonic configurations recycle and add new crust at different rates, magnitudes, and from different sources. As an example of the difference in apparent Hf evolution slopes, we present Hf-time compilations from three geographically distinct Meso-to Neoproterozoic orogenic belts in the North Atlantic region whose geodynamic configurations remain a subject of debate. We use the εHf/Ma trajectory to assist in understanding their evolution. The εHf/Ma trajectory of the Sveconorwegian Orogen corresponds to a ^(176)Lu/^(177) Hf ratio of 0.012, which implies a process driven primarily by reworking of preexisting crust that is balanced with input from the depleted mantle resulting in a relatively shallowεHf/Ma slope. The Valhalla Orogen reveals a similar comparatively shallow εHf/Ma path. In stark contrast to these patterns is the steep εHf/Ma trajectory of the Grenville Orogen that requires a mixing process involving a greater contribution of old crust of at least ～ 1.8 Ga age. The degree of reworking required to produce the εHf/Ma trend of the Grenville Orogen is co

关键词： Zircon Hf crustal evolution Grenville Sveconorwegian Valhalla

Strain Limit of Extra Galvannealed Interstitial-Free and Bake Hardened Steel Sheets Under Different Stress conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel research International 2008年第5期15卷 56-60页

作者： r Narayanasamy N L Parthasarathi r ravindran c Sathiya Narayanan Department of Production Engineering National Institute of TechnologyTiruchirappalli 620015TamilnaduIndia

The formability of bake hardened steel （thickness 0.82 mm）, and the extra galvannealed IF steel （thickness 0.82 mm） have been studied. The suitability of the above steels for forming applications has been critically examined. The microstructure, tensile properties, and formability parameters of the above sheet metals were determined. The manufacturing process of the steels and the significance with reference to its formability were studied.

关键词： bake hardened steel extra galvannealed IF steel microstructure forming limit diagram tensile parameter

Significance of Stefan blowing effect on flow and heat transfer of casson nanofluid over a moving thin needle

在线全文

学校读者我要写书评

暂无评论

communications in Theoretical Physics 2021年第9期73卷 51-58页

作者： A M Jyothi r Naveen Kumar r J Punith Gowda B c Prasannakumara Bangalore Institute of Technology BangaloreIndia Department of Studies and research in Mathematics Davangere UniversityDavangere-577002KarnatakaIndia

The current mathematical model explains the influence of non-linear thermal radiation on the casson liquid flow over a moving thin needle by considering Buongiorno’s nanofluid *** influences of Stefan blowing,Dufour and Soret effects are also considered in the *** equations which represent the described flow pattern are reduced to ordinary differential equations(ODEs)by using apt similarity transformations and then they are numerically solved with runge–Kutta-Fehlberg’s fourth fifth-order method(rKF-45)with shooting *** impacts of pertinent parameters on thermal,mass and velocity curves are deliberated *** friction,rate of heat and mass transfer are also discussed *** reveal that,the increase in values of Brownian motion,thermophoresis,Dufour number,heating and radiative parameters improves the heat *** increasing values of the Schmidt number deteriorates the mass transfer but a converse trend is seen for increasing values of the Soret ***,the escalating values of the radiative parameter decays the rate of heat transfer.

关键词： moving thin needle Brownian motion and thermophoretic diffusion non-linear thermal radiation Stefan blowing condition