检索结果-南通市图书馆

Aggregate dust model to study the polarization properties of comet C/1996 B2 Hyakutake

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2010年第4期10卷 355-362页

作者： Himadri Sekhar Das Abinash Suklabaidya Saonli datta Majumder Asoke Kumar Sen Department of Physics Assam University

The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster Aggregate aggregates of 128 spherical *** first found that the size parameter of the monomer,x ～ 1.56-1.70,turned out to be the most suitable which provides the best fits to the observed dust scattering properties at three wavelengths：λ=0.365 μm,0.485μm and 0.684μ***,the effective radius of the aggregate （r） lies in the range 0.45 μm ≤ r ≤ 0.49 μm at λ=0.365 μm;0.60 μm ≤ r ≤ 0.66 μm at λ=0.485 μm and 0.88 μm ≤ r ≤ 0.94 μm at λ=0.684 μ*** using superposition T-MATRIX code and the power-law size distribution,n（r）～ r-3,the best-fitting values of complex refractive indices are calculated for the observed polarization data at the above three *** best-fitting complex refractive indices （n,k） are found to be （1.745,0.095） at λ=0.365 μm,（1.743,0.100） at λ=0.485 μm and （1.695,0.100） at λ=0.684 μ*** refractive indices derived from the present analysis correspond to a mixture of both silicates and organics,which are in good agreement with the in situ measurement of comets by different spacecraft.

关键词： comets:general - dust extinction - scattering - polarization

Novel Approaches of Using of Spirulina Platensis in Natural Rubber Based Composites

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2018年第7期6卷 680-687页

作者： Ewa Głowińska Janusz datta Paulina Parcheta and Natalia Kaźmierczak Department of Polymers Technology Gdańsk University of TechnologyNarutowicza Street 11/1280-233 GdańskPoland

The aim of this work was to investigate the influence of Spirulina (Spirulina platensis) as a natural filler on thecuring characterization, morphology and mechanical, thermomechanical and thermal properties of naturalrubber (NR) based composites. Spirulina was introduced into NR mixture in amount of 0 phr, 10 phr and 30 *** vulcanization process was carried out at the determined process condition by using hydraulic press atoptimum vulcanization time (t90). It was noticed that Spirulina affected on the reduction of t90, and scorch time(t2) of the NR mixtures. Obtained vulcanizates were subjected to the number of tests e.g. scanning electronmicroscopy analysis, mechanical dynamical analysis, tensile test, hardness, and thermogravimetry. Generally, itwas found that Spirulina added in amount of 10 phr NR positively influenced on tensile strength (TSb), storagemodulus and hardness of obtained composites.

关键词： Spirulina algae natural rubber composites DMA

Groundwater arsenic biogeochemistry-Key questions and use of tracers to understand arsenic-prone groundwater systems

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

Geoscience Frontiers 2019年第5期10卷 1635-1641页

作者： David A. Polya Charlotte Sparrenbom Saugata datta Huaming Guo School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science The University of ManchesterWilliamson BuildingOxford RoadManchesterM13 9PLUK Department of Geology Lund UniversityLundSweden Department of Geology Kansas State University108 Thompson HallManhattanKS66506-3201USA State Key Laboratory of Biogeology and Environmental Geology and School of Water Resources China University of GeosciencesBeijing 100083China

Over 100,000,000 people worldwide are exposed to high arsenic groundwater utilised for drinking or *** consequent global avoidable disease burden is estimated to be of the order of 100,000 avoidable deaths or more per annum from just direct exposures - *** indirect exposure (from rice and other foods) and excluding *** 1000s of papers published on arsenic (hydro)(bio)geochemistry,there remain a number of key outstanding questions to be addressed in relation to arsenic geoscience - these include questions related to:(i) the role of human activities - irrigation,agriculture and other land uses - on arsenic mobilisation in groundwaters;(ii) the specific sources,nature and role of organics,minerals and microbial communities involved in arsenic mobilisation;(iii) the relationship to microscopic to macroscopic scale geological (including tectonic) and evolution processes;(iv) unravelling the over-printing of multiple processes in complex highly heterogeneous aquifer systems and (v) using increasing understanding of the controls of arsenic mobility in groundwaters systems to informing improved locally-relevant remediation and mitigation *** article further summarises how the 9 further papers in this Special Issue address some of these questions through the use of chemical and/or isotopic tracers.

关键词： Arsenic Groundwater Biogeochemical cycles Tracers

Water-soluble-template-derived nanoscale silicon nano- flake and nano-rod morphologies： Stable architectures for lithium-ion battery anodes

在线全文

学校读者我要写书评

暂无评论

Nano Research 2017年第12期10卷 4284-4297页

作者： Bharat Gattu Prashanth Hanumantha Jampani Moni Kanchan datta Ramalinga Kuruba Prashant N. Kumta Department of Chemical and Petroleum Engineering University of Pittsburgh Pittsburgh PA 1526 I USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh PA 15261 USA Department of Bioengineering University of Pittsburgh Pittsburgh PA 1526 I USA Center for Complex Engineered Multifunctional Materials (CCEMM) University of Pittsburgh PA 15261 USA

Earth abundant and economical rock salt （NaC1） particles of different sizes （〈3 μm and 5-20 μm） prepared by high energy mechanical milling were used as water-soluble templates for generation of Si with novel nanoscale architectures via low pressure chemical vapor deposition （LPCVD）. Si nanoflakes （SiNF） comprising largely amorphous Si （a-Si） with a small volume fraction of nanocrystalline Si （nc-Si）, and Si nanorods （SiNR） composed of a larger volume fraction of crystalline Si （c-Si） and a small volume fraction of a-Si resulted from modification of the NaCI crystals. SiNF yielded first-cycle discharge and charge capacities of -2,830 and 2,175 mAh.g-1, respective134 at a current rate of 50 mA.g-1 with a first-cycle irreversible loss （FIR loss） of -15%-20%. SiNR displayed first-cycle discharge and charge capacities of -2,980 and -2,500 mAh-g-1, respectively, at a current rate of 50 mA-g-1 with an FIR loss of -12%-15%. However, at a current rate of 1 A.g-1, SiNF exhibited a stable discharge capacity of -810 mAh-g-1 at the end of 250 cycles with a fade rate of -0.11% loss per cycle, while SiNR showed a stable specific discharge capacity of -740 mAh.g-1 with a fade rate of -0.23% loss per cycle. The morphology of the nanostructures and compositions of the different phases/phase of Si influence the performance of SiNF and SINK, making them attractive anodes for lithium-ion batteries.

关键词： silicon nanoflakes nanorods water-soluble template NaC1

A simplified fragility analysis of fan type cable stayed bridges

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

Earthquake Engineering and Engineering Vibration 2005年第1期4卷 83-94页

作者： R. A. Khan T. K. datta S. Ahmad Civil Engineering Department Jamia Millia Islamia New Delhi-25 IndiaLecturerCivil Engineering Department Indian Institute of Technology New Delhi-16 IndiaProfessorDepartment of Applied Mechanics Indian Institute of Technology New Delhi-16 India Professor

A simplified fragility analysis of fan type cable stayed bridges usingProbabilistic Risk Analysis (PRA) procedure is presented for determining their failure probabilityunder random ground motion. Seismic input to the bridge support is considered to be a riskconsistent response spectrum which is obtained from a separate analysis. For the response analysis,the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses ofthe springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysisprovides a coupled stiffness matrix for the spring system. A continuum method of analysis usingdynamic stiffness is Used to determine the dynamic properties of the bridges .The response of thebridge deck is obtained by the response spectrum method of analysis as applied to multi-degree offreedom system which duly takes into account the quasi - static component of bridge deck *** fragility analysis includes uncertainties arising due to the variation in ground motion,material property, modeling, method of analysis, ductility factor and damage concentration *** of failure of the bridge deck is determined by the First Order Second Moment (FOSM)method of reliability. A three span double plane symmetrical fan type cable stayed bridge of totalspan 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure areobtained under a number of parametric variations. Some of the important conclusions of the studyindicate that (ⅰ) not only vertical component but also the horizontal component of ground motionhas considerable effect on the probability of failure; (ⅱ) ground motion with no time lag betweensupport excitations provides a smaller probability of failure as compared to ground motion with verylarge time lag between support excitation; and (ⅲ) probability of failure may considerablyincrease for soft soil condition.

关键词： probabilistic risk analysis fan type cable stayed bridge fragilityanalysis first order second moment

Effects of anthropogenic disturbances on vegetation diversity and structure:a case study in the remnant forests surrounding the village ecosystems of Tripura,Northeast India

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Population,Resources and Environment 2015年第4期13卷 332-340页

作者： Koushik Majumdar B.K.datta Plant Taxonomy and Biodiversity Laboratory Department of BotanyTripura University

The types,frequency,and intensity of human interference with forests markedly affect the vegetation *** of the impact of anthropogenic disturbances on forest diversity and structure is one of the central issues related to human behaviour and forest ecosystems and *** species diversity and density are very sensitive to local anthropogenic disturbance,which can be reduced depending on land-use *** used 10 line transects of 500 x 10 m to record and measure all plants >10 cm girth in some of the remaining forests surrounding villages in Tripura,Northeast *** predict the effects of anthropogenic pressure on species richness and forest structure,we recorded and scored all ongoing disturbances in all transects of the *** our study did not show any significant effects on the mean number of species,all diversity indices were significantly affected by *** stem density(F = 128.60,p < 0.0001) and basal area(F = 65.30,p < 0.0001) of the forest stands were significantly affected by *** significantly(F= 84.81,p < 0.0001) impacts the abundance of mature voluminous trees removed by extensive illegal ***,stem density at the middle(F= 10.01,p < 0.05) and upper(F= 131.70,p < 0.0001) canopy stories was also reduced by high disturbance *** present analysis will be useful to policy-makers and planners for implementation of sustainable forest management at both the local and regional scale.

关键词： impact of human influence remnant village forests vegetation diversity and density

Responsive envelope tessellation and stochastic rotation of 4-fold penttiles

在线全文

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2014年第2期3卷 192-198页

作者： Sambit datta Stuart Hanafin Robert F. Woodbury School of Built Environment Curtin University Perth Australia School of Architecture and Building Deakin University Geelong Australia School of Interactive Arts and Technology Simon Fraser University Vancouver Canada

This paper reports on the design and control of tessellated components. The study investigates a responsive envelope based on the rotation of responsive and dynamic approaches for building facades and envelopes to regulate solar shading, light control, views and thermal gain within the building. It is well known that near real-time visual output from computational simulation can significantly impact the prediction of dynamic building-environment interactions and lead to the development of smart, adaptable, net zero energy buildings. To address these motivations, this paper reports the development of an experimental simulation of a responsive envelope based on using a 4-fold penttile scheme. The simulation is developed using a novel pentagonal approach involving component （tile） design, tessellation and control methods. The paper further elaborates on the geometry and control aspects of the facade subdivision and presents the results of applying this tessellation geometry to a building envelope shading study based on facade components with rotation. Finally, it tests the ＂responsiveness＂ to multiple performance metrics by applying a non-deterministic exploration method for the stochastic rotation of individual panels. The sophisticated evaluation of alternative envelope configurations for a set of performance criteria require a tighter computational coupling between modelling and control of dynamic geometry.

关键词： Facade tessellation Stochastic rotation Responsive envelopesMoveable facadecomponents Parametric modelling

Nanoengineering of Curved Supramolecular Polymers:Toward Single-Chain Mesoscale Materials

在线全文

学校读者我要写书评

暂无评论

Accounts of Materials Research 2022年第2期3卷 259-271页

作者： Sougata datta Sho Takahashi Shiki Yagai Department of Applied Chemistry and Biotechnology Graduate School of EngineeringChiba UniversityChiba 263-8522Japan Division of Advanced Science and Engineering Graduate School of Engineering and Institute for Global Prominent Research(IGPR)Chiba UniversityChiba 263-8522Japan

CONSPECTUS:Recently,supramolecular polymers(SPs),which depend on the formation of reversible bonds between monomers,have attracted attention as a class of materials that can overcome the potential environmental problems of conventional polymeric *** development of various supramolecular polymers is important not only for their direct application as materials but also because their unique polymerization processes and dynamic properties have a profound influence on the development of polymeric and small-molecule-based functional *** other words,by limiting the dimensionality of molecular assemblies to one dimension,we can discover the essential aspects of selfassembly and *** particular,supramolecular polymerization,in whichπ-electron-rich planar molecules are stacked one-dimensionally via multiple interactions,is interesting because it gives“π-stacked SPs”with one-dimensional crystal-like *** excellent intrinsic(internal)structural order ofπ-stacked SPs is difficult to observe in higher-order structures that exhibit only a monotonous linear ***,our research has shown that when internal structural order intrinsically generates curvature,the curvature appears as a major feature of the entire polymer *** intrinsic curvature allows the formation of diverse topologies such as toroids,random coils,waves,spirals,and helicoids usingπ-stacked SPs and also allows structural changes at the single-polymer-chain level along a topology-dependent energy *** other words,π-stacked SP-based nanomaterials could enable free control of the structure at the single-polymer-chain *** Account will focus on our research into curved supramolecular polymers(CSPs)during the last five *** are formed by the hydrogen bonding between barbituratecontainingπ-conjugated molecules to produce giant supramolecular *** first give an overview of the molecular design of the monomers required for the formation of CSP

关键词： materials curvature bonds

Light signaling and UV-B-mediated plant growth regulation^FA

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 Integrative Plant Biology 2020年第9期62卷 1270-1292页

作者： Arpita Yadav Deeksha Singh Maneesh Lingwan Premachandran Yadukrishnan Shyam Kumar Masakapalli Sourav datta Department of Biological Sciences Indian Institute of Science Education and Research(IISER)BhopalBhopalMadhya Pradesh462066India School of Basic Sciences Indian Institute of Technology(IIT)MandiKamandHimachal Pradesh175005India

Light plays an important role in plants' growth and development throughout their life cycle. Plants alter their morphological features in response to light cues of varying intensity and quality. Dedicated photoreceptors help plants to perceive light signals of different wave-lengths. Activated photoreceptors stimulate the down-stream signaling cascades that lead to extensive gene expression changes responsible for physiological and developmental responses. Proteins such as ELONGATED HYPOCOTYL5 (HY5) and CONSTITUTIVELY PHOTO-MORPHOGENIC 1 (COP1) act as important factors which modulate light-regulated gene expression, especially during seedling development. These factors function as central regulatory intermediates not only in red, far-red, and blue light pathways but also in the UV-B signaling pathway. UV-B radiation makes up only a minor fraction of sunlight, yet it imparts many positive and negative effects on plant growth. Studies on UV-B perception, signaling, and response in plants has considerably surged in recent times. Plants have developed different strat-egies to use UV-B as a developmental cue as well as to withstand high doses of UV-B radiation. Plants' re-sponses to UV-B are an integration of its cross-talks with both environmental factors and phytohormones. This review outlines the current developments in light sig-naling with a major focus on UV-B-mediated plant growth regulation.

关键词： plant Plants seedling