检索结果-南通市图书馆

Nano-Micro Letters 2010年第3期2卷 204-212页

作者： Thirunavukkarasu Somanathan Arumugam Pandurangan Department of Chemistry Anna University Chennai Department of Chemical Engineering University of Massachusetts

Mesoporous MCM-41 molecular sieves containing f-block transition elements（gadolinium） with various Si/Gd ratios（50,75 and 100） were synthesised by a hydrothermal *** mesoporous structure was confirmed by X-ray diffraction,nitrogen sorption studies,thermogravimetric analysis,scanning and transmission electron *** local environment of Gd in the material was studied by electron paramagnetic *** compatibility of the catalyst for the synthesis of uniform diameter CNTs by varying the temperature from 400 to 650°C with fixed flow rates of N2 and C2H2（140 ml/min and 40 ml/min,respectively）.The product is mostly metal containing thin MWCNTs with diameter of 1020 *** shows that a combination of Gd-MCM-41（100） catalyst gives a high yield of high quality MWCNTs under optimum growth conditions.

关键词： MWCNTs Gd carbon nanotubes Contrasting agents Magnetic resonance imaging

Analysis of isoquinoline alkaloids from Mahonia leschenaultia and Mahonia napaulensis roots using UHPLC-Orbitrap-MSn and UHPLC-QqQ LIT-MS/MS

在线全文

学校读者我要写书评

暂无评论

Journal of Pharmaceutical Analysis 2017年第2期7卷 77-86页

作者： Awantika Singh Vikas Bajpai Sunil Kumar Ajay Kumar Singh Rawat Brijesh Kumar Sophisticated Analytical Instrument Facility Division CSIR-Central Drug Research InstituteLucknow 226031India Academy of Scientific and Innovative Research New Delhi 110001India Pharmacognosy and Ethnopharmacology Division CSIR-National Botanical Research InstituteLucknow 226001India

Mahonia leschenaultia（ML） and Mahonia napaulensis（MN） are less known and unexplored medicinal plants of the family Berberidaceae. They are used by the Todas of Nilgiris in their religious and medical practices but chemically less identified. Hence, we decided to do extensive phytochemical analysis to explore the potential of these plant extracts. An ultrahigh performance electrospray tandem mass spectrometry（UHPLC-ESI-MS/MS）method was successfully developed for qualitative analysis of the bioactive components in Mahonia species using Orbitrap Velos Pro mass spectrometer. Sixteen compounds were identified by comparison of their retention times and mass spectra（MS） with authentic standards and reported literature. Multi-stage mass spectra（MS（2-8）） for the identification of protoberberine and aporphine alkaloids showed the sequential expulsion of all the substituents attached with their basic skeleton followed by CO loss. Eight of the identified compounds（berberine, jatrorrhizine, palmatine, magnoflorine, isocorydine, glaucine, tetrahydropalmatine and tetrahydroberberine） were simultaneously determined by another UHPLC-ESI-MS/MS method under the multiple reactions monitoring（MRM） mode quantitatively using triple quadrupole linear ion trap mass spectrometer. The analytical method was validated for 8 bioactive compounds with overall recovery in the range98.5%-103.6%（RSD≤2.2%）, precise（RSD≤2.07%） and linear（r≥0.9995） over the concentration range of 0.5-1000 ng/mL and successfully applied in ML and MN roots, which suggests the suitability of the proposed approach for the routine analysis of Mahonia species and their quality control.

关键词： Orbitrap-MS QqQLIT-MS Mahonia leschenaultia Mahonia napaulensis Isoquinoline alkaloids

On the reality of broad iron L lines from the narrow line Seyfert 1 galaxies 1H0707–495 and IRAS 13224–3809

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第11期16卷 37-42页

作者： Pramod Karbhari Pawar Gulab Chand Dewangan Madhav Khushalrao Patil Ranjeev Misra Sharada Keshav Jogadand S. R. T. M. University Nanded- 431 606 India Inter-University Center for Astronomy and Astrophysics Pune - 411 007 India

We performed time resolved spectroscopy of 1H0707-495 and IRAS 13224-3809 using long XMM-newton observations. These are strongly variable narrow line Seyfert 1 galaxies and show broad features around 1 keV that have been interpreted as relativistically broad Fe Lc~ lines. Such features are not clearly observed in other active galactic nuclei despite sometimes having high iron abundance required by the best fitted blurred reflection models. Given the importance of these lines, we explore whether the rapid variability of spectral parameters may introduce broad bumps/dips artificially in the time averaged spectrum, which may then be mistaken as broadened lines. We tested this hypothesis by performing time resolved spectroscopy using long （〉 100 ks） XMM-newton observations and by dividing them into segments with typical exposures of a few ks. We extracted spectra from each such segment and modeled them using a two component phenomenological model consisting of a power law to represent the hard component and a black body to represent the soft emission. As expected, both the sources showed variations in the spectral parameters. Using these variation trends, we simulated model spectra for each segment and then co-added to get a combined simulated spectrum. In the simulated spectra, we found no broad features below 1 keV and in particular no deviation near 0.9 keV as seen in the real averaged spectra. This implies that the broad Fe Lα line that is seen in the spectra of these sources is not an artifact of the variation of spectral components and, hence, provides evidence that the line is indeed genuine.

关键词： galaxies: general -- galaxies: active -- galaxies: individual (1H0707-495 IRAS 13224-3809)

Rheological fluid motion in tube by metachronal waves of cilia

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2017年第3期38卷 393-410页

作者： S.MAITI S.K.PANDEY Department of Mathematical Sciences Indian Institute of Technology (BHU) Department of Mathematics The LNM Institute of Information Technology

This paper presents a theoretical study of a non-linear rheological fluid transport in an axisymmetric tube by cilia. An attempt has been made to explain the role of cilia motion in the transport of fluid through the ductus efferent of the male reproductive tract. The Ostwald-de Waele power-law viscous fluid is considered to represent the rheological fluid. We analyze pumping by means of a sequence of cilia beats from rowto-row of cilia in a given row of cells and from one row of cells to the next(metachronal wave movement). For this purpose, we consider the conditions that the corresponding Reynolds number is small enough for inertial effects to be negligible, and the wavelengthto-diameter ratio is large enough so that the pressure can be considered uniform over the cross section. Analyses and computations of the fluid motion reveal that the time-average flow rate depends on ε, a non-dimensional measure involving the mean radius a of the tube and the cilia length. Thus, the flow rate significantly varies with the cilia ***, the flow rate has been reported to be close to the estimated value 6 × 10ml/h for human efferent ducts if ε is near 0.4. The estimated value was suggested by Lardner and Shack(Lardner, T. J. and Shack, W. J. Cilia transport. Bulletin of Mathematical Biology, 34, 325–335(1972)) for human based on the experimental observations of flow rates in efferent ducts of other animals, e.g., rat, ram, and bull. In addition, the nature of the rheological fluid, i.e., the value of the fluid index n strongly influences various flow-governed characteristics. An interesting feature of this paper is that the pumping improves the thickening behavior for small values of ε or in free pumping(?P = 0) and pumping(?P > 0) regions.

关键词： non-newtonian fluid cilia movement metachronal wave volumetric flow flow reversal velocity at wave crest and trough

Bird assemblages in natural and urbanized habitats along elevational gradient in Nainital district （western Himalaya） of Uttarakhand state, India

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2011年第3期57卷 318-329页

作者： Dinesh BHATT Kamal Kant JOSHI Avian Diversity and Bioacoustics Lab Department of Zoology and Environmental Science Gurukula Kangri University Harid- war 249 404 Uttarakhand India

The Indian subcontinent is amongst the biologically better known parts of the tropics and its bird fauna has been well documented. However, avian community composition and diversity along elevational gradients and amongst habitat types remains unclear in India. We attempted to estimate bird assemblages in terms of diversity, species composition, status and abun- dance in urban and forest habitats of Nainital district of Uttarakhand （350-2450 m asl; 29N）, Western Himalayas. We sampled different elevational gradients and to understand the effect of urbanization and season on avian community composition. Field studies were conducted during January 2005 to January 2007. Results indicated that the forest had more complex bird community structure in terms of higher species richness （14.35 vs 8.69）, higher species diversity （Shannon＇s index 4.00 vs 3.54）, higher evenness （0.838 vs 0.811） and more rare species （17 vs 5） as compared to urban habitat. However, the abundance of 11 species was higher in urban habitats. Bird Species Richness （BSR） varied considerably among study areas （91 to 113 species）, was high- est （113 species） at mid elevation （1450-1700 m asl） and decreased （22 species） at high elevation （1900-2450 m asl）. It seems that high BSR at mid altitudes is not caused by the presence of a group of mid altitude specialists but rather that there is an over- lap in the distribution of low land and high elevation specialists at this altitude. BSR and Bird Species Diversity fluctuated across seasons but not habitat type [Current Zoology 57 （3）： 318-329,2011].

关键词： Avian biodiversity Western Himalaya Urbanization

Effect of pouring temperature on cooling slope casting of semi-solid Al-Si-Mg alloy

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

Acta Metallurgica Sinica(English Letters) 2012年第5期25卷 329-339页

作者： Prosenjit Das Sudip K. Samanta Himadri Chattopadhyay Pradip Dutta Foundry Group CSIR-Central Mechanical Engineering Research Institute Durgapur-713209 India Department of Mechanical Engineering Jadavpur University Kolkata-70032 India Department of Mechanical Engineering Indian Institute of Science Bangalore-560012 India

Present trend of semi-solid processing is directed towards rheocasting route which allows manufacturing of near-net-shape cast components directly from the prepared semi-solid slurry. Generation of globular equi-axed grains during solidification of rheocast components, compared to the columnar dendritic structure of conventional casting routes, facilitates the manufacturing of components with improved mechanical properties and structural integrity. In the present investigation, a cooling slope has been designed and indigenously fabricated to produce semi solid slurry of A1-Si-Mg （A356） alloy and successively cast in a metallic mould. The scope of the present work discusses about development of a numerical model to simulate the liquid metal flow through cooling slope using Eulerian two-phase flow approach and to investigate the effect of pouring temperature on cooling slope semi-solid slurry generation process. The two phases considered in the present model are liquid metal and air. Solid fraction evolution of the solidifying melt is tracked at different locations of the cooling slope, following Schiel＇s equation. The continuity equation, momentum equation and energy equation are solved considering thin wall boundary condition approach. During solidification of the liquid metal, a modified temperature recovery scheme has been employed taking care of the latent heat release and change of fraction of liquid. The results obtained from simulations are compared with experimental findings and good agreement has been found.

关键词： Rheocasting Semi-solid slurry Cooling slope A356 alloy Numerical simulation

Controlled drug release of 5-amino salicylic acid by poly（2- hydroxyethylmethacrylate） grafted agar

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2014年第4期8卷 465-470页

作者： G. Usha RANI Kartick Prasad DEY Srijita BHARTI Sumit MISHRA Department of Chemistry Birla Institute of Technology Mesra Ranchi 835215 Jharkhand India

The utilization of poly （2-hydroxyethylmetha- crylate） grafted agar （Ag-g-P（HEMA）） as a matrix for the controlled release of 5-aminosalicylic acid was investi- gated. Grafted copolymers of 2-hydroxyethylmethacrylate （HEMA） monomers on agar were synthesized by micro- wave assisted method. In vitro drug release studies were performed at pH values of 2 and 7 in order to investigate the possibility of pH triggered release for colon targeted drug delivery. Further, the percent grafting vs. tso （the time taken for release of 50% of the enclosed drug） value was studied and the results indicate that it may be possible to develop a programmable drug release matrix based on grafted polysaccharide. Ag-g-P（HEMA） appears to be a useful matrix for controlled release.

关键词： agar controlled drug release 5-Amino sal-icylic acid poly(2-hydroxyethylmethacrylate) grafted agar

SPICE compatible analytical electron mobility model for biaxial strained-Si-MOSFETs

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2011年第5期32卷 36-41页

作者： Amit Chaudhry J.N.Roy S.Sangwan UIET Panjab UniversityChandigarhIndia Solar Semiconductro Pvt.Ltd HyderabadIndia

This paper describes an analytical model for bulk electron mobility in strained-Si layers as a function of strain. Phonon scattering, columbic scattering and surface roughness scattering are included to analyze the full mobility model. Analytical explicit calculations of all of the parameters to accurately estimate the electron mobility have been made. The results predict an increase in the electron mobility with the application of biaxial strain as also predicted from the basic theory of strain physics of metal oxide semiconductor （MOS） devices. The results have also been compared with numerically reported results and show good agreement.

关键词： mobility SiGe strained-Si phonon surface roughness columbic

Surfactant assisted solvothermal synthesis of ZnO nanoparticles and study of their antimicrobial and antioxidant properties

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第6期34卷 1035-1043页

作者： Mina Zare K. Namratha K. Byrappa D.M. Surendra S. Yallappa Basavaraj Hungun Centre for Materials Science and Technology Vijnana Bhavan University of Mysore 570006 India DOS in Earth Science University of Mysore Vijnana Bhavan Manasagangotri Mysore 570 006 India Dept. of Chemistry Gokhale Centenary College Ankola 581314 Uttara Kannada India Department ofBiotechnology KLE Technological University Hubballi 580031 India

This study demonstrated a solvothermal method of growth of three different morphologies of zinc oxide nanoparticles （ZnO NPs）： i） flower-like nanorod and nanoflakes, ii） assembled hierarchical structure, and iii） nano granule. Oleic acid （C18H3402）, gluconic acid （C6H1207） and tween 80 （C64H124026） were used as surfactant/capping/reducing agent for the formation of different morphologies of nanoparticles. The as-synthesized ZnO NPs were characterized by different physicochemical techniques such as UV-vis （UV-vis） spectroscopy, X-ray diffraction （XRD）, fourier transform infrared spectroscopy （FFIR）, field emission scanning electron microscopy （FE-SEM）, energy dispersive X-ray （EDX） analysis and dynamic light scattering （DLS） studies. Further, the antioxidant and antimicrobial activity of these nanostructures was evaluated. The antioxidant activity of these nanostructures was assessed via 2,2-diphenyl,1-1 picrylhydrazyl （DPPH）, 2,2＇-azino-bis （3-ethylbenzothiazoline-6-sulphonic acid）（ABTS） and H202 free radical scavenging activity. The in vitro antimicrobial activity of the obtained nanostructures was demonstrated against both gram negative （Escherichia coil） and gram positive （Staphylococcus aureus） bacterial genera. This study revealed antioxidant and antimicrobial properties of different structures ofZnO NPs suggesting their biomedical and industrial applications.

关键词： ZnO nanoparticles Solvothermal method Nanorods Nanoflakes[k]Nano granule Antioxidant & antimicrobial studies

Effect of Ni^(7+) Ion Irradiation on Structure and Ammonia Sensing Properties of Thermally Oxidized Zinc and Indium Films

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第8期28卷 700-706页

作者： Amandeep Kaur Bal Rajinder Singh R.K.Bedi Material Science Laboratory Department of PhysicsGuru Nanak Dev University

ZnO and In203 films were prepared by thermal oxidation of vacuum deposited zinc and indium films, respec- tively onto the glass substrate at 30 ℃. The fabricated films have been irradiated with 100-MeV Ni7＋ ions at different fluences ranging from 5×1011 to 5×1013 ions/cm2. The structural and gas sensing properties of pristine and irradiated films have been discussed. X-ray diffraction （XRD） pattern of pristine and irradiated films reveal that the films are polycrystalline in nature and crystallinity increases after irradiation. In this study, highly porous In203 nanorods evolved when being irradiated at a fluence of 5×1013 ions/cm2 while ZnO film shows decrease in number of nanowires. The ammonia sensing performance of the Ni^7＋ irradiated In203 films shows an improvement as compared to its pristine counterpart.

关键词： Thermal oxidation ZnO film In203 film Ion irradiation Gas sensing