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Structural and luminescence enhancement properties of Eu^(3+)/Ag nanocrystallites doped SiO_2-TiO_2 matrices

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Journal of Rare Earths 2013年第5期31卷 441-448页

作者： Arun Kumar K V Revathy K P Prathibha vasudevan Sunil Thomas Biju P R Unnikrishnan n V School of Pure & Applied Physics Mahatma Gandhi University

We reported here the structural and optical characterisation of silver nanocrystallites/Eu3＋：SiO2-TiO2 matrices synthesised through sol-gel route. Structural characterisations were done by using energy dispersive spectroscopy （EDX）, X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, atomic force microscope （AFM） and transmission electron microscopy （TEM） measurements and optical characterisations were performed by absorption and emission spectroscopy. The TEM and XRD measurements confirmed the presence of nanocrystals. A broad absorption band was observed due to surface plasmon resonance of silver nanocrystals. The effect of silver nanocrystals on the emission spectrum of Eu3＋ doped SiO2-TiO2 matrices was discussed. An attempt was made to explain this fluorescence enhancement by invoking phenomena such as energy transfer, asymmetry ratio, surface plasmon, surface roughness, crystallinity and grain boundary. Our analysis, based on the experimental results, suggested that all the phenomena except crystallinity and grain boundary had favourable effects on fluorescence enhancement. We also estimated the relevant parameters associated with the phenomena that affected the fluorescence emission from the Eu3＋ ions in the matrix. It was seen that the theoretical estimate of fluorescence enhancement agreed well with the experimental estimate.

关键词： sol-gel luminescence SiO2-TiO2 silver nanoparticles rare earths

Screening of phytocompounds, molecular docking studies, and in vivo anti-inflammatory activity of heartwood aqueous extract of Pterocarpus santalinus L.f.

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Asian Pacific Journal of Tropical Biomedicine 2021年第2期11卷 59-65页

作者： Shanti vasudevan C.n. Bibu John Kariyil Athira nair D. I’ma neerakkal Department of Botany Sacred Heart CollegeThevaraKochi 682013KeralaIndia Department of Veterinary Pharmacology&Toxicology College of Veterinary and Animal SciencesPookode 673576WayanadKeralaIndia

Objective:To evaluate the anti-inflammatory potential of aqueous extract of Pterocarpus santalinus *** using molecular docking and in vivo ***:An aqueous extract of Pterocarpus santalinus heartwood was prepared using a Soxhlet *** in the extract were tentatively identified using high-resolution mass *** docking experiments were carried out to evaluate the binding affinity of selected compounds,phloridzin to cyclooxygenase-1(COX-1),cyclooxygenase-2(COX-2),prostaglandin E synthase-1(PGES-1)and 5-lipoxygenase(5-LOX).Anti-inflammatory potential was evaluated by carageenan induced paw edema model in ***:The presence of major component phloridzin along with quercetin,parthenin,ginkgolide B,picrotoxinin,usnic acid,octopine,and epigallocatechin was detected in the *** docking study showed that phloridzin inhibited COX-1,COX-2,PGES-1 and 5-LOX with more affinity than ibuprofen and *** santalinus heartwood extract at 200 and 400 mg/kg BW showed significant reduction in carageenan-induced hind paw edema in a dose-dependent manner,but the effect was slow when compared with the standard ibuprofen(30 mg/kg p.o.).Conclusions:The study indicated that after clinical trials,the aqueous extract of Pterocarpus santalinus heartwood can be effectively used in phytotherapy to treat inflammation.

关键词： Phloridzin COX-1 COX-2 PGES-1 5-LOX

A hydrochemical approach to estimate mountain front recharge in an aquifer system in Tamilnadu, India

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Acta Geochimica 2018年第3期37卷 465-488页

作者： Banaja Rani Panda S.Chidambaram n.Ganesh V.S.Adithya M.V.Prasanna K.Pradeep U.vasudevan Department of Earth Sciences Annamalai University Department of Applied Geology Faculty of Engineering and Science Curtin University Malaysia

Mountain-front recharge(MFR) is a process of recharging an aquifer by infiltration of surface flow from streams and adjacent basins in a mountain block and along a mountain front(MF). This is the first attempt in India to estimate MFR along the foothills of Courtallam using hydrogeochemistry and geostatistical tools. The estimation of MFR has been carried out by collecting groundwater samples along the foothills of Courtallam. Collected water samples were analyzed for major cations and anions using standard procedures. Hydrogeochemical facies show the existence of four water types in this region. Calcium-rich water derived from gneissic rock terrain indicates significant recharge from higher elevation. Log p CO_2 and ionic strength of the samples were also calculated to identify the geochemical process. Majority of the collected samples have sodium-rich water and weak ionic strength, which indicate foothill recharge and low residence time. Silicate and carbonate weathering have an equal interplay along the foothills with a relatively large fraction of Mg from the MF. The spatial diagrams of three factors show that the southern part of the study area is dominated by both weathering and anthropogenic processes, whereas the northern part is dominated by both leaching and weathering processes. Thus, the dominant weathering process represented by the second factor indicates the large recharge process along the foothills.

关键词： Mountain-front recharge Geostatistical toolsHydrogeochemical facies Ionic ratio Anthropogenicprocesses

Causal analysis of competing atomistic mechanisms in ferroelectric materials from high-resolution scanning transmission electron microscopy data

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npj Computational Materials 2020年第1期6卷 570-578页

作者： Maxim Ziatdinov Christopher T.nelson Xiaohang Zhang Rama K.vasudevan Eugene Eliseev Anna n.Morozovska Ichiro Takeuchi Sergei V.Kalinin The Center for nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTN 37831USA Computational Sciences and Engineering Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Department of Materials Science and Engineering University of MarylandCollege ParkMD 20742USA Institute for Problems of Materials Science National Academy of Sciences of UkraineKrjijanovskogo 3Kyiv 03142Ukraine Institute of Physics National Academy of Sciences of Ukraine46pr.NaukyKyiv 03028Ukraine

Machine learning has emerged as a powerful tool for the analysis of mesoscopic and atomically resolved images and spectroscopy in electron and scanning probe microscopy,with the applications ranging from feature extraction to information compression and elucidation of relevant order parameters to inversion of imaging data to reconstruct structural ***,the fundamental limitation of machine learning methods is their correlative nature,leading to extreme susceptibility to confounding ***,we implement the workflow for causal analysis of structural scanning transmission electron microscopy(STEM)data and explore the interplay between physical and chemical effects in a ferroelectric perovskite across the ferroelectric–antiferroelectric phase transitions.

关键词： ferroelectric analysis founding

Improved speciation of dissolved organic nitrogen in natural waters: amide hydrolysis with fluorescence derivatization

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Journal of Environmental Sciences 2008年第10期20卷 1273-1280页

作者： Ryan L.Fimmen Tamara D.Trouts Daniel D.Richter Jr. Dharni vasudevan School of Earth Sciences The Ohio State University 125 S.Oval MallColumbus OH 43210 USA.Nicholas School of the Environment and Earth Sciences Duke University Durham NC 27708 USA School of Earth Sciences The Ohio State University 125 S.Oval MallColumbus OH 43210 USA nicholas School of the Environment and Earth Sciences Duke UniversityDurham NC 27708 USA. nicholas School of the Environment and Earth Sciences Duke UniversityDurham NC 27708 USA.Department of Chemistry Bowdoin CollegeBrunswick ME 04011 USA

The objective of this study was to improve primary-amine nitrogen (1°-n) quantification in dissolved organic matter (DOM) originating from natural waters where inorganic forms of n, which may cause analytical interference, are commonly encountered. Efforts were targeted at elucidating organic-n structural criteria influencing the response of organic amines to known colorimetric and fluorescent reagents and exploring the use of divalent metal-assisted amide hydrolysis in combination with fluorescence analyse...

关键词： dissolved organic matter/nitrogen (DOM/DOn) o-phthaldialdehyde fluorescamine ninhydrin amino acids amide hydrolysis peptides

Determination of the major geochemical processes of groundwater along the Cretaceous-Tertiary boundary of Trichinopoly,Tamilnadu,India

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Acta Geochimica 2020年第5期39卷 760-781页

作者： n.Devaraj S.Chidambaram U.vasudevan K.Pradeep M.nepolian M.V.Prasanna V.S.Adithya R.Thilagavathi C.Thivya Banajarani Panda Department of Earth Sciences Annamalai UniversityChidambaramTamilnadu 608002India Water Research Centre Kuwait Institute for Scientific ResearchKuwait CityKuwait Department of Applied Geology Faculty of Engineering and ScienceCurtin University Malaysia.CDT 25098009 MiriSarawakMalaysia

The hydrogeochemical variations in groundwater are mainly influenced by lithology,residence time of water in the aquifer matrix,and anthropogenic *** study was focused on the geochemical variations of groundwater in different lithological units(Archaean,Cretaceous,Tertiary,and Quaternary)by understanding the major factors governing the geochemical variations in each *** 71 groundwater samples were collected from these rock types,namely,Archaean(14),Cretaceous(37),Tertiary(11),Quaternary(9).The collected samples were measured for major ions and they were used for preparation of standard geochemical plots and ionic *** analysis and factor score were used to identify the major factors controlling the hydrochemistry and their spatial distribution in the study *** addition,geochemical model,WATEQ 4 F was used to determine the saturation condition of carbonate and sulphate minerals in the ***–Cl and mixed Ca–na–HCO3 were the dominant hydrochemical facies irrespective of lithological *** overall interpretation of geochemical data revealed that leaching of secondary salts,weathering and ion exchange reaction along the groundwater flow path through various lithological units,and anthropogenic influence from domestic sewages and agricultural activities constitute the major geochemical processes in the study ***,this study brings out the multiple hydrogeochemical process in the complex geological terrain along the Cretaceous-Tertiary boundary.

关键词： Groundwater Geochemical process Major ions Correlation Factor analysis

Study on Quality Assessment of Insulators Subjected to DC Voltages

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高电压技术 2008年第12期34卷 2602-2608页

作者： V. Muralidhara B. Ramachandra n. Vasudev P.V. vasudevan nambudiri Sriramulu K.n. Ravi High Voltage Dvivsion Central Power Research Institute PB no8066 New Bel Road Bangalore 560080 India

The failure of insulators under DC voltages is due to various factors like thermal runaway,ion migration,anode growth,surface erosion,cement growth etc..However,the rate of failure is higher in polluted zones where surface erosion and puncturing of insulators due to ion migration can ***,insulators have to be subjected to accelerated aging tests to simulate ion migration and to check their capability to withstand the *** runaway is also an important *** carrying out Thermal runaway test at higher temperature,it may be possible to identify the good *** paper presents the work carried out in order to asses the quality of DC insulators by Thermal runaway tests,Ion-migration tests and the measurement of the body resistance of the *** voltage and temperature were varied during these tests in order to clearly identify the good *** result will be useful for the design of insulators for the HVDC transmission system.

关键词：直流电压绝缘子质量评估温度

Stability-indicating assay method for determination of actarit,its process related impurities and degradation products:Insight into stability profile and degradation pathways

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Journal of Pharmaceutical Analysis 2014年第6期4卷 374-383页

作者： A.Abiramasundari Rahul P.Joshi Hitesh B.Jalani Jayesh A.Sharma Dhaivat H.Pandya Amit n.Pandya vasudevan Sudarsanam Kamala K.Vasu Department of Medicinal Chemistry B.V. Pat el PERD Centre Ahmedcibad Gujarat 380054 India

The stability of the drug actarit was studied under different stress conditions like hydrolysis（acid,alkaline and neutral）,oxidation,photolysis and thermal degradation as recommended hy International Conference on Harmonization（ICH） *** was found to be unstable in acidic,basic and photolytic conditions and produced a common degradation product while oxidative stress condition produced three additional degradation *** was impassive to neutral hydrolysis,dry thermal and accelerated stability *** products were identified,isolated and characterized by different spectroscopic *** and the degradation products were synthesized by a new route using green *** chromatographic separation of the drug and its impurities was achieved in a phenomenex luna C18 column employing a step gradient elution by high performance liquid chromatography coupled to photodiode array and mass spectrometry detectors（HPLC-PDAMS）.A specilic and sensitive stability-indicating assay method for the simultaneous determination of the drug *** process related impurities and degradation products was developed and validated.

关键词： Actarit Forced degradation Stability-indicating assay method

Copy number variations are progressively associated with the pathogenesis of colorectal cancer in ulcerative colitis

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World Journal of Gastroenterology 2015年第2期21卷 616-622页

作者： Bhadravathi Marigowda Shivakumar Harish Rotti Thanvanthri Gururajan.vasudevan Aswath Balakrishnan Sanjiban Chakrabarty Ganesh Bhat Lakshmi Rao Cannanore Ganesh Pai Kapaettu Satyamoorthy Department of Gastroenterology and Hepatology Kasturba Medical CollegeManipal UniversityManipal 576104India School of Life Sciences Manipal UniversityManipal 576104India Department of Pathology Kasturba Medical CollegeManipal UniversityManipal 576104India

AIM: To evaluate the association of known copy number variations(CnVs) in ulcerative colitis(UC) progressing to colorectal ***: Microsatellite instability analysis using the national Cancer Institute's panel of markers, and CnV association studies using Agilent 2 × 105 k arrays were done in tissue samples from four patient groups with UC: those at low risk(LR) or high risk of developing colorectal cancer, those with premalignant dysplastic lesions, and those with colitis-associated colorectal cancer(CAC). DnA from tissue samples of these groups were independently hybridized on arrays and analyzed. The data obtained were further subjected to downstream bioinformatics enrichment analysis to examine the correlation with CAC ***: Microarray analysis highlighted a progressive increase in the total number of CnVs [LR(n = 178) vs CAC(n = 958), 5.3-fold], gains and losses [LR(n = 37 and 141) vs CAC(n = 495 and 463), 13.4- and 3.3-fold, respectively], size [LR(964.2 kb) vs CAC(10540 kb), 10.9-fold] and the number of genes in such regions [LR(n = 119) vs CAC(n = 455), 3.8-fold]. Chromosomewise analysis of CnVs also showed an increase in the number of CnVs across each chromosome. There were 38 genes common to all four groups in the study; 13 of these were common to cancer genes from the Genetic Disease Association dataset. The gene set enrichment analysis and ontology analysis highlighted many cancerassociated genes. All the samples in the different groupswere microsatellite ***: Increasing numbers of CnVs are associated with the progression of UC to CAC, and warrant further detailed exploration.

关键词： Ulcerative colitis Colorectal cancer Molecularanal