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Investigation of Silver Nanostructures and Their Influence on the Fluorescence Spectrum of Erbium-Doped Glasses

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Optics and Photonics Journal 2013年第1期3卷 45-50页

作者： Victor O. Obadina b. Rami reddy Department of Physics Alabama A&M University Normal USA

Sodium borate glasses embedded with silver were made by the melt quenching technique. Glass transition temperature was recorded by thermal analysis of the sample. As made glasses revealed emission in the visible region under nitrogen laser and excimer laser excitations. Heat treatment was used to induce silver metallic particles. Absorption spectra revealed a peak at 417 nm due to surface Plasmon resonance. Particle size was estimated to be 2.6 ± 0.2 nm. Erbium and silver co-doped multielement oxide glasses were made by the melt quenching technique followed by heat treatment to induce nanoparticles. In heat treated samples, Er3+ luminescence increased 4× due to enhanced field in the vicinity of silver particles. Under excimer laser excitation, Er3+ and 2% Ag co-doped glass revealed Er3+ transitions due to enhanced field at the rare-earth ions. Under 795 nm laser excitation Er3+ green upconversion signals are found to be 4× stronger in 2% Ag co-doped, heat treated sample, than the others.

关键词： Silver Nanoparticles Field Enhanced Er3+ Luminescence Ag Er3+ Co-Doped Oxide Glass Sodium borate Glass

Grating Lobe Suppression with Element Count Optimization in Planar Antenna Array

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Journal of Electromagnetic Analysis and Applications 2015年第2期7卷 31-40页

作者： b. Rama Sanjeeva reddy D. Vakula Department of Electronics and Communication National Institute of Technology Warangal India

The novel approach of this paper describes the suppression of grating lobe level with the element count optimization in planar antenna array. Rectangular lattice (RL) and triangular lattice (TL) structures are chosen for determining the achievable array element patterns (EP) and further suppressing the grating lobe level. The element spacing and number of elements (10 × 20 array) are taken into account for particular lattice. Grating lobe peaks are observed for the 200-element planar array at maximum scan angle (θ) with the set frequency of 3 GHz. Further, it is found that 14°;bore sight elevation of rectangular lattice produces a transformed field of view, which permits a reduction in element count of 20.39% compared with 10° bore sight elevation. Finally, the typical values of elevation, element count and array size (25 cm2) are trained using artificial neural network (ANN) algorithm and element count is predicted after testing the network. The network shows a high success rate.

关键词： Rectangular Lattice (RL) Triangular Lattice (TL) Element Pattern (EP) Artificial Neural Network (ANN)

Zircon geochronology reveals polyphase magmatism and crustal anatexis in the buchan block,NE Scotland:Implications for the Grampian Orogeny

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Geoscience Frontiers 2017年第6期8卷 1469-1478页

作者： T.E.Johnson C.L.Kirkland D.R.Viete S.Fischer S.M.reddy N.J.Evans b.J.McDonald Department of Applied Geology The Institute for Geoscience Research(TIGeR)CET-Curtin NodeJohn de Laeter CentreCurtin UniversityPerthWA 6102Australia Morton K.blaustein Department of Earth&Planetary Sciences Johns Hopkins UniversityOlin Hall3400 N Charles StreetBaltimoreMD 21218USA School of Earth&Environmental Science University of St AndrewsIrvine BuildingNorth StreetSt AndrewsKY16 9ALScotlandUK

The type locality for high-temperature,low-pressure regional metamorphism,the buchan block in NE Scotland,exhibits profound differences to the rest of the Grampian *** differences have led some to regard the buchan block as an exotic crustal fragment comprising Precambrian basement gneisses and cover rocks thrust into their current position during Grampian *** rocks of the buchan block are now generally correlated with Dalradian strata elsewhere,the origin of the gneisses and the cause of the high heat flow and associated magmatism is *** report SIMS U-Pb and LA-ICPMS Hf isotopic data in zircon from high-grade rocks from the northeast(Inzie Head Gneiss)and northwest(Portsoy)corners of the buchan *** Inzie Head,upper amphibolite to granulite facies metasedimentary gneisses coexist with diorite sheets that were emplaced contemporaneously with partial melting of their host rocks,at least locally.U-Pb geochronology indicates a crystallisation age for the diorite of 486±9 ***-deformed diorites within the Portsoy Gabbro have a crystallisation age of 493±8 *** of ca.490 Ma for magmatism and high-grade metamorphism,which are broadly contemporaneous with ophiolite obduction and the onset of orogenesis,are significantly older than the established peak of Grampian metamorphism(ca.470 Ma).We propose a new model for the Grampian Orogeny involving punctuated tectonothermal activity due to tectonic switching during accretionary *** of a NW-dipping subduction zone at ca.490 Ma produced a back-arc environment(the buchan block)with associated arc magmatism and high dT/dP *** of an outboard arc resulted in shortening(the initial phase of the Grampian Orogeny)at ca.488 *** of a NW-dipping subduction zone to the SE of the ca.488 Ma suture began at 473 Ma and led to lithospheric-scale extension,decompression melting and advective heating of the middle crust,producing the widespread ca.470 Ma Gram

关键词： Dalradian Grampian Orogeny buchan block Zircon geochronology Magmatism Metamorphism

Influence of tool material and rotational speed on mechanical properties of friction stir welded AZ31b magnesium alloy

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Journal of Magnesium and Alloys 2015年第4期3卷 335-344页

作者： Ugender Singarapu Kumar Adepu Somi reddy Arumalle Department of Mechanical Engineering JNTUHyderabadTelangana 500085India Department of Mechanical Engineering NITWarangalTelangana 506004India Department of Mechanical Engineering VITSKarimnagarTelangana 505468India

In this investigation,the effect of friction stir welding(FSW)parameters such as tool material rotational speed,and welding speed on the mechanical properties of tensile strength,hardness and impact energy of magnesium alloy AZ31b was *** experiments were carried out as per Taguchi parametric design concepts and an L9 orthogonal array was used to study the influence of various combinations of process *** optimization technique,ANOVA,was used to determine the optimum levels and to find the significance of each process *** results indicate that rotational speed(RS)and traverse speed(TS)are the most significant factors,followed by tool material(TM),in deciding the mechanical properties of friction stir processed magnesium *** addition,mathematical models were developed to establish relationship between different process variables and mechanical properties.

关键词： Friction stir welding Tool material Mechanical properties Taguchi orthogonal array Analysis of variance(ANOVA)

Enhanced densification and mechanical properties of β-boron by in-situ formed boron-rich oxide

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Journal of Materials Science & Technology 2022年第4期99卷 148-160页

作者： Haibo Zhang Metin Örnek Simanta Lahkar Shuangxi Song Xiaodong Wang Richard A.Haber Kolan Madhav reddy School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Materials Science and Engineering RutgersThe State University of New JerseyPiscatawayNJ 08854USA

We report nearly full densification of polycrystalline rhombohedral beta(β)-boron without the addition of sintering aids via spark plasma sintering(SPS).The analytical aberration corrected transmission electron microscope observations have revealed in-situ growth of nanocrystalline boron-rich oxide precipitates that contain approximately 4 at.%of oxygen and beget the densification of β-*** electron energy loss spectroscopy and diffraction analysis confirmed that the newly formed boron-rich oxide(nominally b_(96)O_(4))structure with b-O σ-bonding belongs to space group R■*** sensitive nanoindentation showed boron-rich oxide phase has a hardness of about 41±2 GPa,which is 10%higher than that of β-boron *** estimated hardness and fracture toughness of β-boron were approximately 31 GPa and 2.2 MPa m^(1/2),respectively,using Vickers microindentation,which falls in the range of those commercially used boron *** results suggest that the enhanced densification and mechanical properties arise from the newly formed boron-rich oxide inβ-boron during SPS experiments.

关键词： boron Precipitates Sintering Mechanical properties Transmission electron microscopy

River mouth dynamics of Swarnamukhi estuary,Nellore coast,southeast coast of India

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Geodesy and Geodynamics 2016年第6期7卷 387-395页

作者： G.Sreeniuasulu N.Jayaraju b.C.Sundara Raja reddy T.Lakshmi Prasad b.Lakshmanna K.Nagalakshmi M.Prashantha Department of Geology Yogi Vemana UniuersityKadapaA.P.India Department of Geology Sri Venkateswara UniversityTirupatiA.P.India Department of Earth Sciences Yogi Vemana UniversityKadapaA.P.India School of Sciences Indira Gandhi National Open UniversityNew DelhiIndia

Swarnamukhi is an east flowing river having a total length of 130 km. This is an inde- pendent river which rises at an elevation of 300 m in the eastern Ghats ranges near Pakala village in Chittoor district of Andhra Pradesh, India. This study was carried out using multitemporal satellite images of IRS P6 LISS-III and Landsat 80LUTIRS data from 2011 to 2015. The subsequent short term river mouth dynamics, coastal erosion and accretion rates have been calculated for the years between 2011 and 2015. Low river inflow, wind, tides, movement of the waves and littoral currents play a key role in the dynamic activities of erosion and accretion. The erosion rate from 2011 to 2015 was slightly decreased from 0.081 to 0.027 km2. The total net rate of accretion was estimated at 0.438 km2. The study shows during last five years （2011-2015） accretion is more than the erosion. High fluctu- ation of erosion and accretion are characteristics for the short term scale at river mouth.

关键词： River mouth dynamicsErosion and accretionSwamamukhi estuary

Cardioprotective effect of bioassay-guided fractions of Cleome viscosa methanolic extract in streptozotocin-induced diabetic rats

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Asian Pacific Journal of Tropical biomedicine 2024年第11期14卷 486-499页

作者： Suresh Yarrappagaari Lavanya Thopireddy Srinivasulu Cheemanapalli Venkata Ramireddy Narala Rajeswara reddy Saddala Division of Ethnopharmacology Department of BiotechnologySchool of Herbal Studies and Naturo SciencesDravidian UniversityKuppam-517426Andhra PradeshIndia Department of Zoology KVR Government College for WomenKurnool-518004Andhra PradeshIndia Regional Ayurveda Research Institute Itanagar-791111Arumachal PradeshIndia Department of Zoology Yogi Vemana UniversityKadapa-516005Andhra PradeshIndia

Objective:To evaluate the cardioprotective effect of bioassay-guided isolated fractions of Cleome viscosa methanolic extract in streptozotocin-induced diabetic ***:Total phenolics,flavonoids,and in vitro antioxidant activities of the methanolic extract of Cleome viscosa were *** FD-40 fraction from this extract was further evaluated for antihyperglycemic efficacy(insulin and HbA1c),antioxidant activity,and cardioprotective effects(creatine kinase-Mb,lactate dehydrogenase,and histopathology)in streptozotocin-induced diabetic *** silico studies were also conducted to assess the bioactivity of ***:Cleome viscosa methanolic extract exhibited the highest antioxidant activity in DPPH,AbTS,H2O2,and FRAP assays compared to other *** with FD-40(40 mg/kg b.w.)isolated from this extract normalized blood glucose,insulin,HbA1c,creatine kinase-Mb,and lactate dehydrogenase levels in diabetic *** also significantly reduced oxidative stress by increasing antioxidant enzymes,decreasing lipid peroxidation as well as restoring the levels of ascorbic acid and *** study demonstrated that FD-40 treatment improved cardiac structure in diabetic *** docking analysis revealed that phytocompounds from FD-40 had strong binding affinities with cardiac markers and oxidative ***(5TMS)demonstrated greater binding affinity with xanthine oxidase and lactate ***:FD-40 of Cleome viscosa methanolic extract exhibits significant cardioprotective effects in diabetic rats by regulating cardiac markers and reducing oxidative *** underlying mechanisms need to be elucidated in the future.

关键词： Cleome viscosa L. Cardioprotection Cardiac markers Docking CK-Mb GC-MS Diabetes

Numerical simulation of self-similar thermal convection from a spinning cone in anisotropic porous medium

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Journal of Hydrodynamics 2016年第2期28卷 184-194页

作者： O. Anwar bEG M. J. UDDIN T. bEG R. reddy GORLA Spray Research Group Petroleum and Gas Engineering Division Room G77 Newton Building School of Computing Science and Engineering (CSE) University of Salford M54WT UK Department of Mathematics American International University-Bangladesh Dhaka Bangladesh Engineering Mechanics Associates Dickenson Road Manchester M 16 England UK Department Mechanical Engineering Cleveland State University Cleveland Ohio USA

Self-similar steady natural convection thermal boundary layer flow from a rotating vertical cone to anisotropic Darcian porous medium is investigated theoretically and numerically. The transformed non-dimensional two-point boundary value problem is reduced to a system of coupled, highly nonlinear ordinary differential equations, which are solved subject to robust surface and free stream boundary conditions with the MAPLE 17 numerical quadrature software. Validation with earlier non-rotating studies is included, and also further verification of rotating solutions is achieved with a variational finite element method （FEM）. The rotational （spin） parameter emerges as an inverse function of the Grashof number. The influence of this parameter, primary Darey number, secondary Darcy number and Prandtl number on tangential velocity and swirl velocity, temperature and heat transfer rate are studied in detail. It is found that the dimensionless tangential velocity increases whilst the dimensionless swirl velocity and temperature decrease with the swirl Darcy number, tangential Darcy number and the rotational parameters. The model finds applications in chemical engineering filtration processing, liquid coating and spinning cone distillation columns.

关键词： self-similarity spinning cone finite element method (FEM) anisotropic porous medium heat transfer MAPLE FEM

Ni_(3)b modified biVO_(4) photoanodes for enhanced photoelectrochemical water splitting:The key role of Ni_(3)b on reducing the water oxidation barrier

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Nano Research 2023年第10期16卷 12043-12049页

作者： Kehui Xue Haifeng Zhu Xingyu Zhao Liana Alvares Rodrigues D.Amaranatha reddy Yaping Zhang Lianqing Yu School of Materials Science and Engineering China University of Petroleum(East China)QingDao 266580China College of Science China University of Petroleum(East China)QingDao 266580China Engineering School of Lorena University of São PauloCEP 12602-810São PauloBrazil Indian Institute of Information Technology Design and Manufacturing Kurnool 518007India

bismuth vanadate(biVO_(4),bVO)as a promising photoelectrode has been received great attention for photoelectrochemical(PEC)water ***,the slow oxidation kinetics on the surface of biVO_(4)limited the PEC water splitting ***,nickel boride(Ni_(3)b,Nb)nanoparticles,generally used in electrocatalytic field material,were modified on the surface of biVO_(4)photoelectrode as an efficient cocatalyst to accelerate the oxygen evolution *** as-prepared bVO-Nb-5P photoelectrode exhibits a remarkable photocurrent density of 1.47 mA·cm^(−2)at 1.23 V versus the reversible hydrogen electrode(RHE)under air mass(AM)1.5 G illumination,which is about 2.8 times higher than the bare biVO_(4)photoelectrode,and its water splitting rate is 11.3 times higher than bare biVO_(4).The PEC studies reveal that the spin coated Ni_(3)b crystal cocatalyst could effectively reduce the water oxidation barrier,and improve the surface charge injection efficiency to 94%,which could boost the photogenerated holes reaction to enhance the PEC performance of biVO_(4)photoelectrode.

关键词： photoelectrochemical water splitting biVO_(4) Ni_(3)b