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mechanical properties of Ni_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)particulate composites by composite oscillator technique and the correlation with the results of magnetoelectric properties

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Journal of Advanced Ceramics 2012年第4期1卷 317-326页

作者： m.venkata ramana m.Penchal REDDY N.Ramamanohar REDDY B.S.mURTY K.V.SIVA KUmAR Shenhua SONG Shenzhen Key Laboratory of Advanced materials Department of Materials Science and EngineeringShenzhen Graduate SchoolHarbin Institute of TechnologyShenzhen 518055China Department of Physics Changwon National UniversityChangwonRepublic of Korea Ceramic Composite materials Laboratory Department of PhysicsSri Krishnadevaraya UniversityAnantapur 515003India Nanotechnology Laboratory Department of Metallurgical and Materials EngineeringIndian Institute of TechnologyChennai 600036India

The xNi_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)(PZT)particulate magneto ferroelectric composites with x=0,0.1,0.2,0.3,0.4,0.5 and 0.6 mole fraction were prepared by conventional ceramic double sintering *** presence of two phases(perovskite structure of ferroelectric phase and spinal structure of ferromagnetic phase)was confirmed by X-ray *** magnetoelectric(mE)property of the particulate composites was determined at room temperature as a function of intensity of magnetic *** temperature variation of the longitudinal modulus(L)and the internal friction(Q−1)of these particulate composites at 104.3 kHz was studied in the wide temperature range 30-420℃.The temperature variation of the longitudinal modulus in each composition of these particulate composites showed two abrupt *** minimum coincided with the ferroelectric-paraelectric Curie transition temperature(θE)and the other with the ferromagnetic-paramagnetic Curie transition temperature(θm).The internal friction measurement also showed two sharp peaks in each composition corresponding to those temperatures where the minima were noticed in the temperature variation of the longitudinal modulus behaviour.

关键词： X-ray diffraction magnetoelectric effect piezoelectric coefficient internal friction Curie transition temperature

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SYNTHESIS OF LEAD FREE SODIUm BISmUTH TITANATE(NBT)CERAmIC BY CONVENTIONAL AND mICROWAVE SINTERING mETHODS

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Journal of Advanced Dielectrics 2011年第1期1卷 71-77页

作者： m.venkata ramana S.ROOPAS KIRAN N.RAmAmANOHAR REDDY K.V.SIVA KUmAR V.R.K.mURTHY B.S.mURTY Ceramic Composite materials Laboratory Department of Physics Sri Krishnadevaraya UniversityAnantapur 515003India microwave Laboratory Department of Physics Indian Institute of Technology Chennai 600036India Nanotechnology Laboratory Department of metallurgical and materials Engineering Indian Institute of Technology Chennai 600036 India

Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))*** material was synthesized by conventional ceramic method(CS)and microwave sintering(mS).The presence of single phase has been confirmed by X-ray diffraction and scanning electron microscopy of NBT *** later technique(mS)resulted in material with high density,dielectric properties and improved *** transition temperature was observed slightly higher for microwave sintered(mS)*** modulus measurements are very sensitive property to identify the phase transitions in *** modulus(L)measurements were also employed on these samples in the frequency 136 kHz and can be studied in the wide temperature range 30℃to 400℃.The elastic behavior(L)showed a break at two temperatures(~200℃and 350℃)in both the conventional and microwave sintered *** NBT ceramics,permittivity anomalies are connected to modulus *** results are correlated with the dielectric *** behavior explained in the light of structural phase transitions in the ferroelectric ceramics.

关键词： microwave sintering NBT X-ray diffractometer scanning electron microscopy dielectric properties longitudinal modulus

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An SPH Framework for Earthquake-Induced Liquefaction Hazard Assessment of Geotechnical Structures

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Computer modeling in Engineering & Sciences 2025年第1期142卷 251-277页

作者： Sourabh mhaski G.V.ramana Department of Civil Engineering Indian Institute of Technology DelhiNew Delhi110016India

Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures *** understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient *** present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the Pm4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile ***,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando *** agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical *** present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.

关键词： Earthquake seismic liquefaction stress particle Pm4Sand smoothed particle hydrodynamics(SPH)

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Controlled Drug Release Studies of Atenolol Using Differently Sulfonated Acryloxyacetophenone and methyl methacrylate Copolymer Resins as Drug Carriers

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Chinese Journal of Polymer Science 2014年第3期32卷 280-291页

作者： K.Doraswamy P.venkata ramana Department of Chemistry Sri Krishnadevaraya University

2-Acryloxyacetophenone （AAP） was prepared and subjected to suspension polymerization with methyl methacrylate （mmA） using azobisisobutyronitrile （AIBN） as free radical initiator. The differently sulfonated AAP-mmA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70 ~C. Several characteristics of the prepared resins were evaluated, i.e. FTIR, the ion-exchange capacity （IEC）, thermo gravimetric analysis （TGA）, particle size distribution and microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of atenolol （ATL） loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonation and hence the drug binding site in resin employed. The drug release was lower from the resins with higher content of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid （SGF） than in stimulated intestinal fluids （SIF）. The basic groups, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery.

关键词： 2-Acryloxyacetophenone methyl methacrylate Different sulfonation Cationic exchange resins Atenolol In vitro drug release.

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Optimization of luminescence properties of Tb^(3+)-doped a-Sr_2P_2O_7 phosphor synthesized by combustion method

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Rare metals 2018年第7期37卷 587-593页

作者： Nimesh Prafulbhai Patel mangalampalli Srinivas Dhaval modi Vishwnath Verma Kota venkata ramana murthy Luminescence material Laboratory Department of PhysicsFaculty of Science The M. S. University of Baroda Vadodara 390002 India Display materials Laboratory Applied Physics DepartmentFaculty of Technology and Engineering The M. S. University of Baroda Vadodara 390001 India

In this paper, thermoluminescence （TL） properties of rare earth Tb^3＋-doped α-Sr2P2O7 were examined after β-irradiation and photoluminescence （PL） properties of samples were examined for proper excitation. All the samples were synthesized by high-temperature combustion method. The X-ray diffraction （XRD） and Fourier transform infrared （FTIR） spectroscopy characterization confirms the formation of pure α-phase with crystallized in orthorhombic structure of samples. The PL emission spectra of all samples exhibit characteristic green emission peaks of Tb^3＋ where the peak at 545 nm has the highest emission intensity for Tb^3＋ con- centration of 5.0 mol%. The TL glow curves of β-irradiated Tb^3＋-doped α-Sr2P2O7 phosphors were recorded at different heating rates of 2, 4, and 6 K.s^-1. TL curves of all sample exhibit combination of two peaks： peak at 420 K shifts toward higher 525 K remains unaffected temperature, while peak at with the increase in Tb^3＋ concentration as well as fading effect. The activation energy and kinetic parameters of the samples were evaluated using thermoluminescence peak shape method.

关键词： Rare earth doping Strontium pyrophosphate β-Irradiation Photoluminescence Thermoluminescence

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A review on anti-bacterials to combat resistance: From ancient era of plants and metals to present and future perspectives of green nano technological combinations

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Asian Journal of Pharmaceutical Sciences 2020年第1期15卷 42-59页

作者： Lakshmi Kalyani Ruddaraju Sri venkata Narayana Pammi Girija sankar Guntuku Veerabhadra Swamy Padavala venkata ramana murthy Kolapalli Department of Pharmaceutics Shri Vishnu College of PharmacyBhimauaram 534202India Department of materials Science and Engineering Chungnam National UniversityRepublic of Korea A.U.College of Pharmaceutical Sciences Visakhapatnam 530003India

In the primitive era, humans benefited partially from plants and metals to treat microbial infections. Later these infections were cured with antibiotics but further suffered from resistance issues. In searching of an alternative, researchers developed an adjuvant therapy but were hampered by spreading resistance. Subsequently, nanoparticles(NPs) were proposed to cease the multi-drug resistant bacteria but were hindered due to toxicity issues. Recently, a novel adjuvant therapy employed metals and botanicals into innovative nanotechnology as nano-antibiotics. The combination of green synthesized metallic NPs with antibiotics seems to be a viable platform to combat against mDR bacteria by alleviating resistance and toxicity. This review focuses on the primitive to present era dealings with bacterial resistance mechanisms, newer innovations of nanotechnology and their multiple mechanisms to combat resistance. In addition, special focus is paid on greener NPs as antibiotic carriers, and their future prospects of controlled release and toxicity study.

关键词： Antibiotics Bacterial resistance Green nanotechnology Adjuvant therapy Toxicity

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Non-Aligned Stagnation Point Flow of a Casson Fluid Past a Stretching Sheet in a Doubly Stratified medium

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Fluid Dynamics & materials Processing 2019年第3期15卷 233-251页

作者： N.Vijaya G.venkata ramana Reddy Y.Hara Krishna Koneru Lakshmaiah Education Foundation VaddeswaramGuntur522502India

This paper investigates the problem of oblique hydro magnetic stagnation point flow of an electrically conducting Casson fluid over stretching sheet embedded in a doubly stratified medium in the presence of thermal radiation and heat source/absorption with first order chemical *** is assumed that the fluid impinges on the wall *** variables were used to convert the partial differential equations to ordinary differential *** transformed ordinary differential equations are solved numerically using Runge-Kutta-Fehlberg method with shooting *** is observed that a boundary layer is formed when the stretching velocity of the surface is less than the in viscid free stream velocity at a point decreases with increase in the non-Newtonian rheology *** augmentation of the temperature is observed with the magnetic parameter,heat source parameter and thermal radiation parameter while a reverse effect with thermal stratification number,Prandtl number and the velocity ratio *** of Skin friction coefficient,Nusselt number and Sherwood number on the flow configurations for different values of pertinent parameters are portrayed graphically and *** results are compared with the published results and are found to be in good agreement with previously published results as special cases of present *** mass concentration is seen to be decrease with Schmidt number,chemical reaction parameter and solutal stratification number.

关键词： magnetic parameter heat source prandtl number chemical reaction casson fluid free stream stagnation flow parameters

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Effect of grain size on dielectric and ferroelectric properties of nanostructured Ba_0.8)Sr_(0.2)TiO_(3) ceramics

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Journal of Advanced Ceramics 2015年第1期4卷 46-53页

作者： venkata ramana mUDINEPALLI Leng FENG Wen-Chin LIN B.S.mURTY Department of Physics “National Taiwan Normal University”Taipei 11677TaiwanChina Department of Chemistry Shenzhen Graduate SchoolPeking UniversityShenzhen 518055China Nanotechnology Laboratory Department of Metallurgical and Materials EngineeringIndian Institute of Technology-MadrasChennai 600036India

Barium strontium titanate( Ba_0.8)Sr_(0.2)TiO_(3),BST)nanocrystalline ceramics have been synthesized by high energy ball *** the sintering temperature increases from 1200℃to 1350℃,the average grain size of BST ceramics increases from 86 nm to 123 *** X-ray diffraction(XRD)studies show that these ceramics are *** phase and grain size of the sintered pellets have been estimated from the XRD patterns,scanning electron microscopy(SEm)and transmission electron microscopy(TEm)*** effect of grain size on dielectric and ferroelectric properties is *** dielectric and piezoelectric parameters are greatly improved at room temperature with increase in grain *** Curie transition temperature is found to shift slightly towards higher temperatures as the grain increases from 86 nm to 123 *** coercive field decreases and the remnant polarization and spontaneous polarization increase as the grain size of BST nano ceramics *** ceramics are promising materials for tunable capacitor device applications.

关键词： nanocrystalline ceramics lead free ceramics crystallization electron microscopy dielectric properties hysteresis

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Silica gel catalyzed α-bromination of ketones using N-bromosuccinimide: An easy and rapid method

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Chinese Chemical Letters 2014年第1期25卷 179-182页

作者： Bodireddy mohan Reddy Velpula venkata ramana Kumar Nallagondu Chinna Gangi Reddy Siripragada mahender Raob Department of Chemistry School of Physical SciencesYogi Vemana University Research & Development (API) Centre Panacea Biotech Ltd.B-1 Extn./A-27Mohan Co-operative Industrial Estate

An easy and rapid method for the α-bromination of ketones using N-bromosuccinimide （NBS） catalyzed by silica gel in methanol under reflux conditions was developed. The expected products were formed in excellent isolated yields within a short period of time （5-20 min）. major advantages of the present procedure include use of inexpensive and readily available catalyst, exclusion of pre- and post-chemical treatment of catalyst and use of methanol as solvent instead of ethers and chlorinated solvents.

关键词： Heterogeneous catalysis α-Brominatio nN-bromosuccinimide (NBS)Silica gel Ketones

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Drug Transport microdevice mimicking an Idealized Nanoscale Bio-molecular motor

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Journal of Bionic Engineering 2011年第4期8卷 455-463页

作者： Jae Hwan Lee ramana m. Pidaparti Department of mechanical Engineering Virginia Commonwealth University Richmond VA 23284 USA

molecular motors are nature＇s nano-devices and the essential agents of movement that are an integral part of many living organisms. The supramolecular motor, called Nuclear Pore Complex （NPC）, controls the transport of all cellular material be- tween the cytoplasm and the nucleus that occurs naturally in biological cells of many organisms. In order to understand the design characteristics of the NPC, we developed a microdevice for drug/fluidic transport mimicking the coarse-grained repre- sentation of the NPC geometry through computational fluid dynamic analysis and optimization. Specifically, the role of the central plug in active fluidic/particle transport and passive transport （without central plug） was investigated. Results of flow rate, pressure and velocity profiles obtained from the models indicate that the central plug plays a major role in transport through this biomolecular machine. The results ofthis investigation show that fluidic transport and flow passages are important factors in designing NPC based nano- and micro-devices for drug delivery.

关键词： molecular motors nuclear pore complex geometry design simulation

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