SORET, HALL CURRENT, ROTATION, CHEMICAL REACTION AND THERMAL RADIATION EFFECTS ON UNSTEADY MHD HEAT AND MASS TRANSFER NATURAL CONVECTION FLOW PAST AN ACCELERATED VERTICAL PLATE

M. VENKATESWARLU,D. VENKATA LAKSHMI,K. NAGA MALLESWARA RAO 한국산업응용수학회 2016 Journal of the Korean Society for Industrial and A Vol.20 No.3

The heat and mass transfer characteristics of the unsteady hydromagnetic natural convection flow with Hall current and Soret effect of an incompressible, viscous, electrically conducting, heat absorbing and optically thin radiating fluid flow past a suddenly started vertical infinite plate through fluid saturated porous medium in a rotating environment are taken into account in this paper. Derivations of exact analytical solutions are aimed under different physical properties. The velocity, concentration and temperature profiles, Sherwood number and Nusselt number are easily examined and discussed via the closed forms obtained. Soret effect and permeability parameter tends to accelerate primary and secondary fluid velocities whereas hall current, radiation and heat absorption have reverse effect on it. Radiation and heat absorption have tendency to enhance rate of heat transfer at the plate. The results obtained here may be further used to verify the validity of obtained numerical solutions for more complicated transient free convection fluid flow problems.

Annealing Temperature Dependent Structural and Magnetic Properties of Ni-Cu-Zn Nanoferrites

P. Venkata Srinivasa Rao,T. Anjaneyulu,M. Rami Reddy 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.5

The effect of annealing temperature on the structural and the magnetic properties of Ni0.5Cu0.25Zn0.25Fe2O4 (Ni−Cu−Zn) nanoferrites synthesized using an oxalic-based precursor method was investigated in detail. A single phase of the Ni−Cu−Zn ferrite was observed from X-ray diffraction (XRD) data. From the XRD analysis, the grain size was found to increase with increasing annealing temperature from 500 to 800 °C whereas the lattice constant was found to decrease. The scanning electron microscope (SEM) analysis showed nanosize grains in the prepared samples. The magnetization analysis showed that the saturation magnetization (Ms) increased with increasing annealing temperature due to the increasing grain size whereas the coercivity (Hc) and the remanence magnetization (Mr) showed decreasing behaviors. The Curie temperature (TC) was measured for all samples. As the grain size increased the Curie temperature was also observed to increase. For these samples, the Curie temperatures lies between 426 K to 504 K. The dielectric constant (ε') was observed to be higher for these samples. The dielectric loss tangent increase slowly with increasing frequency till a particular frequency, after that it slowly decreased. Therefore the annealing temperature was observed to have a significant effect on the structural, magnetic and electrical properties of synthesized Ni−Cu−Zn ferrite.

Effect of Gd Doping on the Structural and Magnetic Properties of Ni-Cu-Zn-Fe$_2$O$_4$

P. Venkata Srinivasa Rao,T. Anjaneyulu,M. Rami Reddy 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.4

Ni$_{0.5}$Cu$_{0.25}$Zn$_{0.25}$Gd$_x$Fe$_{2-x}$O$_4$ ($x$ = 0.0, 0.025, 0.05, 0.075, 0.1) ferrites were synthesized using an oxalic-based precursor method. A single phase Ni-Cu-Zn-Gd ferrite was observed from X-ray diffraction (XRD) data except for higher Gd content. For $x$ = 0.1, a secondary phase due GdFe$_2$O$_3$ was observed. The particle size was observed to decrease and the lattice constant to increase with increasing Gd doping concentration. The IR spectra confirmed the existence of bands corresponding to spinel ferrites. The IR band positions were observed to shift towards higher positions with increasing Gd doping concentration. The saturation magnetization, coercivity and remanence magnetization were observed to increase as a result of Gd doping. The substitution of Gd ions in the place of Fe ions resulted in changes in the structural and magnetic properties due to replacement of smaller ionic radii Fe ions by larger ionic radii Gd ions.

Posterior superior alveolar nerve block alone in the extraction of upper third molars: a prospective clinical study

Swathi Tummalapalli,Ravi Sekhar M,Naga Malleswara Rao Inturi,Venkata Ramana Murthy V,Rama Krishna Suvvari,Lakshmi Prasanna Polamarasetty 대한치과마취과학회 2023 Journal of Dental Anesthesia and Pain Medicine Vol.23 No.4

Background: Third molar extraction is the most commonly performed minor oral surgical procedure in outpatient settings and requires regional anesthesia for pain control. Extraction of the maxillary molars commonly requires both posterior superior alveolar nerve block (PSANB) and greater palatine nerve block (GPNB), depending on the nerve innervations of the subject teeth. We aimed to study the effectiveness of PSANB alone in maxillary third molar (MTM) extraction. Methods: A sample size comprising 100 erupted and semi-erupted MTM was selected and subjected to study for extraction. Under strict aseptic conditions, the patients were subjected to the classical local anesthesia technique of PSANB alone with 2% lignocaine hydrochloride and adrenaline 1:80,000. After a latency period of 10 min, objective assessment of the buccal and palatal mucosa was performed. A numerical rating scale and visual analog scale were used. Results: In the post-latency period of 10 min, the depth of anesthesia obtained in our sample on the buccal side extended from the maxillary tuberosity posteriorly to the mesial of the first premolar (15%), second premolar (41%), and first molar (44%). This inferred that anesthesia was effectively high until the first molars and was less effective further anteriorly due to nerve innervation. The depth of anesthesia on the palatal aspect was up to the first molar (33%), second molar (67%), and lateromedially; 6% of the patients received anesthesia only to the alveolar region, whereas 66% received up to 1.5 cm to the mid-palatal raphe. In 5% of the cases, regional anesthesia was re-administered. An additional 1.8 ml PSANB was required in four patients, and another patient was administered a GPNB in addition to the PSANB during the time of extraction and elevation. Conclusion: The results of our study emphasize that PSANB alone is sufficient for the extraction of MTM in most cases, thereby obviating the need for poorly tolerated palatal injections.

Time Varied Morphology Controllable Fabrication of NiS Nanosheets Structured Thin Film and its Application as a Counter Electrode for QDSSC

Thulasi-Varma, Chebrolu Venkata,Gopi, Chandu V. V. M.,Rao, S. Srinivasa,Punnoose, Dinah,Kim, Soo-Kyoung,Kim, Hee-Je American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.21

<P>A novel strategy has been successfully developed for highly efficient nanosheet-structured NiS counter electrodes. The NiS was deposited on FTO substrate with different deposition times using the simple and cost-effective chemical bath deposition technique. The NiS CEs were used to grow high quality thin films containing nanoparticles, nanosheets, or nanorods. The nanosheet-structured NiS CE in QDSSCs under one-sun illumination (AM 1.5, 100 Mw cm<SUP>–2</SUP>) yielded a high short circuit current density (<I>J</I><SUB>sc</SUB>) of 13.53 mA cm<SUP>–2</SUP>, open circuit voltage (<I>V</I><SUB>oc</SUB>) of 0.570 V, fill factor (FF) of 0.450, and power conversion efficiency (η) of 3.47%. These values are much higher than those of the Pt CE (<I>J</I><SUB>sc</SUB> = 7.85 mA cm<SUP>–2</SUP>, <I>V</I><SUB>oc</SUB> = 0.611, FF = 0.243, and η = 1.170%). The NiS was strongly adhered on the FTO substrate by acetic acid which acts as stabilizer and strong reagent in this one step preparation. The performance of NiS CE was improved by the surface morphology, which enable rapid electron transport and a lower electron recombination rate for the polysulfide electrolyte redox couple. In the present study NiS has obtained higher electrocatalytic activity which plays a crucial role in the QDSSC. Electrochemical impedance spectroscopy and Tafel-polarization measurements were used to investigate the electrocatalytic activity of the NiS and Pt CEs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-21/acs.jpcc.5b01771/production/images/medium/jp-2015-01771s_0001.gif'></P>

Electrochemical growth of NiS nanoparticle thin film as counter electrode for quantum dot-sensitized solar cells

Lee, Y.S.,Gopi, C.V.V.M.,Venkata-Haritha, M.,Rao, S.S.,Kim, H.J. Elsevier Sequoia 2017 Journal of photochemistry and photobiology Chemist Vol. No.

The high stability and superior electrocatalytic activity of counter electrodes (CEs) are crucial but important issues in high performance quantum dot-sensitized solar cells (QDSSCs). To address the above issues, nanoparticle-structured nickel sulfide (NiS) thin film electrodes were prepared on F-doped SnO<SUB>2</SUB> glass (FTO glass) substrates using a facile chemical bath deposition method at different growth times and used directly as the CEs for CdS/CdSe/ZnS QDSSCs. The surface morphology and thickness of the resulting NiS films are greatly affected by the deposition time. By optimizing the growth time of the NiS CE materials, a power conversion efficiency up to 3.25% was achieved for CdS/CdSe/ZnS based QDSSCs, which was much higher than that of the Pt CE (0.79%). In addition, a preliminary durability test of the CE in QDSSCs reveals that the NiS CE exhibited good stability than the Pt CE. The improved performance of the QDSSC was attributed to the resulting electrochemical catalytic activity of the NiS CE with efficient charge transfer at the CE/electrolyte interface, which was verified by the electrochemical impedance spectroscopy and the Tafel polarization measurement results. Therefore, the excellent electrochemical performance of NiS highlights its promising application as a CE for high performance QDSSCs.

Promotional role of Ceria in CeO2/MgAl2O4 spinel catalysts in CO2 assisted selective oxidative dehydrogenation of ethylbenzene to styrene

Ch. Prathap,V. V. Ramana Kumar,M. Venkata Rao,P. Nagaiah,S. Rama Rao K.,B. David Raju 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-

With the aim of understanding the influence of CeO2 on MgO, Al2O3 and MgAl2O4 in CO2 assistedoxidative dehydrogenation of ethylbenzene to styrene was attempted and the results conveyed that theMgAl2O4 spinel supported CeO2 (CeO2/MgAl2O4) catalyst exhibited superior activity with 80% yield ofstyrene and in apart activity consistency up to 50 h of time-on-stream, revealing the establishment ofsynergism in CeO2/MgAl2O4, ascertained from XRD, BET Surface area, FT-IR, H2-TPR, UV–vis DRS, XPS, TPDand HRTEM techniques, acid-base characteristics of MgAl2O4, smaller particle size of CeO2 and its highdispersion are responsible for elevated activity, stability and regenarable capability.

Cost-effective and morphology controllable PVP based highly efficient CuS counter electrodes for high-efficiency quantum dot-sensitized solar cells

Kim, Hee-Je,Myung-Sik, Lee,Gopi, Chandu V. V. M.,Venkata-Haritha, M.,Rao, S. Srinivasa,Kim, Soo-Kyoung The Royal Society of Chemistry 2015 Dalton Transactions Vol.44 No.25

<P>Currently, copper sulfide (CuS) is the most commonly used counter electrode (CE) in high-efficiency quantum dot-sensitized solar cells (QDSSCs) because of its superior electrocatalytic activity in the presence of polysulfide electrolyte. For the first time, CuS thin films were prepared by a facile chemical bath deposition method with different concentrations of polyvinylpyrrolidone (PVP) and directly used as CEs in QDSSCs without any further post treatment. The quantum dot photoanode with the optimized 0.25 mM PVP-based CuS CE exhibits higher short circuit current density (<I>J</I><SUB>sc</SUB>), open circuit voltage (<I>V</I><SUB>oc</SUB>), fill factor (FF), and power conversion efficiency (PCE) of 17.57 mA cm<SUP>−2</SUP>, 0.578 V, 0.514, and 5.22%, respectively, which are much higher values than those of a bare CuS CE (<I>J</I><SUB>sc</SUB>: 12.36 mA cm<SUP>−2</SUP>; <I>V</I><SUB>oc</SUB>: 0.591 V; FF: 0.436; PCE: 3.18%) and Pt CE (<I>J</I><SUB>sc</SUB>: 11.25 mA cm<SUP>−2</SUP>; <I>V</I><SUB>oc</SUB>: 0.464 V; FF: 0.296; PCE: 1.54%) under one-sun illumination (AM 1.5 G, 100 mW cm<SUP>−2</SUP>). Moreover, the 0.25 mM PVP-based CuS CE produces a charge-transfer resistance of only 4.39 Ω with the aqueous polysulfide electrolyte commonly applied in QDSSCs. This value is several orders of magnitude lower than that of a typical Pt electrode (69.75 Ω) and bare CuS electrode (9.27 Ω). This enhancement is mainly attributed to the improved morphology of the 0.25 mM CuS CE with high catalytic activity, which plays a main role in the reduction processes of the oxidized polysulfide electrolyte, as well as the increased sulfur atomic percentage with Cu vacancies. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization were performed to study the underlying reasons behind the efficient CE performance.</P> <P>Graphic Abstract</P><P>A maximum efficiency of 5.22% was achieved with the optimized 0.25 mM PVP based Mn–CuS counter electrode. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5dt01412c'> </P>