93 results on '"Ravi, G."'
Search Results
2. Role of Transporters and Enzymes in Metabolism and Distribution of 4-Chlorokynurenine (AV-101)
- Author
-
Patel, Waseema, Shankar, Ravi G., Smith, Mark A., Snodgrass, H. Ralph, Pirmohamed, Munir, Jorgensen, Andrea L., Alfirevic, Ana, and Dickens, David
- Abstract
4-Chlorokynurenine (4-Cl-KYN, AV-101) is a prodrug of a NMDA receptor antagonist and is in clinical development for potential CNS indications. We sought to further understand the distribution and metabolism of 4-Cl-KYN, as this information might provide a strategy to enhance the clinical development of this drug. We used excretion studies in rats, in vitrotransporter assays, and pharmacogenetic analysis of clinical trial data to determine how 4-Cl-KYN and metabolites are distributed. Our data indicated that a novel acetylated metabolite (N-acetyl-4-Cl-KYN) did not affect the uptake of 4-Cl-KYN across the blood–brain barrier via LAT1. 4-Cl-KYN and its metabolites were found to be renally excreted in rodents. In addition, we found that N-acetyl-4-Cl-KYN inhibited renal and hepatic transporters involved in excretion. Thus, this metabolite has the potential to limit the excretion of a range of compounds. Our pharmacogenetic analysis found that a SNP in N-acetyltransferase 8 (NAT8, rs13538) was linked to levels of N-acetyl-4-Cl-KYN relative to 4-Cl-KYN found in the plasma and that a SNP in SLC7A5(rs28582913) was associated with the plasma levels of the active metabolite, 7-Cl-KYNA. Thus, we have a pharmacogenetics-based association for plasma drug level that could aid in the drug development of 4-Cl-KYN and have investigated the interaction of a novel metabolite with drug transporters.
- Published
- 2024
- Full Text
- View/download PDF
3. Synthesis and characterization of Mn3O4/MnSnO3nanocomposites for supercapacitor applications
- Author
-
Shobana, R., Saravanakumar, B., Ravi, G., Ganesh, V., and Yuvakkumar, R.
- Abstract
Mn3O4/MnSnO3nanocomposites have been successfully synthesized via solvothermal method by using the mixed solution consisting of manganese chloride and tin chloride salt dissolved in the mixture of ethanol and deionized water in 50:50 ratio at the processing temperature of 180 °C by adapting different capping agents such as PVP, PVA and ethylene glycol. The synthesized Mn3O4/MnSnO3nanocomposites were characterized by employing X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence spectra and scanning electron microscopy (SEM) studies. The obtained XRD spectra confirmed the formations of Mn3O4/MnSnO3nanocomposite illustrated by the sharp predominant diffraction peak observed at 34.2° corresponding to the (021) lattice planes of Mn3O4. The SEM images supply the information about the morphology of synthesized Mn3O4/MnSnO3nanocomposites. The sharp peaks observed at 483 cm−1further characterize the presence of Mn–O stretching vibration bond in Mn3O4/MnSnO3nanocomposite by employing Raman spectra. The PL result revealed the emissive nature of the sample. FTIR spectra observed at 625 cm−1attributed to the characteristic peaks of Mn3O4/MnSnO3nanocomposite. The Mn3O4/MnSnO3nanocomposite synthesized by the assistance of PVP surfactant exhibits the high specific capacitance of 178.2 F g−1at 0.5 Ag−1current density which can be considered as potential candidate and excellent electrode for pseudocapacitors applications.
- Published
- 2024
- Full Text
- View/download PDF
4. Dynamic modeling and control of five phase SVPWM inverter fed induction motor drive with intelligent speed controller
- Author
-
Raja, D. and Ravi, G.
- Abstract
Multi-phase induction motor (IM) drive is an emerging field of electric drive applications. This enables us to use the multi-phase AC machine than a three-phase machine. Precision speed control is important for industrial applications. Hence, direct torque control (DTC) with PI or PID regulators used, and these regulators are not flexible because of a constant gain in all working conditions. Therefore, robust speed control is essential for the precision speed control in industrial applications. The major objective of this study is to investigate a novel speed control for DTC of 5-ϕ VSI with space vector PWM (SVPWM) technique fed IM drive using wavelet fuzzy logic interface system. In precise, wavelet-fuzzy controller is an alternative for the PID controller used for DTC IM drive. The speed error signal comprises many short and extraordinary-frequency components. The scaled gains are generated for a DTC IM drive by the decomposition of discrete wavelet transform and the fuzzy logic controller (FLC) from high and low-frequency signals. The investigation of 2 hp 5-ϕ VSI fed IMD is carried out using the simulation model developed in MATLAB2016a software and examined under various working conditions. The simulation results are shown in this paper to confirm the suitability for industrial applications.
- Published
- 2024
- Full Text
- View/download PDF
5. Hybrid sparse and block-based compressive sensing algorithm for industry based applications
- Author
-
Sekar, R., Devarajan, N. Manikanda, Ravi, G., Rajasekaran, B., and Chidambaram, S.
- Abstract
Image reconstructions are a challenging task in MRI images. The performance of the MRI image can be measure by following parameters like mean squared error (MSE), peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM). Compromising the above parameters and reconstructing the MRI image leads to false diagnosing. To avoid the false diagnosis, we have combined sparse based compressive sensing and block-based compressive sensing algorithm, and we introduced the hybrid sparse and block-based compressive sensing algorithm (HSBCS). In compressive stage, however, image reconstruction performance is decreased, hence, in the image reconstruction module, we have introduced convex relaxation algorithm. This proposed algorithm is obtained by relaxing some of the constraints of the original problem and meanwhile extending the objective function to the larger space. The performance is compared with the existing algorithm, block-based compressive sensing algorithm (BCS), BCS based on discrete wavelet transform (DWT), and sparse based compress-sensing algorithm (SCS). The experimentation is carried out using BRATS dataset, and the performance of image compression HSBCS evaluated based on SSIM, and PSNR, which attained 56.19 dB, and 0.9812.
- Published
- 2024
- Full Text
- View/download PDF
6. Ionic Liquid Passivator for Mesoporous Titanium Dioxide Electron Transport Layer to Enhance the Efficiency and Stability of Hole Conductor-Free Perovskite Solar Cells
- Author
-
Mohammed, Mustafa K. A., Al-Mousoi, Ali K., Singh, Sangeeta, Younis, Umer, Kumar, Anjan, Dastan, Davoud, and Ravi, G.
- Abstract
Photovoltaic solar cells based on perovskite materials due to their unique optoelectronic properties are good instruments to develop green energy for worldwide energy demands. In perovskite solar cells (PSCs), a high performance of 25.8% was reported, employing an expensive Spiro-OMeTAD hole transport layer. Here, the study is focused on PSCs without any HTLs (HTL-free PSCs) to reduce the fabrication process costs. The electron transport layers (ETLs) are treated with tetramethylammonium hydroxide (TMAOH) to improve the efficiency of HTL-free devices. By employing a treatment step, the conductivity of ETLs is increased while their transparency is kept safe. The improved conductivity leads to accelerated charge transport within the device and reduces electron–hole recombination. The perovskite layers fabricated on the treated ETLs showed lower surface defects due to better spreading of the perovskite solution on them. The reduced surface defects cause improvements in the photovoltaic performance of HTL-free PSCs, leading to a stability increment due to lower surface defects for the reaction of humidity with the perovskite layer. TMAOH treatment results in PSCs with a maximum PCE of 13.24%, higher than the 10.88% for control devices.
- Published
- 2022
- Full Text
- View/download PDF
7. Investigation of Subsonic to Supersonic Transition of a Low-Pressure Plasma Torch Jet
- Author
-
Mohanta, Ram Krushna and Ravi, G.
- Abstract
The plasma jet emanating out of a thermal plasma torch operating at low pressure (
$\sim 30$ - Published
- 2022
- Full Text
- View/download PDF
8. Investigation of the effect of precoalescence or postcoalescence crosslinking on film formation, properties, and latex morphology
- Author
-
Joshi, Ravi G., Provder, Theodor, Ziemer, Paul, Mao, Wenjing, Shen, Weidian, and Jones, Frank N.
- Subjects
Amides ,Motion pictures ,Coatings industry ,Crosslinked polymers ,Glycols ,Metals, metalworking and machinery industries - Abstract
Abstract Latexes have many product applications including functioning as a binder in coatings. For many years, coatings researchers in industry as well as in academe have been exploring various modes [...]
- Published
- 2009
9. Intelligent polymeric surfaces through molecular self-assembly
- Author
-
Goel, Achin, Joshi, Ravi G., and Mannari, Vijay
- Subjects
Coatings industry -- Mechanical properties ,Metals, metalworking and machinery industries - Abstract
Abstract Recently, stimuli-responsive surfaces have gained considerable interest among coatings researchers in industry as well as in academe. To date, many switchable surfaces based on such external stimuli as temperature, [...]
- Published
- 2009
10. Rare Earth-Doped MoS2for Supercapacitor Application
- Author
-
Isacfranklin, M., Princy, L. Esther Maria, Rathinam, Yuvakkumar, Kungumadevi, L., Ravi, G., Al-Sehemi, Abdullah G., and Velauthapillai, Dhayalan
- Abstract
The low availability of fossil fuels, high expenditure, and serious environmental impacts are the key to sustainable clean and green energy development. Molybdenum-based electrode materials are identified as effective electrodes to improve energy storage devices’ performances. In this work, pure and different rare earth (neodymium and gadolinium) doped MoS2electrodes are successfully prepared by employing the hydrothermal method. Doping rare earth elements with metal sulfides would be beneficial for combining with functional groups due to the 4f vacant orbital. Macroscopic analysis exposed the morphological variations from sphere to sheet by the effect of doping. The sheet-like Gd-doped MoS2nanostructures exhibited the maximum 357 F/g@10 mV/s specific capacitance from CV and 231.38 F/g@1 A/g from GCD with a prolonged cycling life of 81.50% over 5000 cycles. EIS spectra revealed the lowest solution and charge transfer resistance for Gd-doped MoS2materials, which suggests the high conductivity of the material. The strategies and results outlined in this paper are expected to trigger the search for completely new rare earth-doped metal sulfides for efficient energy storage applications.
- Published
- 2022
- Full Text
- View/download PDF
11. Rare Earth-Doped MoS2 for Supercapacitor Application.
- Author
-
Isacfranklin, M., Princy, L. Esther Maria, Rathinam, Yuvakkumar, Kungumadevi, L., Ravi, G., Al-Sehemi, Abdullah G., and Velauthapillai, Dhayalan
- Published
- 2022
- Full Text
- View/download PDF
12. Fatigue Reliability Evaluation of Aged Railway Steel Bridges Based on Probabilistic Fracture Mechanics
- Author
-
Rajeeth, T. J. and Ravi, G.
- Abstract
The most significant mode of the transport system in India is Railways. In its vast network, Indian railways have over 1 lakh major bridges and most of them are steel bridges. Focusing on steel bridges, fatigue is often a major problem, and it is one of the main factors controlling its life span. The present work aims to determine the reliability index and probability of failure of aged simply supported plate girder and truss bridges after a crack is detected using the Linear Elastic Fracture Mechanics approach. Using the methodology, the Reliability index and the desired number of cycles are found. After fixing an accepted risk level, the results were used to develop an inspection strategy. This method provides a rational basis for computing the probability of failure or Reliability index for any steel bridges and this procedure can be further used to arrive at optimum inspection interval.
- Published
- 2022
- Full Text
- View/download PDF
13. Cardiovascular magnetic resonance in the evaluation of heart failure
- Author
-
Assomull, Ravi G., Pennell, Dudley J., and Prasad, Sanjay K.
- Subjects
Heart failure -- Evaluation ,Heart failure -- Diagnosis ,Magnetic resonance imaging -- Usage ,Health - Published
- 2007
14. Recent developments in non-invasive cardiology
- Author
-
Prasad, Sanjay K., Assomull, Ravi G., and Pennell, Dudley J.
- Subjects
Heart diseases -- Diagnosis ,Heart diseases -- Care and treatment ,Magnetic resonance imaging -- Usage ,Cardiology -- Research - Published
- 2004
15. Corrigendum to “High-performance perovskite solar cells using graphene quantum dot modified SnO2/ZnO photoelectrode” [Mater Today Energy 22 (2021) 100853]
- Author
-
Nagaraj, G., Mohammed, Mustafa K.A., Shekargoftar, Masoud, Sasikumar, P., Sakthivel, P., Ravi, G., Dehghanipour, M., Akin, Seckin, and Shalan, Ahmed Esmail
- Published
- 2024
- Full Text
- View/download PDF
16. Nanolatex technology 1: synthesis and characterization of nanosize acrylic latexes and comparison to their conventional size counterparts
- Author
-
Joshi, Ravi G., Jones, Frank N., Provder, Theodore, and Shen, Weidian
- Abstract
For this study, functional precoalescence (internally crosslinked) and postcoalescence (crosslinkable) conventional latexes were made using seeded semi-continuous emulsion polymerization. Nanosize polymer latexes with or without crosslinkable functional groups were made using a modified microemulsion copolymerization process. Films cast from conventional and nanosize latex were characterized using specific end use tests and fundamental properties using dynamic mechanical analysis, modulated differential scanning calorimetry, and atomic force microscopy. This study compares conventional and nanosize latex with respect to the effect of the type and level of crosslinking, particle size and distribution on latex film formation and morphology, and end use and fundamental properties. Nanosize latex films in general have superior gloss, solvent resistance, and adhesion but inferior water resistance. Stress–strain Young’s modulus showed an increase as a function of increasing crosslinker level in the nanosize latex films.
- Published
- 2021
- Full Text
- View/download PDF
17. RETRACTED ARTICLE: Real time link quality based route selection and transmission in industrial Manet for improved QoS
- Author
-
Sankar Ganesh, S. and Ravi, G.
- Abstract
The QoS (quality of service) of Manet is depending various factors but it is highly rely on quality of links between the routes. The ratio of link failure reduces the throughput performance which is directly affecting the QoS. The most industrial units provide various services which can be accessed through mobile adhoc network. This supports the industrial entities and users to access the services through various mobile devices. As the nodes of Manet moves in different speed at various directions, the frequency of link failure will be always higher. However, to support data transmission, number of routing protocols has been discussed earlier (REF-26), but suffer to achieve higher QoS performance. To improve the quality of route selection towards maximization of QoS, a novel probabilistic link availability based traffic free route selection algorithm is presented in this paper. The method uses the location information, mobility speed, direction of various nodes in the measurement of probability in link availability. Also, the value of traffic at each node, neighbors of each node, and the frequency of transmission in each hop to measure the QoS Support Measure. The method first identifies the list of routes according to the broadcast mechanism and learns the topological information and traffic details. Using the details learned, the method identifies the list of routes and probable feature routes. For each route identified, the method estimates QoS support measure to choose a traffic free route at any time. Finally a single route has been selected to achieve high performance transmission in Manet.
- Published
- 2021
- Full Text
- View/download PDF
18. Correction to: Dynamic modeling and control of five phase SVPWM inverter fed induction motor drive with intelligent speed controller
- Author
-
Raja, D. and Ravi, G.
- Abstract
In the original publication of the article, the acknowledgment section was missed. The acknowledgment should read as follows.
- Published
- 2024
- Full Text
- View/download PDF
19. Reaction Discovery Using Spectroscopic Insights from an Enzymatic C–H Amination Intermediate
- Author
-
Das, Anuvab, Gao, Shilong, Lal, Ravi G., Hicks, Madeline H., Oyala, Paul H., and Arnold, Frances H.
- Abstract
Engineered hemoproteins can selectively incorporate nitrogen from nitrene precursors like hydroxylamine, O-substituted hydroxylamines, and organic azides into organic molecules. Although iron-nitrenoids are often invoked as the reactive intermediates in these reactions, their innate reactivity and transient nature have made their characterization challenging. Here we characterize an iron-nitrosyl intermediate generated from NH2OH within a protoglobin active site that can undergo nitrogen-group transfer catalysis, using UV–vis, electron paramagnetic resonance (EPR) spectroscopy, and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) techniques. The mechanistic insights gained led to the discovery of aminating reagents─nitrite (NO2–), nitric oxide (NO), and nitroxyl (HNO)─that are new to both nature and synthetic chemistry. Based on the findings, we propose a catalytic cycle for C–H amination inspired by the nitrite reductase pathway. This study highlights the potential of engineered hemoproteins to access natural nitrogen sources for sustainable chemical synthesis and offers a new perspective on the use of biological nitrogen cycle intermediates in biocatalysis.
- Published
- 2024
- Full Text
- View/download PDF
20. Synthesis of surfactant assisted Cu2ZnSnS4(CZTS) photocatalysts for removal of dyes from wastewater
- Author
-
Keerthana, S.P., Yuvakkumar, R., Ravi, G., Bastina Celcia, J., Arun Metha, S., and Velauthapillai, Dhayalan
- Abstract
[Display omitted]
- Published
- 2024
- Full Text
- View/download PDF
21. A Review on Exploring Better Safety Prospects in Managing Cancer using Liposomal Combinations of Food Bioactive Compounds and Anticancer Drugs: Combisomes
- Author
-
Dubey, Akhilesh, Shriram, Ravi G., and El-Zahaby, Sally A.
- Abstract
Nowadays, cancer is one of the deadliest diseases affecting an annually enormous number of people. Around 9.6 million people had died from different cancer types in 2018. Chemotherapy is considered to be a mainline treatment, and systemic administration of a single anticancer agent is also considered a vital clinical debacle of chemotherapy in cancer management. The formulators have been focusing currently onto procuring maximum benefit with the lowest aftereffects and maximum safety and efficacy for the patients undergoing chemotherapy. This review offers a perspective on the future developments of encapsulating food bioactive compounds with anticancer agents in a multifunctional single nanoliposomal delivery system. In the last decade, the paradigm shift was seen in formulating drug delivery systems for cancer treatment. Currently, food bioactive compounds are being taken as a hot subject by researchers, especially for the treatment of cancer owing to both preventative and curative quality. This review collects the utilization of liposomes in the delivery of anticancer drugs by encapsulating with food bioactive compounds by the oral administration. The authors coined the name of this combination is “Combisomes” as a fourth generation liposomes. Authors opine that “Combisomes” can tackle cancer minimizing side effects encountered from the usual anticancer agents. “Combisomes” will purvey a safe platform for the delivery of food bioactive compounds and anticancer agents for managing cancer with better safety prospects.
- Published
- 2021
- Full Text
- View/download PDF
22. Nanolatex technology 2: blending polymer nanoparticles with conventional latexes for synergistic property improvement
- Author
-
Jones, Frank N., Joshi, Ravi G., Provder, Theodore, and Shen, Weidian
- Abstract
Results of our research on crosslinked latexes and polymer nanoparticles will be reported. Goals of this long-term program have been: comparing precoalescence and post-coalescence crosslinking; synthesizing polymer nanoparticle latexes (~ 20 to 25 nm) from a variety of acrylic monomers, including crosslinking and crosslinkable monomers; and blending nanoparticle latexes with compatible conventional (~ 120 to 130 nm) latexes and understanding their effects on film formation and on fundamental and empirical film properties. As we previously reported, blending conventional and nanolatexes in an 85/15 ratio (w/w of polymer solids) effects substantial changes of fundamental film properties. Best results included reducing minimum filming temperatures (MFT) while increasing Young’s moduli by factors of two to 17. Substantial improvements in empirical film properties such as gloss (up to 97 at 60°), hardness (increased by 2–5 pencils), block resistance, and adhesion to aluminum were also found. The previous report covered only a single blend ratio. Here we report studies of blends with ratios of conventional to nanoparticle latexes ranging from 92.5/7.5 to 30/70 (w/w). As before, the latexes and nanolatexes are BMA/BA copolymers with 0–4 wt.% of 1,3-butylene glycol dimethacrylate (precoalescence crosslinker) and 0–5 wt.% of diacetone acrylamide (for post-coalescence crosslinking with adipic dihydrazide). Films cast from these blends are subjected to everyday empirical coatings tests and are characterized using instrumental tests including dynamic mechanical analysis (DMA) and modulated differential scanning calorimetry (MDSC). Film formation and film morphology are studied using atomic force microscopy (AFM). The results confirm that blending nanoparticles at ratios up to 50/50 (w/w of polymer solids) can substantially improve certain properties of conventional latex films. For many properties, the optimum ratio is around 85/15 conventional/nano; a 92.5/7.5 ratio also affords substantial improvements. As coatings, the blends have near-zero VOC.
- Published
- 2021
- Full Text
- View/download PDF
23. Microstructure and mechanical properties of Inconel-625 slab component fabricated by wire arc additive manufacturing
- Author
-
Ravi, G., Murugan, N., and Arulmani, R.
- Abstract
Wire arc additive manufacturing is a promising reliable free-form fabrication technique suitable for producing large-scale components that feature a very low buy-to-fly ratio. This research work is aimed to fabricate a rectangular prototype Inconel-625 alloy slab using a robotic metal inert gas welding system. The microstructure and mechanical properties of as-deposited and solution-annealed (SA) alloys were investigated. It was found that the as-deposited alloy exhibited a columnar dendritic structure and the presence of intermetallic phases such as the Laves phase, NbC and carbides were observed in the gamma-nickel matrix. In SA deposit, the intermetallic phases were dissolved in the NiCr-matrix and the secondary carbides M23C6, M6C were also observed in the microstructure. It was found that the ultimate tensile strength and microhardness of the as-deposited alloy were higher than that of SA deposit.
- Published
- 2020
- Full Text
- View/download PDF
24. Crystal structure of human lysosomal acid lipase and its implications in cholesteryl ester storage disease[S]
- Author
-
Rajamohan, Francis, Reyes, Allan R., Tu, Meihua, Nedoma, Nicole L., Hoth, Lise R., Schwaid, Adam G., Kurumbail, Ravi G., Ward, Jessica, and Han, Seungil
- Abstract
Lysosomal acid lipase (LAL) is a serine hydrolase that hydrolyzes cholesteryl ester (CE) and TGs delivered to the lysosomes into free cholesterol and fatty acids. LAL deficiency due to mutations in the LAL gene (LIPA) results in accumulation of TGs and cholesterol esters in various tissues of the body leading to pathological conditions such as Wolman's disease and CE storage disease (CESD). Here, we present the first crystal structure of recombinant human LAL (HLAL) to 2.6 Å resolution in its closed form. The crystal structure was enabled by mutating three of the six potential glycosylation sites. The overall structure of HLAL closely resembles that of the evolutionarily related human gastric lipase (HGL). It consists of a core domain belonging to the classical α/β hydrolase-fold family with a classical catalytic triad (Ser-153, His-353, Asp-324), an oxyanion hole, and a “cap” domain, which regulates substrate entry to the catalytic site. Most significant structural differences between HLAL and HGL exist at the lid region. Deletion of the short helix, 238NLCFLLC244, at the lid region implied a possible role in regulating the highly hydrophobic substrate binding site from self-oligomerization during interfacial activation. We also performed molecular dynamic simulations of dog gastric lipase (lid-open form) and HLAL to gain insights and speculated a possible role of the human mutant, H274Y, leading to CESD.
- Published
- 2020
- Full Text
- View/download PDF
25. A stable link connectivity-based data communication through neighbour node using traffic-less path in MANET
- Author
-
Ganesh, S. Sankar and Ravi, G.
- Abstract
Mobile Ad-hoc Network (MANET) is a collection of wireless mobile devices communicating with each other. Mobile devices are taking responsibility of routing packets between each others' nodes without any infrastructure. Generally, all the network uses the hybrid routing protocols to handle the connectivity link flow in the environment. But the hybrid rules do not consider the routing-related problems such as node selection and link analysis. So, the design of Data Communication through Neighbour Stable Link Connectivity (DC-NSLC) routing algorithm is implemented for fast and efficient traffic-less routing in the network. These routing algorithms work under the three phases, analysis of neighbour node information, neighbour node link establishment and data communication using neighbour node predicted link. Each and every phase evaluates the node movement along with the traffic design. The performance of our proposed research methodology is analysed by using the Network Simulator (NS2).
- Published
- 2020
- Full Text
- View/download PDF
26. Structural Basis for Achieving GSK-3β Inhibition with High Potency, Selectivity, and Brain Exposure for Positron Emission Tomography Imaging and Drug Discovery
- Author
-
Bernard-Gauthier, Vadim, Mossine, Andrew V., Knight, Ashley, Patnaik, Debasis, Zhao, Wen-Ning, Cheng, Chialin, Krishnan, Hema S., Xuan, Lucius L., Chindavong, Peter S., Reis, Surya A., Chen, Jinshan Michael, Shao, Xia, Stauff, Jenelle, Arteaga, Janna, Sherman, Phillip, Salem, Nicolas, Bonsall, David, Amaral, Brenda, Varlow, Cassis, Wells, Lisa, Martarello, Laurent, Patel, Shil, Liang, Steven H., Kurumbail, Ravi G., Haggarty, Stephen J., Scott, Peter J. H., and Vasdev, Neil
- Abstract
Using structure-guided design, several cell based assays, and microdosed positron emission tomography (PET) imaging, we identified a series of highly potent, selective, and brain-penetrant oxazole-4-carboxamide-based inhibitors of glycogen synthase kinase-3 (GSK-3). An isotopologue of our first-generation lead, [3H]PF-367, demonstrates selective and specific target engagement in vitro, irrespective of the activation state. We discovered substantial ubiquitous GSK-3-specific radioligand binding in Tg2576 Alzheimer’s disease (AD), suggesting application for these compounds in AD diagnosis and identified [11C]OCM-44 as our lead GSK-3 radiotracer, with optimized brain uptake by PET imaging in nonhuman primates. GSK-3β-isozyme selectivity was assessed to reveal OCM-51, the most potent (IC50= 0.030 nM) and selective (>10-fold GSK-3β/GSK-3α) GSK-3β inhibitor known to date. Inhibition of CRMP2T514and tau phosphorylation, as well as favorable therapeutic window against WNT/β-catenin signaling activation, was observed in cells.
- Published
- 2019
- Full Text
- View/download PDF
27. Tetrabenazine Treatment Patterns and Outcomes for Chorea Associated with Huntington Disease: A Retrospective Chart Review
- Author
-
Claassen, Daniel O., Iyer, Ravi G., Shah-Manek, Bijal, DiBonaventura, Marco, Abler, Victor, and Sung, Victor W.
- Abstract
Huntington disease (HD) is a neurodegenerative disorder characterized by motor impairments (including chorea), along with behavioral, psychiatric, and cognitive symptoms. Tetrabenazine was the first US Food and Drug Administration (FDA)-approved treatment for chorea related to HD. To examine pharmacologic treatment patterns among patients using tetrabenazine, including reasons for treatment initiation, non-initiation, dose adjustments, and discontinuation, and to quantify the burden of chorea based on healthcare resource utilization. In this retrospective patient chart review, neurologists were recruited from the Medefield (http://www.medefield.com) opt-in panel, and selected ≤5 medical charts based on the criteria provided and abstracted data on demographics, disease history, healthcare resource use, and treatment patterns. 138 neurologists participated and 512 HD patient charts were reviewed. Among these patients, 26.4% did not initiate tetrabenazine. Most HD patients (66.5%) received a tetrabenazine dose ≤50 mg. The most common reasons for stopping upward titration were optimal chorea control (55.5%), intolerability of higher doses (31.2%), and reaching the maximum recommended dosage despite suboptimal chorea control (11.4%). Chorea severity and non-persistence to tetrabenazine were associated with increased emergency room visits, hospitalizations, and days hospitalized. Although tetrabenazine was the sole FDA-approved treatment for HD chorea until April 2017, more than one-quarter of respondents never initiated therapy. Tetrabenazine dosing was lower than predicted, and many patients experienced adverse symptoms of intolerability at high doses. New safer and more tolerable treatment options, such as deutetrabenazine, may improve treatment outcomes and reduce healthcare resource use.
- Published
- 2018
- Full Text
- View/download PDF
28. Discovery of 3-Cyano-N-(3-(1-isobutyrylpiperidin-4-yl)-1-methyl-4-(trifluoromethyl)-1H-pyrrolo[2,3-b]pyridin-5-yl)benzamide: A Potent, Selective, and Orally Bioavailable Retinoic Acid Receptor-Related Orphan Receptor C2 Inverse Agonist
- Author
-
Schnute, Mark E., Wennerstål, Mattias, Alley, Jennifer, Bengtsson, Martin, Blinn, James R., Bolten, Charles W., Braden, Timothy, Bonn, Tomas, Carlsson, Bo, Caspers, Nicole, Chen, Ming, Choi, Chulho, Collis, Leon P., Crouse, Kimberly, Färnegårdh, Mathias, Fennell, Kimberly F., Fish, Susan, Flick, Andrew C., Goos-Nilsson, Annika, Gullberg, Hjalmar, Harris, Peter K., Heasley, Steven E., Hegen, Martin, Hromockyj, Alexander E., Hu, Xiao, Husman, Bolette, Janosik, Tomasz, Jones, Peter, Kaila, Neelu, Kallin, Elisabet, Kauppi, Björn, Kiefer, James R., Knafels, John, Koehler, Konrad, Kruger, Lars, Kurumbail, Ravi G., Kyne, Robert E., Li, Wei, Löfstedt, Joakim, Long, Scott A., Menard, Carol A., Mente, Scot, Messing, Dean, Meyers, Marvin J., Napierata, Lee, Nöteberg, Daniel, Nuhant, Philippe, Pelc, Matthew J., Prinsen, Michael J., Rhönnstad, Patrik, Backström-Rydin, Eva, Sandberg, Johnny, Sandström, Maria, Shah, Falgun, Sjöberg, Maria, Sundell, Aron, Taylor, Alexandria P., Thorarensen, Atli, Trujillo, John I., Trzupek, John D., Unwalla, Ray, Vajdos, Felix F., Weinberg, Robin A., Wood, David C., Xing, Li, Zamaratski, Edouard, Zapf, Christoph W., Zhao, Yajuan, Wilhelmsson, Anna, and Berstein, Gabriel
- Abstract
The nuclear hormone receptor retinoic acid receptor-related orphan C2 (RORC2, also known as RORγt) is a promising target for the treatment of autoimmune diseases. A small molecule, inverse agonist of the receptor is anticipated to reduce production of IL-17, a key proinflammatory cytokine. Through a high-throughput screening approach, we identified a molecule displaying promising binding affinity for RORC2, inhibition of IL-17 production in Th17 cells, and selectivity against the related RORA and RORB receptor isoforms. Lead optimization to improve the potency and metabolic stability of this hit focused on two key design strategies, namely, iterative optimization driven by increasing lipophilic efficiency and structure-guided conformational restriction to achieve optimal ground state energetics and maximize receptor residence time. This approach successfully identified 3-cyano-N-(3-(1-isobutyrylpiperidin-4-yl)-1-methyl-4-(trifluoromethyl)-1H-pyrrolo[2,3-b]pyridin-5-yl)benzamide as a potent and selective RORC2 inverse agonist, demonstrating good metabolic stability, oral bioavailability, and the ability to reduce IL-17 levels and skin inflammation in a preclinical in vivo animal model upon oral administration.
- Published
- 2018
- Full Text
- View/download PDF
29. NREM Sleep and Antiepileptic Medications Modulate Epileptiform Activity by Altering Cortical Synchrony
- Author
-
Nayak, Chetan S., Mariyappa, N., Majumdar, Kaushik K., Ravi, G. S., Prasad, Pradeep D., Nagappa, Madhu, Kandavel, Thennarasu, Taly, Arun B., and Sinha, Sanjib
- Abstract
Introduction. The activating role of non–rapid eye movement (NREM) sleep on epileptic cortex and conversely, the seizure remission brought about by antiepileptic medications, has been attributed to their effects on neuronal synchrony. This study aims to understand the role of neural synchrony of NREM sleep in promoting interictal epileptiform discharges (IEDs) in patients with epilepsy (PWE) by assessing the peri-IED phase synchrony during awake and sleep states. It also studies the role played by antiepileptic drugs (AEDs) on EEG desynchronization in the above cohort. Methods. A total of 120 PWE divided into 3 groups (each n = 40; juvenile myoclonic epilepsy [JME], temporal lobe epilepsy [TLE]. and extratemporal lobe epilepsy [Ex-TLE]) were subjected to overnight polysomnography. Each patient group was subdivided into drug-naive and on treatment (Each n = 20). EEG phase synchronization analysis was performed to compare peri-IED phase synchronization indices (SI) during awake and sleep stages and between drug naïve and on treatment groups in 4 frequency bands, namely delta, theta, alpha, and beta. The mean ± SD of peri-IED SI among various subgroups was compared employing a multilevel mixed effects modeling approach. Results. Patients with JME had increased peri-IED cortical synchrony in N3 sleep stage, whereas patients with partial epilepsy had increased IED cortical synchrony in N1 sleep stage. On the other hand, peri-IED synchrony was lower during wake and REM sleep. We also found that peri-IED synchronization in patients with JME was higher in drug-naive patients compared with those on sodium valproate monotherapy in theta, alpha, and beta bands. Conclusion. The findings of this study suggest that sleep stages can alter cortical synchrony in patients with JME and focal epilepsy, with NREM IEDs being more synchronized and wake/REM IEDs being less synchronized. Furthermore, it also suggests that AEDs alleviate seizures in PWE by inhibiting cortical synchrony.
- Published
- 2018
- Full Text
- View/download PDF
30. Optimal reactive power dispatch considering multi-type FACTS devices using harmony search algorithms
- Author
-
Karthikaikannan, D. and Ravi, G.
- Abstract
ABSTRACTOptimal Reactive Power Dispatch (ORPD) plays an important role for the secure and reliable operation of power systems. The main purpose of ORPD is to find the settings of control variables such as voltage rating of generators, reactive power injection of VAr compensators and tap ratios of the tap setting transformers in order to minimize the total active power losses of the network while satisfying a given set of constraints. In this paper, Flexible AC Transmission System (FACTS) controllers such as Static Var Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC) and Thyristor Controlled Phase Shifting Transformer (TCPST) are considered in addition with the conventional ORPD control variables for additional active power loss minimization. The whole ORPD problem is considered as a non-linear multi-modal optimization problem. Harmony search algorithm is a recent meta-heuristic algorithm which mimics the musician’s improvization process. In this paper, two versions of harmony search algorithm, namely Basic Harmony Search Algorithm (HSA) and Improved Harmony Search Algorithm (IHSA) are applied to solve conventional ORPD, as well as ORPD considering FACTS devices. Studies on the proposed algorithm are carried out on IEEE 14 and 57 bus systems. Comparison of simulation results reveals the effectiveness of proposed algorithms over other well-established population-based optimization techniques.
- Published
- 2018
- Full Text
- View/download PDF
31. SmNiO3/SWCNT perovskite composite for hybrid supercapacitor
- Author
-
Isacfranklin, M., Yuvakkumar, R., Ravi, G., Thambidurai, M., Nguyen, Hung D., and Velauthapillai, Dhayalan
- Abstract
Modern world has an unparalleled focus on science and technology as an energy storage device as a promising alternative sources to tackle the growing energy crisis and play an important role in economic development. Thus, new approaches and novel promising electrode materials are trying to overcome high energy density without reducing supercapacitors power density and a long lifetime stability. Accordingly, rational flower like structural control of rare earth nickelate-based composite electrodes is also important but very challenging. The role of carbon composites such as single walled carbon nanotube (SWCNT) and multi walled carbon nanotube (MWCNT) with samarium nickelate (SmNiO3) is studied. Herein, the perovskite rare earth SmNiO3, SmNiO3/MWCNT and SmNiO3/SWCNT composites are prepared as potential electrode materials by solvothermal method and never reported before as electrode for supercapacitors. An asymmetric hybrid supercapacitor (SmNiO3/SWCNT//CNT) was fabricated and presented specific capacitance, energy and power density of 170.58 F/g, 53.30 Wh/kg and 749.88 W/kg at 1 A/g. The assembled asymmetric hybrid device exhibited 79.34 % of capacitance retention and 97.52 % of coulombic efficiency even after the continuous 20,000 long cycles. These superior electrochemical properties make the hybrid microflower rare earth nickelate as a good candidate for next generation electrodes in hybrid supercapacitors.
- Published
- 2023
- Full Text
- View/download PDF
32. Acyl Glucuronide Metabolites of 6-Chloro-5-[4-(1-hydroxycyclobutyl)phenyl]-1H-indole-3-carboxylic Acid (PF-06409577) and Related Indole-3-carboxylic Acid Derivatives are Direct Activators of Adenosine Monophosphate-Activated Protein Kinase (AMPK)
- Author
-
Ryder, Tim F., Calabrese, Matthew F., Walker, Gregory S., Cameron, Kimberly O., Reyes, Allan R., Borzilleri, Kris A., Delmore, Jake, Miller, Russell, Kurumbail, Ravi G., Ward, Jessica, Kung, Daniel W., Brown, Janice A., Edmonds, David J., Eng, Heather, Wolford, Angela C., and Kalgutkar, Amit S.
- Abstract
Studies on indole-3-carboxylic acid derivatives as direct activators of human adenosine monophosphate-activated protein kinase (AMPK) α1β1γ1 isoform have culminated in the identification of PF-06409577 (1), PF-06885249 (2), and PF-06679142 (3) as potential clinical candidates. Compounds 1–3are primarily cleared in animals and humans via glucuronidation. Herein, we describe the biosynthetic preparation, purification, and structural characterization of the glucuronide conjugates of 1–3. Spectral characterization of the purified glucuronides M1, M2, and M3 indicated that they were acyl glucuronide derivatives. In vitro pharmacological evaluation revealed that all three acyl glucuronides retained selective activation of β1-containing AMPK isoforms. Inhibition of de novo lipogenesis with representative parent carboxylic acids and their respective acyl glucuronide conjugates in human hepatocytes demonstrated their propensity to activate cellular AMPK. Cocrystallization of the AMPK α1β1γ1 isoform with 1–3and M1–M3 provided molecular insights into the structural basis for AMPK activation by the glucuronide conjugates.
- Published
- 2018
- Full Text
- View/download PDF
33. Facile synthesis of quantum sized Co3O4nanostructures and their magnetic properties
- Author
-
Anandhababu, G. and Ravi, G.
- Abstract
We examined the quantum sized Co3O4formation with hexagonal morphology of diameter about 20 nm. The photoluminescence study proved the surface defect-rich Co3O4nanostructures. The combined synergistic effect of quantum sized hexagonal nanoplates structures and surface defects are favorable for the enhanced magnetic properties in Co3O4nanostructures. The addition of surfactants and changing of microwave powers led to the paramagnetic behavior. Room temperature magnetic measurements of Ni-doped Co3O4exhibits weak ferromagnetic nature of Co3O4nanostructures. With practical, environmental friendly and solvent-free microwave strategy provides a brand new promising route for large-scale preparation of metal oxide for outstanding magnetic performance.
- Published
- 2018
- Full Text
- View/download PDF
34. Heightened Background Cortical Synchrony in Patients With Epilepsy: EEG Phase Synchrony Analysis During Awake and Sleep Stages Using Novel Ensemble Measure
- Author
-
Nayak, Chetan S., Mariyappa, N., Majumdar, Kaushik K., Prasad, Pradeep D., Ravi, G. S., Nagappa, M., Kandavel, Thennarasu, Taly, Arun B., and Sinha, Sanjib
- Abstract
Introduction. Excessive cortical synchrony within neural ensembles has been implicated as an important mechanism driving epileptiform activity. The current study measures and compares background electroencephalographic (EEG) phase synchronization in patients having various types of epilepsies and healthy controls during awake and sleep stages. Methods. A total of 120 patients with epilepsy (PWE) subdivided into 3 groups (juvenile myoclonic epilepsy [JME], temporal lobe epilepsy [TLE], and extra-temporal lobe epilepsy [Ex-TLE]; n = 40 in each group) and 40 healthy controls were subjected to overnight polysomnography. EEG phase synchronization (SI) between the 8 EEG channels was assessed for delta, theta, alpha, sigma, and high beta frequency bands using ensemble measure on 10-second representative time windows and compared between patients and controls and also between awake and sleep stages. Mean ± SD of SI was compared using 2-way analysis of variance followed by pairwise comparison (P≤ .05). Results. In both delta and theta bands, the SI was significantly higher in patients with JME, TLE, and Ex-TLE compared with controls, whereas in alpha, sigma, and high beta bands, SI was comparable between the groups. On comparison of SI between sleep stages, delta band: progressive increase in SI from wake ⇒ N1 ⇒ N2 ⇒ N3, whereas REM (rapid eye movement) was comparable to wake; theta band: decreased SI during N2 and increase during N3; alpha band: SI was highest in wake and lower in N1, N2, N3, and REM; and sigma and high beta bands: progressive increase in SI from wake ⇒ N1 ⇒ N2 ⇒ N3; however, sigma band showed lower SI during REM. Conclusion. This study found an increased background cortical synchronization in PWE compared with healthy controls in delta and theta bands during wake and sleep. This background hypersynchrony may be an important property of epileptogenic brain circuitry in PWE, which enables them to effortlessly generate a paroxysmal EEG depolarization shift.
- Published
- 2018
- Full Text
- View/download PDF
35. Ferrimagnetism in cobalt ferrite (CoFe2O4) nanoparticles
- Author
-
Rani, B. Jansi, Ravina, M., Saravanakumar, B., Ravi, G., Ganesh, V., Ravichandran, S., and Yuvakkumar, R.
- Abstract
Ferrimagnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized by employing co-precipitation method. Product physico-chemical and magnetic properties with respect to cetyl trimethylammonium bromide (CTAB), hexamethylenetetramine (HMT) and polyethylene glycol (PEG-400) surfactants were investigated. XRD pattern and Raman characteristic active modes revealed the cubic cobalt ferrite structure formation. SEM images explored spherical shaped product with different particle size. Identified strong PL emission peaks confirmed the product quality. IR metal oxygen vibration at 615 and 426 cm−1revealed tetrahedral and octahedral site of cobalt ferrite system. Product electrochemical behavior was found to be size dependent and high specific capacitance was observed using CTAB. Room temperature ferrimagnetic behavior was confirmed through VSM studies. High saturation value as 66 emu/g was found using PEG. Particles with larger crystallite and particle size exhibited improved magnetic behavior.
- Published
- 2018
- Full Text
- View/download PDF
36. Dielectric relaxation study of amides with alcohol mixtures by time domain reflectometry
- Author
-
Ravi, G., Undre, P.B., Ramachandran, K., and Samuvel, K.
- Abstract
Using Time Domain Reflectometry (TDR), dielectric relaxation studies have been carried out on binary mixtures of amides (N-methylacetamide, N,N-dimethylacetamide) with alcohol (1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol and 1-decanol) for various concentrations over the frequency range from 10 MHz to 10 GHz at 303 K. The Kirkwood correlation factor and excess dielectric constant properties were determined and discussed to yield information on the molecular interactions of the systems. The relaxation time is varies with the chain length of alcohols and substituted amides are observed. The Bruggeman plot shows a deviation from linearity. This deviation was attributed to some sort of molecular interaction which might place between the alcohols and substituted amides. The excess static permittivity and excess inverse relaxation time values vary from negative to positive for all the systems indicating the solute-solvent interaction to exist between alcohol and substituted amides for all the dynamics of the mixture.
- Published
- 2017
- Full Text
- View/download PDF
37. Retraction Note to: Real time link quality based route selection and transmission in industrial Manet for improved QoS
- Author
-
Ganesh, S. Sankar and Ravi, G.
- Published
- 2023
- Full Text
- View/download PDF
38. Cerebral and Coronary Vasculature in Disease Associations and Dissociations in the South Indian Population
- Author
-
Srinivasan, Krishnan, Ravikumar, Srinivasan, Chandra, Sadanandavalli Retnaswami, Ganapathy, Selva, and Ravi, G. S.
- Published
- 2017
- Full Text
- View/download PDF
39. Probing the energy conversion and storage process in two dimensional layered bismuthene-hexagonal boron nitride nanocomposite electrode and PVA-KOH-BaTiO3piezoelectrolyte nanogenerators
- Author
-
Maheshwaran, G., Prabhu, M. Ramesh, Ravi, G., Sankaranarayanan, K., and Sudhahar, S.
- Abstract
The design and fabrication of effective piezoelectric self charging hybrid supercapacitor that efficiently harvest, convert, and store energies in a sustainable and cost-effective way is a cutting edge in the fields of advanced research. However, the output power generated from self charging power devices is insufficient to drive the portable and smart electronic systems. Herein, we fabricated a novel Polyvinyl Alcohol - Potassium hydroxide - Barium Titanate (PVA-KOH-BTO) multifunctional piezoelectrolyte based nanogenerators that potentially convert the mechanical energy to electrical energy. The all-in-one self charging hybrid supercapacitor (SCHSC) was fabricated using two dimensional Bismuthene-hexagonal Boron Nitride nanocomposite (Biene-h-BN NC) as cathode, activated carbon (AC) as anode and the PVA-KOH-BTO as piezoelectrolyte, delivering the specific capacity of 280 C/g at 1 A/g. Moreover, the SCHSC provides the high energy density of 87.5 Wh/kg and the high power density of 11250 W/kg. Remarkably, the self charging performance of SCHSC was investigated by externally applying compressive forces, delivering the maximum self charging potential of 146 mV at the compressive force of 50 N. This research generates a new idea towards the understanding of self charging performance by piezoelectrochemical effect and can be utilized as a potential candidate for the fabrication of futuristic smart electronic devices.
- Published
- 2023
- Full Text
- View/download PDF
40. Systemic and Intracranial Outcomes With First-Line Nivolumab Plus Ipilimumab in Patients With Metastatic NSCLC and Baseline Brain Metastases From CheckMate 227 Part 1
- Author
-
Reck, Martin, Ciuleanu, Tudor-Eliade, Lee, Jong-Seok, Schenker, Michael, Zurawski, Bogdan, Kim, Sang-We, Mahave, Mauricio, Alexandru, Aurelia, Peters, Solange, Pluzanski, Adam, Caro, Reyes Bernabe, Linardou, Helena, Burgers, Jacobus A., Nishio, Makoto, Martinez-Marti, Alex, Azuma, Koichi, Axelrod, Rita, Paz-Ares, Luis G., Ramalingam, Suresh S., Borghaei, Hossein, O’Byrne, Kenneth J., Li, Li, Bushong, Judith, Gupta, Ravi G., Grootendorst, Diederik J., Eccles, Laura J., and Brahmer, Julie R.
- Abstract
In CheckMate 227 Part 1, nivolumab plus ipilimumab prolonged overall survival (OS) versus chemotherapy in patients with metastatic NSCLC, regardless of tumor programmed death-ligand 1 (PD-L1) expression. Here, we report post hoc exploratory systemic and intracranial efficacy outcomes and safety by baseline brain metastasis status at 5 years’ minimum follow-up.
- Published
- 2023
- Full Text
- View/download PDF
41. Optimal Location and Setting of FACTS Devices for Reactive Power Compensation Using Harmony Search Algorithm
- Author
-
Karthikaikannan, D. and Ravi, G.
- Abstract
Reactive Power Compensation (RPC) is an important issue in the operation and control of power system. In this paper, two FACTS controller like Static Var Compensator (SVC) and Thyristor Controlled Series Capacitor (TCSC) are considered for RPC. RPC is a multi-objective nonlinear optimization problem that minimizes the bus voltage deviation and real power loss. In this work, Harmony Search Algorithm (HSA) is used to determine the optimal location and setting of SVC and TCSC respectively. The efficacy of HSA is demonstrated on modified IEEE 30 bus power system for two operating conditions. A comparison of simulation results reveals the effectiveness of proposed algorithm over other well established population based optimization technique like Simple Genetic Algorithm (SGA),Particle Swarm Optimization (PSO) and Differential Evolution (DE).
- Published
- 2016
- Full Text
- View/download PDF
42. Samarium doped barium molybdate nanostructured candidate for supercapacitors
- Author
-
Rani, B. Jansi, Swathi, S., Yuvakkumar, R., Ravi, G., Rajalakshmi, R., Al-Sehemi, Abdullah G., and Velauthapillai, Dhayalan
- Abstract
Doping strategy with optimized particle size is an appealing way to manipulate the electrochemical energy storage mechanism of metal oxides for supercapacitor applications. Herein, we reported the optimized co-precipitation method to synthesize the pure and Sm doped BaMoO4nanostructures for energy storage application. More number of hydrophilic group present in the Sm doped candidate favors for easy adsorption of OH−ions to support for oxidation/reduction reaction. With abundant redox couple, optimized particle size, nano porous nature, and surface area (14.74 m2g−1), Sm doped BaMoO4electrode exhibited high 135 F/g capacitance at 1 A/g. Lowest 2.3 Ω Rctvalue was reported and evidenced for high conductivity of Sm doped electrode. Hence, this work provides a great insight toward the rare earth elements supported scheelite type molybdate nanostructures for energy storage and conversion applications.
- Published
- 2022
- Full Text
- View/download PDF
43. Mesoporous oxygen vacancy 3D-rhombohedral Ov-Mn2O3mixed with rGO@CNTs as cathode material for self-charging pouch-type hybrid supercapacitor applications
- Author
-
Karuppaiah, M., Sriram, B., Sakthivel, P., Asaithambi, S., Sidharth, D., Balaji, V., Wang, S.-F., Yuvakkumar, R., and Ravi, G.
- Abstract
The extrinsic integrated self-charging pouch-type hybrid supercapacitors (HSCs) are much more interesting and persuade advance research in worldwide. In HSC, the electrodes and electrolytes are playing a crucial role. Hence, the prepared cathode material's uniform morphology with mesoporous, presence of rich oxygen vacancy, high electrical/ionic conductivities, and addition of redox additives in electrolyte could significantly achieve high charge storage capacity and improved device performance. Initially, the Mn2O3shows a high specific capacity of 31.03 mAh/g at 6 mA/cm2in KOH plus redox additives electrolyte compared to pristine KOH electrolyte (21.75 mAh/g). Further, the optimized Ov-Mn2O3@rGO/CNTs composite sample exhibits superior battery-type behavior. The composite sample delivers a maximum specific capacity of 82.91 mAh/g at 6 mA/cm2, superior rate capability of 49.83%, and long cycle retention of 97.27% after 5000 cycles. Then, the pouch-type HSCs were fabricated using rich Ov-Mn2O3@rGO/CNTs/Ni as battery-type cathode and AC/Ni as a capacitive-type anode. The device delivered a maximum specific energy density of 44.97 Wh/kg at a power density of 847 W/kg with superior capacity retention of 85.41% after 13,000 cycles. Finally, the fabricated HSC devices have been integrated with thermoelectric generator and solar cell to prove for future sustainable self-charging applications.
- Published
- 2022
- Full Text
- View/download PDF
44. Photoelectrochemical study of MoO3assorted morphology films formed by thermal evaporation
- Author
-
Senthilkumar, R., Anandhababu, G., Mahalingam, T., and Ravi, G.
- Abstract
Molybdenum oxide nanostructured thin films were grown on fluorine doped tin oxide (FTO), indium doped tin oxide (ITO) and ordinary glass substrates by thermal evaporation process without vacuum and catalysts using molybdenum trioxide (MoO3) powder as a source material and oxygen as a carrier gas. Various morphologies including nanobelts, disks and hexagonal rod-like nanostructures were obtained by changing the source and substrate temperatures during the growth of MoO3thin films. Structural parameters, morphology, composition and surface features of the films were characterized by XRD, SEM, EDAX, XPS, AFM and Raman spectroscopy. The films were orthorhombic in structure with preferred orientation along (0 1 0) plane. Morphology analysis reveals randomly aligned nanobelts with 40 nm in thickness and a width of 800 nm and 3–12 mm in length. The disks have 1.5 μm diameters, 1 μm thickness and hexagonal rod-like nanostructures with a length, breath and width of 2 μm, 1 μm and 100 nm are formed. The samples were investigated under dark and photocurrent conditions in H2SO4aqueous solution as a function of applied potential. The photocurrent density of samples prepared on ITO and FTO substrate samples were compared and the results are discussed.
- Published
- 2016
- Full Text
- View/download PDF
45. Degradation of Methylene Blue and Rhodamine B Using a New Visible Light-Responsive Photocatalyst, KSb2PO8−xNy
- Author
-
Ravi, G., Sudhakar Reddy, CH., Sreenu, K., Guje, Ravinder, Velchuri, Radha, and Vithal, M.
- Abstract
Potassium phosphatoantimonates, KSb2PO8(KSbPO) and KSb2PO8−xNy(KSbPON), are prepared by solid-state method. Urea is employed as a source of nitrogen for N-doping. Structural, morphological and optical properties of both KSbPO and KSbPON are characterized by powder X-ray diffraction (PXRD), scanning electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy and UV–visible diffuse reflectance spectroscopy. Both samples are found to crystallize in a monoclinic lattice with Cc space group. The d-lines of KSbPO and KSbPON are refined by least square fitting the PXRD data, using POWD software to obtain their unit cell parameters. The bandgap energy (Eg) of both pristine and N-doped KSbPO is found from their Kubelka–Munk plot. The KSbPON/visible photocatalytic degradation of methylene blue and rhodamine B has been investigated in aqueous heterogeneous suspension. The generation of ·OH in the presence of KSbPON during the photoreaction is verified by a fluorescence technique using terephthalic acid (TA) as a probe.
- Published
- 2016
- Full Text
- View/download PDF
46. Pragmatics of language in the broad autism phenotype
- Author
-
Meera, Shoba S., Shankar, Ravi G., Girimaji, Satish C., Seshadri, Shekhar P., Philip, Mariamma, and Shivashankar, Nagarajarao
- Abstract
Researchers have reported a higher prevalence for parents of children with autism spectrum disorders (ASD) to have subtle characteristics of ASD, known as the broad autism phenotype (BAP). Deficits in the pragmatics of language are a hallmark feature of ASD and thus become a natural candidate for assessment in the BAP. This study focused on pragmatic impairments in the parents of children with ASD from India, a group that is ethnically and socio-culturally different from that of the west. Pragmatics was assessed using the broad autism phenotype questionnaire along with directly observing, recording, and profiling social communication, which is referred as ‘Observations of Social Communication’, in parents of children with ASD (PASD), down syndrome, and parents of typically developing children. The PASD group was found to be significantly different from that of the other two groups demonstrating subtle pragmatic language deficits in the BAP thus supporting similar trends in BAP across cultures.
- Published
- 2015
- Full Text
- View/download PDF
47. Metathesis synthesis, characterization, spectral and photoactivity studies of Ln2/3MoO4(Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y)
- Author
-
Velchuri, Radha, Palla, Suresh, Ravi, G., Veldurthi, Naveen Kumar, Reddy, J.R., and Vithal, M.
- Abstract
Rare earth ortho-oxomolybdates of composition Ln2/3MoO4(Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y) were prepared by metathesis reaction. All these materials were characterized by powder X-ray diffraction, Fourier transform-infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectra. The Rietveld analysis of all the samples was carried out to obtain the unit cell parameters and reliability factors. All the materials were crystallized in tetragonal lattice with I41/aspace group. The infrared spectra of all the samples were characterized by bands due to MoO42–units. The bandgap energies of all the samples were obtained from UV-Vis DRS spectra. The luminescence spectra of Ln2/3MoO4(Ln=Pr, Eu and Dy) showed characteristic transitions of the rare earth ions. The visible light photocatalytic activity of all the samples was studied against degradation of methylene blue.
- Published
- 2015
- Full Text
- View/download PDF
48. Enhanced Photocatalytic Activity of N-doped Li2VPO6Under Visible Light Irradiation
- Author
-
Palla, Suresh, Guje, Ravinder, Ravi, G., Velchuri, Radha, and Vithal, M.
- Abstract
Substitutional doping of framework heteroatoms in photocatalysts is one of the approaches for harvesting visible light. The present work aims to utilize the visible light for photocatalytic degradation of organic pollutant by tailoring the bandgap energy of Li2VPO6through nitrogen doping. Li2VPO6and N-doped Li2VPO6are prepared by solid-state method. These materials were characterized by powder X-ray diffraction, energy-dispersive spectra, Raman spectra, UV–Vis diffuse reflectance spectra (UV–Vis DRS), and 31P MAS NMR. The absorption edge of N-doped Li2VPO6is shifted to longer wavelength region considerably. The photocatalytic activity was tested against the degradation of methylene blue. The higher visible light photocatalytic activity of N-doped Li2VPO6compared to pristine Li2VPO6was discussed. The catalysts are stable even after fourth cycle of photodegradation.
- Published
- 2015
- Full Text
- View/download PDF
49. Performance analysis of an energy aware zone routing protocol using span
- Author
-
Ravi, G. and Kashwan, K.R.
- Abstract
AbstractA group of mobile wireless nodes that form a network is called Mobile Ad hoc NETworks (MANET); such a network has no infrastructure and a de-centralized administration. Hence, these wireless nodes greatly depend on their battery power supplies. This power has a much greater influence on the overall lifetime of the network. Extending the lifetime of mobile node has become a major challenge. This paper proposes a Span Adaptive Zone Routing Protocol (SAZRP) to obtain the maximum energy efficiency in MANET nodes using the approach of combining Span and Remote Activated Switch (RAS), with well-known Zone Routing Protocol (ZRP). Furthermore, to promote energy savings through RASs, this hardware is equipped with all of the nodes that are necessary to wake up a sleeping node at any instant of the beacon interval. The simulation results indicate that the SAZRP protocol provides a significant savings in energy consumption, a substantial increase in the packet delivery ratio, and a better throughput compared to the ZRP protocol.
- Published
- 2015
- Full Text
- View/download PDF
50. Preparation, Characterization, Photocatalytic Activity and Conductivity Studies of YLnTi2O7(Ln = Nd, Sm, Eu and Gd)
- Author
-
Devi, V. Rama, Ravi, G., Velchuri, Radha, Muniratnam, N. R., Prasad, G., and Vithal, M.
- Abstract
Bulk and nano sized oxides belonging to pyrochlore family of composition YLnTi2O7(Ln = Nd, Sm, Eu and Gd) have been prepared by sol-gel method. The as-prepared gel ‘precursor’ was sintered at different temperatures in the range 675°-900°C. All the materials were characterized by TGA-DTA, powder XRD, Raman, EDS, XPS and UV-Visible diffuse reflectance spectra. The crystallization of all the materials got started around 700°C. All these oxides were crystallized in ordered pyrochlore lattice with Fd3m space group. The average crystallite size calculated from the FWHM of intense XRD line was in the range 25-50 nm. The vibrational modes observed from Raman spectroscopy also support ordered pyrochlore structure for these oxides. The photocatalytic activities of all the nano powders were evaluated by photodegradation of methylene blue under visible light irradiation. The DC conductivity of all these materials was carried out in the temperature range 180°-560°C and discussed.
- Published
- 2013
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.