93 results on '"K. Shyam Prasad"'
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2. Microwave assisted Biginelli cyclocon densation for the synthesis of dihydropyrimidinones catalysed by H2SO4Clay NPs and their applications
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B.S. Surendra, K. Shyam Prasad, T R Shashi Shekhar, A. A Jahagirdar, S C Prashantha, N. Raghavendra, K. Gurushantha, N. Basavaraju, and K. Rudresha
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Microwave irradiation ,Pyrimidones synthesis ,Acid modified clay ,Chemistry ,QD1-999 - Abstract
The Acid Modification of Bentonite clay (AMC) process was firstly reported and has been developed in one pot by ionic exchange of inorganic interlayer clay combined with different concentrations of acid (H2SO4) under Microwave irradiation. The maximum basal spacing of 28 Å was found in 2 M AMC clay confirmed PXRD analysis. EDAX micrographs of raw and AMCs showed the percentage of elemental analysis (H% = 38.21 for 2 M). Further, it was successfully applied in the Biginelli reaction of Dihydropyrimidinones (DHPMs) synthesis by cyclocon densation reaction under microwave irradiation and structurally confirmed by spectral techniques such as HNMR, C13NMR, FT-IR, Mass and UV-Visible absorption spectra. The yields of DHPMs are 88%, 90%, 92% and 92.6% for EMDHPM, EMNDHPM, EMMDHPM and EMHMDHPM respectively. The antimicrobial activity of synthesized dihydropyrimidinones was examined using Gram-positive (Staphylococcus aureus) and Gram-negative (E. coli) bacterial species showed efficiently inhibited the bacterial growth activities at 4 mg/mL concentration. The results confirmed that the newly prepared DHPMs compounds act as efficient antimicrobial agent and synthesized AMC material as potential catalyst.
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- 2021
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3. Effective synthesis of novel O-acetylated compounds over ZrO2-Al2O3 solid acid
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N. Thimmaraju, S.Z. Mohamed Shamshuddin, S.R. Pratap, and K. Shyam Prasad
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Chemistry ,QD1-999 - Abstract
The solid acids such as ZrO2, Al2O3 and ZrO2-Al2O3 containing different ZrO2 loadings (10–80 mol%) were prepared by solution combustion method (SCM) and characterized for their total surface acidity by NH3-TPD/n-butylamine back titration method and crystallinity by powder X-ray diffraction (PXRD) technique. These solid acids were evaluated for their catalytic activity in the synthesis of novel O-acetylated products from substituted phenols, pyridine alcohols and aryl alcohols with acetic anhydride (AA) as an acetylating agent. The reaction conditions were optimized by varying the catalyst, molar ratio of the reactants, reaction temperature and amount of the catalyst. All the solid acids used in this study exhibited good catalytic activity in the reaction. In particular, ZrO2-Al2O3 containing 80 mol% of ZrO2 was found to be highly active in the acetylation reaction with high yield of acetylated products. Triangular correlation between the surface acidity, crystallinity and catalytic activity of solid acids was observed. These solid acids were found to be reactivable and reusable. Keywords: ZrO2-Al2O3, Solid acid, Solution combustion, Novel acetylated compounds, O-acetylation
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- 2019
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4. Influence of sintering temperature on the electrical and thermal properties of bulk samples of Pr2/3Sr1/3MnO3-δ
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Bhatt, Ramesh Chandra, Daivajna, Mamatha D., Rao, Ashok, K, Shyam Prasad, Thomas, Riya, Nagaraja, B.S., Awana, V.P.S., Lin, C.F., Ramachandran, B., and Kuo, Y.K.
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- 2018
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5. Supplementation of green coffee bean extract in healthy overweight subjects increases lean mass/fat mass ratio: A randomized, double-blind clinical study
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HV Sudeep and K Shyam Prasad
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Medicine (General) ,R5-920 - Abstract
Objective: In this study, we have demonstrated that supplementation of a complex of chlorogenic acid isomers (CGA-7 TM ) could significantly mitigate the risk of obesity in healthy overweight subjects. Method: In a double-blind, placebo-controlled clinical study, healthy overweight (body mass index ⩾ 25 to
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- 2021
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6. Synthesis and characterization of CuO nanoparticle: Its electrochemical paracetamol sensor activity and substituted-2-aminothiophene synthesis applications
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DM, Mamatha, primary, TH, Suresha Kumara, additional, KN, Harish, additional, T, Shamala, additional, M, Dinamani, additional, K., Shyam Prasad, additional, and BS, Surendra, additional
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- 2023
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7. Hydroalcoholic extract from Lepidium meyenii (Black Maca) root exerts wound healing activity in Streptozotocin-induced diabetic rats
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B.V.B., Bramara, H.S., Vasavi, H.V., Sudeep, and K., Shyam Prasad
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- 2017
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8. Chlorogenic acid complex (CGA7), standardized extract from green coffee beans exerts anticancer effects against cultured human colon cancer HCT-116 cells
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K. Gouthamchandra, H.V. Sudeep, B.J. Venkatesh, and K. Shyam Prasad
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Apoptosis ,Chlorogenic acid complex ,PARP-1 ,Green coffee beans ,DNA fragmentation ,Nutrition. Foods and food supply ,TX341-641 - Abstract
Coffee is commonly consumed beverage in the world and it has been suggested to have beneficial effect. Chlorogenic acids (CGAs) are main ingredient of coffee beans which has been extensively used in nutraceuticals and medicine. Recently, various therapeutic effects of chlorogenic acids have been investigated. However, there are limited studies to investigate its anticancer properties. In the present study, we have used chlorogenic acid complex (CGA7) a decaffeinated water soluble green coffee bean extract to evaluate its cytotoxic effect on human and mouse cancer cell lines by using different approaches. From our results we found CGA7 treatment induces cell death in a dose and time dependent manner in different cancer cell lines. Further, CGA7 induced apoptosis was characterized by DNA fragmentation, PARP-1 cleavage, caspase-9 activation, and down regulation of Bcl-2, an anti-apoptotic protein and up regulation of pro-apoptotic protein BAX. Overall findings indicated that CGA7 complex a potent anticancer molecule found in green coffee beans could be a safe bioactive ingredient for prevention of cancer.
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- 2017
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9. Highly efficient conversion of glycerol and t-butanol to biofuel additives over AlPO solid acid catalyst under microwave irradiation technique: kinetic study
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K. Shyam Prasad and S. Z. Mohamed Shamshuddin
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- 2022
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10. Enhancement of low-temperature thermoelectric performance via Pb doping in Cu3SbSe4
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Anand Pal, K. Shyam Prasad, K. Gurukrishna, Suraj Mangavati, P. Poornesh, Ashok Rao, Yin-Chun Chung, and Y.K. Kuo
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General Materials Science ,General Chemistry ,Condensed Matter Physics - Published
- 2023
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11. sj-pdf-1-smo-10.1177_20503121211002590 – Supplemental material for Supplementation of green coffee bean extract in healthy overweight subjects increases lean mass/fat mass ratio: A randomized, double-blind clinical study
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HV Sudeep and K Shyam Prasad
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FOS: Veterinary sciences ,111199 Nutrition and Dietetics not elsewhere classified ,Cardiology ,170199 Psychology not elsewhere classified ,111799 Public Health and Health Services not elsewhere classified ,110604 Sports Medicine ,FOS: Health sciences ,110306 Endocrinology ,110308 Geriatrics and Gerontology ,111099 Nursing not elsewhere classified ,111708 Health and Community Services ,160807 Sociological Methodology and Research Methods ,111702 Aged Health Care ,111403 Paediatrics ,110904 Neurology and Neuromuscular Diseases ,110203 Respiratory Diseases ,110315 Otorhinolaryngology ,70706 Veterinary Medicine ,FOS: Clinical medicine ,fungi ,110319 Psychiatry (incl. Psychotherapy) ,FOS: Sociology ,FOS: Psychology ,110599 Dentistry not elsewhere classified ,110323 Surgery ,110305 Emergency Medicine ,111599 Pharmacology and Pharmaceutical Sciences not elsewhere classified ,111299 Oncology and Carcinogenesis not elsewhere classified ,110314 Orthopaedics - Abstract
Supplemental material, sj-pdf-1-smo-10.1177_20503121211002590 for Supplementation of green coffee bean extract in healthy overweight subjects increases lean mass/fat mass ratio: A randomized, double-blind clinical study by HV Sudeep and K Shyam Prasad in SAGE Open Medicine
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- 2021
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12. Effective synthesis of novel O-acetylated compounds over ZrO2-Al2O3 solid acid
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S. Z. Mohamed Shamshuddin, N. Thimmaraju, K. Shyam Prasad, and S. R. Pratap
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Solid acid ,O-acetylation ,Chemistry(all) ,General Chemical Engineering ,Aryl ,Solution combustion ,ZrO2-Al2O3 ,General Chemistry ,Catalysis ,lcsh:Chemistry ,chemistry.chemical_compound ,Crystallinity ,Acetic anhydride ,chemistry ,lcsh:QD1-999 ,Yield (chemistry) ,Pyridine ,Chemical Engineering(all) ,Organic chemistry ,Novel acetylated compounds ,Phenols ,Powder diffraction - Abstract
The solid acids such as ZrO2, Al2O3 and ZrO2-Al2O3 containing different ZrO2 loadings (10–80 mol%) were prepared by solution combustion method (SCM) and characterized for their total surface acidity by NH3-TPD/n-butylamine back titration method and crystallinity by powder X-ray diffraction (PXRD) technique. These solid acids were evaluated for their catalytic activity in the synthesis of novel O-acetylated products from substituted phenols, pyridine alcohols and aryl alcohols with acetic anhydride (AA) as an acetylating agent. The reaction conditions were optimized by varying the catalyst, molar ratio of the reactants, reaction temperature and amount of the catalyst. All the solid acids used in this study exhibited good catalytic activity in the reaction. In particular, ZrO2-Al2O3 containing 80 mol% of ZrO2 was found to be highly active in the acetylation reaction with high yield of acetylated products. Triangular correlation between the surface acidity, crystallinity and catalytic activity of solid acids was observed. These solid acids were found to be reactivable and reusable. Keywords: ZrO2-Al2O3, Solid acid, Solution combustion, Novel acetylated compounds, O-acetylation
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- 2019
13. Enhancement in the thermoelectric properties of Cu3SbSe4 by Sn doping
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K. Shyam Prasad and Ashok Rao
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010302 applied physics ,Materials science ,Doping ,Analytical chemistry ,Conductivity ,Condensed Matter Physics ,Thermal conduction ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Tetragonal crystal system ,Electrical resistivity and conductivity ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,Charge carrier ,Electrical and Electronic Engineering - Abstract
The solid-state reaction technique was employed to fabricate Sn doped Cu3SbSe4 samples. The effect of doping on structural and thermoelectric properties of Cu3SbSe4 samples is represented in the present communication. The powder X-ray diffraction pattern of all the samples show that they have tetragonal structure (space group $$I\bar{4}2m$$ ). It is observed that doping Sn at Sb site acts as acceptor dopant which enhances hole concentration. The temperature dependent electrical resistivity (ρ(T)) is observed to decrease with increase in Sn concentration up to x = 0.03, thereafter ρ(T) increases with the increase in x concentration. To explore the conduction mechanism, we have employed small poloron hopping (SPH) model to the ρ(T) data and the results indicate that SPH is operative in the high temperature regime for all samples. The data of Seebeck coefficient (S(T)) confirms that holes are the majority charge carriers for pristine as well as doped samples. The analysis of S(T) data reveals that all the samples have a narrow band gap. The contribution from electron thermal conductivity is found to be less than 1%, thus the total conductivity is mainly because of phonon thermal conductivity. The highest value of dimensionless figure of merit (ZT = 0.127) was achieved at 374 K for the sample Cu3Sb0.99Sn0.01Se3 which is slightly higher than that of the pristine sample (ZT = 0.115). The highest value of compatibility factor (0.98 V−1) was observed for the sample Cu3Sb0.98Sn0.02Se3 at 374 K.
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- 2019
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14. Standardized Saw Palmetto Extract Directly and Indirectly Affects Testosterone Biosynthesis and Spermatogenesis
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Jeong Moon Yun, Minhee Lee, Jeongmin Lee, Sangwon Eun, Ok-Kyung Kim, K Shyam Prasad, and Dakyung Kim
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0301 basic medicine ,Male ,medicine.medical_specialty ,Medicine (miscellaneous) ,Rats, Sprague-Dawley ,03 medical and health sciences ,0302 clinical medicine ,Serenoa ,Internal medicine ,Saw palmetto extract ,medicine ,Animals ,Testosterone ,Spermatogenesis ,030109 nutrition & dietetics ,Nutrition and Dietetics ,Chemistry ,Plant Extracts ,food and beverages ,Testosterone (patch) ,medicine.disease ,Rats ,Endocrinology ,030220 oncology & carcinogenesis ,Testosterone biosynthesis ,andropause - Abstract
We investigated whether a standardized saw palmetto extract (SP, mixture of supercritical extract and ethanol extract at a ratio of 9.5 to 0.5) can relieve the symptoms of andropause, including metabolic syndrome, and decreases in muscle endurance and spermatogenesis, in old rats. Twenty-four-week-old male Sprague Dawley rats received oral supplementation of SP at 40, 80, and 160 mg/kg body weight (bw) for 4 weeks. We found that SP supplementation reduced body weight gain by decreasing visceral and epididymal fat weights and the levels of serum triglycerides, total cholesterol, and low-density lipoprotein/very low-density lipoprotein cholesterol. In addition, SP supplementation increased muscle endurance, sperm counts, and testosterone biosynthesis through hormonal regulation. In Leydig cells under hydrogen peroxide-induced oxidative stress, SP treatment directly induced testosterone biosynthesis by activating the mRNA expression of the genes encoding 17,20-desmolase and 3
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- 2021
15. Modeling of High-Speed finish milling Process using Soft Computing.
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Surekha Benguluri, Pandu Ranga Vundavilli, M. B. Parappagoudar, and K. Shyam Prasad
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- 2010
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16. Microwave synthesis of fuel additive over modified amorphous aluminophosphate: Kinetics
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K Shyam Prasad, S Z Mohamed Shamshuddin, and S R Pratap
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General Chemistry - Published
- 2022
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17. Spark plasma sintering technique: an alternative method to enhance ZT values of Sb doped Cu2SnSe3
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Chia Chi Chang, Ruchi Bhardwaj, Ashok Rao, Y. K. Kuo, K. Shyam Prasad, and Kishor Kumar Johri
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010302 applied physics ,Materials science ,Condensed matter physics ,Spark plasma sintering ,02 engineering and technology ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Thermal conduction ,01 natural sciences ,Variable-range hopping ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Thermal conductivity ,Electrical resistivity and conductivity ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
Sb doped Cu2Sn1−xSbxSe3 (0 ≤ x ≤ 0.04) compounds have been fabricated by spark plasma sintering technique for the investigation of their thermoelelctric properties in the temperature range 10–400 K. The conduction mechanism of electrical resistivity reveals that small polaron hopping model is valid in the high-temperature regime and variable range hopping model in low-temperature regime. The positive values of Seebeck coefficient (S) for Cu2Sn1−xSbxSe3 (0 ≤ x ≤ 0.04) samples in the entire temperature range indicates that the majority charge carriers are holes. The electronic thermal conductivity (κe) was estimated by Wiedmann-Franz law and found that the contribution of κe to the total κ is
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- 2018
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18. Correlation between structural and transport properties of electron beam irradiated PrMnO3 compounds
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P. Poornesh, Vikash Chandra Petwal, Ashok Rao, Benedict Christopher, Ganesh Sanjeev, K. Shyam Prasad, Jishnu Dwivedi, Vijay Pal Verma, Gunadhor S. Okram, and B.S. Nagaraja
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010302 applied physics ,Materials science ,Condensed matter physics ,Rietveld refinement ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Polaron ,01 natural sciences ,Condensed Matter::Materials Science ,Paramagnetism ,Ferromagnetism ,Electrical resistivity and conductivity ,Seebeck coefficient ,0103 physical sciences ,Materials Chemistry ,Condensed Matter::Strongly Correlated Electrons ,Charge carrier ,Orthorhombic crystal system ,0210 nano-technology - Abstract
The structural, electrical, magnetic, and thermal properties of electron beam (EB) irradiated PrMnO3 manganites were investigated in the present communication. X-ray diffraction data reveals that all samples are single phased with orthorhombic distorted structure (Pbnm). Furthermore, the diffracted data are analyzed in detail using Rietveld refinement technique. It is observed that the EB dosage feebly disturbs the MnO6 octahedra. The electrical resistivity of all the samples exhibits semiconducting behavior. Small polaron hopping model is conveniently employed to investigate the semiconducting nature of the pristine as well as EB irradiated samples. The Seebeck coefficient (S) of the pristine as well as the irradiated samples exhibit large positive values at lower temperatures, signifying holes as the dominant charge carriers. The analysis of Seebeck coefficient data confirms that the small polaron hopping mechanism assists the thermoelectric transport property in the high temperature region. The magnetic measurements confirm the existence of paramagnetic (PM) to ferromagnetic (FM) behavior for the pristine and irradiated samples. In the lower temperature regime, coexistence of FM clusters and AFM matrix is dominating. Thus, the complex magnetic behavior of the compound has been explained in terms of rearrangement of antiferromagnetically coupled ionic moments.
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- 2018
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19. Enhanced thermoelectric performance of Pb doped Cu 2 SnSe 3 synthesized employing spark plasma sintering
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Ajay Dhar, Kriti Tyagi, Sivaiah Bathula, Bhasker Gahtori, K. Shyam Prasad, Nagendra S. Chauhan, and Ashok Rao
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010302 applied physics ,Materials science ,Doping ,Analytical chemistry ,Spark plasma sintering ,02 engineering and technology ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Thermoelectric materials ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Thermal conductivity ,Electrical resistivity and conductivity ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
We report an enhancement in the thermoelectric performance of Cu2SnSe3 alloy on Pb doping, owing to a sharp increase in its power factor. The powder XRD pattern of all samples of Cu2Sn1−xPbxSe3 (0≤x≤0.03), prepared using solid state reaction, exhibited a cubic structure with a space group of F43m. The results show that temperature dependent electrical resistivity, ρ(T) increases with increasing temperature thereby demonstrating that the samples display heavily doped semiconducting nature, which could be satisfactorily described by small polaron hopping model in the whole temperature range of measurement for all the samples. Both the resistivity and the Seebeck coefficient are reduced with 2 vol% Pb doping. The thermal conductivity of all the samples reduces with increasing temperature. Despite a decrease in Seebeck coefficient the power factor shows an increase on Pb doping, owing to a sharp surge in the electrical conductivity which results in an enhanced ZTmax ~0.64 at 700 K for an optimized composition of Cu2Sn0.98Pb0.02Se3, which is nearly twice the value of the corresponding undoped counterpart.
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- 2017
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20. Bioavailability-enhanced Resveramax™ modulates quorum sensing and inhibits biofilm formation in Pseudomonas aeruginosa PAO1
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H.S. Vasavi, H B Lingaraju, K. Shyam Prasad, and H V Sudeep
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Models, Molecular ,0301 basic medicine ,030106 microbiology ,Molecular Conformation ,Biological Availability ,Swarming motility ,Biosensing Techniques ,Microbial Sensitivity Tests ,Resveratrol ,medicine.disease_cause ,Microbiology ,Virulence factor ,03 medical and health sciences ,chemistry.chemical_compound ,Pyocyanin ,Bacterial Proteins ,Stilbenes ,medicine ,Pseudomonas Infections ,biology ,Pseudomonas aeruginosa ,Biofilm ,Quorum Sensing ,Drug Synergism ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Anti-Bacterial Agents ,Quorum sensing ,030104 developmental biology ,Infectious Diseases ,chemistry ,Biofilms ,Trans-Activators ,Chromobacterium violaceum ,Protein Binding - Abstract
Quorum sensing (QS), a cell-to-cell communication mechanism present in many bacterial species plays a key role in regulating the virulence factor and biofilm formation in many pathogens, which causes severe public health risk. Therefore, interfering with QS mechanism offers an attractive strategy to combat bacterial infections. In the present study, anti-QS activity of a novel resveratrol formulation, Resveramax™, was detected using Chromobacterium violaceum biosensor bioassay and the effect of Resveramax on QS-regulated phenotypes in Pseudomonas aeruginosa PAO1 was assessed by standard protocols. Molecular docking analysis of resveratrol, the major active constituent of Resveramax, with LasR receptor protein was performed to evidence the QS-inhibitory potential of Resveramax. Results showed that Resveramax specifically inhibited the QS-mediated violacein pigment production in C. violaceum; pyocyanin production, proteolytic activity, swarming motility and biofilm formation in P. aeruginosa PAO1 in a concentration-dependent manner. Biofilms treated with Resveramax showed increased susceptibility to antibiotics when compared with the antibiotic treatment alone. Molecular docking analysis proved that resveratrol binds more rigidly with LasR receptor protein with docking score of -8.55 kJ/mol. These findings suggest that Resveramax could be used as novel QS-based antibacterial/anti-biofilm agent for the management of bacterial infections.
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- 2017
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21. The low and high temperature thermoelectric properties of Sb doped Cu 2 SnSe 3
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Ajay Dhar, Sivaiah Bathula, Ashok Rao, Y. K. Kuo, Bhasker Gahtori, K. Shyam Prasad, and Jia-Shiun Du
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010302 applied physics ,Diffraction ,Materials science ,Condensed matter physics ,Scattering ,Mechanical Engineering ,Doping ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Thermal conductivity ,Mechanics of Materials ,Electrical resistivity and conductivity ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,Figure of merit ,General Materials Science ,0210 nano-technology - Abstract
The effect of Sb doping on the thermoelectric properties of Cu 2 SnSe 3 was investigated. The Cu 2 Sn 1 x Sb x Se 3 (0 x 0.04) compounds were prepared by solid state synthesis. The powder X-ray diffraction pattern of the samples showed a cubic structure (space group F 4 ¯ 3 m ). The electrical resistivity decreased with increase in Sb content up to x = 0.02, then it increased with further increase in x . The electrical resistivity data follows variable hopping model at low temperatures. The Seebeck coefficient for all the samples is positive and analysis of data confirms that the variable hopping process is operative at low temperatures. The thermal conductivity is found to decrease with increase in Sb concentration, presumably due to point-defect scattering as a result of Sb substitution. The highest value of figure of merit at 400 K is equal to 0.0137 for the sample Cu 2 Sn 0.99 Sb 0.01 Se 3 which is about eight times greater than that of the pristine sample.
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- 2016
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22. Thermoelectric properties of p-type sb-doped Cu2SnSe3 near room and mid temperature applications
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Ruchi Bhardwaj, Ashok Rao, Kriti Tyagi, Avinash Vishwakarma, K. Shyam Prasad, and Nagendra S. Chauhan
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010302 applied physics ,Materials science ,Condensed matter physics ,Doping ,Spark plasma sintering ,Fermi energy ,02 engineering and technology ,General Chemistry ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electrical resistivity and conductivity ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,General Materials Science ,Charge carrier ,0210 nano-technology - Abstract
In this study, we report low and mid temperature range thermoelectric properties of Sb-substituted Cu2SnSe3 compounds. The Cu2Sn1−xSbxSe3 (0 ≤ x ≤ 0.04) alloys were prepared using conventional solid-state reaction followed by spark plasma sintering. The crystal structure was characterized using XRD and it reveals that all the samples exhibit cubic structure with space group $$\stackrel{-}{4}3m$$. The electrical transport characteristics indicate degenerate semiconducting behavior. Electrical resistivity was found to follow small polaron hopping (SPH) model in the entire temperature range of investigation. The Seebeck coefficient data reveals that the majority of charge carriers are holes and the analysis of Seebeck coefficient data gives negative values of Fermi energy indicating that the Fermi energy is below the edge of valence band. The electronic contribution (κe) for total thermal conductivity is found to be less than 1%. The maximum ZT value of 0.64 is observed for the sample with x = 0.03 (at 700 K) which is approximately 2.3 times that of the pristine sample.
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- 2018
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23. Viwithan, a Standardized
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H V, Sudeep, K, Gouthamchandra, B J, Venkatesh, and K Shyam, Prasad
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B16F1 cells ,cytotoxicity ,Original Article ,Apoptosis ,Withania somnifera - Abstract
Background: Withania somnifera is an Indian medicinal herb known for the multipotential ability to cure various therapeutic ailments as described in the ayurvedic system of medicine. Objective: In the present study, we have evaluated the antiproliferative activity of a standardized W. somnifera root extract (Viwithan) against different human and murine cancer cell lines. Materials and Methods: The cytotoxicity of Viwithan was determined using thiazolyl blue tetrazolium blue assay and crystal violet staining. The apoptotic changes in B16F1 cells following treatment with Viwithan were observed by acridine orange/ethidium bromide (AO/EB) staining and DNA fragmentation assay. The binding affinity of withanolides in Viwithan with antiapoptotic proteins B-cell lymphoma 2, B-cell lymphoma-extra large, and myeloid cell leukemia 1 (MCL-1) were studied using in silico approach. Results: The half maximal inhibitory concentration (IC50) values of Viwithan against liver hepatocellular carcinoma, Henrietta Lacks cervical carcinoma cells, human colorectal carcinoma cell line, and Ehrlich ascites carcinoma cells were 1830, 968, 2715, and 633 μg/ml, respectively. Interestingly, Viwithan was highly effective against B16F1 cells with an IC50 value of 220 μg/ml after 24 h treatment. The morphological alterations of apoptotic cell death were clearly observed in the AO/EB-stained cells after treatment with Viwithan. Viwithan induced late apoptotic changes in treated B16F1 cells as evident by the ladder formation of fragmented DNA in a time-dependent manner. The findings of molecular docking showed that withanolides present in Viwithan have a more binding affinity with the antiapoptotic proteins, particularly MCL-1. Conclusion: We have reported for the first time that Viwithan with 5% withanolides has a potent cytotoxic effect, particularly against B16F1 murine melanoma cells among the different cancer cell lines tested. SUMMARY The present study reports for the first time that Viwithan, a standardized 5% Withania somnifera root extract, has potent cytotoxicity against B16F1 murine melanoma cellsWe have investigated the in vitro cytotoxicity of Viwithan in different human and murine cancer cells. Interestingly, we found that Viwithan was particularly very effective against B16F1 melanoma cells with a half maximal inhibitory concentration value of 220 μg/mlThe microscopic observations following acridine orange/ethidium bromide staining and DNA fragmentation assays clearly indicated that Viwithan might initiate late apoptosis in B16F1 cellsThe binding affinity of withanolides in Viwithan with antiapoptotic proteins of B-cell lymphoma 2 family was predicted using AutoDock tool. The results from in silico studies indicated a plausible synergistic effect of withanolides attributing to the Viwithan-induced apoptosis through suppression of intrinsic pathway for carcinogenesis. Abbreviations used: MTT: Thiazolyl blue tetrazolium blue; DMSO: Dimethyl sulfoxide; BSA: Bovine serum albumin; DMEM: Dulbecco's minimum essential medium; NCCS: National Centre for Cell Science; PBS: Phosphate-Buffered Saline; HepG2: Liver hepatocellular carcinoma; HeLa: Henrietta Lacks cervical carcinoma cells; HCT-116: Human colorectal carcinoma cell line; EAC: Ehrlich ascites carcinoma cells; IC50: Half maximal inhibitory concentration; AO/EB: Acridine orange/Ethidium bromide; BCL-2: B-cell lymphoma 2; BCL-XL: B-cell lymphoma-extra large; MCL-1: Myeloid cell leukemia 1; PDB: Protein Data Bank; ANOVA: Analysis of variance.
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- 2017
24. Chlorogenic acid complex (CGA7), standardized extract from green coffee beans exerts anticancer effects against cultured human colon cancer HCT-116 cells
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B.J. Venkatesh, K Shyam Prasad, K. Gouthamchandra, and H V Sudeep
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0301 basic medicine ,Programmed cell death ,Apoptosis ,PARP-1 ,DNA fragmentation ,lcsh:TX341-641 ,Green coffee beans ,Biology ,03 medical and health sciences ,Ingredient ,chemistry.chemical_compound ,0302 clinical medicine ,Nutraceutical ,Chlorogenic acid ,medicine ,Cytotoxic T cell ,Chlorogenic acid complex ,Cancer ,medicine.disease ,030104 developmental biology ,chemistry ,Biochemistry ,030220 oncology & carcinogenesis ,lcsh:Nutrition. Foods and food supply ,Food Science - Abstract
Coffee is commonly consumed beverage in the world and it has been suggested to have beneficial effect. Chlorogenic acids (CGAs) are main ingredient of coffee beans which has been extensively used in nutraceuticals and medicine. Recently, various therapeutic effects of chlorogenic acids have been investigated. However, there are limited studies to investigate its anticancer properties. In the present study, we have used chlorogenic acid complex (CGA7) a decaffeinated water soluble green coffee bean extract to evaluate its cytotoxic effect on human and mouse cancer cell lines by using different approaches. From our results we found CGA7 treatment induces cell death in a dose and time dependent manner in different cancer cell lines. Further, CGA7 induced apoptosis was characterized by DNA fragmentation, PARP-1 cleavage, caspase-9 activation, and down regulation of Bcl-2, an anti-apoptotic protein and up regulation of pro-apoptotic protein BAX. Overall findings indicated that CGA7 complex a potent anticancer molecule found in green coffee beans could be a safe bioactive ingredient for prevention of cancer.
- Published
- 2017
25. SUNCA standardized extract from Helianthus annus L exerts enhanced digestive enzyme activity and subsides obesity through inhibition of C/EBP-α and PPAR-γ expression both in in vitro and in vivo model
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K Shyam Prasad, H V Sudeep, Amritharaj, H B Lingaraju, and K Gouthamchandra
- Subjects
chemistry.chemical_classification ,Triglyceride ,biology ,Chemistry ,Pharmaceutical Science ,Adipose tissue ,Peroxisome proliferator-activated receptor ,Pharmacology ,biology.organism_classification ,chemistry.chemical_compound ,Adipogenesis ,Drug Discovery ,Digestive enzyme ,Helianthus annuus ,biology.protein ,Sunflower seed ,Helianthus - Abstract
Background: Helianthus annuus L. (sunflower) is well known for its edible oil, sunflower seed has been used as folk remedy for several diseases including cancer. Materials and Methods: In this study, SUNCA, a standardized extract enriched with chlorogenic acid (CGA) from sunflower seed was investigated for in vitro antidiabetic activity using α-amylase and α-glucosidase enzyme inhibition assay. Further, for preventing obesity, we demonstrated anti-adipogenesis in 3T3-L1 cell culture system and on body weight gain and adiposity in rat fed high-fat diet (HFD). Results:SUNCA showed significant inhibitory activity toward digestive enzymes such as α-amylase and α-glucosidase. On the other hand, SUNCA significantly inhibits lipid accumulation during adipogenesis in a dose-dependent manner. The treatment with 100 μg/kg b.w of SUNCA apparently prevented the body weight gain and the increase of triglyceride and total cholesterol level in rat fed an HFD for 6 weeks. Further immunoblotting studies reveal that SUNCA significantly down-regulates the expression of transcription factors peroxisome proliferator-activated receptor gamma and CCAT/enhancer-binding protein alpha, both in adipocytes and adipose tissues. Conclusion: The findings reported here provide the therapeutic potential of SUNCA, a standardized extract from Helanthus annus L.
- Published
- 2019
- Full Text
- View/download PDF
26. MODELING OF HIGH-SPEED FINISH MILLING PROCESS USING SOFT COMPUTING
- Author
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K. Shyam Prasad, Bangal Surekha, Pandu R. Vundavilli, and Mahesh B. Parappagoudar
- Subjects
Soft computing ,Engineering ,Artificial neural network ,business.industry ,Process (computing) ,Binary number ,Transfer function ,Fuzzy logic ,Computer Science Applications ,Machining ,Modeling and Simulation ,Genetic algorithm ,Artificial intelligence ,business ,Algorithm - Abstract
In the present study, forward modeling of high-speed finish milling process has been solved using soft computing. Two different approaches, namely neural network (NN) and fuzzy logic (FL), have been developed to solve the said problem. The performance of NN and FL systems depends on the structure (i.e. number of neurons in the hidden layer, transfer functions, connection weights, etc.) and knowledge base (i.e. rule base and data base), respectively. Here, an approach is proposed to optimize the above-mentioned parameters of NN and FL systems. A binary coded genetic algorithm (GA) has been used for the said purpose. Once optimized, the NN and FL-based models will be able to provide optimal machining parameters online. The developed approaches are found to solve the above problem effectively, and the performances of the developed approaches have been compared among themselves and with that of the results of existing literature.
- Published
- 2010
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- View/download PDF
27. Rapid development and validation of improved reversed-phase high-performance liquid chromatography method for the quantification of mangiferin, a polyphenol xanthone glycoside in Mangifera indica
- Author
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H B Lingaraju, K Shyam Prasad, and Puttaswamy Naveen
- Subjects
validation ,0301 basic medicine ,Pharmacology ,Detection limit ,Reproducibility ,Chromatography ,Correlation coefficient ,Formic acid ,Short Communication ,Analytical chemistry ,Mangifera indica ,Liquid chromatography–mass spectrometry ,High-performance liquid chromatography ,mangiferin ,03 medical and health sciences ,chemistry.chemical_compound ,reversed-phase high-performance liquid chromatography ,030104 developmental biology ,0302 clinical medicine ,chemistry ,030220 oncology & carcinogenesis ,Drug Discovery ,Xanthone ,Mangiferin - Abstract
Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica, is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica. RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography–mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica. SUMMARY The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica. The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica. Abbreviations Used: M. indica: Mangifera indica, RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification.
- Published
- 2017
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28. In vitro cytotoxic activity of aqueous extract of Delonix elata (L.) gamble (fabaceae) leaves on mcf-7 & hep g-2 cell lines
- Author
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Kola, Phani Kumar, primary, K, Shyam Prasad, additional, N, Lakshmi Sudeepthi, additional, D, R.CH.Sekhara Reddy, additional, Sk, Abdul Rahaman, additional, and P, Madan Ranjith, additional
- Published
- 2014
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29. Hydroalcoholic extract from Lepidium meyenii(Black Maca) root exerts wound healing activity in Streptozotocin-induced diabetic rats
- Author
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B.V.B., Bramara, H.S., Vasavi, H.V., Sudeep, and K., Shyam Prasad
- Abstract
•The present study provides the first evidence on wound healing property of Lepidium meyenii(Black Maca) standardized root extract.•Interestingly there was a significant recovery in wound area of diabetic rats after topical/oral treatment with black maca extract.•Healing process is possibly mediated by antimicrobial effect and involvement of myofibroblasts.
- Published
- 2017
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30. [Are the advantages of percutaneous catheterization technique gained by increased blood trauma?]
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K, Shyam Prasad, M, Tönz, L K, von Segesser, B, Leskosek, P, Pei, and M, Turina
- Subjects
Leukocyte Count ,Catheters, Indwelling ,Catheterization, Peripheral ,Hemodynamics ,Hemoglobinometry ,Models, Cardiovascular ,Animals ,Humans ,Cattle ,Assisted Circulation ,Hemolysis ,Blood Cell Count - Abstract
The development of thin-walled cannulas which can be introduced by percutaneous technique into femoral artery and vein has revived interest in emergency cardiopulmonary support (CPS). To assess possible blood damaging effect due to the small-bore cannulas, 8 in vitro perfusions were performed with two parallel pump circuits: one circuit with a 17 F arterial and a 21 F venous cannula, one circuit without cannulas (control). The circuits were filled with 61 of bovine blood and run for 6 hours at a temperature of 37 degrees C and a flow of 4 l/min. Serial blood samples were taken before and during the experiment. There was a significantly higher level of free plasma haemoglobin (pl Hb) and a decreased number of leukocytes (Lc) after 6 hours of perfusion in the group with percutaneous cannulas as compared with control (pl Hb: 63.2 +/- 0.3 vs. 26.3 +/- 4.1 mumol/l, p0.05, Lc: 2.4 +/- 0.6 vs. 4.6 +/- 0.8 x 10(9)/l, p0.05, mean +/- se).percutaneous cannulas are associated with an increased blood trauma. If extended cardiopulmonary support is considered (more than several hours), percutaneous cannulas should be replaced by large-bore cannulas.
- Published
- 1993
31. Spodoptera frugiperda (JE Smith) in India: Pervasiveness, Host Range, and Management.
- Author
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Dash, Shubhasree, Korada, Rajasekhara Rao, and Mishra, Bijoy Kumar
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FALL armyworm ,SORGHUM ,INTEGRATED pest control ,CHLORANTRANILIPROLE ,CYHALOTHRIN ,PEST control - Abstract
The Fall Army Worm (FAW), scientifically referred to as Spodoptera frugiperda, originally emerged in the tropical and subtropical regions of the Americas. Its migration to Africa in 2016 and subsequent spread to Asia, reaching India in May 2018, raised signifi- cant concerns about the adaptable pest's expansion. Karnataka was the first state in India to report FAW, and by 2018 and early 2019, it had spread throughout peninsular India and the North and North East regions. This highly resilient insect has the ability to infest over 100 different plant species, making it a formidable pest. FAW has two dominant strains: The corn strain 'C,' affecting maize, sorghum, and cotton, and the rice strain 'R,' affecting rice and other grasses. The damage caused by FAW varies, posing a substantial threat to agriculture. The use of Integrated Pest Management (IPM) strategies has been shown to be effective in controlling FAW. Bio-rational pesticides, including Metarrhizium rileyi and Nomuraea rileyi, along with parasitoids like Telenomus sp., Trichogramma sp., Glyptapanteles creatonoti, and Campoletis chloridae, play a crucial role in managing the pest. Semiochemicals such as (Z)-9-tetradecenyl acetate and habitat management methods like Push-Pull technology also contribute to successful control. Chemical insecticides like chlorantraniliprole, spinetoram, thiamethoxam, and lambda cyhalothrin can be utilized to combat FAW. However, it is essential to note that early larval chemical control is more effective than late-stage intervention. The goal of this report is to emphasize the prevalence of FAW and to demonstrate the effective management techniques that have been used to minimize its effects. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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32. Effect of Cu Doping on Structural, Optical, and Electrical Properties of Sn2S3 Thin Films Prepared by Spray Pyrolysis.
- Author
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Nagaraja, B. S., Girija, K. P., Mahendra, K., Pattar, Jayadev, Gurumurthy, S. C., Ravikirana, Rao, Ashok, and Shyam Prasad, K.
- Subjects
THIN films ,COPPER ,ELECTRIC conductivity ,DIELECTRIC loss ,PYROLYSIS ,POLYCRYSTALLINE semiconductors ,N-type semiconductors - Abstract
The structural, optical, morphological, and electrical properties of polycrystalline copper-doped tin sulfide (Cu-Sn
2 S3 ) thin films with different concentrations of Cu dopants were synthesized using the spray pyrolysis method. Structural characterizations (powder XRD) revealed orthorhombic Sn2 S3 crystal structure with Pmma space group. The XRD spectra showed improved crystalline quality and preferential orientation for the Cu-doped Sn2 S3 thin films. Morphology of the prepared samples revealed sharp needle-shaped grains uniformly distributed throughout the sample. The UV spectroscopy results show 70–75% transmittance for 6 wt.% and 8 wt.% Cu-doped Sn2 S3 thin films in the visible region. The bandgap values are decreased for the 4 wt.% sample and increased with an increase in the Cu concentration for 2 wt.%, 6 wt.%, and 8 wt.% with Sn2 S3 thin films. The dielectric constant, dielectric loss, and electrical and optical properties were analyzed using UV data. Negative Hall coefficient values of prepared samples confirm the n-type semiconductor nature. Electrical conductivity increases with an increase in Cu concentration. These results indicate that the samples have potential applications in the optoelectronic field. [ABSTRACT FROM AUTHOR]- Published
- 2024
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33. Platinum and microspherule peaks as chronostratigraphic markers for onset of the Younger Dryas at Wakulla Springs, Florida.
- Author
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Moore, Christopher R., Brooks, Mark J., Dunbar, James S., Hemmings, C. Andrew, Langworthy, Kurt A., West, Allen, LeCompte, Malcolm A., Adedeji, Victor, Kennett, James P., and Feathers, James K.
- Abstract
Anomalous peak abundances of platinum and Fe-rich microspherules with high-temperature minerals have previously been demonstrated to be a chronostratigraphic marker for the lower Younger Dryas Boundary (YDB) dating to 12.8 ka. This study used Bayesian analyses to test this hypothesis in multiple sequences (units) of sandy, weakly stratified sediments at Wakulla Springs, Florida. Our investigations included platinum geochemistry, granulometry, optically stimulated luminescence (OSL) dating, and culturally dated lithics. In addition, sediments were analyzed using scanning electron microscopy and energy dispersive x-ray spectroscopy to investigate dendritic, iron-rich microspherules previously identified elsewhere in peak abundances at the onset of the Younger Dryas (YD) cool climatic episode. Our work has revealed this abundance peak in platinum and dendritic spherules in five sediment sequences at Wakulla Springs. A YDB age of ~ 12.8 ka for the platinum and spherule chronostratigraphic datum in these Wakulla Springs sequences is consistent with the archaeological data and OSL dating. This study confirms the utility of this YDB datum layer for intersequence correlation and for assessing relative ages of Paleoamerican artifacts, including those of likely Clovis, pre-Clovis, and post-Clovis age and their possible responses to environmental changes known to have occurred during the Younger Dryas cool climatic episode. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
34. Localizing the First Interstellar Meteor with Seismometer Data.
- Author
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Siraj, Amir and Loeb, Abraham
- Published
- 2023
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35. Detection and Quantification of Extraterrestrial Platinum Group Element Alloy Micronuggets from Archean Impactite Deposits by Low-Voltage Scanning Electron Microscopy/Energy-Dispersive X-ray Spectrometry.
- Author
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Salge, Tobias and Mohr-Westheide, Tanja
- Published
- 2023
- Full Text
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36. Role of charge doping and distortions on the structural, electrical, and magnetic properties of modified CuFeO2 compounds.
- Author
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Barot, Nishant, Mehta, Prashant K., Rao, Ashok, Thomas, Riya, Kuo, Yung-Kang, and Mishra, S. K.
- Subjects
MAGNETIC properties ,JAHN-Teller effect ,MAGNETIC transitions ,DIELECTRIC measurements ,MOSSBAUER effect ,RAMAN effect ,IRON compounds - Abstract
Single phase CuFeO
2 , CuFe0.96 M0.03 V0.01 O2 (M = Ti, Mn, and Ga), and CuFe0.96 V0.04 O2 compounds with space group R 3 ¯ m were prepared through a newly developed solid-state technique using annealing under high vacuum. Raman studies demonstrate, for the first time, a minor shift in Ti and Mn-doped samples as well as the Jahn–Teller effect induced distortions around 500 cm−1 along with well-documented peaks of Eg and A1g modes. Mössbauer studies confirm the presence of iron in high spin Fe3+ and quadruple splitting values endorsing the presence of octahedron distortions. An increase in the electrical conductivity at low temperatures is observed due to the enhanced charge doping with minor variations related to local distortions. Low-temperature magnetic studies of pristine and Ti-doped samples demonstrate paramagnetic nature up to 25 K. However, on one hand, the pristine sample shows a sharp rise in magnetization values at low applied fields and on the other side, Ti-doped samples exhibit nearly linear behavior. Dielectric measurements confirm weakening of electrical ordering near the magnetic transition in distorted Ti-doped samples, compared to pure CuFeO2 sample. Level of charges along with its local distortions affected mobility has significant effects on transport and multiferroic nature of these samples. [ABSTRACT FROM AUTHOR]- Published
- 2020
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37. CRISPR/Cas9‐mediated mutagenesis of Sex lethal (Sxl) gene impacts fertility of the Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae).
- Author
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Chikmagalur Nagaraja, Bhargava, Karuppannasamy, Ashok, Ramasamy, Asokan, Cholenahalli Narayanappa, Anu, Chalapathi, Pradeep, and Maligeppagol, Manamohan
- Published
- 2023
- Full Text
- View/download PDF
38. Mitigation of exotic fall armyworm Spodoptera frugiperda (J.E.Smith) on dryland Sorghum in Southern parts of India.
- Author
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Kamakshi, N., Srujana, Y., Krishna, T. Murali, Sameera, S. K., and Parveen, S. Isha
- Subjects
FALL armyworm ,EMAMECTIN benzoate ,SORGHUM ,CHLORANTRANILIPROLE ,POISONS ,AGRICULTURE - Abstract
Invasion of fall armyworm Spodoptera frugiperda in India has created potential damage to Sorghum crop along with the Maize. To alleviate the damage on sorghum and emphasize the relative cost and benefit, experimentation was done with various methods at Regional Agricultural Research Station, Nandyal, Acharya N G Ranga Agricultural University, Andhra Pradesh, India from 2018 to 2020 for three years. Among the twelve tested techniques, poison bait with thiodicarb 75 SP (9.52%) was effective in reducing the infestation of fall armyworm, which was on par with spinosad 45 SC (10.68%), chlorantraniliprole 18.5 SC (13.37%) and emamectin benzoate 5 SG (16.21%). Higher yields with greater benefit–cost ratio were noted with chlorantraniliprole 18.5 SC (5755 kg/ha; BC ratio 2.7) followed by spinosad 45 SC (5544 kg/ha; BC ratio 2.6), thiodicarb 75 SP (4940 kg/ha; BC ratio 2.3), dichlorvos + emamectin benzoate 5 SG (4811 kg/ha; 2.5), and emamectin benzoate 5 SG (4677 kg/ha; BC ratio 2.6). [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
39. Environmental Changes in Antarctica Using a Shallow Ice Core from Dronning Maud Land (DML), East Antarctica.
- Author
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Verma, Akshaya, Sain, Kalachand, and Kumar, Amit
- Published
- 2023
- Full Text
- View/download PDF
40. Band Engineering Through Pb-Doping of Nanocrystal Building Blocks to Enhance Thermoelectric Performance in Cu 3 SbSe 4 .
- Author
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Wan S, Xiao S, Li M, Wang X, Lim KH, Hong M, Ibáñez M, Cabot A, and Liu Y
- Abstract
Developing cost-effective and high-performance thermoelectric (TE) materials to assemble efficient TE devices presents a multitude of challenges and opportunities. Cu
3 SbSe4 is a promising p-type TE material based on relatively earth abundant elements. However, the challenge lies in its poor electrical conductivity. Herein, an efficient and scalable solution-based approach is developed to synthesize high-quality Cu3 SbSe4 nanocrystals doped with Pb at the Sb site. After ligand displacement and annealing treatments, the dried powders are consolidated into dense pellets, and their TE properties are investigated. Pb doping effectively increases the charge carrier concentration, resulting in a significant increase in electrical conductivity, while the Seebeck coefficients remain consistently high. The calculated band structure shows that Pb doping induces band convergence, thereby increasing the effective mass. Furthermore, the large ionic radius of Pb2+ results in the generation of additional point and plane defects and interphases, dramatically enhancing phonon scattering, which significantly decreases the lattice thermal conductivity at high temperatures. Overall, a maximum figure of merit (zTmax ) ≈ 0.85 at 653 K is obtained in Cu3 Sb0.97 Pb0.03 Se4 . This represents a 1.6-fold increase compared to the undoped sample and exceeds most doped Cu3 SbSe4 -based materials produced by solid-state, demonstrating advantages of versatility and cost-effectiveness using a solution-based technology., (© 2023 Wiley‐VCH GmbH.)- Published
- 2024
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41. Enhancement of thermoelectric power factor in Cu2Se superionic conductor via high energy electron beam irradiation.
- Author
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Mangavati, Suraj, Gurukrishna, K, Rao, Ashok, Petwal, Vikash Chandra, Verma, Vijay Pal, and Dwivedi, Jishnu
- Subjects
THERMOELECTRIC power ,SUPERIONIC conductors ,SEEBECK coefficient ,ELECTRON beams ,IRRADIATION ,ELECTRICAL resistivity - Abstract
The modification in the Cu
2 Se thermoelectric system by electron beam irradiation has been carried out in this work. Samples were prepared using the solid-state reaction technique. The prepared samples were irradiated with various energy dosages viz. 50, 100, and 150 kGy. XRD studies reveal that the synthesized samples crystallized in a monoclinic structure. The micro-hardness of the samples decreased with an increase in irradiation dosage. The sample irradiated at 100 kGy dose exhibits the lowest electrical resistivity, moderate Seebeck coefficient, and highest power factor. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
42. Iron‐based Semiconducting Half‐Heusler Alloys for Thermoelectric Applications.
- Author
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Chauhan, Nagendra S. and Miyazaki, Yuzuru
- Subjects
THERMOELECTRIC materials ,THERMOELECTRIC conversion ,ALLOYS ,IRON alloys ,THERMAL conductivity ,ELECTRONIC structure - Abstract
Iron‐based half‐Heusler alloys constitute an emerging class of semiconducting intermetallics for scalable and efficient thermoelectric conversion, owing to their remarkably high‐power factor, abundance, and low cost. This review encompasses the recent advances in materials synthesis and evolving aspects of optimization pathways in pre‐existing Fe‐based half‐Heusler compositions for attaining a higher thermoelectric figure of merit (zT). The experimental outcomes and theoretical predictions were analyzed and compared using a parametric framework to understand the underlying electronic transport responsible for high power factors exhibited by most of these alloys distinctively. Alongside, effective microstructural approaches were reviewed for which favorable reduction in intrinsically high lattice thermal conductivity (κL) was attained. The electronic structures of MFeSb (M=V, Nb, and Ta) half‐Heuslers is also analyzed using density functional theory‐based calculations to understand the origin of favorable conduction and electrical transport properties. Finally, processing‐structural‐property correlations are discussed to highlight the relevance of structural ordering, phase transformation, and defects on transport properties, for developing effective strategies and material design in Fe‐based half‐Heuslers for their development in thermoelectrics. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. Composition of Cosmic Spherules from Ferromanganese Crusts of the Magellan Seamounts.
- Author
-
Savelyev, D. P., Savelyeva, O. L., Moskaleva, S. V., and Rashidov, V. A.
- Subjects
FERROMANGANESE ,SEAMOUNTS ,COSMIC dust ,SCANNING electron microscopes ,RHODIUM ,PLATINUM ,CATALYTIC converters for automobiles - Abstract
2720 cosmic spherules extracted from ferromanganese crusts sampled at two guyots of the Magellan Seamounts were studied using a scanning electron microscope. In comparison with collections of modern cosmic spherules, our samples are significantly richer in I-type spherules (consisting of Fe oxides, often with a Fe–Ni metal core). The compositions of 406 metal cores were analyzed. Six spherules with cores significantly enriched in Co (>5 wt %) were found; these were the first spherules of this composition ever found worldwide. Such a high Co content in the cores cannot be explained by the evolution of a micrometeorite of chondrite composition at its melting. Some groups of the spherules have either elevated or lower Co concentrations than those expected according to the evolutionary trend of spherules at oxidation during the atmosphere entry. These groups apparently reflect the composition of the initial micrometeorites. It is proposed to use the composition of the cores of cosmic spherules to reveal the time variation in the composition of cosmic dust entering the Earth. Several spherules were found with small cores compared to the oxide shell; these cores are characterized by the presence of a significant amount of platinum group elements (PGE) (up to 2.4 wt % PGE). The averaged composition of PGE in the high-Ni core, which is the richest in PGE, shows a pattern close to that of chondrite. The collection contains 23 spherules that host PGE nuggets. In three spherules, micrometer-sized nuggets with various PGE were found (one nugget is Os + Ir + Ru, and two others contain all PGE). In 20 spherules, nanometer-sized nuggets of rhodium platinum were found. The largest nugget (3 μm) has PGE ratios close to chondritic, with the exception of a significant depletion in Pd. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
44. Improved electrical conductivity and power factor in Sn and Se co-doped melt-grown Bi2Te3 single crystal.
- Author
-
Hegde, Ganesh Shridhar, Prabhu, A. N., and Chattopadhyay, M. K.
- Subjects
SEEBECK coefficient ,SINGLE crystals ,ELECTRIC conductivity ,TIN ,ENERGY dispersive X-ray spectroscopy ,BISMUTH ,FIELD emission electron microscopy - Abstract
In the current work, growth and thermoelectric characterization of tin and selenium co-doped single crystal bismuth telluride have been carried out in the range of temperature 10–400 K. The crystals show hexagonal crystal structure with R 3 ¯ m space group. The direction of growth, quality of the single crystals, the density of dislocation, and dopants effect on the inner plane structure of the crystals have been analyzed through high-resolution X-ray diffraction study. Energy dispersive analysis of X-rays approves the elemental composition, and field emission scanning electron microscopy shows uniform growth with micro precipitates on the surface of the crystals. Quasi degenerate and non-degenerate electrical resistivity is observed in the pristine and doped samples, respectively. Temperature-dependent Seebeck coefficient measurements confirm the n-type semiconducting nature of the pristine as well as doped samples. Temperature-dependent power factor of (Bi
0.96 Sn0.04 )2 Te2.7 Se0.3 is found to increase by 1.1 times, and electrical resistivity reduced by 3.3 times as compared to pristine Bi2 Te3 . [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
45. Status Note on Indian Attempts to Search for Meteorites in Antarctica.
- Author
-
Swain, Ashit Kumar
- Subjects
METEORITES ,ICE sheets ,ANTARCTIC ice ,SCIENTIFIC community ,SOLAR system - Abstract
The study of meteorites is gaining importance due to its importance in understanding the development of our solar system. Published data shows that out of a total of 57186 meteorites recovered from the earth, 42398 are from Antarctica. This huge contribution of Antarctic meteorites is unique to Antarctica, as it allows the preservation of meteorites and concentrates them in highly ablative stranding surfaces. These surface or meteorite traps are formed as a result of topographic obstacles to the flow of the Polar ice sheet. Large tracts of central Droning Maud Land (cDML) in East Antarctica are still unexplored for meteorites. For the benefit of the global scientific community, it is desirable to recover as many Antarctic meteorites as possible before sinking deeper into the ice as a result of the changing climate and eventually being lost to the sea. The meteorite search programme was launched in the 32nd Indian Scientific Expedition to Antarctica. The primary objective of that investigation was to conduct a preliminary survey in the vicinity of the Somovken glacier flowing between the Humboldt and the Orvin mountain ranges for the prospect of finding meteorites. The search exercise was used to gain an understanding of the science of meteorites operating in Antarctica and the meteorite concentration mechanism. It was later complimented with the micrometeorite search programme in Antarctica. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
46. Standardized Saw Palmetto Extract Directly and Indirectly Affects Testosterone Biosynthesis and Spermatogenesis.
- Author
-
Yun, Jeong Moon, Lee, Minhee, Kim, Dakyung, Prasad, K. Shyam, Eun, Sangwon, Kim, Ok-Kyung, and Lee, Jeongmin
- Published
- 2021
- Full Text
- View/download PDF
47. A comparative study of the physical properties of Pr0.63La0.37−xSrxMnO3 (xSr = 0.00–0.30) characterized by "λ" shape dc magnetizations.
- Author
-
Hamdi, Riheb, Haik, Yousef, Hayek, Saleh S., Samara, Ayman, and Mansour, Said A.
- Subjects
MAGNETOCALORIC effects ,HEAT treatment ,MAGNETIC nanoparticles ,MAGNETIZATION ,SCANNING electron microscopy ,MAGNETIC fields - Abstract
Magnetic, morphological, and physical properties of Pr
0.63 La0.37−x Srx MnO3 (xSr = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.30) magnetic nanoparticles have been studied experimentally based on the evolution of the amount of Sr in these systems and by heat treatment. A solid-state reaction method was used to prepare the samples. The microstructure of the samples was determined by scanning electron microscopy. Three sets of Sr-doped manganites of the perovskite family Pr0.63 La0.37−x Srx MnO3 nanoparticles were heated at three different temperatures, i.e., 500, 700, and 800 °C. X-ray data showed that all compounds in the cubic space group Fd-3m crystallized. Field-cooled and zero-field-cooled thermomagnetic curves measured at low field and low temperatures showed that systems have different magnetic states, varying from superparamagnetic, ferromagnetic to paramagnetic states, with charge ordering behavior present in some prepared systems. The maximum entropy change of the xSr-800°C = 0.05 sample reached the highest value of refrigerant capacity compared to other systems in a magnetic field with 17.278 J/kg at 1 T and 208.264 J/kg at 7 T. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
48. Supplementation of green coffee bean extract in healthy overweight subjects increases lean mass/fat mass ratio: A randomized, double-blind clinical study.
- Author
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Sudeep, HV and Shyam Prasad, K
- Published
- 2021
- Full Text
- View/download PDF
49. Bioaccessibility of Tudela artichoke (Cynara scolymus cv. Blanca de Tudela) (poly)phenols: the effects of heat treatment, simulated gastrointestinal digestion and human colonic microbiota.
- Author
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Domínguez-Fernández, Maite, Ludwig, Iziar A., De Peña, María-Paz, and Cid, Concepción
- Published
- 2021
- Full Text
- View/download PDF
50. Probing the nature of extraterrestrial dust reaching the Earth's surface collected from the Maitri station, Antarctica.
- Author
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Rudraswami, N. G., Fernandes, D., and Pandey, M.
- Subjects
SURFACE of the earth ,EXTRATERRESTRIAL life ,DUST ,SUBGLACIAL lakes - Abstract
Micrometeorites (MMs) are extraterrestrial dust particles, in the size range of tens of µm to mm, recovered from the Earth's surface primarily from deep‐sea sediments, Antarctica, and also from space. The present collection of MMs (>50 µm) obtained by melting ~50 t of ice near the Maitri station, Antarctica, has allowed us to investigate the abundance and properties of the particles by an unbiased collection technique. The collection reveals a large quantity of extraterrestrial material in the ~80−140 µm size range. Previous collections have shown an abundance of particles at diameter ~200 µm, which is in contrast to our findings. This can either be explained by movement of material within the ice or a recent influx of smaller particles. The smaller particles (<80 µm) typically undergo atmospheric entry heating, contrary to earlier observations, which have suggested that they reach the Earth's surface unmelted. Chondrules and refractory inclusions are rare in the collected MMs indicating that their contribution is only a small percentage. The Maitri station collection does not have a well‐constrained ice accumulation rate and terrestrial age. Nevertheless, based on matching the previous well‐documented flux calculation of Antarctica, we suggest a slow ice accumulation rate of <1.0 g cm−2 yr−1 near Maitri station. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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