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Ravi Shankar,Rajneesh K Srivastava,S.G. Prakash 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5
In the present work, zinc oxalate [ZnC2O4·2H2O] was used as precursor to prepare zinc oxide nano structures by thermal decomposition. Its photoconductivity and dark-conductivity properties have been studied in air as well as in vacuum. Voltage dependence of photocurrent and dark-current has been observed at room temperature in air under UV-vis illumination and is found as superlinear in nature. Rise and decay curve in air exhibits anomalous behavior wherein the photocurrent decreases even during steady illumination. In vacuum,the rise of photocurrent becomes slow and prolonged.
Fuzzy logic feed‑forward impedance shaping of DAB converter in DC microgrid with CPL load
Ravishankar Gupta,Navdeep Singh 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.10
In a DC microgrid, the dual active bridge (DAB) converter is employed for voltage conversion and power transfer. DABbased energy storage systems (ESSs) are known as constant power loads (CPLs). To improve the input current quality of DAB converter, an LC filter is cascaded to a DAB converter. Impedance interaction takes place between the impedance of the LC filter (Zout) and the impedance of the DAB converter (Zin). ESSs are affected by the impedance interactions of cascaded systems. This interaction leads to significant oscillation and instability, which in turn causes voltage fluctuation and power loss. To overcome instability, this paper proposes a modified fuzzy logic controller (FLC), an active voltage stabilizer (AVS), and feed-forward (FF) controller to reshape the impedance of the DAB converter. In the modified controller, the FLC handles precise voltage monitoring, the AVS handles the transient stability limit, and the FF controller removes the impedance interaction between Zin and Zout. The feed-forward coefficient is calculated through the Routh–Hurwitz criterion. The suggested controller assures system stability during load variation, a quick dynamic response, and precise voltage monitoring. In addition, it achieves reductions in the settling time, rise time, and overshoot. This leads to reliable microgrid operation when compared to the traditional PI (PI + AVS), and (PI + AVS + FF) controllers. The modified controller is verified by results obtained with an OPL-RT-based hardware-in-the-loop (HIL).
Ravishankar Lingesha Telgi,Vaibhav Tandon,Pradeep Shankar Tangade,Amit Tirth,Sumit Kumar,Vipul Yadav 대한치주과학회 2013 Journal of Periodontal & Implant Science Vol.43 No.4
Purpose: Diabetes and periodontal disease are two common diseases with high prevalence rates. Recent evidence has shown a bidirectional relationship between diabetes and periodontitis. The aim of this study was to investigate the effects of nonsurgical periodontal therapy on glycemic control in type 2 diabetes mellitus patients. Methods: Sixty subjects aged 35–45 years with blood sugar controlled by oral hypoglycaemic agents were randomly divided equally among 3 groups: group A (scaling, mouthwash, and brushing), group B (mouthwash and brushing), and group C (brushing only). Glycated haemoglobin (HbA1c), fasting blood sugar (FBS), probing pocket depth (PPD), gingival index (GI), plaque index (PI), and the relevant drug history were recorded at baseline and after 3 months of intervention. Comparison of the mean difference among the variables was performed by parametric and nonparametric tests, which were further evaluated using multiple regression analysis. Results: The mean differences between the PPD, FBS, HbA1c, GI, and PI in groups A and B were found to be statistically significant (P<0.001). Multiple regression analysis in group A showed that out of all the independent variables, GI and frequency of drug administration independently (b=0.3761 and b=0.598) showed a significantly greater impact on HbA1c (R2=0.832, P<0.05). Conclusions: Nonsurgical periodontal therapy can effectively decrease HbA1c levels in type 2 diabetes mellitus patients on medication.
Telgi, Ravishankar Lingesha,Tandon, Vaibhav,Tangade, Pradeep Shankar,Tirth, Amit,Kumar, Sumit,Yadav, Vipul Korean Academy of Periodontology 2013 Journal of Periodontal & Implant Science Vol.43 No.4
Purpose: Diabetes and periodontal disease are two common diseases with high prevalence rates. Recent evidence has shown a bidirectional relationship between diabetes and periodontitis. The aim of this study was to investigate the effects of nonsurgical periodontal therapy on glycemic control in type 2 diabetes mellitus patients. Methods: Sixty subjects aged 35-45 years with blood sugar controlled by oral hypoglycaemic agents were randomly divided equally among 3 groups: group A (scaling, mouthwash, and brushing), group B (mouthwash and brushing), and group C (brushing only). Glycated haemoglobin (HbA1c), fasting blood sugar (FBS), probing pocket depth (PPD), gingival index (GI), plaque index (PI), and the relevant drug history were recorded at baseline and after 3 months of intervention. Comparison of the mean difference among the variables was performed by parametric and nonparametric tests, which were further evaluated using multiple regression analysis. Results: The mean differences between the PPD, FBS, HbA1c, GI, and PI in groups A and B were found to be statistically significant (P<0.001). Multiple regression analysis in group A showed that out of all the independent variables, GI and frequency of drug administration independently (b=0.3761 and b=0.598) showed a significantly greater impact on HbA1c ($R^2$=0.832, P<0.05). Conclusions: Nonsurgical periodontal therapy can effectively decrease HbA1c levels in type 2 diabetes mellitus patients on medication.
Antioxidant and Antimicrobial Activity of Cissus quadrangularis L.
G.A. Ravishankar,K.N. Chidambara Murthy,A. Vanitha,M. Mahadeva Swamy 한국식품영양과학회 2003 Journal of medicinal food Vol.6 No.2
Extracts of Cissus quadrangularis L. were tested for antioxidant activity by b-carotene linoleicacid model and also by 1,1-diphenyl-2-picrylhydrazyl model. The ethyl acetate fraction ofboth fresh and dry stem extracts at a concentration of 100 pm showed 64.8% antioxidant ac-tivity in the b-carotene linoleic acid system and 61.6% in the 1,1-diphenyl-2-picrylhydrazylsystem. This fraction showed the presence of sterols, vitamin C, and tanins as phytocon-stituents. The antioxidant activity of methanol extract and aqueous extract were comparativelyless significant than that of ethyl acetate extract, and n-hexane extract showed the least ac-tivity. The ethyl acetate extract and methanol extract of both fresh and dry stems further ex-hibited antimicrobial activity against Gram-positive bacteria, including Bacillus subtilis,Bacillus cereus, Staphylococcus aureus , and Streptococcus species. The results of the studyhave implications in the use of C. quadrangularis as an antibacterial agent and more so as anantioxidant in several aplications requiring these properties.9
Zhang, Kan,Ravishankar, Sandheep,Ma, Ming,Veerappan, Ganapathy,Bisquert, Juan,Fabregat-Santiago, Francisco,Park, Jong Hyeok Wiley 2017 ADVANCED ENERGY MATERIALS Vol.7 No.3
<P>Bulk and surface charge recombination of photoelectrode are two key processes that significantly hinder solar-to-fuel conversion of photoelectrochemical cell (PEC). In this study, the function of a crystal-deficient overlayer is unveiled, which outperforms a traditionally used amorphous or crystalline overlayer in PEC water splitting by exhibiting a high conductivity and large electron diffusion length to enable unlimited electron collection. The optimized approximate to 2.5 nm thickness of the crystal-deficient shell results in a depletion layer with a width of 3 nm, which overcomes the flat band limitation of the photovoltage and increases the light absorptivity in the wavelength range from 300 to 420 nm. In addition, a 50-fold increase in the conductivity yields a one-order-of-magnitude increase in the diffusion length of an electron (L-n)(approximate to 20 m), allowing for unlimited electron collection in the 1.9 m TiO2 nanowire array with the crystal-deficient shell. The controllable crystal-deficient overlayer in rutile TiO2 nanowires photoanode achieves a photocurrent density greater than 2.0 mA cm(-2) at 1.23 V versus reversible hydrogen electrode (RHE), a 1.18% applied bias photon-to-current efficiency at 0.49 V versus RHE, a faradaic efficiency greater than 93.5% at 0.6 V versus Pt under air mass 1.5G simulated solar light illumination (100 mW cm(-2)).</P>
Jones, Jana,Mirzaei, Mehdi,Ravishankar, Prathiba,Xavier, Dylan,Lim, Do Seon,Shin, Dong Hoon,Bianucci, Raffaella,Haynes, Paul A. Royal Society 2016 Philosophical transactions. Series A, Mathematical Vol.374 No.2079
<P>This article is part of the themed issue 'Quantitative mass spectrometry'.</P>
Jamuna Bai Aswathanarayan,Ravishankar Rai Vittal 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.6
The effects of different nutrient sources andtemperatures on attachment and biofilm formation ofPseudomonas fluorescens PSD4, a dairy isolate, werestudied. Initial adherence and attachment capabilitiesamong different strains were studied using microtitre plateassays. Biofilm development was observed using confocalmicroscopy. Strongly adherent cells were seen in proteinrich media. Citrate as a carbon source enhanced biofilmformation. Glucose did not favor biofilm development. Psychrotrophic P. fluorescens PSD4 formed stronglyadherent biofilms having high metabolic activities at lowtemperatures. P. fluorescens PSD4 with spoilage potentialwas capable of forming strong biofilms in dairy processingenvironments. Biofilm formation was influenced bynutrient availability and growth conditions. These factorsshould be considered for design of effective anti-biofilmstrategies.