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On the convergence of the accelerated Riccati iteration method

Wed, 01 Jan 2020 00:00:00 GMT

Title: On the convergence of the accelerated Riccati iteration method Authors: Prasanthan, R.; Jianhong Xu Abstract: In this paper, we establish results fully addressing two open problems proposed recently by I. Ivanov, see Nonlinear Analysis 69 (2008) 4012–4024, with respect to the convergence of the accelerated Riccati iteration methodfor solving the continuous coupled algebraic Riccati equation, or CCAREfor short. These results confirm several desirable features of that method, including the monotonicity and boundedness of the sequences it produces, its capability of determining whether the CCARE has a solution, the extremal solutions it computes under certain circumstances, and its faster convergence than the regular Riccati iteration method

Ruthenium (Ru) Doped Titanium Dioxide (P25) Electrode for Dye Sensitized Solar Cells

Wed, 01 Jan 2020 00:00:00 GMT

Title: Ruthenium (Ru) Doped Titanium Dioxide (P25) Electrode for Dye Sensitized Solar Cells Authors: Rajaramanan, T.; Natarajan, M.; Ravirajan, P.; Senthilnanthanan, M.; Velauthapillai, D. Abstract: In this study, P25-titanium dioxide (TiO2) was doped with ruthenium (Ru) by systematically varying the Ru content at 0.15, 0.30, 0.45 and 0.6 mol%. The synthesized Ru-doped TiO2 nanomaterials have been characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray (EDX) analysis, UV-visible (UV–Vis) spectroscopy, and electrochemical impedance (EIS) spectroscopy. The XRD patterns of undoped and Ru-doped TiO2 nanomaterials confirm the presence of mixed anatase and rutile phases of TiO2 while EDX spectrum confirms the presence of Ti, O and Ru. Further, UV-visible absorption spectra of doped TiO2 nanomaterial reveal a slight red shift on Ru-doping. The short circuit current density (JSC) of the cells fabricated using the Ru-doped TiO2 photoanode was found to be dependent on the amount of Ru present in TiO2. Optimized cells with 0.3 mol% Ru-doped TiO2 electrodes showed efficiency which is 20% more than the efficiency of the control cell (η = 5.8%) under stimulated illumination (100 mWcm−2 , 1 sun) with AM 1.5 filter. The increase in JSC resulted from the reduced rate of recombination upon doping of Ru and this was confirmed by EIS analysis.

Antimicrobial activity of Azadirachta Indica (neem) leaf, bark and seed extracts

Wed, 01 Jan 2020 00:00:00 GMT

Title: Antimicrobial activity of Azadirachta Indica (neem) leaf, bark and seed extracts Authors: Raja Ratna Reddy, Y.; Krishna Kumari, C.; Lokanatha, O.; Mamatha, S.; Damodar Reddy, C. Abstract: Screening of medicinal plants for bioactive compounds leads to development of less expensive new antimicrobial agents with improved safety and efficacy. Azadirachta Indica (neem) is a multipurpose tree with multiple health benefits. Different parts of the plant are shown to exhibit antimicrobial effects against a wide variety of microorganisms. In the present study we compared the antimicrobial efficacy of aqueous extracts of leaf, bark and seeds of A. Indica against human pathogenic bacteria (Staphylococcus aureus, Enterococcus feacalis, Proteus mirabilis and Pseudomonas aeuroginosa) and fungi (Aspergillus fumigatus and Candida albicans). Agar well diffusion method and micro-broth dilution methods were used to determine the minimum inhibitory concentration (MIC). Results showed that leaf extract exhibited strong antimicrobial activity against bacteria and fungi at all the concentrations tested (500, 1000 and 2000µg/ml). Antimicrobial activity of bark extract was found to be moderate on bacteria and fungi (effective at 1000 and 2000µg/ml), whereas seed extract exhibited least antimicrobial activity. Minimum inhibitory concentration (MIC) of leaf and bark extract was found to be in the range of 500 to 2000µg/ml for all the tested microorganisms, where as the seed extract did not inhibit the microorganisms at all the concentrations tested except Candida albicans (1000µg /ml). Our results suggest that aqueous extracts of Azadirachta Indica leaf and bark exhibit high antimicrobial activity.

Utilization of bioethanol generated from papaw peel waste for hand sanitizer production

Fri, 01 Jan 2021 00:00:00 GMT

Title: Utilization of bioethanol generated from papaw peel waste for hand sanitizer production Authors: Amanullah, A.; Kapilan, R. Abstract: Hands are the primary mode for the spread of microbes. For infection control, the first-line of defense as well as personal hygiene, are mandatory. Hand sanitizers that contain ethanol as the main constituent are used to kill a broad range of microbes. Demand for petroleum-derived ethanol is increasing with the COVID-19 outbreak and primary suppliers are searching for alternatives to overcome this problem. Objective of this study is to produce bioethanol from ripen papaw peel waste using Saccharomyces cerevisiae and to determine the potential utilization of bioethanol generated from papaw peel waste for a pilot study of which the end aim is hand sanitizer production. The blended ripened papaw (Carica papaya) fruit peel (100g/L) was inoculated with the S. cerevisiae (2g/L) in a fermentation medium that contains 10 g/L yeast extract, 10 g/L KH2PO4, 2 g/L (NH4)2SO4 and 0.5 g/L MgSO4•7H2O and allowed to ferment for 6-36 hours at room temperature. The bioethanol yield obtained after 12 hours, was 0.6% (V/V). The fermentation conditions were optimized by changing one factor at a time, while keeping the other variables constant. Significantly higher bioethanol yield (6.2 times, 3.7% V/V [p<0.05]) was obtained from papaya peels at the optimized conditions of 12 hours of incubation period, 5:1 ratio between air space and fermentation solution, 5g/L of yeast inoculum, 15g/100ml of papaw fruit peel, 1g/100ml of soybean powder as nitrogen source, 60ml/100ml of diluted sulfuric acid at pH 5. When the agar well diffusion assay was performed against pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, Bacillus spp. and Pseudomonas spp, all the bacterial strains showed an inhibition zone, i.e., they were sensitive for the bioethanol extract.