1,088 research outputs found

    Cu2+ uptake by Chlorococcum hemicolum - A Xeric Chlorophycean Alga

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    Bioremediation of copper by xeric chlorophycean bioremediator, Chlorococcum hemicolum was investigated. The growth rates at various concentrations of Cu2+ were assessed in terms of protein level and 8 mg L-1 (37.67 % level in growth kinetics) is the tolerance limit. Absorption/adsorption kinetics was estimated after 240 hrs of Cu2+ treatments. Absorptions were higher than adsorption with maximum accumulation factor (AF) of 1.40. The Cu2+ concentration and absorption were linearly related (r = 0.99; p>0.01). Other biochemical parameters like total sugar, chlorophyll and carotenoids were also quantified to correlate the state of metabolism and these exhibited reduction due to heavy metal stress

    Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln 3+-TiO 2 surface under UV/solar light

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    The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln 3+ (Ln 3+ = La 3+, Ce 3+ and Gd 3+) doped TiO 2 at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd 3+ (0.15 mol)-TiO 2 exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd 3+ ions. It is proposed that Ln 3+ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule. √ā¬© 2012 Elsevier B.V. All rights reserved

    An Investigation on Strength of SS316L and Cobalt- Chromium used as cardio Vascular Stent materials by nonlinear FEA

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    Aim of this study is to provide a computational approach for evaluating the effect of Stents on biomechanical outcome of deployment of stent in different condition. Nonlinear FEA software has been used successfully on balloon expandable stents. Projects often require modelling systems that consist of multiple components with nonlinear materials, complex 3D geometries. The ABACUS, handles the full range of nonlinear material properties for the stent, the catheter balloon, and the artery wall. The objective of research carried out was to simulate the mechanical behaviour of the stent using finite element analysis. Implantation and in vivo loading are considered. Finite element analysis provides a quick and cost-effective method for evaluating stent performance, yielding accurate information about the expanded geometry and the stress and strain deformation fields with in the stent for various loading conditions. With appropriate applied internal pressure, the balloon inside the stent is deployed which linearlyexpands the diameter of a Modular Stent until it reaches 1.7 times of its original diameter. The results will assist in the development of novel stent designs and stent deployment to minimize vascular injury during stenting and reduce restenosis. The results obtained for the selected stent material are compared. The Cobalt-chromium undergone plastic deformation at 0.44 MPa and SS316L at 0.3 MPa pressure load

    Photocatalytic activity of TiO2 doped with Zn2+ and V5+ transition metal ions: Influence of crystallite size and dopant electronic configuration on photocatalytic activity

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    Anatase TiO2 was prepared by sol-gel method through the hydrolysis of titanium tetrachloride and doped with transition metal ions like V5+ and Zn2+. The photocatalysts were characterized by various analytical techniques. Powder X-ray diffraction studies revealed only anatase phase for the doped samples. The band gap absorption for the doped samples showed red shift to the visible region (√ʬľ456 nm) as confirmed by UV-vis absorption spectroscopy and diffuse reflectance spectral studies. The surface area of the Zn2+ doped samples were higher than the V5+ doped samples as observed by BET surface area measurements due to their smaller crystallite size. Scanning electron microscopy showed almost similar morphology, while energy dispersive X-ray analysis confirmed the presence of dopant in the TiO2 matrix. The photocatalytic activities of these catalysts were tested for the degradation of Congo Red under solar light. Although both the doped samples showed similar red shift in the band gap, Zn2+ (0.06 at.) doped TiO2 showed enhanced activity and its efficiency was five fold higher compared to Degussa P-25 TiO2. This enhanced activity was attributed to smaller crystallite size and larger surface area. Further completely filled stable electronic configuration (d10) of Zn2+ shallowly traps the charge carriers and detraps the same to the surface adsorbed species thereby accelerating the interfacial charge transfer process. √ā¬© 2009 Elsevier B.V. All rights reserved

    Photo fenton like process Fe3+/(NH4)2 S2O8/UV for the degradation of Di azo dye congo red using low iron concentration

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    Degradation of Congo Red (CR) a di azo dye in aqueous solution is investigated by a Photo Fenton like process using Fe3+ ions as the catalyst and peroxy disulfate as the oxidant. The influence of various reaction parameters like, concentration of Fe3+ ions, concentration of the dye, concentration of ammonium persulfate, pH of the solution and the presence of hydroxyl radical scavenger are studied and optimal conditions are reported. The degradation rate decreased at higher dye concentration and at higher pH. The rate constant (k), catalytic efficiency (kc) and process efficiency (ő¶) are evaluated for different concentration of Fe3+ ions. The degradation of CR by the photo Fenton like process leads to the formation of 4-Amino, 3-azo naphthalene sulphonic acid, dihydroxy substituted naphthalene, dihydroxy substituted biphenyl, phenol, quinol etc., as intermediates, based on which probable degradation mechanism is proposed. These results show that a photo Fenton like process could be useful technology for the mineralization of di azo dyes under lower concentration of iron in acidic conditions. The present process is advantageous as it lowers the sludge production resulting from the iron compl

    Photocatalytic activity of V5+, Mo6+ and Th4+ doped polycrystalline TiO2 for the degradation of chlorpyrifos under UV/solar light

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    TiO2 photocatalysts were prepared by doping transition metal ions like V5+, Mo6+and an inner transition metal Th4+ in the concentration range of 0.02-0.1 and were characterized by various analytical techniques. The photocatalytic activities of these catalysts were studied for the mineralization of chlorpyrifos (CP) as a probe molecule. X-ray diffraction results showed only anatase phase irrespective of nature, oxidation state and concentration of these dopants. The photocatalytic activity of undoped TiO2 showed a better activity under UV light compared to doped catalysts. Under solar light illumination, the Th4+ (0.06)-TiO2 showed highest activity for the mineralization of CP. This was attributed to the prolonged separation of photogenerated electron-hole pairs, high specific surface area of the catalyst and high concentration of surface adsorbed water/hydroxyl groups. Further large shift in the absorption band (460 and 482 nm) due to the creation of mid band gap states by Th4+ dopant and also by its small crystallite size additionally contributes to the enhancement of the degradation process. The degradation pathway was followed by UV-vis spectroscopic and GC-MS analysis. √ā¬© 2009 Elsevier B.V. All rights reserved

    Enhanced photocatalytic activity of transition metal ions Mn2+, Ni2+ and Zn2+ doped polycrystalline titania for the degradation of Aniline Blue under UV/solar light

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    Anatase TiO2 was doped with divalent transition metal ions like Mn2+, Ni2+ and Zn2+ and characterized by various analytical techniques. Powder X-ray diffraction revealed stabilization of anatase phase for Ni2+ and Zn2+ doped samples, while phase transformation from anatase to rutile was promoted due to Mn2+ inclusion. The rutile fraction increased with Mn2+ concentration due to the creation of surface oxygen vacancies. All the doped catalysts showed red shift in the band gap absorption to the visible region. The photocatalytic activities of these catalysts were evaluated in the degradation of Aniline Blue (AB) under UV/solar light. Among the photocatalysts, Mn2+ (0.06 at.)-TiO2 showed enhanced activity, which is attributed to the synergistic effect in the bicrystalline framework of anatase and rutile. Further the unique half filled electronic structure of Mn2+ serves as a shallow trap for the charge carriers to enhance the photocatalytic activity. An insight to the mechanism of interfacial charge transfer in the mixed phase of anatase and rutile is explored, taking into consideration the theories of previous models. √ā¬© 2010 Elsevier B.V

    Kinetic modeling based on the non-linear regression analysis for the degradation of Alizarin Red S by advanced photo Fenton process using zero valent metallic iron as the catalyst

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    The degradation of Alizarin Red S (ARS), an anthraquinone dye was investigated by advanced photo Fenton process using zero valent metallic iron (ZVMI) powder as the catalyst with symmetrical peroxides like hydrogen peroxide (HP)/ammonium persulfate (APS) as the oxidants. APS is proved to be a better oxidant compared to HP as it provides efficient acidic medium which is critical for Fenton process. A kinetic/mathematical model was developed based on the non-linear regression analysis and the validity of the model was tested by comparing the observed experimental values with the theoretically calculated data. The rate equation obtained was found to be a function of iron dosage, oxidant and dye concentration at pH 3.k = 0.2456 Fe 0.21 APS 0.15 ARS - 0.76k = 0.58 Fe 0.12 HP 0.10 ARS - 0.86. The degradation pathway was followed by UV-vis spectroscopy and GC-MS techniques. Based on the intermediates analyzed, a probable degradation mechanism has been proposed. √ā¬© 2009 Elsevier B.V. All rights reserved

    Preparation, characterization and enhanced photocatalytic activity of Ni2+ doped titania under solar light

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    Anatase TiO2 was prepared by sol-gel method through the hydrolysis of TiCl4. Ni2+ was doped into the TiO2 matrix in the concentration range of 0.02 to 0.1 at. and characterized by various analytical techniques. Powder X-ray diffraction revealed only anatase phase for all the samples, while diffuse reflectance spectral studies indicated a red shift in the band gap absorption to the visible region. The photocatalytic activities of these photocatalysts were probed for the degradation of methyl orange under natural solar light. The photocatalyst with optimum doping of 0.08 at. Ni2+, showed enhanced activity, which is attributed to: (i) effective separation of charge carriers and (ii) large red shift in the band gap to visible region. The influence of crystallite size and dopant concentration on the charge carrier trapping - recombination dynamics is investigated. √ā¬© Versita Warsaw and Springer-Verlag Berlin Heidelberg

    HOME REMEDIES FOR ORAL DISEASES

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    Self-help through self-treatment makes a countless contribution. Home remedy use is a component of health self-management, particularly among people who have experienced limited access to medical care or discrimination by the health care system. Self-care using home remedies survived for long time and it surely give effect in the easiest, safest, fastest and cheapest way. Oral diseases are a significant public health burden in India as well as across the globe. The consequence of poor oral health deteriorates the individual health and wellbeing, decrease economic productivity, and act as significant risk factors for other systemic health ailments.  Developing countries have more diverse health systems than developed countries and expenditure in oral health care is low, access to Dental healthcare is limited and restricted to emergency Dental care or pain relief. Moreover, allopathic medicine is expensive and these chemicals can have adverse effects. Hence, there is a need for alternative products and natural extracts obtained from plants which are safe and biocompatible can be considered as good alternatives. In such circumstances use of home remedies would meet the need for treating minor ailments safely. Home remedies are good and comparable methods of equal value which have met the scientific and regulatory criteria for safety and effectiveness. The purpose of this review was to evaluate some of the commonly available foods being utilized in the treatment of oral diseases at home
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