Tyagi N.,Center for Environmental Science and Engineering |
Suresh S.,Center for Environmental Science and Engineering
Journal of Cleaner Production | Year: 2015
Cellulose production by Gluconacetobacter intermedius SNT-1 under static condition was compared using various carbon sources. The trend observed was: HS-glucose>HS-glucose+sucrose+fructose>HS-fructose>HS-sucrose. Molasses, an industrial byproduct also served as a feedstock for cellulose production. Cellulose yield of 12.6gL-1 was obtained from 45.8gL-1 of diluted (1:4) molasses after H2SO4-heat pre-treatment. Cellulose yields were comparable using corn-steep liquor or yeast extract as the nitrogen sources along with heat pretreated molasses. Cellulose production was decreased by 30% in the absence of polypeptone. The number of viable cells entrapped within bacterial cellulose mat was much higher in comparison to that present in the spent medium. Cellulose immobilized cells may be protected against toxicity of components present in molasses. Bacterial cellulose produced from pretreated molasses contained mixture of cellulose I and cellulose II types, was predominantly in Iα (~60%) form, had high tensile strength. This study demonstrates the suitability of using molasses from sugar industries as cheap carbon source for production of bacterial cellulose, with characteristics similar to those obtained using expensive carbon sources such as glucose or fructose. Huge amount of molasses is produced worldwide annually and therefore it is a readily available resource for cellulose production. Cellulose produced by bacteria using molasses is relatively pure which does not require extensive chemical treatments as in Kraft pulping or bleaching. Bacterial production of cellulose causes lower impact on environment in terms of pollution load and energy consumption. © 2015 Elsevier Ltd.
Zhang J.,Center for Environmental science and Engineering
2012 2nd International Conference on Remote Sensing, Environment and Transportation Engineering, RSETE 2012 - Proceedings | Year: 2012
Upgrading of a landfill leachate treatment plant (LLTP) to meet capacity expansion as well as the new discharge standards is addressed. According to the upgrading scheme, the hybrid membrane processes based on membrane bioreactor (MBR) technology are adopted in the plant. A reverse osmosis (RO) unit is installed in the original facility to polish the effluent for reclaimed water reuse, and a new system combined two-stage MBR unit with two-stage nanofiltration (NF) unit is built to enhance treatment capability for additional load from capacity expansion. The results show that the treatment capacity of the plant has increased from 200 to 900 m 3/d, and the effluent of the upgraded LLTP has met the new discharge standards. © 2012 IEEE.
Verma N.,Center for Environmental Science and Engineering
Polymer Composites | Year: 2015
Alumina (AA) nanoparticles- (NPs) dispersed activated carbon microfibers/carbon nanofibers (ACFs/CNFs) were used as fillers in a ∼30 μm thick polymeric film of polypropylene (PP) cross-linked with maleic anhydride (MAH) and polyethylene glycol (PEG). The PEG-MAH-PP film was prepared using the solution casting method, with MAH acting as a "bridging" group between PEG and PP. The AA-ACF/CNF filler was dispersed in situ into the reaction mixture during polymerization and before the curing step. The metal oxide NPs-carbon micro-nanofiber-polymer (AA-ACF/CNF-PP) nanocomposite exhibited significantly enhanced electrical, thermal, and mechanical properties, which can be attributed to the thermally stable AA NPs, the electrically conductive CNFs, which have a high tensile strength, and the uniform dispersion of AA-ACFs/CNFs in the cross-linked polymeric matrix of PP, MAH, and PEG. The production method described in this study is novel and simple, and the resulting nanocomposite may potentially be used as a battery separator and in structural materials. © 2015 Society of Plastics Engineers.
Hood A.R.,Indian Institute of Technology Kanpur |
Saurakhiya N.,DST Unit on Nanosciences |
Deva D.,DST Unit on Nanosciences |
Sharma A.,Indian Institute of Technology Kanpur |
And 3 more authors.
Materials Science and Engineering C | Year: 2013
This study describes the development of a novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers (CNFs) are grown on activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Cu and Fe as the metal catalysts. The transition metal-fiber composite is used as the working electrode of a biosensor applied to detect glucose in liquids. In such a bi-nanometal-grown multi-scale web of ACF/CNF, Cu nanoparticles adhere to the ACF-surface, whereas Fe nanoparticles used to catalyze the growth of nanofibers attach to the CNF tips. By ultrasonication, Fe nanoparticles are dislodged from the tips of the CNFs. Glucose oxidase (GOx) is subsequently immobilized on the tips by adsorption. The dispersion of Cu nanoparticles at the substrate surface results in increased conductivity, facilitating electron transfer from the glucose solution to the ACF surface during the enzymatic reaction with glucose. The prepared Cu-ACF/CNF/GOx electrode is characterized for various surface and physicochemical properties by different analytical techniques, including scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), BET surface area analysis, and transmission electron microscopy (TEM). The electrochemical tests show that the prepared electrode has fast response current, electrochemical stability, and high electron transfer rate, corroborated by CV and calibration curves. The prepared transition metal-based carbon electrode in this study is cost-effective, simple to develop, and has a stable immobilization matrix for enzymes. © 2013 Elsevier B.V.
Wang X.,University of Connecticut |
Yan J.,University of Connecticut |
Yan J.,University of Connecticut Health Center |
Yan J.,Center for Environmental science and Engineering
Computer Methods and Programs in Biomedicine | Year: 2011
Observing recurrent event processes at discrete, possibly random times produces panel count data. Modeling panel count data is challenging because the event process may be associated with the observation pattern and censoring time. Various methods have been proposed to fit flexible semiparametric regression models, but no software is available to practitioners. We develop an R package spef that fits semiparametric regression models for panel count data. Existing methods in the literature are implemented as well as our recently developed estimating equations approach. Some of the implemented methods allow informative observation and censoring scheme. The package usage is illustrated with a well-known bladder tumor data set. © 2010 Elsevier Ireland Ltd.