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A nuclease activity has been purified from the nuclei-kinetoplast fraction of Leishmania. This enzyme, termed endonuclease M (Endo M), is shown by electrophoresis in a denaturing polyacrylamide gel to be associated with a single polypeptide of molecular mass 52 kDa. Physical analysis of the enzyme indicates that it has a sedimentation coefficient S20,w of 4.5S, a Stoke's radius of 32.5 A, and a native molecular mass of 53 kDa. The final Mono Q purified Endo M possesses both DNase and RNase activities. It acts as an endonuclease by introducing random single-stranded nicks into the supercoiled DNA molecules, that often leads to its linearization due to nicking at the opposite strands, and subsequent degradation of the DNA with further incubation. Single-stranded DNA is twice preferred to double-stranded DNA as substrate. Single-stranded RNA is also degraded rapidly and is competitive as a substrate with single-stranded DNA. RNA:DNA hybrids, however, are largely resistant to the Endo M digestion. 相似文献
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Elias Martinez-Hernandez Grant Campbell Jhuma Sadhukhan 《Chemical Engineering Research and Design》2013
The selection of product portfolios, processing routes and the combination of technologies to obtain a sustainable biorefinery design according to economic and environmental criteria represents a challenge to process engineering. The aim of this research is to generate a robust methodology that assists process engineers to conceptually optimise the environmental and economic performances of biorefinery systems. A novel economic value and environmental impact (EVEI) analysis methodology is presented in this paper. The EVEI analysis is a tool that emerges from the combination of the value analysis method for the evaluation of economic potential with environmental footprinting for impact analysis. The methodology has been effectively demonstrated by providing insights into the performance of a bioethanol plant as a case study. The systematisation of the methodology allowed its implementation and integration into a computer-aided process engineering (CAPE) tool in the spreadsheet environment. 相似文献
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Poly(ethylene oxide)‐g‐gellan polysaccharide nanocarriers for controlled gastrointestinal delivery of simvastatin 下载免费PDF全文
Herein, a novel gellan polysaccharide‐based amphiphilic copolymer was synthesized for the development of simvastatin‐loaded micellar nanoparticles. The nanoparticles were explored for their controlled drug release and improved pharmacodynamic potentials. The copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The onset of copolymer micellization was detected by fluorescence spectroscopy. Simvastatin was loaded into micellar particles by solvent evaporation method and the particles were then characterized by microscopic and light scattering techniques. The physical state of drug was studied by X‐ray diffraction analysis. Pharmacodynamic assessment of the micellar preparations was done on rabbit models. The copolymer formed micellar nanoparticles in water. Critical micellar concentration was 9.12mg/l. The micellar particles (426.8–912.6nm) entrapped a maximum of 18.86% drug. Higher negative zeta potential indicated physical stability of micellar systems. A simple diffusion mechanism was operative in the event of comparatively faster drug release in pH6.8 phosphate buffer solution. No significant drug‐copolymer interaction was traced by FTIR spectroscopy. The amorphization of drug into micellar particles reduced LDL‐cholesterol level by ~45% in hyperlipidemic rabbits and this was about 2.5 times higher than pure drug dispersion. Copolymer micellar nanoparticles of simvastatin could control cholesterol level in hyperlipidemic rabbits and thus had potential in drug delivery applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42399. 相似文献
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Bikash Sadhukhan Naba Kumar Mondal Soumya Chattoraj 《Clean Technologies and Environmental Policy》2014,16(6):1015-1025
In this study, response surface methodology (RSM) was employed for the removal of methylene blue (MB) from aqueous solution using neem (Azadirachta indica) bark dust (NBD) as a bioadsorbent. The influence of various process parameters namely initial concentration (500–1,000 mg L?1), bioadsorbent dose [0.20–1.50 g (100 mL)?1], pH (5–12), and stirring rate (250–650 rpm) was taken as an input parameter. A total of 29 biosorption experimental runs were carried out employing the detailed conditions designed by RSM based on the Box–Behnken design (BBD). Response surface plots were studied to determine the interaction effects of main factors and optimum conditions of process. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination (R 2) value of 0.9760 and model F value of 40.68. The predicted R 2 value is 0.8979. In addition, results reported in this research demonstrated the feasibility of employing NBD as bioadsorbent for MB removal. 相似文献
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S. Sarkar A. Chourasia S. Maji S. Sadhukhan S. Kumar B. Adhikari 《Bulletin of Materials Science》2006,29(5):475-484
For tissue engineering purpose two gelatin based polyester urethane scaffolds of different compositions were prepared from
lactic acid, polyethylene glycol 400 (PEG 400) and characterized by FTIR, XRD for their mechanical and morphological properties
using SEM and optical microscopic analyses. Degradation and swelling studies of gelatin based polyester urethane scaffolds
in phosphate buffer saline (PBS) were performed. Human keratinocyte cells were cultured within these scaffolds, which showed
good cell adherence and proliferation. 相似文献
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There has been considerable interest, both academic and industrial, in developing synthesis processes for making polymeric nanoparticles. Our effort relied on the nanoassembly concepts of block macromolecules in solutions to prepare particles with a hard core made of crosslinked plastics and a soft shell made of low T(g) elastomer. By a suitable variation of the composition, polymer molecular weight and solute concentration, we were able to produce spherical, ellipsoidal, cylindrical, and chain-like nanoparticles. Under microscopes, the chain-like nanoparticles displayed very rich conformational features in diluted and dense states. Our observation on the conformation characters of the nanochains in 3D diluted state agreed well with the proposition of the self-avoid coil model. However, in 2D dense state, our observation on the nanochains appeared to be in contradiction with the segregated globule model proposed by de Gennes. 相似文献
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Mriganka Sadhukhan Manas Kumar Kundu Tanmay Bhowmik Sudip Barman 《International Journal of Hydrogen Energy》2017,42(15):9371-9383
Finding efficient electrocatalyst for oxidation of small organic molecules such as methanol (CH3OH), formic acid (HCOOH), formaldehyde (HCHO) etc. is essential for the development of their respective direct fuel cells. We report here highly dispersed platinum nanoparticles (PtNPs) on carbon nitride (CNx) were successfully synthesized by the ultrasound mediated sodium borohydride reduction of H2PtCl6 in presence of CNx nanosheets. This platinum–carbon nitride (Pt/CNx) composite exhibited superior electrocatalytic activity towards oxidation of CH3OH, HCOOH and HCHO in acid media. The mass activity, onset potential, tolerance to carbon monoxide (CO) poisoning and long term durability for the catalytic oxidation of CH3OH, HCOOH, HCHO on Pt/CNx catalyst in acid media is much higher than that of commercial Pt/C catalyst. The mass activity of Pt/CNx catalyst at ~0.64 V (forward scan) is 310 mA/mgPt which is 2.7 time higher than that of commercial Pt/C for methanol oxidation. The electrooxidation of HCOOH on Pt/CNx occurs via dual mechanism with greatly enhanced oxidation through dehydrogenation pathway in comparison with commercial Pt/C. The mass activity on Pt/CNx at 0.3 V (vs. NHE) is 25 times higher than that of Pt/C for oxidation of HCOOH. The superior catalytic activity and durability of this Pt/CNx catalyst can be attributed to high dispersion of PtNPs and strong catalyst support interaction. 相似文献
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Kok Siew NgJhuma Sadhukhan 《Biomass & bioenergy》2011,35(7):3218-3234
The techno-economic potential of the UK poplar wood and imported oil palm empty fruit bunch derived bio-oil integrated gasification and Fischer-Tropsch (BOIG-FT) systems for the generation of transportation fuels and combined heat and power (CHP) was investigated. The bio-oil was represented in terms of main chemical constituents, i.e. acetic acid, acetol and guaiacol. The compositional model of bio-oil was validated based on its performance through a gasification process. Given the availability of large scale gasification and FT technologies and logistic constraints in transporting biomass in large quantities, distributed bio-oil generations using biomass pyrolysis and centralised bio-oil processing in BOIG-FT system are technically more feasible. Heat integration heuristics and composite curve analysis were employed for once-through and full conversion configurations, and for a range of economies of scale, 1 MW, 675 MW and 1350 MW LHV of bio-oil. The economic competitiveness increases with increasing scale. A cost of production of FT liquids of 78.7 Euro/MWh was obtained based on 80.12 Euro/MWh of electricity, 75 Euro/t of bio-oil and 116.3 million Euro/y of annualised capital cost. 相似文献