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31.
32.
Polyacrylonitrile (PAN), is an important base polymer to cast porous membranes. In this work, a detailed study of the effects of molecular weight of PAN homopolymer and its concentration on the cast membrane has been undertaken. The effects of molecular weight of additive polyethylene glycol (PEG) and its concentration have also been investigated. The membranes are cast using dimethyl formamide as solvent using phase inversion technique. They are characterized in terms of porosity, water permeability, molecular weight cut off, average pore diameter, contact angle, and tensile strength at breaking point. Fourier transform infrared spectroscopy and scanning electron microscopy are used to characterize the chemical and morphological changes of the membrane surface. Further studies have been considered to evaluate the antifouling property of various membranes using filtration of bovine serum albumin solution. Membrane modified by PEG 400 membrane shows an improved separation performance and antifouling characteristics. POLYM. ENG. SCI., 54:2375–2391, 2014. © 2013 Society of Plastics Engineers 相似文献
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Nitroarenes as Antitubercular Agents: Stereoelectronic Modulation to Mitigate Mutagenicity 下载免费PDF全文
Dr. Sudhir Landge Dr. Vasanthi Ramachandran Dr. Anupriya Kumar Dr. João Neres Kannan Murugan Dr. Claire Sadler Dr. Mick D. Fellows Vaishali Humnabadkar Dr. Prakash Vachaspati Dr. Anandkumar Raichurkar Sreevalli Sharma Sudha Ravishankar Supreeth Guptha Dr. Vasan K. Sambandamurthy Dr. Tanjore S. Balganesh Dr. Bheemarao G. Ugarkar Dr. V. Balasubramanian Dr. Balachandra S. Bandodkar Dr. Manoranjan Panda 《ChemMedChem》2016,11(3):331-339
Nitroarenes are less preferred in drug discovery due to their potential to be mutagenic. However, several nitroarenes were shown to be promising antitubercular agents with specific modes of action, namely, nitroimidazoles and benzothiazinones. The nitro group in these compounds is activated through different mechanisms, both enzymatic and non‐enzymatic, in mycobacteria prior to binding to the target of interest. From a whole‐cell screening program, we identified a novel lead nitrobenzothiazole (BT) series that acts by inhibition of decaprenylphosphoryl‐β‐d ‐ribose 2′‐epimerase (DprE1) of Mycobacterium tuberculosis (Mtb). The lead was found to be mutagenic to start with. Our efforts to mitigate mutagenicity resulted in the identification of 6‐methyl‐7‐nitro‐5‐(trifluoromethyl)‐1,3‐benzothiazoles (cBTs), a novel class of antitubercular agents that are non‐mutagenic and exhibit an improved safety profile. The methyl group ortho to the nitro group decreases the electron affinity of the series, and is hence responsible for the non‐mutagenic nature of these compounds. Additionally, the co‐crystal structure of cBT in complex with Mtb DprE1 established the mode of binding. This investigation led to a new non‐mutagenic antitubercular agent and demonstrates that the mutagenic nature of nitroarenes can be solved by modulation of stereoelectronic properties. 相似文献
35.
Hang Liu Xiaofeng Zhao Yuancheng Teng Yuxiang Li Xiayu Zheng Shanlin Wang Lang Wu Pritam Kumar Panda Rajeev Ahuja 《Journal of the American Ceramic Society》2022,105(7):4974-4985
LnPO4 · 0.667H2O rhabdophane has been considered as a potential material for the precipitation of actinides from radioactive waste liquid, owing to its outstanding characteristics of high actinide bearing and easy synthesis in acid solutions. However, a comprehensive understanding of the actinide occupation and the precipitation response of rhabdophane to remove actinides has yet to be established. In this study, the effect of ions concentration and pH values on the detailed precipitation reaction of CexNd1-xPO4 · 0.667H2O rhabdophane in acid solutions are systematically investigated. Some specific issues such as structural distortion and flexibility, and occupation mechanism are discussed by combining with experiments and density functional theory (DFT) calculation. The results reveal that ions concentration and pH values have a significant impact on the crystallization nucleation step before 12 h. The obtained removal rate of Nd3+ is more than 99% in pH 1–5 solutions with the ions concentration of 0.05–0.1 mol/L. Moreover, incorporating Nd in CePO4 · 0.667H2O rhabdophane will easily result in the lattice distortion in b-axis. DFT calculation and X-ray photoelectron spectroscopy (XPS) results reveal that Nd is preferentially incorporated in nonhydrated site to form a weaker binding energy of NdO8 polyhedron. 相似文献
36.
Sandeep Panda Pradeep Chandra Rout Chinmaya Kumar Sarangi Srabani Mishra Nilotpala Pradhan Umaballav Mohapatra Tondepu Subbaiah Lala Behari Sukla Barada Kanta Mishra 《Korean Journal of Chemical Engineering》2014,31(3):452-460
Bioleaching studies for chalcopyrite contained ball mill spillages are very scarce in the literature. We developed a process flow sheet for the recovery of copper metal from surface activated (600 °C, 15 min) ball mill spillage through bio-hydrometallurgical processing route. Bioleaching of the activated sample using a mixed meso-acidophilic bacterial consortium predominantly A. ferrooxidans strains was found to be effective at a lixiviant flow rate of 1.5 L/h, enabling a maximum 72.36% copper recovery in 20 days. Mineralogical as well as morphological changes over the sample surface were seen to trigger the bioleaching efficiency of meso-acidophiles, thereby contributing towards an enhanced copper recovery from the ball mill spillage. The bio-leach liquor containing 1.84 g/L Cu was purified through solvent extraction using LIX 84I in kerosene prior to the recovery of copper metal by electrowinning. Purity of the copper produced through this process was 99.99%. 相似文献
37.
Abhishek Dhar Abhishek Dutta Pushan Sharma Biswajit Panda 《Chemical Engineering Communications》2017,204(12):1341-1356
In the present work, first, the reference catalyst super acidic nanostructured sulfated zirconia (SZ) and super acidic nanostructured aluminum chloride impregnated sulfated zirconium oxides in mole ratios of Zr4+:Al3+ as 2:1 (ACSZ-1), 1:1 (ACSZ-2), and 1:2 (ACSZ-3) were synthesized by a simple precipitation method. The catalytic performance of these four catalysts were evaluated during the isomerization of n-hexane, n-heptane, and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions. ACSZ-2 shows high activity toward isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The reference catalyst SZ was proved to be less effective compare to the other three synthesized ACSZ catalysts. Ammonia-temperature-programmed desorption of these two materials ensures that the super acidity of ACSZ-2 is higher than that of SZ. Atomic force microscopic and scanning electron microscopic pictures predict the nature of the surface of the catalysts. Transmission electron micrographic analysis indicates the presence of particle-bulks having average size 12–20?nm, presenting an amorphous nature and having no definite surface morphology of ACSZ-2. Fourier transform infrared provides an outline regarding different linkages and bond connectivities between atoms and groups in ACSZ-2 and SZ. After catalyst evaluation and characterization a probable reaction mechanism has been proposed theoretically. The reactivity and selectivity of ACSZ-2 and SZ as well as the order and activation energy of the isomerization reactions in presence of ACSZ-2 have been calculated. The use of ACSZ-2 is beneficial from the point of cost efficiency as well as its use is energy saving. 相似文献
38.
Ganapati D. Yadav Shashikant B. Kamble 《Clean Technologies and Environmental Policy》2009,11(4):447-457
Alkylation of aromatics catalyzed by solid acids constitutes a class of reactions of both academic and industrial importance.
Among alkylation reactions, isopropylation of aromatic compounds has attracted considerable attention. Use of propylene as
alkylating agent at very high temperatures leads to coke formation which results in deactivation of the catalyst. The use
of isopropanol (IPA) as an alkylating agent is attractive when propylene is not readily available. In situ dehydration of
IPA leads to prolonged activity since water of reaction suppresses coke formation. Further, IPA dehydration also generates
diisopropyl ether which itself is an excellent alkylating agent. Alkylation of mesitylene with propylene or IPA results in
the formation of 2-isopropyl-mesitylene (2-IPMT), which is almost extensively used as a precursor in a number of industrial
chemicals. This work covers the evaluation of clay-supported heteropolyacids and sulfated zirconia. A variety of solid acid
catalysts such as K-10 clay, sulfated zirconia, Filtrol-24, 20% w/w dodecatungstophosphoric acid (H3PW12O40, DTP) supported on K-10 montmorillonite clay and 20% w/w cesium substituted dodecatungstophosphoric acid (Cs2.5H0.5PW12O40, Cs-DTP) supported on K-10 montmorillonite clay were investigated for the liquid phase isopropylation of mesitylene to 2-IPMT
using IPA at much milder conditions vis-à-vis other catalysts reported so far. 20% w/w Cs-DTP/K-10 clay was found to be the
best catalyst which gives 98% conversion of limiting component, IPA and 98% selectivity towards the desired product, 2-IPMT
after 2 h of total reaction time. This catalyst could be reused without any further chemical treatment, eliminating the effluent
disposal problems. The reaction was carried out without using any solvent and the process subscribes to the principles of
green chemistry. The catalytic activity is in the following order: 20% w/w Cs-DTP/K-10 clay (most active) > 20% w/w DTP/K-10
clay > Filtrol-24 > Sulfated zirconia > K-10 clay (least active). The effect of various operating parameters and catalyst
reusability were also systematically investigated. A mathematical model was proposed to probe into the intricate reaction
kinetics and mechanism consistent with the experimental results. The reaction is free from any external mass transfer as well
as intraparticle diffusion limitations and is intrinsically kinetically controlled. An overall second order kinetic equation
was used to fit the experimental data, under the assumption that all the species are weakly adsorbed on the catalytic sites. 相似文献
39.
Subrata Panda Jean-Jacques Fundenberger Yajun Zhao Jianxin Zou Laszlo S. Toth Thierry Grosdidier 《International Journal of Hydrogen Energy》2017,42(35):22438-22448
While severe plastic deformation (SPD) on bulk samples has been widely applied for modifying the H-sorption properties, there has been little attention towards the use of SPD on powder materials. In this context, the aim of the present work was to compare the H-storage properties of high-pressure torsion (HPT) consolidated products obtained from two distinct Mg powder precursors: atomized micro-sized and condensed ultrafine powder particles. The results showed that the nature of the initial powder precursor had a pronounced effect on the H-sorption behavior. The HPT product obtained from the condensed ultrafine powder showed faster absorption kinetics than the consolidated product obtained from the atomized powder. However, the HPT product obtained from atomized powder could absorb more hydrogen and showed faster desorption kinetics corresponding to a lower activation energy. These results are discussed by taking into account the effectiveness of the HPT process to refine the grain sizes and differences in the dispersion of fine MgO oxide particles. 相似文献
40.
In this paper, an evolutionary multi-objective optimization approach is employed to design a static synchronous series compensator (SSSC)-based controller. The design objective is to improve the transient performance of a power system subjected to a severe disturbance by damping the multi-modal oscillations namely; local mode, inter-area mode and inter-plant mode. A genetic algorithm (GA)-based solution technique is applied to generate a Pareto set of global optimal solutions to the given multi-objective optimization problem. Further, a fuzzy-based membership value assignment method is employed to choose the best compromise solution from the obtained Pareto solution set. Simulation results are presented and compared with a PI controller under various disturbances namely; three-phase fault, line outage, loss of load and unbalanced faults to show the effectiveness and robustness of the proposed approach. 相似文献