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121.
The authors present a generalized theory of microphase separation for charged-neutral diblock copolymer melt. The stability limit of the disordered phase for salt-free melt has been calculated using random phase approximation (RPA) and self-consistent-field theory (SCFT). Explicit analytical free energy expressions for different classical ordered microstructures (lamellar, cylinder, and sphere) are presented. The authors demonstrate that the chemical mismatch required for the onset of microphase separation (chi*N) in charged-neutral diblock melt is higher and the period of ordered microstructures is lower than those for the corresponding neutral-neutral diblock system. Theoretical predictions on the period of ordered structures in terms of Coulomb electrostatic interaction strength, chain length, block length, and chemical mismatch between blocks are presented. SCFT has been used to go beyond the stability limit, where electrostatic potential and charge distribution are calculated self-consistently. Stability limits calculated using RPA are in perfect agreement with the corresponding SCFT calculations. Limiting laws for the stability limit and the period of ordered structures are presented and comparisons are made with an earlier theory. Also, transition boundaries between different morphologies have been investigated. 相似文献
122.
Treatment of petroleum refinery wastewater by ultrasound-dispersed nanoscale zero-valent iron particles 总被引:1,自引:0,他引:1
Petroleum refineries release wastewater, which is rich in organic pollutants and cannot be treated easily. This study presents the treatment of petroleum refinery wastewater using nanoscale zero valent iron (NZVI) in the presence of ultrasonication. NZVI characteristics were analyzed using SEM and XRD. The influence of NZVI dosage and initial pH on % chemical oxygen demand (COD) reduction was studied. From the results, it can be inferred that a dosage of 0.15 g/l and an initial pH are optimum for the effective degradation of effluents. The degradation data were found to follow first order kinetics. The results indicate that using NZVI in combination with ultrasonication is an efficient method for the treatment of petroleum refinery wastewater. 相似文献
123.
Sitthuraj Krishnaraj Manisekar Muthukumar Periasamy Viswanathamurthi Santhanam Sivakumar 《Transition Metal Chemistry》2008,33(5):643-648
The reactions of [RuHCl(CO)(B)(EPh3)2] (B = EPh3 or Py; E = P or As) and Schiff bases in 1:1 molar ratio led to the formation of [RuCl(CO)(EPh3)(B)(L)] (E = P or As; B = PPh3, AsPh3 or Py; L = Schiff base ligand). The new complexes have been characterized by analytical and spectroscopic (IR, electronic
and 1H NMR) data. They have been assigned an octahedral structure. The new complexes were found to catalyse the transfer hydrogenation
of ketones. 相似文献
124.
Dr. Nina Diaz Dr. Mingzhao Zhu Dr. Gunnar Ehrlich Ulrike Eggert Yazh Muthukumar Dr. Florenz Sasse Prof. Dr. Markus Kalesse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(16):4946-4952
The improved synthesis of the antitumor compound (+)‐tedanolide is described through an aldol coupling of bis‐ketone 7 . This modification shortens the synthetic steps in the endgame and provides rapid access to this biologically important natural product. Additionally, it serves as a probe in order to unravel the conformational effects that impede or enable its successful synthesis. Having this way access to des‐epoxy‐tedanolide, its biological characterization surprisingly unravelled the mode of action to resemble candidaspongiolide rather than deoxytedanolide. 相似文献
125.
Murugappan Muthukumar 《Macromolecular theory and simulations》1994,3(1):61-71
An explicit formula is derived for the electrophoretic mobility of a linear polyelectrolyte chain in terms of the molecular weight, Debye length and solvent quality. The nature of the crossover between different regimes as the salt concentration and molecular weight are varied is presented. The effect of chain statistics intermediate between the Gaussian and rodlike limits on the electrophoretic mobility is analysed for the first time. 相似文献