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[en] A coarse-grained (CG) model is developed for the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM), using a hybrid top-down and bottom-up approach. Nonbonded parameters are fit to experimental thermodynamic data following the procedures of the SDK (Shinoda, DeVane, and Klein) CG force field, with minor adjustments to provide better agreement with radial distribution functions from atomistic simulations. Bonded parameters are fit to probability distributions from atomistic simulations using multi-centered Gaussian-based potentials. The temperature-dependent potentials derived for the PNIPAM CG model in this work properly capture the coil–globule transition of PNIPAM single chains and yield a chain-length dependence consistent with atomistic simulations
[en] Because of the beneficial effect of a trifluoromethyl group on the biological properties of bioactive compounds on the one hand and the versatile synthetic potential of β-lactams on the other hand, 4-CF3-β-lactams comprises interesting entities for the preparation of a large variety of CF3-substituted nitrogen-containing target structures with promising biological characteristics. In this review, we present an overview of different building block approach-based routes toward the synthesis of 4-(trifluoromethyl)azetidin-2-ones and the application of the “β-lactam synthon method” for the synthesis of a diverse set of (a)cyclic CF3-substituted molecules by means of ring-opening and ring-transformation reactions. Graphical abstract: .
[en] In view of the scale up of a batch reactor for super absorbent polymer (SAP), a dynamic mathematical model of a commercial scale batch reactor was developed with mass balance, energy balance, and complex polymerization kinetics. The kinetic parameters of the polymerization were estimated on the basis of the established mathematical model and reference data. Simulation results were validated with less than 10% marginal error compared with reference data. A case study was executed in terms of dynamic simulation for eight different initial concentrations of initiator and monomer to analyze the influence of initial concentration and predict the operation condition for desired product. The results were compared with various reference data, and good agreement was achieved. From the results, we argue that the methodology and results from this study can be used for the scale up of a polymerization batch reactor from the early stage of design.
[en] To determine the prevalence of Amp C beta lactamases in urinary isolates of Escherichia coli (E. coli), and to evaluate and compare different phenotypic methods for its detection in a cost effective way. Study Design: Descriptive study. Place and Duration of Study: Department of Microbiology, Combined Military Hospital Lahore Pakistan, from Jan 2016 to Jun 2016. Material and Methods: Modified Three Dimensional Test (M3DT) taken as Gold standard, Modified Hodge Test (MHT) (Cefoxitin), Nitrocephin test and three screening strategies for the detection of Amp C Beta-lactamases were tested on urinary isolates of E. coli collected during a period of 06 months. Results: Modified Hodge Test, was found to be simple, highly specific and sensitive in detecting these enzyme producers. Collectively these tests detected 45.07% of E. coli to be Amp C producers. Conclusion: Each of the three tests can be used as an acceptable phenotypic confirmatory tool when Amp C production in E. coli is suspected. (author)
[en] Published data on the use of cyanoacetamides, cyanothio- and -selenoacetamides in fine organic synthesis and the prospects of application of these compounds in combinatorial synthesis are analysed and generalised. The bibliography includes 653 references.