02308nas a2200241   4500008004100000022001400041245009600055210006900151260007300220300001000293490000800303520143000311653001301741653002301754653002401777653002701801653002001828100002701848700002201875700002001897700002201917856012701939       2011                        eng d  a0011-916400aPoly(acrylonitrile) based ultrafiltration membranes: optimization of preparation parameters0 aPolyacrylonitrile based ultrafiltration membranes optimization o  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV  a46-530 v2823 a<p>Supported ultrafiltration (UF) membranes based on poly(acrylonitrile) were prepared while varying crucial parameters responsible for controlling membrane porosity, viz.; polymer concentration, solvent and additives in the dope solution. Insight into membrane porosity and morphology was obtained by water flux, solute rejection, bubble point, pore size distribution, SEM and AFM analyses. It was found that merely increasing polymer concentration does not necessarily reduce pore size of membranes. Among four solvents used for the dope solution preparation, N-methyl pyrrolidone was found to offer membranes with optimal combination of flux and rejection of various solutes. Some of the PAN(17) (17% w/w PAN concentration in the dope solution) membranes prepared using organic acid as the additive (citric acid, tartaric acid or maleic acid) offered 1.2-1.7 times higher flux than the membrane prepared using inorganic salt, ZnCl2 as an additive. The porosity of PAN(17) membrane prepared using CA as an additive was larger as compared to membrane prepared using ZnCl2 as an additive. Atomic force microscopy (AFM) analysis of this membrane exhibited higher surface roughness as compared to the ZnCl2 based membrane. Both these membranes exhibited bacteria (E. Coli) log reduction value (LRV) of at least 6; depicting applicability of these membrane for water disinfection. (C) 2011 Elsevier B.V. All rights reserved.</p>10aAdditive10aBacteria rejection10aPoly(acrylonitrile)10aPore size distribution10aUltrafiltration1 aLohokare, Harshada, R.1 aBhole, Yogesh, S.1 aTaralkar, Suyog1 aKharul, Ulhas, K.  uhttps://library.ncl.res.in/content/polyacrylonitrile-based-ultrafiltration-membranes-optimization-preparation-parameters-002385nas a2200205   4500008004100000022001400041245010100055210006900156260000900225490000700234520164100241653001301882653003101895653002201926653003001948653003501978100002502013700001702038856012402055       2024                        eng d  a1861-472800aRole of aromatic alcohol additives on asymmetric organocatalysis reactions: insights from theory0 aRole of aromatic alcohol additives on asymmetric organocatalysis  cFEB 0 v193 a<p>
	The presence of an aromatic additive has been seen to enhance, often significantly, the enantioselectivity and yield in asymmetric organocatalysis. Considering their success across a dizzying range of organocatalysts and organic transformations, it would seem unlikely that a common principle exists for their functioning. However, the current investigations with DFT suggest a general principle: the phenolic additive sandwiches itself, through hydrogen bonding and pi &amp; sdot;&amp; sdot;&amp; sdot;pi stacking, between the organocatalyst coordinated electrophile and nucleophile. This is seen for a wide range of experimentally reported systems. That such complex formation leads to enhanced stereoselectivity is then demonstrated for two cases: the cinchona alkaloid complex (BzCPD), catalysing thiocyanation (2-naphthol additive employed), as well as for L-pipecolicacid catalysing the asymmetric nitroaldol reaction with a range of nitro-substituted phenol additives. These findings, indicating that dual catalysis takes place when phenolic additives are employed, are likely to have a significant impact on the field of asymmetric organocatalysis. The current DFT based study, on a wide range of organocatalysis systems, reveals a general principle by which phenolic additives influence asymmetric organocatalysis reactions. It is shown that the phenolic additive forms a sandwich complex, through hydrogen bonding and pi &amp; sdot;&amp; sdot;&amp; sdot;pi stacking interactions, with the organocatalyst coordinated electrophile and nucleophile, and enhances the enantioselectivity of the system as a result. image</p>
10aAdditive10aAsymmetric Organocatalysis10aCinchona Alkaloid10aDensity functional theory10aEnantioselective Thiocyanation1 aBanerjee, Subhrashis1 aVanka, Kumar  uhttps://library.ncl.res.in/content/role-aromatic-alcohol-additives-asymmetric-organocatalysis-reactions-insights-theory