Search results for "Anion"

Perfluoro-1,1′-biphenyl and perfluoronaphthalene and their derivatives as π-acceptors for anions

2015

Addition of anions to perfluorinated 1,1′-biphenyl 1 or naphthalene 2 results in a shift of the 19F NMR signals. However, any specific interaction cannot be assigned to this effect. In order to study the interaction in more detail, the salt derivatives 3 and 4 were prepared and studied by single crystal X-ray diffraction revealing weak anion–π interactions in the solid state.

On complete set of solutions for polynomial matrix equations

1990

Abstract In this paper we introduce the concept of co-solution of a polynomial matrix equation which permits us to obtain necessary and sufficient conditions so that a set of solutions be a complete set.

Zur kinetik der anionischen polymerisation von methyl-methyacrylat in tetrahydrofuran bei −75°C

1973

Die anionische Polymerisation von Methylmethacrylat (MMA) in Tetrahydrofuran (THF) verlauft bei −75°C mit Cumylcasium bzw. oligomerem α-Methylstyrylcasium als Initiatoren ohne erkennbare Nebenreaktionen analog der anionischen Polymerisation von unpolaren Monomeren in atherischen Losungsmitteln. Als Beweis wird hauptsachlich die enge Molekulargewichtsverteilung der unter diesen Bedingungen hergestellten Polymethylmethacrylate angefuhrt. Bei −75°C betragen die Geschwindigkeitskonstanten fur die Monomeranlagerung an das Ionenpaar kw(±) = 80 dm3 mol−1 s−1 und an das freie Anion etwa kw(−) ≈ 6 · 104 dm3 mol−1 s−1. Leitfahigkeitsmessungen ergeben, das die Dissoziationskonstante des Polymethylmeth…

1992

The kinetics and the molecular weight distributions (MWD) in the anionic polymerization of tert-butyl acrylate (tBuA) in tetrahydrofuran at 23 ± 3°C were investigated. Tert-butyl α-lithioisobutyrate (tBiB-Li) was used as the initiator in the absence and presence of the additives lithium chloride and lithium tert-butoxide (tBuOLi). A flow tube reactor was used which allowed very rapid mixing of reagents, within milliseconds. The polymerization is extremely fast, half-lives being 0,01 s for the system without additive, 0,05 s for LiCl and 3 s for tBuOLi as an additive. The rate of termination was estimated from the strong UV absorption of the enolized β-oxoester end group formed. The number-a…

Flexible power converters for the fault tolerant operation of Micro-Grids

2010

The progressive penetration level of Distributed Generation (DG) is destined to cause deep changes in the existing distribution networks no longer considered as passive terminations of the whole electrical system. A possible solution is the realization of small networks, namely the Micro-Grids, reproducing in themselves the structure of the main production and distribution of the electrical energy system. In order to gain an adequate reliability level of the microgrids the individuation and the management of the faults with the goal of maintaining the micro-grid operation (fault tolerant operation) is quite important. In the present paper flexible power converters and a companion control al…

Desulfurization: Critical step towards enhanced selenium removal from industrial effluents

2017

Abstract Selenium (Se) removal from synthetic solutions and from real Flue Gas Desulfurization (FGD) wastewater generated by a coal-fired power plant was studied for the first time using a commercial iron oxide impregnated strong base anion exchange resin, Purolite ® FerrIX A33E. In synthetic solutions, the resin showed high affinity for selenate and selenite, while sulfate exhibited a strong competition for both oxyanions. The FGD wastewater investigated is a complex system that contains Se (∼1200 μg L −1 ), SO 4 2− (∼1.1 g L −1 ), Cl − (∼9.5 g L −1 ), and Ca 2+ (∼5 g L −1 ), alongside a broad spectrum of toxic trace metals including Cd, Cr, Hg, Ni, and Zn. The resin performed poorly again…

Remediation of Solutions Containing Oxyanions of Selenium by Ultrafiltration: Study of Rejection Performances with and without Chitosan Addition

2017

Among the various technical options for removing ionic contaminants from wastewaters, membrane processes and especially their coupling with polymer addition have been proven to provide worthwhile prospects for the removal of metal cations. Nevertheless, their use for the removal of anionic pollutants such as oxyanions has been little studied in the literature. In the present work, the rejection of oxyanions forms of Se(IV) and Se(VI) by tight ultrafiltration membranes was deeply investigated under various experimental conditions. This paper aims at understanding the mechanisms governing oxyanion rejection and determining the potential ways to improve performances. It is first shown that sel…

Extensive molecular analysis of patients bearing CFTR-related disorders.

2012

Cystic fibrosis transmembrane conductance regulator (CFTR)–related disorders (CFTR-RDs) may present with pancreatic sufficiency, normal sweat test results, and better outcome. The detection rate of mutations is lower in CFTR-RD than in classic CF: mutations may be located in genes encoding proteins that interact with CFTR or support channel activity. We tested the whole CFTR coding regions in 99 CFTR-RD patients, looking for gene mutations in solute carrier (SLC) 26A and in epithelial Na channel (ENaC) in 33 patients who had unidentified mutations. CFTR analysis revealed 28 mutations, some of which are rare. Of these mutations, RT-PCR demonstrated that the novel 1525-1delG impairs exon 10 s…

Involvement of carboxyl groups in chloride transport and reversible DIDS binding to band 3 protein in human erythrocytes

2011

AbstractNoncovalent DIDS binding to Band 3 (AE1) protein in human erythrocyte membranes, modified by non-penetrating, water soluble 1-ethyl-3-(4-azonia-4,4-dimethylpentyl)-carbodiimide iodide (EAC), was studied at 0°C in the presence of 165 mM KCl. Under experimental conditions applied up to (48 ± 5) % of irreversible chloride self-exchange inhibition was observed. The apparent dissociation constant, KD, for “DIDS-Band 3” complex, determined from the chloride transport experiments, was (34 ± 3) nM and (80 ± 12) nM for control and EAC-treated resealed ghosts, respectively. The inhibition constant, Ki, for DIDS was (35 ± 6) nM and (60 ± 8) nM in control and EAC-treated ghosts, respectively. T…

Metal-bound Nitrate Anion as an Acceptor for Halogen Bonds in mono-Halopyridine-Copper(II) nitrate Complexes

2019

Fifteen n-halopyridine-Cu(NO3)2 complexes (n = 2, 3, 4) obtained from two different solvents, acetonitrile and ethanol, are investigated for C–X···O–N halogen bonds (XBs) in the solid state by single and powder X-ray diffraction. The nitrate anions bind copper(II) via anisobidentate modes and one of three oxygens act as an XB acceptor to halogens on the core pyridine rings. The N-metal coordination activates the electron-deficient π-system and triggers even C2- and C4-chlorines in the corresponding [Cu(2-chloropyridine)2(NO3)2] and [Cu(4-chloropyridine)2(NO3)2(ACN)] complexes to form short C–Cl2/Cl4···O–N halogen bonds. Notably, the C2–Cl2···O–N XBs with a normalized XB distance parameter (…