نتایج جستجو برای: transition metal ion
تعداد نتایج: 619110 فیلتر نتایج به سال:
An overview is presented of classic and more recent applications of liquid chromatography for the analysis of metal species. The different approaches involving ion-exchange, ion-pair, and chelation separation mechanisms are discussed as well as the new philosophy of simply removing interferents before specific detections of metal ions (alkali and alakaline earths, rare earths, heavy and transit...
Spectral studies of metal phthalocyanines are invaluable in the understanding of the electronic processes in phthalocyanines. The electronic overlap between the centrally substituted metal ion and the phthalocyanine ring can be observed from charge transfer (CT) transition between the central metal ion and the phthalocyanine ligand and point to extensive coupling between the two electronic syst...
The basic approach in the microscopic theory of binary metal systems has been developed. The electron-ion model Hamiltonian with nonlocal manyparticle interactions was obtained using the statistical operator averaging for the electron-nuclear model over the localized electron states. The role of orthogonalization and exchange effects on the formation of electron-ion interactions is investigated...
abstract ion selective electrodes (ises) are electrochemical sensors that respond selectivity to the activity of ionic species. an ion-selective electrode is an electrochemical device that uses a thin selective membrane or film as the recognition element, and is an electrochemical half-cell equivalent to other half-cells of the zeroth (inert metal in a redox electrolyte). in common methods o...
Diverse organophosphate hydrolases have convergently evolved the ability to hydrolyse man-made organophosphates. Thus, these enzymes are attractive model systems for studying the factors shaping enzyme functional evolution. Methyl parathion hydrolase (MPH) is an enzyme from the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphate, aryl ester and lactone substrates. ...
Transition metals are involved in essential biological processes in plants since they are cofactors of metalloproteins and also act as regulator elements. Particularly, plant chloroplasts are organelles with high transition metal ion demand because metalloproteins are involved in the photosynthetic electron transport chain. The transition metal requirement of photosynthetic organisms greatly ex...
The transport of Fe(2+) and other divalent transition metal ions across the intestinal brush border membrane (BBM) was investigated using brush border membrane vesicles (BBMVs) as a model. This transport is an energy-independent, protein-mediated process. The divalent metal ion transporter of the BBM is a spanning protein, very likely a protein channel, that senses the phase transition of the B...
A new polyvinyl choloride (PVC) membrane sensor for cerium (III) was prepared based on 4,13-didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (kryptofix22DD) as an ionophore. The sensor exhibites a linear concentration range of 1.0×10-6to 1.0×10-1M, with a Nernstian slope of 18.0±1.0 mV/decade, and a detection limit of 9.7×10-7M. It has a fast response time (5 s) and can be used for two mont...
Two new symmetrical Schiff bases have been prepared by the condensation of ethylenediamine and two benzaldehyde derivatives, 2-hydroxybenzaldehyde and 2,4-dimethoxybenzaldehyde. The electronic transitions within these Schiff bases molecules in chloroform solvent have been investigated by UV-Vis spectroscopy. The 1H NMR and IR spectra were studied and assigned to related groups. Furthermore,...
Biological membranes are complex assemblies of lipids and proteins that serve as platforms for cell signaling. We have developed a novel method for measuring the structure and dynamics of the membrane based on fluorescence resonance energy transfer (FRET). The method marries four technologies: (1) unroofing cells to isolate and access the cytoplasmic leaflet of the plasma membrane; (2) patch-cl...
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