نتایج جستجو برای: alkali metal

تعداد نتایج: 210259  

Journal: :Inorganic chemistry 2010
Simon M Humphrey Richard A Mole Richard I Thompson Paul T Wood

The hexaanion of mellitic acid, mel = (C(6)(CO(2))(6))(6-), links metal ions into extensively connected magnetic coordination polymers. Reaction of alkali metal mellitate salts, M(6)(mel) (M = K, Rb), with M'Cl(2) precursors (M' = Mn, Co, Ni) under mild (473 K) hydrothermal conditions yields an extensive family of isostructural 3-dimensional mixed alkali metal/transition metal polymers of gener...

Journal: :Physical chemistry chemical physics : PCCP 2016
F Zaccaria G Paragi C Fonseca Guerra

The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkal...

2012
Tatjana Šumanovac Ramljak Kata Mlinarić-Majerski Branimir Bertoša

A series of adamantane functionalized diaza-lariat ethers 1–6 have been prepared and alkali metal picrate extraction profiles determined. The ability of aza-crown ethers 1–6 to extract the alkali metal picrates was compared with that of diaza-18-crown-6 (7) and N,N '-dibenzodiaza-18-crown-6 (8). Na and K transport across bulk liquid membrane was also measured. The results of alkali metal cation...

2009
Dezső Boda Mónika Valiskó Douglas Henderson Bob Eisenberg Dirk Gillespie Wolfgang Nonner

A physical model of selective "ion binding" in the L-type calcium channel is constructed, and consequences of the model are compared with experimental data. This reduced model treats only ions and the carboxylate oxygens of the EEEE locus explicitly and restricts interactions to hard-core repulsion and ion-ion and ion-dielectric electrostatic forces. The structural atoms provide a flexible envi...

2003
A. ROTHSTEIN

K+ is a competitive inhibitor of the uptake of the other alkali metal cations by yeast. Rb+ is a competitive inhibitor of K+ uptake, but Li+, Na+, and Cs+ act like H+. At relatively low concentrations they behave as apparent noncompetitive inhibitors of K+ transport, but the inhibition is incomplete. At higher concentrations they inhibit the remaining K+ transport competitively. Ca++ and Mg++ i...

Journal: :The Journal of biological chemistry 1979
F Alvarado A Mahmood

The alkali-metal ions, Li+, Na+ and K+, exhibit complex pH-dependent effects on sucrase that seem to involve at least three separate types of mechanism and, perhaps, an equal number of specific metal-binding sites. In metal-free buffers, the alkali metals give mixed activating effects below pH 7 that involve: 1) Affinitytype (K-type) activation kinetics, where the apparent K,,, decreases as the...

2000
M. Hartmann P. Bergveld

Thin films of iron(W) hexacyanoferrate(I1) (Prussian Blue) were electrochemically deposited on interdigitated array (IDA) electrodes, yielding systems which can be considered as chemiresistors in sensing alkali metal ion concentrations in an adjacent electrolyte. This is due to the fact that the conductivity of the film being measured by a steady-state current on application of a voltage to the...

Journal: :Chemical communications 2015
Sahar Farmanesh Bryan G Alamani Jeffrey D Rimer

We show that alkali metals function as effective modifiers of calcium oxalate monohydrate (COM) crystallization wherein alkali-oxalate ion parings reduce the rate of crystal growth by as much as 60%. Our findings reveal a distinct trend in alkali metal efficacy that cannot be explained by colloidal theories or simple descriptors, such as ion size, but is consistent with a theoretical model that...

Journal: :Physical review letters 1996
Carlsson Claesson Lindgren Walldén

Alkali metals adsorbed on metal surfaces attract interest as prototype examples of simple chemisorption [1] and simple metal quantum well systems [2]. In spite of the numerous studies made the electronic structure is still rather poorly characterized. So far, observations of the filled states have been limited to the discrete states that may be formed by alkali metal valence electrons in the en...

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