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...

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...

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...

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...

Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short article describes properties of new additives in water-soluble metal working fluids for aluminum alloy materials. Many half esters or diesters were prepared from the reactions of higher alcohols with acid anhydrides. Interestingly, diesters of PTMG (tetrahydrofuran oligomer, MW = 650 and 1000) and...

objective(s):   metal nanoparticles (nps) offer a wide variety of potential applications in pharmaceutical sciences due to the unique advances in nanotechnology research. in this work, bimetal ag-au alloy nps were prepared and their combinations with other antibiotics were tested against staphylococcus aureus.   materials and methods: firstly, ag-au alloy nps with au/ag molar ratio of 1:1 was f...

OBJECTIVE The aims of the study are to assess the marginal accuracy of base metal and titanium alloy casting and to evaluate the effect of repeated ceramic firing on the marginal accuracy of base metal and titanium alloy castings. MATERIALS AND METHODS Twenty metal copings were fabricated with each casting material. Specimens were divided into 4 groups of 10 each representing base metal alloy...

AIMS The aims of this study were to investigate the influence of commercially pure titanium (PTi) and titanium-aluminum-vanadium (Ti-6Al-4V) alloys (TiA) on the final shade of low-fusing porcelain bonded to them and to compare the shade changes with those of three conventional metal-ceramic systems. METHODS AND MATERIALS A titanium casting unit was used to cast PTi and Ti-6Al-4V alloy specime...

introduction: evaluation of bonding in atomic level, by sem/eds analysis of si atoms, is an exact method for determination of bond strength of metal and porcelain. the purpose of this study was to evaluate the bond strength of one noble alloy and two base metal alloys with and without beryllium. methods and materials: six specimens of each alloy begostar, rexillium iii, wiron 99 (10×10×1mm dime...