Four cubic compounds are reported that contain the supertetrahedral cluster [M(4)Sn(4)S(17)](10)(-) where M = Mn, Fe, Co, Zn. The cluster features a central quadruply bridging sulfide ion (mu(4)-S) that holds together four divalent M atoms in a tetrahedral arrangement. This core is capped with four tridentate [SnS(4)](4)(-) fragments to complete the structure.

Potassium channels have a very wide distribution of single-channel conductance, with BK type Ca(2+)-activated K(+) channels having by far the largest. Even though crystallographic views of K(+) channel pores have become available, the structural basis underlying BK channels' large conductance has not been completely understood. In this study we use intracellularly applied quaternary ammonium co...

it is a very short time that the quaternaries period in geology and physical geography's knowledge has occupied a very important place. during this period, the earth has suffered consecutive freezing that has been accompanied by tides and alternate erosion and sedimentation. sedimentary successions have recorded valuable evidence of changes with very accurate details. the study of these sedimen...

A new germanium(II) phosphate, sodium tetra-germanium tris-(phosphate), Na[Ge(4)(PO(4))(3)], has been synthesized by a solid-state reaction. The compound is isotypic with A[Sn(4)(PO(4))(3)] (A = Na, K, NH(4)). It features a [Ge(4)(PO(4))(3)](-) framework made up of GeO(3) pyramids and PO(4) tetra-hedra, which are linked by shared corners, yielding a three-dimensional structure. The crystal stud...

The title compound, C(18)H(24)I(2), has an adamantanoid structure with tetra-hedral cages having four C atoms lying on the same plane [(I-)C-C-C-C(-I) torsion angle = 0°]. The plane is extended by the two I atoms, each having a deviation of 1.0 (6) Å [C-C-C-I torsion angle = 178.9 (4)°]. The central C-C bond connecting the two quaternary carbons seems enlarged [1.593 (9) Å] in comparison to the...

Organocatalytic asymmetric Michael reactions of fluorinated nucleophiles with nitroolefins catalyzed by Cinchona alkaloid-derived thiourea catalysts generated the desired Michael products containing vicinal fluorinated quaternary and tertiary chiral centers with exceptional enantioselectivity.

A capillary electrophoretic method for resolving phenolic compounds found in grape seed extracts was developed using a quaternary ammonium salt as the main electrolyte solution. Seven polyphenols were separated and identified. The separation mechanism seems to involve association between quaternary ammonium cations and the polyphenols. Migration times roughly correlate with the size of the know...

Polymeric materials containing quaternary ammonium and/or phosphonium salts have been extensively studied and applied to a variety of antimicrobial-relevant areas. With various architectures, polymeric quaternary ammonium/phosphonium salts were prepared using different approaches, exhibiting different antimicrobial activities and potential applications. This review focuses on the state of the a...

Abstract This letter will clarify the fundamental properties of a quaternary neuron whose weights, threshold values, input and output signals are all quaternions, which is an extension of a usual real-valued neuron to quaternions. The main results of this letter are summarized as follows. A quaternary neuron has an orthogonal decision boundary. The 4-bit parity problem which cannot be solved wi...

Eubacterial and related single-stranded DNA-binding proteins (SSBs) exhibit considerable variability in their quaternary association in spite of their having the same tertiary fold. The variability involves differences in the orientation of dimers in the tetrameric molecule (or of two-domain subunits in the dimeric molecule) and that of monomers in each dimer. The presence of an additional stra...