New quaternary Plotkin constructions are given and are used to obtain new families of quaternary codes. The parameters of the obtained codes, such as the length, the dimension and the minimum distance are studied. Using these constructions new families of quaternary Reed-Muller codes are built with the peculiarity that after using the Gray map the obtained Z4-linear codes have the same paramete...

In analogy to the corresponding measures of pseudorandomness for quaternary sequences introduced by Mauduit and Sárközy (for m-ary sequences) we introduce the well-distribution measure and correlation measure of order k for sequences over F4. Using any fixed bijection from F4 to the set of complex fourth roots of unity, we analyze the relation of these pseudorandomness measures for sequences ov...

3,3-Disubstituted allylic boronic esters are not sufficiently reactive to react with ketones and imines. However, they can be converted into the corresponding borinic esters by the sequential addition of nBuLi and TFAA. These reactive intermediates possess the perfect balance between reactivity and configurational stability. Their enhanced reactivity allows the highly selective allylation of bo...

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...