A refinement of the equaclosure operator

A stronger version of a known property is shown to hold for the natural equaclosure operator on subquasivariety lattices.     

Determination of antiviral nucleoside analogues AM365 and AM188 in perfusate and bile of the isolated perfused rat liver using HPLC

Development, validation and application of an HPLC assay for new antiviral nucleoside analogues AM365 and AM188 in isolated perfused rat liver perfusate and bile were performed. An analytical column (Phenosphere-NEXT, 250 x 4.6 mm, C(18), 4 microm, Phenomenex) was used in tandem with a guard column (4 x 3 mm, C(18), Phenomenex) and operated at 25 degrees C. The mobile phase [methanol:10 mmol/L sodium orthophosphate buffer (pH 7.0), 15:85, v/v] was pumped at 1 mL/min. The signal from a diode array detector was collected from 190 to 300 nm. The chromatogram was processed at 220 and 252 nm for AM365 and AM188, respectively. The HPLC method was validated by six intraday and seven interday runs. Standard curves were linear in the range 0.125-8.00 microg/mL for AM365 and AM188, and the lower limit of quantification for AM365 and AM188 was 0.125 microg/mL. Mean interday precision and accuracy of IPL perfusate quality control samples were within 8.8%, and mean intraday precision and accuracy were within 13.1%. The assay has been successfully used in the study of metabolism and disposition of AM365 in the isolated perfused rat liver.     

A new look at the Jordan-Hölder theorem for semimodular lattices

We show that in a semimodular lattice L of finite length, from any prime interval we can reach any maximal chain C by an up- and a down-perspectivity. Therefore, C is a congruence-determining sublattice of L.     

Jónsson's contributions to lattice theory

Dedicated to Bjarni Jónsson on his 70th birthday     

Host-Guest Interactions of Inorganic Phosphates with the Copper(II) Complexes of the Hexaaza Macrocyclic Ligand 3,6,9,17,20,23-Hexaazatricyclo[23.3.1.1(11,15)]triaconta-1(29),11(30),12,14,25,27-hexaene

The host-guest interactions between ortho-, pyro-, and tripolyphosphate anions and the mono and dinuclear copper(II) complexes of the hexaaza macrocyclic ligand BMXD (3,6,9,17,20,23-hexaazatricyclo[23.3.1.1(11,15)]triaconta-1(29),11(30),12,14,25,27-hexaene) were investigated by potentiometric equilibrium methods. Ternary complexes are formed in aqueous solution as a result of coordinate bonding, hydrogen bond formation, and Coulombic attraction between the host and guest. Formation constants for all the species found are reported. The dinuclear copper(II) complexes of BMXD show strong selectivity for pyrophosphate ions in the presence of orthophosphate ions over the whole p[H] range; the pyrophosphate/tripolyphosphate selectivity is p[H] dependent. The dinuclear copper(II) complex of BMXD, (Cu(2)-BMXD)(SO(4))(2), crystallizes in the orthorhombic space group Pccn, with a = 15.73(2) ?, b = 20.27(1) ?, c = 9.045(5) ?, and Z = 4. The sulfate counterions are found to bridge the copper(II) ions in adjacent molecules leading to an extended polymeric structure.     

The order dimension of relatively free lattices

If V is a nontrivial lattice variety and is an infinite cardinal, then the order dimension of FV() is the smallest cardinal such that 2.This research was supported in part by NSF Grants DMS 87-03540 (Nation) and DMS 86-01576 (Schmerl).