Incommensurate magnetism in FeAs strips: neutron scattering from CaFe(4)As(3)

Magnetism in the orthorhombic metal CaFe(4)As(3) was examined through neutron diffraction for powder and single crystalline samples. Incommensurate [q(m) ≈ (0.37-0.39) × b*] and predominantly longitudinally (|| b) modulated order develops through a 2nd order phase transition at TN = 89.63(6) K with a 3D Heisenberg-like critical exponent β = 0.365(6). A 1st order transition at T2 = 25.6(9) K is associated with the development of a transverse component, locking q(m) to 0.375(2)b*, and increasing the moments from 2.1(1) to 2.2(3) μ B for Fe2+ and from 1.3(3) to 2.4(4) μB for Fe+. The ab initio Fermi surface is consistent with a nesting instability in cross-linked FeAs strips.     

Enantioselective ketoester reductions in water: a comparison between microorganism- and ruthenium-catalyzed reactions

In the search for green chemistry methods for the enantioselective reduction of ketoesters Saccharomyces cerevisiae- and ruthenium-catalyzed reactions in water have been investigated. The highest enantiomeric excesses for the reduction of α- and β-ketoesters have been obtained by S. cerevisiae. Chiral ruthenium catalysts are active for the reduction of all ketoesters with low to moderate enantioselectivities depending on the nature of the substrate and ligand. Interestingly, for several substrates both enantiomers of the hydroxyesters have been obtained according either to the catalytic method or to the structure of the ligand.     

Gas chromatographic profiles of plasma total lipids as indicators of dietary history. Correlation with carbohydrate and alcohol intake based on 24-h dietary recall.

Quantitative gas chromatographic estimates of the major lipid classes and molecular species in fasting plasma were correlated with total carbohydrate, starch, fibre, sucrose and alcohol intake based on 24-h dietary recall. Spearman coefficients (rs) and tests of significance (P) were obtained for groups of 775 males and 471 females aged 20-59 years from a Toronto-McMaster Lipid Research Clinics Population Study. The most significant correlations varying from rs 0.1 to 0.2 and P 0.001 to 0.0005 (n = 400-773) were between increased intake of alcohol and increased ratios of C50/C54 triacylglycerols, C34/C36 phosphatidylcholines and phosphatidylcholine/free cholesterol (PC/FC) of plasma. Increase in total dietary carbohydrate, starch and fibre correlated with decreasing C50/C54 triacylglycerol, C34/C36 phosphatidylcholine and PC/FC ratios (rs = -0.1-0.2; P less than 0.002-0.04; n = 400-773). In contrast, consumption of high levels of alcohol was associated with increasing C50/C54 triacylglycerol, C34/C36 phosphatidylcholine and PC/FC ratios. A high intake of alcohol (50-150 ml per day) distinguished itself from other simple carbohydrate-induced lipid profiles by its marked effect on increased C50/C52 triacylglycerol and PC/FC ratio.     

Nachweis und Bestimmung des Chroms

Ohne Zusammenfassung     

An algebraic characterization of planar graphs

A cycle in a graph is a set of edges that covers each vertex an even number of times. A cocycle is a collection of edges that intersects each cycle in an even number of edges. A bicycle is a collection of edges that is both a cycle and a cocycle. The cycles, cocycles, and bicycles each form a vector space over the integers modulo two when addition is defined as symmetric difference of sets. In this paper we examine the relationship between the left-right paths in a planar graph and the cycle space, cocylce space, and bicycle space. We show that planar graphs are characterized by the existence of a diagonal—a double cover by tours that interacts with the cycle space, cocycle space, and bicycle space in a special manner. This generalizes a result of Rosenstiehl and Read that characterized those planar graphs with no nonempty bicycles. © 1995 John Wiley & Sons, Inc.     

Non-trivial involutions on Floer Homology

 We construct the first examples of irreducible 3-manifolds with the homology of S ¹×S ² admitting an involution acting non-trivially on their Floer Homology. The examples are obtained by 0-surgery along certain composite amphicheiral knots whose SU(2)-representation variety satisfies a non-degeneracy condition. Received: 13 September 1999 / Revised version: 23 March 2000 / Published online: 28 March 2003 Mathematics Subject Classification (2000): 57R58, 57M25 When this article was submitted and revised, the author was supported by an NSERC post-doctoral fellowship and Harvard University     

On webs of maximum rank

This paper contains two results on webs of maximal rank. First, we show that at each point, the web normals for a codimension-r web of maximum r-rank are (r−1)-dimensional generators of a rational normal scroll in the projectivized tangent space to the web domain, an extension of a theorem of Chern and Griffiths in the case r=2 [5]. We use this statement to deduce that webs of maximum rank are almost-Grassmannizable in the sense of Akivis [1]. Second, we show that there are exceptional (that is, maximum rank, but not algebraizable) webs W(2n, n, 2) for all n≥2. The construction relies on the properties of zero-cycles on algebraic K3 surfaces.     

BODIPY: A Highly Versatile Platform for the Design of Bimodal Imaging Probes

In molecular imaging, multimodal imaging agents can provide complementary information, for improving the accuracy of disease diagnosis or enhancing patient management. In particular, optical/nuclear imaging may find important preclinical and clinical applications. To simplify the preparation of dual‐labeled imaging agents, we prepared versatile monomolecular multimodal imaging probe (MOMIP) platforms containing both a fluorescent dye (BODIPY) and a metal chelator (polyazamacrocycle). One of the MOMIP was conjugated to a cyclopeptide (i.e., octreotide) and radiolabeled with ¹¹¹In. In vitro and in vivo studies of the resulting bioconjugate were conducted, highlighting the potential of these BODIPY‐based bimodal probes. This work also confirmed that the biovector and/or the bimodal probes must be chosen carefully, due to the impact of the MOMIP on the overall properties of the resulting imaging agent.     

Formation constants for the complexes of orthophosphate with magnesium and hydrogen ions

The system of orthophosphate, magnesium and hydrogen ions in aqueous solution at 25 degrees and I = 0.2M chloride has been characterized by means of glass-electrode potentiometry. Protonation constants for orthophosphate species and formation constants for the complexes MgH(2)PO(+)(4), MgHPO(4), MgPO(4)(-) and MgOH(+) are reported.