Characterizing the Phragmén‐Lindelöf condition for evolution on algebraic curves

For an algebraic curve V in ${mathbb C}^k times {mathbb C}^n$ it is investigated when it satisfies the Phragmén‐Lindelöf condition PL(ω) of evolution in certain classes of ultradifferentiable functions. Necessary as well as sufficient conditions are obtained which lead to a complete characterization for curves in ${mathbb C}times {mathbb C}^n$. Some examples illustrate how these results can be applied. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Daubechies wavelets as a basis set for density functional pseudopotential calculations

Daubechies wavelets are a powerful systematic basis set for electronic structure calculations because they are orthogonal and localized both in real and Fourier space. We describe in detail how this basis set can be used to obtain a highly efficient and accurate method for density functional electronic structure calculations. An implementation of this method is available in the ABINIT free software package. This code shows high systematic convergence properties, very good performances, and an excellent efficiency for parallel calculations.     

Entanglement witnesses and geometry of entanglement of two-qutrit states

We construct entanglement witnesses with regard to the geometric structure of the Hilbert-Schmidt space and investigate the geometry of entanglement. In particular, for a two-parameter family of two-qutrit states that are part of the magic simplex, we calculate the Hilbert-Schmidt measure of entanglement. We present a method to detect bound entanglement which is illustrated for a three-parameter family of states. In this way, we discover new regions of bound entangled states. Furthermore, we outline how to use our method to distinguish entangled from separable states.     

Detection of Paratuberculosis in Dairy Herds by Analyzing the Scent of Feces,Alveolar Gas,and Stable Air

Paratuberculosis is an important disease of ruminants caused by Mycobacterium avium ssp. paratuberculosis (MAP). Early detection is crucial for successful infection control, but available diagnostic tests are still dissatisfying. Methods allowing a rapid, economic, and reliable identification of animals or herds affected by MAP are urgently required. This explorative study evaluated the potential of volatile organic compounds (VOCs) to discriminate between cattle with and without MAP infections. Headspaces above fecal samples and alveolar fractions of exhaled breath of 77 cows from eight farms with defined MAP status were analyzed in addition to stable air samples. VOCs were identified by GC–MS and quantified against reference substances. To discriminate MAP-positive from MAP-negative samples, VOC feature selection and random forest classification were performed. Classification models, generated for each biological specimen, were evaluated using repeated cross-validation. The robustness of the results was tested by predicting samples of two different sampling days. For MAP classification, the different biological matrices emitted diagnostically relevant VOCs of a unique but partly overlapping pattern (fecal headspace: 19, alveolar gas: 11, stable air: 4–5). Chemically, relevant compounds belonged to hydrocarbons, ketones, alcohols, furans, and aldehydes. Comparing the different biological specimens, VOC analysis in fecal headspace proved to be most reproducible, discriminatory, and highly predictive.     

Dianionic Tris[oxalato(2—)]silicate and Tris[oxalato(2—)]germanate Complexes: Synthesis,Properties, and Structural Characterization in the Solid State and in Solution

Reaction of tetramethoxysilane with three molar equivalents of oxalic acid and two molar equivalents of 1‐(2‐hydroxyethyl)‐pyrrolidine or 1‐(2‐hydroxyethyl)piperidine in tetrahydrofuran yielded the λ⁶Si‐silicates 1‐(2‐hydroxyethyl)pyrrolidinium tris[oxalato(2—)]silicate ( 4 ) and 1‐(2‐hydroxyethyl)piperidinium tris[oxalato(2—)]silicate ( 5 ). The related germanium compounds 1‐(2‐hydroxyethyl)piperidinium tris[oxalato(2—)]germanate ( 6 ) and triethylammonium tris[oxalato(2—)]germanate ( 7 ) were synthesized analogously, starting from tetramethoxygermane and using three molar equivalents of oxalic acid and two molar equivalents of 1‐(2‐hydroxyethyl)piperidine or triethylamine. Compounds 4 — 7 were characterized by elemental analyses (C, H, N), single‐crystal X‐ray diffraction, solid‐state VACP/MAS NMR spectroscopy (²⁹Si), and solution NMR spectroscopy (¹H, ¹³C, ²⁹Si). The structural characterization was complemented by computational studies of the tris[oxalato(2—)]silicate dianion and the tris[oxalato(2—)]germanate dianion. In addition, the stability of compounds 4 — 7 in aqueous solution was studied by ¹³C NMR spectroscopy.     

Oligosaccharide Structural Studies by On-Line HPLC-MS using Fast Atom Bombardment Ionization

Abstract

A moving polyimide belt was used as an HPLC-MS interface for the purification and structural studies of oligosaccharides. The samples, desorbed by FAB in the absence of added liquid matrix, exhibited the following characteristics: a) good signal to noise ratio at low mass; b) a variation in the degree of fragmentation and relative sensitivity with changes in belt speed; c) a diminished sensitivity to signal suppression by contaminants when contrasted to FAB matrix; and d) fragment ions which can provide useful structural information. The moving belt HPLC-MS interface was tested with a series of known standards and a sample of high mannose oligosaccharides isolated from animal urines.     

Neutral Pentacoordinate Silicon(IV) Complexes with a Tridentate Dianionic O,N,O or N,N,O Ligand,an Anionic PhX Ligand (X = O,S, Se), and a Phenyl Group: Synthesis and Structural Characterization in the Solid State and in Solution

A series of neutral pentacoordinate silicon(IV) complexes with a SiO₃NC, SiO₂SNC, SiO₂SeNC, SiO₂N₂C, SiOSN₂C, or SiOSeN₂C skeleton was synthesized and structurally characterized by multinuclear NMR spectroscopy in the solid state and in solution and by single‐crystal X‐ray diffraction. The compounds studied contain a tridentate dianionic O,N,O or N,N,O ligand, an anionic PhX ligand (X = O, S, Se), and a phenyl group. The structures, NMR spectroscopic parameters, and chemical properties of these silicon(IV) complexes were compared with those of related compounds that contain a tridentate dianionic S,N,O ligand instead of the O,N,O or N,N,O ligand.     

Real time quantitative amplification detection on a microarray: towards high multiplex quantitative PCR

Quantitative real-time polymerase chain reaction (qrtPCR) is widely used as a research and diagnostic tool. Notwithstanding its many powerful features, the method is limited in the degree of multiplexing to about 6 due to spectral overlap of the available fluorophores. A new method is presented that allows quantitative amplification detection at higher multiplexing by the integration of amplification in solution and monitoring via hybridization to a microarray in real-time. This method does not require any manipulation of the PCR product and runs in a single closed chamber. Employing labeled primers, one of the main challenges is to measure surface signals against a high fluorescence background from solution. A compact, confocal scanner is employed, based on miniaturized optics from DVD technology and combined with a flat thermocycler for simultaneous scanning and heating. The feasibility of this method is demonstrated in singleplex with an analytical sensitivity comparable to routine qrtPCR.     

Syntheses and structures of dimesitylbismuth(III) bromide, Mes2BiBr, and bis(diphenyldithiophosphinato)mesitylbismuth(III), MesBi(S2PPh2)2

Addition of BiBr₃ to Mes₃Bi (Mes = 2, 4, 6-Me₃C₆H₂) in Et₂O gives 86% of Mes₂BiBr (1) as yellow crystals. Reaction of 1 with Ph₂PS₂NH₄ in a 1 : 1 molar ratio gives a quantitative yield of MesBi(S₂PPh₂)₂ (2) rather than the expected dimesitylbismuth compound. The crystal and molecular structures of 1 and 2 were determined at 153 K and 173 K, respectively. They contain Mes₂BiBr molecules with trigonal pyramidal coordination around Bi. The mean Bi---C bond distance is 2.27 Å and the Bi---Br bond distance is 2.690(2) Å. The angles around Bi vary between 89.4 and 106.4°. Intermolecular Bi…Br contacts of 3.795 Å, indicating weak secondary bonding, give rise to zig-zag shaped (Bi---Br)_x chains. In the polymeric chain the coordination geometry around bismuth atoms can be described as pseudo-trigonal bipyramidal. The crystals of 2 consist of discrete monomeric MesBi(S₂PPh₂)₂ molecules with a symmetry plane containing the metal atom and the aromatic ring of the attached mesityl group. The dithiophosphinato ligands exhibit an anisobidentate coordination pattern with long and short phosphorus—sulfur bonds, i.e. P(1)---S(1) 2.051(31) Å and P(1)---S(2) 1.980(3) Å, related to short and long bismuth—sulfur distances, respectively, i.e. Bi---S(1) 2.662(2) Å and Bi---S(2) 3.123(3) Å. This leads to a square-pyramidal geometry around the bismuth atom, with the metal lying 0.33 Å above the basal plane formed by the four sulfur atoms.