Die Gasmolekeln Pd2Al2Cl10 und PdAlCl5 als Begleiter von PdAl2Cl8

Gas Molecules Pd₂Al₂Cl₁₀ and PdAlCl₅ as Accompanists of PdAl₂Cl₈ Mass spectrometric observations using a double cell showed that the reaction of gaseous Al₂Cl₆ with solid PdCl₂ besides the known gaseous complex PdAl₂Cl₈ gives PdAlCl₅ and the unexpected complex Pd₂Al₂Cl₁₀. For the equilibrium (with ΔCp? ?1 cal/K) ΔH°(298) = 7.5 kcal/Mol and ΔS°(298) = 5.3 ± 2 cl have been obtained.     

Isentropic partial molal compressibilities of alcohols in propylene carbonate at 25°C

The isentropic coefficients of compressibility of the homologous series of alcohols and diols R _n CH₂OH (n=2–6), CH₃CHOHR _n (n=1–5), 1,2-propanediol, 1,3- 1,4- and 2,3-butanediol, 1,5-pentanediol, and 1,7-heptanediol dissolved in propylene carbonate have been measured at 25°C. Isentropic partial molal compressibilities and group partial molal compressibilities at infinite dilution have been evaluated. The isentropic partial molal compressibilities of these alcohols and diols have been compared with the corresponding values in water. This comparison shows that the values in propylene carbonate are higher than in water by a factor of 10 due to an increased compressibility of the solvation sheath around nonpolar groups in PC.     

Metal-organic frameworks exhibiting strong anion-pi interactions

Coordination polymers offer a significant potential for applications in adsorption, guest and anion recognition and sensing. Their structure commonly provides binding sites for such specific interactions as pi-pi stacking and XH...pi hydrogen bonding. The latter reflects the ability of the pi-cloud to interact with positively polarized atoms. An electrostatic interaction between anionic species and electron deficient heterocycles, which parallels the above binding scheme, is also possible and very recently the existence of anion-pi interactions was proved in the solid state and in solution. This effect may be significant also for biomolecule/solution interfaces, as it occurs in protein structures. In fact, such interactions could be especially relevant for host-guest chemistry of coordination polymers, particularly for functionalization of hydrophobic crystal cavities and for the design of geometrically rigid anion receptors. However, typical electron deficient heterocycles such as 1,3,5-triazines and 1,2,4,5-tetrazines are very weak donors and they are hardly suitable for bridging metal ions and the generation of coordination frameworks. As a system that combines efficient donor properties towards transition metal ions and a pronounced ability for anion-pi interactions we have developed unsubstituted pyridazino[4,5-d]pyridazine, which was readily accessible by a novel one-pot synthesis involving inverse electron demand Diels-Alder cycloaddition (Scheme 1). Unusual anion binding properties of the ligand may be clearly related to its electron-deficiency (LUMO energy -1.591 vs. -0.288 eV for the parent pyridazine), influenced also by N-coordination to such Lewis acids as metal ions.     

Power-Counting Theorem for Non-Local Matrix Models and Renormalisation

Solving the exact renormalisation group equation à la Wilson-Polchinski perturbatively, we derive a power-counting theorem for general matrix models with arbitrarily non-local propagators. The power-counting degree is determined by two scaling dimensions of the cut-off propagator and various topological data of ribbon graphs. As a necessary condition for the renormalisability of a model, the two scaling dimensions have to be large enough relative to the dimension of the underlying space. In order to have a renormalisable model one needs additional locality properties—typically arising from orthogonal polynomials—which relate the relevant and marginal interaction coefficients to a finite number of base couplings. The main application of our power-counting theorem is the renormalisation of field theories on noncommutative ^D in matrix formulation.Acknowledgement We are grateful to José Gracia-Bondía and Edwin Langmann for discussions concerning the integral representation of the -product and its matrix base. We would like to thank Thomas Krajewski for advertising the Polchinski equation to us and Volkmar Putz for the accompanying study of Polchinskis original proof. We are grateful to Christoph Kopper for indicating to us a way to reduce in our original power-counting estimation the polynomial in to a polynomial in thus permitting immediately the limit ₀. We would also like to thank Manfred Schweda and his group for enjoyable collaboration. We are indebted to the Erwin Schrödinger Institute in Vienna, the Max-Planck-Institute for Mathematics in the Sciences in Leipzig and the Institute for Theoretical Physics of the University of Vienna for the generous support of our collaboration.     

Renormalisation of <Emphasis Type="Italic">ϕ</Emphasis><Superscript>4</Superscript>-Theory on Noncommutative ℝ<Superscript>4</Superscript> in the Matrix Base

We prove that the real four-dimensional Euclidean noncommutative ⁴-model is renormalisable to all orders in perturbation theory. Compared with the commutative case, the bare action of relevant and marginal couplings contains necessarily an additional term: an harmonic oscillator potential for the free scalar field action. This entails a modified dispersion relation for the free theory, which becomes important at large distances (UV/IR-entanglement). The renormalisation proof relies on flow equations for the expansion coefficients of the effective action with respect to scalar fields written in the matrix base of the noncommutative ⁴. The renormalisation flow depends on the topology of ribbon graphs and on the asymptotic and local behaviour of the propagator governed by orthogonal Meixner polynomials.     

Linear optics controlled-phase gate made simple

Linear optics quantum logic gates are the best tool to generate multiphoton entanglement. Simplifying a recent approach, we were able to implement the conditional phase gate with only one second-order interference at a polarization dependent beam splitter, thereby significantly increasing its stability. The improved quality of the gate is evaluated by analyzing its entangling capability and by performing full process tomography. The achieved results ensure that this device is well suited for implementation in various multiphoton quantum information protocols.     

Ab initio calculation of hyperfine and superhyperfine interactions for shallow donors in semiconductors

For the shallow group V donors in Si we show that the hyperfine interaction for the donor nucleus and the superhyperfine interactions for the first five shells of Si ligands can be quite accurately calculated using the local spin-density approximation of the density-functional theory. We treat the impurity problem in a Green's function approach. Since we have to truncate the long-ranged part of the defect potential, we do not obtain a localized gap state. Instead we identify the resonance above the conduction band with the paramagnetic defect state. We show that the hf and shf interactions thus obtained are at least as accurate as those obtained from one-electron theories with fitting parameters. Application of this first principles method to other shallow donors could be an essential help in defect identification.     

Beam-injection flame furnace AAS: comparison of different nozzle types for beam generation and application of sub-critical liquid carbon dioxide as carrier and gas pressure pump

In beam injection flame furnace AAS (BIFF-AAS) the sample is introduced as a free-flying high-speed liquid beam into an AAS flame-heated nickel tube, resulting in a considerable improvement in the power of detection. For optimization of beam generation different nozzle types (smooth jet nozzles, turbulent working nozzles) have been compared at different pressures. It was found that the type of the nozzle hardly influences the analytical signal. However, the flow rates resulting from the different inner diameters of the nozzles and the applied pressures led to drastic changes in the analytical signal. For these investigations a recently developed 0.6 MPa (84 psig) diaphragm pump system was used. Furthermore, for the first time ever sub-critical liquid carbon dioxide has been used simultaneously as a liquid gas-pressure pump, as carrier in a flow-injection system (FIA), and for the beam generation. Transport of the carrier takes place as a result of the head pressure (6 MPa) of the liquid CO₂ in the gas cylinder. For volatile elements (e.g. Cd, Hg, Pb, and Tl) detection limits between 0.2 µg L^–1 (Cd) and 28 µg L^–1 (Hg) were found, the standard deviation was from 0.6% to 3.2% depending on the element, concentration, and sample volume used. The use of liquid CO₂ as a carrier in FIA systems opens up new possibilities for online sample pretreatment and trace preconcentration.     

Identification of novel biomarker candidates by differential peptidomics analysis of cerebrospinal fluid in Alzheimer's disease

The objective of this work was the application of peptidomics technologies for the detection and identification of reliable and robust biomarkers for Alzheimer's disease (AD) contributing to facilitate and further improve the diagnosis of AD. Using a new method for the comprehensive and comparative profiling of peptides, the differential peptide display (DPD), 312 cerebrospinal fluid (CSF) samples from AD patients, cognitively unimpaired subjects and from patients suffering from other primary dementia disorders were analysed as four independent analytical sets. By combination with a cross validation procedure, candidates were selected from a total of more than 6,000 different peptide signals based on their discriminating power. Twelve candidates were identified using mass-spectrometric techniques as fragments of the possibly neuroprotective neuroendocrine protein VGF and another one as the complement factor C3 descendent C3f. The combination of peptide profiling and cross validation resulted in the detection of novel potential biomarkers with remarkable robustness and a close relation to AD pathophysiology.