Impossibility of Stokes decomposition for a class of light beams

Decomposition throughout all space of a typical light beam into the sum of a completely polarized and a completely unpolarized beam (Stokes decomposition) seems to be rather the exception than the rule. However, it is known that such decomposition can often be made across a certain plane, although it may lose validity upon propagation. Then, one may guess that, for any light beam, there exists at least one plane where the Stokes decomposition can be performed. Without adopting any particular model for polarized and unpolarized beams, we present a class of beams for which no such plane can exist.     

Modular Architecture of Protein Binding Units for Designing Properties of Cellulose Nanomaterials

Molecular biomimetic models suggest that proteins in the soft matrix of nanocomposites have a multimodular architecture. Engineered proteins were used together with nanofibrillated cellulose (NFC) to show how this type of architecture leads to function. The proteins consist of two cellulose‐binding modules (CBM) separated by 12‐, 24‐, or 48‐mer linkers. Engineering the linkers has a considerable effects on the interaction between protein and NFC in both wet colloidal state and a dry film. The protein optionally incorporates a multimerizing hydrophobin (HFB) domain connected by another linker. The modular structure explains effects in the hydrated gel state, as well as the deformation of composite materials through stress distribution and crosslinking. Based on this work, strategies can be suggested for tuning the mechanical properties of materials through the coupling of protein modules and their interlinking architectures.     

A Mass‐Spectrometry‐Based Approach to Distinguish Annular and Specific Lipid Binding to Membrane Proteins

Membrane proteins engage in a variety of contacts with their surrounding lipids, but distinguishing between specifically bound lipids, and non‐specific, annular interactions is a challenging problem. Applying native mass spectrometry to three membrane protein complexes with different lipid‐binding properties, we explore the ability of detergents to compete with lipids bound in different environments. We show that lipids in annular positions on the presenilin homologue protease are subject to constant exchange with detergent. By contrast, detergent‐resistant lipids bound at the dimer interface in the leucine transporter show decreased k_off rates in molecular dynamics simulations. Turning to the lipid flippase MurJ, we find that addition of the natural substrate lipid‐II results in the formation of a 1:1 protein–lipid complex, where the lipid cannot be displaced by detergent from the highly protected active site. In summary, we distinguish annular from non‐annular lipids based on their exchange rates in solution.     

LC–MS–MS Separation and Simultaneous Determination of Tolterodine and its Active Metabolite, 5-Hydroxymethyl Tolterodine in Human Plasma

A selective, sensitive and high throughput LC–MS–MS method has been developed and validated for the chromatographic separation and quantitation of tolterodine (TOL) and its metabolite 5-hydroxymethyl TOL in human plasma. Sample clean-up concerned liquid–liquid extraction of the drug, metabolite and their respective labelled internal standards from 300 μL human plasma. Both the analytes were chromatographically separated on a Symmetry C18 (100 mm × 4.6 mm, 5 μm particle size) analytical column using 10 mM ammonium formate (pH 5.0 ± 0.1, adjusted with formic acid) and acetonitrile (35:65, v/v) as the mobile phase with a resolution factor of 2.72. The method was validated over the concentration range of 0.025–10.0 ng mL^?1 for both analytes. The process efficiency found for TOL and its metabolite was 98.3 and 99.5%, respectively. The method was successfully applied to a pivotal bioequivalence study in 41 healthy human subjects after oral administration of a 2 mg tablet formulation under fasting conditions.     

Anomalous energy transport in the FPU‐β chain

We consider the energy current correlation function for the FPU‐β lattice. For small nonlinearity one can rely on kinetic theory. The issue reduces then to a spectral analysis of the linearized collision operator. We prove thereby that, on the basis of kinetic theory, the energy current correlations decay in time as t^?3/5. It follows that the thermal conductivity is anomalous, increasing as N^2/5 with the system size N. © 2008 Wiley Periodicals, Inc.     

Temperature dependent atomic transport properties of liquid Sn

A simple analytical model for atomic motion of Tankeshwar et al. [J. Phys.: Condens. Matter 3, 3173 (1991)] is used to obtain velocity autocorrelation function (VACF) with the inter-atomic potential and the pair correlation function as required inputs for liquid Sn. For the electron-ion interaction the modified empty-core potential is used, which represents the orthogonalisation effect due to s-core states in such sp-bonded metals. Temperature dependence of structure factor is considered through temperature dependent potential parameter in the pair potential. The coherent behaviour of liquid Sn in terms of the dynamic structure factor employing viscoelastic theory has also been studied. Intrinsic temperature effect has been studied through damping term\hbox{${\exp}( {-\frac{{\pi k}_{{B}} {T}}{{2k}_{{F}} }{r}} )$} exp (?πkBT2kFr)in the pair potential. The predicted results for VACF, cosine power spectrum, mean square displacement, diffusion and viscosity coefficients have been compared with recent available data, and a good agreement has been achieved.     

Novel Fe (III) heterochelates: Synthesis,structural features and fluorescence studies

Fluorescence properties of five 4-acyl pyrazolone based hydrazides (H₂SB_n) and their Fe (III) heterochelates of the type [Fe(SB_n)(L)(H₂O)]·mH₂O [H₂SB_n = nicotinic acid [1-(3-methyl-5-oxo-1-phenyl-4,5-di hydro-1H-pyrazol-4yl)-acylidene]-hydrazide; where acyl = –CH₃, m = 4 (H₂SB₁); –C₆H₅, m = 2 (H₂SB₂); –CH₂–CH₃, m = 3 (H₂SB₃); –CH₂–CH₂–CH₃, m = 1.5 (H₂SB₄); –CH₂–C₆H₅, m = 1.5 (H₂SB₅) and HL = 1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid] were studied at room temperature. The fluorescence spectra of heterochelates show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. The kinetic parameters such as order of reaction (n), energy of activation (E_a), entropy (S*), pre-exponential factor (A), enthalpy (H*) and Gibbs free energy (G*) have been reported.     

Boundary conditions,symmetry breakdown and Feynman path integral

The analysis of boundary conditions in variational formulation of classical field theory is performed. It is used in the Feynman path integral formulation of quantum theory including non-trivial cases of dynamical symmetry breakdown.Presented at the International Symposium Selected Topics in Quantum Field Theory and Mathematical Physics, Bechyn, Czechoslovakia, June 14–19, 1981.