Single-step link of the superdeformed band in 143Eu

A discrete γ-ray transition with an energy of 3360.6 keV deexciting the second lowest SD state in ¹⁴³ Eu has been discovered. It carries 3.2 % of the full intensity of the band and feeds into a nearly spherical state which is above the I = 35/2⁽⁺⁾, E_x=4947 keV level. The exact placement of the single-step link is, however, not established due to the specially complicated level scheme in the region of interest. The energy of the single-step link agrees well with the previously determined two-step links.     

Sharp Sobolev inequalities in the presence of a twist

Let be a smooth compact Riemannian manifold of dimension . Let also be a smooth symmetrical positive -tensor field in . By the Sobolev embedding theorem, we can write that there exist such that for any ,

where is the standard Sobolev space of functions in with one derivative in . We investigate in this paper the value of the sharp in the equation above, the validity of the corresponding sharp inequality, and the existence of extremal functions for the saturated version of the sharp inequality.

     

Tunable single-mode fiber-VCSEL using an intracavity polymer microlens

We report a tunable, single-mode vertical cavity surface-emitting laser (VCSEL) format suitable for array operation, power scaling, fiber coupling, and operation in isolated environments such as those required by atom optics. The devices are fiber VCSELs, consisting of a semiconductor gain and mirror structure separated from a mirror-coated optical fiber by an air (or vacuum) gap. The gain structure has polymer microlenses fabricated on its surface, of characteristics suitable to focus the oscillating mode on both cavity mirrors, ensuring stable fundamental mode emission and high fiber coupling efficiency. We demonstrate such devices in continuous-wave operation at 1.03 microm at room temperature, with a single-mode tuning range of 13 nm, laser threshold as low as 2.5 mW, and a maximum fiber-coupled output power of 10 mW.     

Cluster chemistry: size-dependent reactivity induced by reverse spill-over

In the present work, the CO oxidation rate on size-selected Pd clusters supported on thin MgO films is investigated in pulsed molecular beam experiments. By varying the cluster coverage independent of the cluster size, we were able to change the ratio of direct and diffusion flux (reverse spill-over) of CO onto the cluster catalyst and thus probe the influence of reverse spill-over on the reaction rate for different cluster sizes (Pd(8) and Pd(30)). The experimental results show that the change in reaction rate as a function of cluster coverage is different for Pd(8) and Pd(30). In order to explain these findings, the CO flux onto the clusters is modeled utilizing the collection zone model for the given experimental conditions. The results indicate that, for small clusters (Pd(8)), the reaction probability of an impinging CO molecule is independent of whether it is supplied by diffusion or direct flux. By contrast, for larger clusters (Pd(30)) a reduced reaction probability is found for CO supplied by reverse spill-over compared to CO supplied by direct flux.     

Mechanism of oxygen reactions at porous oxide electrodes. Part 2--Oxygen evolution at RuO2, IrO2 and Ir(x)Ru(1-x)O2 electrodes in aqueous acid and alkaline solution

The kinetics and mechanism of the oxygen evolution reaction at a series of RuO(2)/IrO(2) mixed oxides in aqueous acid and alkaline solution has been examined using a variety of electrochemical methods. Factors affecting the electrocatalytic activity have been elucidated and novel oxygen evolution mechanisms in terms of reactive oxyruthenium and oxyiridium surface groups are proposed.     

Photo-SRM: laser-induced dissociation improves detection selectivity of Selected Reaction Monitoring mode

Selected Reaction Monitoring (SRM) carried out on triple‐quadrupole mass spectrometers coupled to liquid chromatography has been a reference method to develop quantitative analysis of small molecules in biological or environmental matrices for years and is currently emerging as a promising tool in clinical proteomic. However, sensitive assays in complex matrices are often hampered by the presence of co‐eluted compounds that share redundant transitions with the target species. On‐the‐fly better selection of the precursor ion by high‐field asymmetric waveform ion mobility spectrometry (FAIMS) or increased quadrupole resolution is one way to escape from interferences. In the present work we document the potential interest of substituting classical gas‐collision activation mode by laser‐induced dissociation in the visible wavelength range to improve the specificity of the fragmentation step. Optimization of the laser beam pathway across the different quadrupoles to ensure high photo‐dissociation yield in Q2 without detectable fragmentation in Q1 was assessed with sucrose tagged with a push‐pull chromophore. Next, the proof of concept that photo‐SRM ensures more specific detection than does conventional collision‐induced dissociation (CID)‐based SRM was carried out with oxytocin peptide. Oxytocin was derivatized by the thiol‐reactive QSY® 7 C₅‐maleimide quencher on cysteine residues to shift its absorption property into the visible range. Photo‐SRM chromatograms of tagged oxytocin spiked in whole human plasma digest showed better detection specificity and sensitivity than CID, that resulted in extended calibration curve linearity. We anticipate that photo‐SRM might significantly improve the limit of quantification of classical SRM‐based assays targeting cysteine‐containing peptides. Copyright © 2011 John Wiley & Sons, Ltd.     

X-ray diffraction microscopy of magnetic structures

We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L3 edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.     

Titan Based Hybrid Organic-Inorganic Gels Comprising Carbohydrate Moiety

Abstract

A series of titanium based gels comprising carbohydrate moieties was synthesized. The sugars used include a specific hydrazide group as complex forming agent. Additionally, this group forms stable hydrates which allow further slow water release. As a result, the compounds used in this study form transparent and stable gels with titanium alkoxide without addition of external water. Interpretation of the IR-spectra reveals that some compounds form monodentate ligands and other bidentate ligands. Further Tian-Calvet calorimetric measurements confirmed our IR-based conclusions. This strategy of synthesis gives a new opportunity to obtain hybrid materials by addition of natural chelating ligands to slow down the hydrolysis/condensation reactions that occur during the sol-gel process. Therefore, carbohydrate moieties have been incorporated in the gels obtained and different type of Ti coordination was proposed based on the IR spectroscopy studies. SEM investigations show the influence of the ligand on the morphology of the xerogel.

GRAPHICAL ABSTRACT