Coherent heavy quasiparticles in a CePt5 surface alloy

We report on the results of a high-resolution angle-resolved photoemission study on the ordered surface alloy CePt(5). The temperature dependence of the spectra show the formation of the coherent low-energy heavy-fermion band near the Fermi level. These experimental data are supported by a multiband model calculation in the framework of the dynamical mean-field theory.     

Superresolution vibrational imaging by simultaneous detection of Raman and hyper-Raman scattering

We have developed a superresolution vibrational imaging method by simultaneous detection of Raman and hyper-Raman scattering. Raman and hyper-Raman images obtained with the same laser spot carry independent information on the sample spatial distribution, owing to different signal dependence (linear in Raman and quadratic in hyper-Raman) on the incident light intensity. This information can be quantitatively analyzed to recover the incident light intensity distribution at the focal plane. A superresolution vibrational image is then derived by the constrained deconvolution of the images by the obtained incident light intensity distribution. This method has been applied to a TiO? nanostructure and the obtained superresolution image was compared with a scanning electron microscopy image. The spatial resolution achieved by the present method is evaluated to be 160 nm, which is more than twice better than the diffraction limited resolution.     

Flexible antibodies with nonprotein hinges

There is a significant need for antibodies that can bind targets with greater affinity. Here we describe a novel strategy employing chemical semisynthesis to produce symmetroadhesins: antibody-like molecules having nonprotein hinge regions that are more flexible and extendible and are capable of two-handed binding. Native chemical ligation was carried out under mild, non-denaturing conditions to join a ligand binding domain (Aβ peptide) to an IgG1 Fc dimer via discrete oxyethylene oligomers of various lengths. Two-handed Aβ-Fc fusion proteins were obtained in quantitative yield and shown by surface plasmon resonance to bind an anti-Aβ antibody with a K(D) at least two orders of magnitude greater than the cognate Aβ peptide. MALDI-TOF MS analysis confirmed the protein/nonprotein/protein structure of the two-handed molecules, demonstrating its power to characterize complex protein-nonprotein hybrids by virtue of desorption/ionization mediated by peptide sequences contained therein. We anticipate many applications for symmetroadhesins that combine the target specificity of antibodies with the novel physical, chemical and biological properties of nonprotein hinges.     

Highly cooperative double metalation of a bis(N2O2) ligand based on bipyridine-phenol framework driven by intramolecular π-stacking of square planar nickel(II) complex moieties

Highly cooperative double metalation took place when a novel ligand based on a bipyridine-phenol framework was allowed to react with nickel(II) acetate. The π-stacking of the square planar metal complex moieties is responsible for the highly cooperative double metalation judging from the X-ray crystal structure in which two complex moieties stack on top of each other in a parallel fashion.     

Selection of the biological activity of DNJ neoglycoconjugates through click length variation of the side chain

A series of neoglycoconjugates derived from deoxynojirimycin has been prepared by click connection with functionalised adamantanes. They have been assayed as glycosidase inhibitors, as inhibitors of the glycoenzymes relevant to the treatment of Gaucher disease, as well as correctors of the defective ion-transport protein involved in cystic fibrosis. We have demonstrated that it is possible to selectively either strongly inhibit ER-α-glucosidases and ceramide glucosyltransferase or restore the activity of CFTR in CF-KM4 cells by varying the length of the alkyl chain linking DNJ and adamantane.     

A specific LC/ESI-MS/MS method for determination of 25-hydroxyvitamin D3 in neonatal dried blood spots containing a potential interfering metabolite, 3-epi-25-hydroxyvitamin D3

Vitamin D deficiency in an infant is associated with a wide range of adverse health outcomes in later life. A method for the quantification of 25‐hydroxyvitamin D₃ [25(OH)D₃, the best‐established indicator of vitamin D status] in neonatal dried blood spots (DBSs) using LC/ESI‐MS/MS has been developed and validated. The method employed two steps of derivatization, a Diels–Alder reaction with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione followed by acetylation, to enhance the detectability of 25(OH)D₃ in ESI‐MS/MS and to separate 25(OH)D₃ from 3‐epi‐25‐hydroxyvitamin D₃ [3‐epi‐25(OH)D₃], a potent interfering metabolite. 25(OH)D₃ was extracted from two DBS punches (3 mm in diameter, equivalent to 5.3 μL of whole blood), purified using an Oasis HLB^® cartridge, and subjected to derivatization prior to analysis with LC/ESI‐MS/MS. 25‐Hydroxyvitamin D₄ was used as the internal standard. This method was reproducible (intra‐ and inter‐assay RSDs, <6.9%) and accurate (analytical recovery, 95.2–102.7%), and the LOQ was 3.0 ng/mL. The developed method enabled specific quantification of 25(OH)D₃ in neonatal DBSs and detection of vitamin D deficiency without interference from 3‐epi‐25(OH)D₃.     

Electrochemical heparin sensing at liquid/liquid interfaces and polymeric membranes

The monitoring of heparin and its derivatives in blood samples is important for the safe usage of these anticoagulants and antithrombotics in many medical procedures. Such an analytical task is, however, highly challenging due to their low therapeutic levels in the complex blood matrix, and it still relies on classical, indirect, clot-based assays. Here we review recent progress in the direct electrochemical sensing of heparin and its analogs at liquid/liquid interfaces and polymeric membranes. This progress has been made by utilizing the principle of electrochemical ion transfer at the interface between two immiscible electrolyte solutions (ITIES) to voltammetrically drive the interfacial transfer of polyanionic heparin and monitoring the resulting ionic current as a direct measure of heparin concentration. The sensitivity, selectivity, and reproducibility of the ion-transfer voltammetry of heparin are dramatically enhanced compared to those of traditional potentiometry. This voltammetric principle was successfully applied for the detection of heparin in undiluted blood samples, and was used to develop highly sensitive ion-selective electrodes based on thin polymeric membranes that are intended for analytical applications beyond heparin detection. The mechanism of heparin recognition and transfer at liquid/liquid interfaces was assessed quantitatively via sophisticated micropipet techniques, which aided the development of a powerful ionophore that can extract large heparin molecules into nonpolar organic media. Moreover, the reversible potentiometric detection of a lethal heparin-like contaminant in commercial heparin preparations was achieved through the use of a PVC membrane doped with methyltridodecylammonium chloride, which enables charge density dependent polyanion selectivity.     

Synthesis and electrode performance of carbon coated Na2FePO4F for rechargeable Na batteries

Carbon-coated Na₂FePO₄F is synthesized by a simple solid-state method with ascorbic acid as carbon source. Structural characterization of Na₂FePO₄F by synchrotron X-ray diffraction, scanning/transmission electron microscopy, and Raman spectroscopy reveals that ascorbic acid effectively suppresses the particle growth of Na₂FePO₄F, forming the nano-sized carbon coated materials. Electrode performance of Na₂FePO₄F for rechargeable sodium batteries is also examined. The carbon-coated Na₂FePO₄F sample (1.3 wt% carbon) delivers initial discharge capacity of 110 mAh g^-1 at a rate of 1/20 C (6.2 mA g^-1) with well-defined voltage plateaus at 3.06 and 2.91 V vs. Na metal. The sample also shows acceptable capacity retention and rate capability as the positive electrode materials for rechargeable Na batteries, which is operable at room temperature.     

Investigation of adsorption behavior and energy transfer of cationic porphyrins on clay surface at low loading levels by picosecond time-resolved fluorescence measurement

Time-resolved fluorescence and steady-state spectroscopic measurements were performed with +4-charged cationic porphyrins adsorbed on an anionic-type clay (Sumecton SA; SSA) surface at a low molecular loading level (10 % vs. cation-exchange capacity of clay) corresponding to an occupied area of ca 50 nm² per molecule. Absorption spectra indicated no interaction between transition moments of the porphyrins on the clay surface. An efficient energy-transfer process from donor to acceptor porphyrin was observed on the clay surface even under low porphyrin loading conditions. The efficiency of energy transfer obtained from the steady-state measurement was 65 %. Real-time behavior of the porphyrins was successfully captured during energy transfer. The rate constant of the energy transfer obtained from time-resolved fluorescence measurements was found to be 5.3 × 10⁸ s^?1. According to the efficiency and the rate constant, it is proposed that the adsorbed porphyrins did not have a uniform and fixed distribution.     

Novel methodology to control the adsorption structure of cationic porphyrins on the clay surface using the "size-matching rule"

Saponite-type clays that have different cation exchange capacities were successfully synthesized by hydrothermal synthesis. The structure and properties were analyzed by X-ray diffraction, X-ray fluorescence, (27)Al NMR, FT-IR, thermogravimetric and differential thermal analysis, atomic force microscopy, and cation exchange capacity measurement. The intercharge distances on the synthetic saponite (SS) surfaces were calculated to be 0.8-1.9 nm on the basis of a hexagonal array. The complex formation behavior between SS and cationic porphyrins was examined. It turns out that the average intermolecular distance between porphyrin molecules on the SS surface can be controlled, depending on the charge density of the SS. In the case of tetrakis(1-methylpyridinium-4-yl)porphyrin (H(2)TMPyP(4+)), the average intermolecular distances on the SS surface can be controlled from 2.3 to 3.0 nm on the basis of a hexagonal array. It was also found that absorption maxima of porphyrins depend on the charge density of the SS. The adsorption behavior of porphyrin on the SS surface can be rationally understood by the previously reported "size-matching rule". This methodology using host-guest interaction can realize a unique adsorption structure control of the porphyrin molecule on the SS surface, where the gap distance between guest porphyrin molecules is rather large. These findings will be highly valuable to construct photochemical reaction systems such as energy transfer in the complexes.