Evidence for two geminate rebinding states following laser photolysis of R state hemoglobin encapsulated in wet silica gels

In this letter we report the first experimental evidence for CO rebinding to human hemoglobin from multiple geminate states. The analysis of the rebinding kinetics using a maximum entropy method allowed the identification of two distinct rebinding states within the protein matrix, which become populated under conditions of increased viscosity in a silica gel at high glycerol concentration. Our findings suggest the presence of at least two distinct docking sites for the photolyzed ligand. Assuming a minimal four-state model, we estimate the microscopic rates and the activation energies for the elementary processes.     

Functions with presribed singular values of the gradient

We prove the existence of infinitely many vector-valued Lipschitz-continuous functions u on an open set satisfying suitable Dirichlet boundary conditions such that the singular values of the gradient matrix u, i.e. the square roots of the eigenvalues of the symmetrized matrix , agree a.e. on with N given positive, bounded and lower semicontinuous functions. Received May 28, 1997     

Effect on structural relaxation of the poly(methyl‐methacrylate) copolymers chain flexibility

The structural relaxation of poly(methyl‐methacrylate) (PMMA)‐based copolymers with different chain flexibility has been studied by DSC with the classical procedure of the isothermal and dynamical approach. Modified PMMA with different chain flexibility have been prepared by free radical polymerization in solution using a mixture of monomers containing 10 mol % of alkyl methacrylate (i.e., ethyl, buthyl, and hexyl methacrylate). The molecular characteristics of all the prepared copolymers have been performed by a multiangle laser light scattering (MALS) photometer on‐line to a size exclusion chromatography (SEC) system (SEC‐MALS) after and before the thermal treatments, NMR (¹H and ¹³C) and MALDI‐TOF mass spectrometry. A comparison of the apparent relaxation rate (R_H) was appraised from the enthalpy loss by annealing the different samples at the same level of undercooling (T_a = T_g ? 18 °C). It was found an increase of R_H increasing the chain flexibility in the copolymers. Dynamical tests, performed at different cooling rates, have been used to estimate the apparent activation energy of the relaxation process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 596–607, 2009     

Error Estimates for a Stochastic Impulse Control Problem

We obtain error bounds for monotone approximation schemes of a stochastic impulse control problem. This is an extension of the theory for error estimates for the Hamilton-Jacobi-Bellman equation. We obtain almost the same estimate on the rate of convergence as in the equation without impulsions [2], [3].     

Optimization and validation of a high-performance liquid chromatography method for the analysis of cardiac glycosides in Digitalis lanata

In this study, a simple and reliable HPLC method for the qualitative and quantitative analysis of cardiac glycosides in Digitalis lanata Ehrh. raw material was developed and applied to healthy and phytoplasma-infected plants. The target analytes cover a broad range of secondary metabolites, including primary, secondary and tertiary glycosides and the corresponding aglycones. The sample preparation was carried out by sonication of the plant material with 70% (v/v) aqueous methanol at room temperature, followed by reversed-phase solid-phase extraction purification from interfering pigments. The HPLC analyses were performed on a Symmetry C₁₈ column (75 mm × 4.6 mm I.D., 3.5 μm), with a gradient elution composed of water and acetonitrile, at a flow rate of 1.0 mL/min. The column temperature was set at 20 °C and the photodiode array detector monitored the eluent at 220 nm. The method was validated with respect to ICH guidelines and the validation parameters were found to be highly satisfactory. The application of the method to the analysis of D. lanata leaves indicated that air-drying was the optimum method for raw material processing when compared with freeze-drying. The analysis of healthy and phytoplasma-infected plants demonstrated that the secondary metabolite mainly affected by the pathogen presence was lanatoside C (153.2 μg/100 mg versus 76.1 μg/100 mg). Considering the importance of D. lanata plant material as source of cardiac glycosides, the developed method can be considered suitable for the phytochemical analysis and for the quality assurance of D. lanata used for pharmaceutical purpose.     

Efficient access to 5-substituted thiazoles by a novel metallotropic rearrangement

A novel rearrangement process involving the migration of trimethylstannanyl or trimethylsilanyl groups around the thiazole ring provides access to either 2- or 5-metallated thiazoles by tuning the reaction conditions. The proposed mechanism, based on experimental evidence, is characterized by the catalytic role of thiazole bisadducts as metal-transfer agents.     

Synthesis of biomimetic light-driven molecular switches via a cyclopropyl ring-opening/nitrilium ion ring-closing tandem reaction

A cyclopropyl ring-opening/nitrilium ion ring-closing tandem reaction has been conveniently used in an expeditious synthetic approach to light-driven Z/E molecular switches featuring an imine function conjugated to olefin groups that mimics natural protonated Schiff bases.     

On the minimum problem for nonconvex, multiple integrals of product type

We consider the problem of minimizing multiple integrals of product type, i.e. where is a bounded, open set in , is a possibly nonconvex, lower semicontinuous function with p-growth at infinity for some and the boundary datum is in (or simply in if ). Assuming that the convex envelope off is affine on each connected component of the set , we prove attainment for () for every continuous, positively bounded below function g such that (i) every point is squeezed between two intervals where g is monotone and (ii) g has no strict local minima. This shows in particular that the class of coefficents g that yield existence to () is dense in the space of continuous, positive functions on . We present examples which show that these conditions for attainment are essentially sharp. Received April 12, 2000 / Accepted May 9, 2000 / Published online November 9, 2000     

Nanocomposite PEO-based polymer electrolyte using a highly porous,super acid zirconia filler

In this work we report a new composite, PEO-based lithium polymer electrolyte containing a micro-sized, nanoporous zirconium–oxide–sulfate (Zr–O–SO4) filler synthesized by a surfactant templating sol–gel route. By thermal and transport studies, we show that the particular morphology of the filler enhances the properties of the material leading to a solvent-free electrolyte having unique features in terms of ionic conductivity, lithium ion transference number and thermal behaviour. Finally, the galvanostatic test of the lithium battery prepared using lithium iron phosphate, LiFePO4, as the cathode, lithium metal as the anode and the studied membrane as the electrolyte, shows enhanced performances also at the medium–low temperatures.