A generalization of Dahlberg's theorem concerning the regularity of harmonic Green potentials

Let be the solution operator for in , Tr on , where is a bounded domain in . B. E. J. Dahlberg proved that for a bounded Lipschitz domain maps boundedly into weak- and that there exists such that is bounded for . In this paper, we generalize this result by addressing two aspects. First we are also able to treat the solution operator corresponding to Neumann boundary conditions and, second, we prove mapping properties for these operators acting on Sobolev (rather than Lebesgue) spaces.

     

Neutralizing the Impact of the Virulence Factor LecA from Pseudomonas aeruginosa on Human Cells with New Glycomimetic Inhibitors

Bacterial adhesion, biofilm formation and host cell invasion of the ESKAPE pathogen Pseudomonas aeruginosa require the tetravalent lectins LecA and LecB, which are therefore drug targets to fight these infections. Recently, we have reported highly potent divalent galactosides as specific LecA inhibitors. However, they suffered from very low solubility and an intrinsic chemical instability due to two acylhydrazone motifs, which precluded further biological evaluation. Here, we isosterically substituted the acylhydrazones and systematically varied linker identity and length between the two galactosides necessary for LecA binding. The optimized divalent LecA ligands showed improved stability and were up to 1000-fold more soluble. Importantly, these properties now enabled their biological characterization. The lead compound L2 potently inhibited LecA binding to lung epithelial cells, restored wound closure in a scratch assay and reduced the invasiveness of P. aeruginosa into host cells.     

HPLC with diode-array detection for the simultaneous determination of di(2-ethylhexyl)phthalate and mono(2-ethylhexyl)phthalate in seminal plasma

A high-performance liquid chromatographic method for the simultaneous determination of di(2-ethylhexyl)phthalate (DEHP) and its major metabolite mono(2-ethylhexyl)phthalate (MEHP) in seminal plasma was developed and validated. The method involves liquid-liquid extraction followed by isocratic reversed-phase chromatography with diode-array detection. The recovery, selectivity, linearity, precision and accuracy of the method were evaluated from the analysis of spiked seminal plasma samples. The effect of mobile-phase composition and pH on the retention of the target analytes was investigated. The limits of detection were 0.010 and 0.015 microg/mL, for DEHP and MEHP, respectively. This method was used to analyze real samples in support of clinical studies on these potential endocrine disruptors.     

Remarkable steric effects and influence of monodentate axial ligands l on the spin-crossover properties of trans-[FeII(N4 ligand)L] complexes

Iron(II) complexes obtained from tetradentate, rigid, linear N4 ligands have been investigated to appraise the influence of steric effects and the impact of trans-coordinated anions on the spin-transition behavior. As expected, the well-designed ligands embrace the metal center, resulting in octahedral iron(II) complexes where the basal plane is fully occupied by the pyridine/pyrazole N4 ligand, while anions or solvent molecules are exclusively axially coordinated. Precursor complexes, namely, [Fe(bpzbpy)(MeOH)2](BF4)2 (where bpzbpy symbolizes the ligand 6,6'-bis(N-pyrazolylmethyl)-2,2'-bipyridine) and [Fe(mbpzbpy)(MeOH)2](BF4)2 (where mbpzbpy symbolizes the ligand 6,6'-bis(3,5-dimethyl-N-pyrazolmethyl)-2,2'-bipyridine), have been used for the in situ preparation of a series of structural analogues via the exchange of the weakly coordinated trans methanol molecules by various anions, such as thiocyanate, selenocyanate, or dicyanamide. The magnetic properties of all seven iron(II) compounds thus obtained have been investigated. Two iron(II) complexes, i.e., [Fe(bpzbpy)(NCS)2] and [Fe(bpzbpy)(NCSe)2], exhibit gradual spin-crossover (SCO) properties typical of isolated mononuclear species with weak cooperative interaction. These two SCO materials have been studied by M?ssbauer spectroscopy, and the light-induced excited spin state trapping effect has been investigated, revealing the possibility to induce the spin-transition both by temperature variation and by light irradiation. A correlation between steric/anion effect and SCO behavior is suggested.     

Dislocation theory as a 3‐dimensional translation gauge theory

We consider the static elastoplastic theory of dislocations in an elastoplastic material. We use a Yang‐Mills type Lagrangian (the teleparallel equivalent of Hilbert‐Einstein Lagrangian) and some Lagrangians with anisotropic constitutive laws. The translational part of the generalized affine connection is utilized to describe the theory of elastoplasticity in the framework of a translation gauge theory. We obtain a system of Yang‐Mills field equations which express the balance of force and moment.     

Preparation and Characterization of Semi-IPN Cryogels Based on Polyacrylamide and Poly(N,N-dimethylaminoethyl methacrylate); Functionalization of Carrier with Monochlorotriazinyl-β-cyclodextrin and Release Kinetics of Curcumin

Curcumin (CCM) is a natural hydrophobic polyphenol known for its numerous applications in the food industry as a colorant or jelly stabilizer, and in the pharmaceutical industry due to its anti-inflammatory, antibacterial, antioxidant, anti-cancer, and anti-Alzheimer properties. However, the large application of CCM is limited by its poor solubility in water and low stability. To enhance the bioavailability of CCM, and to protect it against the external degradation agents, a novel strategy, which consists in the preparation of semi-interpenetrating polymer networks, (s-IPNs) based on poly(N,N-dimethylaminoethyl methacrylate) entrapped in poly(acrylamide) networks, by a cryogelation technique, was developed in this work. All s-IPN cryogels were characterized by SEM, EDX, FTIR, and swelling at equilibrium as a function of pH. Functionalization of semi-IPN cryogel with monochlorotriazinyl-β-cyclodextrin (MCT-β-CD) led to IPN cryogel. The release profile of CCM from the composite cryogels was investigated at 37 °C, in pH 3. It was found that the cumulative release increased with the increase of the carrier hydrophobicity, as a result of increasing the cross-linking degree, the content and the molar mass of PDMAEMA. Fitting Higuchi, Korsmeyer–Peppas, and first order kinetic models on the CCM release profiles indicated the diffusion as the main driving force of drug release from the composite cryogels.     

Calculation of displacement fields and simulation of HRTEM images of dislocations in sphalerite type A(III)B(V) compound semiconductors

The displacement fields of different kinds of both perfect and dissociated dislocations have been calculated for an isotropic continuum, and by means of linear elasticity. Additionally, the corresponding HRTEM images have been simulated by the well-established EMS program package in order to predetermine the structural aspects of dislocations, and then to compare it with experimental HRTEM micrographs. The latter ones resulted from plastically deformed GaP single crystals and InAs/(001)GaAs single epitaxial layers. It could be established that using the simple approach of linear elasticity and isotropy results can be obtained which correspond well to the experimental images. So, the structure of various Shockley partial dislocations bounding a stacking fault can be detected unambiguously. The splitting behaviour of perfect 30° dislocations (separation into a 0° and 60° partial) and 90° dislocations (separation into two 60° partials) both with line direction along 〈112〉, 60° dislocations (separation into 30°/90° and 90°/30° configuration) and screw dislocations (separation into two 30° partials) along 〈110〉 are discussed in the more detail. Moreover, the undissociated sessile Lomer dislocation, glissile 60° dislocation and edge dislocation have been considered too.     

Retrospective correction for T1-weighting bias in T2 values obtained with various spectroscopic spin-echo acquisition schemes

Localized tissue transverse relaxation time (T₂) is obtained by fitting a decaying exponential to the signals from several spin-echo experiments at different echo times (TE). Unfortunately, time constraints in magnetic resonance spectroscopy (MRS) often mandate in vivo acquisition schemes at short repetition times (TR), that is, comparable with the longitudinal relaxation constant (T₁). This leads to different T₁-weighting of the signals at each TE. Unaccounted for, this varying weighting causes systematic underestimation of the T₂'s, sometimes by as mush as 30%. In this article, we (i) analyze the phenomenon for common MRS spin-echo T₂ acquisition schemes; (ii) propose a general post hoc T₁-bias correction for any (TR, TE) combination; (iii) show that approximate knowledge of T₁ is sufficient, since a 20% uncertainty in T₁ leads to under 3% bias in T₂; and consequently, (iv) efficient, precision-optimized short TR spin-echo T₂ measurement protocols can be designed and used without risk of accuracy loss. Tables of correction for single-refocusing (conventional) spin-echo and double refocusing, such as, PRESS acquisitions, are provided.     

Self‐healing of high elasticity block copolymers

A new route for adding self‐healing properties to soluble polymers is presented briefly. Self‐healing block copolymers (polystyrene‐block‐polybutadiene block‐polystyrene from Sigma‐Aldrich) were obtained by dissolving the polymer in a solvent that neither dissolves the microbubbles nor deactivate the Grubbs catalyst. The self‐healing block copolymer has been obtained by mixing the polymer, the solvent, the microbubbles filled with monomer (dicyclopentadiene), and the Grubbs' catalyst followed by the evaporation of the solvent. The structure of self‐healed high elasticity block copolymer has been investigated by optical and Scanning Electron Microscopy. Raman spectroscopy and mechanical data suggested that the block copolymer exhibits self‐healing features. Copyright © 2008 John Wiley & Sons, Ltd.