Anisotropic conformal infinity

We generalize Penrose’s notion of conformal infinity of spacetime, to situations with anisotropic scaling. This is relevant not only for Lifshitz-type anisotropic gravity models, but also in standard general relativity and string theory, for spacetimes exhibiting a natural asymptotic anisotropy. Examples include the Lifshitz and Schrödinger spaces (proposed as AdS/CFT duals of nonrelativistic field theories), warped AdS ₃, and the near-horizon extreme Kerr geometry. The anisotropic conformal boundary appears crucial for resolving puzzles of holographic renormalization in such spacetimes.     

Transport equation on semidiscrete domains and Poisson–Bernoulli processes

In this paper, we consider a scalar transport equation with constant coefficients on domains with discrete space and continuous, discrete or general time. We show that on all these underlying domains, solutions of the transport equation can conserve sign and integrals both in time and space. Detailed analysis reveals that, under some initial conditions, the solutions correspond to counting stochastic processes and related probability distributions. Consequently, the transport equation could generate various modifications of these processes and distributions and provide some insights into corresponding convergence questions. Possible applications are suggested and discussed.     

Development of Novel Stability-Indicating Method for the Determination of Dimethindene Maleate and Its Impurities

A novel and selective stability-indicating liquid chromatographic method has been developed and validated for the analysis of dimethindene maleate, the related substance 2-ethylpyridine, and three degradation products. Dimethindene maleate was subjected to forced degradation study by acid and basic hydrolysis, oxidation, and thermal decomposition. Three degradation products that were formed during the forced degradation study were separated from dimethindene using a Zorbax SB CN column (150 × 4.6 mm; 5 μm); cyanopropyl-bonded stationary phase was applied for the first time for the separation of dimethindene and its impurities. The proposed method was validated and was found suitable for quality control and stability tests of pharmaceuticals containing dimethindene maleate.

     

Surface plasmon resonance biosensor for the detection of VEGFR-1—a protein marker of myelodysplastic syndromes

The surface plasmon resonance (SPR) biosensor system with dispersionless microfluidics for the direct and label-free detection of a soluble vascular endothelial growth factor receptor (sVEGFR-1) is described. The detection approach takes advantage of an affinity interaction between sVEGFR-1 and its ligand, vascular endothelial growth factor (VEGF-A), which is covalently immobilized on the surface of the SPR sensor. The ability of the immobilized VEGF-A to specifically bind the sVEGFR-1 receptor is demonstrated in a buffer. The detection of sVEGFR-1 in 2% human blood plasma is carried out by using the sequential injection approach. The detection limit of 25 ng/mL is achieved. In addition, we demonstrate that the functional surface of the sensor can be regenerated for repeated use.     

Controlled grafting of cellulose esters using SET‐LRP process

Here, we present the first example of application of single‐electron transfer living radical polymerization (SET‐LRP) process to a controlled grafting of cellulose esters, cellulose diacetate (CDA), and cellulose acetate butyrate (CAB). The cellulose ester macroinitiators with various functionality densities have been prepared by acylation of the backbones with 2‐bromoisobutyryl (BrIB) and dichloroacetyl (DCA) groups, respectively. Methacrylate monomers were polymerized using DCA‐functionalized macroinitiators in the presence of pentamethyldiethylene triamine as a ligand. At 30 °C, the reaction is rather slow, reaching about 10% conversion after 3 to 6 h of polymerization, whereas the higher temperature (60 °C) perceptibly speeds up the polymerization so that methyl methacrylate (MMA) conversion is ～30% after 5 h. Graft copolymers with random‐type and diblock‐type grafts having amphiphilic character were also synthesized. For acrylate grafting (BuA and t‐BuA), BrIB‐functionalized macroinitiators are more convenient in a combination with a low concentration of Cu(0) and Me₆TREN as a ligand and polymerization is detectably faster even at the lower temperature than that of MMA. Kinetic studies show “living” character of both the graftings. Important advantages of SET‐LRP, compared with classic ATRP, are (i) higher polymerization rate, (ii) lower extent of recombination of the growing grafts and (iii) negligible coloration of the products with catalytic residua, so that the prepared polymers do not require additional careful purification. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010