A convenient synthesis of 2-C-methyl-d-erythritol 4-phosphate and isotopomers of its precursor

A new synthetic approach toward 2-C-methyl-d-erythritol 4-phosphate (MEP), a key intermediate in the mevalonate-independent biosynthetic pathway for isoprenoids, and deuterated analogues of its precursor, 2-C-methyl-d-erythritol acetonide, is described. This procedure uses 2-C-methyl-d-erythrose acetonide as starting material and delivers, through a mono-protection strategy, the target compounds in a short way and in high yield.     

Feebly associativeP-hypergroupoids

In this paper we study the hyperstructures, saidP-hypergroupoids, (H, P*) in whichH is a set andP* is one of the hyperoperations defined as follows: ?(x, y) εH ²,xP*y=xyP orxP*y=Pxy whereP is a subset ofH. In particular we give a general formula for to express the simple hyperproducts ofn elements and then we consider some cases in which (H, P*) is feebly associative. We study, in such cases theβ-relations.     

Validation of a novel, fully automated high throughput high-performance liquid chromatographic/tandem mass Spectrometric method for quantification of pantoprazole in human plasma

An automated high-throughput HPLC/MS/MS method was developed for the quantitative determination of pantoprazole in human plasma. Only 100 microL plasma was placed in 2.2 mL 96 deep-well plates, and both pantoprazole and omeprazole (IS) were extracted from human plasma by liquid-liquid extraction, using diethyl ether-dichloromethane (70:30, v/v) as the organic solvent. Robotic liquid-handling workstations were used for all liquid transfer and solution preparation steps and resulted in a short sample preparation time. After vortexing, centrifugation, and freezing, the supernatant organic solvent was evaporated and reconstituted in a small volume of reconstitution solution. Sample analysis was performed by utilizing the combination of RP-HPLC/MS/MS, with positive-ion electrospray ionization and multiple reaction monitoring detection. The chromatographic run time was set at 1.8 min with a flow rate of 0.6 mL/min on a Nucleosil octylsilyl (C8) analytical column. The method was proven to be sensitive, specific, accurate, and precise for the determination of pantoprazole in human plasma. The method was applied to a bioequivalence study after per os administration of a 40 mg pantoprazole gastric retentive tablet.     

Dielectric breakdown and avalanches at nonequilibrium metal-insulator transitions

Motivated by recent experiments on the finite temperature Mott transition in VO(2) films, we propose a classical coarse-grained dielectric breakdown model where each degree of freedom represents a nanograin which transitions from insulator to metal with increasing temperature and voltage at random thresholds due to quenched disorder. We describe the properties of the resulting nonequilibrium metal-insulator transition and explain the universal characteristics of the resistance jump distribution. We predict that by tuning voltage, another critical point is approached, which separates a phase of boltlike avalanches from percolationlike ones.     

Large subgroups in finite groups

Following Isaacs (see [6, p. 94]), we call a normal subgroup N of a finite group Glarge, if ${\mathbf{C}}_G(N)\le N$, so that N has bounded index in G. Our principal aim here is to establish some general results for systematically producing large subgroups in finite groups (see Theorem A, Theorem C). We also consider the more specialised problems of finding large (non-abelian) nilpotent as well as abelian subgroups in soluble groups.     

An algorithm to construct Monte Carlo confidence intervals for an arbitrary function of probability distribution parameters

We derive a new algorithm for calculating an exact confidence interval for a parameter of location or scale family, based on a two-sided hypothesis test on the parameter of interest, using some pivotal quantities. We use this algorithm to calculate approximate confidence intervals for the parameter or a function of the parameter of one-parameter continuous distributions. After appropriate heuristic modifications of the algorithm we use it to obtain approximate confidence intervals for a parameter or a function of parameters for multi-parameter continuous distributions. The advantage of the algorithm is that it is general and gives a fast approximation of an exact confidence interval. Some asymptotic (analytical) results are shown which validate the use of the method under certain regularity conditions. In addition, numerical results of the method compare well with those obtained by other known methods of the literature on the exponential, the normal, the gamma and the Weibull distribution.     

An improved approach to chiral cyclopentenone building blocks. Total synthesis of pentenomycin I and neplanocin A

An improved approach to enantiomerically pure hydroxylated cyclopentenones is reported here, which involves intramolecular nitrone cycloaddition of sugar-derived chiral pent-4-enals and hex-5-en-ones-2 followed by N-O bond cleavage, quaternization of the amine thus produced, and finally oxidative elimination of the amino group. Synthesis of pentenomycin I and neplanocin A is described following this methodology.     

Stability and Instability of Extreme Reissner�CNordstr?m Black Hole Spacetimes for Linear Scalar Perturbations II

This paper contains the second part of a two-part series on the stability and instability of extreme Reissner–Nordstr?m spacetimes for linear scalar perturbations. We continue our study of solutions to the linear wave equation \square_gy = 0{\square_{g}\psi=0} on a suitable globally hyperbolic subset of such a spacetime, arising from regular initial data prescribed on a Cauchy hypersurface Σ₀ crossing the future event horizon H⁺{\mathcal{H}^{+}}. We here obtain definitive energy and pointwise decay, non-decay and blow-up results. Our estimates hold up to and including the horizon H⁺{\mathcal{H}^{+}}. A hierarchy of conservations laws on degenerate horizons is also derived.     

Stability and Instability of Extreme Reissner-Nordström Black Hole Spacetimes for Linear Scalar Perturbations I

We study the problem of stability and instability of extreme Reissner-Nordström spacetimes for linear scalar perturbations. Specifically, we consider solutions to the linear wave equation \({\square_{g}\psi=0}\) on a suitable globally hyperbolic subset of such a spacetime, arising from regular initial data prescribed on a Cauchy hypersurface Σ₀ crossing the future event horizon \({\mathcal{H}^{+}}\) . We obtain boundedness, decay and non-decay results. Our estimates hold up to and including the horizon \({\mathcal{H}^{+}}\) . The fundamental new aspect of this problem is the degeneracy of the redshift on \({\mathcal{H}^{+}}\) . Several new analytical features of degenerate horizons are also presented.