Synthesis of 2-diphenylphosphinoyl-3,5-diaryl-3,4-dihydro-2H-telluropyrans by reaction of chalcones with bis[(diphenylphosphinoyl)methyl]telluride

The NaH-promoted tandem Michael addition/intramolecular Wittig-Horner reaction of bis[(diphenylphosphinoyl) methyl]telluride with chalcones stereoselectively afforded trans-2-diphenylphosphinoyl-3,5-diaryl-3,4-dihydro-2H-telluropyran derivatives in 51-72% yield, under mild conditions.     

Analytical and numerical investigation of mixed-type functional differential equations

This paper is concerned with the approximate solution of a linear non-autonomous functional differential equation, with both advanced and delayed arguments. We search for a solution x(t), defined for t∈[−1,k], (k∈N), that satisfies this equation almost everywhere on [0,k−1] and assumes specified values on the intervals [−1,0] and (k−1,k]. We provide a discussion of existence and uniqueness theory for the problems under consideration and describe numerical algorithms for their solution, giving an analysis of their convergence.     

Asymptotic Symmetries in Cosmological Models

In the present article we study asymptotic isometries and asymptotic conformal Killing motions of some anisotropic Bianchi cosmological models. We show that asymptotically isotropic homogeneous cosmological spaces can be covariantly studied and characterized using scalars constructed with the help the Killing equations. We exhibit some illustrative examples of space-times possessing asymptotic Killing collineations. We apply our results in order to discuss asymptotic symmetries associated with scalar cosmological perturbations.     

Effective polarization in quasi-free scattering

A simple relation, involving only experimental quantities, for the effective polarizations in quasi-free (p, 2p) scattering on closed shell nuclei is tested for recent TRIUMF (p, 2p) experiments with 200 MeV polarized protons.     

Networkmetrics: multivariate big data analysis in the context of the internet

Multivariate problems are found in all areas of knowledge. In chemistry and related disciplines, the chemometric community was developed in a joint effort to understand and solve problems mainly from a multivariate and exploratory perspective. This perspective is, indeed, of broader applicability, even in areas of knowledge far from chemistry. In this paper, we focus on the Internet: the net of devices that allow an interconnected world where all types of data can be shared and unprecedented communication services can be provided. Problems in the Internet or in general in networking are not very different from chemometric problems. Building on this parallelism, we review four classes of problems in networking: estimation, anomaly detection, optimization, and classification. We present an illustrative set of problems and show how a multivariate perspective may lead to significant improvements from state‐of‐the‐art techniques. In the absence of a better name, we call the approach of treating these problems from that multivariate perspective networkmetrics. Networkmetric problems have their own specificities, mainly, their typical Big Data nature and the presence of unstructured data. We argue that multivariate analysis is, indeed, useful to tackle these specificities. Copyright © 2016 John Wiley & Sons, Ltd.     

QM/MM metadynamics study of the direct decarboxylation mechanism for orotidine-5'-monophosphate decarboxylase using two different QM regions: acceleration too small to explain rate of enzyme catalysis

Despite decades of study, the mechanism by which orotidine-5'-monophosphate decarboxylase (ODCase) catalyzes the decarboxylation of orotidine monophosphate remains unresolved. A computational investigation of the direct decarboxylation mechanism has been performed using mixed quantum mechanical/molecular mechanical (QM/MM) dynamics simulations. The study was performed with the program CP2K that integrates classical dynamics and ab initio dynamics based on the Born-Oppenheimer approach. Two different QM regions were explored. The free energy barriers for direct decarboxylation of orotidine-5'-monophosphate (OMP) in solution and in the enzyme (using the larger QM region) were determined with the metadynamics method to be 40 and 33 kcal/mol, respectively. The calculated change in activation free energy (DeltaDeltaG++) on going from solution to the enzyme is therefore -7 kcal/mol, far less than the experimental change of -23 kcal/ mol (for k(cat.)/k(uncat.): Radzicka, A.; Wolfenden, R., Science 1995, 267, 90-92). These results do not support the direct decarboxylation mechanism that has been proposed for the enzyme. However, in the context of QM/MM calculations, it was found that the size of the QM region has a dramatic effect on the calculated reaction barrier.     

Thermophilic anaerobic digester performance under different feed-loading frequency

The effect of feed-loading frequency on digester performance was studied on a thermophilic anaerobic digester with a working volume of 27.43 m(3). The digester was fed 0.93 m(3) of chicken-litter slurry/d, containing 50.9 g/L chemical oxygen demand. The treatments were loading frequencies of 1, 2, 6, and 12 times/d. The hourly pH, biogas production, and methane percent of the biogas were less stable at lower feed frequencies. There was no statistical difference among treatments in methanogenic activity. The feed-loading frequency of six times per day treatment provided the greatest biogas production.     

Some Integral Representation for Meta-Monogenic Function in Clifford Algebras Depending on Parameters

In recent years, the integral representation problems have been studied in many context and generalities. For example, for the monogenic and meta functions in some Clifford type algebras, see [10, 11]. In this paper we construct a Cauchy-Pompeiu type formula for meta-monogenic operator of order ${n, (D-\lambda)^n, \lambda \in \mathbb{R}}$ , and its conjugate ${(\overline{D} - \lambda)^n}$ in a Clifford algebra depending on parameters ${\mathcal{A}_n(2, \alpha_j, \gamma_{ij})}$ . Using these explicit representation formula of Cauchy-Pompeiu type we will show some applications.     

A new piece in the puzzle of lithium/air batteries: computational study on the chemical stability of propylene carbonate in the presence of lithium peroxide

The electrolyte role in non-aqueous lithium/air batteries is attracting a lot of attention in several research groups, because of its fundamental importance in producing the appropriate reversible electrochemical reduction. While recent published works identify the lithium superoxide as the main degrading agent for propylene carbonate (PC), there is no clear experimental evidence that the oxygen at the cathode interface layer does not reduce further to peroxide before reacting with PC. Here, we investigate the reactivity of lithium peroxide versus propylene carbonate and find that Li(2)O(2) irreversibly decomposes the carbonate solvent, leading to alkyl carbonates. We also show that, compared with a single Li(2)O(2) unit in PC, a crystalline surface of Li(2)O(2) exhibits an enhanced reactivity. Our findings support the possibility that in lithium/air cells, oxygen may still be reduced to peroxide, with the formation of solid Li(2)O(2), which degrades by decomposing PC.