Numerically stable,scalable formulas for parallel and online computation of higher-order multivariate central moments with arbitrary weights

Formulas for incremental or parallel computation of second order central moments have long been known, and recent extensions of these formulas to univariate and multivariate moments of arbitrary order have been developed. Such formulas are of key importance in scenarios where incremental results are required and in parallel and distributed systems where communication costs are high. We survey these recent results, and improve them with arbitrary-order, numerically stable one-pass formulas which we further extend with weighted and compound variants. We also develop a generalized correction factor for standard two-pass algorithms that enables the maintenance of accuracy over nearly the full representable range of the input, avoiding the need for extended-precision arithmetic. We then empirically examine algorithm correctness for pairwise update formulas up to order four as well as condition number and relative error bounds for eight different central moment formulas, each up to degree six, to address the trade-offs between numerical accuracy and speed of the various algorithms. Finally, we demonstrate the use of the most elaborate among the above mentioned formulas, with the utilization of the compound moments for a practical large-scale scientific application.     

Benzopentalenonaphthalenones from the intramolecular capture of a merocyanine derived from a naphthopyran

Novel, highly coloured benzopentalenonaphthalenones result from a cascade process initiated by the thermally-induced ring-opening of diarylmethanol substituted 2H-naphtho[1,2-b]pyrans in the presence of acid.     

EDTA-catalyzed synthesis of 3,4-dihydroquinoxalin-2-amine derivatives by a three-component coupling of one-pot condensation reactions in an aqueous medium

This paper describes a simple and efficient one-pot synthetic approach for the preparation of biologically interesting 3,4-dihydroquinoxalin-2-amine derivatives using EDTA-catalyzed three-component reactions of o-phenylenediamines, carbonyl compounds, and isocyanides in an aqueous medium. This method is of great value because of its environmentally benign character, high yields, and ease of handling.     

An efficient synthesis of dexlansoprazole employing asymmetric oxidation strategy

An alternative and scalable synthesis of dexlansoprazole ((R)-(+)-1); the (R)-enantiomer of Lansoprazole with an enantiomeric excess of >99.8% is presented.     

Influence of cross diffusions on mixed convection chemical reaction flow in a vertical channel with Navier slip: Homotopy approach

This paper is to examine the incompressible, laminar mixed convective Navier slip flow between vertical plates with cross diffusion effects. This research includes the first order chemical reaction also. The resulting equations with boundary conditions are reduced into dimensionless form using appropriate transformations. The series solutions are developed through a modern technique known as the homotopy analysis method. The convergent expressions of velocity components and temperature are derived. The influence of emerging parameters on fluid flow quantities have been presented graphically. Also, the nature of physical quantities are shown in tabular form.     

Polymer-coated cation-exchange stationary phases on the basis of silica

Summary The procedure of polymer coating of preferably inorganic porous particle support materials for LC has been applied to the preparation of a new type of weak cationexchange phases. A special copolymer of butadiene and maleic acid could be immobilized on silica by cross-linking effected with radical starters such as peroxides or γ-radiation. The chromatographic properties of such materials proved to be excellent regarding efficiency, ion-exchange capacity and selectivity, as well as chemical stability also in comparison to other, commercially available, materials. Test measurements were successfully performed with ionic or ionizable inorganic and organic solutes over the entire applicable pH-range of the mobile phase which also contained organic modifiers. A special feature of the new type of cation-exchange phase is the minor contribution of hydrophobic (lipophilic) interaction to the retention mechanism besides the actual ion-exchange process.     

Synthesis and Characterization of Related Substances of Deferasirox,an Iron (Fe3+) Chelating Agent

Deferasirox is an orally active iron chelating agent, and during process development for deferasirox, we observed six related substances (impurities), namely deferasirox methyl ester, deferasirox salicylyl derivative, deferasirox ethyl ester, deferasirox methoxy carbonyl derivative, bis(salicyl)imide, and deferasirox-2-isomer. The present work describes the detection, origin, synthesis, and characterization of these related substances.     

Fabrication and characterization of thin films of single-walled carbon nanotube bundles on flexible plastic substrates

A convenient method to obtain patterns of films of single-walled carbon nanotubes (SWNT) bundles on flexible plastic is described. Using the Line Patterning method SWNT films of thickness ranging from approximately 300-1500 nm can be obtained from aqueous surfactant-supported dispersions of chemically purified SWNT bundles synthesized by the pulsed-laser ablation method. These films are strongly adherent and are competitive in performance with commercially available films of indium-tin-oxide (ITO) on plastics. For example, an approximately 1500 thick film of SWNT on poly(ethylene terephthalate) (PET) shows a surface resisitvity of approximately 80 Omega/sq, optical transparency >80%, and robust flexibility. Unlike ITO/PET, films of SWNT/PET can be folded and bent to a crease without cracking. The simple techniques involoved in obtaining these films (i.e., those without requiring lithography or ink-jet printing) could help facilitate the rapid fabrication of transparent, flexible electronic devices, heralding what promises to be a new approach towards the development of next-generation optoelectronic devices.     

Appearance of the dielectric instability and its coexistence with the superconductivity in ultrathin metallic filaments with decreasing diameter

Some dielectric instability appears before the superconducting (s/c) transition of Hg, In, Ga, Sn filaments when their diameters are decreased to 20–30 Å. Above the s/c transition the differential conductivity of the filaments may be approximated by the formula σ = σ_a + σ_b exp [-E₀(T)/E], where the electric field E₀ is equal toabout 10–60 mV cm^-1, and falls abruptly before the s/c transition. There are conductivity oscillations along E in the s/c transition region. The results are interpreted in terms of Peierls instability and charge-density wave (CDW) conductivity.