Sulfonyl Ketenimines as Key Intermediates in One‐Pot Synthesis of N‐Sulfonyl‐2‐alkaneimidoyl Selenocyanates

Sulfonyl‐ketenimine intermediates, generated by the addition of Cu acetylides to sulfonyl azides, are trapped by KSeCN to afford N‐sulfonyl‐2‐alkaneimidoyl selenocyanates in moderate‐to‐good yields.     

Alkaline phosphatase-labeled macromolecular probe for sensitive chemiluminescence detection of proteins on a solid-phase membrane

In the present study, we synthesized dextran (MW = ca. 2,000 kDa)-based macromolecular probes containing multiple molecules of alkaline phosphatase (ALP) as a signal-trigger enzyme and of biotin as an assembly mediator. The ALP and biotin molecules were covalently attached into the dextran backbone after the formation of aldehyde groups into the macromolecule by periodate oxidation. The synthesized probes contained 27–31 molecules of ALP in their macromolecules when 50-fold molar ratio of ALP to the dextran was used for the synthesis. These probes provided 14–20 times stronger chemiluminescence (CL) than that of the equimolar free ALP adsorbed on a nylon membrane. The velocity of the CL reaction of ALP-catalyzed adamantlyl-1,2-dioxetane substrate was improved from a slower emission (glow type) of CL to a faster one (flash type). The CL signal integrated for 2 min under strongly alkaline conditions (pH 13.0) was about ten times greater than that obtained by the conventional conditions (pH 9.5). Therefore, the synthesized macromolecular probe could be successfully utilized for the high-throughput CL detection of biotin-conjugated anti-rabbit IgG antibody with a lower detection limit of 880 amol per spot on the nylon membrane. This study provides analytical strategy for the rapid, convenient, and sensitive detection of target proteins in immunoassays.     

A note on warped product submanifolds of Kenmotsu manifolds

Warped product manifolds are known to have applications in Physics. For instance, they provide an excellent setting to model space-time near a black hole or a massive star (cf. [HONG, S. T.: Warped products and black holes, Nuovo Cimento Soc. Ital. Fis. B 120 (2005), 1227–1234]). The studies on warped product manifolds with extrinsic geometric point of view are intensified after B. Y. Chen’s work on CR-warped product submanifolds of Kaehler manifolds. Later on, similar studies are carried out in the setting of Sasakian manifolds by Hasegawa and Mihai. As Kenmotsu manifolds are themselves warped product spaces, it is interesting to investigate warped product submanifolds of Kenmotsu manifolds. In the present note a larger class of warped product submanifolds than the class of contact CR-warped product submanifolds is considered. More precisely the existence of warped product submanifolds of a Kenmotsu manifold with one of the factors an invariant submanifold is ensured, an example of such submanifolds is provided and a characterization for a contact CR-submanifold to be a contact CR-warped product submanifold is established.     

Mathematical modeling and numerical simulation of CO2 transport through hollow-fiber membranes

Chemical absorption of carbon dioxide was studied theoretically using hollow-fiber membrane contactors in this work. A 2D mathematical model was developed to study CO₂ transport through hollow-fiber membrane contactors. The model considers axial and radial diffusion in the membrane contactor. It also considers convection in the tube and shell side with chemical reaction. The finite element method (FEM) was used to solve the model equations. Modeling predictions were validated with the experimental data obtained from literature for CO₂ absorption in amine aqueous solutions as solvent. The modeling predictions were in good agreement with the experimental data for different values of gas and liquid velocities. The liquid solvents considered for this study include aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP) and potassium carbonate (K₂CO₃). The simulation results indicated that amine aqueous solutions were better than K₂CO₃ aqueous solution for CO₂ absorption. Also simulation results revealed that the removal of CO₂ with aqueous solution of MEA was the highest among the amines solvents. The hollow-fiber membrane contactors showed a great potential in the area of CO₂ absorption.     

Investigation on the dynamics of electron transport and recombination in TiO2 nanotube/nanoparticle composite electrodes for dye-sensitized solar cells

In this work, we report on fabrication and characterization of dye-sensitized solar cells based on TiO(2) nanotube/nanoparticle (NT/NP) composite electrodes. TiO(2) nanotubes were prepared by anodization of Ti foil in an organic electrolyte. The nanotubes were chemically separated from the foil, ground and added to a TiO(2) nanoparticle paste, from which composite NT/NP electrodes were fabricated. In the composite TiO(2) films the nanotubes existed in bundles with a length of a few micrometres. By optimizing the amount of NT in the paste, dye-sensitized solar cells with an efficiency of 5.6% were obtained, a 10% improvement in comparison to solar cells with pure NP electrodes. By increasing the fraction of NT in the electrode the current density increased by 20% (from 11.1 to 13.3 mA cm(-2)), but the open circuit voltage decreased from 0.78 to 0.73 V. Electron transport, lifetime and extraction studies were performed to investigate this behavior. A higher fraction of NT in the paste led to more and deeper traps in the resulting composite electrodes. Nevertheless, faster electron transport under short-circuit conditions was found with increased NT content, but the electron lifetime was not improved. The electron diffusion length calculated for short-circuit conditions was increased 3-fold in composite electrodes with an optimized NT fraction. The charge collection efficiency was more than 90% over a wide range of light intensities, leading to improved solar cell performance.     

A survey of parameter and state estimation in queues

Queueing Systems - We present a broad literature survey of parameter and state estimation for queueing systems. Our approach is based on various inference activities, queueing models, observations...     

Some fixed point theorems in convex metric spaces

The concept of a convex metric space was introduced by Takahashi [10]. He observed that it is possible to generalize fixed point theorems in Banach spaces. Subsequently, Machado [8], Itoh [5], Naimpally, Singh and Whitfield [9] and Beg and Azam [2], among others have studied fixed point theorems in convex metric spaces. This paper is a continuation of these investigations.     

Planarity relations for the sextic centrifugal distortion constants of triangular triatomic molecules

Four linearly independent linear combinations of the ten sextic centrifugal distortion coefficients of triangular triatomic molecules are presented. These combinations are formed in such a way that the resulting expressions depend only on the equilibrium geometry and the harmonic force field parameters of the molecule, quantities which are ordinarily known to considerably better precision than the sextic constants. The relations obtained thus constitute a set of planarity constraints on the ten sextic coefficients which arise in connection with the Nielsen-Amat expansion of the Darling-Dennison Hamiltonian. The planarity expressions can be utilized to effect a reduction of the sextic portion of the Hamiltonian.     

Modified alpha-beta chimeric oligoDNA bearing a multi-conjugate of 2,2-bis(hydroxymethyl)propionic acid-anthraquinone-polyamine exhibited improved and stereo-nonspecific triplex-forming ability

Novel alpha-beta chimeric oligonucleotides bearing a propionic acid derivative of an anthraquinone-polyamine conjugate in the "linker" region sequence-specifically formed a substantially stable alternate-stranded triplex with dsDNA almost regardless of the stereochemistry of the derivative.     

Solving stochastic chemical kinetics by Metropolis-Hastings sampling

This study considers using Metropolis-Hastings algorithm for stochastic simulation of chemical reactions. The proposed method uses SSA (Stochastic Simulation Algorithm) distribution which is a standard method for solving well-stirred chemically reacting systems as a desired distribution. A new numerical solvers based on exponential form of exact and approximate solutions of CME (Chemical Master Equation) is employed for obtaining target and proposal distributions in Metropolis-Hastings algorithm to accelerate the accuracy of the tau-leap method. Samples generated by this technique have the same distribution as SSA and the histogram of samples show it''s convergence to SSA