Extremal metrics and modulus

We give a new proof of Beurling's result related to the equality of the extremal length and the Dirichlet integral of solution of a mixed Dirichlet-Neuman problem.Our approach is influenced by Gehring's work in space. Also, some generalizations of Gehring's result are presented.     

Internal Stabilizability of Some Diffusive Models

We consider a single species population dynamics model with age dependence, spatial structure, and a nonlocal birth process arising as a boundary condition. We prove that under a suitable internal feedback control, one can improve the stabilizability results given in Kubo and Langlais [J. Math. Biol.29 (1991), 363-378]. This result is optimal.Our proof relies on an identical stabilizability result of independent interest for the heat equation, that we state and prove in Section 3.     

Development of a microfluidic‐based assay on a novel nitrocellulose platform

A novel microfluidic paper‐based analytical device (μPAD) utilizing a nitrocellulose (NC) membrane to detect IgG antibodies through a colorimetric analysis is described. The μPAD was constructed using layered polyethylene terephthalate (PET) and pressure‐sensitive adhesives (PSA). The biotin labeled Goat Anti‐Mouse IgG antibody was spotted and dried on the NC channel prior to subjecting it to a series of wash solutions (Tris‐tween), increasing concentrations of alkaline phosphatase conjugated to streptavidin (Strep‐ALP), and para‐nitrophenyl phosphate (p‐NPP) realizing a vibrant yellow color. The reaction proceeds for 10 min before applying the p‐NPP stop solution. The device was then dried, scanned, and analyzed yielding a linear range of inverse yellow color intensities versus Strep‐ALP concentrations. The development of this simple μPAD should further facilitate the use of NC in colorimetric assays to detect and quantitate antibodies.     

Theoretical study of K3Sb/graphene heterostructure for electrochemical nitrogen reduction reaction

Instead of the energy-intensive Haber-Bosch process, electrochemical nitrogen reduction reaction (NRR) is an exciting new carbon neutral technique for ammonia synthesis under ambient conditions. In this work, we investigated K-based electrocatalysts theoretically and demonstrated that K₃Sb/graphene performs excellent activity and inhibits hydrogen evolution on alternating reaction pathway. The first hydrogenation step from N₂* to NNH* was found to be the most energetic and limiting step (0.61 eV). Graphene substrate plays the critical role to promote electronic conductivity between K₃Sb and dinitrogen.     

An optimized microfluidic paper‐based NiOOH/Zn alkaline battery

In this paper, an alkaline nickel oxide hydroxide/zinc (NiOOH/Zn) battery featuring a cellulose matrix separator between electrodes is presented. The metallic electrodes and the paper separator are inserted in a layer‐by‐layer assembly that provides mechanical stability to the system resulting in a lightweight and easy‐to‐use device. The battery was optimized for the amount of NiOOH‐ink used at the cathode (11.1 mg/cm²) and thickness of the paper membrane separating the electrodes (360 μm). The battery was able to function using a small volume (75 μL) of 1.5 M potassium hydroxide (KOH) producing a maximum voltage, current density, and power density of 1.35 ± 0.05 V, 10.62 ± 0.57 mA/cm², and 0.56 ± 0.01 mW/cm², respectively. The system displayed a maximum current of 23.9 mA and a maximum power of 1.26 mW. Moreover, four batteries connected in series were able to power a small flameless candle for approximately 22 min. This work has potential in fulfilling the demands for short‐term and lightweight power supplies.     

Temperature influence on the malonic acid decomposition in the Belousov-Zhabotinsky reaction

The kinetic investigations of the malonic acid decomposition (8.00 × 10⁻³ mol dm⁻³ ≤ [CH₂(COOH)₂]₀ ≤ 4.30 × 10⁻² mol dm⁻³) in the Belousov-Zhabotinsky (BZ) system in the presence of bromate, bromide, sulfuric acid and cerium sulfate, were performed in the isothermal closed well stirred reactor at different temperatures (25.0°C ≤ T ≤ 45.0°C). The formal kinetics of the overall BZ reaction, and particularly kinetics in characteristic periods of BZ reaction, based on the analyses of the bromide oscillograms, was accomplished. The evolution as well as the rate constants and the apparent activation energies of the reactions, which exist in the preoscillatory and oscillatory periods, are also successfully calculated by numerical simulations. Simulations are based on the model including the Br₂O species. The article is published in the original.     

Effect of Added Monosodium Glutamate on Characteristics of Polyamide Dope Solutions

Formic acid (FA) solutions prepared with various concentrations of polyamide 66 (PA 66) and monosodium glutamate (MSG) were evaluated in terms of properties, such as density, viscosity, and cloud point. The influence on density was insignificant, whereas the viscosity was strongly affected by the amount of PA 66 and MSG additive. The solutions were further evaluated by casting them in a flat film form and determining the demixing time in a humid atmosphere. The considered cases at lower polymer concentrations at various MSG amounts, indicated that the demixing time increased with increase in polymer concentration. The time for demixing, however, decreased for a given higher amount of polymer when the amount of additive was increased in the dope solution. Membranes were prepared at various coagulant bath temperatures. The tensile strength and degree of adsorption (DOA) of these membranes were found. The tensile strength was higher when the membranes were prepared at higher temperature. The DOA, on the other hand, was higher for the membranes formed at lower temperature.     

On implementation via demand commitment games

A simple version of the Demand Commitment Game is shown to implement the Shapley value as the unique subgame perfect equilibrium outcome for any n-person characteristic function game. This improves upon previous models devoted to this implementation problem in terms of one or more of the following: a) the range of characteristic function games addressed, b) the simplicity of the underlying noncooperative game (it is a finite horizon game where individuals make demands and form coalitions rather than make comprehensive allocation proposals and c) the general acceptability of the noncooperative equilibrium concept. A complete characterization of an equilibrium strategy generating the Shapley value outcomes is provided. Furthermore, for 3 player games, it is shown that the Demand Commitment Game can implement the core for games which need not be convex but have cores with nonempty interiors. Received March 1995/Final version February 1997     

Intermittent Chaos in the Bray–Liebhafsky Oscillator. Dependence of Dynamic States on the Iodate Concentration

Chaotic dynamic states with intermittent oscillations were generated in a Bray–Liebhafsky (BL) oscillatory reaction in an isothermal open reactor i.e., in the continuously-fed well-stirred tank reactor (CSTR) when the inflow concentration of potassium iodate was the control parameter. They are found between periodic oscillations obtained when [KIO₃]₀ < 3.00 × 10^–2 M and stable steady states when [KIO₃]₀ > 4.10 × 10^–2 M. It was shown that the most chaotic states obtained experimentally somewhere in the middle of this region are in high correlation with results obtained by means of largest Lyapunov exponents and phenomenological analysis based on the quantitative characteristics of intermittent oscillations.     

Rapid asymmetric synthesis of amino acids via NiII complexes based on new fluorine containing chiral auxiliaries

New fluorine-containing chiral auxiliaries (S)-N-(2-benzoylphenyl)-1-(2-fluorobenzyl)-, (S)-N-(2-benzoylphenyl)-1-(3-fluorobenzyl)-, and (S)-N-(2-benzoylphenyl)-1-(4-fluorobenzyl)-pyrrolidine-2-carboxamide and their Ni^II complexes of Schiff bases with glycine and alanine have been synthesized. The greater efficiency of the complexes in terms of faster reaction rates and stereoselectivities in the asymmetric synthesis of (S)-α-amino acids has also been demonstrated.