Design,synthesis and activity study of tyrosinase encapsulated silica aerogel (TESA) biosensor for phenol removal in aqueous solution

Tyrosinase encapsulated silica aerogel (TESA) was synthesized via an alcohol-free colloidal sol–gel route at room temperature and at neutral pH. Characterization on TESA indicated that 98% of enzyme was effectively loaded and located inside the aerogel network. TESA without solvent extraction showed higher tyrosinase activity than TESA extracted by amyl acetate/acetone (v/v:1/1). Stability of tyrosinase in TESA was enhanced towards extreme temperature, acidic and basic conditions. Optimization study indicates that 500 U enzyme/g silica aerogel; aged for 2 days, showed superior performance in the oxidation of catechol. The activity of TESA was remarkably enhanced; which was active at a wider temperature (up to 80 °C) and pH range (4–9). In contrast, free tyrosinase was totally inactive at these pH values and temperature >55 °C. TESA successfully removed about 90% of phenol in aqueous solution after 3 h of contact time with excellent reusability.     

Cs2PtI6 Halide Perovskite is Stable to Air,Moisture, and Extreme pH: Application to Photoelectrochemical Solar Water Oxidation

Halide perovskites show incredible photovoltaic power conversion efficiency coupled with several hundreds of hours of device stability. However, their stability is poor in aqueous electrolyte media. Reported here is a vacancy ordered halide perovskite, Cs₂PtI₆, which shows extraordinary stability under ambient conditions (1 year), in aqueous media of extreme acidic (pH 1), basic (pH 13), and under electrochemical reduction conditions. It was employed as an electrocatalyst and photoanode for hydrogen production and water oxidation, respectively. The catalyst remains intact for at least 100 cycles of electrochemical cycling and six hours of hydrogen production at pH 1. Cs₂PtI₆ was employed as a photoanode for PEC water oxidation, and the material displayed a photocurrent of 0.8 mA cm^?2 at 1.23 V (vs. RHE) under simulated AM1.5G sunlight. Using constant voltage measurement, Cs₂PtI₆ exhibited over 12 hours of PEC stability without loss of performance.     

Microwave Plasma Jet in Water: Effect of Water Electrical Conductivity on Plasma Characteristics

Plasma Chemistry and Plasma Processing - Plasma-induced water treatment is a novel water treatment technique that has shown high efficiency and flexibility. Although the electrical conductivity of...     

THIRD ORDER SHEAR DEFORMATION MODEL FOR LAMINATED SHELLS WITH FINITE ROTATIONS： FORMULATION AND CONSISTENT LINEARIZATION

The paper presents an approach for the formulation of general laminated shells based on a third order shear deformation theory. These shells undergo finite (unlimited in size) rotations and large overall motions but with small strains. A singularity-free parametrization of the rotation field is adopted. The constitutive equations, derived with respect to laminate curvilinear coordinates, are applicable to shell elements with an arbitrary number of orthotropic layers and where the material principal axes can vary from layer to layer. A careful consideration of the consistent linearization procedure pertinent to the proposed parametrization of finite rotations leads to symmetric tangent stiffness matrices. The matrix formulation adopted here makes it possible to implement the present formulation within the framework of the finite element method as a straightforward task.     

Chaos and instability in a power system — Primary resonant case

We investigate some of the instabilities in a single-machine quasi-infinite busbar system. The system's behavior is described by the so-called swing equation, which is a nonlinear second-order ordinary-differential equation with additive and multiplicative harmonic terms having the frequency . When ₀, where ₀ is the linear natural frequency of the machine, we use digital-computer simulations to exhibit some of the complicated responses of the machine, including period-doubling bifurcations, chaotic motions, and unbounded motions (loss of synchronism). To predict the onset of these complicated behaviors, we use the method of multiple scales to develop an approximate first-order closed-form expression for the period-one responses of the machine. Then, we use various techniques to determine the stability of the analytical solutions. The analytically predicted period-one solutions and conditions for its instability are in good agreement with the digital-computer results.     

First-order accurate finite difference schemes for boundary vorticity approximations in curvilinear geometries

In this work we develop first-order accurate, forward finite difference schemes for the first derivative on both a uniform and a non-uniform grid. The schemes are applied to the calculation of vorticity on a solid wall of a curvilinear, two-dimensional channel. The von Mises coordinates are used to transform the governing equations, and map the irregular domain onto a rectangular computational domain. Vorticity on the solid boundary is expressed in terms of the first partial derivative of the square of the speed of the flow in the computational domain, and the derived finite difference schemes are used to calculate the vorticity at the computational boundary grid points using combinations of up to five computational domain grid points. This work extends previous work (Awartani et al., 2005) [3] in which higher-order schemes were obtained for the first derivative using up to four computational domain grid points. The aim here is to shed further light onto the use of first-order accurate non-uniform finite difference schemes that are essential when the von Mises transformation is used. Results show that the best schemes are those that use a natural sequence of non-uniform grid points. It is further shown that for non-uniform grid with clustering near the boundary, solution deteriorates with increasing number of grid points used. By contrast, when a uniform grid is used, solution improves with increasing number of grid points used.     

Recent trends in ultra‐fast HPLC: New generation superficially porous silica columns

New generation columns, i.e. packed with superficially porous silica particles are available as trade names with following manufacturers: Halo, Ascentis Express, Proshell 120, Kinetex, Accucore, Sunshell, and Nucleoshell. These provide ultra‐fast HPLC separations for a variety of compounds with moderate sample loading capacity and low back pressure. Chemistries of these columns are C₈, C₁₈, RP‐Amide, hydrophilic interaction liquid chromatography, penta fluorophenyl (PFP), F5, and RP‐aqua. Normally, the silica gel particles are of 2.7 and 1.7 μm as total and inner solid core diameters, respectively, with 0.5‐μm‐thick of outer porous layer having 90 Å pore sizes and 150 m²/g surface area. This article describes these new generation columns with special emphasis on their textures and chemistries, separations, optimization, and comparison (inter and intra stationary phases). Besides, future perspectives have also been discussed.