Continuous Laminaribiose Production Using an Immobilized Bienzymatic System in a Packed Bed Reactor

The first continuous production system of laminaribiose from sucrose and glucose in a bienzymatic reaction is reported in this study. Immobilized laminaribiose phosphorylase and sucrose phosphorylase were used in a packed bed reactor system comprising of a 3-cm glass column at 35 °C with a steady feeding flow rate of 0.1 ml/min. Factors affecting product formation including enzyme ratio, peal concept (both enzymes in one pearl or in separate pearls), and pearl size were studied. An enzyme ratio of 2:1 of laminaribiose phosphorylase (LP) to sucrose phosphorylase (SP) when encapsulated separately in bigger size peals resulted in higher concentration of product. Laminaribiose (0.4 g/(L h)) is produced in the optimized system at steady state. The reaction system proved to be operationally stable throughout 10 days of continuous processing. A half-life time of more than 9 days was observed for both biocatalysts.     

Micellar effects on the rates of the condensation reaction between copper(II)‐histidine complex and ninhydrin

The kinetics of formation of N‐diketohydrindylidenehistidinatocopper(II) complex has been investigated in the presence of cationic cetyltrimethylammonium bromide (CTAB) surfactant in aqueous medium (pH = 5.0). Similarly in aqueous solution, the reaction followed irreversible first‐order kinetics with respect to [Ninhydrin]. Although the reaction mechanism remained unaltered by micelles, a typical k_ψ‐[CTAB] profile was observed, that is, with a progressive increase in [CTAB], the reaction rate increased, reached a maximum value, and then decreased. The results are treated quantitatively in terms of the kinetic pseudo‐phase model. Activation parameters were also evaluated and a large decrease in ΔS^# shows the formation of a well‐structured activated complex. It was found that anionic sodium dodecyl sulphate (SDS) and non‐ionic Triton X‐100 (TX‐100) surfactants have no effect on the reaction. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 729–736, 1999     

Kinetics of interaction of Histidine and Histidine Methyl Ester with Ninhydrin in micellar media

Kinetics of the interaction of histidine and histidine methyl ester with ninhydrin under varying concentrations of reactants, anionic (sodium dodecyl sulphate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and non‐ionic (Triton X‐100, TX‐100) micelles have been carried out. Rate of the reaction was found to be independent of the initial concentration of histidine (and histidine methyl ester) but was dependent on [Ninhydrin]. The SDS micelles had no effect on the rate of the reaction. In the presence of the CTAB micelles a small enhancement in the rate was observed. The rate − [CTAB] profile showed that the increase in [CTAB] increased the rate up to a maximum value and a further increase had a decreasing effect on the rate. The rate was enhanced by TX‐100 also but, unlike CTAB micelles, TX‐100 possessed a curve without peak for the rate − [TX‐100] profile. The following rate equation was obeyed by the reaction in CTAB and TX‐100 micelles: Values of k_w, k_m, and K_S were evaluated and are reported herein. ©1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 103–111, 1999     

Yolk–shell microspheres assembled from Preyssler‐type NaP5W30O11014− polyoxometalate and MIL‐101(Cr) metal–organic framework: A new inorganic–organic nanohybrid for fast and selective removal of cationic organic dyes from aqueous media

Novel inorganic–organic yolk–shell microspheres based on Preyssler‐type NaP₅W₃₀O₁₁₀^14? polyoxometalate and MIL‐101(Cr) metal–organic framework (P₅W₃₀/MIL‐101(Cr)) were synthesized by reaction of K_12.5Na_1.5[NaP₅W₃₀O₁₁₀], Cr(NO₃)₃·9H₂O and terephthalic acid under hydrothermal conditions at 200°C for 24 h. The as‐prepared yolk–shell microspheres were fully characterized using various techniques. All analyses confirmed the incorporation of the Preyssler‐type NaP₅W₃₀O₁₁₀^14? polyoxometalate into the three‐dimensional porous MIL‐101(Cr) metal–organic framework. The results revealed that P₅W₃₀/MIL‐101(Cr) demonstrated rapid adsorption of cationic methylene blue (MB) and rhodamine B (RhB) with ultrahigh efficiency and capacity, as well as achieving rapid and highly selective adsorption of MB from MB/MO (MO = methyl orange), MB/RhB and MB/RhB/MO mixtures. The P₅W₃₀/MIL‐101(Cr) adsorbent not only exhibited a high adsorption capacity of 212 mg g^?1, but also could quickly remove 100% of MB from a dye solution of 50 mg l^?1 within 8 min. The effects of some key parameters such as adsorbent dosage, initial dye concentration and initial pH on dye adsorption were investigated in detail. The equilibrium adsorption data were better fitted by the Langmuir isotherm. The adsorption kinetics was well modelled using a pseudo‐second‐order model. Also, the inorganic–organic hybrid yolk–shell microspheres could be easily separated from the reaction system and reused up to four times without any change in structure or adsorption ability. The stability and robustness of the adsorbent were confirmed using various techniques.     

Adsorption Capacities of Iron Hydroxide for Arsenate and Arsenite Removal from Water by Chemical Coagulation: Kinetics,Thermodynamics and Equilibrium Studies

Arsenic (As)-laden wastewater may pose a threat to biodiversity when released into soil and water bodies without treatment. The current study investigated the sorption properties of both As(III, V) oxyanions onto iron hydroxide (FHO) by chemical coagulation. The potential mechanisms were identified using the adsorption models, ζ-potential, X-ray diffraction (XRD) and Fourier Transform Infrared Spectrometry (FT-IR) analysis. The results indicate that the sorption kinetics of pentavalent and trivalent As species closely followed the pseudo-second-order model, and the adsorption rates of both toxicants were remarkably governed by pH as well as the quantity of FHO in suspension. Notably, the FHO formation was directly related to the amount of ferric chloride (FC) coagulant added in the solution. The sorption isotherm results show a better maximum sorption capacity for pentavalent As ions than trivalent species, with the same amount of FHO in the suspensions. The thermodynamic study suggests that the sorption process was spontaneously exothermic with increased randomness. The ζ-potential, FT-IR and XRD analyses confirm that a strong Fe-O bond with As(V) and the closeness of the surface potential of the bonded complex to the point of zero charge (pH_zpc) resulted in the higher adsorption affinity of pentavalent As species than trivalent ions in most aquatic conditions. Moreover, the presence of sulfates, phosphates, and humic and salicylic acid significantly affected the As(III, V) sorption performance by altering the surface properties of Fe precipitates. The combined effect of charge neutralization, complexation, oxidation and multilayer chemisorption was identified as a major removal mechanism. These findings may provide some understanding regarding the fate, transport and adsorption properties onto FHO of As oxyanions in a complex water environment.     

Simulation of heat and mass transfer on peristaltic flow of hyperbolic tangent fluid in an asymmetric channel

In the present analysis, the influence of heat and mass transfer on the peristaltic flow of a hyperbolic tangent fluid in an asymmetric channel has been discussed. The highly nonlinear equations are simplified under lubrication approach. The perturbation and numerical solutions of the problem are not only discussed but the validity of the results is also being checked. The graphical results of the problem under discussion are also being brought under consideration to see the behavior of various physical parameters. Copyright © 2012 John Wiley & Sons, Ltd.     

Quintic spline technique for time fractional fourth‐order partial differential equation

Higher order non‐Fickian diffusion theories involve fourth‐order linear partial differential equations and their solutions. A quintic polynomial spline technique is used for the numerical solutions of fourth‐order partial differential equations with Caputo time fractional derivative on a finite domain. These equations occur in many applications in real life problems such as modeling of plates and thin beams, strain gradient elasticity, and phase separation in binary mixtures, which are basic elements in engineering structures and are of great practical significance to civil, mechanical, and aerospace engineering. The quintic polynomial spline technique is used for space discretization and the time‐stepping is done using a backward Euler method based on the L1 approximation to the Caputo derivative. The stability and convergence analysis are also discussed. The numerical results are given, which demonstrate the effectiveness and accuracy of the numerical method. The numerical results obtained in this article are also compared favorably well with the results of (S. S. Siddiqi and S. Arshed, Int. J. Comput. Math. 92 (2015), 1496–1518). © 2016 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 445–466, 2017     

Plasmonic nanoloop array antenna

In this Letter, we create an optical nanoantenna array composed of parasitic plasmonic loops that can enhance radiation characteristics and direct the optical energy successfully. Three metallic loops inspired by the concept of the Yagi-Uda antenna are optimized around the region where they feature high scattering performance to control the radiation beam. The loop geometry, when compared to the dipole configuration, has the benefit of using the available aperture in an effective way to provide higher directivity. The angular emission of the nanoloop array antenna is highly directive, and a directivity of 8.2 dB for upward radiation is established.     

Engineering CNOT gate in cavity QED scenario

We present a quantum CNOT logic gate based on interaction of a three-level cesium atom with a two-mode electromagnetic field in a high-Q superconducting cavity. The three-level atom acts as a control qubit and the two-mode electromagnetic field serves as a target qubit. Presently available QED experiments make it feasible to realize the theoretical suggestion in the laboratory. We determine the feasibility of our proposal by calculating the fidelity.     

A study of cylindrically symmetric solutions in $$f(R, phi,X)$$ theory of gravity

The European Physical Journal C - Much theoretical effort and automatization are required to confront new physics models with experimental data for many types of particle reactions at future...