DNA as a bioligand supported on magnetite for grafting palladium nanoparticles for cross-coupling reaction

The utilization of deoxyribonucleic acid (DNA) in nanotechnology is a promising area of research wherein the distinct properties of DNA are exploited for the design and development of new materials and applications. The biodegradability and natural profusion of DNA makes it highly suitable for use in various fields. In this report, we have treated DNA as a bioligand, supported on functionalized magnetite for the grafting of palladium (Pd) nanoparticles to make Pd-DNA bio-nanocatalyst. The Pd-DNA was subjected to Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Brunauer–Emmett–Teller, energy dispersive X-ray spectroscopy, vibrating sample magnetometry, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry analysis. The prepared Pd-DNA was found to be highly efficient in catalyzing Suzuki–Miyaura cross-coupling reaction with excellent yields when compared with commercially available palladium-based catalysts. Also, the Pd-DNA could be easily recovered from the reaction mass using an external magnet and recycled up to six times without substantial loss of activity. Furthermore, Felbinac, a non-inflammatory drug, was synthesized in quantitative yields using the Pd-DNA bio-nanocatalyst.     

Bifunctional 3D-MOF-based nanoprobes for electrochemical sensing and nanozyme enhanced with peroxidase mimicking for colorimetric detection of acetaminophen

The outgrowth of the zeolitic imidazole framework (ZIF-67) with substantial benefits was significantly used in the present study. The attractive properties of ZIF-67 are envisioned to develop a dual-functional sensing platform as electrochemical and colorimetric for acetaminophen detection. Co-ZIF-67 was developed as a synthesis-controlled material via three different preparation techniques as ZIF-67-C, ZIF-67-A, and ZIF-67-H. ZIF-67-C prepared via simple co-precipitation strategy in room temperature acquired rhombic dodecahedral structure with increased electrocatalytic activity. ZIF-67-C nanozyme exhibits enzymatic activity with intrinsic peroxidase mimicking and higher electron affinity than ZIF-67-A and ZIF-67-H. The well-developed ZIF-67-C without further aggregation and a steadily build structure resulted in an enhanced response. While the higher chance of aggregation and irregular arrangements of ZIF-67-A and ZIF-67-H resulted in lower performance toward acetaminophen detection. Moreover, the absorption of 3, 3 ', 5, 5' – tetramethylbenzidine (TMB) molecules could lower the diffusion distance leading to improved peroxidase mimicking activity. Nanozyme ZIF-67-C effectively oxidizes TMB to TMBox product and with hydroxyl radicals (^?OH) generation from H₂O₂ decomposition. Michaelis-Menten and Lineweaver Burk's model was estimated. The LOD was 0.014 μM (electrochemical) and 0.034 μM (calorimetric). The real samples as river water and lake water show good recovery in both sensing modes. The high surface area, improved electrical conductivity, high porosity of the prepared ZIF-67-C sample is beneficial for dual sensing applications and determined to be used in several applications.     

The unusual formation of methyl α-(5,6-dimethoxycarbonyl-2,3-dimethoxyazepin-7-ylidene)-α-[5-methoxycarbonyl-2,3-dimethoxypyrid-6-yl)acetate during the pyrolysis of “Azido-meta-hemipinate”: First example of a reaction involving a concomitant ring expansion and ring extrusion

The ortho methoxycarbonyl substituent constitutes a sole exception in the ring closure reactions of ortho substituted aryl azides, as it provides no rate acceleration to this reaction. Pyrolysis of “azido-meta-hemipinate”, an aryl azide containing such a substituent, led us to the title compound, a new azepinylidene-pyridylacetic ester, whose structure has been established unambiguously by a single crystal X-ray diffraction study. This is the first report of a reaction involving both a ring expansion to an azaheptafulvalene and a ring extrusion to a pyridyl ring residue.     

Finite volume element method for the incompressible miscible displacement problems in porous media

We present the finite volume element method (FVEM) for incompressible miscible displacement problems in porous media. Optimal error estimates in L^∞(L²) are derived for velocity and concentration. Numerical experiments are also presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

First principles study and database analyses of structural preferences for sodium ion (Na+) solvation and coordination

Extensive computations were performed on aqueous clusters of monovalent sodium cation [Na⁺(H₂O) _n ; (n = 1–20)] using MP2/cc-pVTZ and density functional theory. The structure, energy, and coordination number (CN) preference of a large number of competing conformations of different complexes have been explored. For complexes up to n = 12, the CN 4 is most preferred while 5, 6 CNs are favored in case of larger complexes containing up to 20 water molecules. These results are in very good agreement with experimental observations. The strength of hydrogen bonding among the waters coordinated to the Na⁺ ion is found to play a major role in the stability of the complexes. The varying preferences for CN of Na⁺ ion were explored by screening two important databases: Protein Databank and Cambridge Structural Database. A linear correlation is observed between the M (Metal)–O distance and the charge on metal ion in complex with the increase in CN of metal ion.     

Automated design of fractional PI QFT controller using interval constraint satisfaction technique (ICST)

In this paper, a fractional-order proportional-integral (FOPI) controller is proposed and designed for a class of nonlinear integer-order (IO) systems. For fair comparison, the proposed FOPI and the traditional integer-order PID (IOPID) controllers are designed following the same set of imposed tuning constraints, which can guarantee the desired control performance and the robustness of the designed controllers to the loop gain variations. This proposed design scheme offers a practical and systematic way of controller design for the nonlinear IO plant. We also propose a new and efficient method for automated synthesis of a fixed structure Quantitative Feedback Theory (QFT) FO controller. This is achieved by solving QFT quadratic inequalities of robust stability and performance specifications. The controller synthesis problem is posed as interval constraint satisfying problem (ICSP) and solved with interval constraint solver. The main feature of this method is that it guarantees to find all feasible controllers of given structure in the specified search domain. The designed FOPI and the traditional IOPID controllers are tested on the experimental setup designed by Educational Control Product (ECP) Magnetic Levitation Setup ECP 730. From the experimental results presented, it is observed that the designed FO controllers work more efficiently, with improved performance compared with the designed stabilizing IOPID controller.     

New Ru(II)–dmso complexes with heterocyclic hydrazone ligands towards cancer chemotherapy

The synthesis and characterization of ruthenium(II) complexes, [RuCl₂(dmso)₂(bfmh)] (1; dmso = dimethyl sulfoxide, bfmh = benzoic acid furan-2-ylmethylene-hydrazide), [RuCl₂(dmso)₂(btmh)](2; btmh = benzoic acid thiophen-2-ylmethylene-hydrazide), [RuCl₂(dmso)₂(bfeh)](3; bfeh = benzoic acid (1-furan-2-yl-ethylidene)-hydrazide) and [RuCl₂(dmso)₂(bpeh)](4; bpeh = benzoic acid (1-pyridin-2-yl-ethylidene)-hydrazide) are described. The ligands, when treated with either cis-[RuCl₂(dmso)₄] or trans(Cl)–[RuCl₂(dmso)₂(bpy)], resulted in the same products. This has been confirmed by IR spectra and single crystal X-ray diffraction studies. The redox behaviors of the complexes have been found to be strongly dependent on the electronic nature of the moieties present in the hydrazone ligands. The binding of the complexes to Herring sperm DNA has been studied by absorption titration and cyclic voltammetry. But, due to the random change in the absorption on the addition of DNA, only a qualitative result rather than a quantitative result has been obtained. All the complexes have been found to bind DNA through different modes to different extents. The antibacterial properties of the ligands and the complexes have been studied against five pathogenic bacteria and also the minimum inhibitory concentrations (MIC) of all the ligands and complexes 2 and 4 have been evaluated.     

Prediction of physical properties of nanofiltration membranes using experiment and theoretical models

Two commercial nanofiltration (NF) membranes, viz., Desal-HL and NF 700 MWCO were investigated experimentally using neutral and charged solutes, viz., glucose, sodium chloride and magnesium chloride. Effect of pH was studied for sodium chloride rejection and isoelectric point of the membrane was deduced. Experimental results were analyzed using Donnan steric pore and dielectric exclusion models. Dielectric exclusion arises due to the difference in dielectric constant between the bulk and the nano-pore. Born dielectric effect was used as dielectric exclusion phenomena in the present investigation. Stokes–Einstein, Born effective and Pauling radii were used for theoretical simulation, which accurately predicted different charge densities. Empirical correlations were proposed between charge density, concentration and pH for each radius. Charge density decreased drastically when dielectric exclusion term was included in the theoretical model, which showed the real physical characteristics of the membranes employed. Charge density and radius of pore was found to be an important surface parameter in predicting the separation effects in NF membranes.     

Nonlinear mathematical modeling of butterfly valves driven by solenoid actuators

This paper describes high fidelity modeling and analysis of the opening and closing processes of butterfly valves driven by solenoid actuators using multiphysics models. The equations are derived and solved numerically. The variable of primary interest is the butterfly valve rotation angle. The coupled model for electromagnetics, fluid dynamics and mechanical dynamics are derived by making some simplifying assumptions. It is shown that the behavior of hydrodynamic torque plays an important role in the closing and opening processes. A discussion is presented with an explanation of the results and a comparison has been made for both the processes.