Insights into the Kramers’ flux‐over‐population rate for chemical reactions in liquid phases through the matrix transport equation

Kramers’ equation models a chemical reaction as a Brownian particle diffusing over a potential barrier under the influence of medium viscosity. In the case of high viscosity, the equation reduces to a simpler Smoluchowski equation. In this report, we have contrived an equivalent matrix‐transport equation that relates the ordered pair (activity, flux) of the output (activated complex) to that of the input (reactant). With an initial condition of the Dirac delta type placed at the location of the reactant, and a reflecting boundary condition set on the reactant state, and an absorbing boundary condition on the activated complex state, we are able to prove the equality relation between the mean first passage time, , for the diffusion and the inverse of the rate constant, k^?1, for the reaction counterpart. We have also derived , where λ_i is the ith eigenvalue of the Smoluchowski differential operator stipulated with the above‐mentioned boundary conditions. We have also deduced that, in the long time limit, the number of particles remaining inside the diffusion domain decays exponentially with a relaxation time just the same as the concentration of the reactant does for a first‐order reaction system.     

Discovery of DNA dyes Hoechst 34580 and 33342 as good candidates for inhibiting amyloid beta formation: in silico and in vitro study

Combining Lipinski’s rule with the docking and steered molecular dynamics simulations and using the PubChem data base of about 1.4 million compounds, we have obtained DNA dyes Hoechst 34580 and Hoechst 33342 as top-leads for the Alzheimer’s disease. The binding properties of these ligands to amyloid beta (Aβ) fibril were thoroughly studied by in silico and in vitro experiments. Hoechst 34580 and Hoechst 33342 prefer to locate near hydrophobic regions with binding affinity mainly governed by the van der Waals interaction. By the Thioflavin T assay, it was found that the inhibition constant IC50 ≈ 0.86 and 0.68 μM for Hoechst 34580 and Hoechst 33342, respectively. This result qualitatively agrees with the binding free energy estimated using the molecular mechanic-Poisson Boltzmann surface area method and all-atom simulations with the AMBER-f99SB-ILDN force field and water model TIP3P. In addition, DNA dyes have the high capability to cross the blood brain barrier. Thus, both in silico and in vitro experiments have shown that Hoechst 34580 and 33342 are good candidates for treating the Alzheimer’s disease by inhibiting Aβ formation.     

Myoglobin Detection: Utilizing Functional Magnetic Hybrid and Silica Micro Particles and Simple Molding Based Micro Channel Fabrication

A magnetic separator attached in a zig zag flow channel assembly has been fabricated to detect myoglobin on the micro particles. An anti‐myoglobin conjugated magnetic hybrid and myoglobin conjugated silica micro particles were prepared and used for myoglobin detection on channel. For the detections, the competitive assay principle was followed based on affinity interaction of anti‐myoglobin‐myoglobin. The caliberation curve was plotted based on the deposit percentage of myoglobin conjugated silica micro particles. The calibration curve of the myoglobin showed the linear range between 1 × 10^?8 ‐ 5 × 10^?11 (M) (R² = 0.9944). The minimum detectable concentration was 300 pg/mL. Hence all that concludes that, the application of zig zag flow channel with magnetic separator has offered new, simple and rapid approach for detecting myoglobin in whole blood samples with in 30 min.     

Transparent,flexible and solid-state supercapacitors based on room temperature ionic liquid gel

This paper describes a novel strategy to make fully transparent, solid-state and flexible supercapacitors based on room temperature ionic liquid (RTIL) gel and ITO electrodes coated on transparent polymer substrate without a separator, which enables the roll-to-roll technique for fabrication of such supercapacitors as printable devices. This is the first type of transparent electrochemical double layer capacitor (EDLC) based on ionic liquid gel.     

Recursive neural networks prediction of glass transition temperature from monomer structure: an application to acrylic and methacrylic polymers

We propose a new method based on a Recursive Neural Network (RecNN) for predicting polymer properties from their structured molecular representations. RecNN allows for a completely novel approach to QSPR analysis by direct adaptive processing of molecular graphs. This model joins the representational power of structured domains with Neural Network ability to capture underlying complex relationships in the data by a process of training from examples. To this aim, a structured representation was designed for the modelling of polymer structures. The adopted representation can account also for average macromolecule characteristics, such as degree of polymerization, stereoregularity, comonomer distribution. To begin with, this model was applied to the prediction of the glass transition temperature of (meth)acrylic polymers with different degree of main chain tacticity. The results so far obtained indicate that the proposed representation of polymer structure can convey information on both the repeating unit structure and average polymer features. The ability of the proposed RecNN method of treating this structured representation makes this method more general and flexible with respect to standard literature methods. Moreover, the same model can handle at the same time the Tg of polymer samples present in only one tacticity form together with that of polymer with different stereoregularity.     

One‐Pot Synthesis of 13‐Acetyl‐9‐methyl‐11‐oxo(or thioxo)‐8‐oxa‐10,12‐diazatricyclo[7.3.1.02,7]trideca‐2,4,6‐trienes under Microwave Irradiation

Oxygen‐bridged monastrol analogs, 13‐acetyl‐9‐methyl‐11‐oxo(or thioxo)‐8‐oxa‐10,12‐diazatricyclo[7.3. 1.0^2,7]trideca‐2,4,6‐trienes, were synthesized by one‐pot three component condensation reaction of substituted salicylaldehyde, acetylacetone and urea or thiourea with nontoxic, inexpensive, and easily available NaHSO₄ as catalyst under microwave irradiation and solvent‐free conditions in short time with good yields. The structures of the products were characterized by IR, ¹H NMR, ¹³C NMR spectra, and elemental analyses.     

Estimation of the Moments of the Residence Time and First Passage Time from Experimentally Measurable Permeation Parameters via a New Formulation of the Transmission Matrix

Siegel's analysis on membrane transport in the Laplace domain [J. Phys. Chem. 95 (1991) 2556] in terms of transmission matrix, T(s), has been extended to a more useful formulation. This is achieved by combining uses of the matrix transport equations appropriate for void initial condition, or for saturated equilibrium, or of Dirac delta functional type and the theorem det[T(s)] = 1. This formulation enables us to expand T(s) in power series of the Laplace variable, s, with the expansion coefficients as the algebraic functions of the experimentally measurable transport parameters. Utility of the formulation is illustrated in the estimation of the experimentally inaccessible time moments for the first passage or residence times. It was also applied to the percutaneous drug delivery to obtain from the experimental data. The higher moments of the time lag or time lead using a graphic method.     

Kinetics of Complex Formation Between Cobalt(II) and the Polyamine Me2Octaen

Abstract

The kinetics and the equilibria of complex formation between Co(II) and the linear polyamine 1,25-dimethyl-1,4,7,10,13,16,19,22,25-nonaazapentacosane (Me₂Octaen) have been investigated in aqueous solution under anaerobic conditions by the stopped-flow and potentiometric method. Static titrations and kinetic experiments indicate that below pH 5.6 the binding of Co(II) to the ligand gives rise to several 1:1 complexes differing for their degree of protonation, whereas above pH 5.6 binuclear complexes are formed as well. The analysis of the kinetic data reveals that the mostly reactive form of the ligand (denoted in its fully protonated form as H₉L₉₊) is H₆L⁶⁺. The species H₅L⁵⁺ and H₄L⁴⁺ yield only a minor contribution to the overall process of complex formation. Measurements at different ionic strengths have shown positive salt effects, as expected for reactive processes involving particles with charges of the same sign. The analysis of the results shows that Co²⁺ and H₆L⁶⁺ react according to the internal conjugate base mechanism.