Dye Degradation and Sulfur Oxidation of Methyl Orange and Thiophenol via Newly Designed Nanocomposite GQDs/NiSe-NiO Photocatalyst Under Homemade LED Light

Photocatalytic processes triggered by graphene-based photocatalysts under solar light have sparked interest as a new sort of instrument for solar chemical synthesis. Herein we investigated self-assembled graphene quantum dots (GQDs)/NiSe-NiO composite photocatalyst for organic transformation as well as dye degradation. The synthesized GQDs/NiSe-NiO composite photocatalyst has an excellent suitable band gap, high molar extinction coefficient, low toxicity and chemical/thermal stability. The GQDs/NiSe-NiO composite photocatalyst emerges as a new standard for sulfur oxidation and dye degradation reactions under homemade LED light with high yield.     

Peptide Cysteine Thiols Act as Photostabilizer of Avobenzone through Stabilizing the Transition State of Keto-Enol Tautomerization

Photostabilizers have been used to impart stability to an FDA-approved chemical UV-A filter avobenzone against the UV-A radiations and sunlight. The thiol group of glutathione plays a critical role in imparting the photostabilization activity of glutathione on avobenzone. The current report aims to evaluate the photostabilization activity of multiple thiols containing cysteine peptides on avobenzone. Cysteine-tripeptide and cysteine-pentapeptide were chemically synthesized and characterized using mass spectrometry. Synthetic peptides were assessed for their photostabilization activity on the enolic-form of the avobenzone under natural sunlight using UV spectroscopy in both protic and aprotic solvents. Unlike glutathione, which has pronounced activity in protic solvents, cysteine-pentapeptide exhibits similar photoprotection activity in both protic and aprotic solvents. Computational calculations using DFT suggest that peptide cysteine thiols may assist in the reversal of the photoketonization process of avobenzone thereby exhibiting the photoprotection activity to the enolic-form of avobenzone. Peptide cysteine thiols lower the activation energy barrier of keto-to-enol tautomerization of avobenzone by 30 kcal mol⁻¹ by assisting the proton shuttle through a six-membered transition state. The current report emphasizes the applications of peptide thiols in cosmetics and may help in the development of peptides as aesthetic medicines.     

Phase switching in Hindmarsh-Rose relay neurons

A system of Hindmarsh-Rose relay neurons with time delay coupling is considered in which the relay (central) neuron has an additional feedback term that represents the interaction activity with a local environment. The strength of environmental coupling with the central neuron plays an important role in inducing synchronization and de-synchronization between the outer neurons. The strength of feedback developed from the environmental coupling has created a gradual quenching in the oscillations of the central neuron. At a higher feedback coupling strength, oscillation of the central neuron is suppressed drastically and a transition from a regime of synchronization to out-of-phase synchronization take place between the oscillations of the two outer neurons.     

Exploring structural feature of aldose-reductase inhibition by 5-[[2-(omega-carboxyalkoxy)aryl]methylene]-4-oxo-2-thioxothiazolidine derivatives employing Fujita-Ban and Hansch approach

Designing of a highly selective, potent and safe inhibitor of aldose reductase (ALR) capable of potentially blocking the excess glucose flux through the polyol pathway that prevails under diabetic condition has been a long standing challenge. In our study, we did quantitative structure-activity relationship (QSAR) analysis, based on Fujita-Ban and classical Hansch approach, on 5-[[2-(omega-carboxyalkoxy)aryl]methylene]-4-oxo-2-thioxothiazolidine derivatives. Study gave structural insight into the binding mode of the molecules to the aldose reductase enzyme. The Fujita-Ban approach revealed that benzylidene thiazolidine nucleus is more potent as compare to naphthyl-methylene thiazolidine analogs. The bulkierness of naphthyl-methylene might be inquisitive with receptor. Hansch approach suggested that electron-withdrawing groups are conducive to aldose reductase inhibitory activity.     

Microsphere based continuous-flow immunoassay in a microfluidic device for determination of clinically relevant insulin levels

This paper describes a miniaturized microsphere-based immunoassay integrated into a microfluidic device for rapid quantitation of insulin. Analysis of bionic pancreas studies have revealed that the rates of absorption of insulin analogs vary from patient to patient, and even within patients on different occasions. Thus development of an approach to monitor insulin continuously allows the pharmacokinetic characteristics of insulin analogs to be determined in real-time. The authors have developed a microsphere-based continuous flow assay in a microfluidic chip that allows for the detection of insulin within seconds with high sensitivity and specificity. The method was applied to near real-time monitoring of clinical samples. Calibration plot were established for different insulin analogs such as insulin aspart (Novolog), insulin lispro (Humalog), and regular human insulin (RHI) and the insulin detection limit was 0.26 ng.mL^?1 (44 pM). This sensitivity allows to detect the fasting insulin levels of T1D patients, which are reported in the range of 50–180 pM (0.3–1 ng.mL^?1), after treatment with subcutaneous insulin administration. This fast approach was also applied to sera collected in intervals from T1D patients after a bolus of insulin aspart delivery. The insulin profile obtained by this method is similar to the basal and peak insulin levels as determined using the standard non-continuous ELISA reference method. In our perception, this assay will improve healthcare by personalizing diagnostics for better clinical outcome and provide real-time feedback on sensing and actuation.

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Graphical abstract Schematic illustration of the microfluidic microsphere based Microfluidic Lab-On-Chip device for near real-time insulin monitoring.

     

Click chemistry-inspired design,synthesis, and molecular docking studies of biscoumarin derivatives using carbon-based acid catalyst

A green and eco-benign synthesis of biscoumarin derivatives using carbon sulfonic acid, a solid support catalyst has been described. The reaction involved a one-pot two-component reaction of 4-hydroxycoumarin and aldehyde using carbon sulfonic acid involving Knoevenegal-Michael condensation. A series of aromatic (bearing electron withdrawing and releasing group) and heteroaromatic aldehydes has been converted to biscoumarins with excellent isolated yields. The reaction is in compliance with green principles, that is, inexpensive catalyst, easy to prepare, nontoxic, easy handling, reusable up to five recycle runs, easy separation, short reaction time, no need of time consuming column purification, high yielding, and so on. The synthesized catalyst and biscoumarin derivatives were well characterized by spectral analysis. The molecular modeling studies showed that the designed molecular scaffolds (3a-j) showed outstanding interaction with methylenetetrahydrofolate reductase (MTHFR) and cytochrome P450 3A4 (CYP3A4) proteins. It was noticed that 3f (−17.55 kJ/mol) and 3d (−26.23 kJ/mol) showed the highest docking score against CYP3A4 and MTHFR proteins, respectively.     

An unexpected directing effect in the asymmetric transfer hydrogenation of α,α-disubstituted ketones

α,α-Disubstituted ketones containing an aromatic ring or alkene are reduced in high enantiomeric excess using an asymmetric transfer hydrogenation catalyst. The sense of reduction indicates that the unsaturated region of the ketone adopts a position adjacent to the Ru-bound η(6)-arene ring in the reduction transition state.     

First-principles study of electronic and magnetic properties of transition metal adsorbed h-BNC2 sheets

Adsorption of Fe, Co and Ni atoms on a hybrid hexagonal sheet of graphene and boron nitride is studied using density functional methods. Most favorable adsorption sites for these adatoms are identified for different widths of the graphene and boron nitride regions. Electronic structure and magnetic properties of the TM-adsorbed sheets are then studied in detail. The TM atoms change the electronic structure of the sheet significantly, and the resulting system can be a magnetic semiconductor, semi-metal, or a non-magnetic semiconductor depending on the TM chosen. This gives tunability of properties which can be useful in novel electronics applications. Finally, barriers for diffusion of the adatoms on the sheet are calculated, and their tendency to agglomerate on the sheet is estimated.     

Competing S(N)2 and E2 reaction pathways for hexachlorocyclohexane degradation in the gas phase, solution and enzymes

Quantum chemistry calculations have been used alongside experimental kinetic analysis to investigate the competition between S(N)2 and E2 mechanisms for the dechlorination of hexachlorocyclohexane isomers, revealing that enzyme specificity reflects the intrinsic reactivity of the various isomers.