Effects of methanol on the hydrogen bonding structure and dynamics in aqueous N-methylacetamide solution

Degradation of Hydrogen Bonds Enormously Enhances Convective Heat Transfer in Nanofluidics

The ultrafast mass transport of liquid through nanochannels holds promising potential to tackle the challenge of thermal management in high-power-density electronic devices. However, convective heat transfer in underpinned nanofluidics-based environments remains elusive. Here, we report with atomistic simulations that the convective heat transfer in nanochannels can be enhanced by ∼50% due to the deterioration of hydrogen bonds subjected to internal stress. The degraded hydrogen bonds largely weaken the intrinsic constraints by local confinement, significantly promoting the mobility of the confined liquid molecules, which facilitates phonon transmission for rapid heat transfer. The internal stress is further elucidated and quantitatively correlated with the convective heat transfer through the development of a thermal-mechanics scaling law that incorporates the Nusselt number and the interaction energy between the nanoconfined liquid and solid. This work provides theoretical insights for designing nanofluidics-based cooling strategies to meet stringent thermal dissipation requirements of high-power-density electronics.

Effects of Hydrogen Peroxide on the Hydrogen Bonding Structure and Dynamics of Water and Its Influence on the Aqueous Solvation of the Insulin Monomer

The hydrogen bond structure and dynamics of water and hydrogen peroxide (H2O2) in their binary mixtures have been studied at 298 K by classical molecular dynamics simulations. Twelve different concentrations of aqueous-H2O2 solutions are considered for this study. We have analyzed the interactions between water and H2O2 by site-site pair correlation functions and observed that the probability of formation of OW···HP hydrogen bonds are higher compared to OP···HW. The second solvation shell of water is strongly affected by increasing H2O2 concentrations (XP > 0.50), which signifies the destruction of the tetrahedral network structure of water. The translational and rotational dynamics of water and H2O2 do not significantly change up to 25% of H2O2 in aqueous mixtures. The hydrogen bond lifetime of water-water, water-H2O2, and H2O2-H2O2 in the aqueous-H2O2 solutions shows a very minimal change with increasing H2O2 concentrations. In addition to this, we also investigated the effect of H2O2 on the insulin monomer and observed that higher concentrations of H2O2 (XP = 0.10) change the secondary structure. The influence of H2O2 is more on chain-B than that on chain-A in the insulin monomer. The H2O2 occupancy at the protein surface is higher for negatively charged (GLU) and polar (ASN and THR) amino acid residues compared with that for positively charged and neutral residues in the solutions.

Removal of methanol from water by capacitive deionization system combined with functional nanoporous graphene membrane

In this article, molecular dynamics simulations were used to examine the feasibility of capacitive deionization (CDI) system combined with a functionalized nanoporous graphene (NPG) membrane for removing methanol from water. The radial distribution function of electrode-methanol and methanol-water, the self-diffusion coefficient of methanol and water, the water density near the membrane, the interaction energy between methanol and membrane, the hydrogen bond structure between methanol and water, and the 2D density map of methanol molecules near the membrane under different electric field (EF) (to simulate the effect of capacitance) were examined to evaluate the separation performance of NPG membranes with hydrogen-passivated pores for methanol. The findings show that an EF with appropriate strength can decrease the amount of water molecules near methanol, increase the self-diffusion coefficient of methanol and water, increase hydrophobicity of hydrogenated pores, decrease the interaction between the NPG membrane and methanol, and weaken hydrogen bond interaction between water and methanol molecules. All these findings suggest that an appropriate EF can improve the NPG membrane's permeability to methanol, and verify the feasibility of CDI system combined with hydrogenated NPG membrane to remove methanol from water. This study is expected to propose a potential CDI application technology, and also give a novel idea for the removal of small organic molecules in water by functionalized NPG membrane.

Identification of phytochemicals from Eclipta alba and assess their potentiality against Hepatitis C virus envelope glycoprotein: virtual screening, docking, and molecular dynamics simulation study

Hepatitis C virus has a major role in spreading chronic liver disease and hepatocellular carcinoma. Factors such as high costs, pharmacological side effects, and the development of drug resistance strains require the development of new and potentially effective antiviral to treat the various stages of Hepatitis C. Bioactive chemicals have been extracted from medicinal plants and are utilized by humans for the goal of maintaining a healthy lifestyle. The goal of this work is to recognize phytochemicals from Eclipta alba and assess their potentiality activity against the hepatitis C virus envelope glycoprotein using in silico approaches. Phytochemicals from Eclipta alba were virtually screened by Auto dock raccoon and 12 compounds were selected for molecular docking to probe the active binding site. The top two compounds based on the binding score like ecliptalbine and oleanolic acid with HCV E2 glycoprotein exhibit binding energy -8.88 and -8.02 kcal/mol, respectively. The chemicals' usefulness was reinforced by positive pharmacokinetic data. The phytocompounds were identified as potent HCV inhibitors based on the drug likeness and ADMET properties. Both ecliptalbine and oleanolic acid underwent molecular dynamics simulations to determine features such as RMSD, RMSF, SASA, hydrogen-bond number, and MM-PBSA-based binding free energy. From the molecular docking and molecular dynamics simulation study revealed that oleanolic acid obtained from Eclipta alba can be used as inhibitors against Hepatitis C. The identified inhibitor from our study will be study in vitro and in vivo studies to check their efficacy against Hepatitis C.Communicated by Ramaswamy H. Sarma.

Per- and poly-fluoroalkyl substance remediation from soil and sorbents: A review of adsorption behaviour and ultrasonic treatment

Per- and poly-fluoroalkyl substances (PFAS) are xenobiotics, present at variable concentrations in soils and groundwater worldwide. Some of the current remediation techniques being researched or applied for PFAS-impacted soils involve solidification-stabilisation, soil washing, excavation and disposal to landfill, on site or in situ smouldering, thermal desorption, ball milling and incineration. Given the large volumes of soil requiring treatment, there is a need for a more environmentally friendly technique to remove and treat PFASs from soils. Sorbents such as granular/powdered activated carbon, ion exchange resins and silicas are used in water treatment to remove PFAS. In this work, PFAS adsorption mechanisms and the effect of pore size, pH and organic matter on adsorption efficacy are discussed. Then, adsorption of PFAS to soils and sorbents is considered when assessing the viability of remediation techniques. Sonication-aided treatment was predicted to be an effective removal technique for PFAS from a solid phase, and the effect of varying frequency, power and particle size on the effectiveness of the desorption process is discussed. Causes and mitigation strategies for possible cavitation-induced particle erosion during ultrasound washing are also identified. Following soil remediation, degrading the extracted PFAS using sonolysis in a water-organic solvent mixture is discussed. The implications for future soil remediation and sorbent regeneration based on the findings in this study are given.

Decelerated Liquid Dynamics Induced by Component-Dependent Supercooling in Hydrogen and Deuterium Quantum Mixtures

Isotopic mixtures of p-H₂ and o-D₂ molecules have been an attractive binary system because they include two kinds of purely isotopic molecules which possess the same electronic potential but the twice different mass inducing differently pronounced nuclear quantum effects (NQEs). Accessing details of structures and dynamics in such quantum mixtures combining complex molecular dynamics with NQEs of different strengths remains a challenging problem. Taking advantage of the nonempirical molecular dynamics method which describes p-H₂ and o-D₂ molecules, we found that the liquid dynamics slows down at a specific mixing ratio, which can be connected to the observed anomalous slowdown of crystallization in the quantum mixtures. We attributed the decelerated dynamics to the component-dependent supercooling of p-H₂ taking place in the mixtures, demonstrating that there is an optimal mixing ratio to hinder crystallization. The obtained physical insights will help in experimentally controlling and achieving unknown quantum mixtures including superfluid.

Synthesis of 5-(5-methyl-benzofuran-3-ylmethyl)-3H- [1, 3, 4] oxadiazole-2-thione and investigation of its spectroscopic, reactivity, optoelectronic and drug likeness properties by combined computational and experimental approach

This paper reports the synthesis of 5-(5-methyl-benzofuran-3-ylmethyl)-3H- [1, 3, 4] oxadiazole-2-thione (5MBOT) and characterization by FT-IR, FT-Raman, ¹H NMR, ¹³C NMR and UV spectral studies. The density functional theory (DFT) calculations have been executed for the 5MBOT using B3LYP/6-31++G (d, p) basis set. The fundamental modes of the vibrations were designated by the potential energy distribution (PED), and the computed and experimental values support each other. The ¹H NMR and ¹³C NMR chemical shifts of 5MBOT were estimated by gauge-including atomic orbitals (GIAO) method and compared with the experimental chemical shifts. The UV-Vis method used to study the visible absorption maxima (λ_max) by using Time-Dependent DFT. Further, the Mulliken population analysis (MPA), natural population analysis (NPA) charges, thermodynamic properties at different temperatures were presented. The calculated HOMO and LUMO energies show that charge transfer within the molecule. The natural bonds orbital (NBO) also computed. Optoelectronic properties have been carried out by combination of DFT calculations and molecular dynamics (MD) simulations, in order to assess the potential of this structure for applications in organic electronics. Further, the study encompassed calculations of reorganization energies for holes and electrons and charge transfer rates. DFT calculations have been also used in order to identify locations possibly sensitive towards the autoxidation mechanism, which correlates between bond dissociation energy for hydrogen abstraction and the mechanism. The MD simulations have been used to understand interaction of 5MBOT with water molecules. Molecular docking studies reveals the antifungal activity of 5MBOT may be due to hydrogen bonding and hydrophobic interactions with different antifungal proteins.