Differences In Interaction Energies Research Articles

Modulation of the intermolecular interactions of cucurbit[7]uril with phenylalanine derivatives by the functional groups

Abstract Intermolecular interactions in 1:1 inclusion complexes of cucurbit[7]uril (CB[7]) with phenylalanine derivatives were investigated by density functional theory (B97-D) calculations. For each complex, 2 optimized geometries were found: conformer C in which a guest molecule resided in the center of CB[7], and conformer E where a guest molecule was present at the edge of CB[7]. The order of energy differences between these conformers agreed well with previously reported differences in the affinity of guest molecules for CB[7]. Molecular dynamics simulations of the complexes showed that the guest molecules in CB[7] had different stabilities, and the calculated binding free energies between them also qualitatively agreed with the experimental results. Pair-interaction energy decomposition analyses of the complexes at FMO-MP2/6-31G(d) and aug-cc-pVDZ level of theory were performed using snapshot structures at 500 ns of simulations. The dispersion interaction characterized the interaction, and the order of total interaction energies between the guest molecules and CB[7] was also associated with the experimental results. A significant difference in electrostatic interaction energies was observed in conformer E, which was correlated with the stability of the guest molecules at the edge of CB[7]. The balance between the stabilities of these conformers was correlated with the affinity of guest molecules for CB[7].

Exploring ionic liquids for the extraction separation of aromatic hydrocarbons from diesel via multiple interaction analyses coupled with experimental evaluation

The separation of aromatic hydrocarbons from petroleum fractions is of great significance for both the quality upgrading of products and value-added utilization of aromatic compounds. However, the separation of polycyclic aromatic hydrocarbons (PAHs) and their derivatives from diesel remains challenging because of their lower solubility and selectivity as compared to the monocyclic aromatic compounds. In this work, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TF2N]) was screened from 320 ionic liquid (IL) candidates through solvent capacity predication using COSMO-RS method. Liquid-liquid equilibrium experiments were carried out using a series of tetralin/n-decane mixtures with different tetralin concentrations to evaluate the extraction performance of several solvents. The results indicate that [EMIM][TF2N] has high selectivity up to 95.73 for tetralin over n-decane, which is 4.5 and 3.9 times higher than that of dimethyl sulfoxide and sulfolane. During five regeneration cycles, the [EMIM][TF2N] exhibits consistent extraction performance and nearly complete recovery. Molecular polarity index (MPI) analysis indicates that tetralin has larger dissolving affinity to solvents as compared to n-decane. Combined analyses of interaction energy, energy decomposition, and visualization of weak interaction reveal that the crucial role of weak hydrogen bond in dominating the complex solvent–solute interactions. Compared to n-decane, tetralin shows a stronger interaction with the solvents due to the existence of C-H···π and hydrogen bond interactions. The great difference in interaction energy between {[EMIM]+ + tetralin} and {[EMIM]+ + n-decane}, therefore, endows [EMIM][TF2N] with high selectivity for tetralin. Given the dominant role of cation, a IL, [CN1 = C2SCCS2(CC = C)C1][TF2N] having both high selectivity and high solvent capacity was subsequently explored using the cation generation method based on the SeqVAE model. Furthermore, present study proposes a strategy for the design of ILs for separation and other specific application circumstances.

Molecular dynamics simulation on asphalt-limestone interfaces considering unconstraint surfaces and individual colloid components

In molecular dynamics (MD) simulation, interactions of asphalt-limestone interfaces are investigated inaccurately because applying of constraint aggregate surfaces simplify some kinetic energies. Utilizing unconstrained aggregate surfaces provides a novel insight to understand the intermolecular effect of displacement of unconstrained particles. The influence of mineral structures containing Mg2+ other than calcite on adhesion are also ignored. This study builds various unconstraint surfaces and individual colloid components to reasonably evaluate adhesion and interaction by calculating energy, diffusion, and distribution of asphalt-limestone interfaces. Simulations reveal that asphalt-limestone interactions intensify with aging and higher temperatures. Polarity, primarily from sulfoxide (SO) and carbonyl (CO) groups after aging, amplifies adhesion by enhancing electrostatic forces. Individual SARA (saturate, aromatic, resin, asphaltene) components exhibit higher interaction energies with limestone, and differences in interaction energies of SARA on limestone surfaces cause separation in asphalt. Ca2+ and Mg2+ mainly combine with CO32- ions via ionic binding, forming stable surfaces unaffected by asphalt. The mineral composition has a limited impact on asphalt-limestone interfaces, although magnesite displaying the highest attraction to asphalt due to greater electronegativity of Mg2+. Inside asphalt molecules, polar CO and SO groups and planar sharps exhibit strong attraction to aromatic rings, increasing intermolecular energies and cohesion. Self-agglomeration and stacking of asphaltenes, driven by π-π conjunctions in central-aromatic rings and reinforced by aging.

Mechanism and Stereoselectivity Control of Terminal Alkyne Dimerization Activated by a Zr/Co Heterobimetallic Complex: A DFT Study.

Heterobimetallic complexes have recently garnered considerable attention in organic synthesis owing to their high activity and selectivity, which surpass those of monometallic complexes. In this study, the detailed mechanisms of terminal alkyne dimerization activated by the heterobimetallic Zr/Co complex, as well as the different stereoselectivities of Me3SiC≡CH and PhC≡CH dimerization, were investigated and elucidated by using density functional theory calculations. After excluding the three-molecule reaction and outer-sphere mechanisms, the inner-sphere mechanism was determined as the most optimal process. The inner-sphere mechanism involves four processes: THF dissociation and coordination of the first alkyne; ligand migration and C-H activation; N2 dissociation and insertion of the second alkyne; and reductive elimination. The stereoselectivity between the E-/Z- and gem-isomers is determined by the C-C coupling mode of the two alkynes and that of the E- and Z-isomers is determined by the sequence of the C-C coupling and hydrogen migration in the reductive elimination process. Me3SiC≡CH dimerization yields only an E-isomer owing to the large differences in the distortion and interaction energies, whereas PhC≡CH dimerization produces an E-, Z-, and gem-isomers owing to the reduced interaction energy differences.

Molecular mechanism-based extractant screening and process design for the separation of methanol/dimethyl carbonate azeotrope

The separation of methanol/dimethyl carbonate azeotrope is an important process in the industrial production of dimethyl carbonate. Extractive distillation is an effective separation method, which can ensure the full utilization of resources and achieve sustainable development. In this work, an extractant screening method based on density functional theory (DFT) was proposed. By comparing the interaction energy difference, the optimal extractant (dimethyl sulfoxide, DMSO) was obtained. The molecular mechanism of action between the extractant and the separated components was explained. The separation order of the components of the extraction distillation process was obtained by the magnitude of the interaction energy. The σ-profile curve and isovolatility curves method were used to verify the effectiveness of the proposed method. A new separation process with DMSO as an extractant was designed. With the lowest total annual cost (TAC) as the goal, sensitivity analysis and cyclic iteration method is used to optimize the parameters involved in the process to determine the best process parameters. Heat integration technology is introduced to further reduce energy consumption. TAC, energy utilization efficiency, and global warming potential (GWP) were used to evaluate the process. Compared with the reported optimal extractant methyl salicylate, the TAC of the simple process using DMSO as the extractant was reduced by 9.08%. The heat-integrated process with DMSO shows a TAC reduction of 17.17% compared to the simple process. And the energy utilization efficiency and GWP were increased by 40.90% and decreased by 31.88%, respectively. The results show that the extractant screened by DFT method is applied to the azeotrope separation, which makes the process have good economic benefits, low energy consumption, and less environmental impact.

Intrinsic disorder in the dynamic evolution of structure, stability, and flexibility of potyviral VLP assemblies: A computational study

An all-atom Molecular Dynamics (MD) study was applied to three viral nanoparticles (VLPs) of Turnip mosaic virus (TuMV), a potyvirus: the particles genetically functionalized with two peptides, VIP (human vasoactive intestinal peptide) and VEGFR (peptide derived from the human receptor 3 of the vascular endothelial growth factor), and the non-functionalized VLP. Previous experimental results showed that VIP-VLP was the only construct of the three that was not viable. VLPs subjected to our MD study were modeled by four complete turns of the particle involving 35 subunits of the coat protein (CP). The MD simulations showed differences in structures and interaction energies associated to the crucial contribution of the disordered N-terminal arms of CP to the global stability of the particle. These differences suggested an overall stability greater in VEGFR-VLP and smaller in VIP-VLP as compared to the unfunctionalized VLP. Our novel MD study of potyviral VLPs revealed essential clues about structure and interactions of these assembled protein particles and suggests that the computational prediction of the viability of VLPs can be a valuable contribution in the field of viral nanobiotechnology.

Effect mechanism of wettability on CO2 replacement brine in nanopores

The mechanism of using CO2 to replace brine in nanopores is still unclear, and the influence of the wettability of pore walls on the interfacial effect needs to be improved. In this study, the effect of wettability in tight sandstone reservoirs on CO2 replacement brine in nanopores was probed through molecular dynamics simulations. The results showed that the replacement front of CO2 molecules was meniscus shaped in hydrophilic and amphipathic systems, while it advanced as a whole in lipophilic systems. When CO2 replaced brine in nanopores, the interaction energies of the H2O and CO2 molecules near the pore walls with the pore walls were much greater than those of molecules in the centers of the pore channels·H2O molecules had strong interactions with the hydroxyl groups on the pore walls but weak interactions with the methyl groups on the pore walls, while CO2 molecules had strong interactions with both hydroxyl and methyl groups. Water films were always present on the hydrophilic pore walls to separate CO2 molecules from the pore walls, while the H2O molecules could be basically replaced in the lipophilic pore channels. CO2 molecules could easily strip the H2O molecules around the hydrophobic groups on the amphipathic pore walls, but they could not replace the H2O molecules around the hydrophilic groups on the amphipathic pore walls. During the process of CO2 replacement brine in nanopores, the interaction energies of the H2O molecules with pore walls dominated in hydrophilic and amphipathic systems, which were much greater than the energies of the CO2 molecules with H2O molecules and the CO2 molecules with pore walls. However, in the lipophilic system, the difference in interaction energy between different components was less. The results of this research could serve as a reference for understanding the mechanism of CO2 storage in tight sandstone reservoirs.

Orthogonal Inverse-Electron-Demand Cycloaddition Reactions Controlled by Frontier Molecular Orbital Interactions.

Chemoselective pairs of bioorthogonal reactants enable the simultaneous labeling of several biomolecules. Here, we access orthogonal click reactions by exploiting differences in frontier molecular orbital interaction energies in transition states. We establish that five-membered cyclic dienes are inert to isonitriles but readily react with strained alkynes, while tetrazines with bulky substituents readily react with isonitriles. Strained alkynes show an opposite reactivity pattern. The approach was demonstrated by orthogonally labeling two proteins with different fluorophores.

Selectivity and permeability of gas separation in SILMs: Effect of collapsed structure

In this work, the influence of the intramembrane structure of SILMs on gas separation was demonstrated by molecular dynamics simulations. The five morphological characteristics of separation membranes bring different separation effects. For the selection process, interfacial characteristics have a significant effect on the selectivity by the analysis of density and energy barrier. The difference in the blocking effect on CO2 is the key to the separation. For the permeation process, the analysis of free volume and interaction energy revealed that the residence time and penetration of gas molecules in membranes are sensitive to distribution characteristics of ionic liquids. Lastly, the interaction energy and pressure difference were analyzed to reveal the influence of the membrane structure on the persistence of separation and flow interruption. This work can provide theoretical support for the high efficiency control of membrane separation and the development of two-dimensional membrane materials.

Spectroscopic study of cooperative states of Nd3+ pair centers in fluorite-type crystals: A competition of dipole-dipole and quadrupole-quadrupole energy exchange

Pair centers of Nd3+ ions in the CdF2, CaF2, and SrF2 doped crystals at T=6.5K were studied under tunable narrow-linewidth laser excitation. It has been established that the exchange of electronic excitation leads to the splitting of the one-exciton cooperative 4G5/2(1) x 4I9/2(1) state by 2–3 cm−1 with a non-monotonic dependence on the distance between the ions in the pairs in these crystals. This dependence is explained by the competition of forced dipole-dipole and quadrupole-quadrupole interactions with spin flip. The high rate of such exchange mechanisms is due to strong spin–orbit interaction and small energy difference between the 4f levels of Nd3+ ions. It is shown that the pair centers in all one-exciton cooperative states, in contrast to the ground and two-exciton excited states, have nonzero static dipole moments. This makes it possible to use the latter states as ultrafast qubits, and one-exciton states as control qubit to implement a CNOT quantum gate.

Experimental and mechanistic study of bio-based solvent Cyrene for de-aromatization of model diesel

Liquid-liquid extraction is an important technique for separating aromatic and alkane hydrocarbons. The toxicity and pollution problems of traditional solvents are difficult to solve, and the use of green bio-based solvents for diesel fuel dearomatization is of great significance to solve energy and environmental problems. In this paper, Cyrene, a low toxicity, low cost, green composition bio-based solvent, was selected as an extractant to study its ability to remove mono- and bicyclic aromatics from chain alkanes and cycloalkanes, respectively. In addition to the ternary system, the extraction effects under various experimental conditions and multi-component simulated systems were also investigated. The results showed that aromatics and cyclic structures tend to interact more strongly with Cyrene due to differences in solute structure, and therefore polycyclic aromatic hydrocarbons tend to produce larger distribution coefficients. the selectivity coefficients of Cyrene for the four systems were influenced by differences in interaction energies in the order: dodecane/1-methylnaphthalene > dodecane/indene > decahydronaphthalene/1-methylnaphthalene > decahydronaphthalene/indene. At the same time, multi-component simulated oil experiments have demonstrated that Cyrene is equally selective in removing aromatic hydrocarbons from complex components. Quantum chemical calculations were used to investigate the extraction mechanism of Cyrene. The results of Reduced Density Gradient (RDG), Atoms In Molecules (AIM), and Symmetry-Adapted Perturbation Theory (SAPT) energy decomposition proved that the interaction forces between Cyrene and solute molecules are van der Waals forces dominated by dispersion forces and accompanied by some very weak hydrogen bonds. Finally, thermodynamic correlations using the NRTL model were performed to obtain binary interaction parameters for the four systems. The results of this paper indicate that Cyrene, as a new green bio-based solvent, has the potential to be used as an extractant and shows good separation in the removal of long carbon chain aromatic hydrocarbons, and this paper also provides basic data and references for subsequent studies.

Exploring structural and dynamical properties of polymer-ionic liquid ternary electrolytes for sodium ion batteries

This work investigates the ion transport mechanisms in binary and ternary electrolyte systems based on polymers and ionic liquids for Na-ion batteries. Molecular dynamics (MD) simulations were performed on poly(ethylene oxide) (PEO) and ionic liquids (IL) based electrolytes, bis(trifluoromethanesulfonyl)imide (TFSI)/N-methyl-N-propylpyrrolidinium (Pyr13) and bis(fluorosulfonyl)imide (FSI)/Pyr13, varying the composition at 0, 5, 10 and 20 wt% over a range of temperatures from 313 to 400 K. The simulations could satisfactorily reproduce the experimental densities and trends in diffusivities and conductivity data. It was observed that there exists a stronger interaction between sodium ions and the FSI anions as compared to the TFSI counterparts, correlated to a difference in interaction energy between the ionic species. This controls how well the different ILs act as plasticizers for the Na-PEO system, with TFSI actually displaying lower conductivity for low IL loadings while the conductivity increases continuously for the FSI counterparts. Moreover, the simulations show that the sodium ions interact more strongly with the polymer at lower temperatures, leading to a lower polymer free volume which explains the trends in ionic transport. Thereby, these MD simulations unveil an interplay between the coordination chemistry and the dynamic properties in these ternary polymer-ionic liquid-salt electrolytes, and how the coordination strength controls the conductive properties.

Organic Persistent RTP Crystals: From Brittle to Flexible by Tunable Self-Partitioned Molecular Packing.

Aiming to solve trade-off of "RTP-flexibility" in principle, organic room temperature phosphorescence (RTP) crystals with elastic/plastic deformation have been realized. These properties are mainly due to the divisional aggregation structures of aromatics and alkoxy chains, and can be modulated by the controllable molecular configurations. The longest RTP lifetime of 972.3ms has been achieved as the highest record for organic flexible crystals. The plastic crystals with persistent RTP were realized for the first time, which can be applied into biomedical optical technologies by afterglow delivery. Moreover, relationship among elastic/plastic deformation, RTP property and aggregated structures have been established. Elastic/plastic deformation is mainly determined by difference of interaction energies from aromatics and alkoxy chains. For BP-OR series with twisted configurations, the alkoxy chain with the middle length is favorable for RTP property, while the strength of π-π coupling is the cruical factor to RTP property of Xan-OR series with planar skeletons. It explored a new way to promote the development of flexible RTP crystals, by modulation of aggregated structures as well as rational distribution of intermolecular interactions. This article is protected by copyright. All rights reserved.

The interface design and properties enhancement of ZnO/cellulose composites: Branching fiber network to guide the assembly of ZnO flower

Using renewable biomass resources to regulate the growth and properties of catalysts is sustainable nanotechnology for achieving efficient photocatalysis and recycling. This work suggested a way to produce paper-based photocatalysts and resize the embedded zinc oxide (ZnO) flowers. The combination of experimental analysis and theoretical simulations demonstrated that small pores of the branching fiber network enhanced the interfacial interaction between ZnO flowers and cellulose fibers, thereby improving mechanical properties and optimizing flower structure. The interaction energy and electron density difference (EDD) simulation results demonstrated that the ZnO/cellulose interface structure shares significant attraction and charge transfer. Cellulose fibers ground for 20 cycles (CFG20) possessed dense branching fiber network and loaded with the smallest ZnO flowers, achieving a balance of strong mechanical properties and reaction efficiency. Remarkably, ZnO/CFG20 paper-based catalyst indicated strong photodegradation efficiency (100% for methyl orange, 100% for phenol, and 85.23% for aniline) and excellent reusability. This work will pave the way for the green regulation of catalysts.

Accuracy of Noncovalent Interactions Involving d-Elements by the 1-Determinant Fixed-Node Diffusion Monte Carlo Method with Effective Core Potentials.

A critical assessment of effective core potential (ECP)-based single-determinant (SD) fixed-node diffusion quantum Monte Carlo (FNDMC) accuracy in prototypical noncovalent closed-shell systems involving d-elements is presented. Careful analysis of biases and elimination of possible bias sources leads to two findings of practical importance for SD FNDMC in these systems. First, in some systems (HCu:HCu, HCu:CuH), SD FNDMC reveals large biases of interaction energy differences (significantly exceeding the target 2% relative error) vs a reliable coupled-cluster CCSD(T)/CBS (complete basis set) reference. Second, the leading error of SD FNDMC with ECPs was attributed to a higher nuclear charge Z of d-group (pseudo) atoms, when compared to sp elements, in line with a previously reported finding that aggregate SD FNDMC bias tends to increase in systems with higher electronic densities. Therefore, SD FNDMC should only be used with caution in systems with a large Z.

Liquid–liquid equilibrium and mechanism study on separation of short carbon chain hydrocarbon mixtures by Cyrene

AbstractThe separation of short‐chain hydrocarbon mixtures is of great significance for the efficient utilization of fossil energy. Liquid–liquid extraction, as one of the commonly used treatment methods, has significant advantages in terms of operation conditions and energy consumption. As a new dipolar aprotic solvent developed in recent years, dihydrolevoglucosenone (Cyrene) has a wide range of sources and a green composition. In this paper, the liquid–liquid equilibrium and extraction mechanism of Cyrene and five hydrocarbon mixtures with short carbon chains, including toluene/n‐heptane, toluene/cyclohexane, n‐hexane/cyclohexane, n‐pentane/pentene, and n‐hexane/hexene, have been studied by combining experiments and quantum chemical calculations, and the extraction effects under different conditions have been investigated. The results showed that the forces between Cyrene and the different solutes are mainly van der Waals (VDW) forces dominated by dispersion forces, with some weak hydrogen bonds present. Due to the difference in interaction energy, the order of extraction selectivity was toluene‐n‐heptane > toluene‐cyclohexane > n‐hexane‐hexene > n‐hexane‐cyclohexane > n‐pentane‐pentene, and the order of distribution coefficients of the extracted components (aromatics, olefins, and cycloalkanes) was toluene > pentene > hexene > cyclohexane. The dissolution processes of all systems were heat‐absorbing, and they all reached the extraction equilibrium within 60 s. The reliability of the experimental data was verified using the Othmer–Tobias equation and the Hand equation, and the binary interaction parameters of all systems were obtained by the non‐random two liquid (NRTL) model, providing basic data and references for the subsequent studies on the separation of Cyrene and short‐chain hydrocarbons.

Screening method and mechanism of ionic liquid as extractant in fuel extraction desulfurization process

AbstractBackgroundIn the production of ultra‐low sulfur fuels, the use of extraction processes to remove sulfides from the fuel has various advantages. The selection of a suitable extractant is key to the extraction process. Ionic liquids (ILs) are known as green solvents and are designable, but there is a wide variety. In this study, an IL screening method was developed based on a conductor‐like screening model‐segment activity coefficient (COSMO‐SAC) model and a fuzzy comprehensive evaluation model. In addition, the feasibility of the method was verified by fuel extraction desulfurization experiments. Finally, the separation mechanism was explored through intermolecular interactions.ResultsIn this study, suitable extractants were screened from 2400 ILs with 24 anions and 100 cation combinations. Based on the results of the fuzzy comprehensive evaluation model, five ILs were selected; 1‐hexyl‐3‐methylimidazolium hexafluorophosphate ([HMIM][PF6]) was selected as the extractant and the single desulfurization rate could reach 72.74%. After four desulphurization experiments, the sulfur content in the model oil decreased from 1200 to 6.98 μg/g. The interaction energy difference between [HMIM][PF6] + BT and [HMIM][PF6] + OC (ΔE = ‐12.8662 kJ·mol−1) is higher than those of the other four extractants.ConclusionThe feasibility of the screened method was verified by the extraction desulfurization experiment. [HMIM][PF6] was selected as the most suitable extractant. Furthermore, by analyzing the weak interaction between ILs and benzothiophene (BT) and n‐octane (OC), it was found that weak hydrogen bonds (HBs) and π–π interactions between [HMIM][PF6] and BT play important roles in the extraction process. © 2022 Society of Chemical Industry (SCI).

Nitrogenated Holey Graphene (C2N-h2D): An excellent sensor for neurotransmitter amino acids

Interactions of amino acids with organic surfaces are highly relevant to the development of modern synthetic biomaterials with biocompatibility and low biotoxicity. Biomolecule-surface interactions vary differently according to the molecule orientation, charge state, and distance from the surface. Furthermore, the electron transfer through molecule/surface could also play a key role in biological recognition and signaling systems. Here, using density functional theory (DFT), we investigated the interactions of three neurotransmitter amino acids (NAAs), namely, glycine (Gly), γ-aminobutyric acid (Gaba), and glutamate (Glu), onto a nanosheet of holey nitrogenated graphene (C2N-h2D). In general, the interactions between amino acids and carbon-based surfaces are mediated through weak van der Waals interactions. However, based on interaction energy and charge density difference calculations, there is a strong physisorption process between NAAs and the C2N structure. In particular, Gaba and Glu can act as exclusive electron donor and acceptor, respectively. Our calculations also reveal that, by changing the orientations from neutral to zwitterionic, the Gly molecule changes from a donor to a strong acceptor of electrons. In the case of electron donation, the resistivity on the C2N surface should be reduced. These findings indicate that the C2N surface is an excellent candidate for high-performance biosensor applications. From the band structure point of view, the NAAs molecules introduce occupied flat bands within the bandgap of the C2N single layer, while the surface energy levels keep the bulk characteristics of the semiconductor system. Finally, the optical absorption spectrum of NAAs-C2N systems reveals that these NAAs seem to improve the photoactivity performance of the C2N structure, with the appearance of intraband transitions.

A Peculiar Binding Characterization of DNA (RNA) Nucleobases at MoOS-Based Janus Biosensor: Dissimilar Facets Role on Selectivity and Sensitivity.

Distinctive properties of Janus monolayer have drawn much interest in biotechnology applications. For this purpose, it has explored theoretically all sensing possibilities of nucleobases molecules (DNA/RNA) by Janus MoOS monolayer on both oxygen and sulfur terminations by means of rigorous first–principles calculation. Indeed, differences in interaction energy between nucleobases indicate that a monolayer can be used for DNA sequencing. Exothermic interaction energy range for DNA/RNA molecules with both oxygen and sulfur sides of the Janus MoOS surfaces have been found to range between (0.61–0.91 eV), and (0.63–0.88 eV), respectively, and the binding distances indicate that these molecules bind to both facets by physisorption. The exchange of weak electronic charges between the MoOS monolayer and the nucleobases molecules has been studied by means of Hirshfeld-I charge analysis. It has been observed that the introduction of DNA/RNA nucleobases molecules alters the electronic properties of both oxygen and sulfur atomic layers of the Janus MoOS complex systems as determined by plotting the 3D Kohn–Sham frontier orbitals. A good correlation has been found between the interaction energy, van der Waals energy, Hirshfeld-I, and d–band center as a function of the nucleobase’s affinity, and the interaction energy, suggesting adsorption dominated by van der Waals interactions driven by molybdenum d–orbital. Moreover, the lowering in the adsorption energy leads to an active interaction of the DNA/RNA with the surfaces, accordingly its conduct to shorter the recovery time. The selectivity of the biosensor modulation device has illustrated a significant sensitivity for the nucleobases on both the oxygen and sulfur layer sides of the MoOS monolayer. This finding reveals that apart from graphene, dichalcogenides–Janus transition metal may also be adequate for identifying DNA/RNA bases in applied biotechnology.

Influence of elasticity on the morphology of fcc-Cu precipitates in Fe-Cu alloys. A phase-field study

Cu-rich precipitation ensures high strength and satisfactory ductility of steels at low carbon content. Although in an over-aged state, it leads to the degradation of mechanical properties. It is of prime importance for nuclear reactor vessel steels, which are exposed to extreme conditions at elevated temperature for a long time. The precipitates at this state have an fcc structure and possess a characteristic elongated morphology. The invariant-line model was mostly used to explain the morphology of fcc-Cu precipitates in the bcc-Fe matrix, although it has several limitations. It idealizes morphology and does not consider the elastic properties of both precipitate and matrix. Also, this method does not reveal the influence of the eigenstrains on kinetics and the formation of the nanostructure. Besides, the influence of the applied stress on the precipitation process can’t be revealed with this method.With this in mind, we developed a phase-field model to investigate the formation of the elongated morphology of fcc-Cu precipitates in the bcc-Fe matrix. The effect of diffuse interface and discretization on the behavior of solution was verified with a sharp-interface model and invariant-line prediction. It was found that simulated precipitates agree qualitatively with available experimental data. The role of a minimal mismatch line on the morphology formation was verified. Also, it was shown that the anisotropy of elastic properties has a minor effect on morphology formation. The applied stress with different magnitudes and directions has a minor effect on the morphology of precipitates. Nevertheless, it results in variant selection due to the difference in interaction energy. The bifurcation diagram of interaction of two precipitates was constructed. The equilibrium configurations reveal that elasticity enhances the kinetics of the reaction and that there is a twin-like configuration, which enhances the accommodation of shear-like eigenstrain and reduces the elastic interaction energy.