Strong Attractive Interaction Research Articles

Colourful organic afterglow materials with super-wide color gamut and scaled processability from cellulose

Multi-colour afterglow materials have attracted widespread attention recently, because they not only can eliminate the interference of scattered light and background fluorescence, but also store the richer information. In this work, the phosphorescence emission of cellulose-based nitrogen-doped carbon dots (CDs) was transferred to the rhodamine derivatives via an efficient radiative energy transfer process, because of the strong electrostatic attraction interactions between the positive charged CDs and the negative charged rhodamine derivatives. As a result, multi-color afterglow luminescence with tunable emission and wide color gamut was realized from blue-green to green, yellow, orange and red. With the contribution of the excellent processability of polymer materials, multi-color afterglow films, coatings, fibers and patterns were readily obtained, indicating a practical application in advanced anti-counterfeiting and multiple-mode information encryption. Such a facile, universal and efficient strategy to construct multi-colour afterglow materials inspires us to understand the luminescence process and design novel afterglow materials.

Floquet-engineered pair and single-particle filters in the Fermi-Hubbard model

We investigate the Fermi-Hubbard model with a Floquet-driven impurity in the form of a local time-oscillating potential. For strong attractive interactions a stable formation of pairs is observed. These pairs show a completely different transmission behavior than the transmission that is observed for the single unpaired particles. Whereas in the high frequency limit the single particles show a maximum of the transition at low driving amplitudes, the pairs display a pronounced maximum transmission when the amplitude of the driving lies close to the ratio of the interaction U and the driving frequency {\omega}. We use the distinct transmission behaviour to design filters for pairs or single particles, respectively. For example one can totally block the transmission of single particles through the driven impurity and allow only for the transmission of pairs. We quantify the quality of the designed filters.

Strong tunable phonon-phonon interactions induced by silicon-vacancy centers in one-dimensional chiral phononic waveguides

In solid quantum systems, strong phonon-phonon repulsive or attractive interactions are difficult to achieve. The highly adjustable phonon-phonon interactions created by silicon-vacancy (SiV) centers in a one-dimensional chiral phononic waveguide are investigated in this paper. Under specific situations, phonon-phonon attractive or repulsive interactions between the chiral transport phonons are created when they are scattered by two-level or three-level structural SiV centers. Furthermore, by modulating the laser Rabi frequencies and detunings, the resultant attractive or repulsive interactions between phonons can be adjusted over a large frequency range. Single-phonon creation and phonon manipulation in solid acoustic quantum information processing could benefit from the tunable phonon-phonon interactions.

Assembly of partially covered strawberry supracolloids in dilute and concentrate aqueous dispersions

HypothesisCore-corona supracolloids can be assembled in aqueous dispersions by controlling the physical interactions between the corona and core colloidal particles. A raspberry corona configuration with full surface coverage of the core can be reached by inducing strong attractive interactions between the individual particles. A controlled partial surface coverage of the core, i.e. strawberry configuration, is however, more difficult to achieve. Supracolloids with different surface coverage ratio exhibit unique and multifunctional surface properties. ExperimentsBy counterbalancing the multiple physical interactions playing a role during the assembly, the configuration and stability of the assemblies could be fine-tuned over a wide range of concentrations. Supracolloids consisting of polyethylene glycol (PEO)-grafted polymer particles covered by silica nanoparticles were assembled with different configurations, by adjusting the pH and ionic strength of the dispersion, the PEO grafting density and the particles concentration. The self-assembly process and resulting configurations were monitored via cryogenic transmission electron microscopy (Cryo-TEM) and light scattering. FindingsThe suitable conditions to assemble supracolloids with partial corona coverage have been established. Stable strawberry supracolloids could be prepared, both for diluted (1 wt%) and concentrated (12 wt%) dispersions. These hybrid supracolloids with well-defined configuration are highly relevant to developing advanced water-borne paints and inks, food dispersions, cosmetic and healthcare products.

Enhanced electrochemical performance of the LiNi0.8Co0.1Mn0.1O2 cathode via in-situ nanoscale surface modification with poly(imide-siloxane) binder

The Ni-rich layered oxide cathode (LiNi0.8Co0.1Mn0.1O2, NCM811) suffers from serious interfacial side reactions and phase transition during high-voltage cycling (4.7 V), causing the poor rate capability and sharp capacity fading. Herein, a beneficial strategy is proposed, combining rigid/flexible chains, to exploit an endurable poly(imide-siloxane) (PIS) binder with transitable ion channel by structural tailoring and copolymerization. The in-situ formed nanoscale PIS layer on the NCM811 particle surface provides stern resistance to extreme conditions and strong attractive interactions, which enable a firm cathode-electrolyte interface and facile ion transfer path during charge-discharge process. The fabricated PIS-based cathodes under 4.3 V cutoff voltage exhibit higher capacity retention (83% vs. 69%, 1.0C, 500 cycles) and higher rate capacity (137.6 mAh g−1 vs. 123.6 mAh g−1, 5.0C), in contrast to the cathodes with polyvinylidene fluoride (PVDF) binder. Further test under 4.7 V cutoff voltage indicates the rate capacity of PIS-based cathodes is superior than that of PVDF-based cathodes (163.2 mAh g−1 vs. 119.7 mAh g−1, 5.0C), as well as superior capacity retention (74 % vs. 34%, 0.2C, 100 cycles). This work provides a valuable guideline for designing a polymer binder by focusing on stabilizing high-voltage cathode structure and facilitating ion diffusion.

The chemical environment and structural ordering in liquid Mg-Y-Zn system: An ab-initio molecular dynamics investigation of melt for the formation mechanism of LPSO structure

In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy, the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation. In liquid Mg-rich Mg-Y alloys, the strong Mg-Y interaction is determined, which promotes the formation of fivefold symmetric local structure. For Mg-Zn alloys, the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure. Due to the coexistence of Y and Zn, the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy, and contributes to the clustering of Mg, Y, Zn launched from Zn. What is more, the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys. These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure, which provides a new insight into the formation mechanism of LPSO structure at atomic level.

Analysis of nanocellular foaming with nucleating agents based on coarse-grained molecular dynamics simulations

Nanoscale foaming using nucleating agents was modeled based on coarse-grained molecular dynamics simulations to analyze the nucleation and growth of nanocellular foams. Interactions between the polymer chains and nucleating agents, the blowing rate, and the number of nucleating agents were varied, and foam formation was analyzed. Snapshots of the simulated foamed structures were obtained and characteristic parameters—such as the number of foams and the size distribution of the foams—were estimated. In the case of weak attractive interactions between the polymers and nucleating agents, foams formed first at the interfaces of the polymers and nucleating agents, then formed in the polymer matrix. In the case of strong attractive interactions, foams originated only in the polymer matrix. These nucleation-type foams depended on the number and size of the foams, and on their growth and coalescence. Our simulations indicate that the foamed structures can be modulated by the following parameters: interactions between the polymer chains and nucleating agents, the blowing rate, and the number of nucleating agents.

Nonpolarizable Force Fields through the Self-Consistent Modeling Scheme with MD and DFT Methods: From Ionic Liquids to Self-Assembled Ionic Liquid Crystals.

A key to achieve the accuracy of molecular dynamics (MD) simulation is the set of force fields used to express the atomistic interactions. In particular, the electrostatic interaction remains the main issue for the precise simulation of various ionic soft materials from ionic liquids to their supramolecular compounds. In this study, we test the nonpolarizable force fields of ionic liquids (ILs) and self-assembled ionic liquid crystals (ILCs) for which the intermolecular charge transfer and intramolecular polarization are significant. The self-consistent modeling scheme is adopted to refine the atomic charges of ionic species in a condensed state through the use of density functional theory (DFT) under the periodic boundary condition. The atomic charges of the generalized amber force field (GAFF) are effectively updated to express the electrostatic properties of ionic molecules obtained by the DFT calculation in condensed phase, which improves the prediction accuracy of ionic conductivity with the obtained force field (GAFF-DFT). The derived DFT charges then suggest that the substitution of a hydrophobic liquid-crystalline moiety into IL-based cations enhances the charge localization of ionic groups in the amphiphilic molecules, leading to the amplification of the electrostatic interactions among the hydrophilic/ionic groups in the presence of hydrophobic moieties. In addition, we focus on an ion-conductive pathway hidden in the self-assembled nanostructure. The MD results indicate that the ionic groups of cation and anion interact strongly for keeping the bicontinuous nanosegregation of ionic nanochannel. The partial fractions of hydrophilic/ionic and hydrophobic nanodomains are then quantified with the volume difference from referenced IL systems, while the calculated ionic conductivity decreases in the self-assembled ILCs more than the occupied volume of ionic nanodomains. These analyses suggest that the mobility of ions in the self-assembled ILCs remains quite restricted even with small tetrafluoroborate anions because of strong attractive interaction among ionic moieties.

Metallated porphyrinic metal−organic frameworks for CO2 conversion to HCOOH: A computational screening and mechanistic study

Catalytic CO2 conversion is a promising and increasingly needed strategy to reduce carbon footprint, stockpile renewable energy in the form of fuels and high value-added chemicals. In recent years, porphyrinic metal-organic frameworks (PMOFs) have emerged as potential catalysts due to their isolated active sites, tunable structures and functionalities. Herein, we report a computational exploration for CO2 conversion into formic acid (HCOOH) on 9 metallated porphyrinic MOF-525(M) (M = CrIII, MnIII, FeIII, CoIII, NiII, CuII, ZnII, RhIII and IrIII) via density functional theory (DFT) calculations. The confinement effect of MOF-525(M) framework on CO2 conversion is found to be negligible. A reaction mechanism involving H2 dissociation and subsequent CO2 hydrogenation is proposed and investigated in detail, and the former is revealed to be rate-determining. From the analysis of natural bonding orbital (NBO) charges, charge transfer among different atoms is observed during H2 dissociation and the magnitude of charge is governed by the internal charge redistribution and the spin-state of metal. Moreover, d–σ* back-donation is unraveled to be significant in H2 dissociation on MOF-525(Rh) and MOF-525(Ir). Good correlations are established between the energy barriers of H2 dissociation and certain geometric/thermodynamic properties. During CO2 hydrogenation, there is significant non-covalent interaction between CO2 and dissociated H atom, and a strong attractive interaction is revealed to be favorable for hydrogenation. All the 9 MOF-525(M) are predicted to be catalytic active over the gas-phase reaction, particularly MOF-525(Rh) and MOF-525(Ir) are screened out as the best catalysts for CO2 conversion to HCOOH. This study demonstrates the capability of metallated porphyrinic MOF-525 to catalyze CO2 conversion and would assist in the future rational design of more efficient MOFs for CO2 conversion.

Atomic structures of ordered monolayer GP zones in Mg-Zn-X (X= Ca, Nd) systems

Atomic structures of ordered monolayer Guinier-Preston (GP) zones in Mg-Zn-X (X = Ca, Nd) systems are predicted based on first-principles calculations combined with the statistical-mechanical approach of cluster expansion. Multiple metastable GP zones with various compositions are identified in both systems. The predicted metastable structures in both systems show striking similarities and are all structurally related to monolayer Mg2X with each X atom 6-fold coordinated by Mg atoms on the HCP basal plane. An increased number of Mg atoms in monolayer Mg2X are replaced by Zn atoms to form ordered GP zones at an increased Zn/X ratio due to strong attractive interactions between Zn and X solutes, which ultimately leads to lower formation energies of the GP zones. Simulated TEM images and diffraction patterns of the predicted structures agree well with prior experimental observations.

Effective forces between active polymers.

The characterization of the interactions between two fully flexible self-avoiding polymers is one of the classic and most important problems in polymer physics. In this paper we measure these interactions in the presence of active fluctuations. We introduce activity into the problem using two of the most popular models in this field, one where activity is effectively embedded into the monomers' dynamics, and the other where passive polymers fluctuate in an explicit bath of active particles. We establish the conditions under which the interaction between active polymers can be mapped into the classical passive problem. We observe that the active bath can drive the development of strong attractive interactions between the polymers and that, upon enforcing a significant degree of overlap, they come together to form a single double-stranded unit. A phase diagram tracing this change in conformational behavior is also reported.

Nanosized Cr-N clustering in expanded austenite layer of low temperature plasma-nitrided Fe-35Ni-10Cr alloy

Expanded austenite (γN) formed by low temperature nitriding of austenitic stainless steel is a N-enriched fcc containing Cr-N short range ordering, but no direct observation of Cr-N clustering has been reported. In the present study, the nanostructure of an Fe-35Ni-10Cr (at%) alloy plasma-nitrided at 673 K was investigated using transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) technique in this study. Nanosized Cr-N clusters were directly observed in the γN accompanied with strong streaks in selected area diffraction, obvious modulated structure in TEM and Cr-N rich regions observed by 3DAP. Thermodynamic calculations suggested that Cr-N clusters were formed by spinodal decomposition due to a strong Cr-N attractive interaction. The hardness of the γN layer was much higher than that of Fe-N austenite steel, which indicates that the hardness is not only due to nitrogen solid-solution hardening but also to a synergetic effect of the coexistence of Cr and N.

Mixed Micellization, Thermodynamic and Adsorption Behavior of Tetracaine Hydrochloride in the Presence of Cationic Gemini/Conventional Surfactants.

In this approach, tensiometry and UV-visible techniques are used to determine the effect of cationic gemini and conventional surfactants on tetracaine hydrochloride (TCH), an anesthetic drug. We have estimated micellar, interfacial, and energetic constraints. To gain a deep understanding of their mixed association behavior, the outputs were examined using different theoretical models. The critical micelle concentration for single and mixed amphiphiles was estimated. The cmc values of mixed amphiphiles were found between the individual amphiphiles due to strong attractive interaction (synergism) between the components after mixing. The non-ideal behavior of mixtures was confirmed by the larger values of ideal cmc than the experimental cmc values. The negative values of interaction parameter (β) and values of activity coefficients less than unity indicate strong synergistic interaction between drug and surfactant. The stability of the mixed systems is demonstrated by the negative Gibbs free energy of micellization and excess free energy of micellization. In contrast to a single chain surfactant, a double chain surfactant (gemini) exhibits better interactions with the drug. Spectral measurements (UV-visible spectra) were used to monitor the binding of the drug with surfactant (conventional as well as gemini). Studying these mixed aggregates could help to optimize their compositions and find synergistic properties between TCH monomers and surfactants.

3D architecture of Drosophila interphase chromatin is stabilized by relatively strong attractive interactions between highly-dynamic lamina-associated domains and nuclear envelope

Interactions between nuclear envelope (NE) and lamina-associated domains (LADs), as well as interactions between topologically associating domains (TADs), are expected to shape various aspects of 3D chromatin structure and dynamics at the level of the entire nucleus. However, relevant genome-wide experiments that may provide statistically significant conclusions remain difficult. We have developed a dynamic coarse-grained model of the Drosophila melanogaster nucleus at TAD (∼100 kb) resolution that explicitly accounts for four distinct epigenetic classes of TADs and describes a time evolution of all chromosomes over the entire interphase.

Study on the properties of sodium lauroyl lactate anionic surfactant and cationic surfactant in a mixed system

The surface properties and applications of mixtures of an anionic surfactant (sodium lauroyl lactate (SLL)) and cationic surfactant (gemini quaternary ammonium salt with a hydroxyl group (GC12)) were investigated. The results showed that SLL/GC12 surfactant mixtures have synergistic effects, yielding higher surface activity and greater application performance. When the mole fraction of SLL (αSLL) was 0.4, the surface tension reached its minimum value. Furthermore, based on the calculated interaction parameters, stronger attractive interactions between the mixed SLL/GC12 surfactant molecules could be obtained at air/solution interfaces or with mixed micelles. When the mass fraction of SLL was 50%, its wetting ability and emulsifying capacity were optimal. The foam stability exceeded 95% when the mass fractions of SLL (WSLL) were 20%, 40%, and 50%. In addition, when the mole fraction of SLL was approximately 0.5, vesicles formed easily at a total solution concentration of 3 mM.

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

High thermoelectric and optical conductivity driven by the interaction of Boron and Nitrogen dopant atoms with a 2D monolayer Beryllium Oxide

The electronic, thermal and optical properties of a monolayer BeO with Boron (B) and Nitrogen (N) co-dopant atoms are studied by means of a density functional theory computation. Our calculations reveal that BeO with BN-codopant atoms can give rise to more effective and outstanding performance for the thermal and optical responses. More significantly, the monolayer BeO with BN codopant atoms becomes a semiconductor with a direct band gap in comparison with the insulator behavior of pristine BeO. The particular attention of this work is paid to the influence of the atomic configuration and the interaction of the B and N dopant atoms with BeO. The interaction of the B and N atoms with the BeO monolayer diminishes degenerate energy states forming flat bands. It is also found that there is a strong attractive interaction between the O and N atoms forming a strong sigma bond breaking the symmetry of BeO structure. Consequently, the band gap is reduced leading to a semiconductor behavior with improved thermoelectric properties such as the Seebeck coefficient and the figure of merit. The reduced band gap and the flat bands induce a high optical responses such as the refractive index, the reflectivity and the optical conductivity in the visible light region. In addition, the anisotropy of a monolayer BeO with B and N atoms regarding different direction of electromagnetic polarization is presented. We anticipate that our results can be useful for design of both thermoelectric and optoelectronic devices.

TDOS/PDOS/OPDOS, reduced density gradient (RDG) and molecular docking studies of [3-(3-bromophenyl)-cis-4,5-dihydroisoxazole-4,5-diyl]bis(methylene) diacetate

Due to the wide range of biological activity, 4,5-dihydroisoxazole compounds form an important family of five-membered heterocycles containing an oxygen atom and a nitrogen atom in the adjacent position. Therefore, [3- (3-bromophenyl) -cis-4,5-dihydroisoxazol-4,5-yl] bis (methylene) diacetate [BDBD] compound, which is a derivative of 4,5-dihydroisoxazole, was investigated in this study. The partial density of state (PDOS), the overlap population density of state (OPDOS) and total density of state (TDOS) of functional groups of the [BDBD] compound were theoretically evaluated using the DFT / B3LYP / 6-311G (d, p) method. Reduced density gradient (RDG) was also given to study the weak interaction, strong attraction, and strong repulsion interactions of the studied molecule. The PASS (Prediction of Activity Spectra) analysis predicts the carcinogenic activities with probability to be active value of 0.273 for the studied molecule. The antibacterial and anti-inflammatory activities of the [BDBD] compound against various the HIV-1 protease (1HSG), GyrB ATPase (3U2D), and VEGFR-2 kinase enzyme (4AG8) proteins were studied using molecular docking. The binding energies of 1HSG, 3U2D, and 4AG8 target proteins with [BDBD] ligand were calculated to be -6.11, -4.54, and -4.80 kcal/mol, respectively. Results were interpreted by comparing with the literature.

Selective CO2 adsorption and bathochromic shift in a phosphocholine-based lipid and conjugated polymer assembly.

We assemble a film of a phosphocholine-based lipid and a crystalline conjugated polymer using hydrophobic interactions between the alkyl tails of the lipid and alkyl side chains of the polymer, and demonstrated its selective gas adsorption properties and the polymer's improved light absorption properties. We show that a strong attractive interaction between the polar lipid heads and CO2 was responsible for 6 times more CO2 being adsorbed onto the assembly than N2, and that with repeated CO2 adsorption and vacuuming procedures, the assembly structures of the lipid-polymer assembly were irreversibly changed, as demonstrated by in situ grazing-incidence X-ray diffraction during the gas adsorption and desorption. Despite the disruption of the lipid structure caused by adsorbed polar gas molecules on polar head groups, gas adsorption could promote orderly alkyl chain packing by inducing compressive strain, resulting in enhanced electron delocalization of conjugated backbones and bathochromic light absorption. The findings suggest that merging the structures of the crystalline functional polymer and lipid bilayer is a viable option for solar energy-converting systems that use conjugated polymers as a light harvester and the polar heads as CO2-capturing sites.

Strong Be-Be bonds in double-aromatic bridged Be2(μ-SO) molecules.

A bridged Be2(μ-SO) molecule is formed by stabilizing the Be2 dimer using a SO ligand. In this molecule, which is thermodynamically stable, the Be2 moiety behaves as an efficient electron donor toward the SO fragment. The ionic character of Be2δ+ and SOδ- in this molecule is confirmed by NBO analysis. Energy decomposition analysis shows that the strongest attractive interactions in this molecule are the polarization and exchange interactions. Also, Adaptive Natural Density Partitioning (AdNDP) analysis indicates the stability of this molecule, which could be due to the double-aromatic character of this system. Therefore, it seems that the title molecule could be experimentally detected.