Electrostatic Potential Distribution Research Articles

Direct determination of paraquat herbicide by square-wave voltammetry by two-step transfer mechanism at heterogeneous boron-doped carbon nanowall electrodes

Boron-doped carbon nanowalls (B:CNW) versus boron-doped diamond (BDD) materials were investigated for the effective electrochemical detection of highly toxic herbicide paraquat (PQ). Depending on the surface morphology and functional groups of BDD and B:CNWs, the electrochemical absorption and detection of the target analyte PQ revealed different detection mechanisms. The surface absorption mechanism was mainly observed for BDD, while for B:CNWs, both surficial and edge absorption were observed due to the sharp edges of carbon nanowalls. This effectually drives the high heterogenous electron transfer kinetics at absorption sites. Detection of PQ was carried out in phosphate buffer solution with an optimized pH of 10 and parameters of the square-wave voltammetry. Comparative studies show higher voltammetric current peak heights for B:CNWs (∼90.5 μA) than BDD (∼7.5 μA) at a much lower PQ concentration of 4 μM. B:CNWs show a higher sensitivity of 11 μA/μM/cm2 than BDD of 2.23 μA/μM/cm2, hence BDD shows a LOD of 1.8 μM, whereas B:CNWs have a much lower LOD of 0.47 μM. Density functional theory calculations (DFT) show a higher propensity of the B:CNW models toward electrocatalytic reduction of the PQ. Moreover, the proposed two-step detection mechanism is strongly supported by the distribution of the PQ electrostatic potential in different oxidation states in conjunction with the slab surfaces. The higher the sensitivity, the lower the LOD, and the excellent performance of B:CNWs in the detection of PQ in real water samples also suggests its potential for use in the environmental monitoring and assessment of emerging pollutants.

One Pot Synthesis, Crystal Structure, Hirshfeld Studies, Docking Simulation and Antimicrobial Efficacy Assay of New Fused/Substituted Pyrazolinyl–Thiazolidinyl–Indolone Triheterocyclic Hybrid Scaffolds

In this present investigation, a new series of functionalized hybrid compounds containing three bioactive triheterocyclic templates, pyrazolines, thiazolidinones, and indolones are designed and synthesized via multicomponent, one-pot reaction of 3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide with various substituted isatin derivatives and chloroacetic acid in the presence of fused sodium acetate and glacial acetic acid viz ring closure mechanism followed by dehydration. The formation of new scaffolds 4–7(a–c) is evidenced by analytical and spectral studies. The single-crystal X-ray diffraction study supported the molecular structure of compound 4a as a triclinic crystal system with a P space group and Z = 2. Interestingly, the compound is crystallized with two molecules (A/B) and one water molecule in the asymmetric unit, and the crystal packing is stabilized by intra and intermolecular hydrogen bonds. To quantify the percentage of intermolecular contacts and electrostatic potential distribution in crystal packing, Hirshfeld surface analysis was performed. All the compounds were screened for their preliminary antimicrobial activity against a panel of bacterial and fungal strains. The newly synthesized compounds exhibited fairly encouraging in vitro antibacterial activity, so the validation of the potent compound was done by docking against the antibacterial target Escherichia coli FabH (PDB: 5BNS). The virtual screening is focused on ADME and drug-likeliness properties to identify their putative ligand-protein interactions using Schrödinger software.

Antimicrobial activities and theoretical studies on the weak interactions formation in two different configuration complexes

The ligand 2-(3-pyrazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide (L) was synthesized, and two transition metal complexes, namely [Cu(L)2]·(NO3)2 (1) and [Ni(L)3]·(NO3)2·3CH3OH (2) were prepared through complexation reaction between L and the corresponding metal salt. L and both complexes were characterized by elemental analysis, as well as compared with spectrographic technique for example FT-IR and UV–Vis spectroscopy. X-ray single-crystal diffraction demonstrated that 1 was tetra-coordinated square planar whereas 2 was hexa-coordinated slightly distorted octahedral geometry. Meanwhile, the metal-ligand ratios were 2:1 in 1 whereas 3:1 in 2. Through the superposition of hydrogen bonds and other weak interactions, both complexes formed 1-D chain-like, 2-D layered, and 3-D supramolecular structures. Theoretical investigations explained the optimized geometries of complexes and the electrostatic potential distribution in molecules, and also analyzed the electron transition types of L and both complexes in combination with UV–vis spectroscopy, which provided theoretical support for the experimental conclusions. Electrostatic potential (ESP) was computed for both complexes to predict the reaction positions of electrophilic and nucleophilic assaults. Hirshfeld Surface Analysis quantified interactions in molecules and analyzed the contribution of various weak interactions to stabilize the structure of complexes. Especially, antibacterial experiments displayed compounds had certain antibacterial activities against both Gram-positive and Gram-negative bacterial strains.

Experimental and simulation study on the influence of pH on mono-molecular mechanical properties of benzene and graphene

In drug delivery systems, graphene materials are promising drug carriers. Drug molecules are loaded on graphene through π-π interaction between graphene and benzene ring structure, which is widely found in organic drug molecules. Then the drug molecules are released under different conditions, such as different environmental pH, at lesion site. In the application, the adsorption and desorption between benzene ring structure in drug molecules and graphene play a key role. Herein, an experimental method for measuring the adhesion force between a single phenyl and graphene is proposed, and the adsorption and desorption mechanical properties of a benzene ring structure on graphene surface at different environmental pH are firstly measured. The experimental results show that the adhesion force decreases with the increase of environmental pH. Moreover, molecular dynamics simulations show that the influence of pH on adhesion force is mainly realized by changing the electrostatic potential distribution on graphene surface, and the interaction force between a single benzene and graphene changes from attractive to repulsive with the increase of environmental alkalinity. In addition, a molecular dynamics model for the dynamic adsorption and desorption capacities of benzene molecules on graphene surface at different quantity of ions is established. Benzene molecules can achieve full adsorption on the surface of graphene when there are 10 and 20 hydrogen ions. And benzene molecules can achieve full desorption on the surface of graphene when there are 10 and 20 hydroxide ions.

Insight with Crystallization, Quantum Computation, Hirshfeld, ELF/LOL and Molecular Docking of Syringic Acid Nicotinamide Cocrystal as Potent Mycobacterium Tuberculosis Inhibitor

Tuberculosis (TB) is a recurring and progressive illness with a high global death rate. MycobacteriumTB drug resistance is a serious impediment to allelopathy therapy. Contemplating combinatorial drug delivery (pharmaceutical cocrystal) as anti-TB medicines targeting Mycobacterium tuberculosis’s active site can be an alternative strategy. The syringic acid nicotinamide (SYNI) cocrystal was synthesized in this work through slow evaporation technique and was examined based on quantum chemical calculations, Hirshfeld analysis, electron localization analysis and molecular docking. The intended vibrational wavenumbers were allocated a PED value and related with experimental frequencies. The UV–Visible absorption spectra of the cocrystal in the liquid phase (ethanol) were revealed as [Formula: see text]* electronic transitions. The HOMO–LUMO values, band gap, molecular electrostatic potential and Mulliken atomic charge distribution of the molecule were evaluated to estimate its stability and molecular reactivity. The molecule’s second-order perturbation energy [Formula: see text] standards were determined by means of natural bond orbital analysis, and potential reactive site was assessed using local reactivity descriptors. Hirshfeld analysis revealed that H…H (44.9%), O…H/H…O (39.3%), C…H/H…C (6.1%), N…H/H…N (5.3%) and C…C (2.4%) have the major percentage contributions from the most significant interactions. The topological features of the SYNI cocrystal were assessed through electron localization function based on color gradient. The binding ability of SYNI cocrystal with the Mycobacterium tuberculosis associated proteins was evaluated through docking and their binding scores fall between the range of −9.1 kcal/mol and −10.8 kcal/mol, which confirms the better binding ability and makes SYNI cocrystal a potent medication against TB.

Improvement of carbon dots corrosion inhibition by ionic liquid modification: Experimental and computational investigations

Chemical modification is effective in improving the corrosion inhibition efficiency of carbon dots (CDs) on steel. Here, the imidazolium ionic liquids (IL) modified-CDs (IL-CDs) are synthesized and proved to be mixed-type corrosion inhibitors. The IL increases the pyrrole N content and facilitates the formation of a denser inhibitor film. Molecular simulations confirm that the IL reduces the π-π interaction between CDs, endowing IL-CDs with higher water solubility and better corrosion inhibition effect than CDs. The lower orbital energy gap and larger positive electrostatic potential distribution enable the inhibition efficiency of IL-CDs of 97.11% in 1 M HCl, much superior to CDs (90.80%).

Insight into (Z)-ethyl-2-(2-((E)-2,4-dinitro benzylidene amino)-4-oxo-3-phenylthiazolidin-5-ylidene) acetate in-silico anti-SARS-CoV-2 performance: Synthesis, structural-spectral characterizations and DFT computations

This study reports on the synthesis of a 4-thiazolidinone derivative (EN2Th), namely, (Z)-Ethyl-2-(2-((E)-2,4-dinitro benzylidene amino)-4-oxo-3-phenylthiazolidin-5-ylidene) acetate. Its crystal structure has been determined by single crystal X-ray diffraction and the spectral characterizations were carried out by means of 1H and 13C NMR, and FT-IR techniques. The molecule of EN2Th crystallizes in the monoclinic P21/c symmetry and its crystal structure consists of a herringbone packing along [100]. The density functional theory (DFT) at the B3LYP/6-311G (d,p) level has been employed for structure optimization, the results confirm a good consistency between the theoretical and the experimental geometrical data. Hirshfeld surface and 2D fingerprints indicate C−H···O (29.7%) and H···H (24.5%) as the most relevant intermolecular interactions in the crystal packing of EN2Th. According to the reduced density gradient (RDG) analysis, EN2Th exhibits vdW to weak repulsive regions with low electron densities. The theoretical electronic circular dichroism (ECD) spectrum displays an exciton coupled transitions associated with the Z-configuration of the thiazolidin-4-one moiety reflecting the steric effect of the ester group. Charge transfer inside the 4-thiazolidinone derivative EN2Th was considered via the frontier molecular orbitals (FMOs) and natural bond orbital (NBO) investigations along with molecular electrostatic potential (MEP) distribution maps. The HOMO and LUMO energies allowed the estimation of the chemical reactivity descriptors. In accordance with the NBO results, the predicted hyperpolarizabilities indicate a strong donor to acceptor π-electrons delocalization in EN2Th. The anti-viral performance of EN2Th was evaluated in silico against SARS-CoV-2 main protease (MPro) via molecular docking simulations. Finally, ADMET (absorption, distribution, metabolism, excretion and toxicity) online software tools were utilized to uncover the title compound's potential cytotoxicity.

Virtual Work Principle for Piezoelectric Semiconductors and Its Application on Extension and Bending of ZnO Nanowires

This paper presents the principle of virtual work (PVW) for piezoelectric semiconductors (PSs), which extends the piezoelectric dielectrics to involve the semiconducting effect. As an application of the PVW, a one-dimensional (1D) approximation theory for the extension and bending of PS nanowires is established by directly applying the PVW and Bernoulli–Euler beam theory with the aid of the second-order approximation of electrostatic potential. To illustrate the new model, the mechanical displacement, electrostatic potential, and concentration of electrons for extension and bending deformation of n-type ZnO nanowires are analytically determined. Additionally, numerical results show that, for n-type Zinc Oxide nanowires, the distribution of electrostatic potential is anti-symmetric along the thickness direction for extension deformation. In contrast, the bending deformation causes a symmetric distribution of electrostatic potential characterized by the zeroth-order and the second-order electrostatic potential. Furthermore, these two different deformations result in the redistribution of electrons. The electrostatic potential can be tuned by adjusting the amplitude of the applied mechanical load. Moreover, we find that the increase in doping level will reduce the magnitude of electrostatic potential due to the screening effect. The presented PVW provides a general approach to establishing structural theories and an effective way of implementing numerical methods.

Preparation and performance of superhydrophobic surfaces with low surface energy modified attapulgite

Material modification with low surface energy can offer lower surface free energy on micro- and nano-rough structures, which is necessary for developing superhydrophobic surfaces. Based on experiment and molecular simulation, the composite systems of attapulgite (APT) modified by alkylamine, alkylammonium salt and stearic acid were prepared. Combine surface free energy, electrostatic potential distribution, self-diffusion coefficient, and interfacial formation energy to favor the superhydrophobic composite system, and the interaction between low surface materials and attapulgite was explained. The results demonstrate that the hydrophobicity of APT are clearly modified by alkyl amine, alkyl ammonium salt, and stearic acid, and that when the molecular number of low surface energy monomers increases, the surface free energy of the composites first decreases and then increases. At the ideal concentration, the contact angles of alkyl amine/APT and SA/APT composites are all greater than 150°, and the antifouling performance is excellent. Finally, compounding technology was used to further optimize the superhydrophobic composite system. It was discovered that the hydrophobicity and antifouling properties of the composite system were superior to those of the monomer, and the octadecylamine/SA/APT composite system performed optimally at a contact angle of 167.54°.

Intramolecular engineering of defective terminations within triazine-based conjugated polymers for augmented photocatalytic H2 production and Cr(VI) reduction

In this study, enhanced intramolecular polarization of π-conjugated electrons in triazine-based conjugated polymers (TCPs) was modulated by incorporating –NH2/-CN terminations. The electron-abundant –NH2 groups and the electron-deficient –CN groups lead to the delocalization of the π-conjugated electrons on the plane of the conjugated polymer by the push-and-pull effect. The resultant A-TCP-C configuration expands the photoresponsive regions and form spatially separated electron-hole centers as the charge-transfer channels for electron shuttling. The π-conjugated electrons polarized delocalization system induces the asymmetrical distribution of electrostatic potential and creates intramolecular electric field to facilitate the activation of the conjugated electrons over the plane from π to π* states by accumulating valence electrons on the benzene ring near –NH2 terminals, which reduce the activation energy barrier and thus offer profitably condition for the visible light excitation process. Additionally, the exposed –NH2/-CN terminal defects create high-energy adsorption sites for the preconcentration of target substances. This optimization of thermodynamically and kinetically accessible pathways enabled preferential reactant accumulation and charges transfer. The as-synthesized A-TCP-C20 polymer exhibits a photocatalytic activity of removing 95.8% Cr(VI) within 40 min and a H2 production ability of 1919.0 μmol g−1 h−1, which is 6 folds and 260 folds over the pristine TCP, respectively. Our work presents a facile and directional structure arrangement can be devised to simultaneously optimize active species binding, transfer, and activation on TCPs surface sites.

Mechanism of [BMIM][BF4] inhibiting coal groups activity from experiments and DFT calculations

The interaction between ionic liquid and coal (IL-coal) plays a theoretically pivotal role in revealing the internal mechanism of ILs inhibiting coal spontaneous combustion (CSC). This can determine the degree of reaction or inhibitory ability between IL-coal molecules. First, the activity characteristics of FTIR structural parameters from molecular surfaces affected by [BMIM][BF4] were obtained. In addition, the optimal structures of [BMIM][BF4] with methyl, hydroxyl, ether bond, methylene, and carboxyl groups were determined based upon Density Functional Theory. The activity characteristics of the IL-coal complexes were investigated from the aspects of charge population and transfer, bond length change, and electrostatic potential distribution. Finally, the types and relationships of the forces between the five structures of the IL-coal complexes and the stability and activity order were explored. The results demonstrated that [BMIM][BF4] could possibly reduce the structural abundance, side chain length, and oxygen-containing groups of aliphatic hydrocarbons. The interaction between anion [BF4]− and active groups was more stable than that between cation [BMIM]+ and active groups. Meanwhile, the dissolution and destruction of coal active groups by ILs were not completely determined by the number of hydrogen bonds formed between ILs and coal active groups, but by the strength of hydrogen bonds formed between anions and coal active groups, and the effect of anions was stronger than that of cations. The order of oxidation capacity of the IL-coal complexes was: [BMIM][BF4]–CH2– > [BMIM][BF4]–O– > [BMIM][BF4]–COOH > [BMIM][BF4]–CH3 > [BMIM][BF4]–OH. The van der Waals effect mainly presented complexes. Despite this, there were hydrogen bonds between the complexes formed by hydroxyl groups, but the hydrogen bond force showed exceptionally slight effects.

Oxygen-modified graphitic carbon nitride with nitrogen-defect for metal-free visible light photocatalytic H2O2 evolution

Photocatalytic oxygen reduction is regarded as the cleanest approach for the production of hydrogen peroxide (H2O2). Herein, oxygen-modified graphite carbon nitride (g-C3N4) with nitrogen-defect (namely g-C3N4-ND4-OM3) was synthesized by a feasible method. Owing to the existence of nitrogen vacancy and oxygen-containing functional group, the absorption bands derived from n → π* and π → π* electronic transitions were enhanced, thereby enlarging the visible light response range of catalysts. Interestingly, nitrogen-defect can capture electron and effectively suppress the recombination of photoinduced electrons and holes. More importantly, the introduction of oxygen-containing functional groups can improve the hydrophilicity of g-C3N4, which was beneficial for the adsorption of dissolved oxygen. The electrostatic potential distributions of g-C3N4-based photocatalyst structural unit were also changed after introducing nitrogen vacancy and oxygen-containing functional group, and the electron-donating ability of g-C3N4 was improved. As a result, the evolution rate of H2O2 catalyzed by g-C3N4-ND4-OM3 was as high as 146.96 μmol/g/L under visible light irradiation. The photocatalytic H2O2 generation was completed through the direct 2-e− oxygen reduction. In short, current work will share novel insights into photocatalytic H2O2 generation over g-C3N4-based catalyst.

Investigation of photophysical and electronic properties of aurone derivatives: Insights from spectroscopic techniques and density functional theory calculations

This paper reports on a study of the photophysical properties, density functional theory (DFT) calculations, infrared (IR), ultraviolet (UV) and nuclear magnetic resonance (NMR) spectroscopic techniques of a series of aurone compounds. The photophysical properties were investigated using UV absorption and fluorescence spectroscopy in a dimethyl sulfoxide (DMSO) solution. Furthermore, the fluorescence quantum yields of the target compounds (1–24) were also investigated. Remarkably, these compounds revealed high quantum yields (Φ = 0.001–0.729) as compared to the already existing aurones in literature. The DFT calculations were performed to elucidate the electronic structure, energy levels and draw a comparison between experimental and theoretical findings. The simulated properties such as molecular frontier orbitals, the density of states, reactivity descriptors (GCRD), electrostatic potential distribution, transition density matrix, electron localization function (ELF) and localized orbital locator (LOL) have been calculated using DFT. The DFT calculations provided insight into the electronic structure and energy levels of the aurone compounds, while the IR and UV spectroscopy results shed light on their functional groups and electronic transitions, respectively. The results of this study contribute to a better understanding of the photophysical properties of aurone compounds and suggest their potential use in technological applications.

Understanding the Role of Removable Solid Additives: Selective Interaction Contributes to Vertical Component Distributions.

Sequentially deposited organic solar cells (SD-OSCs) have attracted great attention owing to their ability in achieving a more favorable, vertically phase-separated morphology to avoid the accumulation of counter charges at absorber/transporting layer interfaces. However, the processing of SD-OSCs is still quite challenging in preventing the penetration of small-molecule acceptors into the polymer donor layer via erosion or swelling. Herein, solid additives (SAs) with varied electrostatic potential distributions and steric hinderance are introduced into SD-OSCs to investigate the effect of evaporation dynamics and selective interaction on vertical component distribution. Multiple modelings indicate that the π-π interaction dominates the interactions between aromatic SAs and active layer components. Among them, p-dibromobenzene shows a stronger interaction with the donor while 2-chloronaphthalene (2-CN) interacts more preferably with acceptor. Combining the depth-dependent morphological study aided by multiple X-ray scattering methods, it is concluded that the evaporation of SAs can drive the stronger-interaction component upward to the surface, while having minor impact on the overall molecular packing. Ultimately, the 2-CN-treated devices with reduced acceptor concentration at the bottom surface deliver a high power conversion efficiency of 19.2%, demonstrating the effectiveness of applying selective interactions to improve the vertical morphology of OSCs by using SAs with proper structure.

Design of atomic cobalt selenide-doped sulfurized polyacrylonitrile cathode with enhanced electrochemical kinetics for high performance lithium-SPAN batteries

In this work, sulfurized polyacrylonitrile (SPAN) cathodes with atomically dispersed Co and Se active site, namely cobalt selenide doped-sulfide polyacrylonitrile (CoSe2-x@SPAN, x = 6, 10, 15) with different CoSe2 doping concentrations of 6, 10, and 15 wt%, were fabricated by co-heating approach to strengthen the charge conductivity and catalytic activity of SPAN cathode. Atomic scale CoSe2 were doped into the SPAN skeleton to expediating the redox kinetics of lithium storage process, and the catalytic mechanism was made clear by a viewing angle of frontier molecular orbital theory. The DFT calculation results show that CoSe2@SPAN has a more uniform electrostatic potential distribution with a smaller LUMO-HOMO band gap, which is more conducive to electron transport. The Co/Se loaded SPAN polymer constructed by N-Co-S chemical coordination improves the matching degree between the highest occupied molecular orbital (HOMO) of the nucleophile S2− and the lowest unoccupied molecular orbital (LUMO) of the electrophile Li+ during the discharge process, and effectively reduces the bonding orbital σ level of the deposited product Li2S, thereby promoting the lithium storage kinetics of CoSe2@SPAN cathode material and avoiding the shuttle effect. Meanwhile, the larger Gibbs free energy variation during the lithiation process indicates the enhanced reaction kinetics of the CoSe2@SPAN cathode. Ultimately, The Li-SPAN battery with CoSe2-10@SPAN cathode delivers high reversible capacity of 1475 mAh g−1 at 0.2 A/g, superior rate capability and long-term capacity retention of 71.1% after 500 cycles at 1.0 A/g. Accordingly, this study offers insights into the utilization of frontier molecular orbital theory (FMO) to improve the redox kinetics and sulfur utilization of Li-SPAN batteries.

Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

Layered double hydroxides (LDH) frameworks have shown significant enhancement in stability and reusability, and their tailorable architecture brings new insight into the development of the next generation of hybrid materials, which attracted considerable attention in many fields over the years. One of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition, which can accommodate a wide spectrum of potential anionic guests. This exceptional property makes the LDH system simple to adjust for various applications. However, most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating systems. In this study, LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation (PEO) treatment in the presence of ethylenediaminetetraacetic acid, thereby avoiding the use of hydrothermal autoclave conditions. This LDH system was compared with a hybrid architecture consisting of organic-inorganic self-assembly. An organic layer was fabricated on top of the LDH film using 4-Aminophenol (Aph) compound, resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion performance. At the molecular level, the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as follows. First, Localized orbit locator (LOL)-π isosurface, electrostatic potential (ESP) distribution, and average local ionization energy (ALIE) on the molecular surface were used to highlight localization region, reveal the favorable electrophilic and nucleophilic attacks, and clearly explore the type of interactions that occurred around interesting regions. Second, first-principles based on density functional theory (DFT) was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual interactions. The experimental and computational analyses suggest that the high π-electron density and delocalization characteristics of the functional groups and benzene ring in the Aph molecule played a leading role in the synergistic effects arising from the combination of organic and inorganic coatings. This work provides a promising approach to design advanced hybrid materials with exceptional electrochemical performance.

Effect of functional groups on VOCs adsorption by activated carbon: DFT study

Volatile organic compounds (VOCs) have attracted increasing attention in the field of environmental control due to their harmful effects on human health and the environment. Activated carbon is promising as an adsorbent for VOCs. The physisorption of six VOCs (methane (CH4), dichloromethane (CH2Cl2), ethylene (C2H4), formaldehyde (HCHO), ethanol (C2H5OH), and toluene (C7H8)) by four activated carbon models (without functional group (NF), with hydroxyl (HD), pyridine (PD), and pyrrole (PR) group, respectively) was studied in combination with their electrostatic potential (ESP). The results show that ESP plays a decisive role in the adsorption of CH4, CH2Cl2, C2H4, HCHO, and C2H5OH, as their adsorption is mainly carried out by H-bonds. The functional group affects the adsorption process by changing the ESP distribution on the activated carbon surface. The orders of the absolute ESP values on the plane and edge of activated carbon are PR>HD>NF>PD and HD>PR>PD>NF, respectively, so that the order of the interaction strength and the physisorption energy are almost the same. Meanwhile, dispersion can enhance adsorption and change the order. For example, the order of CH2Cl2 adsorption at the activated carbon edge is PD>HD>PR>NF. C7H8 is difficult to be adsorbed at the activated carbon edge, but it can be adsorbed on the plane by a π-π stacking interaction whose strength is controlled by the relative molecular mass of activated carbon. This study will guide the design of activated carbon for efficient adsorption of VOCs.

Human-murine chimeric autoantibodies with high affinity and specificity for systemic sclerosis.

Scleroderma 70 (Scl-70) is commonly used in the clinic for aiding systemic sclerosis (SSc) diagnosis due to its recognition as autoantibodies in the serum of SSc patients. However, obtaining sera positive for anti-Scl-70 antibody can be challenging; therefore, there is an urgent need to develop a specific, sensitive, and easily available reference for SSc diagnosis. In this study, murine-sourced scFv library were screened by phage display technology against human Scl-70, and the scFvs with high affinity were constructed into humanized antibodies for clinical application. Finally, ten high-affinity scFv fragments were obtained. Three fragments (2A, 2AB, and 2HD) were select for humanization. The physicochemical properties of the amino acid sequence, three-dimensional structural basis, and electrostatic potential distribution of the protein surface of different scFv fragments revealed differences in the electrostatic potential of their CDR regions determined their affinity for Scl-70 and expression. Notably, the specificity test showed the half-maximal effective concentration values of the three humanized antibodies were lower than that of positive patient serum. Moreover, these humanized antibodies showed high specificity for Scl-70 in diagnostic immunoassays for ANA. Among these three antibodies, 2A exhibited most positive electrostatic potential on the surface of the CDRs and highest affinity and specificity for Scl-70 but with least expression level; thus, it may provide new foundations for developing enhanced diagnostic strategies for SSc.

Polypyrene Porous Organic Framework for Efficiently Capturing Electron Specialty Gases.

The polypyrene polymer with an extended π-conjugated skeleton is attractive for perfluorinated electron specialty gas (F-gas) capture as the high electronegativity of fluorine atoms makes F-gases strongly electronegative gases. Herein, a polypyrene porous organic framework (termed as Ppy-POF) with an extended π-conjugated structure and excellent acid resistance was constructed. Systematic studies have shown that the abundant π-conjugated structures and gradient electric field distribution in Ppy-POF can endow it exceptional adsorption selectivity for high polarizable F-gases and xenon (Xe), which has been collaboratively confirmed by single-component gas adsorption experiments, time-dependent adsorption rate tests, dynamic breakthrough experiments, etc. Electrostatic potential distribution and charge density difference based on Grand Canonical Monte Carlo simulations and density functional theory calculations demonstrate that the selective adsorption of F-gases and Xe in Ppy-POF is attributed to the strong charge-transfer effect and polarization effect between Ppy-POF and gases. These results manifest that the POF with an extended π-conjugated structure and gradient electric field distribution has great potential in efficiently capturing electron specialty gases.

Molecular simulation of the regulation mechanism of the hydrophilic structure of surfactant on the wettability of bituminous coal surface

The regulation of surfactant on the wettability of bituminous coal surface is influenced by its hydrophilic structure. Based on the water absorption simulation and contact angle experiment of bituminous coal under different surfactants, the wetting effect of different surfactants with different hydrophilic structures on bituminous coal was obtained. The mechanism of different surfactants at the coal-water interface was analyzed by molecular dynamics simulation. The frontier orbital distribution and surface electrostatic potential distribution of surfactants and bituminous coal molecules were calculated by quantum chemistry method. The results showed that the wetting effect of surfactants on bituminous coal was APG1214 > OA-12 > SDBS > DTAB. The structure of hydroxyl and amine oxide made surfactants more conducive to promoting the interaction between coal and water molecules. The more oxygen and nitrogen elements the hydrophilic structure contains, the more favorable the surfactant is to modulate the wettability of the bituminous coal surface.