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In this work, the structural, electronic, and optical properties of bulk and monolayer of Iron dichalcogenides FeX2 (X= S, Se, Te) have been investigated using the full potential linearized augmented plane wave (FP-LAPW) in the framework of density functional theory (DFT) with Wien2k simulation package. The calculated results show that FeX2 compounds in the bulk structure are non-magnetic semiconductors with a direct gap at the Γ point, while the monolayer compounds are ferromagnetic with metallic character. The band structure and energy gap of bulk and monolayer structures of FeX2 are calculated using GGA-PBE and GGA-mbj approximations that Becke-Johnson functional gives us better results for band gaps. All-optical properties such as real and imaginary parts of the dielectric function, absorption and reflection coefficients, refractive and extinction index, conductivity, and electron energy loss spectrum have been calculated and analyzed for bulk and monolayer. The High amplitude and wide absorption coefficient in the visible and ultraviolet region make these compounds a good candidate for use in photoelectric instruments and solar cells. Since monolayer compounds show magnetic properties, all calculations for monolayer compounds are performed in the spin-polarized form.

A new chemosensor 1 was synthesized by reacting rhodamine B hydrazide and 2,3,4-trihydroxybenzaldehyde, which was then characterized by spectroscopic techniques and single crystal X-ray crystallography. Sensor 1 has the ability to sense Co2+/Cu2+ ions by “naked-eye” with an apparent colour change from colourless to pink in different solvent system, MeCN and DMF respectively. Furthermore, it can selectively detect Co2+/Cu2+ among wide range of different metal ions, and it exhibits low detection limit of 4.425 × 10−8 M and 1.398 × 10−7 M respectively. Binding mode of the two complexes were determined to be 1:1 stoichiometry for Co2+ complex and 1:2 stoichiometry for Cu2+ complex through Job’s plot, IR spectroscopy, mass spectrometry and 1H NMR spectroscopy. Moreover, reversibility of the sensor 1 as copper (II) ion detector was determined by using EDTA and the results showed that sensor 1 can be reused for at least 6 cycles. Other than that, a low cost chemosensor test strips were fabricated for the convenient “naked-eye” detection of Co2+ and Cu2+ in pure aqueous media. The MTT assay was conducted in order to determine the cytotoxicity of sensor 1 towards human cell lines.

Homophymines A–E and A1–E1 are bioactive natural cyclodepsipeptides with a complex molecular architecture. These molecules could have a potential use as antimicrobial, antiviral, and anticancer substances. We have carried out a computational study of the properties of this family of marine peptides using a CDFT‐based Computational Peptidology (CDFT‐CP) methodology that results from the combination of the chemical reactivity descriptors that arise from conceptual Density Functional Theory (CDFT) together with cheminformatics tools. The latter can be used to estimate the associated physicochemical parameters and to improve the process of virtual screening through a similarity search. Using this approach, the ability of the peptides to behave as a potentially useful drugs can be investigated. An analysis of their bioactivity and pharmacokinetics indices related to the ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) features has also been carried out., Chemoinformatic by the sea: Computational peptidology based on the combination of conceptual DFT and computational pharmacokinetics has been applied to predict the biological properties and chemical reactivities of the members of the Homophymines family of marine cyclic peptides.

The spin polarization of carbon nanomaterials is crucial to design spintronic devices. In this paper, the first‐principles is used to study the electronic properties of two defect asymmetric structures, Cap‐(9, 0)‐Def [6, 6] and Cap‐(9, 0)‐Def [5, 6]. We found that the ground state of Cap‐(9, 0)‐Def [6, 6] is sextet and the ground state of Cap‐(9, 0)‐Def [5, 6] is quartet, and the former has a lower energy. In addition, compared with Cap‐(9, 0) CNTs, the C adatom on C30 causes spin polarization phenomenon and Cap‐(9, 0)‐Def [6, 6] has more spin electrons than Cap‐(9, 0)‐Def [5, 6] structure. Moreover, different adsorb defects reveal different electron accumulation. This finding shows that spin polarization of the asymmetric structure can be adjusted by introducing adatom defects., Two defect asymmetric structures Cap‐(9, 0)‐Def [6, 6] CNT and Cap‐(9, 0)‐Def [5, 6] CNT have been constructed, and the former has a lower energy. In addition, the C adatoms on C30 causes spin polarization phenomenon, and Cap‐(9, 0)‐Def [6, 6] CNT has more spin electrons than Cap‐(9, 0)‐Def [5, 6] CNT.

Funder: Engineering and Physical Sciences Research Council; doi: https://doi.org/10.13039/501100000266, Recently published density functional theory results using the PBE functional (Whaley-Baldwin and Needs 2020 New J. Phys. 22 023020) suggest that elemental sulfur does not adopt the simple-cubic (SC) P m 3 ̄ m phase at high pressures, in disagreement with previous works (Rudin and Liu 1999 Phys. Rev. Lett. 83 3049--52; Gavryushkin et al 2017 Phys. Status Solidi B 254 1600857). We carry out an extensive set of calculations using a variety of different exchange–correlation functionals (both local and non-local), and show that even though under LDA and PW91 a high-pressure SC phase does indeed become favourable at the static lattice level, when zero-point energies (ZPEs) are included, the transition to the SC phase is suppressed in every case, owing to the larger ZPE of the SC phase; thus confirming the transition sequence as R 3 ̄ m → BCC, with no intervening SC phase. We reproduce these findings with pseudopotentials that explicitly include core electronic states, and show that even at these high pressures, only the n = 3 valence shell contributes to bonding in sulfur. We then compare our findings against the all-electron code ELK, which is in excellent agreement with our pseudopotential results, and examine the roles of the exchange and correlation contributions to the total energy. We further calculate anharmonic vibrational corrections to the ZPEs of the two phases, and find that such corrections are several orders of magnitude smaller than the ZPEs and are thus negligible. The effect of finite temperatures is also considered, and we show that the P m 3 ̄ m phase becomes even more unfavourable with an increase in temperature. Finally, the experimental consequences of our results on the equation of state of sulfur and its superconducting critical temperature are explicitly calculated.

Graphical abstract The synthetic cyclohexenecarboxylate ester antiviral Oseltamivir (O) have been theoretically studied by B3LYP/6–311 + + G** calculations to estimate its reactivity and behaviour in gas and aqueous media. The most stable structure obtained in above media is consistent with that reported experimental for Oseltamivir phosphate. The solvation energy value of (O) in aqueous media is between the predicted for antiviral Idoxuridine and Ribavirin. Besides, (O) containing a NH2 group and NH group reveals lower solvation energy compared with other antiviral agents with an NH2 group, such as Ribavirin, Cidofovir, and Brincidofovir. Atomic charges on N and O atoms in acceptors and donor groups reveal different behaviours in both media, while the natural bond orbital (NBO) studies show a raised stability of (O) in aqueous solution. This latter resulted is in concordance with the lower reactivity evidenced in water. Frontier orbital studies have revealed that (O) in gas phase has a very similar gap value to antiviral Cidofovir used against the ebola disease, while Chloroquine in the two media are more reactive than (O). This study will allow to identify (O) by using vibrational spectroscopy because the 144 vibration modes expected have been assigned using the harmonic force fields calculated from the scaled mechanical force field methodology (SQMFF). Scaled force constants for (O) in the mentioned media are also reported for first time. Due to hydration of the C = O and NH2 groups by solvent molecules, the calculations in solution produce variations not only in the IR wavenumbers bands, but also in their intensities. Supplementary Information The online version contains supplementary material available at 10.1007/s00894-021-04962-3.

The catalytic and photon-induced oxidation of NO2 on anatase TiO2 has been studied and compared with the surface nitrate species obtained after adsorption of HNO3. Using a combination of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), density functional theory (DFT), and temperature-programmed desorption (TPD), it is shown that identical products are obtained in all reaction systems but that their formation rates differ significantly. The surface reaction products are identified as combinations of surface–NO3– species, where NO2 bonds to the lattice oxygen, and freely adsorbed NO3– ions. These products can be obtained either by dissociative adsorption of HNO3 or by catalytic/photocatalytic oxidation of NO2, which is facilitated by UV light. A concerted reaction mechanism is unraveled that involves reorientation of bidentate nitrate that pushes out a neighboring protonated lattice oxygen to form a surface–NO3– species and a terminal OH group. The thermal stability of these surface species has been studied by means of TPD and simultaneous in situ DRIFTS measurements that reveal a main desorption peak (m/z = 46) at around 430 °C, which is attributed to concerted nitrate desorption through pentoxide (N2O5) formation. A weaker and broader TPD peak is found at about 185 °C and is attributed to desorption of nitrate species bonded in a compressed configuration. The experimental results can be explained by the changing stability of the identified nitrate products, which depends strongly on the surface chemical environment and the surface coverage. The DFT results show that the stabilization of intermediate NO2 adsorbates and the final nitrate reaction products occurs through a bifunctional charge exchange mechanism that is mediated by the TiO2 crystal. In particular, a stable surface–NO3– and NO3– ion pair configuration has been identified. This mechanism explains both the thermal and photoinduced oxidation of NO2 and their thermal stability and different formation rates, yielding high photoinduced oxidation reaction rates. Our results provide insights into the structure and chemical stability of nitrate surface products on TiO2 particles and their formation mechanism, which is important for understanding their catalyzed transformation into the harmful compounds HONO and N2O during continued UV light illumination. Title of manuscript version in list of papers for David Langhammer: Adsorption and Catalytic Oxidation of NO2 on Anatase TiO2: A Combined DFT and Operando DRIFT Spectroscopy StudyAuthors of manuscript version in list of papers for David Langhammer: David Langhammer, Lars Österlund

S-nitrosothiols (RSNOs) are an important group of nitric oxide (NO)-donating compounds with low toxicity and wide biomedical applications. In this paper, we, for the first time, demonstrate that the concentration of buffer remarkably affects the stability of RSNOs including naturally occurring S-nitrosoglutathione (GSNO) and synthetic S-nitroso-N-acetylpenicillamine (SNAP). For a solution with a high concentration of GSNO (e.g., 50 mM) and an initial near-neutral pH, the optimal buffer concentration is close to the GSNO concentration under our experimental conditions. A lower buffer concentration does not have adequate buffer capacity to resist the pH drop caused by GSNO decomposition. The decreased solution pH further accelerates GSNO decomposition because GSNO is most stable at near-neutral pH according to our density functional theory (DFT) calculations. A higher-than-optimal buffer concentration also reduces the GSNO stability because buffer ingredients including phosphate, Tris base, and HEPES consume NO/N2O3. In contrast to GSNO, the highest SNAP stability is obtained when the starting solution at a neutral pH does not contain buffer species, and the stability decreases as the buffer concentration increases. This is because SNAP is more stable at mildly acidic pH and the SNAP decomposition-induced pH drop stabilizes the donor. When the RSNO concentration is low (e.g., 1 mM), the buffer concentration also matters because any excess buffer accelerates the donor decomposition. Since the effect of buffer concentration was previously overlooked and suboptimal buffer concentrations were often used, this paper will aid in the formulation of RSNO solutions to obtain the maximum stability for prolonged storage and sustained NO release.

The photoreversible color switching system (PCSS) is attracting increasing attention for use in alleviating energy crisis and environmental problems. We report a robust PCSS in which lattice matching enables bottom-up oriented assembly between metal-organic frameworks (MOFs) and inorganic nanocrystals (INCs), two distinct entities that differ drastically in structure and function. Specifically, cubic-phase Prussian blue (PB) of a framework backbone is spontaneously attached to rutile TiO2 nanowires in a defined orientation triggered by the lattice matching between the (001) plane of TiO2 and the (222) plane of PB. Ultraviolet light irradiation accelerates the photoelectron transport within the oriented TiO2/PB system and enables fast photo switching. The derived TiO2/PB paper can be ranked as one of the best light-printing papers in literature because of its high resolution (∼ µm) and capability to be repeatedly written for >100 times without significant loss of contrast. The ultrathin TiO2 nanowires are rich in oxygen and Ti vacancies, which allow visible- and sunlight-light printing. Density functional theory calculations suggest that the [Fe(CN)6]4− ligand from the PB attaches preferentially to the (110) surface of TiO2 to give the ordered TiO2/PB assembly. The findings demonstrate the strong versatility of particles-mediated assembly in advanced materials design.

Millions of people in poor areas are still under the threat of fluoride contamination. How to effectively separate fluorine in water is an important step to reduce the ecological risk. In this paper, we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl- and MgAl-LDHs. The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination, because of the better electronic structure. After the defluorination, the LiAl-LDHs with adsorbed-F

This paper employs the Heyd-Scuseria-Ernzerhof (HSE) function to research electronic structures of monolayer InxAl1-xN with different compositions (x = 0, 0.25, 0.5, 0.75, 1) based on the first-principles, and the optical properties of single-layer InxAl1-xN are calculated by Generalized Gradient Approximation-Perdew Burke Ernzerhof (GGA-PBE) function. The influence of the electronic structure on the properties has been analyzed. Then the influence of doping quantity on the characteristics has been summarized, which also indicates the trend of the complex dielectric function and absorption spectrum. The calculation results show that with the increase of x, the static dielectric constant increases, the electron transition ability increases, and the absorption peak intensity in the light absorption spectrum increases. It can conclude that the InxAl1-xN compound can theoretically achieve the adjustable Eg and photoelectric performance with x, which will apply in making various optoelectronic devices, including solar cells and sensors.

The large-scale manufacturing of flexible electronics is nowadays based on inkjet printing technology using specially formulated conductive inks, but achieving adequate wetting of different surfaces remains a challenge. In this work, the development of a silver nanoparticle-based functional ink for printing on flexible paper and plastic substrates is demonstrated. Amphiphilic silver nanoparticles with narrow particle size distribution and good dispersibility were prepared via a two-step wet chemical synthesis procedure. First, silver nanoparticles capped with poly(acrylic acid) were prepared, followed by an amidation reaction with 3-morpholynopropylamine (MPA) to increase their lipophilicity. Density functional theory (DFT) calculations were performed to study the interactions between the particles and the dispersion medium in detail. The amphiphilic nanoparticles were dispersed in solvents of different polarity and their physicochemical and rheological properties were determined. A stable ink containing 10 wt% amphiphilic silver nanoparticles was formulated and inkjet-printed on different surfaces, followed by intense pulsed light (IPL) sintering. Low sheet resistances of 3.85 Ω sq–1, 0.57 Ω sq–1 and 19.7 Ω sq–1 were obtained for the paper, coated poly(ethylene terephthalate) (PET) and uncoated polyimide (PI) flexible substrates, respectively. Application of the nanoparticle ink for printed electronics was demonstrated via a simple flexible LED circuit.

International audience; Combining experimental set up and ab initio molecular dynamics simulations, we were able to follow the time evolution of the X-ray absorption near edge spectrum (XANES) of a dense copper plasma. This provides a deep insight into femtosecond laser interaction with a metallic copper target. This paper presents a review of the experimental developments we made to reduce the X-ray probe duration, from approximately 10 ps to fs duration with table-top laser systems. Moreover, we present microscopic scale simulations, performed with Density Functional Theory, as well as macroscopic simulations considering the Two-Temperature Model. These tools allow us to get a complete picture of the evolution of the target at a microscopic level, from the heating process to the melting and expansion stages, with a clear view of the physics involved during these processes. This article is part of the theme issue ‘Dynamic and transient processes in warm dense matter’.

In this paper, the structural and electronic properties of P/SnBr2 heterojunctions were investigated using the first-principles calculation method based on the density functional theory (DFT). The band alignment of the P/SnBr2 heterojunction was type I. The bandgap value was 0.71 eV in the DFT calculation. Furthermore, the bandgap of the heterojunction could be efficiently tuned by controlling an electric field and biaxial strain. The bandgap changed linearly with the electric field in a certain range; when the electric field was greater than 0.8 V/Å, the heterojunction was metallic. The bandgap could also be tuned when a biaxial strain was applied. Under tensile or compressive stress, significant effects such as the band alignment shift from type I to type III, and the transition from indirect to direct bandgap occurred. In conclusion, these research findings provide theoretical guidance for designing new heterojunctions based on SnBr2.

The specific crystalline form of a compound remarkably affects its physicochemical properties. Therefore, a detailed analysis of the structural features and intermolecular interactions of a multi-component crystal is feasible to understand the relationships among the structure, physicochemical properties and the formation mechanism. In the present study, three novel cocrystal salt solvates of rhein and berberine were reported for the first time. Various solid characterizations and theoretical computations based on density functional theory (DFT) were carried out to demonstrate the intermolecular interactions. The theoretical computation shows that the strongest interaction existed between berberine cation and rhein anion, and the electrostatic interaction play a dominant role. However, no salt bond was observed between them. Further intrinsic dissolution rate analysis in water shows that the monohydrate exhibits 17 times enhancement in comparison with rhein. The rhein and berberine combined in ionic state in cocrystal salt is the main reason for the solubility improvement. This paper suggests that the interactions between the different components can be visualized and qualitatively and quantitatively analyzed by theoretical computation, which is helpful to understand the relationship between stereochemical structure and physicochemical properties of multi-component complex.

Funding Information: T. G. thanks the HPC‐EUROPA3 (INFRAIA‐2016‐1‐730897) for a travel grant and CSC, the Finnish IT Center for Science, for the computing resources. We would like to thank Björn Koch and Dr. Tobias Chemnitz for the recording of all infrared spectra of the currently experimentally accessible molecular hexafluorides presented in this paper. We thank Solvay for the kind donations of F. Open access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2023 The Authors. ChemPhysChem published by Wiley-VCH GmbH. Quantum chemical methods were used to study the molecular structure and anharmonic IR spectra of the experimentally known closed-shell molecular hexafluorides MF6 (M=S, Se, Te, Xe, Mo, W, U). First, the molecular structures and harmonic frequencies were investigated using Density Functional Theory (DFT) with all-electron basis sets and explicitly considering the influence of spin-orbit coupling. Second, anharmonic frequencies and IR intensities were calculated with the CCSD(T) coupled cluster method and compared, where available, with IR spectra recorded by us. These comparisons showed satisfactory results. The anharmonic IR spectra provide means for identifying experimentally too little studied or unknown MF6 molecules with M=Cr, Po, Rn. To the best of our knowledge, we predict the NdF6 molecule for the first time and show it to be a true local minimum on the potential energy surface. We used intrinsic bond orbital (IBO) analyses to characterize the bonding situation in comparison with the UF6 molecule.

Pollution flashover on insulators is one of the greatest challenges affecting the smooth operation of high-voltage transmission lines. Demonstrating super-hydrophobic coatings on insulators’ interfaces is an effective measure to prevent insulator flashovers. In the present investigation, a super-hydrophobic FAS-17-modified SiO2/PDMS coating on a composite insulator was demonstrated by spraying. The coating had a contact angle of 159.2° and a sliding angle of 1.3° with better insulation properties. The prepared FAS-17-modified nano-SiO2 nanoparticles were not easy to agglomerate; to illustrate this, the binding energy was calculated by the density functional theory. The super-hydrophobic mechanism of the coating was explained in terms of the adsorption energy between SiO2 molecules and water before and after modification. This paper provides a new method to solve the pollution flashover problem of insulators and a new angle to explain the super-hydrophobic mechanism.

In this paper, the ternary system La2O3-TiO2-Nb2O5 is studied to find new ternary phases with useful electrical properties. The solid solution La3−xTi5−3xNb10−2xO39.5−12.5x was recently identified, and this study focuses on the structural characterization of this solid solution with x = 0.04. The crystal structure, representing a new structural type, was determined from synchrotron and neutron powder diffraction data. The unit cell parameters are a = 7.332 Å, b = 7.421 Å, c = 10.673 Å, α = 84.15°, ß = 80.16°, γ = 60.37°, and space group P1¯. The titanium and niobium atoms are disordered in five different crystallographic sites coordinated octahedrally by oxygen atoms. The eight-coordinated La atoms are embedded in the octahedral framework. Ti and Nb preferentially occupy different sites, and this feature was studied using periodic density functional theory methods. Energies of possible Ti/Nb distributions were calculated and the results agree well with the site occupancies obtained by combined Rietveld refinement of synchrotron and neutron powder diffraction patterns. The geometries optimized by DFT also agree well with the structural parameters determined by diffraction. The general agreement between the theoretical calculations and the experimental data justifies the quantum chemical methods as reliable complementary tools for the structural investigation of ceramic materials.

The last few decades have seen an immense development of interest in two-dimensional materials, which can be integrated in either mono-, bi-, tri- or tetra-layer form. The tuning of physical properties of 2D materials is a prevalent challenge since they disclose enormous opportunities for electronic and opto-electronic devices. The functionality of two dimensional (2D) materials can be enhanced through several external factors such as strain, defects, doping, electric field, stacking, and mechanical stress, etc. Recently, the two-dimensional III-V (III = B, Al, Ga, In, Tl and V = N, P, As, Sb, and Bi) monolayers have been theoretically discovered. The present research has been designed to study the variations in their properties under a small range of external electric field. Previous studies have been highlighted which suggested that electric field can be an effective approach to improve the physical properties of 2D materials. In this paper, the influence of an external electric field, in the range of −0.3 VA−1 to 0.3 VA−1, on the structural, electronic and optical properties of III-V monolayers has been investigated using the first-principles calculations in the context of density functional theory (DFT). The results suggest that monolayers retain their geometrical properties. However, the electric field enhances the strength of covalent bonds. The results also disclose that the bandgap of these monolayers can be widely tuned with the help of electric field. As the electric field is raised, few of the monolayers exhibit transition from semiconducting to conducting behavior. Moreover, the optical absorption is also observed to modify with electric field. The amount of absorption and the energy at which electronic transitions occur vary uniformly with electric field. The transparency of few monolayers in visible region alongwith maximum absorption in UV region ensures their potential for Visible-blind UV detectors, flat panel displays and window layers in solar cells. The bandgap-type transition promise their application in low-power electronic devices and widely tunable bandgap shows their potential for various opto-electronic devices. The findings of this paper focus on the contribution of III-V monolayers to the development of more efficient electronic and opto-electronic devices.

The fault type of GIS during running is related to the decomposition of the insulating gas SF6. In this paper, the adsorption behavior of three representative gases (SO2, SOF2, and SO2F2) decomposed by SF6 under unfavorable conditions at high temperature on the surface of Sc-doped WSe2 monolayers was discussed based on density functional theory. Adsorption systems of three target gases on Sc-WSe2 were developed, and the structural parameters, density of states and frontier molecular orbitals were calculated. The results show that the adsorption performance of target gases on Sc-WSe2 is better than that on intrinsic WSe2, indicating that the effectiveness of utilizing Sc atoms for modification. The strong interaction between WSe2 monolayers embedded with Sc atoms and gases confirmed the stability of the system in complex environments. Our findings are of great significance in the construction of atomically modified WSe2 gas sensors for detecting SF6 decomposition gases.

Among all inorganic perovskite, CsPbI3 has the closest ideal bang gap for solar cells. However, the instability of metal halides hinders its commercial application. The doping of A-site organic cations might improve the stability of perovskite and also make the bandgap adjustable, thus enhance its photoelectric properties. In this paper, the structure stability, electronic structure and optical properties of CsPbI3 with five different organic cations (H3NNH2+, CH3NH3+, C3H6NH2+, CH3NH2CH3+, CH3CH2NH3+) partially alternative doping instead the A site cation have been studied by using the first principles within density functional theory. In order to get accurate description of the bandstructure information, different exchange–correlation functions, e. g. PBE, PBE + SOC and HSE were used to describe the calculated systems, our calculation results indicated that the PBE exchange–correlation function can describe the electronic properties of the systems very well in this paper. Formation energy calculation indicates that all the doping systems are thermally stable; and all the doped CsPbI3 show good tolerance factor according Goldschmidt rule. Among the five different doping systems, the bandgap of doped H3NNH2+ will decrease to 1.28 eV, while the bandstructure of other doped cations will widen the bandgap. The maximum bandgap increased to 1.65 eV with doping C3H6NH2+. However, all the band structures are mainly contributed by inorganic framework. The results suggest that the structure doped organic cations can be exited stably, and the band edge of the optical absorption spectrum will be redshifted. These properties can provide research ideas for the subsequent research of A-site doping organic cations.

Based on the density functional theory (DFT) combined thermodynamics method, the flue gas arsenic forms from the coal-fired power plants were successfully confirmed at different temperature ranges, and the interaction mechanism of the fly ash unburned carbon (UBC) components on different gaseous arsenic species were also investigated. The content of trivalent arsenic (As3+) is the highest in flue gas, and its morphological distribution is significantly affected by the flue gas temperature. When the flue gas temperature is lower than 900 K, the As2O3 molecules are dominant in the trigonal bipyramid type. While when the temperature exceeds 900 K, the priority structure of As2O3 is chain type > horn type > trigonal bipyramid type in turn. This paper has verified the feasibility for the adsorption of flue gas arsenic via the unburned carbon in fly ash, and the performance of the zigzag carbon surface is always better than the armchair surface. This paper provides theoretical support for arsenic removal in coal-fired power plants, and also provides some new ideas for the secondary utilization of fly ash and the development of carbon-based arsenic removal adsorbent.

Recently, the two-dimensional biphenylene with sp2-hybridized carbon atoms has been successfully fabricated by experiment [Science, 372, 852 (2021)]. In this paper, the thermal expansion properties of monolayer biphenylene (MBP) are investigated by using the density functional theory combined with Gruneisen's theory. It is found that MBP exhibits anisotropic and negative in-plane thermal expansion and the negative thermal expansion is up to 1000 K. Although MBP and graphene have similar sp2 hybridized planar structure, the MBP exhibits significantly larger thermal contraction than graphene over a wide temperature range (0–1000K). At 300 K, the linear thermal expansion coefficient of MBP along the a-direction (1.10 × 10−5 K−1) is about three times that of graphene (3.7 × 10−6 K−1). The extraordinary negative thermal expansion not only originates from the ripple effect as in graphene only, but also the rigid unit modes are responsible for the thermal expansion behavior.

In this paper, utilization of density functional theory (DFT) to obtain mechanical, electrical and thermal properties of crystalline materials are reviewed. DFT has resulted as an efficient tool for predicting ground states of many body systems thus aiding in resolving dispersion spectrums of complex atomic arrangements where solution by traditional Schr dinger (SH) equation is infeasible. Great success has been reported by previous researchers on utilizing DFT for functional property predictions of crystalline solids.

Surface modification is a simple and efficient method to enhance the gas sensing properties of semiconductor materials. In this paper, Fe2O3 nanoparticle-decorated ZnO nanorods are successfully fabricated by a facile two-step synthesis method. The SEM, TEM and XPS results indicate that the Fe2O3 nanoparticles grow directly on the surface of ZnO nanorods. The gas sensing properties of pure ZnO and Fe2O3/ZnO nanocomposites have been systematically analyzed. The gas response value of a 1 wt% Fe2O3/ZnO sample is 14.5 to 100 ppm triethylamine (TEA) at the optimal operating temperature of 260 °C, which is about 3 times that of pure ZnO (5.0). In addition, the 1 wt% Fe2O3/ZnO sensor reflects a rapid response/recovery time (1 s/14 s). The density functional theory (DFT) simulation results confirm that after the Fe2O3 cluster modifies the surface of ZnO, the atomic position at the interface changes significantly and the structure of Fe2O3/ZnO has the lowest adsorption energy for TEA molecules; these are the key factors for improving the gas sensitivity of the composite sample.

GIS plays an irreplaceable role in the modern electrical system. However, partial discharge will inevitably occur under insulation defect conditions and may lead to serious insulation malfunction. The online monitoring method based on gas sensor is a feasible method to diagnose the severity of partial discharge in GIS. In this paper, metal oxide (TiO2, Fe2O3, NiO) cluster-modified single-layer graphene was proposed as a novel gas sensor to detect the characteristic components of SF6 decomposition products, SOF2 and SO2F2. Density functional theory calculations were carried out to study the gas adsorption and sensing mechanisms. The adsorption structures of gas molecules and the metal oxide cluster-modified single-layer graphene were built and optimized. Then, the most stable structure was selected to analyze the corresponding adsorption parameters. Calculation results showed that metal oxides decoration reduces the energy gap, improving the electrical conductivity and enhancing the adsorption activity of the graphene surface. According to DOS and CDD analyses, TiO2 modification obtained the best adsorption effect. Calculation results show that the metal-oxide-modified graphene sensor provides an effective method for effectively estimating the operating state of GIS by detecting SF6 decomposition products.

In this paper, the optimization of the structure of di(hydroxybenzyl) diselenide and its studies on HOMO and LUMO energy levels, hardness and Mulliken population using density functional theory (DFT)are reported. Molecular optimization is carried out at all the eight GGA functionals. The total minimum energy is calculated for the titled molecule at various functionals are in the order of BLYP > RPBE > BOP > PBE > PW91 > VWN-BP > BP > HCTH. Therefore, the results obtained at BLYP functional are considered for the remaining study of this work. From the contribution of the bands, the calculated HOMO-LUMO electronic transition is 2.101 eV. The study of HOMO and LUMO is extended to the calculation of the electron affinity, the ionization potential, and the chemical hardness. Chemical shifts for 1H and 13C NMR are also predicted. In 1H and 13C NMR, H25/ H32 and C5/C16 resonance signals are expected to be highly deshielded based on the Mulliken population analysis.

Marcasite (FeS2) is widespread in nature, its oxidation plays a vital role in acid mine drainage, mineral resource recovery, and photoelectric material applications. In this paper, the oxidation mechanism of marcasite has been studied for the first time using density functional theory (DFT). It is found that, unlike the oxidation of pyrite, the oxidation of marcasite merely occurs at surface S atoms. Under the coexistence of water and oxygen, S atoms around surface Fe atoms are replaced by O atoms. The surface S sites are initially oxidized to form S==O bonds, and continue to adsorb oxygen to gradually generate SO32−, SO42− species, and eventually FeSO4. In this process, H2O molecules participate in neither oxidation nor dissociation, and they are adsorbed on surface Fe sites in the form of molecules, i.e., all O atoms in SO42− derive from oxygen rather than water molecules.

Half-Heusler alloys are prominent material for spintronics devices as these materials usually exhibit high spin polarization. But this spin polarization is severely affected by various disorders and distortions which ultimately hinders their practical applications. This paper examines the effect of the uniaxial strain as well as the tetragonal strain on the electronic and magnetic properties of half-Heusler FeCrAs alloy. This work is carried out by using the first-principles density functional theory calculations using the Wein2k software. The results of our study show that FeCrAs alloy exhibiting AFM and FM characteristics in u- strain while showing only FM characteristics in t- strain. The Half metallicity of the FeCrAs is sensitive in negative u-strain while it is quite robust in positive u-strain and t-strain the FeCrAs. The maximum value of band gap at 0% tetragonal-strain is about 1.04 eV. The FeCrAs Heusler alloy preserve the 100% spin polarization for whole studied range of tetragonal-strain (−10% to 10%). This property may make this system a promising candidate for spin transfer torque application.

This paper describes the spectroscopic (FT-IR and UV–Visible), electronic, structural, vibrational properties of celecoxib compound using density functional theory. The optimized geometry structure of the titled molecule is explained by the method of B3LYP with 6–31 + G (d, p) basis set. We found that the simulated optimized geometry of the titled molecule is simulated to the experimental ones. The infrared spectrum of celecoxib compound is represented in the present work. The computational information about the organic molecule can be explained by the charge transfer properties, which is a computational tool for the precise quantum chemical calculations of space charge density distribution and HOMO-LUMO states. The transition states of celecoxib compound have explained by the time-dependent density functional theory (TD-DFT) which is observed by the UV–visible spectrum. Docking research [1] is a modeling method, with the help of docking method we can find out new drug and chemical behavior of the drug which is useful in the application purpose of the drug, the interaction between protein and legends provides the information of the binding energy and physical parameter like partition function, free energy, internal energy, entropy.

Selenium nucleic acids possess unique properties and have been demonstrated to have a wide range of applications such as DNA X-ray crystallography and novel medical therapies. Yet, as a heavy atom, selenium substitution may easily alter the photophysical properties of nucleic acid by red-shifting absorption spectra and introducing effective intersystem crossing to triplet excited states. In this paper, excited state dynamics of a natural occurring selenium substituted uracil (2-selenuracil, 2SeU) is studied by using femtosecond transient absorption spectroscopy as well as quantum chemistry calculation. Ultrafast intersystem crossing to the lowest triplet state (T1) and effective non-radiative decay of this state to the ground state (S0) are demonstrated in neutral form 2SeU. However, the triplet lifetime of the deprotonated form 2SeU is found to be almost one order of magnitude longer than that in the neutral one. Quantum chemistry calculation indicates that the short triplet lifetime in 2SeU is due to excited state population decay through a crossing point between T1 and S0. In the deprotonated form, shorten of N1-C2 bond length makes the structural distortion more difficult and brings larger energy barrier on the pathway to the T1/S0 crossing point, resulting one order of magnitude increase of triplet state lifetime. Our study reveals one key factor to regulate the triplet lifetime of 2SeU and set the stage to further investigate the photophysical and photochemical properties of 2SeU substituted DNA/RNA duplexes.

In this paper, the effects of the sulfur vacancy (VS) distribution in 2H–MoS2 monolayer on the H2 evolution mechanism and activity are researched by density functional theory (DFT) calculations. The calculation results reveal that the H2 generation on VS follows the Volmer-Heyrovsky mechanism with the Heyrovsky reaction as the rate determined step (RDS) with an energy barrier of 18.5 kcal/mol. When two VS are separated by one S atom, the H2 evolution on VS remains the Heyrovsky-step-determined Volmer-Heyrovsky mechanism and the RDS energy barrier increases to 20.0 kcal/mol. Removing adjacent S of VS causes that the Tafel-step-determined Volmer-Tafel mechanism works for HER and the barrier of RDS increases to 21.4 kcal/mol. Though the barriers of RDS ascend when the concentration of VS is enhanced by these two strategies, the Tafel step can take place at a lower potential and more VS are exposed. Therefore, two adjacent or next-near VS may obtain better H2 generation performance. Three adjacent or spaced out VS by one S may be less favorable for HER.

Oxidative stress and metal dyshomeostasis are considered crucial factors in the pathogenesis of Alzheimer’s disease (AD). Indeed, transition metal ions such as Cu(II) can generate reactive oxygen species (ROS) via O2 Fenton-like reduction, catalyzed by Cu(II) coordinated to the amyloid-beta (Aβ) peptide. Despite intensive efforts, the mechanisms of ROS-induced molecular damage remain poorly understood. In the present paper, we investigate, on the basis of Density Functional Theory (DFT) computations, a possible mechanism of the OH radical propagation toward membrane phospholipid polar head and fatty acid chains starting from the end-product of the OH radical generation by Cu(II)-Aβ. Using phosphatidylcholine as a model of a single unit inside a membrane, we evaluated the thermochemistry of the OH propagation with the oxidation of a C-H bond and the formation of the radical moiety. The DFT results show that Cu(II)-Aβ-OH can oxidize only sn-2 C-H bonds of the polar head and can easily oxidize the C-H bond adjacent to the carbon–carbon double bond in a mono or bis unsaturated fatty acid chain. These results are discussed on the basis of the recent literature on in vitro Aβ metal-catalyzed oxidation and on the possible implications in the AD oxidative stress mechanism.

В данной работе методом теории функционала плотности проведен расчет энергий адсорбции бензольного кольца на маленьких кластерах Pd (состоящих из четырех или девяти атомов). Показано, что адсорбция бензола на кластерах палладия ведет к заметному выигрышу системы в энергии: -146 кДж/моль в случае Pd и -117 кДж/моль в случае Pd. Кроме того, для системы Pd * CH рассчитаны энергии адсорбции хлор-, бром- и йоданизола. Показано, что адсорбция йоданизола, характеризующаяся наибольшим выигрышем системы в энергии (-278 кДж/моль), происходит диссоциативно и безактивационно, что принципиально отличает его от хлор- и броманизола. Полученные данные могут использоваться для объяснения различий в поведении катализаторов на основе сверхсшитого полистирола в реакциях кросс-сочетания различных арилгалогенидов c фенилбороновой кислотой, а также того факта, что арилйодиды могут провоцировать образование гомогенных форм палладия. In this paper, the density functional theory calculations were carried out in order to find the adsorption energies of a benzene ring on small Pd clusters consisting of four or nine atoms. The adsorption of benzene on palladium clusters was found to result in a noticeable energy gain of the system: -146 kJ/mol in the case of Pd, and -117 kJ/mol in the case of Pd. The adsorption energies of chloro-, bromo- and iodoanisole on Pd * CH were also calculated. The adsorption of iodoanisole was characterized by the highest energy gain of the system (-278 kJ/mol) and occurred dissociatively without activation, that fundamentally distinguished it from chloro- and bromoanisole. The data obtained can be used to explain the differences in the behavior of catalysts based on hypercross-linked polystyrene in cross-coupling reactions of various aryl halides and phenylboronic acid, and also the fact that aryl iodides can favor the formation of homogeneous forms of palladium.

Electronic structures, the effect of the substitution, structure physicochemical property/activity relationships and drug-likeness applied in pyrazine derivatives, have been studied at ab initio (HF, MP2) and B3LYP/DFT (density functional theory) levels. In the paper, the calculated values, i.e., NBO (natural bond orbitals) charges, bond lengths, dipole moments, electron affinities, heats of formation and quantitative structure-activity relationships (QSAR) properties are presented. For the QSAR studies, we used multiple linear regression (MLR) and artificial neural network (ANN) tatistical modeling. The results show a high correlation between experimental and predicted activity values, indicating the validation and the good quality of the derived QSAR models. In addition, statistical analysis reveals that the ANN technique with (9-4-1) architecture is more significant than the MLR model. The virtual screening based on the molecular similarity method and applicability domain of QSAR allowed the discovery of novel anti-proliferative activity candidates with improved activity.

Climate change and global warming are the visible consequences of the increased amount of carbon dioxide (CO2) in the atmosphere. Among the various sources of anthropogenic CO2 emission, the diesel engine has a significant contribution. The development of a reliable system to efficiently minimize CO2 emissions from diesel engines to the safest level is lacking in the open literature. Therefore, a comprehensive multidisciplinary approach has been applied in this paper to investigate the efficacy of the post-combustion carbon capture (PCC) process for the diesel engine. The experiments have been performed on the exhaust of a direct injection diesel engine at five different brake powers with blends of aqueous ammonia (AQ_NH3), monoethanolamine (MEA), N,N-dimethylethanolamine (DMEA), and 1-ethyl-3-methylimidazolium tetrafluoroborate (C2mim BF4) ionic liquid (IL) as an absorbent for CO2 capture. The reaction mechanism of these absorbent with CO2 are also studied by the geometrical, energetical, MESP, frontier molecular orbitals, and NBO analysis using the first-principles density functional theory (DFT) calculations. The maximum CO2 absorption efficiency of almost 97% was achieved for the blend consisting of 67% of AQ_NH3 and 33% of MEA. Moreover, AQ_MEA and blend of AQ_NH3, DMEA, and C2mim BF4 ionic liquid showed 96% and 94% CO2 absorption efficiency, respectively.

In this paper, the electronic effects of the adsorption of thyroid stimulating hormones (TSH) on two-dimensional structures of graphene and ψ-graphene are theoretically investigated by means of the density functional theory (DFT). Initially, the binding energies of TSH molecules on graphene (both the zigzag and armchair structures) and ψ-graphene are computed at different spatial orientations using the Siesta code. The most stable orientations had the following binding energies: –1.04 eV for triiodothyronine on graphene, –1.25 eV for thyroxine on graphene, –0.97 eV for triiodothyronine on ψ-graphene, and –0.95 eV for thyroxine on ψ-graphene. Subsequent to identifying the most stable orientations, the current-voltage characteristics of graphene and ψ-graphene monolayers, before and after the adsorption of TSH molecules are calculated by the TranSiesta computational software package, using the non-equilibrium Green’s function approach. The adsorption of the TSH molecules on the both graphene structures reduced the passing electric current significantly. The findings show that graphene sheets can be used to synthesize fast responding TSH nano-biosensors.

In this paper we present a thorough description of the digital twin development for a continuous pharmaceutical powder blending process in accordance with the Process Analytical Technologies (PAT) and Quality by Design (QbD) guidelines. A low-dosage system of caffeine active pharmaceutical ingredient (API) and dextrose excipient was examined via continuous blending experiments. Near infrared (NIR) spectroscopy-based process analytics were applied; quantitative evaluation of spectra was achieved using multivariate data analysis. The blending system was represented with mechanistic residence time distribution (RTD) models and two types of recurrent artificial neural networks (ANN), experimental datasets were used for model training or fitting and validation. Detailed comparison of the two modelling approaches, the optimization of the model-based digital twin, and efficiency of the soft sensor-based process monitoring is presented through several validating simulations. Both RTD models and nonlinear autoregressive neural networks demonstrated excellent predictive power for the low dosage blending process. RTD models can prove to be more advantageous in industrial development as they are less resource-intensive to develop and prediction accuracy on low concentration levels lacks dependency from the precision of chemometric calibration. Reduced material costs and limited development timeframe render the digital twin an efficient tool in technological development.

Since controlling strain in different types of heterostructures devices causes the improvement of properties and functionalities in real devices, considering this matter is vital in simulation. In this paper, the impact of strain in the interface of different layers of solar cells has been investigated with density functional theory (DFT) and finite-difference time-domain (FDTD) techniques. We have simulated the complex issue of strain and relaxation of atomic layers by using a new, effective and simple method and using a precise meshing technique. The amplitude and region of the strain have been meshed to specific values. The lattice strain is included in both simple and gradient patterns in the theoretical simulations. The strain factor has been considered in two steps; between active layers in solar cells and between the active layer and the electron transport layer (ETL). DFT results indicate alterations in the structural and optical properties of the material as a function of strain. The results of DFT have been used in FDTD simulation. To describe this new method, we used perovskite as the active layer in the solar cell. We realized that the electric and optical parameters such as short circuit current density, absorptance, and reflectance of strained solar cells are different in comparison to strain free cells, and applying strain to the contacting layers in the solar cell alters the optoelectronic properties of the device.

In this paper, the novel 3D hollow Z-scheme heterojunction photocatalysts based on Bi2O3 and CoAl layered double hydroxides (Bi2O3@CoAl-LDHs) were prepared for efficient visible-light-driven photocatalytic ammonia synthesis. The synthesized nanohybrid exhibits excellent photocatalytic ammonia synthesis performance (48.7 μmol·L−1·h−1) and structural stability, which is primarily attributed to the fact that Z-scheme heterojunction significantly enhanced lifetime of photogenerated carriers (6.22 ns) and transfer efficiency of surface photogenerated electrons (72.5%). Strict control experiments and nitrogen isotope labeling results show that nitrogen and hydrogen in the produced ammonia come from nitrogen and water in the reactant respectively. Electron paramagnetic resonance (EPR) experiments and density functional theory (DFT) calculations further reveal that the built-in electric field due to the difference between Bi2O3 and CoAl-LDHs is the key to constructing the Z-scheme heterojunction. In addition, results of partial density of states (PDOS) show that Co in Bi2O3@CoAl-LDHs composite is the active site for photocatalytic N2 fixation.

The experimental discovery of the highest, up to 0 degree Celsius, superconducting transition temperatures T $$_c$$ in the class of so-called hydrides under high pressure is undoubtedly the striking event in modern physics. In this paper, we give a short overview of the some history of the room-temperature conventional superconductivity. A theoretical description of such high T $$_c$$ , as was shown and even predicted in a number of ab initio works, can be unambiguously given in the framework of the electron–phonon mechanism of Cooper pairing. Thus, the basic equation to calculate T $$_c$$ will be the one proposed in 1957 by Bardeen, Cooper, and Schriefer. It is known that in this case the value of T $$_c$$ is directly determined by a number of effective parameters: the Debye frequency, the density of electronic states at the Fermi level, and the electron–phonon interaction constant. Within the framework of the modern development of the density functional theory, all these quantities can be obtained using standard packages for band structure calculations.

The paper deals with the electronic impact of ancillary ligands on the varying redox features of azobis(benzothiazole) (abbt) in the newly introduced mononuclear ruthenium complexes [Ru(pap)2(abbt)]n (1n) and [Ru(bpy)2(abbt)]n (2n), where pap = 2-phenylazopyridine and bpy = 2,2'-bipyridine. In this regard, the complexes [RuII(pap)2(abbt•-)]ClO4 ([1]ClO4), [RuII(pap)2(abbt0)](ClO4)2 ([1](ClO4)2), [RuII(bpy)2(abbt0)](ClO4)2 ([2](ClO4)2), and [RuII(bpy)2(abbt•-)]ClO4 ([2]ClO4) were structurally and spectroscopically characterized. Unambiguous assignments of the aforestated radical and nonradical forms of abbt in 1+/2+ and 12+/22+, respectively, were made primarily based on their redox-sensitive azo (N═N) bond distances as well as by their characteristic electron paramagnetic resonance (EPR)/NMR signatures. Although the radical form of abbt•- was isolated as an exclusive product in the case of strongly π-acidic pap-derived 1+, the corresponding moderately π-acidic bpy ancillary ligand primarily delivered an oxidized form of abbt0 in 22+, along with the radical form in 2+ as a minor (

In the field of electrolysis of water, the design and synthesis of catalysts over a wide pH range have attracted extensive attentions. In this paper, Co and N are co-introduced into the structural unit of tungsten disulfide (WS2), and the hydrogen evolution reaction (HER) performances of different WS2-based catalysts are theoretically predicted and systematically studied by density functional theory (DFT) calculations. With the guidance of DFT calculations, an evaporation-pyrolysis strategy is applied to prepare Co and N co-doped WS2 (Co,N-WS2) flower-like nanosheets, which exhibits excellent HER performance over a wide pH range. In addition, the DFT calculations show that the active sites in Co,N-WS2 have a good ability of hydrogen adsorption after the introduction of Co and N, suggesting that such a co-doping system will be an ideal catalyst for oxidative dehydrogenation (ODH). The following experiment results indeed evidence that the Co,N-WS2 catalyst displays a high activity in the ODH of 1,2,3,4-tetrahydroquinoline (4H-quinoline) and its derivatives. Therefore, this work provides a good example for the rational design and accurate preparation of functional catalysts, which enables it possible to develop other efficient catalysts with multiple functions.

In the field of photocatalytic water splitting, the direct Z-scheme heterostructure is regarded as a promising photocatalyst configuration. In this paper, we use density functional theory to predict the Ti2CO2/CrSSe heterostructure as a potential direct Z-scheme heterojunction photocatalyst and investigate its electronic, optical, and heterojunction interface properties. The results show that the Ti2CO2/CrSSe heterojunction has a strong electrostatic attraction between the electrons in the conduction band of Ti2CO2 and the holes in the valence band of CrSSe due to the small interlayer band gap, which can realize the rapid interlayer electron-hole (e−–h+) recombination. The redistribution of charge results in a built-in electric field that prevents unwanted electron and hole migration. In addition, the Ti2CO2/CrSSe van der Waals (vdW) heterojunction exhibits excellent light absorption, and its redox ability has been improved. These properties indicate that Ti2CO2/CrSSe heterostructure is a promising photocatalyst.

This paper systematically examines the performance of contemporary wavefunction and density functional theory methods to identify robust and cost-efficient methods for predicting gas-phase anion binding energies. This includes the local coupled cluster LNO-CCSD(T) and DLPNO-CCSD(T), as well as double-hybrid DSD-PBEP86-D3(BJ) and various hybrid functionals M06-2X, B3LYP-D3(BJ), ωB97M-V, and ωB97X-V. The focus is on dual-hydrogen-bonding anion receptors that are commonly found in supramolecular chemistry and organocatalysis, namely, (thio)ureas, deltamides, (thio)squaramides, and croconamides as well as the yet-to-be-explored rhodizonamides. Of the methods examined, M06-2X emerged as the overall best performing method as the other functionals including DSD-PBEP86-D3(BJ) and the local coupled cluster DLPNO-CCSD(T) method displayed systematic errors that increase with the degree of carbonylation of the receptors. Hybrid ONIOM models that employed semiempirical methods (PM7, GFN1-xTB, and GFN2-xTB) and "threefold"-corrected small-basis set potentials (HF-3c, B97-3c, and PBEh-3c) were explored, and the best models resulted in 50- to 500-fold reduction in CPU time compared to W1-local. These calculations provide important insight into the structure-binding relationships where there is a direct correlation between Brønsted acidity and anion binding affinity, though the strength of the correlation also depends on other factors such as hydrogen-bonding geometry and the geometrical distortion that the receptor needs to undergo to bind the anion.

In this paper, a method for the enzymatic modification of pectin, in which gallic acid (GA) and propyl gallate (PG) were grafted onto pectin molecules in an aqueous/organic two-phase system catalyzed by lipase, was proposed. The potential reaction mechanism was explored through UV–Vis, FTIR and 1H NMR spectroscopic methods and density functional theory. Results suggested that the lipase played a dual role during the modification by catalyzing the hydrolysis of methyl ester bonds of pectin in the aqueous phase and the esterification between the 4-OH of GA and PG and the –COOH of pectin in the organic phase. Moreover, the effects of GA and PG on the antioxidant and the antibacterial activities of pectin were evaluated, and results showed that the antioxidant and the antibacterial activities of modified pectin were better than those of native pectin. The effect of modified pectin on the quality of fresh bass (Lateolabrax maculatus) was further studied. Results suggested that, compared to control group, the total viable count, histamine level, malondialdehyde content and acid value of bass fillets treated with modified pectin were significantly reduced, whereas the sensory score was significantly increased.

In this paper, a statistical physics theory was used to analyze the adsorption isotherms of three Donor (D)-π -Acceptor (A) dyes bearing pyridyl group on TiO2 for dye sensitized solar cells. The experimental data of these organic dyes fit with a monolayer model with two binding sites. Our model is established with the statistical physics approach and contain parameters with a clear physical significance rightly connected to the adsorption mechanism of all adsorbates. The main advantage of this development is to give physical meaning to all involved parameters to be able interpret information about physical adsorption at the molecular level which remains unapproachable by means of empirical methods. The modeling by the adequate model provides new microscopic and macroscopic information included in the adsorption process that did not arise in any case of all previous works. The result shows that the values of adsorption energies proved that a chemisorption process occurred. The density functional theory (DFT) determined the different adsorbed modes, the electronic structure, energy level alignment and electronic density difference maps (EDDs) of the three dyes. The energy levels alignment indicates that the dye regeneration in the NI-4/TiO2 system is the most efficient in DSSCs application. The EDDs showed that the electron density decreases and increases at the dye/TiO2 interface, which is beneficial for the intermolecular electron transfer (IET) process. The DFT calculations support the statistical physics modeling and confirm the strong coordinate bonding between the pyridine ring of dyes NI-4, YNI-1 and YNI-2 and the TiO2 surface.

Background and Objectives: Polyelectrolyte capsules are one of the most promising materials for targeted drug delivery – one of the rapidly developing areas of modern chemistry, pharmacology and medicine. They have a wide range of applications due to various methods of controlling their physical and chemical properties. In this paper, the possibility of drug delivery and retention in cells due to the formation of hydrogen bonds between a polyelectron capsule and highly toxic drugs on the example of mitoxantrone is investigated by molecular modeling. Materials and Methods: Using molecular modeling by the B3LYP density functional theory method with a base set of 6–31 G (d), we analyze the formation of hydrogen bonds and their effect on the IR spectra and structure of the molecular complex formed as a result of the interaction of the drug mitoxantrone and polyelectrolyte capsules consisting of polyarginine and dextran sulfate. Due to the large size of the polyarginine molecule, which consists of repeating fragments, one link is used in the work, namely arginine. Results: As a result of calculations, various variants of molecular complexes consisting of mitoxantrone, polyarginine and dextran sulfate were considered. The results have shown that dextran sulfate forms weak hydrogen bonds with polyarginine and with mitoxantrone. Polyarginin forms strong and close to strong bonds with mitoxantrone. Conclusions: Based on the results obtained, it can be concluded that polyarginine plays a significant role as a substance that holds mitoxantrone in the capsule, and dextran sulfate, on the contrary, plays the role of a buffer substance. Encapsulation can be considered as one of the main mechanisms of targeted drug delivery and their retention in the cells and, thus, increasing the therapeutic effectiveness of drugs.

Synthetic ester can replace the mineral oil traditionally used in transformers to avoid the environmental problems caused by oil leakage. However, the fast discharge phenomenon in a high electric field in transformers using synthetic ester seems to indicate its insulation property is inferior to that of mineral oil. In this paper, typical molecular models of synthetic ester, including F2, F4, F6, F8, and F10, are constructed. We studied the effect of electric fields on the molecular properties of the five molecules by density functional theory and time-dependent density functional theory. According to the electric field intensity required for discharge initiation and propagation in insulating oil, the electric field intensity applied in this study varied from 108 to 109 V/m. The results showed that the molecular bond lengths are obviously dependent on the electric field. The ionization potential (IP) of the F8 and F10 molecules decreases sharply under electric field intensities of 3.1 × 109 and 4.0 × 109 V/m. It can be inferred that the IP reduction of the long carbon chain molecules, such as F8 and F10, is the reason for the formation of fast discharge in the case of synthesis ester. Calculations for excited states show that the introduction of an electric field makes the electron transition more active. The results obtained by this work improve our understanding of the discharge mechanism in synthetic ester dielectrics and provide theoretical support for improvement in the performance of synthetic ester insulating oil.

This paper aimed to study the effects of fullerene (C60) impregnation on the isoreticular metal-organic framework (IRMOF) materials MOF-650 (ZnO4 nodes were connected to azulenedicarboxylate linkers), MOF-5(ZnO4 nodes were connected to benzenedicarboxylate linkers), and IRMOF-10 (ZnO4 nodes were connected to biphenyldicarboxylate linkers) for H2 storage, these IRMOFs had similar structures but different pore volumes and organic linkers. Density functional theory (DFT) and grand canonical monte Carlo (GCMC) calculations indicated that C60 plays an important role in balancing the gravimetric and volumetric H2 densities of the IRMOFs. The C60@IRMOFs revealed improved volumetric density when H2 was undersaturated but reduced gravimetric density under H2 saturation. The saturated gravimetric H2 density of the IRMOFs was decided by the free volume. At 77 K, C60@MOF-650 had a gravimetric H2 density of 5.3 wt% and volumetric H2 density of 42 g/L under 10 bar, and C60@IRMOF-10 had a gravimetric H2 density of 7.4 wt% and volumetric H2 density of 43 g/L under 18 bar. These values nearly meet the United States Department of Energy (DOE) gravimetric and volumetric H2 density ultimate targets (gravimetric H2 density, 6.5 wt%; volumetric H2 density, 50 g/L) under ambient pressures. Among the studied IRMOFs, C60@MOF-650 and C60@IRMOF-10 demonstrated the best H2 storage properties at 233 and 298 K.