Diffraction Calculations Research Articles

Demonstration of feasibility and effectiveness of deep eutectic solvent-water system extraction of RG-I type pectin from wolfberry based on target polysaccharide, solvent and their interactions

Lycium barbarum fruit (wolfberry) is rich in rhamnogalacturonan-I (RG-I) pectin with favorable prebiotic activity. However, there is currently limited research on the targeted extraction of RG-I type pectin from Lycium barbarum fruit (LBP). DES is widely recognized as an efficient solvent for extracting bioactive compounds from plants. In this study, a mixture of choline chloride (ChCl) and propylene glycol (PG) at the molar ratio 1:2 with 20 wt% water content was optimal to extract LBP. The yield and extent of branching of LBP extracted by ChCl-PG-water system (LBP-P) were 1.74-fold and 2.87-fold higher than those of LBP extracted by water (LBP-W), respectively. Compared with LBP-W, LBP-P exhibited higher total neutral sugar and uronic acid contents, as well as lower molecular weight and viscosity. The proliferative ability of LBP-P on six Bifidobacterial strains was 1.06–1.92-fold greater than that of LBP-W. In addition, Fourier transform infrared spectroscopy (FTIR) and apparent viscosity proved that the role of water was to maintain strong hydrogen bonds of DES with reduced viscosity. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra and density functional theory (DFT) calculations proved that the role of DES was to penetrate cell walls and interact with target substances. The effective extraction mechanism of the DES-water system was based on cell wall cellulose disassembly, side chain exposure, and high-branched LBP dissolution stages. Our results provided a theoretical basis for targeted extraction of RG-I pectin using new solvents.

Molecular insights into histidine adsorption on Na-montmorillonite, anatase, and goethite

The adsorption of amino acids (AAs) on minerals plays a role in the geochemical processes that determine the availability of nutrients in the environment. Histidine can be used as typical basic AA because it is frequently detected in natural waters, soils, and sediments. Herein, the pH effects and time factor were analyzed to reveal the molecular-level mechanisms of histidine adsorption on Na-montmorillonite, anatase, and goethite. Attenuated total reflectance Fourier transform infrared (ATR–FTIR) flow-cell measurements, X-ray diffraction (XRD), and density functional theory (DFT) calculations were used to determine the adsorbed species structures and the time-dependent adsorption/desorption processes. The structures of adsorbed histidine were governed by pH conditions, but were not affected by time variations. The histidine adsorbed on the minerals was in the cationic (pH 4), neutral zwitterionic (pH 7.5), and anionic (pH 10.5) forms, which was consistent with those dissolved in solution at the same pH. Adsorption on the clay mineral montmorillonite was favorable due to the dominant interlayer adsorption mechanism at pH 4 and hydrophobic attraction (external basal surface) at pH 4–10.5. Histidine adsorption on the two metal (hydr)oxides was dominated by inner-sphere surface complexation, which involved one or two O atoms of the COO− group. The adsorbed histidine was in the monodentate form on anatase and in the bidentate form on goethite.

Short range order of glassy KSb5S8 by diffraction, EXAFS, vibrational spectroscopy and DFT calculations

We report on a detailed experimental and simulation study of the short- and medium-range order of a potential phase change material – glassy KSb5S8. On the experimental side, diffraction techniques and EXAFS have been employed to record accurate structural data. Structural models have been generated by fitting multiple datasets simultaneously with the reverse Monte Carlo simulation technique. In addition, density functional theory was employed to study the structure and vibrational modes of selected clusters, representative of the glass structure. Unconstrained RMC simulation runs revealed that the average Sb-S coordination number is 3.18 ± 0.2, thus Sb is mostly threefold coordinated in the glassy state. The fraction of edge and corner sharing SbSn polyhedra and distribution of bridging S atoms (Qn distribution) have also been obtained. Distribution of bridging S atoms around Sb is similar in the crystalline and glassy states. DFT calculations assisted in the identification of a Raman mode at ∼468 cm−1, assigned to hypervalent bonding (quasi-tetrahedral units) in the glass structure.

Stokes and Anti-Stokes Luminescent Rare-Earth-Doped Tantalum Oxide Nanoparticles.

Doping of nano- and microparticles of oxides with rare earth elements (REEs) is used to fine-tune their structural, optical, and electrochemical properties. On the way to establish the structure-property relationship, we dope tantalum oxide (Ta2O5) particles with REEs to study their effect on the oxide structure and luminescence. Ta2O5 is highly perspective in medicine, catalysis, and optics, but its crystal structure is insufficiently studied. Two synthesis approaches (sol-gel and solvothermal) were used to obtain powders with different textures. Experimental and theoretical studies of amorphous and crystallized tantalum oxide NPs by means of X-ray powder diffraction, Rietveld analysis, EXAFS/XANES spectroscopy, and density functional theory calculations were performed. All samples (doped and undoped) crystallized in orthorhombic phase with no admixtures. It was demonstrated that Ta2O5 is a promising wide-spectrum luminescent material: by combining REEs, both Stokes and anti-Stokes luminescence in the visible region were obtained. By means of optical absorption spectroscopy, it was shown that the prepared samples could be classified as wide band gap semiconductors.

Active sites of Te-hyperdoped silicon by hard x-ray photoelectron spectroscopy

Multiple dopant configurations of Te impurities in close vicinity in silicon are investigated using photoelectron spectroscopy, photoelectron diffraction, and Bloch wave calculations. The samples are prepared by ion implantation followed by pulsed laser annealing. The dopant concentration is variable and high above the solubility limit of Te in silicon. The configurations in question are distinguished from isolated Te impurities by a strong chemical core level shift. While Te clusters are found to form only in very small concentrations, multi-Te configurations of type dimer or up to four Te ions surrounding a vacancy are clearly identified. For these configurations, a substitutional site location of Te is found to match the data best in all cases. For isolated Te ions, this matches the expectations. For multi-Te configurations, the results contribute to understanding the exceptional activation of free charge carriers in hyperdoping of chalcogens in silicon.

A new Cu-halide organic-inorganic hybrid compound's synthesis, single-crystal X-ray diffraction, vibrational investigations, optical characteristics, and DFT calculation: (C12H20N2)CuCl4

Through gradual evaporation at room temperature, single crystals of a novel Cu(II) halide complex (C12H20N2)CuCl4 (symbolized by 1PEPCu) were formed. Physical-chemical techniques such as X-ray diffraction, IR and Raman spectroscopy, UV–visible absorption, luminescence, and thermal analysis were used to identify this substance. CuCl42-anions and 1–2-phenylethylpiperazine-1,4-diium dications make up the crystal structure. Hydrogen bonds kept these components together, and van der Waals interactions also helped. To determine the relative significance of intermolecular interactions, Hirshfeld surfaces were used to explore the interactions between molecules. The presence of the vibrational functional groups of organic and inorganic substances is confirmed by the IR and Raman spectroscopy investigations. In addition, calculations using Density Functional Theory (DFT) have been carried out to precisely infer the experimental finding, and excellent agreement has been obtained. At room temperature, the UV–visible absorption and luminescence spectroscopies were investigated. The thermal behavior was investigated using TGA and DTA analyses. A molecular docking study suggests that 1PEPCu may have an inhibitory effect on coronavirus proteins (COVID-19 and SARS-CoV2).

A nanoscale ferromagnetic nickel-supercluster functionalized giant heterometallic arsenototungstate with ability in catalyzing reactive oxygen species generation

In this work, a high-nuclear functionalized giant heterometallic arsenototungstate with artificial oxidase property, [Na(H2O)5]2[Ni(H2O)(en)2]2[Ni(H2O)3(en)][H4Ni6 (OH)2(en)2.5(B-α-AsVW9O34)]2[W4O16][Ni4(H2O)2(en)2]2[Ni(H2O)(en)][(α-AsVW6O26)]2·3H2O (abbreviated as NiAW, en = ethylenediamine) has been designed and synthesized successfully. NiAW was structurally characterized by X-ray photoelectron spectrum (XPS), infrared (IR) spectrum, ultraviolet-visible (UV-vis) spectrum, single-crystal X-ray diffraction (SXRD) and bond valence sums (Σs) calculation. The SXRD results indicated that the skeleton of NiAW is constructed by two sandwich-type [(B-α-AsVW9O34)H4Ni6(OH)2(en)2.5(α-AsVW6O26)]4– sub-unit linking by a [W4O16]8– building block, in which a novel tetra-Ni cluster [Ni4(H2O)2(en)2O10]12– graft to the hexa-vacant Keggin [α-AsW6O26]11– fragment. Finally, with the embellishment of several [Ni(en)2(H2O)]2+, [Ni(en)(H2O)]2+, and [Na(H2O)5]+ cations, NiAW forms its complete structure. Notably, the Ni-cluster in NiAW exhibited the ferromagnetic coupling interactions. Furthermore, it is also demonstrated that NiAW is capable of catalyzing the generation of ROS efficiently by the synergistic effects of POM fragments and nickel complexes.

Synergistic Ion Diffusion in Lithium Titanium Phosphate Conductors: A Tale from Solo to Ensemble

The rational design of solid electrolytes for the next-generation batteries entails an accurate understanding of ionic transport mechanisms. To elucidate the detailed ion hopping processes in different coordinate environments, two solid electrolytes, LiTi2(PO4)3 and Li3Ti2(PO4)3, with the same NASICON-type framework but different sites for accommodating mobile ions, were synthesized and investigated by in situ neutron diffraction and theoretical calculations. The temperature-dependent anisotropic thermal vibrational ellipsoids and migration paths from the maximum entropy method (MEM) indicated that Li ions move faster at higher coordinate architectures, exhibiting three-dimensional (3D) diffusion pathways. In this rhombohedral structure, “one” node (M1 site) out of “three” interconnected transition sites was found to be the lithium configuration of NASICON. Li ions located at the nodes along the 3D pathway in LiTi2(PO4)3 can only drive out another Li-ion species at the node site, while Li ions located at transition sites between two nodes in Li3Ti2(PO4)3 have repulsive force from their five surrounding Li ions. These different configurations lead to distinct overall transport modes. In LiTi2(PO4)3, concerted Li ions transport along a separated chain, while in Li3Ti2(PO4)3, concerted motion occurs along multiple cooperating chains in the 3D channels. Theoretical calculations further indicated that a larger diffusion bottleneck size of Li3Ti2(PO4)3 enables lower hopping energy compared to LiTi2(PO4)3. This study clarifies the detailed ionic hopping processes and the underlying structure–conductivity relationships. Overall, these results elucidate the synergistic events in Li-ion hopping from thermodynamic and kinetic points of view, which will greatly benefit the rational design of solid electrolytes for next-generation batteries.

The conformational behavior and structure of monosubstituted 1,3,5‐trisilacyclohexanes—Part III: 1‐Methyl‐1,3,5‐trisilacyclohexane

Abstract1‐Methyl‐1,3,5‐trisilacyclohexane was synthesized and its structure and conformational properties have been determined by gas‐phase electron diffraction (GED) and quantum chemical (QC) calculations. The molecule may exist in two forms differing from each other by the substituent's position. QC results show that the equatorial conformer is predicted to be slightly more stable than the axial conformer; note that one method (M06‐2X) with basis set 6‐311G** shows an equal amount of Ax and Eq conformers: ratio (Ax/Eq) = (30–50):(70–50)% (depending on the method and basis set). From the GED data, the molar fractions of the conformers were found to be Ax:Eq = 54(10):46(10) at 280(5) K. A temperature‐dependent Raman experiment resulted in an Ax:Eq ratio of 58(4):42(4). Conformational properties are compared in series of analogous 1‐X‐1‐(hetero)cyclohexanes.

Effect of Zr substitution on the structure and magnetic properties of (Y, Zr) (Fe, Ti)12 compounds

Fe-rich ThMn12-type intermetallic compounds have attracted wide attention due to high potential in advanced permanent magnet motors. However, the necessary addition of the third elements M to stabilize the ThMn12-type structure leads to a substantial decrease of Ms, which becomes a barrier to improve the intrinsic magnetic properties. Some studies showed that substituting Zr for R at the 2a site helped reduce the content of M. In this paper, the effect of Zr substitution on the structure and magnetic properties of (Y, Zr) (Fe, Ti)12 compounds has been investigated utilizing neutron diffraction, magnetic measurement, and first-principles calculation. The results show that Zr substitution obviously enhances the stability and significantly reduces the content of Ti. In Y1-xZrxFe11.5Ti0.5 compounds, the competition between the magnetic volume effect and the chemical bonding effect of Zr leads to a maximum of Ms when Zr = 0.2. In addition, Y0.7Zr0.3(Fe0.75Co0.25)11.7Ti0.3 compound containing the lowest content of Ti is successfully prepared, with Ms and Tc reaching 163.4 Am2/kg (12.26 kG) and 843.4 K, respectively. The highest Ms of 167.7 Am2/kg (12.53 kG) and Tc of 829.6 K are obtained in Y0.7Zr0.3(Fe0.75Co0.25)11.6Ti0.4, which are superior to those of Nd-Fe-B and show great potential for permanent magnet applications.

Moving on from Silicon to the Heavier Tetrels: Germyl- and Stannyl-Substituted Phosphole Derivatives

Germyl- and stannyl-substituted phospholes have been prepared and isolated. The increased reactivity of the tetrel carbon bond requires increased effort in purification by initial transformation to the chalcogen derivatives and subsequent reduction to the phosphole after subsequent to chromatographic purification for the germanium derivative. The photophysical properties of the germyl phosphole are comparable to that of its silyl analogue, whereas the stannyl phospholes turned out to be nonluminescent. All isolated compounds have been characterized by NMR spectroscopy, mass spectrometry, and elemental analysis. Furthermore, single-crystal X-ray diffraction and density functional theory (DFT) calculations have been performed on selected compounds.

A semi analytic method for the analysis of the symmetric hydroelastic response of a container ship under slamming and green water loads

This paper presents a semi analytic time domain method for the analysis of the symmetric hydroelastic response of a container ship subject to slamming and green water loads. An Impulse Response Function (IRF) is adopted for the calculation of radiation, diffraction and wave excitation forces. Local hydrodynamic forces associated with green water on decks and slamming loads are respectively modelled by the Buchner’s Dam Break Model and a Generalised Wagner Model. The structural responses are captured by Euler-Bernoulli beam theory and solved by the modal superposition method. The Duhamel Integral technique is used to evaluate the dynamic response. A parametric study demonstrates how external forces may affect the global wave induced vertical bending moments and shear forces. Numerical simulations are compared against a hybrid method that combines computational fluid dynamics, boundary element and finite element methods for low to medium frequency induced dynamic response. It is concluded that the proposed semi analytic methodology is fast and accurate and may be useful at concept ship design stage.

Taming Super-Reduced Bi23- Radicals with Rare Earth Cations.

Here, we report the synthesis of two new sets of dibismuth-bridged rare earth molecules. The first series contains a bridging diamagnetic Bi22- anion, (Cp*2RE)2(μ-η2:η2-Bi2), 1-RE (where Cp* = pentamethylcyclopentadienyl; RE = Gd (1-Gd), Tb (1-Tb), Dy (1-Dy), Y (1-Y)), while the second series comprises the first Bi23- radical-containing complexes for any d- or f-block metal ions, [K(crypt-222)][(Cp*2RE)2(μ-η2:η2-Bi2•)]·2THF (2-RE, RE = Gd (2-Gd), Tb (2-Tb), Dy (2-Dy), Y (2-Y); crypt-222 = 2.2.2-cryptand), which were obtained from one-electron reduction of 1-RE with KC8. The Bi23- radical-bridged terbium and dysprosium congeners, 2-Tb and 2-Dy, are single-molecule magnets with magnetic hysteresis. We investigate the nature of the unprecedented lanthanide-bismuth and bismuth-bismuth bonding and their roles in magnetic communication between paramagnetic metal centers, through single-crystal X-ray diffraction, ultraviolet-visible/near-infrared (UV-vis/NIR) spectroscopy, SQUID magnetometry, DFT and multiconfigurational ab initio calculations. We find a πz* ground SOMO for Bi23-, which has isotropic spin-spin exchange coupling with neighboring metal ions of ca. -20 cm-1; however, the exchange coupling is strongly augmented by orbitally dependent terms in the anisotropic cases of 2-Tb and 2-Dy. As the first examples of p-block radicals beneath the second row bridging any metal ions, these studies have important ramifications for single-molecule magnetism, main group element, rare earth metal, and coordination chemistry at large.

Experimental and theoretical study of novel germanium tungstates compounds GexW1-xO3 (x ∼ 1/4, 1/2) and Ge1-xWO4 (x ∼ 0.2)

The crystal structures of three (03) novel germanium tungstates were investigated by single-crystal X-ray diffraction and density functional theory (DFT) calculations. The structures are characterized by distorted MO6(M = Ge/W) octahedral, forming infinite zigzag chains.In GexW1-xO3(x ∼ 1/4, 1/2), the systems display a transition from pure WO3 semiconducting to metal-like behavior by shifting down the Fermi level; this is due to germanium's lower valence, which acts as a p-type semiconductor by creating electron holes in the lattice.It was found that GexW1-xO3(x ∼ 1/4, 1/2) exhibits strong reflectivity and absorption in the near-infrared region, while weak reflectivity and absorption appear in the visible region.Compared to GeWO4, the estimated electronic density of states in Ge1-xWO4(x ∼ 0.2) shows a narrow band gap (0.89 eV) due to Ge-vacancies, which is considered the smaller band gap among analogous wolframites, resulting in an increase of the absorption and the relectivity in the visible region.

Analyzing multiple acoustic diffraction over a wide barrier using equivalent knife-edge geometries and Babinet's principle (L)

We present a new method for the calculation of the multiple acoustic diffraction caused by the presence of a wide barrier. Our solution decomposes the initial scenario into an equivalent sum of geometries that only consider knife-edges. Then, by applying Babinet's principle, the total acoustic field that reaches the receiving point, which can be located at an arbitrary position, can be calculated via the uniform theory of diffraction. This method is mathematically less complex and computationally more efficient than most existing techniques. The results are validated (with and without ground reflection) by the solid agreement obtained with other solutions that solve the problem by considering the wide barrier as such, with our proposed method yielding a lower computational time (except against semi-empirical formulations) and better accuracy when compared with measurements. The presented solution can be applied in urban environments where the impact of traffic noise on residential buildings located along roads or highways needs to be evaluated, as well as in scenarios in which the insertion loss caused by a rectangular obstacle, such as a noise barrier, is to be calculated.

MAX phase forming mechanism of M–Al–C (M = Ti, V, Cr) coatings: In-situ X-ray diffraction and first-principle calculations

• The phase evolution of MAX phases dependent on temperature were clarified using in-situ XRD. • First-principle calculations correlated with the experience revealed the phase forming mechanism. • The relationship between phase composition and mechanical properties was established. • This study provided a deeper understanding to guide the preparation of high-purity MAX phase coatings. The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the Mn+1AXn (MAX) phase attractive as a potential protective coating for vital structural components in harsh systems. However, an extremely narrow phase-forming region makes it difficult to prepare MAX phase coatings with high purity, which is required to obtain coatings with high-temperature anti-oxidation capabilities. This work describes the dependence of the phase evolution in deposited M–Al–C (M = Ti, V, Cr) coatings as a function on temperature using in-situ X-ray diffraction analysis. Compared to V2AlC and Cr2AlC MAX phase coatings, the Ti2AlC coating displayed a higher phase-forming temperature accompanied by a lack of any intermediate phases before the appearance of the Ti2AlC MAX phase. The results of the first-principle calculations correlated with the experience in which Ti2AlC exhibited the largest formation energy and density of states. The effect of the phase compositions of these three MAX phase coatings on mechanical properties were also investigated using ex-situ Vickers and nano-indenter tests, demonstrating the improved mechanical properties with good stability at high temperatures. These findings provide a deeper understanding of the phase-forming mechanism of MAX phase coatings to guide the preparation of high-purity MAX phase coatings and the optimization of MAX phase coatings with expected intermediate phases such as Cr2C, V2C etc., as well as their application as protective coatings in temperature-related harsh environments.

Superconductivity emerging from a pressurized van der Waals kagome material Pd3P2S8

Kagome materials have been reported to possess abundant and peculiar physical properties, which provide an excellent platform to explore exotic quantum states. We present a discovery of superconductivity in van der Waals material Pd3P2S8 composed of Pd kagome lattice under pressure. Pd3P2S8 displays superconductivity for those pressures where the semiconducting-like temperature dependence of the resistivity turns into a metallic one. Moreover, it is found that the increased pressure results in a gradual enhancement of superconducting transition temperature, which finally reaches 6.83 K at 79.5 GPa. Combining high-pressure x-ray diffraction, Raman spectroscopy and theoretical calculations, our results demonstrate that the observed superconductivity induced by high pressure in Pd3P2S8 is closely related to the formation of amorphous phase, which results from the structural instability due to the enhanced coupling between interlayer Pd and S atoms upon compression.

A Selective and Reversible Fluorescent Probe for Cu2+ and GSH Detection in Aqueous Environments

AbstractCu2+ and Biothiols play a critical role in diverse biological processes in organisms. Herein, we reported using a well‐known ESPT molecule 2‐(2’‐Pyridyl)benzimidazol(PBI) as a fluorescent probe to detect Cu2+ and GSH in aqueous solution. PBI presented a rapid fluorescence “ON‐OFF” response on Cu2+ over other metal cations, with a low detection limit (39.4 nM), and also been applied in real water samples detection. Through mass spectroscopy, single crystal X‐ray diffraction and DFT calculation, we confirmed that two PBI molecules would form a stable complex with one Cu2+. After adding GSH, PBI‐Cu2+ complex would release the free probe, and the “on‐off‐on” recognition process to achieve continuous detection of Cu2+ and GSH.

Orbital Nature of Carboionic Monoradicals Made from Diradicals.

The electronic, optical, and solid state properties of a series of monoradicals, anions and cations obtained from starting neutral diradicals have been studied. Diradicals based on s-indacene and indenoacenes, with benzothiophenes fused and in different orientations, feature a varying degree of diradical character in the neutral state, which is here related with the properties of the radical redox forms. The analysis of their optical features in the polymethine monoradicals has been carried out in the framework of the molecular orbital and valence bond theories. Electronic UV-Vis-NIR absorption, X-ray solid-state diffraction and quantum chemical calculations have been carried out. Studies of the different positive-/negative-charged species, both residing in the same skeletal π-conjugated backbone, are rare for organic molecules. The key factor for the dual stabilization is the presence of the starting diradical character that enables to indistinctively accommodate a pseudo-hole and a pseudo-electron defect with certainly small reorganization energies for ambipolar charge transport.

Direct Separation of UO2 2+ by Coordination Sieve Effect via Spherical Coordination Traps.

Molecule sieve effect (MSE) can enable direct separation of target, thus overcoming two major scientific and industrial separation problems in traditional separation, coadsorption, and desorption. Inspired by this, herein, the concept of coordination sieve effect (CSE) for direct separation of UO2 2+ , different from the previously established two-step separation method, adsorption plus desorption is reported. The used adsorbent, polyhedron-based hydrogen-bond framework (P-HOF-1), made from a metal-organic framework (MOF) precursor through a two-step postmodification approach, afforded high uptake capacity (close to theoretical value) towards monovalent Cs+ , divalent Sr2+ , trivalent Eu3+ , and tetravalent Th4+ ions, but completely excluded UO2 2+ ion, suggesting excellent CSE. Direct separation of UO2 2+ can be achieved from a mixed solution containing Cs+ , Sr2+ , Eu3+ , Th4+ , and UO2 2+ ions, giving >99.9% removal efficiency for Cs+ , Sr2+ , Eu3+ , and Th4+ ions, but <1.2% removal efficiency for UO2 2+ , affording benchmark reverse selectivity (SM/U ) of >83 and direct generation of high purity UO2 2+ (>99.9%). The mechanism for such direct separation via CSE, as unveiled by both single crystal X-ray diffraction and density-functional theory (DFT) calculation, is due to the spherical coordination trap in P-HOF-1 that can exactly accommodate the spherical coordination ions of Cs+ , Sr2+ , Eu3+ , and Th4+ , but excludes the planar coordination UO2 2+ ion.