Crystal System Research Articles

Optimization of sodium-ion battery cathode performance by nickel-based Prussian blue epitaxial growth with iron-based Prussian blue core-shell structure

To address the structural defects and poor electrical conductivity of conventional Prussian blue analogues (PBAs) samples, in this study, nickel hexacyanoferrate (NiHCF) and nickel hexacyanoferrate epitaxially grown with iron hexacyanoferrate (Ni@FeHCF-X) series of samples were successfully synthesized by co-precipitation combined with epitaxial growth technique, and their structural and electrochemical properties were systematically characterized. X-ray powder diffractometer (XRD) results show that all the samples maintain a cubic crystal system structure, and the diffraction peaks of the (220) and (400) crystal planes are shifted to a lower angle with the epitaxial growth of ferric hexacyanoferrate (FeHCF). The successful embedding of Fe was confirmed by inductively coupled plasma (ICP) measurement data. Scanning electron microscope (SEM) images show that the samples are in a cubic morphology, and the surfaces gradually become rounded from sharp to rounded with the increase of the Fe content. High-resolution transmission electron microscope (HRTEM) and energy-dispersive spectrometer (EDS) analyses confirm the successful construction of the core-shell structure and the homogeneous distribution of the elements. Electrochemical testing showed that the Ni@FeHCF-X samples exhibited higher specific capacities and superior rate performance compared to NiHCF, particularly the Ni@FeHCF-4 sample, which delivered a high specific capacity of 73.4 mAh·g⁻¹ at a current density of 100 mA·g⁻¹, significantly outperforming the 38.2 mAh·g⁻¹ achieved by NiHCF. Additionally, the capacity retention rate of Ni@FeHCF-4 reached 42.16 %. Electrochemical impedance spectroscopy (EIS) further confirmed the reduced charge transfer resistance and enhanced reversibility of the electrochemical reactions in the Ni@FeHCF-X samples. These results demonstrate that Ni@FeHCF-4 significantly enhances the electrochemical performance of the samples in aqueous sodium-ion battery, providing new insights into the design of cathode materials for sodium-ion batteries.

Crystal structure and optical properties of a new 0D Sb-based hybrid metal halide: (3,5-DMP)3Sb2Br9

Zero-dimensional (0D) lead-free hybrid organic-inorganic metal halides (OIMHs) have recently garnered tremendous attention due to their diversified structures and unique structure-dependent photoluminescent (PL) properties. Herein, we report a novel Sb-based 0D hybrid organic-inorganic metal halide (OIMH), with the chemical formula (3,5-DMP)3Sb2Br9 [3,5-DMP+ = 3,5-dimethyl piperidinium cation, C7H16N+]. The (3,5-DMP)3Sb2Br9 compound crystallizes in the triclinic crystal system (P1‾ space group), possessing a typical zero-dimensional (0D) structure with isolated face-sharing (Sb2Br9)3− bi-octahedral units encased by (3,5-DMP)+ organic cations. The isolated bi-octahedral units are distorted due to the strong stereochemical expression of the 5s2 lone pair on Sb3+ and intermolecular H-bonding between the organic moieties and inorganic clusters. The compound exhibited good thermal and environmental stability and possessed an indirect band gap of 2.92 eV. Upon 390 nm UV light excitation, the compound displayed a broad emission band centred at 555 nm, which was attributed to the self-trapped excitons (STEs) formed due to strong electron-phonon coupling in this compound. This study suggests the possibility of new types of 0D OIMHs by introducing different metal centers and bulky organic cations and provides a reference for the structure-property relationship in these compounds, thus, offering guidance for examining the structural evolution and improving their luminescent properties.

Crystal structure, microwave dielectric properties, and far-infrared spectroscopy of a novel low-dielectric constant tremolite ceramic CaZnGe2O6

The diopside-structured CaZnGe2O6 ceramics were synthesized using the conventional solid-state reaction method in this study, and their crystal structure, microstructural evolution, and microwave dielectric properties were systematically investigated. The XRD and Rietveld refinement analyses confirmed that CaZnGe2O6 crystallizes in the monoclinic crystal system with a C2/c space group. The intrinsic microwave dielectric properties of the ceramics were evaluated using far-infrared spectroscopy. The ceramic structure exhibits high density and microstructural homogeneity after sintering at 1130 °C, resulting in exceptional microwave dielectric properties achieved at this optimal temperature (εr = 8.78 Q×f = 63,782 GHz, τf = −66.4 ppm/°C). These findings highlight the potential application of CaZnGe2O6 ceramics as low-permittivity materials suitable for microwave devices.

Structure elucidation and computational studies of the thiazole derivative against SARS-CoV-2 virus: Insights from XRD, DFT, molecular docking, and molecular dynamics simulation

The present work is focused on the crystal structure, Hirshfeld surface, Density Functional Theory (DFT) studies of thiazole derivative N-benzyl-4-(4-bromophenyl)thaiazole-2-carboxamide (TT4). The crystal structure has been determined using single crystal X-ray diffraction analysis, which shows that the compound crystallizes in the monoclinic crystal system with space group P21/c. C-H⋯O type of hydrogen bond interaction is responsible for the crystal packing in crystal The molecular geometry optimization was performed by DFT calculations. The 2D scattered plot was generated by Reduced Density Gradient (RDG) analysis, which divulge the weak and noncovalent interactions in the compound TT4. In silico studies were carried out to delve into the binding pattern of the TT4 compound against SARS-CoV-2 proteins using molecular docking and molecular dynamics simulation. Finally, the binding free energy and the contributed energies were derived using MM-GBSA approach. The 7K40-ligand complex showed the highest binding free energy, and among all other interactions, the contributions of the covalent binding and van der Waals energy were found to be significant.

Naphthyl-functionalized acetamide derivatives: Promising agents for cholinesterase inhibition and antioxidant therapy in Alzheimer’s disease

This study presents the synthesis and characterization of a series of 13 novel acetamides. These were subjected to Ellman’s assay to determine the efficacy of the AChE and BChE inhibitors. Finally, we report their antioxidant activity as an alternative approach for the search for drugs to treat AD. These studies revealed that compounds 1a–1k and 2l–2m were obtained in moderate yield. Four amides (1h, 1j, 1k, and 2l) were selective for one of the enzymes (BChE); thus, those that inhibited BChE were more active than the positive control (galantamine) and showed better IC50 values (3.30–5.03 µM). The theoretical free binding energies calculated by MM-GBSA indicated that all inhibitors were more stable than rivastigmine, and the inhibition mechanisms involved the entire active site: peripheral anionic site, oxyanion hole, acyl-binding pockets, and catalytic site. We examined the cytotoxicity of compounds 1h, 1j, 1k, and 2l in human dermal cells and found that they did not exhibit any toxic effects under the tested conditions. Additionally, these compounds, which also inhibited BChE, displayed mixed inhibition and did not exhibit hemolytic effects on human erythrocytes. Furthermore, the ABTS and DPPH assays indicated that, although none of the compounds showed activity in the DPPH assay, the EC50 values for radical trapping by the ABTS method showed that compounds 1a, 1d, 1e, and 1g had EC50 values lower than 10 µg/mL, indicating their strong radical scavenging capacity. We also report the crystal structures of compounds 1c, 1d, 1f, and 1g, which are found in monoclinic crystal systems.

Novel Co(II), Cu(II) and Zn(II) complexes derived from thiazole containing Schiff base ligands: Green synthesis, antimicrobial and anti-cancer studies

Six novel metal complexes of Co(II), Cu(II), and Zn(II) were synthesized using a microwave-assisted method. These complexes were derived from Schiff base ligands prepared through the condensation of 4-(p-fluorophenyl)-5-methyl-2-aminothiazole with 3-methoxysalicyldehyde (L1) and 2-hydroxynaphthaldehyde (L2). Characterization techniques, including UV–vis, IR, NMR, and HR-MS confirm the tridentate nature of Co(II), Zn(II), and bidentate nature of Cu(II) complexes. Elemental and thermogravimetric analysis showed 1:2 (M: L) stoichiometry in metal complexes. Meanwhile, magnetic susceptibility and powder X-ray diffraction express the geometry and crystal systems of complexes. The antimicrobial analysis of the synthesized compounds indicates Cu(II) complexes have greater potency against gram-positive bacterial and fungal strains while Zn(II) complexes show a greater zone of inhibition against gram-negative bacterial strains. Moreover, MIC values of the most potent complexes [Cu(L2)2] and [Zn(L2)2] range from 190-375 µg/mL. Furthermore, ligands and their complexes have been tested for anticancer potential against MDA-MB 231 and A549 cell lines by MTT assay. [Zn(L1)2] and [Zn(L2)2] complexes were found to have potent activity with IC50 values of 16.7 µM, 24.1 µM, and 8.7 µM, 13.4 µM respectively on MDA-MB-231 and A549 cell lines compared to other complexes and parent ligands. Molecular docking study performed using the PyRx 0.8 (with RF-Score V2 scoring function) program against EGFR (PDB: 5XGM) showed strong binding interactions which supports the experimental results.

Infrequent trigonal crystal system CoNb thin films: investigation of growth behavior, microstructure and magnetic properties

Magnetic films with excellent initial permeability, high resonance frequency, suitable anisotropy fields, and well compatibility are highly desirable for on-chip inductors and transformers. Here, Co90Nb10 thin films with different thicknesses are grown on Si substrates of different orientations using an electron beam evaporation technique. A rare trigonal crystal structure of the CoNb films was observed and was virtually unaffected by substrate orientation. Films grown exhibit thickness-dependent magnetic behavior: coercivity initially decreases and then increases, while the in-plane anisotropy field progressively diminishes. Meanwhile, the initial permeability increases initially before decreasing, and the resonance frequency continuously decreases as the thickness increases. The resultant Co90Nb10/Si (111)-50 nm film displays a high μi of 496 and a great fr of 2.1GHz. The improved magnetic performance originates from the smaller crystallite size, smoother surface roughness, and suitable in-plane anisotropy field. Moreover, the in-plane anisotropy transition to the out-of-plane anisotropy in the Co90Nb10 films whose thickness exceeds 70nm, which is attributed to the growth of the coarse columnar grains once the critical thickness is exceeded. This study demonstrates the correlation between the growth behavior, microstructure, and magnetic properties of CoNb thin films, presenting a new potential for utilizing Co-based thin films in high-frequency applications.

Synthesis and Characterization of Air‐Stable Palladium(II) and Copper(I) Ph‐Garphos Complexes and their Applications to Asymmetric Catalysis

AbstractAir‐stable palladium(II) and copper(I) complexes containing the 4,4′,6,6′‐tetramethoxybiphenyl‐2,2′‐diyl)bis(diphenylphosphine) ligands, (R)‐Ph‐Garphos ((R)‐L1) and ((S)‐Ph‐Garphos ((S)‐L1), were synthesized and characterized by 1H‐, 13C‐, and 31P{1H} NMR spectroscopy and elemental analyses. The PdCl2((R)‐Ph‐Garphos) ((R)‐1) and PdCl2((S)‐Ph‐Garphos) ((S)‐1) complexes were assessed for the Suzuki‐Miyaura cross‐coupling of aryl halides with phenylboronic acid under ambient conditions, or naphthyl substrates under reflux. X‐ray crystal structures of the copper complexes revealed that [Cu((R)‐Ph‐Garphos)I] ((R)‐2) crystallized as a three‐coordinate monomer in the orthorhombic space group P212121 whereas [Cu((S)‐Ph‐Garphos)I] ((S)‐2) crystallized as a tetrahedral (μ‐I) dimer in the same crystal system. The synthesis of the analogous [Cu((R)‐Ph‐Garphos)OAc] ((R)‐3) is also described. Complexes (R)‐2 and (R)‐3 were evaluated for the asymmetric hydrosilylation of ketones wherein enantioselectivities of up to 83 % ee were achieved.

Antimicrobial Susceptibility of Food-Borne Pathogens Isolated from Frequently Consumed Cheeses in Bulgaria

Cheese is essential to the daily human diet. Rich in nutrients such as proteins and carbohydrates, it is the perfect environment for developing microorganisms. The study aimed to screen the antimicrobi¬al resistance of pathogenic microorganisms isolated from imported Bulgarian cheeses. Randomly picked isolates of bacteria and fungi were cultured in selective and differential media. Isolates were identified using the Crystal Gram-positives system, catalase, PYR-test, and API 20 C AUX Candida. Antimicrobial susceptibility screening was performed against 19 antibiotics and three antifungal substances, according to EUCAST-2023 (The European Committee on Antimicrobial Susceptibility Testing). Isolated bacteria were identified as pathogenic Enterococcus durans, two strains of Enterococcus faecalis 1 and 2, and Staphy¬lococcus simulans. Isolated yeasts belong also to pathogenic Candida krusei – four strains, and Candida glabrata – one strain. Only one strain - E. faecalis-2 showed resistance to three antibiotics from the class of Fluoroquinolones (Ciprofloxacin, Levofloxacin, and Norfloxacin) while the other bacterial strains: E. fae¬calis-1, E. durans, and S. simulans, were susceptible to all tested antibiotics. The fungal isolates C. krusei and C. glabrata demonstrated susceptibility to all three tested antifungal drugs.

N-Morpholine-N'-benzoylthiourea as an extractant for Pb(II) and Cu(II) in aqueous media: Crystal structure of bis(N-morpholine-N′-4-benzoylthioureato)lead(II)

The reaction of N-morpholine-N′-benzoylthiourea (L: HBMOR) and lead(II) acetate gave a neutral, stable metal(II) complex of type ML2. The Pb(II) complex crystallized in a monoclinic crystal system with P21/n space group. The complex was further characterized by spectroscopic and microanalytic analyses. The solvent extraction behaviors of Pb(II) and Cu(II) ions were investigated in aqueous media containing HBMOR/CHCl3 as extracting reagents. The solvent extraction of Pb(II) and Cu(II) ions from solutions of varying pH, varying concentrations of mineral acids (HCl, HNO3 and H2SO4), varying concentrations of masking agents (EDTA, KCN and KH[C8H6O4]) and varying concentrations of salting-out agents (NaCl, Na2SO4, KNO3) in chloroform solutions of HBMOR were studied. Pb(II) and Cu(II) ions were quantitatively extracted at pH = 7 in 10 min (HCl = 0.01 M) and pH = 8 in 5 min (H2SO4 = 0.01 M), respectively. The Pb(II) ions were quantitatively extracted with minimal interference from EDTA (0.01 M), KCN (0.50 M), and potassium hydrogen phthalate (1.0 M), while the Cu (II) ions were extracted with EDTA (1.0 M), KCN (1.0 M) and potassium hydrogen phthalate (0.01 M). The order of increasing interference for the extraction of Pb(II) and Cu(II) ions was KCN > potassium hydrogen phthalate > EDTA. Sodium sulfate (0.01 M) in HCl enhanced the extraction of Pb(II) ions, while sodium chloride (0.50 M) in HCl enhanced the extraction of Cu(II) ions. pH0.5 values of 0.67 and 2.70 were obtained for Pb(II) and Cu(II) ions, respectively, indicating that the separation of the two metal ions is favorable with HBMOR.

Mongrel synthesis of tin (IV) based 3-aminopyridine with hydrogen halides: Structural, optical, thermal analysis, DFT, Hirshfeld surface analysis and antibacterial investigations

The novel organic-inorganic hybrid materials (C5H7N4)2 [SnCl6] 2- (1) and (C5H7N4)2 [SnBr6]2-(2) have been synthesized and characterized by single-crystal X-ray diffraction at room temperature. Both compounds demonstrate the crystal system was triclinic with Pī space group. Hirshfeld surface analysis investigate the intermolecular interactions and crystal packing derived by single-crystal XRD data reveals the closer contacts associated with strong interactions. Infrared spectrum of both compounds shows the NH stretching band at 3396 cm−1 which indicates a protonated amine group. The product crystals optical characteristics were inspected using UV–visible and photoluminescence spectroscopy. The thermal characteristics were evaluated simultaneously using thermogravimetric (TG) and differential thermal analysis. Tin formal oxidation state was determined as +4 through bond valence sum calculations and CSM shows the ideal octahedral geometry of the anions. DFT calculations utilizing the B3LYP method with the LanL2DZ basis set provide optimized geometries and molecular electrostatic potential maps. We explored the energy difference between (HOMO) and (LUMO) orbitals to understand molecular electrical transport capabilities. The biological activity of the investigated compounds are examined against pathogens which indicates efficacy against bacterial strains.

Design, synthesis, structural analysis, and DFT calculation insights into the molecular architecture of amino substituted 4H-chromene scaffolds

Amino-substituted 4H-chromene scaffolds, comprising nitrogen and oxygen, have garnered significant attention in modern organic chemistry due to their widespread applications in medicinal chemistry, drug discovery, and material sciences. This study demonstrates the synthesis and investigation of a series of 2-amino-3-cyano-4H-chromenes. The molecular structures of these compounds were established using X-ray diffraction, which revealed their supramolecular features. The fused 4H-chromene molecules crystallise in monoclinic and triclinic crystal systems with space groups P-1, P21/c, C2/c, and P21/n. These molecules show interactions like O-H···O, N-H···O, N-H···N, C‑H···O, and C-H···N, along with the π–π stacking and C–H···π arrangements. Hirshfeld surface analysis confirmed the presence of these interactions, and 2D fingerprint plots quantified their contributions. The structural aspects of the compounds, including their optimised molecular geometry and intramolecular hydrogen bonding, were examined using Density Functional Theory (DFT). The constructed structures showed a strong correlation with experimental results. Additionally, the molecular electrostatic potential was studied to understand the energy distribution and chemically reactive regions of the molecules.

Study of the Sintering Process Behavior on Some Structural and Physical Properties of (Ni-47Ti-3Cu) Alloy Prepared by Powder Metallurgy

This research aims to prepare the alloy (Ni-47Ti-3Cu) using powder metallurgy techniques and study the sintering behavior of this alloy at different temperatures. Powders of nickel, titanium, and copper, were mixed to ensure homogeneity, then compacted under a pressure of (5ton) for (2 min) to obtain cohesive samples. The sintering process was carried out at temperatures of (1050, 950, 850, 750, 650) °C for 1 hour. The structural properties were studied using X-ray diffraction (XRD), and the physical properties (apparent density, bulk density, porosity, and water absorption) were examined using Archimedes' principle-based tests. The XRD results indicated the emergence of a new phase with a different crystalline structure from the elements used in the preparation of the models, identified as (TiCuNi2) with a rhombohedral crystal system, while the constituent elements of the alloy exhibited face-centered cubic (F.C.C) structures for nickel and copper and a hexagonal close-packed (H.C.P) structure for titanium. The physical examination results showed that both apparent and bulk densities increased with increasing sintering temperature, while porosity and water absorption decreased with increasing sintering temperature.

The luminescent behaviors and J-O theory analysis of red phosphor Ca1-xGeO3:xEu3+

The luminescent material Eu3+-doped CaGeO3 has been synthesized using a high-temperature solid-state reaction technique. The crystal structure was analyzed using X-ray diffraction (XRD). The results showed that the samples belonged to the triclinic crystal system with the space group P1̅. The luminescent properties including photoluminescence excitation (PLE), Photoluminescence emission (PL) spectra, and lifetime, thermal stability, and diffuse reflectance spectroscopy (DRS) have been investigated. Under near-ultraviolet excitation at 390 nm, the phosphor emits red light with the highest intensity around 611 nm, which is dominated by the 5D0→7F2 electric dipole transitions. It indicates that Eu3+ is in the inversion center of the crystal. The concentration quenching occurs at about 6 % doping from the concentration-dependent luminescence behavior. The energy transfer mechanism was analyzed to be mainly the energy transfer between neighboring ions. The thermal stability was 82.16 % at 423 K. The chromaticity coordinates are in the red area and the color purity approaches 99 %. Furthermore, the J-O theoretical results are used to confirm the experimental result. It suggests that Ca1-xGeO3:xEu3+ is an effective red luminescent material for illumination and backlight display applications.

Synthesis, growth and nonlinear optical properties of imidazolium hydrogen adipate monohydrate single crystal

A single crystal of Imidazolium Hydrogen Adipate Monohydrate (IHAM) has been obtained by the slow evaporation technique. The grown crystal belongs to the Triclinic crystal system. The spectral studies were further used to confirm the structure. The Hirshfeld analysis suggests that the major bonding in the crystal occurs through the Hydrogen atom constituting 69 % of the total bonding. The Void analysis shows a lower percentage of voids suggesting that the crystal is strongly packed. The optical constants such as optical and electrical conductivity, optical susceptibility and extinction coefficient were elucidated from the UV–Vis-NIR analysis. The refractive index of IHAM was determined to be 1.391 by the Prism Coupler. The work-hardening coefficient of the title compound was found to be 1.14 which classifies the material as hard. The hardness number shows the normal Indentation Size Effect (ISE). The electrical characteristics were studied by using the dielectric analyser. The solid-state parameters such as the Fermi gap, Penn gap and optical electronegativity were calculated based on the dielectric parameters. The electronic polarizability calculated by different methods is in mutual agreement. The TG/DTA analysis suggests that the material is suitable for applications up to 79 °C. The Z-Scan analysis confirms the Reverse Saturable Absorption behaviour. The third-order nonlinear susceptibility was calculated as 9.77×10−9 esu.

Investigation on growth, structural, mechanical, linear and nonlinear optical properties of DiLithium Fumarate TetraHydrate single crystal

In this work reports on the growth and characterization of semiorganic NLO single crystal of DiLithium Fumarate TetraHydrate (DLFTH) using a slow evaporation technique. The crystal structure was an orthorhombic crystal system with the centrosymmetric space group Pbcn, as demonstrated by single crystal X-ray diffraction (SCXRD) investigations. The UV–Vis-NIR spectrum is used to derive optical parameters, such as the lower cut off wavelength (277 nm) and optical energy band gap Eg = 4.98 eV. DLFTH crystals belongs to hard material category using Vickers microhardness test. From NLO studies, the nonlinear optical parameters were studied, such as the nonlinear refractive index (n2), absorption coefficient (β) and third order NLO susceptibility (χ3). The crystal has the properties of saturable absorption and self-defocusing nature. Third order NLO susceptibility (χ3) were found to be 4.14384 × 10-10esu. The higher χ3 number is due to the presence of hydrogen bonds between C-H-O and O-H-O atoms. Therefore, we confirm that it’s applicability for optical device applications.

Unclonable Encryption-Verification Strategy Based on Bilayer Shape Memory Photonic Crystals.

The ability to reversibly exhibit structural color patterns has positioned photonic crystals (PCs) at the forefront of anti-counterfeiting. However, the security offered by the mere reversible display is susceptible to illicit alteration and disclosure. Herein, inspired by the electronic message captcha, bilayer photonic crystal (BPC) systems with integrated decryption and verification modules, are realized by combining inverse opal (IO) and double inverse opal (DIO) with polyacrylate polymers. When the informationized BPC is immersed in ethanol or water, the DIO layer displayed encrypted information due to the solvent-induced ordered rearrangement of polystyrene (PS) microspheres. The verification step is established based on the different structural colors of the IO layer pattern, which result from the deformation or recovery of the macroporous skeleton induced by solvent evaporation. Moreover, through the evaporation-induced random self-assembly of PS@SiO2 and SiO2 microspheres, unclonable structurally colored identifying codes are created in the IO layer, ensuring the uniqueness upon the verification. The decrypted code in the DIO layer is valid only when the IO layer displays the pattern with the predetermined structural color; otherwise, it is a pseudo-code. This structural color-based "decryption-verification" approach offers innovative anti-counterfeiting applications in nanophotonics.

Ratiometric fluorescence sensor based on dye-encapsulated Zn-MOF for highly sensitive detection of diquat in tap water and apple samples

The development of convenient and intelligent visualization of rapid pesticide detection methods is key to ensuring food quality and safety. This paper presents a smartphone-based ratiometric fluorescence sensor for smart field visualization and detection of diquat (DQ). Three-dimensional Zn-MOFs are prepared by the solvothermal method using the rigid ligand 4,4′,4″-s-triazine-2,4,6-triyltribenzoic acid (H3TATB), the flexible ligand 1,4-bis((1H-imidazol-1-yl)methyl)benzene (bimb), and the transition metal (Zn2+), which shows good structural and thermal stability. Zn-MOF is a three-dimensional framework crystallizing in a triclinic crystal system in the Pī space group. Then, RhB@Zn-MOF is obtained by introducing rhodamine B (RhB) into the Zn-MOF framework using the same method. Internal Filter Effect (IFE) quenches red fluorescence and Fluorescence Resonance Energy Transfer (FRET) enhances blue fluorescence, enabling high sensitivity and visual detection of DQ. The sensor has a low detection limit of 10.50 nM and is linear over the 0–70.00 μM concentration range. Compared to Zn-MOF (detection limit of 16.90 nM), the introduction of RhB significantly improved the precision and sensitivity of DQ detection. The combination of a smartphone and RGB analysis enables fast and accurate quantitative analysis of DQ in tap water and apple samples. The sensor platform has the advantages of convenience, intelligent real-time detection, etc. It has a wide prospect of practical application and consolidates a solid foundation for food safety control.

Synthesis and full characterization of tert-butyl (4-ethynylphenyl)carbamate

Structure and conformation of tert-butyl(4-ethynylphenyl)carbamate, the compound combining carbamate and alkyne parts within the molecule, were studied using single X-ray diffraction analysis, NMR, FTIR and UV–vis spectroscopies. For unambiguous assignment of the signals 1H and 13C-APT-NMR, HMQC and HMBC-NMR experiments were realized. The compound crystallized in orthorhombic crystal system, displaying NHO hydrogen bonds and CH-π interactions. The X-ray structure has been recreated by means of theoretical calculations in order to assess the proposed arrangement and discuss the source of the intra and intermolecular relationships. The use of Grimme, Wiberg and Hirshfeld surface tools were applied to have a good confirmation of the presence and importance of hydrogen bonds.

Crack-tip cleavage/dislocation emission competition behaviors/mechanisms in magnesium: ALEFM prediction and atomic simulation

Structural properties and reliability of materials can be improved by increasing fracture toughness. At the atomic scale, the fracture is a material separation process, and the fracture toughness of materials is associated with the atomic-scale crack-tip behaviors/mechanisms. The crack-tip behaviors are relevant to the energy state of atoms in the system. Atomic thermal oscillation increases with increasing temperature, which may affect/alter the crack tip behaviors. This work is the first to investigate the temperature-dependent crack-tip cleavage/dislocation emitting competition in magnesium (Mg) using anisotropic linear elastic fracture mechanics theory, Density Functional Theory (DFT), and atomic simulation. Crack-tip behaviors are examined using a specially designed ‘K-field’ loads model. DFT calculations show that a single crystal system with lower entropy and higher Gibbs free energy implies stronger interatomic bonding that favors a higher KIc. Changes in the stress distribution initiate a brittle-ductile transition in crack-tip behavior. The ductile crack tip can be blunted by continuous crack-tip dislocations nucleation/slip, and the evolution of the ductile crack-tip geometry from sharp to semicircular structure significantly decreases the stress concentration at the crack tip. A new criterion of the crack-tip force vector is established, which reasonably explains the geometrical evolution of ductile crack tip where the angle θ between the crack plane and the slip plane is 0∘<θ<90∘ and θ=90∘. This work expands the atomic-scale brittle/ductile crack-tip behaviors/mechanisms of Mg, which provides a reference for crack-tip behavior analysis in engineering research.