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41.
A new Schiff base hydrazone (Z)‐2‐(2‐aminothiazol‐4‐yl)‐N′‐(2‐hydroxy‐3‐methoxybenzylidene) acetohydrazide (H2L) and its chelates [VO (HL)2]·5H2O, [Cu (HL)Cl(H2O)]·2H2O and [Fe(L)Cl(H2O)2]·3H2O have been isolated and characterized using different physico‐chemical methods, for example infrared (IR), electron paramagnetic resonance (EPR), thermogravimetric analysis and DTG in the solid state, and 1H‐NMR, 13C‐NMR and UV in solution. Magnetic and UV–visible measurements proposed that the coordination environments are square pyramidal, tetrahedral and octahedral geometries for oxovanadium (IV), Cu (II) and Fe (III), respectively. The ligand acts as mono‐negative NO towards oxovanadium (IV) and Cu (II) ions, and bi‐negative ONO for Fe (III) ion. The geometries of the ligand and its complexes were performed using Gaussian 9 program with density functional theory. The EPR spectral data of oxovanadium (IV) and Cu (II) chelates confirmed the mentioned geometries. The molecular modeling was done, and illustrated bond lengths, bond angles, molecular electrostatic potential, Mulliken atomic charges and chemical reactivity for the inspected compounds. Theoretical IR and 1H‐NMR of the free ligand were calculated. Furthermore, thermodynamic and kinetic parameters for thermal decomposition steps were studied. Docking study of H2L was applied against the proteins of both bacterial strains Staphylococcus aureus and Escherichia coli, as well as the protein of xanthine oxidase as antioxidant agent by Schrödinger suite program utilizing XP glide protocol. Furthermore, antimicrobial, antioxidant and DNA‐binding activities of the compounds have been carried out. 相似文献
42.
《Comptes Rendus Mecanique》2019,347(8):601-614
During machining processes, materials undergo severe deformations that lead to different behavior than in the case of slow deformation. The microstructure changes, as a consequence, affect the materials properties and therefore influence the functionality of the component. Developing material models capable of capturing such changes is therefore critical to better understand the interaction process–materials. In this paper, we introduce a new physics model associating Mechanical Threshold Stress (MTS) with Dislocation Density (DD) models. The modeling and the experimental results of a series of large strain experiments on polycrystalline copper (OFHC) involving sequences of shear deformation and strain rate (varying from quasi-static to dynamic) are very similar to those observed in processes such as machining. The Kocks–Mecking model, using the mechanical threshold stress as an internal state variable, correlates well with experimental results and strain rate jump experiments. This model was compared to the well-known Johnson–Cook model that showed some shortcomings in capturing the stain jump. The results show a high effect of rate sensitivity of strain hardening at large strains. Coupling the mechanical threshold stress dislocation density (MTS–DD), material models were implemented in the Abaqus/Explicit FE code. The model shows potentialities in predicting an increase in dislocation density and a reduction in cell size. It could ideally be used in the modeling of machining processes. 相似文献
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Jesse Geneson 《Discrete Mathematics》2019,342(5):1489-1491
Permutations of the positive integers avoiding arithmetic progressions of length 5 were constructed in Davis et al. (1977), implying the existence of permutations of the integers avoiding arithmetic progressions of length 7. We construct a permutation of the integers avoiding arithmetic progressions of length 6. We also prove a lower bound of on the lower density of subsets of positive integers that can be permuted to avoid arithmetic progressions of length 4, sharpening the lower bound of from LeSaulnier and Vijay (2011). 相似文献
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Juan Colmenero 《Journal of Polymer Science.Polymer Physics》2019,57(18):1239-1245
The diffusion of polymer chains in miscible polymer blends with large dynamic asymmetry—those where the two blend components display very different segmental mobility—is not well understood yet. In the extreme case of the blend system of poly(ethylene oxide) (PEO) and poly(methyl methacrylate)(PMMA), the diffusion coefficient of PEO chains in the blend can change by more than five orders of magnitude while the segmental time scale hardly changes with respect to that of pure PEO. This behavior is not observed in blend systems with small or moderate dynamic asymmetry as, for instance, polyisoprene/poly(vinyl ethylene) blends. These two very different behaviors can be understood and quantitatively explained in a unified way in the framework of a memory function formalism, which takes into account the effect of the collective dynamics on the chain dynamics of a tagged chain. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1239–1245 相似文献
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Dr. Qing Tang 《Chemphyschem》2019,20(4):595-601
Among the widely studied 2D transition metal dichalcogenides (TMDs), MoTe2 has attracted special interest for phase-change applications due to its small 2H-1T′ energy difference, yet a large scale phase transition without structural disruption remains a significant challenge. Recently, an interesting long-range phase engineering of MoTe2 has been realized experimentally by Ca2N electride. However, the interface formed between them has not been well understood, and moreover, it remains elusive how the presence of Ca2N would affect the basal plane reactivity of MoTe2. To address this, we performed density functional theory (DFT) calculations to investigate the potential of tuning the phase stability and chemical reactivity of a MoTe2 monolayer via interacting with Ca2N to form a van der Walls heterostructure. We found that the contact nature at the 2H-MoTe2/Ca2N interface is Schottky-barrier-free, allowing for the spontaneous electron transfer from Ca2N to 2H-MoTe2 to make it strongly n-type doped. Moreover, Ca2N doping significantly lowers the energy of 1T′-MoTe2 and dynamically triggers the 2H-to-1T′ transformation. The Ca2N-induced phase modulation can also be applied to tune the phase energetics of MoS2 and MoSe2. Furthermore, using H adsorption as the testing ground, we also find that the H binding on the basal plane of MoTe2 is enhanced after forming heterostructure with Ca2N, potentially providing basis for surface modification and other related catalytic applications. 相似文献
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