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Graphene oxide (GO) nanoreinforcement is shown to significantly improve the strength and durability of concrete at the expense of mix workability. While polycarboxylate superplasticizers (PCSP) addition has improved GO-cement/mortar strength and workability in existing literature, this article examines if this improvement is translated to concrete with lower cement and water contents. PCSP and GO showed colloidal instability and particulate aggregation through surface charge measurements, presumably caused by divalent Ca 2 + ion interbridging between the GO and PCSP. This chemical interference results in a 26% reduction in 28-day compressive strength and a 20% decrease in the workability of PCSP-treated GO-concrete. Microstructural examination reveals significantly larger pores in PCSP+GO cement than in GO-cement or PCSP-only cement due to the chemical interference induced by PCSP-GO interactions in cement and concrete. Hence, PCSP and GO interactions must be further researched for practical use in concrete structures. [ABSTRACT FROM AUTHOR]

La0.67Sr0.33MnO3 (LSMO) thin films were fabricated on (011)- and (001)-Pb(Mg1/3Nb2/3)1 − xTixO3 (PMN-PT) substrates to investigate the mechanism of electric field regulation. Both (011)- and (001)-LSMO/PMN-PT heterostructures exhibit electric-field-dependent resistance curves with an asymmetric butterfly shape under a bipolar electric field (±10 kV/cm). Confirmed through a mathematical method, the "butterfly" and "asymmetric" characteristics indicate the volatile strain and non-volatile ferroelectric field effects, respectively. However, by applying a unipolar electric field, the electric-field-dependent resistance curves of the (011)-LSMO/PMN-PT heterostructures present a larger loop shape than those in the (001)-LSMO/PMN-PT heterostructure, which is related to the non-volatile strain effect. The volatile strain, non-volatile strain, and ferroelectric field effects on the resistance of the LSMO films are associated with the enhanced or weakened double exchange coupling. [ABSTRACT FROM AUTHOR]

Fe3O4 with high Curie temperature and 100% spin polarization is a potential candidate for practical applications in flexible spintronics. In this work, combined with flexible muscovite substrates, the dynamic strain influenced Verwey transition of Fe3O4 has been studied. The Verwey transition temperature increases (decreases) in the inward (outward) bending heterostructures. From the analyses of Fe L2,3 edge X-ray absorption spectroscopy, the reversible modulation originates from the charge reconstruction effect with the valence variations of Fe ions on the tetrahedral site and octahedral site in different bending states. Meanwhile, the charge reconstruction effect enhances the net magnetic moments of the Fe3O4/muscovite heterostructures in bending states. [ABSTRACT FROM AUTHOR]

The spin-Hamiltonian parameters (g factors g//, g⊥ and zero-field splitting D) of the trigonal Cr3+ centers in Cr3+-doped ABO3 (A = Sc, In, Lu) borate crystals are computed from both the complete diagonalization (of energy matrix) method and also the perturbation method based on the two-spin–orbit-parameter model, where the contributions to spin-Hamiltonian parameters due to both the spin–orbit parameter of central dn ion and that of ligands via covalence effect are considered. The calculated results are compatible with those available in experiments. The defect structures of the trigonal (CrO6)9− octahedral centers are also evaluated from the calculations. It is found that the trigonal (MO6)9− octahedra change from the elongation in the host crystals to the compression in the impurity centers because of the large size and nature mismatch substitution in these Cr3+-doped ABO3 crystals. The results are discussed. [ABSTRACT FROM AUTHOR]

The high-order perturbation formulas founded on the two-mechanism model are applied in this paper to compute the spin-Hamiltonian parameters (g factors g//, g⊥ and zero-field splitting D) of the trigonal Mn4+ centers in Y2Ti2O7:Mn4+ crystal. In this model, besides the contributions from the traditional crystal-field (CF) mechanism (in the CF theory) related to CF excited states, those from the charge-transfer (CT) mechanism connected with CT excited states are contained. The calculated results are reasonably coincident with the observed values. The calculations show that the contributions of CT mechanism to spin-Hamiltonian parameters (in particular, the g factors) for (MnO6)8− clusters are large and cannot be neglected. The defect structure of trigonal (MnO6)8− clusters in Y2Ti2O7:Mn4+ crystals is also evaluated. The results are discussed. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Helicobacter pylori (HP) infection has been demonstrated to be a risk factor accounting for the initiation and development of gastric cancer (GC). The aim of the present study was to investigate the clinical significance of miR-490-3p in HP associated GC. PATIENTS AND METHODS: We measured the expression level of miR-490-3p in human GC tissues by quantitative Real-time PCR (qPCR). Then the association between miR-490-3p and clinical features of GC was further investigated. RESULTS: Our results showed that miR-490-3p levels exhibited a progressive downregulation in gastritis, intestinal metaplasia, HP negative GC and HP positive GC. In addition, miR-490-3p expression was significantly correlated with various clinicopathological parameters such as lymph node metastasis and clinical stage in HP-positive GC. Moreover, GC patients with lower miR-490-3p had a shorter 5 years overall/disease free survival time in the HP positive cohort. Finally, multivariate analysis showed that low miR-490-3p was an independent risk factor for HP associated GC. CONCLUSIONS: miR-490-3p is downregulated in HP-positive GC and associated with poor clinical outcome, indicating that miR-490-3p is a promising prognostic biomarker for HP positive GC. [ABSTRACT FROM AUTHOR]

The optical band positions and spin-Hamiltonian parameters (g factors gi and hyperfine structure constants Ai, where i = x; y; z) of the rhombic VO2+ complex in CsCl crystal are calculated together from two theoretical methods. One is the complete diagonalization (of energy matrix) method and another is the perturbation theory method. The calculated results from the two methods coincide and are in reasonable agreement with the experimental values. So, both methods are effective in the explanations of optical and electron paramagnetic resonance (EPR) data for d¹ ions in crystals. The calculations also suggest that in d¹ rhombic octahedra the ground state is almost a pure ∣dxy∣ state. This point is different from that of conjugate d9 (e.g., Cu2+) ions in rhombic octahedra where the ground state should be an admixture of ground and first excited states. [ABSTRACT FROM AUTHOR]

The spin-Hamiltonian parameters (g factors, [image omitted], [image omitted], and hyperfine structure constants, [image omitted], [image omitted]) for Yb3+ at the 12-fold coordinated Sr2+ site of tetragonal SrTiO3 crystal at T ≈ 2 and 50 K were calculated using the completed diagonalization (of the energy matrix) method (CDM). Differing from the conventional CDM, the Hamiltonian concerning the energy matrix in this CDM contains the Zeeman and hyperfine interaction terms and so the spin-Hamiltonian parameters can be calculated directly from CDM. The crystal parameters used in the energy matrix are calculated from the superposition model, in which the tetragonal distortions and hence the order parameters φ at both temperatures are applied. From the calculations, the spin-Hamiltonian parameters at both temperatures are explained reasonably and the signs of hyperfine structure constants for the 171Yb3+ and 173Yb3+ isotopes in SrTiO3 are suggested. The results are discussed. [ABSTRACT FROM AUTHOR]

The EPR g factors, g// and g⊥, of tetragonally elongated and compressed CuIIN6 octahedral clusters (with the ground states |dx2 - y2〉 and |dz2〉, respectively) in [image omitted] (MI = K, Rb, Cs; MII = Ca, Sr, Ba, Pb) crystals were calculated using a two-mechanism model. In the model, the contributions to the g-shifts, Δgi (= gi - gs, where i = // or ⊥; gs ≈ 2.0023 is the free-ion g value), from both the crystal-field (CF) mechanism related to CF excited states and the charge-transfer (CT) mechanism related to CT excited states, which is neglected in the widely-used CF theory, were considered. For the CF mechanism, two theoretical methods, the perturbation theory method (PTM) and the complete diagonalization (of energy matrix) method (CDM), were applied. The CF parameters used were calculated from the superposition model, in which the structural data for CuIIN6 clusters in [image omitted] crystals were measured exactly by X-ray diffraction. The calculated g factors for both the tetragonally elongated and compressed CuIIN6 octahedra are in reasonable agreement with the experimental values. For the strongly covalent CuIIN6 clusters in crystals with different ground states, both the PTM and CDM can be applied to calculate the g-shifts, [image omitted], arising from the CF mechanism, but exact and reasonable calculations of g factors should take both CF and CT mechanisms into account. [ABSTRACT FROM AUTHOR]

The spin-Hamiltonian (SH) parameters (g factors g//, g⊥ and hyperfine structure constants 63A//, 63A⊥, 65A//, 65A⊥) for Cu2+ ions in the trigonally-distorted tetrahedral sites of ZnO and GaN crystals are calculated from a complete diagonalization (of energy matrix) method (CDM) based on a two spin-orbit parameter model for d9 ions in trigonal symmetry. In the method, the Zeeman and hyperfine interaction terms are added to the Hamiltonian in the conventional CDM. The calculated results are in good agreement with the experimental values. The calculated SH parameters are also compared with those using the traditional diagonalization method or perturbation method only within the 2T2 term. It appears that, for exact calculations of SH parameters of d9 ions in trigonal tetrahedral clusters in crystals, the present CDM is preferable to the traditional diagonalization method or perturbation method within the 2T2 term. The local structures of Cu2+ centers (which differ from the corresponding structure in the host crystal) in ZnO : Cu2+ and GaN : Cu2+ are obtained from the calculations. The results are discussed. [ABSTRACT FROM AUTHOR]

The spin-Hamiltonian (SH) parameters (g factors, g¶ and g⊥, and hyperfine structure constants, 171A¶, 171A⊥, 173A¶ and 173A⊥) for Yb3+ ions in trigonally-distorted octahedral sites of Na3Sc2V3O12 garnet were calculated from a complete diagonalization (of energy matrix) method (CDM) concerning 4f13 ions in trigonal symmetry. In the method, the Zeeman and hyperfine interaction terms are added to the Hamiltonian in the conventional CDM and the crystal-field parameters are estimated from the empirical superposition model. From the calculations, these SH parameters are explained reasonably. The defect structure of Yb3+ impurity centres in Na3Sc2V3O12 garnet and the signs of 171Ai (i = ¶ or ⊥) and 173Ai are also suggested. The intrinsic parameters in the superposition model obtained in the studied system show that [image omitted] > [image omitted] > [image omitted]. This point is consistent with the intrinsic parameters obtained for many rare earth ion systems and can be regarded as suitable. [ABSTRACT FROM AUTHOR]