12 research outputs found

    Functionalized magnetic composite nano/ microfibres with highly oriented van der Waals CrI3 inclusions by electrospinning

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    This study reports on the synthesis of highly oriented chromium triiodide (CrI3) magnetic inclusions inside nano/microfibres with a polyethylene oxide matrix, prepared by the electrospinning technique. The structural, microstructural and spectroscopic analysis shows uniformly dispersed CrI3 nanosized inclusions inside the fibres, presenting a C2/m monoclinic structure at room temperature, where their c-axis is perpendicular to the fibre mat plane and the ab layers are in-plane. Analysis of the magnetic properties show that the samples have a ferromagnetic-paramagnetic phase transition at ∼55-56 K, lower than that of bulk CrI3. Noticeably, a field-driven metamagnetic transition is observed below ∼45 K, from M versus H curves, when the applied magnetic field is perpendicular to the fibre mat plane, while it is strongly reduced when the field is in-plane. This anisotropic behaviour is attributed to the field-induced changes from antiferromagnetic to ferromagnetic interlayer magnetic moment alignment along the CrI3 c-axis stacked layers. These CrI3 electrospun fibres then show an efficient cost-effective route to synthesize magnetic composite fibres with highly oriented van der Walls inclusions, for spintronic applications, taking advantage of their anisotropic 2D layered materials properties.We are grateful to the Fundacao Para a Ciencia e a Tecnologia (FCT) for the financial support through the Physics Centers of the Universities of Minho and Porto (Ref. UIDB/04650/2020) and projects UTAPEXPL/NTec/0046/2017, NORTE-01-0145-FEDER-028538 and PTDC/FIS-MAC/29454/2017. J H Belo thanks FCT for the Grant SFRH/BD/88440/2012, the project PTDC/FIS-MAC/31302/2017 and his contract DL57/2016 reference SFRH-BPD-87430/2012. J P Araujo and J H Belo thank the funding from the project, with reference POCI-01-0145-FEDER-032527. V B Isfahani acknowledges a Post-Doc grant from the project NORTE-01-0145-FEDER-028538. L Boddapati acknowledges the Nano TRAIN for Growth II program by the European Commission through the Horizon 2020 Marie Sklodowska-Curie COFUND Programme and support provided by the International Iberian Nanotechnology Laboratory. We are gratefull to Professor Michael Belsley, of the Physics Department at Minho University, for the fruitfull discussions on the manuscript

    EFFECT OFVARIATIONSIN ABCC2, CYP2C9, CYP2C19 & SCN2A GENESON TREATMENT RESPONSETO ANTICONVULSANTS- A SYSTEMATIC REVIEWAND META-ANALYSIS OF GENETIC ASSOCIATION STUDIES

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    Objective: This study was aimed to determine the effect of genetic polymorphisms (non-synonymous, missense, and copy number variations) in ABCC2, CYP2C9, CYP2C19&SCN2A genes on treatment response to anticonvulsants. Methods: The search was carried out in PubMed, Scopus, Cochrane Central Register of Controlled Trials, Embase, LILACS, Google Scholar, MEDLINE, ScienceDirect, Web of Science, and the DOAJ database. Hardy Weinberg Equilibrium (HWE), New-Castle Ottawa scale value, Cochrane Review Manager 5.0 (&R 4.0.3,) and Rayyan QCRI are used for assessing data synthesis, risk of bias, heterogeneity assessment using I[2]statistics and calculating Inter-rater agreement respectively. Publication bias assessment was performed using Eggers test and the Funnel plot. For statistical analysis, random effects modeling was used to explain the association between genetic variations in ABCC2, CYP2C9, CYP2C19 & SCN2A genes related to drug resistance or treatment failure. Results: This meta-analysis includes a total of 29 studies. We found a greater risk of AED resistance in ABCC2rs2273697 genetic variations (OR=1.51 [ 0.93-2.47], p value=0.03 at 95% CI), ABCC2 rs3740066 genetic variation has a greater possibility of AED resistance was seen in pooled population (OR= 0.85 [0.12-5.85], p-value<0.01 at 95% CI), risk of drug resistance was increased by ABCC2 rs717620 polymorphism. (OR =2.13, [1.02-4.44], p-value<0.01 at 95% CI), CYP2C9 rs1799853 polymorphism had a significant increase in AED resistance (OR =1.27, [0.49-3.32] p-value<0.01 at 95% CI), CYP2C9 rs1057910 polymorphism. (OR= 0.74, [0.32-1.70] p-value 0.01 at 95% CI), CYP2C19 rs4244285 polymorphism. (OR= 0.68, [0.29-1.62], p value=0.02 at 95% CI), SCN2A rs2304016 polymorphism. (OR= 1.20, [0.48-3.05], p value<0.01 at 95% CI), SCN2Ars17183814 polymorphism. (OR =1.51, [1.12-2.03], p value=0.30 at 95% CI). Conclusions:Gene polymorphisms play a key role in epilepsy development and therapeutic efficacy, and could have greater impact treatment outcomes

    Characterization of structure and magnetism in Zn1-x(Co-x/Mn-x)O epitaxial thin films as a function of composition

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    We have investigated the non-equilibrium solubility of Mn and Co in Zn1-xTMxO (x = 5-30 at.% TM = Co, Mn) single crystal thin film and the role of Co/Mn concentration on the structural and magnetic properties. The films have been grown by pulsed laser deposition and the structural and magnetic characterization has been performed using high resolution transmission electron microscopy and superconducting quantum interference device respectively. Cobalt shows high solubility in single crystalline ZnO films with no tendency to form incoherent secondary precipitates up to 30 at.%. Whereas for Mn:ZnO, secondary precipitate started forming from Mn concentration of 25 at.% and above. HREELS of both Co and Mn L-2,L-3 absorption edges shows that the Co and Mn atoms have substituted the Zn positions in the lattice. ZnO doped with 30 at.% Mn forms single crystalline spinel Mn3O4 phase on the sapphire substrate in the form of an interlayer which is responsible for aligning subsequent Mn:ZnO film with respect to sapphire as [11-20]Al2O3 vertical bar vertical bar [11-20] ZnO compared to the usual [11-20]Al2-O3 vertical bar vertical bar[01-10] ZnO orientation. Saturation magnetization remained almost the same similar to 10(20)-10(21) mu(B)/cm(3)) for Co:ZnO but a composition dependent coercivity has been observed. For Zn0.75CO0.25O film, the coercivity is similar to 922 (769) Oe corresponding to applied field perpendicular (parallel) to the c axis, which is the highest value reported in this system. For Mn:ZnO ferromagnetism disappears beyond Mn concentrations of 15 at.%. (C) 2013 Elsevier Ltd. All rights reserved

    Interferroelectric transition as another manifestation of intrinsic size effect in ferroelectrics

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    In general, crystallite size reduction is known to suppress the ferroic order (polarization or magnetization) in ferroelectric and magnetic systems. Using free particles of a giant tetragonality (c/a-1 = 0.18) ferroelectric alloy BiFeO3-PbTiO3 as the model system, here we show that the intrinsic size effect in ferroelectrics can as well manifest in terms of switching the ground state from one ferroelectric phase (tetragonal with polarization along 001]) to another ferroelectric phase (rhombohedral with polarization along 111]). In this particular case, because of the strong coupling of the magnetic and structural degrees of freedom, a magnetic order also sets in below the critical size, making it a size induced magnetoferroelectric transformation. The driving force for this unusual transformation is argued to be the large depolarizing and domain wall energies in the tetragonal phase

    Metastable monoclinic and orthorhombic phases and electric field induced irreversible phase transformation at room temperature in the lead-free classical ferroelectric BaTiO3

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    For decades it has been a well-known fact that among the few ferroelectric compounds in the perovskite family, namely, BaTiO3, KNbO3, PbTiO3, and Na1/2Bi1/2TiO3, the dielectric and piezoelectric properties of BaTiO3 are considerably higher than the others in polycrystalline form at room temperature. Further, similar to ferroelectric alloys exhibiting morphotropic phase boundary, single crystals of BaTiO3 exhibit anomalously large piezoelectric response when poled away from the direction of spontaneous polarization at room temperature. These anomalous features in BaTiO3 remained unexplained so far from the structural standpoint. In this work, we have used high-resolution synchrotron x-ray powder diffraction, atomic resolution aberration-corrected transmission electron microscopy, in conjunction with a powder poling technique, to reveal that at 300 K (i) the equilibrium state of BaTiO3 is characterized by coexistence of metastable monoclinic Pm and orthorhombic (Amm2) phases along with the tetragonal phase, and (ii) strong electric field switches the polarization direction from the 001] direction towards the 101] direction. These results suggest that BaTiO3 at room temperature is within an instability regime, and that this instability is the fundamental factor responsible for the anomalous dielectric and piezoelectric properties of BaTiO3 as compared to the other homologous ferroelectric perovskite compounds at room temperature. Pure BaTiO3 at room temperature is therefore more akin to lead-based ferroelectric alloys close to the morphotropic phase boundary where polarization rotation and field induced ferroelectric-ferroelectric phase transformations play a fundamental role in influencing the dielectric and piezoelectric behavior

    Epitaxial Co metal thin film grown by pulsed laser deposition using oxide target

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    We report here the growth of epitaxial Co metal thin film on c-plane sapphire by pulsed laser deposition (RD) using Co:ZnO target utilizing the composition inhomogeneity of the corresponding plasma. Two distinct plasma composition regions have been observed using heavily alloyed Co0.6Zn0.4O target. The central and intense region of the plasma grows Co:ZnO film; the extreme tail grows only Co metal with no trace of either ZnO or Co oxide In between the two extremes, mixed phases (Co +Co-oxides +Co:ZnO) were observed. The Co metal thin film grown in this way shows room temperature ferromagnetism with large in plane magnetization similar to 1288 emu cm(-3) and a coerciviLy of similar to 230 Oe with applied field parallel to the film-substrate interface. Carrier density of the film is similar to 10(22) cm(-3). The film is epiLaxial single phase Co metal which is confirmed by both X-ray diffraction and transmission electron microscopy characierizaLions. Planar Hall Effect (PHE) and Magneto Optic Kerr Effect (MOKE) measurements confirm that the film possesses similar attributes of Co metal. The result shows that the epiLaxial Co metal thin film can be grown from its oxides in the PLD. (C) 2014 Elsevier B.V. All rights reserved
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