The magnetic order associated with the degree of freedom of spin in two-dimensional (2D) materials is subjected to intense investigation because of its potential application in 2D spintronics and ...valley-related magnetic phenomena. We report here a bottom-up strategy using molecular beam epitaxy to grow and dope large-area (cm2) few-layer MoSe2 with Mn as a magnetic dopant. High-quality Mn-doped MoSe2 layers are obtained for Mn content of less than 5% (atomic). When increasing the Mn content above 5%, we observe a clear transition from layer-by-layer to cluster growth. Magnetic measurements, involving a transfer process of the cm2-large doped layers on 100-micron-thick silicon substrate, show plausible proof of high-temperature ferromagnetism of 1% and 10% Mn-doped MoSe2. Although we could not point to a correlation between magnetic and electrical properties, we demonstrate that the transfer process described in this report permits to achieve conventional electrical and magnetic measurements on the doped layers transferred on any substrate. Therefore, this study provides a promising route to characterize stable ferromagnetic 2D layers, which is broadening the current start-of-the-art of 2D materials-based applications.
This study evaluated (1) the effects of in vivo GnRH treatment on mRNA expression of TNF-α system (TNF-α, TNFR1 and TNFR2) in granulosa cells of bovine preovulatory follicles, (2) the in vitro ...influence of gonadotropins on mRNA expression of TNF-α system in cultured cumulus cells, (3) the protein expression of the TNF-α system in late antral follicles and, (4) the influence of TNF-α on cumulus cells expansion, ultrastructure and on expression of HAS2, CASP3 and CASP6 in follicular cells cultured for 24 h. An increased expression of TNF-α and TNFR1 was observed after 3, 6 and 12 h of GnRH treatment when compared to 0 and 24h. Higher TNFR2 mRNA levels were observed 3, 6 and 12 h after GnRH, when compared to 0 and 24 h. Proteins of TNF-α system were also expressed in late antral follicles. In vitro, TNF-α did not affect cumulus cells expansion, but reduced the HAS2, CASP3 and CASP6 mRNA levels in cumulus cells after 12 h. After 24 h of culture, TNF-α increased the mRNA levels for CASP6 in mural granulosa cells, while the TNF-α, TNFR1 and TNFR2 mRNA levels were increased in cumulus-oocyte complexes (COCs) cultured for 12 h with gonadotropins, but not after 24 h. Ultrastructural analysis confirmed the integrity of COCs cultured in presence of TNF-α. In conclusion, TNF-α system members are present in bovine antral follicles and expression of TNF-α is influenced by gonadotropins in vivo and in vitro. In vitro, TNF-α maintained cumulus cells ultrastructure during COC culture.
•The proteins by TNF-α and its receptors (TNFR1 and TNFR2), are present in antral follicles compartments.•GnRH treatment increases TNF-α mRNA level in granulosa cells of preovulatory follicles in vivo.•In vitro, expression of TNF-α mRNA in cumulus cells is also upregulated by gonadotropins.•TNF-α maintains ultrastructure and regulates gene expression during COC culture.
Investigation of the thickness dependence of the magnetic anisotropy in B2-type Co2TiSi films on GaAs(001), shows a pronounced perpendicular magnetic anisotropy at 10 K for thicknesses up to 13.5 nm. ...We have evidenced that the interfacial anisotropy induced by interface clusters has a strong influence on the perpendicular magnetic anisotropy of this hybrid structure, especially at temperatures lower than the blocking temperature of the clusters (28 K). However, as this influence can be ruled out at higher temperatures, the perpendicular magnetic anisotropy which is found to persist up to room-temperature can be ascribed to the magnetic properties of the Co2TiSi films. For thicknesses larger than 15.0 nm, we observe an alignment of the magnetic easy axis parallel to the sample surface, which is most likely due to the shape anisotropy and the film structure.
•TNF-α system members are expressed at different follicular stages in bovine ovaries.•TNF-α reduces follicular survival in cultured bovine ovarian tissue.•TNF-α increases the total number of ...apoptotic cells in cultured follicles.•Dexamethasone improves ultrastructure of bovine follicle cultured in vitro.
This study was conducted to detect the protein expression of TNF-α system members (TNF-α/TNFR1/TNFR2) in bovine ovarian follicles and to evaluate the effects of TNF-α or dexamethasone on the survival and growth of primordial follicles in vitro, as well as on gene expression in cultured ovarian tissue. It was hypothesized that TNF-α induces follicular atresia in ovarian tissues cultured in vitro, and that dexamethasone suppresses the production of endogenous TNF-α, which can improve follicle viability in vitro. Ovarian fragments were cultured for 6days in α-MEM+ supplemented with TNF-α (0, 1, 10, 100 or 200ng/ml) or dexamethasone (0, 1, 10, 100 or 200ng/ml). After culture, the expression of mRNAs for BCL-2, BAX, P53, TNF-α, and CASP3 and CASP6 were evaluated. Immunohistochemical results showed that the TNF-α system members, were detected in bovine preantral and antral follicles. After 6days, the TNF-α (10ng/ml) treatment reduced the percentage of normal preantral follicles and increased the number of TUNEL-positive cells in cultured tissue. Dexamethasone (10ng/ml) during 6days of culture did maintain the percentage of normal follicles and the ultrastructure of follicles, while the presence of TNF-α or dexamethasone did not influence primordial follicle activation. However, TNF-α or dexamethasone had no effect on the levels of mRNA for P53, BCL-2, BAX and CASP6, in cultured tissues, but the presence of dexamethasone reduced the levels of CASP3 compared to ovarian slices cultured in control medium (α-MEM+). In conclusion, proteins of the TNF-α system are expressed at different bovine follicle stages. The addition of TNF-α in culture reduces follicle survival and increases the number of apoptotic cells in ovarian tissue, while the presence of dexamethasone maintains follicle ultrastructure in cultured tissue.
Adenines mismatched with guanines or 7,8-dihydro-8-oxo-deoxyguanines that arise through DNA replication errors can be repaired by either base excision repair or mismatch repair. The human MutY ...homolog (hMYH), a DNA glycosylase, removes adenines from these mismatches. Human MutS homologs, hMSH2/hMSH6 (hMutSα), bind to the mismatches and initiate the repair on the daughter DNA strands. Human MYH is physically associated with hMSH2/hMSH6 via the hMSH6 subunit. The interaction of hMutSα and hMYH is not observed in several mismatch repair-defective cell lines. The hMutSα binding site is mapped to amino acid residues 232–254 of hMYH, a region conserved in the MutY family. Moreover, the binding and glycosylase activities of hMYH with an A/7,8-dihydro-8-oxo-deoxyguanine mismatch are enhanced by hMutSα. These results suggest that protein-protein interactions may be a means by which hMYH repair and mismatch repair cooperate in reducing replicative errors caused by oxidized bases.
We report on the Mn segregation and diffusion during the epitaxial overgrowth of Ge on Mn 5 Ge 3 /Ge(111)heterostructures. It is shown that the underneath Mn 5 Ge 3 layers remain stabilized at the ...interface with thesubstrate while a small amount of Mn can leave the layers and floats at the Ge growth front. Mn can then actas a surfactant during Ge growth along the (111) orientation. The Mn segregation length and also the state ofMn atoms incorporated in the Ge layers are found to depend on the growth temperature. At a growthtemperature of 250 °C, a segregation length of ~ 10 nm is observed and Mn atoms incorporated in the Gelayers are uniformly distributed. At 450 °C, segregated Mn atoms can react with Ge to form Mn 5 Ge 3 clustersinside the Ge overgrown layer. Such Mn 5 Ge 3 clusters display random orientations and induce modification ofthe magnetic anisotropy of the whole film.
Reflexion high-energy electron diffraction (RHEED), transmission electron microscopy (TEM) along with physical property measurement system (PPMS) were used to investigate the growth kinetics of ...Ge1−xMnx diluted magnetic semiconductors (DMS) grown on Ge(001) by means of molecular beam epitaxy (MBE). At a given intermediate growth temperature of 130 °C, we have identified the formation of successive heterogeneous phases when increasing the Mn concentration from 1 to 14 %: DMS phase containing nanosized Mn-rich clusters for x below 2%, DMS phase containing high Curie temperature (TC) nanocolumns for x ranging from 5 to 6 %, DMS phase in which GeMn nanocolumns and Mn5Ge3 clusters coexist and then finally DMS containing mainly Mn5Ge3 clusters at Mn concentration higher than 12%. Our results confirm that the low solubility of Mn in Ge is the main origin of the formation of heterogeneous phases and provide evidence that it is extremely difficult to form a homogenous GeMn DMS even for Mn concentrations being below 2%. We also demonstrate that high-TC nanocolumns and Mn5Ge3 clusters are competing processes and the process window corresponding to the stabilisation of high-TC nanocolumns remains extremely tight.
Abstract
Janus single-layer transition metal dichalcogenides, in which the two chalcogen layers have a different chemical nature, push chemical composition control beyond what is usually achievable ...with van der Waals heterostructures. Here, we report such a Janus compound, SPtSe, which is predicted to exhibit strong Rashba spin–orbit coupling. We synthetized it by conversion of a single-layer of PtSe
2
on Pt(111) via sulfurization under H
2
S atmosphere. Our in situ and operando structural analysis with grazing incidence synchrotron X-ray diffraction reveals the process by which the Janus alloy forms. The crystalline long-range order of the as-grown PtSe
2
monolayer is first lost due to thermal annealing. A subsequent recrystallization in presence of a source of sulfur yields a highly ordered SPtSe alloy, which is isostructural to the pristine PtSe
2
. The chemical composition is resolved, layer-by-layer, using angle-resolved X-ray photoelectron spectroscopy, demonstrating that Se-by-S substitution occurs selectively in the topmost chalcogen layer.
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