The etiology of the Graves’ disease (GD) is largely unknown. However, genetic factors are believed to play a major role. A recent genome-wide association study in a Han Chinese sample collection revealed two new Graves’ disease (GD) risk loci within chromosome band 4p14 and 6q27. In this study, we aimed to investigate these associations with Weifang Han Chinese population of Shandong province and perform a meta-analysis of associations with GD.A case–control study was conducted to investigate association of variation within 4p14 and 6q27 to GD susceptibility in Weifang Han Chinese population of Shandong province. SNP rs6832151 at chromosome 4p14 and SNP rs9355610 at chromosome 6q27 was selected for genotyping in 2,382 GD patients and 3,092 unrelated controls. SNP genotyping was performed using TaqMan Real-time PCR technique assays on ABI7900 platform. A meta-analysis was performed with the data obtained in the current sample-set and those available from prior studies.PAllelic = 1.48 × 10−9) and rs9355610 located in 6q27  was associated with GD susceptibility. By model of inheritance analysis, we found the recessive model should be preferred (PRecessive = 2.75 × 10−11) for rs6832151. The dominant model should be preferred (PDominant = 7.15 × 10−3) for rs9355610, whereas analysis of recessive model showed no significant association (PRecessive = 0.13). Meta-analysis with the data of 10,781 cases and 16,304 controls obtained from present sample-set and those available from prior studies confirmed association of rs6832151 at 4p14 with GD susceptibility using a fixed model . Meta-analysis with the data of 11,306 cases and 12,756 controls confirmed association of rs9355610 at 6q27 with GD susceptibility using a fixed model .Association analysis revealed both rs6832151 located in 4p14 (odds ratio (OR) = 1.27, Our findings showed that chromosome 4p14 and 6q27 variants were associated with Graves’ disease in Weifang Han Chinese population of Shandong province. Graves’ disease (GD) is a common organ-specific autoimmune disorder characterized by autoantibodies activating the thyrotropin receptor (TSHR) causing a hyperfunction of thyroid gland. Lymphocytic infiltration was found in the thyroid gland of patients with accompanying evidence of both humoral and cellular immune system activation. GD is clinically characterized by hyperthyroidism, diffuse goiter and the presence of thyrotropin receptor (TSHR) antibodies. Stimulatory TSHR auto-antibodies are directly responsible for the syndrome of hyperthyroidism in the development of GD.HLA), cytotoxic T-lymphocyte associated antigen-4 (CTLA-4), TSHR and Fc receptor like 3 (FcRL3) [Both genetic and environmental factors were thought to be involved in the pathogenesis of GD. Previous studies suggested that genetic background had a predominant impact on individual susceptibility to GD and contributed up to about 79% of total disease risk . GD, as  (FcRL3) –5.CHRNA9 and RHOH, and a newly cloned gene, namely GDCG4p14. Rs9355610 is located in a region of linkage disequilibrium (LD) at 6q27 containing three genes, namely RNASET2, FGFR1OP and CCR6. Rs9355610 lies 13-kb 5’ upstream RNASET2, which is the closest gene to rs9355610. The chromosome locations of these genes made them as the positional candidate genes for GD susceptibility.A recent genome-wide association study (GWAS) in Chinese Han population firstly identified two novel GD susceptibility loci at chromosomal bands 4p14 rs6832151) and 6q27 (rs9355610) [832151 anThe associations of variation at 4p14 and 6q27 were then investigated several following independent studies. Association of rs6832151 within 4p14 was replicated in Polish population, and rs9355610 within 6q27 was associated with GD susceptibility only following a recessive model in Polish population . These iBecause of possible genetic heterogeneity between Han Chinese of different regions, we investigated the associations of the above two SNPs (rs6832151 at 4p14 and rs9355610 at 6q27) with GD risk in Weifang Han population. To further clarify the inconclusive association between two SNPs and GD, we conducted a meta-analysis with available data sets from prior studies together with our current data.The study population consisted of 2,382 Chinese Han GD patients and 3,092 unrelated, age and sex matched healthy controls. All patients with GD were recruited from Department of Endocrinology, Weifang People’s Hospital of Shandong province in China. The healthy controls were recruited from the Health Check-Up Center of the hospital, which were all of self-reported Chinese Han ethnicity from Weifang City of Shandong province. The study was approved by the ethics committee of Weifang People’s Hospital and written informed consent was taken from all participants.Patients were diagnosed with GD based on the documented clinical symptoms and laboratory tests ) as described previously . The thyPeripheral blood of 2 ml was collected from each participant. Genomic DNA was extracted from human peripheral blood cells using the FlexiGene DNA Kit 250  according to the manufactures’ guidelines. Two selected SNPs (rs6832151 and rs9355610) were genotyped using TaqMan assays on ABI7900 platform. TaqMan SNPs genotype assays were provided by Applied Biosystems . SNP genotyping was performed on ABI7900 Sequence Detection System  according to the manufacturer’s instructions. The data completion rate of rs6832151 and rs9355610 was 99.6% and 99.4% respectively.χ2-test between the cases and the controls. A two-tailed P-value < 0.05 was considered statistically significant. The risk allele of each SNP was revealed by odds ratios (ORs).Statistical analysis was performed using Plink. The genotype distribution of each SNP was tested for Hardy-Weinberg equilibrium in both case and control population. Both allele and genotype frequencies were assessed by We assessed the power of the data using the CaTS . Assuminhttp://www.pubmed.gov) up to April 2016. We searched for all publications relating to association studies and checked the reference lists of identified studies for additional studies. Association studies of chromosome 4p14 with GD were found by entering the search phrase: ‘GD’ or ‘Graves’ disease’ and ‘4p14’ and ‘rs6832151’ and ‘SNP’. Similarly, association studies of chromosome 6q27 with GD were found using the search phrase: ‘GD’ or ‘Graves’ disease’ and ‘6q27’ and ‘rs9355610’ and ‘SNP’. The analyzed data covered all English and Chinese publications from September 2011 to April 2016. Six studies including the present study investigated the association of rs6832151 at 4p14 with GD, and totally 10,781 cases and 16,304 controls were studied. Seven studies including the present study investigated the association of rs9355610 at 6q27 with GD, and totally 11,306 cases and 12,756 controls were studied.To identify data to be included in the meta-analysis, a literature search was performed in PubMed . All P-values are two-sided.We conducted meta-analysis using Review Manager software (version 4.2). The Isistency  and the tatistic  was usedes > 50% . StatistTo investigate whether rs6832151and rs9355610 contributed to GD susceptibility, we recruited a case–control sample collection. Demographic information was shown in Table P > 0.05). The genotypic frequencies of the two SNPs were showed in Table In both of the patients and control samples, the distribution of genotype frequencies of the two SNPs conformed to Hardy-Weinberg equilibrium . The frequency of rs6832151 G allele was 0.41in cases and 0.35 in controls. The frequencies of rs6832151 genotypes in GD patients  differed significantly from those in the controls  (PGenotypic = 5.65 × 10−11). Analysis of model of inheritance revealed the risk allele G of rs6832151 was associated with GD susceptibility following both the recessive model (PRecessive = 2.75 × 10−11) and the dominant model (PDominant = 1.78 × 10−4). The recessive model should be preferred.The minor allele G of rs6832151 was associated with GD risk . The frequency of rs9355610 risk allele G was 0.51 in cases and 0.49 in controls. The genotype frequencies of rs9355610 in GD cases  differed significantly from those in the controls  (PGenotypic = 2.12 × 10−2). Analysis of model of inheritance showed the G allele of rs9355610 had a dominant effect on GD in the current population (PDominant = 7.15 × 10−3), whereas analysis of recessive model showed no significant association (PRecessive = 0.13).The major allele G of rs9355610 within 6q27 was associated with GD risk . The frequency of the risk allele G was 0.41 and 0.35 in the current Chinese cases and controls. The frequency of the risk allele G was 0.292 and 0.252 in the Japanese cohort with 286 cases and 222 controls. The trend of the ORs for each of the Chinese, Japanese and Polish cohorts was similar and there was no significant heterogeneity across the seven data-sets  that the rs6832151 polymorphism at 4p14 played in GD susceptibility. Consistently positive associations were found in the six data-sets. However, no association was found Japanese population when comparing the allelic effects . The frequency of rs9355610 risk allele G was 0.51 and 0.49 in the current Chinese cases and controls. The frequency of the risk allele G was 0.71 and 0.68 in the Polish Caucasian cases and controls. The trend of the ORs for each of the Chinese, Japanese and Polish cohorts was similar and there is no significant heterogeneity across the seven data-sets (Fig. We also found rs9355610 in 6q27 was associated with GD risk in Weifang Han Chinese Han population. Our meta-analysis summarizes the evidence to date regarding the association between rs9355610 and GD, representing a pooled total of 11,306 cases and 12,756 controls from three countries across two continents. The results of meta-analysis indicated an association of rs9355610 with GD susceptibility (OR = 1.18; 95% CI: 1.13 to 1.22; Fig. ets Fig. . It shouRNASET2 and the 5’ upstream region. The risk allele of rs9355610 was significantly with the diminished level of RNASET2 expression in T cells from healthy subjects [RNASET2, encoding ribonuclease T2, is the only RNase T2 family member in humans. Ribonucleases were suggested to have a broad range of biological functions including scavenging of nucleic acids, degradation of self-RNA, serving as cytotoxins and modulating host immune responses [+ T cells [RNASET2 in immune response made it a potential GD susceptibility gene and further functional studies were needed to clarify whether and how it played a role in GD pathogenesis. It should be noted that the association of chromosome band 6q27 were also found with susceptibility of other autoimmune diseases such as Crohn’s disease, rheumatoid arthritis, type 1 diabetes mellitus and vitiligo [LD pattern in Chinese population showed that rs9355610 was located in an LD block covering 5’ exons of esponses . RNase T T cells , 30. TheWe confirmed the association between GD susceptibility and rs6832151 at 4p14 as well as rs9355610 at 6q27. These associations indicated that variation in 4p14 and 6q27 might be involved in GD pathogenesis in Weifang Han Chinese population of Shandong province. Although our association study and meta-analysis replicated the associations of 4p14 and 6q27 variation with Graves’ disease with compelling evidence, future studies in Caucasian and other population were needed to further confirm these associations with GD susceptibility. Further molecular experiments should be put forth to clarify how these risk variants accounted for the susceptibility of GD.


Here, we report a novel perovskite oxide that belongs to the BiFeO3–BiMnO3–PbTiO3 ternary system, chemically designed to present such multiferroic phase boundary with enhanced ferroelectricity and canted ferromagnetism, which shows distinctive room-temperature magnetoelectric responses.There is a growing activity in the search of novel single-phase multiferroics that could finally provide distinctive magnetoelectric responses at room temperature, for they would enable a range of potentially disruptive technologies, making use of the ability of controlling polarization with a magnetic field or magnetism with an electric one . A very promising novel material concept could be to make use of phase-change phenomena at structural instabilities of a multiferroic state. Indeed, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of the perovskite BiFeO Structural change at multiferroic phase boundary is anticipated to have an associated large magnetoelectric response, which yet awaits to be evidenced. Here, Fernández-Posada et al. report electric field-induced phase change for a BiFeO3–BiMnO3–PbTiO3 solid solution with distinctive magnetic signature. Magnetoelectric multiferroics are compounds that show coexistence of electrical and magnetic orders, and a range of coupling phenomena between polarization and magnetization. They are highly topical materials from both the fundamental and applied points of view2O5, in which a small (below 1 μC cm−2) spontaneous polarization develops as a byproduct of a magnetic transition, often involving complex incommensurate antiferromagnetic states that are intrinsically associated with the existence of spin frustration due to competing interactions. Though large magnetoelectric responses have been reported as a result of the inherent relationship between the electrical and magnetic orders, by tuning the ferroelectric state with a magnetic field, this is usually only possible at very-low temperatures, and the mechanism does not allow for a comparable electrical control of magnetism56Among the various families of multiferroic compounds under study, magnetic (or spin-induced) ferroelectrics have concentrated a lot of attention. They are improper ferroelectrics like orthorhombic TbMn3 perovskite oxides in which multiferroicity is chemically engineered by placing ferroelectrically and magnetically active cations in the A- and B-site, respectively. Most promising systems are BiMO3 compounds, such as BiCoO3 and BiFeO3, that are both ferroelectric and antiferromagnetic at room temperature, and for which magnetoelectric coupling has been demonstrated83 stands out as the most topical multiferroic. This oxide has a rhombohedral distorted structure (R3c space group) that results in spontaneous polarization exceeding 100 μC cm−2, and high transition temperature of ∼1,100 K. Besides, it is a G-type antiferromagnet with an ordering temperature of ∼640 K. Crystal magnetoelectric coupling exists and gives place to a long-range incommensurate cycloidal superstructure with the spins rotating within a plane containing the electrical polarization11MS ≈0.6 emu g−1 for 200 nm thick films)MS ≈1.2 emu g−1 for Bi0.7Ba0.3FeO3 ceramic materials)A second set of materials under extensive research are ABO3, and the ferroelectric/ferroelastic and antiferromagnetic domain configurations are coupled, which enables the electrical drive of magnetic domains15171920Spontaneous polarization and magnetization easy axis are orthogonal in BiFeO3 is still at the cutting edge of research230.53Ti0.47)O3–Pb(Fe1/2Ta1/2)O3 at room temperatureAlthough BiFeO3–BiCoO3 perovskite binary systemR3c and tetragonal P4mm symmetries. Mechanism would be the discrete rotation of the magnetization easy axis following that of the spontaneous polarization under the electric field, linked to the electric field-induced transformation from one multiferroic polymorph to the other. Large phase-change electromechanical responses have been widely reported for perovskite systems with ferroelectric MPBs, like Pb(Zn1/3Nb2/3)O3–PbTiO3Perovskite solid solutions are also the basis of a different, not well explored approach. A strong phase-change magnetoelectric response has been anticipated by a first-principles investigation of phases in the BiFeOCm phase between the rhombohedral and tetragonal polymorphs in the BiFeO3–BiCoO3 system, and polarization rotation with temperature and composition within this phase3, which is directly associated with their very high piezoelectric response30A recent experimental study reported the existence of a monoclinic 3–BiMnO3–PbTiO3 ternary system. BiFeO3–PbTiO3 has been extensively studied as an alternative to BiFeO3–BiCoO3, which also shows a multiferroic phase boundary33343-rich phase383–BiMnO3–PbTiO3 ternary system0.68Pb0.32Fe0.655Mn0.025Ti0.32O3 (0.655BiFeO3–0.025BiMnO3–0.32PbTiO3) lies within this line, and shows both enhanced ferroelectricity and weak ferromagnetism for distinctive room-temperature magnetoelectric responses.Here, we report a novel perovskite oxide chemically designed to present a multiferroic MPB that does show distinctive room-temperature magnetoelectric responses by means of these two mechanisms: field-driven phase changes and transverse lattice softening. The new material is a solid solution belonging to the BiFeOA first critical issue was determining the actual phase coexistence at the MPB, namely discriminating whether the polymorphic phase in coexistence with the tetragonal component was rhombohedral or monoclinic, for lattice transverse softening is characteristic of the latter symmetry. This was done by using high-resolution X-ray diffraction (XRD). Chemically homogenous nanocrystalline powders obtained by mechanosynthesis, thermally treated at 950 °C for 12 h to increase crystallinity were characterized. A typical XRD pattern is shown in P4mm space group of PbTiO3 along with the rhombohedral R3c of BiFeO3 or monoclinic Cc symmetry (among others) were selected as structural models. The best fits between observed and calculated profiles obtained by the Rietveld refinements were compared with choose among the models. The initial lattice parameters and atom coordinates for the phases involved in the refinements were taken from previous reports on the BiFeO3–PbTiO3 binary system with composition at the MPB34c/a ∼1.18, which is considerably higher than that of PbTiO3.The diffraction profile was then analyzed by the Rietveld method using JANA packageR3c and Cc phases, using both mixture models involving coexistence with P4mm polymorph, are given in A major problem in the application of the Rietveld method to this system arises from the fits of the peaks at high angles, for which the complexity of the profile resulting from the polymorphic phase coexistence is a handicap. This is further complicated by the crystal stresses present due to the large difference in transition strain between the two coexisting polymorphs . This requires the implementation of anisotropic strain broadening models, such as that proposed by StephensRwp, Rexp and the goodness-of-fit indicator, are better for the model involving the monoclinic Cc space group. The best agreement for the latter phase is evident when one specifically analyses the refined profiles across the (200)p and (103)p reflections (referring to pseudocubic indices), shown in Cc and R3c symmetries, respectively. It is clear that the fit using R3c symmetry is not satisfactory, for example, the anomalous peak broadening of the (200)p reflection is not consistent with its singlet nature (and neither it is that of the (103)p considering it as a doublet), as expected for the R3c space group.It can be seen that the statistical parameters obtained, factors Cc polymorphic phase, the study was also carried out in another composition at the pseudo-rhombohedral side of the MPB, right next to that under study, but for which the tetragonal phase is not present . This composition is Bi0.75Pb0.25Fe0.7Mn0.05Ti0.25O3, for which only one polymorph can be observed in the XRD pattern, as shown in R3c and Cc, among others. The refined structural and statistical parameters are summarized in Cc, in particular RBragg.To confirm the actual existence of a monoclinic 3- and BiMnO3-based materials. Specifically, incipient perovskite decomposition during sintering can result in increasing levels of A-site and oxygen vacancies within the structure, and also of Fe and Mn mixed-valence states. Actually, this is a characteristic of these materials that always show non-negligible electron hopping-type conductivity associated with the presence of such defects, even though the microstructural characterization did not show any evidence of phase decomposition or grain boundary minor secondary phases in the ceramics.Fully dense materials with tailored microstructures and no traces of chemical inhomogeneities (checked by scanning electron microscopy and energy dispersive XRD) were processed by hot-pressing at moderate temperatures of the nanocrystalline powder obtained by mechanosynthesis. This is a requirement for a sound ferroelectric characterization, and also for applicability, which is not easily achieved in the case of low-tolerance factor perovskites, such as BiFeO0.68Pb0.32Fe0.655Mn0.025Ti0.32O3 Pr≈62 μC cm−2 and Ec≈4.7 kV mm−1. Loops for these materials could only be obtained after quenching from temperatures above the ferroelectric transition. This is an effective means of releasing the ferroelectric domain walls, initially clamped by oriented FeFe′-VO·· dipolar defects−1.A low-temperature ferroelectric state exists then for this material, as confirmed by P-E hysteresis loop measurements. Typical ferroelectric hysteresis and current density curves after compensation are shown in 0.68Pb0.32Fe0.655Mn0.025Ti0.32O3 not only showed enhanced ferroelectricity as compared with the binary system, but also enhanced spin-canted ferromagnetism. Magnetization was measured during conventional zero-field-cooling (ZFC)/field-cooling (FC) cycles under a dc magnetic field of 500 Oe. The temperature dependence of the molar magnetic susceptibility (M/H ratio) is shown in TN) above 400 K has been reported for compositions at the MPB of the BiFeO3–PbTiO3 binary system (c.a. 480 K)Bi3–PbTiO3 binary system, and associated with a spin-reorientation (SRO) phenomenon within the antiferromagnetic state of the monoclinic Cc phase3–0.3PbTiO3, and shifts towards lower temperatures upon addition of BiMnO3, along the line of MPBs in the ternary system−1, as shown in 3-based compositions like Bi0.7Ba0.3FeO33 along the line of MPBs  than the unpoled one, as shown in The ZFC/FC magnetization curves at 500 Oe for the same ceramic sample before and after the poling process are shown in α31 of ∼0.5 mV cm−1 Oe−1 was calculated after subtracting the background from the voltage amplitude at maximum dc field. It is worth remarking that this response must originate only from the monoclinic component, decreased in the poled state, for the tetragonal phase is in the paramagnetic state at room temperature.Also, the linear magnetoelectric response at room temperature was studied for the poled ceramic material as a function of magnetization. This was carried out by measuring the magnetoelectric voltage developed under the application of an alternate low-magnetic field, while the samples were subjected to static, increasingly high-magnetization fields. A longitudinal-transverse configuration; polarization perpendicular to magnetic fields, was selected. The results are shown in Cc polymorphic phase. Indeed, a controversy persists regarding the presence of this Cc polymorph at the MPB of the binary system. The crystal structures reported for BiFeO3–PbTiO3 by different groups differ and seem to depend on the synthesis/processing conditions and also on the thermal history3–0.3PbTiO3 has been claimed to be a mixture of tetragonal P4mm and either rhombohedral R3c  of a poled ceramic, associated with the expected, yet slow partial phase-change relaxation after removing the electric field.This electric field-induced phase-change takes place in a system with magnetic properties, specifically between a monoclinic phase with spin-canted antiferromagnetic ordering, and a tetragonal phase with 3+ spins in the perovskite unit cell and the superimposed spin-canting originating the ferromagnetic moment is shown in the inset of 3, and that is known to be intrinsically linked with the oxygen octahedral tilting11y,Fxz) magnetic structure was proposed above the SROXZ,FY) structure proposed below the SRO, for the former law is not fulfilled. Though the calculation of the actual octahedral rotation axis, which requires the accurate determination of the antiferrodistortive motions, is beyond the scope of this article, this axis must of the [uuv] type , and also to those obtained from first-principlesThe voltage magnetoelectric coefficient 3 epitaxial films under high compressive stress, in which a multiferroic MPB is strain engineeredCc) to tetragonal phase transformation has been demonstrated with a distinctive effect on magnetism3 epitaxial films by applying a moderate (below the coercive one) opposite electric field3, associated with a field-induced orthorhombic Pnma to rhombohedral R3c transitionAlthough further research is necessary to fully explore the potential of this approach, we believe that results here presented demonstrate that both linear magnetoelectric effect and large phase-change magnetoelectric response can be obtained at multiferroic phase boundaries. The novel perovskite oxide here reported, chemically designed to show this type of multiferroic instability and enhanced canted ferromagnetism, shows the targeted phase-change phenomena, and also linear magnetoelectric effect, all at room temperature. This phenomenology is analogous to that previously described for BiFeOMechanosynthesis was used to obtain chemically homogenous nanocrystalline powders of the novel perovskite phase. Details of the procedure and of the mechanisms taking place during the mechanical treatments can be found elsewhere36Kα radiation). Electrical properties were measured on ceramic discs, on which Au electrodes were painted and annealed at 750 °C for 1 h. The temperature dependence of the dielectric permittivity was dynamically measured under heating/cooling cycles at 1.5 °C min−1, with a HP4284A precision LCR Meter in the frequency range 20 Hz–1 MHz. Additional impedance spectroscopy was carried out in static conditions at temperature steps of 20 °C in the same frequency range. Ferroelectric hysteresis loops were obtained by current integration. High-voltage sine waves (0.1 Hz) were applied by the combination of a synthesizer/function generator (HP3325B) and a high-voltage amplifier (Trek Model 10/40A), while charge was measured with a homebuilt charge to voltage converter. Loops are presented after subtracting linear polarization and conduction contributions to the current curves, assuming a resistance and a capacitance in parallel.X-ray diffraction patterns were collected on a two-axis diffractometer with a Rigaku RA-HF18 rotating anode generator (Cu Magnetic properties were characterized with a Quantum Design MPMS-XL5 SQUID magnetometer. The samples were cooled down to 2 K under zero field and then a magnetic field of 500 Oe was applied and maintained during a following heating (ZFC) and cooling (FC) cycle. Isothermal magnetization measurements M(H) between −50 kOe and +50 kOe were recorded at 300 K. The magnetoelectric response was measured using an experimental set-up made of a combination of two Helmholtz coils: a high power coil and a high frequency one, designed to independently provide a static increasingly high magnetic field up to 1 kOe (magnetization field), and an alternate magnetic field of 10 Oe at 10 kHz (the stimulus), respectively (Serviciencia S.L.). The out-put voltages developed as a response of the alternate magnetic field were monitored with a lock-in amplifier.The authors declare that all data supporting the findings of this study are included within the manuscript and its  files anHow to cite this article: Fernández-Posada, C.-M. et al. A novel perovskite oxide chemically designed to show multiferroic phase boundary with room-temperature magnetoelectricity. Nat. Commun. 7:12772 doi: 10.1038/ncomms12772 (2016).Supplementary Figures 1-6, Supplementary Tables 1-3, Supplementary Notes 1-4 and Supplementary References


Transition metal oxides show great promise as Earth-abundant catalysts for the oxygen evolution reaction in electrochemical water splitting. However, progress in the development of highly active oxide nanostructures is hampered by a lack of knowledge of the location and nature of the active sites. Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy and computational modelling, how hydroxyls form from water dissociation at under coordinated cobalt edge sites of cobalt oxide nanoislands. Surprisingly, we find that an additional water molecule acts to promote all the elementary steps of the dissociation process and subsequent hydrogen migration, revealing the important assisting role of a water molecule in its own dissociation process on a metal oxide. Inspired by the experimental findings, we theoretically model the oxygen evolution reaction activity of cobalt oxide nanoislands and show that the nanoparticle metal edges also display favourable adsorption energetics for water oxidation under electrochemical conditions. Earth abundant transition metal oxides show great promise as catalysts for the oxygen evolution reaction. Here, the authors reveal a self-assisted water dissociation mechanism and favourable theoretical adsorption energetics for water oxidation at the edge sites of cobalt oxide nano-islands. The nature of water interactions with metal oxides is a topic of special interest for geochemistry, corrosion, catalysis and electrochemistry12342O in our experiments are located on the particle edges. These results highlight a special nature and reactivity of edge sites and propose that such minority sites should be payed special attention and considered in the efforts to further understand the detailed OER pathway on oxides. Inspired by our experimental study that emphasize significant differences between edge and basal plane sites, we extend the studies by means of density functional theory (DFT) calculations on the adsorption energetics of OER intermediates to address the potential of layered cobalt oxide structures as OER catalysts. The calculations reveal very favourable properties and a low theoretical overpotential for cobalt terminated edges, that is, the same sites also responsible for the observed water dissociation. Our theoretical modelling of the process observed in the experiment furthermore indicates that all the steps in the dissociation process, as well as in the following hydroxyl migration, are assisted by an additional water molecule, acting to lower the energy barriers involved.In this article, we investigate the mechanism of hydroxylation resulting from water dissociation on cobalt oxide nanoislands synthesized on a single gold (111) crystalThe majority (95%) of the cobalt oxide nanoislands synthesized on Au(111) are single Co–O bilayers that coexist with a minority (5%) of double Co–O bilayers, both oriented with a pristine close-packed O-terminated (111) basal plane parallel to the substrate with a cobalt layer in direct contact with the gold support . These sp(H2O)=2 × 10−7 mbar) at room temperature and investigated the surface with X-ray photoelectron spectroscopy (XPS). s XPS spectrum of the islands as a function of water exposure measured in Langmuir . The O 1s spectrum radically changes as a function of exposure. This can be monitored in more detail by deconvolution of the spectra into individual peaks, corresponding to distinct oxygen species. We find that three peaks are required to produce a satisfactory fit for the entire series. The low binding energy (BE) peak is predominant in the spectrum recorded for pristine nanoislands and represents lattice oxygen (Olat) within the nanoislands. The higher binding energy peak at 532.0 eV, on the other hand, increases significantly with water exposure and can be assigned to hydroxyl groups (OOH)lat as a function of water exposure, indicating that lattice oxygen atoms are hydroxylated in the process (lat to OOH of 1:1. We ascribe the weak intermediate energy peak to buried lattice oxygen present in the double bilayer islands (Odbl). The peak's intensity does not show dramatic changes throughout the experiment and the Odbl do not appear accessible for hydroxylation under our experimental conditions.To study water dissociation, we exposed the cobalt oxide nanoislands to water vapour perature  with a dexposure . Hydroxyexposure , inset iexposure  since thlat positions) of hydroxyls  under the experimental conditions for the defect-free basal plane is θOH=0.33, reflected by such a θOH≈0.5, as observed by XPS measurements  display the emergence of an ordered ydroxyls . In agresorbed H . Howeverurements . This ised on Au , consist,000 l diθOH was measured and compared with the effective island radius  for a number of islands in STM images in each synthesis. The hydroxyl density θOH follows exactly a trend inversely proportional to the radius, in agreement with edge activity, as dissociation on the basal plane sites would result in a constant θOH independent of r.The atom-resolved STM movies also reveal that the new hydroxyls originate from the edges of the islands before they diffuse to the basal plane , which is at first inspection inconsistent with the reactivity observed in the experiments at room temperature. Therefore, taking into account the water vapour background during the hydroxylation process, this step was modelled again in the presence of another water molecule in the vicinity. The influence of the additional water molecule is surprisingly strong, finding a significantly lower barrier of 0.41 eV. This demonstrates that the additional water assists water dissociation on the exposed Co sites by acting as a proton shuttle in form of a H3O species in the transition state  surface (see Methods section30on state . Such prEa=0.23 eV), as opposed to the non-assisted hopping (Ea=1.06 eV), similar to a previous study on H diffusion a FeO thin film3O species in the transition state formed from the water and the hydrogen on the surface. Upon dissociation of the H3O species, the excess H adsorbs again on the surface with equal probability on all three neighbouring O sites leading to overall diffusion of H across the surface. In the STM movies presented in −10 mbar), hydroxyls are almost completely static, as expected from the calculations. Moreover, the mobility was directly shown to strongly correlate with water vapour pressure by recording an STM movie similar to in situ (The hydrogen originating from the dissociated water in configuration (2) subsequently diffuses away from the Co-metal edge to energetically preferable configurations on the basal plane O lattice of the cobalt oxide stripe as in experiment ). Again, we find that the associated hydrogen hopping is much more efficient when it is assisted by water ( in situ .Ea=0.57 eV) compared with the first H dissociation step, but again strongly water assisted, following the same mechanism. The water dissociation process is −0.54 eV downhill in total energy at 0 K, while energy neutral at typical conditions of the experiment. Overall, the calculations indicate that water plays a far greater role than previously thought, not only assisting hydrogen hopping, but also mediating all the elementary steps of its own dissociation.The second dehydrogenation of the OH intermediate on the Co edge  is between 0.10 and 0.15 giving an expected maximum hydroxylation of θOH=0.20–0.30. Surprisingly, we always observe a significantly higher hydroxylation of θOH ≈ 0.5 in both XPS and STM at saturation  is related to the edge lengthx and NiOx catalysts in alkaline media is based on a single-site OH−/e− exchange mechanism1635363773516U=3.32 eV) level. We find that all of these steps require the interaction of the OER intermediates  at the under coordinated Co site at edges of the bilayer and trilayer nanoislands. Additionally, we have calculated the formation energies of vacancies on the fully O saturated basal plane, O edge and Co edge sites. Here, the O sites at the basal plane stand out as the sites with the highest oxygen vacancy formation energy , again pinpoint the edges as the preferable active site for the OER, and thus support the recent indirect evidence that β-CoOOH layers host the active sites for the OER on the edges−10 mbar. Cobalt oxide nanoislands were synthesized on a clean and flat Au(111) surface using the synthesis described in (ref. −6 mbar O2) and a post-annealing step at 523 K in the same environment and a final brief anneal at 523 K in UHV conditions. Milli-Q grade water was dosed from a glass vial into the UHV chamber via a leak valve. The water was first degassed by repeated freeze–pump–thaw cycles. The resultant islands were imaged using an ‘Aarhus'-type STM and XPS was done using the Matline endstation on the ASTRID II synchrotron, Aarhus (operating in ‘top up' mode). O 1s spectra were recorded at normal emission and a photon energy of 625 eV. The spectra were energy calibrated using the Au 4d 5/2 peak at a binding energy of 335.0 eV as a reference. There was no X-ray beam present on the sample during the water dosing.All syntheses and analysis was performed in UHV chambers with a base pressure of ∼1 × 10 in ref. . Brieflyab initio simulation package411U methodUeff =1 eV applied for the d-electrons of Co atoms. A standard energy cutoff of 400 eV and an approximately constant k-point mesh of 8 × 8 × 1 points per p(1 × 1) unit cell was kept in all slab calculations. In all cases, a metal-oxide bilayer and the upper most top layer of Au(111) were allowed to relax with the maximum force threshold of 0.02 eV Å−1, while at least 11 Å of vacuum was used to separate the layers. The magnetic structure was always taken to be the row-wise AFM structure, RW-AF-(2 × 1), known from FeO bilayersDFT calculations were performed using the projector augmented wave (PAW) potentialsp(1 × 1), p(✓3 × ✓3), p(2 × 2), p(3 × 3) to p(4 × 4) with the metal-oxide layer placed in a FCC stacking relative to a commensurate Au(111) lattice (p(✓3 × ✓3) metal-oxide, where we also adopted incommensurate p(✓3 × ✓3)/Au(2 × 2) structures known from a previous work on FeO on Pt(111)p(2 × 4) CoO FCC stacked within the p(2 × 8) unit cell of Au(111), referred to as p(2 × 4/2 × 8). Size effects were also tested for some reaction intermediates using two times wider p(4 × 4/4 × 8) stripes leading to very similar results. The transition states for water dissociation and hydrogen hopping were located by means of the climbing image nudged elastic band (CI-NEB) method, using at least five images along the reaction coordinateThe hydroxylation of basal planes was studied using infinite surfaces of periodicities ranging from  lattice . One excThe data that support the findings of this study are available from the corresponding author upon reasonable request.How to cite this article: Fester, J. et al. Edge reactivity and water-assisted dissociation on cobalt oxide nanoislands. Nat. Commun.8, 14169 doi: 10.1038/ncomms14169 (2017).Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Supplementary Figures-7 mbar H2O at room temperature. Time difference between single images: 82.02s.""STM movie  of a single bilayer CoO island during in-situ exposure to 2×10-8 mbar H2O at room temperature. Time difference between single images: 36.7s."STM movie  of a double bilayer CoO island during in-situ exposure to 5×10


However, transfer functions linking δ2Hp with δ2Hf are influenced by physiological and environmental processes. A better understanding of the causes and consequences of variation in δ2Hf values among individuals and species will improve the predictive ability of geographic assignment tests. We tested for effects of species, land cover, forage substrate, nest substrate, diet composition, body mass, sex, and phylogenetic relatedness on δ2Hf from individuals at least two years old of 21 songbird species captured during the same breeding season at a site in northeastern Alberta, Canada. For four species, we also tested for a year × species interaction effect on δ2Hf. A model including species as single predictor received the most support (AIC weight = 0.74) in explaining variation in δ2Hf. A species-specific variance parameter was part of all best-ranked models, suggesting variation in δ2Hf was not consistent among species. The second best-ranked model included a forage substrate × diet interaction term (AIC weight = 0.16). There was a significant year × species interaction effect on δ2Hf suggesting that interspecific differences in δ2Hf can differ among years. Our results suggest that within- and among-year interspecific variation in δ2Hf is the most important source of variance typically not being explicitly quantified in geographic assignment tests using non-specific transfer functions to convert δ2Hp into δ2Hf. However, this source of variation is consistent with the range of variation from the transfer functions most commonly being propagated in assignment tests of geographic origins for passerines breeding in North America.Understanding bird migration and dispersal is important to inform full life-cycle conservation planning. Stable hydrogen isotope ratios from feathers ( Each year, billions of birds migrate between breeding and wintering areas . Migrati2H:1H; depicted as δ2H) are now the most commonly used marker [δ2Hp) worldwide is well documented [δ2Hp (i.e. isoscapes) have been used in combination with δ2H from feathers (δ2Hf) to infer geographic origin of birds as the H in bird feathers is ultimately derived from environmental waters where the feather was grown [δ2Hp values need to be adjusted to reflect the difference between local precipitation driving food webs (δ2Hp) and δ2Hf , stabled marker . Predictcumented . The resas grown , 12. In as grown ) may proas grown –16. Howections”; ). Clark ctions”;  providedctions”;  found thpiration  or diffepiration .δ2Hf and δ2Hp have been documented, what causes this interspecific variation is not as well understood. Analytical approaches have been developed to deal with this uncertainty in Bayesian assignment tests to provide more accurate and less biased estimates of likely geographic origin [δ2Hf among species with the same geographic origin should help in assessing those factors contributing to variation we see among various transfer functions. For example, evaporative processes in response to increased activity or ambient conditions may lead to higher δ2H in tissues [δ2Hf values relative to species associated with forest understory. Increased body water loss due to metabolic activity can result in enriched heavy isotopes in the body water pool, in turn leading to higher δ2Hf values, and this effect might be more important in smaller individuals/species [Trachycineta bicolor) was positively correlated with δ2H from blood samples. Phylogenetically conserved life history traits [δ2Hf that could explain important interspecific variation. Inter-annual variation in δ2Hf has been reported for a few songbird species [δ2Hf of forest songbirds. Finally, different species may seek out different local microhabitats during the molt period and these might also account for differences in δ2Hf from the same general area but little is known about habitat use during this typically “secretive” period of the annual cycle .δ2Hf. Specifically, we used a model selection approach to compare the relative importance of species, land cover type, forage substrate, nest substrate, diet composition, body mass, sex, and phylogenetic relatedness in explaining variation in δ2Hf among experienced breeders  of 21 songbird species (7 families and 16 genera). We predicted that ground foragers and insectivores  would have higher δ2Hf compared to non-ground foragers and omnivores , respectively. Observed δ2Hf for ground and non-ground foragers were used to validate predicted values from the transfer functions provided by Hobson et al. [δ2Hf than those nesting in forest understory. Finally, we predicted that closely related species (i.e. within the same genera) would have more similar δ2Hf values than less related individuals. There were no a priori expectations regarding the direction of the effect (positive or negative) of body mass and sex  on δ2Hf. Females are more likely to experience breeding dispersal movements, i.e. straight-line distance moved by an individual from a breeding territory to another in subsequent years, and over larger distances than males [δ2Hf values than males, but larger variation, assuming no bias in direction of dispersal movements. For four of our most common species, we also tested for a year × species interaction effect on δ2Hf to determine whether annual variations in δ2Hf are consistent among species.In this study, we used tail feathers collected from different songbird species during the same breeding season and geographic area (within a ca. 130 km radius) to test various hypotheses that have been proposed to explain intraspecific and interspecific variation in n et al. . We alsoan males . Thus, wPicea mariana; white spruce, Picea glauca; jack pine, Pinus banksiana), deciduous , and mixedwood stands typical of the western boreal forest. The banding stations in the oil sands region are similarly forested, but also occur in riparian areas and reclaimed mine sites.The study was conducted at bird banding stations in the Lesser Slave Lake Provincial Park  and the lower Athabasca oil sands region  in northeastern Alberta, Canada. The region is characterized by conifer  were attracted to mist nets using conspecific song playback. Additional samples were also collected from these 4 MAPS stations. Two 3rd rectrices were plucked from as many captured individuals as possible and individual body mass was recorded at time of capture. All feathers were stored in paper envelopes at room temperature. In the oil sands region, birds were captured and feathers were collected by KF, CG (banders-in-charge), and their banding staff. At Slave Lake, birds were captured and feather samples were collected by RK (bander-in-charge), LSLBO banding staff, and volunteers.Breeding birds have been captured at banding stations as part of the Monitoring Avian Productivity and Survivorship (MAPS) program . In 2013http://www.birdpop.org/). We further determined age of some S. aurocapilla by quantifying the wear pattern of the 3rd rectrices [http://www.on.ec.gc.ca/wildlife/wildspace/project.cfm; Only feathers from males and females of at least two years old  were used for isotope analysis. These individuals were selected based on the higher site fidelity reported in adult songbirds compared to first-year breeders , 34. Alsectrices . Featherectrices ). For eaFieldwork was conducted in accordance with the Canadian Council for Animal Care and the permit for this study was approved by the University of Alberta Animal Care Committee (permit # AUP00000100). Federal and provincial bird banding and feather collection permits for this study were approved by the Canadian Wildlife Service and Alberta Environment and Sustainable Resource Development, respectively.2 pulses were used to measure δ2Hf by continuous-flow isotope-ratio mass spectrometry (CF-IRMS). For both laboratories, we used the comparative equilibration approach with the same in-house keratin working standards  to account for exchangeable hydrogen in keratins where δ2H of nonexchangeable H was established [δ2Hf) in units of per mil (‰) and the analytical error, based on within-run replicates of keratin reference standards (n = 5 per run) was ±2‰. Results are reported relative to the Vienna Standard Mean Ocean Water—Standard Light Antarctic Precipitation (VSMOW-SLAP) scale.Surface oils were removed from all feathers by using a 2:1 chloroform:methanol solution. The central vane of each feather was weighed (350 ± 20 μg) and samples were secured in silver capsules. Isotopic analysis was conducted at the Colorado Plateau Stable Isotope Laboratory at the Northern Arizona University for 2011 samples and the Stable Isotope Hydrology and Ecology Laboratory of Environment Canada for 2013 samples. Samples were exposed to high temperature (1350°C) flash pyrolysis and the separated Hablished . Thus weablished ). Resultδ2Hf values from individuals of the selected species captured in 2013 were influenced by species, individual, and land cover factors (fixed effects) and phylogenetic relationships across species (random effects). A Multivariate Normal distribution was specified for each model where fixed effects are part of the mean specification, while random effects are part of the covariance structure. The response variable (yij) was δ2Hf for individual i (i = 1…n) of species j (j = 1…s). We examined 15 different fixed effects as possible explanatory factors for δ2Hf and compared them to a (0) null (intercept only) model. The fixed effects included species , banding station , individual , and interactive effects  was included as a random effect in our 15 models and we divided each model into two subsets where variance in δ2Hf among species was estimated as homoscedastic  and heteroskedastic . To examine the phylogenetic correlation in δ2Hf, we estimated a multiplier of the off-diagonal elements in the Multivariate Normal covariance matrix defined as λ [yij, yik) and corresponding Mutivariate Normal means  was defined as cov = σjσktjkλ, where tjk is proportional to the shared evolutionary path length between species j and k.Residual variance  unless specified otherwise. We also extracted δ2Hp values for our study area from the isoscape provided by Bowen et al. [2Hf for omnivores and insectivores following Hobson et al. [A two-way ANOVA was used to test for a Year (2011 and 2013) × Species  interaction effect on on 3.1.0 . Resultsn et al.  .Standard deviations were smallest for Mourning Warbler (± 4‰) and largest for Song Sparrow ± 22‰; . The 95%n et al.  for groun et al.  for our δ2Hf (δ2Hf ranged from -135 ± 16‰ (mixedwood) to -162 ± 6‰; (agriculture) across nest substrate . Three of the four species had higher δ2Hf values in 2013 compared to 2011 , while the Ovenbird had lower δ2Hf values in 2013 compared to 2011  performed better than the homoscedastic model subsets  Tables. δ2Hf  Tables. ubstrate  and was ubstrate . Lastly,011 -6‰; .δ2Hf among songbird species breeding in the same region. Species was the strongest predictor of the variation in δ2Hf among individuals followed by a nesting substrate × diet composition interaction effect. Limited support was found for single effect models that included life history traits, individual (sex and body mass), or land cover predictors. Some studies have found support for these predictors [δ2Hf between years are not always consistent among species. Our results provide important insights regarding different sources of error being propagated in Bayesian assignment tests and suggest that the use of species- and year-specific δ2Hf isoscapes could improve the accuracy of assigned geographic origin of birds .δ2Hf compared to those foraging in the upper- or lower-canopy. Mean δ2Hf values or corresponding 95% confidence intervals for the 15 focal species did indeed overlap with predicted values from the transfer functions of Hobson et al. [δ2Hf compared to those using forest understories. In temperate or boreal ecosystems, differences in ground temperature between closed and open habitats may not influence evapotranspiration rates and, ultimately, δ2Hf. For example, Hache et al. [δ2Hf between nestlings from recent selection harvesting (open) vs unharvested stands (closed). However, most adult songbirds start molting during the post-fledgling period and some mature forest specialists have been shown to aggregate in open-canopy clearcuts for concealment from predators during this period [δ2Hf of ASY songbirds from a given region, but it is unclear to what extent resources consumed during the nesting period can be integrated in tissues that have grown during the post-fledging period  could aod e.g. , 56)..δ2Hf comδ2Hf than smaller birds because larger individuals or species lose proportionately less of their total body water to evaporative processes [δ2Hf in adult songbirds, but differences in body mass among individuals at the time of capture might not reflect differences during the molting period. Females also did not have different δ2Hf values than males [δ2Hf was only slightly lower for males than females. These results indicate that population level assignments can be generated irrespective of body size and sex of individuals.Birds with larger body sizes could have lower rocesses , 22. Howan males  and variδ2Hf can be used as a proxy for breeding dispersal rate and distance, i.e. species with larger variation might have a higher proportion of individuals that experienced breeding dispersal movements and/or dispersed over larger spatial extents. The relatively small variation around mean δ2Hf reported for all focal species in this study suggests that most dispersal events would have occurred within the isocline corresponding to predicted δ2Hf for our study area. However, differences in mean δ2Hf among species could also reflect population-level post-breeding movements  and molt occurring elsewhere in the species breeding range .δ2Hf. Differences in variation around species-specific mean δ2Hf in a region might reflect interspecific differences in breeding dispersal rates, but also differences in niche breath. Habitat generalists use a broader range of land cover types which could result in greater variation in δ2Hf than habitat specialists. However, species-specific tolerance  was notδ2Hf values than less related species. Our 15 focal species represented only 3 families  and may have been too closely related to detect phylogenetic effects. We also expected a consistent difference in δ2Hf between years (2011 vs 2013) for the 4 focal species, but this effect was not observed. If year effects on δ2Hf were exclusively driven by differences in δ2Hp across years, we would expect a proportionate year effect across species breeding in the same region. Future studies should aim to identify the underlying mechanisms explaining this interaction effect. This could potentially be achieved by quantifying differences in δ2Hf for a broader range of species and years. Nonetheless, along with species-specific variation in δ2Hf, this species × year interaction effect was another important factor and likely corresponds to a large proportion of the variance being propagated in Bayesian assignment tests [Studies have shown morphological traits to be more similar in closely related passerine species while for other traits, such as behavior and habitat associations, this might not be the case . In thisnt tests .δ2Hf. However, we had limited success identifying the underlying mechanisms. Future studies should determine whether missing variables or interaction terms could explain interspecific variation in δ2Hf or more precisely determine where birds undergo the prebasic molt relative to breeding territories. A better understanding of the variation in δ2Hf within and across years (i.e. across a larger number of species and years) should provide important information about sources of error being propagated in assignments of geographic origin. Transfer functions to explicitly account for these sources of error would likely help generate more precise and accurate assignments and provide better information on migratory bird movements to inform full-cycle conservation strategies. However, our ability to integrate these sources of variance in assignment tests will depend on the objectives. For example, it might be unrealistic to expect that species- and year-specific δ2Hf isoscapes would be available over large spatial extent. Alternatively, it would be possible to document regional dispersal movements [δ2Hf isoscapes would depend on the study region because the degree of inter-annual variation in δ2Hp differs among regions. It is also likely that we are close to identifying the limit of accuracy of this single isotope approach, highlighting the importance of combining multiple markers in multivariate assignment tests [We provided evidence suggesting that the most important source of error being propagated in assignment tests of geographic origin of birds is likely interspecific variation in ovements , 4. Resuovements  also sugnt tests , 61–63.δ2Hf values. For example, it is still unclear how local hydrology interacts with biology by influencing relationships between δ2H values of foodwebs used by birds during the molt period and their subsequent δ2Hf values. At interior continental sites, there are extreme seasonal effects in precipitation δ2H values [δ2H values experienced by molting birds. In northern regions where H from snowmelt contributes to the overall foodweb leading to bird feathers, the use of an amount-weighted mean annual precipitation δ2H value or an average corresponding to those months where δ2H from precipitation has the strongest influence on the foodweb may be more appropriate. Nonetheless, our study provides encouraging evidence that once isotopic variance is understood and accounted for, current assignment isotopic models provide a valuable means of propagating such variance into the most parsimonious depiction of origins for North American passerines.Finally, there are a number of caveats that need to be considered in our study and future research is encouraged to investigate further potential mechanisms contributing to within-site variance in H values  and nortS1 File(DOCX)Click here for additional data file.S1 Table(DOCX)Click here for additional data file.S2 Table(DOCX)Click here for additional data file.


These limits basically rule out most of the existing popular dark matter interpretation of the GeV excess in the Milky Way.Recently, some very tight constraints of annihilating dark matter have been obtained from gamma-ray data of the Milky Way and Milky Way dwarf spheroidal satellite galaxies. In this article, we report that there are two excellent galaxy clusters (A2877 and Fornax) which can provide interesting constraints for annihilating dark matter. The lower limits of the dark matter mass for the thermal relic annihilation cross section are 25 GeV, 6 GeV, 130 GeV and 100 GeV respectively for the  These limits give a certain tension for the dark matter interpretation of the GeV excess in the Milky Way. Besides, some recent studies suggest that the GeV excess in the Milky Way can be explained by pulsars’ emission13 or depletion of gamma rays in molecular clouds14. Furthermore, recent results of Fermi-LAT gamma-ray detection strongly disfavour the dark matter interpretation of the GeV excess15. Therefore, the GeV excess in the Milky Way becomes a very controversial issue in dark matter astrophysics now.In the past few years, gamma-ray observations of the Milky Way initiated a hot research area about dark matter annihilation. Many studies16 find that the gamma-ray data from the Fornax cluster is quite good to constrain the parameters of dark matter annihilation because its cosmic ray emission is not very significant. The cross section constrained by using the Fornax cluster data is <συ>≤ (2–3) × 10 cm3 s−1 16. Besides, Huang et al.17 use three years of Fermi-LAT data of several nearby galaxy clusters to constrain annihilating dark matter. The upper limits of annihilation cross section are also of the order 10−25 cm−3 s−1. Later studies of gamma-ray emission from galaxy clusters and galaxy groups give more stringent constraints on dark matter parameters. For example, Ackermann et al.18 and Lisanti et al.19 exclude the thermal relic annihilating dark matter via m ≤ 40 GeV and m ≤ 30 GeV respectively. Also, using new Fermi-LAT data of nearby galaxy clusters can provide stringent constraints for gamma-ray line feature of annihilating dark matter20. Besides gamma-ray data, by using radio data of galaxy clusters, the annihilation cross sections for some channels can be constrained down to 3 s−1 23, though the uncertainties due to magnetic field strength are somewhat significant. Overall speaking, these limits are quite close to or even tighter than some of the parameters for the dark matter interpretation of the GeV excess in the Milky Way.Although most of the gamma-ray observations are now focusing on the Milky Way and the MW dSphs galaxies, some studies start to realize that galaxy clusters are also good candidates to constrain annihilating dark matter. For example, Ando & NagaiIn this article, by using the latest gamma-ray data of galaxy clusters from Fermi-LAT, we show that the A2877 and Fornax clusters can give very stringent constraints for annihilating dark matter. Our results improve the current limits of annihilation cross sections for wide ranges of dark matter mass. These limits are tighter than the parameters involved for the dark matter interpretation of the GeV excess in the Milky Way.Generally speaking, there are two different kinds of gamma-ray emissions for annihilating dark matter in galaxy clusters. One is ‘direct emission’ and the other is ‘indirect emission’. ‘Direct emission’ means the gamma-ray photons produced when dark matter particles annihilate each other. Since dark matter annihilation also produces electron and positron pairs, these electron and positron pairs can interact with the thermal electrons in galaxy clusters via Bremsstrahlung cooling. This process would emit gamma-ray photons if the energy of the electrons or positrons is high enough. This kind of emission is regarded as ‘indirect emission’.E0 produced by annihilating dark matter within a galaxy cluster can be calculated byρDM is the dark matter density profile, R200 is the radius of a galaxy cluster, and dNγ/dE is the energy spectrum of gamma-ray produced per one annihilation, which can be obtained in24. Based on the sample of galaxy clusters in25 and the observed limits of gamma-ray flux Φobs obtained in26, there are two galaxy clusters (Fornax and A2877) which have the largest ratio I/Φobs, where I/Φobs can give tighter constraints for annihilating dark matter. Therefore, we choose the Fornax and A2877 clusters to perform analysis. By assuming the dark matter density profiles of the A2877 and Fornax clusters follow the Navarro-Frenk-White (NFW) density profile ρDM = ρsrs3[r(r + rs)2]−1 27 and using the corresponding parameters in28, we can get the total photons produced with energy greater than E0 for direct emission.The total number of photons for direct emission with energy greater than 32. However, the actual value of the boost factor in a galaxy cluster is controversial. Some high-resolution simulations can get the boost factor 29 while other studies point to a lower value of the order 31. Moreover, the effect of tidal interaction in galaxy clusters is also controversial. Some studies point out that tidal interaction would give a lower boost31 while some studies suggest that tidal stripping can increase the boost factor by 2–5 times33. Here, for a conservative estimation, we neglect the effect of tidal interaction and take the lower bound of the boost factor, which can be described by a simple parametrization31:bi =  and M200 is the total mass of a galaxy cluster. The accuracy of this parametrization is better than 5% in the mass range 31. For the A2877 and Fornax clusters, the total mass M200 are 28. Therefore, the parametrization can be applied and the corresponding boost factors are 35 and 30 respectively. As discussed in32, the boost factor of the order D is the distance of the galaxy cluster. Here, we are using the point-source approximation, which can be justified because we will compare the calculated fluxes with the ‘point-source upper limits’ in26.On the other hand, recent numerical simulations show that substructures’ contribution for dark matter annihilation is very significant. High dark matter density of the substructures can boost the annihilation signal to more than 10–100 times for galaxy clusters2 s−1 34, the diffusion time scale for a 1 GeV electron is about 21b(E) is the cooling function which is given by34n is the thermal electron number density in cm−3, EGeV = E/1 GeV, Bμ is the magnetic field strength in μG, bIC = 0.25 × 10−16 GeV s−1, bsyn = 0.0254 × 10−16 GeV s−1, bcou = 6.13 × 10−16[1 + log(γ/n)/75] GeV s−1, bbrem = 1.51 × 10−16[log(γ/n) + 0.36] GeV s−1 and γ is the Lorentz factor of a high-energy electron or positron. We follow the β-profile to model the thermal electron number density profile in a galaxy cluster:n0, rc and β are fitted parameters, which can be obtained in25. For the magnetic field profile, we follow21 to useB0 = 4.7 μG and η = 0.5 for both galaxy clusters (the effect of the uncertainties in B will be discussed below)21.Dark matter annihilation also produces electron and positron pairs. These electrons and positrons would diffuse and cool down to a lower energy by synchrotron cooling, inverse Compton scattering, Bremsstrahlung cooling and Coulomb cooling. Since the diffusion coefficient for a typical galaxy cluster is about E0 can be given by35For Bremsstrahlung emission (indirect emission), the total gamma-ray photons emitted per second for indirect emission with energy greater than By taking the same boost factors, we can calculate the indirect emission flux for each galaxy cluster by The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.dir + Φind emitted from each of the galaxy clusters. Based on the observational results from Fermi-LAT26, we obtain the fluxes for three lower limits of gamma-ray energy E0 = 0.5 GeV, E0 = 1 GeV and E0 = 10 GeV. Also, we use the upper limits of the fluxes for these values of E0 to constrain E0 (see Table E0).We can now obtain the total gamma-ray flux Φ = Φe+e− for 4 popular channels   by nearly an order of magnitude. Nevertheless, by using radio data of galaxy clusters, some recent studies can give more stringent constraints of annihilation cross sections. For example, Beck & Colafrancesco22 obtain m ≥ 200 GeV for the thermal relic annihilation cross section via τ+τ− by using the radio data of the Coma cluster. However, these studies constrain dark matter annihilation by synchrotron radiation which may suffer from large uncertainties of magnetic field strength. Although our study also includes the consideration of magnetic field strength, we consider the effect of Bremsstrahlung radiation due to magnetic field, but not synchrotron radiation. As discussed below, the uncertainties of magnetic field do not affect our result significantly. Therefore, using gamma-ray data is more reliable than using radio data for constraining annihilating dark matter, especially in using data of galaxy clusters. Based on the above discussion, we suggest that the Fornax and A2877 clusters are better candidates for constraining annihilating dark matter.Furthermore, our results are more stringent than that obtained by other recent studies with the data of galaxy clusters. For example, recent studies using the data of Virgo clusterτ+τ− or 5 . The contribution of indirect emission varies with dark matter mass mildly. The largest values of the ratio Φind/Φdir for the e+e−, μ+μ−, τ+τ− and E ≤ 1 GeV). In the above calculations, we used a typical central magnetic field strength B0 = 4.7 μG and a typical index η = 0.5. We have tried another extreme value B0 = 25 μG21 and change the index η to 0.4, we find that the overall upper limits of annihilation cross sections are just larger by E ≥ 10%. Therefore, the effect of the systematic uncertainties of magnetic field strength (or contribution from indirect emission) is not very significant. The reason is that the most stringent constraints mainly come from the data of gamma-ray flux E ≥ 10 GeV. Changing the magnetic field strength does not affect too much for the gamma-ray flux for E ≥ 10 GeV.We have also checked with the effects by varying the magnetic field strength, dark matter profile and boost factor for both galaxy clusters. First of all, the magnetic field strength mainly affects the indirect emission for low energy , the boost factor of the Fornax cluster is 525. The resultant constraints are much tighter . We improve the upper limits of annihilation cross sections by a factor of 1.3–1.8 for wide ranges of m for e+e−, μ+μ− and τ+τ− channel (for m ≤ 100 GeV). Tighter constraints are obtained because we have considered the ‘indirect emission’ (Bremsstrahlung emission) and the effect of substructures in galaxy clusters. In particular, the effect of substructures is significant in galaxy clusters as they are large and massive structures. Besides, we have used the most updated gamma-ray data for analysis, which provide more stringent limits for annihilating dark matter. Furthermore, among a large sample of nearby galaxy clusters, we found that the A2877 and Fornax clusters are the best candidates to constrain dark matter annihilation cross section because they have larger values of I/Φobs.Recently, it has been reported that the excess gamma-ray emission in the Milky Way can be best explained by dark matter annihilation. The proposed dark matter mass is about 15.Besides, the lower limits of the dark matter mass for the thermal relic annihilation cross section are larger than the mass expected in dark matter interpretation of the gamma-ray excess. We show that most of the existing popular dark matter interpretation of the GeV excess in the Milky Way are ruled out. Our results basically support the latest Fermi-LAT analysis of the Milky Way GeV excess44. Therefore, our results are quite consistent with these experimental results that dark matter mass may be much larger than the previous expected values. We expect that future observations of TeV gamma rays46 and anti-proton detection48 might provide some new insight of dark matter annihilation.In fact, searching dark matter particles is one of the most important tasks in particle physics. However, the null detection in direct detection experiments may indicate that dark matter mass is probably larger than 1 TeV


Carassius, deeper body depth is more adaptive to avoid predation by gape-limited piscivorous fish, but it raises swimming costs. It is therefore predicted that the relative body depth will decrease when the prey fish has reached a size larger than the predator gape-size. This prediction was tested by allometric analysis of the relation between body depth and standard length of triploid asexual females of the Japanese crucian carp (Carassius auratus sspp.) sampled from 13 geographic populations. The overall allometric relation was not significantly different from isometry. The estimate of the common major-axis slope was close to 1 (near-isometry). The mean relative body depth differed significantly among populations. A significant positive correlation was found with the mean annual air temperature. The geographic variation suggests that local selection pressures vary. In conclusion, the hypothesis that larger fish will have lower body depth was not supported, perhaps indicating that deep body depth in large fish is adaptive for some reason other than defense against piscivorous fish.Costly anti-predator traits tend to be expressed only in high-predation conditions. For the cyprinid fish genus  Carassius carassius), a well-studied freshwater fish for testing the theory of predator-inducible defense, the presence of chemical cues from piscivorous fish  has been shown to induce a deeper body depth55102Defense traits against predation often entail costs or tradeoffs1223n = 16, Kivilampi pond n = 24, Marjalanlampi pond n = 13Size-limited predation can also cause changes in the extent of constitutive or induced defense during the ontogenetic growth of an organism 16Carassius auratus sspp.). Japanese crucian carp, which are closely related to crucian carp, are distributed widely throughout freshwater areas in JapanSilurus asotus)Carassius auratus auratus). The enlarged morphology reduces predation risk from a piscivorous fish (yellow perch Perca flavescens)192223For this study, we test the defense-allometry hypothesis for body-depth morphology using geographic populations of Japanese crucian carp 16Y = log α + β log X or to test for a non-one allometric slope β because both variables are expected to be subject to natural variation and measurement error2527For the analysis conducted using the allometric equation R2) were generally high but were variable among the populations . The common major-axis slope was estimated as 1.004 , indicating a nearly isometric growth pattern . This isometric property enables us to use the relative body depth  in the following analysis of the pattern of the trait variation among populations because the ratio is independent of body size in cases of isometry25A double logarithmic plot of body depth on standard length of the triploid asexual Japanese crucian carp from 13 populations , Table 1F12,67.08 = 26048, P < 2.2 × 10−16). The total variation in the relative body depth was 45% explained by the between-population variation and 55% by within-population variation . Within-population variation in the relative body depth was significantly different among populations .The mean relative body depth of the triploid asexual Japanese crucian carp differed significantly among 13 populations . The mean air temperature explains 15% of the total variation in the relative body depth  was included in the range of body depths of the studied carp  and were approved by the FRA.Fish samples were collected from 13 geographic populations in Japan ; Table 1The populations of Japanese crucian carp include sexual and asexual fish, which are distinguishable by ploidy or cell size1922232223The standard length , body depth , and the caudal peduncle depth  of the samples of carp were measured to the nearest millimeter. The caudal peduncle depth was measured as an instrumental variable for the instrumental-variable regression2223Temperature data for each region (population) were obtained to assess the relation between temperature and body depth of carp. Mean annual air temperature of geographical regions listed in Y = αXβ and the logarithmic linear form log Y = log α + β log X were used as a model to study the functional relation between body depth Y and standard length X of carp. β is the allometric coefficient (slope) that expresses the relative growth rate. Relative growth of the body depth might be positive (β > 1), negative (β > 1), or isometric (β = 1). Because both body depth and standard length are expected to be subject to errors and because both variables are measured in the same units (cm), major-axis regression was used to estimate the allometric equation252627λ did not change the results (not shown). We calculated a neighborhood contiguity between populations . In addition, the mean of their differences was small (0.157 cm). However, the body weight of the females before spawning (mean: 225.69 g) was significantly greater than that after spawning (mean: 207.63 g) . Morphological observations of females before and after spawning were also performed. The females after spawning had a thin abdomen between the ventral fin and the anal fin, but showed no significant change in body shape between the pectoral fin and the ventral fin, which included the measurement site of the maximum body depth. In conclusion, results of these analyses show negligible effects of the gonadal condition on body depth.Sampling in different seasons  revealedn = 58) after anesthetization with 0.2 ml/L 2-phenoxyethanol. The vertical gape opening of the mouth was 2.2–6 cm. The mouth width was 2.6–6 cm. To predict the mouth size for a given standard length, the parameters of the allometric relation were estimated using ordinary least-squares regression . Even when both variables are subject to errors, the ordinary least-squares regression is recommended for prediction .Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


We also report a carbon isotopic ratio typical of C4 plants, which may indicate millet consumption in the Late Bronze Age, despite suggestions of the crop’s earlier arrival in Europe during the Neolithic.The development of farming was a catalyst for the evolution of the human diet from the varied subsistence practices of hunter-gatherers to the more globalised food economy we depend upon today. Although there has been considerable research into the dietary changes associated with the initial spread of farming, less attention has been given to how dietary choices continued to develop during subsequent millennia. A paleogenomic time transect for 5 millennia of human occupation in the Great Hungarian Plain spanning from the advent of the Neolithic to the Iron Age, showed major genomic turnovers. Here we assess where these genetic turnovers are associated with corresponding dietary shifts, by examining the carbon and nitrogen stable isotope ratios of 52 individuals. Results provide evidence that early Neolithic individuals, which were genetically characterised as Mesolithic hunter-gatherers, relied on wild resources to a greater extent than those whose genomic attributes were of typical Neolithic European farmers. Other Neolithic individuals and those from the Copper Age to Bronze Age periods relied mostly on terrestrial C They al on them ,55. In t factors ,57. C4 pn Europe –60.15N) in tissues increase with trophic level, with a stepwise increase of 3–5‰ between diet and consumers. This trophic level increase is used to analyse the relative consumption of plant versus animal proteins in the diet [15N-enriched compared to terrestrial foods, due to longer and more complex food webs [15N values in soils resulting in higher nitrogen isotope ratios in the tissues of animals and humans consuming fertilised crops [Nitrogen stable isotope values , soiood webs ,67), cliood webs ,69), heaood webs , or breaood webs  have alsed crops –74.3 plants made most of the contribution to individual’s diets, except for some sites where some individuals’ δ13C values suggest an increase in C4 plant consumption (e.g. millet) [Previous stable isotope research in Hungary has focused on Neolithic and Copper Age populations ,42,75,76 millet) . However4 plant resources in the Late Bronze and Iron Age periods.This study includes isotopic data from a 5,000 years transect of the GHP, including Bronze and Iron Age periods, and analyses dietary changes along prehistoric time in the GHP. Specifically, the aim of this study is to investigate if the genetic changes and cultural transitions occurred in the GHP from Early Neolithic to Iron Age were associated with dietary shifts. The analysis focuses on carbon and nitrogen stable isotope ratios of bone collagen of 13 individuals reported in [Carbon and nitrogen stable isotope analysis was carried out on collagen from bone samples of 52 human individuals from both sexes and various ages, along with 17 faunal bone samples representing 6 species from three settlements Tables  Tables. p<0.05 at the statistical significance level , are consistent with expected ranges for a terrestrial C3 environment [Both domestic fauna  and wild fauna  were used for statistical purposes, and are reported in ironment . The nitp = 0.076)  .When comparing domesticates, no significant differences were found in carbon isotopic mean values over time  . However< 0.001) . By cont13C values reported here range from −22.6‰ to −14.4‰ ) and the δ15N values range between 8.8‰ and 13.1‰ ) (The human δ8‰ (1σ)) .13C values consistent with a diet based on terrestrial C3 resources  than other Körös Early Neolithic and later period individuals (p<0.05) higher δ13C values than those reported for previous periods  have significantly lower values (p<0.05) than individuals from the Middle Neolithic to Middle Copper Ages  than the values for Middle Neolithic individuals  than Late Neolithic and Middle Copper Ages samples  than those of the Early Neolithic  interpreted as freshwater resource consumer [15N values of Körös Tiszaszőlős-Domaháza individuals, nevertheless, are even higher (~1.5‰) than the Maroslele-Pana Mesolithic individual. This suggests that freshwater resources either made a greater contribution to the diet than at Maroslele-Pana, or that higher trophic level freshwater resources were consumed. Thus, the levels of fish consumption at Tiszaszőlős-Domaháza would appear to be a continuation of a Mesolithic dietary pattern, in accordance with the non-admixed Western hunter-gatherer genetic pattern found previously [The two Körös individuals from the site of Tiszaszőlős-Domaháza have lower δhis site . The sithis site  suggest consumer . The δ153 terrestrial resources. Nevertheless, there appears to be some temporal and regional variation. The Körös Early Neolithic samples have lower δ13C mean values than those of the subsequent Middle Neolithic, Copper and Early Bronze Age. Although small, the consistency of this difference suggests that it is a genuine reflection of either environmental influences on plant or animal δ13C values, such as increased irrigation [4 plant resources . Although archaeobotanical evidence for the presence of common millet [4 plant consumption exist in some Hungarian sites from the Early Neolithic [13C values from Middle Neolithic to Early Bronze Age might indicate the inclusion of some C4 plant source in the diet, explaining its difference with previous Early Neolithic samples. However, the consumption was not as important as other C3 crops as their δ13C values still indicate that diet is overwhelmingly based on terrestrial C3 plants.The remainder of the Neolithic, Copper and Early Bronze Age human isotopic data suggest a broadly similar diet based on Crigation , or dietn millet  and isoteolithic , millet 3 plant resources. In contrast, the Late Bronze Age and Early Iron Age individuals have significantly higher δ13C‰ than the values reported for earlier periods. Marine consumption would seem extremely unlikely given the landlocked location of the GHP, but the consumption of millet is entirely possible. As mentioned above, there is some scattered evidence that broomcorn millet may have been present in Europe (including Hungary) from the Early Neolithic [4 crop gradually intensified from the Bronze to Iron Ages. The C4 plant input in the diet of Late Bronze and Early Iron Age people may originate from the direct ingestion of cultivated millet or consumption of fauna foddered with this C4 plant. However, without associated faunal values it is not possible to discern between these two possibilities.Although two of the Bronze Age individuals analysed in  have oveeolithic ,42,43. Heolithic . Stable eolithic ,45,82–84eolithic . The regeolithic . This maeolithic ), or migeolithic . Alterna15N values from the Middle Neolithic onwards. Nitrogen isotopic ratios have been shown to be affected by several environmental factors . Therefore, although the homogeneity of δ15N values may be explained by changes to agricultural practices, other factors may also have caused an increase of the values themselves in humans and domesticated fauna.The nitrogen data exhibit variability from Early Neolithic to Early Iron Age. The results from humans  and domesticated animals, show significantly higher and more homogenous δors  [15N range in values of human bone collagen was suggested for a combination of manured crops and animal protein intake in early Neolithic European farmers [15N values in the wild fauna used here suggest that probably the enriched 15N isotopic ratios from Middle Neolithic domesticated fauna are due to the use of fodder from manured crops [Previous studies in the same area show that high δ manure) ,29. Nitr manure) –74. Thes manure) . Thus, a farmers ,73,88. Aed crops ,88. Thused crops ,29.15N values during the Early Copper Age could be ascribed to important changes that occurred during the Neolithic and Copper Age transition. During this transition, there were crucial changes in the use of the landscape, with settlements more dispersed across the landscape and fewer nucleated sites [15N mean values is not statistically significant, and it is the variability of individual values that increase from previous Late Neolithic ones  and results must be interpreted with caution.As well as this, Hoekman-Sites and Giblin  argued f3 plant resources seems to be common from Early Neolithic to Copper Age periods, in accordance with the genomic stasis [13C ratios than previous times suggesting a dietary change with a higher consumption of millet, which is in accordance with its wide cultivation in Europe from the second millennium BC. Nitrogen isotopic ratios from both domesticated fauna and humans are suggestive of consumption of fertilised crops from Middle Neolithic, which may be probable due to the use of secondary agricultural products (manure) [In summary, the results of the isotopic data analysed here suggest changes in dietary patterns from Early Neolithic to Early Iron Age that are not in all cases associated with cultural and genetic shifts. The dietary practices of the individuals from the Early Neolithic Körös site of Tiszaszőlős-Domaháza is in accord with the genetic data. Their dietary isotopic profiles resemble the continuity of a Mesolithic hunter-gatherer pattern with an important reliance on freshwater resources consumption. The Mesolithic genomic signature of one of the individuals, together with similar dietary patterns, might indicate some evidence of contact between Early Neolithic communities and indigenous hunter-gatherers, as previously suggested . A diet c stasis . Althoug(manure) .S1 Appendix(DOCX)Click here for additional data file.S2 Appendix(DOCX)Click here for additional data file.S1 Table13C‰ and δ15N‰ values represent average values of duplicate runs for each sample. . Samples collected from 1Faunal Collection of the Archaeological Department of the Déri Museum , 2Hungarian Natural History Museum .All samples represent a single individual. Samples were analyzed in duplicate except for those marked with an asterisk. The δ(DOCX)Click here for additional data file.S2 Table13C‰ and δ15N‰ values represent average values of duplicate runs for each sample. Samples that do not meet the quality range (C:N = 2.9–3.6) are in bold. The upper/lower M1 samples employed here correspond to a root dentine subsample belonging to the very last stage of formation of the tooth, following  and the subsampling method in Beaumont and Montgomery, 2015. Legend: no col. = no collagen; EN = Early Neolithic; MN = Middle Neolithic; LN = Late Neolithic; ECA = Early Copper Age; MCA = Middle Copper Age; LCA = Late Copper Age; EBA = Early Bronze Age; LBA = Late Bronze Age; EIA = Early Iron Age. Infant = 0−2 years.All samples were analyzed in duplicate except for those marked with an asterisk. The δ(DOC)Click here for additional data file.S3 Tablep<0.05.Human and faunal number of samples (N) includes the new samples reported in this study, together with the published data (references in Tables (DOCX)Click here for additional data file.


We find that the nakhlites sample a layered volcanic sequence with at least four discrete eruptive events spanning 93 ± 12 Ma (1416 ± 7 Ma to 1322 ± 10 Ma (2σ)). A non-radiogenic trapped 40Ar/36Ar value of 1511 ± 74 (2σ) provides a precise and robust constraint for the mid-Amazonian Martian atmosphere. Our data show that the nakhlite-source volcano grew at a rate of ca. 0.4–0.7 m Ma−1—three orders of magnitude slower than comparable volcanoes on Earth, and necessitating that Mars was far more volcanically active earlier in its history.Mars hosts the solar system’s largest volcanoes. Although their size and impact crater density indicate continued activity over billions of years, their formation rates are poorly understood. Here we quantify the growth rate of a Martian volcano by  Mars hosts the solar system’s largest volcanoes, but their formation rates remain poorly constrained. Here, the authors have measured the crystallization and ejection ages of meteorites from a Martian volcano and find that its growth rate was much slower than analogous volcanoes on Earth. A small proportion of terrestrial volcanoes are fed by mantle plumes—highly localized upwellings of abnormally hot rock that ascend from deep within the mantle and undergo partial melting at relatively shallow depths2. Mars, on the other hand, has lacked plate tectonics for most of its history4. The static ‘stagnant lid’ of the thick Martian lithosphere has restricted convective heat loss1, leaving mantle plumes as the dominant, but less efficient, mechanism for transferring heat from the planet’s core to its surface5. Tectonic activity continually moves the Earth’s lithospheric plates over mantle plumes, forming age-progressive chains of volcanoes2. Even in cases of the slowest-moving plates, individual plume-derived volcanoes on Earth are only active for a few million years6. Conversely, Martian plume-fed edifices have remained connected to their magma sources for extraordinary lengths of time—in some cases for billions of years8. As a consequence, although morphologically similar to shield volcanoes on Earth, Martian volcanoes have grown to be the largest in the solar system9  of individual plume volcanoes on Earth10  but far lower eruption rates (<10 m Ma−1 and <700 km3 Ma−1)  and eruption rates . Their bulk chemistry is basaltic, with abundant clinopyroxene, less common olivine and a rapidly quenched fine-grained mesostasis comprising feldspar and accessory phases, including chlorapatite and volcanic glassn = 43 to 45 steps) laser step-heating 40Ar/39Ar dating of multiple aliquots (n = 2 to 5) of six nakhlites is applied in conjunction with cosmogenic (38Ar) exposure dating. The cosmogenic exposure dating allows for accurate correction of cosmogenic and chlorine-derived contributions to the bulk isotope measurements and for determination of accurate 40Ar/39Ar age data. The six meteorites analysed span the full range of mineralogical variation observed in the nakhlite group18. The data show that the nakhlites were not all formed during a single cooling event, but instead reveal a protracted volcanic eruption history on Mars.In this study, high-resolution , which is ingrown from the radioactive decay of 40K to 40Ar, and accumulates once the rocks have cooled below the closure temperature for 40Ar diffusion. To calculate accurate 40Ar/39Ar ages (a measure of the decay of 40K to 40Ar) it is necessary to establish the contribution of each argon component to the bulk isotope budget of each meteorite19.The isotope budgets of meteorites are derived from multiple sources. Martian meteorites contain trapped 38Ar and 36Ar produced from chlorine during neutron irradiation, which can lead to inaccurate correction of age data21. The chlorine-derived isotopes are a particular issue for the nakhlite group of Martian meteorites, which can contain over 1000 ppm Cl hosted in salts and/or chlorine-bearing apatite that can be found in the meteorite's mesostasis  and Yamato 000593 defines a trapped 40Ar/36Ar ratio of 1560 ± 110  that overlap within two-sigma analytical uncertainty. As 24 separate analyses from two different aliquots overlap within analytical uncertainty, we conservatively interpret these data to represent a minimum eruption age for NWA 5790.After the above contributions from cosmogenic and atmospheric argon were accounted for, the tra Fig. . Plateaup”) values of greater than 0.05 (95% confidence), indicating the analyses are statistically robust24.The eruption age for each meteorite was calculated as a weighted-mean of all plateau steps. Analytical uncertainties were calculated as the standard error of the mean, but if the mean square weighted deviates (MSWD or reduced chi-squared statistic) was greater than one, the analytical uncertainty was inflated by multiplying the standard error of the mean by the square-root of the MSWD. All samples analysed in this study (including NWA 5790) have plateau and weighted-mean ages with MSWD of less than two, and probability of fit . The highly reproducible age data are consistent with the near-pristine character of the meteorites and associated low degrees of shock metamorphism17. The experimental design25 also facilitated resolution of the different argon reservoirs in each meteorite 26 and Yamato 000593 (40Ar/36Ar = 1502 ± 159)27, as well as Chassigny (40Ar/36Ar = 1452 ± 168)27 are commensurate with our analyses , and therefore the common trapped component likely reflects the isotopic composition of the Martian atmosphere at that time. The weighted average of these measurements is 1511 ± 74 (2σ) for the 40Ar/36Ar trapped component—the most precise constraint yet obtained for the mid-Amazonian atmosphere of Mars. This value is more precise than, but within analytical uncertainty of, measurements by the Curiosity rover for the present-day Martian atmosphere 29. It is, however, distinct from the paleo-atmospheric 40Ar/36Ar recorded by the shergottite meteorites (40Ar/36Ar of 1800 ± 100)30, which yield 40Ar/39Ar cooling ages of ca. 180–600 Ma21. Together, these data therefore suggest that the atmospheric 40Ar/36Ar of Mars has increased significantly (Δ 40Ar/36Ar of 300 ± 130) over the last 1300 Ma. The 40Ar/36Ar value of Earth’s atmosphere has likewise increased over time31, and reflects degassing of radiogenic 40Ar from the interior. In the case of Mars, the change in 40Ar/36Ar also provides constraints on atmospheric loss through time32.The trapped components previously measured in the nakhlites MIL 03346 , a period spanning 93 ± 12 Ma . This age difference is incompatible with the hypothesis that these were fall-paired stones38 . Despite being found in the same Antarctic field season, there is, however, no a priori scientific reason for why these stones should be fall-paired, particularly when considering that the Yamato meteorite stranding surface is the largest in Antarctica, covering an area of 4000 km2, and that the glaciers which feed into the stranding area extend for a further 500 km upstream39. Yamato 000593 and Yamato 000749 could therefore have fallen anywhere in the catchment area, only to be brought to a similar part of the ice field by the action of Antarctic glaciers.We also note that the two Yamato meteorites have 40Ar/39Ar and cosmogenic exposure ages inform about the provenance of the nakhlites on the surface of Mars, including their ejection crater, and properties of their source volcano. More than seven different Martian craters have been suggested as potential sources for the nakhlites42. However, when we use the recent re-mapping of the Martian surface by NASA43, we find that only one of these craters is situated in a mid-Amazonian volcanic terrain compatible with our 40Ar/39Ar results  obtained for the nakhlites 10.If the nakhlite samples analysed span the full spallation depth (near-surface to 40–66 m), then considering the time taken to accumulate the lava sequence (93 ± 12 Ma), approximately 0.4–0.7 m of lava was extruded every 1 Ma. If the nakhlites analysed do not span the full spallation depth, this rate represents an upper bound, whereas if the source crater is located on the volcano flank, or on lava plains, then the calculated rate represents a lower bound, as eruptions are likely to be more voluminous and frequent closer to the centre of an edifice. In all scenarios, the growth rate is three orders of magnitude lower than is observed for a terrestrial plume-derived volcano . Therefore, the eruption rate must have been greater prior to the mid-Amazonian. Both crater counting and planetary heat-flow models support this conclusion, as they demonstrate that the rate of volcanism during the Noachian and Hesperian (4500–3000 Ma) was at least 2–10 times greater than in the Amazonian (<3000 Ma)7. Our data compare favourably with remote-sensing crater-counting studies of Martian volcanoes47, which indicate that volcanism occurred at much lower rates in the recent past, compared to early in the planet’s history. For example, over the last 300 Ma the maximum effusion rate at the Arisa Mons volcano47 was between 1 and 8 km3 Ma−1—well below the eruption rate of 270 km3 Ma−1 averaged over the 3400 Ma duration of the volcano 48 and secondary standard GA1550 (standard age of 99.738 ± 0.104 Ma (1σ)48. Samples were then irradiated for 80 h in the Cd-lined TRIGA facility, Oregon State University, USA. After a decay period of 5–9 months, analyses of neutron flux monitors and meteorite samples were undertaken on an MAP 215-50 spectrometer operated in peak-hopping mode, with measured sensitivity of 1.13 × 10−13 mol V−1. Hb3gr crystals were analysed via total-fusion, while meteorite samples were incrementally heated using a using a defocused CO2 laser. The released gases were purified using two SAES GP50 getters with ST101 Zr-Al cartridges, one at room temperature (0 V) and the other at ~ 450 °C (2 V). Isotope extraction, purification, extraction line operation and mass spectrometry were fully automated. Data were corrected for background measurements, mass discrimination and radioactive decay since irradiation using MassSpec software version 8.131. Values used in the 40Ar/39Ar data regression are listed in Supplementary Table Samples were prepared at the NERC Argon Isotope Facility, Scottish Universities Environmental Research Centre (SUERC). The meteorites were first gently crushed in an agate mortar and pestle to liberate mineral phases, which were then washed in distilled water to remove dust. Hand-picked chips of groundmass were then wrapped in Cu-foil packets, and loaded in two irradiation vials along with neutron-fluence monitor Hb3gr (standard age of 1081.0 ± 1.2 Ma (1λ = 810 ± 10 nm)21. The released argon was purified using four SAES getters (one hot and three cold) and analysed using a Nu Instruments Noblesse mass spectrometer. Samples were analysed statically in peak hopping mode using the axial multiplier detector. Sample analyses were bracketed by analyses of a spike of known abundance and isotopic composition to monitor for time-dependent changes in spectrometer sensitivity and mass discrimination.These analyses were performed on unirradiated aliquots, and were measured both at SUERC and Lawrence Livermore National Laboratory (LLNL). Gas extractions at SUERC followed the procedure described above. At LLNL, whole-rock fragments of Nakhla and Lafayette were loaded into small metal packets made from high-purity Pt–Ir tubes and heated with a 75 W diode laser  at LLNL 51 and the trapped component is derived from the Martian atmosphere (38Ar/36Ar = 0.244)52.Cosmogenic exposure ages were calculated from elemental production rates40Ar/39Ar ages across the group .Supplementary InformationSupplementary Data 1