Fourteen sequence variants that associate with multiple sclerosis discovered by meta-analysis informed by genetic correlations

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesA meta-analysis of publicly available summary statistics on multiple sclerosis combined with three Nordic multiple sclerosis cohorts (21,079 cases, 371,198 controls) revealed seven sequence variants associating with multiple sclerosis, not reported previously. Using polygenic risk scores based on public summary statistics of variants outside the major histocompatibility complex region we quantified genetic overlap between common autoimmune diseases in Icelanders and identified disease clusters characterized by autoantibody presence/absence. As multiple sclerosis-polygenic risk scores captures the risk of primary biliary cirrhosis and vice versa (P = 1.6 x 10(-7), 4.3 x 10(-9)) we used primary biliary cirrhosis as a proxy-phenotype for multiple sclerosis, the idea being that variants conferring risk of primary biliary cirrhosis have a prior probability of conferring risk of multiple sclerosis. We tested 255 variants forming the primary biliary cirrhosis-polygenic risk score and found seven multiple sclerosis-associating variants not correlated with any previously established multiple sclerosis variants. Most of the variants discovered are close to or within immune-related genes. One is a low-frequency missense variant in TYK2, another is a missense variant in MTHFR that reduces the function of the encoded enzyme affecting methionine metabolism, reported to be dysregulated in multiple sclerosis brain.Swedish Research Council Knut and Alice Wallenberg Foundation AFA Foundation Swedish Brain Foundatio

Magnetic MAX phases from theory and experiments: a review

This review presents MAX phases (M is a transition metal, A an A-group element, X is C or N), known for their unique combination of ceramic/metallic properties, as a recently uncovered family of novel magnetic nanolaminates. The first created magnetic MAX phases were predicted through evaluation of phase stability using density functional theory, and subsequently synthesized as heteroepitaxial thin films. All magnetic MAX phases reported to date, in bulk or thin film form, are based on Cr and/or Mn, and they include (Cr,Mn)(2)AlC, (Cr,Mn)(2)GeC, (Cr,Mn)(2)GaC, (Mo,Mn)(2)GaC, (V,Mn)(3)GaC2, Cr2AlC, Cr2GeC and Mn2GaC. A variety of magnetic properties have been found, such as ferromagnetic response well above room temperature and structural changes linked to magnetic anisotropy. In this paper, theoretical as well as experimental work performed on these materials to date is critically reviewed, in terms of methods used, results acquired, and conclusions drawn. Open questions concerning magnetic characteristics are discussed, and an outlook focused on new materials, superstructures, property tailoring and further synthesis and characterization is presented.Funding Agencies|European Research Council (ERC); Swedish Research Council (VR) [621-2012-4425, 642-2013-8020]; KAW foundation; Swedish Foundation for Strategic Research (SSF) through the synergy grant FUNCASE</p

Toward Structural Optimization of MAX Phases as Epitaxial Thin Films

Prompted by the increased focus on MAX phase materials and their two-dimensional counterparts MXenes, a brief review of the current state of affairs in the synthesis of MAX phases as epitaxial thin films is given. Current methods for synthesis are discussed and suggestions are given on how to increase the material quality even further as well as arrive at those conditions faster. Samples were prepared to exemplify the most common issues involved with the synthesis, and through suggested paths for resolving these issues we attain samples of a quality beyond what has previously been reported.Funding Agencies|European Research Council under the European Community Seventh Framework Program (FP7)/ERC Grant [258509]; Swedish Research Council (VR); Knut and Alice Wallenberg (KAW) Fellowship program; SSF synergy grant FUNCASE</p

Mn3GaC inverse perovskite thin films by magnetron sputtering from elemental targets

We have deposited epitaxial thin films of the inverse perovskite Mn3GaC using magnetron sputtering from elemental targets. Two substrates were used, MgO (111) and (100), resulting in corresponding orientation of the Mn3GaC thin films. Both samples displayed magnetic properties consistent with an AFM to FM transition at similar to 170 K and a Curie temperature around 265 K, evaluated with vibrating sample magnetometry (in-plane measurements). These two ground states are further supported by first principles calculations. Based on that the two orientations of Mn3GaC display very similar magnetic properties, it can be concluded that shape anisotropy dominates over the materials easy axis.Funding Agencies|Knut and Alice Wallenberg (KAW) FoundationKnut &amp; Alice Wallenberg Foundation [KAW 2015.0043]; Swedish Research councilSwedish Research Council [642-2013-8020]</p

Long-range antiferromagnetic order in epitaxial Mn2GaC thin films from neutron reflectometry

The nature of the magnetic structure in magnetic so-called MAX phases is a topic of some controversy. Here we present unpolarized neutron-diffraction data between 3.4 and 290.0 K and momentum transfer between Q = 0.0 and 1.1 angstrom(-1), as well as complementary x-ray-diffraction data on epitaxial thin films of the MAX phase material Mn2GaC. This inherently layered material exhibits neutron-diffraction peaks consistent with long-ranged antiferromagnetic order with a periodicity of two structural unit cells. The magnetic structure is present throughout the measured temperature range. The results are in agreement with first-principles calculations of antiferromagnetic structures for this material where the Mn-C-Mn atomic trilayers are found to be ferromagnetically coupled internally but spin flipped or rotated across the Ga layers. The present findings have significant bearing on the discussion regarding the nature of the magnetic structure in magnetic MAX phases.Funding Agencies|European Research Council (ERC) under the European Communitys Seventh Framework Programme FP7 (ERC Grant) [258509]; Swedish Research Council [621-2012-4425]; Knut and Alice Wallenberg Foundation program</p

Formation of RuO(OH)(2) on RuO2-Based Electrodes for Hydrogen Production

The catalytic and durable electrode coating of ruthenium dioxide (RuO2), applied on nickel (Ni) substrates, is today utilized as electrocatalytic cathodes for hydrogen production, e.g., in the chlor-alkali process and alkaline water electrolysis. The drawback is, however, the sensitivity to reverse currents obtained during power shutdowns, e.g., at maintenance, where the RuO2-based electrodes can be severely damaged unless polarization rectifiers are employed. Through the material characterization techniques X-ray diffraction and X-ray photoelectron spectroscopy, we can now reveal that RuO2 coatings, when exposed to hydrogen evolution at industrially relevant conditions, transforms into ruthenium oxyhydroxide (RuO(OH)(2)). The study further shows that as the hydrogen evolution proceeds the formed RuO(OH)(2) reduces to metallic ruthenium (Ru)

Corrosion of ruthenium dioxide based cathodes in alkaline medium caused by reverse currents

A reverse current obtained during power shutdowns in industrial processes, such as chlor-alkali production or alkaline water electrolysis, is deleterious for hydrogen evolving ruthenium dioxide (Ru02) based cathodes. It has been observed that RuO2 coatings after a power shutdown, necessary for e.g. maintenance, are severely damaged unless polarization rectifiers are employed. In this work we show why these types of cathodes are sensitive to reverse currents, i.e. anodic currents, after hydrogen evolution. RuO2 coatings deposited on nickel substrates were subjected to different electrochemical treatments such as hydrogen evolution, oxygen evolution, or reverse currents in 8 M NaOH at 90 degrees C. Polarity inversion was introduced after hydrogen evolution to simulate the effect of reverse currents. Because of chemical interaction with hydrogen, a significant amount of the RuO2 coating was transformed into hydroxylated species during cathodic polarization. Our study shows that these hydroxylated phases are highly sensitive to electrochemical corrosion during anodic polarization after extended hydrogen evolution.Funding Agencies|Swedish Research Council [2007-5059]; European Research Council under the European Communities/ERC [258509]; Swedish Research Council (VR) [642-2013-8020]; KAW Fellowship program</p

Effect of Ti-Al cathode composition on plasma generation and plasma transport in direct current vacuum arc

DC arc plasma from Ti, Al, and Ti1-xAlx (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes was characterized with respect to plasma chemistry and charge-state-resolved ion energy. Scanning electron microscopy, X-ray diffraction, and Energy-dispersive X-ray spectroscopy of the deposited films and the cathode surfaces were used for exploring the correlation between cathode-, plasma-, and film composition. Experimental work was performed at a base pressure of 10(-6) Torr, to exclude plasma-gas interaction. The plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. This may be explained by presence of neutrals in the plasma/vapour phase. The average ion charge states (Ti = 2.2, Al = 1.65) were consistent with reference data for elemental cathodes, and approximately independent on the cathode composition. On the contrary, the width of the ion energy distributions (IEDs) were drastically reduced when comparing the elemental Ti and Al cathodes with Ti0.5Al0.5, going from similar to 150 and similar to 175 eV to similar to 100 and similar to 75 eV for Ti and Al ions, respectively. This may be explained by a reduction in electron temperature, commonly associated with the high energy tail of the IED. The average Ti and Al ion energies ranged between similar to 50 and similar to 61 eV, and similar to 30 and similar to 50 eV, respectively, for different cathode compositions. The attained energy trends were explained by the velocity rule for compound cathodes, which states that the most likely velocities of ions of different mass are equal. Hence, compared to elemental cathodes, the faster Al ions will be decelerated, and the slower Ti ions will be accelerated when originating from compound cathodes. The intensity of the macroparticle generation and thickness of the deposited films were also found to be dependent on the cathode composition. The presented results may be of importance for choice of cathodes for thin film depositions involving compound cathodes

Synthesis and characterization of magnetic (Cr0.5Mn0.5)2GaC thin films

Growth of (Cr0.5Mn0.5)2GaC thin films from C, Ga, and compound Cr0.5Mn0.5 targets is reported for depositions on MgO (111), 4H-SiC (0001), and Al2O3 (0001) with and without a NbN (111) seed layer. Structural quality is found to be highly dependent on the choice of substrate with MgO (111) giving the best results as confirmed by X-ray diffraction and transmission electron microscopy. Phase pure, high crystal quality MAX phase thin films are realized, with a Cr:Mn ratio of 1:1. Vibrating sample magnetometry shows a ferromagnetic component from 30 K up to 300 K, with a measured net magnetic moment of 0.67 μB per metal (Cr + Mn) atom at 30 K and 5 T. The temperature dependence of the magnetic response suggests competing magnetic interactions with a resulting non-collinear magnetic ordering.At the time for thesis presentation publication was in status: ManuscriptFunding Agencies|European Research Council under the European Community [258509]; Swedish Research Council (VR) [642-2013-8020, 621-2012-4425]; KAW Fellowship program; SSF synergy grant FUNCASE; Icelandic University Research fund</p