A supercurrent on the proximitized surface of a topological insulator can cause a delocalization transition of a Majorana fermion bound to a vortex core as a zero mode. Here we study the dynamics of the deconfinement, as a manifestation of the Magnus effect (the coupling of the superflow to the velocity field in the vortex). The initial acceleration of the Majorana fermion is ±2v2FK/ℏ, perpendicular to the Cooper pair momentum K, for a ±2π winding of the superconducting phase around the vortex. The quasiparticle escapes with a constant velocity from the vortex core, which we calculate in a semiclassical approximation and compare with computer simulations.
Weniger anzeigenBackground: Therapeutic options for migraine prevention in non-responders to monoclonal antibodies (mAbs) targeting Calcitonin Gene-Related Peptide (CGRP) and its receptor are often limited. Real-world data have shown that non-responders to the CGRP-receptor mAb erenumab may benefit from switching to a CGRP ligand mAb. However, it remains unclear whether, vice versa, erenumab is effective in non-responders to CGRP ligand mAbs. In this study, we aim to assess the efficacy of erenumab in patients who have previously failed a CGRP ligand mAb.
Methods: This monocentric retrospective cohort study included patients with episodic or chronic migraine in whom a non-response (< 30% reduction of monthly headache days during month 3 of treatment compared to baseline) to the CGRP ligand mAbs galcanezumab or fremanezumab led to a switch to erenumab, and who had received at least 3 administrations of erenumab. Monthly headache days were retrieved from headache diaries to assess the >= 30% responder rates and the absolute reduction of monthly headache days at 3 and 6 months of treatment with erenumab in this cohort.
Results: From May 2019 to July 2022, we identified 20 patients who completed 3 months of treatment with erenumab after non-response to a CGRP ligand mAb. Fourteen patients continued treatment for >= 6 months. The >= 30% responder rate was 35% at 3 months, and 45% at 6 months of treatment with erenumab, respectively. Monthly headache days were reduced from 18.6 +/- 5.9 during baseline by 4.1 +/- 3.1 days during month 3, and by 7.0 +/- 4.8 days during month 6 compared to the month before treatment with erenumab (p < 0.001, respectively). Responders and non-responders to erenumab did not differ with respect to demographic or headache characteristics.
Conclusion: Switching to erenumab in non-responders to a CGRP ligand mAb might be beneficial in a subgroup of resistant patients, with increasing responder rates after 6 months of treatment. Larger prospective studies should aim to predict which subgroup of patients benefit from a switch.
Weniger anzeigenMethods to discretize the Hamiltonian of a topological insulator or topological superconductor, without giving up on the topological protection of the massless excitations (respectively, Dirac fermions or Majorana fermions) are reviewed. The method of tangent fermions, pioneered by Richard Stacey, is singled out as being uniquely suited for this purpose. Tangent fermions propagate on a 2+1-dimensional space-time lattice with a tangent dispersion: in dimensionless units. They avoid the fermion doubling lattice artefact that will spoil the topological protection, while preserving the fundamental symmetries of the Dirac Hamiltonian. Although the discretized Hamiltonian is nonlocal, as required by the fermion-doubling no-go theorem, it is possible to transform the wave equation into a generalized eigenproblem that is local in space and time. Applications that are discussed include Klein tunneling of Dirac fermions through a potential barrier, the absence of localization by disorder, the anomalous quantum Hall effect in a magnetic field, and the thermal metal of Majorana fermions.
Weniger anzeigenThis study evaluated the reliability and comprehensiveness of the Unified classification system (UCPF), Wright & Cofield, Worland and Kirchhoff classifications and related treatment recommendations for periprosthetic shoulder fractures (PPSFx). Two shoulder arthroplasty specialists (experts) and two orthopaedic residents (non-experts) assessed 20 humeral-sided and five scapula-sided cases of PPSFx. We used the unweighted Cohen's Kappa (?) for measuring the intra-observer reliability and Krippendorff's alpha (a) for measuring the inter-observer reliability. The inter-rater reliabilities for the Wright & Cofield and Worland classifications were substantial for all groups. The expert and non-expert groups for UCPF also showed substantial inter-rater agreement. The all-rater group for the UCPF and the expert and non-expert group for the Kirchhoff classification revealed moderate inter-rater reliability. For the Kirchhoff classification, only fair inter-rater reliability was found for the non-expert group. Almost perfect intra-rater reliability was measured for all groups of the Wright & Cofield classification and the all-rater and expert groups of the UCPF. All groups of the Kirchhoff and Worland classifications and the group of non-experts for the UCPF had substantial intra-rater reliabilities. Regarding treatment recommendations, substantial inter-rater and moderate intra-rater reliabilities were found. Simple classification systems for PPSFx (Wright & Cofield, Worland) show the highest inter- and intra-observer reliability but lack comprehensiveness as they fail to describe scapula-sided fractures. The complex Kirchhoff classification shows limited reliability. The UCPF seems to offer an acceptable combination of comprehensiveness and reliability.
Weniger anzeigenIntroduction: Since cannabinoids were partially legalized as prescription medicines in Germany in 2017, they are mostly used when conventional therapies do not suffice. Ambiguities remain regarding use, benefits and risks. This web-based survey explored the perspectives of patients whose experiences are not well enough known to date.
Methods: In an anonymous, exploratory, cross-sectional, one-time web-based observational study, participants receiving cannabinoid therapy on prescription documented aspects of their medical history, diagnoses, attitudes toward cannabinoids, physical symptoms, and emotional states. Participants completed the questionnaires twice here: first regarding the time of the survey and then, retrospectively, for the time before their cannabinoid therapy. Participants were recruited in a stratified manner in three German federal states.
Results: N = 216 participants (48.1% female, aged 51.8 +/- 14.0) completed the survey, most of which (72%, n = 155) reported pain as their main reason for cannabinoid therapy. When comparing the current state with the retrospectively assessed state, participants reported greater satisfaction with their overall medical therapy (TSQM II: +47.9 +/- 36.5, p < 0.001); improved well-being (WHO-5: +7.8 +/- 5.9, p < 0.001) and fewer problems in PROMIS subscales (all p < 0.001). Patients suffering primarily from pain (72%, n = 155) reported a reduction of daily pain (NRS: -3.2 +/- 2.0, p < 0.001), while participants suffering mainly from spasticity (8%, n = 17) stated decreased muscle spasticity (MSSS: -1.5 +/- 0.6, p < 0.001) and better physical mobility (-0.8 +/- 0.8, p < 0.001). Data suggests clinically relevant effects for most scores. Participants' attitudes toward cannabinoids (on a 5-point scale) improved (+1.1 +/- 1.1, p < 0.001). Most patients (n = 146, 69%) did not report major difficulties with the cannabinoid prescription process, while (n = 27; 19%) had their cannabinoid therapy changed due to side effects.
Discussion: Most participants experienced their therapy with cannabinoids as more effective than their previous therapy. There are extensive limitations to this cross-sectional study: the originally intended representativeness of the dataset was not reached, partly due to the SARS-CoV-2 pandemic; the sample has a larger proportion of privately insured and self-paying patients. Results does not suggest that cannabinoid patients belong to a particular clientele. Effect sizes observed for pain reduction, quality of life, social participation, and other outcomes suggest a therapeutic potential, particularly in the treatment of chronic pain.
Weniger anzeigenIntroduction: Chronic pain is a growing worldwide health problem and complementary and integrative therapy options are becoming increasingly important. Multi-component yoga interventions represent such an integrative therapy approach with a promising body of evidence. Methods: The present study employed an experimental single-case multiple-baseline design. It investigated the effects of an 8-week yoga-based mind-body intervention, Meditation-Based Lifestyle Modification (MBLM), in the treatment of chronic pain. The main outcomes were pain intensity (BPI-sf), quality of life (WHO-5), and pain self-efficacy (PSEQ). Results: Twenty-two patients with chronic pain (back pain, fibromyalgia, or migraines) participated in the study and 17 women completed the intervention. MBLM proved to be an effective intervention for a large proportion of the participants. The largest effects were found for pain self-efficacy (TAU-U = 0.35), followed by average pain intensity (TAU-U = 0.21), quality of life (TAU-U = 0.23), and most severe pain (TAU-U = 0.14). However, the participants varied in their responses to the treatment. Conclusion: The present results point to relevant clinical effects of MBLM for the multifactorial conditions of chronic pain. Future controlled clinical studies should investigate its usefulness and safety with larger samples. The ethical and philosophical aspects of yoga should be further explored to verify their therapeutic utility.
Weniger anzeigenIntroduction: Neoadjuvant stereotactic radiosurgery (NaSRS) of brain metastases has gained importance, but it is not routinely performed. While awaiting the results of prospective studies, we aimed to analyze the changes in the volume of brain metastases irradiated pre- and postoperatively and the resulting dosimetric effects on normal brain tissue (NBT).
Methods: We identified patients treated with SRS at our institution to compare hypothetical preoperative gross tumor and planning target volumes (pre-GTV and pre-PTV) with original postoperative resection cavity volumes (post-GTV and post-PTV) as well as with a standardized-hypothetical PTV with 2.0 mm margin. We used Pearson correlation to assess the association between the GTV and PTV changes with the pre-GTV. A multiple linear regression analysis was established to predict the GTV change. Hypothetical planning for the selected cases was created to assess the volume effect on the NBT exposure. We performed a literature review on NaSRS and searched for ongoing prospective trials.
Results: We included 30 patients in the analysis. The pre-/post-GTV and pre-/post-PTV did not differ significantly. We observed a negative correlation between pre-GTV and GTV-change, which was also a predictor of volume change in the regression analysis, in terms of a larger volume change for a smaller pre-GTV. In total, 62.5% of cases with an enlargement greater than 5.0 cm(3) were smaller tumors (pre-GTV < 15.0 cm(3)), whereas larger tumors greater than 25.0 cm(3) showed only a decrease in post-GTV. Hypothetical planning for the selected cases to evaluate the volume effect resulted in a median NBT exposure of only 67.6% (range: 33.2-84.5%) relative to the dose received by the NBT in the postoperative SRS setting. Nine published studies and twenty ongoing studies are listed as an overview.
Conclusion: Patients with smaller brain metastases may have a higher risk of volume increase when irradiated postoperatively. Target volume delineation is of great importance because the PTV directly affects the exposure of NBT, but it is a challenge when contouring resection cavities. Further studies should identify patients at risk of relevant volume increase to be preferably treated with NaSRS in routine practice. Ongoing clinical trials will evaluate additional benefits of NaSRS.
Weniger anzeigenChronic granulomatous disease is an inborn error of immunity due to disrupted function of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. This results in impaired respiratory burst of phagocytes and insufficient killing of bacteria and fungi. Patients with chronic granulomatous disease are at increased risk for infections, autoinflammation and autoimmunity. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only widely available curative therapy. While HSCT from human leukocyte antigen (HLA) matched siblings or unrelated donors are standard of care, transplantation from HLA-haploidentical donors or gene therapy are considered alternative options. We describe a 14-month-old male with X-linked chronic granulomatous disease who underwent a paternal HLA-haploidentical HSCT using T-cell receptor (TCR) alpha/beta(+)/CD19(+) depleted peripheral blood stem cells followed by mycophenolate graft versus host disease prophylaxis. Decreasing donor fraction of CD3(+) T cells was overcome by repeated infusions of donor lymphocytes from the paternal HLA-haploidentical donor. The patient achieved normalized respiratory burst and full donor chimerism. He remained disease-free off any antibiotic prophylaxis for more than three years after HLA-haploidentical HSCT. In patients with x-linked chronic granulomatous disease without a matched donor paternal HLA-haploidentical HSCT is a treatment option worth to consider. Administration of donor lymphocytes can prevent imminent graft failure.
Weniger anzeigenIn lateralized oral squamous cell carcinoma (OSCC) with ipsilateral cervical lymph node metastasis (CLNM), the surgical management of the unsuspicious contralateral neck remains a matter of debate. The aim of this study was to analyze this cohort and to compare the outcomes of patients with and without contralateral elective neck dissection (END). Material and Methods: A retrospective analysis of patients with lateralized OSCC, ipsilateral CLNM (pN+) and contralateral cN0-stage was performed. Patients were divided into two groups according to the surgical management of the contralateral neck: I: END; and II: no END performed. Adjuvant radiotherapy was applied bilaterally in both groups according to individual risk. Results: A total of 65 patients (group I: 16 (24.6%); group II: 49 (75.4%)) with a median follow-up of 28 months were included. Initially, there was no case of contralateral CLNM after surgery. During follow-up, 6 (9.2%) patients presented with recurrent CLNM. In 5 of these cases (7.7%), the contralateral neck (group I: 3/16 (18.8%); group II: 2/49 (4.1%)) was affected. Increased ipsilateral lymph node ratio was associated with contralateral CLNM (p = 0.07). END of the contralateral side showed no significant benefit regarding OS (p = 0.59) and RFS (p = 0.19). Conclusions: Overall, the risk for occult contralateral CLNM in patients with lateralized OSCC ipsilateral CLNM is low. Our data suggest that END should not be performed routinely in this cohort. Risk-adapted radiotherapy of the contralateral neck alone seems to be sufficient from the oncological point of view.
Weniger anzeigenThe chiral edge modes of a topological superconductor can transport fermionic quasiparticles with Abelian exchange statistics, but they can also transport non-Abelian anyons: edge vortices bound to a π-phase domain wall that propagates along the boundary. A pair of such edge vortices is injected by the application of an h/2e flux bias over a Josephson junction. Existing descriptions of the injection process rely on the instantaneous scattering approximation of the adiabatic regime [Beenakker et al., Phys. Rev. Lett. 122, 146803 (2019)], where the internal dynamics of the Josephson junction is ignored. Here, we go beyond that approximation in a time-dependent many-body simulation of the injection process, followed by a braiding of mobile edge vortices with a pair of immobile Abrikosov vortices in the bulk of the superconductor. Our simulation sheds light on the properties of the Josephson junction needed for a successful implementation of a flying topological qubit.
Weniger anzeigenWe investigate magnetotransport across an interface between two Weyl semimetals whose Weyl nodes project onto different interface momenta. Such an interface generically hosts Fermi arcs that connect Weyl nodes of identical chirality in different Weyl semimetals (homochiral connectivity)—in contrast to surface Fermi arcs that connect opposite-chirality Weyl nodes within the same Weyl semimetal (heterochiral connectivity). We show that electron transport along homochiral-connectivity Fermi arcs, in the presence of a longitudinal magnetic field, results in a universal longitudinal magnetoconductance of e2/h per magnetic flux quantum. Furthermore, a weak tunnel coupling can result in a close encounter of two homochiral-connectivity Fermi arcs, enabling magnetic breakdown. Above the breakdown field the interface Fermi arc connectivity is effectively heterochiral, leading to a saturation of the conductance.
Weniger anzeigenIntroduction: Bloodwork is a widely used diagnostic tool in veterinary medicine, as diagnosis and therapeutic interventions often rely on blood biomarkers. However, biomarkers available in veterinary medicine often lack sensitivity or specificity. Mass spectrometry-based proteomics technology has been extensively used in the analysis of biological fluids. It offers excellent potential for a more comprehensive characterization of the plasma proteome in veterinary medicine.
Methods: In this study, we aimed to identify and quantify plasma proteins in a cohort of healthy dogs and compare two techniques for depleting high-abundance plasma proteins to enable the detection of lower-abundance proteins via label-free quantification liquid chromatography-mass spectrometry. We utilized surplus lithium-heparin plasma from 30 healthy dogs, subdivided into five groups of pooled plasma from 6 randomly selected individuals each. Firstly, we used a commercial kit to deplete high-abundance plasma proteins. Secondly, we employed an in-house method to remove albumin using Blue-Sepharose.
Results and discussion: Among all the samples, some of the most abundant proteins identified were apolipoprotein A and B, albumin, alpha-2-macroglobulin, fibrinogen beta chain, fibronectin, complement C3, serotransferrin, and coagulation factor V. However, neither of the depletion techniques achieved significant depletion of highly abundant proteins. Despite this limitation, we could detect and quantify many clinically relevant proteins. Determining the healthy canine proteome is a crucial first step in establishing a reference proteome for canine plasma. After enrichment, this reference proteome can later be utilized to identify protein markers associated with different diseases, thereby contributing to the diagnosis and prognosis of various pathologies.
Weniger anzeigenThree-dimensional higher-order topological insulators can have topologically protected chiral modes propagating on their hinges. Hinges with two copropagating chiral modes can serve as a “beam splitter” between hinges with only a single chiral mode. Here we show how such a crystal, with Ohmic contacts attached to its hinges, can be used to realize a Mach-Zehnder interferometer. We present concrete calculations for a lattice model of a first-order topological insulator in a magnetic field, which, for a suitable choice of parameters, is an extrinsic second-order topological insulator with the required configuration of chiral hinge modes.
Weniger anzeigenAims: Heart failure (HF) does not only reduce the life expectancy in patients, but their life is also often limited by HF symptoms leading to a reduced quality of life (QoL) and a diminished exercise capacity. Novel parameters in cardiac imaging, including both global and regional myocardial strain imaging, promise to contribute to better patient characterization and ultimately to better patient management. However, many of these methods are not part of clinical routine yet, their associations with clinical parameters have been poorly studied. An imaging parameters that also indicate the clinical symptom burden of HF patients would make cardiac imaging more robust toward incomplete clinical information and support the clinical decision process.
Methods and results: This prospective study conducted at two centers in Germany between 2017 and 2018 enrolled stable outpatient subjects with HF [n = 56, including HF with reduced ejection fraction (HFrEF), HF with mid-range ejection fraction (HFmrEF), and HF with preserved ejection fraction (HFpEF)] and a control cohort (n = 19). Parameters assessed included measures for external myocardial function, for example, cardiac index and myocardial deformation measurements by cardiovascular magnetic resonance imaging, left ventricular global longitudinal strain (GLS), the global circumferential strain (GCS), and the regional distribution of segment deformation within the LV myocardium, as well as basic phenotypical characteristics including the Minnesota Living with Heart Failure Questionnaire (MLHFQ) and the 6-minute walk test (6MWT). If less than 80% of the LV segments are preserved in their deformation capacity the functional capacity by 6MWT (6 minutes walking distance: MyoHealth >= 80%: 579.8 +/- 177.6 m; MyoHealth 60-<80%: 401.3 +/- 121.7 m; MyoHealth 40-<60%: 456.4 +/- 68.9 m; MyoHealth < 40%: 397.6 +/- 125.9 m, overall p-value: 0.03) as well as the symptom burden are significantly impaired (NYHA class: MyoHealth >= 80%: 0.6 +/- 1.1 m; MyoHealth 60-p-value < 0.01). Differences were also observed in the perceived exertion assessed by on the Borg scale (MyoHealth >= 80%: 8.2 +/- 2.3 m; MyoHealth 60-p-value: 0.20) as well as quality of life measures (MLHFQ; MyoHealth >= 80%: 7.5 +/- 12.4 m; MyoHealth 60-p-value: 0.15)-while these differences were not significant.
Conclusion: The share of LV segments with preserved myocardial contraction promises to discriminate between symptomatic and asymptomatic subjects based on the imaging findings, even when the LV ejection fraction is preserved. This finding is promising to make imaging studies more robust toward incomplete clinical information.
Weniger anzeigenPressure overload hypertrophy of the left ventricle is a common result of many cardiovascular diseases. Androgens show anabolic effects in skeletal muscles, but also in myocardial hypertrophy. We carefully reviewed literature regarding possible effects of androgens on specific left ventricular hypertrophy in pressure overload conditions excluding volume overload conditions or generel sex differences.
This article interrogates the widely held, but rarely defended, view that states wield legitimate power over potential immigrants when and because they refrain from violating their human rights. I reconstruct a strong argument for this view, which turns on a claim about the limited power states claim over migrants. Drawing on recent empirical work, I show how this argument is inapplicable to the border regimes of a set of wealthy democracies. These regimes are characterized by a practice that is coordinated and extraterritorial in a way that undercuts the case for holding them to a minimal legitimacy standard. By participating in this practice, these states wield significant power over potential immigrants. I argue that this power exposes potential immigrants to novel risk, which in turn triggers a demand for the satisfaction of a higher standard of legitimation.
Weniger anzeigenBackground
Early negative life events (NLE) have long-lasting influences on neurodevelopment and psychopathology. Reduced orbitofrontal cortex (OFC) thickness was frequently associated with NLE and depressive symptoms. OFC thinning might mediate the effect of NLE on depressive symptoms, although few longitudinal studies exist. Using a complete longitudinal design with four time points, we examined whether NLE during childhood and early adolescence predict depressive symptoms in young adulthood through accelerated OFC thinning across adolescence.
Methods
We acquired structural MRI from 321 participants at two sites across four time points from ages 14 to 22. We measured NLE with the Life Events Questionnaire at the first time point and depressive symptoms with the Center for Epidemiologic Studies Depression Scale at the fourth time point. Modeling latent growth curves, we tested whether OFC thinning mediates the effect of NLE on depressive symptoms.
Results
A higher burden of NLE, a thicker OFC at the age of 14, and an accelerated OFC thinning across adolescence predicted young adults' depressive symptoms. We did not identify an effect of NLE on OFC thickness nor OFC thickness mediating effects of NLE on depressive symptoms.
Conclusions
Using a complete longitudinal design with four waves, we show that NLE in childhood and early adolescence predict depressive symptoms in the long term. Results indicate that an accelerated OFC thinning may precede depressive symptoms. Assessment of early additionally to acute NLEs and neurodevelopment may be warranted in clinical settings to identify risk factors for depression.
Weniger anzeigen[Fe]-hydrogenase harbors the iron-guanylylpyridinol (FeGP) cofactor, in which the Fe(II) complex contains acyl-carbon, pyridinol-nitrogen, cysteine-thiolate and two CO as ligands. Irradiation with UV-A/blue light decomposes the FeGP cofactor to a 6-carboxymethyl-4-guanylyl-2-pyridone (GP) and other components. Previous in vitro biosynthesis experiments indicated that the acyl- and CO-ligands in the FeGP cofactor can scramble, but whether scrambling occurred during biosynthesis or photolysis was unclear. Here, we demonstrate that the [18O1-carboxy]-group of GP is incorporated into the FeGP cofactor by in vitro biosynthesis. MS/MS analysis of the 18O-labeled FeGP cofactor revealed that the produced [18O1]-acyl group is not exchanged with a CO ligand of the cofactor, indicating that the acyl and CO ligands are scrambled during photolysis rather than biosynthesis, which ruled out any biosynthesis mechanisms allowing acyl/CO ligands scrambling. Time-resolved infrared spectroscopy indicated that an acyl-Fe(CO)3 intermediate is formed during photolysis, in which scrambling of the CO and acyl ligands can occur. This finding also suggests that the light-excited FeGP cofactor has a higher affinity for external CO. These results contribute to our understanding of the biosynthesis and photosensitive properties of this unique H2-activating natural complex.
Weniger anzeigenFamilial cancer burden and genetics play an increasingly important role in the early detection and prevention of gynecological cancers. However, people with hereditary cancer risks are often identified late when they already have cancer. We aimed at developing and evaluating a training concept for primary care gynecologists—iKNOWgynetics—to improve their knowledge and awareness of genetic cancer syndromes and their ability to identify patients with increased familial cancer risks based on up-to-date evidence and current guidelines (in Germany, primary care includes all doctors treating patients on an outpatient basis without a clear separation of the expertise of the doctor or of their specialty). Starting off with a needs assessment among primary care gynecologists, we developed and evaluated an online training concept—using a web-based learning platform in combination with a live virtual seminar—to convey practice-relevant knowledge about familial cancer. After registration, participants get access to the web-based learning platform (www.iknowgynetics.de) to prepare for the virtual seminars and to use it as online reference to re-access the contents after the training. Evaluation included multiple-choice (MC) questions on knowledge and participants' self-efficacy to implement the acquired knowledge, which were administered in a pre-post design. Of 109 participants, 103 (94.5%) filled out pre- and post-questionnaires. Eighty-five participants were gynecologists in primary care from Berlin (81.2%) and Brandenburg (18.8%) and had an average of 24.1 years (SD = 8.5 years) of professional experience. After the training, participants answered significantly more knowledge questions correctly (M = 15.2 of 17, SD = 1.3) than before (M = 13.8 of 17, SD = 1.7) (p < 0.01) and felt more confident to be able to apply referral criteria for specialized counseling in practice (p < 0.001). The online-based training iKNOWgynetics considers the busy schedule of primary care gynecologists and supports them in acquiring practice-relevant information on familial cancer risks and on how to identify healthy persons at risk, which may ultimately help to improve the prevention of gynecological cancers. In future studies, the reported concept could be transferred to other entities.
Weniger anzeigenThe growth, morphology, and structure of MnxAu1-x films on Cu(001) and Ag(001) are studied by means of low-energy electron diffraction (LEED), medium-energy electron diffraction, Auger electron spectroscopy, and scanning tunnelling microscopy. Different concentrations x from about 0.5 to 1 and thicknesses from0.2 to 12.9 ML of MnxAu1-x are examined. For several values of x, MnxAu1-x exhibits a c(2 x 2) superstructure pattern on Cu(001) when the total thickness is around or above 0.5 ML. Above 1 ML, LEED patterns of MnxAu1-x can be only observed on Ag(001), but not on Cu(001). LEED-I(V) is employed to deduce the vertical interlayer distance for as-grown and post-annealed films on Ag(001). Above 500 K, Ag from the substrate segregates into thefilms.
Weniger anzeigen