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Phase coexistence phenomena have been intensively studied in strongly correlated materials where several ordered states simultaneously occur or compete. Material properties critically depend on external parameters and boundary conditions, where tiny changes result in qualitatively different ground states. However, up to date, phase coexistence phenomena have exclusively been reported for complex compounds composed of multiple elements. Here we show that charge- and magnetically ordered states coexist in double-layer Fe/Rh(001). Scanning tunnelling microscopy and spectroscopy measurements reveal periodic charge-order stripes below a temperature of 130 K. Close to liquid helium temperature, they are superimposed by ferromagnetic domains as observed by spin-polarized scanning tunnelling microscopy. Temperature-dependent measurements reveal a pronounced cross-talk between charge and spin order at the ferromagnetic ordering temperature about 70 K, which is successfully modelled within an effective Ginzburg–Landau ansatz including sixth-order terms. Our results show that subtle balance between structural modifications can lead to competing ordering phenomena.
Localized electron spins can couple magnetically via the Ruderman–Kittel–Kasuya–Yosida interaction even if their wave functions lack direct overlap. Theory predicts that spin–orbit scattering leads to a Dzyaloshinskii–Moriya type enhancement of this indirect exchange interaction, giving rise to chiral exchange terms. Here we present a combined spin-polarized scanning tunneling microscopy, angle-resolved photoemission, and density functional theory study of MnO2 chains on Ir(100). Whereas we find antiferromagnetic Mn–Mn coupling along the chain, the inter-chain coupling across the non-magnetic Ir substrate turns out to be chiral with a 120° rotation between adjacent MnO2 chains. Calculations reveal that the Dzyaloshinskii–Moriya interaction results in spin spirals with a periodicity in agreement with experiment. Our findings confirm the existence of indirect chiral magnetic exchange, potentially giving rise to exotic phenomena, such as chiral spin-liquid states in spin ice systems or the emergence of new quasiparticles.
Im Rahmen dieser Arbeit wurden die elektronischen Eigenschaften von Graphen auf Metalloberflächen mittels Rastertunnelmikroskopie und Quasiteilcheninterferenz (englisch quasiparticle interference, QPI)-Messungen untersucht. Durch das Verwenden schwerer Substrate sollte die Spin-Bahn-Wechselwirkung des Graphen verstärkt werden und damit eine Bandlücke am K-Punkt der Bandstruktur mittels QPI beobachtet werden. Um das Messen von QPI auf Graphen zu testen, wurde auf der Oberfläche eines SiC(0001)-Kristalls durch Erhitzen Graphen erzeugt und mit dem Rastertunnelmikroskop untersucht. Dieses System wurde schon ausführlich in der Literatur beschrieben und bereits bekannte QPI-Messungen von Streuringen, die auf den Dirac-Kegeln des Graphen am K-Punkt basieren, konnte ich auf gr/SiC(0001) in guter Qualität erfolgreich reproduzieren. Anschließend wurde Graphen nach einem wohlbekannten Verfahren durch Aufbringen von Ethylen auf ein erhitztes Ir(111)-Substrat erzeugt. Dieses gr/Ir(111)-System diente auch als Grundlage für Interkalationsversuche von Bismut (gr/Bi/Ir(111)) und Gadolinium (gr/Gd/Ir(111)) zwischen das Graphen und das Substrat. Auf gr/Bi/Ir(111) wurde ein schon aus der Literatur bekanntes Netzwerk aus Versetzungslinien beobachtet, dem zusätzlich eine Temperaturabhängigkeit nachgewiesen werden konnte. Beim Versuch, Gadolinium zu interkalieren, wurden zwei verschieden Oberflächenstrukturen beobachtet, die auf eine unterschiedlich Anordnung bzw. Menge des interkalierten Gadoliniums zurückzuführen sein könnten. Auf keinem dieser drei Systeme konnten allerdings Streuringe mittels QPI beobachtet werden. Als Vorbereitung der Interkalation von Gadolinium wurden dessen Wachstum und magnetische Eigenschaften auf einem W(110)-Kristall untersucht. Dabei konnte eine aus der Literatur bekannte temperaturabhängige Austauschaufspaltung reproduziert werden. Darüber hinaus konnten sechs verschieden magnetische Domänen beobachtet werden. Zusätzlich sind auf der Oberfläche magnetische Streifen auszumachen, die möglicherweise auf einer Spinspirale basieren. Als Grundlage für die mögliche zukünftige Erzeugung Graphen-artiger Molekülgitter wurde das Wachstum von H-TBTQ und Me-TBTQ auf Ag(111) untersucht. Die Moleküle richten sich dabei nach der Oberflächenstruktur des Silber aus und bilden längliche Inseln, deren Kanten in drei Vorzugsrichtungen verlaufen. Auf H-TBTQ wurde zudem eine zweite, Windmühlen-artige Ausrichtung der Moleküle auf der Oberfläche beobachtet. Auf den mit den Molekülen bedeckten Stellen der Oberfläche wurde eine Verschiebung des Ag-Oberflächenzustands beobachtet, die mit einem Ladungstransfer vom Ag(111)-Substrat auf die TBTQ-Moleküle zu erklären sein könnte.
Objectives
Vessel wall enhancement (VWE) may be commonly seen on MRI images of asymptomatic subjects. This study aimed to characterize the VWE of the proximal internal carotid (ICA) and vertebral arteries (VA) in a non-vasculitic elderly patient cohort.
Methods
Cranial MRI scans at 3 Tesla were performed in 43 patients (aged ≥ 50 years) with known malignancy for exclusion of cerebral metastases. For vessel wall imaging (VWI), a high-resolution compressed-sensing black-blood 3D T1-weighted fast (turbo) spin echo sequence (T1 CS-SPACE prototype) was applied post gadolinium with an isotropic resolution of 0.55 mm. Bilateral proximal intradural ICA and VA segments were evaluated for presence, morphology, and longitudinal extension of VWE.
Results
Concentric VWE of the proximal intradural ICA was found in 13 (30%) patients, and of the proximal intradural VA in 39 (91%) patients. Mean longitudinal extension of VWE after dural entry was 13 mm in the VA and 2 mm in the ICA. In 14 of 39 patients (36%) with proximal intradural VWE, morphology of VWE was suggestive of the mere presence of vasa vasorum. In 25 patients (64 %), morphology indicated atherosclerotic lesions in addition to vasa vasorum.
Conclusions
Vasa vasorum may account for concentric VWE within the proximal 2 mm of the ICA and 13 mm of the VA after dural entry in elderly subjects. Concentric VWE in these locations should not be confused with large artery vasculitis. Distal to these segments, VWE may be more likely related to pathologic conditions such as vasculitis.
Objective
Blindness is a feared complication of giant cell arteritis (GCA). However, the spectrum of pathologic orbital imaging findings on magnetic resonance imaging (MRI) in GCA is not well understood. In this study, we assess inflammatory changes of intraorbital structures on black blood MRI (BB-MRI) in patients with GCA compared to age-matched controls.
Methods
In this multicenter case-control study, 106 subjects underwent BB-MRI. Fifty-six patients with clinically or histologically diagnosed GCA and 50 age-matched controls without clinical or laboratory evidence of vasculitis were included. All individuals were imaged on a 3-T MR scanner with a post-contrast compressed-sensing (CS) T1-weighted sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) BB-MRI sequence. Imaging results were correlated with available clinical symptoms.
Results
Eighteen of 56 GCA patients (32%) showed inflammatory changes of at least one of the intraorbital structures. The most common finding was enhancement of at least one of the optic nerve sheaths (N = 13, 72%). Vessel wall enhancement of the ophthalmic artery was unilateral in 8 and bilateral in 3 patients. Enhancement of the optic nerve was observed in one patient. There was no significant correlation between imaging features of inflammation and clinically reported orbital symptoms (p = 0.10). None of the age-matched control patients showed any inflammatory changes of intraorbital structures.
Conclusions
BB-MRI revealed inflammatory findings in the orbits in up to 32% of patients with GCA. Optic nerve sheath enhancement was the most common intraorbital inflammatory change on BB-MRI. MRI findings were independent of clinically reported orbital symptoms.
Key Points
• Up to 32% of GCA patients shows signs of inflammation of intraorbital structures on BB-MRI.
• Enhancement of the optic nerve sheath is the most common intraorbital finding in GCA patients on BB-MRI.
• Features of inflammation of intraorbital structures are independent of clinically reported symptoms.
Purpose
The purpose of this study is to investigate changes over time in quality of life (QoL) in incurable lung cancer patients and the impact of determinants like molecular alterations (MA).
Methods
In a prospective, longitudinal, multicentric study, we assessed QoL, symptom burden, psychological distress, unmet needs, and prognostic understanding of patients diagnosed with incurable lung cancer at the time of the diagnosis (T0) and after 3 (T1), 6 (T2) and 12 months (T3) using validated questionnaires like FACT-L, National Comprehensive Cancer Network (NCCN) Distress Thermometer (DT), PHQ-4, SCNS-SF-34, and SEIQoL.
Results
Two hundred seventeen patients were enrolled, 22 (10%) with reported MA. QoL scores improved over time, with a significant trend for DT, PHQ-4, and SCNS-SF-34. Significant determinants for stable or improving scores over time were survival > 6 months, performance status at the time of diagnosis, and presence of MA. Patients with MA showed better QoL scores (FACT-L at T1 104.4 vs 86.3; at T2 107.5 vs 90.0; at T3 100.9 vs 92.8) and lower psychological distress (NCCN DT at T1 3.3 vs 5; at T2 2.7 vs 4.5; at T3 3.7 vs 4.5; PHQ-4 at T1 2.3 vs 4.1; at T2 1.7 vs 3.6; at T3 2.2 vs 3.6), but also a worsening of the scores at 1 year and a higher percentage of inaccurate prognostic understanding (27 vs 17%) compared to patients without MA.
Conclusion
Patients with tumors harboring MA are at risk of QoL deterioration during the course of the disease. Physicians should adapt their communication strategies in order to maintain or improve QoL.
The increasingly frequent use of immunomodulatory agents in dermatology requires the observance of specific recommendations for immunization. These recommendations are developed and regularly updated by the German Standing Committee on Vaccination (STIKO), an independent advisory group at the Robert Koch Institute. Dermatological patients on immunosuppressive treatment should ideally receive all vaccinations included in the standard immunization schedule. Additionally, it is recommended that they also undergo vaccination against the seasonal flu, pneumococci, and herpes zoster (inactivated herpes zoster subunit vaccine for patients ≥ 50 years). Additional immunizations against Haemophilus influenzae type B, hepatitis B and meningococci may be indicated depending on individual comorbidities and exposure risk. Limitations of use, specific contraindications and intervals to be observed between vaccination and immunosuppression depend on the immunosuppressive agent used and its dosing. Only under certain conditions may live‐attenuated vaccines be administered in patients on immunosuppressive therapy. Given its strong suppressive effect on the humoral immune response, no vaccines – except for flu shots – should be given within six months after rituximab therapy.
This CME article presents current recommendations on immunization in immunocompromised individuals, with a special focus on dermatological patients. Its goal is to enable readers to provide competent counseling and to initiate necessary immunizations in this vulnerable patient group.
The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and enhances RNA polymerase II (Pol II) function, but its precise mode of action is poorly understood. Using mass spectrometry of both MYC and Pol II complexes, we show here that MYC controls the assembly of Pol II with a small set of transcription elongation factors that includes SPT5, a subunit of the elongation factor DSIF. MYC directly binds SPT5, recruits SPT5 to promoters, and enables the CDK7-dependent transfer of SPT5 onto Pol II. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. Intriguingly, the high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, thereby decreasing the expression of growth-suppressive genes. Altogether, these results argue that MYC controls the productive assembly of processive Pol II elongation complexes and provide insight into how oncogenic levels of MYC permit uncontrolled cellular growth.