Elastocaloric determination of the phase diagram of Sr2RuO4.

One of the main developments in unconventional superconductivity in the past two decades has been the discovery that most unconventional superconductors form phase diagrams that also contain other strongly correlated states. Many systems of interest are therefore close to more than one instability, and tuning between the resultant ordered phases is the subject of intense research1. In recent years, uniaxial pressure applied using piezoelectric-based devices has been shown to be a particularly versatile new method of tuning2,3, leading to experiments that have advanced our understanding of the fascinating unconventional superconductor Sr2RuO4 (refs. 4-9). Here we map out its phase diagram using high-precision measurements of the elastocaloric effect in what we believe to be the first such study including both the normal and the superconducting states. We observe a strong entropy quench on entering the superconducting state, in excellent agreement with a model calculation for pairing at the Van Hove point, and obtain a quantitative estimate of the entropy change associated with entry to a magnetic state that is observed in proximity to the superconductivity. The phase diagram is intriguing both for its similarity to those seen in other families of unconventional superconductors and for extra features unique, so far, to Sr2RuO4.

Strain-Stabilized (π, π) Order at the Surface of Fe1+xTe.

A key property of many quantum materials is that their ground state depends sensitively on small changes of an external tuning parameter, e.g., doping, magnetic field, or pressure, creating opportunities for potential technological applications. Here, we explore tuning of the ground state of the nonsuperconducting parent compound, Fe1+xTe, of the iron chalcogenides by uniaxial strain. Iron telluride exhibits a peculiar (π, 0) antiferromagnetic order unlike the (π, π) order observed in the Fe-pnictide superconductors. The (π, 0) order is accompanied by a significant monoclinic distortion. We explore tuning of the ground state by uniaxial strain combined with low-temperature scanning tunneling microscopy. We demonstrate that, indeed under strain, the surface of Fe1.1Te undergoes a transition to a (π, π)-charge-ordered state. Comparison with transport experiments on uniaxially strained samples shows that this is a surface phase, demonstrating the opportunities afforded by 2D correlated phases stabilized near surfaces and interfaces.

[COVID-19 pandemic-related burden and SARS-CoV-2 prevalence in care facilities]. / COVID-19-Pandemie-bedingte Belastungen und SARS-CoV-2-Prävalenz in Pflegeeinrichtungen.

BACKGROUND: Care facilities are particularly challenged by the COVID-19 pandemic. Besides others this includes human and structural resources. OBJECTIVE: This cross-sectional study evaluated the occurrence of infections, psychosocial stress and the different strategies to handle the COVID-19 pandemic in care facilities. MATERIAL AND METHODS: Data collection took place in 7 care facilities in Baden-Württemberg, Germany between 17 July and 25 August 2020. This included a SARS-CoV­2 PCR and antibody testing and a questionnaire for residents and staff. Care facilities were questioned on interventions and preventive measures taken. RESULTS: Out of 829 SARS-CoV­2 PCR tests all remained negative. Only 2 asymptomatic subjects had detectable SARS-CoV­2 antibodies. All subjects (n = 6) with a history of positive PCR had no detectable antibodies. Healthcare workers were mainly worried about infecting family, friends and especially residents (54.4%) with less fear to infect themselves (27.2%). Individual stress caused by the COVID-19 pandemic: 17.1% exhaustion, 16% financial burden and 13.1% sleeping disorders. Coping strategies included a moderate increase of harmful behavior (+3.3% alcohol, +4.3% nicotine). This was relevantly more important in staff aged under 35 years (+13% alcohol, +12.7% nicotine). Women reported a 2.4% increased use of medication, 49.8% of respondents reduced their social contacts, 76.8% changed their individual hygiene behavior. Care facilities felt prepared to a limited extent for the challenges faced by the pandemic. CONCLUSION: Even with a low prevalence of infections at the time of the survey the COVID-19 pandemic challenged care facilities at multiple levels. This should result in better preventive management and coping strategies.

Multicritical Fermi Surface Topological Transitions.

A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are enhanced through density of states peaks. A well-known example occurs at van Hove singularities where the Fermi surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leaves of Fermi surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and critically boost the formation of complex quantum phases via interactions. As a concrete example of the power of these Fermi surface topological transitions, we demonstrate how they can be used in the analysis of experimental data on Sr_{3}Ru_{2}O_{7}. Understanding the related mechanisms opens up new avenues in material design of complex quantum phases.

Relevance of liver-limited disease in metastatic colorectal cancer: Subgroup findings of the FIRE-3/AIO KRK0306 trial.

In metastatic colorectal cancer (mCRC), liver-limited disease (LLD) is associated with a higher chance of metastectomy leading to long-term survival. However, limited data describes the prognostic and predictive relevance of initially unresectable LLD with regard to targeted first-line therapy. The present analysis investigated the relevance of initially unresectable LLD in mCRC patients treated with targeted therapy against either the epidermal growth factor receptor (EGFR) or vascular epithelial growth factor (VEGF). The analysis was performed based on FIRE-3, a randomized phase III trial comparing first-line chemotherapy with FOLFIRI plus either cetuximab (anti-EGFR) or bevacizumab (anti-VEGF) in RAS wild-type (WT) mCRC. Of 400 patients, 133 (33.3%) had LLD and 267 (66.8%) had non-LLD. Median overall survival (OS) was significantly longer in LLD compared to non-LLD patients (36.0 vs. 25.4 months; hazard ratio [HR] = 0.66; 95% confidence interval [CI]: 0.51-0.87; p = 0.002). In a multivariate analysis also including secondary hepatic resection as time-dependent variable, LLD status was independently prognostic for OS (HR = 0.67; 95% CI: 0.50-0.91; p = 0.01). As assessed by interaction tests, treatment benefit from FOLFIRI plus cetuximab compared to FOLFIRI plus bevacizumab was independent of LLD status with regard to objective response rate (ORR), early tumour shrinkage ≥20% (ETS), depth of response (DpR) and OS (all p > 0.05). In conclusion, LLD could be identified as a prognostic factor in RAS-WT mCRC, which was independent of hepatic resection in patients treated with targeted therapy. LLD had no predictive relevance since benefit from FOLFIRI plus cetuximab over bevacizumab was independent of LLD status.

FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab as first-line treatment for patients with metastatic colorectal cancer (FIRE-3): a randomised, open-label, phase 3 trial.

BACKGROUND: Cetuximab and bevacizumab have both been shown to improve outcomes in patients with metastatic colorectal cancer when added to chemotherapy regimens; however, their comparative effectiveness when partnered with first-line fluorouracil, folinic acid, and irinotecan (FOLFIRI) is unknown. We aimed to compare these agents in patients with KRAS (exon 2) codon 12/13 wild-type metastatic colorectal cancer. METHODS: In this open-label, randomised, phase 3 trial, we recruited patients aged 18-75 years with stage IV, histologically confirmed colorectal cancer, an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2, an estimated life expectancy of greater than 3 months, and adequate organ function, from centres in Germany and Austria. Patients were centrally randomised by fax (1:1) to FOLFIRI plus cetuximab or FOLFIRI plus bevacizumab (using permuted blocks of randomly varying size), stratified according to ECOG performance status, number of metastatic sites, white blood cell count, and alkaline phosphatase concentration. The primary endpoint was objective response analysed by intention to treat. The study has completed recruitment, but follow-up of participants is ongoing. The trial is registered with ClinicalTrials.gov, number NCT00433927. FINDINGS: Between Jan 23, 2007, and Sept 19, 2012, 592 patients with KRAS exon 2 wild-type tumours were randomly assigned and received treatment (297 in the FOLFIRI plus cetuximab group and 295 in the FOLFIRI plus bevacizumab group). 184 (62·0%, 95% CI 56·2-67·5) patients in the cetuximab group achieved an objective response compared with 171 (58·0%, 52·1-63·7) in the bevacizumab group (odds ratio 1·18, 95% CI 0·85-1·64; p=0·18). Median progression-free survival was 10·0 months (95% CI 8·8-10·8) in the cetuximab group and 10·3 months (9·8-11·3) in the bevacizumab group (hazard ratio [HR] 1·06, 95% CI 0·88-1·26; p=0·55); however, median overall survival was 28·7 months (95% CI 24·0-36·6) in the cetuximab group compared with 25·0 months (22·7-27·6) in the bevacizumab group (HR 0·77, 95% CI 0·62-0·96; p=0·017). Safety profiles were consistent with the known side-effects of the study drugs. The most common grade 3 or worse adverse events in both treatment groups were haematotoxicity (73 [25%] of 297 patients in the cetuximab group vs 62 [21%] of 295 patients in the bevacizumab group), skin reactions (77 [26%] vs six [2%]), and diarrhoea (34 [11%] vs 40 [14%]). INTERPRETATION: Although the proportion of patients who achieved an objective response did not significantly differ between the FOLFIRI plus cetuximab and FOLFIRI plus bevacizumab groups, the association with longer overall survival suggests that FOLFIRI plus cetuximab could be the preferred first-line regimen for patients with KRAS exon 2 wild-type metastatic colorectal cancer. FUNDING: Merck KGaA.

A spectroscopic-imaging scanning tunneling microscope in vector magnetic field.

Cryogenic scanning tunneling microscopy and spectroscopy (STM/STS) performed in a high vector magnetic field provide unique possibilities for imaging surface magnetic structures and anisotropic superconductivity and exploring spin physics in quantum materials with atomic precision. Here, we describe the design, construction, and performance of a low-temperature, ultra-high-vacuum (UHV) spectroscopic-imaging STM equipped with a vector magnet capable of applying a field of up to 3 T in any direction with respect to the sample surface. The STM head is housed in a fully bakeable UHV compatible cryogenic insert and is operational over variable temperatures ranging from ∼300 down to 1.5 K. The insert can be easily upgraded using our home-designed 3He refrigerator. In addition to layered compounds, which can be cleaved at a temperature of either ∼300, ∼77, or ∼4.2 K to expose an atomically flat surface, thin films can also be studied by directly transferring using a UHV suitcase from our oxide thin-film laboratory. Samples can be treated further with a heater and a liquid helium/nitrogen cooling stage on a three-axis manipulator. The STM tips can be treated in vacuo by e-beam bombardment and ion sputtering. We demonstrate the successful operation of the STM with varying the magnetic field direction. Our facility provides a way to study materials in which magnetic anisotropy is a key factor in determining the electronic properties such as in topological semimetals and superconductors.

Magnetic-Field Tunable Intertwined Checkerboard Charge Order and Nematicity in the Surface Layer of Sr2 RuO4.

In strongly correlated electron materials, the electronic, spin, and charge degrees of freedom are closely intertwined. This often leads to the stabilization of emergent orders that are highly sensitive to external physical stimuli promising opportunities for technological applications. In perovskite ruthenates, this sensitivity manifests in dramatic changes of the physical properties with subtle structural details of the RuO6 octahedra, stabilizing enigmatic correlated ground states, from a hotly debated superconducting state via electronic nematicity and metamagnetic quantum criticality to ferromagnetism. Here, it is demonstrated that the rotation of the RuO6 octahedra in the surface layer of Sr2 RuO4 generates new emergent orders not observed in the bulk material. Through atomic-scale spectroscopic characterization of the low-energy electronic states, four van Hove singularities are identified in the vicinity of the Fermi energy. The singularities can be directly linked to intertwined nematic and checkerboard charge order. Tuning of one of these van Hove singularities by magnetic field is demonstrated, suggesting that the surface layer undergoes a Lifshitz transition at a magnetic field of ≈32T. The results establish the surface layer of Sr2 RuO4 as an exciting 2D correlated electron system and highlight the opportunities for engineering the low-energy electronic states in these systems.

A multicentric observational trial of pegylated liposomal doxorubicin for metastatic breast cancer.

BACKGROUND: Pegylated liposomal doxorubicin (PLD) is active in metastatic breast cancer. This observational study evaluated the efficacy and safety of PLD in patients treated during routine clinical practice. METHODS: Eligible patients had metastatic breast cancer and were treated with PLD according to the dose and schedule determined by their physician as part of routine practice. The primary objectives were to analyze the efficacy and toxicity of PLD therapy. RESULTS: 125 patients were assessable. Median age was 62 years, 78% had performance status 0-1, and 60% had estrogen-receptor-positive disease. PLD treatment was second- or third-line in 69% of patients. Prior anthracyclines (adjuvant or metastatic) had been used in 56% of patients. The majority of patients (79%) received PLD every 4 weeks at a median dose of 40 mg/m2. Overall response rate was 43% in all patients and 34% in those previously treated with anthracyclines. The most common grade 3/4 adverse events were skin toxicity/hand-foot syndrome (6%), and leukopenia (3%). CONCLUSIONS: This observational study supports the activity and tolerability of PLD in metastatic breast cancer as demonstrated in PLD clinical trials.

Coherent order parameter oscillations in the ground state of the excitonic insulator Ta2NiSe5.

The excitonic insulator is an intriguing electronic phase of condensed excitons. A prominent candidate is the small bandgap semiconductor Ta2NiSe5, in which excitons are believed to undergo a Bose-Einstein condensation-like transition. However, direct experimental evidence for the existence of a coherent condensate in this material is still missing. A direct fingerprint of such a state would be the observation of its collective modes, which are equivalent to the Higgs and Goldstone modes in superconductors. We report evidence for the existence of a coherent amplitude response in the excitonic insulator phase of Ta2NiSe5. Using nonlinear excitations with short laser pulses, we identify a phonon-coupled state of the condensate that can be understood as a novel amplitude mode. The condensate density contribution substantiates the picture of an electronically driven phase transition and characterizes the transient order parameter of the excitonic insulator as a function of temperature and excitation density.

Tunable Weyl and Dirac states in the nonsymmorphic compound CeSbTe.

Recent interest in topological semimetals has led to the proposal of many new topological phases that can be realized in real materials. Next to Dirac and Weyl systems, these include more exotic phases based on manifold band degeneracies in the bulk electronic structure. The exotic states in topological semimetals are usually protected by some sort of crystal symmetry, and the introduction of magnetic order can influence these states by breaking time-reversal symmetry. We show that we can realize a rich variety of different topological semimetal states in a single material, CeSbTe. This compound can exhibit different types of magnetic order that can be accessed easily by applying a small field. Therefore, it allows for tuning the electronic structure and can drive it through a manifold of topologically distinct phases, such as the first nonsymmorphic magnetic topological phase with an eightfold band crossing at a high-symmetry point. Our experimental results are backed by a full magnetic group theory analysis and ab initio calculations. This discovery introduces a realistic and promising platform for studying the interplay of magnetism and topology. We also show that we can generally expand the numbers of space groups that allow for high-order band degeneracies by introducing antiferromagnetic order.

Bendamustine plus rituximab is effective and has a favorable toxicity profile in the treatment of mantle cell and low-grade non-Hodgkin's lymphoma.

PURPOSE: The aim of this multicenter-study was to evaluate the progression-free survival, response rate and toxicity of the combination of bendamustine and rituximab (BR) in patients with mantle cell or low-grade lymphomas in first to third relapse or refractory to previous treatment. PATIENTS AND METHODS: A total of 245 courses (median, four courses per patient) were administered to 63 patients. Bendamustine was given at a dose of 90 mg/m2 as a 30-minute infusion on days 1 and 2, combined with 375 mg/m2 rituximab on day 1, for a maximum of four cycles every 4 weeks. Histologies were 24 follicular, 16 mantle cell, 17 lymphoplasmacytoid, and six marginal zone lymphoma. RESULTS: Fifty-seven of 63 patients responded to BR, corresponding to an overall response rate of 90% (95% CI, 80% to 96%) with a complete remission rate (CR) of 60% (95% CI, 47% to 72%). The median time of progression-free survival was 24 months (range, 5 to 44+ months), and the median duration of overall survival has not yet been reached. In mantle cell lymphomas, BR showed a considerable activity, achieving a response rate of 75% (95% CI, 48% to 93%) with a CR rate of 50%. Myelosuppression was the major toxicity, with 16% grade 3 and 4 leukocytopenia. Thrombocytopenia was rare, with only 3% grade 3 and 4. CONCLUSION: These results demonstrate that the BR combination is a highly active regimen in the treatment of low-grade lymphomas and mantle cell lymphomas.

Phase II trial of biweekly infusional fluorouracil, folinic acid, and oxaliplatin in patients with advanced gastric cancer.

PURPOSE: To evaluate the toxicity and activity of infusional fluorouracil (FU), folinic acid (FA), and oxaliplatin, administered every 2 weeks in patients with metastatic gastric cancer. PATIENTS AND METHODS: Forty-one previously untreated patients with measurable adenocarcinoma of the stomach were eligible for the study. Patients received FU 2.6 g/m(2) (24-hour continuous infusion), FA 500 mg/m(2) (2-hour intravenous infusion), and oxaliplatin 85 mg/m(2) (2-hour intravenous infusion) every 2 weeks for 6 weeks. Treatment was continued until progression of disease was observed. RESULTS: All patients were assessable for toxicity and 37 of 41 patients were assessable for response. Patient characteristics were: sex (male, 28; female,13), median age 60 years (range, 20 to 77 years), and median Eastern Cooperative Oncology Group performance status of 1. Response was evaluated every 6 weeks. Of 37 assessable patients, one complete and 15 partial remissions were observed (overall response rate, 43%). Stable disease was observed in 12 patients (32%) and progressive disease in nine patients (24%). The median overall survival was 9.6 months. WHO grade 3 or 4 hematologic toxicities included neutropenia in two patients (4.9%) and thrombocytopenia in one patient (2.4%). Other WHO grade 3 or 4 toxicities included diarrhea in three patients (7.3%) and vomiting in two patients (4.9%). There were no cases of grade 3 peripheral neuropathy and no treatment-related deaths. CONCLUSION: Biweekly fluorouracil, folinic acid, and oxaliplatin is active and well-tolerated in patients with advanced gastric cancer. Response rates, time to progression, and overall survival were comparable to those achieved with other combination chemotherapy regimens, including FOLFOX6, with significantly less toxicity.

Randomized phase III trial of gemcitabine plus cisplatin compared with gemcitabine alone in advanced pancreatic cancer.

PURPOSE: To compare the effectiveness and tolerability of gemcitabine plus cisplatin with single-agent gemcitabine as first-line chemotherapy for locally advanced or metastatic pancreatic cancer. PATIENTS AND METHODS: Patients with advanced adenocarcinoma of the pancreas were randomly assigned to receive either gemcitabine 1,000 mg/m2 and cisplatin 50 mg/m2 given on days 1 and 15 of a 4-week cycle (GemCis arm) or gemcitabine alone at a dose of 1,000 mg/m2 on days 1, 8, and 15 of a 4-week regimen (Gem arm). The primary end point was overall survival; secondary end points were progression-free survival, response rate, safety, and quality of life. RESULTS: One hundred ninety-five patients were enrolled and showed baseline characteristics well balanced between treatment arms. Combination treatment in the GemCis arm was associated with a prolonged median progression-free survival (5.3 months v 3.1 months; hazard ratio [HR] = 0.75; P = .053). Also, median overall survival was superior for patients treated in the GemCis arm as compared with the Gem arm (7.5 v 6.0 months), an advantage which did not, however, reach statistical significance (HR = 0.80; P = .15). Tumor response rates were comparable between treatment arms (10.2% v 8.2%). The rate of stable disease was, however, greater in the combination arm (60.2% v 40.2%; P < .001). Grade 3 to 4 hematologic toxicity did not exceed 15% in both treatment arms. CONCLUSION: These results support the efficacy and safety of an every-2-weeks treatment with gemcitabine plus cisplatin. Median overall survival and progression-free survival were more favorable in the combination arm as compared with gemcitabine alone, although the difference did not attain statistical significance.