294 research outputs found

    Electronic properties of EuB6 in the ferromagnetic regime: Half-metal versus semiconductor

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    To understand the halfmetallic ferromagnet EuB6 we use the Kondo lattice model for valence and conduction band. By means of a recently developed many-body theory we calculate the electronic properties in the ferromagnetic regime up to the Curie temperature. The decreasing magnetic order induces a transition from halfmetallic to semiconducting behavior along with a band broadening. We show the temperature dependence of the quasiparticle density of states and the quasiparticle dispersion as well as the effective mass, the number of carriers and the plasma frequency which are in good agreement with the experimental data

    Behaviour of the V<sup>2+</sup> Ground State in Tetrahedrally Coordinated II–VI Semiconductors

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    The ground state of the lattice-neutral charge state of vanadium in tetrahedrally coordinated II—VI materials is a 4T1 term and is hence subject to a Jahn-Teller (JT) effect. In this paper photo-luminescence and EPR investigations on V2+ (3d3) in ZnS, ZnSe, ZnTe, and CdTe are combined with Tanabe-Sugano calculations including JT interaction. For ZnS the no-phonon structure is explained by a tunnelling splitting

    Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method

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    Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the (n,L)=(37,35)(n,L)=(37,35) state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure due to the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of ÎœHF+=12.89596±0.00034\nu_{\text HF}^+ =12.89596 \pm 0.00034 GHz and ÎœHF−=12.92467±0.00029\nu_{\text HF}^- =12.92467 \pm 0.00029 GHz agree with recent theoretical calculations on a level of 6×10−5 6 \times10^{-5}.Comment: 4 pages, 4 figures, 1 tabl

    First observation of two hyperfine transitions in antiprotonic He-3

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    We report on the first experimental results for microwave spectroscopy of the hyperfine structure of antiprotonic He-3. Due to the helium nuclear spin, antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4 which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.Comment: 8 pages, 6 figures, just published (online so far) in Physics Letters

    The association of intra-therapeutic heterogeneity of somatostatin receptor expression with morphological treatment response in patients undergoing PRRT with [177Lu]-DOTATATE

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    AIM: Purpose of this study was to evaluate the association of the spatial heterogeneity (asphericity, ASP) in intra-therapeutic SPECT/ CT imaging of somatostatin receptor (SSR) positive metastatic gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) for morphological treatment response to peptide receptor radionuclide therapy (PRRT). Secondly, we correlated ASP derived form a pre-therapeutic OctreoScan (ASP[In]) and an intra-therapeutic [177Lu]-SPECT/CT (ASP[Lu]). MATERIALS AND METHODS: Data from first therapy cycle [177Lu-DOTA0-Tyr3]octreotate ([177Lu]-DOTATATE)-PRRT was retrospectively analyzed in 33 patients (m = 20; w = 13; median age, 72 [46-88] years). The evaluation of response to PRRT was performed according to RECIST 1.1 in responding lesions [RL (SD, PR, CR), n = 104] and non-responding lesions [NRL (PD), n = 27]. The association of SSR tumor heterogeneity with morphological response was evaluated by Kruskal-Wallis test and receiver operating characteristic curve (ROC). The optimal threshold for separation (RL vs. NRL) was calculated using the Youden-index. Relationship between pre- and intra-therapeutic ASP was determined with Spearman's rank correlation coefficient (ρ) and Bland-Altman plots. RESULTS: A total of 131 lesions (liver: n = 59, lymph nodes: n = 48, bone: n = 19, pancreas: n = 5) were analyzed. Lesions with higher ASP values showed a significantly poorer response to PRRT (PD, median: 11.3, IQR: 8.5-15.5; SD, median: 3.4, IQR: 2.1-4.5; PR, median 1.7, IQR: 0.9-2.8; CR, median: 0.5, IQR: 0.0-1.3); Kruskal-Wallis, p5.45% (sensitivity 96% and specificity 82%). The correlation coefficient of pre- and intra-therapeutic ASP revealed ρ = 0.72 (p <0.01). The mean absolute difference between ASP[In] and ASP[Lu] was -0.04 (95% Limits of Agreement, -6.1-6.0). CONCLUSION: Pre- and intra-therapeutic ASP shows a strong correlation and might be an useful tool for therapy monitoring

    Structure-activity correlations for BrĂžnsted acid, Lewis Acid, and photocatalyzed reactions of exfoliated crystalline niobium oxides

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    Exfoliated crystalline niobium oxides that contain exposed but interconnected NbO6 octahedra with different degrees of structural distortion and defects are known to catalyze Brþnsted acid (BA), Lewis acid (LA), and photocatalytic (PC) reactions efficiently but their structure–activity relationships are far from clear. Here, three exfoliated niobium oxides, namely, HSr2Nb3O10, HCa2Nb3O10, and HNb3O8, are synthesized, characterized extensively, and tested for selected BA, LA, and PC reactions. The structural origin for BA is associated mainly with acidic hydroxyl groups of edge-shared NbO6 octahedra as proton donors; that of LA is associated with the vacant band position of Nb5+ to receive electron pairs from substrate; and that of PC is associated with the terminal Nb=O of NbO6 octahedra for photon capture and charge transfer to long-lived surface adsorbed substrate complex through associated oxygen vacancies in close proximity. It is believed that an understanding of the structure–activity relationships could lead to the tailored design of NbOx catalysts for industrially important reactions

    Tax Crimes and Illicit Money Flows in the EUs: Comparison and Key Findings

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    The European Union (EU) is one of the attractive jurisdictions for illicit money flows (IMFs) in the world. This is due to structural weaknesses and a comparatively stable economic and political environment in the EU. Criminals engaged in IMFs use sophisticated methods such as trusts, shell companies, and VAT carousel to commit crimes such as money laundering and tax crimes. The link between tax crimes and other IMFs is built on the principle that financial criminals will ensure that their criminal proceeds are safely placed, layered, and integrated into the legitimate financial system. In all these processes, as usually associated with money laundering, the proceeds are susceptible to tax crimes since the criminals would evade payment of taxes in most cases. Using case studies in eleven European States, this chapter maps the variety of main legal approaches to countering tax crime in these jurisdictions. Despite EU’s efforts to unify counter-crime measures in its Member States, the national legal frameworks and institutional settings produce different approaches to tackling tax crimes. This chapter concludes that effective domestic and international cooperation in approaches towards mitigating tax crimes and IMFs are evermore needed

    Experimental observation of flow fields around active Janus spheres

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    The phoretic mechanisms at stake in the propulsion of asymmetric colloids have been the subject of debates during the past years. In particular, the importance of electrokinetic effects on the motility of Pt-PS Janus sphere was recently discussed. Here, we probe the hydrodynamic flow field around a catalytically active colloid using particle tracking velocimetry both in the freely swimming state and when kept stationary with an external force. Our measurements provide information about the fluid velocity in the vicinity of the surface of the colloid, and confirm a mechanism for propulsion that was proposed recently. In addition to offering a unified understanding of the nonequilibrium interfacial transport processes at stake, our results open the way to a thorough description of the hydrodynamic interactions between such active particles and understanding their collective dynamics

    Predictive value of FDG-PET in patients with advanced medullary thyroid cancer undergoing vandetanib treatment

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    Introduction: The prognosis of medullary thyroid carcinoma (MTC) is poor using common chemotherapeutic approaches. However, during the last years encouraging results of recently introduced tyrosine kinase inhibitors (TKI) such as vandetanib have been published. In this study we aimed to correlate the results of 18^{18}F-fluorodeoxyglucose ([18^{18}F]FDG) positron emission tomography (PET) imaging with treatment outcome. Methods: Eighteen patients after thyroidectomy with recurrent/advanced MTC lesions receiving vandetanib (300 mg orally/day) could be analysed. A baseline 18^{18}F-FDG PET prior to and a follow-up 18^{18}F-FDG PET 3 months after TKI initiation were performed. During follow-up, tumor progression was assessed every 3 months including computed tomography according to RECIST. Progression-free survival (PFS) was correlated with the maximum standardized uptake value of 18^{18}F-FDG in lymph nodes (SUV(LN)max) or visceral metastases (SUV(MTS)max) as well as with clinical parameters using ROC analysis. Results: Within median 3.6 years of follow-up, 9 patients showed disease progression at median 8.5 months after TKI initiation. An elevated glucose consumption assessed by baseline 18^{18}F-FDG PET (SUV(LN)max > 7.25) could predict a shorter PFS (2 y) with an accuracy of 76.5% (SUV(LN)max 2.7) also demonstrated an unfavorable prognosis (accuracy, 85.7%). On the other hand, none of the clinical parameters reached significance in response prediction. Conclusions: In patients with advanced and progressive MTC, tumors with higher metabolic activity at baseline are more aggressive and more prone to progression as reflected by a shorter PFS; they should be monitored more closely. Preserved glucose consumption 3 months after treatment initiation was also related to poorer prognosis

    Impact of the first COVID-19 lockdown in Germany on the rate of acute infections during intensive chemotherapy for Hodgkin lymphoma

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    PURPOSE: Evidence on the effect of self-protection via social distancing and wearing face-masks on infections during chemotherapy is currently not available. We asked if the occurrence of acute infections during chemotherapy for advanced-stage Hodgkin lymphoma (HL) decreased when COVID-19 protection measures were in effect. METHODS: We analyzed the occurrence of infections during all documented eBEACOPP cycles starting between 01 March and 30 June of 2017 to 2020 in patients treated within the GHSG HD21 study in Germany and compared the infection rates and characteristics by logistic regression models and means of descriptive statistics. RESULTS: We analyzed 911 cycles of 313 adult patients treated with 4 to 6 cycles of eBEACOPP. We found a significant decrease in the occurrence of infections during chemotherapy for HL during COVID-19 lockdown from 131 (19.6%) of 670 cycles in 2017-2019 to 30 (12.6%) of 239 cycles during COVID-19 lockdown [OR 0.574 (95% CI 0.354-0.930), P = 0.024]. The strongest effect was evident for unspecified infections with 39 cycles (5.8%) during 2017-2019 in comparison to 5 cycles (2.1%) during COVID-19 lockdown. 20 (24.1%) of 83 patients had an infection during the COVID-19 lockdown versus 99 (43.2%) of 229 patients in the years 2017-2019 (P = 0.0023). CONCLUSION: The significant decrease of infections during chemotherapy for HL during COVID-19 lockdown reveals the protective measures' potential to shield patients from transmissible pathogens. We conclude that these measures could be recommended for HL patients at risk for infections during chemotherapy
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