29 research outputs found

    Characterization of a new iron-on-zeolite Y Fischer-Tropsch catalyst

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    Iron pentacarbonyl adsorbed on dry Na-Y zeolite can be oxidized at subambient temperatures into Fe203 located in the zeolite supercages (catalyst I). When catalyst I is hydrogen reduced at 575 K most of the iron has agglomerated externally to the zeolite (catalyst 11). When the iron carbonyl is thermally decomposed in vacuo at 525 K, an iron phase with a very low degree of dispersion is again obtained (catalyst 111). During a Fischer-Tropsch reaction most of the iron is transformed into a Hagg-type carbide phase, located externally to the zeolite. Catalysts I1 and 111 rapidly reach steady state and show a Schulz-Flory-type of product distribution, the Hagg carbide being the active phase. Catalyst I slowly moves to steady state and Schulz-Flory behavior. Product selectivity is only found on this catalyst during transient conditions. The physical information on the three catalysts before and after reaction was obtained with transmission electron microscopy and Mossbauer and EXAFS spectroscopies. These techniques supplied consistent and complementary evidenc

    Substrate effect on the growth of iron clusters in Y zeolite

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    Investigation of the decomposition process and of the thermolytic products obtained from Fe(CO)5/faujasite adducts by thermogravimetric, IR-spectroscopic, Mössbauer spectroscopic and X-ray absorption measurements (EXAFS) provides evidence for a substrate effect on the growth process of iron clusters. CsY substrate increases the Fe---CO bond strength. The stabilized intermediates generated by this effect upon thermolysis at 500 K are easily oxidized to small iron(III) oxide clusters, whereas with NaY substrate to a large extent iron(O) particles are generated. The latter show Mössbauer effect and EXAFS spectra comparable to those obtained from bulk iron. An inner oxidation process is assumed to be involved in the generation of the zeolite-supported iron oxide

    Comorbidities rather than older age define outcome in adult patients with tumors of the Ewing sarcoma family

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    BACKGROUND: Ewing family of tumors (EFT) is rarely diagnosed in patients (pts) over the age of 18 years (years), and data on the clinical course and the outcome of adult EFT pts is sparse. METHODS: In this retrospective analysis, we summarize our experience with adult EFT pts. From 2002 to 2020, we identified 71 pts of whom 58 were evaluable for the final analysis. RESULTS: Median age was 31 years (18-90 years). Pts presented with skeletal (n = 26), and extra-skeletal primary disease (n =32). Tumor size was ≥8 cm in 20 pts and 19 pts were metastasized at first diagnosis. Between the age groups (≤25 vs. 26-40 vs. ≥41 years) we observed differences of Charlson comorbidity index (CCI), tumor origin, as well as type and number of therapy cycles. Overall, median overall survival (OS) was 79 months (95% confidence interval, CI; 28.5-131.4 months), and median progression-free survival (PFS) 34 months (95% CI; 21.4-45.8 months). We observed a poorer outcome (OS, PFS) in older pts. This could be in part due to differences in treatment intensity and the CCI (<3 vs. ≥3; hazard ratio, HR 0.334, 95% CI 0.15-0.72, p = 0.006). In addition, tumor stage had a significant impact on PFS (localized vs. metastasized stage: HR 0.403, 95% CI 0.18-0.87, p = 0.021). CONCLUSIONS: Our data confirms the feasibility of intensive treatment regimens in adult EFT pts. While in our cohort outcome was influenced by age, due to differences in treatment intensity, CCI, and tumor stage, larger studies are warranted to further explore optimized treatment protocols in adult EFT pts

    Combination therapy with Olaratumab/doxorubicin in advanced or metastatic soft tissue sarcoma -a single-Centre experience

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    BACKGROUND: The antibody targeting platelet-derived growth factor receptor alpha (PDGFRA), olaratumab, was approved in 2016 for metastatic soft tissue sarcoma (STS) in combination with doxorubicin based on promising results of a phase Ib/II trial by the Food and Drug Administration (FDA). However, recently the phase III ANNOUNCE trial could not confirm the additional value of olaratumab in this context. METHODS: Here, in a retrospective analysis we share our single-centre experience with olaratumab/doxorubicin in STS by including n = 32 patients treated with olaratumab/doxorubicin between 2016 and 2019. RESULTS: Median progression-free survival (PFS) in the overall cohort was 3.1 months (range 0.6-16.2). A response [complete remission (CR), partial remission (PR) or stable disease (SD)] was seen in n = 11 (34%) cases, whereas n = 21 (66%) patients showed progressive disease (PD). In n = 9 patients surgery was performed subsequently in an individual therapeutic approach. Out of n = 5 patients receiving additional regional hyperthermia, n = 3 achieved PR or SD. CONCLUSIONS: This single-centre experience does also not support the promising phase Ib/II results for olaratumab/doxorubicin in STS. However, our findings do not preclude that olaratumab combination therapy could be valuable in a neoadjuvant setting. This warrants further exploration also taking into account the heterogeneous nature of STS

    Impact of a specialised palliative care intervention in patients with advanced soft tissue sarcoma - a single-centre retrospective analysis

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    BACKGROUND: Soft tissue sarcomas (STS) account for less than 1% of all malignancies. Approximately 50% of the patients develop metastases with limited survival in the course of their disease. For those patients, palliative treatment aiming at symptom relief and improvement of quality of life is most important. However, data on symptom burden and palliative intervention are limited in STS patients. AIM: Our study evaluates the effectiveness of a palliative care intervention on symptom relief and quality of life in STS patients. DESIGN/SETTING: We retrospectively analysed 53 inpatient visits of 34 patients with advanced STS, admitted to our palliative care unit between 2012 and 2018. Symptom burden was measured with a standardised base assessment questionnaire at admission and discharge. RESULTS: Median disease duration before admission was 24 months, 85% of patients had metastases. The predominant indication for admission was pain, weakness and fatigue. Palliative care intervention led to a significant reduction of pain: median NRS for acute pain was reduced from 3 to 1 (p < 0.001), pain within the last 24 h from 5 to 2 (p < 0.001) and of the median MIDOS symptom score: 18 to 13 (p < 0.001). Also, the median stress level, according to the distress thermometer, was reduced significantly: 7.5 to 5 (p = 0.027). CONCLUSIONS: Our data underline that specialised palliative care intervention leads to significant symptom relief in patients with advanced STS. Further efforts should aim for an early integration of palliative care in these patients focusing primarily on the identification of subjects at high risk for severe symptomatic disease

    Roentgenabsorptionsexperimente an Verbindungen der Seltenen Erden und des Urans unter hohem Druck

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    SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

    Pressure-induced changes in L<SUB>III</SUB> X-ray-absorption near-edge structure of CeO<SUB>2</SUB> and CeF<SUB>4</SUB>: relevance to 4f-electronic structure

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    X-ray-absorption near-edge structure (XANES) studies were performed at the LIII thresholds of CeO2 and CeF4 as a function of external pressure up to &#x2245;267 kbar at room temperature. In both cases, the 4f0-related higher-energy component of the essentially double-peaked XANES structure decreases in relative intensity with pressure, opposite to what is generally observed for metallic mixed-valent Ce compounds. This supports the proposed peak assignment on the basis of core-hole induced many-body effects due to 4f-ligand covalency compatible with traditional tetravalency of these compounds

    Mixed valency versus covalency in rare-earth core-electron spectroscopy

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    A comparison of photoemission from shallow core levels with deep core-level spectroscopies allows a distinction between mixed valency and covalency in rare-earth systems. The determinative parameter distinguishing these spectroscopies is the Coulomb interaction between the core hole and the 4f shell. This approach confirms that the compound CeF<SUB>4</SUB> is tetravalent, but does not deny the covalent admixture of 4f character into the valence band

    Pressure-induced valence changes in EuS and SmTe

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    X-ray absorption spectroscopy was applied to study the pressure-induced valence changes in EuS and SmTe, which are divalent semiconductors of NaCl-type structure at ambient pressure. In both systems the Eu-LIII and Sm-LIII thresholds exhibit the onset of intermediate valencies of the rare earth ions at 15 GPa and 4 GPa, respectively. In EuS, one observes only a small increase of the valency within the investigated pressure range (36 GPa), while in SmTe a full transition to trivalency is observed above 20 GPa. The transition to the CsCl-Type high-pressure phase has no significant influence on the valence in both systems
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