210 research outputs found
theoretical and experimental results for Co-OEP on Ni(100)
Metal octaethylporphyrins (M-OEP), M-N4C20H4(C2H5)8, adsorbed at a metallic
substrate are promising candidates to provide spin dependent electric
transport. Despite these systems having been studied extensively by
experiment, details of the adsorbate geometry and surface binding are still
unclear. We have carried out density functional theory calculations for cobalt
octaethyl porphyrin (Co-OEP) adsorbate at clean and oxygen-covered Ni(100)
surfaces as well as for the free Co-OEP molecule where equilibrium structures
were obtained by corresponding energy optimizations. These geometries were
then used in calculations of Co-OEP carbon and nitrogen 1s core excitations
yielding theoretical excitation spectra to be compared with corresponding
K-edge x-ray absorption fine structure (NEXAFS) measurements. The experimental
NEXAFS spectra near the carbon K-edge of Co-OEP bulk material show large
intensity close to the ionization threshold and a triple-peak structure at
lower energies, which can be reproduced by the calculations on free Co-OEP.
The experimental nitrogen K-edge spectra of adsorbed Co-OEP layers exhibit
always a double-peak structure below ionization threshold, independent of the
layer thickness. The peaks are shifted slightly and their separation varies
with adsorbate-substrate distance. This can be explained by hybridization of N
2p with corresponding 3d contributions of the Ni substrate in the excited
final state orbitals as a result of adsorbate-substrate binding via N–Ni bond
formation
Development and external validation of a multivariable [Ga]Ga-PSMA-11 PET-based prediction model for lymph node involvement in men with intermediate or high-risk prostate cancer
PURPOSE
To develop and evaluate a lymph node invasion (LNI) prediction model for men staged with [Ga]Ga-PSMA-11 PET.
METHODS
A consecutive sample of intermediate to high-risk prostate cancer (PCa) patients undergoing [Ga]Ga-PSMA-11 PET, extended pelvic lymph node dissection (ePLND), and radical prostatectomy (RP) at two tertiary referral centers were retrospectively identified. The training cohort comprised 173 patients (treated between 2013 and 2017), the validation cohort 90 patients (treated between 2016 and 2019). Three models for LNI prediction were developed and evaluated using cross-validation. Optimal risk-threshold was determined during model development. The best performing model was evaluated and compared to available conventional and multiparametric magnetic resonance imaging (mpMRI)-based prediction models using area under the receiver operating characteristic curves (AUC), calibration plots, and decision curve analysis (DCA).
RESULTS
A combined model including prostate-specific antigen, biopsy Gleason grade group, [Ga]Ga Ga-PSMA-11 positive volume of the primary tumor, and the assessment of the [Ga]Ga-PSMA-11 report N-status yielded an AUC of 0.923 (95% CI 0.863-0.984) in the external validation. Using a cutoff of ≥ 17%, 44 (50%) ePLNDs would be spared and LNI missed in one patient (4.8%). Compared to conventional and MRI-based models, the proposed model showed similar calibration, higher AUC (0.923 (95% CI 0.863-0.984) vs. 0.700 (95% CI 0.548-0.852)-0.824 (95% CI 0.710-0.938)) and higher net benefit at DCA.
CONCLUSIONS
Our results indicate that information from [Ga]Ga-PSMA-11 may improve LNI prediction in intermediate to high-risk PCa patients undergoing primary staging especially when combined with clinical parameters. For better LNI prediction, future research should investigate the combination of information from both PSMA PET and mpMRI for LNI prediction in PCa patients before RP
Spin crossover in a vacuum-deposited submonolayer of a molecular iron(II) complex
Spin-state switching of transition-metal complexes (spin crossover) is
sensitive to a variety of tiny perturbations. It is often found to be
suppressed for molecules directly adsorbed on solid surfaces. We present X-ray
absorption spectroscopy measurements of a submonolayer of [FeII(NCS)2L] (L:
1-{6-[1,1-di(pyridin-2-yl)ethyl]-pyridin-2-yl}-N,N-dimethylmethanamine)
deposited on a highly oriented pyrolytic graphite substrate in ultrahigh
vacuum. These molecules undergo a thermally induced, fully reversible, gradual
spin crossover with a transition temperature of T1/2 = 235(6) K and a
transition width of ΔT80 = 115(8) K. Our results show that by using a carbon-
based substrate the pin-crossover behavior can be preserved even for molecules
that are in direct contact with a solid surface
Probabilistic Model-Based Safety Analysis
Model-based safety analysis approaches aim at finding critical failure
combinations by analysis of models of the whole system (i.e. software,
hardware, failure modes and environment). The advantage of these methods
compared to traditional approaches is that the analysis of the whole system
gives more precise results. Only few model-based approaches have been applied
to answer quantitative questions in safety analysis, often limited to analysis
of specific failure propagation models, limited types of failure modes or
without system dynamics and behavior, as direct quantitative analysis is uses
large amounts of computing resources. New achievements in the domain of
(probabilistic) model-checking now allow for overcoming this problem.
This paper shows how functional models based on synchronous parallel
semantics, which can be used for system design, implementation and qualitative
safety analysis, can be directly re-used for (model-based) quantitative safety
analysis. Accurate modeling of different types of probabilistic failure
occurrence is shown as well as accurate interpretation of the results of the
analysis. This allows for reliable and expressive assessment of the safety of a
system in early design stages
Site-specific bonding of copper adatoms to pyridine end groups mediating the formation of two-dimensional coordination networks on metal surfaces
We study the formation of a coordination network consisting of the organic
pyridine-based 2,4,6-tris(4-pyridine)-1,3,5-triazine (T4PT) species and Cu
atoms on Cu(111) and Ag(111) metal surfaces. Using scanning tunneling
microscopy, we find that the organic molecule T4PT forms stable two-
dimensional porous networks on the surface of Cu(111) and, by codeposition of
Cu atoms, also on the Ag(111) crystal, in which Cu atoms are twofold
coordinated by T4PT molecules. X-ray absorption spectroscopy measurements of
the metal-organic network Cu–T4PT on Ag(111) accompanied by density-functional
theory calculations show that the nitrogen atoms of the pyridine end groups of
the T4PT molecules are the active sites in coordinating the Cu adatoms. X-ray
magnetic circular dichroism experiments reveal that the Cu atom in such a
metal-organic motif is in a low-valent d10 state and has no magnetic moment
Patient recruitment into clinical studies of solid malignancies during the COVID-19 pandemic in a tertiary cancer center
Background and purpose: To analyze clinical trial activities and patient recruitment numbers into prospective clinical studies for solid malignancies during the COVID-19 pandemic in a tertiary cancer center.
Materials and methods: Patient recruitment numbers in prospective clinical studies of solid malignancies were retrospectively analyzed for the years 2019 – 2021 at the Comprehensive Cancer Center Zurich (CCCZ). Changes in recruitment numbers were tested for association with organ-specific subunits, as well as organizational and treatment-related trial characteristics. To assess differences between categorical variables, Chi-squared test was used. For uni- and multivariate analysis, Cox proportional hazards were calculated.
Results: In 2019, there were a total of 107 studies (registry trials, clinical phase I-III trials, and translational studies) recruiting 304 patients at the CCCZ. During the COVID-19 pandemic in 2020 and 2021, there were 120 and 125 active trials with a total recruitment of 355 and 666 patients, respectively. No significant differences between the subunits and study characteristics in changes of patient recruitment in clinical phase I-III trials were identified when the year prior to the COVID-19 pandemic (2019) was compared to the first year of the pandemic (2020) and to 2020-2021.
Conclusions: Despite healthcare systems around the world have experienced significant disruption due to the COVID-19 pandemic, data from our tertiary cancer center showed that clinical trial activities were maintained at a high level during the pandemic
Current and potential future role of PSMA-PET in patients with castration-resistant prostate cancer
PURPOSE: To review the current literature and discuss potential future roles of the novel positron emission tomography (PET) tracers targeting the prostate-specific membrane antigen (PSMA) in patients with castration-resistant prostate cancer (CRPC).
METHODS: A literature search on February 19th 2018 was conducted using the Medline database and www.clinicaltrials.gov . Additionally, illustrative cases of CRPC patients from our own institution who were restaged and treated based on PSMA-PET scan results are provided.
RESULTS: 11 Studies met the inclusion criteria. PSMA-PET detected more metastatic lesions compared to conventional bone scan. Several patients were up-staged from non-metastatic CRPC (nmCRPC) to metastatic CRPC (mCRPC). Currently, no clear consensus exists regarding treatment response assessment in PSMA-PET scans for mCRPC patients undergoing treatment. Also, the role of PSMA-PET as a gatekeeper for systemic therapy or radioligands is currently undefined. PSMA-guided metastasis-directed radiotherapy may not only alleviate local symptoms but has the potential to defer systemic treatment in patients with oligoprogressive CRPC.
CONCLUSION: Compared to bone scan, PSMA-PET is more sensitive and specific to detect metastases but the therapeutic consequences of PSMA-PET results in the setting of CRPC remain unclear. Until future studies define the role of PSMA-PET in patients with CRPC, the current standard for imaging remains bone scan and computerized tomography
Ablative efficiency of 532-nm laser vaporization compared to transurethral resection of the prostate: results from a prospective three-dimensional ultrasound volumetry study
Purpose: To assess and compare postoperative prostate volume changes following 532-nm laser vaporization (LV) and transurethral resection of the prostate (TURP). To investigate whether differences in volume reduction are associated with differences in clinical outcome. Methods: In this prospective, non-randomized study, 184 consecutive patients undergoing 120W LV (n=98) or TURP (n=86) were included. Transrectal three-dimensional ultrasound and planimetric volumetry of the prostate were performed preoperatively, after catheter removal, 6weeks, 6 and 12months. Additionally, clinical outcome parameters were recorded. Mann-Whitney U test and analysis of covariance were utilized for statistical analysis. Results: Postoperatively, a significant prostate volume reduction was detectable in both groups. However, the relative volume reduction was lower following LV (18.4 vs. 34.7%, p40ml. Re-operations were necessary in three patients following LV. Conclusions: The modest but significantly lower volume reduction following LV was associated with a lower PSA reduction, a lower Q max and more re-operations. Given the lack of long-term results after LV, our results are helpful for preoperative patient counseling. Patients with large prostates and no clear indication for the laser might not benefit from the procedure
Validierung eines Fragebogens zu Problemen der Krankheitsakzeptanz bei Diabetes mellitus: Diabetes Acceptance Scale (DAS)
Fragestellung: Probleme der Diabetesakzeptanz sind assoziiert mit non-adhärentem Selbstbehandlungsverhalten und hyperglykämischer Blutzuckereinstellung. Zur Erfassung von Diabetesakzeptanzproblemen existierte bisher allerdings nur ein recht limitiertes Messinstrument, der Acceptance and Action Diabetes Questionnaire (AADQ). Um differenziertere Messungen zu ermöglichen, wurde die Diabetes Acceptance Scale (DAS) entwickelt, deren Validierung hier berichtet wird.
Methodik: Die DAS ist eine 28-Item-Selbstberichtsskala mit Subskalen zur diabetesbezogenen „Akzeptanz/Integration“, „Behandlungsmotivation“, „Abwehr/Vermeidung“ und „emotionalen Belastung“ sowie einer Summenskala zur Gesamt-Diabetesakzeptanz; Entwicklung beschrieben in Diabetologie und Stoffwechsel 2015; 10 – P137. 460 Diabetespatienten (50% Typ-1, 48% Typ-2, 2% Typ-3; 50% weiblich; Alter 52 ± 15 Jahre; BMI 30 ± 7 kg/m2; Diabetesdauer 15 ± 12 Jahre; HbA1c 7,8 ± 1,4%) bearbeiteten die DAS sowie Fragebögen zu Diabetesakzeptanzproblemen (AADQ), diabetesbezogener Belastung (PAID-5), depressiver Stimmung (PHQ-9) und Diabetes-Selbstbehandlungsverhalten (DSMQ). Gleichzeitig wurde der HbA1c-Wert bestimmt. Anhand dieser Daten wurden Kennwerte der Reliabilität (Cronbachs α) und Validität (kriterienbezogene Korrelationen) der DAS untersucht.
Ergebnisse: Alle DAS-Skalen zeigten durchweg hohe Reliabilität (Subskalen: α= 0,89 – 0,93; Summenskala: α= 0,96). Höhere DAS-Summenwerte (bessere Diabetesakzeptanz) waren hoch korreliert mit weniger Diabetesakzeptanzproblemen nach AADQ (r=-0,65), geringerer diabetesbezogener Belastung (r=-0,69) und weniger Depressivität (r=-0,56); alle P< 0,001. Weiter korrelierten höhere DAS-Summenwerte mit günstigeren Selbstbehandlungsverhaltensweisen nach DSMQ (diabetesgerechte Ernährung: r= 0,56; Medikamentenadhärenz: r= 0,54; Blutzuckerselbstkontrolle: r= 0,42; körperliche Betätigung: r= 0,26; Arztkontakt: r= 0,51) sowie einer besseren Blutzuckereinstellung (HbA1c-Wert: r=-0,42); alle P< 0,001.
Schlussfolgerungen: Die Ergebnisse sprechen für eine hohe Reliabilität und Validität der Diabetes Acceptance Scale. Die Skala erscheint als sehr gutes Messinstrument zur Erkennung von Problemen der Diabetesakzeptanz sowie zur besseren Erforschung dieser gravierenden psychologischen Problematik
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