Aerosols represent a health risk since small droplets may enter the respiratory system and cause lung cancer, allergies, or diseases like COVID-19. In this work, an Eulerian-Lagrangian computational fluid dynamics model is used based on a voxel-based (GeoDict) and a mesh-based (StarCCM+) code. For evaluating accuracy and computational time of both models, fractional filtration efficiency and pressure drop are compared to an empirical solution for a single fiber and to experimental results for a complex 3D fibrous filter material. Simulation results of both methods are in good agreement with empirical and measurement results although the complex geometry of the fibers is captured more accurately by the unstructured mesh using the same resolution. Computing times are much faster using the voxel-based code.
Similar to fine dust, liquid aerosols represent a risk to human health since small droplets may enter the respiratory system and cause health problems or severe diseases, such as COVID-19. Oil mist emissions from production processes and from air brakes are reduced by filters and by air dryer cartridges, respectively, while virus-like aerosols are removed by face-masks. Since the two-phase flow processes involved are highly complex and occur on vastly different scales ranging from the scale of single droplets and fibers up to the scale of a whole filter or face mask, the modeling and simulation is extremely challenging. In this work, we present a macro-scale approach for modeling and simulation of the two-phase flow processes in fibrous filters which allows predicting both pressure loss and filtration efficiency from new to steady-state where material parameters and constitutive relationships are obtained based on nano CT scans and micro-scale simulations. Compared to previous work, this approach starts from a physical basis as it relies on mass and momentum conservation and is then closed by material laws. Using this macro-scale approach it is found that both pressure loss and oil mass at steady-state are in good agreement with experimental findings.
BACKGROUND: Post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND) is an integral part of the management of patients with metastatic non-seminoma and residual masses >1 cm after chemotherapy. AIMS: To assess perioperative complications and oncological outcomes at two major referral centres in Switzerland. METHODS: This was a retrospective chart review of 136 patients with non-seminoma who underwent PC-RPLND between 2010 and 2020 at the university hospitals of Bern and Zürich. Patient, treatment and tumour characteristics as well as the types and frequencies of intra- and postoperative complications were registered and compared using the chi-square test. Oncological outcomes consisted of the time and location of relapses as well as progression-free and overall survival, which were compared using the log-rank test. RESULTS: Overall, 70 patients from Bern and 66 patients from Zürich were included; 5 patients had a previous retroperitoneal lymph node dissection (RPLND) (2 Bern, 3 Zürich). Vascular injuries were the most frequent intraoperative complication, occurring in 27/136 (19.9%) patients. Postoperative complications were observed in 42/136 (30.9%) patients, ileus being the most common. Perioperative mortality was 2.2%. A retroperitoneal mass ≥50 mm was significantly associated with intraoperative complications (p = 0.004) and increased resource demands (p = 0.021). Postoperative morbidity was higher according to age at post-chemotherapy retroperitoneal lymph node dissection ≥40 years (p = 0.028) and retroperitoneal mass ≥20 mm (p = 0.005). The median follow-up time was 37 months (interquartile range [IQR] 18–64 months). The median progression-free survival at 5 years was 76% (95% confidence interval [CI]: 64–85%) in Bern and 69% (95% CI: 54–80%) in Zürich (p = 0.464). The median overall survival at 5 years was 88% (95% CI: 76–94%) in Bern and 77% (95% CI: 60–87%) in Zürich (p = 0.335). Patients with progressive disease or a tumour marker increase before retroperitoneal lymph node dissection had significantly inferior progression-free and overall survival compared to non-progressing patients. The presence of teratoma in resected specimens did not confer inferior survival probabilities compared to necrosis only, whereas the presence of vital undifferentiated tumour conferred inferior progression-free and overall survival. Patients with a previous retroperitoneal lymph node dissection and patients operated for late relapses >2 years after chemotherapy also had significantly inferior progression-free and overall survival. CONCLUSIONS: We found a relevant rate of severe perioperative complications at PC-RPLND at even experienced high-volume centres. The oncological outcomes at two major university urological centres in Switzerland were similar and determined by preoperative risk factors and intraoperative histology.
Purpose Our aim is to describe the role of immune checkpoint inhibitors (ICI) in clinical practice by providing the patient and tumor characteristics as well as survival and toxicity rates by sex. Methods We used electronic health records to identify patients treated at the Cancer Center of the University Hospital Bern, Switzerland between January 1, 2017 and June 16, 2021. Results We identified 5109 patients, 689 of whom (13.5%) received at least one dose of ICI. The fraction of patients who were prescribed ICI increased from 8.6% in 2017 to 22.9% in 2021. ICI represented 13.2% of the anticancer treatments in 2017 and increased to 28.2% in 2021. The majority of patients were male (68.7%), who were older than the female patients (median age 67 vs. 61 years). Over time, adjuvant and first line treatments increased for both sexes. Lung cancer and melanoma were the most common cancer types in males and females. The incidence of irAEs was higher among females (38.4% vs. 28.1%) and lead more often to treatment discontination in females than in males (21.1% vs. 16.8%). Independent of sex, the occurrence of irAEs was associated with greater median overall survival (OS, not reached vs. 1.1 years). Female patients had a longer median OS than males (1.9 vs. 1.5 years). Conclusions ICI play an increasingly important role in oncology. irAEs are more frequent in female patients and are associated with a longer OS. More research is needed to understand the association between patient sex and toxicity and survival.
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