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After decades where human spaceflight missions have been reserved to low Earth orbit, recent years have seen mission proposals and even implemented plans, e.g. with the mission Artemis I, for returning to the lunar surface. SpaceX has published over various media (e.g., its official website, conference presentations, user manual) conceptual information for its reusable Starship to enable human exploration missions to the Martian surface by the end of the decade. The technological and human challenges associated with these plans are daunting. Such a mission at that distance would require excellent system reliability and in-situ-resource utilization on a grand scale, e.g. to produce propellant. The plans contain little details however and have not yet been reviewed concerning their feasibility. In this paper we show significant technological gaps in these plans. Based on estimates and extrapolated data, a mass model as needed to fulfill SpaceX’s plans could not be reproduced and the subsequent trajectory optimization showed that the current plans do not yield a return flight opportunity, due to a too large system mass. Furthermore, significant gaps exist in relevant technologies, e.g. power supply for the Martian surface. It is unlikely that these gaps can be closed until the end of the decade. We recommend several remedies, e.g. stronger international participation to distribute technology development and thus improve feasibility. Overall, with the limited information published by SpaceX about its system and mission scenario and extrapolation from us to fill information gaps, we were not able to find a feasible Mars mission scenario using Starship, even when assuming optimal conditions such as 100% recovery rate of crew consumables during flight.

High-test peroxide (HTP) monopropellant thrusters are being considered for spacecraft lander missions due to their simplicity and reduced toxicity compared to traditional propellants. Pulse-Width Modulation (PWM) throttling is a key technique for precise thrust control in such systems. However, PWM throttling can lead to pressure surges and oscillations in the propellant feed system, potentially compromising system reliability. This study investigates the influence of PWM parameters, specifically duty cycle and frequency, on pressure surges and oscillations in a 50-newton-class HTP monopropellant thruster. The objective is to identify stable operating conditions that mitigate these effects, thereby enhancing the reliability of PWM throttling for lander applications. An experimental setup was developed, including a 50-newton-class thruster with a MnO2/La/Al2O3 catalyst and a solenoid valve for PWM control. Cold flow tests using water characterized the valve response and water hammer effects, while hot fire tests with 90 wt.% HTP were used to evaluate thruster performance under steady-state and PWM conditions. Analytical methods, including Joukowsky’s equation and power spectral density analysis, were used to interpret the data and understand the underlying mechanisms. The results showed that while surge pressures generally aligned with steady-state values, specific PWM conditions led to amplified surges, particularly at low duty cycles. Additionally, high duty cycles induced chugging instability. The natural frequencies of the feed system were found to play a crucial role in these phenomena. Stable operating conditions were identified by avoiding duty cycles that cause constructive interference of pressure waves. This research demonstrates that by carefully selecting PWM parameters based on the feed system’s dynamic characteristics, pressure surges and oscillations can be minimized, ensuring reliable operation of HTP monopropellant thrusters in PWM throttling mode. These findings contribute to the development of more efficient and safer propulsion systems for spacecraft landers.

Current political and sociological efforts to respond to the need for more environmentally friendly technologies have inspired a revival of wood and wood-based material utilization in space systems. The popularity of these materials has faded since their widespread use in the early days of aerospace engineering. This work reviews the literature to provide an overview of use cases, the motivation for using wood and wood-based materials and the challenges involved. A small number of applications were identified in which wood and wood-based materials were preferred over non-renewable raw materials. They are mainly applied for less-stressed disposable components or as a thermal protection material. It can be shown that the applied wooden materials have advantages such as low production costs, easy availability, easy and environment-friendly decomposition and low weight. However, only a limited number of applications have achieved a high level of technological readiness so far. Properties such as anisotropy and a lack of uniformity, defects in wood, the quantity available material and a lack of standards for the certification of wooden materials represent challenges. These are addressed in the current research, which additionally focuses on sustainable growth, enhanced environmental friendliness and advanced lightweight design.

Treatment of advanced melanoma with combined PD-1/CTLA-4 blockade commonly causes serious immune-mediated complications. Here, we identify a subset of patients predisposed to immune checkpoint blockade-related hepatitis who are distinguished by chronic expansion of effector memory CD4 + T cells (T EM cells). Pre-therapy CD4 + T EM cell expansion occurs primarily during autumn or winter in patients with metastatic disease and high cytomegalovirus (CMV)-specific serum antibody titres. These clinical features implicate metastasis-dependent, compartmentalised CMV reactivation as the cause of CD4 + T EM expansion. Pre-therapy CD4 + T EM expansion predicts hepatitis in CMV-seropositive patients, opening possibilities for avoidance or prevention. 3 of 4 patients with pre-treatment CD4 + T EM expansion who received αPD-1 monotherapy instead of αPD-1/αCTLA-4 therapy remained hepatitis-free. 4 of 4 patients with baseline CD4 + T EM expansion given prophylactic valganciclovir and αPD-1/αCTLA-4 therapy remained hepatitis-free. Our findings exemplify how pathogen exposure can shape clinical reactions after cancer therapy and how this insight leads to therapeutic innovations. Checkpoint blocking therapies are used to treat metastatic melanoma, but can have adverse immune-mediated effects, including liver pathology. Here the authors identify an expanded pool of CD4 + effector memory T cells resulting from prior CMV exposure as a risk factor for this adverse effect in these patients.

The objective of this study is to determine the intraobserver and interobserver reliability of end vertebra definition and Cobb angle measurement using printed and digital radiographs of 48 patients with scoliosis. The Cobb angle and the end vertebra were assessed by six observers in 48 patients with scoliosis using printed and digital radiographs. Definition of end vertebra and measurement of the Cobb angle was repeated three times with a 3 week interval. Intraclass correlation coefficients (ICC) were used to determine the interobserver and intraobserver reliabilities. 95% prediction limits for the errors in measurements are provided. For the Cobb angle a mean ICC of 0.97 was determined for intra- and interobserver reliability measurement of the printed radiographs. For the electronic radiographs a mean ICC value of 0.93 was determined for interobserver reliability and a mean ICC value of 0.96 for intraobserver reliability. Intraobserver ICC for definition of end vertebrae was 0.8 for both methods. Interobserver ICC was 0.83 for the manual and 0.74 in the digital method. One pitfall in angle measurement implies the Cobb method itself which measures in two dimensions. Until we develop a proper tri-dimensional measuring system an error is introduced. For the Cobb angle measurement the definition of end vertebrae introduces the main source of error. Digital radiography does not improve the measurement accuracy.

High performance ceramics, particularly Ceramic Matrix Composite (CMC) materials found their way into liquid rocket engines. Yet, so far, mainly carbide or nonoxide CMCs have been of interest. This paper explores the potential and challenges of oxide–oxide ceramic matrix composites (OCMCs) for application in rocket thrust chambers. Therefore, strength, leakage and hot gas tests are conducted with material samples. A particular focus lies on the application of coatings to seal the permeability inherent to the material. Furthermore, prototypes in the form of flame tubes, ceramic chambers with nozzles and ceramic chambers with graphite inlays are developed and investigated experimentally in test firings. The results show that a recrystallised glass of a Y-Al-Si-O compound can successfully create an impermeable coating of the OCMC without affecting its damag-tolerant behaviour. However, the prototype developments show that it is still very challenging to manufacture even slightly complex structures without critical failures. Nevertheless, OCMC structures of relatively simple geometries showed promising results in hot firings and could be used as a lightweight housing, while the inner contour of the chamber and nozzle are realised, e.g., by a graphite inlay of appropriate quality.

Identifying new substances that could potentially be used for tumor therapy and the precise analysis of their spectrum of action requires models that are as similar as possible to the tumor present in the patient. Traditionally, two-dimensional (2D) cell cultures are used. However, these only resemble solid tumors to a limited extent. More realistic in vivo models, such as tissue cultures, which are invaluable for the final analysis of the effect of new substances, are unsuitable for high-throughput screening (HTS), such as substance library screening. Therefore, we addressed which parameters need to be optimized to produce 3D cultures suitable for HTS using established tumor cell lines and ultra-low attachment plates, and we tested which experimental parameters need to be considered. In our studies, we have focused on cell lines from gliomas. Gliomas are incurable tumors of the central nervous system and are the subject of intensive research. Our studies used ten glioma cell lines from which we generated spheroids using ultra-low attachment plates. We then determined the spheroid size as a function of the initial cell number and the culture time. We analyzed cell viability using propidium iodide staining, evaluated the effects of temozolomide and radiation on spheroids, and compared the effect to that on 2D cultures. We found that spheroid size correlated linearly with the initial cell number. Fewer cells (250–500) generally resulted in better growth than a higher number. However, not all cell lines produced growing spheroids at all. The spheroids had an outer layer of living cells and an inner core of dead cells. The size of the inner core of dead cells was different in the various cell lines and developed differently during the incubation period. Radiation affected spheroids more than 2D cultures, especially at higher cell densities. Our results provide insight into using glioma cell lines to form spheroids as model systems. We have identified initial cell numbers as a critical parameter for their effective use in research, offering a hopeful outlook for tumor therapy research and drug development.

ASHRAE RP-1743 investigates the impact of inlet duct design on the fan performance of indoor air handling units during equipment testing. The standard inlet duct specified in ASHRAE 37 can be problematic as the duct might increase the length of the testing setup to exceed the height of legacy testing facilities. Hence, several alternative inlet reduced-length duct configurations were tested to identify a configuration that achieves fan performance comparable to the ASHRAE 37 inlet duct. The considered inlet duct configurations were 4-inch (10.2-cm) straight inlet duct and two unconventional inlet duct configurations. The inlet duct configurations were tested on two 3-ton (10.55-kW) units, one had Electronic Commuted Motor (ECM) and the other had Constant Torque Motor (CTM). Testing of the units for each inlet duct configuration was under two nominal air flowrates, which were 350 CFM/ ton (46.97 L/s-kW) and 450 CFM/ ton (60.39 L/s-kW), and seven External Static Pressure (ESP) points. Also, testing of the units included investigating various effects, such as hysteresis and atmospheric pressure, that might affect the repeatability of tests of indoor air handling units. The results showed that the effects of hysteresis and atmospheric pressure were significant, as the change in power and air flowrate were more than the uncertainty of measurements, on the unit with an ECM fan, while they were not on the unit with a CTM fan. In terms of inlet duct configurations, fan performance was maintained within the suggested tolerance, which was 5% in power and 2.5% in air flowrate, while testing the two unconventional inlet duct configurations compared to the standard inlet duct. The reduction in the stack-height of the inlet duct was ranged from 60%-80% compared to the standard inlet duct. For 4-inch (10.2-cm) straight inlet duct, the test was conducted on the unit with the CTM fan, and the results showed that fan performance was maintained within the suggested tolerance, as well.

Background The type of pneumonia that is caused by the new coronavirus (SARS-CoV-2) has spread across the world in a pandemic. It is not clear if COVID-19 patients have any lower urinary tract signs or symptoms. Methods The effect of COVID-19 on lower urinary tract function was studied in a prospective multi-centre, observational study including 238 patients who were admitted with symptoms caused by COVID-19 to the university hospital of Aachen in Germany and Tabriz in Iran. Results None of the patients reported to have any lower urinary tract symptoms. SARS-CoV-2 was found in the urine of 19% of the tested patients. The mortality rate in COVID-19 infected patients with microscopic haematuria together with white blood cells in their urine, was significantly increased from 48 to 61% in the Tabriz cohort ( p -value = 0.03) and from 30 to 35% in the Aachen cohort (p-value =0.045). Furthermore, in the group of patients with SARS-CoV-2 urine PCR, the mortality rate rose from 30 to 58%. ( p -value =0.039). Conclusion Patients admitted with COVID-19 did not report to have any lower urinary tract symptoms, even those patient who had a positive Urine SARS-CoV-2 PCR. In addition, hematuria, WBC in urine as well as SARS- CoV-2 presence in urine, were found to be strong negative prognostic factors in admitted COVID-19 patients.