Design of a test platform for miniaturized electric propulsion

Nanosatellites represent an emerging opportunity to pursue a broad set of mission goals, including remote sensing, technology demonstration, and communications, at low cost and fast delivery. These new opportunities require a technological improvement to increase capabilities such as orbit change and transfer, formation flying, and constellation build up, close proximity operations and deorbiting. In this sense, miniaturized electrical propulsion systems increase the range of missions performed with multi-unit CubeSats. At subsystem level, many concepts have been recently developed but their level of readiness is limited. Moreover, the integration of propulsion poses new challenges at system level that influence heavily the spacecraft design and its verification. The present research, developed by Politecnico di Torino and supported by ESA, intends to build a flexible test platform and define effective procedures to support the evaluation of suitable propulsion systems for future nanosatellites. The main objectives are to investigate the interaction of propulsion systems with CubeSat-technology from different perspectives (mechanical, electrical, magnetic, and chemical) and to evaluate the performance of the integrated platform. The test platform is a 6U CubeSat able to host electric propulsion systems selected among European solutions, providing mechanical, electrical and data interfaces. A flexible and robust structure holds and protects the propulsion system and avionics, and externally interfaces the test platform with the facility of ESA/ESTEC propulsion laboratory. The on-board Electrical Power System adapts the voltage and power provided by batteries to serve loads up to 2A @ 28V. Different protocols are included in the on-board computer to exchange data and commands with a range of propulsion systems. The test platform is equipped with a wide range of sensors (e.g. temperature sensors, accelerometers, and magnetometers) to measure and acquire parameters both of the propulsion system and of on-board avionics. Data are stored on-board and sent to the ground support system via wired and/or RF links. The test platform operations are controlled through commands sent by the operator and by autonomous onboard routines in charge of managing transitions between operative modes and for detection, identification and recovery of failures. The test platform will be ready in December 2018, and it will represent the first important step for the evaluation of electrical propulsion systems integrated in small satellites. The paper describes into the detail the design and development of the platform and the plan for the test campaign

On the mechanism and rate of gold incorporation into thiol-dependent flavoreductases.

International audienceNADPH-dependent flavoreductases are important drug targets. During their enzymatic cycle thiolates and selenolates that have high affinity for transition metals are generated. Auranofin (AF), a gold-containing compound, is classified by the World Health Organization as an antirheumatic agent and it is indicated as the scaffold for the development of new anticancer and antiparasitic drugs. AF inhibits selenocysteine-containing flavoreductases (thioredoxin reductase and thioredoxin glutathione reductase) more effectively than non Se-containing ones (glutathione reductase); this preference has been ascribed to the high affinity of selenium for gold. We solved the 3D structure of the Se-containing Thioredoxin Glutathione Reductase from the human parasite Schistosoma mansoni complexed with Au and our results challenge this view: we believe that the relative velocity of the reaction rather than the relative affinity, depends on the presence of Sec residues, which appear to dictate AF selectivity

Verification campaign of small test platform hosting electric propulsion systems

The growing interest of the market in nano-satellites is pushing the technology associated with development of these small platforms Among the enabling technologies, miniaturized electrical propulsion (EP)systems deeply increase the range of missions performed with multi-unit CubeSats (6U+). Actually, the level of readiness of these technologies is still low, due to the lack of effective and safe processes and facilities to verify and validate them before in-orbit demonstration. One of the major issue sis to understand what the mutual impact of an electric propulsion system and the spacecraft technology is, in order to avoid loss of onboard functionalities and anomalies and misbehaviours. The present paper deals with the verification campaign of a versatile test platform based on CubeSat-like technology, able to host a wide range of EP system favouring an effective verification campaign thanks to precise procedures and a proper setup of the facility (the Small Plasma Facility /SPF) of ESA-ESTEC). The platform is equipped with specific sensors and tools, i.e. temperature sensors (NTC), current and voltage sensing circuits, strips of open resistors, magnetometers, silica wafers mounted on the CubeSat faces, and a very precise (24-bit resolution) acquisition system. The objective is to obtain unprecedented information that, integrated with external devices normally used for the verification campaign of propulsion system, e.g. faraday cups and Magnetic Field Mapper, allows to assess the functional behaviour of the integrated system (platform and EP system). The test platform has already been integrated with SPF and the functional test campaign has been successfully performed, demonstrating the test platform is ready for final tests

Impact of transition from open bay to single room design neonatal intensive care unit on multidrug-resistant organism colonization rates

Background: The influence of the neonatal intensive care unit (NICU) design on the acquisition of multidrug-resistant organisms (MDROs) has not been well-documented.Aim: To examine the effect of single room unit (SRU) versus open bay unit (OBU) design on the incidence of colonization with MDROs and third-generation cephalosporin-resistant bacteria (3G-CRB) in infants admitted to the NICU.Methods: Retrospective cohort study, including all infants admitted to the NICU of a tertiary care academic hospital two years prior to and two years following the transition from OBU to SRU in May 2017. Weekly cultures of throat and rectum were collected to screen for MDRO carriership. Incidence of colonization (percentage of all infants and incidence density per 1000 patient-days) with MDROs and 3G-CRB were compared between OBU and SRU periods.Findings: Incidence analysis of 1293 NICU infants, identified 3.2% MDRO carriers (2.5% OBU, 4.0% SRU, not significant), including 2.3% extended-spectrum b-lactamase-producing Enterobacterales carriers, and 18.6% 3G-CRB carriers (17% OBU, 20% SRU, not significant). No differences were found in MDRO incidence density per 1000 patient-days between infants admitted to OBU (1.56) compared to SRU infants (2.63).Conclusion: Transition in NICU design from open bay to SRUs was not associated with a reduction in colonization rates with MDROs or 3G-CRB in our hospital. Further research on preventing the acquisition and spread of resistant bacteria at high-risk departments such as the NICU, as well as optimal ward design, are needed. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of The Healthcare Infection Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Developmen

Impact of transition from open bay to single room design neonatal intensive care unit on multidrug-resistant organism colonization rates

Background: The influence of the neonatal intensive care unit (NICU) design on the acquisition of multidrug-resistant organisms (MDROs) has not been well-documented.Aim: To examine the effect of single room unit (SRU) versus open bay unit (OBU) design on the incidence of colonization with MDROs and third-generation cephalosporin-resistant bacteria (3G-CRB) in infants admitted to the NICU.Methods: Retrospective cohort study, including all infants admitted to the NICU of a tertiary care academic hospital two years prior to and two years following the transition from OBU to SRU in May 2017. Weekly cultures of throat and rectum were collected to screen for MDRO carriership. Incidence of colonization (percentage of all infants and incidence density per 1000 patient-days) with MDROs and 3G-CRB were compared between OBU and SRU periods.Findings: Incidence analysis of 1293 NICU infants, identified 3.2% MDRO carriers (2.5% OBU, 4.0% SRU, not significant), including 2.3% extended-spectrum b-lactamase-producing Enterobacterales carriers, and 18.6% 3G-CRB carriers (17% OBU, 20% SRU, not significant). No differences were found in MDRO incidence density per 1000 patient-days between infants admitted to OBU (1.56) compared to SRU infants (2.63).Conclusion: Transition in NICU design from open bay to SRUs was not associated with a reduction in colonization rates with MDROs or 3G-CRB in our hospital. Further research on preventing the acquisition and spread of resistant bacteria at high-risk departments such as the NICU, as well as optimal ward design, are needed. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of The Healthcare Infection Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

The Effect of Single-Room Care Versus Open-Bay Care on the Incidence of Bacterial Nosocomial Infections in Pre-Term Neonates: A Retrospective Cohort Study

Introduction Nosocomial infections (NIs) are a major source of iatrogenic harm in neonatal intensive care units (NICUs). The influence of the infrastructure of NICUs on NIs is not well documented. This study aims to examine the effect of single-room units (SRU) versus open-bay units (OBU) on the incidence of NIs, including central-line-associated bloodstream infections (CLABSI), in preterm neonates. Methods All preterm neonates (= 1 NIs. No differences were found in incidence density (13.68 vs. 12.62, p = 0.62) or cumulative incidence of NI (23.97 vs. 22.02, p = 0.59) between OBU and SRU. CLABSIs showed a similar non-significant reduction after the move (14.00 vs. 10.59, p = 0.51). U chart analysis did not identify unit transition as a potential source of special-cause variation for CLABSI and NI. Competing risks regression analysis revealed longer duration of invasive mechanical ventilation as a significant risk factor for NI (subhazards ratio: 1.03 per day on ventilation, p = 0.01). Conclusion Single-rooms are not associated with a significant reduction in NIs in the NICU. This study therefore does not add evidence that could support the transition to SRUs if based only on a large multimodal infection control strategy. Recommendations to build SRUs would require a wider justification, also taking into account other SRU benefits.Developmen