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Ices, silicates and carbonaceous materials have been detected in several astrophysical environments such as interstellar molecular clouds, comets, and planetary surfaces. These solids are continuously exposed to ion irradiation and UV photolysis. Our knowledge on the properties of solids and molecules and on the modification induced by fast ions (keV-MeV) and UV photons is mainly based on laboratory experiments and on the comparison of experimental results with observations. Here we will give a few examples of the role of laboratory experiments to our understanding of the physical and chemical properties of ices in space.

The concepts of energy islands or energy hubs have gained attention in Europe as a means to enhance offshore wind integration and regional energy systems. These islands can incorporate high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) transmission systems, battery energy storage systems (BESS), and hydrogen production, requiring advanced operational strategies to manage the inherent nonlinearities and time dependence of their subsystems. To address these challenges, this work proposes a comprehensive framework for the optimal operation of hybrid AC/DC energy islands, addressing (i) active and reactive power dispatch, incorporating BESS and hydrogen production; (ii) a detailed wind resource characterization based on 1 year of hourly data obtained using a realistic wind model with local measurements, including wake losses and turbine-level forecasts, used to define representative seasonal and spatial production patterns that inform typical operating conditions; (iii) operational optimization of a realistic test system based on the Princess Elisabeth Energy Island, and (iv) uncertainty analysis via Monte Carlo simulations, quantifying the impact of wind power and electricity price forecast errors, set up using commercial wind power planning tools and advanced forecasting software, and verified with Pyomo/Python.

Structured treatment interruptions of highly-active antiretroviral therapy (HAART) might be particularly relevant for sub-Saharan Africa, where cost-saving strategies could help to increase the number of patients on HAART. We did a randomised trial of structured treatment interruption in Abidjan, Côte d'Ivoire. HIV-infected adults were randomised to receive continuous HAART (CT), CD4-guided HAART (CD4GT) with interruption and reintroduction thresholds at 350 and 250 cells per mm 3, respectively, or 2-months-off, 4-months-on HAART. Primary endpoints were death and severe morbidity (any WHO stage 3 or 4 events and any events leading to death) at month 24. We report data from the CT and CD4GT groups until Oct 31, 2005, when the data safety monitoring board recommended to prematurely stop the CD4GT arm. Analyses were intention-to-treat. This study is registered at ClinicalTrials.gov, number NCT00158405. 326 adults (median CD4 count nadir 272 per mm 3) were randomised to the CT or CD4GT groups and followed up for median of 20 months. Incidence of mortality (per 100 person-years) was not different between groups (CT 0·6, CD4GT 1·2; p=0·57). Incidence of severe morbidity (per 100 person-years) was higher in the CDG4T group (17·6) than in the CT group (6·7; p=0·001). The most frequent severe events were invasive bacterial diseases. 79% of severe morbidity episodes occurred in patients with CD4 count 200–500 per mm 3. Patients on CD4GT had severe morbidity rates 2·5-fold higher than those on CT. This difference was mainly due to high rates of common diseases in patients with CD4 count 200–500 per mm 3. This CD4-guided structured treatment interruption strategy should not be recommended in Abidjan.

In this paper, a new DC-DC transformer topology is described and analyzed. The Modular Multilevel DC Transformer (MMDCT) is studied for interconnecting high-voltage direct current (HVDC) systems with different grounding schemes and converter technologies. Its operating principle is explained and demonstrated using time-domain simulations, where the MMDCT is connected to a hybrid HVDC system with a Line Commutated Converter (LCC) based system on one side and to a Voltage Source Converter (VSC) based system, specifically a Modular Multilevel Converter (MMC) to the other.

This paper is focused in the control design of a DC/DC Current Flow Controller (CFC) for meshed HVDC grids. It proposes a control design methodology based on an outer current loop to regulate DC grid currents and an inner voltage loop to keep under control the CFC voltage. This approach is able to limit the CFC voltage to avoid exceeding the device limitations. A linear model of the HVDC grid including the CFC is obtained to apply linear control techniques to design the regulator. The system performance is validated by means of simulations considering different case studies.

The article introduces a hierarchical control structure for Multiterminal High Voltage Direct Current (M-HVDC) systems. The presented hierarchy is similar to the control structure of the classical AC systems divided in primary, secondary and tertiary control. The design and interaction between the secondary, or power control, and the primary controllers, or voltage control, are discussed. Furthermore, the operation characteristics and operation points are commented. Some scenarios have been simulated in order to test and verify the proposed method including a power reference change and a grid side converter disconnection. (6 pages)

Un homme de 35 ans, VIH-1, sans antécédents médicaux et chirurgicaux particuliers, a été hospitalisé à Abidjan, Côte d'Ivoire, dans un contexte fébrile, toux, dyspnée, douleurs thoraciques et à la radiographie pulmonaire, un déroulement de la crosse de l'aorte une semaine après avoir débuté les antirétroviraux (ARV). Les scanners angiothoraciques réalisés ont mis en évidence une ectasie aortique globale étendue avec thrombus mural. Une échocardiographie transoesophagienne conclut à une dissection aortique, type A de Stanford. Le diagnostic de tuberculose a été confirmé par l'isolation en culture de Mycobacterium Tuberculosis. Huit ans après, le patient est encore vivant, sans intervention chirurgicale et se plaint de douleurs thoraciques intermittentes. Sa pression artérielle est stable et a une insuffisance rénale modérée. Nous rapportons un cas rare de dissection aortique anévrismale chez un adulte infecté par le VIH-1 dans le cadre d'un syndrome de reconstitution immune avec tuberculose pulmonaire.

This paper presents a voltage control for an offshore load fed by a Multi-Terminal VSC-HVDC transmission system (MTHVDC). The studied system is composed by two GSCs (Grid Side Converters) and one OSC (Offshore Side Converter). The objective is to maintain the amplitude and frequency of the AC voltage constant at the offshore terminal with a minimum overshoot. A vector control strategy including a current control loop and a voltage control loop is proposed for the OSC and also LQG (Linear-Quadratic-Gaussian) compensator is employed to improve the voltage response of offshore load. The performance of this controller is validated using simulation in MATLAB/SIMULINK software for three operating conditions: normal operation, no-load and start-up of the offshore load. Simulation results illustrate that the AC voltage of load can be governed at its nominal value and MT-HVDC system linked to the offshore load with the proposed controller is able to provide a reliable dynamic operation and a desirable voltage quality during load variations.

Currently, the installation of photovoltaic power plants (PVPPs) integrated with the transmission system is becoming common. This interconnection must obey the grid codes of the transmission system operator. The requirements of these grid codes are related to the response during faults, frequency, voltage support, and the regulation of active and reactive power. Because of these requirements, it is necessary to analyse the limitations of the photovoltaic (PV) generators. Accordingly, this paper focuses on the mathematical analysis of the reactive power capability curve of a PV generator considering the variation of solar radiation and temperature. In addition, a PVPP of 1 MW is modelled and simulated in DiGSILENT PowerFactory validating the results.