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The selected ice nanoparticle accelerator, SELINA, was used to prepare beams of single ice particles with positive or negative charge. Positively charged particles were prepared from deionized water and 0.05–0.2 molar solutions of sodium chloride in water, and negatively charged ice particles were generated from water without salt. Depending on the electrospray source configuration, the measured particles vary from 50 to 1000 nm in diameter. The kinetic energy per charge for all particles was set to 200 eV by the collisional equilibration in quadrupoles, which resulted in primary velocities up to 600 m/s for the lowest m/z particles. The electrospray ionization and thus particle formation from SELINA become less efficient with increasing salt concentration, resulting in a lower detected particle frequency and size. Good instrument operation is achievable for concentrations below 0.2 M. After we have verified and characterized positively and negatively charged ice particles, we have combined SELINA with a target and time-of-flight spectrometer for a 'proof-of-principle' post acceleration of 120 nm particles towards hypervelocity (v ~ 3000 m/s) and detection of fragments from the particle impact (SELINA-HIMS). General conditions are discussed for the acceleration of particles between 50 and 1000 nm to velocities well above 3000 m/s with SELINA-HIMS instrument. This article is part of the theme issue 'Dust in the Solar System and beyond'. [ABSTRACT FROM AUTHOR]

Literature models proposed to avoid valve instabilities in safety valves for gas service are evaluated. The phenomena occurring during the opening of the safety valve are described to introduce possible sources of instabilities. Models from the last thirty years are classified based on the hypothesis of the source, creating the classifications balance-based and pressure wave models. The experiments used by their authors to validate the models are evaluated. A sensitivity analysis of five models is conducted based on set pressure, inlet line diameter, ratio of specific heats and moving mass. The model results are also compared to experimental data with different gases and set pressures. In all cases the trends of the balance-based models do not match that of the pressure wave models. Compared to measurements with different set pressures, none of the tested models did both match the trends and predict a reliable inlet line length. Comparing against measurements with varying set pressure, the three percent rule only predicted a reliable inlet line length in 2 out of 5 cases. The predicted increasing trend according to the three percent rule did not match the measured trend of decreasing maximum permissible inlet line length. Based on phenomena like the spindle friction and lubrication not being included as model input parameter, and authors finding non-reproducible measurement setups, it is concluded that the instability of a safety valve is a rather stochastic process without considering additional parameters throughout the lifecycle of the safety valve. [ABSTRACT FROM AUTHOR]

Saturn's large and diffuse E ring is populated by microscopic water ice dust particles, which originate from the Enceladus plume. Cassini 's Cosmic Dust Analyser sampled these ice grains, revealing three compositional particle types with different concentrations of salts and organics. Here, we present the analysis of CDA mass spectra from several orbital periods of Cassini , covering the region from interior to Enceladus' orbit to outside the orbit of Rhea, to map the distribution of the different particle types throughout the radial extent of the E ring. This will provide a better understanding of the potential impact of space weathering effects on to these particles, as the ice grains experience an increasing exposure age during their radially outward migration. In this context, we report the discovery of a new ice particle type (Type 5), which produces spectra indicative of very high salt concentrations, and which we suggest to evolve from less-salty Enceladean ice grains by space weathering. The radial compositional profile, now encompassing four particle types, reveals distinct radial variations in the E ring. At the orbital distance of Enceladus our results are in good agreement with earlier compositional analyses of E ring ice grains in the moon's vicinity. With increasing radial distance to Saturn however, our analysis suggests a growing degree of space weathering and considerable changes to the spatial distribution of the particle types. We also find that the proportion of Type 5 grains – peaking near Rhea's orbit – probably reflects particle charging processes in the E ring. [ABSTRACT FROM AUTHOR]

Chemical reactors in batch- and semi-batch processes are mainly protected by mechanical safety devices or safety integrity systems against critical runaway reactions. Both devices have in common, to limit with their fixed set conditions and discharge areas the productivity and flexibility of chemical plants. Besides, the trend in the industry is to reduce/avoid toxic and explosives to be discharges trough safety devices due to the increased requirements for climate- and environmental protection. A new idea in that regard is to connect the advantages of mechanical safety devices and safety integrated systems in so called smart overpressure protection devices (SmOP). Here, a predictive CSE conversion model (PreCoM) is online tracking the hazard potential of a chemical reaction and defines individual shutoff limits for the reaction. Its zero-emission mode ensures flexible, reaction independent application without fluid discharge. The smart relief mode is maximizing the plant utilization with individual shutoff limits and is minimizing the pollution with controlled discharge areas. In this article, the SmOP concept and the utilization of the PreCoM model for two different reactions and three industrial use cases for zero-emission application is being presented. [ABSTRACT FROM AUTHOR]