This study presents an experimental and fluid-based numerical investigation of axisymmetric radio-frequency argon capacitively coupled plasmas, focusing on the impact of highly detailed geometric representations. Numerical simulations were performed using varying levels of geometric detail for the discharge chamber. Experiments were conducted over a pressure range of 20-50 Pa, with a nominal power of 10 W applied at the power supply, and current-voltage characteristics were recorded. Experimental parameters-including peak-to-peak voltage Vpp, direct current (DC) self-bias VDC, pressure, and system geometry-served as inputs for the simulations. The measured peak-to-peak current Ipp was then compared with the calculated results. The findings demonstrate that a more comprehensive representation of the experimental geometry significantly improves the agreement between simulation and experiment, highlighting the necessity of detailed chamber models for reliable plasma characterization and predictive capability.

Skin barrier dysfunction and redox imbalance contribute to inflammatory dermatoses, including atopic dermatitis. Although cold atmospheric plasma has demonstrated therapeutic potential, its molecular effects on intact epidermal regulatory networks under non-overtly damaging conditions remain incompletely understood. Here, we investigated the in vivo responses of healthy murine skin to surface dielectric barrier discharge plasma applied within an experimentally defined non-overtly damaging exposure window. Murine dorsal skin was exposed to plasma for 10 or 30 s. Barrier integrity, lipid organization, inflammatory activation, and oxidative DNA damage were assessed using biophysical measurements, histology, immunohistochemistry, and molecular analyses. Proteomic profiling combined with network integration and targeted transcriptional validation was performed to identify plasma-responsive regulatory pathways. Plasma exposure preserved epidermal architecture, lipid organization, and barrier function, without evidence of inflammatory activation or increased oxidative DNA damage. Proteomic analysis identified integrin alpha 6 as a prominently upregulated adhesion-associated node. Network integration associated integrin alpha 6 with molecular responses related to keratinocyte differentiation, cornified envelope regulation, and immune-epithelial signaling pathways. Targeted gene expression analysis confirmed selective modulation of differentiation- and barrier-associated programs. Comparative mapping further demonstrated partial overlap between plasma-responsive targets and curated atopic dermatitis-associated gene networks. Collectively, these findings demonstrate that cold atmospheric plasma exposure, under the tested non-overtly damaging conditions, is associated with selective modulation of epidermal barrier-related molecular networks in intact skin.

In this article, we present a semi-implicit method for coupling a plasma fluid model (PFM) with an external circuit model (ECM) for the simulation of capacitively coupled plasma (CCP) discharges. To incorporate the ECM into the PFM, we applied a semi-implicit treatment of the applied voltage across the electrodes, thus improving numerical stability. For automatic convergence of the simulations, we introduced a convergence criterion based on the two-norm difference of plasma variables between successive radio frequency (RF) cycles. Recognizing the strong sensitivity of solution accuracy to the time-step size, we further proposed a time-step size refinement (TSSR) algorithm. This approach iteratively halves the time-step size and uses the quasi-steady-state solution from the previous iteration as the initial condition for the next. Combined with the convergence-based ending criterion, the TSSR algorithm significantly reduces total simulation time while preserving solution accuracy. The proposed framework offers a robust and efficient strategy for simulating transient plasma-circuit interactions in a typical CCP system.

This study presents a portable planar argon-based plasma jet designed for large-area biomedical applications, with an emphasis on uniform discharge, stability, and safety. The device incorporates interchangeable rear and side inlet gas adapters with restriction plates and channels to equalize gas flow, while electrodes are encapsulated in low-temperature co-fired ceramics to reduce degradation and arcing during repeated operation. Flow simulations were conducted for multiple channel configurations to ensure laminar gas distribution and uniform plasma generation. Device performance and safety were evaluated using the kinPen MED as a reference standard. Electrical characteristics, optical emission, discharge uniformity, temperature, gas velocity, ozone generation, UV irradiance, and leakage current were systematically measured. The plasma exhibited stable voltage, current, and power after an initial warm-up period. Temperatures stabilized within minutes, with the rear-inlet configuration demonstrating lower operating temperatures due to higher outlet gas velocity. Ozone levels remained below established safety limits, while UV exposure constrained allowable treatment times. Leakage current decreased with increasing distance and approached safety thresholds at short separations. These results demonstrate that the proposed planar plasma jet provides stable, uniform plasma delivery while meeting key safety requirements, supporting its potential for clinical and biomedical use.

Renewed global interests in high-speed flight have created a need for experimental platforms to probe the transonic to hypersonic regimes. Simultaneously, Taiwan’s New Space initiatives created a strong demand for rocket engineering talent. This paper introduces Asfaloth, a 6.21 m tall, 261 kg academic sounding rocket developed to address both needs. Asfaloth was designed to exceed Mach 1.2 and an apogee of 9000 m, powered by a polypropylene-[Formula: see text] hybrid engine that delivers [Formula: see text] in thrust and [Formula: see text] of total impulse. The engine is shared with HTTP-3A, a different indigenous rocket targeting the Kármán Line, using a common core approach to accelerate propulsion maturation. Onboard, Asfaloth was designed to support ocean recovery, in-flight data downlink, and advanced payloads such as event-based imaging diagnostic experiments. A successful subscale launch with [Formula: see text] total impulse has been demonstrated, operating from Taiwan’s new Xuhai Short-Term Scientific Research Sounding Rocket Launch Site. In spite of telemetry loss, video analysis of the flight showed reliable departure from the launch rail. Summarily, by integrating a high-speed flight-inspired motivator with academic training, Asfaloth represents a notable milestone in Taiwan’s New Space initiatives and provides a versatile platform for future flight experiments.

This study evaluates an argon low-temperature atmospheric-pressure plasma jet (APPJ) combined with medication for the treatment of onychomycosis. Plasma characterization confirmed operation below 25 degrees C, indicating biomedical suitability. Using Candida albicans cultured on bovine hoof models, APPJ exposure achieved an approximately 1-log reduction in colony counts within 2 min. For embedded infections, plasma treatment, medication alone, and combined therapies were compared. The combined plasma-medication approach significantly reduced yeast burden in moderately infected samples (p <= 0.05) and showed superior antimicrobial efficacy in mildly infected specimens compared with medication alone (p <= 0.01). Plasma-assisted drug permeation experiments further demonstrated complete penetration through the specimen, reaching the bottom at approximately 200 & micro;m depth.

This study investigates the behavior of electric discharges by focusing on real power for simplifying calculation and establishing air gap resistance as a robust indicator of the discharge mode. We demonstrate that high air gap resistance correlates with a dielectric barrier discharge (DBD) mode, whereas low resistance signals the formation of a conductive plasma bridge in a streamer mode. Critically, we examine the often-neglected influence of the treated object resistance and the heat generation. We find that higher object resistance lowers the system’s power factor, which in turn increases the frequency of detrimental spark discharges. Intensified Charge-Coupled Device (ICCD) visualization further reveals that the treated object resistance interrupts discharge continuity. Thus, reducing the treated object resistance is shown to be an effective strategy for mitigating surface damage by lowering voltage amplitude, suppressing sparks, and reducing heat generation. Conversely, it implies that increasing resistance is an effective method to enhance surface modification. This work identifies air gap resistance, voltage amplitude, power factor and heat generation ratio as crucial parameters for optimizing applications and strongly recommends their inclusion in future studies while only voltage and current data are required.

Ethylene-alpha-olefin elastomer (EAO)/polyethylene (PE) wax blends with various compositions were investigated as candidate materials for hybrid rocket fuel applications, focusing on correlating blends' crystalline structure and thermomechanical properties to their combustion behaviors. The structural characterizations using grazing-incidence wide-angle X-ray scattering and X-ray diffraction revealed a composition-dependent evolution from predominantly out-of-plane oriented lamellar crystalline domains toward increasingly in-plane oriented crystalline domains as the content of PE wax increased. This structural evolution was accompanied by enlarged crystallite size and enhanced crystallinity in the blends, reaching an optimum value of 45.6% for the D30E70 (EAO: PE wax wt. ratio, 30:70) blend, as confirmed by differential scanning calorimetry. Furthermore, the thermogravimetric analyses showed a decreasing thermal stability, and dynamic mechanical analyses displayed progressively increased stiffness and reduced elastomeric response with the increasing PE wax content in the blends. The thermal conductivity of the D30E70 blend increased to 0.36 W m-1 K-1 from 0.26 W m-1 K-1 for pristine EAO, indicating improved internal heat transfer capability. The Mechanical tests demonstrated that tensile strength increased with PE wax loading, while the elastomeric EAO phase helped preserve ductility in the blends. The combustion and hot-fire evaluations revealed that the D30E70 blend exhibited the highest regression rate value of 0.78 mm s-1, while effectively suppressing thermal dripping observed in pristine PE wax. These findings suggest that the orientation of crystalline domains in EAO/PE wax blends is closely correlated with thermomechanical and combustion behavior, particularly regression rate. This approach offers an effective strategy to modulate regression rate through control of crystalline domain orientation.

Nitrous oxide is a highly suitable oxidizer for hybrid rockets due to its self-pressurizing properties, moderate cost, and high accessibility. However, its vapor pressure and density are highly dependent on ambient temperature, requiring careful consideration of temperature variations in real applications. To mitigate this issue, an oxidizer called Nytrox was produced by adding a small fraction of oxygen to bulk nitrous oxide. This modification enables the hybrid rocket propulsion system to maintain a nearly constant average thrust and total impulse across a wide range of ambient temperatures. A series of 7 s hot-fire tests of a small Nytrox/polypropylene hybrid rocket engine operating at ~60 barA of running tank pressure demonstrated a consistent average thrust of 45.3 ± 0.7 kgf and a total impulse of 307.6 ± 3.9 kgf·s within a N2O temperature range of 5.9–22.6 °C, compared to highly varying values of the N2O/polypropylene one within a N2O temperature range of 10.8–29.8 °C. Furthermore, the specific impulse of the Nytrox hybrid rocket engine increases mildly with decreasing temperature because of the increasing amount of added oxygen that benefits the combustion for generating the thrust.

To improve the ignition system of a hybrid rocket engine, this paper reports the experimental study of the performance of the hypergolic solid fuel grain (HSF) consisting of a mixture of NaBH4/KNO3 with paraffin for a hybrid rocket engine using 90 % HTP as the oxidizer. Drop tests were conducted to examine the ignition delay time (IDT) of HSF compositions with varying ratios of sodium borohydride (NaBH4) and potassium nitrate (KNO3) mixing with paraffin. The results showed that IDT decreased with increasing amount of NaBH4, and decreased further with KNO3 addition. For comparison purpose, two formulations were selected for the tests: HSF01 (80 wt% paraffin, 20 wt% NaBH4) and HSF02 (65 wt% paraffin, 20 wt% NaBH4, 15 wt% KNO3). A series of image visualizations using high-resolution and high-speed cameras, and event cameras revealed similar ignition mechanisms for both tests, in which flamelets were formed upon the contact of HTP droplet, leading to explosive combustion. However, KNO3 in HSF02 consumed the smoke-like mixture produced during the explosion, in which behavior was absent in HSF01. In addition, atmospheric combustion tests (ACT) were conducted in a PMMA tube (10 mm in diameter and 100 mm in length) and the results showed that only HSF02 was successfully ignited, with flamelets forming similar to 4 ms after HTP injection and full combustion was established at similar to 0.7 s. The test results indicated that the KNO3 as an oxidant additive added to the hypergolic solid fuel grain (HSF) plays an important role in the HSF ignition mechanism. It decreases not only the IDT of the fuel grain, but also increases the flammability of the HSF.

Europa, an icy moon of Jupiter, features complex surface characteristics shaped by tidal forces and interactions with its subsurface ocean, making it a key target for astrobiology research. Outgassing plumes have been reported using Earth-based observations and in situ Galileo mission data, though the nature of plumes on Europa remains largely unknown. This study investigates the dynamics of dust entrained in Europa’s water vapor plumes, which is crucial for understanding surface evolution and subsurface interactions. We employ the Direct Simulation Monte Carlo method to simulate these plumes considering various gas production rates and initial velocities. The Direct Simulation Monte Carlo results provide information for dust trajectory modeling to evaluate the effects of gas drag on particle transport during an idealized plume eruption. We explore how gas production rates, initial gas and dust velocities, and dust size distributions influence plume morphology and deposition patterns. Our findings reveal that gas drag plays a significant role in the behavior of dust, with smaller particles (0.001−0.1 μ m) becoming widely dispersed, while larger particles (0.1−10 μ m) tend to settle near the source. At the highest gas production rate of 1 × 10 ^29 H _2 O s ^−1 considered in this paper, gas drag becomes the dominant force and reduces the influence of initial ejection velocities. Our study also provides essential insights into surface−subsurface interactions on Europa, aiding in interpreting the upcoming observational data from the missions of JUICE and Europa Clipper, which will further explore these intriguing phenomena.

Microbial contamination is the major safety concern of sprouts, and its main source is the seeds. Achieving effective reduction requires very high concentrations of chlorine-based disinfectants (>10,000 mg/kg). Thus, the objective of this study was to combine microbubble (MB) with chlorine dioxide (ClO2, 500 mg/L) and slightly acidic electrolyzed water (SAEW, containing 250 mg/L of available chlorine) to inactivate Salmonella Typhimurium on mung bean seeds. MB water containing disinfectants (10 L) was generated for 10 min, then the seeds were treated for 10, 20, or 30 min. Significant reductions were obtained by combining MB with disinfectants. After 20-min treatment, ClO2-MB (ClMB) achieved additional reductions of 3.7 and 2.3 log CFU/g, respectively, compared with water washing and ClO2 only. SAEW-MB (SMB) achieved additional reductions of 3.6 and 2.0 CFU/g, respectively when compared with water washing and SAEW only after 20-min treatment. No significant difference for the reduction in S. Typhimurium was observed (p >= 0.05) between 20-min and 30-min treatments, but increased damage to seeds was evident after 30-min treatment. More surface cracks were observed on the seeds treated with ClMB than on those subjected to water washing and ClO2 only when examined under a scanning electron microscope. However, the germination rate of seeds and the weight increase of sprouts were not significantly different between treatments of ClMB, water washing, and ClO2 only. A large-volume MB device (100 L) was established, resulting in a reduction of S. Typhimurium and natural microflora by 3.1 and 3.3 log CFU/g, respectively, after a 20-min ClMB treatment. This study's findings demonstrated how MB enhances the effectiveness of disinfectants and its potential capacity for large-scale operation.

Enceladus continuously ejects approximately 300 kg s ^−1 of water vapor from its south polar regions, forming an extensive neutral gas torus around Saturn. In this study, we use the direct simulation Monte Carlo method to model the detailed spatial structure of this neutral torus, explicitly incorporating major loss processes, including photolysis, charge exchange, and electron-impact reactions. Our results demonstrate that molecular collisions and chemical reactions significantly enhance the radial and vertical spreading of water-group molecules within the Saturnian system. Specifically, our calculations indicate that 40% of the water-group neutrals emitted by Enceladus’ plumes impact Saturnian rings, with a roughly estimated deposition of 0.03 mm of icy material over one million years. These findings provide insight into the physical and chemical processes that govern Enceladus' neutral torus environment, including implications for the composition of rings and their evolution.

In spite of hypergolic systems common use in rocket engine ignitors, the dynamics of hypergolic reaction at fluid–fluid interfaces remain underexplored. This study investigates the ignition dynamics of hydrogen peroxide (H2O2) droplets impacting deep pools of a sodium borohydride (NaBH4)-based hypergolic liquid fluid. Unlike prior studies employing confined geometries (e.g., petri dishes or test tubes), the present setup minimizes wall effects and reveals several previously unreported phenomena. Key parameters–including NaBH4 concentration (3, 6, 9 wt

The European Space Agency's (ESA) Rosetta mission escorted comet 67P/Churyumov-Gerasimenko (hereafter 67P) from August 2014 to September 2016 along its orbit through the inner Solar System. It watched as the comet's activity started to develop at large heliocentric distances, come to its culmination at perihelion, and decline as the comet travelled out towards Jupiter's orbit. This long-term continuous monitoring of the comet's activity has provided an unprecedented wealth of data on this comet and its activity.The observations revealed a complex bi-lobate shape [1, 2] and diverse morphology [3]. As a comet approaches the Sun it is heated and the ices start sublimating and ripping with them dust particles. Thus one of the important questions to be answered was what the bulk of the comet was made of i.e. what the bulk refractory-to-volatile ratio is. In the simplified view where any ejected material is lost to space two measurements are sufficient to determine this ratio. First, the total mass loss during one apparition measured by the Radio Science Investigation (RSI) [4]. Second, the total volatile mass loss which can be indirectly determined by the in-situ measurements of the gas density [5, 6, 7] or remote sensing data [8, 9, 10, 11]. In this simple case, the refractory-to-volatile ratio can be immediately inferred from those two measurements. But the complex surface morphology has revealed large dust deposits [12] that indicate that possibly a large fraction of the ejected dust is re-deposited [13]. If that is indeed the case, then the two above mentioned quantities cannot constrain the total dust mass ejected but rather only the dust mass escaping the nucleus gravity. Further, the process of dust fall-back obscures the emitted dust-to-gas ratio.In this work, we present results that simultaneously constrain the dust size distribution, dust-to-gas ratio, fraction of dust re-deposition, and total mass production rates for comet 67P. We use a 3D Direct Simulation Monte Carlo (DSMC) gas dynamics code to simulate the inner gas coma of the comet for the duration of the Rosetta mission. The gas model is constrained by ROSINA/COPS data. Further, we simulate for different epochs the inner dust coma using a 3D dust dynamics code including gas drag and the nucleus' gravity. Using advanced dust scattering properties these results are used to produce synthetic images that can be compared to the OSIRIS data set. These simulations allow us to constrain the properties of the dust coma and the total gas and dust production rates.In particular, we show how the dust-to-gas mass production rate ratio, the power-law exponent of the dust size distribution, the fraction of dust fall back, and the scattering properties of the dust are inter-related and constrain each other. Because these parameters are not independent they need to be fit simultaneously. E.g. the lowest mass needed to match the brightness of the dust coma as observed by OSIRIS is achieved with power-law distributions with exponents between 4 and 4.5. Using the constraint of the total mass loss of the comet during the 2015 apparition we will show that only a narrow parameter set fits all observations. We determined a total volatile mass loss of (6.1 ± 1.5)·109 kg during the 2015 apparition. Further, we found that power-laws with q=3.7+0.57-0.078 are consistent with the data. This results in a total of 5.1+6.0-4.9 ·109 kg of dust being ejected from the nucleus surface, of which 4.4+4.9-4.2·109 kg escape to space and 6.8+11-6.8·108kg (or an equivalent of 14+22-14 cm over the smooth regions) is re-deposited on the surface. This leads to a dust-to-gas ratio of 0.73+1.3-0.70 for the escaping material and 0.84+1.6-0.81 for the ejected material. We have further found that the smallest dust size must be strictly smaller than ~30 μm and nominally even smaller than ~12 μm. AcknowledgementsWe thank Frank Preusker and Frank Scholten for providing us the comet shape model SHAP7 [2] used in this work.We thank Vladimir Zakharov for providing valuable comments on the section of the analytical solution.We acknowledge the personnel at ESA's European Space Operations Center (ESOC) in Darmstadt, Germany, European Space Astronomy Center (ESAC) in Spain, and at ESA for the making the Rosetta mission possible. Furthermore, we thank the OSIRS and ROSINA instrument and science teams for their hard work. We thank Martin Rubin and Kathrin Altwegg for giving us access and support to/for the ROSINA/COPS data.References[1] Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, H., et al. 2015, Science, 347, 1044[2] Preusker, F., Scholten, F., Matz, K.-D., et al. 2017, A&A, 607, L1.[3] Thomas, N., Davidsson, B., El-Maarry, M. R., Fornasier, S., Giacomini, L., Gracia-Berna, A. G., et al. 2015. A&A 583, A17[4] Pätzold, M., Andert, T. P., Hahn, M., Barriot, J.-P., Asmar, S. W., Häusler, B., et al. 2019, MNRAS, 483, 2337–2346.[5] Fougere, N., Altwegg, K., Berthelier, J. J., et al. 2016, A&A, 588, A134.[6] Läuter, M., Kramer, T., Rubin, M., and Altwegg, K., 2018, MNRAS, 483, 852–861[7] Combi, M., Shou, Y., Fougere, N., Tenishev, V., Altwegg, K., Rubin, M., et al., 2020, Icarus 335, 113421[8] Migliorini, A., Piccioni, G., Capaccioni, F., Filacchione, G., Bockelée-Morvan, D., Erard, S., et al., 2016, A&A 589, A45.[9] Bockelée-Morvan, D., Crovisier, J., Erard, S., Capaccioni, F., Leyrat, C., Filacchione, G., et al., 2016, MNRAS, 462 S170–S183[10] Marshall, D. W., Hartogh, P., Rezac, L., von Allmen, P., Biver, N., Bockelée-Morvan, D., et al., 2017, A&A, 603, A87[11] Biver, N., Bockelée-Morvan, D., Hofstadter, M., Lellouch, E., Choukroun, M., Gulkis, S., et al. 2019, A&A, 630, A19[12] Thomas, N., El Maarry, M. R., Theologou, P., Preusker, F., Scholten, F., Jorda, L., et al., 2018, PSS, 164, 19–36[13] Thomas, N., Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Rickman, H., et al., 2015. Science, 347, 44

This paper extensively reviews hybrid rocket propulsion-related activities from combustion engine designs to launch tests. Starting with a brief review of rocket propulsion development history, a comparison among the three bi-propellant rocket propulsion approaches, and hybrid rocket engine design guidelines, a very thorough review related to hybrid rocket propulsion and its applications is presented in this paper. In addition to propellant choice, engine design also affects the hybrid rocket performance and, therefore, a variety of engine designs, considering, e.g., fuel geometry, swirl injection, ignition designs, and some innovative flow-channel designs are also explored. Furthermore, many fundamental studies on increasing hybrid rocket engine performances, such as regression rate enhancement, mixing enhancement, and combustion optimization, are also reviewed. Many problems that will be encountered for practical applications are also reviewed and discussed, including the O/F ratio shift, low-frequency instability, and scale-up methods. For hybrid rocket engine applications in the future, advanced capabilities and lightweight design of the hybrid rocket engine, such as throttling capability, thrust vectoring control concept, insulation materials, 3D-printing manufacturing technologies, and flight demonstrations, are also included. Finally, some active hybrid rocket research teams and their plans for flight activities are briefly introduced.

There is a basic understanding of the way gases are released from cometary nuclei in order to form the gas and dust comae as they approach the Sun. We know that the production of these gases is driven by the incident solar radiation on the nucleus, and this leads to the sublimation of cometary ices. The composition of the coma depends on the composition and thermal properties of its nucleus. In general, comets are often assumed to be a mixture of ice and dust [1, 2, 3]. There is however a lack of knowledge on the actual internal structure of comets both at macroscopic and microscopic levels. For comet 67P/Churyumov-Gerasimenko (67P/CG), for example, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) determined H2O, CO2, CO and O2 to be the most abundant gases in the coma[4, 5, 6], which is a clear indication of the composition of dominant ices within the nucleus. How these different ices are physically related to each other and distributed within the nucleus is a more intricate issue for which we have no clear answer at this time.Previous studies have produced mathematical models of the surface layer of cometary nuclei based on heat and gas diffusion through pores [7, 8, 9, 10, 11]. These studies use a one-dimensional geometry. Our aim is to use a similar approach to model the gas activity distribution around three-dimensional nuclei. This is known in the literature as "standard thermal model" for slow-rotators [12, 13, 14] and it calculates the insolation condition at a certain heliocentric distance for one point on the surface after Nrot nucleus rotations on its axis. Here in the influence of thermal inertia combined with sub-surface sublimation sources at different depths and the resulting gas flow field is investigated using both H2O and CO2 as driving volatiles. The additional complexity in geometry prevents more sophisticated numerical solutions. We have therefore ignored the influence of heating of gas through collision with a hotter dust mantle in the present model, considering that these additional effects probably only result in relatively small changes in the position of the sublimation front due to the exponential change in sublimation rate with temperature.We apply this study to a spherical nucleus comet, but we adopt some of the rotational and surface properties of the target of the Rosetta mission, comet 67P/CG. In order to model gas activity in the inner coma, we have chosen a nucleus with a 2 km radius and an outer limit of our simulation domain to be at 8km from the surface of the comet. The 3D Direct Simulation Monte Carlo method is then used to model the coma as a sublimation-driven flow.Simulation results displayed in figure 1 show that thermal inertia and the depth of the sublimation front can have a strong effect on the emission distribution of the flow at the surface. We determine that for cases with a thermal inertia larger than zero, the H2O distribution can be shifted in rotation by about 20º relative to models with no thermal lag. For CO2 cases with different thermal inertia values and sublimation fronts, the activity distribution can be shifted towards the terminator making CO2-ice the main source of nightside activity. This would be consistent with observations of gas density and dust column density above the nightside hemisphere of the nucleus of 67P/CG.There is also a strong effect of CO2 activity on the distribution of the H2O flow field in the nightside of the comet, which can decrease the amount of H2O by up to 98% compared to a pure H2O case. CO2 gas also decreases the temperature of the flow, as well as the flow velocities on the nightside. In the cases we studied, temperatures were reduced by a factor of 2 and velocities were up to 150m/s slower than the cases without CO2 activity. Figure 1: Slice of the 3D simulation domain on the xy-plane, with information of number density, temperature and velocity within the flow for a case without thermal inertia (upper row), a pure H2O case with thermal inertia of 40 J/(m2K√s) (second row) and a mixture case with 40 J/(m2K√s) (third and fourth row). The arrows on the left side indicate the position of the sub-solar point. Acknowledgements This work has been carried out within the frame- work of the National Centre of Competence in Re- search PlanetS supported by the Swiss National Sci- ence Foundation. The authors acknowledge the finan- cial support of the SNSF. Raphael Marschall acknowledges the support from the Swiss National Science Foundation grant 184482. References [1] F. L. Whipple: A comet model. I. The acceleration of comet Encke, Astrophysical Journal, Vol. 111, p375-394, 1950. [2] D. A. Mendis and G. D. Brin, 1977, The Moon, 17, Issue 4, p. 359-372. [3] F. P. Fanale and J. R. Salvail, 1984, Icarus, 60, Issue 3, p. 476-511. [4] M. Hässig et al., 2015, Science, 347, Issue 6220. [5] L. Le Roy et al., 2015, A&A, 583, A1. [6] A. Bieler et al., 2015, Nature, 526, p. 678-681. [7] Y. V. Skorov and H. Rickman, 1995, Planetary and Space Science, 43, Issue 12. [8] Y. V. Skorov et al., 1999, Icarus, 140, Issue 1. [9] Y. V. Skorov et al., 2001, Icarus, 153, Issue 1. [10] Y. V. Skorov et al., 2002, Earth Moon and Planets, 90. [11] B. Davidsson and Y. Skorov, 2004, Icarus, 168, Issue 1, p. 163- 185. [12] L. Lebofsky and J. Spencer ,1989, Asteroids II: Radiometry and thermal modeling of asteroids. [13] M. Festou, H. U. Keller and H. A. Weaver, 2004, Comets II, University of Arizona Press. [14] W.F., Huebner et al., 2006, Heat and Gas Diffusion in Comet Nuclei, The International Space Science Institute.

This research focuses on using natural renewable water resources, filters, and performance recovery systems to reduce the cost of generating pure hydrogen for Proton Exchange Membrane Fuel Cells (PEMFCs). This study uses de-ionized (DI) water, tap water, and river water from upstream as the water source. Water from these sources passes through 1 μm PP filters, activated carbon, and reverse osmosis for filtering. The filtered water then undergoes hydrogen production experiments for a duration of 6000 min. Performance recovery experiments follow directly after hydrogen production experiments. The hydrogen production experiments show the following: DI water yielded a hydrogen production rate of 27.13 mL/min; unfiltered tap water produced 15.41 mL/min; unfiltered upstream river water resulted in 10.03 mL/min; filtered tap water yielded 19.24 mL/min; and filtered upstream river water generated 18.54 mL/min. Performance recovery experiments conducted by passing DI water into PEMFCs for 15 min show that the hydrogen generation rate of tap water increased to 25.73 mL/min, and the rate of hydrogen generation of upstream river water increased to 22.58 mL/min. In terms of cost-effectiveness, under the same volume of hydrogen production (approximately 600 kg/year), using only DI water costs 1.8-times more than the cost of using filtered tap water in experiments.

The major pathogen associated with eggs is Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) and chlorine washing is the most widely used for sanitization. Microbubble, a novel technique and able to operate in large quantity, has been presented to be an alternative method. Thus, microbubble water combining with ozone (OMB) was applied to disinfect S. Enteritidis spiked on shells at 107 cells per egg. OMB was generated by injecting ozone into a Nikuni microbubble system, then delivered into 10 L of water. After 5, 10, or 20 min of activation time, the eggs were placed into OMB and washed for 30 or 60 s. The controls involved unwashed, water washing, ozone only, and microbubble only (MB). The highest reduction, 5.19 log CFU/egg, was achieved by the combination of 20-min activation and 60-s washing, which was used for following tests of large water quantities. Comparing with the unwashed control, 4.32, 3.73 and 3.07 log CFU/egg reductions were achieved in 25, 80, and 100 L of water, respectively. The other system, Calpeda, with higher motor power was tested in 100 L and obtained a reduction of 4.15 log CFU/egg. The average diameter of bubbles generated by Nikuni and Cal-peda pump systems were 29.05 and 36.50 mu m, respectively, which both were within the microbubble definition of ISO. Much lower reductions, around 1-2 log10 CFU/egg, were shown with the treatments of ozone only and MB by the same operative parameters. After 15-day storage at ambient temperature, the OMB-treated eggs showed similar sensory quality with the unwashed ones. This is the first study demonstrating that OMB effec-tively inactivates S. Enteritidis on shell eggs in large quantity of water and does not diminished the sensory characteristics of eggs. Furthermore, bacterial population was under the detection limit in the OMB-treated water.

Pesticide residues and microorganisms are major concerns when it comes to vegetable safety. Several techniques are employed to eliminate these contaminants, one of which is ozone microbubble water (OMB), known for its effectiveness. However, previous studies on OMB tested OMB's effectiveness on pesticides and microorganisms separately, using different operative parameters for each. Therefore, this study aimed to investigate the efficacy of OMB in removing frequently detected pesticides in Taiwan, namely chlorantraniliprole and dimethomorph, and Salmonella Typhimurium and Escherichia coli. Napa cabbages (Brassica rapa subsp. pekinensis) were inoculated with these contaminants and subjected to OMB treatment (10 min of microbubble activation and 3 min of washing). The control groups included unwashed, municipal water, ozone treatment, microbubble treatment, and sodium hypochlorite washing. The concentrations of residual chlorantraniliprole and dimethomorph after OMB treatment were found to be 16.10% and 19.39%, respectively, of those washed with municipal water. Treatments with only ozone or microbubble showed higher residual concentrations (40.89% and 22.19% for chlorantraniliprole, and 59.37% and 35.47% for dimethomorph, respectively). Using water washing as the baseline, OMB reduced S. Typhimurium and E. coli by 2.11 and 2.31 log CFU g(-1), respectively, whereas the reduction achieved by ozone or microbubble treatments alone was lower (similar to 1 log CFU g(-1)). Finally, there were no significant differences in the physical characteristics of the leaves (breaking force, cutting force, and color) between OMB and water washing. This study is the first to demonstrate the effective removal of pesticides and bacteria using OMB with the same operative parameters.