MARS System Research Articles

Characterizing a novel in-situ oxygen delivery device for establishing controlled redox zonation within a high infiltration rate sequential biofilter

By applying favorable oxic and oligotrophic conditions through subsequent aeration and an additional infiltration step, the sequential managed aquifer recharge technology (SMART) was proven to better remove trace organic chemicals (TOrCs) than conventional MAR systems. To minimize the physical footprint, pumping costs and hydraulic retention times, as well as to overcome limitations of site-specific heterogeneities of such systems, the SMART concept was further upgraded by two main engineered technologies. This SMARTplus bioreactor is comprised of an infiltration trench and highly homogenous porous media to provide high infiltration rates and plug-flow conditions. Additionally, an in-situ oxygen delivery device, in particular a self-designed PDMS gas-liquid membrane contactor, was designed to establish favorable subsurface oxic conditions. This novel SMARTplus technology was investigated at pilot scale and is designed for advanced water treatment either in the context of water reuse or treatment of impaired surface water. To determine the design specifications and to construct a pilot-scale membrane contactor, the mass transfer coefficients of the PDMS membrane were investigated at lab-scale for varying Reynold numbers (0.2–2). With the help of the customized membrane contactor, homogenous, bubble-free and passive oxygen delivery could be successfully demonstrated at pilot-scale under laminar flow conditions and short contact times. Oxygen concentrations downstream of the membrane contactors met the design specifications (>1 mg/L) as long as the required feed water quality was provided. However, high NH4+ concentrations in the secondary effluent resulted in higher and unsteady oxygen demand than the target oxygen transfer rates could meet and suboxic conditions prevailed. Although a 20–50% enhancement in the removal of certain compounds (4-FAA, antipyrine, sulfamethoxazole, and citalopram) was achieved, demonstration of the full potential of enhanced TOrC removal by SMARTplus was hindered due to unsteady feed water quality.

Autonomous optical navigation of Mars probe aided by one-way Doppler measurements in capture stage

The optical navigation errors of Mars probe in the capture stage depend closely on which targets are selected to be observed in the Mars system. As for this problem, an integrated navigation scheme is proposed wherein the optical observation is aided by one-way Doppler measurements. The errors are then analyzed respectively for the optical observation and one-way Doppler measurements. The real-time calculating scheme which exploits the extended Kalman filter (EKF) framework is designed for the integrated navigation. The simulation tests demonstrate that the errors of optical navigation, which select the Mars moon as the observation target, are relatively smaller than those in the Mars-orientation optical navigation case. On one hand, the integrated navigation errors do not depend on the selecting pattern of optical observation targets. On the other hand, the integrated navigation errors are significantly reduced as compared with those in the optical-alone autonomous navigation mode.

The potential impacts of automated cars on urban transport: An exploratory analysis

ObjectiveThe concept of automated cars is rapidly becoming a reality. Yet there has been very little analysis of the impacts of such developments on the performance of urban transport systems. These impacts are potentially complex. On the positive side, automation has the potential to increase road capacity, make driving available to more people, and reduce accidents and emissions. On the negative side, it could attract users away from public transport, walking and cycling, substantially increase traffic levels and stimulate urban sprawl. These impacts cannot currently be measured empirically and, by the time that they can, it will be too late to change the implementation model to rectify any resulting problems. Predictive assessments are therefore needed. This paper considers the possible impacts of automated vehicles, predicts their effects on the urban land use and transport system, and discusses the policy implications. We focus on automation of the car fleet, and do not consider the potential of automation of public transport or freight. MethodsWe consider the literature on the range of attributes of automated vehicles which might affect transport and land use patterns, and suggest potential outcomes for each over the period to 2050. These include the proportion of automated vehicles in the car fleet, whether automated vehicles are privately purchased or publicly shared, the impacts on network capacity, the reduced need to pay for and walk from parking places, the potential reduction in the value of in-vehicle time and the potential use by current non-drivers. We represent these attributes in an expanded causal link diagram of the urban land use and transport system and import those causal links into the MARS system dynamics model. We determine from the literature a level for each attribute, and test the impacts in a set of ten scenarios using an updated MARS model of Leeds. ResultsBased on our input assumptions, we find that car-km in 2050 could be over 50% higher than in the business as usual scenario. Public transport use could fall by 18%, threatening accessibility for those dependent on it, while walking and cycling could fall by 13%, reducing their health benefits. Overall person-km would rise, suggesting a reduction in sustainability. A requirement that all automated cars are shared vehicles could reduce these adverse impacts somewhat, but the effects are sensitive to the charge per km. DiscussionOur use of a single value for each attribute means that our analysis is exploratory, but the size of the resulting impacts demonstrates the importance of understanding the scale of systems response to each of the attributes which we have considered. It will be important to manage the way in which automated cars are introduced into urban areas, if they are not to lead to a worsening of the urban environment, accessibility and health. A requirement to make all such vehicles part of shared fleets offers one way forward, but more work is needed to understand the way in which use of such fleets should be charged.

Developing a novel biofiltration treatment system by coupling high-rate infiltration trench technology with a plug-flow porous-media bioreactor

The sequence of two infiltration steps combined with an intermediate aeration named ‘sequential managed aquifer recharge technology (SMART)’ proved to be a promising approach to replenish groundwater using treated wastewater effluents or impaired surface waters due to efficient inactivation of pathogens and improved removal of many trace organic chemicals. To minimize the physical footprint of such systems and overcome limitations through site-specific heterogeneity at conventional MAR sites, an engineered approach was taken to further advance the SMART concept. This study investigated the establishment of plug-flow conditions in a pilot scale subsurface bioreactor by providing highly controlled hydraulic conditions. Such a system, with a substantially reduced physical footprint in comparison to conventional MAR systems, could be applied independent of local hydrogeological conditions. The desired redox conditions in the bioreactor are achieved by in-situ oxygen delivery, to maintain the homogenous flow conditions and eliminate typical pumping costs. For the time being, this study investigated hydraulic conditions and the initial performance regarding the removal of chemical constituents during baseline operation of the SMARTplus bioreactor. The fit of the observed and simulated breakthrough curves from the pulse injection tracer test indicated successful establishment of plug-flow conditions throughout the bioreactor. The performance data obtained during baseline operation confirmed similar trace organic chemical biotransformation as previously observed in lab- and field-scale MAR systems during travel times of <13 h.

Потоки пылевых частиц в системе Марса

Fluxes of mass and dust particles are calculated, which appear in orbit around Mars due to collisions of meteoroids with Phobos and Deimos. Size distributions of dust particles captured in orbit around Mars are determined. Knowledge of parameters of these particles is important when planning the experimental studies on dust in the system of Mars within the framework of the future space missions.

Scaling factors in HYDRUS to simulate a reduction in hydraulic conductivity during infiltration from recharge wells and infiltration basins

AbstractManaged aquifer recharge (MAR) represents a promising technique to cope with increasing water stress worldwide. However, it can be challenging to operate MAR systems, especially concerning clogging. Clogging reduces the infiltration capacity and system efficiency of a MAR facility. Processes that cause clogging are difficult to quantify and assess, and their simulations in MAR schemes have so far been limited. The variably saturated water flow model HYDRUS‐2D was therefore modified to include time‐variable hydraulic conductivities to more realistically represent clogging at the infiltration interface of infiltration basins and recharge wells. An exponential function with a time‐variable scaling factor was implemented into HYDRUS to vary the soil hydraulic conductivity over time during simulations. The new approach was tested, in combination with the reservoir boundary condition, by simulating two‐dimensional cross‐sections of two three‐dimensional laboratory experiments representing recharge from infiltration basins and injection wells. With the help of the time‐variable scaling factor, the increasing ponding depth in both experiments due to progressive clogging was reproduced. Hypothetical simulations with various well configurations, soils, and injection rates indicate that clogging influences the infiltration volumes and subsurface infiltration area, which should be considered during the planning of MAR systems. The approach can be used to evaluate the resulting infiltration capacity numerically and to help with the operation and design of MAR facilities. However, further research is required to fully understand and integrate the processes that lead to clogging at MAR facilities into numerical simulations.

Cytotoxicity, Docking Study of New Fluorinated Fused Pyrimidine Scaffold: Thermal and Microwave Irradiation Synthesis.

Azolopyrimidines are imposed on the arena of drugs treated for cancer. The urgent need to discover new selective anticancer agents, paved the way to explore the antitumor significance of such fused systems. From the synthetic point of view, Microwave facilitated technique for synthesis is very strongly associated with green method in chemistry field. Our aim is to synthesize bioactive compounds using docking simulation run by MOE program to explore the binding mode of the most active enzyme inhibitor among the target compounds. In addition to the use of conventional heating, the MARS system of CEM utilized for Microwave irradiation that is equipped with a multi-mode platform with a magnetic stirring plate and a rotor that allows the parallel processing of many vessels per batch. All the synthesized compounds were tested for their anticancer activity against hepatic cancer (HepG-2), breast cancer (MCF-7) and colon cancer (HCT-116). Screening against the cancer cell lines was performed, using doxorubicin as a reference drug. Docking studies were conducted using MOE software. A novel series of fluorinated fused-pyrimidine namely, pyrazolopyrimidine, triazolopyrimidine and pyrimidobenzimidazole were designed and synthesized conventionally and under microwave irradiations. The mechanistic pathways as well as the structure of all products were debated and demonstrated based on all possible spectral data. In-vitro examination of the novel prepared derivatives versus the three different human cancer cell lines [hepatic cancer (HepG-2), breast cancer (MCF-7) and colon cancer (HCT-116)] was evaluated to estimate their actual activity. We have developed a simple, facile, and efficient procedure for the formation of new series of azolopyrimidines. All spectra of all products were investigated deliberately to confirm their structures. The anti-cancer activity has been examined against three cancer cell lines e.g. HepG-2, MCF-7 and HCT116. Molecular modeling study was carried out in order to rationalize the in vitro anti-tumor results.

The oldest managed aquifer recharge system in Europe: New insights from the Espino recharge channel (Sierra Nevada, southern Spain)

In Sierra Nevada (southern Spain), the highest mountain range in southern Europe, the application of an ancestral Integrated Water Resources Management system (IWRM), based on the conjunctive use of groundwater and surface water, provides water resources for irrigation and supply in the driest months of the year in this semiarid mountain region. Meltwater is derived from the headwaters of the mountain streams and rivers through a set of uncoated channels excavated in the ground (locally known as acequias de careo) to infiltrate at the upper part of the valleys. Water infiltrated along the acequias de careo slowly flows down the hillsides, through the weathered zone of the hard rock aquifer and the glacial and periglacial sediments. The recharge accomplished through this Managed Aquifer Recharge technique (MAR) activates numerous springs located halfway down the hillside and increases the base flow of the rivers. In this study, focused on a careo channel located on the southern slope of Sierra Nevada called Acequia de El Espino, different archaeological, sedimentological, geophysical and hydrogeological techniques are applied to determine the age and the efficiency of this ancestral example of a MAR and IWRM system. Results suggest that the acequias de careo may be the oldest MAR system in Europe, and that this MAR technique could be applied in other high mountain alpine watersheds to mitigate the effects of climate change.

Assessment of Aerocapture for Orbit Insertion of Small Satellites at Mars

Small satellites may provide a low-cost platform for targeted science investigations in the Mars system. With current technology, small satellites require ride shares with larger orbiters to capture into orbit, limiting the range of orbits available to small satellite mission designers. Successful development of an independent orbit insertion capability for small satellites, using aerocapture, would allow small satellite mission designers to choose the orbit most appropriate for a science investigation while enabling small satellite ride shares on any mission to Mars. A generic small satellite drag-modulation aerocapture system is assessed for use at Mars across a range of approach trajectories and destinations in the Mars system. Analyses include assessment of the sensitivity of the entry corridor size over different atmospheric conditions, a comparison of velocity-trigger and numerical predictor-corrector guidance schemes for drag modulation, and aerocapture flight performance assessment via Monte Carlo techniques. A special focus is placed on four baseline missions: a low-altitude Mars mapping orbit, Phobos and Deimos flyby/rendezvous, and areosynchronous orbit. Results indicate that aerocapture may decrease the orbit insertion system mass fraction by 30% or more with respect to fully propulsive options.

Dusty plasma interactions near the Moon and in the system of Mars

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Survey of Mars Ballistic Capture Trajectories Using Periodic Orbits as Generating Mechanisms

A systematic approach is devised to find ballistic captures in the planar elliptic restricted three-body problem. Simple symmetric periodic orbits around the smaller primary in the circular problem are used as generators for ballistic captures. Combining a scaling factor that maps states from the circular to the elliptic model, and restricting the motion to emanate from periodic solutions, the search space for ballistic capture is reduced to three dimensions. Results in the Sun–Mars system indicate an abundance of long-duration, regular solutions with a variety of characteristics, including low osculating eccentricities. A large-scale survey is completed using three families of periodic orbits encompassing more than 2600 periodic solutions. Discretizing over the mapping parameter, the Mars true anomaly, and the generating periodic orbits, 37 million ballistic captures are evaluated and classified for potential use. The existence of sample solutions into a high-fidelity ephemeris model is evidenced.

Mission analysis for the Martian Moons Explorer (MMX) mission

Mars Moon eXplorer (MMX) is JAXA's next candidate flagship mission to be launched in the early 2020s. MMX will explore the Martian moons and return a sample from Phobos. This paper presents the mission analysis work, focusing on the transfer legs and comparing several architectures, such as hybrid options with chemical and electric propulsion modules. The selected baseline is a chemical-propulsion Phobos sample return, which is discussed in detail with the launch- and return-window analysis. The trajectories are optimized with the jTOP software, using planetary ephemerides for Mars and the Earth; Earth re-entry constraints are modeled with simple analytical equations. Finally, we introduce an analytical approximation of the three-burn capture strategy used in the Mars system. The approximation can be used together with a Lambert solver to quickly determine the transfer Δv costs.

MarsSI: Martian surface data processing information system

MarsSI (Acronym for Mars System of Information, https://emars.univ-lyon1.fr/MarsSI/) is a web Geographic Information System application which helps managing and processing martian orbital data. The MarsSI facility is part of the web portal called PSUP (Planetary SUrface Portal) developed by the Observatories of Paris Sud (OSUPS) and Lyon (OSUL) to provide users with efficient and easy access to data products dedicated to the martian surface. The portal proposes 1) the management and processing of data thanks to MarsSI and 2) the visualization and merging of high level (imagery, spectral, and topographic) products and catalogs via a web-based user interface (MarsVisu). The portal PSUP as well as the facility MarsVisu is detailed in a companion paper (Poulet et al., 2018). The purpose of this paper is to describe the facility MarsSI. From this application, users are able to easily and rapidly select observations, process raw data via automatic pipelines, and get back final products which can be visualized under Geographic Information Systems. Moreover, MarsSI also contains an automatic stereo-restitution pipeline in order to produce Digital Terrain Models (DTM) on demand from HiRISE (High Resolution Imaging Science Experiment) or CTX (Context Camera) pair-images. This application is funded by the European Union's Seventh Framework Programme (FP7/2007–2013) (ERC project eMars, No. 280168) and has been developed in the scope of Mars, but the design is applicable to any other planetary body of the solar system.

The Small Mars System

The Small Mars System is a proposed mission to Mars. Funded by the European Space Agency, the project has successfully completed Phase 0. The contractor is ALI S.c.a.r.l., and the study team includes the University of Naples “Federico II”, the Astronomical Observatory of Capodimonte and the Space Studies Institute of Catalonia. The objectives of the mission are both technological and scientific, and will be achieved by delivering a small Mars lander carrying a dust particle analyser and an aerial drone. The former shall perform in situ measurements of the size distribution and abundance of dust particles suspended in the Martian atmosphere, whereas the latter shall demonstrate low-altitude flight in the rarefied planetary environment. The mission-enabling technology is an innovative umbrella-like heat shield, known as IRENE, developed and patented by ALI. The mission is also a technological demonstration of the shield in the upper atmosphere of Mars. The core characteristics of SMS are the low cost (120M€) and the small size (320kg of wet mass at launch, 110kg at landing), features which stand out with respect to previous Mars landers. To comply with them is extremely challenging at all levels, and sets strict requirements on the choice of the materials, the sizing of payloads and subsystems, their arrangement inside the spacecraft and the launcher's selection. In this contribution, the mission and system concept and design are illustrated and discussed. Special emphasis is given to the innovative features and to the challenges faced in the development of the work.

Trace organic chemical attenuation during managed aquifer recharge: Insights from a variably saturated 2D tank experiment

Meaningful model-based predictions of water quality and quantity are imperative for the designed footprint of managed aquifer recharge installations. A two-dimensional (2D) synthetic MAR system equipped with automated sensors (temperature, water pressure, conductivity, soil moisture, oxidation-reduction potential) and embedded water sampling ports was used to test and model fundamental subsurface processes during surface spreading managed aquifer recharge operations under controlled flow and redox conditions at the meso-scale. The fate and transport of contaminants in the variably saturated synthetic aquifer were simulated using the finite element analysis model, FEFLOW. In general, the model concurred with travel times derived from contaminant breakthrough curves at individual sensor locations throughout the 2D tank. However, discrepancies between measured and simulated trace organic chemical concentrations (i.e., carbamazepine, sulfamethoxazole, tris (2-chloroethyl) phosphate, trimethoprim) were observed. While the FEFLOW simulation of breakthrough curves captured overall shapes of trace organic chemical concentrations well, the model struggled with matching individual data points, although compound-specific attenuation parameters were used. Interestingly, despite steady-state operation, oxidation-reduction potential measurements indicated temporal disturbances in hydraulic properties in the saturated zone of the 2D tank that affected water quality.

Extracorporeal liver support of liver failure

Extracorporeal liver support can be classified into cell-free, artificial methods (artificial liver support, ALS) and cell-based bioartificial methods (bioartificial liver support, BLS). ALS improves biochemical parameters of liver failure by the simultaneous removal of protein-bound and water-soluble substances. Here, the MARS therapy belongs to the most studied methods with a proved beneficial effect on hepatic encephalopathy (HE), hepatorenal syndrome (HRS) or hyperbilirubinemia. However, a general survival advantage of any liver support for liver failure has not been shown yet and is restricted to meta-analyses or patient subgroups. There are no prospective randomized studies on the treatment of liver failure by intoxication. However, several case series report positive treatment effects using the MARS system, particularly in mushroom poisoning or acetaminophen intoxication. In acute liver failure (ALF) studies, the usage of BLS showed no survival advantage. Using ALS systems, a positive effect on mortality could be demonstrated in patient subgroups after several consecutive MARS therapies. The first randomized controlled trial demonstrating a survival benefit used large-volume plasmapheresis. Apparently, immunomodulatory and hemodynamic effects of the treatment play a crucial role in this context. In patients with acute-on-chronic liver failure (ACLF) accompanied by hyperbilirubinemia without any further organ failure (singular hepatic dysfunction), prognostic favorable effects by using a BLS system have been shown. However, once other extrahepatic organ systems are affected, indicating a progressive transition to multi-organ failure, a survival advantage could be achieved with the MARS and Prometheus system. Decisive for a successful therapy is the exact indication of the respective liver dialysis procedure for this very heterogeneous disease. Future studies are needed to define more accurate patient selection criteria for each liver support.

Feasibility of two low-cost organic substrates for inducing denitrification in artificial recharge ponds: Batch and flow-through experiments

Anaerobic batch and flow-through experiments were performed to assess the capacity of two organic substrates to promote denitrification of nitrate-contaminated groundwater within managed artificial recharge systems (MAR) in arid or semi-arid regions. Denitrification in MAR systems can be achieved through artificial recharge ponds coupled with a permeable reactive barrier in the form of a reactive organic layer. In arid or semi-arid regions, short-term efficient organic substrates are required due to the short recharge periods. We examined the effectiveness of two low-cost, easily available and easily handled organic substrates, commercial plant-based compost and crushed palm tree leaves, to determine the feasibility of using them in these systems. Chemical and multi-isotopic monitoring (δ15NNO3, δ18ONO3, δ34SSO4, δ18OSO4) of the laboratory experiments confirmed that both organic substrates induced denitrification. Complete nitrate removal was achieved in all the experiments with a slight transient nitrite accumulation. In the flow-through experiments, ammonium release was observed at the beginning of both experiments and lasted longer for the experiment with palm tree leaves. Isotopic characterisation of the released ammonium suggested ammonium leaching from both organic substrates at the beginning of the experiments and pointed to ammonium production by DNRA for the palm tree leaves experiment, which would only account for a maximum of 15% of the nitrate attenuation. Sulphate reduction was achieved in both column experiments. The amount of organic carbon consumed during denitrification and sulphate reduction was 0.8‰ of the total organic carbon present in commercial compost and 4.4% for the palm tree leaves. The N and O isotopic fractionation values obtained (εN and εO) were −10.4‰ and −9.0‰ for the commercial compost (combining data from both batch and column experiments), and −9.9‰ and −8.6‰ for the palm tree column, respectively. Both materials showed a satisfactory capacity for denitrification, but the palm tree leaves gave a higher denitrification rate and yield (amount of nitrate consumed per amount of available C) than commercial compost

Antagonistic autoregulation speeds up a homogeneous response in Escherichia coli.

By integrating positive and negative feedback loops, biological systems establish intricate gene expression patterns linked to multistability, pulsing, and oscillations. This depends on the specific characteristics of each interlinked feedback, and thus one would expect additional expression programs to be found. Here, we investigate one such program associated with an antagonistic positive and negative transcriptional autoregulatory motif derived from the multiple antibiotic resistance (mar) system of Escherichia coli. We studied the dynamics of the system by combining a predictive mathematical model with high-resolution experimental measures of the response both at the population and single-cell level. We show that in this motif the weak positive autoregulation does not slow down but rather enhances response speedup in combination with a strong negative feedback loop. This balance of feedback strengths anticipates a homogeneous population phenotype, which we corroborate experimentally. Theoretical analysis also emphasized the specific molecular properties that determine the dynamics of the mar phenotype. More broadly, response acceleration could provide a rationale for the presence of weak positive feedbacks in other biological scenarios exhibiting these interlinked regulatory architectures.

Winter Maintenance Wash-Water Heavy Metal Removal Pilot Scale Evaluation

To encourage sustainable engineering practices, departments of transportation are interested in reusing winter maintenance truck wash water as part of their brine production and future road application. Traffic-related metals in the wash water, however, could limit this option. The objective of this work was to conduct a pilot scale evaluation of heavy metal (copper, zinc, iron, and lead) removal in a filtration unit (maximum flow rate of 45 L/minute) containing proprietary (MAR Systems Sorbster®) media. Three different trials were conducted and approximately 10,000 L of wash water collected from a winter maintenance facility in Ohio was treated with the pilot unit. Lab studies were also performed on six wash-water samples from multiple facilities to assess particle size removal and estimate settling time as a potential removal mechanism during wash-water storage. Pilot unit total metal removal efficiencies were 79%, 77%, 63%, and 94% for copper, zinc, iron, and lead, respectively. Particle settling calculation estimates for copper and zinc show that 10 hours in storage can also effectively reduce heavy metal concentrations in winter maintenance wash water in excess of 70%. These pilot scale results show promise for reducing heavy metal concentrations to an acceptable level for reuse.

Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in a Dune Sand Aquifer in Western Saudi Arabia: Assessment of Evaporation Loss for Design of an MAR System

A component of designing a managed aquifer recharge system in a dune aquifer is the control of diffusive evaporative loss of water which is governed by the physical properties of the sediments and the position of the water table. A critical water table position is the “extinction depth”, below which no further loss of water occurs via diffusion. Field experiments were conducted to measure the extinction depth of sediments taken from a typical dune field in the region. The soil grain size characteristics, laboratory porosity, and saturated hydraulic conductivity were measured. The sand is classified as well-sorted, very fine sand with a mean grain diameter of 0.15 mm. Soil moisture gradients and diffusion loss rates were measured using sensors in a non-weighing lysimeter that was placed below land surface. The sand was saturated carefully with water from the bottom to the top and was exposed to the natural climate for a period of about two months. The moisture gradient showed a gradual decline during measurement until extinction depth was reached at about 100 cm below surface after 56 days. Diurnal temperature changes were observed in the upper 75 cm of the column and were negligible at greater depth.