130 research outputs found
Models of dust around Europa and Ganymede
We use numerical models, supported by our laboratory data, to predict the
dust densities of ejecta outflux at any altitude within the Hill spheres of
Europa and Ganymede. The ejecta are created by micrometeoroid bombardment and
five different dust populations are investigated as sources of dust around the
moons. The impacting dust flux (influx) causes the ejection of a certain amount
of surface material (outflux). The outflux populates the space around the
moons, where a part of the ejecta escapes and the rest falls back to the
surface. These models were validated against existing Galileo DDS (Dust
Detector System) data collected during Europa and Ganymede flybys.
Uncertainties of the input parameters and their effects on the model outcome
are also included. The results of this model are important for future missions
to Europa and Ganymede, such as JUICE (JUpiter ICy moon Explorer), recently
selected as ESA's next large space mission to be launched in 2022
Diversity of new Martian crater clusters informs meteoroid atmospheric interactions
We investigated 634 crater clusters on Mars detected between 2007 and 2021,
which represent more than half of all impacts discovered in this period. Crater
clusters form when meteoroids in the 10 kg to 10 ton mass range break-up in
Mars' atmosphere to produce a few to a few hundred fragments that hit the
ground. The properties of the clusters can inform our understanding of
meteoroid properties and the processes that govern their fragmentation. We
mapped individual craters 1 m within each cluster and defined a range of
cluster properties based on the spatial and size distributions of the craters.
The large data set, with over eight times more cluster observations than
previous work, provides a more robust statistical investigation of crater
cluster parameters and their correlations. Trends in size, dispersion and large
crater fraction with elevation support weak atmospheric filtering of material.
The diversity in the number of individual craters within a cluster, and their
size-frequency distributions, may reflect either a diversity in fragmentation
style, fragility or internal particle sizes.Comment: 12 pages, 12 figures at the en
Effect of mebendazole on fibrosarcoma in hamsters
Purpose: To investigate the effect of mebendazole on an in vivo solid tumor model of fibrosarcoma in hamsters.Methods: 24 Syrian golden hamsters of both sexes with the approximate bodyĀ weight of 100g were randomly distributed in 2 experimental and 2 control groups, with 6 animals in each group. BHK-21/C13 cells (2 x 106) in 1 mL Glasgow Minimum Essential Medium (GMEM) were injected subcutaneously into the back of each animal in 3 groups. The experimental groups were treated with mebendazoleĀ (460 mg/kg) via a gastric tube on a daily basis, immediately after tumor inoculation. In addition, one experimental group received deoxycholic acid 20 mg/kg once a day. After 2 weeks, when the tumors were approximately 1 - 2 cm in the control group, all the animals were sacrificed, and their blood collected for laboratory analysis. The tumors were excised, their weight and diameters measured, and the volumesĀ calculated. The tumor samples were histopathologically assessed and the main organs toxicologically analyzed. Images were taken and processed by an imaging software, and Ki-67-positive cells in the tumor samples were quantified.Results: Mebendazole diminished tumor mitosis from 18.5 Ā± 3.02 to 13.5 Ā± 3.45 (p < 0.05), vasculature and tissue penetration, and increased necroses in tumorĀ slices. Tumor volume and weight were insignificantly attenuated. Toxicity was not observed.Conclusion: Mebendazole might be an effective non-toxic agent in sarcoma therapy.Keywords: Mebendazole, Hamsters, BHK-21/C13 cells, Fibrosarcoma therapy,Ā Tumor mitosi
Seismic Efficiency for Simple Crater Formation in the Martian Top Crust Analog
The first seismometer operating on the surface of another planet was deployed by the NASA InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission to Mars. It gives us an opportunity to investigate the seismicity of Mars, including any seismic activity caused by small meteorite bombardment. Detectability of impact generated seismic signals is closely related to the seismic efficiency, defined as the fraction of the impactor's kinetic energy transferred into the seismic energy in a target medium. This work investigated the seismic efficiency of the Martian near surface associated with small meteorite impacts on Mars. We used the iSALEā2D (ImpactāSimplified Arbitrary Lagrangian Eulerian) shock physics code to simulate the formation of the meterāsize impact craters, and we used a recently formed 1.5 m diameter crater as a case study. The Martian crust was simulated as unfractured nonporous bedrock, fractured bedrock with 25% porosity, and highly porous regolith with 44% and 65% porosity. We used appropriate strength and porosity models defined in previous works, and we identified that the seismic efficiency is very sensitive to the speed of sound and elastic threshold in the target medium. We constrained the value of the impactārelated seismic efficiency to be between the order of ā¼10ā7 to 10ā6 for the regolith and ā¼10ā4 to 10ā3 for the bedrock. For new impacts occurring on Mars, this work can help understand the nearāsurface properties of the Martian crust, and it contributes to the understanding of impact detectability via seismic signals as a function of the target media
Large impact cratering during lunar magma ocean solidification
The lunar cratering record is used to constrain the bombardment history of both the Earth and the Moon. However, it is suggested from different perspectives, including impact crater dating, asteroid dynamics, lunar samples, impact basin-forming simulations, and lunar evolution modelling, that the Moon could be missing evidence of its earliest cratering record. Here we report that impact basins formed during the lunar magma ocean solidification should have produced different crater morphologies in comparison to later epochs. A low viscosity layer, mimicking a melt layer, between the crust and mantle could cause the entire impact basin size range to be susceptible to immediate and extreme crustal relaxation forming almost unidentifiable topographic and crustal thickness signatures. Lunar basins formed while the lunar magma ocean was still solidifying may escape detection, which is agreeing with studies that suggest a higher impact flux than previously thought in the earliest epoch of Earth-Moon evolution
Supplementary data for the article: BjelogrliÄ, S. K.; TodoroviÄ, T. R.; KojiÄ, M.; SenÄanski, M.; NikoliÄ, M.; ViÅ”njevac, A.; AraÅ”kov, J.; MiljkoviÄ, M.; Muller, C. D.; FilipoviÄ, N. R. Pd(II) Complexes with N-Heteroaromatic Hydrazone Ligands: Anticancer Activity, in Silico and Experimental Target Identification. Journal of Inorganic Biochemistry 2019, 199. https://doi.org/10.1016/j.jinorgbio.2019.110758
Supplementary material for: [10.1016/j.jinorgbio.2019.110758]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3318
Metamizole: Current status of the safety and efficacy
Metamizole is a nonsteroidal anti-inflammatory drug, with analgesic, antipyretic, spasmolytic, and weak anti-inflammatory properties. The analgesic effect of metamizole seems to be based on the inhibition of cyclooxygenase enzyme activity and stimulation of cannabinoid receptors. Its use is still controversial, mainly due to agranulocytosis, metamizole-induced serious adverse reaction. While in many countries it is withdrawn from the market, in some countries metamizole is available as a medication prescribed for strictly defined indications, while in the others like Mexico, Brazil and China it can be obtained as an Over-The-Counter drug. The most common adverse effects of metamizole are the skin and subcutaneous tissue disorders. Metamizole appears to be of similar efficacy to analgesics which are frequently used in the treatment of moderate to severe postoperative pain
Statistical analysis of fireballs: Seismic signature survey
Fireballs are infrequently recorded by seismic sensors on the ground. If recorded, they are usually reported as one-off events. This study is the first seismic bulk analysis of the largest single fireball data set, observed by the Desert Fireball Network (DFN) in Australia in the period 2014-2019. The DFN typically observes fireballs from cm-m scale impactors. We identified 25 fireballs in seismic time series data recorded by the Australian National Seismograph Network (ANSN). This corresponds to 1.8% of surveyed fireballs, at the kinetic energy range of 106-1010 J. The peaks observed in the seismic time series data were consistent with calculated arrival times of the direct airwave or ground-coupled Rayleigh wave caused by shock waves by the fireball in the atmosphere (either due to fragmentation or the passage of the Mach cone). Our work suggests that identification of fireball events in the seismic time series data depends on both physical properties of a fireball (such as fireball energy and entry angle in the atmosphere) and the sensitivity of a seismic instrument. This work suggests that fireballs are likely detectable within 200 km direct air distance between a fireball and seismic station, for sensors used in the ANSN. If each DFN observatory had been accompanied by a seismic sensor of similar sensitivity, 50% of surveyed fireballs could have been detected. These statistics justify the future consideration of expanding the DFN camera network into the seismic domain
The Seismic Moment and Seismic Efficiency of Small Impacts on Mars
Since landing in late 2018, the InSight lander has been recording seismic signals on the surface of Mars. Despite nominal prelanding estimates of one to three meteorite impacts detected per Earth year, none have yet been identified seismically. To inform revised detectability estimates, we simulated numerically a suite of small impacts onto Martian regolith and characterized their seismic source properties. For the impactor size and velocity range most relevant for InSight, crater diameters are 1ā30 m. We found that in this range scalar seismic moment is 106ā1010 Nm and increases almost linearly with impact momentum. The ratio of horizontal to vertical seismic moment tensor components is ā¼1, implying an almost isotropic PĀ wave source, for vertical impacts. Seismic efficiencies are ā¼10ā6, dependent on the target crushing strength and impact velocity. Our predictions of relatively low seismic efficiency and seismic moment suggest that meteorite impact detectability on Mars is lower than previously assumed. Detection chances are best for impacts forming craters of diameter >10 m
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