Investigating the Coating Effect on Charge Transfer Mechanisms in Composite Electrodes for Lithium-Ion Batteries

The performance of lithium-ion batteries (LIBs) relies on the characteristics of the cathode material, including both intentionally applied coatings and naturally formed surface layers or binder adhesion. This study investigated the influence of the ion-permeable surface fraction, distribution, and characteristics of the coating on the performance of a lithium iron phosphate (LFP) electrode material. We developed an extended Newman-type half-cell model and examined the impact of coating parameters on the galvanostatic discharge curves of the LFP electrode material. The study found that the ion-permeable surface fraction has a significant influence on the diffusion and charge transfer characteristics of the electrode material. A decrease in the ion-permeable surface fraction leads to a decrease in the measured diffusion coefficients and to an increase in the overall coating resistance of the electrode material. Interestingly, the distribution of the ion-permeable surface also plays a role in the diffusion characteristics, with a coarsely dispersed coating resulting in lower diffusion coefficients. Additionally, the coating characteristics significantly affect the polarization and capacity of the electrode material at different C-rates. The model was used to approximate the experimental discharge curves of the LFP-based composite electrodes with two different compositions, and the simulated data showed satisfactory agreement with the experiment. Thus, we believe that the developed model and its further extension will be useful in numerical simulations that aim to facilitate the search for optimal compositions.

Transient HCl in the atmosphere of Mars

A major quest in Mars' exploration has been the hunt for atmospheric gases, potentially unveiling ongoing activity of geophysical or biological origin. Here, we report the first detection of a halogen gas, HCl, which could, in theory, originate from contemporary volcanic degassing or chlorine released from gas-solid reactions. Our detections made at ~3.2 to 3.8 μm with the Atmospheric Chemistry Suite and confirmed with Nadir and Occultation for Mars Discovery instruments onboard the ExoMars Trace Gas Orbiter, reveal widely distributed HCl in the 1- to 4-ppbv range, 20 times greater than previously reported upper limits. HCl increased during the 2018 global dust storm and declined soon after its end, pointing to the exchange between the dust and the atmosphere. Understanding the origin and variability of HCl shall constitute a major advance in our appraisal of martian geo- and photochemistry.

Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season

The loss of water from Mars to space is thought to result from the transport of water to the upper atmosphere, where it is dissociated to hydrogen and escapes the planet. Recent observations have suggested large, rapid seasonal intrusions of water into the upper atmosphere, boosting the hydrogen abundance. We use the Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter to characterize the water distribution by altitude. Water profiles during the 2018-2019 southern spring and summer stormy seasons show that high-altitude water is preferentially supplied close to perihelion, and supersaturation occurs even when clouds are present. This implies that the potential for water to escape from Mars is higher than previously thought.

Publisher Correction: Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

The surname of author Cathy Quantin-Nataf was misspelled 'Quantin-Nata' , authors Ehouarn Millour and Roland Young were missing from the ACS Science Team list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.

Publisher Correction: No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

The surname of author Cathy Quantin-Nataf was misspelled 'Quantin-Nata', authors Ehouarn Millour and Roland Young were missing from the ACS and NOMAD Science Teams list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.

Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Global dust storms on Mars are rare^1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere³, primarily owing to solar heating of the dust³. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars⁴. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes^5,6, as well as a decrease in the water column at low latitudes^7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H₂O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H₂O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals³. The observed changes in H₂O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.

No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today¹. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations^2-5. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere^6,7, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane^1,6,8. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections^2,4. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater⁴ would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally.

Infrared Spectrometer for ExoMars: A Mast-Mounted Instrument for the Rover

ISEM (Infrared Spectrometer for ExoMars) is a pencil-beam infrared spectrometer that will measure reflected solar radiation in the near infrared range for context assessment of the surface mineralogy in the vicinity of the ExoMars rover. The instrument will be accommodated on the mast of the rover and will be operated together with the panoramic camera (PanCam), high-resolution camera (HRC). ISEM will study the mineralogical and petrographic composition of the martian surface in the vicinity of the rover, and in combination with the other remote sensing instruments, it will aid in the selection of potential targets for close-up investigations and drilling sites. Of particular scientific interest are water-bearing minerals, such as phyllosilicates, sulfates, carbonates, and minerals indicative of astrobiological potential, such as borates, nitrates, and ammonium-bearing minerals. The instrument has an ∼1° field of view and covers the spectral range between 1.15 and 3.30 μm with a spectral resolution varying from 3.3 nm at 1.15 μm to 28 nm at 3.30 μm. The ISEM optical head is mounted on the mast, and its electronics box is located inside the rover's body. The spectrometer uses an acousto-optic tunable filter and a Peltier-cooled InAs detector. The mass of ISEM is 1.74 kg, including the electronics and harness. The science objectives of the experiment, the instrument design, and operational scenarios are described. Key Words: ExoMars-ISEM-Mars-Surface-Mineralogy-Spectroscopy-AOTF-Infrared. Astrobiology 17, 542-564.

Development of a space-borne spectrometer to monitor atmospheric ozone

A new compact satellite spectrometer dedicated to monitoring terrestrial atmospheric ozone (ozonometer) is in preparation for the Russian Geophysics Program. Four instruments at four satellites (Ionosphere) are intended to monitor the total ozone content by measuring spectra of scattered solar radiation in nadir. The spectrometer is based on the Rowland scheme with a concave holographic diffraction grating. It covers the near UV and visible range of the spectrum, 300-500 nm, with a spectral resolution of ∼0.3  nm. At present, a qualification model has been manufactured and tested. We introduce the description of the instrument and the results of laboratory and ground-based atmospheric calibrations. The ozone amount retrieved from atmospheric measurements using the differential optical absorption spectroscopy (DOAS) method is in good agreement with that measured by the collocated Brewer spectrophotometer and ozone monitoring instrument on board the Aura satellite.

Compact echelle spectrometer for occultation sounding of the Martian atmosphere: design and performance

The echelle spectrometer TIMM-2 is the instrument developed for the unsuccessful Russian mission Phobos-Grunt. The instrument was dedicated to solar occultation studies of the Martian atmosphere by measuring the amount of methane, by sensitive measuring of other minor constituents, and by profiling the D/H ratio and the aerosol structure. The spectral range of the instrument is 2300-4100 nm, the spectral resolving power λ/Δλ exceeds 25,000, and the field of view is 1.5×21 arc min. The spectra are measured in narrow spectral intervals, corresponding to discreet diffraction orders. One measurement cycle includes several spectral intervals. To study the vertical profiles of aerosol, the instrument incorporates four photometers in the UV to near-IR spectral range. The mass of the instrument is 2800 g, and its power consumption is 12 W. One complete flight model remains available after the Phobos-Grunt launch. We discuss the science objectives of the occultation experiment for the case of Mars, the implementation of the instrument, and the results of ground calibrations.

[Potential of impression cytology in diagnosis and evaluation of efficacy of pharmacological correction of dry eye syndrome associated with contact lens wearing]

Potential of impression cytology in diagnosis and evaluation of efficacy of pharmacological correction of dry eye syndrome (DES) associated with contact lens wearing was studied. When wearing contact lenses for a long time DES with tear film instability and reduction of tear production occurs in more than 50% patients. Morphological changes of epithelium of tarsal and bulbar conjunctiva manifest consequently. Impression cytology reveals structural damage of epithelium with keratinization signs and decrease of goblet cells density down to total absence. After tear substitution therapy tear break-up time increased by 65,3% and total tear production by 11,4%. In control impression cytology of tarsal and bulbar conjunctiva during tear substitution therapy the following changes were revealed: recovery of goblet cells density and differentiation, recovery of epithelial structure and reduction of epithelium keratinization.

[Detection of sodium monourate crystals in biopsies of gastric mucosa in patients with gout]

AIM

To examine gastric biopsies with polarization microscopy for detection of sodium monourate crystals (SMC).

MATERIAL AND METHODS

The trial included 20 patients with gout diagnosis (mean age 55.7 years, mean duration of the disease 12.3 years) in whom esophagogastroduodenoscopy was made with biopsy of gastric mucosa from the antral part of the stomach and middle third of the gastric body.

RESULTS

Crystals in the biopsy specimens were detected in 11 of 20 examinees. The crystals were characterized by strong double refraction, length 3-20 mcm, acicular or planiform shape, blue or yellow color depending on position in compensated polarized light. Quantitative distribution of the crystals within one biopsy specimen was uneven and varied from solitary crystals to clusters of 70-80 crystals in sight, up to formation of tophus-like structures. Clinical picture in detection of SMC was characterized by more frequent occurrence of cases with subcutaneous tophuses of various location combined with higher hyperuricemia.

CONCLUSION

One of the essential lines in the research of gout concerns mechanisms of SMC formation in organs and tissues and microcrystalline gastroduodenal inflammation. Methods of correction of this inflammation are to be designed.

[Cytogenetic changes in peripheral blood lymphocytes in people with impaired thyroid status]

Increased counts of cells with chromosome aberrations were revealed in peripheral blood lymphocytes of subjects with thyroid dysfunction: 5.5 +/- 0.6% in hypothyrosis, 9.0 +/- 1.8% in hyperthyroidism, and 2.5 +/- 0.1% in controls (20 donors). The aberrations are mainly presented by paired and solitary fragments, rarely by chromatid translocations; in two patients with hyperthyroidism dicentrics were detected. Distribution of aberration types varied. In hypothyrosis chromosome aberrations were two times more incident than chromatid ones. In hyperthyroidism chromosome and chromatid aberrations were approximately equally incident. These results may be used to explain the causes of unfavorable outcomes of pregnancy in patients with thyroid diseases.

[Effect of thyroxine in the G0 stage of the cell cycle on the yield of chromosome aberrations in rat hepatocytes and human lymphocytes after X-irradiation]

A study was made of the mechanism of a modifying action of thyroxin (T4) on the chromosome integrity after the application thereof in vivo and in vitro following a single whole-body exposure to X-radiation with a dose of 2.19 Gy. It is concluded that T4 influences the quantity of cells with chromosome aberrations stimulating the recovery of the chromosome integrity: the stimulation can be brought about at the G0 stage of the cell cycle as a result of the direct effect of the hormone on a cell.

[Effect of thyroxine on the integrity of chromosomes]

Some features of the mechanism of thyroxin (T4) mutagenic effect in the culture of the human peripheral blood lymphocytes and the rat liver in vivo were studied. It was shown, that T4 mutagenic effect, discovered previously in the entire organism, can be stipulated by direct hormone-cell interaction. T4 mutagenic effect is associated with a change in DNA-dependent RNA polymerase activity and is realized during different phases of the cellular cycle. T4 modifying influence upon chromosome entirety is substantially limited by the age.