Understanding the true nature of extra-terrestrial water and organic matter that were present at the birth of our solar system, and their subsequent evolution, necessitates the study of pristine ...astromaterials. In this study, we have studied both the water and organic contents from a dust particle recovered from the surface of near-Earth asteroid 25143 Itokawa by the Hayabusa mission, which was the first mission that brought pristine asteroidal materials to Earth's astromaterial collection. The organic matter is presented as both nanocrystalline graphite and disordered polyaromatic carbon with high D/H and
N/
N ratios (δD = + 4868 ± 2288‰; δ
N = + 344 ± 20‰) signifying an explicit extra-terrestrial origin. The contrasting organic feature (graphitic and disordered) substantiates the rubble-pile asteroid model of Itokawa, and offers support for material mixing in the asteroid belt that occurred in scales from small dust infall to catastrophic impacts of large asteroidal parent bodies. Our analysis of Itokawa water indicates that the asteroid has incorporated D-poor water ice at the abundance on par with inner solar system bodies. The asteroid was metamorphosed and dehydrated on the formerly large asteroid, and was subsequently evolved via late-stage hydration, modified by D-enriched exogenous organics and water derived from a carbonaceous parent body.
Solar wind ion irradiation continuously modifies the optical properties of unprotected surfaces of airless bodies in the Solar System. This alteration induces significant biases in the interpretation ...of the spectral data obtained through remote sensing, and it impedes a correct estimation of the composition of the sub-surface pristine materials. However, as the alteration of the surface is a function of time, an in-depth understanding of the phenomenon may provide an original way to estimate the weathering age of a surface. Laboratory experiments show that mid- and far-IR bands are very sensitive to space weathering, as they are significantly modified upon irradiation. These bands can thus constitute a reliable proxy of the time-bound effects of irradiation on an object. We show that the detection of irradiation effects is within the reach of IR spectral resolution of the OSIRIS-REx mission and of the future James Webb Space Telescope. Our results provide a possible evidence for space weathering effects in the IR spectrum of asteroid 101955 Bennu measured by OTES/OSIRIS-REx.
•Laboratory experiments show that IR bands are very sensitive to space weathering.•IR bands are a reliable proxy of the time-bound effects of solar wind irradiation.•Detecting irradiation effects are within the reach of OSIRIS-REx and JWST.•There is evidence of space weathering in the IR spectrum of asteroid Bennu.
Liver stiffness was measured by transient elastography (FibroScan®) in 228 consecutive patients with chronic viral hepatitis, with (115) or without cirrhosis (113), to study its correlations with ...serum transaminases alanine aminotransferase (ALT), fibrosis stage and surrogate noninvasive markers of fibrosis (APRI, FORNS, FibroTest and hyaluronic acid). The dynamic profiles of serum transaminases and liver stiffness were compared by multiple testing in 31 patients during a 6‐month follow‐up. We identified 8.3 and 14 kPa as the fibrosis ≥F2 and cirrhosis cut‐offs, respectively: their sensitivities were 85.2%/78.3%; specificities 90.7%/98.2%; positive predictive values 93.9%/97.8%; negative predictive values 78.8%/81.6%; diagnostic accuracies 87.3%/88.2%. FibroScan® performed better than the other surrogate markers of fibrosis (P < 0.001). Other than fibrosis, other factors independently associated with liver stiffness were ALT for all patients and chronic hepatitis patients (P < 0.001), and 12‐month persistently normal ALT (biochemical remission, P < 0.001) in cirrhotics. In patients with biochemical remission either spontaneous or after antiviral therapy (48 of 228, 21%), liver stiffness was lower than in patients with identical fibrosis stage, but elevated ALT (P < 0.001). The liver stiffness dynamic profiles paralleled those of ALT, increasing 1.3‐ to 3‐fold during ALT flares in 10 patients with hepatitis exacerbations. Liver stiffness remained unchanged in 21 with stable biochemical activity (P = 0.001). In conclusion, transient elastography is a new liver parameter that behaves as a reliable surrogate marker of fibrosis in chronic viral hepatitis patients, provided that its relationship with major changes of biochemical activity is taken into account.
The currently available antiviral treatments (Peg-Interferon-α and Nucleos(t)ide Analogues, NA) for chronic hepatitis B (CHB) achieve a functional cure (serum HBsAg and HDV-DNA clearance) of HBV ...infection in a limited number of patients. Nevertheless, the continuous pharmacological suppression of viral replication by NA halts liver disease progression lowering the risk of HCC development and improving the survival. In the near future, to fully exploit the potential of old and new drugs for HBV treatment a personalized approach to the patients will be required according to an accurate definition of their virologic, immunologic and clinical profile.
Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of ...keV ion energies. Aims. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results. The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions. The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices.
...the administration of siRNAs targeting integrated HBV DNA sequences resulted in significant HBsAg declines. ...in samples obtained at baseline and before starting NAs, measurements of HBV DNA ...serum levels were comparable in standard real‐time polymerase chain reaction (PCR) assays (such as cobas HBV Roche Molecular Diagnostics, Pleasanton, CA or Xpert HBV Cepheid, Maurens‐Scopont, France) and assays able to co‐amplify circulating HBV RNA, either by adding an extra step of RT (cobas HBV plus RT) to real‐time PCR or using a real‐time transcription‐mediated amplification (TMA) (HBV Quant Assay; Hologic, Inc., Marlborough, MA). The abundance of pgRNA serves as a template during the RT amplification step, resulting in the nonspecific overestimation of real HBV DNA copy equivalents. ...the use of the RT step that provides an overboosting of the overall viral load assay sensitivity taking advantage of the additional amplification of pregenomic HBV RNA forms has an advantage in some specific diagnostic settings, such as blood screening in blood banking. ...in this case, the acritical use of a positive result obtained by these assays would lead to the misclassification of patients, resulting in inappropriate clinical decisions.
Significant compositional and structural heterogeneity at nm to mm scales is an important characteristic of primitive extraterrestrial materials. Here, we report the analysis of high‐resolution ...Fourier transform IR hyperspectral imaging analytical measurements at the micron scale on a fragment of the Paris carbonaceous chondrite, supported by Raman and SEM‐EDS measurements. The fragment is crushed in a diamond compression cell. The micro‐FTIR analyses are performed in transmission with two setups, an imaging microscope with a matrix detector using a thermal source and a system using a single point detector coupled with the synchrotron source at the SOLEIL synchrotron facility. We obtain the spatial distribution of chemical/mineralogical components. We confirm at a larger scale (10 μm) the presence of hydrated amorphous silicates observed at a smaller scale (1 μm). Based on the relative abundance of different minerals (hydrated amorphous silicate, olivine, diopside, and serpentine), we propose a sequence of aqueous alteration. Considering the spatial correlation of minerals with organic matter, we discuss the effects of aqueous alteration on the organic matter in bulk. In particular, we detect an increase in the CH2/CH3 ratio in the altered zone and present the possible scenarios that led to the observed chain length shortening/cracking of hydrocarbons.
Representatives from academia, industry, regulatory agencies, and patient groups convened in March 2019 with the primary goal of developing agreement on chronic HBV treatment endpoints to guide ...clinical trials aiming to ‘cure’ HBV. Agreement among the conference participants was reached on some key points. ‘Functional’ but not sterilising cure is achievable and should be defined as sustained HBsAg loss in addition to undetectable HBV DNA 6 months post-treatment. The primary endpoint of phase III trials should be functional cure; HBsAg loss in ≥30% of patients was suggested as an acceptable rate of response in these trials. Sustained virologic suppression (undetectable serum HBV DNA) without HBsAg loss 6 months after discontinuation of treatment would be an intermediate goal. Demonstrated validity for the prediction of sustained HBsAg loss was considered the most appropriate criterion for the approval of new HBV assays to determine efficacy endpoints. Clinical trials aimed at HBV functional cure should initially focus on patients with HBeAg-positive or negative chronic hepatitis, who are treatment-naïve or virally suppressed on nucleos(t)ide analogues. A hepatitis flare associated with an increase in bilirubin or international normalised ratio should prompt temporary or permanent cessation of an investigational treatment. New treatments must be as safe as existing nucleos(t)ide analogues. The primary endpoint for phase III trials for HDV coinfection should be undetectable serum HDV RNA 6 months after stopping treatment. On treatment HDV RNA suppression associated with normalisation of alanine aminotransferase is considered an intermediate goal. In conclusion, regarding HBV ‘functional cure’, the primary goal is sustained HBsAg loss with undetectable HBV DNA after completion of treatment and the intermediate goal is sustained undetectable HBV DNA without HBsAg loss after stopping treatment.
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