First Hard X-Ray Imaging Results by Solar Orbiter STIX

The Spectrometer/Telescope for Imaging X-rays (STIX) is one of six remote sensing instruments on-board Solar Orbiter. The telescope applies an indirect imaging technique that uses the measurement of 30 visibilities, i.e., angular Fourier components of the solar flare X-ray source. Hence, the imaging problem for STIX consists of the Fourier inversion of the data measured by the instrument. In this work, we show that the visibility amplitude and phase calibration of 24 out of 30 STIX sub-collimators has reached a satisfactory level for scientific data exploitation and that a set of imaging methods is able to provide the first hard X-ray images of solar flares from Solar Orbiter. Four visibility-based image reconstruction methods and one count-based are applied to calibrated STIX observations of six events with GOES class between C4 and M4 that occurred in May 2021. The resulting reconstructions are compared to those provided by an optimization algorithm used for fitting the amplitudes of STIX visibilities. We show that the five imaging methods produce results morphologically consistent with the ones provided by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory (SDO/AIA) in UV wavelengths. The χ2 values and the parameters of the reconstructed sources are comparable between methods, thus confirming their robustness

ALP enzymatic activity related to different implant surface microtopographies

The aim of this study was an in vitro investigation of the Alkaline Phosphatase (ALP) enzymatic activity related to different surface treatments applied to ten implant systems in order to assess if the interaction between cells and implant (osteoblastic proliferation and differentiation) was influenced by the surface structure and/or surface composition of the fixture. The originality of this study was that all implants were tested as manufactured for clinical use. The implant systems object of this study divided by the surface treatment were the following: Machined: Mk III Branemark; Sandblasted: Ankylos, Silhouette and Galant (experimental fixture); Etched: Osseotite, Mac System,MK 4 (experimental fixture), ITI; Oxided: Ti Unite, Pilot. We used Sa-OS2 cultured osteoblasts and we analyzed n14 fixtures for each implant system (n11 fixture for the cellular growth curve and n13 fixtures for the ALP activity). After 14 days the assay for the ALP activity was carried out according to Wataha et al. (JBMR, 1997) After the cellular growth evaluation in a Burker\u2019s hemocytometer chamber we quantify by a spectrophotometer at 405nm the absorbance value for each sample (the absorbance value indicate the amount of the conversion by ALP of the P-Nitro-Phenyl-Phosphate into P-Nitro-Phenol) and we corrected the mean value for cell number determined before. The data were statistically analyzed by ANOVA and Post hoc Scheffe` Test. Within the limits of the in vitro investigations we can conclude that: The etched surfaces shown more cellular growth than others. The sandblasted surfaces shown the smallest amount of cellular proliferation but a very high differentiation (according to Postiglione et al 2003 that found an inverse correlation between the two factors) We found a statistically significant difference in ALP activity only between oxided and etched surfaces (p < 0.05) The sandblasted and oxided surfaces shown more osteoblastic differentiation (more ALP enzymatic activity) Themachined surface is competitive, as regard the osteoblastic differentiation, with the rougher surfaces. Actually it\u2019s still difficult to recommend a particular rougher surface