Role of heat accumulation in the multi-shot damage of silicon irradiated with femtosecond XUV pulses at a 1 MHz repetition rate

The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV monochromatic radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm². Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm²) and liquid state (54 mJ/cm²), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes

Composés porteurs d'une fonction R-noh (évaluation comme substrats pour la production de monoxyde d'azote (NO) par des voies indépendantes des no-synthases et comme donneurs de No au niveau vasculaire )

STRASBOURG ILLKIRCH-Pharmacie (672182101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

S-Nitrosating Nitric Oxide Donors Induce Long-Lasting Inhibition of Contraction in Isolated Arteries

ABSTRACT The ability of various nitric oxide (NO) donors to induce longlasting inhibition of contraction in isolated arteries was compared. All the studied compounds elicited a relaxant effect in rat aortic rings precontracted with norepinephrine (NE). Almost maximal relaxation was obtained with 1 M of each compound. The S-nitrosating agents S-nitrosoglutathione (GSNO), S-nitroso-N-acetylpenicillamine, S-nitroso-N-acetylcysteine, and sodium nitroprusside (1 M) produced a decrease of the maximal effect of NE that persisted after removal of the drug. This hyporesponsiveness to NE was associated with a relaxant effect of N-acetylcysteine, a low-molecular weight thiol that can displace NO from cysteine-NO bonds. Such modifications of contraction were not observed in aortic rings previously exposed to 1 M S-nitrosocysteine, glyceryl trinitrate, 3-morpholinosydnonimine, or 2-(N,N-diethylamino)-diazenolate-2-oxide (DEA-NO). The same differential effects of GSNO and DEA-NO on contraction were also observed in porcine coronary arteries. Rat aortic rings previously exposed to 100 M GSNO, but not to 100 M DEA-NO, displayed a persistent increase in NO content (determined by NO spin trapping) and cysteine-NO residues (determined by immunostaining with an anti-cysteine-NO antiserum). The GSNO-induced increase in cysteine-NO residues in aortic tissue was prevented by the thiolmodifying agent p-hydroxymercuribenzoic acid. This study shows that in isolated arteries, the effects of S-nitrosating agents differed from those of other NO-donating agents. SNitrosating agents induced a persistent inhibition of contraction, which was attributed to the formation of releasable NO stores by S-nitrosation of tissue thiols. These differential effects of NO donors may be important for orientating their therapeutic indications. Some nitric oxide (NO) donors such as sodium nitroprusside (SNP) or low-molecular weight (LMW) S-nitrosothiols (RSNO) cause long-lasting vasodilatation in vitro (after washing out the drug) or in vivo (after drug elimination

KLK5 and KLK7 Ablation Fully Rescues Lethality of Netherton Syndrome-Like Phenotype

Netherton syndrome (NS) is a severe skin disease caused by the loss of protease inhibitor LEKTI, which leads to the dysregulation of epidermal proteases and severe skin-barrier defects. KLK5 was proposed as a major protease in NS pathology, however its inactivation is not sufficient to rescue the lethal phenotype of LEKTI-deficient mice. In this study, we further elucidated the in vivo roles of the epidermal proteases in NS using a set of mouse models individually or simultaneously deficient for KLK5 and KLK7 on the genetic background of a novel NS-mouse model. We show that although the ablation of KLK5 or KLK7 is not sufficient to rescue the lethal effect of LEKTI-deficiency simultaneous deficiency of both KLKs completely rescues the epidermal barrier and the postnatal lethality allowing mice to reach adulthood with fully functional skin and normal hair growth. We report that not only KLK5 but also KLK7 plays an important role in the inflammation and defective differentiation in NS and KLK7 activity is not solely dependent on activation by KLK5. Altogether, these findings show that unregulated activities of KLK5 and KLK7 are responsible for NS development and both proteases should become targets for NS therapy

Characterizing the Grating-like Nanostructures Formed on BaF₂ Surfaces Exposed to Extreme Ultraviolet Laser Radiation

Monocrystalline barium fluoride (BaF2) slab targets were irradiated by focused 46.9-nm laser radiation at various fluence levels above the ablation threshold. Well-developed ablation patterns with sharp edges were studied by AFM (atomic force microscopy). Their inner surfaces were uniformly covered by periodic structures. The spatial period of the ripples depends on the laser fluence. When the sample is rotated by 45°, the orientation of the grating-like structure changes accordingly. Thus, the grating vector of the periodic structure seems to be coupled to the crystallographic planes of the single crystal. This means that the XUV-laser induced ripples reported here differ from LIPSS (laser-induced periodic surface structures) associated with interference phenomena occurring on illuminated surfaces. Therefore, other mechanisms are discussed to explain the formation of the periodic nanostructures reported in this article