| 1. |
- Alonso, Benjamin, et al.
(författare)
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Characterization of sub-two-cycle pulses from a hollow-core fiber compressor in the spatiotemporal and spatiospectral domains
- 2013
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 112:1, s. 105-114
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Tidskriftsartikel (refereegranskat)abstract
- We have post-compressed 25 fs (Fourier limit) amplified pulses in an argon-filled hollow-core fiber. The output pulses were compressed using a pair of wedges and chirped mirrors down to 4.5 fs (Fourier limit of 4.1 fs), which corresponds to less than two optical cycles. We then performed the characterization of the pulses by combining the d-scan and the STARFISH techniques. The temporal (and spectral) measurement of the pulses is done with d-scan, which is used as the reference to extend the characterization to the spatiotemporal (and spatiospectral) amplitude and phase of the pulses by means of STARFISH. The post-compressed pulses at the output of the hollow-fiber had an energy of 150 mu J. The analysis of the pulses revealed larger spectral broadening and blue-shift, and shorter duration at the center of the beam. For the first time, we demonstrate the complete characterization of intense ultra-broadband pulses in the sub-two-cycle regime, which provides an improved insight into the properties (space-time and space-frequency) of the pulses and is highly relevant for their applications.
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| 2. |
- Gogniat, Emiliano, et al.
(författare)
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Dead space analysis at different levels of positive end-expiratory pressure in acute respiratory distress syndrome patients
- 2018
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Ingår i: Journal of critical care. - : W B SAUNDERS CO-ELSEVIER INC. - 0883-9441 .- 1557-8615. ; 45, s. 231-238
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To analyze the effects of positive end-expiratory pressure (PEEP) on Bohr's dead space (VDBohr/VT) in patients with acute respiratory distress syndrome (ARDS).Material and methods: Fourteen ARDS patients under lung protective ventilation settingswere submitted to 4 different levels of PEEP (0, 6, 10, 16 cmH(2)O). Respiratory mechanics, hemodynamics and volumetric capnography were recorded at each protocol step.Results: Two groups of patients responded differently to PEEP when comparing baseline with 16-PEEP: those in which driving pressure increased > 15% (Delta P.(15%), n = 7, p = .016) and those in which the change was <= 15% (Delta P-<= 15%, n = 7, p = .700). VDBohr/VT was higher in Delta P-<= 15% than in Delta P-<= 15% patients at baseline ventilation [0.58 (0.49-0.60) vs 0.46 (0.43-0.46) p = .018], at 0-PEEP [0.50 (0.47-0.54) vs 0.41 (0.40-0.43) p = .012], at 6-PEEP [0.55 (0.49-0.57) vs 0.44 (0.42-0.45) p = .008], at 10-PEEP [0.59 (0.51-0.59) vs 0.45 (0.44-0.46) p = .006] and at 16-PEEP [0.61 (0.56-0.65) vs 0.47 (0.45-0.48) p =. 001]. We found a good correlation between Delta P and VDBohr/VT only in the Delta P.(15%) group (r = 0.74, p < .001).Conclusions: Increases in PEEP result in higher VDBohr/VT only when associated with an increase in driving pressure.
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| 3. |
- Perez, Paloma, et al.
(författare)
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Bioresorbable and nonresorbable macroporous thermosensitive hydrogels prepared by cryopolymerization. Role of the cross-linking agent
- 2008
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 9:1, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- Macroporous poly(N-isopropylacrylamide) (pNIPA) gels (so-called cryogels), cross-linked with different bisacryliccompounds, N,N'-methylenebisacrylamide (MBAAm) and dimethacrylate-tyrosine-lysine-tyrosine (DMTLT), were prepared through free-radical polymerization at subzero temperature in dioxane/water media. DMTLT is a hydrolytically degradable cross-linker with relatively hydrophobic character. The effects of different synthesis conditions, namely the concentration of monomers, the cross-linker, and the initiator in the reaction mixture, on the structure of the pNIPA-cryogels have been studied. The equilibrium swelling ratio of the DMTLT crosslinked pNIPA cryogels at temperatures below lower critical solution temperature (LCST) of pNIPA, was over ten times higher than that of the gels synthesized at room temperature from the same feed composition. The MBAAm cross-linked pNIPA cryogels synthesized in water exhibited the highest equilibrium swelling and the fastest response. The critical transition temperature, T-c, was lower (T-c approximate to 31 degrees C) for pNIPA-cryogels synthesized in dioxane/water media or cross-linked with DMTLT as compared to MBAAm cross-linked pNIPA cryogels synthesized in water (T-c approximate to 33 degrees C). Scanning electron microscopy (SEM) revealed different porous structure and pore surface morphology depending on the cross-linker (MBAAm or DMTLT) and the solvent (water or dioxane/water) used. Gels and cryogels were also characterized by SAXS, showing that the nanostructure of the samples is related to swelling.
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