80 research outputs found
Two components for one resistivity in LaVO3/SrTiO3 heterostructures
A series of 100 nm LaVO3 thin films have been synthesized on (001)-oriented
SrTiO3 substrates using the pulsed laser deposition technique, and the effects
of growth temperature are analyzed. Transport properties reveal a large
electronic mobility and a non-linear Hall effect at low temperature. In
addition, a cross-over from a semiconducting state at high-temperature to a
metallic state at low-temperature is observed, with a clear enhancement of the
metallic character as the growth temperature increases. Optical absorption
measurements combined with the two-bands analysis of the Hall effect show that
the metallicity is induced by the diffusion of oxygen vacancies in the SrTiO3
substrate. These results allow to understand that the film/substrate
heterostructure behaves as an original semiconducting-metallic parallel
resistor, and electronic transport properties are consistently explained.Comment: Improved version as accepted in Journ Phys: Cond Mat. Additional
Optical measurements are presente
SiNx:Tb3+--Yb3+, an efficient down-conversion layer compatible with a silicon solar cell process
SiN x : Tb 3+-Yb 3+, an efficient down-conversion layer compatible with
silicon solar cell process Abstract Tb 3+-Yb 3+ co-doped SiN x down-conversion
layers compatible with silicon Photovoltaic Technology were prepared by
reactive magnetron co-sputtering. Efficient sensitization of Tb 3+ ions through
a SiN x host matrix and cooperative energy transfer between Tb 3+ and Yb 3+
ions were evidenced as driving mechanisms of the down-conversion process. In
this paper, the film composition and microstructure are investigated alongside
their optical properties, with the aim of maximizing the rare earth ions
incorporation and emission efficiency. An optimized layer achieving the highest
Yb 3+ emission intensity was obtained by reactive magnetron co-sputtering in a
nitride rich atmosphere for 1.2 W/cm and 0.15 W/cm power density
applied on the Tb and Yb targets, respectively. It was determined that
depositing at 200 {\textdegree}C and annealing at 850 {\textdegree}C leads to
comparable Yb 3+ emission intensity than depositing at 500 {\textdegree}C and
annealing at 600 {\textdegree}C, which is promising for applications toward
silicon solar cells.Comment: Solar Energy Materials and Solar Cells, Elsevier, 201
Electroluminescence efficiencies of erbium in silicon-based hosts
International audienceWe report on room-temperature 1.5 lm electroluminescence from trivalent erbium (Er3ĂŸ) ionsembedded in three different CMOS-compatible silicon-based hosts: SiO2, Si3N4, and SiNx. We showthat although the insertion of either nitrogen or excess silicon helps enhance electrical conductionand reduce the onset voltage for electroluminescence, it drastically decreases the external quantumefficiency of Er3ĂŸ ions from 2% in SiO2 to 0.001% and 0.0004% in SiNx and Si3N4, respectively.Furthermore, we present strong evidence that hot carrier injection is significantly more efficient thandefect-assisted conduction for the electrical excitation of Er3ĂŸ ions. These results suggest strategiesto optimize the engineering of on-chip electrically excited silicon-based nanophotonic light sources
RĂ©alisation dâun laser Ă faible courant de seuil, avec des boites quantiques InAs/InP organisĂ©es et couplĂ©es latĂ©ralement
Nous prĂ©sentons ici la rĂ©alisation dâun laser Ă faible courant de seuil avec des boites quantiques (QDs) organisĂ©es et couplĂ©es InAs/InP sur subsstrat (311)B pour une Ă©mission Ă 1.55 m. En effet, pour des hautes densitĂ©s de QDs, une organisation pĂ©riodique apparaĂźt dans le plan. Cette organisation renforce le couplage latĂ©ral inter-boites. Des expĂ©riences de magnĂ©to-photoluminescence permettent de mettre en Ă©vidence ces effets de couplage. Ce couplage amĂ©liore lâinjection des porteurs. Une Ă©mission laser avec des faibles courants de seuil est obtenue avec de telles boites
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Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.
Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (nâ=â143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (nâ=â152), or no hydrocortisone (nâ=â108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (nâ=â137), shock-dependent (nâ=â146), and no (nâ=â101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
Cryoglobulinémie dans l'hépatite C et relation avec la charge virale. Etude rétrospective de patients inclus dans un protocole thérapeutique et revue de la littérature
CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Apport du Heidelberg Retina Tomograph II Rostosk Cornea Module (HRT II RCM) pour l'Ă©tude de la surface oculaire
De nouveaux systĂšmes de microscopie confocale in vivo comme le Heidelberg Retina Tomograph II Rostock Cornea Module (HRT II RCM) permettent aujourd hui une analyse de l ensemble de la surface oculaire du centre Ă la pĂ©riphĂ©rie mais aussi des tissus les plus superficiels jusqu aux plus profonds. L analyse de la conjonctive est dĂ©sormais possible avec des applications multiples comme l Ă©valuation de la cicatrisation aprĂšs chirurgie du glaucome. Par une meilleure rĂ©solution, une plus grande rapiditĂ© d acquisition et un traitement informatique des images simplifiĂ©, cette technique d exploration s est rĂ©vĂ©lĂ©e extrĂȘmement prometteuse pour l exploration des pathologies cornĂ©ennes. Cette approche in vivo, quasi-histologique et facilement accessible aux cliniciens des trĂšs nombreuses pathologies de la surface oculaire constitue une aide prĂ©cieuse dans leur prise en charge. Enfin en recherche, cette technique non invasive et simple ouvre de trĂšs nombreuses perspectives dans le domaine de l expĂ©rimentation animale. L analyse en microscopie confocale in vivo de la cornĂ©e, mais aussi maintenant de l ensemble de la surface oculaire normale et pathologique ne fait donc que commencer.PARIS6-Bibl.PitiĂ©-SalpĂȘtrie (751132101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
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