Light-Management Strategies for Thin-Film Silicon Multijunction Solar Cells

Light management is of crucial importance to reach high efficiencies with thin-film silicon multijunction solar cells. In this contribution, we present light-management strategies that we recently developed. This includes high quality absorber materials, low-refractive index intermediate reflectors, and highly transparent multiscale electrodes. Specifically, we show the fabrication of high-efficiency tandem devices with a certified stabilized efficiency of 12.6%, triple-junction solar cells with a stabilized efficiency of 12.8%, recently developed smoothening intermediate reflector layers based on silicon dioxide nanoparticles, and periodic-on-random multiscale textures

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Psychologues en réanimation : Quels enjeux ? Quels possibles ?

International audienc

Psychologues en réanimation : Quels enjeux ? Quels possibles ?

International audienc

Fabrication of thermo-responsive nano-valve by grafting-to in melt of poly(N-isopropylacrylamide) onto nanoporous silicon nitride membranes

This article reports the grafting-to in melt of amino and carboxy-terminated poly(N-isopropylacrylamide) (PNIPAM) onto ultrathin nanoporous silicon nitride membranes (NSiNMs) with a mean pore size of 85 +/- 15 nm functionalized respectively with a self-assembled monolayer (SAM) of isocyanatopropyltriethoxysilane (ICPES) and glycidylpropyloxytrimethoxysilane (GPS) to achieve permeation control and obtain thermo-responsive nano-valves. The presence of PNIPAM onto the surface was controlled via X-ray photoelectron spectroscopy (XPS) analysis and the grafting characteristics such as the grafting density and the distance between grafting sites were calculated from the ellipsometric measurements of the dry PNIPAM films. The modified NSiNMs were then integrated into a diffusion cell and used for vitamin B12 and fluorescein isothiocyanate-dextrans (FITC-dextrans) diffusion experiments to demonstrate the reversible and reproducible thermo-responsive behavior of the whole device. By controlling the temperature of the system below and above the lower critical solution temperature (LCST) of the PNIPAM (32 degrees C), the nanopores can switch from a closed state (swollen state of the chains below the LCST) to an opened state (collapsed state of the chains above the LCST). The clear ON-OFF behavior of the grafted NSiNMs has been observed for the diffusion of FITC-dextran molecules with a hydrodynamic radius superior to 3 nm

Large area hole arrays fabricated by a templating method for refractive index sensing

Subwavelength hole arrays in thin gold films were fabricated in a low-cost and parallel fabrication process on 2" wafers. Polystyrene beads were used as an initial pattern template which is transferred into a thin gold film by sputter etching. Hole arrays with two different periodicities were characterized in optical transmission measurements in air and in liquids of varying refractive index. Despite the conical hole shape and long-range disorder of the arrays, the optical transmission spectra are similar to those obtained for precise hole arrays fabricated by serial writing methods, e.g. focused ion beam milling (FIB). We further show the use of the fabricated hole arrays for sensing of molecular binding events

Dynamic Perspective on the Function of Thermoresponsive Nanopores from in Situ AFM and ATR-IR Investigations

This article describes the morphological and chemical characterization of stimuli-responsive functionalized silicon surfaces provided in parallel by atomic force spectroscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) enhanced by the single-beam sample reference attenuated total reflection method (SBSR-ATR). The stimuli-responsive behavior of the surfaces was obtained by grafting-to in melt carboxyl-terminated poly-N-isopropylacryl amides (PNIPAAM) with different degree of polymerization (DP) on epoxide-functionalized silicon substrates. The unprecedented real time and in situ physicochemical insight into the temperature-triggered response of the densely packed superficial brushes allowed for the selection of a PNIPAAM with a specific DP as a suitable polymer for the fabrication of silicon membranes exhibiting switchable nanopores. The fabrication process combines the manufacture of nanoporous silicon surfaces and their subsequent chemical functionalization by the grafting-to in melt of the selected polymer. Then, relevant information was obtained in what concerns the chemical modifications behind the topographical changes that drive the functioning of PNIPAAM-based hybrid nanovalves as well as the timescale on which the opening and closing of the nanopores occur

Inexpensive and fast wafer-scale fabrication of nanohole arrays in thin gold films for plasmonics

In this paper, a fast and inexpensive wafer-scale process for the fabrication of arrays of nanoscale holes in thin gold films for plasmonics is shown. The process combines nanosphere lithography using spin-coated polystyrene beads with a sputter-etching process. This allows the batch fabrication of several 1000 μm2 large hole arrays in 200 nm thick gold films without the use of an adhesion layer for the gold film. The hole size and lattice period can be tuned independently with this method. This allows tuning of the optical properties of the hole arrays for the desired application. An example application, refractive index sensing, is demonstrated

Concept and Demonstration of Individual Probe Actuation in Two-Dimensional Parallel Atomic Force Microscope System

A concept of an array actuator that is used to control the tip–sample separation of cantilevers in a two-dimensional (2D) probe array scanning system is proposed in this article. The feasibility of the concept is demonstrated with a 10×10 array actuator with 500 µm xy-pitches. The array actuator is made by slicing a bulk piezoceramic block. The obtained maximum actuation of a single probe was 2.19 µmp–p at ±168 Vp–p. A major issue for the actuator was the insufficient strength of the frame of the probe array chip. The demonstrated array actuator is highly compatible with previously developed parallel readout modules that use either a parallel optical beam or integrated piezoresistive deflection sensing. A large-scale 2D probe array is our ultimate target