Search results for "conversion."

Conversion of carbohydrates into 5-HMF in Deep Eutectic Solvents under mild reaction conditions

Perovskite CH3NH3PbI3–XClx Solar Cells. Experimental Study of Initial Degradation Kinetics and Fill Factor Spectral Dependence

2021

The main drawback of the methylammonium lead halide perovskite solar cells is their degradation in ambient atmosphere. To investigate ambient-air-induced cell degradation, spec-tral dependencies of open-circuit voltage (VOC), fill factor (FF) and the power conversion effi-ciency (PCE) have been acquired (for the first time reported in literature). Our custom-made measurement system allowed us to perform measurements of the above-mentioned entities in situ directly in vacuum during and after thermal deposition of the elec-trode. We also studied how these parameters in vacuum changed after cell exposure to ambient air for 85 min (50 nm top electrode) and for 180 min (100 nm top Ag electrode).…

A didactic experiment and model of a flat-plate solar collector

2011

We report on an experiment performed with a home-made flat-plate solar collector, carried out together with high-school students. To explain the experimental results, we propose a model that describes the heating process of the solar collector. The model accounts quantitatively for the experimental data. We suggest that solar-energy topics should be included in school programmes to give students the opportunity to gain experience with solar energy and increase their awareness of the benefits that can be obtained from this remarkable and renewable energy source.

Upconversion nanoparticles with a strong acid-resistant capping

2016

Water-dispersible upconversion nanoparticles (β-NaYF:Yb,Er, UCNP) coated with a thin shell of a biocompatible copolymer comprising 2-hydroxyethylmethacrylate (HEMA) and 2-acrylamido-2-methyl-1-propanesulphonsulphonic acid (AMPS), which we will term COP, have been prepared by multidentate grafting. This capping is remarkably resistant to strong acidic conditions as low as pH 2. The additional functionality of the smart UCNP@COP nanosystem has been proved by its association to a well-known photosensitizer (namely, methylene blue, MB). The green-to-red emission ratio of the UC@COP@MB nanohybrid exhibits excellent linear dependence in the 7 to 2 pH range as a consequence of the release of the d…

Fluorinated Heterocyclic Compounds− The First Example of an Irreversible Ring-Degenerate Rearrangement on Five-Membered Heterocycles by Attack of an …

2004

The reactions of 5-perfluoroalkyl-1,2,4-oxadiazoles 3 with hydroxylamine in DMF give the regioisomeric 3-perfluoroalkyl-1,2,4-oxadiazoles 4 in excellent yields. This process is the first example of ring-degenerate rearrangement (RDR) occurring on five-membered heterocycles by attack of an external bidentate nucleophile, which replaces two heteroatoms of the ring. We suggest that an ANRORC-like mechanism occurs in which the addition of the nucleophilic nitrogen atom (NH2OH) on the C(5) atom of 3 is followed by ring opening and irreversible ring-degenerate closure by attack of the nucleophilic oxygen atom (=NOH) on the C(3) atom of the original ring, realizing an elegant and efficient synthes…

Emploi public, emploi privé : la difficile conversion des titulaies de thèse

1998

International audience; Les titulaires de thèse continuent de bénéficier d'une insertion relativement favorable. La plupart deviennent enseignants, chercheurs ou ingénieurs après 3 ans de vie active. Pourtant, leur nombre a fortement augmenté depuis 1989, comme celui de l'ensemble des sortants de l'enseignement supérieur. Ceux qui ne peuvent prétendre à un poste dans l'enseignement supérieur ou la recherche doivent réorienter leur projet professionnel pour espérer se faire une place dans le secteur privé. Ils sont toutefois concurrencés par les diplômés des écoles d'ingénieurs lors de leur recrutement en entreprise. Les docteurs doivent alors tirer profit de leur spécialisation et des liens…

Electro-optical characterization of ruthenium-based dye sensitized solar cells: A study of light soaking, ageing and temperature effects

2017

Abstract In this work, we report on the electro-optical characterization of Dye Sensitized Solar Cells (DSSCs) which use ruthenium complexes as sensitizers. In particular, several kinds of measurements have been performed to study the electrical performances and the efficiency levels of the cells at different operating conditions. In detail, the measurements have been conducted at varying temperatures and hours of light soaking. Our results show that the short circuit current density J SC , the open circuit voltage V OC and the conversion efficiency η increase with the hours of light soaking, while they decrease with temperature. A thorough investigation on the light soaking process at the …

Organic Dye Bearing Asymmetric Double Donor-π-Acceptor Chains for Dye-Sensitized Solar Cells

2011

A novel efficient metal free sensitizer containing asymmetric double donor-π-acceptor chains (DC) was synthesized for dye-sensitized solar cells (DSSCs). Comparing to 3.80%, 4.40% and 4.64% for the DSSCs based on the dyes with single chain (SC1, SC2) and cosensitizers (SC1 + SC2), the overall conversion efficiency reaches 6.06% for DC-sensitized solar cells as a result of its longer electron lifetime and higher incident monochromatic photon-to-current conversion efficiency.

Design of Soft Ferrite filters for EMI reduction in Power Conversion Systems

2019

The use of a discrete passive filter is the most attractive solution for EMI reduction in power conversion systems. This is due to its simplicity of concept and efficiency in the frequency range up to tens of megahertz and over. The common mode and differential mode sections of the EMI filter contain capacitors and soft magnetic chokes and, when they are used in the transportation context, their design has to satisfy further constraints in terms of low weight, low volume, low losses and low cost in adjoint to filtering efficiency. In this framework the authors, by using an EMI filter design procedure already setup by themselves, investigate, also with an experimental setup, the possibility …

Transcriptome analysis of Pseudomonas mediterranea and P. corrugata plant pathogens during accumulation of medium-chain-length PHAs by glycerol bioco…

2017

Pseudomonas corrugata and P. mediterranea are soil inhabitant bacteria, generally living as endophytes on symptomless plants and bare soil, but also capable of causing plant diseases. They share a similar genome size and a high proteome similarity. P. corrugata produces many biomolecules which play an important role in bacterial cell survival and fitness. Both species produce different medium-chain-length PHAs (mcl-PHAs) from the bioconversion of glycerol to a transparent film in P. mediterranea and a sticky elastomer in P. corrugata. In this work, using RNA-seq we investigated the transcriptional profiles of both bacteria at the early stationary growth phase with glycerol as the carbon sou…