Search results for "version"
showing 10 items of 1591 documents
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…
La motivación de los entrenadores deportivos: un estudio desde la teoría de la autodeterminación
2013
El objetivo del estudio consistió en analizar, en una muestra formada por 506 entrenadores, sus percepciones de: satisfacción de necesidades, percepción de utilidad, motivación autodeterminada, y promoción del bienestar de sus deportistas, así como las diferencias en función del sexo, edad y tipo de deporte. También se analizó si las relaciones entre las variables analizadas correspondían a los postulados de la Teoría de la Autodeterminación (TA) (Deci y Ryan, 1985a, b; 2000; Ryan y Deci, 2007). El análisis descriptivo indicó que los entrenadores en general obtuvieron altos niveles de satisfacción de necesidades, percepción de utilidad, motivación autodeterminada, y promoción del bienestar,…
How Hox genes can shed light on the place of echinoderms among the deuterostomes.
2014
19 pages; International audience; BACKGROUND: The Hox gene cluster ranks among the greatest of biological discoveries of the past 30 years. Morphogenetic patterning genes are remarkable for the systems they regulate during major ontogenetic events, and for their expressions of molecular, temporal, and spatial colinearity. Recent descriptions of exceptions to these colinearities are suggesting deep phylogenetic signal that can be used to explore origins of entire deuterostome phyla. Among the most enigmatic of these deuterostomes in terms of unique body patterning are the echinoderms. However, there remains no overall synthesis of the correlation between this signal and the variations observ…
Combined proton NMR wideline and NMR relaxometry to study SOM-water interactions of cation-treated soils
2013
Abstract Focusing on the idea that multivalent cations affect SOM matrix and surface, we treated peat and soil samples by solutions of NaCl, CaCl2 or AlCl3. Water binding was characterized with low field 1H-NMR-relaxometry (20 MHz) and 1H wideline NMR spectroscopy (400 MHz) and compared to contact angles. From 1H wideline, we distinguished mobile water and water involved in water molecule bridges (WaMB). Large part of cation bridges (CaB) between SOM functional groups are associated with WaMB. Unexpectedly, 1H NMRrelaxometry relaxation rates suggest that cross-linking in the Al-containing peat is not stronger than that by Ca. The relation between percentage of mobile water and WaMB water in…
El acontecimiento de la inversión dialéctica
2020
La metafísica de Žižek es hegeliana, por encima de todo, porque entiende la inversión dialéctica como el núcleo real de la realidad. Por ello, para comprender su pensamiento es necesario aclarar su manera de entender esta inversión, esto es, el encuentro que, según Hegel, tiene lugar entre “sustancia” y “sujeto” y, en general, entre los extremos de las oposiciones que estructuran la realidad. Para Žižek lo propio de la posición hegeliana es localizar este encuentro en la falta de coincidencia de cada opuesto consigo mismo. La íntima inconsistencia de cada posición o identidad, su propia negatividad, constituye lo más originario de ellas y, a la vez, lo que las vincula a su otro en la forma …
Taking the Biographical approach seriously – what does it mean for the concept of biographicity?
2018
The article starts from the dialectic relationship between “the biographicity of the social” and “the sociality of the biographical” – a relationship especially underlined in the works of Bettina Dausien (e.g. 2006). Starting from here, we have not only to look at “what” is reconstructed here, but also “how” this reconstruction is presented . By this, the complex powerful social processes of “addressing” and “being addressed” come into the center of interest (Rose/Ricken, 2018:). Addressing and the way people let themselves “being addressed” (Althusser) – if and how they let themselves being addressed – this question opens up for processes of subjectivation, as has been conceptualized by Ju…
Managing conversation uncertainty in TutorJ
2009
Uncertainty in natural language dialogue is often treated through stochastic models. Some of the authors already presented TutorJ mat is an Intelligent Tutoring System, whose interaction with the user is very intensive, and makes use of both dialogic and graphical modality. When managing the interaction, the system needs to cope with uncertainty due to the understanding of the user's needs and wishes. In this paper we present the extended version of TutorJ, focusing on the new features added to its chatbot module. These features allow to merge deterministic and probabilistic reasoning in dialogue management, and in writing the rules of the system's procedural memory.