Public Broadcasting Service

Public Broadcasting Service (PBS) est un réseau de télévision public à but non lucratif comptant plus de membres aux États-Unis qui le détiennent en propriété collective. Son siège est situé à Alexandria, en Virginie. Histoire Identité visuelle À l'occasion de son , le réseau dévoile une nouvelle identité le . Fichier:PBS logo 1970.svg|Logo de PBS de 1970 à 1971. Fichier:PBS 1971 id.svg|Première ère des logos du {{date-|6 février 1971}} à {{date-|septembre 1984}}. Fichier:Public Broadcasting Service logo 2002.svg|Ères 2 à 8 des logos du {{date-|4 septembre 1984}} à {{date-|novembre 2019}}. Fichier:PBS textlogo.svg Présentation PBS est le fournisseur le plus important de programmes télévisés aux stations de télévision publiques américaines, distribuant des émissions et séries telles que Sesame Street, Nova, Arthur, PBS NewsHour, Great Performances, Masterpiece, et Frontline. Depuis le milieu des années 2000, les sondages de Roper commandés par PBS

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Salt-induced thermochromism of a conjugated polyelectrolyte

Natalie Renuka Banerji, Yauhen Sheima, Laurent Alexis Clément Vannay

We report here the photophysical properties of a water-soluble conjugated polythiophene with cationic side-chains. When dissolved in aqueous buffer solution (PBS, phosphate buffered saline), there is ordering of the polymer chains due to the presence of the salts, in contrast to pure water, where a random-coil conformation is adopted at room temperature. The ordering leads to a pronounced colour change of the solution (the absorption maximum shifts from 400 nm to 525 nm). Combining resonance Raman spectroscopy with density functional theory computations, we show a significant backbone planarization in the ordered phase. Moreover, the ratio of ordered phase to random-coil phase in PBS solution, as well as the extent of intermolecular interactions in the ordered phase, can be tuned by varying the temperature. Femtosecond transient absorption spectroscopy reveals that the excited-state behaviour of the polyelectrolyte is strongly affected by the degree of ordering. While triplet state formation is favoured in the random-coil chains, the ordered chains show a weak yield of polarons, related to interchain interactions. The investigated polyelectrolyte has been previously used as a biological DNA sensor, based on optical transduction when the conformation of the polyelectrolyte changes during assembly with the biomolecule. Therefore, our results, by correlating the photophysical properties of the polyelectrolyte to backbone and intermolecular conformation in a biologically relevant buffer, provide a significant step forward in understanding the mechanism of the biological sensing.

Royal Soc Chemistry2017

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Investigation of Interfacial Charge Separation at PbS QDs/ (001) TiO2 Nanosheets Heterojunction Solar Cell

Lioz Etgar, Elham Ghadiri, Bin Liu, Jacques-Edouard Moser

In the recent years, the heterojunction solar cells based on quantum dots (QDs) have attracted attention due to strong light absorbing characteristics and the size effect on the bandgap tuning. This paper reports on the kinetics of interfacial charge separation of PbS QDs/(001) TiO2 nanosheets heterojunction solar cells. PbS QDs are deposited using a bifunctional linker molecule on two different TiO2 films, i.e., TiO2 nanosheets (with 001 dominant exposed facet) and TiO2 nanoparticles (with 101 dominant exposed facet). Upon bandgap excitation, electrons are transferred from the PbS QDs conduction band to the lower lying conduction band of TiO2. Based on the ultrafast pump-probe laser spectroscopy technique, the kinetics of charge separation is scrutinized at the PbS/TiO2 interface. The interfacial charge separation at PbS/TiO2 nanosheets films made of (001) dominant exposed facets is five times faster than that on (101) dominant exposed facets TiO2 nanoparticles. The quantum yields for charge injection are higher for the (001) TiO2 nanosheets than the (101) TiO2 nanoparticles due to enhanced interfacial interaction with (001) surface compared to the (101) nanoparticles. The superior interfacial charge separation at PbS/(001) nanosheets respect to PbS/(101) nanoparticles is consistent with the higher photocurrent and enhanced power conversion efficiency in the PbS QDs/(001) TiO2 heterojunction solar cell. The use of (001) TiO2 nanosheets can be a better alternative to conventional mesoporous TiO2 films in QD heterojunction solar cells and perovskites-based heterojunction solar cells.

Wiley-Blackwell2015

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Regenerative PbS and CdS Quantum Dot Sensitized Solar Cells with a Cobalt Complex as Hole Mediator

Takeru Bessho, Peter Chen, Pascal Comte, Michael Graetzel, Soo-Jin Moon, Mohammad Khaja Nazeeruddin, Kevin Sivula, Shaik Mohammed Zakeeruddin

Metal sulfide (PbS and CdS) quantum dots (QDs) were prepared over mesoporous TiO2 films by improved successive ionic layer adsorption and reaction (SILAR) processes. The as-prepared QD-sensitized electrodes were combined with a cobalt complex redox couple Co(o-phen)(3) to make a regenerative liquid-type photovoltaic cell. The optimized PbS QD-sensitized solar cells exhibited promising incident photon-to-current conversion efficiency (IPCE) of over 50% and an overall conversion efficiency of 2% at 0.1 sun in a regenerative mode. The overall photovoltaic performance of the PbS QD-sensitized cells was observed to be dependent on the final turn of the SILA R process, giving a better result when the final deposition was Pb2+, not S2-. However, in the case of CdS QD-sensitized cells, S2- termination was better than that of Cd2+. The cobalt complex herein used as a regenerative redox couple was found to be more efficient in generating photocurrents from PbS QD cells than the typical hole scavenger Na2S in a three-electrode configuration. The CdS-sensitized cell with this redox mediator also showed better defined current-voltage curves and an IPCE reaching 40%.

2009

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EE-295: Electrical systems and electronics I

Le but de ce cours est d'apporter les connaissances et les expériences fondamentales pour comprendre les systèmes électriques et électroniques de base.

BIO-472: Cancer biology II

The course covers in detail the interactions of cancer cells with their environment with an emphasis on tumor-angiogenesis, inflammation, adaptive and innate immunity and cancer-induced immune suppression. Additional topics are cancer metabolism, cancer stem cells and metastasis.

BIOENG-456: Controlling behavior in animals and robots

Students will acquire an integrative view on biological and artificial algorithms for controlling autonomous behaviors in animals and robots. Students will synthesize and apply this knowledge in oral presentations and exercises.

États-Unis

Les États-Unis (prononcé : ), en forme longue les États-Unis d'Amérique, également appelés informellement les USA ou moins exactement lAmérique ou encore les States (en anglais : United States, Unit

New York

New York (prononcé en anglais : ), officiellement nommée en, connue également sous les noms et abréviations de en ou en (pour éviter la confusion avec l'État de New York), et dont le surnom le plus co

CBS

CBS Broadcasting, Inc. (abrégé en CBS) est un important réseau de télévision commercial américain créé en 1927 en tant que réseau de radio sous le nom de United Independent Broadcasters Inc. puis reno