116 research outputs found
Novel Hybrid Materials Consisting of Regioregular Poly(3-octylthiophene)s Covalently Attached to Single-Wall Carbon Nanotubes
No full textPreparation and characterization of thin CsAu films
No full textThe formation of CsAu films by successive evaporation of gold and caesium atoms onto a clean Ru(001) substrate surface was followed by UV photoelectron spectroscopy and (subsequent) thermal desorption spectroscopy. No compound but only a chemisorbed layer (and eventually bulk caesium) is formed if caesium is deposited onto a gold layer, if the quantity of the latter itself does not exceed the monolayer capacity. With thicker gold layers, on the contrary, semiconducting CsAu (with a band gap of 2.6 eV and the Fermi level close to the conduction band edge) is formed by interdiffusion at T > 250 K, but the outer surface consists always of a layer of chemisorbed caesium. This even holds for a “sandwich” system for which a thick gold film was evaporated onto a CsAu layer. The surface region of CsAu is highly reactive towards oxygen
NOTE : UTILISATION DE L'ORGE EN VERT PRODUITE HORS SOL POUR ALIMENTER DES LAPINS EN CROISSANCE EN SYSTEME FAMILIAL
No full text[EN] Twenty, 42-day old crossbred rabbits (New-Zealand x
Californian) were divided in 2 groups and raised in wire mesh
cages involving 5 rabbits per cage. During the 7 weeks of the
experiment, rabbits received daily one of the following feeding
programmes : control ration (T) - 160 g pelleted concentrate per
animal, or experimental ration (E) - 80 g of the same concentrate
+ 400 g per animal of barley grass produced in 1 O days using a
hydroponic method. The crude fibre content of barley grass was 24.8% of dry mater (DM). Barley grass (whole plant parts) was
readily consumed by rabbits. lntake of barley grass represented
40% of the daily DM intake (34 to 45% according to the week).
Final live weight at 91 days was similar in the 2 groups : 2.47 and
2.38 kg for T and E. DM feed conversion ratio was numerically
lower in the E than in the T group: 4.09 vs 4.28. Carcass weight
and adiposity (6 rabbits slaughtered per group) were similar in
the 2 groups. Use of barley grass makes it possible to reduce
feed costs by 10% and also to increase independence of
breeders from pellets suppliers.[FR] Vingt lapins croisés (mére New Zélandaise, pére
Californien) agés de 42j ont été répartis en 2 lots de 1 O et logés dans
des cages collectives de 5 sujets. lls ont été alimentés pendant 7
semaines avec deux rations différentes : lot témoin (T) distribution
d'un aliment granulé concentré complet pour lapin en croissance, a
raison de 160 g I tete/jour et lot expérimental (E) distribution de 80 g
du meme aliment concentré granulé et de 400 g de verdure par
/tete/jour. La verdure était fournie par de l'orge cultivée en systéme
hydroponique pendant 1 O jours et contenait 24,8% de cellulose brute
par rapport a la matiére séche (MS). La verdure a été bien acceptée
par les lapins qui ont consommé facilement la plantule entiére (feuilles + racines). Son ingestion a représenté 40% de la
consommation moyenne quotidienne de MS des lapins du lot E (34 a
45% selon les semaines). Le poids vif final des deux groupe de
lapins était équivalent: 2,47 kg et 2,38 kg a 91 jours pour les lots T et
E. L'indice de consommation de la MS a été numériquement plus
faible pour le lot E : 4,09 vs 4,28. Le poids et l'adiposité des
carcasses (6 lapins par lot) n'ont pas été significativement affectés
par les traitements. L'utilisation de l'orge en vert permet de réduire
de 10% les coOts alimentaires et diminue la dépendance des
élevages par rapport aux fournisseurs d'aliments du bétail.Kriaa, S.; Bergaoui, R.; Kennou, S. (2001). NOTE : UTILISATION DE L'ORGE EN VERT PRODUITE HORS SOL POUR ALIMENTER DES LAPINS EN CROISSANCE EN SYSTEME FAMILIAL. World Rabbit Science. 9(4). https://doi.org/10.4995/wrs.2001.462SWORD9
Photoelectron spectroscopy study of surface alloying in the Au/Ni (s) 5(0 0 1) × (1 1 1) system
No full textPETITS PROJETS CUNICOLES ET DEVELOPPEMENT RURAL EN TUNISIE :POSSIBILITES ET LIMITES
No full text[EN] In Tunisia, the breeding of rabbits often represents an importan!
componen! of projects of rural development. This breeding is
developed in small units (15 to 20 does) using technologies of the
industrial system (buildings, wire mesh cages, concentrate
feeding .... ). Fifteen units established within the framework of a
project of rural development were studied during one year. On
average, the dimension of a breeding unit was 18.4 New Zealand
White does and 2 Californian males. The number of breeding does
per mother cage was 1 .15. Matings were performed 3 to 7 days after
each kindling and the fertility rate was 66.2 kindlings per 100
matings. On average, 6.18 kindlings were observed in a mother cage
per year (5.37 I doe), with a litter size of 7.64 kits. Out of the 47 kits
born per mother cage, only 27 (about 65% of !hose born alive) were
present at slaughter time (2.24 kg alive). These low performances were mainly explained by peor management of the units (lack of
hygiene, insufficiently controlled reproduction, errors in the building
management, ... ). The expense of pelleted feed was 4.55 kg per kg
of live weight sold. The gross financia! income above the feeding and
direct expenses was 60 Tunisian Dinars (about 42 US dollars). This
low income was the result of very low productivity of the units and of
excessive charges, mostly for pelle! feeding. lf the reimbursement of
the expenses invested to create the unit (4400 Dinars/unit) were
included, ali breeders were in a negative balance situation during this
first year of production. On the other hand, this project allowed the
integration of rural women in the economic or marketing system, and
is presently blooming despite the very traditional and conservative
society. The economic success of this type of project will depend on
the improvement of the technical management of rabbit production
and a reduction of investments costs. lt would permit a sustainable
rabbit production system in the area with new employment[FR] L'élevage du lapin représente souvent en Tunisie une
composante des projets de développement générateurs de revenu et
ciblant les femmes rurales. Cet élevage est développé avec des
petites unités de 15 a 20 femelles reproductrices utilisant du matériel
et des technologies issus du systeme industrie! (batiments fermés,
cages grillagées, alimentation concentrée exclusivement, ... ). Les
auteurs ont suivi pendan! une année la production de 15 unités
cunicoles installées dans le cadre d'un projet de développement rural
dans la région de Tunis. En moyenne, chaque unité comprenait 18,4
lapines reproductrices de type Néo-Zélandais Blanc accouplées a 2
males de génotype Californien. Le taux d'occupation des cagesmeres
était de 115% et les femelles étaient présentées au male 3 a
7 jours apres la mise bas. Le taux de mise bas par saillie a été de
66,2% . La productivité annuelle a été de 6,18 mises bas de 7,64
lapereaux par cage-mere (5,37 mises bas par lapine). Sur les 47
lapereaux nés totaux par cage mere et par an, 27 seulement (soit
65% des nés vivants) ont été vendus, au poids mayen de 2,24 kg.
Ces faibles performances peuvent etre expliquées essentiellement
par une mauvaise maitrise de la conduite de l'élevage (hygiene reproduction, ambiance au sein du clapier ... ). La dépense
alimentaire a été de 4,55 kg d'aliment complet granulé par kg de
lapin vendu. Le revenu mayen brut par unité cunicole hors
alimentation et charges directes a été en moyenne de 60 Dinars
Tunisiens par mois (équivalent a 42 Dollars US). La faiblesse de ce
revenu est le résultat de la faible production des lapines et de
charges de production élevées, notamment les charges alimentaires.
Si l'on tient compte du remboursement de !'avance consentie pour la
création de l'unité de production (4400 Dinars), les élevages ont tous
été en déficit au cours de cette premiere année de fonctionnement.
Ce projet a par centre permis l'intégration de femmes rurales dans le
circuit économique et leur épanouissement dans un milieu
traditionnellement tres conservateur. La réussite économique de tels
projets nécessite une meilleure maitrise technique des élevages,
principalement de la mortalité, et une réduction des coOts
d'investissement. Elle garantirait leur durabilité et pourrait aboutir a la
mise en place d'une filiere complete et d'importantes possibilités de
création d'emplois (amont, production, valorisation des sous
produits, aval ... ).Bergaoui, R.; Kennou- Sebeï, S.; Fekih, S. (2001). PETITS PROJETS CUNICOLES ET DEVELOPPEMENT RURAL EN TUNISIE :POSSIBILITES ET LIMITES. World Rabbit Science. 9(4). https://doi.org/10.4995/wrs.2001.463SWORD9
Hydrogenated under-stoichiometric tungsten oxide anode interlayers for efficient and stable organic photovoltaics
No full textIn this work a hydrogenated under-stoichiometric tungsten oxide is introduced as an efficient anode interlayer in organic photovoltaics (OPVs). The benefits of hydrogen incorporation into the oxide lattice for obtaining desirable properties of tungsten oxides are explored. These benefits include the occupation of gap states near the Fermi level, which may facilitate charge transport, and the maintenance of a high work function, nearly similar to that of the stoichiometric tungsten oxide, which contributes to the formation of a large interfacial dipole at the anode interface and enhances charge extraction. A large improvement was achieved in the operational characteristics-especially in the open-circuit voltage-of bulk heterojunction solar cells based on different polymeric donors, namely poly(3-hexylthiophene), P3HT, or poly[(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)-2,5-thiophenediyl-2,1, 3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl], PCDTBT, and the fullerene acceptor [6,6]-phenyl-C71 butyric acid methyl ester, PC71BM, that incorporated a hydrogenated tungsten oxide as an anode interlayer. This improvement was correlated with the devices' incident photon-to-electron conversion efficiencies (IPCEs) and impedance measurements. Furthermore, an increase in both the device's flat-band voltage (Vfb) and the doping level of the organic semiconductor was measured in P3HT:PC71BM based devices by Mott-Schottky capacitance analysis. Additional benefits are the large process window established for the devices incorporating the hydrogenated tungsten oxide as an anode interlayer and the maintenance of a high PCE (>80% of its initial efficiency) over 50 days, demonstrating good long-term stability, which is much better than that of the conventional devices based on PEDOT:PSS. The results suggest that the interface engineering with hydrogen-treated metal oxide interlayers is an important strategy to develop highly performing and stable organic photovoltaics.</p
Reduced transition metal oxides as electron injection layers in hybrid-PLEDs
No full textHere we report on the improved performance of hybrid polymer light emitting diodes (HyPLEDs) upon inserting an ultra thin layer of partially reduced tungsten oxide (WO2.5) or molybdenum oxide (MoO2.7), deposited (by heating a W or Mo filament while hydrogen was flowing through the chamber) at the polymer/Al cathode interface. Improved current densities, luminances and efficiencies were achieved as a result of improved electron injection and transport at its interface with Al. The observed electron injection improvement is attributed to the lowering of the effective cathode interfacial barrier due to the occupation of gap states with electrons after partial reduction.</p
An x-ray photoelectron spectroscopy and work-function study of the Er/α-SiC(0001) interface
No full text
Tungsten oxides as interfacial layers for improved performance in hybrid optoelectronic devices
No full textTungsten oxide (WO3) films with thicknesses ranging from 30 to 100 nm were grown by Hot Filament Vapor Deposition (HFVD). Films were studied by X-Ray Photoemission Spectroscopy (XPS) and were found to be stoichiometric. The surface morphology of the films was characterized by Atomic Force Microscopy (AFM). Samples had a granular form with grains in the order of 100 nm. The surface roughness was found to increase with film thickness. HFVD WO3 films were used as conducting interfacial layers in advanced hybrid organic-inorganic optoelectronic devices. Hybrid-Organic Light Emitting Diodes (Hy-OLEDs) and Organic Photovoltaics (Hy-OPVs) were fabricated with these films as anode and/or as cathode interfacial conducting layers. The Hy-OLEDs showed significantly higher current density and a lower turn-on voltage when a thin WO3 layer was inserted at the anode/polymer interface, while when inserted at the cathode/polymer interface the device performance was found to deteriorate. The improvement was attributed to a more efficient hole injection and transport from the Fermi level of the anode to the Highest Occupied Molecular Orbital (HOMO) of a yellow emitting copolymer (YEP). On the other hand, the insertion of a thin WO3 layer at the cathode/polymer interface of Hy-OPV devices based on a polythiophene-fullerene bulk-heterojunction blend photoactive layer resulted in an increase of the produced photogenerated current, more likely due to improved electron extraction at the Al cathode.</p
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