305,218 research outputs found
Valutazioni Interannuali del livello di eutrofizzazione lungo un transetto posto all\u27altezza di Senigallia (Adriatico-settentrionale): 1988-1994.
No full textThe TRIX index method was applied to historical data set of Senigallia Transect (Northern Adriatic Sea) to evaluate the eutrophication level in 3 stations characterised by different trophic conditions. Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphorus (DIP) were used and TRIX index showed a significant positive correlation with DIN. In 1994 the trophic front expanded up to 15 nM, in an area usually external to trophic coastal front, and we correlate this phenomenon with meteo-climatic conditions of the period. The TRIX index was confirmed to be a valid method in the monitoring of the trophic level in coastal waters.E\u27 stato applicato l\u27indice TRIX per la valutazione del livello di eutrofizzazione sulla serie storica proveniente dal transetto di Senigallia (Adriatico settentrionale), su 3 stazioni caratterizzate da un differente grado di trofia. I parametri utilizzati per il calcolo dell\u27indice sono: azoto inorganico disciolto (DIN) e fosforo inorganico disciolto (DIP) come PO4. L\u27indice TRIX ? correlato significativamente, in modo positivo, soltanto con il DIN. Nel 1994 si ? manifestata la tendenza ad una espansione del fronte della zona trofica verso il largo fino a 15 nM, dove solitamente non si riscontravano fenomeni di eutrofia. L\u27indice si ? rivelato un valido strumento per il monitoraggio del livello trofico dell\u27Adriatico ed il fenomeno individuato dal TRIX nel 1994 trova un riscontro anche negli eventi meteo-climatici registrati in quel periodo
Caratteristiche idrobiochimiche e fluttuazioni del fitoplancton nel transetto di Senigallia (Adriatico settentrionale): 1988-1994
No full textPhytoplankton time series in the northern Adriatic Sea: the Senigallia transect (1988-1994)
No full textDistribution of abundance, biomass, production and productivity of macrozoobenthos in the sub-Antarctic Magellan Province (South America)
No full textDistribution of abundance, biomass, productivity and production of macrozoobenthos was investigated in four study areas in the Magellan region (South Patagonian Ice-Field, Strait of Magellan, Beagle Channel, Continental Shelf). Using a Reineck box corer and a multibox corer, a total of 277 quantitative benthos samples were taken at 78 stations in water depths between 8 and 1139 m during the Joint Chilean-German-Italian Magellan "Victor-Hensen Campaign" in 1994, the "Polarstern" expedition ANT XIII/4 in 1996 and the Chilean expeditions "Cimar Fiordo II + III" in 1996 and 1997, respectively, on board RV "Vidal Gormaz". Mean abundance in the South Patagonian Ice-Field was significantly lower than in the Strait of Magellan and the Beagle Channel. Biomass and abundance decreased clearly with depth (20-300 m to 700-1500 m: 3.9 gC mm2 to 0.6 gC mm2; 2832 ind. mm2 to 569 ind. mm2). Average abundance, biomass and production of the whole Magellan region are lower (2318 ind. mm2, 3.2 gC mm2, 0.62 gC mm2 yearm1) than in the high Antarctic Weddell Sea. In the Magellan region, macrozoobenthos composition of abundance is mainly dominated by polychaetes (56%), followed by arthropods (16%), echinoderms (10%) and molluscs (11%). Comparisons of our present results with those of high Antarctic areas make it clear that the Magellan region has a transitional character
Annealing Temperature and Post Sulphurizaton/Seleniation Effects on Solution-Based CZTS Devices
No full textCZTS absorber films were prepared by spin-coating technique and the effect of selenization temperature on the structural and morphological properties of the CZTSSe films were studied. After confirming the phase purity of the selenized CZTS films, precursor films were also annealed in different atmosphere including sulphur and selenium+sulphur with the optimized annealing temperature. The structural properties of the films were analyzed by X-ray diffraction and Raman spectroscopy; the surface morphology of the films was analyzed by atomic force microscopy. The phase purity was confirmed for the CZTS films annealed at 450°C in different atmosphere. A prototype CZTS solar cell was fabricated with spin-coated CZTS precursor film selenized at 450°C. The influence of light soaking on the films was also studied and observed an increase in device performance after 24hr light soaking. The highest device efficiency of 2.18% with Voc=212 mV, Jsc=35.1 mA/cm2, and FF=33.4% was observed for CZTS films selenized at 450°C
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Achievement of Graded Band Gap in CdTe Solar Cells through Selenization of the Absorber
No full textThe awareness of climate change is growing worldwide and with it, also the request for alternative energy solutions to fossil sources. Photovoltaic energy is one of the main answers, since the technology is well developed and can be installed anywhere. The main challenge in this field, today, is to reduce the costs of the energy produced. In this respect, CdTe thin film panels, which can be fabricated in a single manufacturing line, have a great advantage over traditional crystalline silicon cells. Moreover their efficiency is nowadays closer to that of silicon cells, having reached a value of 22.1 %. The efficiency improvement is mainly due to the replacement of the CdS layer with MZO, which has a higher band gap, and to the introduction of a CdTe1-xSex layer, which allows the grading of the absorber band gap, increasing the absorption in the long wavelength region. In this work we present a novel method to produce the band gap grading of the CdTe absorber layer through selenization of the CdTe layer
Analysis of Environmentally Friendly and Low Cost Non Vacuum Process for Cu2ZnSn(S,Se)4 Solar Cells
No full textIn this work CZTSSe absorber films were prepared by spin coating technique followed by selenization at optimized suitable condition. The structural properties and phase purity of the films were analyzed by XRD and Raman spectroscopy, surface morphology of the films was analyzed by SEM and AFM. Elemental composition was analyzed by energy dispersive x ray spectroscopy. Phase pure CZTSSe films with the required photovoltaic properties was obtained by selenizing the precursor films at 450 °C for 30 min with the optimal precursor drying condition. Prototype CZTSSe solar cell was fabricated and its performance were studied systematically. The highest device efficiency of 4.9% with Voc=321 mV, Jsc=30 mA/cm2 , and FF=51% was obtained for spin coated CZTSSe device. It was observed that precursor drying condition significantly influence the performance of devices
How the selenium distribution in CdTe affects the carrier properties of CdSeTe/CdTe solar cells
No full textRecently, the introduction of a CdSexTe1-x (CST) buffer in the CdTe absorber has increased the photon absorption at both short wavelengths in the visible range (by removal of the parasitic absorption of the CdS layer) and at the infrared range (by reduction of the absorber band gap). But, moreover, the efficiency improvement is also attributed to a longer minority carrier lifetime when Se is added. This paper presents CdSexTe1-x/CdTe devices fabricated by evaporation at low substrate temperature and with a reduced absorber thickness (2 & mu;m). These cells achieve record current densities, exceeding 28 mA/cm2 for this absorber thickness with efficiencies close to 15 %. We have compared CdSexTe1-x/CdTe devices made with different approaches and we have found that the performance improvement is due to a lower amount of interstitial Te in the absorber, suggesting that the increase of the minority carrier lifetime is connected with a change of the stoichiometry due to the selenium diffusion
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