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To determine temperature losses in a photovoltaic (PV) installation, the operating temperature of the cells in the PV panels must be known. This temperature cannot be directly measured because the cells are not accessible from the outside, as they are inside the panels, with other layers of material surrounding them. Therefore, the parameter to which direct access exists by means of measuring is the temperature of the outer surfaces of the modules. However, the cell junction temperatures are typically 1–3 °C higher than the temperature measured on the module's rear surface, depending on the module construction. Some methods exist for determining the cell temperature, including measuring the open-circuit voltage of the panels, but because this is difficult to do with an on-site PV installation, normally this temperature is determined by using models. Numerous models appear in the literature for determining the cell temperature, so in this paper, a recompilation of twenty models is taken into account for determining the temperature and miscellaneous losses of a PV installation located in South Spain in a year’s time. These models have different relations between the value of the cell temperature and some environmental parameters, considering or not the value of the wind speed and the form in which the panels are installed. A maximum difference in annual temperature losses found using the twenty models was 90.4 h/year. This non-negligible quantity indicates the importance of an appropriate choice of model and the correct conditions for applying it to make a precise estimation of the capture temperature losses. Moreover, it would be interesting to reach an agreement on the best procedure for determining this type of losses, especially for correctly performing comparisons of these losses in different PV plants in operation, which can reach very significant values in locations with high temperature registers. [ABSTRACT FROM AUTHOR]

A set of 33 fragments of lustre-decorated ceramics uncovered during an archaeological excavation in Manises (Valencia, Spain) have been studied. These ceramics were produced in Manises from the 14th to the 18th century. This well-dated set of ceramic shards represents the diversity of Manises lustre production and is a complete time sequence of reference for the technological analysis. Texture analysis of the glazes has been carried out by SEM-EDAX, the inner and outer surfaces of the lustre decorations being analysed with non-destructive ion beams by PIXE and RBS, and also by high-resolution electron microscopy. The results are compared with other lustre productions and the time trend of the microstructures, glaze and lustre composition is analysed. It is concluded that Sn was used to opacify glazes until the beginning of the 17th century and that changes in the lustre microstructure occurred around 1500. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between particulate organic carbon (POC) concentrations measured in modern sediment and fluxes of exported POC to the sediment surface needs to be understood in order to use POC content as a proxy of paleo-environmental conditions. The objective of our study was to compare POC concentrations, POC mineralization rates calculated from O2 consumption and POC burial rates. Benthic O2 distributions were determined in 58 fine-grained sediment cores collected at different periods at 14 stations in the southeastern part of the Bay of Biscay with depths ranging from 140 to 2800m. Depth-dependent volume-specific oxygen consumption rates were used to assess rates of aerobic oxidation of organic matter (OM), assuming that O2 consumption solely was related to heterotrophic activity at the sediment–water interface. Heterogeneity of benthic O2 fluxes denoted changes in time and space of fresh organic material sedimentation. The most labile fraction of exported POC engendered a steep decrease in concentration in the upper 5mm of vertical O2 profiles. The rupture in the gradient of O2 microprofile may be related to the bioturbation-induced mixing depth of fast-decaying carbon. Average diffusive O2 fluxes showed that this fast-decaying OM flux was much higher than buried POC, although diffusive O2 fluxes underestimated the total sediment oxygen demand, and thus the fast-decaying OM flux to the sediment surface. Sedimentary POC burial was calculated from sediment mass accumulation rate and the organic carbon content measured at the top of the sediment. The proportion of buried POC relative to total exported POC ranged at the most between 50% and 10%, depending on station location. Therefore, for a narrow geographic area like the Bay of Biscay, burial efficiency of POC was variable. A fraction of buried POC consisted of slow-decaying OM that was mineralized within the upper decimetres of sediment through oxic and anoxic processes. This fraction was deduced from the decrease with depth in POC concentration. At sites located below 500m water depth, where the fast-decaying carbon did not reach the anoxic sediment, the slow-decaying pool may control the O2 penetration depth. Only refractory organic material was fossilized in sedimentary records at locations where labile OM did not reach the anoxic portion of the sediment. [Copyright &y& Elsevier]

Abstract: The Ebro river flows to the Mediterranean coast of Spain. During its final stretch, the Ebro behaves in a similar way to a highly stratified estuary. This paper describes the transport of nutrients to the Ebro estuary, evaluates the general movement of nutrients in the estuarine region, using a mass balance approach, and estimates the amounts of nutrients discharged to the coastal environment. Given the strong saline stratification, this study only includes the surface layer that contains the continental freshwater. The annual nutrient budget for the Ebro estuary shows a net excess for nitrogen and phosphorus, while silicate almost attains equilibrium between addition and removal. There are several reasons for gains in nitrogen and phosphorous: a contribution of dissolved and particulate compounds in the freshwater (some of which are mineralized); a lower uptake of phytoplankton indicated by chlorophyll reduction in the estuary; an entrainment of the nutrient-rich upper part of the salt wedge; and, to a lesser extent, the impact of wastewater and agricultural water use. The biggest load discharged into the Mediterranean Sea by the Ebro is nitrogen, followed by silicate with over 10 000 tons of each deposited annually. Phosphorus is discharged at relatively low concentrations and with an annual load of about 200tyr−1. [Copyright &y& Elsevier]