Comparative study of elemental content in farmed and wild life Sea Bass and Gilthead Bream from four different sites by FAAS and EDXRF

The purpose of this work is to compare the elemental content of samples of wild and farmed fish from four different Portuguese locations.     

Review and discussion of polymer action on alkali–silica reaction

This paper compares the factors known to influence the deleterious alkali–silica reaction in concrete with the properties that polymers tend to modify in cementitious materials. A discussion on the potential ASR-influencing mechanisms of polymer additions is provided, along with a critical review of the existing literature on the subject. The influence of the potentially significant differences in mechanical properties and sorptivity between polymer-modified and unmodified cementitious materials on the expansion results of alkali reactivity tests is also discussed. According to the available results, the influence of polymers on ASR-related expansion seems to depend on both polymer type and dosage, suggesting the existence of concurrent, not yet well understood mechanisms by which polymers may influence ASR-related expansion. As polymer modification of cementitious materials can lead to significantly lower modulus of elasticity, higher tensile strength and resistance to microcracking, it is suggested that further research on the subject includes not only expansion tests but also an assessment of the resistance of polymer-modified cementitious materials to ASR-related damage, the main concern due to this deleterious phenomena.     

Interpreting the dioxin and furan profiles in the lichen Ramalina canariensis Steiner for monitoring air pollution

The purpose of this study was to compare the dioxin and furan (PCDD/F) profiles in lichens with those of air and soil. Lichen samples of the species Ramalina canariensis Steiner were collected from 44 different sites and analysed. The results were compared to PCDD/F air and soil profiles from bibliographic data concerning several countries and locations. When compared to other biomonitors (pine needles, vegetation, fruits), lichens were observed to accumulate greater concentrations of PCDD/Fs. The results showed that, although the concentrations of PCDD/Fs in lichens were at the same level of magnitude as those found for soils from the same country (197.5-1218.7 ng kg(-1) and 2.3-15.2 ng I-TEQ kg(-1)), the PCDD/Fs profiles do not reflect soil particle contamination. On the contrary, the PCDD/Fs lichen profiles seemed to be very similar to the ones in the air, at least for the diversity of the ones used for comparison in this study. These results indicated that lichens of the species R. canariensis are potential biomonitors of PCDD/F air pollution.     

Etude du mécanisme réactionnel de réduction électrolytique de l'aluminium dans le mélange NaCl-KCl-LiCl-LiF fondu à 450° C

Résumé La réduction des ions de l'aluminium dans l'électrolyte NaCl-KCl-LiCl-LiF fondu à 450° C contenant du chlorure d'aluminium en teneur supérieure à 10^–4 mol cm^–3 a été étudiée par voltampérométrie triangulaire sur électrodes d'argent et de platine. Sur électrode d'argent le mécanisme de réduction est un processus simple et rapide entre espèces solubles qui met en jeu deux électrons. Sur électrode de platine la réduction massive des ions de l'aluminium, précédée de la formation de composés définis Al _x Pt _y apparaît également comme un mécanisme simple et rapide avec échange de trois électrons. Dans le but de confirmer ces conclusions nous avons procedé au traitement des courbes expérimentales par analyse convolutionnelle. Nous avons également comparé les tracés expérimentaux avec les courbes théoriques correspondant au processus proposé. Les voltampérogrammes expérimentaux et théoriques étant pratiquement identiques nous confirmons ainsi la validité du diagnostique établi.

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The reduction of the aluminium ions in the molten electrolyte NaCl-KCl-LiCl-LiF at 450° C containing more than 10^–4 mol cm^–3 aluminium chloride was studied with triangular voltamperometry on silver and platinum electrodes. On the silver electrode, the mechanism of the reduction is a simple, rapid process between soluble species involving the exchange of two electrons. On the platinum electrode the massive reduction of the aluminium ions, which leads to the formation of the composites Al _x Pt _y also appears to be a simple and rapid mechanism with exchange of three electrons. In order to confirm the conclusions, we have treated the experimental curve using convolutional analysis. We have also compared the experimental with the theoretical curves corresponding to the proposed processes. The experimental voltamperograms are practically identical to the theoretical, therefore confirming the proposed mechanism.

     

Investigating intentional distortions in software cost estimation – An exploratory study

Cost estimation of software projects is an important activity that continues to be a source of problems for practitioners despite improvement efforts. Most of the research on estimation has focused on methodological issues while the research focused on human factors primarily has targeted cognitive biases or perceived inhibitors. This paper focuses on the complex organizational context of estimation and investigates whether estimates may be distorted, i.e. intentionally changed for reasons beyond legitimate changes due to changing prerequisites such as requirements or scope. An exploratory study was conducted with 15 interviewees at six large companies that develop software-intensive products. The interviewees represent five stakeholder roles in estimation, with a majority being project or line managers. Document analysis was used to complement the interviews and provided additional context. The results show that both estimate increase and estimate decrease exist and that some of these changes can be explained as intentional distortions. The direction of the distortion depends on the context and the stakeholders involved. The paper underlines that it is critical to consider also human and organizational factors when addressing estimation problems and that intentional estimate distortions should be given more and direct attention.     

Modelling spectral reflectance of open cork oak woodland: a simulation analysis of the effects of vegetation structure and background

This study analyses the influence of vegetation structure (i.e. leaf area index and canopy cover) and seasonal background changes on moderate-resolution imaging spectrometer (MODIS)-simulated reflectance data in open woodland. Approximately monthly spectral reflectance and transmittance field measurements (May 2011 to October 2013) of cork oak tree leaves (Quercus suber) and of the herbaceous understorey were recorded in the region of Ribatejo, Portugal. The geometric-optical and radiative transfer (GORT) model was used to simulate MODIS response (red, near-infrared) and to calculate vegetation indices, investigating their response to changes in the structure of the overstorey vegetation and to seasonal changes in the understorey using scenarios corresponding to contrasting phenological status (dry season vs. wet season). The performance of normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI), and enhanced vegetation index (EVI) is discussed. Results showed that SAVI and EVI were very sensitive to the emergence of background vegetation in the wet season compared to NDVI and that shading effects lead to an opposing trend in the vegetation indices. The information provided by this research can be useful to improve our understanding of the temporal dynamic of vegetation, monitored by vegetation indices.     

Correction to: A report on teaching a series of online lectures on quantum computing from CERN

The Journal of Supercomputing - A correction to this paper has been published: https://doi.org/10.1007/s11227-021-03923-0