642 research outputs found

    A PORTABLE AND INEXPENSIVE DO-IT-YOURSELF TEMPERATURE SENSOR

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    Nowadays it is important to have commercial solutions to be used in teaching and research laboratories for the needs. We can have different equipment according to the necessary parameters of control being related to the influence of parameters internal or external to the laboratory practice. However they can't be straightforward to use, their costs can be considerable.  In this context, the do-it-yourself approach is an interesting alternative. In this paper we report the construction of a temperature sensor made by students. Based on a probe taken from a deactivated equipment, the sensor development and validation encompassed its design and building up, the establishment of a connection to a personal computer via USB, the setup of computer-controlled processes, which included remote control, graphical and numerical displaying and signal acquisition, and finally its testing. Tests were performed in water containers with different temperatures, namely boiling, room and ice. The obtained results are comparable to those from a commercial thermometer. This student experiment project allowed not only to contact different disciplines such as chemistry, electronics, and programming but also to gain competencies that can be used outside the class context. We proved it is possible to build tailor-made electronic devices capable of providing useful measurements to chemical purposes old equipment in an inexpensive and trustworthy way

    Unconventional Metallic Magnetism in LaCrSb{3}

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    Neutron-diffraction measurements in LaCrSb{3} show a coexistence of ferromagnetic and antiferromagnetic sublattices below Tc=126 K, with ordered moments of 1.65(4) and 0.49(4) Bohr magnetons per formula unit, respectively (T=10 K), and a spin reorientation transition at ~95 K. No clear peak or step was observed in the specific heat at Tc. Coexisting localized and itinerant spins are suggested.Comment: PRL, in pres

    Dois bispos do século XVIII: D. Miguel da Anunciação, bispo de Coimbra e D. Frei Manuel da Ressurreição

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    Devendo discorrer sobre dois Bispos da Igreja Católica, que viveram no século XVIII, um em Portugal, o Bispo de Coimbra, Dom Miguel da Anunciação (el. 1741 — m. 1779), o outro no Brasil, o Bispo de São Paulo, Dom Frei Manuel da Ressurreição (el. 1771 — m. 1789), e, por força do tema, obrigado a tratar de movimentos culturais de dificil caracterização, como o Iluminismo e mesmo das correntes de idéias que culminaram na Revolução Francesa, confesso o meu receio de, nos limites de um artigo, não apresentar, como se deve, toda a objetividade da verdade histórica

    Dois bispos do século XVIII: D. Miguel da Anunciação, bispo de Coimbra e D. Frei Manuel da Ressurreição

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    Devendo discorrer sobre dois Bispos da Igreja Católica, que viveram no século XVIII, um em Portugal, o Bispo de Coimbra, Dom Miguel da Anunciação (el. 1741 — m. 1779), o outro no Brasil, o Bispo de São Paulo, Dom Frei Manuel da Ressurreição (el. 1771 — m. 1789), e, por força do tema, obrigado a tratar de movimentos culturais de dificil caracterização, como o Iluminismo e mesmo das correntes de idéias que culminaram na Revolução Francesa, confesso o meu receio de, nos limites de um artigo, não apresentar, como se deve, toda a objetividade da verdade histórica

    Study of the Potential Accumulation of the Pesticide Alpha-Endosulfan by Microplastics in Water Systems

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    Microplastics (MP) are spread into all ecosystems and represent a threat to the equilibrium of the environment and human health, not only due to their intrinsic characteristics but also to their action as effective carriers of contaminants, such as pesticides, pharmaceuticals, polychlorinated biphenyls and polycyclic aromatic hydrocarbons. The pesticide α-endosulfan is persistent and spread in the environment. The MP are another possible way of dissemination to be considered in the fate of this pesticide. The adsorption dynamics of α-endosulfan by six different MP (low-density polyethylene—LDPE, polyethylene-co-vinyl acetate, unplasticized polyvinyl chloride, polyamide 6, polystyrene granule, polypropylene granule) with different sizes/shapes and chemical compositions were evaluated. The most critical situation was identified for the system LDPE (particle size < 300 μm). Equilibrium studies (48 h equilibrium time) were performed for distilled, tap and filtered river water. Based on the Langmuir model parameters, the highest maximum adsorption capacity was obtained for distilled water, followed by filtered river and tap waters (i.e., 366 ± 39, 247 ± 38, 157 ± 22 μg/g). The obtained results demonstrate the important role that microplastics may have in the fate and transport of pesticides and their potentially harmful effect on the environment, which requires further investigationThis research was funded by the Associate Laboratory for Green Chemistry-LAQV, which received financial support from UIDB/50006/2020, UIDP/50006/2020, and LA/P/0008/2020 by the Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through national funds. This research was funded through the 2019–2020 Biodiversa & Water JPI joint call for research proposals, under the BiodivRestore ERA-Net COFUND programme, DivRestore/0002/2020, and with the funding organisation FCT, Portugal. Virgínia Cruz Fernandes thanks FCT for the financial support through a postdoctoral fellowship (SFRH/BPD/109153/2015). Also, Sílvia Daniela Martinho thanks FCT for the financial support through a doctoral fellowship (SFRH/BD/13595/2022). The authors are greatly indebted to all financing sources.info:eu-repo/semantics/publishedVersio

    Microplastic Pollution Focused on Sources, Distribution, Contaminant Interactions, Analytical Methods, and Wastewater Removal Strategies: A Review

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    Plastics have been one of the most useful materials in the world, due to their distinguishing characteristics: light weight, strength, flexibility, and good durability. In recent years, the growing consumption of plastics in industries and domestic applications has revealed a serious problem in plastic waste treatments. Pollution by microplastics has been recognized as a serious threat since it may contaminate all ecosystems, including oceans, terrestrial compartments, and the atmosphere. This micropollutant is spread in all types of environments and is serving as a “minor but efficient” vector for carrier contaminants such as pesticides, pharmaceuticals, metals, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The need to deeply study and update the evolution of microplastic sources, toxicology, extraction and analysis, and behavior is imperative. This review presents an actual state of microplastics, addressing their presence in the environment, the toxicological effects and the need to understand their extent, their interactions with toxic pollutants, the problems that arise in the definition of analytical methods, and the possible alternatives of treatmentsThis research was funded by the Associate Laboratory for Green Chemistry-LAQV, which received financial support from UIDB/50006/2020, UIDP/50006/2020, and LA/P/0008/2020 by the Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through national funds. The research was funded also by FCT and BiodivRestore Joint Call 2020–2021—European Union’s Horizon 2020 research and innovation programme under grant agreement No 101003777-BiodivRestore-406/DivRestore/0002/2020-BioReset-“Biodiversity restoration and conservation of inland water ecosystems for environmental and human well-being”. Virgínia Cruz Fernandes thanks FCT for the financial support through a postdoctoral fellowship (SFRH/BPD/109153/2015). The authors are greatly indebted to all financing sourcesinfo:eu-repo/semantics/publishedVersio

    Asymmetric visual input and route recapitulation in homing pigeons

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    Pigeons (Columba livia) display reliable homing behaviour, but their homing routes from familiar release points are individually idiosyncratic and tightly recapitulated, suggesting that learning plays a role in route establishment. In light of the fact that routes are learned, and that both ascending and des- cending visual pathways share visual inputs from each eye asymmetrically to the brain hemispheres, we investigated how information from each eye con- tributes to route establishment, and how information input is shared between left and right neural systems. Using on-board global positioning system loggers, we tested 12 pigeons’ route fidelity when switching from learning a route with one eye to homing with the other, and back, in an A-B-A design. Two groups of birds, trained first with the left or first with the right eye, formed new idiosyncratic routes after switching eyes, but those that flew first with the left eye formed these routes nearer to their original routes. This confirms that vision plays a major role in homing from familiar sites and exposes a behavioural consequence of neuroanatomical asymmetry whose ontogeny is better understood than its functional significance

    Evolutionarily conserved mechanisms of male germline development in flowering plants and animals

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    Sexual reproduction is the main reproductive strategy of the overwhelming majority of eukaryotes. This suggests that the last eukaryotic common ancestor was able to reproduce sexually. Sexual reproduction reflects the ability to perform meiosis, and ultimately generating gametes, which are cells that carry recombined half sets of the parental genome and are able to fertilize. These functions have been allocated to a highly specialized cell lineage: the germline. Given its significant evolutionary conservation, it is to be expected that the germline programme shares common molecular bases across extremely divergent eukaryotic species. In the present review, we aim to identify the unifying principles of male germline establishment and development by comparing two very disparate kingdoms: plants and animals. We argue that male meiosis defines two temporally regulated gene expression programmes: the first is required for meiotic commitment, and the second is required for the acquisition of fertilizing ability. Small RNA pathways are a further key communality, ultimately ensuring the epigenetic stability of the information conveyed by the male germline

    Instagram: A gimmick or a serious reputation builder in the airline business?

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    The purpose of the research is to shed light on the interrelatedness between Instagram and corporate reputation on the one hand and customer service expectations on the other. A conceptual model is proposed to be tested in the context of the civil aviation economy. A national flagship airline company was chosen in which to conduct the research. An online questionnaire was made available and 283 responses were collected. Partial Least Squares Structural Equation Modelling (PLS-SEM) was used to test research hypotheses derived from the literature. The novelty of the work is in the scarce research found when scrutinizing the literature on possible links between Instagram and airline corporate reputation. The study found there to be a positive correlation between social media usage and corporate reputation in the airline sector. Future research needs to replicate this study across other airlines to ascertain the external validity of the current study and its potential for extrapolation.info:eu-repo/semantics/acceptedVersio
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