La espiral del residuo

Entre dos o más estudiantes de educación básica secundaria, practican el juego “la espiral del residuo”, cuyos materiales son: tablero con 20 casillas, 14 de ellas numeradas del 6 al 19, un dado y una ficha para cada participante. Un jugador lanza el dado, y para avanzar en el tablero, debe calcular el residuo de dividir el número en que se encuentre, por el obtenido en el dado. Se busca que los estudiantes se apropien del algoritmo de la división y adquieran claridad sobre los elementos que en esta operación intervienen: dividendo, divisor, cociente, residuo

Effects of vacuum and modified atmosphere packaging on the quality and shelf-life of gray triggerfish (Balistes capriscus) fillets

Seafood products are perceived as healthy foods. However, several species of seafood are still not fully utilized for different reasons or can be valued outside the original locale, if issues with the short shelf-life and/or the preparation/presentation form are overcome, e.g., gray triggerfish, Balistes capriscus. Consumed mostly fresh, its flesh is of excellent quality. We studied the effect of different types of packaging (in air (AIR), vacuum (VP), and modified atmosphere (MAP)) on physicochemical (color and texture, pH, and total volatile basic nitrogen), microbiological (total viable count, psychrotrophic, sulphide-reducing bacteria, and acid-lactic bacteria), and sensory qualities, and shelf-life of gray triggerfish fillets stored at refrigeration temperature for 15 days. The samples were analyzed on days 0 (fresh fish), 5, 10 (8 and 12 for sensory analysis), and 15 after filleting and packaging. During the trial, fillets became lighter (increased L*) and yellower (b* >> 0) with time of storage. Distinct patterns were observed for pH among treatments. Unexpectedly, the increasing trend observed in the texturometer-derived hardness of VP and MAP fillets, contrasted with the sensory assessment, wherein panelists perceived a clear softening of fillets. VP delayed and MAP inhibited the increase in TVB-N contents of fillets compared to fillets packed in AIR. Total viable count and psychrothropic bacteria of fillets in AIR exceeded the conventional limit of 7 log(CFU/g) on day 10, while in fillets packed in VP and MAP, their abundance remained below that limit during the trial. The organoleptic attributes of fillets perceived by a sensory panel changed significantly in all treatments during the storage trial. Willingness to consume the fillets decreased constantly in AIR and MAP, but not in VP fillets. Considering primarily sensory, but also biochemical and microbiological parameters, namely panelists’ rejection, total volatile basic nitrogen content, and total viable count and psychrotrophic bacteria abundance, the shelf-life of fillets packed in air was eight days. Vacuum and modified atmosphere packaging extended the shelf-life to 15 and 12 days, and thus can add value to this product. Future research regarding the VP and MAP of gray triggerfish fillets could involve the optimization of mixtures of gases use and/or the application of combined processes.FCT-Foundation for Science and Technology (Portugal) [UIDB/04326/2020] Portuguese Foundation of Science and Technology (FCT) to CIMA through UIDP/00350/2020.info:eu-repo/semantics/publishedVersio

Idade e crescimento do boca-negra, Helicolenus dactylopterus dactylopterus (Delaroche, 1809) dos Açores

A idade e o crescimento de boca-negra, Helicolenus dactylopterus dactylopterus (Delaroche, 1809), foram estudadas pela observação dos otólitos (sagittae) esquerdos inteiros (n = 401) obtidos de exemplares (14-47 cm de comprimento total) capturados em águas Açoreanas. Enumeraram-se os anéis opacos observados na face anti-sulcal dos otólitos. Os intervalos de idades foram 3-14 anos para machos e 3-12 anos para fêmeas. Estimaram-se e compararam-se os parâmetros da equação de crescimento de von Bertalanffy, entre sexos e entre métodos (leitura directa de otólitos, retrocálculo e análise de distribuições de frequências de comprimentos). Não se verificaram diferenças importantes. Os resultados são diferentes da literatura publicada para a região. Discutem-se as causas e implicações dos resultados obtidos.ABSTRACT: Bluemouth, Helicolenus dactylopterus dactylopterus (Delaroche, 1809), age and growth were studied by whole-view examination of left sagittae (n = 401) obtained from specimens (14-47 cm in total length) caught off the Azores. Opaque rings observed on the anti-sulcal surface of sagittae were enumerated as age estimates. Ages ranged from 3 to 14 years in males and 3 to 12 years in females. The von Bertalanffy growth equation was fitted to average length at age data, and compared between sexes and methods (direct examination of otoliths, backcalculation and length-frequency analysis). No important differences in growth between sexes were found. Results are different from published literature for the region. The causes and implications of the results are discussed

State-of-the-art green roofs: Technical performance and certifications for sustainable construction

Green roof systems, a technology which was used in major ancient buildings, are currently becoming an interesting strategy to reduce the negative impact of traditional urban development caused by ground impermeabilization. Only regarding the environmental impact, the application of these biological coatings on buildings has the potential of acting as a thermal, moisture, noise, and electromagnetic barrier. At the urban scale, they might reduce the heat island effect and sewage system load, improve runoff water and air quality, and reconstruct natural landscapes including wildlife. In spite of these significant benefits, the current design and construction methods are not completely regulated by law because there is a lack of knowledge of their technical performance. Hence, this review of the current state of the art presents a proper green roof classification based on their components and vegetation layer. Similarly, a detailed description from the key factors that control the hydraulic and thermal performance of green roofs is given. Based on these factors, an estimation of the impact of green roof systems on sustainable construction certifications is included (i.e., LEED—Leadership in Energy and Environment Design, BREEAM—Building Research Establishment Environmental Assessment Method, CASBEE—Comprehensive Assessment System for Built Environment Efficiency, BEAM—Building Environmental Assessment Method, ESGB—Evaluation Standard for Green Building). Finally, conclusions and future research challenges for the correct implementation of green roofs are addressed

Análisis de posiciones puntuales en una misma estación con distintos equipos Doppler

Desde 1981 hasta la fecha, se han realizado observaciones reiteradas de los satélites TRANSIT desde un mismo punto situado en la terraza del edificio del Servicio de Hidrografía Naval [SHN]. Para ello se emplearon cuatro posicionadores Doppler diferentes: JMR-4 y Mini-Ranger (Motorola) del SHN, JMR-4A de la Dirección Nacional del Antártico y MX-1502 (Magnavox) del Instituto Geográfico Militar [IGM]. Los resultados se obtuvieron utilizando los microprocesadores de cada equipo, en el modo "posicionamiento puntual" y muestran importantes diferencias sistemáticas en longitud y altura. En este trabajo se analizan esas diferencias y se concluye que se deben fundamentalmente al uso de diferentes sistemas de referencia, pese a la utilización, en cada caso, de los mismos parámetros del elipsoide sobre el cual se proyectan las coordenadas espaciales para obtener coordenadas geodésicas.Since 1984 up to the present several observations of Transit satellites have been carried out from the terrace of the Servicio de Hidrografía Naval (SHN] (Naval Hidrographic Service) building. Four different Doppler receivers were used: JMR-4 and Mini- Ranger (Motorola) of the SHN, JMR-4A of the Dirección Nacional del Antártico ‘(National Direction of the Antarctics) and MX-1 502 (Magnavox) of the Instituto Geográfico Militar [IGM] (Military Geographic Institute). The results were secured by means of the microprocessors of each receivers in the "single positioning" mode and show important systematic differences in longitude and altitude. These differences are analyzed in this paper to conclude that they are mainly due to the use of different reference Systems despite of applying, in each case, the same parameters of the ellipsoid on which the spatial coordinates are projected to obtain geodetic coordinates.Asociación Argentina de Geofísicos y Geodesta

Metals from human activities in a coastal Lagoon Saltmarsh - Sediment toxicity and phytoremediation by Sarcocornia fruticosa

Anthropogenic pressure on coastal areas has been increasing in the last decades, threating the saltmarshes and the ecosystem services they provide. Sarcocornia fruticosa can have an important role in sequestration of metals from human activities. This study evaluated the effect of metal toxicity in saltmarsh sediment (measured by Ecological Risk Index-ERI) on S. fruticosa ability to metal (Cd, Cr, Ni, Pb and Zn) remediation (Enrichment Factor and metal translocation). The impact of urbanization was studied through the metal loads on stormwaters during two main rainfall events, and the industrial impact was assessed through data analyses in a saltmarsh area influenced by a stream that receives industrial runoffs. The S. fruticosa response on metal remediation was affected by ERI. In more polluted locations, retained metals on roots and prevented the most toxic (Cd and Pb) from reaching the aerial organs, avoiding tissues death and metal remobilisation to the saltmarsh. Meanwhile, in rhizosediments with conditions to high metal bioavailability, S. fruticosa transported Cd and Pb to aerial organs, but used the Zn translocation to decrease their toxicity. This halophyte resilience is important to saltmarsh metal sequestration in high toxicity conditions, and allows the maintenance of other ecosystem services, contributing to the environmental protection and public health.info:eu-repo/semantics/publishedVersio

Urban wastewater reuse for citrus irrigation in Algarve, Portugal—Environmental benefits and carbon fluxes

Water scarcity is increasing in the Mediterranean and alternative sources of water are needed to meet food production needs, protect the environment and reduce the effects of climate change. Currently, many urban wastewater treatment plants (WWTP) produce high volumes of treated effluents which can be an alternative source of water for agriculture irrigation, since they fulfill the quality requirements for crops and the environment. This work analyzed the quantity and quality of a treated effluent produced by an urban WWTP in Algarve, and the environmental benefits of its use on the irrigation of a citrus orchard, as an alternative to groundwater. Carbon dioxide emissions related to orange production were quantified and the orchard’s potential to sequester CO2 was estimated. The reuse of this urban wastewater is revealed to be technologically feasible and environmentally advantageous, avoiding the overexploitation of the local aquifer and preventing the eutrophication of aquatic ecosystems, contributing to the improvement of soil characteristics and decreasing the carbon emissions in orange production. Furthermore, it was found that during the five-month experimental period, the citrus orchard sequestered 87.5% of the CO2e emitted by WWTP in the effluent treatment, converting 72,623 kg of sequestered CO2 into orange biomassinfo:eu-repo/semantics/publishedVersio

Alguns aspectos da química agrícola

info:eu-repo/semantics/publishedVersio

Osmotic dehydration in native fruits (Mammea americana L. and Mammea americana L.) and vegetables (Capsicum annuum L.) of the Amazon region

Los productos nativos de la región Amazonas como el mamey, aguaymanto y pimentón están considerados como alimentos funcionales con una demanda creciente, pero con problemas de comercialización debido a su alta perecibilidad y al deficiente manejo postcosecha. El objetivo del presente trabajo fue elaborar frutas y hortalizas desecadas mediante deshidratación osmótica, utilizando solución azucarada como agente osmótico. El tratamiento preliminar que fueron sometidos las muestras fue por separado, esto debido a que las muestras en estudio presentan características propias, sin embargo, todas estas fueron sometidas a los mismos tratamientos de deshidratación osmótica a temperaturas de 35°C, 45 °C y 55 °C y a 30, 40, 50 y 60 °Brix según correspondía. La cinética de deshidratación osmótica de la pérdida de agua y ganancia de sólidos en el mamey (Mammea americana), la aguaymanto (Physalis peruviana L.), pimentón (Capsicum annuum L) presentaron una buena respuesta en disoluciones a 60 °Brix y 55 °C y el equilibrio es alcanzado a las 8, 11 y 7 horas respectivamente. Asimismo, el coeficiente de difusividad, presentan diferencia significativa con respecto al factor de la temperatura y la estructura interna, el área y la piel de contacto del producto influyen en gran medida en el proceso de deshidratación osmótica de los tres productos en estudio

Mechanical properties of concrete using recycled aggregates obtained from old paving stones

Nowadays, construction, maintenance, reparation, rehabilitation, retrofitting, and demolition from infrastructure and buildings generate large amounts of urban waste, which usually are inadequately disposed due to high costs and technical limitations. On the other hand, the increasing demand for natural aggregates for concrete production seriously affects mountains and rivers as they are the source of these nonrenewable goods. Consequently, the recycling of aggregates for concrete is gaining attention worldwide as an alternative to reduce the environmental impacts caused by the extraction of nonrenewable goods and disposal of construction and demolition waste (C&DW). Therefore, this article describes the effect on the mechanical properties of new concrete using recycled aggregates obtained from old paving stones. Results show that replacing 50% by weight of the fine and coarse aggregate fractions in concrete with recycled aggregate does not meaningfully affect its mechanical behavior, making the use of recycled aggregates in new precast paving stones possible. Therefore, the latter can reduce environmental impacts and costs for developing infrastructure and building projects