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Nevertheless, after MW treatment, the primary hydroxyl groups of hemicellulose are mainly affected, since the hemicellulose molecule reacts with electromagnetic fields of MW and promote a high reactivity with the OH groups adjacent to the glycosidic bonds of the cellulose (Ren and Sun [36]). Microwave Radiation as Alternative to Modify Natural Fibers: Recent Trends and Opportunities - A Review Microwave treatment Microwaves (MW) are a electromagnetic radiation with a wavelength range from 1 mm to 1 m at a frequency between 0.3 and 300 GHz. Keywords: Natural fibers; cellulose; lignocellulosic wastes; microwave; dielectric heating; : ; ; ; ; EN Natural fibers cellulose lignocellulosic wastes microwave dielectric heating ZH : 7594 7610 17 11/21/22 20221220 NES 221220 Introduction Today, some agri-food industries generate large amounts of lignocellulosic wastes (natural fibers, bagasse, seeds, wood, swept away waste, sludge, etc.), which causes an environmental problem. [Extracted from the article]

Policosanol is a mixture of higher aliphatic alcohols purified from sugar cane wax, with cholesterol-lowering effects demonstrable in experimental models and in patients with type II hypercholesterolemia. The protective effects of policosanol on atherosclerotic lesions experimentally induced by lipofundin in rabbits and rats and spontaneously developed in stumptail monkeys have been described. The present study was conducted to determine whether policosanol administered orally to rabbits with exogenous hypercholesterolemia also protects against the development of atherosclerotic lesions. Male New Zealand rabbits weighing 1.5 to 2 kg were randomly divided into three experimental groups which received 25 or 200 mg/kg policosanol (N = 7) orally for 60 days with acacia gum as vehicle or acacia gum alone (control group, N = 9). All animals received a cholesterol-rich diet (0.5%) during the entire period. Control animals developed marked hypercholesterolemia, macroscopic lesions and arterial intimal thickening. Intima thickness was significantly less (32.5 ± 7 and 25.4 ± 4 µm) in hypercholesterolemic rabbits treated with policosanol than in controls (57.6 ± 9 µm). In most policosanol-treated animals, atherosclerotic lesions were not present, and in others, thickness of fatty streaks had less foam cell layers than in controls. We conclude that policosanol has a protective effect on the atherosclerotic lesions occurring in this experimental model.

Panamá es una de las regiones biológicamente más importantes del planeta, debido a su variada riqueza de ecosistemas y de especies de flora y fauna. Esta variedad se debe a un conjunto de factores, como su historia y su posición geográfica, ubicada en la Región Neotropical como puente natural entre Norte y Suramérica. La conservación de la diversidad biológica ha dejado de significar la simple protección de especies y ecosistemas, para convertirse en parte fundamental de las propuestas hacia el desarrollo sostenible de los pueblos. Entre los primeros pasos hacia una sostenibilidad ambiental, están los estudios de la evaluación de su biodiversidad, gracias a las cuales se acordó formular estrategias y planes de acción nacional e integrar actividades relacionadas con la sostenibilidad y la conservación de la biodiversidad en todos los sectores de la población. Se presenta un panorama amplio de la importancia de la conservación ex situ y su relación con la sostenibilidad ambiental, la cual se fundamenta básicamente en el uso de los recursos, pero sin afectar el disfrute de estos por las generaciones futuras.

La introducción de especies exóticas e invasoras y sus impactos a la biodiversidad de los ecosistemas, constituye una de las grandes preocupaciones ambientales para la comunidad internacional. Los cambios que sufren las poblaciones y comunidades nativas después de la introducción de especies exóticas aportan evidencias sobre los impactos de estos últimos. Las características ecológicas de cada especie, sus posibilidades de producción y su papel económico en los países de introducción, son factores que condicionan las perspectivas de su mejora, las directrices de la investigación por emprender y los métodos de trabajo. Algunos pensarían que la introducción de especies aumenta la biodiversidad de la región, pero en muchos casos el efecto ha sido el opuesto. Las nuevas especies suelen ser excelentes depredadores que eliminan a las nativas, que no están acostumbradas a su presencia. Las especies introducidas no solo resultan ser depredadoras, sino, también, compiten con las nativas por los recursos disponibles en el nuevo hábitat.

Primary productivity in the Arctic Ocean is experiencing dramatic changes linked to the receding sea ice cover. The vertical transport of nutrients from deeper water layers is the limiting factor for primary production. Here, we compare coincident profiles of turbulence and nutrients from the Siberian Seas in 2007, 2008, and 2018. In all years, the water column structure in the upstream region of the Arctic Boundary Current promotes upward nutrient transport, in contrast to the regions further downstream, and there are first indications for an eastward progression of these conditions. In summer 2018, strongly enhanced vertical nitrate flux and primary production above the continental slope were observed, likely related to a remote storm. The estimated contribution of these elevated fluxes above the slope to the Pan‐Arctic vertical nitrate supply is comparable with the basin‐wide transport, and is predicted to increase with declining sea ice cover in the future. Plain Language Summary: Microscopic algae, growing in the sunlit surface layer of the ocean, provide food for other species and form the basis of the ecosystem. In the Arctic Ocean, their growth is limited by the availability of nutrients. The main source of these nutrients are waters entering from the Atlantic and Pacific Oceans. These nutrient‐rich waters reside far below the sunlit zone, and vertical mixing is required to bring them upwards to support algal growth. With rapidly declining summer sea ice and changes in the ocean layering, these mixing processes might substantially change. Changes are considered most likely in the region of the steep slopes in the Siberian Seas. To investigate this, we analyze nutrient and mixing measurements in this region from 2007, 2008, and 2018. In 2018, we observed strong mixing, which is connected to ice free conditions and a process that has only recently been described. This strong mixing only happens at the narrow, steep slope region, but might supply the same amount of nutrients to the surface zone as the weak mixing over the much larger area of the deep basins. Key Points: Nutrient fluxes are higher in the western compared with the eastern Laptev SeaEpisodic mixing above the slope might significantly contribute to Pan‐Arctic vertical nitrate supplyIn the central Laptev Sea, a thinning halocline and shoaling Atlantic Water indicate an emerging regime shift in line with Atlantification [ABSTRACT FROM AUTHOR]

The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three‐dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assess this possibility by evaluating inorganic nutrient budgets for 2004 and 2010 in the North Atlantic based on observations from the transatlantic A05‐24.5°N and the Greenland‐Portugal OVIDE hydrographic sections, to which we applied a box inverse model to solve the circulation and estimate the across‐section nutrient transports. Full water column nutrient budgets were split into upper and lower meridional overturning circulation (MOC) limbs. According to our results, anomalous circulation in early 2010, linked to extreme negative NAO conditions, led to an enhanced northward advection of more nutrient‐rich waters by the upper overturning limb, which resulted in a significant nitrate and phosphate convergence north of 24.5°N. Combined with heaving of the isopycnals, this anomalous circulation event in 2010 favored an enhancement of the nutrient consumption (5.7 ± 4.1 kmol‐P s−1) and associated biological CO2 uptake (0.25 ± 0.18 Pg‐C yr−1, upper‐bound estimate), which represents a 50% of the mean annual sea–air CO2 flux in the region. Our results also suggest a transient state of deep silicate divergence in both years. Both results are indicative of a MOC‐driven modulation of the biological carbon uptake (by the upper MOC limb) and nutrient inventories (by the lower MOC limb) in the North Atlantic. Key Points: The overturning circulation lower limb drives a net southward transport of oxygen and nutrients from the North to the South AtlanticAnomalous circulation in 2010 enhanced nutrient convergence by the overturning upper limb, boosting North Atlantic biological CO2 uptakeWe observed a deep silicate divergence in the North Atlantic in 2004 and 2010 compatible with a transient response to reduced overturning [ABSTRACT FROM AUTHOR]

Ocean biological processes play an important role in the global carbon cycle via the production of organic matter and its subsequent export. Often, this flux is assumed to be in steady state; however, it is dependent on nutrients introduced to surface waters via multiple mechanisms, some of which are likely to exhibit both intra‐annual and interannual variability leading to comparable variability in ocean carbon uptake. Here we test this variability using surface (5 m) inorganic nutrient concentrations from voluntary observing ships and satellite‐derived estimates of chlorophyll and net primary production. At lower latitudes, the seasonality is small, and the monthly averages of nitrate:phosphate are lower than the canonical 16:1 Redfield ratio, implying nitrogen limitation, a situation confirmed via a series of nutrient limitation experiments conducted between Bermuda and Puerto Rico. The nutrient seasonal cycle is more pronounced at higher latitudes, with clear interannual variability. Over a large area of the midlatitude North Atlantic, the winters of 2009/2010 and 2010/2011 had nitrate values more than 1μmol L−1 higher than the 2002–2017 average, suggesting that during this period, the system may have shifted to phosphorus limitation. This nitrate increase meant that, in the region between 31° and 39° N, new production calculated from nitrate uptake was 20.5g C m−2 in 2010, more than four times higher than the median value of the whole observing period. Overall, we suggest that substantial variability in nutrient concentrations and biological carbon uptake occurs in the North Atlantic with interannual variability apparent over a number of different time scales. Key Points: Surface nitrate and phosphate concentrations have been higher after 2011 in the North Atlantic Subtropical GyreThe winter seasons of 2010 and 2011 had anomalously high concentrations of surface nitrate across the North AtlanticThis caused an up to fourfold increase in new production in the Central North Atlantic [ABSTRACT FROM AUTHOR]