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941.
Diana Soto José Urdaneta Kelly Pernia Orietta León Alexandra Muñoz-Bonilla Marta Fernández-García 《Journal of Polymers and the Environment》2016,24(4):343-355
Hydrogels were synthesized by free radical graft copolymerization of itaconic acid (IA) onto corn starch (S-g-IA). For this purpose, potassium permanganate (KMnO4)-sodium bisulfite (NaHSO3) was used as redox initiation system. The formation of grafted starches was confirmed by Fourier transform infrared spectroscopy, wide angle X-ray scattering, thermogravimetric analysis and scanning electron microscopy. The effect of monomer concentration, neutralization, addition of crosslinking agent, N,N-bismetilenacrilamide (MBAm), and initiator concentration on grafting efficiency and adsorption capacity of the starch hydrogels was investigated. It was demonstrated that the introduction of carboxyl and carbonyl groups promoted starch hydration and swelling. Grafting degree increased with the decrease of monomer concentration, increase of initiator concentration, grade of neutralization and the addition of MBAm without neutralization. Remarkably the resulting materials exhibited water absorption capacities between 258 and 1878% and the ability to adsorb metal ions. It was experimentally confirmed the metal uptake, obtaining the higher adsorption capacity (q e = 35 mg/g) for the product prepared with the pre-oxidation and lower initiator concentration. The removal capacity order was Pb2+>Ni2+>Zn2+>Cd2+. Moreover, the experimental kinetic and the equilibrium adsorption data for Ni2+ and Pb2+ were best fitted to the pseudo-second order and Freundlich isotherm models, respectively. This work describes for the first time the preparation of metal removal hydrogels based on starch and itaconic acid using the pair redox system KMnO4/NaHSO3, which avoids the starch hydrolysis and allows itaconic acid grafting incorporation without the requirement of more reactive comonomers. 相似文献
942.
943.
Carotenoid pigments cannot be synthesized by vertebrates but must be ingested through the diet. As they seem to be a limited
resource, carotenoid-based ornaments are particularly interesting as possible honest signals of individual quality, in particular
of foraging efficiency and nutritional status. Some studies have demonstrated the condition dependence of carotenoid-based
plumage in birds. However, many other carotenoid-pigmented bare parts (i.e. skin, caruncles, bills, cere, and tarsi) are present
in birds but, in comparison with plumage, little is known about these traits as indicators of individual quality. Here, we
show that the eye ring pigmentation and bill redness of the red-legged partridge (Alectoris rufa) are positively associated to body condition and recent changes in body mass. Also, we found a negative relationship between
these two traits and heterophil-to-lymphocyte ratio, an indicator of physiological stress (the relationship with bill redness
being significant only for males). In an experiment, we found that after a period of reduction in food intake (with the consequent
loss of body mass), food-restricted birds showed lower eye ring pigmentation than ad-libitum-fed birds. Therefore, different
ornaments seem to reflect changes in body condition but at different speeds or intensities (eye ring, a fleshy ornament, appears
to respond more rapidly to changes in the nutritional status than a keratinized structure as the bill). These results indicate
that carotenoid-based ornaments are condition-dependent traits in the red-legged partridge, being therefore susceptible to
be employed as honest signals of quality in sexual selection. 相似文献
944.
David W. Gibbons Chris Sandbrook William J. Sutherland Rezvin Akter Richard Bradbury Steven Broad Andy Clements Humphrey Q. P. Crick Joanna Elliott Ngawang Gyeltshen Melanie Heath Jonathan Hughes Richard K. B. Jenkins Alastair H. Jones Rocio Lopez de la Lama Nicholas B. W. Macfarlane Mike Maunder Ravikash Prasad Alfredo Romero-Muñoz Noa Steiner James Tremlett Rosie Trevelyan Savita Vijaykumar Irushinie Wedage Nancy Ockendon 《Conservation biology》2022,36(1):e13781
The COVID-19 pandemic has had an enormous impact on almost all aspects of human society and endeavor; the natural world and its conservation have not been spared. Through a process of expert consultation, we identified and categorized, into 19 themes and 70 subthemes, the ways in which biodiversity and its conservation have been or could be affected by the pandemic globally. Nearly 60% of the effects have been broadly negative. Subsequently, we created a compendium of all themes and subthemes, each with explanatory text, and in August 2020 a diverse group of experienced conservationists with expertise from across sectors and geographies assessed each subtheme for its likely impact on biodiversity conservation globally. The 9 subthemes ranked highest all have a negative impact. These were, in rank order, governments sidelining the environment during their economic recovery, reduced wildlife-based tourism income, increased habitat destruction, reduced government funding, increased plastic and other solid waste pollution, weakening of nature-friendly regulations and their enforcement, increased illegal harvest of wild animals, reduced philanthropy, and threats to survival of conservation organizations. In combination, these impacts present a worrying future of increased threats to biodiversity conservation but reduced capacity to counter them. The highest ranking positive impact, at 10, was the beneficial impact of wildlife-trade restrictions. More optimistically, among impacts ranked 11-20, 6 were positive and 4 were negative. We hope our assessment will draw attention to the impacts of the pandemic and, thus, improve the conservation community's ability to respond to such threats in the future. 相似文献
945.
Branß Till Núñez-González Francisco Aberle Jochen 《Environmental Fluid Mechanics》2022,22(2-3):559-585
Environmental Fluid Mechanics - Natural levees are wedge-shaped morphological features developing along the boundaries of mass flows. When they form in fluvial landscapes, they can have multiple... 相似文献
946.
Rolón Eugenia Rosso Juan José Mabragaña Ezequiel Tripodi Pamela Bavio Marta Bidone Camila Volpedo Alejandra V. Avigliano Esteban 《Environmental science and pollution research international》2022,29(39):58843-58868
Environmental Science and Pollution Research - Environmental pollution affects the quality of the natural environment where major and trace elements have been commonly found to accumulate in biotic... 相似文献
947.
Pantoja-Echevarría Laura María Tamburin Elena Elorriaga-Verplancken Fernando R. Marmolejo-Rodríguez Ana Judith Galván-Magaña Felipe Tripp-Valdez Arturo Lara Ariagna Jonathan M. P. Sujitha S. B. Delgado-Huertas Antonio Arreola-Mendoza Laura 《Environmental science and pollution research international》2022,29(41):61685-61697
Environmental Science and Pollution Research - Sharks are top predators and play an important role in the regulation of marine ecosystems at lower trophic position. Mustelus californicus, Sphyrna... 相似文献
948.
Reyes-Márquez Alejandra Aguíñiga-García Sergio Morales-García Sandra Soledad Sedeño-Díaz Jacinto Elías López-López Eugenia 《Environmental science and pollution research international》2022,29(41):61643-61661
Environmental Science and Pollution Research - Trophic transfer and bioaccumulation of trace metals have a profound impact on the structure and function of coastal areas; however, the metal... 相似文献
949.
del Real Álvaro Expósito Andrea Ruiz-Azcona Laura Santibáñez Miguel Fernández-Olmo Ignacio 《Environmental science and pollution research international》2022,29(42):62973-62983
Environmental Science and Pollution Research - We aimed to determine the presence of SARS-CoV-2 RNA in indoor and outdoor size-segregated aerosol samples (PM10-2.5, PM2.5). Five outdoor daily... 相似文献
950.
Cañaveras JC Cuezva S Sanchez-Moral S Lario J Laiz L Gonzalez JM Saiz-Jimenez C 《Die Naturwissenschaften》2006,93(1):27-32
In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber calcite
crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals,
extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation
in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been
able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us
to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding
that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes. 相似文献