Browsing by Issue Date, starting with "2017-09"
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- The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomenaPublication . Lindman, Bjorn; Medronho, Bruno; Alves, Luis; Costa, Carolina; Edlund, Hakan; Norgren, MagnusCellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.
- Gender-specific histopathological response in guppies Poecilia reticulata exposed to glyphosate or its metabolite aminomethylphosphonic acidPublication . Antunes, Adriana Maria; Lopes Rocha, Thiago; Pires, Fernando Santiago; de Freitas, Meire Alves; Milhomem Cruz Leite, Vanessa Rafaela; Arana, Sarah; Moreira, Paulo Cesar; Teixeira Saboia-Morais, Simone MariaEcotoxicity of glyphosate (GLY) and itsmetabolite aminomethylphosphonic acid (AMPA) was investigated in guppies, Poecilia reticulata. We tested the effects of these chemicals on the gills and liver of bothmale and female guppies using qualitative and quantitative histopathological analyses associated with histopathological condition indexes. Both genders showed similar median lethal concentration (LC50) at 96 h for GLY (68.78 and 70.87mg l(-1)) and AMPA (180 and 164.32mg l(-1)). However, the histopathological assessment of both fish organs exposed to sublethal concentrations of GLY (35mg l(-1)) and AMPA ( 82mg l(-1)) for 96h showed a tissue-and gender-specific histopathological response. In both exposure assays, fish presented mainly progressive changes, such as proliferation of the interlamellar epithelium, partial and total fusion of secondary lamellae. The liver showed mainly regressive changes, such as steatosis, pyknotic nuclei and high distribution of collagen fibers. Unusually large hepatocytes as degenerated cells were also detected. Histopathological changes in gills were similar for the males and females, but the liver response was different between the genders. The hepatic inflammatory changes were more common in males. The increase in the area of hepatocyte vacuoles is gender dependent with higher values in the male compared to the female guppies exposed to GLY and AMPA. Multiparametric analysis indicated that the male guppies are-more sensitive than females, particularly in the presence of AMPA. Our study shows that the histopathological assessment associated with gender-specific response can be successfully used in ecotoxicological assessment of GLY and the metabolite AMPA. Copyright (C) 2017 JohnWiley & Sons, Ltd.
- Trade of live bait in Portugal and risks of introduction of non-indigenous species associated to importationPublication . Sa, Erica; Fidalgo e Costa, Pedro; Cancela Da Fonseca, Luís; Alves, Ana Sofia; Castro, Nuno; Cabral, Sara dos Santos; Chainho, Paula; Canning-Clode, Joao; Melo, Pedro; Pombo, Ana Margarida; Costa, Jose LinoDifferent invertebrate groups are often exploited on sediment shores and mudflats, including polychaetes, sipunculids, bivalves and crustaceans. The commercial importance of polychaetes and sipunculids, that has increased in the early 2000's because of its use as a food source for the aquaculture sector and a growing demand of worms for use as sea angling bait, seems to be declining nowadays. In Portugal bait harvesting from natural populations became insufficient to meet market demands and as a result, polychaetes and sipunculids have been imported in recent years. Due to this it was important to know the ways of the live bait import to Portugal, and to assess the risk of introduction of non-indigenous species associated to that live bait trade. The origin and quantities of imported live bait were determined by examining the landing's records at Lisbon airport, from two periods: 2002-2003 and 2012-2015. Live worms imported to Portugal arrived almost exclusively from China, USA and Vietnam. Monthly import data and bait registers at fish auction landings were significantly correlated, showing that bait captures and imports are directly related to higher bait demand. In addition, the risk of live bait's importation as an introduction vector for non-indigenous species was evaluated by examining the bait boxes content. Five worm species were identified in bait boxes with foreign species: Glycera dibranchiata, Namalycastis rhodochorde, Perinereis cultrifera, Perinereis lines, and Sipunculus (Sipunculus) nudus. The examination of bait boxes in Portugal suggested that there is a low risk of associated hitchhiker species introduction and dissemination, mostly because of packaging procedures, which should be advised. The same is not true to the non-indigenous live bait species. (C) 2017 Elsevier Ltd. All rights reserved:
- A cork-silica xerogel nanocomposite with unique propertiesPublication . Garcia, Ana; Julio, M. F.; Ilharco, L. M.Taking advantage of the bonding between cork and silica xerogel, environmentally friendly nanocomposites are synthesized by a sol-gel process and dried at ambient pressure, with a superb combination of properties: densities near 600 kg m(-3), surface areas of 200 m(2) g(-1), mechanical strength up to 24 MPa, Shore D hardness up to 58 and, moreover, flame retardant. These properties are tunable by adjusting the synthesis parameters. The effects of cork granulometry and pre-swelling, and of the catalysis conditions are analyzed. Potential applications for these innovative nanocomposites are envisaged as replacement of thermoplastic polymers or hard wood, when non-flammability is desirable. The present approach opens a range of possibilities for developing unique composite materials that use natural and inexpensive raw resources and soft synthesis processes, with little energy requirements. [GRAPHICS]
- Population and production parameters of the wedge clam Donax trunculus (Linnaeus, 1758) in intertidal areas on the southwest Spanish coast: Considerations in relation to protected areasPublication . Delgado, Marina; Silva, Luis; Gomez, Santiago; Masferrer, Esther; Cojan, Miguel; Gaspar, MiguelThe main objectives of this study were (i) to provide an updated age-length key for D. trunculus from Atlantic waters, and (ii) to evaluate population dynamics, the timing of recruitment and production parameters of the wedge clam Donax trunculus in two moderately exposed sandy beaches (the protected area of Donana National Park and the tourist destination of Isla Canela) along the littoral of Huelva (SW Spain). First an in-depth analysis of the shell and updated estimation of growth parameters of the intertidal D. trunculus population were performed between January 2014 and July 2015 using two different methods i) thin-layer cross section (TL) (ii) length-frequency distributions (LFD). Von Bertalanffy growth functions provided an asymptotic length of 46 mm (LFD) and 46.7 mm (TL) and growth constants of 0.48 (LFD) and 0.47 yr(-1) (TL) in Donana beach. In addition, several deformities as well as signs of shell repair were observed. Population dynamics analyses through length frequency distribution clarified the timing of recruitment (February-March and July). The mean annual biomass ((B) over bar) of intertidal populations of D. trunculus ranged between 3.03 (Donana) and 3.31 g ash-free dry mass (AFDW) m(-2) yr(-1) (Isla Canela). Individual production showed the highest value at 27 mm length (0.117 g AFDW m(-2) yr(-1)) and annual production (P) ranged between 3.40 (Donana) and 4.91 g (Isla Canela), resulting in renewal rate (P/(B) over bar) values between 1.03 and 1.61, respectively. The present results, together with information on environmental parameters, revealed clear differences in population dynamics and production between beaches related to the presence or absence of a protection figure.
- The contribution of genetics and environment to obesityPublication . Albuquerque, David; Nóbrega, Clévio; Manco, Licínio; Padez, CristinaBackground: Obesity is a global health problem mainly attributed to lifestyle changes such as diet, low physical activity or socioeconomics factors. However, several evidences consistently showed that genetics contributes significantly to the weight-gain susceptibility. Sources of data: A systematic literature search of most relevant original, review and meta-analysis, restricted to English was conducted in PubMed, Web of Science and Google scholar up to May 2017 concerning the contribution of genetics and environmental factors to obesity. Areas of agreement: Several evidences suggest that obesogenic environments contribute to the development of an obese phenotype. However, not every individual from the same population, despite sharing the same obesogenic environment, develop obesity. Areas of controversy: After more than 10 years of investigation on the genetics of obesity, the variants found associated with obesity represent only 3% of the estimated BMI-heritability, which is around 47-80%. Moreover, genetic factors per se were unable to explain the rapid spread of obesity prevalence. Growing points: The integration of multi-omics data enables scientists having a better picture and to elucidate unknown pathways contributing to obesity. Areas timely for developing research: New studies based on case-control or gene candidate approach will be important to identify new variants associated with obesity susceptibility and consequently unveiling its genetic architecture. This will lead to an improvement of our understanding about underlying mechanisms involved in development and origin of the actual obesity epidemic. The integration of several omics will also provide insights about the interplay between genes and environments contributing to the obese phenotype.
- Regional assessment of storm related overwash and breaching hazards on coastal barriersPublication . Plomaritis, Theocharis A.; Ferreira, Óscar; Costas, SusanaCoastal communities are threatened by the impact of severe storms that may cause significant loss of life and damage to properties. Among the main processes behind such impacts on coastal barriers are the occurrence of overwash and breaching during storm events. In order to estimate potential losses associated with a particular event, the above processes must be properly parameterized. Here, we propose a novel methodology to estimate overwash and breaching hazards suitable for a regional scale analysis (Ø 100 km). For the overwash hazard assessment, the method is based on the application of the approach developed by Donnelly (2008) that allows the parametrisation of the overwash hazard considering both flow velocity and flow depth. Moreover, the inland extension of the associated hazard, which is critical to assess subsequent vulnerability, can also be estimated following this methodology. The proposed method requires the selection of a runup formula validated for the study area, a storm beach profile, a runup lens angle, and a percolation constant for infiltration. To assess the breaching, hazard, a new multivariable evaluation is proposed that allows ranking the potential of breaching. The multivariable evaluation combines overwash and erosion hazards as well as their extensions with the main morphological characteristics of the barrier, resulting in the breaching hazard index, that ranks from 0 to 5 (no breaching to inlet formation). Inland breaching extension is also relevant for the vulnerability assessment. The breaching extension can be estimated using historical or contemporary analogues of the nearest flood deltas. The developed approaches were applied to Ancão Peninsula (Algarve, Portugal) as a demonstration example. The advantages of the present approach are: adaptability to various environments where overwash and/or breaching processes are important, time efficiency on evaluating overwash and breaching hazards, and the assessment of hotspot areas at a regional scale.
- Pediatric chronic osteomyelitis in the outskirts of Al-Ushbuna (Carnide, Lisboa, Portugal)Publication . Tavares, Ana; Makhoul, Calil; Monteiro, Mario; Curate, FranciscoThe skeletal remains of seven individuals (five non-adults and two adults) were recovered during an archeological intervention in the township of Carnide (Lisbon, Portugal). Funerary anthropology strongly suggests that the sample is from the Medieval Islamic period (8th -12th centuries AD). This report presents a case of chronic osteomyelitis in a non-adult individual. The diagnostic is substantiated by the presence of pathognomonic signs of osteomyelitis, including the presence of cloacae and a sequestrum in the left tibia. The bone infection is discussed in the context of inadequate socioeconomic conditions. This case from a relatively unfamiliar chronology and cultural context supplements the uncommon paleopathological descriptions of osteomyelitis in non-adults from historical populations.
- Maximal operator with rough kernel in variable musielak-morrey-orlicz type spaces, variable herz spaces and grand variable lebesgue spacesPublication . Rafeiro, Humberto; Samko, StefanIn the frameworks of some non-standard function spaces (viz. Musielak-Orlicz spaces, generalized Orlicz-Morrey spaces, generalized variable Morrey spaces and variable Herz spaces) we prove the boundedness of the maximal operator with rough kernel. The results are new even for p constant.
- Deregulation of the retinal renin-angiotensin system precedes the onset of diabetic retinopathyPublication . S, Simão; Bitoque, D. B.; Santos, D. F.; Araújo, Inês; Silva, G. A.The renin-angiotensin system (RAS) is a set of complex pathways with a well-defined function in the regulation of blood pressure and body fluid homeostasis.