190 research outputs found
Validation and quality assurance applied to goat milk chemical composition: minerals and trace elements measurements
In the present study, quality assurance programmes were implemented to validate and control the analytical methodologies used for the characterization of minerals and trace elements in goat milk from Portuguese breeds. With the exception of chloride that was determined by potentiometric titration, all the other elements were determined by spectroscopic techniques after different sample decomposition: P was measured by ultraviolet-visible molecular absorption spectrometry, Ca, Fe, K, Mg, Mn, Na and Zn by flame atomic absorption spectrometry and Cd, Co, Cr, Cu, Mo, Ni and Pb by electrothermal atomic absorption spectrometry. The methods performance characteristics, namely specificity, limit of detection, limit of quantification, working range, precision and trueness were evaluated. Measurement uncertainty was expressed in terms of precision and trueness. Precision under intralaboratory reproducibility conditions was estimated from triplicate analysis, and the trueness component was estimated in terms of overall recovery using either skim milk powder certified reference materials or spiked samples. The results obtained are discussed on the basis of the performance criteria required by EC regulations to verify when a method is suitable for food control. The methods used for the characterization of minerals and trace elements in goat milk complied with EC requirements since there was no matrix influence, the Horrat values were < 2.0, recoveries were within the interval 1.00 ± 0.10 for minerals and 1.00 ± 0.20 for trace elements and the combined uncertainty of the results were lower than the maximum standard uncertainty calculated using the uncertainty function approach. In relation to the limits of detection and quantification, the limits obtained for Pb were lower than those specified by EC regulation
Minerals and trace elements from milk of indigenous Portuguese goat breads: preliminary results
Red mud-based geopolymers with tailored alkali diffusion properties and pH buffering ability
This study develop novel porous red mud (RM) based geopolymers and evaluates their potential to ensure prolonged pH control. Several properties of the novel geopolymers were examined including buffering ability, alkalis leaching behaviour, mineralogical composition, microstructure and physical properties. Two experimental plans were defined to evaluate the influence of porosity and RM content on those properties. The pH values of the eluted water and geopolymers OH ions leaching have been determined over time showing that total OH ions and the leaching rate can be tailored by controlling the geopolymers porous structure and the availability of free alkaline species. The lower pH gradient over 28th d (1.64 pH units) was achieved by combining a 0.025 wt% pore forming agent (aluminium powder) with 45 wt% MK replacement by red mud.
A high and prolonged buffer capacity was accomplished, proving that red mud-based geopolymers have potential to be applied as pH buffering material.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.info:eu-repo/semantics/publishedVersio
Are organic falls bridging reduced environments in the deep sea?: Results from colonization experiments in the Gulf of Cadiz
Organic falls create localised patches of organic enrichment and disturbance where enhanced degradation is mediated by diversified microbial assemblages and specialized fauna. The view of organic falls as “stepping stones” for the colonization of deep-sea reducing environments has been often loosely used, but much remains to be proven concerning their capability to bridge dispersal among such environments. Aiming the clarification of this issue, we used an experimental approach to answer the following questions: Are relatively small organic falls in the deep sea capable of sustaining taxonomically and trophically diverse assemblages over demographically relevant temporal scales Are there important depth- or site-related sources of variability for the composition and structure of these assemblages? Is the proximity of other reducing environments influential for their colonization? We analysed the taxonomical and trophic diversity patterns and partitioning (α- and β-diversity) of the macrofaunal assemblages recruited in small colonization devices with organic and inorganic substrata after 1-2 years of deployment on mud volcanoes of the Gulf of Cádiz. Our results show that small organic falls can sustain highly diverse and trophically coherent assemblages for time periods allowing growth to reproductive maturity, and successive generations of dominant species. The composition and structure of the assemblages showed variability consistent with their biogeographic and bathymetric contexts. However, the proximity of cold seeps had limited influence on the similarity between the assemblages of these two habitats and organic falls sustained a distinctive fauna with dominant substrate-specific taxa. We conclude that it is unlikely that small organic falls may regularly ensure population connectivity among cold seeps and vents. They may be a recurrent source of evolutionary candidates for the colonization of such ecosystems. However, there may be a critical size of organic fall to create the necessary intense and persistent reducing conditions for sustaining typical chemosymbiotic vent and seep organisms
Information representation in Displaced Archives: a meta-synthesis
The phenomenon of displaced archives emerges in the scientific literature as a kind of wicked problem. In addition to the conceptual diversity associated with this phenomenon present in the scientific literature from various fields (e.g., removed archives, migrated archives, seized archives, alienated archives, captured archives, diasporic archives, expatriated/repatriated archives, estray archival, disputed archival claims, replevin, etc.), there is a tendency in the scientific community to adopt the concept of displaced archives as a possible hypernym. The most recent definition of displaced archive is found in the report issued by the International Council on Archives through the Expert Group on Shared Archival Heritage, understood as "archives removed from the place of their creation, where the ownership of the archives is disputed by two or more parties" (Lowry 2020, 5). Nevertheless, one of the problems that makes this phenomenon a particular case is whether we can identify archives that are in the condition of displaced without there necessarily having to be claimant party(ies) for that purpose.
Although the most recurrent focus in addressing this phenomenon has been around the problems of restitution, repatriation, return or relocation, the identification and, more incisively, the representation of these documentary sets have remained obscured in scientific discourse. According to Winn (2015), one of the limiting factors in the identification of displaced archives consists, among others, in the inexistence of information access tools. For Lowry, "the catalogue is the key" (2017a, 8), not only as an instrument of access to information where the processes of organization and description are materialized with a view to its retrieval and access, but also as a mechanism of information representation that derives from the powers of archival mediation.
Studies on information representation suggest that, in the postmodern archival stream, it is not possible to ensure neutrality or impartiality in the representation of the content and structure of a fonds (MacNeil 2012) in finding aids. Such archival descriptions are supported by interpretative approaches that depend on the description and access policies adopted by custodians, which are not unrelated to the political, historical, socio-cultural, and institutional contexts of the environment where they were produced.
Considering that the finding aids can be genologically diverse (e.g., catalogues, inventories, guides, scripts, directories, indexes and databases), it is considered more productive to focus on the representation of archival information, from the perspective of how a "fluid, evolving, and socially constructed practice" (Yakel 2003, 2) is constituted as "the core of archival description produced to facilitate access to archival materials in the background of their creation and custodial history" (Zhang 2012, 49).
Considering that some of the studies on archival information representation have been problematized with greater incidence, although incipient, in Knowledge Organization and Information Science (Barros and Sousa 2020; Aguiar and Kobashi 2013; Tognoli 2013; Vital, Medeiros, and Brascher 2017; Corujo and Freitas 2021; Tognoli and Guimarães 2011; 2012; Troitiño Rodriguez 2018; Hjørland 2002), these studies have largely confined themselves to material and technical processes, physical (u. g., arrangement) and intellectual (u. g., classification and description), of concepts that conform to the bureaucratic dimension of the producers and/or custodial entities. In what concerns the displaced archives, the phenomenon itself challenges the core concepts of Archival Science, especially how these disputed documentary sets are represented from the point of view of provenance, integrity, organicity and how these representations are (re)constructed or destroyed in the process of archival mediation.
Based on these aspects, and given the scarcity of studies on this topic, this article focuses on how the representation of information about archives removed from their original social and territorial contexts has been addressed in the scientific literature. Thus, we intend to conduct a survey of scientific literature that informs about the trajectory of the information representation process from the removal process to the claim by the dispossessed communities that can be theoretically relevant to the scope of Knowledge Organization. Thus, based on the above, it justifies performing a synthesis of knowledge from scientific literature called meta-synthesis (Sandelowski and Barroso 2010; Grant and Booth 2009; Finfgeld-Connett 2018). Thus, this article is structured as follows: section 2.0 formulates the starting question and research objectives; section 3.0 outlines the methodological assumptions for this type of qualitative literature synthesis; section 4.0 presents the results of the empirical investigation; section 5.0 makes concluding remarks around limitations and implications, as well as future lines of research.info:eu-repo/semantics/submittedVersio
Below the Nation State: Power Asymmetry and Jurisdictional Boundaries around the Archives of Madeira Archipelago
The main purpose of this chapter is to describe a case study developed in a sub-national context between the Autonomous Region of Madeira and the National Archive ‘Torre do Tombo’ (ANTT). Our analysis will
focus theoretically on the etiologies of dispossession and empirically on a case study. Thus, the main questions that will lead this case study are: ‘Why were the Madeiran fonds taken in the past to or by ANTT?’ and ‘How were these Madeiran fonds represented in finding aids provided by ANTT and the RAM?’. Finally, based on nissological critiques,13 we will define and contextualise the notion of sub-national displaced archives as an underresearched subset of disputed archival claims, in order to reveal some particular aspects of this phenomenon.info:eu-repo/semantics/publishedVersio
Cork extractives exhibit thermo-oxidative protection properties in polypropylene-cork composites and as direct additives for polypropylene
The thermo-oxidative stability of polypropylene (PP) in composites containing 15 wt.% of cork and the performance of selected cork extracts as stabilizing additives for PP was evaluated by Oxidation Induction Time (OIT) and by Oxidation Onset Temperature (OOT). The results showed that cork increases the OIT of PP in the composite and it was identified that the cork extractives fraction is responsible for such behavior. Selected cork extracts with high antioxidant capacity (determined by dpph radical scavenging and oxygen reactive absorbance capacity assays) were compounded by extrusion with PP in 0.5 and 1.5 wt.%. It was found that the ethanol extract is the most effective as thermo-oxidative stabilizer for PP. At the loading level of 1.5%, the OIT increases from 3.8 (neat PP) to 29.7 min at 200 °C and from 1.2 (neat PP) to 9.0 min at 220 °C. The OOT also increases from 216 °C (neat PP) to 247 °C. Mechanical tests, performed on PP loaded with the cork extracts, showed that the presence of these extracts has no significant effect on the polymer mechanical performance. The results demonstrate the suitability of cork as a source of thermo-oxidative stabilizing additives for the formulation of polyolefins, and enable the exploitation of new routes of cork valorization.The authors are grateful to Amorim Cork Composites for providing the cork powder raw material. Ivo Aroso and Emanuel Fernandes are grateful for financial support of FCT through grants SFRH/BD/42273/2007 and SFRH/BPD/96197/2013, respectively. Funding was also granted from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS and from Project "Novel smart and biomimetic materials for innovative regenerative medicine approaches (Ref.: RL1-ABMR-NORTE-01-0124-FEDER-000016)" co-financed by North Portugal Regional Operational Programme (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)
Functionalized cork-polymer composites (CPC) by reactive extrusion using suberin and lignin from cork as coupling agents
High density polyethylene (HDPE) and cork powder were compounded in a co-rotating twin-screw
extruder to obtain cork-polymer composites (CPC) with improved properties. Benzoyl peroxide (BPO)
was used as initiator agent, and suberin or lignin isolated from cork enhanced filler-matrix bonding
and promoted mechanical reinforcement with environmental benefits. The novel composites were characterised
in terms of dimensional stability, evolution of morphology, thermal and mechanical properties
and their performance was compared with that of composites containing polyethylene-grafted maleic
anhydride (PE-g-MA) as coupling agent. As expected, composites with coupling agent present higher
mechanical properties, lower water uptake and thickness swelling variation. Suberin acts as plasticizer
with antioxidant benefits, while lignin works as a coupling agent, improving tensile modulus and
maximum strength. Increasing lignin content does not improve the mechanical properties but improves
thermal stability.The work was performed within the project of Corticeira Amorim S.G.P.S. on the development of new products based in/with cork. The authors gratefully acknowledge the financial support, through the COMPETE/QREN/EU funding program in the project with acronym NovelComp (QREN FCOMP-01-0202-FEDER-003107). The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) and POPH/FSE for the doctoral Grants to E.M.F. (SFRH/BD/71561/2010) and I.M.A. (SFRH/BD/42273/2007)
Inhibition of HMG-CoA reductase activity and cholesterol permeation through Caco-2 cells by caffeoylquinic acids from Vernonia condensata leaves
AbstractThe aim of this study was to provide scientific knowledge to support the use of Vernonia condensata Baker, Asteraceae, beverages for their alleged hypocholesterolemic properties by testing their action as HMG-CoA reductase inhibitors and their capacity to lower dietary cholesterol permeation. Chlorogenic acid, and other caffeoylquinic acids derivatives were identified as the main components of these beverages by LC–MS/MS. No changes in the composition were notice after the in vitro gastrointestinal digestion and no toxicity against Caco-2 and HepG2 cell lines was detected. Cholesterol permeation through Caco-2 monolayers was reduced in 37% in the presence of these herbal teas, and the caffeoylquinic acids permeated the monolayers in 30–40% of their initial amount in 6h. HMG-CoA reductase activity was reduced with these beverages, showing an IC50 of 217μgml−1. It was concluded that caffeoylquinic acids, the major components, justified 98% of the enzyme inhibition measured
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