5,729 research outputs found

    On the use of thermal properties for characterizing dimension stones from Portugal

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    It has been usual practice to measure physical and mechanical properties of dimension stones; however, the same is not true for thermal properties, such as thermal conductivity, thermal diffusivity, specific heat capacity, and heat production which are particularly important when processes related with heating and cooling of buildings must be considered. Thermal conductivity, thermal diffusivity, and specific heat capacity are related with the way thermal energy is transmitted and accumulated in stones; heat production is related with the amount of radioactive elements on the rocks. Several rock samples from several quarries were collected in Mainland Portugal for measuring their thermal conductivities, thermal diffusivities, specific heat capacities, and heat productions. The rock set consists of granites, limestones, and marbles used in architecture and civil engineering. The results of the study indicate that the collected granites have thermal conductivities, thermal diffusivities, and specific heat capacity that vary from 2.98 ± 0.09 to 3.24 ± 0.21 W/m.K, 1.32 ± 0.03 to 1.55 ± 0.12 (x10-6) m2/s, 2.10 ± 0.04 to 2.26 ± 0.04 J/m3.K, respectively; the collected limestones have thermal conductivities, thermal diffusivities, and specific heat capacity that vary from 2.77 ± 0.02 to 3.07 ± 0.03 W/m.K, 1.26 ± 0.01 to 1.42 ± 0.03 (x10-6) m2/s, 2.16 ± 0.05 to 2.32 ± 0.04 J/m3.K, respectively. The average thermal conductivity, thermal diffusivity, and specific heat capacity for marbles is 2.90 ± 0.03 W/m.K, 1.31 ± 0.03 (x10-6) m2/s, 2.22 ± 0.07 J/m3.K. The average heat production per unit volume for the granites is 2.75 (0.25) mW/m3

    Conjugated linoleic acid reduces permeability and fluidity of adipose plasma membranes from obese Zucker rats

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    NOTICE: this is the author’s version of a work that was accepted for publication in Biochemical and Biophysical Research Communications. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Biochemical and Biophysical Research Communications. July 2010; 398 (2): 199-204.Conjugated linoleic acid (CLA) is a dietary fatty acid frequently used as a body fat reducing agent whose effects upon cell membranes and cellular function remain unknown. Obese Zucker rats were fed atherogenic diets containing saturated fats of vegetable or animal origin with or without 1% CLA, as a mixture of cis(c)9,trans(t)11 and t10,c12 isomers. Plasma membrane vesicles obtained from visceral adi- pose tissue were used to assess the effectiveness of dietary fat and CLA membrane incorporation and its outcome on fluidity and permeability to water and glycerol. A significant decrease in adipose membrane fluidity was correlated with the changes observed in permeability, which seem to be caused by the incor- poration of the t10,c12 CLA isomer into membrane phospholipids. These results indicate that CLA supple- mentation in obese Zucker rats fed saturated and cholesterol rich diets reduces the fluidity and permeability of adipose membranes, therefore not supporting CLA as a body fat reducing agent through membrane fluidification in obese fat consumers

    Hyperbolic models to represent the effect of mechanical damage and abrasion on the short-term tensile response of a geocomposite

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    The objective of this study was to analyse the short-term tensile response of a geocomposite (a geotextile and a geogrid overlapped) and apply hyperbolic models to describe its load-strain tensile curves. Data from specimens submitted to mechanical damage, abrasion, and mechanical damaged followed by abrasion were analysed. Reduction factors were proposed by comparing data from damaged specimens with those from undamaged specimens. The experimental results were compared with those fitted by the constitutive models to validate the model. The constitutive models demonstrated good fitting capacity. For any mechanical condition, the model parameters could be estimated by relating the experimental tensile properties of the geocomposite with adjustment coefficients, which allowed for describing the tensile load-strain curves with good accuracy. The reduction factors for the specimens subjected to mechanical damage followed by abrasion were lower than the values which would be obtained if the damages were considered individually.This work was financially supported by: FCT (Fundacao para a Ciencia e a Tecnologia Portugal) through the doctoral scholarship 2020.07874.BD (1st author) and projects UIDB/04450/2020 (RISCO), UIDB/00481/2020 and UIDP/00481/2020; PRR (Portuguese Resilience Plan through European Union -NextGenerationEU), through project TRANSFORM; Centro2020 (Centro Portugal Regional Operational Programme) through project CENTRO-01-0145-FEDER-022083.info:eu-repo/semantics/publishedVersio

    The Effect of Auriculotherapy on Situational Anxiety Trigged by Examinations: A Randomized Pilot Trial.

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    Auriculotherapy may activate the parasympathetic nerve system and reduce anxiety levels. Short-term auriculotherapy's effects and safety on university students' anxiety levels was assessed prior to exams. Methods A randomized, controlled pilot trial was conducted. The day before the exam, university students were randomly allocated to the auriculotherapy group (AA, n = 13) or the waiting-list group (WG, n = 13). Baseline measures were taken 4 weeks before the exam at Time point (TP 0); at 7.30 a.m. on the day before the exam (TP I); at 11 a.m. before auriculotherapy (TP II); 30 min after AA (TP III); and at 7.30 a.m. before the exam (TP IV). The outcomes were the State-Trait-Anxiety Inventory (STAI); quality of night-sleep, Visual Analogue scale (VAS) for anxiety, and salivary cortisol. Adverse events were also recorded.Results A total of 26 students participated in this study and became more anxious as assessed by STAI in TPII (p = 0.002) and TPIV (p = 0.000) than TP0. AA reduced the STAI in TPIII (p = 0.045) and PIV (p = 0.001) and the VAS (p = 0.012) in TPIV. Cortisol was reduced in TPIII (p = 0.004), and the AA slept better (p = 0.014) at TPIV. Discomfort at the auricular site was reported in only one AA participant.Conclusions Auriculotherapy appeared safe and effective in reducing anxiety levels before university exams

    Effect of dietary conjugated linoleic acid isomers on water and glycerol permeability of kidney membranes

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    NOTICE: this is the author’s version of a work that was accepted for publication in Biochemical and Biophysical Research Communications. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Biochemical and Biophysical Research Communications. May 2009; 383(1): 108-112.Conjugated linoleic acid (CLA) refers to a group of positional and geometrical isomers of linoleic acid in which the double bonds are conjugated. Dietary CLA has been associated with various health benefits although details of its molecular mode of action remain elusive. The effect of CLA supplemented to palm oil-based diets in Wistar rats, as a mixture of both or isolated c9,t11 and t10,c12 isomers, was examined on water and glycerol membrane permeability of kidney proximal tubule. Although water permeability was unaltered, an increase in glycerol permeability was obtained for the group supplemented with CLA mixture, even though the activation energy for glycerol permeation remained high. This effect was correlated with an increased CLA isomeric membrane incorporation for the same dietary group. These results suggest that diet supplementation with CLA mixture, in contrast to its individual isomers, may enhance membrane fluidity subsequently raising kidney glycerol reabsorption

    In-depth phenolic characterization of iron gall inks by deconstructing representative Iberian recipes

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    UIDB/50006/2020 PTDC / QUI-OUT / 29925/2017Iron-gall ink is one of the most important inks in the history of western civilization. The deep black colour results from Fe3+ complexes with phenolic compounds available in gall extracts. Unfortunately, it induces the degradation of both ink and support over time. Furthermore, our knowledge of these complex molecular structures is limited. This work aims to overcome this gap, revealing essential information about the complex structures of these pigments and dyes that will create a breakthrough in the next generation of conservation treatments. It presents the first in-depth phenolic identification and quantification of extracts and inks, prepared with and without gum arabic (an essential additive in medieval recipes). Five representative Iberian recipes were selected and prepared. Their phenolic profile was analysed by HPLC–DAD and HPLC–ESI–MS, which revealed that the phenolic compounds present in higher concentration, in the gall extracts, are pentagalloylglucose and hexagalloylglucose (0.15 ± 0.01–32 ± 3 mg/mL), except for one recipe, in which gallic acid is the main phenolic. The influence of the ingredients is also discussed by deconstructing the recipes: extracts of additives as pomegranate peel and solvents used in the extraction of the galls (vinegar and white wine) were characterized.publishersversionpublishe

    Relevance of genipin networking on rheological, physical, and mechanical properties of starch-based formulations

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    The small amount of proteins in starch-rich food industry byproducts can be an advantage to crosslink with genipin and tailor the performance of biobased films. In this work, genipin was combined with non- purified starch recovered from industrial potato washing slurries and used for films production. Starch recovered from potato washing slurries contained 0.75% protein, 2 times higher than starch directly obtained from potato and 6 times higher than the commercial one. Starch protein-genipin networks were formed with 0.05% and 0.10% genipin, gelatinized at 75 °C and 95 °C in presence of 30% glycerol. Bluish colored films were obtained in all conditions, with the higher surface roughness (Ra, 1.22 μm), stretchability (elongation, 31%), and hydrophobicity (water contact angle, 127°) for 0.10% genipin and starch gelatinized at 75 °C. Therefore, starch-rich byproducts, when combined with genipin, are promising for surpassing the starch-based films hydrophilicity and mechanical fragilities while providing light barrier properties.publishe

    Leptin promotes meiotic progression and developmental capacity of bovine oocytes via cumulus cell-independent and -dependent mechanisms

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    Leptin has been shown to exert positive effects during the maturation of bovine oocytes, influencing blastocyst development, apoptosis, and the transcript levels of developmentally important genes. The present study was conducted to characterize further the mechanisms of leptin action on oocytes and the role of cumulus cells (CCs) in this context. In the first series of experiments, cumulus-oocyte complexes (COCs) were matured in serum-free medium that contained 0, 1 or 10 ng/ml leptin or in medium that was supplemented with 10% (v/v) estrus cow serum (ECS). Leptin concentrations of 1 and 10 ng/ml stimulated the meiotic progression of oocytes. Moreover, TUNEL staining demonstrated that these leptin doses reduced the proportion of apoptotic CCs. In the second series of experiments, COCs or denuded oocytes (DOs) were matured in the presence of 0 or 10 ng/ml leptin. The percentages of COCs and DOs with extruded polar bodies were increased by leptin. In contrast, positive effects of leptin on fertilization rates and blastocyst development were only observed after treatment of COCs but not of DOs. Leptin treatment of COCs consistently enhanced blastocyst development even after parthenogenetic activation of oocytes or after the removal of CCs before fertilization. The proportion of polyspermic oocytes was not affected by leptin treatment or oocyte denudation. In the third series of experiments, COCs were matured in the presence of 0, 1 or 10 ng/ml leptin. The transcript levels of specific genes were determined by reverse transcriptase-quantitative PCR (RT-qPCR) analysis of cumulus cells and single oocytes. Leptin treatment increased the levels of FAS, FASLG, and STAT3 transcripts in oocytes, but did not affect the LEPR, BAX, and BIRC4 mRNA concentrations. In cumulus cells, leptin treatment increased the mRNA levels for LEPR, STAT3, BAX, BIRC4, and FAS, but did not alter FASLG mRNA abundance. In conclusion, leptin differentially regulates gene expression in oocytes and cumulus cells. Moreover, leptin enhances both oocyte maturation and developmental capacity via cumulus cell-independent and -dependent mechanisms
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