Development of weft-knitted and braided polypropylene stents for arterial implant

Textile biomedical materials have been used for various applications contributing considerably in improving quality of life. The current study aims at improving polypropylene fibre stents which may replace metallic ones. In order to produce the stents, weft-knitting and braiding technologies were used. In the braiding technique, by varying the takeup ratio (using gears with the appropriate number of teeth in the braiding machine), it was possible to manufacture regular braids with angles of 65 ° , 70 ° and 75 ° in order to obtain different covers. In the knitting technique, a circular machine was used and the tightness of the structure was adjusted by varying the loop length and thus the fabric loop density, resulting in variations of the sample diameter. The knitting machine had negative feed, and so loop length variations were achieved by varying the yarn input tension, the stitch cam settings and the fabric take-down tension. The samples were heat set. Yarns were contracted by setting at 130 ° C and 140 ° C, and this led to increasing the loop density and the flexural rigidity of the samples. A high cover of the samples resulted in a greater stiffness of the structures. The stents were evaluated by undertaking the tests required for arterial support: rigidity to radial compression, resistance to tensile forces and bending rigidity. The best results were obtained with braided structures. Future work may concentrate in improving the stent design and using new biocompatible fibres.The authors wish to thank the European Commission for awarding research funds under the EU Asia-link programme and the University of Minho (Portugal) and Donghua University (People's Republic of China) for providing research facilities

Conformational analysis of 2,2-difluoroethylamine hydrochloride: double gauche effect

The gauche effect in fluorinated alkylammonium salts is well known and attributed either to an intramolecular hydrogen bond or to an electrostatic attraction between the positively charged nitrogen and the vicinal electronegative fluorine atom. This work reports the effect of adding a fluorine atom in 2-fluoroethylamine hydrochloride on the conformational isomerism of the resulting 2,2-difluoroethylamine chloride (2). The analysis was carried out using NMR coupling constants in D2O solution, in order to mimic the equilibrium conditions in a physiological medium, in the gas phase and in implicit water through theoretical calculations. Despite the presence of sigma(CH)->sigma(*)(CF) and sigma(CH)->sigma(*)(CN) interactions, which usually rule the hyperconjugative gauche effect in 1,2-disubstituted ethanes, the most important forces leading to the double gauche effect (+NH3 in the gauche relationship with both fluorine atoms) in 2 are the Lewis-type ones. Particularly, electrostatic interactions are operative even in water solution, where they should be significantly attenuated, whereas hyperconjugation and hydrogen bond have secondary importance10877882CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçãosem informação2012/03933-5; 2011/11098-6; 2011/01170-

Few-layer graphene aqueous suspensions for polyurethane composite coatings

Graphite nanoplates (GnP) have recently attracted attention as an economically viable alternative for the development of functional and structural nanocomposites. The incorporation of GnP into waterborne polyurethane (WPU) with loadings from 0.1 to 10 wt.% was studied. The mechanical properties of the composite films were assessed by tensile testing showing an increase of the Young’s modulus up to 48%. The electrical conductivity increased by 9 orders of magnitude and the water vapor permeability of the composite films decreased 57% for composites containing 5.0 wt.% of GnP.The authors acknowledge FCT, project PEst-C/CTM/LA0025/2015 and PhD grant SFRH/BD/87214/2012.info:eu-repo/semantics/publishedVersio

Determination of 2,4,6-trichloroanisole by cyclic voltammetry

The electrochemical reduction of 2,4,6-trichloroanisole (TCA), a chlorinated arene with electron-donating substituents, was evaluated by cyclic voltammetry (CV). TCA is a major concern for the winery industry since it is related with “cork taint”, a wine defect. The results obtained showed that CV could be used to detect and quantify TCA in standard solutions. Linear relationships could be set between the current amplitude and TCA concentrations (R>0.990) with detection and quantification limits of 0.08 and 0.26 ppm. Although, these preliminary limits are higher than the human sensory threshold (5 ppt in wine), the simplicity of the methodology confers this study a possible role in the development of more efficient and less expensive process for TCA detection in the industry.This work was partially supported by project PEst-C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundacao para a Ciencia e a Tecnologia

In vitro fermentation and prebiotic potential of selected extracts from seaweeds and mushrooms

Extracts with prebiotic activity or bioactive compounds from natural sources such as seaweeds or mushrooms, combining a broad spectrum of biological properties, may offer great potential for their use as functional ingredients enabling intestinal microbiota modulation. In this context, selected enzymatic extracts from Sargassum muticum, Osmundea pinnatifida and Pholiota nameko were evaluated in vitro. Faecal fermentations were conducted anaerobically under controlled temperature and pH over 24 h. Enzymatic extracts of Ph. nameko and of O. pinnatifida at 1% (w/v), lead to increases in Bifidobacterium spp. after 6 h of fermentation in comparison to negative control, suggesting a stimulatory effect. No significant changes over 24 h were observed of Lactobacillus spp. In particular, the Ph. nameko extract obtained with Flavourzyme not only stimulated growth and/or activity of Bifidobacterium spp. but also led to a decrease of Clostridium histolyticum group upon 24 h, thus potentially benefiting colonic health. Higher percentages of this extract (2 and 3%) impaired a C. histolyticum reduction confirming this selective action and prebiotic potential. Differences in short chain fatty acids (SCFA) and lactic acid production between the four extracts may indicate a potential relationship between their physico-chemical properties, which differ in composition and structures, and modulation of gut bacterial species

Li+ Influx and Binding, and Li+/Mg2+ Competition in Bovine Chromaffin Cell Suspensions as Studied by 7Li NMR and Fluorescence Spectroscopy

Li+ influx by bovine chromaffin cells, obtained from bovine adrenal medulla, was studied in intact cell suspensions using 7Li NMR spectroscopy with the shift reagent [Tm(HDOTP)]4-. The influx rate constants, ki, were determined in the absence and in the presence of two Na+ membrane transport inhibitors. The values obtained indicate that both voltage sensitive Na+ channels and (Na+/K+)-ATPase play an important role in Li+ uptake by these cells. 7Li NMR T1 and T2 relaxation times for intracellular Li+ in bovine chromaffin cells provided a T1/T2 ratio of 305, showing that Li+ is highly, immobilized due to strong binding to intracellular structures. Using fluorescence spectroscopy and the Mg2+ fluorescent probe, furaptra, the free intracellular Mg2+ concentration in the bovine chromaffin cells incubated with 15 mM LiCl was found to increase by about mM after the intracellular Li+ concentration reached a steady state. Therefore, once inside the cell, Li+ is able to displace Mg2+ from its binding sites

Systematic Observation of Corner Kick Strategies in Portuguese Football Players

Set pieces are important for the success of football teams, with the corner kick being one of the most game defining events. The aim of this research was twofold: (1) to analyze the corner kicks of a senior football amateur team, and (2) to compare the corner kicks of successful and unsuccessful teams (of the 2020/21 sporting season). In total, 500 corners were observed using a bespoke notational analysis tool, using a specific observational instrument tool (8 criteria; 25 categories). Out of the 500 corner kicks, 6% resulted in a goal. A greater number of direct corners using inswing trajectories were performed (n = 54%). Corners were delivered to central and front post areas most frequently (n = 79%). Five attackers were most predominantly used for offensive corners (n = 58%), but defenders won the ball more frequently (n = 44%). Attempts at goal occurred following a corner most commonly from outside of the box (n = 7%). Goals were scored most frequently with the foot (n = 16%) and head (n = 15%). Successful teams are more effective at reaching the attackers and score more goals directly from corners. Unsuccessful teams deliver more corner kicks out of play, the first touch is more frequently from the opposition defenders, and fewe goals are scored from corner kicks. The study provides an insight into the determining factors and patterns that influence corner kicks and success in football matches. This information should be used by coaches to prepare teams for both offensive and defensive corner kicks to increase team success and match outcomes.info:eu-repo/semantics/publishedVersio