Towards the development of poly (phenylene sulphide) based nanocomposites with enhanced mechanical, electrical and tribological properties

Novel poly(phenylene sulphide) (PPS) nanocomposites reinforced with an aminated derivative (PPS-NH2) covalently attached to acid-treated single-walled carbon nanotubes (SWCNTs) were prepared via simple melt-blending technique. Their morphology, viscoelastic behaviour, electrical conductivity, mechanical and tribological properties were investigated. Scanning electron microscopy revealed that the grafting process was effective in uniformly dispersing the SWCNTs within the matrix. The storage and loss moduli as a function of frequency increased with the SWCNT content, tending to a plateau in the low-frequency regime. The electrical conductivity of the nanocomposites was considerably enhanced in the range 0.1?0.5 wt% SWCNTs; electrical and rheological percolation thresholds occurred at similar nanotube concentrations. Mechanical tests demonstrated that with only 1.0 wt% SWCNTs the Young's modulus and tensile strength of the matrix improved by 51 and 37%, respectively, without decrement in toughness, ascribed to a very efficient load transfer. A moderate decrease in the friction coefficient and a 75% reduction in wear rate were found for the abovementioned nanotube loading, indicating that PPS-NH2-g-SWCNTs are good tribological additives for thermoplastic polymers. Based on the promising results obtained in this work, it is expected that these nanofillers will be used to develop high-performance thermoplastic/CNT nanocomposites for structural applications

Travel Tales of a Worldwide Weed: Genomic Signatures of Plantago major L. Reveal Distinct Genotypic Groups With Links to Colonial Trade Routes

Retracing pathways of historical species introductions is fundamental to understanding the factors involved in the successful colonization and spread, centuries after a species’ establishment in an introduced range. Numerous plants have been introduced to regions outside their native ranges both intentionally and accidentally by European voyagers and early colonists making transoceanic journeys; however, records are scarce to document this. We use genotyping-by-sequencing and genotype-likelihood methods on the selfing, global weed, Plantago major, collected from 50 populations worldwide to investigate how patterns of genomic diversity are distributed among populations of this global weed. Although genomic differentiation among populations is found to be low, we identify six unique genotype groups showing very little sign of admixture and low degree of outcrossing among them. We show that genotype groups are latitudinally restricted, and that more than one successful genotype colonized and spread into the introduced ranges. With the exception of New Zealand, only one genotype group is present in the Southern Hemisphere. Three of the most prevalent genotypes present in the native Eurasian range gave rise to introduced populations in the Americas, Africa, Australia, and New Zealand, which could lend support to the hypothesis that P. major was unknowlingly dispersed by early European colonists. Dispersal of multiple successful genotypes is a likely reason for success. Genomic signatures and phylogeographic methods can provide new perspectives on the drivers behind the historic introductions and the successful colonization of introduced species, contributing to our understanding of the role of genomic variation for successful establishment of introduced taxa.publishedVersio

Travel Tales of a Worldwide Weed: Genomic Signatures of Plantago major L. Reveal Distinct Genotypic Groups With Links to Colonial Trade Routes

Retracing pathways of historical species introductions is fundamental to understanding the factors involved in the successful colonization and spread, centuries after a species’ establishment in an introduced range. Numerous plants have been introduced to regions outside their native ranges both intentionally and accidentally by European voyagers and early colonists making transoceanic journeys; however, records are scarce to document this. We use genotyping-by-sequencing and genotype-likelihood methods on the selfing, global weed, Plantago major, collected from 50 populations worldwide to investigate how patterns of genomic diversity are distributed among populations of this global weed. Although genomic differentiation among populations is found to be low, we identify six unique genotype groups showing very little sign of admixture and low degree of outcrossing among them. We show that genotype groups are latitudinally restricted, and that more than one successful genotype colonized and spread into the introduced ranges. With the exception of New Zealand, only one genotype group is present in the Southern Hemisphere. Three of the most prevalent genotypes present in the native Eurasian range gave rise to introduced populations in the Americas, Africa, Australia, and New Zealand, which could lend support to the hypothesis that P. major was unknowlingly dispersed by early European colonists. Dispersal of multiple successful genotypes is a likely reason for success. Genomic signatures and phylogeographic methods can provide new perspectives on the drivers behind the historic introductions and the successful colonization of introduced species, contributing to our understanding of the role of genomic variation for successful establishment of introduced taxa.info:eu-repo/semantics/publishedVersio

The high-performance liquid chromatography/multistageelectrospray mass spectrometric investigation and extractionoptimization of beech (Fagus sylvatica L.) bark polyphenols

The aim of the present work was the high-performance liquid chromatographic separation and multi-stage mass spectrometric characterization of the polyphenolic compounds of beech bark, as well as theextraction optimization of the identified compounds. Beech is a common and widely used material inthe wood industry, yet its bark is regarded as a by-product. Using appropriate extraction methods thesecompounds could be extracted and utilized in the future.Different extraction methods (stirring, sonication, microwave assisted extraction) using different sol-vents (water, methanol:water 80:20 v/v, ethanol:water 80:20 v/v) and time/temperature schedules havebeen compared basing on total phenol contents (Folin–Ciocâlteu) and MRM peak areas of the identifiedcompounds to investigate optimum extraction efficiency.Altogether 37 compounds, including (+)-catechin, (−)-epicatechin, quercetin-O-hexoside, taxifolin-O-hexosides (3), taxifolin-O-pentosides (4), B-type (6) and C-type (6) procyanidins, syringic acid-and coumaric acid-di-O-glycosides, coniferyl alcohol- and sinapyl alcohol-glycosides, as well as otherunknown compounds with defined [M−H]−m/z values and MS/MS spectra have been tentatively iden-tified.The choice of the method, solvent system and time/temperature parameters favors the extraction ofdifferent types of compounds. Pure water can extract compounds as efficiently as mixtures containingorganic solvents under high-pressure and high temperature conditions. This supports the implementa-tion of green extraction methods in the future. Extraction times that are too long and high temperaturescan result in the decrease of the concentrations.Future investigations will focus on the evaluation of the antioxidant capacity and utilization possibili-ties of the prepared extract

The impact of policy measures and coaching on the availability and accessibility of early child care: a longitudinal study

We conducted a study of changes in the availability, accessibility and enrolment of children from low-income, single-parent and ethnic minority families in early child care centres. The study was carried out in Brussels which offers unique possibilities to study accessibility in a context in which quality and costs are controlled across centres. A survey on access policies in 89 day care centres, and on 150 mothers regarding their search process, was complemented by two focus groups attended by centre directors. The results were compared with data from a similar study we conducted in 2005. The results show that while inequality in availability has remained, centre directors' awareness of social priority criteria has changed, resulting in a significant increase in the enrolment of children from single-parent and ethnic minority families, and – to a lesser extent – an increase in the enrolment of children from low-income families. The results support the hypothesis that policy measures, combined with support, can influence inequalities in enrolment rates