152 research outputs found
Comment on Baltic provenance of top-Famennian siliciclastic material of the northern Rhenish Massif, Rhenohercynian zone of the Variscan orogen, by Koltonik et al., International Journal of Earth Sciences (2018) 107:2645–2669
Koltonik et al. (Int J Earth Sci 107:2645–2669, 2018) evidence that the Late Devonian siliciclastic rocks from the Rheno-
Hercynian Zone, in Germany, derived from Baltica and Scandinavian Caledonides. This finding together with what is known
about the provenance of the Pulo do Lobo and South Portuguese zones, in Portugal and Spain, reinforces the probability
that Late Devonian basins may have been sourced from distinct terranes placed along the Variscan suture. Our comment
intends to underline changes in the provenance of the Late Devonian basins along the active margin of Laurussia, and also,
to improve the correlation model for the Variscan tectonic units from SW Iberia and Germany
Early Carboniferous synorogenic basins evolution of the Ossa-Morena and
The stratigraphic record of the Early Carboniferous in Iberia reveals that synorogenic deposition was
important and occurred simultaneously in basins influenced by extension and contraction with gravitational instability.
In NW Iberia (Galicia – Trás-os-Montes Zone) contraction was dominant and the deposition took place in a forebulge
outwards from the nappe stacking front. Here, synorogenic deposits were strongly affected by folding and thrusting as
they were imbricated and incorporated in the allochthonous pile. In a different way, in SW Iberia (Ossa-Morena Zone)
synorogenic deposition was influenced by extension and happened simultaneously with the onset of significant
magmatism
Preliminary studies on enzymatic applications in the paper industry
DisponĂvel apenas o abstract
Bacterial nanocellulose membrane as novel substrate for biomimetic structural color materials: Application to lysozyme sensing
The development of optical biosensors based on structural colors generated by short-range ordered colloidal particles is attracting growing interest due to their non-iridescent and non-fading features. In this study, a biomimetic approach using biopolymers for the various steps of sensor construction is presented. Bacterial nanocellulose (BNC) has many foreseen applications in biomedical engineering because of its biocompatibility, good mechanical strength, and large modifiable surface area. Herein, a novel approach is taken by using functionalized BNC as a substrate to build a molecularly imprinted photonic sensing layer. BNC was modified with polydopamine (PDA), which improved the adhesion and mechanical properties of the BNC substrate while providing simultaneously a black background for color saturation. A molecularly imprinted polymer (MIP) also made of PDA was used to create the recognition sites for the biomarker lysozyme. A monodisperse colloidal suspension of silica particles was first synthesized and used as core of the MIP shell, and then the photonic structure was assembled on the PDA-BNC membrane. The biosensor showed a detection limit of about 0.8nmolL1 of lysozyme in spiked human serum and demonstrated to be selective against cystatin C. These properties, combined with biocompatible, eco-friendly, and low-cost materials, offer a sustainable sensing platform with great potential for healthcare applications.info:eu-repo/semantics/publishedVersio
Evidence formulti-cycle sedimentation and provenance constraints from
Laser ablation ICP-MS U–Pb analyses were conducted on detrital zircons of Triassic sandstone and conglomerate
from the Lusitanian basin in order to: i) document the age spectra of detrital zircon; ii) compare U–Pb detrital
zircon ages with previous published data obtained from Upper Carboniferous, Ordovician, Cambrian and Ediacaran
sedimentary rocks of the pre-Mesozoic basement of western Iberia; iii) discuss potential sources; and iv) test the
hypothesis of sedimentary recycling. U–Pb dating of zircons established a maximum depositional age for this
deposit as Permian (ca. 296Ma),which is about sixty million years older compared to the fossil content recognized
in previous studies (Upper Triassic). The distribution of detrital zircon ages obtained points to common source
areas: the Ossa–Morena and Central Iberian zones that outcrop in and close to the Porto–Tomar fault zone. The
high degree of immaturity and evidence of little transport of the Triassic sediment suggests that granite may
constitute primary crystalline sources. The Carboniferous age of ca. 330 Ma for the best estimate of crystallization
for a granite pebble in a Triassic conglomerate and the Permian–Carboniferous ages (ca. 315Ma) found in detrital
zircons provide evidence of the denudation of Variscan and Cimmerian granites during the infilling of continental
rift basins in western Iberia. The zircon age spectra found in Triassic strata are also the result of recycling from the
Upper Carboniferous Buçaco basin,which probably acted as an intermediate sediment repository.U–Pb data in this
study suggest that the detritus from the Triassic sandstone and conglomerate of the Lusitanian basin is derived
fromlocal source areas with features typical of Gondwana,with no sediment from external sources from Laurussia
or southwestern Iberia
Sedimentary record of the amalgamation and break-up of Pangaea: U-Pb detrital zircon geochronology and provenance of Carboniferous-Triassic siliciclastic rocks (SW Iberia)
In SW Iberia there is a basal unconformity where Triassic sandstones overlie previously deformed
Carboniferous turbidites. This important stratigraphic boundary records the transition from the
final stages of Pangaea’s amalgamation to the initial stages of break-up. U-Pb dating of detrital
zircon from Carboniferous greywackes of the South Portuguese Zone and Triassic sandstones of
the Algarve and Alentejo basins was carried out to conduct a study of sedimentary provenance.
The radiometric ages obtained by LA-ICP-MS show that most of the samples have common
age spectra which are typical of North Gondwana sources: Archean and Paleoproterozoic ages
characteristic of the West African craton, Neoproterozoic ages associated with Cadomian and
Pan-African orogenies, and Cambrian ages related to the intra-continental rifting of North
Gondwana. The only exception is a Visean immature greywacke that was probably derived
from Devonian magmatic arcs related to the Variscan orogeny. Very rare pre-Devonian zircons
indicate faint contributions from recycled sediments. In contrast the Serpukhovian to Moscovian
greywackes are derived from felsic mature source rocks and include Proterozoic and Paleozoic
detrital zircons suggesting recycling of an old basement. They also include Ordovician and
Silurian detrital zircons, the ages of which have no correspondence in North Gondwana, and
thus indicate an external source (Laurussia?). U-Pb ages younger than Ordovician are significant
in the Triassic sandstone of the Alentejo basin and resemble the zircon populations of the
Serpukhovian to Moscovian greywackes from the South Portuguese Zone. U-Pb ages younger
than Neoproterozoic are poorly represented in the zircon population of the Triassic sandstone
from the Algarve basin, which rests unconformably upon Moscovian turbidites, pointing to
Upper Devonian quartzites of the South Portuguese Zone as probable sources, since they are
dominated by Precambrian detrital zircons. These differences occurring in the Triassic basins
suggest that detrital zircon populations could be derived from two independent sources and
paleo-drainage systems due to complex crustal-block extension architecture
Mechanical fatigue performance of PCL-chondroprogenitor constructs after cell culture under bioreactor mechanical stimulus
[EN] In tissue engineering of cartilage, polymeric scaffolds are implanted in the damaged tissue and subjected to repeated compression loading cycles. The possibility of failure due to mechanical fatigue has not been properly addressed in these scaffolds. Nevertheless, the macroporous scaffold is susceptible to failure after repeated loading-unloading cycles. This is related to inherent discontinuities in the material due to the micropore structure of the macro-pore walls that act as stress concentration points. In this work, chondrogenic precursor cells have been seeded in poly-epsilon-caprolactone (PCL) scaffolds with fibrin and some were submitted to free swelling culture and others to cyclic loading in a bioreactor. After cell culture, all the samples were analyzed for fatigue behavior under repeated loading-unloading cycles. Moreover, some components of the extracellular matrix (ECM) were identified. No differences were observed between samples undergoing free swelling or bioreactor loading conditions, neither respect to matrix components nor to mechanical performance to fatigue. The ECM did not achieve the desired preponderance of collagen type II over collagen type I which is considered the main characteristic of hyaline cartilage ECM. However, prediction in PCL with ECM constructs was possible up to 600 cycles, an enhanced performance when compared to previous works. PCL after cell culture presents an improved fatigue resistance, despite the fact that the measured elastic modulus at the first cycle was similar to PCL with poly(vinyl alcohol) samples. This finding suggests that fatigue analysis in tissue engineering constructs can provide additional information missed with traditional mechanical measurements.Contract grant sponsors: FEDER Funds; Programa Operacional Regional do Norte (ON.2 - O Novo Norte); Quadro de Referencia Estrategico Nacional (QREN); Fundo Europeu de Desenvolvimento Regional (FEDER); VI National R&D&i Plan 2008-2011; Iniciativa Ingenio 2010; Consolider Program; CIBER Actions; Instituto de Salud Carlos III with assistance from the European Regional Development FundPanadero, JA.; Sencadas, V.; Silva, SCM.; Ribeiro, C.; Correia, V.; Gama, FM.; GĂłmez Ribelles, JL.... (2016). Mechanical fatigue performance of PCL-chondroprogenitor constructs after cell culture under bioreactor mechanical stimulus. Journal of Biomedical Materials Research Part B Applied Biomaterials. 104(2):330-338. https://doi.org/10.1002/jbm.b.33386330338104
Bacterial cellulose production through hydrolysates produced with cellulosic residues
In the paper industry, significant fraction of fibers that cannot be reutilized
are wasted by the paper companies, which raise economic and
environmental concerns. An increasing demand of bacterial cellulose
(BC) has been noticed in the last years. In order to ally the recycling
of lignocellulosic residues and the production of bacterial cellulose,
Recycled paper sludge (RPS) and rejected fibers (EUR) were
enzymatically hydrolyzed to obtain sugar hydrolysates, which were
used for BC production. Exploratory assay (different strains and
nitrogen sources) was performed with RPS and EUR hydrolysates.
RPS hydrolysate showed to be an interesting an alternative carbon
source for G. hansenii (5 g/L of BC) and EUR hydrolysate showed
potential as carbon source for G. xylinum (4-5 g/L of BC). Overall, the
results suggest that RPS and EUR residues have potential to be
alternatives of carbon source for BC production, after a further
optimization of the BC production and the enzymatic hydrolysis.The authors wish to thank Daniel Gomes for technical help. This work received financial support from FCT via project
ID520405.ID1956.info:eu-repo/semantics/publishedVersio
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