843 research outputs found
Rapid colour changes in Euglena sanguinea (Euglenophyceae) caused by internal lipid globule migration
The accumulation of red pigments under chronic stress is a response observed in most
groups of oxygenic photoautotrophs. It is thought that the red pigments in the cell shield
the chlorophyll located underneath from the light. Among these red pigments, the
accumulation of carotenoids is one of the most frequent cases. However, the synthesis
or degradation of carotenoids is a slow process and this response is usually only
observed when the stress is maintained over a period of time. In the Euglenophyte
Euglena sanguinea, this is due to the accumulation of a large amount of free and
esterified astaxanthin (representing 80% of the carotenoid pool). While reddening is a
slow and sometimes irreversible process in other phototrophs, reducing the efficiency of
light harvesting by chlorophyll, in E. sanguinea it is highly dynamic, capable of shifting
from red to green (and vice-versa) in 10-20 min. This change is not due to de novo
carotenogenesis, but to the relocation of cytoplasmic lipid globules where astaxanthin
accumulates. Thus, red globules migrate from the centre of the cell to peripheral
locations when photoprotection is demanded. This protective system seems to be so
efficient that other classical mechanisms are not operative in this species. For example,
despite the presence and operation of the diadino-diatoxanthin cycle, nonphotochemical
quenching (NPQ) is almost undetectable. Since E. sanguinea forms
extensive floating colonies, reddening can be observed at much greater scale than at a
cellular level, the mechanism described here being one of the fastest and most dramatic
colour changes attributable to photosynthetic organisms at cell and landscape level. In
sum, these data indicate an extremely dynamic and efficient photoprotective mechanism
based on organelle migration more than on carotenoid biosynthesis that prevents excess
light absorption by chlorophylls reducing the need for other protective processes related
to energy dissipation.This work was supported by the Basque Government [UPV/EHU-GV IT-1018-16] [UPV/EHU PPG17/67 – GV IT-1040-16], and by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Research and Development Foundation (FEDER) through (i) [CTM2014-53902-C2-2-P] national grant and (ii) a “Juan de la Cierva-Incorporación” postdoctoral grant [IJCI-2014-22489] to BFM
A new LED-LED portable CO2 gas sensor based on an interchangeable membrane system for industrial applications
A new system for CO2 measurement (0-100%) by based on a paired emitter-detector diode arrangement as a colorimetric detection system is described. Two different configurations were tested: configuration 1 (an opposite side configuration) where a secondary inner-filter effect accounts for CO2 sensitivity. This configuration involves the absorption of the phosphorescence emitted from a CO2-insensitive luminophore by an acid-base indicator and configuration 2 wherein the membrane containing the luminophore is removed, simplifying the sensing membrane that now only contains the acid-base indicator. In addition, two different instrumental configurations have been studied, using a paired emitter-detector diode system, consisting of two LEDs wherein one is used as the light source (emitter) and the other is used in reverse bias mode as the light detector. The first configuration uses a green LED as emitter and a red LED as detector, whereas in the second case two identical red LEDs are used as emitter and detector. The system was characterised in terms of sensitivity, dynamic response, reproducibility, stability and temperature influence. We found that configuration 2 presented a better CO2 response in terms of sensitivity
Environmentally friendly processing of Laminaria ochroleuca for soft food applications with bioactive properties
Dehydrated Laminaria ochroleuca was processed by autohydrolysis with compressed hot water to extract bioactive compounds.
Both the whole algae and individual fractions obtained (solid residue and liquor) were characterised to assess its functional
properties for future innovative food applications. Purée-like systems were developed by combining ultrasonic and thermal
technologies to maximise the antioxidant capacity and were evaluated by determining colour, texture, rheology, syneresis and
the presence of bioactive compounds. Overall, the obtained results indicated that L. ochroleuca is a valuable resource that can be
used as a whole or taking advantage of its bioactive fractions, in a concept of circular economy and sustainabilityinfo:eu-repo/semantics/publishedVersio
Milling angular references and process parameters on fiber reinforced plastics
[EN] Machining of fiber-reinforced composites produces delamination in the workpiece. In bidirectional long fiber fabric reinforced composites, delamination depends on different parameters. In this work, two parameters are studied: fiber orientation angle respect to machining direction and the distance of the warp yarn from the trimmed edge until the next dip below the crossing fill. This work defines angles relating fiber orientation with cutting and feed movements and their relations in a robust way, being applied to edge trimming and grooving operations. On the other hand, for Type II delamination, three different kinds of delamination (constant, uniform pattern variation and random) are studied taking into account fiber orientation, wick size and the fiber orientation angle respect to machining direction.Navarro-Mas, M.; Meseguer, M.; Ordeig Fernández, IN.; Lluch-Cerezo, J. (2021). Milling angular references and process parameters on fiber reinforced plastics. IOP Conference Series Materials Science and Engineering. 1193:1-10. https://doi.org/10.1088/1757-899x/1193/1/012004110119
- …