577 research outputs found
Conditions for Equality between Lyapunov and Morse Decompositions
Let be a continuous principal bundle whose group is
reductive. A flow of automorphisms of endowed with an ergodic
probability measure on the compact base space induces two decompositions of
the flag bundles associated to . A continuous one given by the finest Morse
decomposition and a measurable one furnished by the Multiplicative Ergodic
Theorem. The second is contained in the first. In this paper we find necessary
and sufficient conditions so that they coincide. The equality between the two
decompositions implies continuity of the Lyapunov spectra under pertubations
leaving unchanged the flow on the base space
Tailoring carbon nanotubes to enhance their efficiency as electron shuttle on the biological removal of acid orange 10 under anaerobic conditions
Anaerobic treatments have been described for the biodegradation of pollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Carbon nanomaterials (CNM) intermediate in, and favor, the electron transfer, accelerating the anaerobic reduction of pollutants, which act as final electron acceptors. In the present work, different carbon nanotubes (CNT) with modified surface chemistry, namely CNT oxidized with HNO3 (CNT_HNO3) and CNT doped with nitrogen in a ball milling process (CNT_N_MB) were prepared using commercial CNT as a starting material. The new CNM were tested as redox mediators (RM), 0.1 g Lâ1, in the biological reduction of the azo dye, Acid Orange 10 (AO10), with an anaerobic granular sludge, over 48 h of reaction. Methane production was also assessed to verify the microorganismâs activity and the CNMâs effect on the methanogenic activity. An improvement in the biological removal of AO10 occurred with all CNM (above 90%), when compared with the control without CNM (only 32.4 ± 0.3%). The best results were obtained with CNT_N_MB, which achieved 98.2 ± 0.1% biological AO10 removal, and an 11-fold reduction rate increase. In order to confer magnetic properties to the CNM, tailored CNT were impregnated with 2% of iron-samples: CNTThis study was supported by the Portuguese Foundation for Science and Technology (FCT) under
the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTEâ01â0145â
FEDERâ000004) funded by the European Regional Development Fund under the scope of Norte2020 â Programa Operacional Regional do Norte, as well as FCT/MCTES trough national funds (PIDDAC) and Base Funding â UIDB/50020/20 of the Associate Laboratory LSREâLCM â funded by national funds rough FCT/MCTES (PIDDAC). Ana Rita Silva holds a Grant from FCT, reference SFRH/BD/131905/2017. SalomĂ©. G.P. Soares acknowledges FCT funding under the Scientific Employment Stimulus â Institutional Call
CEECINST/00049/2018.info:eu-repo/semantics/publishedVersio
Assessment of ciprofloxacin photocatalysis by-products toxicity with Vibrio fischeri
The presence of pharmaceuticals in water has become a large concern due to the potential negative effects on humans and aquatic ecosystems. From these pharmaceuticals, antibiotics represent a serious problem since their overuse and misuse may lead to adverse environmental effects, in particular, toxicity to microflora and fauna and potential negative effects to humans [1].
Photocatalysis has become attractive to promote the degradation of contaminants in the aquatic environment since it allows their rapid and efficient removal from water, transforming them into by-products [2]. In order to evaluate toxicity of these by-products, several bio tests using bacteria (Vibrio fischeri) and algae (Daphnia spp.), among others, have been used [3]. In the present work a
photocatalytic systems using commercial TiO2 and ZnO nanoparticles in suspension was used to degrade ciprofloxacin under UV radiation. Samples were withdraw over time in order to monitor degradation and toxicity. The luminescence of the bacteria Vibrio fischeri was used to test the toxicity of ciprofloxacin intermediate compounds, produced during the photocatalysis process. If a
substance is toxic towards these bacteria, their normal luminescence decreases, as a consequence of a decreasing bacteria viability. Results (Figure 1) indicate that samples without ciprofloxacin degradation (t=0), in contact with bacteria (for 35 min), result in a higher luminescence than with completely degraded ciprofloxacin (t=15min). These results indicate that by products are responsible for low bacteria viability.FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and project PTDC/CTM-NAN/121038/2010
Adaptive und Maladaptive Emotionen aus Sicht der REVT
Die Theorie der Rational-Emotiven Verhaltenstherapie (Ellis, 1985; Ellis & DiGiuseppe, 1993) postuliert, dass sich adaptive Emotionen nicht nur quantitativ von maladaptiven unterscheiden, sondern insbesondere qualitativ. Adaptive Emotionen wie Furcht, Ărger, Bedauern und Trauer sind eher angemessene Reaktionen auf ein auslösendes Ereignis und helfen, individuelle Ziele zu erreichen. Maladaptive Emotionen hingegen wie Wut, Schuld, Angst und Depression stellen unangemessene Reaktionen dar, die den individuellen Zielen zuwiderlaufen. Auch vermeintlich Ă€hnliche Emotionen wie beispielsweise Furcht und Angst sollten sich demnach hinsichtlich etablierter emotionsrelevanter Variablen unterscheiden lassen. In zwei Experimentalstudien wurden die EinschĂ€tzungen adaptiver und maladaptiver Emotionen bezĂŒglich der Dimensionen FunktionalitĂ€t, Valenz, Aktivierung, Dauerhaftigkeit, Einflussweite und TypizitĂ€t mittels unterschiedlicher Instrumente erhoben (N = 96 bzw. N = 240). Die Ergebnisse belegen, dass adaptive Emotionen insgesamt funktionaler, angenehmer und weniger unangenehm sind sowie weniger Lebensbereiche beeinflussen als maladaptive Emotionen, sich aber keine TypizitĂ€tsunterschiede zwischen den beiden Emotionsgruppen ergeben
TiO2/graphene and TiO2/graphene oxide nanocomposites for photocatalytic applications: A computer modeling and experimental study
Supplementary data related to this article can be found at http://dx. doi.org/10.1016/j.compositesb.2018.03.015.This work reports a computational study, focused on graphene (G) and graphene oxide (GO) interfaces with titanium dioxide (TiO2), and an experimental assay on the photocatalytic activity of TiO2/G and TiO2/GO nanocomposites in the degradation of two different pollutants: methylene blue and ciprofloxacin. Both carbon nanostructures were compared due to their different chemical structure: GO is a G derivative with oxygen functional groups which should promote a closer chemical interaction with TiO2 nanoparticles. Computational models of the fundamental properties of the composites indicated potentially improved photocatalytic activity compared to TiO2, namely lower band gaps and charge carrier segregation at the interfaces. These fundamental properties match qualitatively experimental results on methylene blue, which was more effectively degraded by TiO2/G and TiO2/GO nanocomposites than by pure TiO2 under UV light. In contrast, the same nanocomposites were found to be less efficient to degrade ciprofloxacin than pure TiO2 under visible and UV light. Therefore, this work showcases the relevance of an efficient matching between the catalyst and the molecular properties and structure of the pollutant.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PESTC/FIS/UI607/2014 and PEST-C/QUI/UIO686/2014 and the CICECO Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013). Access to computing facilities provided by the Project âSearch-ON2: Revitalization of HPC infrastructure of UMinhoâ (NORTE-07-0162-FEDER-000086) is also acknowledged. P. M. Martins and Luciana Pereira thanks the FCT for grants SFRH/BD/98616/2013 and SFRH/BPD/110235/2015, respectively. MMF for a program CiĂȘncia 2008 fellowship. The authors thank ïŹnancial support from the Basque Government Industry Department under the ELKARTEK Program. P.A.A.P. Marques thanks the grant IF/00917/2013/CP1162/ CT0016. Acknowledges also to FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-010145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio
Photocatalytic activity of TiO2/graphene and TiO2/graphene oxide nanocomposites
Semiconductor-based heterogeneous photocatalysis has been one of the most promising processes for
the treatment of contaminated water. Among the available catalysts, titanium dioxide (TiO2) presents
the best photocatalytic properties, being chemically and biologically inert, stable, non-toxic, cheap
and easy to produce. However, its energy bang gap lies in the ultraviolet (UV) range, which is
responsible for a reduced spectral activation, since UV radiation corresponds to only 5% of the solar
spectrum [1]. For this reason, one of the main purposes of the scientific community has been to
improve the photocatalytic performance of TiO2, namely through an adequate doping of this material,
or through the creation of nanocomposites, to enable photocatalysis occurrence by the incidence of
visible light. One alternative concerns the application of nanocomposites of TiO2 with graphene and
graphene oxide to photocatalytic processes [2].
In this work, nanocomposites of TiO2 with different weight concentrations of graphene and graphene
oxide (namely 0.5%, 1%, 1.5% and 3%) were synthetized by a one-step hydrothermal method and
characterized in terms of morphology, crystalline structure, vibrational modes and optical band gap.
The photocatalytic activity of these nanocomposites was then evaluated through the degradation of
methylene blue and ciprofloxacin solutions under UV and visible radiation. The results indicated that
the studied nanocomposites presented higher degradation rates of the methylene blue than the pure
TiO2, which increased with the content of graphene/graphene oxide. However, these composites
proved to be less suitable to degrade the ciprofloxacin solution than the pure TiO2 nanoparticles.Portuguese Foundation for Science and Technology (FCT) -
UID/FIS/04650/2013, PTDC/CTM-ENE/5387/2014 and SFRH/BD/98616/2013; Basque Government
Industry Department under the ELKARTEK Program.info:eu-repo/semantics/publishedVersio
Soybean (Glycine max) as a versatile biocatalyst for organic synthesis
A series of aliphatic and aromatic aldehydes and ketones were reduced using plant cell preparations of Glycine max seeds (soybean). The biotransformation of five aromatic aldehydes in water, at room temperature afforded the corresponding alcohols in excellent yields varying from 89 to 100%. Two prochiral aromatic ketones yielded the alcohol in very low conversion, 1% and to 4%; however with good enantiomeric excess (ee) of 99 and 79%, respectively. Additionally, three prochiral and one cyclic aliphatic ketones produced the corresponding alcohols in moderate yields varying from 10 to 58% and ee varying from 73 to 99%. Hydrolysis of two aromatic esters yielded the expected carboxylic acids in 49 and 66%. Most of the obtained alcohols have commercial value as cosmetic fragrances. Although, the enzymes present in soybean (reductase/lipase) has not been defined, the reaction is an important route for the preparation of pure alcohols and carboxylic acid, with low cost and environmental impact.Keywords: Glycine max, biocatalysis, bioreduction, aldehydes and ketones, ester hydrolysi
Acceleration of anaerobic reactions by conductive carbon nanomaterials
Anaerobic processes are environmentally friendly solutions for the decontamination of a wide range of recalcitrant compounds, while generating energy through the production of methane, a renewable energy source. The rates of anaerobic biotransformations are often slow, but the amendment with carbon-based conductive materials (CBCM) has been reported to accelerate the microbial conversions. For example, methane production from organic compounds could be accelerated in the presence of CBCM, which has been often justified by the occurrence of direct interspecies electron transfer (DIET), between anaerobic bacteria and methanogens, over the typical electron exchange via hydrogen or formate. However, in these studies the effect of conductive materials towards individual microbial species was never determined and therefore it is difficult to conclude whether it influences the entire microbial community and changes the electron transfer mechanism between distinct microbial groups, or whether it only stimulates the activity of specific groups of microorganisms. In our laboratory, we have been investigating the effect of CBCM in two main research areas: in the anaerobic biodegradation of organic pollutants, and in the activity of pure cultures of methanogens and in syntrophic co-cultures.ERC Grant nÂș323009; UID/BIO/04469/2013; POCI-01-0145-FEDER-006684; NORTE
-01-0145-FEDER-000004; FCOMP-01-0124-FEDER-027462; SFRH/BPD/80528/2011info:eu-repo/semantics/publishedVersio
A wide perspective of carbon materials as catalysts for bioremediation of emerging pollutants and methanogenesis
Biotransformation of emerging pollutants under anoxic conditions can be accelerated by carbon materials
(CM) acting as redox mediators. CM have been also extensively reported as facilitating external electron transfer in
methanogenic processes. Here, different CM including magnetic carbon materials (C@MNP), were prepared,
characterized and applied as RM on the biological reduction of Acid Orange 10 (AO10) and ciprofloxacin (CIP). CIP
could be biologically removed in the presence of CNT and CNT@2%Fe, and AO10 decolourisation rates were 79-fold
higher in the assays with CNT@2%Fe. The effect of carbon nanotubes (CNT) on the activity of several pure cultures of
methanogens was also investigated, demonstrating that CNT could accelerate up to 17-fold the methane production rate.
It is evident from this work that carbon materials with different chemical and textural characteristics can accelerate
significantly bioremediation and methanogenic processes. The fact that concentrations as low as 0.1 g/L were used with
positive effects, is remarkable in terms of economic feasibility of using CM as efficient catalysts in both processes.info:eu-repo/semantics/publishedVersio
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