1,019 research outputs found
Discrete Time Evolution and Energy Nonconservation in Noncommutative Physics
Time-space noncommutativity leads to quantisation of time and energy
nonconservation when time is conjugate to a compact spatial direction like a
circle. In this context energy is conserved only modulo some fixed unit. Such a
possibility arises for example in theories with a compact extra dimension with
which time does not commute. The above results suggest striking
phenomenological consequences in extra dimensional theories and elsewhere. In
this paper we develop scattering theory for discrete time translations. It
enables the calculation of transition probabilities for energy nonconserving
processes and has a central role both in formal theory and phenomenology.
We can also consider space-space noncommutativity where one of the spatial
directions is a circle. That leads to the quantisation of the remaining spatial
direction and conservation of momentum in that direction only modulo some fixed
unit, as a simple adaptation of the results in this paper shows.Comment: 17 pages, LaTex; minor correction
Insights into the nature of eutectic and deep eutectic mixtures
A stricter definition of a deep eutectic solvent (DES) is urgent, so that it may become a sound basis for further developments in this field. This communication aims at contributing to deepening the understanding of eutectic and deep eutectic mixtures concerning their definition, thermodynamic nature and modelling. The glut of literature on DES applications should be followed by a similar effort to address the fundamental questions on their nature. This hopefully would contribute to correct some widespread misconceptions, and help to establish a stringent definition of what a DES is. DES are eutectic mixtures for which the eutectic point temperature should be lower to that of an ideal liquid mixture. To identify and characterize them, their phase diagrams should be known, in order to compare the real temperature depression to that predicted if ideality is assumed, and to define composition ranges for which they are in the liquid state at operating temperatures. It is also shown that hydrogen bonding between the DES components should not be used to define or characterize a DES, since this would describe many ideal mixtures. The future of deep eutectic solvents is quite promising, and we expect that this work will contribute to the efficient design and selection of the best DES for a given application, and to model properties and phase equilibria without which the process design is impractical.This work was developed in the scope of the Project CICECO – Aveiro Institute of
Materials, POCI-01-0145-FEDER-007679 (Ref. FCT UID/CTM/50011/2013) and Associate Laboratory
LSRE-LCM, POCI-01-0145-FEDER-006984 (Ref. FCT UID/EQU/50020/2013), both financed by national
funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership
Agreement. This work is also a result of Project “AIProcMat@N2020 - Advanced Industrial Processes
and Materials for a Sustainable Northern Region of Portugal 2020”, with the reference NORTE-01-0145-
FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the
Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). FCT
is also acknowledged for funding the project DeepBinfo:eu-repo/semantics/publishedVersio
PMS75 Explanatory Factors for the Rheumatoid Arthritis Patients' Access to Biological Agents in 15 European Countries
The slope current along the western European margin: A numerical investigation
A three-dimensional hydrodynamic model is used to investigate the poleward flow along the western European slopes. The area of the model domain goes from northwest Africa to Ireland. During a first stage, the currents are driven by climatological density fields. In a second stage the model is also forced by climatological winds, although special attention is paid to spring, when the winds are favourable to the development of an equatorward jet along the Iberian coast. Results show that the climatological density field is able to produce the poleward current along the European continental slope. Winds can modify the flow pattern, mainly in the southern areas off Iberia, specially during the upwelling season. The poleward current obtained is continuous between the Portuguese and French coasts, following the contour depths, with a core of maximum velocity located from 300-1 500 m, depending both on space and time. This core corresponds to the shelfward divergence of isopycnals. Maximum speeds range from 10-20 cm/s. A poleward intensification of the current is also obtained.Un modelo tridimensional hidrodinámico se ha usado para investigar el flujo en dirección hacia el polo a lo largo del talud occidental europeo. El área de dominio del modelo va desde el noroeste de áfrica hasta Irlanda. En un primer estadio, las corrientes son dirigidas por los campos climatológicos de densidad. En un segundo estadio el modelo se fuerza con vientos climatológicos, donde se presta una especial atención a la primavera, cuando los vientos son favorables al desarrollo de un jet en dirección al ecuador a lo largo de la costa ibérica. Los resultados muestran cómo el campo de densidad climatológica es capaz de producir una corriente en dirección al polo a lo largo del talud del continente europeo. Los vientos pueden modificar este esquema de flujo, principalmente en las áreas al sur de la península Ibérica, sobre todo durante la estación de upwelling. La corriente hacia el polo obtenida es continua entre las costas portuguesa y francesa, siguiendo las líneas de profundidad, con una velocidad máxima en el núcleo situada entre 300 m y 1 500 m, dependiendo tanto del espacio como del tiempo. Este núcleo corresponde a la divergencia de las isopicnas hacia la plataforma continental. Las velocidades máximas varían entre 10 y 20 cm/s. También se obtiene una intensificación hacia el polo de la corriente.Instituto Español de Oceanografí
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SciBERT-based Semantification of Bioassays in the Open Research Knowledge Graph
As a novel contribution to the problem of semantifying bio-
logical assays, in this paper, we propose a neural-network-based approach to automatically semantify, thereby structure, unstructured bioassay text descriptions. Experimental evaluations, to this end, show promise as the neural-based semantification significantly outperforms a naive frequencybased baseline approach. Specifically, the neural method attains 72% F1 versus 47% F1 from the frequency-based method. The work in this paper aligns with the present cutting-edge trend of the scholarly knowledge digitalization impetus which aim to convert the long-standing document-based format of scholarly content into knowledge graphs (KG). To this end, our selected data domain of bioassays are a prime candidate for structuring into KGs
Liquefying Compounds by Forming Deep Eutectic Solvents: A Case Study for Organic Acids and Alcohols
The criterion to distinguish a simple eutectic mixture from
a deep eutectic solvent (DES) lies in the deviations to thermodynamic
ideality presented by the components in the system. In this work, the
current knowledge of the molecular interactions in types III and V DES is
explored to liquefy a set of three fatty acids and three fatty alcohols, here
used as model compounds for carboxyl and hydroxyl containing solid
compounds. This work shows that thymol, a stronger than usual hydrogen
bond donor, is able to form deep eutectic solvents of type V with the fatty
alcohols studied. This is particularly interesting, since these DES formed
are hydrophobic. Regarding type III DES, the results suggest that the
prototypical DES hydrogen bond acceptor, cholinium chloride, is unable
to induce negative deviations to ideality in the model molecules studied.
By substituting choline with tetramethylammonium chloride, it is shown that the choline hydroxyl group is responsible for the
difficulty in forming choline-based deep eutectic solvents and that its absence induces strong negative deviations to ideality in the
alkylammonium side. Finally, it is demonstrated that tetrabutylammonium chloride acts as a chloride donning agent, causing
significant negative deviations to ideality in both fatty acids and alcohols and leading to the formation of deep eutectic solvents of
type III.This work was developed within the scope of the projects
CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and
UIDP/50011/2020, financed by national funds through the
Portuguese Foundation for Science and Technology/MCTES,
and CIMO-Mountain Research Center, UIDB/00690/2020,
financed by national funds through the FCT/MEC and when
appropriate cofinanced by FEDER under the PT2020 Partnership
Agreement. L.P.S. acknowledges FCT for her PhD grant
SFRH/BD/135976/2018.info:eu-repo/semantics/publishedVersio
Tuberculose disseminada com manifestações cerebrais, pulmonares, ganglionares e intestinais em raposas
Tuberculose disseminada com manifestações cerebrais, pulmonares, ganglionares e intestinais em raposas
Green extraction of glycosides from Stevia rebaudiana (Bert.) with low solvent consumption: A desirability approach
The sweet flavor of Stevia rebaudiana (Bert.) leaf extract is well known and has raised the interest of huge food companies due to its natural bid. The extraction of their main glycosides stevioside and rebaudioside A is an important step on the preparation of final Stevia granules. The aim of the work reported here was to study and optimize the dynamic maceration of Stevia leaves using water and ethanol as green solvents. For instance, a fractional factorial design was chosen to evaluate the individual effects of the drug powder size, weight ratio of drug to solvent, temperature, agitation, and time on the yield of these glycosides. The glycosides were quantified by high pressure liquid chromatography. An exhaustive extraction by successive maceration steps showed that ethanol 70% was superior to water and ethanol 90% for stevioside and rebaudioside extraction. The liquid extract composition in dry basis and the yield of stevioside and rebaudioside A were significantly affected by the drug to solvent weight ratio, showing that larger volumes of solvent should be used. Furthermore, increasing solvent volume favors the extraction of the stevioside by a twofold factor as compared to rebaudioside A. Among the other factors, only drug powder size affected the yield of rebaudioside A significantly. The optimal solution for S. rebaudiana leaves dynamic extraction estimated by desirability functions methodology led to a condition which allows obtaining extraction yields of 2.31 and 1.24% for stevioside and rebaudioside A and their concentrations in dried extract corresponding to 8.38 and 4.51%, respectively. These high yields were obtained with drug to solvent ratio (1:10, w/w) much higher than previous works, thus resulting in a more sustainable and green process
Solid-liquid equilibria for hexafluorophosphate-based ionic liquid quaternary mixtures and their corresponding subsystems
The present work describes an experimental study and the
thermodynamic modeling for the solid−liquid phase diagram of an ionic liquid
quaternary system constituted by hexafluorophosphate ([PF6]−) as the common
anion and by 1-methyl-3-propylimidazolium ([C3mim]+), 1-methyl-1-propylpyrrolidinium
([C3mpyrr]+), 1-methyl-3-propylpyridinium ([C3mpy]+), or 1-methyl-
1-propylpiperidinium ([C3mpip]+) as the cations. The Modified Quasichemical
Model was used to model the liquid solution, and the Compound Energy
Formalism was used for the relevant solid solutions. The liquidus projections of
the four ternary subsystems (1) [C3mim][PF6]−[C3mpip][PF6]−[C3mpyrr]-
[PF6], (2) [C3mpy][PF6]−[C3mpip][PF6]−[C3mpyrr][PF6], (3) [C3mpip]-
[PF6]−[C3mpy][PF6]−[C3mim][PF6], and (4) [C3mpyrr][PF6]−[C3mpy]-
[PF6]−[C3mim][PF6] were predicted using a standard symmetric (for systems 3
and 4) or asymmetric (for systems 1 and 2) interpolation method. In order to test
the accuracy of the thermodynamic model, two isoplethal sections were experimentally measured in each of the four ternary
systems using differential scanning calorimetry. Overall, agreement was very satisfactory, not requiring fitting of any ternary
interaction parameters for the liquid solution model. In each of the four calculated ternary liquidus projections, the region of
composition corresponding to room temperature ionic liquid mixtures was determined. The global minimum of the liquidus
temperature in the complete composition space was calculated to be about −16 °C, with a mole percentage composition of
(33.8% [C3mpyrr][PF6] + 33.9% [C3mpy][PF6] + 32.3% [C3mim][PF6]).The modeling part of this project was supported by the
Natural Sciences and Engineering Research Council of Canada
(Discovery Grant RGPIN 435893-2013). The new DSC
measurements in the four ternary subsystems were supported
by the laboratories CICECOAveiro Institute of Materials,
project POCI-01-0145-FEDER-007679 (ref FCT UID/CTM/
50011/2019), and Associate Laboratory LSRE-LCM (ref FCT
UID/EQU/50020/2019), both financed by national funds
through the FCT/MEC and when appropriate cofinanced by
FEDER under the PT2020 Partnership Agreement, and the
project “AIProcMat@N2020Advanced Industrial Processes
and Materials for a Sustainable Northern Region of Portugal
2020” (ref NORTE-01-0145-FEDER-000006) supported by
Norte Portugal Regional Operational Programme (NORTE
2020), under the Portugal 2020 Partnership Agreement,
through the European Regional Development Fund (ERDF).
Constructive discussions with Dr. Aım̈ en Gheribi, Prof. Youn-
Bae Kang, and Prof. Nick Virgilio were much appreciated.info:eu-repo/semantics/publishedVersio
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