Some thoughts about nonequilibrium temperature

The main objective of this paper is to show that, within the present framework of the kinetic theoretical approach to irreversible thermodynamics, there is no evidence that provides a basis to modify the ordinary Fourier equation relating the heat flux in a non-equilibrium steady state to the gradient of the local equilibrium temperature. This fact is supported, among other arguments, through the kinetic foundations of generalized hydrodynamics. Some attempts have been recently proposed asserting that, in the presence of non-linearities of the state variables, such a temperature should be replaced by the non-equilibrium temperature as defined in Extended Irreversible Thermodynamics. In the approximations used for such a temperature there is so far no evidence that sustains this proposal.Comment: 13 pages, TeX, no figures, to appear in Mol. Phy

Photochromic heteroarylethenes with fast thermal isomerization kinetics

Supplementary data to this article can be found online at https://doi.org/10.1016/j.dyepig.2022.111000Stilbenes (diphenylethenes) are fully examined organic chromophores for very diverse applications. However, these molecules might show poor stability under irradiation because several simultaneous reactions (oxidative photocyclization and dimerization) can take place during the photochemical isomerization of their C=C bond. In this context, heteroarylethenes emerge as powerful counterparts thanks to their improved stability. In addition, the chosen heterocycles and their functionalization allows to fine tune and increase the speed at which the thermal back reaction occurs, broadening the scope of application of the resulting chromophores. Here we report on the thermal Z-to-E isomerization kinetics of a series of rationally designed heteroarylethenes and how the chemical architecture of the chromophore modulates the speed of the process. Specifically, the metastable Z isomers display relaxation times covering a wide time window, from a few hours to hundreds of microseconds. In fact, one of the studied dyes is the fastest heteroarylethene known to date. It should be also noticed that the described heteroarylethenes exhibit great photochemical stability, it being possible to switch them back and forth many times without degradation.This research was funded by the Ministerio de Ciencia, Innovacion y Universidades (Spain)/Agencia Estatal de Investigacion (Spain)/Fondo Europeo de Dearrollo Regional (FEDER, European Union), grant number PGC2018-095477-B-I00. Thanks are also due to Fundação para a Ciência e Tecnologia (FCT) and to FEDER-COMPETE for financial support through the research center CQUM (UID/QUI/0686/2016) and (UID/ QUI/0686/2020). The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project Nº 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). Authors also thank Prof. Santi Nonell for granting access to the nanosecond laser flash photolysis setup

Fastest non-ionic azo dyes and transfer of their thermal isomerisation kinetics into liquid-crystalline materials

Push-pull bithienylpyrrole-based azo dyes exhibit thermal isomerisation rates as fast as 1.4 μs in acetonitrile at 298 K becoming, thus, the fastest neutral azo dyes reported so far. These remarkably low relaxation times can be transferred into liquid-crystalline matrixes enabling light-triggered oscillations in the optical density of the final material up to 11 kHz under ambient conditions.Financial support for this research was obtained from the Ministerio de Economía y Competitividad (Spain, CTQ2012-36074 and CTQ2015-65770-P). The authors thank Prof. Santi Nonell for his help with the flash photolysis measurements. Thanks are also due to: Fundação para a Ciência e Tecnologia (FCT) for a PhD grant to M. C. R. Castro (SFRH/BD/78037/2011); FEDERCOMPETE for financial support through the Centro de Quı ´mica – UM, PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT

Molecular photo-oscillators based on highly accelerated heterocyclic azo dyes in nematic liquid crystals

Benzothiazole-pyrrole-based azo dyes enhance greatly their thermal isomerisation rate up to 160 times when they are under the influence of the nematic mean field yielding the LC-based photochromic oscillators with the highest oscillation frequencies reported so far (2.6 kHz at 298 K).Fundação para a Ciência e a Tecnologia (FCT

Parámetros productivos y digestivos de gazapos de engorde alimentados con dietas enriquecidas con aceite de salmón

El objetivo del presente trabajo ha sido determinar el efecto de la suplementación de ácidos grasos poliinsaturados n-3 sobre los parámetros productivos y digestivos en gazapos durante el período de cebo (30-60 días). Para ellos se formularon dos piensos que únicamente diferían en la fuente de grasa: manteca (grupo CON) o un producto comercial a base de aceite de salmón rico en ácidos grasos poliinsaturados n-3 (PUFA). En ambos casos, el nivel de inclusión de grasa fue de 7,5 g/kg de pienso. Cada uno de los piensos se administró a 12 camadas de gazapos de 8 animales cada una. En la mitad de las camadas de cada tratamiento se determinó semanalmente el consumo de pienso (CMD) y la ganancia de peso vivo (GMD) de los animales y al final de la prueba se sacrificaron 4 animales de cada camada. En la otra mitad de las camadas, se sacrificaron 2 gazapos de cada una de los 30 (destete), 45 y 60 días de vida para analizar los parámetros de fermentación cecal y la morfología ileal. No se encontraron diferencias (P>0,05) entre tratamientos en el CMD, GMD, índice de conversión del alimento, peso al sacrificio, pero de la canal, pH y concentración de NH3-N en el contenido cecal, ni en la morfología ileal (longitud de vellosidades y profundidad de criptas). Los gazapos suplementados con PUFA presentaron mayores (P<0,001) concentraciones de ácidos grasos volátiles en el ciego a los 30 y 45 días de edad que los gazapos control y se observó una tendencia (P=0,062) a este efecto a los 60 días de edad. En conclusión, la sustitución del manteca por PUFA en la dieta no afectó al rendimiento productivo de los gazapos, pero incrementó la fermentación de la digesta en el ciego

Estudio de diferentes protocolos de restricción alimentaria sobre el desarrollo fetoplacentario en la coneja

Two feed strategies (ad libitum throughout pregnancy and restriction during the first 20 days), combined with oestrus synchronization with eCG or not in nulliparous rabbit does, were studied

SO(10) unified models and soft leptogenesis

Motivated by the fact that, in some realistic models combining SO(10) GUTs and flavour symmetries, it is not possible to achieve the required baryon asymmetry through the CP asymmetry generated in the decay of right-handed neutrinos, we take a fresh look on how deep this connection is in SO(10). The common characteristics of these models are that they use the see-saw with right-handed neutrinos, predict a normal hierarchy of masses for the neutrinos observed in oscillating experiments and in the basis where the right-handed Majorana mass is diagonal, the charged lepton mixings are tiny. In addition these models link the up-quark Yukawa matrix to the neutrino Yukawa matrix Y^\nu with the special feature of Y^\nu_{11}-> 0 Using this condition, we find that the required baryon asymmetry of the Universe can be explained by the soft leptogenesis using the soft B parameter of the second lightest right-handed neutrino whose mass turns out to be around 10^8 GeV. It is pointed out that a natural way to do so is to use no-scale supergravity where the value of B ~1 GeV is set through gauge-loop corrections.Comment: 26 pages, 2 figures. Added references, new appendix of a relevant fit and improved comment

Molecular elucidation of CO2 methanation over a highly active, selective and stable LaNiO3/CeO2-derived catalyst by in situ FTIR and NAP-XPS

The CO2 methanation mechanism over the highly active (TOF=75.1 h−1), selective (>92%) and stable 10% LaNiO3/CeO2-derived catalyst is still unresolved. The surface of the catalyst is monitored under hydrogenation (H2), oxidizing (CO2) and CO2 methanation (H2 +CO2) conditions by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) using synchrotron radiation. Meanwhile, the main reaction intermediates are identified by in situ FTIR analysis. NAP-XPS experiments confirm that LaNiO3 perovskite reduction leads to the ex-solution of Ni0 nanoparticles and Ni2+single bondCeO2−x and Ni2+single bondLa2O3 interfaces conformation, favouring the CO2 adsorption and the H2 dissociation/transfer. In situ FTIR experiments combined with the C1s spectra (NAP-XPS) suggest that the CO2 activation occurs on CeO2−x (oxygen vacancies and OH–) at low temperatures, in the form of bicarbonates; whereas, mono-/bidentate carbonates are formed on different strength La2O3 sites at increasing temperatures. These species are consecutively reduced to formates, as the main reaction intermediate, and methane by the H spilled from Ni0 nanoparticles near to NiOsingle bondCeO2−x and NiOsingle bondLa2O3 interfaces.Support for this study was provided by Projects PID2019–105960RB-C21 and PID2019–105960RB-C22 by MCIN/AEI/10.13039/501100011033, the Basque Government (Project IT1509–2022), Generalitat Valenciana (CIPROM/2021/74) and ALBA synchrotron. One of the authors (JAOC) acknowledges the postdoctoral research grant (DOCREC20/49) provided by the University of the Basque Country (UPV/EHU)