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Ring nematodes are obligate ectoparasites on crops and natural herbaceous and woody plants, and some species are of economic importance and cause damage to roots of several crops. Recent integrative taxonomical analyses recognized the existence of two cryptic species within the Criconema annuliferum morphotype in Spain. In this study, we corroborated that morphometric, morphological and a multi-locus analysis (including the ribosomal markers D2-D3 expansion segments of 28S rRNA, ITS rRNA, 18S RNA, and the mitochondrial DNA cytochrome oxidase I gene) identified a new lineage clearly separated from C. annuliferum, C. paraannuliferum and C. plesioannuliferum. The new lineage was described herein as Criconema pseudoannuliferum sp. nov., confirming that C. annuliferum species complex species complex comprises a hyper-cryptic species complex. This research analysed soil samples from the rhizosphere of maritime pine (Pinus pinaster Ait.) forests in Bermeja-Crestellina Mountain, located at the western part of Málaga province, southern Spain. The integrative taxonomical analyses revealed the occurrence of a new cryptic species identified using females, males and juveniles with detailed morphology, morphometry and molecular markers, described herein as Criconema pseudoannuliferum sp. nov. All molecular markers (D2-D3, ITS, 18S and COI) were obtained from the same individual that was also used for morphological and morphometric analyses. This research demonstrated the hidden diversity within the C. annuliferum species complex species complex can reach to four lineages under ribosomal and mitochondrial gene markers for one morphospecies group, which includes four species, viz. C. annuliferum, C. paraannuliferum, C. plesioannuliferum, and C. pseudoannuliferum sp. nov. Criconema pseudoannuliferum sp. nov. was detected in moderate soil density in two maritime pine forests (5 and 25 nematodes/500 cm3 of soil) suggesting that does not cause damage to maritime pine., This research was supported by the Spanish Ministry of Science, Innovation and Universities, grant number RTI2018-095345-B-C21, LITHOFOR (“Modulating role of LITHOlogy in the response of Mediterranean FORest ecosystems to climate change: growth, edaphological processes and future predictions”); and grant RYC2021-031108-I, funded by MCIN/AEI/10.13039/501100011033 and UE “Next Generation EU/PRTR”.

Accepted manuscript version, licensed CC BY-NC-ND 4.0. Achieving effective size selectivity for different species within a fishing gear is a major challenge in mixed fisheries. Fish behaviour may be exploited to separate species into separate codends where different selective properties can then be applied. Within the Basque bottom trawl fishery such a set-up has never been tested despite species with different behaviours being present. In this study, we investigate if species separation can be achieved through the use of a horizontal grid, where species typically found close to the seabed are intended to pass through the horizontal grid into the lower codend, while maintaining other species in an upper codend. Furthermore, the effect of artificial light on grid passage probability was estimated. Results were obtained for five fish species of commercial interest in the Basque bottom trawl fishery. Less than 25% of the individuals of all species analysed passed through the grid and were retained in the lower codend, and no significant differences were found when the grid was illuminated. The specific conditions under which the Basque bottom trawl fishery is conducted, i.e., high turbidity levels, high towing speed, may have influenced the performance of the gear in this fishery. Consequently, the design was found to have limited potential to improve species and size selection in the Basque bottom trawl fishery.

Показано, что пластмассы являются важнейшими конструкционными материалами в автомобилестроении, рациональное применение которых позволяет достичь высокой утилизируемости транспортных средств после завершения их эксплуатации. Для этого рекомендовано использовать пластмассы из термопластичных полимеров, способных к многократной переработке с сохранением основных характеристик. Доступная утилизация автокомпонентов из пластмасс позволяет сократить потребление материальных и энергетических ресурсов, уменьшить загрязнение окружающей среды и тем самым повысить экологичность автомобилей., It is shown that plastics are the most important structural materials in the automotive industry, the rational use of which makes it possible to achieve high utilization of vehicles after their operation. For this purpose, it is recommended to use plastics made of thermoplastic polymers that are capable of repeated processing while preserving the main characteristics. Affordable recycling of plastic car components reduces the consumption of material and energy resources, reduces environmental pollution and thereby improves the environmental friendliness of cars., Управление техносферой, Выпуск 1 2021, Pages 11-17

Molecular contamination refers to the formation of molecular deposits that can modify the surface properties of satellites components and reduce their performances. To mitigate the degradation risks, realistic predictions of molecular contamination levels are essential. However, errors of several orders of magnitude can be made during predictions if no separation method is used to get the proper model for each molecular species.This thesis aims to develop the species separation method implemented at ONERA thanks the experimental apparatus COPHOS (COntamination PHOton Synergy) in order to carry out a species separation robust and free from thermal artefact within the thermal range [-80;150]°C. To meet this challenge, the mass spectrometry data generation capacity and the sample older thermal regulation have been extended to the aimed thermal range in order to characterize the less volatile molecules that are likely to induce in flight degradations. Those developments enabled to carry out a species separation on the space adhesive Scotchweld EC2216 to test the method. This separation allowed the estimation of the major species fluxes and their identification through their mass spectrum. Thanks to the real species kinetics determination, molecular contamination models were compared, bringing a fresh perspective on contamination physics., La contamination moléculaire désigne la formation de dépôts de contaminants pouvant modifier les propriétés de surface des composants du satellite et diminuer leurs performances. Pour limiter le risque de dégradations, il est indispensable de réaliser des prédictions fiables des niveaux de contamination. Cependant, des erreurs de plusieurs ordres de grandeurs peuvent être générés si aucune méthode de séparation n’est utilisée pour obtenir le modèle adéquat pour chaque espèce moléculaire.Cette thèse a pour but de développer la méthode de séparation des espèces mise en oeuvre à l’ONERA à l’aide du moyen d’essai COPHOS (COntamination PHOton Synergy) afin de réaliser une séparation des espèces robuste et exempte d’artefact thermique sur la plage de température [-80 ; 150]°C. Pour cela, la capacité de génération de données par spectrométrie de masse et la régulation thermique des éléments du porte-échantillon ont été étendues à la plage de température de caractérisation visée afin de caractériser les molécules les moins volatiles, qui sont plus susceptibles d’engendrer des dégradations en vol.Ces développements ont permis de réaliser une séparation sur l’adhésif spatial Scotchweld EC2216 afin d’éprouver la méthode. Celle-ci a permis d’estimer le flux des espèces majoritaires et de les identifier via leur spectre de masse. Grâce à la mise en évidence des cinétiques réelles des molécules, les modèles de contamination ont été confrontés, permettant de porter un regard nouveau sur la physique de la contamination.

In management of fisheries, knowledge about the species is crucial due to differences in life history traits. The first step is therefore species identification. For many species this task is straightforward, however for some species e.g. the two species of Atlantic redfish Sebastes mentella and Sebastes norvegicus, it can be difficult for an untrained eye. With the goal to separate the two species, we analysed otolith shape variation of S. mentella and S. norvegicus caught on the continental slope of East Greenland using the R package “Shape R”. Results were evaluated against genetic analysis of the same fish, and compared to results of both a visual identification of the two species and a separation based on a linear discriminant analysis on standardised values of fish length, fish weight and otolith weight. It was concluded that the objective otolith shape analysis using the Shape R package analysis achieve a reasonable classification success, however with a clear bias towards S. mentella. Classification using the otolith weight achieved a slightly higher success than the shape analysis making it a promising method. Furthermore, the method is at the same time both objective, less time consuming than the otolith shape analysis and less expensive than genetic analysis. However, the visual classification method of the whole fish had the highest success rate of the three tested methods, which despite the need for trained technicians makes it the most successful method.

Made available in DSpace on 2022-04-29T23:53:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Universidade de São Paulo Growers appreciate Cattleya walkeriana and C. loddigesii due to striking shape and rarity. Thus, this study aimed to evaluate the feasibility of DNA barcode regions, namely ITS1, ITS2 and rpoC1, to discriminate between C. walkeriana and C. loddigesii species. DNA barcode regions were successfully amplified using primers designed to amplify plants. We also included sequences from public databases in order to test if these regions were able to discriminate C. walkeriana and C. loddigesii from other Cattleya species. These regions, and their combinations, demonstrated that the ITS1+ITS2 had the highest average interspecific distance (11.1%), followed by rpoC1 (1.06%). For species discrimination, ITS1+ITS2 provided the best results. The combined data set of ITS1+ITS2+rpoC1 also discriminated both species, but did not result in higher rates of discrimination. These results indicate that ITS region is the best option for molecular identification of these two species and from some other species of this genus. Departamento de Genética Instituto de Biociências Universidade Estadual Paulista Instituto de Biotecnologia Universidade Estadual Paulista Universidade Estadual do Centro-Oeste, PR-153, Km 7 Faculdade de Ciências Agronômicas Universidade Estadual Paulista, Rua José Barbosa de Barros, 1780 Escola Superior de Agricultura “Luiz de Queiroz” Universidade de São Paulo Departamento de Genética Instituto de Biociências Universidade Estadual Paulista Instituto de Biotecnologia Universidade Estadual Paulista Faculdade de Ciências Agronômicas Universidade Estadual Paulista, Rua José Barbosa de Barros, 1780

An analytical and numerical study of the action of ultrasonic waves on species separation within a rectangular cavity filled with a binary fluid (water-ethanol mixture) is presented. An ultrasonic wave was emitted on a portion of one of its vertical walls, while the opposite wall was perfectly absorbent. The two horizontal walls were differentially heated. A progressive acoustic wave was used to generate, at a large scale, a stationary flow of the viscous binary fluid (Eckart Streaming) within the cavity. The authors analytically determined the temperature T, mass fraction C and velocity fields under the parallel flow hypothesis used for cells with high aspect ratio [Formula: see text], in the presence of the gravitational field. From the analysis of the velocity fields the authors concluded that the associated flow is either unicellular or consists of three counter-rotating cells superimposed in the horizontal direction of the cavity. They also found the variation domains of the physical parameters leading to one or the other of these two types of flows. The algebraic equation allowing the calculation of the mass fraction gradient and hence the species separation between the vertical walls of the cavity was determined. The variation of the dimensional mass fraction gradient, for the water-ethanol mixture, as a function of the two control parameters of the problem, namely the acoustic parameter A and the temperature difference [Formula: see text] imposed on the two horizontal walls was studied.

The evolution of an initially homogeneous solution consisting of two species subjected to a thermal gradient which generates a mass transfer, which can lead to the separation species from the binary fluid, is studied. The configuration chosen to study the separation is a rectangular (or parallelepipedic) cell, horizontal and placed in the gravitational field. The presence of a piezoelectric source on one of the vertical walls of the cavity makes it possible to generate a stationary flow on a large scale. The flow is induced by the propagation of ultra-sonic waves within the viscous fluid : the dissipation of the acoustic energy of the wave within the fluid is called Eckart streaming. We seek to optimize the separation by combining thermal gradient and acoustic source. The first part consists of the study of the isothermal flow generated by the ultrasonic wave in a monoconstituent fluid. After calculating the acoustic intensity field with the Rayleigh integral, the profile is implemented in a Comsol Multiphysics finite element code. The numerical results are compared with previous experimental results. In a second part, we consider a cavity containing a binary fluid. A configuration heated from the top is privilegied to allow the insertion of an acoustic source. The separation (difference of mass fraction between the two ends of the cell) is determined analytically using the Maple software as a function of the control parameters of the problem. 2D and 3D numerical simulations showed a good agreement between the analytical and numerical results, for a constant acoustic parameter. The problem considered depends on eight dimensionless parameters. Three of them are specific to the nature of the binary fluid : the Lewis number Le, the Prandtl number Pr and the separation factor ψ. There are then two control parameters, the thermal Rayleigh number Ra and the adimensional acoustic force A. Finally, the other dimensionless parameters are the two aspect ratios of the cavity, as well as the relative thickness of the beam.; On étudie l'évolution d'une solution initialement homogène constituée de deux espèces soumises à un gradient thermique qui génère un transfert de matière, ce qui peut conduire à la séparation des espèces du fluide binaire. La configuration choisie pour étudier la séparation est une cellule rectangulaire (ou parallélépipédique), horizontale et placée dans le champ de pesanteur. La présence d'une source piézo-électrique, sur l'une des parois verticales de la cavité, permet de générer un écoulement stationnaire à grande échelle. L'écoulement est induit par la propagation d'ondes ultrasonores au sein du fluide visqueux : la dissipation de l'énergie acoustique de l'onde au sein du fluide porte le nom d'Eckart streaming. On cherche à optimiser la séparation en combinant gradient thermique et source acoustique. La première partie consiste en l'étude de l'écoulement isotherme généré par l'onde ultrasonore dans un fluide mono-constituant. Après avoir calculé le champ d'intensité acoustique avec l'intégrale de Rayleigh, le profil est implémenté dans un code aux éléments finis Comsol Multiphysics. Les résultats numériques sont comparés avec des résultats expérimentaux antérieurs. Dans une seconde partie, on considère une cavité contenant un fluide binaire. On détermine analytiquement, à l'aide du logiciel Maple, la séparation (différence de fraction massique entre les deux extrémités de la cellule) en fonction des paramètres de contrôle du problème. Des simulations numériques 2D et 3D ont montré un bon accord entre les résultats analytiques et numériques, pour un paramètre acoustique constant et un chauffage par le bas ou par le haut de la cellule. Le problème considéré dépend alors de huit paramètres adimensionnels. Trois d'entre eux sont propres à la nature du fluide binaire : le nombre de Lewis Le, de Prandtl Pr et le facteur de séparation ψ. Il y a ensuite deux paramètres de contrôle, le nombre de Rayleigh thermique Ra et la force acoustique adimensionnelle A. Enfin, les autres paramètres adimensionnels sont les deux rapports d'aspect de la cavité, ainsi que l'épaisseur relative du faisceau acoustique

In this paper, an analytical and numerical study of species separation in binary mixtures taking account of the presence of bounding plates for the cell is presented. A rectangular horizontal porous cavity saturated by a binary mixture and heated from below is considered. This cavity is bounded by thin plates of uniform thickness, the outer surfaces of which are subjected to a constant heat flux. The transition from the equilibrium solution to the convective one, either stationary or oscillatory, was previously studied by Ouattara et al. (2012). Thus in the first part of this paper, the critical parameters associated with the onset of long wavelength disturbances, obtained analytically, are recalled. Then the hypothesis of parallel flow is used to determine an analytical solution which describes the unicellular flow which may appear in the case of a large aspect ratio cell for a given range of separation ratio, ψ , Rayleigh number, Ra , Lewis number, Le, the ratio of the plate to the porous layer thickness, δ, and their thermal conductivity ratio, d. The analytical results are corroborated by direct numerical simulations. We verify that if d goes to infinity, the walls become infinitely conductive and we find the results obtained by Charrier-Mojtabi et al. (2007). When d tends to 0, the walls become infinitely thin the results obtained by Yacine et al. (2016) are recovered. A linear stability analysis of the unicellular flow is also presented. The eigenvalue problem resulting from the temporal stability analysis is solved by a Tau spectral method. The optimal Rayleigh number leading to an optimal value of the separation horizontal gradient is determined for different values of physical parameters. We show that the species separation depends sensitively on the ratio of the plate to the porous layer thickness, and the ratio of their thermal conductivities. Furthermore, we have shown that in the stationary state and for a given value of the thermal conductivity ratio (d = 29), the maximum separation is almost equal for walls of the same thickness than the one of porous cavity or for the case of porous cell delimited by the infinitely thin walls.

The evolution of an initially homogeneous solution consisting of two species subjected to a thermal gradient which generates a mass transfer, which can lead to the separation species from the binary fluid, is studied. The configuration chosen to study the separation is a rectangular (or parallelepipedic) cell, horizontal and placed in the gravitational field. The presence of a piezoelectric source on one of the vertical walls of the cavity makes it possible to generate a stationary flow on a large scale. The flow is induced by the propagation of ultra-sonic waves within the viscous fluid : the dissipation of the acoustic energy of the wave within the fluid is called Eckart streaming. We seek to optimize the separation by combining thermal gradient and acoustic source. The first part consists of the study of the isothermal flow generated by the ultrasonic wave in a monoconstituent fluid. After calculating the acoustic intensity field with the Rayleigh integral, the profile is implemented in a Comsol Multiphysics finite element code. The numerical results are compared with previous experimental results. In a second part, we consider a cavity containing a binary fluid. A configuration heated from the top is privilegied to allow the insertion of an acoustic source. The separation (difference of mass fraction between the two ends of the cell) is determined analytically using the Maple software as a function of the control parameters of the problem. 2D and 3D numerical simulations showed a good agreement between the analytical and numerical results, for a constant acoustic parameter. The problem considered depends on eight dimensionless parameters. Three of them are specific to the nature of the binary fluid : the Lewis number Le, the Prandtl number Pr and the separation factor ψ. There are then two control parameters, the thermal Rayleigh number Ra and the adimensional acoustic force A. Finally, the other dimensionless parameters are the two aspect ratios of the cavity, as well as the relative thickness of the beam., On étudie l'évolution d'une solution initialement homogène constituée de deux espèces soumises à un gradient thermique qui génère un transfert de matière, ce qui peut conduire à la séparation des espèces du fluide binaire. La configuration choisie pour étudier la séparation est une cellule rectangulaire (ou parallélépipédique), horizontale et placée dans le champ de pesanteur. La présence d'une source piézo-électrique, sur l'une des parois verticales de la cavité, permet de générer un écoulement stationnaire à grande échelle. L'écoulement est induit par la propagation d'ondes ultrasonores au sein du fluide visqueux : la dissipation de l'énergie acoustique de l'onde au sein du fluide porte le nom d'Eckart streaming. On cherche à optimiser la séparation en combinant gradient thermique et source acoustique. La première partie consiste en l'étude de l'écoulement isotherme généré par l'onde ultrasonore dans un fluide mono-constituant. Après avoir calculé le champ d'intensité acoustique avec l'intégrale de Rayleigh, le profil est implémenté dans un code aux éléments finis Comsol Multiphysics. Les résultats numériques sont comparés avec des résultats expérimentaux antérieurs. Dans une seconde partie, on considère une cavité contenant un fluide binaire. On détermine analytiquement, à l'aide du logiciel Maple, la séparation (différence de fraction massique entre les deux extrémités de la cellule) en fonction des paramètres de contrôle du problème. Des simulations numériques 2D et 3D ont montré un bon accord entre les résultats analytiques et numériques, pour un paramètre acoustique constant et un chauffage par le bas ou par le haut de la cellule. Le problème considéré dépend alors de huit paramètres adimensionnels. Trois d'entre eux sont propres à la nature du fluide binaire : le nombre de Lewis Le, de Prandtl Pr et le facteur de séparation ψ. Il y a ensuite deux paramètres de contrôle, le nombre de Rayleigh thermique Ra et la force acoustique adimensionnelle A. Enfin, les autres paramètres adimensionnels sont les deux rapports d'aspect de la cavité, ainsi que l'épaisseur relative du faisceau acoustique

We present an analytical and numerical stability analysis of Soret-driven convection in a porous cavity saturated by a binary fluid mixture and subjected to vertical high-frequency and small-amplitude vibrations. Two configurations have been considered and compared: an infinite horizontal layer and a bounded domain with a large aspect ratio. In both cases, the initial temperature gradient is produced by a constant uniform heat flux applied on the horizontal boundaries. A formulation using time-averaged equations is used. The linear stability of the equilibrium solution is carried out for various Soret separation ratios $$\varphi $$ , vibrational Rayleigh numbers Rv, Lewis numbers Le and normalized porosity. For an infinite horizontal layer, the critical Rayleigh number $$\mathrm{Ra}_c$$ is determined analytically. For a steady bifurcation to a one-cell solution (the critical wavenumber is zero), we obtain $$\mathrm{Ra}_{c}={12}/{({\varphi }(\mathrm{Le}+1)+1)}$$ for all Rv. When the bifurcation is a Hopf bifurcation or when the critical wavenumber is not zero, we use a Galerkin method to compute the critical values. Our study is completed by a nonlinear analysis of the bifurcation to one-cell solutions in an infinite horizontal layer that is compared to numerical simulations in bounded horizontal domains with large aspect ratio.

Species separation can be produced by imposing a pressure gradient in gaseous mixtures, which induces different molecular velocities depending on the molar weight. Pressure gradients can be achieved by centrifugal forces brought about by the passage of the gas through a curved nozzle at supersonic velocity. The efficiency of this process depends on the geometry of the nozzle as well as the flow operating conditions. The numerical solver Fluent was used in order to produce a model of the aerodynamics and the oxygen diffusion of a steady-state flow of air in a curved nozzle. The development of the pressure and O2 concentration profiles along the nozzle were analyzed for different pressure boundary conditions at the inlet and the exit, testing several nozzle sizes. Optimum values of the cut and the inlet pressure were found which maximize the separation efficiency. The effect of the exit pressure was associated with the axial pressure distribution along the inner wall of the nozzle. The results were compared with measurements showing good agreement. Fil: Guozden, Tomas Manuel. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Clausse, Alejandro. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

International audience; An analytical and numerical study of Soret-driven convection in a horizontal porous layer saturated by a binary fluid and subjected to uniform cross heat fluxes is presented. The flow is driven by the combined buoyancy effect due to temperature and induced mass fraction variations through a binary water ethanolmixture. In the first part of the study, a closed-form analytical solution in the limit of a large aspect ratio of the cell (A >> 1) is developed. We are mainly concerned with the determination of the mass fraction gradient of the component of interest along the horizontal direction, which determines the species eparation. In the second part, numerous numerical simulations are carried out in order to validate the analytical results and extend heat and mass transfer to an area not covered by the analytical study. Good agreement is found between analytical and numerical results concerning the species separation obtained for a unicellular flow. In this configuration, the Soret separation process is improved by two control parameters: the heat flux density imposed on the horizontal walls of the cell and the ratio, a, of heat flux density imposed on vertical walls to that on horizontal walls. The influence of the heat flux density ratio, a, on the transient regime (relaxation time) is also investigated numerically. We observe that an increase in the parameter a leads to a decrease in the relaxation time. Thus, for a cell heated from below withoutlateral heating, the onset of convection from the mechanical equilibrium state is analyzed. The linear stability analysis shows that the equilibrium solution loses its stability via a stationary bifurcation or a Hopf bifurcation depending on the separation ratio and the normalized porosity of the medium. The linear stability results are widely corroborated by direct 2D numerical simulations. The thresholds of various multicellular solutions are determined in terms of the governing parameters of the problem using nonlinear direct numerical simulations

International audience; The onset of Soret-driven convection in a shallow porous horizontal layer filled with a binary mixture and submitted to a vertical heat flux on the two horizontal walls is investigated. We study the species separation between the two vertical ends of the cell, which appears for low values of the Rayleigh number and for positive separation ratio. An analytical solution is performed and the separation is expressed in terms of thermal Rayleigh number, Lewis number, separation ratio and aspect ratio of the cell. These analytical results are corroborated by direct non-linear numerical simulations. Then, the results are compared with those obtained in a differentially heated vertical cavity.

In this paper, an analytical and numerical study to determine the species separation process in a binary fluid mixture by decoupling the thermal gradient from the convective velocity was performed. The configuration considered is a horizontal rectangular cavity of large aspect ratio, filled with a binary fluid. A constant tangential velocity is applied to the upper horizontal wall. The two horizontal impermeable walls are maintained at different and uniform temperatures T1 and T2 with ΔT = T2 − T1. Species separation is governed by two control parameters, the temperature difference and the velocity of the upper plate U e x → . The intensity of the thermodiffusion is controlled by the temperature gradient, while the velocity U e x → controls the convective flow. This problem depends on six dimensionless parameters, namely, the separation ratio ψ , the Lewis number Le, the Prandlt number Pr, the aspect ratio of the cell A and two control parameters: the thermal Rayleigh number, Ra and the Peclet number Pe. In this study, the separation (mass fraction difference between the two ends of the cell) is obtained analytically as a function of mass Peclet number (Pem = PeLe) and mass Rayleigh number ( Ra m = ψ R a L e ) . The optimal separation m = 42 / 15 ≈ 0.432 is obtained for Pe m = 42 and Ram = 540. The numerical results, obtained using the full governing equations, are in good agreement with the analytical results based on a parallel flow approximation.

International audience; In this paper, a numerical and analytical analysis is performed in order to improve the species separation process in a binary fluid mixture by decoupling the thermal gradient from the convective velocity. The configuration considered is a horizontal rectangular cavity, of large aspect ratio, filled with a binary fluid. A constant tangential velocity is applied to the upper horizontal wall. The two horizontal impermeable walls are maintained at different and uniform temperatures T1 and T2 with ΔT = T1 − T2 Species separation is governed by two control parameters, the temperature difference ΔT and the velocity of the upper plate Uex. The intensity of the thermodiffusion is controlled by the temperature, while the velocity Uex controls the convective flow. This problem depends on six dimensionless parameters, namely, the separation ratio, ψ, the Lewis number, Le, the Prandtl number Pr, the aspect ratio of the cell, A and two control parameters: the thermal Rayleigh number, Ra and the Péclet number Pe. In this study, the formulation of the separation (mass fraction difference between the two ends of the cell) as a function of the Péclet number and the Rayleigh number is obtained analytically. For a cell heated from below, the optimal separation m = √42/15 is obtained for Pe = √42/Le and Ra = 540/(Leψ). 2D numerical results, obtained by solving the full governing equations, are in good agreement with the analytical results based on a parallel flow approach.

Validity of the taxa currently recognized in the genus Vasconcellea was analyzed by investigating morphological and molecular data from 105 specimens of this genus and six specimens of the related genus Carica. Taxon identification of these specimens was compared with clustering in two phenetic dendrograms generated with 36 morphological characters and 254 amplified fragment length polymorphic (AFLP) markers. Moreover, cytoplasmic haplotypes were assessed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of one mitochondrial and two chloroplast DNA regions. Results show that the morphological data set, containing mainly vegetative characteristics, merely reveals external resemblance between specimens, which is not directly associated with genetic relationships and taxon validity. Phenotypic plasticity and intercompatibility between several species are likely to confuse morphological delimitation of the taxa. Based on the results of our study, several specimens that could not be identified with the currently used identification key (1) could be attributed to a known taxon, which should be extended to include a higher range of morphological variability or (2) could be hypothesized to be of hybrid origin. Because of the high intraspecific variation within V. microcarpa and V. X heilbornii, revision of these taxa is recommended.

The aim of this article is to present briefly a summary of the state of art in theoretical, experimental and numerical approaches in thermodiffusion. The concepts and equations giving the mass flux of constituents in binary, ternary and multicomponent mixtures are presented.