Number Of Secondary Cells Research Articles

Morphological and Molecular Characterization of the Eggs of Some Noctuid Species Associated with Soybean in Brazil

AbstractThe most important species of Lepidoptera that attack soybean, in descending order of importance, are Chrysodeixis includens (Walker), Anticarsia gemmatalis Hübner, Spodoptera cosmioides (Walker), Spodoptera eridania (Stoll), and Spodoptera albula (Walker). In addition, Rachiplusia nu ( Guenée ) is one of the most common Plusiinae in the southern region of Brazil, encompassing the states of Paraná, Santa Catalina, and Rio Grande do Sul. The correct identification of these species is essential for choosing the appropriate control measures, as they differ in their susceptibility to insecticides and biological control agents. To distinguish Lepidoptera species commonly found in Brazil, the eggshells of all these species were morphologically characterized by scanning electron microscopy. Diagnostic characters for differentiating species include shape of rosette petals, number of primary cells, number of secondary cells, number of ribs, and rosette diameter. Also, a molecular diagnostic method using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis was developed to distinguish noctuid species commonly found in Brazil. A 658-bp region of the mitochondrial DNA cytochrome oxidase subunit I gene was amplified using PCR and then sequenced. The five Lepidoptera species were distinguished by restriction enzymes Bpm I and Mbol. RFLPs produced by Bpm I endonuclease were useful to discriminate species from within Spodoptera (S. cosmioides, S. eridania, and S. albula) and R. nu from C. includens. However, Bpm I did not digest the amplicons from S. eridania and C. includens, which were discriminated by RFLP patterns produced by the restriction enzyme MboI. PCR-RFLP can be performed in a short period, and it is useful to distinguish the most important Brazilian Lepidoptera soybean pests.

Marteilia cochillia sp. nov., a new Marteilia species affecting the edible cockle Cerastoderma edule in European waters

Marteilia “type C” was recently identified, by molecular characterization, in the cockle Cerastoderma edule from the Ebro Delta in southern Catalonia (Spain) where it caused high mortalities during the summer of 2008. The present paper provides a transmission electron microscopic morphological description and additional molecular analyses. Specific ultrastructural diagnosis is based in TEM observations of mature stages of the parasite characterized by four secondary cells which subdivide into three “proteic masses”. Each proteic mass contained two spores and thus six spores per secondary cell were suspected. The number of secondary cells and number and nature of spores define the morphological taxobasis to distinguish different members of the Phylum Paramyxea. New sequences included in the phylogenetic analysis place Marteilia “type C” in a well-defined cluster proximal to Marteilia refringens. The new data thus corroborate previous results and lead us to formally describe Marteilia “type C” as a new species, Marteilia cochillia n. sp. affecting bivalves in Europe.

Contribution to the Study of Multicellular Flows Inside Two-Dimensional Rectangular and Pinched Insulated Glazing Cavities

This paper describes the results of an investigation aimed at examining secondary cells in two-dimensional high aspect ratio cavities, such as those encountered in insulated glazing units (IGU). Numerically, the governing transient equations are solved using a co-located equal order control-volume finite element (CVFEM) approach. Velocity fields are obtained experimentally using a particle image velocimetry (PIV) system. Results for a rectangular cavity with an aspect ratio of 40 and Ra = 9524 are presented first. The secondary cell structure present for such conditions is well captured experimentally and compares favorably with corresponding numerical results. Experimentally, the results show that the secondary cells are in movement toward the bottom of the cavity. Flow structure in two different two-dimensional pinched cavities with an aspect ratio of 20 and Ra = 41606 and 28879 is also examined numerically. The main flow in such cavities is impeded by the restriction at the center, which tends to lower the overall Nusselt number by approximately 28% and 35% when the center plate deflections are 0.5 and 0.75 cm, respectively. Finally, for a center plate deflection of 0.75 cm, it is shown that the number of secondary cells is time dependent.

Flow patterns of natural convection in an air-filled vertical cavity

Flow patterns of two-dimensional natural convection in a vertical air-filled tall cavity with differentially heated sidewalls are investigated. Numerical simulations based on a finite difference method are carried out for a wide range of Rayleigh numbers and aspect ratios from the onset of the steady multicellular flow, through the reverse transition to the unicellular pattern, to the unsteady multicellular flow. For aspect ratios (height/width) from 10 to 24, the various cellular structures characterized by the number of secondary cells are clarified from the simulations by means of gradually increasing Rayleigh number to 106. Unsteady multicellular solutions are found in some region of Rayleigh numbers less than those at which the reverse transition has occurred.

Formation of cells in natural convection in a vertical slot at large Prandtl number

This paper presents several features at supercritical conditions of natural convection of large Prandtl number fluids in a vertical slot. Both experimental and numerical results show that even at slightly supercritical conditions the multicellular flow is in an unsteady state which is attributed to the moving and merging of cells. The effect of variable viscosity on the unsteadiness is investigated numerically. Successive merging and appearance of cells is characteristic of this convection so that the number of secondary cells changes with time. The bifurcation phenomena characterized by several modes of unsteady cellular flow are examined.

Secondary cells and separation in developing laminar curved-pipe flows

Laminar flows through 180° curved bends of circular cross section are investigated numerically. For small curvature ratio, α, defined as pipe radius over mean bend radius, the governing equations could be parabolized. The equations are solved for an α range of from 0.04 to 0.143, a Dean number (De) range of from 277.5 to 1360, and for a uniform flow, a potential vortex, and a parabolic flow inlet condition. In all these studies a zero cross-stream flow at the inlet is assumed. A detailed study of the effects of α, De, and inlet condition on the secondary flow pattern is carried out. Within the range of parameters investigated, up to three secondary cells are found in the cross-stream half-plane of a curved pipe. They are the Dean-type secondary cell, a secondary separation cell near the inner bend (closest to the center of curvature of the bend), and a third cell near the pipe center. The number of secondary cells in the cross-stream half-plane is greatly influenced by the inlet flow, and to a much lesser extent by α and De. For example, only the Dean cell is found in a curved-pipe flow where α and De are small and the inlet flow is either uniform or a potential vortex. When the inlet condition of the same case is changed to a parabolic flow, a three-cell structure results. Furthermore, as De increases to 1180, incipient axial flow separation begins at around 23° downstream of the curved-pipe entrance. The formation and extent of the separation and third cells are investigated together with their dependence on the parameters studied. This investigation further shows that, within the range of parameters examined, there is no secondary cell occurring near the outer bend, contrary to some earlier findings on fully developed curved-pipe flows.