Home About us Contact
|
Home About us Contact | ||
|
|
||
Outer Wall (outer + wall)
Selected AbstractsA spatially advancing turbulent flow and heat transfer in a curved channelHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2010Koji Matsubara Abstract Direct numerical simulation was performed for a spatially advancing turbulent flow and heat transfer in a two-dimensional curved channel, where one wall was heated to a constant temperature and the other wall was cooled to a different constant temperature. In the simulation, fully developed flow and temperature from the straight-channel driver was passed through the inlet of the curved-channel domain. The frictional Reynolds number was assigned 150, and the Prandtl number was given 0.71. Since the flow field was examined in the previous paper, the thermal features are mainly targeted in this paper. The turbulent heat flux showed trends consistent with a growing process of large-scale vortices. In the curved part, the wall-normal component of the turbulent heat flux was twice as large as the counterpart in the straight part, suggesting active heat transport of large-scale vortices. In the inner side of the same section, temperature fluctuation was abnormally large compared with the modest fluctuation of the wall-normal velocity. This was caused by the combined effect of the large-scale motion of the vortices and the wide variation of the mean temperature; in such a temperature distribution, large-scale ejection of the hot fluid near the outer wall, which is transported into the near inner-wall region, should have a large impact on the thermal boundary layer near the inner wall. Wave number decomposition was conducted for various statistics, which showed that the contribution of the large-scale vortex to the total turbulent heat flux normal to the wall reached roughly 80% inside the channel 135° downstream from the curved-channel inlet. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20275 [source] The barnacle and the building: a modern morality taleINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 2 2008John S. BUCKERIDGE Abstract A rare and almost complete barnacle fossil, previously described on the basis of two isolated shell fragments, was recently exposed in a limestone block on the outer wall of Melbourne's Old Magistrates' Courts in Victoria, Australia. These courts comprise one of the oldest and grandest buildings in Melbourne and because of this they have a heritage listing. As heritage-listed buildings are protected from alteration by law, and as removal of the fossil would be deemed "alteration", official permission had to be obtained to extract the specimen. This paper discusses the processes involved with extraction of a unique specimen from a protected building and provides an overview of the palaeontological significance of the fossil. Consideration is given to the likely fate of a fossil of this nature, situated a little below eye level on a busy city street, if it was left in situ; finally, the implications of designating a holotype from material removed from a building are assessed. [source] Shaping ability of ProFile and K3 rotary Ni-Ti instruments when used in a variable tip sequence in simulated curved root canalsINTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2004L. R. Ayar Abstract Aim, To compare the shaping ability of ProFile and K3 rotary Ni-Ti instruments when used in a variable tip sequence in simulated curved root canals with different curvature and radius. Methodology, ProFile or K3 .06 taper instruments were used to prepare simulated canals of 20° curvature and 5 mm radius (n = 10) and 30° curvature and 3 mm radius canals (n = 10) in resin blocks. All canals were prepared to an apical size 40 at 0.5 mm from the canal terminus using a variable tip crown-down sequence. Pre- and postinstrumentation digital images were recorded, and an assessment of the canal shape was determined using a computer image analysis program. The material removal from the inner and outer wall of the canal was measured at 28 measuring points, beginning 0.5 mm from the end-point of the canal and the data compared using the Mann,Whitney U -test. Results, In 20° and 30° canals both instruments significantly removed more (P < 0.05) material on the outer wall than the inner wall in the apical half of the canal. For ProFile files there was no significant difference in the amount of material removed on the outer canal wall between the 20° and 30° canals. However, in the K3 groups significantly more (P < 0.05) outer canal wall was removed in the apical area in 20° canals. When comparing both instruments the results showed that in 20° canals K3 instruments removed more outer and inner canal wall than ProFile instruments (P < 0.05) but that there was no significant difference (P > 0.05) between the instruments in 30° canals. Conclusion, Within the limitation of this study, both rotary nickel-titanium instruments prepared a well-shaped root canal with minimal canal transportation. [source] An in vitro comparison of canal preparation using two automated rotary nickel,titanium instrumentation techniquesINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2000S. J. Jardine Abstract Aim The aim of this study was to compare the efficacy of root canal preparation using two automated rotary nickel,titanium instrumentation techniques with a double flared balanced forces hand preparation technique, using stainless steel files in extracted human teeth. Methodology Sixty root canals in extracted human teeth were matched for curvature, length and diameter and divided evenly between three groups (group 1 = double flare using Flexofiles®, group 2 = rotary nickel,titanium using McXIM® instruments and group 3 = rotary nickel,titanium using Profile® .04 TaperTM Series 29 instruments). The instruments were used according to the manufacturer's instructions in a torque controlled motor and handpiece (groups 2 and 3) and according to a predetermined procedure in group 1. A standardized radiographic technique using mercury as a contrast medium was used to evaluate the canal shape before and after preparation in the plane of maximum curvature. The pre- and postoperative radiographic images were compared against each other and with a predicted ,ideal preparation' calculated from a projection of the final instrument dimensions. The outcome measures were changes in canal dimensions as quantified by measuring the changes in the position of the inner and outer wall at 1 mm intervals. Alteration in canal curvature could be inferred by comparison with the ideal preparation. Results The degree of canal curvature did not influence the effectiveness of any of the techniques. The results showed no statistically significant differences in the outcome measures between the groups (two-way anova). There were no significant differences in canal wall position changes at any level except the apical three, where significantly less change occurred in all groups (P = 1%). Instruments fractured in three canals, with acute curves in groups 2 and 3. Conclusions Canal curvatures were equally and well maintained following preparation in all the groups, as long as the instrument did not fracture. [source] Experimental investigation into cavity-type inertial separators,a novel technique for development of subcompact circulating fluidized bed boilersINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2005Animesh Dutta Abstract Cavity-type inertial separators developed by GRI (Patent no. 2, 159, 949, Canada, 2002) were tested in a semi-industrial size circulating fluidized bed pilot plant operated at room temperature. Three rows of separators were hung from the roof of the pilot plant where one row was kept inside the riser and the others were kept in the primary separation chamber, located between the back-pass and the riser. Parameters measured were axial pressure drops along the height of the riser, vertical solids flux on the separator walls, lateral outwards solids flux in the riser with and without separator and local temperatures on the separator walls. A net downwards solids flux is on the inner wall of the separators; however, no downwards solids flux is on the outer walls of the separators. Heat transfer coefficients on the outer wall are found higher than those on the inner walls of the separator. It is also found that the presence of inertial separators not only provides additional heat transfer surfaces but also indirectly increases the heat transfer coefficients on the riser wall. Copyright © 2005 John Wiley & Sons, Ltd. [source] Ultrastructure of the ovary and oogenesis in six species of patellid limpets (Gastropoda: Patellogastropoda) from South AfricaINVERTEBRATE BIOLOGY, Issue 3 2000Alan N. Hodgson Abstract. The ultrastructural features of the ovary and oogenesis have been described in 6 species of patellid limpets from South Africa. The ovary is a complex organ that is divided radially into numerous compartments or lacunae by plate-like, blind-ended, hollow trabeculae that extend from the outer wall of the ovary to its central lumen. Trabeculae are composed of outer epithelial cells, intermittent smooth muscle bands, and extensive connective tissue. Oocytes arise within the walls of the trabeculae and progressively bulge outward into the ovarian lumen during growth while partially surrounded by squamous follicle cells. During early vitellogenesis, the follicle cells lift from the surface of the underlying oocytes and microvilli appear in the perivitelline space. Follicle cells restrict their contact with the oocytes to digitate foot processes that form desmosomes with the oolamina. When vitellogenesis is initiated, the trabecular epithelial cells hypertrophy and become proteosynthetically active. Yolk synthesis involves the direct incorporation of extraoocytic precursors from the lumen of the trabeculae (hemocoel) into yolk granules via receptor-mediated endocytosis. Lipid droplets arise de novo and Golgi complexes synthesize cortical granules that form a thin band beneath the oolamina. A fibrous jelly coat forms between the vitelline envelope and the overlying follicle cells in all species. [source] Synthesis and self-assembly of polystyrene-grafted multiwalled carbon nanotubes with a hairy-rod nanostructureJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2006Yingkui Yang Abstract Polystyrene-grafted multiwalled carbon nanotubes (PS- g -MWNTs) with a hairy-rod nanostructure were synthesized by the in situ free-radical polymerization of styrene in the presence of multiwalled carbon nanotubes (MWNTs) terminated with vinyl groups. To quantitatively study the molecular weight and composition of polystyrene (PS) chains in PS- g -MWNTs, PS- g -MWNTs were fully defunctionalized by hydrolysis. The results showed that 1 of every 100 carbon atoms in MWNTs was functionalized at the tips and outer walls of the carbon nanotubes and grafted by PS with a weight-average molecular weight of 9800 g/mol; therefore, a uniform thin layer (ca. 8,10 nm) of a PS shell was formed on the outer wall of MWNTs. PS- g -MWNTs were soluble in dimethylformamide and tetrahydrofuran. The thermal stability and glass-transition temperature of PS in PS- g -MWNTs were obviously increased. Nanopins were formed on the glass substrates by the self-assembly of PS- g -MWNTs, and the dewetting effect between the glass substrate and PS chains covered MWNTs during the evaporation of the solution. Both the length and diameter of the nanopins increased with the solution concentration. When PS- g -MWNTs were compression-molded, MWNTs were dispersed uniformly in the PS matrix and formed good networks, such as circlelike and starlike structures, because of the entanglements of hairy PS chains on MWNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3869,3881, 2006 [source] The Effects of Containment on Detonation VelocityPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2004Clark Souers Abstract Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70,,s,1. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For Us/Co,1.2, where Us is the detonation velocity and Co the zero-pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump-off. For Us/Co,1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The Us/Co,1.2 cylinders saturate in detonation velocity for thick walls but the Us/Co<<1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15,0.5 power. [source] A subtilisin-like serine protease essential for mucilage release from Arabidopsis seed coatsTHE PLANT JOURNAL, Issue 3 2008Carsten Rautengarten Summary During Arabidopsis seed development large quantities of mucilage, composed of pectins, are deposited into the apoplast underneath the outer wall of the seed coat. Upon imbibition of mature seeds, the stored mucilage expands through hydration and breaks the outer cell wall that encapsulates the whole seed. Mutant seeds carrying loss-of-function alleles of AtSBT1.7 that encodes one of 56 Arabidopsis thaliana subtilisin-like serine proteases (subtilases) do not release mucilage upon hydration. Microscopic analysis of the mutant seed coat revealed no visible structural differences compared with wild-type seeds. Weakening of the outer primary wall using cation chelators triggered mucilage release from the seed coats of mutants. However, in contrast to mature wild-type seeds, the mutant's outer cell walls did not rupture at the radial walls of the seed coat epidermal cells, but instead opened at the chalazal end of the seed, and were released in one piece. In atsbt1.7, the total rhamnose and galacturonic acid contents, representing the backbone of mucilage, remained unchanged compared with wild-type seeds. Thus, extrusion and solubility, but not the initial deposition of mucilage, are affected in atsbt1.7 mutants. AtSBT1.7 is localized in the developing seed coat, indicating a role in testa development or maturation. The altered mode of rupture of the outer seed coat wall and mucilage release indicate that AtSBT1.7 triggers the accumulation, and/or activation, of cell wall modifying enzymes necessary either for the loosening of the outer primary cell wall, or to facilitate swelling of the mucilage, as indicated by elevated pectin methylesterase activity in developing atsbt1.7 mutant seeds. [source] Possible Molecular Evolution of Biomembranes: from Single-Chain to Double-Chain LipidsCHEMISTRY & BIODIVERSITY, Issue 5 2007Mari Gotoh Abstract We have studied a possible evolution process permitting a ,primitive' membrane to evolve towards a membrane structure with an outer wall, similar to that of bacteria. We have investigated whether a polysaccharide bearing hydrophobic phytyl or cholesteryl chains coats giant vesicles made of single- or double-chain lipids. Phytyl-pullulan 5b was found to bind to the surface of vesicles made of either single- or double-chain lipids. In contrast, cholesteryl-pullulan 5a only coated the surface of vesicles made of double-chain lipids. These results indicate that there must be a close match between the size and shape of membrane constituents and the hydrophobic molecules to be inserted. This process could, thus, provide a selection mechanism of lipid-membrane constituents during the course of biomembrane evolution. The presence of the above ,hydrophobized' polysaccharides on the surface of different giant vesicles was identified by lectin binding. Both concanavalin A and annexin V were shown by fluorescence microscopy to bind spontaneously to vesicles made of double-chain lipids. Our experiments exemplify that self-organization of amphiphiles into closed vesicles in aqueous solution automatically leads to the coating of vesicles by ,hydrophobized' polysaccharides, which then permit lectin binding. This is a possible mechanism for the evolution of primitive membranes towards ,proto-cells'. [source] Template Synthesis of Aligned Carbon Nanotube Arrays using Glucose as a Carbon Source: Pt Decoration of Inner and Outer Nanotube Surfaces for Fuel-Cell Catalysts,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2008Zhenhai Wen A facile method is developed to synthesize aligned arrays of open-ended carbon nanotubes (CNTs) via in situ glucose polymerization in the inner pores of anodic aluminum oxide templates under hydrothermal conditions, followed by carbonization at high temperature. Pt nanoparticles are decorated on the surfaces of the as-prepared CNTs using the incipient wet method based on the use of NaBH4 as a reductant. Characterization of the resulting structures by transmission electron microscopy and field-emission scanning electron microscopy demonstrates that the Pt nanoparticles are anchored on both the inner and outer walls of CNTs, thus giving rise to a shell,core,shell-like nanotube composite. The electrocatalytic properties of the Pt,CNT,Pt electrodes are investigated for methanol oxidation by cyclic voltammetry and chronoamperometric measurements. It is found that the hybrid electrodes show superior catalytic performance compared to commercial carbon-black-supported Pt. The increased catalytic efficiency of Pt might be a result of the unique morphology of these structures. [source] Large eddy simulation of turbulent concentric annular channel flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2004Nan-Sheng Liu Abstract Fully developed turbulent concentric annular channel flow has been investigated numerically by use of large eddy simulation (LES) technique coupled with a localized one-equation dynamic subgrid-scale (SGS) model. The objective of this study is to deal with the behaviour of turbulent flow near the inner and outer walls of the concentric annular channel and to examine the effectiveness of LES technique for predicting the turbulent flow influenced by the transverse curvature effect. The computations are performed for the Reynolds number Re,=180, 395 and 640, based on an averaged friction velocity and the annular channel width with the inner and outer cylinder radius being Ri=1 and Ro=2. To validate the present approach, calculated results for turbulent pipe flow and concentric annular channel flow are compared with available experimental data and direct numerical simulation results, which confirms that the present approach can be used to study turbulent concentric annular channel flow satisfactorily. To elucidate turbulence characteristics in the concentric annular channel, some typical quantities, including the resolved velocity, turbulence intensity, turbulent eddy viscosity, SGS kinetic energy, SGS dissipation rate, Reynolds stress budgets, and turbulence structures based on the velocity fluctuations, are analysed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Experimental investigation into cavity-type inertial separators,a novel technique for development of subcompact circulating fluidized bed boilersINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2005Animesh Dutta Abstract Cavity-type inertial separators developed by GRI (Patent no. 2, 159, 949, Canada, 2002) were tested in a semi-industrial size circulating fluidized bed pilot plant operated at room temperature. Three rows of separators were hung from the roof of the pilot plant where one row was kept inside the riser and the others were kept in the primary separation chamber, located between the back-pass and the riser. Parameters measured were axial pressure drops along the height of the riser, vertical solids flux on the separator walls, lateral outwards solids flux in the riser with and without separator and local temperatures on the separator walls. A net downwards solids flux is on the inner wall of the separators; however, no downwards solids flux is on the outer walls of the separators. Heat transfer coefficients on the outer wall are found higher than those on the inner walls of the separator. It is also found that the presence of inertial separators not only provides additional heat transfer surfaces but also indirectly increases the heat transfer coefficients on the riser wall. Copyright © 2005 John Wiley & Sons, Ltd. [source] A numerical study of mixing in a microchannel with circular mixing chambersAICHE JOURNAL, Issue 9 2009Mubashshir Ahmad Ansari Abstract The mixing of fluids in a microchannel is numerically investigated using three-dimensional Navier,Stokes equations. The microchannel has circular mixing chambers that are designed to create a self-circulating flow that operates at low Reynolds numbers. The investigations have been performed on a design that comprises of four circular mixing chambers that are joined together with constriction channels. The study has been carried out in two parts. Firstly, the mixing and the flow field are analyzed for a wide range (1,250) of the Reynolds number. Secondly, the effects of two design parameters, namely, the ratio, w/d, of the width of the constriction channel to the diameter of the circular chamber, and the angle, ,, between the outer walls of the chamber and the connection channel, on the mixing and the flow field have been evaluated. The mixing has been evaluated using a parameter, called mixing index, which is based on the variance of the mass fraction. The mixing index at the end of the device increases rapidly with the Reynolds number. The presence of a flow recirculation zone in the circular chamber is found to be effective in enhancing mixing, especially for larger Reynolds numbers. The mixing performance improves with an increase in ,, and with a decrease in w/d. The characteristics of the pressure drop have also been investigated as a function of the Reynolds number and geometric parameters. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis and self-assembly of polystyrene-grafted multiwalled carbon nanotubes with a hairy-rod nanostructureJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2006Yingkui Yang Abstract Polystyrene-grafted multiwalled carbon nanotubes (PS- g -MWNTs) with a hairy-rod nanostructure were synthesized by the in situ free-radical polymerization of styrene in the presence of multiwalled carbon nanotubes (MWNTs) terminated with vinyl groups. To quantitatively study the molecular weight and composition of polystyrene (PS) chains in PS- g -MWNTs, PS- g -MWNTs were fully defunctionalized by hydrolysis. The results showed that 1 of every 100 carbon atoms in MWNTs was functionalized at the tips and outer walls of the carbon nanotubes and grafted by PS with a weight-average molecular weight of 9800 g/mol; therefore, a uniform thin layer (ca. 8,10 nm) of a PS shell was formed on the outer wall of MWNTs. PS- g -MWNTs were soluble in dimethylformamide and tetrahydrofuran. The thermal stability and glass-transition temperature of PS in PS- g -MWNTs were obviously increased. Nanopins were formed on the glass substrates by the self-assembly of PS- g -MWNTs, and the dewetting effect between the glass substrate and PS chains covered MWNTs during the evaporation of the solution. Both the length and diameter of the nanopins increased with the solution concentration. When PS- g -MWNTs were compression-molded, MWNTs were dispersed uniformly in the PS matrix and formed good networks, such as circlelike and starlike structures, because of the entanglements of hairy PS chains on MWNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3869,3881, 2006 [source] Reinforcement of Calcium Phosphate Cement by Bio-Mineralized Carbon NanotubeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2007Xiupeng Wang Bio-mineralized carbon natotubes (CNTs) were prepared by soaking carboxyl functionalized CNTs in a simulating body fluid (SBF). A uniform hydroxyapatite layer was precipitated on the outer walls of CNTs after 7 days of soaking. The results showed that, by addition of the as-received CNTs and bio-mineralized CNTs, the compressive strength of the calcium phosphate cement (CPC) increased by 24% and 120%, respectively. The modified interfacial bonding between the bio-mineralized CNTs and CPC accounted for the significant improvement in the mechanical property by addition of the bio-mineralized CNTs as compared with the as-received CNTs. [source] Biological Natural Retting for Determining the Hierarchical Structuration of Banana FibersMACROMOLECULAR BIOSCIENCE, Issue 10 2004Piedad Gañán Abstract Summary: Extraction processes of natural fibers can be performed by different procedures that include mechanical, chemical and biological methods. Each method presents different advantages or drawbacks according to the amount of fiber produced or the quality and properties of fiber bundles obtained. In this study, biological natural retting was satisfactorily used for obtaining banana fibers from plant bunches. However, the most important contribution of this work refers to the description of the hierarchical microstructural ordering present in banana fiber bundles in both bundle surface and inner region. The chemical composition of banana fiber bundles has been evaluated by FTIR spectroscopy. Through exposure time, the fiber bundle configuration presents small variations in composition. The main changes are related to hemicellulose and pectins as they conform the outer walls of the bundle. Hierarchical helicoidal ordering in the bundle surface as well as orientation on the longitudinal axis of the bundle were observed by optical microscopy (OM) and scanning electron microscopy (SEM) for 3,4 ,m surface fibers and 10,15 ,m inner elementary fibers, respectively. With increasing exposure time, fiber bundle walls lose integrity, as reflected in their mechanical behavior. [source] Silicification in sorghum (Sorghum bicolor) cultivars with different drought tolerancePHYSIOLOGIA PLANTARUM, Issue 1 2002Alexander Lux Sorghum belongs to a group of economically important, silicon accumulating plants. X-ray microanalysis coupled with environmental scanning electron microscopy (ESEM) of fresh root endodermal and leaf epidermal samples confirms histological and cultivar specificity of silicification. In sorghum roots, silicon is accumulated mostly in endodermal cells. Specialized silica aggregates are formed predominantly in a single row in the form of wall outgrowths on the inner tangential endodermal walls. The density of silica aggregates per square mm of inner tangential endodermal cell wall is around 2700 and there is no significant difference in the cultivars with different content of silicon in roots. In the leaf epidermis, silicon deposits were present in the outer walls of all cells, with the highest concentration in specialized idioblasts termed ,silica cells'. These cells are dumb-bell shaped in sorghum. In both the root endodermis and leaf epidermis, silicification was higher in a drought tolerant cultivar Gadambalia compared with drought sensitive cultivar Tabat. Silicon content per dry mass was higher in leaves than in roots in both cultivars. The values for cv. Gadambalia in roots and leaves are 3.5 and 4.1% Si, respectively, and for cv. Tabat 2.2 and 3.3%. However, based on X-ray microanalysis the amount of Si deposited in endodermal cell walls in drought tolerant cultivar (unlike the drought susceptible cultivar) is higher than that deposited in the leaf epidermis. The high root endodermal silicification might be related to a higher drought resistance. [source] Comparative anatomy and systematics of Catasetinae (Orchidaceae)BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2001WILLIAM LOUIS STERN FLS Catasetinae consist of five genera of pseudobulbous Orchidaceae of the Neotropics. Anatomy is characterized by sunken, three-celled foliar hairs, mostly tetracytic stomatal apparatuses, superficial stomata, homogeneous mesophyll, foliar fibre bundles, collateral vascular bundles in a single row, xylem and phloem sclerenchyma associated with vascular bundles in leaves, conical, and rough-surfaced silica bodies adjacent to vascular bundle sclerenchyma; epidermal cells of pseudobulbs with heavily thickened outer walls, pseudobulb ground tissue of assimilatory and water-storage cells, scattered vascular bundles in pseudobulbs, and sclerenchyma and stegmata associated only with phloem of pseudobulbs; roots with thin-walled velamen cells and tenuous spirals of cell wall material, distinctive epivelamen cells, thin-walled exodermal cells and vascular tissue embedded in parenchyma. Except for mucilaginous idioblasts that occur in Mormodes and Cycnoches, there are few outstanding anatomical differences among the five genera. Thus, there are few anatomical characteristics of phylogenetic value. The monophyly of Catasetinae is supported by the presence of sunken foliar hairs. Our results support a close relationship between Clowesia and Catasetum, and between Mormodes and Cycnoches. Among the outgroups Pteroglossaspis is especially distinctive. [source] | |||||||||||||||||||