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The family Nymphaeaceae includes most of the diversity among the ANA‐grade angiosperms. Among the species of this family, floral structures and pollination strategies are quite varied. The genus Victoria, as well as subgenera Lotos and Hydrocallis in Nymphaea, presents night‐blooming, scented flowers pollinated by scarab beetles. Such similar pollination strategies have led to macromorphological similarities among the flowers of these species, which could be interpreted as homologies or convergences based on different phylogenetic hypotheses about the relationships of these groups. We employed SEM of floral epidermis for seven species of the Nymphaeaceae with contrasting pollination biology to identify the main characters of the floral organs and the potential homologous nature of the structures involved in pollinator attraction. Moreover, we used TEM to observe ultrastructure of papillate‐conical epidermis in the stamen of Victoria cruziana. We then tested the phylogenetic or ecological distribution of these traits using both consensus network approaches and ancestral state reconstruction on fixed phylogenies. Our results show that the night‐blooming flowers present different specializations in their epidermis, with Victoria cruziana presenting the most elaborate floral anatomy. We also identify for the first time the presence of conical‐papillate cells in the order Nymphaeales. The epidermal characters tend to reflect phylogenetic relationships more than convergence due to pollinator selection. These results point to an independent and parallel evolution of scarab pollination in Nymphaeaceae, and show the promise of floral anatomy as a phylogenetic marker. Moreover, they indicate a degree of sophistication in the anatomical basis of cantharophilous flowers in the Nymphaeales that diverges from the most simplistic views of floral evolution in the angiosperms. This article is protected by copyright. All rights reserved.

† Background and Aims In the sexually deceptive Ophrys genus, species isolation is generally considered ethological and occurs via different, specific pollinators, but there are cases in which Ophrys species can share a common pollinator and differ in pollen placement on the body of the insect. In that condition, species are expected to be reproductively isolated through a pre-mating mechanical barrier. Here, the relative contribution of pre- vs. post-mating barriers to gene flow among two Ophrys species that share a common pollinator and can occur in sympatry is studied. † Methods A natural hybrid zone on Sardinia between O. iricolor and O. incubacea, sharing Andrena morio as pollinator, was investigated by analysing floral traits involved in pollinator attraction as odour extracts both for non-active and active compounds and for labellum morphology. The genetic architecture of the hybrid zone was also estimated with amplified fragment length polymorphism (AFLP) markers, and pollination fitness and seed set of both parental species and their hybrids in the sympatric zone were estimated by controlled crosses. † Key Results Although hybrids were intermediate between parental species in labellum morphology and nonactive odour compounds, both parental species and hybrids produced a similar odour bouquet for active compounds. However, hybrids produced significantly lower fruit and seed set than parental species, and the genetic architecture of the hybrid zone suggests that they were mostly first-generation hybrids. † Conclusions The two parental species hybridize in sympatry as a consequence of pollinator overlap and weak mechanical isolation, but post-zygotic barriers reduce hybrid frequency and fitness, and prevent extensive introgression. These results highlight a significant contribution of late post-mating barriers, such as chromosomal divergence, for maintaining reproductive isolation, in an orchid group for which pre-mating barriers are often considered predominant.

• Background and Aims Pollen characters have been widely used in defining evolutionary trends in orchids. In recent years, information on pollination biology and phylogenetic patterns within Orchidinae has become available. Hence, the aim of the presented work is to re-evaluate exine micromorphology of Orchidinae in light of recent phylogenetic studies and to test whether pollen micromorphology strictly depends on phylogenetic relationships among species or whether it is influenced by the marked differences in pollination ecology also reported among closely related species. • Methods Pollen sculpturing of 45 species of Orchidinae and related taxa was investigated using scanning electron microscopy. To cover potential intraspecific variation, several accessions of the same species were examined. • Key Results Orchidinae show remarkable variation in exine sculpturing, with a different level of variation within species groups. In some genera, such as Serapias (rugulate) and Ophrys (psilate to verrucate), intrageneric uniformity corresponds well to a common pollination strategy and close relationships among species. However, little exine variability (psilate–scabrate and scabrate–rugulate) was also found in the genus Anacamptis in spite of striking differences in floral architecture and pollination strategies. A larger variety of exine conditions was found in genera Dactylorhiza (psilate, psilate–scabrate and reticulate) and Orchis s.s. (psilate, reticulate, perforate–rugulate and baculate) where no unequivocal correspondence can be found to either phylogenetic patterns or pollination strategies. • Conclusions Changes in pollen characteristics do not consistently reflect shifts in pollination strategy. A unique trend of exine evolution within Orchidinae is difficult to trace. However, the clades comprising Anacamptis, Neotinea, Ophrys and Serapias show psilate to rugulate or scabrate pollen, while that of the clade comprising Chamorchis, Dactylorhiza, Gymnadenia, Orchis s.s., Platanthera, Pseudorchis and Traunsteinera ranges from psilate to reticulate. Comparison of the data with exine micromorphology from members of the tribe Orchidieae and related tribes suggests a possible general trend from reticulate to psilate.

A model is developed for heat transfer, polymer vaporization, and gas diffusion at the interface between the advancing liquid metal and the receding foam pattern during mold filling in lost foam casting of aluminum. Most of the pattern interior decomposes by ablation, but the boundary cells decompose by a collapse mechanism, which creates an undercut in the pattern next to the coating. By regulating how much of the pattern coating is exposed to gas diffusion, the undercut controls the overall filling speed of the metal through the mold. Computed values for the foam decomposition energy from this model compare very well with experimental data on foam pyrolysis, and predicted filling speeds are consistent with observations in published experiments. In addition, the model explains several unusual observations about mold filling that until now have not been understood.

A new approach is developed for analyzing liquid metal flow in die casting which, compared with conventional methods, greatly shortens the time required to calculate a solution. Instead of modeling the usually thin die casting cavity as a general three-dimensional fluid region, the governing equations are integrated through the cavity thickness, creating an equivalent two-dimensional theory that describes the motion of the liquid metal in terms of a bulk velocity and a pressure resultant. The liquid metal is represented as an inviscid, incompressible fluid. This makes it possible to introduce a two-dimensional velocity potential on the cavity surface and avoid an explicit solution for pressure. The arbitrary jump in potential that may occur when two flow fronts meet is accommodated by using discontinuous finite elements. The cavity gas displaced by the advancing metal front is assumed to compress adiabatically as an ideal gas. The method allows for generally curved, branched cavities, venting of the cavity gas, energy dissipation at gates, and a variable injection speed. A number of example problems are considered which illustrate the performance of the analysis under several geometric and process conditions.

Light and scanning electron microscopy were utilised to study stoma and cuticle morphology whereas transmission electron microscopy was used to observe plastid ultrastructure in Ceratozamia kuesteriana Regel (Zamiaceae). Results show that in G kuesteriana a diperigenous‐type stoma (or a derivation of a diperigenous type) occurs and that protein crystalloids and prolamellar bodies are simultaneously present in the chloroplast.

Thermal expansion of the part can be a significant source of dimensional and form errors in precision machining operations. This paper describes a method for calculating the thermal expansion of an axisymmetric workpiece. The analysis is based on a commercially available boundary element code modified to properly represent concentrated moving heat sources such as those produced in machining. The inputs required are the amount of heat entering the part from the cutting zone and the thermal properties of the workpiece material. Calculations are compared with direct measurements of expansion from tests on large diameter 2024 aluminum sleeves. The agreement between calculated and measured values is generally reasonable, although calculated expansions are consistently smaller than measured expansions. This error is probably due to errors in estimating the heat input to the part, and particularly the neglect of flank friction in heat input calculations. Sample calculations for hard turning of a wheel spindle show that expansions can approach tolerances on critical surfaces. Based on sample calculations, thermal expansion is likely to be significant when hard turning parts with tolerances on the order of 0.01 mm. For these applications, critical surfaces should be machined first, before cuts on other sections heat the part, and gaging should be carried out only after the part has cooled.

A new approach is developed for solving the initial value, steady periodic heat conduction problem in steady-state die casting. Three characteristics found in nearly all die casting processes are exploited directly: The casting is thin compared with its overall size, its thermal conductivity is high compared with that of the mold, and the cycle time is short compared with the start-up transient of the process. Under these conditions, it is reasonable to neglect the transverse temperature gradients in the casting and assume that all die temperatures below a certain depth from the cavity surface are independent of time. The transient die temperatures near the cavity surface are represented by a polynomial expansion in the depth coordinate, with time-varying coefficients determined by a Galerkin method. This leads to a set of ordinary differential equations on the cavity surface, which govern the transient interaction between the casting and the die. From the time-averaged solution of these equations, special conditions are derived that relate the transient solution near the cavity surface to the three-dimensional steady solution in the die interior. With these conditions, the steady temperatures in the bulk of the die can be determined independently of the explicit surface transients. This reduces the effort of solving a complex transient heat conduction problem to little more than finding a steady solution alone. The overall approach provides a general analytical tool, which is capable of predicting complex thermal interactions in large multicomponent dies.

To try to understand the causative role of epilepsy PER SE in the developmental deterioration of brain injured infants, twenty-eight infants affected with early acquired, pre- and perinatal brain injuries were enrolled and divided into three groups, a) those with West syndrome, b) those with other non-West epilepsies, and c) those without epilepsy. Developmental monitoring consisted of a full clinical assessment, including examination of visual function, Griffiths developmental scales, standard EEG, long-term monitoring when necessary, and MRI, from the seizure onset or the first observation to the end of follow-up. Patients with epilepsy showed at study onset abnormal clinical features (neurological and developmental) distinct from those of non-epileptic patients, partially due to the varying severity of their brain injuries. A definite differentiation between groups was observed in the clinical evolution that showed among the epileptic patients, mostly in West syndrome, a significant deterioration. Moreover, impaired visual function at seizure onset was possibly associated with a bad developmental evolution. A developmental deterioration, mostly in West syndrome, accounts for a causative role of the epileptic disorder PER SE, but in few cases it was also observed in infants with only a brain injury, suggesting other aetiopathogenic mechanisms. The predictive value of early visual function seems to be confirmed.

Models reproducing plant structures used for educational purposes at the Botanical Garden of Naples in the 19th century have been recently recovered from a state of partial abandonment, assembled and exposed. The models together with illustrative panels have been placed in showcases in the classrooms of the Botanical Garden of Naples and of the department of Biology at University of Naples Federico II. Moreover, models have been presented in a multimedia cd-rom that allows to improve their valorisation and fruition. For each species reproduced in the models, the cd-rom shows photos in the field of plants cultivated in the Botanical Garden of Naples. the images are accompanied by explanatory texts to make easier the understanding of the illustrated models and the identification of the plants.

A method has been developed for calculating hydraulic pressures induced by thermal expansion of liquid binders early in the removal cycle, when evaporative losses are negligible and fully saturated conditions prevail. Specific results were obtained for flat compacts containing a common wax binder, mixed with varying amounts of low-density polyethylne. In general, these results show how the risk of hydraulic fracture increases with heating rate and compact thickness. Although pressures are minimal when the binder consists entirely of wax, the continual addition of polyethylene eventually gives rise to unacceptable risk levels, even for relatively thin compacts. Binder removal at elevated temperatures is considered subsequently. In this case, vapor pressures eventually approach a critical level, thereby allowing mass removal by evaporation to overcome the effect of thermal expansion in maintaining full saturation. With the onset of void formation, the developing capillary pressure supersedes hydraulic pressure as the driving force in liquid transport. Besides representing capillary flow, the present formulation also accounts for thermal degradation of the binder during removal. The resulting system of equations was solved numerically for a variety of representative debinding conditions. Predictions for flat compact containing a balanced wax/polyethylene binder indicate that thermal degradation of the polyethylene can give rise to a marked improvement in debinding rates. It turns out, however, that this enhancement is far more effective in thinner compacts.

Experiments utilizing charges constructed of black and white sheet molding compound (SMC) reveal the basic kinematic mechanisms controlling the flow of the fiber-filled compound in compression molding. The experimental results show that SMC deforms in uniform extension within individual charge layers, with slip occurring at the mold surface and, for slower closing speeds, also between the layers of SMC. When the mold closes rapidly, the charge extends uniformly through its thickness, with all slip concentrated at the mold surface.

A production sheet molding compound (SMC) mold for an automotive hood outer panel was instrumented with 64 thermocouples to measure cavity surface temperatures along two cross-sections in each mold half and regulate the supply of steam to each heating line. The positions and temperatures of each heating line in the mold were optimized using an in-house computer program to produce a minimum spatial variation in cavity surface temperature during steady cyclic molding. Provision was also made to heat the mold conventionally so that optimal and conventional heating could be directly compared in the same mold. While maintaining a 78 s overall molding cycle, the conventional heating system eventually produced a 10°C temperature variation on the cavity surface. This, in turn, led to serious resin undercure and severe difficulties in removing the part from the mold. When the optimal heating design was substituted in place of the conventional system, the surface temperature variation was reduced to less than 3°C and the problems experienced with conventional heating disappeared. For the most part, the measured temperatures in these experiments agreed with the results of the computer analysis to within 1°C.

Thin sections, lanthanum tracer and the freeze-fracture technique revealed the presence of different types of cell junctions in early sea urchin (Paracentrotus lividus) embryos. During the first four cleavage cycles, which are characterized by synchrony of cell division, sister blastomeres were connected only by intercellular bridges, formed as a result of incomplete cytokinesis; no trace of other junctions was found at these stages. From the 16-cell stage onwards, septate junctions and gap junctions began to appear between blastomeres. It is postulated that cell-cell interactions may provide a mechanism for the propagation of signals necessary for the coordination of cell proliferation and differentiation.

A new formulation for obtaining design sensitivities in shape optimization has been developed. The formulation is based on a direct application of the material derivative concept to the appropriate boundary integral equations for displacements and stresses in an elastic solid. As a check on accuracy, the approach was applied to a uniformly loaded infinite plate containing an elliptical hole. In this case, the availability of an analytical solution made it possible to calculate errors exactly. Furthermore, a wide range of stress states could be considered simply by varying the aspect ratio of the elliptical hole. For convenience, the design sensitivities were calculated with respect to changes in the major axis. Numerical convergence was established by comparing results based on four successive boundary meshes. In general, the predictions for both displacement and stress sensitivities were remarkably accurate.

A boundary element formulation for design sensitivities has been developed for application in three-dimensional shape optimization of elastic solids. Both displacement and stress sensitivities can be determined, at any stage of the design process, by relatively straightforward numerical integration procedures. Further simplification in calculating displacement sensitivities is accomplished by using a special rigid-body integral identity to remove singularities. The issue of accuracy was addressed by analyzing the problem of an infinite elastic solid with a triaxial ellipsoidal cavity. It turns out that this test case is considerably more general than the usual axisymmetric examples employed in prior elastostatic error analyses. Furthermore, the stress concentration can be increased indefinitely by decreasing the two aspect ratios that define the cavity surface. More importantly, the availability of an analytical solution makes it possible to obtain an exact measure of error. For completeness, stresses and stress sensitivities were obtained for three progressively eccentric cavity shapes, using three different singular integration schemes. Generally, the numerical predictions and exact results were in excellent agreement. In the worst case, with a stress concentration of about 4.1, the best stress sensitivity prediction was within 2 percent of the exact value. This is remarkably accurate, given that the corresponding cavity model consisted of only twelve elements per octant.

This paper concerns heat conduction in a chopped-fiber reinforced polyester resin during compression molding of thin sheet-like parts. Since the resin generates heat as it cures, the general boundary value problem involves a deforming heat conductor which reacts chemically. The randomly woven fiber structure in the sheet molding compound (SMC) motivates a kinematical assumption on the material deformation in the mold cavity. The resulting description of the deformation field is then used to formulate a boundary value problem for the temperature distribution in the deforming SMC in terms of coordinates that move with the material. From the solution to this problem we derive a general expression in closed form for the nonuniform distribution of heat energy absorbed from the mold surface as each part is molded. The exothermic cure reaction in the polyester resin, which begins after the mold closes, is characterized in terms of heat generated in the SMC. Numerical analysis of the transient distribution of temperature and cure shows how the degree of coupling between heat conduction and cure depends on the thickness of the molded sheet. The results of the analysis also determine the effect of sheet thickness and mold temperature on cure time, subject to limitations of thermal degradation.

In this paper, minimum-weight design of double-layer panels made from sheet molding compound is related to cure time—a critical indicator of manufacturing cost. This is done by incorporating cure time restrictions in the optimization analysis. Depending on the design constraints imposed on the panel, the least-weight design can require cure times which are unacceptably long for economical high volume production. Nevertheless, we show that cure time can be brought within acceptable bounds by design changes that incur only modest increases in weight.

Dans les processus de formage qui necessite un echange de chaleur entre un dispositif de fixation permanent et le materiau etant soumis au formage, le moule ou matrice doit normalement etre chauffe ou refroidi par des ouvertures circulaires internes. Pour concevoir la localisation de ces ouvertures, il faut pouvoir calculer les temperatures dans le moule ou la matrice, et il faut calculer le potentiel electrique entourant une configuration tridimensionnelle des conducteurs elances. Presentation d'une methode de calcul dans ce but

Since the cure rate of injection molded thermosets is usually very sensitive to cavity surface temperature, spatial variations in these temperatures can lengthen the necessary cure time for the entire part and cause distortion and residual stress in the molded article. This problem is addressed in the present paper by combining an optimization algorithm with a quasi-steady heat conduction analysis in the mold to determine the heating line positions and operating temperatures that minimize the spatial variation in cavity surface temperature. The method is applied to an example mold for a flat panel of uniform thickness, using two different gate locations. At a one-minute cycle, the optimal designs for each gate location dramatically reduce the variation in cavity surface temperature compared with corresponding results using a conventional heating system. These results are made more significant by the fact that the optimal designs use considerably fewer heating lines. In spite of their simplicity, the optimal designs still have enough flexibility to adjust to a changing cycle without sacrificing uniformity in cavity surface temperature.

The flow of a chopped fiber reinforced polymer compound in compression molding is modelled as a two-dimensional membrane-like sheet which extends uniformly through the cavity thickness with slip at the mold surface. The model is consistent with both the kinematic mechanisms observed in actual flow and the three-dimensional anisotropy caused by the arrangement of fibers in the sheet. The material resistance to extension is expressed in a constitutive equation for the two-dimensional stress resultant formed by integrating the planar stress components through the thickness of the cavity. This stress resultant is assumed to be a linear function of the corresponding planar rate of deformation in the molding compound. Through a mechanism of fiber-resin interaction, the material resistance to extension can be characterized by a single scalar function of the transverse temperature distribution. Three alternatives are considered for the friction response at the cavity surface: (i) constant magnitude, (ii) proportional to the relative velocity (hydrodynamic), and (iii) proportional to the normal component of the stress vector (Coulomb). These three assumptions are compared by considering their general implications on the flow-front progression. The latter two are examined in some detail for thin charges in which the material resistance to extension is negligible compared to the effect of friction. Analytical solutions for an elliptical charge are obtained for both hydrodynamic and Coulomb friction. By comparing these solutions with experimental results, we conclude that the hydrodynamic model for the friction response is the best of the three proposed alternatives.

An integral equation method is presented which permits evaluation of stress and displacement fields in two-dimensional elastic solids near corners and notches. The procedure begins by using well known expressions of an asymptotic character for the fields near the points in question. Unknown coefficients, one of which will be a stress intensity factor in the case of a cracked plate, are treated as generalized displacements. Suitable test solutions are developed to express the generalized displacements in terms of integrals involving far-field quantities. Sample numerical solutions are presented for notched and cracked plates.