Small Protuberances Research Articles

Adhesive structures in the eggs of Corydoras aeneus(Gill, 1858; Callichthyidae)

The surface structure of the eggs of the catfish Corydoras aeneus was examined and showed to be a unique pattern among teleosts. The surface was covered with small protuberances, which resemble attaching‐filaments of teleost eggs. Eggs were, however, found to be very adhesive and since the species is known to inhabit turbid waters, this rare egg attachment mode could well be related to these environmental conditions.

A Revision of the Genus Parastilomysis (Mysida: Mysidae), with Descriptions of Three New Species and Establishment of a New Genus for P. Secunda

Abstract Three new species of Parastilomysis, P. paucispina, P. prominula, and P. separata, are described from Japanese waters. Parastilomysis paucispina is different from the other species of the genus by the smaller body size and the uropodal endopod with the inner margin armed with fewer spines, P. prominula by two small protuberances on the mid-dorsal line of the carapace, and P. separata by the arrangement of spines on the lateral margin of the telson. Parastilomysis secunda is revised taxonomically, and a new genus, Hyperstilomysis, is proposed for the accommodation of this species.

Growth of nordstrandite: effect of carboxylates on surface morphology

We studied the effect of carboxylates on the crystallization of nordstrandite precipitated from ethylenediamine solutions by examining the nanometer scale step structure of the basal faces with atomic force microscopy (AFM). The crystals grown in the presence of carboxylates are more rounded in shape than those grown without added carboxylates, with irregular growth in the direction perpendicular to the basal faces and small protuberances from the crystals. AFM images show monolayer steps on the surfaces of the crystals. These steps are composed of straight segments down to a horizontal resolution of a few nanometers. A survey of the step segments showed that the steps formed in the presence of carboxylates have shorter segments. For the crystals grown in the control solutions, two-dimensional nucleation is evident in a few places on the surfaces, and concentric terraces are present in many cases. For the crystals grown in carboxylate solutions, two-dimensional nucleation had occurred more randomly and evenly on the surfaces, with smaller nuclei. These differences in step morphology are due to the adsorption of the carboxylates at the steps, which affected the step edge surface energy.

Laboratory evidence of natural remobilization of multicomponent DNAPL pools due to dissolution

Mixtures of dense non-aqueous phase liquids (DNAPLs) trapped in the subsurface can act as long-term sources of contamination by dissolving into flowing groundwater. In general, the components of higher solubility are removed more quickly, thus altering the composition of the remaining DNAPL, and possibly leading to changes in its physical properties. Through the development of a simple compositional model, Roy et al. [J. Contam. Hydrol. 2002 (59) 163] showed that preferential dissolution of a mixed DNAPL could potentially result in changes in density and interfacial tension that could subsequently lead to remobilization of an initially static DNAPL pool. The laboratory experiments presented in this next paper provide a proof-of-concept for the previously presented theory, demonstrating and quantifying this process of remobilization. In addition, the experiments provide a data set for evaluation of the model presented by Roy et al. [J. Contam. Hydrol. 2002 (59) 163]. In the four experiments, a DNAPL pool comprised of tetrachloroethene and benzene was created as an open pool overlying glass beads within a water-saturated 2-D flow box. Experiments included rectangular and triangular pools. In each of the experiments, remobilization (as breakthrough) was observed more than 2 weeks after formation of the initial pool. During each experiment, the pool height declined as mass was lost by dissolution, while sampling indicated a decrease in the mole fraction of benzene, the more soluble component. Small protuberances formed along the bottom of the pool as its composition changed with time and the displacement pressure was achieved for various pore throats. Eventually one of the protuberances extended further, forming a finger (breakthrough). In general, the pool emptied as the finger proceeded further into the beads. It was also shown theoretically and experimentally that remobilization will occur sooner for pools with a triangular (pointing down), rather than rectangular, shape. The experimental results were simulated using the model developed by Roy et al. [J. Contam. Hydrol. 2002 (59) 163]. The model matched the observations well, suggesting that it accurately represents the primary mechanisms involved with natural remobilization under the conditions of the study.

THE PERIDERM DEVELOPMENT IN QUERCUS SUBER

In the cork oak (Quercus suber L.), the phellogen differentiates during the first year of growth in the cell layer immediately under the epidermis and divides to form 3–6 suberized phellem cells. Division of the phellogen only occurs after suberization of the previous divided cell. During the first four years of growth, the phellem cells have tannin-filled lumens and it is only in the 5th to 7th years that they acquire the characteristics of ʻadultʼ cork cells with empty lumens and thin suberized walls. The lenticels are formed by the lenticular phellogen, which differentiates under the stomata and has a high meristematic activity. In this region, the cells are unsuberized, with a loose arrangement and intercellular voids, constituting the filling or complementary tissue. After three years, the lenticels appear as small protuberances that soon become conspicuous. Inclusions of sclerenchymatous nodules and isolated sclereids occur occasionally mostly in the vicinity of, or in, the lenticels.

Nectary structure and nectar secretion in Maxillaria coccinea (Jacq.) L.O. Williams ex Hodge (Orchidaceae).

It had previously been assumed that Maxillaria spp. produce no nectar. However, nectar has recently been observed in Maxillaria coccinea (Jacq.) L.O. Williams ex Hodge amongst other species. Furthermore, it is speculated that M. coccinea may be pollinated by hummingbirds. The aim of this paper is to investigate these claims further. Light microscopy, histochemistry, scanning and transmission electron microscopy. This is the first detailed account of nectar secretion in Maxillaria Ruiz & Pav. A 'faucet and sink' arrangement occurs in M. coccinea. Here, the nectary is represented by a small protuberance upon the ventral surface of the column and nectar collects in a semi-saccate reservoir formed by the fusion of the labellum and the base of the column-foot. The nectary comprises a single-layered epidermis and three or four layers of small subepidermal cells. Beneath these occur several layers of larger parenchyma cells. Epidermal cells lack ectodesmata and have a thin, permeable, reticulate cuticle with associated swellings that coincide with the middle lamella between adjoining epidermal cells. Nectar is thought to pass both along the apoplast and symplast and eventually through the stretched and distended cuticle. The secretory cells are collenchymatous, nucleated and have numerous pits with plasmodesmata, mitochondria, rough ER and plastids with many plastoglobuli but few lamellae. Subsecretory cells have fewer plastids than secretory cells. Nectary cells also contain large intravacuolar protein bodies. The floral morphology of M. coccinea is considered in relation to ornithophily and its nectary compared with a similar protuberance found in the entomophilous species M. parviflora (Poepp. & Endl.) Garay. Flowers of M. coccinea produce copious amounts of nectar and, despite the absence of field data, their morphology and the exact configuration of their parts argue strongly in favour of ornithophily.

Surface functionalization and grafting of heparin and/or RGD by an aqueous-based process to a poly(carbonate-urea)urethane cardiovascular graft for cellular engineering applications.

An aqueous-based process is reported for surface functionalization and grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine-glycine- aspartate (RGD) onto the lumenal surface of a prefabricated cardiovascular graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2'-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink polymer. Following bonding, the graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p(3/2) states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO(3). RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective grafts postbonding remained within normal batch release limits (5 +/- 0.1mm, i.d.; 0.9 +/- 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane.

Material removal on lubricated steel gears with W-DLC-coated surfaces

The wear process that occurs in lubricated steel gears with thin, metal-containing diamond-like-carbon (Me-DLC) films deposited on the surface has been characterized using a variety of techniques that include the atomic force microscope and the focused ion beam imaging system. The profile of the tungsten-containing DLC (W-DLC) has been found to duplicate that of the original steel surface with peaks and valleys having amplitude up to 1 μm, superposed on a very thin (50 nm) Cr adhesion layer. Beneath the surface, imperfections are embedded in the steel. Wear occurs through the removal of the peaks by a polishing mechanism, leaving the valleys intact. When the peaks have been fully removed to create a plateau, the RMS roughness is approximately 35 nm. There are still pits corresponding to the original valleys up to 200 nm deep. When the remnant DLC becomes smaller than the amplitude of the peaks on the steel surface, the steel and the Cr adhesion layer become polished, causing the peaks to be eliminated, as well as the imperfections present in the subsurface. The resulting surface has RMS roughness with amplitude 25 nm, as well as small protuberances associated with the carbide particles in the steel.

Human horns: a historical review and clinical correlation.

Accounts of bony human horns originating from the cranium are found peppered throughout the early medical literature. This study reviews the extant literature regarding these entities to elucidate their authenticity. We reviewed both historical and current literature as well as osteological material from our anatomy laboratories for accounts or observations of bony outgrowths of the calvaria in humans. Human horns seem to be mentioned more frequently in the historical literature and are documented primarily with drawings. Moreover, from early accounts, it is often difficult to distinguish true large bony outgrowths from scalp excrescences. Only two cadaveric specimens from our laboratory were noted to have small anomalous bony protuberances, one on the occiput and one on the frontal bone. With the lack of either photographic or extreme dry specimen evidence of such human horns, we would propose that benign calvarial tumors, such as osteomas, may have initiated speculation that such entities, i.e., horns, exist in humans but that scalp lesions, exaggeration, legend, and religious beliefs have historically propagated these entities to a mythical status. In addition, early surgical intervention and changes in nomenclature may have also decreased the frequency of such sightings. Finally, many early descriptions have not been repeated in recent history, even in third-world countries lacking advanced medical care.

Barium Carbonate Phase on the Surfaces of Barium Titanate Particles and in Situ Transmission Electron Microscopy Observation of Its Decomposition

A BaCO3 phase is found on the surfaces of hydrothermally synthesized BaTiO3 particles; it occurs as aggregates or small protuberances. A small proportion of the phase decomposes to BaO crystallites when heated by a convergent electron beam in a transmission electron microscope. The BaO and BaCO3 crystallites disappear when they are irradiated successively by the convergent electron beam. The BaO crystallites and the BaCO3 phase sublimate and/or react with BaTiO3 crystals whose surface layers are deficient in Ba2+ ions.

Caracterização morfológica da semente e da plântula de bacurizinho (Rheedia acuminata (Ruiz et Pav.) Plachon et Triana - Clusiaceae)

O bacurizinho é uma espécie frutífera do gênero Rheedia, nativa da Amazônia, e raramente cultivada, pois seus frutos, embora comestíveis, apresentam polpa escassa. Os estudos com o bacurizinho visam a sua utilização como porta-enxerto, redutor de porte para outras espécies do gênero Rheedia e Garcinia que apresentam altura elevada, como o bacuripari (Rheedia macrophylla Planchon et Triana- Clusiaceae) e o mangostão (Garcinia mangostana L.). Este trabalho teve como objetivo caracterizar, morfologicamente, a semente e a plântula dessa espécie. A semente é exalbuminosa, bitegumentada, com a testa de coloração marrom, apresentando vários feixes vasculares bem visíveis, distinguindo-se por sua coloração um pouco mais clara. O hilo é arredondado, de coloração escura, com pequena região mais clara ao centro, correspondendo no ponto de entrada de feixe vascular. A micrópila situa-se próxima ao hilo, sobre uma pequena protuberância triangular. O embrião é anômalo, hipocotilar e é representado unicamente por um longo eixo hipocótilo-radícula, sendo os cotilédones diminutos, aparecendo apenas na extremidade superior no lado oposto da micrópila. Durante a germinação, ocorre primeiramente a emergência de delgada raiz primária, no pólo oposto onde será originado o epicótilo. Essa raiz cresce aproximadamente 5-7cm e cessa, fenecendo posteriormente. Por ocasião da emergência do epicótilo, ocorre ao mesmo tempo a formação de uma raiz adventícia, na base do epicótilo, bem mais robusta que a anterior e que se constituirá no sistema radicular da planta. Precedendo a abertura do primeiro par de metáfilos, desenvolvem-se no epicótilo três pares de catafilos opostos e de coloração esverdeada. A germinação é hipógea e a plântula do tipo criptocotiledonar.

Development of Valves in the Marine Diatom Genus Trigonium

Abstract Trigonium arcticum and T. formosum, marine diatoms epiphytic on Ectocarpus sp., were collected from the sublittoral off Point Loma, California. Forming valves of these two sympatric species were studied using scanning electron microscopy. The earliest developing valve of T. arcticum encountered is a porous basal layer of silica, triangular, with pseudocelli just starting to form at each corner. The central annulus, the site of the earliest valve formation, appears to be about the size of a single areola. Early rimoportulae (labiate processes) are interspersed between central areolae and are simple oval openings. Internally these form their labiate lip‐like structures just before cribrum formation. Ridges form on the external side of the basal layer in a honeycomb pattern and produce the walls of the loculate structures. The ridges expand outward until cribrum formation is initiated. Small protuberances grow out from the edge of the ridge‐like structures and then become anvil‐shaped as they grow toward the center of the pores and form the ‘roofs’ of the loculi. In external view of the mature valve, the pores are smoothly covered over except for a ring of C‐shaped slits. These cribra are flush with the surface of the valve. At about the time the cribra are completing, rotae are formed within the porelli of the pseudocelli by extensions from two or three sides. The quadrangular T. formosum develops along much the same pattern. Differences are the less numerous, more centrally located rimoportulae, which possess external tubes and the formation of highly domed cribra.

Differential approximations for transient radiative transfer through a participating medium exposed to collimated irradiation

First, we apply the modified differential approximation (MDA) suggested by Chandrasekhar to transient radiative transfer in a scattering planar medium exposed to collimated pulse irradiation. Next, a hybrid method of the P 1/3 approximation suggested by Olson and the MDA is developed. The hybrid method may be referred to as the modified P 1/3 approximation (MP 1/3A) and is also applied to the same example. Comparisons of the results obtained by solving the MDA, the MP 1/3A and the exact integral equation are made. The comparisons show that the temporal distribution of the transmissivity obtained by the MDA contains a small protuberance or an abrupt slope change, which decreases with the decrease of the scattering albedo. The results obtained by the MP 1/3A are more accurate than those obtained by the MDA for most of the cases considered, because the MP 1/3A corrects the propagation speed of the transmitted radiation.

Apocalmodulin and Ca2+-Calmodulin Bind to Neighboring Locations on the Ryanodine Receptor

Calmodulin (CaM) binds to the ryanodine receptor/calcium release channel of skeletal muscle (RyR1), both in the absence and presence of Ca(2+), and regulates the activity of the channel activity by activating and inhibiting it, respectively. Using cryo-electron microscopy and three-dimensional reconstruction, we found that one apoCaM binds per RyR1 subunit along the sides of the cytoplasmic assembly of the receptor. This location is distinct from but close to the location found for Ca(2+)-CaM, providing a structural basis for efficient switching of CaM between these two positions with the oscillating intracellular Ca(2+) concentration that generates muscle relaxation/contraction cycles. The locations of apoCaM and Ca(2+)-CaM at a critical region for RYR1-dihydropyridine receptor interaction are suggestive of a direct role for CaM in the mechanism of excitation-contraction coupling.

20-Hydroxyecdysone-induced differentiation and apoptosis in the Drosophila cell line, l(2)mbn

20-Hydroxyecdysone has an inhibitory effect on the proliferation of l(2)mbn cells, causes vacuolization and fragmentation of cells, and promotes a strong phagocytotic activity. From several lines of evidence, it can be concluded that 20-hydroxyecdysone induces apoptosis. Long-term video observations following the fate of individual cells, scanning and transmission electron microscopy reveal the typical characteristics of apoptosis: sequestration of small cellular protuberances or larger parts of the cell with nuclear fragments (apoptotic bodies), chromatin condensation, condensation and vesiculation of cytoplasm, whereas the mitochondria retain their normal appearance. The induction of apoptosis by 20-hydroxyecdysone was confirmed by the TUNEL reaction and quantitatively determined by a method based on this reaction. Onset of apoptosis precedes phagocytotic activity. JH III alone has no clear-cut effect on l(2)mbn cells. In double treatments, the inhibitory effect of 20-hydroxyecdysone on cell proliferation is significantly reduced by the addition of JH III. Whether or not JH III also reduces apoptotic activity is not yet clear. It is shown that the l(2)mbn cell line is an advantageous model system for the exploration of steroid-induced apoptosis.

Ceratal autotomy and regeneration in the aeolid nudibranch Phidiana crassicornis and the role of predators

Abstract. Ceratal autotomy by the aeolid nudibranch Phidinna crassicornis is common in the field and was induced in the laboratory by mechanical and predatory stimuli. The ceras detaches from the body wall along an autotomy plane located at its basal constriction. Cerata released copious amounts of mucus during autotomy and exhibited a prolonged writhing response that continued for several hours after detachment. Regeneration of cerata autotomized in the field and in the laboratory was documented. Four days after autotomy, regenerating cerata appeared as small protuberances. By day 24 the regenerates acquired their mature structural organisation and vivid colour. The cerata subsequently increased in length and diameter and were indistin‐guishable from surrounding cerata by 41 to 43 days after autotomy. Regeneration rates of cerata induced to autotomize in the laboratory and regeneration of cerata autotomized in the field were similar, averaging 0.08 and 0.067 mdday, respectively. The sequence of morphological events involved with regeneration following experimental and natural induction of autotomy was identical. The kelp crab Pugettia productn induced autotomy by holding cerata with its chelae. This crab also fed on autotomized cerata and consumed locomotory and ceratal mucus. Ceratal autotomy may be an important mechanism of escape from this predatory crustacean. Other potential predators including hermit crabs and tidepool sculpins did not elicit defensive behaviour in P. crussicornis. Nematocysts were present in the enidosacs and their role in defense was investigated. Fired nematocysts were observed in podia of the asteroid Crossaster papposus following ceratal contact but were not seen in the podia of Pycnopodia helianthoides in a similar trial. For P. crassicornis, the cnidosacs may function primarily as a storage device for safe sequestering of nematoeysts that could pose a threat to the digestive system. They did not play a major defensive role against the predators tested, but may be important in the field against other predators.

Computational Investigation of Simulated Large-Droplet Ice Shapes on Airfoil Aerodynamics

The objective of this research was to study numerically the effects of simulated spanwise-step-ice accretions (resulting from supercooled large-droplet icing conditions ) on subsonic aircraft aerodynamics. The investigation was performed with a high-resolution full Navier ‐Stokes code with a solution-adaptive unstructured grid for both non-icedandicedcone gurations.Theairfoilinvestigatedwasamodie ed NACA23012 witha simplee ap.Simulated ice shapesweretested on theairfoilto determinethe sensitivity oficeshapesizeon airfoil performanceand control. Predictions of sectional aerodynamic characteristics for quarter-round ice shape heights of 0.0083 and 0.0139 chords are presented and compared with experimental data. Signie cant reductions in lift were noted for these relatively small protuberances, which were consistent with experimental e ndings. The results also indicate good predictive performance for drag, pitching-moment, and hinge-moment variations.

Enhanced Mass Transfer in Monolith Catalysts with Bumps on the Channel Walls

The mass-transfer rate in metallic triangular monolith channels with small protuberances on the channel walls was measured and compared with conventional, straight channels without bumps. The CO oxidation reaction was used to estimate the mass-transfer rates. Measurements were made at Reynolds numbers between 300 and 1400. The channels were 3.7 mm wide and 2.6 mm high and had a length of 96.5−152 mm. Two different bump heights were investigated: 1 and 1.2 mm. Moreover, the distance between the bumps as well as the distance from the inlet to the first bump was varied. It was found that the protuberances increase the mass-transfer rate, expressed as the Sherwood number. The increase was higher when the Reynolds number was increased. There was also a penalty of increased pressure drop. However, when the jD factor for mass transfer was compared with the friction factor f, it was found that the increase in mass transfer was generally higher than the increase in pressure drop.

1620 Geographos and 433 Eros: Shaped by Planetary Tides?

Until recently, most asteroids were thought to be solid bodies whose shapes were determined largely by collisions with other asteroids. It now seems that many asteroids are little more than rubble piles, held together by self-gravity; this means that their shapes may be strongly distorted by tides during close encounters with planets. Here we report on numerical simulations of encounters between a ellipsoid-shaped rubble-pile asteroid and the Earth. After an encounter, many of the simulated asteroids develop the same rotation rate and distinctive shape (i.e., highly elongated with a single convex side, tapered ends, and small protuberances swept back against the rotation direction) as 1620 Geographos. Since our numerical studies show that these events occur with some frequency, we suggest that Geographos may be a tidally distorted object. In addition, our work shows that 433 Eros, which will be visited by the NEAR spacecraft in 1999, is much like Geographos, which suggests that it too may have been molded by tides in the past.

In vitro studies on the anatomy and morphology of bud regeneration in melon cotyledons

The anatomy and morphology of bud regeneration were investigated in melon (Cucumis melo L.) cv. Galia, which regenerates in vitro only by direct organogenesis from the cotyledon explant. Explants were cut from the cotyledon proximal to the apex from 3-d-old in vitro seedlings. After 3 d on Murashige and Skoog medium with N6-benzyladenine, cell division can be observed in the epidermal layer on the adaxial side in the center of the explant, near the most proximal (wounded) cut edge. Over the next week, the area of the meristem increases laterally. Additional cell layers are added to the meristematic area by cell division in the epidermis. In places the epidermis remains active in cell division. Alongside those active areas there are zones where the epidermis has become inactive, although the subepidermal layers continue to divide. In transverse section, the explant now has small protuberances on the adaxial surface. After 10 d on cytokinin-containing medium, the first signs of development are visible on the adaxial surface adjacent to the proximal cut edge. The protuberances observed after 10 d are neither primordia nor buds, although some meristematic bulges are observed. The first regenerated shoot buds are observed histologically after 15 d, by which time the surface has many protuberances and some small leaves. The first shoot is found by histology after 22 d. By this time the surface is covered with protrusions and leaves, mostly without accompanying buds. The leaves may be produced from the protrusions initially visible after 10 d.