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External Surface (external + surface)
Selected AbstractsFormation of SnO2 Nanoparticles on External Surface of NaY ZeoliteCHINESE JOURNAL OF CHEMISTRY, Issue 4 2005Xu Xiao-Wen Abstract Tin dioxide nanoparticles of 5 nm in size were prepared on NaY zeolite external surface by impregnation of SnCl2 solution and subsequent calcination at 623 K. A SnO2 -NaY based chemical sensor for detecting H2 was demonstrated. [source] Adhesive papillae on the brachiolar arms of brachiolaria larvae in two starfishes, Asterina pectinifera and Asterias amurensis, are sensors for metamorphic inducing factor(s)DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2007Naoyuki Murabe It has been hypothesized by Barker that starfish brachiolaria larvae initiate metamorphosis by sensing of metamorphic inducing factor(s) with neural cells within the adhesive papillae on their brachiolar arms. We present evidence supporting Barker's hypothesis using brachiolaria larvae of the two species, Asterina pectinifera and Asterias amurensis. Brachiolaria larvae of these two species underwent metamorphosis in response to pebbles from aquaria in which adults were kept. Time-lapse analysis of A. pectinifera indicated that the pebbles were explored with adhesive papillae prior to establishment of a stable attachment for metamorphosis. Microsurgical dissections, which removed adhesive papillae, resulted in failure of the brachiolaria larvae to respond to the pebbles, but other organs such as the lateral ganglia, the oral ganglion, the adhesive disk or the adult rudiment were not required. Immunohistochemical analysis with a neuron-specific monoclonal antibody and transmission electron microscopy revealed that the adhesive papillae contained neural cells that project their processes towards the external surface of the adhesive papillae and they therefore qualify as sensory neural cells. [source] Osteoderm morphology in recent and fossil euphractine xenarthransACTA ZOOLOGICA, Issue 4 2009C. M. Krmpotic Abstract The presence of osteoderms within the integument, forming a carapace, is one of the most distinctive features of armadillos with the external morphology of these elements forming the basis of most systematic schemes. This is especially true for fossil taxa, where these elements are most frequent in the palaeontological record. A detailed study of osteoderms from the cephalic shield and different regions of the dorsal armour of Chaetophractus villosus (Euphractinae, Xenarthra) was made and compared to those of the extant genus Dasypus (Dasypodinae, Xenarthra), and the extinct genus ,Eutatus. Three distinct histological zones were recognized: outer and inner zones are thin, formed by regular compact bone, the middle zone is thicker, with large cavities that contain mainly adipose tissue, hair follicles, and sweat and sebaceous glands. The internal structure of ,Eutatus (also a member of Euphractinae) osteoderms is close to that of C. villosus, consistent with the notion that these taxa are phylogenetically closely related. In contrast, Dasypus shows marked differences. Dasypus shows hair follicles associated with both gland types (sweat and sebaceous) and connected to foramina on the external surface. Although not observed in adult C. villosus, it has been documented during embryonic development, only to atrophy later in ontogeny. Furthermore, the presence of red bone marrow is rare in C. villosus, but widespread in Dasypus novemcinctus osteoderms. These results suggest an early split of both subfamilies and support the hypothesis that the Euphractinae are more derived than the Dasypodinae. [source] The earliest evidence of host,parasite interactions in vertebratesACTA ZOOLOGICA, Issue 2009evics, ns Luk Abstract Traces of parasite action have been discovered in the Middle,Upper Devonian fish from Estonia, Latvia and European Russia. Such traces are known in heterostracan Psammolepis venyukovi, antiarchs Asterolepis radiata and Bothriolepis ciecere, sarcopterygians Holoptychius sp., Ventalepis ketleriensis and Eusthenodon sp. nov. The traces include evidence of parasitic fixation and penetration as well as dwelling traces. Pathologies are developed as (1) round fossulae on the external surface of bones and scales; (2) oval fossulae with a slight elevation in the centre of the pit; (3) hollow swellings (possible galls); (4) openings (perforations) that have been repaired to various degrees; (5) variously shaped buttresses on the visceral surface of sarcopterygian scales; and (6) porous spongy formations on the non-overlapped surface of sarcopterygian scales. The round fossulae in sarcopterygian, placoderm and psammosteid skeletal elements could be produced by parasites that are similar to copepod crustaceans. Gall formation in Asterolepis is most likely to be caused by a larva, possibly of a trematode. The perforations of scales (and dermal bones) might arise from the attacks of ectoparasites (copepods?) or different worms. The spongy formations on the Holoptychius scales could be the result of invasion of a unicellular parasite. [source] Capillary electrophoretic study of the binding of zinc(II) ion to bacitracin A1 in water-2,2,2-trifluoroethanolELECTROPHORESIS, Issue 10 2003Massimo Castagnola Abstract Binding of Zn2+ to bacitracin A1 was studied by capillary electrophoresis in water/2,2,2-trifluoroethanol (70/30 v/v) at different apparent pH values in order to estimate the association constant of metal, the acidic dissociation constants and the Stokes radii of both free and bounded peptide in apolar environment. The Stokes radii of the free peptide species were compared with those in aqueous solution, as obtained in a recent study performed by our group, indicating that apolar environment stabilizes bacitracin A1 in a conformational structure with the lateral chain of apolar amino acids exposed on the external surface. This conformation of the macrocyclic dodecapeptide is ready to interact with Zn2+ ion, as pointed out by the strong increase of the association constant measured in water/2,2,2-trifluoroethanol with respect to the value obtained in aqueous solution. In addition, whereas Zn2+ ion binding in aqueous solution provides a sensible reduction of peptide Stokes radius, no sensible variations following to ion binding were observed in hydro-organic solution. The present results suggest that the apolar environment, rather than the metal ion binding, could be responsible for the conformational transition that brings bacitracin A1 towards its biologically active structure.* [source] Immunocompetence of bivalve hemocytes as evaluated by a miniaturized phagocytosis assayENVIRONMENTAL TOXICOLOGY, Issue 3 2002C. Blaise Abstract Immune function in bivalves can be adversely affected by long-term exposure to environmental contaminants. Investigating alterations in immunity can therefore yield relevant information about the relationship between exposure to environmental contaminants and susceptibility to infectious diseases. We have developed a rapid, cost-effective, and miniaturized immunocompetence assay to evaluate the phagocytic activity, viability, and concentration of hemocytes in freshwater and marine bivalves. Preliminary experiments were performed to optimize various aspects of the assay including 1) the time required for adherence of hemocytes to polystyrene microplate wells, 2) the time required for internalization of fluorescent bacteria, 3) the ratio of hemocytes to fluorescent bacteria in relation to phagocytosis, 4) hemolymph plasma requirements, and 5) the elimination of fluorescence from (noninternalized) bacteria adhering to the external surface of hemocytes. The results of these experiments showed the optimal adherence time for hemocytes in microplate wells to be 1 h, that phagocytosis required at least 2 h of contact with fluorescently labeled E. coli cells, that the number of fluorescent E. coli cells had a positive effect on phagocytic activity, that at least 2.5 million cells/mL were required to measure a significant intake, and that a linear increase in uptake of bacteria (R = 0.91; p < 0.01) could be obtained with concentrations of up to 1.3 × 106 hemocytes/mL. Afterward, the assay was used in two field studies to identify sites having the potential to affect the immunocompetence of bivalves. The first study was conducted on Mya arenaria clams collected at selected contaminated sites in the Saguenay River (Quebec, Canada), and the second examined Elliptio complanata freshwater bivalves that had been exposed to a municipal effluent plume in the St. Lawrence River (Quebec, Canada). In the Saguenay River field study a significant increase in phagocytosis was observed at sites closest to polluted areas. Phagocytotic activity varied over time and was highest during the warmest months (June, July, and August), closely paralleling the spawning period of Mya arenaria clams. In contrast, a drop in phagocytic activity was observed in Elliptio complanata mussels exposed to surface water 4 km downstream of a major municipal effluent plume, with a concomitant increase in the number of hemocytes in the hemolymph. It appears that both immunosuppressive and immunostimulative effects are likely to occur in the field and that responses will be influenced by the type and intensity of contaminants at play. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 160,169, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10047 [source] Generality of vertebrate developmental patterns: evidence for a dermomyotome in fishEVOLUTION AND DEVELOPMENT, Issue 1 2006S. H. Devoto SUMMARY The somitic compartment that gives rise to trunk muscle and dermis in amniotes is an epithelial sheet on the external surface of the somite, and is known as the dermomyotome. However, despite its central role in the development of the trunk and limbs, the evolutionary history of the dermomyotome and its role in nonamniotes is poorly understood. We have tested whether a tissue with the morphological and molecular characteristics of a dermomyotome exists in nonamniotes. We show that representatives of the agnathans and of all major clades of gnathostomes each have a layer of cells on the surface of the somite, external to the embryonic myotome. These external cells do not show any signs of terminal myogenic or dermogenic differentiation. Moreover, in the embryos of bony fishes as diverse as sturgeons (Chondrostei) and zebrafish (Teleostei) this layer of cells expresses the pax3 and pax7 genes that mark myogenic precursors. Some of the pax7- expressing cells also express the differentiation-promoting myogenic regulatory factor Myogenin and appear to enter into the myotome. We therefore suggest that the dermomyotome is an ancient and conserved structure that evolved prior to the last common ancestor of all vertebrates. The identification of a dermomyotome in fish makes it possible to apply the powerful cellular and genetic approaches available in zebrafish to the understanding of this key developmental structure. [source] Synthesis of High-Surface-Area Platinum Nanotubes Using a Viral TemplateADVANCED FUNCTIONAL MATERIALS, Issue 8 2010. Górzny, Marcin Abstract A novel method for the synthesis of high-active-surface-area, platinum,tobacco mosaic virus (Pt,TMV) nanotubes is presented. A platinum salt is reduced to its metallic form on the external surface of a rod-shaped TMV by methanol, which serves as a solvent and reductant simultaneously. It was found that for the same Pt loading the Pt,TMV nanotubes had an electrochemically active surface area between 4 to 8 times larger than similarly sized Pt nanoparticles. A Pt,TMV catalyst displays greater stability in acidic conditions than those based on nanoparticles. When used as a catalyst for methanol oxidation, these Pt nanotubes display a 65% increase in catalytic mass activity compared to that based on Pt nanoparticles. [source] Presence of pores and vacuoles in set endodontic sealersINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2005L. Mutal Abstract Aim, To assess qualitatively the presence of pores and vacuoles in the structure of various endodontic sealers when set. Methodology, Eight specimens were prepared in keeping with Instituto Argentino de Racionalización de Materiales (IRAM) and ISO regulations for each of the 10 sealers assessed. Four specimens per sealer were examined to identify the presence of structural defects, termed pores, on the external surface. The remaining four specimens were used to examine the presence of defects on the surface exposed by cross-sectional fracture; these were termed vacuoles. The largest and smallest diameters of the pores and vacuoles were measured by scanning electron microscope on both surfaces. The structural defects were classified according to their frequency as abundant, frequent, scarce or exceptional. Results, Pores and vacuoles were consistently found in every specimen of each sealer. However, their frequency and dimensions were greater in zinc-eugenol-based sealers than in epoxy-resins and glass,ionomer sealers; they increased if the sealer contained calcium hydroxide. The diameter of the pores ranged from 5 to 320 ,m and the diameter of the vacuoles ranged from 80 to 500 ,m. The diameter of the vacuoles always exceeded that of the pores. Conclusions, Pores and vacuoles were a consistent finding in set sealers. Their frequency and size depended on the density of the sealer and increased when the sealers contained calcium hydroxide. [source] Symbiosis of Mycale (Mycale) vansoesti sp. nov. (Porifera, Demospongiae) with a coralline alga from North Sulawesi (Indonesia)INVERTEBRATE BIOLOGY, Issue 3 2006Barbara Calcinai Abstract. The symbiotic association between the new sponge species Mycale vansoesti and the coralline alga Amphiroa sp. from the Bunaken Marine Park (North Sulawesi, Indonesia) is described. The alga completely pervades the sponge. The color of the sponge ectosome is white, both on the external surface and on the atrial wall, but where the alga is present the sponge takes on the light pink color of the alga. The sponge spicular complement is characterized by mycalostyles, anisochelae of two types, sigmas (often "C" shaped), and extremely abundant toxas organized in bundles forming toxadragma. In the association, the sponge shows very low silicate value, and consequently the alga represents the main skeleton of the sponge. On the other hand, the sponge affects the morphology of the alga, leading to a cylindrical shape, with thalli running parallel to the sponge surface. This association seems to be obligate for the sponge, as we found no sponges of this species living in isolation. [source] A comparative study of mammalian tracheal mucous glandsJOURNAL OF ANATOMY, Issue 3 2000H. K. CHOI We have compared the distribution, numbers and volume of mucous glands in the tracheas of 11 mammalian species. No glands were present in the rabbit. The mouse only contained glands at the border between the trachea and larynx. In the rat, glands were commonest in the cephalad third of the trachea, but on average were much scarcer than in the larger species. Between species, there was a significant correlation between airway diameter and gland volume per unit surface area, suggesting that the rate of deposition of inhaled particles may increase in large airways. In the ventral portion of the trachea of about half the species, the glands were concentrated between the cartilaginous rings; in others they were evenly distributed over and between the rings. In most species in which the trachealis muscle attached to the internal surface of the cartilaginous rings, the glands were external to the muscle. In all species in which the muscle attached to the external surface of the cartilaginous rings, the glands were internal to the muscle. In the ox, goat, dog and sheep, the volume of glands per unit tracheal surface area was markedly greater in the ventral than the dorsal aspect of the trachea. The reverse was true of the pig. In humans, gland density in the 2 regions was similar. The frequency of gland openings was determined in the ox, goat, pig, dog and sheep tracheas, and ranged from 0.3 per mm2 in the dorsal portion of the sheep trachea to 1.5 per mm2 in the ventral portion of the ox trachea. For these 5 species, the volume of gland acini per unit luminal surface area varied linearly with the numbers of gland openings, with the volume of individual glands being constant at , 120 nl. [source] Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactorJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2002Vassilios I. Sikavitsas Abstract The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague,Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L -lactic- co -glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the accelerated proliferation and differentiation of marrow stromal osteoblasts, and the localization of the enhanced mineralization on the external surface of the scaffolds. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 136,148, 2002 [source] Esophageal Luminal Temperature Measurement Underestimates Esophageal Tissue Temperature During Radiofrequency Ablation Within the Canine Left Atrium: Comparison Between 8 mm Tip and Open Irrigation CathetersJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2008JENNIFER E. CUMMINGS M.D. Introduction: Evaluation of luminal temperature during left atrial ablation is used clinically; however, luminal temperature does not necessarily reflect temperature within the esophageal wall and poses a risk of atrioesophageal fistula. This animal study evaluates luminal esophageal temperature and its relation to the temperature of the external esophageal tissue during left atrial lesions using the 8 mm solid tip and the open irrigated tip catheters (OIC). Methods and Results: A thermocouple was secured to the external surface of the esophagus at the level of the left atrium of the dogs. Luminal esophageal temperature was measured using a standard temperature probe. In four randomized dogs, lesions were placed using an 8 mm solid tip ablation catheter. In six randomized dogs, lesions were placed using the 3.5 mm OIC. The average peak esophageal tissue temperature when using the OIC was significantly higher than that of the 8 mm tip catheter (88.6°C ± 15.0°C vs. 62.3°C ± 12.5°C, P < 0.05). Both OIC and 8 mm tip catheter had significantly higher peak tissue temperatures than luminal temperatures (OIC: 88.6°C ± 15.0°C vs 39.7°C ± 0.82°C, P < 0.05) (8 mm: 62.3°C ± 12.5°C vs 39.0 ± 0.5°C, P < 0.05). Both catheters achieved peak temperatures faster in the tissue as compared to the lumen of the esophagus, although the tissue temperature peaked significantly faster for the OIC (OIC: 25 seconds vs 90 seconds, P < 0.05) (8 mm: 63 seconds vs 105 seconds, P < 0.05). Conclusion: Despite the significant difference in actual tissue temperatures, no significant difference was observed in luminal temperatures between the OIC and 8 mm tip catheter. [source] Effect of activation type on bioregeneration of various activated carbons loaded with phenolJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006Özgür Akta Abstract Thermally and chemically activated powdered carbons (PAC), and their granular countertypes (GAC) with similar physical characteristics were used to investigate the extent of bioregeneration in laboratory-scale activated sludge reactors. Bioregeneration of activated carbon was determined by measurement of bulk phenol concentrations and loadings remaining on activated carbon. It was also followed by oxygen uptake rate measurements. For the carbons used in this study, bioregeneration of chemically activated carbons was found to be higher than thermally activated ones. This was in accordance with their higher reversibility of adsorption and showed that bioregeneration was controlled by the reversibility of adsorption. Oxidative polymerization of phenol was a plausible explanation for low bioregeneration of thermally activated carbons. However, bioregeneration efficiencies of thermally activated carbons were much higher than their total desorbabilities. This unexpectedly high bioregeneration indicated that some exoenzymatic reactions had occurred. These results suggest that carbon activation type is of crucial importance for bioregeneration. PAC and GAC countertypes showed comparable bioregeneration efficiencies indicating that carbon size was not an effective factor. The environmental scanning electron microscopy (ESEM) studies showed that microorganisms were attached both on the external surface and interval cavities of activated carbon particles. Copyright © 2006 Society of Chemical Industry [source] Performance study of modified ZSM-5 as support for bimetallic chromium,copper catalysts for VOC combustionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2004Ahmad Zuhairi Abdullah Abstract The catalytic performance of bimetallic chromium,copper supported over untreated ZSM-5 (CrCu/Z), ZSM-5 treated with silicon tetrachloride (Cr,Cu/SiCl4 -Z) and ZSM-5 treated with steam (Cr,Cu/H2O-Z) is reported. The activity is based on the combustion of ethyl ethanoate and benzene at a feed concentration of 2000 ppm and a gas hourly space velocity (GHSV) of 32 000 h,1. Due to higher reactivity and larger molecular size compared with that of water molecules, SiCl4 reacted at the external surface of ZSM-5 crystals. Cr,Cu/SiCl4 -Z and Cr,Cu/H2O-Z both gave slightly lower conversion and carbon dioxide yield compared with Cr,Cu/Z. This was attributed to larger active metal crystallites formed in the mesopores and narrowing pore mouth and pore intersection by extraframework species. Cr,Cu/SiCl4 -Z and Cr,Cu/H2O-Z both had reduced concentration and strength of acid sites, thus making them less susceptible to deactivation by coking. The coke accumulated by these two catalysts was relatively softer and more easily decomposed in oxygen during catalyst regeneration. Copyright © 2004 Society of Chemical Industry [source] A new source of aging?JOURNAL OF COSMETIC DERMATOLOGY, Issue 2 2009Helen Knaggs MD Summary There has been a considerable increase in understanding how skin ages, along with significant progress toward the correction and prevention of the visible signs of aging. However, there are still many unknown factors regarding why we age , and why we all seem to age differently. An area of high interest is the biological or intrinsic processes that affect our appearance over time. This article describes a recent discovery of a membrane bound enzyme proven to be present in skin and increases its activity as biological age increases. The enzyme is located on the external surface of both fibroblast and keratinocytes, and generates free radicals. Therefore, as we age there appears to be a biological mechanism that further increases the production of free radicals. Additionally, there appears to be a relationship between activity of the enzyme and appearance. Data showed that subjects who look younger than their biological age had lower enzyme activity and conversely, subjects who looked older than their biological age had higher enzyme activity. Free radicals are believed to be a major contributing factor in the production of fine lines and wrinkles by destroying the collagen and elastin network keeping skin supple and firm. [source] Histopathology, immunohistochemistry and ultrastructure of the intestine of Leuciscus cephalus (L.) naturally infected with Pomphorhynchus laevis (Acanthocephala)JOURNAL OF FISH DISEASES, Issue 1 2002B S Dezfuli The histopathology, immunohistochemistry and ultrastructure of the alimentary canal of chub, Leuciscus cephalus (L.), from the River Brenta, naturally infected with the acanthocephalan Pomphorhynchus laevis Müller, 1776, was studied and described. Of 62 chub examined, 54 (87%) were infected with P. laevis; the intensity of infection ranged from five to 130 parasites per host, and a density of 8 P. laevis per cm2 was common. Examination of histological material of infected chub revealed that both male and female acanthocephalans deeply penetrated all layers of the gut wall by means of their slender neck, bulb and proboscis. As a result, a capsule was formed around the bulb and proboscis on the external surface of the host intestine. In parasitized chub, four main types of reaction against the body of the acanthocephalan were recognized. Pomphorhynchus laevis caused local damage to the intestinal wall, eliciting catarrhal-erosive enteritis in the lumen and a fibroblastic-collagenous and fibro-epithelioid encapsulation in its thickness with tissue zonation according to the depth of parasite penetration. Furthermore, eosinophilic granular cells (EGC) within the inflammatory tissue were identified by immunohistochemical methods and transmission electron microscopy. [source] INFLUENCE OF WASHING TREATMENT ON NATIVE MICROFLORA AND ESCHERICHIA COLI POPULATION OF INOCULATED CANTALOUPESJOURNAL OF FOOD SAFETY, Issue 1 2001DIKE O. UKUKU ABSTRACT The influence of chlorine or hydrogen peroxide treatment on populations of Escherichia coli 25922 on the external surface of inoculated cantaloupe was investigated. Surface treatment with 70% EtOH, followed by immersion in 108 CFU/mL E. coli inoculum deposited an average of 4.4 log10CFU/cm2 cell population on the cantaloupe surface. The efficncy of washing inoculated cantaloupe was dependent on storage interval between inoculation and treatment. Dipping the cantaloupes in solutions containing 1000 mg/L chlorine or 5% peroxide for 5 min, within 24 h of inoculation, caused a 2 log10 CFU/cm2 reduction of the indigenous surface microflora and a 3,4.0 log10 CFU/cm2 reduction in E. coli. The efficacy was less when the interval between inoculation and treatment exceeded 24 h. Chlorine appeared in be a better antimicrobial agent than hydrogen peroxide against F. coli ATCC 25922 inoculated on cantaloupe surfaces while hydrogen peroxide was better in reducing surface microflora of cantaloupe. [source] Numerical analysis of thermal and electrochemical phenomena for anode supported microtubular SOFCAICHE JOURNAL, Issue 3 2009Daan Cui Abstract A 2D model considering momentum, heat/species transport and electrochemical phenomena, has been proposed for tubular solid oxide fuel cell. The model was validated using experimental polarization curves and the good agreement with the experimental data was attained. The temperature distributions show that temperature varies severely at the tube inlet than at the tube outlet. The heat generation and transfer mechanisms in electrodes, electrolyte and electrochemical reaction interface were investigated. The results show that the overall electrochemical reaction heat is produced at cathode/electrolyte interface, and a small portion of the heat is consumed at anode/electrolyte interface. The heat produced at cathode/electrolyte interface is about five times as much as that consumed at anode/electrolyte interface. Overwhelming part of the heat transfer between cell and outside occurs at cathode external surface. Most current flow goes into anode from a very small area where the current collectors locates. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The pheromonal gland of Lymantria dispar: Morphology and evidence for its innervationJOURNAL OF MORPHOLOGY, Issue 4 2009Marianna Boi Abstract The morphological features of the glandular epithelium that secretes pheromone in the polyphagous pest gypsy moth Lymantria dispar are described by light and electron microscopy. The monolayered gland cells are covered by the folded cuticle of the intersegmental membrane between the 8th and 9th abdominal segments showing neither sites of discontinuity nor distinct openings on its external surface. The cells bear a large, often irregularly shaped nucleus, and contain granules of variable amount and electron-density. These granules are mostly located in the basal compartment of the cytoplasm, in a labyrinthine zone laying on a basement membrane. The apical membrane of the gland cells bear microvilli and cell,cell contact is established by different junctional structures. Nerve fibers enwrapped in glia are found beneath the basement membrane, in close contact with the secretory cells. This latter finding represents the first evidence of the innervation of the pheromonal gland in L. dispar. J. Morphol. 2009. © 2008 Wiley-Liss, Inc. [source] Metamorphosis of cinctoblastula larvae (Homoscleromorpha, porifera)JOURNAL OF MORPHOLOGY, Issue 6 2007Alexander V. Ereskovsky Abstract The metamorphosis of the cinctoblastula of Homoscleromorpha is studied in five species belonging to three genera. The different steps of metamorphosis are similar in all species. The metamorphosis occurs by the invagination and involution of either the anterior epithelium or the posterior epithelium of the larva. During metamorphosis, morphogenetic polymorphism was observed, which has an individual character and does not depend on either external or species specific factors. In the rhagon, the development of the aquiferous system occurs only by epithelial morphogenesis and subsequent differentiation of cells. Mesohylar cells derive from flagellated cells after ingression. The formation of pinacoderm and choanoderm occurs by the differentiation of the larval flagellated epithelium. This is possibly due to the conservation of cell junctions in the external surface of the larval flagellated cells and of the basement membrane in their internal surface. The main difference in homoscleromorph metamorphosis compared with Demospongiae is the persistence of the flagellated epithelium throughout this process and even in the adult since exo- and endopinacoderm remain flagellated. The antero-posterior axis of the larva corresponds to the baso-apical axis of the adult in Homoscleromorpha. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source] Fabrication of Free-Standing Titania-Based Gas Sensors by the Oxidation of Metallic Titanium FoilsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2000Pelagia I. Gouma A simple method for fabricating TiO2 -based sensors of CO(g) is demonstrated: the oxidation of Ti-bearing foils. Metallic foils (35 ,m thick) were converted into free-standing, porous rutile foils (60 ,m thick) by exposure to O2(g) at 800°,965°C. The oxidized foils contained thin (0.5,1 ,m thick), regularly spaced oxide layers oriented parallel to the external surface. The exposure of such porous foils to increasing concentrations of CO(g) resulted in a monotonic increase in the steady-state electrical resistance. Rutile foils sensitive to 50 ppm changes in CO(g) content with response times of a few minutes were produced. The effects of oxidation conditions and copper doping on sensing performance are discussed. [source] Rho A participates in the regulation of phosphatidylserine-dependent procoagulant activity at the surface of megakaryocytic cellsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2004C. Kunzelmann Summary. Once exposed at the external surface of activated platelets or apoptotic cells, phosphatidylserine, an anionic phospholipid mostly sequestered in the inner leaflet of the plasma membrane, plays essential roles in hemostasis and phagocytosis. The mechanism governing the migration of the phosphatidylserine to the exoplasmic leaflet is not yet fully understood. We have proposed that store-operated calcium entry (SOCE) constitutes a key step of this process. ERK pathway is among the elements modulating SOCE and phosphatidylserine externalization in megakaryocytic HEL cells. Here, we investigated the role of small GTPase Rho A, which may interact with the ERK pathway. Specific inhibitors of Rho A (exoenzyme C3 and toxin B) reduced both SOCE and phosphatidylserine-dependent procoagulant activity. Simultaneous inhibition of Rho A and extracellular signal-regulated kinase (ERK) pathways did not elicit further reduction with respect to each individual one. Rho A can regulate SOCE and phosphatidylserine exposure through the reorganization of actin cytoskeleton, but not through ROCK pathway. Hence, Rho A is another regulatory element for the completion of SOCE-induced phosphatidylserine transmembrane redistribution in HEL cells. [source] The Bagnone iron meteorite (Tuscany, Italy): History, mineralogy, and chemical classificationMETEORITICS & PLANETARY SCIENCE, Issue S8 2004M. D'Orazio The morphology of the external surface suggests that Bagnone represents a complete individual. It is classified as a medium octahedrite (average bandwidth = 0.96 mm) of the IIIAB chemical group, based on inductively coupled plasma mass spectrometry analyses. [source] Numerical analysis of interferograms for evaluation of tear film build-up timeOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2009Dorota H. Szczesna Abstract The lateral shearing interferometer was applied to the in vivo dynamic investigation of the external surface of the pre-corneal tear film after an eye blink. Sequences of interferograms were recorded at a sampling frequency of 25 Hz. Immediately after every eye blink, a bright pattern was observed under the interference fringes. This disappeared after a short time interval (around 0.5,2 s): smooth interference fringes were then observed, corresponding to the creation of a smooth anterior optical surface over the cornea. The purpose of this study is to describe in detail the kinetics of pre-corneal tear film stability and to propose quantitative measures of the stabilisation process in healthy eyes during the 3 s period after a blink. Two methods of quantitative assessment of the tear film build-up time are presented. The first is based upon the evaluation of the inhomogeneity of the background of the interferogram; the second evaluates the orientation of the structure of the background by the analysis of the zero order of the Fast Fourier Transform (FFT) spectrum. The quasi-vertically oriented bright line patterns observed in interferograms immediately after a blink and the mirror-symmetry of their tilts for right and left eyes indicate that the pattern is related to the wiping movements of the upper eyelids during the eye blink. [source] Physicochemical Properties of Functional Surfaces in Pitchers of the Carnivorous Plant Nepenthes alata Blanco (Nepenthaceae)PLANT BIOLOGY, Issue 6 2006E. V. Gorb Abstract: Pitchers of the carnivorous plant Nepenthes alata are highly specialized organs adapted to attract, capture, and digest animals, mostly insects. They consist of several well distinguishable zones, differing in macro-morphology, surface microstructure, and functions. Since physicochemical properties of these surfaces may influence insect adhesion, we measured contact angles of non-polar (diiodomethane) and polar liquids (water and ethylene glycol) and estimated the free surface energy of 1) the lid, 2) the peristome, 3) the waxy surface of the slippery zone, and 4) the glandular surface of the digestive zone in N. alata pitchers. As a control, the external surface of the pitcher, as well as abaxial and adaxial surfaces of the leaf blade, was measured. Both leaf surfaces, both lid surfaces, and the external pitcher surface showed similar contact angles and had rather high values of surface free energy with relatively high dispersion component. These surfaces are considered to support strong adhesion forces based on the capillary interaction, and by this, to promote successful attachment of insects. The waxy surface is almost unwettable, has extremely low surface energy, and therefore, must essentially decrease insect adhesion. Both the peristome and glandular surfaces are wetted readily with both non-polar and polar liquids and have very high surface energy with a predominating polar component. These properties result in the preclusion of insect adhesion due to the hydrophilic lubricating film covering the surfaces. The obtained results support field observations and laboratory experiments of previous authors that demonstrated the possible role of different pitcher surfaces in insect trapping and retention. [source] A heuristic approach of calculating spray water flux needed to avert fire-induced runaway reactions,,PROCESS SAFETY PROGRESS, Issue 3 2006BChE (Honors), Dilip K. Das BSc (Honors), MSChE In general all reactions have some heat effects. When the ability of the equipment to remove the heat is exceeded by the heat generated by a reaction, a hazardous situation called a runaway reaction may take place. Sometimes the exothermicity of runaway reactions is so high that the size of an emergency vent becomes impractical to install. A water spray system can sometimes be used to avert a fire-induced runaway reaction. Because the water spray system has a finite activation time, insulation helps to prolong the time required to reach the decomposition temperature. This article concludes that the required water flux to avert the fire-induced runaway reaction may be conservatively estimated by adding the water flux necessary to maintain an unbroken water film on the external surface of the equipment and the water flux necessary to absorb the fire heat after allowing for the splash loss and the in-flight loss. When adequate spray water is used, the metal temperature of the insulation jacket cannot theoretically exceed the boiling point of water thereby ensuring the avoidance of fire-induced runaway reactions whose adjusted onset decomposition temperature exceeds 100 ° C. Fire-induced runaway reactions with lower onset temperature can also be avoided depending on the initial temperature of the contents, mass of the contents and equipment, insulation thickness, and fire duration, for example, but a detailed calculation including dynamic simulation is necessary and the burden of proof lies with the designer. The reliability of the spray water system must be maintained high to include its credit as an environmental factor defined according to NFPA 30 to avoid the fire-induced runaway reaction as a scenario. Although API RP 521 does not allow any credit for sprinkler water, it allows credit, unlike NFPA 30, for insulation thickness and thus a runaway reaction can be avoided by using insulation alone according to API RP 521. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006 [source] An approach to characterizing single-subunit mutations in multimeric prepores and pores of anthrax protective antigenPROTEIN SCIENCE, Issue 2 2009Blythe E. Janowiak Abstract Heptameric pores formed by the protective antigen (PA) moiety of anthrax toxin translocate the intracellular effector moieties of the toxin across the endosomal membrane to the cytosol of mammalian cells. We devised a protocol to characterize the effects of individual mutations in a single subunit of heptameric PA prepores (pore precursors) or pores. We prepared monomeric PA containing a test mutation plus an innocuous Cys-replacement mutation at a second residue (Lys563, located on the external surface of the prepore). The introduced Cys was biotinylated, and the protein was allowed to cooligomerize with a 20-fold excess of wild-type PA. Finally, biotinylated prepores were freed from wild-type prepores by avidin affinity chromatography. For the proof of principle, we examined single-subunit mutations of Asp425 and Phe427, two residues where Ala replacements have been shown to cause strong inhibitory effects. The single-subunit D425A mutation inhibited pore formation by >104 and abrogated activity of PA almost completely in our standard cytotoxicity assay. The single-subunit F427A mutation caused ,100-fold inhibition in the cytotoxicity assay, and this effect was shown to result from a combination of strong inhibition of translocation and smaller effects on pore formation and ligand affinity. Our results show definitively that replacing a single residue in one subunit of the heptameric PA prepore can inhibit the transport activity of the oligomer almost completely,and by different mechanisms, depending on the specific residue mutated. [source] Large Bore Catheters with Surface Treatments versus Untreated Catheters for Vascular Access in HemodialysisARTIFICIAL ORGANS, Issue 7 2004Rolf Bambauer Abstract:, Infection, thrombosis, and stenosis are among the most frequent complications associated with blood-contacting catheters. Complications resulting from infection remain a major problem for hemodialysis catheters, with significant numbers of catheters being removed due to catheter-related sepsis. Numerous strategies have been employed to reduce the occurrence of infection and im-prove long-term outcomes, with varying degrees of success. The most important is the careful and sterile handling by the attending staff of the catheters during hemodialysis treatments to minimize or stop a microbial colonization of the skin and the catheter. Another approach is coating the external surface of the catheters with substances which are antibacterial like silver and/or substances with low thrombogenicity like silicone. This investigation reviews results of animal and clinical experiments conducted to assess the efficacy and biocompatibility of silver and silicone coated dialysis catheters. It is concluded that silver coatings can reduce bacterial colonization and occurrence of infection associated with these devices. The catheters employing ion implantation of silicone rubber showed low thrombogenicity. Results of the studies indicate that ion beam based processes can be used to improve thrombus and infection resistance of blood contacting catheters. A new development is the microdomain structured surface (PUR-SMA coated catheters). Preliminary results with these catheters are very encouraging. [source] Diagnosis and management of unusual dental abscesses in childrenAUSTRALIAN DENTAL JOURNAL, Issue 3 2003WK Seow Abstract Although the majority of dental abscesses in children originate from dental caries or trauma, a few are associated with unusual conditions which challenge diagnosis and management. Recent research findings have shed light on these unusual entities and greatly improved understanding of their clinical implications. These conditions include developmental abnormalities such as dens invaginatus in which there is an invagination of dental tissues into the pulp chamber and dens evaginatus in which a tubercle containing pulp is found on the external surface of a tooth crown. In addition, inherited conditions which show abnormal dentine such as dentine dysplasia, dentinogenesis imperfecta, and osteogenesis imperfecta predispose the dentition to abscess formation. Furthermore, ,spontaneous' dental abscesses are frequently encountered in familial hypophosphataemia, also known as vitamin D-resistant rickets, in which there is hypomineralization of dentine and enlargement of the pulp. In addition to developmental conditions, there are also acquired conditions which may cause unusual dental abscesses. These include pre-eruptive intracoronal resorption which was previously known as ,pre-eruptive caries' or the ,fluoride bomb'. In addition, some undiagnosed infections associated with developing teeth are now thought to be the mandibular infected buccal cysts which originate from infection of the developing dental follicles. In the present paper, these relatively unknown entities which cause unusual abscesses in children are reviewed with the aim of updating the general practitioner in their diagnosis and management. [source] | |||||||||||||||||||||||||