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Electron Microscope Analysis (electron + microscope_analysis)
Kinds of Electron Microscope Analysis Selected AbstractsScanning Electron Microscope Analysis of Internal Adaptation of Materials Used for Pulp Protection under Composite Resin RestorationsJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2005MARIA INEZ LEMOS PELIZ DDS ABSTRACT Purpose:: The aim of this study was to evaluate the interfacial microgap with different materials used for pulp protection. The null hypothesis tested was that the combination of calcium hydroxide, resin-modified glass ionomer, and dentin adhesive used as pulp protection in composite restorations would not result in a greater axial gap than that obtained with hybridization only. Materials and Methods: Standardized Class V preparations were performed in buccal and lingual surfaces of 60 caries-free, extracted human third molars. The prepared teeth were randomly assessed in six groups: (1) Single Bond (SB) (3M ESPE, St. Paul, MN, USA); (2) Life (LF) (Kerr Co., Romulus, MI, USA) + SB; (3) LF + Vitrebond (VT) (3M ESPE) + SB; (4) VT + SB; (5) SB + VT; (6) SB + VT + SB. They were restored with microhybrid composite resin Filtek Z250 (3M ESPE), according to the manufacturer's instructions. However, to groups 5 and 6, the dentin bonding adhesive was applied prior to the resin-modified glass ionomer. The specimens were then thermo-cycled, cross-sectioned through the center of the restoration, fixed, and processed for scanning electron microscopy. The specimens were mounted on stubs and sputter coated. The internal adaptation of the materials to the axial wall was analyzed under SEM with × 1,000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal-Wallis, p V .05). The null hypothesis was rejected. Calcium hydroxide and resin-modified glass ionomer applied alone or in conjunction with each other (p < .001) resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. [source] X-ray diffraction analysis of GaInNAs double-quantum-well structuresJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2004Kiichi Nakashima The structures of GaInNAs/GaAs double-quantum-well (DQW) samples with various well-layer thicknesses were analysed by X-ray diffraction measurements. Two types of rocking-curve analysis were applied with different scanning configurations: a conventional configuration without a receiving slit and one with an analyser crystal placed in front of the receiving detector (the latter is the same as that usually used in reciprocal-space mapping measurements). It was found that systematic combination of both types of analysis is essential for the characterization of the sample structures. The two types of X-ray profiles obtained using the different scanning configurations exhibit a considerable difference in intensity as the thickness of the well layers increases. The increasing difference clearly indicates deterioration of the DQW structures. The two profiles exhibit little difference in terms of shape, merely showing that the DQW layers are coherently strained relative to the substrate. This implies that measurement in only one of the configurations is insensitive to the deterioration and leads to the wrong conclusion that a sample has a perfect structure without dislocations and defects. Photoluminescence and transmission electron microscope analyses both reveal that defects really do exist in the DQW structures, which is consistent with the difference in intensity observed in the X-ray measurements. From these results, a clear picture that consistently explains the sensitivity of X-ray diffraction analysis to the deterioration of samples is presented. In addition, based on this picture, it is proposed that the procedure of comparing the two types of profiles represents a new type of analysis method for the precise characterization of samples. [source] Comparative morphology and evolutionary pathways of the mouthparts in spore-feeding Staphylinoidea (Coleoptera)ACTA ZOOLOGICA, Issue 3 2003Oliver Betz Abstract This study surveys the external morphology of the mouthparts in the guild of spore-feeders among the coleopterous superfamily Staphylinoidea, evaluating the influence of different phylogenetic and ecological starting points on the formation of their mouthparts. Our emphasis is on a scanning electron microscope analysis (SEM) of the involved trophic structures in spore-feeding larvae and adults of the Ptiliidae, Leiodidae and Staphylinidae, describing the fine structure of their main functional elements. Functionally, mouthpart structures resemble brushes, brooms, combs, rakes, rasps, excavators, knives, thorns, cram-brushes, bristle troughs, blocks and differently structured grinding surfaces. Their different involvement in the various aspects of the feeding process (i.e. food gathering, transporting, channelling and grinding) is deduced from our SEM analyses plus direct video observations. We infer five different patterns of food transport and processing, discriminating adults of ptiliids, leiodids plus staphylinids (excluding some aleocharines), several aleocharine staphylinids, and the larvae of leiodids and staphylinids. The structural diversity of the mouthparts increases in the order from (1) Ptiliidae, (2) Leiodidae towards (3) Staphylinidae, reflecting the increasing systematic and ecological diversity of these groups. Comparisons with non-spore-feeders show that among major lineages of staphylinoids, shifts from general microphagy to sporophagy are not necessarily constrained by, nor strongly reflected in, mouthpart morphology. Nevertheless, in several of these lineages the organs of food intake and grinding have experienced particular fine-structural modifications, which have undergone convergent evolution, probably in response to specialized mycophagy such as spore-feeding. These modifications involve advanced galeal rakes, galeal or lacinial ,spore brushes' with arrays of stout bristles, reinforced obliquely ventrad orientated prosthecal lobes and the differentiations of the molar grinding surfaces into stout teeth or tubercles. In addition, several staphylinids of the tachyporine and oxyteline groups with reduced mandibular molae have evolved secondary trituration surfaces, which in some aleocharines are paralleled by considerable re-constructions of the labium,hypopharynx. [source] Differential routing of coexisting neuropeptides in vasopressin neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003Marc Landry Abstract The functional implications of intraneuronal coexistence of different neuropeptides depend on their respective targeting to release sites. In the rat hypothalamic magnocellular neurons, we investigated a possible differential routing of the coexpressed galanin and vasopressin. The respective location of proteins and messengers was assessed with double immunogold and in situ hybridization combining confocal and electron microscope analysis. The various populations of labelled granules were quantitatively compared in three subcellular compartments: perikarya, local processes and posthypophyseal nerve endings. Three subpopulations of granules were detected in all three compartments, but their respective amount showed significant differences. Galanin alone was immunolocalized in some secretory granules, vasopressin alone in others, and both peptides in a third subpopulation of granules. The major part of the granules containing vasopressin, either alone or in association with galanin, is found in neurohypophyseal nerve endings. In contrast, galanin single-labelled granules represent the most abundant population in dendritic processes, while double-labelled granules are more numerous in perikarya. This indicates a preferential distribution of the two peptides in the different compartments of magnocellular neurons. Furthermore, galanin and vasopressin messenger RNAs were detected at different domains of the endoplasmic reticulum, suggesting that translation might also occur at different locations, thus leading to partial segregation of galanin and vasopressin cargoes between two populations of secretory granules. The present study provides, for the first time in mammals, evidence suggesting that galanin and vasopressin are only partly copackaged and undergo a preferential targeting toward dendrites or neurohypophysis, suggesting different functions, autocrine/paracrine and endocrine, respectively. [source] Differential routing of coexisting neuropeptides in vasopressin neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Marc Landry Abstract The functional implications of intraneuronal coexistence of different neuropeptides depend on their respective targeting to release sites. In the rat hypothalamic magnocellular neurons, we investigated a possible differential routing of the coexpressed galanin and vasopressin. The respective location of proteins and messengers was assessed with double immunogold and in situ hybridization combining confocal and electron microscope analysis. The various populations of labelled granules were quantitatively compared in three subcellular compartments: perikarya, local processes and posthypophyseal nerve endings. Three subpopulations of granules were detected in all three compartments, but their respective amount showed significant differences. Galanin alone was immunolocalized in some secretory granules, vasopressin alone in others, and both peptides in a third subpopulation of granules. The major part of the granules containing vasopressin, either alone or in association with galanin, is found in neurohypophyseal nerve endings. In contrast, galanin single-labelled granules represent the most abundant population in dendritic processes, while double-labelled granules are more numerous in perikarya. This indicates a preferential distribution of the two peptides in the different compartments of magnocellular neurons. Furthermore, galanin and vasopressin messenger RNAs were detected at different domains of the endoplasmic reticulum, suggesting that translation might also occur at different locations, thus leading to partial segregation of galanin and vasopressin cargoes between two populations of secretory granules. The present study provides, for the first time in mammals, evidence suggesting that galanin and vasopressin are only partly copackaged and undergo a preferential targeting toward dendrites or neurohypophysis, suggesting different functions, autocrine/paracrine and endocrine, respectively. [source] Swelling properties of CMC- g -poly (AAm- co -AMPS) superabsorbent hydrogelJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009Ali Pourjavadi Abstract A series of biopolymer-based superabsorbent hydrogels based on carboxymethyl cellulose has been prepared by free-radical graft copolymerization of acrylamide and 2-acrylamido-2-methylpropan sulfonic acid (AMPS) in aqueous solution using methylenebisacrylamide as a crosslinking agent and ammonium persulfate as an initiator. The effect of variables on the swelling capacity such as: acrylamide/AMPS weight ratio, reaction temperature, and concentration of the initiator and crosslinker were systematically optimized. The results indicated that with increasing the amount of AMPS, the swelling capacity is increased. FT-IR spectroscopy and scanning electron microscope analysis were used to confirm the hydrogel structure. Swelling measurements of the synthesized hydrogels in different salt solutions indicated considerable swelling capacity. The absorbency under load of the superabsorbent hydrogels was determined by using an absorbency under load tester at various applied pressures. A preliminary swelling and deswelling behaviors of the hydrogels were also studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Biodegradable poly(D,L -lactide) coating of implants for continuous release of growth factorsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 4 2001G. Schmidmaier Abstract Local application of growth factors like insulin like growth factor-I (IGF-I) and transforming growth factor-beta 1 (TGF-,1) from a biodegradable thin layer of poly(D,L -lactide) (PDLLA) coated implants could stimulate fracture healing. A new "cold coating technique" for metallic implants was established to produce a biodegradable coating with a high mechanical stability that provides a continuous release of incorporated growth factors. The properties of this bioactive coating were investigated in vitro and in vivo. Scanning electron microscope analysis revealed a coating thickness of in average 14.8 ,m on titanium and 10.7 ,m on steel wires. Intramedullary implantation and extraction experiments depicted a loss of PDLLA coating from titanium and steel implants of less than 5%. After explantation of the implants, the coating displayed a complete and regular layer without any defects of PDLLA uncovering the metallic surface. Smear tests demonstrate that the coating can be performed under sterile conditions. The PDLLA depicted a reduction of about 8% within 6 weeks in vitro and in vivo. The growth factors were incorporated in a stable form and demonstrated a loss of stability of less than 3% within 42 days and less than 5% within one year. In an elution experiment, 54% IGF-I and 48% TGF-,1 were released within the first 48 h. After 42 days, 76% of IGF-I and 71% of TGF-,1 were detected in the elution fluid by ELISA. Comparable results were obtained in the in vivo experiments after 42 days. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 449,455, 2001 [source] Dynamic Compressive Failure of AlON Under Controlled Planar ConfinementJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2008Bhasker Paliwal An experimental technique is developed to impose a planar lateral confinement in a prismatic specimen (with a rectangular cross section); the setup enabled a controlled and homogeneous stress state with high lateral compressive stresses. A transparent polycrystalline aluminum oxynitride (AlON) specimen was used for the study. The statically precompressed specimen was then subjected to axial dynamic compressive loading using a modified compression Kolsky bar setup. Experimental design was performed using 3D computational modeling. Initial exploratory experiments were conducted on AlON at an average planar confinement of 400,410 MPa; the results suggested a higher compressive strength and a nonlinear stress evolution in AlON due to the confinement. A high-speed camera was used to observe the damage evolution in the specimen during the course of loading. The photographs and stress evolution are suggestive of an additional inelastic deformation mechanism, whose evolution is slower than the typical brittle-cracking type of damage apparent in the unconfined case. The TEM and high-resolution electron microscope analysis indicated dislocation plasticity in some fragments; dislocations in the slip bands were characterized to be dissociated ,110, dislocations on {111} planes. The width between two partial dislocations was about 15 nm, suggesting low stacking fault energy of AlON. Microscopic characterization also shows that the eventual fragmentation of AlON is by cleavage mainly along low-index {111} planes. 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