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PubMed2003

Phase analysis of superconducting polycrystalline MgB(2).

Superconducting MgB(2) ceramics were prepared and yield superconducting transition temperatures of about 39 K. For covering the various length scales on which inhomogeneities appear in MgB(2), electron-probe micro-analysis (EPMA) and analytical transmission electron microscopy (TEM) were applied for a phase analysis. Particularly useful were the preliminary electron spectroscopic imaging (ESI) results in the TEM. It could be shown by EPMA that the microstructure consists of a Mg-B-O matrix and boron-rich secondary phases of composition close to MgB(12). It was unclear in which form oxygen was present in the superconducting matrix. By combining the acquisition of B-K and O-K edge jump ratio images and energy-dispersive X-ray spectroscopy in the TEM, we could prove that the matrix consists of superconducting MgB(2) and MgO. Most of the MgO precipitates and grains appear with diameters between 20 and 300 nm. The size distribution of MgO was inhomogeneous and oxygen-rich areas of dimensions >1 microm were also observed. Edge jump ratio images obtained by ESI were analysed for determining the signal values and effects of multiple inelastic scattering.

Boron Compounds↗
PubMed2002

Comparisons between bone and cementum compositions and the possible basis for their layered appearances.

In humans, age estimation from the adult skeleton represents an attempt to determine chronological age based on growth and maturational events. In teeth, such events can be characterized by appositional growth layers in midroot cementum. The purpose of this study was to determine the underlying cause of the layered microstructure of human midroot cementum. Whether cementum growth layers are caused by changes in relative mineralization, collagen packing and/or orientation, or by variations in organic matrix apposition was investigated by subjecting midroot sections of human canine teeth to analysis using polarized light and scanning electron microscopy (SEM). Polarized light was used to examine transverse midroot sections in both mineralized and demineralized states. Mineralized sections were also reexamined following subsequent decollagenization. Polarized light was additionally used in the examination of mineralized sections taken transversely, longitudinally, and obliquely from the same tooth root. From the birefringence patterns it was concluded that collagen orientation does not change with varying section plane. Instead, the mineral phase was most responsible for the birefringence of the cementum. SEM studies suggested that neither collagen packing nor collagen orientation change across the width of the cementum, confirming and validating the results of the polarized light examination. Also, SEM analysis using electron backscatter and the electron probe suggested no changes in the mean atomic number density, calcium, phosphate, and sulfur levels across the width of the cementum. Therefore, we conclude that crystalline orientation and/or size is responsible for the layered appearance of cementum.

Animals↗
PubMed2002

Physical and magnetic modification of co/pt multilayers by ion irradiation.

The microstructure of Co/Pt multilayers with large perpendicular magnetic anisotropy (PMA) was investigated before and after energetic ion irradiation. No pronounced microstructural changes were detected at ion doses sufficient to completely reduce the PMA and cause a spin reorientation transition to in-plane. Ion-induced displacement of Co and Pt atoms near Co/Pt interfaces lead to local "roughening" and Co layer strain relaxation, reducing the PMA. The magnetic domain confinement induced by ion irradiation and magnetic patterning by selective ion irradiation were also investigated.

Alloys↗
PubMed2004

Nanoscale precipitation in a maraging steel studied by APFIM.

This article summarizes findings from our previous investigations and recent studies concerning precipitation in a maraging steel of type 13Cr-9Ni-2Mo-2Cu (at.%) with small additions of Ti (1 at.%) and Al (0.7 at.%). The material was investigated after aging at 475 degrees C up to 400 h using both conventional and three-dimensional atom-probe analyses. The process of phase decomposition in the steel proved to be complicated. It consisted of precipitation of several phases with different chemistry. A Cu-rich phase was first to precipitate and Mo was last in the precipitation sequence. The influence of the complex precipitation path on the material properties is discussed. The investigation clearly demonstrated the usefulness of the applied techniques for investigation of nanoscale precipitation. It is also shown that, complementary methods (such as TEM and EFTEM) giving structural and chemical information on a larger scale must be applied to explain the good properties of the steel after prolonged aging.

Alloys↗
PubMed2005

Mineralogy of air-pollution-control residues from a secondary lead smelter: environmental implications.

The mineralogy and solubility of air-pollution-control (APC) residues from a secondary lead (Pb) smelter have been studied on samples from the Príbram smelter, Czech Republic, recycling car batteries, with the emphasis on their potential environmental effect. The presence of dominant anglesite (PbSO4) and laurionite (Pb(OH)Cl) was observed in a sintered residue from after-burning chambers (800-1000 degrees C). In contrast, low-temperature Pb-bearing phases, such as KCl x 2PbCl2 and caracolite (Na3Pb2(SO4)3Cl), were detected in the major APC residue from bag-type fabric filters. Metallic elements, zinc (Zn), cadmium (Cd), and tin (Sn) were found homogeneously distributed within this residue. The formation of anglesite, cotunnite (PbCl2), (Zn,Cd)2SnO4, and (Sb,As)2O3 was observed during the sintering of this APC residue at 500 degrees C in a rotary furnace. The 168 h leaching test on filter residue, representing the fraction that may escape the flue gas treatment system, indicated rapid release of Pb and other contaminants. Caracolite and KCl x 2PbCl2 are significantly dissolved, and anglesite and cotunnite form the alteration products, as was confirmed by mineralogical analysis and PHREEQC-2 modeling. The observed Pb-bearing chlorides have significantly higher solubility than anglesite and, following emission from the smelter stack, can readily dissolve, transferring Pb into the environmental milieu (soils, water, inhabited areas).

Air Pollutants↗
PubMed1997

Fractal analysis of beta-cyclodextrin-indomethacin particles compacted by ultrasound.

An association between indomethacin and beta-cyclodextrin (beta-CD) was obtained by compacting a 1:2 molar physical mixture by ultrasound. The product prepared by this technique was compared with the initial physical mixture and with materials having the same composition but prepared by a simple compaction and kneading process. The samples examined by scanning electron microscopy revealed morphological differences related to the methods of preparation. In particular the material obtained by ultrasound had a smooth surface and on milling produced particles of uniform size; moreover EDAX analysis (energy dispersion analysis by X-rays) also revealed a homogeneous distribution of the two components in each particle examined. Surface fractal dimension of the surface of these particles is very low, suggesting the presence of a regular and smooth surface whereas the sample obtained by kneading had a higher value. The reactive dimension related to dissolution was much higher than the corresponding surface dimension in all cases and had comparable values for all samples regardless of the techniques used. This behavior was attributed to the hydrophilicity of beta-CD, which levels the differences during dissolution and which could be originated by surface imperfections. Experimental results suggested that the material obtained by ultrasound had a dissolution rate comparable to that measured with the kneaded material. The use of ultrasound, however, can both reduce the production time and improve the homogeneity of the association between indomethacin and beta-CD.

Cyclodextrins↗
PubMed1996

A pilot study comparing screw-shaped implants. Surface analysis and histologic evaluation of bone healing.

The purpose of this study was to compare surface treatment and bone formation adjacent to 2 screw shaped implants of similar design manufactured by two different companies. The test implants were manufactured by SERF (Decines, France), while the controls were manufactured by Nobelpharma (Goteborg, Sweden). The surface of 3 standard 3.75 mm test and 3 standard 3.75 mm control implants were investigated by means of scanning electron microscopy (SEM), X-ray micro-analysis, electron spectroscopy for chemical analysis (ESCA) and surface topography analysis. There was a microscopic difference on the thread design (SEM). Test threads were flat at the edge, while controls appeared rounded at the edge of the threads. Tests and controls were made of commercially pure titanium, with a regular topography. Results of ESCA indicated that the carbon peak for SERF implants was slightly higher than for the Brånemark implants. 5 test and 5 control implants were installed into the epiphyseal head of the femur of 2 ewes using a standardized surgical technique. In order to stain the bone for histologic analysis, oxytetracycline injections were given 17 and 8 days before the animals were sacrificed. The animals were sacrificed 12 weeks after implant placement. Histomorphometric analysis indicated that there was an average bone to implant contact orf 68% for the test implants and 61% for the controls. There were no statistical differences between tests and controls. The preliminary results of this pilot study indicated that early bone healing for the 2 screw shaped implants investigated were similar.

Animals↗
PubMed2000

The reliability of cryoSEM for the observation and quantification of xylem embolisms and quantitative analysis of xylem sap in situ.

The reliability of cryoSEM for visualizing gas embolisms in xylem vessels of intact, functioning roots is examined and discussed. The possibility that these embolisms form as a result of freezing water columns under tension is discounted by a double-freeze experiment. Two regions of the same root, one frozen under tension, the other isolated from the tension by the first freeze, had the same percentage of embolisms, as did also long pieces of root frozen simultaneously along their length. The reliability of energy-dispersive X-ray analysis to measure xylem sap concentration in situ in frozen tissue was established by measurement of KCl standard solution frozen on stubs, and within xylem vessels. Solute heterogeneity within the vessels varied with freezing procedure; deep-freeze > LN2 > cryopliers > liquid ethane, but only the deep-freeze method gave unsatisfactory estimates of concentration for the standard solution. It is concluded that cryoanalytical SEM is useful for direct observation of gas and liquid-filled compartments, and for solute analyses at depth within intact plant organs.

Cryoelectron Microscopy↗
PubMed2001

Microstructural investigations of strain-related collagen mineralization.

Distraction osteogenesis in rabbit mandibles after osteotomy can be used as an experimental model to study the microstructural features of mineralization of callus under defined mechanical loads. Our aim was to study the relation between the micromotions in the gap and the resulting features of mineralization of the matrix. We found that assembly of collagen and formation of crystals depended on the magnitude of the mechanical stress applied. At physiological bone strains (2000 microstrains), the callus had collagen type I in a mature bone-like extracellular arrangement, whereas at 20000 microstrains bundles were orientated predominantly towards the tension vector. Maximum loads (200000 microstrains) resulted in disorganized assembly of the collagen. Quantitative energy-dispersive analysis by X-rays confirmed that high strains were associated with substantially lower concentrations of calcium and phosphate. In contrast to bone-like apatitic formation of crystals at physiological strains, significantly fewer but larger crystals were detected by electron diffraction analysis in samples exposed to high strains. We suggest that mechanical stress regulates the assembly and mineralization of collagen during distraction osteogenesis.

Animals↗
PubMed1997

Analytical and ultrastructural studies of pellicle on primary teeth.

The pellicle on permanent enamel has been thoroughly studied. The aims of this study were to compare the chemical composition, rate of formation, and ultrastructural appearance of pellicle formed on deciduous enamel in children with those on permanent teeth. This was done by amino acid analyses, Auger analyses, and transmission electron microscopy. The amino acid composition of 2-h pellicle on deciduous and permanent enamel had an overall similar pattern, but the contents of serine, glycine, and tyrosine were statistically significantly different. An initially slower pellicle formation and a thinner 2-h pellicle without a globular structured second layer was observed on deciduous enamel. The results indicated therefore distinct differences in chemical composition, rate of formation, and ultrastructural appearance between pellicle on primary teeth and that on permanent teeth.

Amino Acids↗
PubMed2005

Interface evaluation after manual and ultrasonic insertion of standardized class I inlays using composite resin materials of different viscosity.

OBJECTIVE: The aim of the present study was to investigate the effect of manual and ultrasonic insertion of standardized class I inlays (Cerana) using three composite resin materials of different viscosity (Tetric Flow, Tetric, and Tetric Ceram) on time to seat inlays, film thickness, and filler distribution within the materials. METHODS: In a preliminary test, mean loads for manual and ultrasonic insertion were measured using the high viscosity composite resin material (Tetric Ceram). These loads were then applied with all composite resin materials to evaluate the times required to seat the inlays. In addition, film thickness was assessed using scanning electron microscopy, and filler distribution (wt% silicon, barium, ytterbium) was monitored using energy-dispersive spectroscopy. RESULTS: Ultrasonic insertion significantly reduced mean load applied to seat inlays (6.4+/-1.4 N; mean+/-SD) as compared to manual insertion (18.9+/-3.1 N; p < 0.001). Using an ultrasonic device, times for insertion values were significantly lower in the high and medium viscosity composite resin material groups compared to manual insertion (p < 0.05). The widest film thickness was recorded for the high viscosity composite resin material in combination with manual insertion (p < 0.05). However, when ultrasound was applied, there was no difference in film thickness between the three materials at any levels. Furthermore, the analysis of filler distribution revealed no significant differences between groups. CONCLUSION: Highly filled viscous composite resin materials may be used in combination with the ultrasonic insertion technique without untoward effects on film thickness or filler distribution.

Barium↗
PubMed2006

A methodology for evaluating biocide release rate, surface roughness and leach layer formation in a TBT-free, self-polishing antifouling coating.

Due to the forthcoming IMO ban on the use of tributyltin (TBT) antifouling paints, a new generation of TBT-free coatings has been developed that typically contain cuprous oxide and an organic co-biocide. Accurate and reproducible test methods are needed to evaluate the performance and environmental impact of these new coatings. This study investigated a methodology for evaluating TBT-free, AF coatings containing cuprous oxide. A commercially available AF coating underwent rotary immersion testing at 0, 0.51 and 2.05 m s-1. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis were used to assess leach layer formation, percentage cuprous oxide by weight and particle size distribution (PSD). Biocide release rates and surface roughness were also measured. An increase in rotary speed caused a spike in Cu2+ release rate after which the release rate stabilised to previous levels. An increase in leach layer thickness was also observed after the rotary speed increase. A model is suggested to account for the observations.

Copper↗
PubMed1979

High resolution microchemical analysis using soft X-ray lithographic techniques.

High resolution x-ray lithographic studies of cells from chick embryo hearts dried by the CO2 critical point method have been made with soft x-ray radiation of different wavelengths. A marked difference in the relief replica in polymethyl methacrylate (PMMA) resulting from the differential absorption by the dried cells of carbon K alpha radiation at 4.48 nm and broad band synchrotron radiation (SR) with lambda is greater than 1.5 nm demonstrates the potential usefulness of the technique in making high resolution (approximately or equal to 10 nm) chemical identification of the constitutents which make up the various parts of the cell.

Animals↗
PubMed2001

Effects of erbium, chromium:YSGG laser irradiation on root surface: morphological and atomic analytical studies.

OBJECTIVE: The purpose of this study was to investigate the morphological and atomic changes on the root surface by stereoscopy, field emission-scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (SEM-EDX) after erbium, chromium:yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser irradiation in vitro. SUMMARY BACKGROUND DATA: There have been few reports on morphological and atomic analytical study on root surface by Er,Cr:YSGG laser irradiation. METHODS: Eighteen extracted human premolar and molar teeth were irradiated on root surfaces at a vertical position with water-air spray by an Er,Cr:YSGG laser at the parameter of 5.0 W and 20 Hz for 5 sec while moving. The samples were then morphologically observed by stereoscopy and FE-SEM and examined atomic-analytically by SEM-EDX. RESULTS: Craters having rough but clean surfaces and no melting or carbonization were observed in the samples. An atomic analytical examination showed that the calcium ratio to phosphorus showed no significant changes between the control and irradiated areas (p > 0.01). CONCLUSIONS: These results showed that the Er,Cr:YSGG laser has a good cutting effect on root surface and causes no burning or melting after laser irradiation.

Calcium↗
PubMed1986

Bladder granulomata after bladder surgery.

Bladder granulomata were found in 17 (3%) of 539 patients who had bladder biopsy or resection. The finding of granulomata in 13.6% of patients who had at least two surgical procedures, but never in the first biopsy specimen of any patient was highly significant statistically (P much less than 0.001). The occurrence of granulomata exclusively in patients with bladder carcinoma was related to the significantly greater number of biopsies performed in these patients and not to carcinoma, per se. There were two types of granulomata: necrotizing, palisading granulomata (NPG) resembling rheumatoid granulomata; and foreign-body-type granulomata (FBG). They often occurred together in the same specimen, and transitions from FBG to NPG were evident histologically. The granulomata apparently healed by fibrous scarring. Energy-dispersive analysis of x-rays (EDAX) did not reveal any inorganic foreign material, but showed sulphur in some granulomata, possibly released from necrotic stroma and urothelium. Clinical and morphologic evidence is presented indicating that the granulomata arose as a local reaction to tissue necrosis caused by surgery and/or cautery.

Biopsy↗
PubMed2002

Aluminum chloride induces retinal changes in the rat.

We studied rat retinal changes due to aluminum (Al) toxicosis with a transmission electron microscope (TEM) and an energy dispersive X-ray analyzer (EDXA). Normal 4-week-old Wistar Kyoto rats were divided randomly into Al toxicosis and control groups. The Al toxicosis group was injected ip with 0.3 ml of 4% aluminum chloride (AlCl3) per day every day for 16 weeks. The retina was examined with a TEM and EDXA at 8, 12, and 16 weeks after starting injections with AlCl3. There was a statistically significant increase in the serum Al concentration in the Al toxicosis group (p < 0.001). We observed prominent pathologic changes at 16 weeks after the first injections. Thin retinal pigment epithelium (RPE), and disappearance of the photoreceptor outer and inner segments and nuclei were observed. There were high-density irregular granules in the outer and inner plexiform layers and in the inner nuclear layer. We found dense granules in the cells, which remained between the RPE and the inner nuclear layer. EDXA detected Al in the high-density irregular granules in these areas. Al injected ip caused accumulation of Al in the rat retina and the destruction of photoreceptor cells. These findings indicate that Al is toxic to the retina.

Aluminum Chloride↗
PubMedDate not supplied

Uptake of iodinated contrast material by the ischemically damaged myocardial cell.

Computerized transmission tomography has shown differential contrast enhancement of the area of ischemic damage after intravenous administration of iodinated contrast material. The current study performed in normal dogs and dogs with two-day-old and 30-day-old myocardial infarctions was intended to determine if the iodine accumulation is intracellular. Scanning electron microscopy with energy dispersive x-ray analysis detected iodine peaks associated with the cells in areas of ischemic damage, while iodine peaks were not detected in normal myocardium. Energy spectra in the area of ischemic damage showed a significant increase in the Na+ -K+ ratio compared to normal myocardium, consistent with the loss of cellular membrane integrity in this region. Results were similar for both two- and 30-day-old infarcts. These results indicate that iodinated contrast material attaches to the membrane of enters the ischemically damaged cell, but is virtually excluded from the normal myocardial cell. It may serve as a marker of myocardial cells which have lost cellular membrane integrity after an ischemic insult.

Animals↗