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Electron Microscope Observation (electron + microscope_observation)
Kinds of Electron Microscope Observation Selected AbstractsPalaeointensity and palaeodirectional studies of early Riphaean dyke complexes in the Lake Ladoga region (Northwestern Russia)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2008V. V. Shcherbakova SUMMARY Results of palaeointensity and palaeomagnetic studies for the volcanic rocks of 1450 Ma, from Early Riphaean Baltic shield dyke complex sampled in Lake Ladoga region (Karelia, Northwestern Russia) are reported. Electron microscope observations, thermomagnetic and hysteresis measurements indicate the presence of single domain (SD) to pseudo-single domain (PSD) titanomagnetite (TM) with low Ti content as the main magnetic mineral. Stepwise alternating field (AF) and/or thermal demagnetization revealed a two-component natural remanent magnetization (NRM) for most of the samples. The characteristic remanent magnetization (ChRM) component was isolated between 440 and 590 °C. Note that the ChRM amounts to 95 per cent of the NRM intensity. The geographic position of the ChRM palaeopoles does not contradict the ,key poles' of the [1270; 1580] Myr time interval, testifying anticlockwise rotation of whole East Europe Craton between 1450 and 1500 Ma. Palaeointensity determinations were performed by Coe-modified Thellier procedure. 35 samples passed our palaeointensity selection criteria and show large linear segments on Arai-Nagata plots. The site mean virtual dipole moment (VDM) varies from 2.00 to 3.91 (× 1022 A m2). Based on these and other observations, we suggest that the Palaeo- and MezoProterozoic was dominated by low VDMs. [source] Palaeomagnetic and rock-magnetic studies of Cretaceous rocks in the Gongju Basin, Korea: implication of clockwise rotationGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2002Seong-Jae Doh Summary Palaeomagnetic and rock-magnetic studies have been carried out for Cretaceous non-marine sedimentary rocks (Gongju Group) and volcanic rocks in the Gongju Basin, located along the northern boundary of the Ogcheon Belt, Korea. K,Ar age dating for the volcanic rocks was also performed. It is found that the Gongju Group was remagnetised during the tilting of the strata with the characteristic remanent magnetisation (ChRM) direction of at 30 per cent untilting of the strata with a maximum value of precision parameter (k), while the volcanic rocks are revealed to acquire primary remanence with the direction of after the tilt-correction. The K,Ar ages of the volcanic rocks range from 81.8 ± 2.4 to 73.5 ± 2.2 Ma, corresponding to the Campanian stage of the Late Cretaceous. Electron microscope observations of samples from the Gongju Group show authigenic iron-oxide minerals of various sizes distributed along the cleavage of chlorite and in the pore spaces, indicating that the strata acquired the chemical remanent magnetisation due to the formation of secondary magnetic minerals under the influence of fluids. The palaeomagnetic pole positions are at Lat./Long. = 69.6°N/224.3°E (dp= 3.5°, dm= 5.2°) calculated for the 30 per cent tilt-corrected direction of the Gongju Group and at for the volcanic rocks. Based on the results of this study, it is interpreted that the volcanic rocks acquired the primary magnetisation almost at the same time as the remagnetisation of the Gongju Group in the Late Cretaceous. Comparisons of Cretaceous palaeomagnetic poles from the Korean Peninsula with those from Eurasia implies that the Korean Peninsula underwent clockwise rotation of 21.2°± 5.3° for the middle Early Cretaceous, 12.6°± 5.4° for the late Early Cretaceous, and 7.1°± 9.8° for the Late Cretaceous with respect to Eurasia, due to the sinistral motion of the Tan-Lu Fault. [source] Spray Pyrolysis of Fe3O4,BaTiO3 Composite ParticlesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2009Tomoyuki Adachi Fe3O4,BaTiO3 composite particles were successfully prepared by ultrasonic spray pyrolysis. A mixture of iron(III) nitrate, barium acetate and titanium tetrachloride aqueous solution were atomized into the mist, and the mist was dried and pyrolyzed in N2 (90%) and H2 (10%) atmosphere. Fe3O4,BaTiO3 composite particle was obtained between 900° and 950°C while the coexistence of FeO was detected at 1000°C. Transmission electron microscope observation revealed that the composite particle is consisted of nanocrystalline having primary particle size of 35 nm. Lattice parameter of the Fe3O4,BaTiO3 nanocomposite particle was 0.8404 nm that is larger than that of pure Fe3O4. Coercivity of the nanocomposite particle (390 Oe) was much larger than that of pure Fe3O4 (140 Oe). These results suggest that slight diffusion of Ba into Fe3O4 occurred. [source] Onychomycosis caused by Alternaria spp. in Tuscany, Italy from 1985 to 1999MYCOSES, Issue 3-4 2001C. Romano Alternaria alternata; Alternaria chlamidospora; Nagelinfektionen; Itraconazol. Summary. Cutaneous phaeohyphomycosis due to Alternaria spp. is reported with increasing frequency, especially in patients with immune deficiency. Onychomycosis caused by this mould is still rarely observed. Here we report nine cases observed in Tuscany in the period 1985,99; the agent was Alternaria alternata in eight cases and Alternaria chlamidospora in one. Diagnosis was made on the basis of repeated direct microscopic mycological examination and culture, confirmed by scanning electron microscope observation of fragments of colonies. In most cases, the clinical manifestations were dystropy and distal subungual hyperkeratosis of one or two nails of the feet or hands. Seven cases were treated with oral itraconazole, successfully in six cases, as clinical and mycological recovery was confirmed at follow-up 1 year later. Zusammenfassung. Kutane Phaeohyphomykosen durch Alternaria spp. werden immer häufiger beschrieben, besonders bei Patienten mit gestörter Infektabwehr. Andererseits sind Onychomykosen durch diese Pilzerreger nur selten zu beobachten. Wir berichten über 9 Fälle von Onychomykosen durch Alternaria spp., die innerhalb eines Zeitraums von 14 Jahren (1985,99) beobachtet worden sind. In 8 Fällen wurde Alternaria alternata und in einem Fall Alternaria chlamidospora isoliert. Die Diagnose wurde nach wiederholtem Nachweis der selben Spezies sowohl in Nativpräparaten als auch in Kultur gestellt und durch elektromikroskopische Untersuchungen der Kolonien bestätigt. Klinisch waren in den meisten Fällen dystrophische Veränderungen und distale subunguale Onychomykose an einem oder mehreren Finger- oder Fußnägeln zu beobachten. 7 Patienten wurden systemisch mit Itraconazol behandelt. In 6 dieser Fälle wurde eine klinische und mykologische Heilung erzielt. Während einjähriger Nachbeobachtungzeit blieben die Patienten rezidivfrei. [source] RF-MBE growth of InN on 4H-SiC (0001) with off-anglesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010Misao Orihara Abstract We have grown InN on 4H-SiC (0001) substrates with various off-angles by RF-N2 plasma molecular beam epitaxy (RF-MBE). Scanning electron microscope observation revealed that InN films grown on 4H-SiC (0001) substrates with off-angles of 4° and 8° are very smooth and that there are no voids which have often observed for InN epitaxial layers. X-ray diffraction reciprocal space maps for InN grown on 4H-SiC (0001) showed that the c-axes of InN grown on 4H-SiC 4° and 8° off substrates are inclined by 0.35° and 0.8°, respectively, toward the misorientation of the substrate while the c-axis of InN is parallel to that of 4H-SiC for the on-axis substrate. Strong PL peak was observed from InN grown on 4° off substrate at 0.68 eV at 15 K. The PL peak was clearly observed even at room temperature and simply shifted to lower energies with increasing temperature. The difference in the PL peak energy between at 15 K and 300 K was 20 meV, which is reasonable taking into account the difference in the thermal coefficients of InN and SiC (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mechanical and dynamic mechanical properties of nylon 66/montmorillonite nanocomposites fabricated by melt compoundingPOLYMER INTERNATIONAL, Issue 8 2004Zhong-Zhen Yu Abstract Nylon 66 nanocomposites were prepared by melt compounding of nylon 66 with organically modified montmorillonite (MMT). The organic MMT was pre-modified with about 14 wt% of ammonium surfactant, much lower than the 35,46 wt% in most commercial organic MMT powders. Transmission electron microscope observation indicated that the MMT layers were well exfoliated in nylon 66 matrix. Dynamic mechanical analysis confirmed the constraint effect of exfoliated MMT layers on nylon 66 chains, which benefited the increased storage modulus, increased glass transition temperature and reduced magnitude of alpha relaxation peak. The effects of organic MMT loading levels on reinforcement and fracture behaviour of the nanocomposites were evaluated using tensile and three-point bending tests. The addition of the organic MMT clearly increased Young's modulus and tensile strength but decreased ductility and fracture toughness of nylon 66. Copyright © 2004 Society of Chemical Industry [source] Synthesis and Characterization of Nanostructured Manganese Dioxide Used as Positive Electrode Material for Electrochemical Capacitor with Lithium Hydroxide ElectrolyteCHINESE JOURNAL OF CHEMISTRY, Issue 1 2008An-Bao YUAN Abstract A nanostructured manganese dioxide electrode material was prepared using a solid-reaction route starting with MnCl2·4H2O and NH4HCO3, and its electrochemical performance as a positive electrode for MnO2/activated carbon hybrid supercapacitor with 1 mol·L,1 LiOH electrolyte was reported. The material was proved to be a mixture of nanostructured , -MnO2 and , -MnO2 containing some bound water in the structure, which was characterized by X-ray diffraction analysis, infrared spectrum analysis, and transmission electron microscope observation. Electrochemical properties of the MnO2 electrode and the MnO2/AC capacitor were investigated by cyclic voltammetry, ac impedance and galvanostatic charge/discharge methods. Experimental results showed that the MnO2 electrode exhibited faradaic pseudocapacitance behavior and higher specific capacitance in 1 mol·L,1 LiOH electrolyte. The MnO2/AC hybrid capacitor with 1 mol·L,1 LiOH electrolyte presented excellent rate charge/discharge ability and cyclic stability. [source] d -Alanyl ester depletion of teichoic acids in Lactobacillus reuteri 100-23 results in impaired colonization of the mouse gastrointestinal tractENVIRONMENTAL MICROBIOLOGY, Issue 7 2007Jens Walter Summary The dlt operon of Gram-positive bacteria encodes proteins required for the incorporation of d -alanine esters into cell wall-associated teichoic acids (TA). d -Alanylation of TA has been shown to be important for acid tolerance, resistance to antimicrobial peptides, adhesion, biofilm formation, and virulence of a variety of pathogenic organisms. The aim of this study was to determine the importance of d -alanylation for colonization of the gastrointestinal tract by Lactobacillus reuteri 100-23. Insertional inactivation of the dltA gene resulted in complete depletion of d -alanine substitution of lipoteichoic acids. The dlt mutant had similar growth characteristics as the wild type under standard in vitro conditions, but formed lower population sizes in the gastrointestinal tract of ex- Lactobacillus -free mice, and was almost eliminated from the habitat in competition experiments with the parental strain. In contrast to the wild type, the dlt mutant was unable to form a biofilm on the forestomach epithelium during gut colonization. Transmission electron microscope observations showed evidence of cell wall damage of mutant bacteria present in the forestomach. The dlt mutant had impaired growth under acidic culture conditions and increased susceptibility to the cationic peptide nisin relative to the wild type. Ex vivo adherence of the dlt mutant to the forestomach epithelium was not impaired. This study showed that d -alanylation is an important cell function of L. reuteri that seems to protect this commensal organism against the hostile conditions prevailing in the murine forestomach. [source] Relationships between the olive fly and bacteriaJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2008P. Sacchetti Abstract The relationship between the olive fly population and epiphytic bacteria of the olive tree was investigated by carrying out a 1-year survey in the field. The olive fly population affected the number of bacteria present on the olive surface. Scanning electron microscope observations demonstrated that bacteria may be ingested by the fly's mouth apparatus through the midline of the pseudotracheae. DNA amplification of the oesophageal bulb content using 16S bacteria universal primers and DNA sequencing evidenced that Candidatus Erwinia dacicola was the predominant species present. The role of bacteria in olive fly biology is discussed. [source] Schmeissneria: An angiosperm from the Early JurassicJOURNAL OF SYSTEMATICS EVOLUTION, Issue 5 2010Xin WANG Abstract, The origin of angiosperms has been a focus of intensive research for a long time. The so-called pre-Cretaceous angiosperms, including Schmeissneria, are usually clouded with doubt. To expel the cloud around the enigmatic Schmeissneria, the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied. These materials include female inflorescences and infructescences. The latter are old materials but were under-studied previously. Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed, and that the ovaries are closed before pollination. Thus the plants meet two strict criteria for angiosperms: angiospermy plus angio-ovuly. Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic, more compatible with many molecular dating conclusions on the age of angiosperms, and demanding a reassessment of the current doctrines on the origin of angiosperms. Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question, this study adds to research concerning the origin of angiosperms. [source] Surface alteration of Saccharomyces cerevisiae induced by thymol and eugenolLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2004S. Bennis Abstract Aims:, This study aims to bring some information about the mechanism of the fungicidal action of thymol and eugenol; phenolic major components of thyme and clove essential oils respectively. Saccharomyces cerevisiae was used as yeast model. Methods and Results:, Treatment of yeast cells with these components led to their lysis as shown by the release of substances absorbing at 260 nm. In addition, scanning electron microscope observations revealed that the surface of the treated cells was significantly damaged. Conclusions:, Antifungal activity of thymol and eugenol involve alteration of both membrane and cell wall of the yeast. Significance and Impact of the Study:, This work is a preliminary contribution aiming to develop a new generation of efficient and natural antifungal agents. [source] Awns play a dominant role in carbohydrate production during the grain-filling stages in wheat (Triticum aestivum)PHYSIOLOGIA PLANTARUM, Issue 4 2006Xiaojuan Li In wheat (Triticum aestivum L), the leaves particularly flag leaves have been considered to be the key organs contributing to higher yields, whereas awns have been considered subsidiary organs. Compared with extensive investigations on the assimilation contribution of leaves, the photosynthetic characteristics of awns have not been well studied. In this study, we investigated the ultrastructure of chloroplasts, oxygen evolution, and phosphoenolpyruvate carboxylase [phosphoenolpyruvate carboxylase (PEPCase) EC 4.1.1.31)] activity in both flag leaves and awns during the ontogenesis of wheat. Transmission electron microscope observations showed initial increases in the sizes of grana and the degree of granum stacks from the florescence-emergence stage both in flag leaves and in awns, followed by the breakdown of membrane systems after the milk-development stage. The results of oxygen evolution assays revealed that in both organs, the rate of photosynthesis increased in the first few stages and then decreased, but the decrease occurred much earlier in flag leaves than in awns. A PEPCase activity assay demonstrated that the activity of PEPCase was much higher in awns than in flag leaves throughout ontogeny; the value was particularly high at the late stages of grain filling. Our results suggest that awns play a dominant role in contributing to large grains and a high grain yield in awned wheat cultivars, particularly during the grain-filling stages. [source] | |||||||||||||