An alkaline hydrolysate of Bacillus thuringiensis var kurstaki HD1 (Btk) parasporal crystals was administered at 25 micrograms ml-1 (f.c.) to isolated, short-circuited, midguts of tobacco hornworm (Manduca sexta) larvae. The short-circuit current (s.c.c.), a precise measure of K+ active transport, was inhibited by 78% in 10 min in Btk-treated midguts as compared to controls. The elemental concentrations of K, together with Na, Mg, P, S, Cl and Ca, as well as the water content, were determined by electron probe X-ray microanalysis (EPXMA) in the muscle cells, columnar cells and goblet cells, as well as in the extracellular goblet cavity and the bathing media. The average K concentration in the goblet cell cavity was 129 mmol/kg wet wt in control midguts but only 37 mmol/kg wet wt in Btk-treated midguts. The elemental concentrations, including that of K, in other cell compartments were much less affected by Btk, but a rise in total cell calcium is suggested. It has been previously suggested that ...
Immobilized cells of a Citrobacter sp. can remove heavy metals from wastewaters by deposition ofmetals with enzymatically liberated phosphate. Nickel is not removed effectively by this technique, but Ni2+ can be intercalated into cell-bound, crystalline HUO2PO4 previously deposited enzymatically. This technique for efficient removal of Ni from solution has been generically termed microbially enhanced chemisorption of heavy metals(MECHM). The nickel uranyl phosphate deposits bound to Citrobactersp. cells immobilized in polyacrylamide gel (FAG) were analyzed using scanning transmission electronmicroscopy with electron probe X-ray microanalysis (EPXMA) and proton-induced X-ray emissionanalysis(PIXE). Both methods gave the molar ratios of nickel, uranium, and phosphorus in the depositsas close to 1:2:2 in all analyzed parts of the sample. EPXMA proved that the deposits were localized onthe surface of cells inside FAG particles as well as those immobilized on the edge. Small deposits ofnickel uranyl ...
The use of strontium-to-calcium (Sr/Ca) ratios in otoliths is becoming a standard method to describe life history type and the chronology of migrations between freshwater and seawater habitats in teleosts (e.g. Kalish, 1990; Radtke et al., 1990; Secor, 1992; Rieman et al., 1994; Radtke, 1995; Limburg, 1995; Tzeng et al. 1997; Volk et al., 2000; Zimmerman, 2000; Zimmerman and Reeves, 2000, 2002). This method provides critical information concerning the relationship and ecology of species exhibiting phenotypic variation in migratory behavior (Kalish, 1990; Secor, 1999). Methods and procedures, however, vary among laboratories because a standard method or protocol for measurement of Sr in otoliths does not exist. In this note, we examine the variations in analytical conditions in an effort to increase precision of Sr/Ca measurements. From these findings we argue that precision can be maximized with higher beam current (although there is specimen damage) than previously recommended by Gunn et...
Amount:5.0000,CurrencyCode:GBP,DonationDate:2017-07-06T07:39:38,DonorDisplayName:Kaoru Adachi,DonorLocalAmount:5.0000,DonorLocalCurrencyCode:GBP,EstimatedTaxReclaim:0.0000,ImageUrl:http://images.justgiving.com/image/f9cfb620-15b4-4c31-a934-6ce9b4eac0d9.jpg?template=profilesummary,Message:Great collection!},{Amount:10.0000,CurrencyCode:GBP,DonationDate:2016-08-02T04:18:28,DonorDisplayName:Suzanne Burke,DonorLocalAmount:10.0000,DonorLocalCurrencyCode:GBP,EstimatedTaxReclaim:0.0000,ImageUrl:https://www.justgiving.com/content/images/graphics/icons/avatars/facebook-avatar.gif,Message:Excellent online information for my students!},{Amount:5.0000,CurrencyCode:GBP,DonationDate:2016-11-17T08:56:35,DonorDisplayName:Katja ...
Scanning electron microscopy of lung tissue, ashed at low temperature, and obtained from an insulation worker who had died of pleural mesothelioma, showed the presence of numerous inorganic particles and fibres. A regional variation in fibre concentration in different tissue samples was found, and the size distribution of naked fibres and asbestos bodies was determined. By energy dispersive x-ray microanalysis the fibres were identified mainly as amphibole asbestos. This method also showed the presence of particles containing titanium and of fragments of diatom shells. Despite a mean concentration of 33 x 10(6) fibres per gram of dry tissue no significant lung fibrosis was found.. ...
Abstract Cryosections of human red blood cells infected by Plasmodium falciparum were analyzed by energy dispersive x-ray microanalysis to determine the elemental composition of the parasites and their red cell hosts separately. The effects of two antimalarial drugs, qinghaosu and chloroquine, on potassium, sodium, and phosphorus concentrations were studied. Malarial infection causes a decrease in potassium concentration and an increase in sodium concentration in the host red cells. The drastic change in the cation composition, however, occurs only in red cells infected by late stage parasites (late trophozoite and schizont). Red cells infected by early stage parasites (ring stage) show only small changes in sodium concentration. Furthermore, the noninfected red cells in parasitized cultures show no difference in composition from those of normal red cells. Treatment of the parasitized cultures with qinghaosu (10-6 M) or chloroquine (10-6 M) for 8 hr causes phosphorus concentration of both early and late
Objective: Evidence suggests that abnormal iron metabolism is associated with Parkinson disease (PD), with raised iron levels found in pathologically affected areas in PD. It is unknown if this elevated iron is actually associated with neurons or reactive glia, and we therefore addressed this issue by determining if raised iron was present in single dopaminergic neurons.. Methods: We used unfixed frozen sections from postmortem tissue of PD patients and elderly normal individuals to avoid metal contamination and translocation. Levels of iron and other elements were measured using sensitive and specific wavelength dispersive electron probe x-ray microanalysis coupled with cathodoluminescence spectroscopy in individual substantia nigra dopaminergic neurons.. Results: We identified raised intraneuronal iron in single defined substantia nigra neurons in PD (mean neuronal iron 2,838 vs 1,611, p , 0.0001) but not in other movement disorders such as Huntington disease. These findings were unrelated to ...
Refractory-based high entropy alloys (HEAs) of the 2nd-generation type are new intensively-studied materials with a high potential for structural high-temperature applications. This paper presents investigation results on microstructural evolution and phase formation in as-cast and subsequently heat-treated HEAs at various temperature-time regimes. Microstructural examination was performed by means of scanning electron microscopy (SEM) combined with the energy dispersive spectroscopy (EDS) mode of electron probe microanalysis (EPMA) and qualitative X-ray diffraction (XRD). The primary evolutionary trend observed was the tendency of Zr to gradually segregate as the temperature rises, while all the other elements eventually dissolve in the BCC solid solution phase once the onset of Laves phase complex decomposition is reached. The performed thermodynamic modelling was based on the Calculation of Phase Diagrams method (CALPHAD). The BCC A2 solid solution phase is predicted by the model to contain
This paper describes an innovative process for the production of ferrochromium alloy via segregation reduction of chromite at 1300 °C in the presence of calcium chloride. Both charcoal and petroleum coke were used as the reductant. Individual polycrystalline ferrochrome carbide particles were produced, with their particle size and shape resembling that of the starting carbon particles. Interactions among calcium chloride, clinochlore, and chromite resulted in the formation of Ca-bearing chromite, wadalite, and gaseous chlorides. Monocrystalline ferrochrome carbide whiskers were formed only when charcoal in the presence of calcium chloride was used to reduce the chromite fraction containing large amounts of siliceous gangue. Incorporating thermodynamic evaluations, a possible segregation reduction mechanism is suggested based on the characterization of the products using scanning electron microscopy, energy dispersive spectroscopy, X-ray powder diffraction, and electron probe microanalysis, combined
Ge 116 Module 2: Electron Probe. Part 1: instrument basics, WDS X-ray analysis and standardization. Electron Probe: Parts. (5 of these). Electron Microprobe Instrumentation. What Makes a Microprobe? High Stability Electron Source Focussing WDS X-ray Optics High Precision Stage Slideshow...
TY - JOUR. T1 - Secondary fluorescence in WDS. T2 - the role of spectrometer positioning. AU - Buse, Benjamin. AU - Wade, Jon. AU - Llovet, Xaviet. AU - Kearns, Stuart. PY - 2018/12/3. Y1 - 2018/12/3. N2 - Secondary fluorescence, typically a minor error in routine electron probe microanalysis (EPMA), may not be negligible when performing high precision trace element analyses in multiphase samples. Other factors, notably wavelength dispersive spectrometer defocusing, may introduce analytical artefacts. To explore these issues, we measured EPMA transects across two material couples chosen for their high fluorescence yield. We measured transects away from the fluorescent phase, and at various orientations with respect to the spectrometer focal line. Compared to calculations using both the Monte Carlo simulation code PENEPMA and the semi-analytical model FANAL, both codes estimate the magnitude of SF, but accurate correction requires knowledge of the position of the spectrometer with respect to the ...
The Canadian Space Agency (CSA) recently commissioned the development of a suite of over fifty well-characterized planetary analogue materials. These materials are terrestrial rocks and minerals that are similar to those known or suspected to occur on the lunar or martian surfaces. These include: Mars analogue sedimentary, hydrothermal, igneous and low-temperature alteration rock suites; lunar analogue basaltic and anorthositic rock suites; and a generic impactite rock suite from a variety of terrestrial impact structures. Representative thin sections of the materials have been characterized by optical microscopy and electron probe microanalysis (EPMA). Reflectance spectra have been collected in the ultraviolet, visible, near-infrared and mid-infrared, covering 0.2-25. μm. Thermal infrared emission spectra were collected from 5 to 50. μm. Raman spectra with 532. nm excitation, and laser-induced fluorescence spectra with 405. nm excitation were also measured. Bulk chemical analysis was carried ...
With ever more challenging (T,p) environments for cementing applications in oil and gas wells, there is a need to identify the fundamental mechanisms of fracture resistant oil well cements. We report results from a multi-technique investigation of behavior and properties of API class G cement and silica-enriched cement systems subjected to hydrothermal curing from 30 °C to 200 °C; including electron probe microanalysis, X-ray diffraction, thermogravimetry analysis, electron microscopy, neutron scattering (SANS), and fracture scratch testing. The results provide a new insight into the link between system chemistry, micro-texture and micro-fracture toughness. We suggest that the strong correlation found between chemically modulated specific surface and fracture resistance can explain the drop in fracture properties of neat oil-well cements at elevated temperatures; the fracture property enhancement in silica-rich cement systems, between 110° and 175 °C; and the drop in fracture properties of ...
In previous evaluations, of GTA welding stainless steel plates the surfactant content in the workplace has been assumed to be in a state of equilibrium. However surfactant concentration usually had to be adjusted in order to achieve agreement between the weld pool shapes in experiments and those in simulations. In this study a physiochemical approach to the redistribution of surfactant at the surface and in the bulk is presented for the first time. Sulphur was considered as a represenative surfactant. The model allows surfactant molecular transport via convection, diffusion, and sorption. It is shown that sulphur atoms accumulate at the surface at stagnation points, affecting the coefficient of surface tension and thus the final weld pool shape. Thus, the sulphur content in the simulation approaches the nominal sulphur content in the steel plate. The theory is strenghtened by both electron probe microanalysis and Auger electron spectroscopy. At the time the work was carried out, Mr Winkler, Dr ...
Abstract A potent (Na,K)-ATPase inhibitor purified from "Sigma Grade* ATP has been identified as vanadium using electron probe microanalysis and confirmed by microwave-induced emission spectroscopy and electron paramagnetic resonance spectroscopy. Sodium orthovanadate (Na3 VO4) is identical with the purified inhibitor with respect to ultraviolet absorbance, migration on thin layer chromatography, and inhibition of (Na,K)-ATPase. The (Na,K)-ATPase is in-inhibited 50% by 40 nM Na3 VO4 under optimal conditions (28 mM Mg2+) and the inhibition is 100% reversible by millimolar concentrations of norepinephrine. The physiological significance of this inhibition is discussed in relation to vanadium concentrations in vivo.. ...
2017 Elsevier B.V.Primary ore-forming minerals retain geochemical signatures of magmatic crystallization information and can reveal the petrochemical conditions prevalent at the time of their formation. The Baogutu deposit is a typical reduced porphyry Cu deposit. Amphibole and biotite Fe3+/SFe ratios, minerals (feldspar, biotite, amphibole, zircon and apatite), in situ elemental and apatite Nd isotopic compositions were determined by Mössbauer spectroscopy, electron probe microanalysis, and laser ablation multiple-collection inductively coupled plasma mass spectrometry, respectively, to investigate the magma oxidation state, petrogenesis, source features, and to constrain the carbon species at magmatic stages for the intrusive phases. The results show that the primary plagioclase and amphibole in the mineralized diorite to granodiorite porphyry and post ore hornblende diorite porphyry are distinct (An26-55 versus An60-69; Mg-hornblende versus tschermakite). In particular, the amphibole shows ...
TY - JOUR. T1 - A menu of electron probes for optimising information from scanning transmission electron microscopy. AU - Nguyen,D. T.. AU - Findlay,S. D.. AU - Etheridge,J.. PY - 2018. Y1 - 2018. N2 - We assess a selection of electron probes in terms of the spatial resolution with which information can be derived about the structure of a specimen, as opposed to the nominal image resolution. Using Ge [001] as a study case, we investigate the scattering dynamics of these probes and determine their relative merits in terms of two qualitative criteria: interaction volume and interpretability. This analysis provides a menu of probes from which an optimum probe for tackling a given materials science question can be selected. Hollow cone, vortex and spherical wave fronts are considered, from unit cell to Angstrom size, and for different defocus and specimen orientations.. AB - We assess a selection of electron probes in terms of the spatial resolution with which information can be derived about the ...
Cystic fibrosis (CF) is a multi-organ autosomal recessive disease of fluid-transporting epithelia, due to a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is a cAMP-regulated Cl-channel involved in various regulatory processes. Salt and water transport depend on CFTR and the epithelial sodium channel (ENaC), operating in concert with the paracellular pathway through the tight junctions (TJ). The ionic composition of the ASL has been assumed to be altered in CF, resulting in a fatal accumulation of viscous mucus in the airways.. ASL samples were collected from tracheal and nasal fluid in normal and transgenic CF mice and from the fluid covering the apical surface of normal bronchial cells (16HBE14o-) and a CF human bronchial cell line (CFBE41o-). Analysis of the elemental content of the ASL was performed by X-ray microanalysis. The ASL contained more Na and Cl in CFTR-deficient or DF508-CFTR-containing cells than in control cells with ...
An electron probe micro-analyzer is a microbeam instrument used primarily for the in situ non-destructive chemical analysis of minute solid samples. EPMA is also informally called an electron microprobe, or just ...
Semantic Scholar extracted view of [Sural nerves in Behçets disease--histopathological, electronmicroscopical and X-ray microanalytical studies (authors transl)]. by Natsuko Fujiwara et al.
Field observations, petrography, electron microprobe analysis (EPMA), geothermometry, and geochemical analyses (ICP-MS and XRF) of the fluorspar deposit associated with the Late Cretaceous alkaline igneous-carbonatite complex at Okorusu (Namibia) have identified two previously unrecognized types of carbonatites, namely pyroxene and pegmatitic carbonatites. These carbonatites exhibit interesting textural characteristics, with the pyroxene carbonatite exhibiting occasional bands of diopside alternating with coarse-grained calcite-rich bands, and pegmatitic carbonatite having the same mineralogy but much coarser texture. Both types of carbonatites are closely spatially associated. Ülvospinel exsolution lamellae were recognized in magnetite crystals within the pyroxene and pegmatitic carbonatite. Stable isotope determinations for calcite crystals separated from pegmatitic carbonatites, pyroxene carbonatites, and marbles indicate that the carbonatites are primary in origin. Cathodoluminescence microscopy
This thoroughly revised and updated Fourth Edition of a time-honored text provides the reader with a comprehensive introduction to the field of scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) for elemental microanalysis, electron backscatter diffraction analysis (EBSD) for micro-crystallography, and focused ion beams. Students and academic researchers will find the text to be an authoritative and scholarly resource, while SEM operators and a diversity of practitioners - engineers, technicians, physical and biological scientists, clinicians, and technical managers - will find that every chapter has been overhauled to meet the more practical needs of the technologist and working professional. In a break with the past, this Fourth Edition de-emphasizes the design and physical operating basis of the instrumentation, including the electron sources, lenses, detectors, etc. In the modern SEM, many of the low level instrument parameters are now controlled and optimized by ...
OSTROOUMOV, Mikhail et al. Colimaite, K3VS4 - a new potassium-vanadium sulfide mineral from the Colima volcano, State of Colima (Mexico). Rev. mex. cienc. geol [online]. 2009, vol.26, n.3, pp.600-608. ISSN 2007-2902.. Colimaite, K3VS4, has been discovered in the active fumaroles of the Colima volcano crater, Mexico. The mineral is named colimaite after the locality, which, at the same time, is the current active volcanic crater and the name of the State of Colima (Mexico). Colimaite is the naturally occurring analog of synthetic K3VS4. The mineral formed as a sublimate from the volcanic gases and is associated with cristobalite, arcanite, thenardite, barite and native gold. Colimaite occurs in "hedgehog"-like particles, which contain the needle crystals, up to 50 µm length and 20 µm width. Electron microprobe analyses gave S=43.29 %, K=39.36 %, V=17.41 %, Na=0.43 %, with the sum of 100.49 (wt.%), as the mean of six measurements, previously tested as discordant outlier-free statistical samples. ...
J.D. Grice, R.A. Gault, A.C. Roberts, M.A. Cooper (2000) Adamsite-(Y), a new sodium-yttrium carbonate mineral species from Mont Saint-Hilaire, Quebec. Can. Mineral., 38, 1457-1466.. The mineral occurs as spherical aggregates of acicular to fibrous crystals, up to 2.5 cm long. Electron microprobe analysis gave Na2O 8.64, CaO 0.05, Y2O3 22.88, Ce2O3 0.37, Nd2O3 1.41, Sm2O3 1.02, Gd2O3 1.92, Tb2O.... ...
The Mount Clifford nickel sulfide deposit consists of several stratabound lenses of disseminated sulfides, averaging 1.5 to 2.0 percent Ni, in a serpentinized periodotite. The sulfide assemblage is Ni rich, represented by varying proportions of godlevskite, millerite, heazle-woodite, and Ni-rich pentlandite.In a single 50-cm section of core below the disseminated sulfide lenses, native nickel has been found as a significant component of irregular oxide-sulfide veins, stringers, and blebs in a serpentinized skeletal-textured periodotite. It is present as grains and granular aggregates ranging from 100 mu m to 3 mm in size, and averaging about 500 mu m. The chemical composition (average wt % from 24 electron microprobe analyses) is Ni, 96.41; Fe, 1.41; Co, 0.45; and Cu, 1.51; total, 99.78. Euhedral to subhedral spinels dominate the veins (approximate mode 75%) and are typically zoned from cores of nickeloan magnetite to rims of ferroan trevorite. The spinel both encloses and is included in an ...
I am a NERC funded PhD candidate under the supervision of Prof. Fin Stuart and Dr. Darren Mark. I am based in the noble gas isotope laboratories, SUERC. I am currently studying the influence of rock chemistry on different cosmogenic nuclide production rates (relative to what theoretical calculations predict). I am analyzing cosmogenic 3He production rates in olivine and pyroxene from xenoliths collected at Mount Hampton and Mount Cumming, Antarctica. Advanced Mass Spectrometry (e.g., Thermo Fisher HELIX-SFT) is been used to determine variations in cosmogenic 3He production rates. SEM and electron microprobe analyses have be performed in order to obtain accurate chemical composition of the minerals studied. This study will be extended to a comparison of 21Ne and 10Be production rate.. ...
The Deccan Traps, a 65 million-year-old continental flood basalt province located in western India, is the result of one of the largest short-lived magmatic events to have occurred on Earth. The nature and composition of its mantle source(s), however, have been difficult to resolve due to extensive assimilation of continental crust into the ascending Traps magmas. To circumvent this issue, using high-precision electron microprobe analysis, we have analyzed olivine grains from MgO-rich (up to 15.7 wt.%) lavas that likely erupted before substantial crustal assimilation occurred. We compare olivine, pyroxene and plagioclase mineral chemistry and He-O-Os isotope compositions with bulk rock major- and trace-element abundances and 187Os/188Os for both bulk-rocks and mineral separates. Helium isotope compositions for the olivine grains generally show strong influence from crustal assimilation (,3 RA), but one ankaramite from the Pavagadh volcanic complex has a 3He/4He ratio of 10.7 RA, which is ...
Additional resources for Petrology of the Ocean Floor. Example text. The increase in ferrosilite content is most prominent in the groundmass clinopyroxene. , 1979) t o differentiate between alkali basalts and tholeiites. The elements which are the most sensitive to variation are Cr, Ti, Na and Al. Cr, Ti and A1 enter into the 6-coordinate site of the pyroxene crystalline structure while Si and A1 are found in the 4-coordinate site. 2atom/formula unit) while alkali basalts from other w TABLE 1-11 00 Electron microprobe analyses of clinopyroxene from Mid-Oceanic Ridge basalts East Pacific Rise Total Mid-Atlantic Ridge - Mid-Indian Oceanic Ridge Leg 9 82-7-1/60 (ave. This ternary diagram is part of the more complex diopside-forsterite-nepheline-quartz diagram of the iron-free basalt system of Yoder and Tilley (1962). The plagioclase-olivine-pyroxene system corresponds theoretically t o the critical plane of silica undersaturation. The ternary plagioclase-olivine-pyroxene diagram is used t o show ...
The CAMECA SX50 is equipped with four WDS spectrometers containing 12 diffracting crystals which allow analysis of all elements with Z ≥ 4 (beryllium). ...
Segregation of P and Mo to prior austenite grain boundaries in a 2.25Cr1Mo steel subjected to neutron irradiation and ageing is examined using field emission gull scanning transmission electron microscopy (FEGSTEM) with energy dispersive X-ray microanalysis. The steel samples are irradiated and aged at around 270 and 400 degrees C, respectively. The irradiation dose rate and dose are about 1.05 x 10(-8) dpa s(-1) and 0.032 dpa for 370 degrees C-irradiation, and 1.75 x 10(-8) dpa s(-1) and 0.13 dpa for 400 degrees C-irradiation. The FEGSTEM results indicate that, during 270 degrees C-irradiation, there is no irradiation effect for P segregation and some effect for Mo segregation with the Mo boundary concentration decreasing. During 400 degrees C-irradiation, there is a slight irradiation effect for P segregation with the P boundary concentration increasing and some irradiation effect for Mo segregation with the Mo boundary concentration decreasing. The 400 degrees C-ageing does not enhance Mo segregation
ARTAXO, P, RABELLO, MLC, WATT, F, GRIME, G and SWIETLICKI, E (1993) NUCLEAR MICROPROBE ANALYSIS AND SOURCE APPORTIONMENT OF INDIVIDUAL ATMOSPHERIC AEROSOL-PARTICLES In: 6TH INTERNATIONAL CONF ON PIXE ( PARTICLE INDUCED X-RAY EMISSION ) AND ITS ANALYTICAL APPLICATIONS, 1992-07-20 - 1992-07-24, WASADEA UNIV CONF HALL, TOKYO, JAPAN. Full text not available from this repository ...
However, the user has a responsibility to bring intellect, curiosity, and a proper skepticism to information on a computer screen and to the entire measurement process. This book helps you to achieve this goal ...
Microscopy & Microanalysis 2014 Meeting. M&M 2014 will be held August 3-7 at the Connecticut Convention Center in downtown Hartford, CT.. Register for Microscopy & Microanalysis. ...
One experimental study is available investigating the toxicological effects of the test item (CAS 16260-09-6) to earthworms (ECT, 2017). The study was performed according to OECD guideline 222 under GLP conditions. Adult Eisenia andrei (4 x 10 animals per concentration, the fresh weight was between 250 and 600 mg) were exposed for 28 days in an artificial soil to the nominal concentrations of 62.5, 125, 250, 500 and 1000 mg test item/kg artificial soil dry weight. The artificial soil comprised 5% sphagnum peat, 20% kaolin clay, 74-75% Quartz sand and 0.3 - 1% calcium carbonate. No morphological and behavioral effects were observed. Related to weight alterations and symptoms, the no-observed-effect-concentration (NOEC) was ≥ 1000 mg test item/kg dry weight soil, the lowest-observed-effect-concentration (LOEC) , 1000 mg test item/kg dry weight soil for all parameters after 28 days for mortality and biomass. No mortality was recorded resulting in a EC50 (28 d) of , 1000 mg test item/kg dry weight ...
If intracellular free calcium is the key regulator, then the ability of changes in the activity of Na+ channels and K+ channels to alter the extent of degeneration could be readily explained. One possibility is that there are changes in resting membrane potential of the distal axonal membrane by enhanced opening or closing of endogenous channels. Alternatively, changes in intracellular ion concentration might change the current flowing through the same constellation of open channels. Either change would influence the probability of Ca2+ influx through voltage gated Ca2+ channels. Changes in the excitability of injured distal axons have been previously inferred through electrophysiological studies (Moldovan et al., 2009). x-ray microprobe analysis of elemental distributions in injured sciatic nerves have also noted changes in the levels of axonal K and N, which precede changes in Ca (LoPachin et al., 1990).. If the initial effect of injury is a slight depolarization from the normal resting ...
Realigns the text with the needs of a diverse audience from researchers and graduate students to SEM operators and technical managers Emphasizes
The staining of neurons with cobalt chloride, either by intracellular injection or infusion through the cut ends of axons, and subsequent precipitation of the black insoluble sulphide within the...
www.MOLUNA.de Practical Scanning Electron Microscopy [4192822] - I Introduction.- I. Evolution of the Scanning Electron Microscope.- II. Evolution of the Electron Probe Microanalyzer.- III. Combination SEM-EPMA.- IV. Outline and Purpose of This Book.- References.- Bibliography of Texts and Monographs in SEM and EPMA.- II Electron Optics.- I. Electron Guns.- A. Tungsten Filament Cathode.- B. LaB6 Rod Cathode.-
Mineralogy and mineral chemistry data collected on unusual boninite samples (U1439C 15R-1, U1439C 25R-1) recovered during IODP Expedition 352 demonstrate highly variable mineral chemistries that suggest complex crystallization histories. The samples include early-crystallized olivines with embayed and reacted margins, some of which also show zoning (Fo87 cores; Fo77 rims), and large, euhedral pyroxene crystals, with clinoenstatite to pigeonite cores (En86 Fs12 Wo2, to En69 Fs12 Wo19), and augite rims (En43 Fs17 Wo40). Cr-rich spinels were found to be enclosed in both olivines and pyroxenes. These spinels show elevated Al2O3 and MgO contents (≈8-12%), suggesting early high pressure crystallization. Further EPMA studies of these and other Expedition 352 boninites, focused on spinel-olivine and spinel-pyroxene relationships, were conducted using the JEOL 8900R electron microprobe system at the Florida Center for Analytical Electron Microscopy (FCAEM) at Florida International University. Olivine-spinel
The artifact was recovered from Emirau Island in the Bismark Archipelago. It was likely dropped from a stilt house into the water below and covered by years of beach sand.After preliminary analysis at Academia Sinica (Taiwan) and the University of Otago, the gouge was sent to the Museum, where it was studied with x-ray microdiffraction, a technique that bounces a small beam of x-rays off the specimen to elucidate the atomic structure of the material, and, consequently, the types of minerals it contains. Harlow also used the Museums electron microprobe to determine the chemical composition of the minerals in the jadeitite."When we first looked at this artifact, it was very clear that it didnt match much of anything that anyone knew about jadeite jade," Harlow said.The chemical composition of the jadeite in the rock is substantially different from that of other jadeitite samples. Jadeite, a mineral of sodium, aluminum, silicon and oxygen in its pure form, is usually mixed compositionally with ...
The work currently being carried out on the Chumash Indian rock art pigments has involved the study of samples from a number of sites in the Santa Barbara, Ventura, San Luis Obispo, and Kern County areas. Most of the sites occur in the historic Chumash area with some of the art in the Coso Yokuts tribal zones. The Californian sites studied so far include: Painted Cave: SBa506; Morris Cabin Creek: SBa1288; Pool Rock: SBa1632; Condor Cave: SBa1633; Carneros Rock: Ker161; Indian Wells Canyon: Ker735 and Ker736; Edgar Rock: SLO336; North Selby: SLO1103; and Painted Rock: SLO79.. The study was instigated to determine what pigments had been employed by the Chumash Indians and was based on pigment microsamples and rock art fragments excavated from site debris. The techniques of examination employed in the study were polarized light microscopy, environmental scanning electron microscopy, electron microprobe, color measurement in situ, and powder X-ray diffraction powder.. The pigments identified in the ...
Petrographic, microthermometric, chemical, and isotopic analyses of melt and fluid inclusions. Specifications/Capabilities: To document petrographic relations among inclusions and their host minerals, DIAL is equipped with supporting sample preparation equipment, petrographic microscopes with ultraviolet (UV), infrared (IR), or cathodoluminescence (CL) capability, scanning electron microscope-cathodoluminescence (SEM-CL), and digital imaging systems. Single inclusion instruments include heating/freezing stage microscopes (T, P, salinity, density), electron microprobe (major-minor elements), laser Raman spectroscope (major gases), thermal decrepitation-quadrupole mass spectrometer and laser ablation-ion trap-time of flight-mass spectrometer (major-minor gases), as well as laser ablation-inductively coupled plasma-mass spectrometer (multielements). Bulk analysis methods include dual ion chromatograph (cations and anions), quadrupole mass spectrometer (major to trace gases), static high-resolution ...
Si-bearing, OH-dominant pertsevite Mg2(BO3)1−x(SiO4)x(OH,F)1−x (x = 0.2−0.3) from contact-metasomatic kotoitites and kotoite marbles at East Verkhoyanye region (northern Siberia) and at Gonochan, Dzhugdzhur Ridge (Russian Far East) was studied by electron microprobe (EMP) techniques, including boron analyses, and Raman spectroscopy. At both localities borate mineral-assemblages are very similar. Minerals associated with OH-dominant pertsevite (East Verkhoyanye region) are ludwigite, kotoite, szaibelyite, REE-bearing sakhaite, olivine and minerals of the humite group. Humite-group minerals and olivine were found to be slightly B2O3-bearing (ca. 1 wt.%). OH-dominant pertsevite, described here for the first time, formed at the expense of kotoite and hydroxylclinohumite and has a rather heterogeneous composition with respect to Si, B, F and OH between different grains and even within individual grains. The crystal structure of one selected grain of OH-dominant pertsevite ...
The distribution of Fe, Ni, Co, P, Ge, W, Mo, and O between molten silicate and liquid metal was determined at pressures and temperatures relevant to core formation (50-80 kb, 2000-2300 degrees C) under both carbon-free and graphite-saturated conditions. The effect of carbon is very pronounced in reducing the siderophile tendencies of P and Ge. Germanium showed a significant reduction in metal-silicate partition coefficients (D-met/sil) from a value too high to be determined by the electron microprobe in the carbon-free metal/ultrabasic silicate system down to a value of similar to 33 in the carbon-bearing metal/ultrabasic silicate system. Phosphorus becomes lithophile at carbon saturation. Nickel and cobalt show a modest reduction, and W and Mo show a modest increase in siderophility at graphite saturation. These effects are seen both in basic, aluminous, and ultrabasic, magnesian silicate liquids. Carbon-bearing liquids, in combination with their sulfurous cousins, would be less effective at ...
Northwest Africa 12923 (NWA 12923). Niger. Purchased: 2017. Classification: Ordinary chondrite (H5, melt breccia). History: Wang Chen and Ziyao Wang purchased many individual specimens totaling 3.4 kg and 2 kg respectively from a Moroccan meteorite dealer during the 2017 Beijing International Mineral, Gem & Fossil Show.. Petrography: (C. Herd, UAb) Examination of two ~2 × 4 cm sequential slices and a ~1.5 × 2.5 cm slice (later used to make the thin section) shows dark-gray rounded clasts containing metal and silicates with some microporosity, surrounded by lighter-gray microcrystalline domains which often have vein-like morphology relative to the clasts. Metal grains in the clasts are mostly ,0.5 mm, but locally up to 5 mm in longest dimension. At thin section scale, the clasts consist of poorly-delineated chondrules, metal and sulfides in a typical equilibrated ordinary chondrite texture. Microcrystalline domains are glassy in places under optical microscopy. Under the electron microprobe, ...
Co-directors: Scott E. Fraser, Steven Nutt. Contact: John Curulli ([email protected]). The mission of the Center for Electron Microscopy and MicroAnalysis (CEMMA) is to promote and advance the science and application of microscopic imaging and analysis techniques for visualizing and elucidating the ultrastructure and function of diverse materials. The center provides research tools for imaging, visualization and analysis of nano-scale features and structures, both man-made and natural, including biological structures. The shared instrumentation facility is accessible to all USC personnel and houses major instrumentation, including scanning and transmission electron microscopes and related instruments.. For more information, visit usc.edu/dept/CEMMA.. ...
Gatan continues its partnership with the Microscopy Society of America as a major corporate exhibitor, sponsor, and presenter at the annual Microscopy and Microanalysis (M&M) conference. Join us to learn how our state of the art cameras, imaging energy filters, specimen preparation equipment, and other products can help you push the boundaries of what can be done with electron microscopy.
Hren, John J. is the author of Electron Optical Systems for Microscopy, Microanalysis and Microlithography Proceedings of the 3rd Pfefferkorn Conference, Held April 9 to 14, 1984, at the Carousel Hotel, Ocean City, MD with ISBN 9780931288340 and ISBN 0931288347. [read more] ...
... provides researchers and organisations with expertise and training in a range of microscopy fields.
The 2019 Microscopy and Microanalysis Conference is held in Portland, OR from August 4-8th 2019.. This years meeting will be held just two hours driving of Hummingbird Scientifics facility in the Olympia/Lacey WA area so let us know if you are interested in coming to visit while you are in the area!. During the conference Hummingbird Scientific will be in booth #1045 (just behind the ThermoFischer booth as you walk in the Exhibit Hall).. We have a series of events planned for the week at our booth:. ...