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Sample records for paranitrophenol-an xrd tem

  1. Changes in the surfaces on DDOAB organoclays adsorbed with paranitrophenol-An XRD, TEM and TG study

    SciTech Connect

    Zhou Qin; He Hongping; Frost, Ray L. Xi Yunfei

    2008-12-01

    The adsorption of paranitrophenol on organoclays synthesised by the ion exchange of the surfactant molecule dimethyldioctadecylammonium bromide (DDOAB) of formula (CH{sub 3}(CH{sub 2}){sub 17}){sub 2}NBr(CH{sub 3}){sub 2} has been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis. The expansion of the montmorillonite depends on the loading of the montmorillonite with dimethyldioctadecylammonium bromide and is related to the arrangement of the surfactant molecules within the clay interlayer. This expansion is altered by the adsorbed paranitrophenol and is observed in the transmission electron microscopic images of the organoclay with adsorbed paranitrophenol. Changes in the surfactant molecular arrangements were analysed by thermogravimetry. The paranitrophenol is sublimed simultaneously with the loss of surfactant. The dehydroxylation temperature of the montmorillonite is decreased upon adsorption of the paranitrophenol indicating a bonding between the paranitrophenol and the hydroxyl units of the montmorillonite.

  2. Characterization of crystallite morphology for doped strontium fluoride nanophosphors by TEM and XRD

    NASA Astrophysics Data System (ADS)

    O'Connell, J. H.; Lee, M. E.; Yagoub, M. Y. A.; Swart, H. C.; Coetsee, E.

    2016-01-01

    Crystallite morphology for Eu-doped and undoped SrF2 nanophosphors have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The values for average crystallite size obtained by the application of the Scherrer equation and the full width at half maximum (FWHM) values for XRD peaks are compared to the results obtained using the hollow cone dark field (HCDF) TEM imaging technique. In the case of the TEM analysis, a bimodal crystallite size distribution was revealed with one of the distributions having a measured range of crystallite sizes which was in good agreement with the XRD data. HCDF in combination with FIB specimen preparation was found to be a promising technique for the determination of crystallite size distributions in nanophosphors which might facilitate a better understanding of their scintillation properties.

  3. XRD, TEM, IR, Raman and NMR Spectroscopy of In Situ Crystallization of Lithium Disilicate Glass

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Mogus-Milankovic, A.; Ray, C. S.; Lesher, C. E.; Youngman, R.; Day, D. E.

    2006-01-01

    The structure of a Li2O-2SiO2 (LS2) glass was investigated as a function of pressure and temperature up to 6 GPa and 750 C respectively, using XRD, TEM, IR, Raman and NMR spectroscopy. Glass densified at 6 GPa has an average Si-O-Si bond angle approx.7deg lower than that found in glass processed at 4.5 GPa. At 4.5 GPa, lithium disilicate crystallizes from the glass, while at 6 GPa a new high pressure form of lithium metasilicate crystallizes. The new phase, while having lithium metasilicate crystal symmetry, contains at least 4 different Si sites. NMR results for 6 GPa sample indicate the presence of Q4 species with (Q(sup 4))Si-O-Si(Q(sup 4)) bond angles of approx.157deg. This is the first reported occurrence of Q(sup 4) species with such large bond angles in alumina free alkali silicate glass. No five- or six- coordinated Si are found.

  4. Mössbauer, TEM/SAED and XRD investigation on waste dumps of the Valea lui Stan gold mines

    NASA Astrophysics Data System (ADS)

    Constantinescu, Serban Grigore; Udubasa, Sorin S.; Udubasa, Gheorghe; Kuncser, Victor; Popescu-Pogrion, Nicoleta; Mercioniu, Ionel; Feder, Marcel

    2012-03-01

    The complementary investigation techniques, Mössbauer spectroscopy, transmission electron microscopy with selected area electron diffraction (TEM/SAED), X-ray diffraction (XRD) have been used to investigate the fate of the Valea lui Stan, Romania, gold-ore nanoscale-minerals during the long time of residence in the waste dumps. The preliminary investigations showed such waste dumps to contain significant amount of metals which cannot be identified by conventional methods. An intense research activity started up in order to evaluate the possibilities to recycle Valea lui Stan waste dumps and to recover metals by chemical or phytoextraction procedures. The waste dumps naturally show different mineral constituents with clay minerals as major phases, observed by XRD-technique. Although the waste dumps materials have whitish-yellowish colours, MÖSSBAUER technique evidences the presence of the finely dispersed iron bearing minerals. The authors are focusing to inspect and analyze Fe-compounds in the samples collected from Valea lui Stan's waste dumps in order to identify the magnetic phases by Mössbauer technique.

  5. NGR, XRD and TEM/SAED investigations on waste dumps materials with a view to recover precious metals

    NASA Astrophysics Data System (ADS)

    Udubasa, S. S.; Constantinescu, S.; Popescu-Pogrion, N.; Feder, M.; Udubasa, G.

    2010-03-01

    Two types of ores were selected for the investigation of the fate of the ore minerals during relatively long time of residence in the waste dumps (active mining: 25 years ago in the Badeanca Valley and some 50 years ago in the Valea lui Stan area). The pentametallic ores (Co-Ni-Bi-Ag-U) in the Leaota Mts. contain a great number of primary minerals of Cu, As etc. Although the waste dumps materials have whitish-yellowish colors their NGR spectra show the presence of iron minerals very finely dispersed. In the gold ores of Valea lui Stan deposit numerous minerals were identified, such as arsenopyrite, pyrite, pyrrhotite, etc., as major gold bearing sulfides. The waste dumps materials naturally show different mineral constituents, with clay minerals as major phases. Detailed NGR investigations show however Mössbauer spectra pointing out the presence of finely dispersed iron or iron-bearing minerals. Under supergene conditions gold is commonly sequestrated by iron hydroxydes; further TEM/SAED and XRD investigations are contributing to localize the gold. In some samples Mössbauer spectra resembling those of greigite have been obtained. Greigite is also a principal concentrator of gold under supergene conditions.

  6. A TEM and XRD Study of (BiS) 1+δ(Nb 1+ɛS 2) n Misfit Layer Structures

    NASA Astrophysics Data System (ADS)

    Otero-Diaz, L. C.; Withers, R. L.; Gomez-Herrero, A.; Welberry, T. R.; Schmid, S.

    1995-02-01

    Monolayer and bilayer lamellar misfit layered chalcogenides within the BiS-NbS 2 system have been synthesized and studied via TEM and XRD. Both BiS and NbS 2 parent substructures are shown to have very close to orthorhombic symmetry in the former case, but definite monoclinic symmetry in the latter. Stacking disorder and its effect upon electron diffraction patterns is investigated via higher order Laue zone (HOLZ) diffraction. In addition to the usual set of reflections for such systems, an additional set of weak, somewhat diffuse satellite reflections (not previously reported before for any other misfit layered chalcogenide) have been observed. Bilayer tubular crystals have also been studied by XRD. A close relationship with the corresponding lamellar bilayer phase is established, and some unusual features of its reciprocal lattice are pointed out.

  7. Vacancy ordered γ-Fe2O3 nanoparticles functionalized with nanohydroxyapatite: XRD, FTIR, TEM, XPS and Mössbauer studies

    NASA Astrophysics Data System (ADS)

    Ramos Guivar, Juan A.; Sanches, Edgar A.; Bruns, Florian; Sadrollahi, Elaheh; Morales, M. A.; López, Elvis O.; Litterst, F. Jochen

    2016-12-01

    Vacancy ordered maghemite (γ-Fe2O3) nanoparticles functionalized with nanohydroxyapatite (HAp - Ca10(PO4) 6(OH)2) have been successfully synthesized using an inexpensive co-precipitation chemical route. Evidence for the presence of vacancy order in maghemite was shown by the superstructure lines observed in X-ray diffraction. The adsorption of carboxyl groups of citric acid (C6H8O7) onto γ-Fe2O3 nanoparticles was investigated by FTIR, XPS and Mössbauer spectroscopy. From XPS surface analysis, two binding energies related to oxygen were attributed to bindings between C6H8O7/γ- Fe2O3 and C6H8O7/HAp from an interfacial reaction promoted by strongly adsorbed H2O molecules at the surface of these nanomaterials. Le Bail refinement of the XRD patterns showed the formation of well-crystallized pure tetragonal maghemite before and after functionalization with nanoHAp. The temperature dependence of hyperfine parameters of pure and functionalized γ-Fe2O3 nanoparticles was investigated via Mössbauer spectroscopy. TEM revealed the formation of quasi-spherical γ- Fe2O3 nanoparticles with an average diameter of ca. 12 nm and 16 nm before and after functionalization with nanoHAp in agreement with Le Bail refinement. Magnetometry measurements showed a saturation magnetization of 12 emu/g and a blocking temperature of 340 K for the functionalized γ- Fe2O3 nanoparticles.

  8. Alteration history of mudrock samples from the San Andreas Fault Observatory at Depth (SAFOD) drill hole: a TEM-XRD study

    NASA Astrophysics Data System (ADS)

    Schleicher, A. M.; van der Pluijm, B. A.; Warr, L. N.

    2006-12-01

    Studying rock alteration in active fault zones is key to understanding fault history and the interaction with mechanical, hydrological and mineralogical processes. In the SAFOD mudrocks at 3064 and 3436 m depths, abundant clay mineral phases, including mixed-layered varieties, occur in the matrix. At present, little is known about the mechanism and timing of their formation in relation to the faulting process. Based on a detailed TEM-XRD study, a preliminary assessment of the alteration history of the clay-rich rock chips is made by studying mineral character, hydration behavior, fabric and textural relationships. The mudrocks contain detrital grains of chlorite, muscovite and biotite, along with a range of authigenic illite, illite-smectite, chlorite- smectite and smectite. The predominant clay minerals are small illite packets (20-30 nm thickness) of a 1Md polytype. The illite constitutes about 75 percent of the illite-smectite mixed layer particles, showing a long- range ordering (R greater than 3). These authigenic mineral phases are probably formed during the movement of aqueous fluids along permeable fractures and veins by dissolution-precipitation reactions, and partly at the expense of larger (about 150 nm thick), deformed, detrital packets. The chlorite-smectite mixed layered phases formed via similar mechanisms, but in this case by direct alteration of detrital chlorite and biotite grains. Preliminary DTA heat flow results from a whole rock mudstone indicate a total loss of about 6 percent of total volatiles (about 2 percent interlayer water, about 4 percent crystalline water), most of which occurs during the dehydroxylation of clays (400-600 C). The timing of authigenic mineral growth in the matrix assemblages is considered to be coeval or older than localized mineralization along open fractures. The fracture precipitations are notably smectite rich and can be taken as an indication of more recent low temperature fluids of varying composition or more

  9. XRD and TEM characterization of cathodic MnO{sub 2} and discharge products in the Li-MnO{sub 2} cell

    SciTech Connect

    Shao, Y.; Hackney, S.A.; Cornilsen, B.C.

    1995-12-31

    The crystal structures of the undischarged, heat-treated electrolytic manganese dioxide (HEMD) and discharge products are characterized by high spatial resolution convergent beam electron diffraction (CBED). The results are compared with the x-ray diffraction (XRD) patterns characterized by broad, diffuse peaks. The CBED results for HEMD show that the starting cathodic material has the pyrolusite space group, but with a range of c/a ratios. The variability of the lattice parameter from grain to grain is found to coincide with the broadening on the low angle side of the XRD peaks. The CBED patterns of discharge products suggest a reduction range in c/a ratios and the formation of another phase.

  10. Morphological and Structural Changes during the Reduction and Reoxidation of CuO/CeO2 and Ce1-xCuxO2 Nanocatalysts: In Situ Studies with Environmental TEM XRD and XAS

    SciTech Connect

    J Ciston; R Si; J Rodriquez; J Hanson; A Martinez-Arias; M Fernandez-Garcia; Y Zhu

    2011-12-31

    We have studied the structural, morphological, and electronic properties of CuO/CeO{sub 2} and Ce{sub 1-x}Cu{sub x}O{sub 2} nanocatalysts during reduction/oxidation cycles using H2 and O2 as chemical probes. Time-resolved in situ characterization was performed by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) as well as aberration-corrected environmental transmission electron microscopy (ETEM). We have found that both types of nanocatalysts reduce to a Cu/CeO{sub 2} biphase system with significant oxygen vacancies in CeO{sub 2}. Important variations are seen in the Cu particle size and metal dispersion depending on the initial state of the copper oxide-ceria systems. During subsequent in situ oxygen annealing, the Cu precipitated from the CuO/CeO{sub 2} system reoxidized to form CuO through a Cu2O intermediate phase as expected. However, the Cu precipitated from the Ce{sub 0.8}Cu{sub 0.2}O{sub 2} solid solution behaved rather differently under oxidizing conditions, and neither oxidized to form CuO nor fully returned to a bulk Ce{sub 0.8}Cu{sub 0.2}O{sub 2} phase in solid solution. We found that 50% of the Cu returned to a Ce{sub 1-x}Cu{sub x}O{sub 2} solid solution, while the remainder was observed by in situ ETEM to form an amorphous copper oxide phase with a Cu oxidation state similar to Ce{sub 1-x}Cu{sub x}O{sub 2}, but with a local bonding environment similar to CuO. The behavior of the reduced Ce{sub 0.8}Cu{sub 0.2}O{sub 2} reflects strong interactions between Cu and the ceria matrix and illustrates the advantages of working with solid solutions of mixed oxides.

  11. Morphological and Structural Changes During the Reduction and Reoxidation of CuO/CeO(2) and Ce(1-x)Cu(x)O(2) Nanocatalysts: In-situ Studies with Environmental TEM, XRD and XAS

    SciTech Connect

    Rodriguez, J.A.; Ciston, J.; Si, R.; Hanson, J.C.; Martínez-Arias, A.; Fernandez-García, M.; Zhu, Y.

    2011-07-21

    We have studied the structural, morphological, and electronic properties of CuO/CeO{sub 2} and Ce{sub 1-x}Cu{sub x}O{sub 2} nanocatalysts during reduction/oxidation cycles using H{sub 2} and O{sub 2} as chemical probes. Time-resolved in situ characterization was performed by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) as well as aberration-corrected environmental transmission electron microscopy (ETEM). We have found that both types of nanocatalysts reduce to a Cu/CeO{sub 2} biphase system with significant oxygen vacancies in CeO{sub 2}. Important variations are seen in the Cu particle size and metal dispersion depending on the initial state of the copper oxide-ceria systems. During subsequent in situ oxygen annealing, the Cu precipitated from the CuO/CeO{sub 2} system reoxidized to form CuO through a Cu{sub 2}O intermediate phase as expected. However, the Cu precipitated from the Ce{sub 0.8}Cu{sub 0.2}O{sub 2} solid solution behaved rather differently under oxidizing conditions, and neither oxidized to form CuO nor fully returned to a bulk Ce{sub 0.8}Cu{sub 0.2}O{sub 2} phase in solid solution. We found that {approx} 50% of the Cu returned to a Ce{sub 1-x}Cu{sub x}O{sub 2} solid solution, while the remainder was observed by in situ ETEM to form an amorphous copper oxide phase with a Cu oxidation state similar to Ce{sub 1-x}Cu{sub x}O{sub 2}, but with a local bonding environment similar to CuO. The behavior of the reduced Ce{sub 0.8}Cu{sub 0.2}O{sub 2} reflects strong interactions between Cu and the ceria matrix and illustrates the advantages of working with solid solutions of mixed oxides.

  12. TEM Video Compressive Sensing

    SciTech Connect

    Stevens, Andrew J.; Kovarik, Libor; Abellan, Patricia; Yuan, Xin; Carin, Lawrence; Browning, Nigel D.

    2015-08-02

    One of the main limitations of imaging at high spatial and temporal resolution during in-situ TEM experiments is the frame rate of the camera being used to image the dynamic process. While the recent development of direct detectors has provided the hardware to achieve frame rates approaching 0.1ms, the cameras are expensive and must replace existing detectors. In this paper, we examine the use of coded aperture compressive sensing methods [1, 2, 3, 4] to increase the framerate of any camera with simple, low-cost hardware modifications. The coded aperture approach allows multiple sub-frames to be coded and integrated into a single camera frame during the acquisition process, and then extracted upon readout using statistical compressive sensing inversion. Our simulations show that it should be possible to increase the speed of any camera by at least an order of magnitude. Compressive Sensing (CS) combines sensing and compression in one operation, and thus provides an approach that could further improve the temporal resolution while correspondingly reducing the electron dose rate. Because the signal is measured in a compressive manner, fewer total measurements are required. When applied to TEM video capture, compressive imaging couled improve acquisition speed and reduce the electron dose rate. CS is a recent concept, and has come to the forefront due the seminal work of Candès [5]. Since the publication of Candès, there has been enormous growth in the application of CS and development of CS variants. For electron microscopy applications, the concept of CS has also been recently applied to electron tomography [6], and reduction of electron dose in scanning transmission electron microscopy (STEM) imaging [7]. To demonstrate the applicability of coded aperture CS video reconstruction for atomic level imaging, we simulate compressive sensing on observations of Pd nanoparticles and Ag nanoparticles during exposure to high temperatures and other environmental

  13. Vanga Bhasma and its XRD analysis

    PubMed Central

    Hiremath, Rudramma; Jha, C.B.; Narang, K.K.

    2010-01-01

    Bhasmas are potent Ayurvedic medicaments, biologically active and powerful healing preparations in all aspects. Properly prepared Bhasmas have not reported any serious untoward effects in clinical practice. Vanga Bhasma is an effective Ayurvedic medicine among various Bhasmas which are classically explained and advised specially in genitourinary disorders. XRD peaks of Vanga Bhasma are identified to be as Tindioxide (SnO2) PMID:22557364

  14. TEM turbulence optimisation in stellarators

    NASA Astrophysics Data System (ADS)

    Proll, J. H. E.; Mynick, H. E.; Xanthopoulos, P.; Lazerson, S. A.; Faber, B. J.

    2016-01-01

    With the advent of neoclassically optimised stellarators, optimising stellarators for turbulent transport is an important next step. The reduction of ion-temperature-gradient-driven turbulence has been achieved via shaping of the magnetic field, and the reduction of trapped-electron mode (TEM) turbulence is addressed in the present paper. Recent analytical and numerical findings suggest TEMs are stabilised when a large fraction of trapped particles experiences favourable bounce-averaged curvature. This is the case for example in Wendelstein 7-X (Beidler et al 1990 Fusion Technol. 17 148) and other Helias-type stellarators. Using this knowledge, a proxy function was designed to estimate the TEM dynamics, allowing optimal configurations for TEM stability to be determined with the STELLOPT (Spong et al 2001 Nucl. Fusion 41 711) code without extensive turbulence simulations. A first proof-of-principle optimised equilibrium stemming from the TEM-dominated stellarator experiment HSX (Anderson et al 1995 Fusion Technol. 27 273) is presented for which a reduction of the linear growth rates is achieved over a broad range of the operational parameter space. As an important consequence of this property, the turbulent heat flux levels are reduced compared with the initial configuration.

  15. Characterization of magnetite in silico-aluminous fly ash by SEM, TEM, XRD, magnetic susceptibility, and Moessbauer spectroscopy

    SciTech Connect

    Gomes, S.; Francois, M.; Abdelmoula, M.; Refait, P.; Pellissier, C.; Evrard, O.

    1999-11-01

    Spinel magnetite contained in a silico-aluminous fly ash (originating from la Maxe's power plant, near Metz in the east of France) issued from bituminous coal combustion has been studied by scanning and transmission electron microscopy linked with energy dispersive spectroscopy. X-ray diffraction, susceptibility measurements, and Moessbauer spectroscopy. The results show that in this magnetite Mg is strongly substituted for Fe and the chemical formula is closer to MgFe{sub 2}O{sub 4} than Fe{sub 3}O{sub 4}. Magnetite also contains Mn, Ca, and Si elements, but at a lower proportion. The results are compatible with the chemical formula Fe{sub 2.08}Mg{sub 0.75}Mn{sub 0.11}Ca{sub 0.04}Si{sub 0.02}O{sub 4} and crystallochemical formula [Fe{sup 2{minus}}{sub 0.92}Ca{sup 2+}{sub 0.06}Si{sup 4+}{sub 0.02}]{sup tetra}[Fe{sup 3+}Fe{sup 2+}{sub 0.16}Mg{sup 2+}{sub 0.73}Mn{sup 2+}{sub 0.11}]{sup octa}O{sub 4}, showing the cation distribution on octahedral and tetrahedral sites of the spinel structure. The reason Mg element is not incorporated in soluble surface salt and in glass composition of the silico-aluminous fly ashes is now understood.

  16. Technical Evaluation Motor No. 7 (TEM-7)

    NASA Technical Reports Server (NTRS)

    Hughes, Phil

    1991-01-01

    The Technical Evaluation Motor No. 7 (TEM-7) test was a full-scale, full duration static test firing of a high performance motor-configuration solid rocket motor with nozzle vectoring. The final test report documents the procedures, performance, and results of the static test firing of TEM-7. All observations, discussions, conclusions, and recommendations included in the report are complete and final except for the TEM-7 fixed housing unbond investigation. A presentation and discussion of TEM-7 performance, anomalies, and test result concurrence with the objectives outlined in CTP-0107, Rev A, Space Shuttle Technical Evaluation Motor No. 7 (TEM-7) Static Fire Test Plan are included.

  17. Technical Evaluation Motor No. 10 (TEM-10)

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Technical Evaluation Motor No. 10 (TEM-10) was static fired on 27 Apr. 1993 at the Thiokol Corporation full-scale motor static test bay, T-24. This final test report documents the procedures, performance, and results of the static test firing of TEM-10. All observations, discussions, conclusions, and recommendations contained are final. Included is a presentation and discussion of TEM-10 performance, anomalies, and test results in concurrence with the objectives outlined in CTP-0110, Revision D, Space Shuttle Technical Evaluation Motor No. 10 (TEM-10) Static Fire Test Plan.

  18. New TEM variant (TEM-92) produced by Proteus mirabilis and Providencia stuartii isolates.

    PubMed

    de Champs, C; Monne, C; Bonnet, R; Sougakoff, W; Sirot, D; Chanal, C; Sirot, J

    2001-04-01

    The sequences of the bla(TEM) genes encoding TEM-92 in Proteus mirabilis and Providencia stuartii isolates were determined and were found to be identical. Except for positions 218 (Lys-6) and 512 (Lys-104), the nucleotide sequence of bla(TEM-92) was identical to that of bla(TEM-20), including the sequence of the promoter region harboring a 135-bp deletion combined with a G-162-->T substitution. The deduced amino acid sequence of TEM-92 differed from that of TEM-52 by the presence of a substitution (Gln-6-->Lys) in the peptide signal.

  19. XRD and FTIR crystallinity indices in sound human tooth enamel and synthetic hydroxyapatite.

    PubMed

    Reyes-Gasga, José; Martínez-Piñeiro, Esmeralda L; Rodríguez-Álvarez, Galois; Tiznado-Orozco, Gaby E; García-García, Ramiro; Brès, Etienne F

    2013-12-01

    The crystallinity index (CI) is a measure of the percentage of crystalline material in a given sample and it is also correlated to the degree of order within the crystals. In the literature two ways are reported to measure the CI: X-ray diffraction and infrared spectroscopy. Although the CI determined by these techniques has been adopted in the field of archeology as a structural order measure in the bone with the idea that it can help e.g. in the sequencing of the bones in chronological and/or stratigraphic order, some debate remains about the reliability of the CI values. To investigate similarities and differences between the two techniques, the CI of sound human tooth enamel and synthetic hydroxyapatite (HAP) was measured in this work by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), at room temperature and after heat treatment. Although the (CI)XRD index is related to the crystal structure of the samples and the (CI)FTIR index is related to the vibration modes of the molecular bonds, both indices showed similar qualitative behavior for heat-treated samples. At room temperature, the (CI)XRD value indicated that enamel is more crystalline than synthetic HAP, while (CI)FTIR indicated the opposite. Scanning (SEM) and transmission (TEM) images were also used to corroborate the measured CI values.

  20. Technical Evaluation Motor no. 5 (TEM-5)

    NASA Technical Reports Server (NTRS)

    Cook, M.

    1990-01-01

    Technical Evaluation Motor No. 5 (TEM-5) was static test fired at the Thiokol Corporation Static Test Bay T-97. TEM-5 was a full scale, full duration static test fire of a high performance motor (HPM) configuration solid rocket motor (SRM). The primary purpose of TEM static tests is to recover SRM case and nozzle hardware for use in the redesigned solid rocket motor (RSRM) flight program. Inspection and instrumentation data indicate that the TEM-5 static test firing was successful. The ambient temperature during the test was 41 F and the propellant mean bulk temperature (PMBT) was 72 F. Ballistics performance values were within the specified requirements. The overall performance of the TEM-5 components and test equipment was nominal. Dissembly inspection revealed that joint putty was in contact with the inner groove of the inner primary seal of the ignitor adapter-to-forward dome (inner) joint gasket; this condition had not occurred on any previous static test motor or flight RSRM. While no qualification issues were addressed on TEM-5, two significant component changes were evaluated. Those changes were a new vented assembly process for the case-to-nozzle joint and the installation of two redesigned field joint protection systems. Performance of the vented case-to-nozzle joint assembly was successful, and the assembly/performance differences between the two field joint protection system (FJPS) configurations were compared.

  1. Modulation of synthetic parameters of cobalt nanoparticles: TEM, EDS, spectral and thermal studies.

    PubMed

    Chandra, Sulekh; Kumar, Avdhesh

    2012-12-01

    The study focuses on the modulation of synthetic parameters in order to influence the size, structure, composition and arrangement of nanoparticles of cobalt. Cobalt nanoparticles were synthesized by ethanolic solution of benzildiethylenetriamine in cobalt nitrate solution at 60 °C with stirring and refluxing leads to nanoparticles of cobalt. The morphology and structure of the synthesized nanoparticles of cobalt were characterized by Transmission Electron Microscopy (TEM), Powder X-ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), QELS Data and Infrared Spectroscopy (IR). Crystalline size was 20 nm determined from the sharp peak at 2θ=25 °C from the powder XRD. TEM images of cobalt nanoparticles without reducing agent having the diameter 20 nm with spherical shape and black color.

  2. TEM-STM for Novel Nanotechnological Experimentation

    NASA Astrophysics Data System (ADS)

    Vaughn, Joel

    2005-03-01

    We present the design and construction of a miniature scanning tunneling microscope (STM) to be used inside a transmission electron microscope (TEM). In our system, the entire STM head is fitted inside the TEM sample holder, which allows for both TEM imaging/diffraction and STM-tip indentation experiments. The positioning of STM-tip over the desired sample locations can be guided through the real time TEM images. In addition to the nano indentation experiments, the STM program also allows the state-of-the-art control of atom/molecule manipulation procedures [1]. This hybrid TEM-STM system can be used for nanoscale manipulation, electrical characterization and mechanical strength examination of various nanomaterials including nanowires, nanotubes and quantum dots. [1]. S.-W. Hla, K.-F. Braun, V. Iancu, A. Deshpande, Nano Lett. 4 (2004) 1997-2001. This work is financially supported by the NSF-NIRT grant no. DMR- 0304314 and the US-DOE grant no. DE-FG02-02ER46012.

  3. Technical Evaluation Motor No. 7 (TEM-07)

    NASA Technical Reports Server (NTRS)

    Hugh, Phil

    1991-01-01

    Technical Evaluation Motor Number 7 (TEM-7) was a full scale, full-duration static test firing of a high performance motor (HPM) configuration solid rocket motor (SRM) with nozzle vectoring. The static test fire occurred on 11 December 1990 at the Thiokol Corporation Static Test Bay T-97. Documented here are the procedures, performance, and results available through 22 January 1991. Critical post test hardware activities and assessment of the test data are not complete. A completed test report will be submitted 60 days after the test date. Included here is a presentation and discussion of the TEM-7 performance, anomalies, and test result concurrence with the objectives outlined in CTP-0107 Revision A, Space Shuttle Technical Evaluation Motor number 7 (TEM-07) Static Fire Test Plan.

  4. Silver Trees: Chemistry on a TEM Grid

    EPA Science Inventory

    The copper/carbon substrate of a TEM grid reacted with aqueous silver nitrate solution within minutes to yield spectacular tree-like silver dendrites, without using any added capping or reducing reagents. These results demonstrate a facile, aqueous, room temperature synthesis of...

  5. Design of a TEM cell EMP simulator

    NASA Astrophysics Data System (ADS)

    Sevat, Pete

    1991-06-01

    Electromagnetic pulse (EMP) simulators are designed to simulate the EMP generated by a nuclear weapon and are used to harden equipment against the effects of EMP. A transverse electromagnetic (TEM) cell is a square or rectangular coaxial transmission line tapered at each end to form a closed cell. The cell is fed at one end with a signal generator, a continuous wave or pulse generator, and terminated at the other end with a resistor equal to the characteristic impedance of the line. An advantage of the TEM cell is that the field is well characterized and reasonably uniform. A small, symmetric, TEM cell EMP simulator is described which is intended for applications such as susceptibility testing of small equipment, calibration of sensors, design and testing of countermeasures, measurement of transfer functions, and research and development. A detailed design is presented for a 50 ohm and 100 ohm TEM cell with an inner volume of 4 m(exp 3) and a test volume of 0.24 m(exp 3). The pulse generator and terminating network are integrated into the cell to form a completely shielded structure. In this way no interference from the inside of the cell to the outside, or vice versa, will occur.

  6. FTIR and XRD study of PMMA/PCTFE blend films

    SciTech Connect

    Tripathi, S. Shripathi, T.; Tripathi, J.; Agrawal, A.; Sharma, A.

    2014-04-24

    The results are reported on solution cast PMMA-PCTFE blend films characterized using x-ray diffraction and FTIR. The nanocrystalline nature of PMMA is still seen in the blends, however, the bond modifications are clearly observed. The addition of PCTFE results in the modification in structural properties, as reflected in the XRD and FTIR spectra showing modifications in bonding as a function of PCTFE percentage.

  7. Quantification of small, convex particles by TEM.

    PubMed

    Andersen, Sigmund J; Holme, Børge; Marioara, Calin D

    2008-07-01

    It is shown how size distributions of arbitrarily oriented, convex, non-overlapping particles extracted from conventional transmission electron microscopy (TEM) images may be determined by a variation of the Schwartz-Saltykov method. In TEM, particles cut at the surfaces have diminished projections, which alter the observed size distribution. We represent this distribution as a vector and multiply it with the inverse of a matrix comprising thickness-dependent Scheil or Schwartz-Saltykov terms. The result is a corrected size distribution of the projections of uncut particles. It is shown how the real (3D) distribution may be estimated when particle shape is considered. Computer code to generate the matrix is given. A log-normal distribution of spheres and a real distribution of pill-box-shaped dispersoids in an Al-Mg-Si alloy are given as examples. The errors are discussed in detail.

  8. LLNL Workshop on TEM of Pu

    SciTech Connect

    King, W.E.

    1996-09-10

    On Sept. 10, 1996, LLNL hosted a workshop aimed at answering the question: Is it possible to carry out transmission electron microscopy (TEM) on plutonium metal in an electron microscope located outside the LLNL plutonium facility. The workshop focused on evaluation of a proposed plan for Pu microscopy both from a technical and environment, health, and safety point of view. After review and modification of the plan, workshop participants unanimously concluded that: (1) the technical plan is sound, (2) this technical plan, including a proposal for a new TEM, provides significant improvements and unique capabilities compared with the effort at LANL and is therefore complementary, (3) there is no significant environment, health, and safety obstacle to this plan.

  9. Radial averages of astigmatic TEM images.

    PubMed

    Fernando, K Vince

    2008-10-01

    The Contrast Transfer Function (CTF) of an image, which modulates images taken from a Transmission Electron Microscope (TEM), is usually determined from the radial average of the power spectrum of the image (Frank, J., Three-dimensional Electron Microscopy of Macromolecular Assemblies, Oxford University Press, Oxford, 2006). The CTF is primarily defined by the defocus. If the defocus estimate is accurate enough then it is possible to demodulate the image, which is popularly known as the CTF correction. However, it is known that the radial average is somewhat attenuated if the image is astigmatic (see Fernando, K.V., Fuller, S.D., 2007. Determination of astigmatism in TEM images. Journal of Structural Biology 157, 189-200) but this distortion due to astigmatism has not been fully studied or understood up to now. We have discovered the exact mathematical relationship between the radial averages of TEM images with and without astigmatism. This relationship is determined by a zeroth order Bessel function of the first kind and hence we can exactly quantify this distortion in the radial averages of signal and power spectra of astigmatic images. The argument to this Bessel function is similar to an aberration function (without the spherical aberration term) except that the defocus parameter is replaced by the differences of the defoci in the major and minor axes of astigmatism. The ill effects due this Bessel function are twofold. Since the zeroth order Bessel function is a decaying oscillatory function, it introduces additional zeros to the radial average and it also attenuates the CTF signal in the radial averages. Using our analysis, it is possible to simulate the effects of astigmatism in radial averages by imposing Bessel functions on idealized radial averages of images which are not astigmatic. We validate our theory using astigmatic TEM images.

  10. Novel TEM-type extended-spectrum beta-lactamase, TEM-134, in a Citrobacter koseri clinical isolate.

    PubMed

    Perilli, Mariagrazia; Mugnaioli, Claudia; Luzzaro, Francesco; Fiore, Marianna; Stefani, Stefania; Rossolini, Gian Maria; Amicosante, Gianfranco

    2005-04-01

    A new natural TEM derivative with extended-spectrum beta-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The bla(TEM-134) gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.

  11. Porosity investigation of compacted bentonite using XRD profile modeling

    NASA Astrophysics Data System (ADS)

    Holmboe, Michael; Wold, Susanna; Jonsson, Mats

    2012-02-01

    Many countries intend to use compacted bentonite as a barrier in their deep geological repositories for nuclear waste. In order to describe and predict hydraulic conductivity or radionuclide transport through the bentonite barrier, fundamental understanding of the microstructure of compacted bentonite is needed. This study examined the interlayer swelling and overall microstructure of Wyoming Bentonite MX-80 and the corresponding homo-ionic Na + and Ca 2 + forms, using XRD with samples saturated under confined swelling conditions and free swelling conditions. For the samples saturated under confined conditions, the interparticle, or so-called free or external porosity was estimated by comparing the experimental interlayer distances obtained from one-dimensional XRD profile fitting against the maximum interlayer distances possible for the corresponding water content. The results showed that interlayer porosity dominated total porosity, irrespective of water content, and that the interparticle porosity was lower than previously reported in the literature. At compactions relevant for the saturated bentonite barrier (1.4-1.8 g/cm 3), the interparticle porosity was estimated to ≤ 3%.

  12. Silver Accumulation in the Green Microalga Coccomyxa actinabiotis: Toxicity, in Situ Speciation, and Localization Investigated Using Synchrotron XAS, XRD, and TEM.

    PubMed

    Leonardo, Thomas; Farhi, Emmanuel; Pouget, Stéphanie; Motellier, Sylvie; Boisson, Anne-Marie; Banerjee, Dipanjan; Rébeillé, Fabrice; den Auwer, Christophe; Rivasseau, Corinne

    2016-01-05

    Microalgae are good candidates for toxic metal remediation biotechnologies. This study explores the cellular processes implemented by the green microalga Coccomyxa actinabiotis to take up and cope with silver over the concentration range of 10(-7) to 10(-2) M Ag(+). Understanding these processes enables us to assess the potential of this microalga for applications for bioremediation. Silver in situ speciation and localization were investigated using X-ray absorption spectroscopy, X-ray diffraction, and transmission electron microscopy. Silver toxicity was evaluated by monitoring microalgal growth and photochemical parameters. Different accumulation mechanisms were brought out depending on silver concentration. At low micromolar concentration, microalgae fixed all silver initially present in solution, trapping it inside the cells into the cytosol, mainly as unreduced Ag(I) bound with molecules containing sulfur. Silver was efficiently detoxified. When concentration increased, silver spread throughout the cell and particularly entered the chloroplast, where it damaged the photosystem. Most silver was reduced to Ag(0) and aggregated to form crystalline silver nanoparticles of face-centered cubic structure with a mean size of 10 nm. An additional minor interaction of silver with molecules containing sulfur indicated the concomitant existence of the mechanism observed at low concentration or nanoparticle capping. Nanoparticles were observed in chloroplasts, in mitochondria, on the plasma membrane, on cytosolic membrane structures, and in vacuoles. Above 10(-4) M Ag(+), damages were irreversible, and photosynthesis and growth were definitely inhibited. However, high silver amounts remained confined inside microalgae, showing their potential for the bioremediation of contaminated water.

  13. Insights into the fine-grained fraction of serpentine mud from the Southern Chamorro seamount (ODP Leg 195): A combined XRD, RFA and TEM-EDS study

    NASA Astrophysics Data System (ADS)

    Lischka, M.; Meschede, M.; Warr, L. N.

    2009-12-01

    Serpentine mud volcanoes in the outer forearc of the Izu-Bonin-Mariana subduction system occur in a restricted zone, 50km - 120 km away from the trench axis [Fryer et al., 1985]. The morphotectonic elements of the forearc are dominated by horst and graben structures, caused by extensional movements and normal fault systems related to seamount subduction [Fryer et al., 2000; Stern and Smooth, 1998]. These faults may provide conduits for the diapiric uprising of low density serpentine, extruding at the seafloor in stratovolcanic like structures. Released fluids from the subducted slab at estimated depths of approximately 30km are considered to hydrate the forearc mantle wedge along those fractures [Benton et al., 2001; Mottl et al., 2003; Rübke et al., 2004]. During the formation of the fault gouge, serpentine-bodies entrained xenoliths and xenocrysts from the surrounding rocks and are exhumed towards the surface [Fryer et al., 1990]. In our investigation we focus on the silty to clay-sized particle fraction of the serpentine mud matrix, drilled during ODP Leg 195 at site 1200E. We analysed the bulk mineral composition with X-ray diffraction methods on random powder samples, supplemented by X-ray fluorescence measurements on 25 samples. To obtain more insights into the mineralogy fabric and microstructure of the samples, electron microscopy and electron dispersive spectroscopy were used to determine the crystal-chemistry and alteration textures. Particular emphasis was given on determining serpentine polymorphs and the nature of other phyllosilicates and their geochemical composition and constraints. Geochemical observation of the secondary mineral phases should allow us to reconstruct the processes linked with the migration of fluids and volatile components during subduction related metamorphism affecting the mantle wedge. Based on the new data we characterize the conditions of alteration products within a subduction factory, related to the diapiric deposition of serpentine mud volcanoes.

  14. Graphene nanoscrolls and live TEM imaging

    NASA Astrophysics Data System (ADS)

    Mokkapati, Venkata; Mirsaidov, Utkur; Matsudaira, Paul; Oezyilmaz, Barbaros; Graphene research laboratory Team; Centerbio-imaging sciences/Mechanobiology institute Team

    2013-03-01

    It has been theoretically hypothesized and predicted that graphene when in contact with water, wraps itself around the droplets and forms graphene nanoscrolls. Studying the applications of these nanoscrolls can open a new area of research especially in the bio-medical field. Here we present a method where partially suspended graphene nanoscrolls were fabricated on carbon mesh attached to a gold TEM grid. The process involves sandwiching of two graphene layers with water being encapsulated within these nanoscrolls. Gold nanoparticles were encapsulated and live imaging of water and gold nanoparticles was carried out under the TEM. The dynamics of the encapsulated water and nanobubbles is being studied. The encapsulated water within these graphene nanoscrolls lasted for more than three months (till the date of publication). It was also realized that the formation/abundance of these nanoscrolls is concentration dependent of the etching solution (Ammonium persulfate) with a saturation point. Large area, uniform, monolayer graphene films can also be produced by varying the concentration of Ammonium persulfate. Further studies are being carried out to live image TMV/protein and liposome encapsulated drugs using nanoscrolls and films respectively. The authors would like to acknowledge A*Star for funding this research

  15. Technical Evaluation Motor 3 (TEM-3)

    NASA Technical Reports Server (NTRS)

    Garecht, Diane

    1989-01-01

    A primary objective of the technical evaluation motor program is to recover the case, igniter and nozzle hardware for use on the redesigned solid rocket motor flight program. Two qualification objectives were addressed and met on TEM-3. The Nylok thread locking device of the 1U100269-03 leak check port plug and the 1U52295-04 safe and arm utilizing Krytox grease on the barrier-booster shaft O-rings were both certified. All inspection and instrumentation data indicate that the TEM-3 static test firing conducted 23 May 1989 was successful. The test was conducted at ambient conditions with the exception of the field joints (set point of 121 F, with a minimum of 87 F at the sensors), igniter joint (set point at 122 F with a minimum of 87 F at sensors) and case-to-nozzle joint (set point at 114 F with a minimum of 87 F at sensors). Ballistics performance values were within specification requirements. Nozzle performance was nominal with typical erosion. The nozzle and the case joint temperatures were maintained at the heaters controlling set points while electrical power was supplied. The water and the CO2 quench systems prevented damage to the metal hardware. All other test equipment performed as planned, contributing to a successful motor firing. All indications are that the test was a success, and all expected hardware will be refurbished for the RSRM program.

  16. A Combined XRD/XRF Instrument for Lunar Resource Assessment

    NASA Technical Reports Server (NTRS)

    Vaniman, D. T.; Bish, D. L.; Chipera, S. J.; Blacic, J. D.

    1992-01-01

    Robotic surface missions to the Moon should be capable of measuring mineral as well as chemical abundances in regolith samples. Although much is already known about the lunar regolith, our data are far from comprehensive. Most of the regolith samples returned to Earth for analysis had lost the upper surface, or it was intermixed with deeper regolith. This upper surface is the part of the regolith most recently exposed to the solar wind; as such it will be important to resource assessment. In addition, it may be far easier to mine and process the uppermost few centimeters of regolith over a broad area than to engage in deep excavation of a smaller area. The most direct means of analyzing the regolith surface will be by studies in situ. In addition, the analysis of the impact-origin regolith surfaces, the Fe-rich glasses of mare pyroclastic deposits, are of resource interest, but are inadequately known; none of the extensive surface-exposed pyroclastic deposits of the Moon have been systematically sampled, although we know something about such deposits from the Apollo 17 site. Because of the potential importance of pyroclastic deposits, methods to quantify glass as well as mineral abundances will be important to resource evaluation. Combined x ray diffraction (XRD) and x ray fluorescence (XRF) analysis will address many resource characterization problems on the Moon. XRF methods are valuable for obtaining full major-element abundances with high precision. Such data, collected in parallel with quantitative mineralogy, permit unambiguous determination of both mineral and chemical abundances where concentrations are high enough to be of resource grade. Collection of both XRD and XRF data from a single sample provides simultaneous chemical and mineralogic information. These data can be used to correlate quantitative chemistry and mineralogy as a set of simultaneous linear equations, the solution of which can lead to full characterization of the sample. The use of

  17. X-ray microdiffraction, TEM characterization and texture analysis of human dentin and enamel.

    PubMed

    Xue, J; Zavgorodniy, A V; Kennedy, B J; Swain, M V; Li, W

    2013-08-01

    Human tooth is a complex bioceramic composite, which consists of enamel, dentin and the interface, the dentin-enamel junction (DEJ). The crystal properties and ultrastructure of the inorganic phase through the thickness of healthy human molar teeth were investigated using X-ray microdiffraction (μXRD), electron diffraction and transmission electron microscopy (TEM) techniques. The XRD data were analysed using the Le Bail profile fitting approach. The size and the texture of the crystallites forming enamel and dentin in the crown part of teeth were measured using both techniques and then compared. Results showed that the thickness of dentin crystallites was found to decrease towards the DEJ, whereas the thickness of the enamel crystallites increased from the DEJ towards the outer layers. It was demonstrated that enamel exhibited an increase of texture in 002 lattice planes from the DEJ towards the outer layers. Texture was also detected in 102 lattice planes. The texture effect in 002 planes at the scale of less than 1 μm was also demonstrated in dentin. The variation of lattice parameters as a function of the position within the thickness of dentin and enamel was also observed. The values of the nonuniform microstrain in the dentin and enamel crystallites were from 1.40 × 10(-6) % to 4.44 × 10(-5) %. The good correlation between XRD and TEM indicated that μXRD is a useful technique to study crystallography and microstructure of heterogeneous enamel and dentin. The observed gradient characteristics of texture and crystallite size in enamel and dentin maybe an evolutionary outcome to resist wear and fracture, thereby contributing to the excellent mechanical properties of teeth.

  18. XRD analysis and leachability of solidified phenol-cement mixtures

    SciTech Connect

    Vipulanandan, C.; Krishnan, S. . Department of Civil and Environmental Engineering)

    1993-07-01

    The microstructure and leachability of phenol from solidified phenol-Portland cement mixtures cured up to 6 months were investigated. Phenol was solidified with Type I Portland cement at concentrations of 0.5% and 2% by weight of the cement. XRD studies and pore fluid analyses indicate that phenol inhibits cement setting by reacting with the calcium hydroxide produced during the hydration of cement. Phenol leachability was studied using the Toxicity Characteristic Leaching Procedure (TCLP) test recommended by the U. S. EPA. The quantity of phenol leached is dependent on the initial phenol concentration and the curing time and a simple model has been proposed to predict the leachability. Phenol increases the initial and final setting times of cement. The compressive strength of the solidified cement-phenol mixtures decrease with increasing phenol content in the matrix and increase with curing time. The relationship between leaching of phenol and strength of cement-phenol mixtures has been verified.

  19. High temperature XRD of Cu2GeSe3

    NASA Astrophysics Data System (ADS)

    Premkumar D., S.; Chetty, Raju; Malar, P.; Mallik, Ramesh Chandra

    2015-06-01

    The Cu2GeSe3 is prepared by solid state synthesis method. The high temperature XRD has been done at different temperature from 30 °C to 450 °C. The reitveld refinement confirms Cu2GeSe3 phase and orthorhombic crystal structure. The lattice constants are increasing with increase in the temperature and their rate of increase with respect to temperature are used for finding the thermal expansion coefficient. The calculation of the linear and volume coefficient of thermal expansion is done from 30 °C to 400 °C. Decrease in the values of linear expansion coefficients with temperature are observed along a and c axis. Since thermal expansion coefficient is the consequence of the distortion of atoms in the lattice; this can be further used to find the minimum lattice thermal conductivity at given temperature.

  20. [Infrared spectroscopy and XRD studies of coral fossils].

    PubMed

    Chen, Quan-li; Zhou, Guan-min; Yin, Zuo-wei

    2012-08-01

    Coral fossil is an old remain of multicellular animal on the earth, and formed by various geological processes. The structural characteristics and compositions of the coral fossils with different color and radial texture on the surface were studied by infrared absorption spectroscopy and X-ray powder diffraction analyses. The results show that the studied coral fossils mainly are composed of SiO2, and the radial microstructure characterized by the calcareous coral cross-section is preserved. It is formed by metasomatism by SiO2. The infrared absorption spectra of the coral fossil with different color and texture are essentially the same, showing typical infrared absorption spectra of the quartz jade. XRD analysis shows that the main components of the coral fossils with different color and texture are consistent and mainly composed of SiO2 with a trace amount of other minerals and without CaCO3.

  1. Vacancy ordering and superstructure formation in dry and hydrated strontium tantalate perovskites: a TEM perspective.

    PubMed

    Ashok, Anuradha M; Haavik, Camilla; Norby, Poul; Norby, Truls; Olsen, Arne

    2014-07-01

    Crystal structures of Sr4(Sr2Ta2)O11 and Sr4(Sr1.92Ta2.08)O11.12, synthesized by solid state reaction technique in dry and hydrated state have been studied mainly using Transmission Electron Microscopy. Due to the lesser ability of X-rays to probe details in oxygen sublattice, the change in crystal symmetry due to ordering of oxygen vacancies could be detected better using Transmission Electron Microscopy. After detailed analysis through TEM, it was observed that no major change occurs in the cation sublattice. The TEM observations are compared with XRD data and discussed. The crystal symmetries and corresponding unit cells of all the perovskites based on the ordering of oxygen vacancies is deduced. Crystal unit cells based on the observations are proposed with ideal atomic coordinates. Finally an attempt is made to explain the water uptake behaviour of these perovskites based on the proposed crystal structure.

  2. Quantifying Nonspecific TEM β-Lactamase (blaTEM) Genes in a Wastewater Stream▿

    PubMed Central

    Lachmayr, Karen L.; Kerkhof, Lee J.; DiRienzo, A. Gregory; Cavanaugh, Colleen M.; Ford, Timothy E.

    2009-01-01

    To control the antibiotic resistance epidemic, it is necessary to understand the distribution of genetic material encoding antibiotic resistance in the environment and how anthropogenic inputs, such as wastewater, affect this distribution. Approximately two-thirds of antibiotics administered to humans are β-lactams, for which the predominant bacterial resistance mechanism is hydrolysis by β-lactamases. Of the β-lactamases, the TEM family is of overriding significance with regard to diversity, prevalence, and distribution. This paper describes the design of DNA probes universal for all known TEM β-lactamase genes and the application of a quantitative PCR assay (also known as Taqman) to quantify these genes in environmental samples. The primer set was used to study whether sewage, both treated and untreated, contributes to the spread of these genes in receiving waters. It was found that while modern sewage treatment technologies reduce the concentrations of these antibiotic resistance genes, the ratio of blaTEM genes to 16S rRNA genes increases with treatment, suggesting that bacteria harboring blaTEM are more likely to survive the treatment process. Thus, β-lactamase genes are being introduced into the environment in significantly higher concentrations than occur naturally, creating reservoirs of increased resistance potential. PMID:18997031

  3. SIMS and TEM Analysis of Niobium Bicrystals

    SciTech Connect

    Maheshwari, P; Griffis, D P; Stevie, F A; Zhou, C; Ciovati, G; Myneni, R; Spradlin, J K; Rigsbee, M

    2011-07-01

    The behaviour of interstitial impurities(C,O,N,H) on the Nb surface with respect to grain boundaries may affect cavity performance. Large grain Nb makes possible the selection of bicrystal samples with a well defined grain boundary. In this work, Dynamic SIMS was used to analyze two Nb bicrystal samples, one of them heat treated and the other non heat treated (control). H levels were found to be higher for the non heat treated sample and a difference in the H intensity and sputtering rate was also observed across the grain boundary for both the samples. TEM results showed that the bicrystal interface showed no discontinuity and the oxide layer was uniform across the grain boundary for both the samples. TOF-SIMS imaging was also performed to analyze the distribution of the impurities across the grain boundary in both the samples. C was observed to be segregated along the grain boundary for the control sample, while H and O showed a difference in signal intensity across the grain boundary. Crystal orientation appears to have an important role in the observed sputtering rate and impurity ion signal differences both across the grain boundary and between samples

  4. Motorized manipulator for positioning a TEM specimen

    DOEpatents

    Schmid, Andreas Karl; Andresen, Nord

    2010-12-14

    The invention relates to a motorized manipulator for positioning a TEM specimen holder with sub-micron resolution parallel to a y-z plane and rotating the specimen holder in the y-z plane, the manipulator comprising a base (2), and attachment means (30) for attaching the specimen holder to the manipulator, characterized in that the manipulator further comprises at least three nano-actuators (3.sup.a, 3.sup.b, 3.sup.c) mounted on the base, each nano-actuator showing a tip (4.sup.a, 4.sup.b, 4.sup.c), the at least three tips defining the y-z plane, each tip capable of moving with respect to the base in the y-z plane; a platform (5) in contact with the tips of the nano-actuators; and clamping means (6) for pressing the platform against the tips of the nano-actuators; as a result of which the nano-actuators can rotate the platform with respect to the base in the y-z plane and translate the platform parallel to the y-z plane.

  5. Mirrored low-energy channel for the MiniXRD

    SciTech Connect

    Dutra, Eric; MacNeil, Lawrence; Raphaelian, Mark; Compton, Steve; Jacoby, Barry

    2015-10-08

    X-ray Diodes (XRDs) are currently used for spectroscopic measurements, measuring X-ray flux, and estimating spectral shape of the VUV to soft X-ray spectrum. A niche exists for an inexpensive, robust X-ray diode that can be used for experiments in hostile environments on multiple platforms, including explosively driven experiments that have the potential for destroying the diode during the experiment. A multiple channel stacked filtered array was developed with a small field of view where a wider parallel array could not be used, but filtered channels for energies lower than 1000 eV were too fragile to deploy under normal conditions. To achieve both the robustness and the required low-energy detection ability, the researchers designed a small low-energy mirrored channel with a spectral sensitivity from 30 to 1000 eV. The stacked MiniXRD X-ray diode system design incorporates the mirrored low-energy channel on the front of the stacked filtered channels to allow the system to work within a small field of view. We will present results that demonstrate this is a promising solution for low-energy spectrum measurements.

  6. Gahnite under high pressure: A XRD insitu study

    NASA Astrophysics Data System (ADS)

    Lathe, Christian; Wehber, Michael; Schilling, Frank; Mueller, Hans

    2013-06-01

    Placing P-T-t constraints on planetary differentiation Natural gahnite has the ideal formula ZnAl2O4. Together with franklinite (ZnFe2O4) it forms a limited solid solution at high temperatures an occurs as an accessory phase in magmatic and metamorphic rocks, but mainly in the Franklin marble and skarn deposits (Carvalho and Sclar 1988, Frondel and Baum 1974). A natural gahnite sample was investigated with large volume presses at the Synchrotron source DESY. Pressure was stepwise increased to 5 GPa at the MAX80 and 15 GPa at MAX200x and diffraction patterns were collected after each step. The determined volume-pressure-data are fitted to a 2nd and 3rd order Birch-Murnaghan equation of state to obtain the isothermal bulk modulus KT0 and its pressure derivative K'. Isothermal bulk modulus was derived from XRD data. Using a 2nd and 3rd order Birch-Murnaghan equation of state revealed KT02nd = 207(4) GPa KT03rd = 204(4) GPa and K' = 4.9(3), respectively. A significant change of the pressure derivatives of C11, C12 and C44 at a pressure of approximately 15 GPa indicates a 2nd order phase transition in gahnite.

  7. RBS and XRD Characterization of Yttrium Iron Garnet Thin Films

    NASA Astrophysics Data System (ADS)

    Mansour, M.; Roumie, M.; Abdel Samad, B.; Basma, H.; Korek, M.

    2015-03-01

    Magnetic materials such as yttrium iron garnet (YIG or Y3Fe5O12) present a great importance for their magneto-optic properties. They are potential materials used for applications in the domain of optical telecommunications for example. In this work, we have investigated YIG thin films deposited on substrates of quartz and GGG (gadolinium gallium garnet or Gd3Ga5O12). Using Rutherford backscattering spectrometry (RBS) we characterized the performed layers (thickness and stoichiometry) in order to correlate the films preparation conditions with the quality of the final material. We determined the optimal energy of the alpha particles beam used for RBS measurements and we fitted the experimental spectra using the SIMNRA simulated code. Our RBS results showed that the films have a stoichiometry close to that of the starting material. In addition, we found that the film thickness is proportional to deposition time but inversely proportional to the substrate temperature. Moreover, using x-ray diffraction (XRD) we determined the annealing effect on the structure of the profile of our thin films.

  8. A-10/TF34 Turbine Engine Monitoring System (TEMS)

    NASA Technical Reports Server (NTRS)

    Christopher, R. G.

    1981-01-01

    The hardware and software development of the A-10/TF34 turbine engine monitoring system (TEMS) is described. The operation and interfaces of the A-10/TF34 TEMS hardware are discussed with particular emphasis on function, capabilities, and limitations. The TEMS data types are defined and the various data acquisition modes are explained. Potential data products are also discussed.

  9. OBSERVATION OF DIPOLAR FERROMAGNETISM BY TEM TECHNIQUES.

    SciTech Connect

    BELEGGIA, M.ZHU,Y.TANDON,S.ET AL.

    2004-08-01

    Magnetostatic interactions play a central role in determining the magnetic response of an array of patterned magnetic elements or magnetized nanoparticles of given shape. The Fourier space approach recently introduced for the analytical computation of the demagnetizing tensor, field and energy for particles of arbitrary shape [1], has been recently extended to cover interactions between elements [2]. The main achievement has been the definition of a generalized dipole-dipole interaction for cylindrical objects, which takes into account the influence of shape anisotropy without resorting to,any kind of approximations [3]. Once the interaction energy is available, it becomes possible to evaluate the minimum energy state of the system for a given set of external parameters (such as applied field, aspect ratio, distance between elements). It turns out that, below a critical combination of aspect ratios and distances, the system undergoes a phase transition, changing abruptly from a closure domain state, with zero net magnetization, to a dipolar ferromagnetic state with a net magnetization which depends on the interaction strength between the elements. In order to observe this phenomenon by TEM, it is necessary to estimate the feasibility of the experiment by a series of simulations. Figure 1 shows the electron optical phase shifts for the system of three weakly (a-c) and strongly (d) interacting disks. The elements have a radius of 50 nm, a thickness of 5 nm (aspect ratio 1/20), and are uniformly magnetized at 2 T. By comparing Fig.1 (c) and (d), it can be seen that the fingerprint of the transition is the presence of fringing fields around the elements, revealed by the cosine fringes which resemble a dipole-like field in (d). When the system is in the closure-domain state, as in (a-c), no fringing field can be observed on a large scale. Figure 2 shows a set of Fresnel images, calculated for the same configurations as in Fig.1. As the Fresnel technique is scarcely

  10. Rapid approximate inversion of airborne TEM

    NASA Astrophysics Data System (ADS)

    Fullagar, Peter K.; Pears, Glenn A.; Reid, James E.; Schaa, Ralf

    2015-11-01

    Rapid interpretation of large airborne transient electromagnetic (ATEM) datasets is highly desirable for timely decision-making in exploration. Full solution 3D inversion of entire airborne electromagnetic (AEM) surveys is often still not feasible on current day PCs. Therefore, two algorithms to perform rapid approximate 3D interpretation of AEM have been developed. The loss of rigour may be of little consequence if the objective of the AEM survey is regional reconnaissance. Data coverage is often quasi-2D rather than truly 3D in such cases, belying the need for `exact' 3D inversion. Incorporation of geological constraints reduces the non-uniqueness of 3D AEM inversion. Integrated interpretation can be achieved most readily when inversion is applied to a geological model, attributed with lithology as well as conductivity. Geological models also offer several practical advantages over pure property models during inversion. In particular, they permit adjustment of geological boundaries. In addition, optimal conductivities can be determined for homogeneous units. Both algorithms described here can operate on geological models; however, they can also perform `unconstrained' inversion if the geological context is unknown. VPem1D performs 1D inversion at each ATEM data location above a 3D model. Interpretation of cover thickness is a natural application; this is illustrated via application to Spectrem data from central Australia. VPem3D performs 3D inversion on time-integrated (resistive limit) data. Conversion to resistive limits delivers a massive increase in speed since the TEM inverse problem reduces to a quasi-magnetic problem. The time evolution of the decay is lost during the conversion, but the information can be largely recovered by constructing a starting model from conductivity depth images (CDIs) or 1D inversions combined with geological constraints if available. The efficacy of the approach is demonstrated on Spectrem data from Brazil. Both separately and in

  11. XRD studies of chitin-based polyurethane elastomers.

    PubMed

    Zia, Khalid Mahmood; Bhatti, Ijaz Ahmad; Barikani, Mehdi; Zuber, Mohammad; Sheikh, Munir Ahmad

    2008-08-15

    Chitin-based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly(epsilon-caprolactone) (PCL) varying diisocyanate and chain extender structures. The viscosity average molecular weight (M(v)) of chitin was deduced from the intrinsic viscosity and found; M(v)=6.067 x 10(5). The conventional spectroscopic characterization of the samples with FTIR, (1)H NMR and (13)C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and loss tangent curves (tan delta peaks). The observed patterns of the crystalline peaks for the lower angle for chitin in the 2theta range were indexed as 9.39 degrees, 19.72 degrees, 20.73 degrees, 23.41 degrees and 26.39 degrees. Results showed that crystallinity of the synthesized PUEs samples was affected by varying the structure of the diisocyanate and chain extender. Crystallinity decreased from aliphatic to aromatic characters of the diisocyanates used in the final PU. The presence of chitin also favors the formation of more ordered structure, as higher peak intensities was obtained from the PU extended with chitin than 1,4-butane diol (BDO). The value of peak enthalpy (DeltaH) of chitin was found to be 47.13 J g(-1). The higher DeltaH value of 46.35 J g(-1) was found in the samples extended with chitin than BDO (39.73 J g(-1)).

  12. In situ TEM of radiation effects in complex ceramics.

    PubMed

    Lian, Jie; Wang, L M; Sun, Kai; Ewing, Rodney C

    2009-03-01

    In situ transmission electron microscopy (TEM) has been extensively applied to study radiation effects in a wide variety of materials, such as metals, ceramics and semiconductors and is an indispensable tool in obtaining a fundamental understanding of energetic beam-matter interactions, damage events, and materials' behavior under intense radiation environments. In this article, in situ TEM observations of radiation effects in complex ceramics (e.g., oxides, silicates, and phosphates) subjected to energetic ion and electron irradiations have been summarized with a focus on irradiation-induced microstructural evolution, changes in microchemistry, and the formation of nanostructures. New results for in situ TEM observation of radiation effects in pyrochlore, A(2)B(2)O(7), and zircon, ZrSiO(4), subjected to multiple beam irradiations are presented, and the effects of simultaneous irradiations of alpha-decay and beta-decay on the microstructural evolution of potential nuclear waste forms are discussed. Furthermore, in situ TEM results of radiation effects in a sodium borosilicate glass subjected to electron-beam exposure are introduced to highlight the important applications of advanced analytical TEM techniques, including Z-contrast imaging, energy filtered TEM (EFTEM), and electron energy loss spectroscopy (EELS), in studying radiation effects in materials microstructural evolution and microchemical changes. By combining ex situ TEM and advanced analytical TEM techniques with in situ TEM observations under energetic beam irradiations, one can obtain invaluable information on the phase stability and response behaviors of materials under a wide range of irradiation conditions.

  13. XRD measurement of mean crystallite thickness of illite and illite/smectite: Reappraisal of the Kubler index and the Scherrer equation

    USGS Publications Warehouse

    Drits, V.; Srodon, J.; Eberl, D.D.

    1997-01-01

    The standard form of the Scherrer equation, which has been used to calculate the mean thickness of the coherent scattering domain (CSD) of illite crystals from X-ray diffraction (XRD) full width data at half maximum (FWHM) intensity, employs a constant, Ksh, of 0.89. Use of this constant is unjustified, even if swelling has no effect on peak broadening, because this constant is valid only if all CSDs have a single thickness. For different thickness distributions, the Scherrer "constant" has very different values. Analysis of fundamental particle thickness data (transmission electron microscopy, TEM) for samples of authigenic illite and illite/smectite from diagenetically altered pyroclastics and filamentous illites from sandstones reveals a unique family of lognormal thickness distributions for these clays. Experimental relations between the distributions' lognormal parameters and mean thicknesses are established. These relations then are used to calculate the mean thickness of CSDs for illitic samples from XRD FWHM, or from integral XRD peak widths (integrated intensity/maximum intensity). For mixed-layer illite/smectite, the measured thickness of the CSD corresponds to the mean thickness of the mixed-layer crystal. Using this measurement, the mean thickness of the fundamental particles that compose the mixed-layer crystals can be calculated after XRD determination of precent smectitic interlayers. The effect of mixed layering (swelling) on XRD peak width for these samples is eliminated by using the 003 reflection for glycolated samples, and the 001, 002 or 003 reflection for dehydrated, K-saturated samples. If this technique is applied to the 001 reflection of air-dried samples (Kubler index measurement), mean CSD thicknesses are underestimated due to the mixed-layering effect. The technique was calibrated using NEWMOD ??-simulated XRD profiles of illite, and then tested on well-characterized illite and illite/smectite smaples. The XRD measurements are in good

  14. The Structural Bases of Antibiotic Resistance in the Clinically Derived Mutant beta-Lactamases TEM-30, TEM-32, and TEM-34

    SciTech Connect

    Wang, Xiaojun; Minasov, George; Shoichet, Brian K.

    2010-03-08

    Widespread use of {beta}-lactam antibiotics has promoted the evolution of {beta}-lactamase mutant enzymes that can hydrolyze ever newer classes of these drugs. Among the most pernicious mutants are the inhibitor-resistant TEM {beta}-lactamases (IRTs), which elude mechanism-based inhibitors, such as clavulanate. Despite much research on these IRTs, little is known about the structural bases of their action. This has made it difficult to understand how many of the resistance substitutions act as they often occur far from Ser-130. Here, three IRT structures, TEM-30 (R244S), TEM-32 (M69I/M182T), and TEM-34 (M69V), are determined by x-ray crystallography at 2.00, 1.61, and 1.52 {angstrom}, respectively. In TEM-30, the Arg-244 {yields} Ser substitution (7.8 {angstrom} from Ser-130) displaces a conserved water molecule that usually interacts with the {beta}-lactam C3 carboxylate. In TEM-32, the substitution Met-69 {yields} Ile (10 {angstrom} from Ser-130) appears to distort Ser-70, which in turn causes Ser-130 to adopt a new conformation, moving its O{gamma} further away, 2.3 {angstrom} from where the inhibitor would bind. This substitution also destabilizes the enzyme by 1.3 kcal/mol. The Met-182 {yields} Thr substitution (20 {angstrom} from Ser-130) has no effect on enzyme activity but rather restabilizes the enzyme by 2.9 kcal/mol. In TEM-34, the Met-69 {yields} Val substitution similarly leads to a conformational change in Ser-130, this time causing it to hydrogen bond with Lys-73 and Lys-234. This masks the lone pair electrons of Ser-130 O{gamma}, reducing its nucleophilicity for cross-linking. In these three structures, distant substitutions result in accommodations that converge on the same point of action, the local environment of Ser-130. TEM-1 {beta}-lactamase is the predominant source of resistance to {beta}-lactams, such as the penicillins. TEM-1 and related class A {beta}-lactamases confer resistance by hydrolyzing the {beta}-lactam ring of these antibiotics

  15. Transmission Electron Microscopy (TEM) Sample Preparation of Si(1-x)Gex in c-Plane Sapphire Substrate

    NASA Technical Reports Server (NTRS)

    Kim, Hyun Jung; Choi, Sang H.; Bae, Hyung-Bin; Lee, Tae Woo

    2012-01-01

    The National Aeronautics and Space Administration-invented X-ray diffraction (XRD) methods, including the total defect density measurement method and the spatial wafer mapping method, have confirmed super hetero epitaxy growth for rhombohedral single crystalline silicon germanium (Si1-xGex) on a c-plane sapphire substrate. However, the XRD method cannot observe the surface morphology or roughness because of the method s limited resolution. Therefore the authors used transmission electron microscopy (TEM) with samples prepared in two ways, the focused ion beam (FIB) method and the tripod method to study the structure between Si1-xGex and sapphire substrate and Si1?xGex itself. The sample preparation for TEM should be as fast as possible so that the sample should contain few or no artifacts induced by the preparation. The standard sample preparation method of mechanical polishing often requires a relatively long ion milling time (several hours), which increases the probability of inducing defects into the sample. The TEM sampling of the Si1-xGex on sapphire is also difficult because of the sapphire s high hardness and mechanical instability. The FIB method and the tripod method eliminate both problems when performing a cross-section TEM sampling of Si1-xGex on c-plane sapphire, which shows the surface morphology, the interface between film and substrate, and the crystal structure of the film. This paper explains the FIB sampling method and the tripod sampling method, and why sampling Si1-xGex, on a sapphire substrate with TEM, is necessary.

  16. Updated Sequence Information for TEM β-Lactamase Genes

    PubMed Central

    Goussard, Sylvie; Courvalin, Patrice

    1999-01-01

    The sequences of the promoter regions and of the structural genes for 13 penicillinase, extended-spectrum, and inhibitor-resistant TEM-type β-lactamases have been determined, and an updated blaTEM gene nomenclature is proposed. PMID:9925535

  17. Recognition and Resistance in TEM [superscript beta]-Lactamase

    SciTech Connect

    Wang, Xiaojun; Minasov, George; Blazquez, Jesus; Caselli, Emilia; Prati, Fabio; Shoichet, Brian K.

    2010-03-08

    Developing antimicrobials that are less likely to engender resistance has become an important design criterion as more and more drugs fall victim to resistance mutations. One hypothesis is that the more closely an inhibitor resembles a substrate, the more difficult it will be to develop resistant mutations that can at once disfavor the inhibitor and still recognize the substrate. To investigate this hypothesis, 10 transition-state analogues, of greater or lesser similarity to substrates, were tested for inhibition of TEM-1 beta-lactamase, the most widespread resistance enzyme to penicillin antibiotics. The inhibitors were also tested against four characteristic mutant enzymes: TEM-30, TEM-32, TEM-52, and TEM-64. The inhibitor most similar to the substrate, compound 10, was the most potent inhibitor of the WT enzyme, with a K(i) value of 64 nM. Conversely, compound 10 was the most susceptible to the TEM-30 (R244S) mutant, for which inhibition dropped by over 100-fold. The other inhibitors were relatively impervious to the TEM-30 mutant enzyme. To understand recognition and resistance to these transition-state analogues, the structures of four of these inhibitors in complex with TEM-1 were determined by X-ray crystallography. These structures suggest a structural basis for distinguishing inhibitors that mimic the acylation transition state and those that mimic the deacylation transition state; they also suggest how TEM-30 reduces the affinity of compound 10. In cell culture, this inhibitor reversed the resistance of bacteria to ampicillin, reducing minimum inhibitory concentrations of this penicillin by between 4- and 64-fold, depending on the strain of bacteria. Notwithstanding this activity, the resistance of TEM-30, which is already extant in the clinic, suggests that there can be resistance liabilities with substrate-based design.

  18. Novel Sample-handling Approach for XRD Analysis with Minimal Sample Preparation

    NASA Technical Reports Server (NTRS)

    Sarrazin, P.; Chipera, S.; Bish, D.; Blake, D.; Feldman, S.; Vaniman, D.; Bryson, C.

    2004-01-01

    Sample preparation and sample handling are among the most critical operations associated with X-ray diffraction (XRD) analysis. These operations require attention in a laboratory environment, but they become a major constraint in the deployment of XRD instruments for robotic planetary exploration. We are developing a novel sample handling system that dramatically relaxes the constraints on sample preparation by allowing characterization of coarse-grained material that would normally be impossible to analyze with conventional powder-XRD techniques.

  19. Remote In-Situ Quantitative Mineralogical Analysis Using XRD/XRF

    NASA Technical Reports Server (NTRS)

    Blake, D. F.; Bish, D.; Vaniman, D.; Chipera, S.; Sarrazin, P.; Collins, S. A.; Elliott, S. T.

    2001-01-01

    X-Ray Diffraction (XRD) is the most direct and accurate method for determining mineralogy. The CHEMIN XRD/XRF instrument has shown promising results on a variety of mineral and rock samples. Additional information is contained in the original extended abstract.

  20. Instability of nanoscale metallic particles under electron irradiation in TEM

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Zhang, S. G.; Xia, M. X.; Li, J. G.

    2016-03-01

    The stability of nano metallic glass under electron beam in transmission electron microscope (TEM) was investigated. The most common voltage of TEM used in metallic materials characterization was either 200 kV or 300 kV. Both situations were investigated in this work. An amorphous metallic particle with a dimension of a few hundred nanometers was tested under 300 keV electron irradiation. New phase decomposed from the parent phase was observed. Moreover, a crystal particle with the same composition and dimension was tested under 200 keV irradiation. Decomposition process also occurred in this situation. Besides, crystal orientation modification was observed during irradiation. These results proved that the electron beam in TEM have an effect on the stability of nanoscale samples during long time irradiation. Atomic displacement was induced and diffusion was enhanced by electron irradiation. Thus, artifacts would be induced when a nanoscale metallic sample was characterized in TEM.

  1. Preparation of carbon-free TEM microgrids by metal sputtering.

    PubMed

    Janbroers, S; de Kruijff, T R; Xu, Q; Kooyman, P J; Zandbergen, H W

    2009-08-01

    A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775K under vacuum conditions.

  2. TEM Study of Internal Crystals in Supernova Graphites

    NASA Astrophysics Data System (ADS)

    Croat, T. K.; Bernatowicz, T.; Stadermann, F. J.; Messenger, S.; Amari, S.

    2003-03-01

    A coordinated TEM and isotopic study of ten supernova (SN) graphites from the Murchison meteorite has revealed many internal grains, mostly titanium carbides (TiCs) and TiC-kamacite composite grains, which were accreted during the graphite growth.

  3. Appendix B: Summary of TEM Particle Size Distribution Datasets

    EPA Pesticide Factsheets

    As discussed in the main text (see Section 5.3.2), calculation of the concentration of asbestos fibers in each of the bins of potential interest requires particle size distribution data derived using transmission electron microscopy (TEM).

  4. Stability of mineral fibres in contact with human cell cultures. An in situ μXANES, μXRD and XRF iron mapping study.

    PubMed

    Pollastri, Simone; Gualtieri, Alessandro F; Vigliaturo, Ruggero; Ignatyev, Konstantin; Strafella, Elisabetta; Pugnaloni, Armanda; Croce, Alessandro

    2016-12-01

    Relevant mineral fibres of social and economic importance (chrysotile UICC, crocidolite UICC and a fibrous erionite from Jersey, Nevada, USA) were put in contact with cultured diploid human non-tumorigenic bronchial epithelial (Beas2B) and pleural transformed mesothelial (MeT5A) cells to test their cytotoxicity. Slides of each sample at different contact times up to 96 h were studied in situ using synchrotron XRF, μ-XRD and μ-XAS (I18 beamline, Diamond Light Source, UK) and TEM investigations. XRF maps of samples treated for 96 h evidenced that iron is still present within the chrysotile and crocidolite fibres and retained at the surface of the erionite fibres, indicating its null to minor mobilization in contact with cell media; this picture was confirmed by the results of XANES pre-edge analyses. μ-XRD and TEM data indicate greater morphological and crystallinity modifications occurring in chrysotile, whereas crocidolite and erionite show to be resistant in the biological environment. The contact of chrysotile with the cell cultures seems to lead to earlier amorphization, interpreted as the first dissolution step of these fibres. The formation of such silica-rich fibre skeleton may prompt the production of HO in synergy with surface iron species and could indicate that chrysotile may be much more reactive and cytotoxic in vitro in the (very) short term whereas the activity of crocidolite and erionite would be much more sluggish but persistent in the long term.

  5. In-situ TEM observation on STM tunneling gap

    NASA Astrophysics Data System (ADS)

    Kim, Suhyun; Tanishiro, Yasumasa; Takayanagi, Kunio

    2009-03-01

    Transmission Electron Microscope and Scanning Tunneling Microscope in an ultra high vacuum environment (UHV-TEM-STM) have been combined to simultaneously perform both high resolution TEM and atomically resolved STM experiments. This system was constructed for in-situ investigation of physical property of impurity atoms embedded below semiconductor surface. To image TEM and STM at the same time, crucial requirement is that, the STM image must be acquired under the electron beam irradiation. As a preliminary test, we used HOPG (Highly Oriented Pyrolytic Graphite) sample and tungsten tip as schematically shown in Fig 1(a). Fig 1(b) shows an atomic resolution STM image of HOPG obtained with 300mV sample bias and 3nA tunneling current even in the condition of the electron beam irradiation on the tip. TEM image can be simultaneously acquired by performing In-situ TEM observation on STM tunneling gap formed between the tip and a thin sample. Fig 1(a) Geometry of STM observation on STM tunneling gap Fig 1(b) STM image of HOPG obtained with 300mV sample bias and 3nA tunneling current

  6. Detecting flaws in Portland cement concrete using TEM horn antennae

    NASA Astrophysics Data System (ADS)

    Al-Qadi, Imad L.; Riad, Sedki M.; Su, Wansheng; Haddad, Rami H.

    1996-11-01

    To understand the dielectric properties of PCC and better correlate them with type and severity of PCC internal defects, a study was conducted to evaluate PCC complex permittivity and magnetic permeability over a wideband of frequencies using both time domain and frequency domain techniques. Three measuring devices were designed and fabricated: a parallel plate capacitor, a coaxial transmission line, and transverse electromagnetic (TEM) horn antennae. The TEM horn antenna covers the microwave frequencies. The measurement technique involves a time domain setup that was verified by a frequency domain measurement. Portland cement concrete slabs, 60 by 75 by 14 cm, were cast; defects include delamination, delamination filled with water, segregation, and chloride contamination. In this paper, measurements using the TEM horn antennae and the feasibility of detecting flaws at microwave frequency are presented.

  7. A single-tilt TEM stereomicroscopy technique for crystalline materials.

    PubMed

    McCabe, Rodney J; Misra, Amit; Mitchell, Terence E; Alexander, Kathleen B

    2003-02-01

    A new single-tilt technique for performing TEM stereomicroscopy of strain fields in crystalline materials has been developed. The technique is a weak beam technique that involves changing the value of g and/or s g while tilting across a set of Kikuchi bands. The primary benefit of the technique is it can be used with single-tilt TEM specimen holders including many specialty holders such as in situ straining, heating, and cooling holders. Standard stereo-TEM techniques are almost always limited to holders allowing two degrees of rotational freedom (i.e., double-tilt or tilt/rotation holders). An additional benefit of the new technique is that it eliminates the need to focus with the specimen height control. These advantages make it useful for stereo viewing or for quantitative stereomicroscopy provided necessary consideration is given to errors that may result from the technique.

  8. Chromium and aluminum biosorption on Chryseomonas luteola TEM05.

    PubMed

    Ozdemir, G; Baysal, S H

    2004-05-01

    Cr(VI) and Al(III) are environmental pollutants that are frequently encountered together in industrial wastewaters, e.g., from mining iron-steel, metal cleaning, plating, metal processing, automobile parts, and the manufacturing and dye industries. In this work, several variables that affect the capacity for chromium and aluminum biosorption by Chryseomonas luteola TEM05 were studied, particularly the effects of pH, metal concentration and contact time. Optimum adsorption pH values of Cr(VI) and Al(III) were determined as 4.0 and 5.0, respectively. The biosorption equilibrium was described by Freundlich and Langmuir adsorption isotherms. The value of Qo appears to be significantly higher for the Al(III) C. luteola TEM05 system. Langmuir parameters of C. luteola TEM05 also indicated a maximum adsorption capacity of 55.2 mg g(-1) for Al(III) and 3.0 mg g(-1) for Cr(VI).

  9. Mineralogical Composition of the Mexican Ordinary Chondrite Type Meteorite: A Raman, Infrared and XRD Study

    NASA Astrophysics Data System (ADS)

    Ostrooumov, M.

    2016-08-01

    The Raman microprobe (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of seven mexican meteorites: Aldama, Cosina, El Pozo, Escalon, Nuevo Mercurio,Pacula, Zapotitlan Salinas.

  10. Complete Tem-Tomography: 3D Structure of Gems Cluster

    NASA Technical Reports Server (NTRS)

    Matsuno, J.; Miyake, A.; Tsuchiyama, A.; Messenger, S.; Nakamura-Messenger, K.

    2015-01-01

    GEMS (glass with embedded metal and sulfide) grains in interplanetary dust particles (IDPs) are considered to be one of the ubiquitous and fundamental building blocks of solids in the Solar System. They have been considered to be interstellar silicate dust that survived various metamorphism or alteration processes in the protoplanetary disk but the elemental and isotopic composition measurements suggest that most of them have been formed in the protoplanetary disk as condensates from high temperature gas. This formation model is also supported by the formation of GEMS-like grains with respect to the size, mineral assemblage, texture and infrared spectrum by condensation experiments from mean GEMS composition materials. Previous GEMS studies were performed only with 2D observation by transmission electron microscopy (TEM) or scanning TEM (STEM). However, the 3D shape and structure of GEMS grains and the spatial distribution of Fe/FeS's has critical information about their formation and origin. Recently, the 3D structure of GEMS grains in ultrathin sections of cluster IDPs was revealed by electron tomography using a TEM/STEM (JEM-2100F, JEOL). However, CT images of thin sections mounted on Cu grids acquired by conventional TEM-tomography are limited to low tilt angles (e. g., less than absolute value of 75 deg. In fact, previous 3D TEM observations of GEMS were affected by some artifacts related to the limited tilt range in the TEM used. Complete tomographic images should be acquired by rotating the sample tilt angle over a range of more than absolute value of 80 deg otherwise the CT images lose their correct structures. In order to constrain the origin and formation process of GEMS grains more clearly, we performed complete electron tomography for GEMS grains. Here we report the sample preparation method we have developed for this study, and the preliminary results.

  11. Investigating materials formation with liquid-phase and cryogenic TEM

    NASA Astrophysics Data System (ADS)

    de Yoreo, J. J.; N. A. J. M., Sommerdijk

    2016-08-01

    The recent advent of liquid-phase transmission electron microscopy (TEM) and advances in cryogenic TEM are transforming our understanding of the physical and chemical mechanisms underlying the formation of materials in synthetic, biological and geochemical systems. These techniques have been applied to study the dynamic processes of nucleation, self-assembly, crystal growth and coarsening for metallic and semiconductor nanoparticles, (bio)minerals, electrochemical systems, macromolecular complexes, and organic and inorganic self-assembling systems. New instrumentation and methodologies that are currently on the horizon promise new opportunities for advancing the science of materials synthesis.

  12. Clay pigment structure characterisation as a guide for provenance determination--a comparison between laboratory powder micro-XRD and synchrotron radiation XRD.

    PubMed

    Švarcová, Silvie; Bezdička, Petr; Hradil, David; Hradilová, Janka; Žižak, Ivo

    2011-01-01

    Application of X-ray diffraction (XRD)-based techniques in the analysis of painted artworks is not only beneficial for indisputable identification of crystal constituents in colour layers, but it can also bring insight in material crystal structure, which can be affected by their geological formation, manufacturing procedure or secondary changes. This knowledge might be helpful for art historic evaluation of an artwork as well as for its conservation. By way of example of kaolinite, we show that classification of its crystal structure order based on XRD data is useful for estimation of its provenance. We found kaolinite in the preparation layer of a Gothic wall painting in a Czech church situated near Karlovy Vary, where there are important kaolin deposits. Comparing reference kaolin materials from eight various Czech deposits, we found that these can be differentiated just according to the kaolinite crystallinity. Within this study, we compared laboratory powder X-ray micro-diffraction (micro-XRD) with synchrotron radiation X-ray diffraction analysing the same real sample. We found that both techniques led to the same results.

  13. In situ TEM electromechanical testing of nanowires and nanotubes.

    PubMed

    Espinosa, Horacio D; Bernal, Rodrigo A; Filleter, Tobin

    2012-11-05

    The emergence of one-dimensional nanostructures as fundamental constituents of advanced materials and next-generation electronic and electromechanical devices has increased the need for their atomic-scale characterization. Given its spatial and temporal resolution, coupled with analytical capabilities, transmission electron microscopy (TEM) has been the technique of choice in performing atomic structure and defect characterization. A number of approaches have been recently developed to combine these capabilities with in-situ mechanical deformation and electrical characterization in the emerging field of in-situ TEM electromechanical testing. This has enabled researchers to establish unambiguous synthesis-structure-property relations for one-dimensional nanostructures. In this article, the development and latest advances of several in-situ TEM techniques to carry out mechanical and electromechanical testing of nanowires and nanotubes are reviewed. Through discussion of specific examples, it is shown how the merging of several microsystems and TEM has led to significant insights into the behavior of nanowires and nanotubes, underscoring the significant role in-situ techniques play in the development of novel nanoscale systems and materials.

  14. RECENT DEVELOPMENT IN TEM CHARACTERIZATION OF IRRADIATED RERTR FUELS

    SciTech Connect

    J. Gan; B.D. Miller; D.D. Keiser Jr.; A.B. Robinson; J.W. Madden; P.G. Medvedev; D.M. Wachs

    2011-10-01

    The recent development on TEM work of irradiated RERTR fuels includes microstructural characterization of the irradiated U-10Mo/alloy-6061 monolithic fuel plate, the RERTR-7 U-7Mo/Al-2Si and U-7Mo/Al-5Si dispersion fuel plates. It is the first time that a TEM sample of an irradiated nuclear fuel was prepared using the focused-ion-beam (FIB) lift-out technical at the Idaho National Laboratory. Multiple FIB TEM samples were prepared from the areas of interest in a SEM sample. The characterization was carried out using a 200kV TEM with a LaB6 filament. The three dimensional orderings of nanometer-sized fission gas bubbles are observed in the crystalline region of the U-Mo fuel. The co-existence of bubble superlattice and dislocations is evident. Detailed microstructural information along with composition analysis is obtained. The results and their implication on the performance of these fuels are discussed.

  15. Dopant profiling in the TEM, progress towards quantitative electron holography

    SciTech Connect

    Cooper, David; Truche, Robert; Chabli, Amal; Twitchett-Harrison, Alison C.; Midgley, Paul A.; Dunin-Borkowski, Rafal E.

    2007-09-26

    Off-axis electron holography has been used to characterise the dopant potential in GaAs p-n junctions. We show that the measured potential across the junctions is affected by both FIB specimen preparation and by charging in the TEM and suggest methods that can be used to minimise these problems.

  16. The mineralogy and chemistry analyser (MARS-XRD) for the ExoMars 2018 mission

    NASA Astrophysics Data System (ADS)

    Marinangeli, L.; Hutchinson, I. B.; Stevoli, A.; Adami, G.; Ambrosi, R.; Amils, R.; Assis Fernandes, V.; Baliva, A.; Basilevsky, A. T.; Benedix, G.; Bland, P.; Böttger, A. J.; Bridges, J.; Caprarelli, G.; Cressey, G.; Critani, F.; D'Alessandro, N.; Delhez, R.; Domeneghetti, C.; Fernandez-Remolar, D.; Filippone, R.; Fioretti, A. M.; Garcia Ruiz, J. M.; Gilmore, M.; Hansford, G. M.; Iezzi, G.; Ingley, R.; Ivanov, M.; Marseguerra, G.; Moroz, L.; Pelliciari, C.; Petrinca, P.; Piluso, E.; Pompilio, L.; Sykes, J.; Westall, F.

    2011-10-01

    The Mineralogy and Chemistry Analyser (MARSXRD) is a miniaturised X-ray diffraction and fluorescence (XRD/XRF) spectrometer aimed to the mineralogical characterisation of Martian rocks. Simultaneously, MARS-XRD is able to acquire the diffraction pattern for mineralogical phases identification and the X-ray fluorescence spectrum for the chemical species, providing a complete rock characterization. The X-ray diffractometer (XRD) is the routine instrument used in every Earth Science laboratory to provide the mineralogical composition of rocks. XRD produces unequivocal results because it is based on the recognition of the geometrical properties of the crystal lattice. This kind of investigation is an extremely useful tool to define the textural and petro-mineralogical characteristics of the Martian rocks or soils and provide information on the past Martian environment conditions related to life. The analytic range we plan to cover includes all the silicate minerals, from clays or other phyllosilicates characterised by high interplanar lattice distance, to oxide and carbonates or evaporates (mainly sulphates). This rock spectrum is what we expect to be the target for exobiological exploration. These data will be integrated with those obtained by elemental analysis, in order to determine the exact elemental chemistry characterization of rock components. As mineralogy can be unambiguously derived from XRD analysis, it is probably our most powerful tool for distinguishing targets of biologic importance. In summary, the main scientific objectives of the proposed XRD/XRF instrument, Mars-XRD, are: - In situ determination of the mineral paragenesis of rock samples; - The characterization of the origin of rock samples; - Determination of alteration processes; - Understanding the exobiological potential of the samples. The hardware is developed by the Thales Alenia Space Italia with an important contribution of the Univ. of Leicester for the detection system.

  17. Growth of copper sulfide dendrites and nanowires from elemental sulfur on TEM Cu grids under ambient conditions.

    PubMed

    Han, Qiaofeng; Sun, Shanshan; Li, Jiansheng; Wang, Xin

    2011-04-15

    Copper sulfide dendrites and subsequent uniform nanowires up to tens of micrometers long can be grown on carbon-coated transmission electron microscopy (TEM) Cu grids from elemental sulfur at room temperature under ambient conditions without any solvent and surfactants. TEM and high-resolution TEM studies demonstrated the morphology evolution of Cu₂S from dendrites into ultra-long nanowires with increasing ageing time. The sulfur species influenced significantly the growth rate of Cu₂S dendrites and nanowires, but the final morphology remained the same. The native oxide on the surface of Cu grids played a critical role in the formation of Cu₂S dendrites and nanowires. The crystal structures and phase purity of Cu₂S samples were confirmed by x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDX). A solid-liquid-solid growth model may be considered a potential mechanism in Cu₂S morphology evolution on the basis of the experimental results. Most importantly, the present study provides a simple and environmentally friendly route for the growth of one-dimensional (1D) Cu₂S on Cu substrate.

  18. In situ TEM studies of carbon and gold nanostructures

    NASA Astrophysics Data System (ADS)

    Casillas Garcia, Gilberto

    Properties of matter change as structures go down in size to the nanoscale, creating new possibilities for creating new functional materials with better properties than the bulk. In situ TEM techniques were used to probe the properties of two different materials: atomic carbon chains and gold nanoparticles. Carbon chains were synthesized by in situ TEM electron beam irradiation from few-layers-graphene (FLG) flakes. Several chains up to 5 nm long were observed. Aberration corrected TEM confirmed the dimerization of the linear chain as predicted by Peierls. Moreover, it was observed that two linear carbon chains can cross-bond every 9 atoms, and it was confirmed by DFT calculations. Five-fold nanoparticles are not supposed to be stable beyond 5 nm size. Here, decahedra with high index facets in the order of 300 nm were studied by TEM. It was found that the high index facets were only stable by adding a capping agent, otherwise, smooth edges were observed. In this case, a (5x1) hexagonal surface reconstruction was observed on the {001} surfaces, with the hexagonal strings along a [110] and a [410] direction. Additionally, mechanical properties of gold nanoparticles, with and without twin boundaries, under 100 nm were measured by in situ TEM compression experiments. All of the nanoparticles presented yield strengths in the order of GPa. Multi twinned nanoparticles were found to be more malleable, reaching real compressing strains of 100 %, while the single crystal nanoparticle presented less plastic flow. Molecular dynamics simulations revealed that the twin boundaries contribute to the malleability of the nanoparticles, at the same time it provides a mechanism to stop dislocations, hence, strain hardening the nanoparticle at later stages of compression. Finally, the behavior of a single grain boundary was studied by in situ TEM manipulation of nanoparticles. A liquid-like behavior of a grain boundary is observed after two 40 nm gold nanoparticles are brought to

  19. Visualizing DNA Nanoparticle Motion under Graphene Liquid Cell TEM

    NASA Astrophysics Data System (ADS)

    Chen, Qian; Smith, Jessica; Park, Jungwon; Lee, Somin; Zettl, Alex; Alivisatos, Paul

    2013-03-01

    We think of a simple colloidal nanocrystal as one type of artificial atoms. They mutually interact, cluster into artificial molecules, and further arrange into macroscopically functional artificial solids. The ``atomic'' resolution dynamics of this bottom-up strategy in materials design is studied here in a system of artificial molecules composed of DNA and nanoparticle. The observation of dynamics in their liquid environment is recently enabled by graphene liquid cell transmission electron microscopy (TEM). In comparison to conventional TEM, wherein the assembled 3D artificial structures are dried out during sample preparation and thus are collapsed, this graphene liquid cell introduces a special local liquid structure that retains the conformations as well as the dynamics of the assemblies. In situ imaging of correlated motions of DNA and nanoparticle provides insights into the design principles of artificial nanocrystal molecules and solids linked by DNA.

  20. Effects of diagnostic ionizing radiation on pregnancy via TEM

    NASA Astrophysics Data System (ADS)

    Mohammed, W. H.; Artoli, A. M.

    2008-08-01

    In Sudan, X-rays are routinely used at least once for measurements of pelvis during the gestation period, though this is highly prohibited worldwide, except for a few life threatening cases. To demonstrate the effect of diagnostic ionizing radiation on uterus, fetus and neighboring tissues to the ovaries, two independent experiments on pregnant rabbits were conducted. The first experiment was a proof of concept that diagnostic ionizing radiation is hazardous throughout the gestation period. The second experiment was done through Transmission Electron Microscopy (TEM) to elucidate the morphological changes in the ultra structure of samples taken from irradiated pregnant rabbits. This study uses TEM to test the effect of diagnostic radiation of less than 0.6 Gray on the cellular level. Morphological changes have been captured and the images were analyzed to quantify these effects.

  1. SimulaTEM: multislice simulations for general objects.

    PubMed

    Gómez-Rodríguez, A; Beltrán-Del-Río, L M; Herrera-Becerra, R

    2010-01-01

    In this work we present the program SimulaTEM for the simulation of high resolution micrographs and diffraction patterns. This is a program based on the multislice approach that does not assume a periodic object. It can calculate images from finite objects, from amorphous samples, from crystals, quasicrystals, grain boundaries, nanoparticles or arbitrary objects provided the coordinates of all the atoms can be supplied.

  2. Strain mapping in TEM using precession electron diffraction

    DOEpatents

    Taheri, Mitra Lenore; Leff, Asher Calvin

    2017-02-14

    A sample material is scanned with a transmission electron microscope (TEM) over multiple steps having a predetermined size at a predetermined angle. Each scan at a predetermined step and angle is compared to a template, wherein the template is generated from parameters of the material and the scanning. The data is then analyzed using local mis-orientation mapping and/or Nye's tensor analysis to provide information about local strain states.

  3. Assessment of TEM Cells for Whole Aircraft EMV Testing

    DTIC Science & Technology

    2007-05-01

    known to be due to cavity resonances within the cell. A novel method of active mode cancellation has been developed through CEM modelling together with...TEM Cell, OATS and Free Space Comparison . . . . . . . . . . . . . . . . . . 19 2.3.1 FEKO Models...accredited EMC test houses. The EMC/EMI characteristics of a box forms the basis of analysis at the system level once installed in the aircraft. The intra

  4. XRD measurement and EXAFS study using synchrotron radiation of Ni (II) complexes of macro cyclic ligand

    NASA Astrophysics Data System (ADS)

    Mishra, Ashutosh; Ninama, Samrath

    2013-06-01

    Nickel (II) tetra-aza macro cyclic complexes compound were synthesis by chemical rout method. X-ray diffraction (XRD) and Extended X-ray absorption fine structure (EXAFS) measurement were carried out. XRD analysis shows that sample is crystalline in nature and having particle size in the range of few micrometers. The EXAFS technique used to determine the bond lengths by three different methods, namely, Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The phase uncorrected bond lengths have also been obtained from Fourier transformation (F.T.) method and the results obtained have been compared with the results obtained from LSS method, which also gives phase uncorrected bond lengths.

  5. Data acquisition and control software for XRD beamline at Indus-2

    SciTech Connect

    Kane, Sanjeev R.; Garg, C. K.; Sinha, A. K.

    2010-06-23

    X-ray diffraction (XRD) beamline is under commissioning on Indus-2 synchrotron radiation facility. The experimental setup of XRD beamline consists of a six-circle diffractometer and various detector systems such as scintillation detector, ionization chamber and image plate. The diffractometer can be controlled via EIA232 serial interface or Ethernet. Standard data acquisition software with a graphical user interface has been developed using LabVIEW. A firm safety and error handling scheme is implemented for failsafe operation of the experimental station. This paper describes in detail the data acquisition and control software for the experimental station.

  6. Hydride phase formation in carbon supported palladium hydride nanoparticles by in situ EXAFS and XRD

    NASA Astrophysics Data System (ADS)

    Bugaev, A. L.; Guda, A. A.; Lomachenko, K. A.; Lazzarini, A.; Srabionyan, V. V.; Vitillo, J. G.; Piovano, A.; Groppo, E.; Bugaev, L. A.; Soldatov, A. V.; Dmitriev, V. P.; Pellegrini, R.; van Bokhoven, J. A.; Lamberti, C.

    2016-05-01

    In the current work we present a detailed analysis of the hydride phase formation in industrial Pd/C nanocatalysts by means of combined in situ X-ray absorption spectroscopy (EXAFS), X-ray diffraction (XRD) and volumetric measurements for the temperatures from - 10 to 50 °C in the hydrogen pressure range from 0 to 1000 mbar. α- and β- hydride phases are clearly distinguished in XRD. For the first time, H/Pd atomic ratio were obtained by theoretical fitting of the near-edge region of the absorption spectra (XANES) and compared with volumetric measurements.

  7. Characterization of some biological specimens using TEM and SEM

    NASA Astrophysics Data System (ADS)

    Ghosh, Nabarun; Smith, Don W.

    2009-05-01

    The advent of novel techniques using the Transmission and Scanning Electron Microscopes improved observation on various biological specimens to characterize them. We studied some biological specimens using Transmission and Scanning Electron Microscopes. We followed negative staining technique with Phosphotungstic acid using bacterial culture of Bacillus subtilis. Negative staining is very convenient technique to view the structural morphology of different samples including bacteria, phage viruses and filaments in a cell. We could observe the bacterial cell wall and flagellum very well when trapped the negative stained biofilm from bacterial culture on a TEM grid. We cut ultra thin sections from the fixed root tips of Pisum sativum (Garden pea). Root tips were pre fixed with osmium tetroxide and post fixed with uranium acetate and placed in the BEEM capsule for block making. The ultrathin sections on the grid under TEM showed the granular chromatin in the nucleus. The protein bodies and large vacuoles with the storage materials were conspicuous. We followed fixation, critical point drying and sputter coating with gold to view the tissues with SEM after placing on stubs. SEM view of the leaf surface of a dangerous weed Tragia hispida showed the surface trichomes. These trichomes when break on touching releases poisonous content causing skin irritation. The cultured tissue from in vitro culture of Albizia lebbeck, a tree revealed the regenerative structures including leaf buds and stomata on the tissue surface. SEM and TEM allow investigating the minute details characteristic morphological features that can be used for classroom teaching.

  8. Design and Characterization of a Lens TEM Horn

    NASA Astrophysics Data System (ADS)

    Bigelow, W. S.; Farr, E. G.; Bowen, L. H.; Ellibee, D. E.; Lawry, D. I.

    We investigate an approach for obtaining smaller UWB antennas with lower sidelobes than those offered by current designs. In support of this, we built and tested a lens TEM horn employing a collimating polyethylene aperture lens. It was thought that the lens TEM horn, with a more uniformly illuminated aperture field, might lead to higher gain with lower sidelobes than a comparably sized reflector IRA. That hypothesis is tested here. The lens horn, with a 30-cm aperture, has a maximum realized gain on boresight of 23 dB at 10 GHz. The normalized antenna impulse response is a clean peak with a full-width-at-half-maximum (FWHM) of 35 ps. For comparison, a highly optimized reflector IRA with 46-cm diameter achieves a maximum realized gain of 28 dB at 19 GHz and an impulse response with a FWHM of 30 ps. From theory, we expected the lens horn to exhibit lower sidelobes than the IRA. However, we did not observe that behavior in our experimental model. We suggest refinements which might lead to reduced sidelobes and increased gain in lens TEM horns.

  9. Observations from TEM Analysis of Swift Creek Samples

    NASA Astrophysics Data System (ADS)

    Harris, J. R.

    2012-12-01

    Samples analyzed by transmission electron microscopy (TEM) from suspended sediments in Swift Creek have unique characteristics compared to other naturally occurring asbestos (NOA) sites across the country. Our first introduction to the uniqueness of the Swift Creek site came about when we analyzed soil sediments by polarized light microscopy (PLM) and found relatively low or nonexistent levels of chrysotile asbestos. Upon submission of these samples for TEM analysis, we found that the samples were literally filled with small chrysotile fibers and bundles. We also notice a high number of dark, rounded particles which were not asbestiform. Out of curiosity, we viewed the surface features of one of these particles using scanning electron microscopy to find compacted chrysotile fibers bundled inside these particles. These particles contained the vast majority of chrysotile in the sample. This finding began our approach to provide more advanced TEM/SEM methods for identifying and characterizing complex arrangements of asbestos from NOA sites. We will present some of our experiences and methods for characterizing these types of particles common to NOA sites.

  10. Raman and XRD Field Characterisation of Sulfate Efflorescences at Rio Tinto (Spain)

    NASA Astrophysics Data System (ADS)

    Rull, F.; Sansano, A.; Sobron, P.; Lafuente, B.; Sarrazin, P.; Gailhanou, M.; Blake, D.

    2009-03-01

    In this work a comparative in-situ analysis of evaporate minerals from Rio Tinto (Spain) is undertaken using two techniques selected for Mars exploration: Raman spectrometer and CheMin XRD both selected as part of the ExoMars and MSL missions respectively.

  11. Chemical Species, Micromorphology, and XRD Fingerprint Analysis of Tibetan Medicine Zuotai Containing Mercury

    PubMed Central

    Li, Cen; Yang, Hongxia; Xiao, Yuancan; Zhandui; Sanglao; Wang, Zhang; Ladan, Duojie; Bi, Hongtao

    2016-01-01

    Zuotai (gTso thal) is one of the famous drugs containing mercury in Tibetan medicine. However, little is known about the chemical substance basis of its pharmacodynamics and the intrinsic link of different samples sources so far. Given this, energy dispersive spectrometry of X-ray (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), and powder X-ray diffraction (XRD) were used to assay the elements, micromorphology, and phase composition of nine Zuotai samples from different regions, respectively; the XRD fingerprint features of Zuotai were analyzed by multivariate statistical analysis. EDX result shows that Zuotai contains Hg, S, O, Fe, Al, Cu, and other elements. SEM and AFM observations suggest that Zuotai is a kind of ancient nanodrug. Its particles are mainly in the range of 100–800 nm, which commonly further aggregate into 1–30 μm loosely amorphous particles. XRD test shows that β-HgS, S8, and α-HgS are its main phase compositions. XRD fingerprint analysis indicates that the similarity degrees of nine samples are very high, and the results of multivariate statistical analysis are broadly consistent with sample sources. The present research has revealed the physicochemical characteristics of Zuotai, and it would play a positive role in interpreting this mysterious Tibetan drug. PMID:27738409

  12. TEM Pump With External Heat Source And Sink

    NASA Technical Reports Server (NTRS)

    Nesmith, Bill J.

    1991-01-01

    Proposed thermoelectric/electromagnetic (TEM) pump driven by external source of heat and by two or more heat pipe radiator heat sink(s). Thermoelectrics generate electrical current to circulate liquid metal in secondary loop of two-fluid-loop system. Intended for use with space and terrestrial dual loop liquid metal nuclear reactors. Applications include spacecraft on long missions or terrestrial beacons or scientific instruments having to operate in remote areas for long times. Design modified to include multiple radiators, converters, and ducts, as dictated by particular application.

  13. TEM studies of calcium phosphates for the understanding of biomineralization

    NASA Astrophysics Data System (ADS)

    Xin, Renlong

    Calcium phosphate (Ca-P) formation and bone minerals have been the focus of research for several decades because achievements in these areas could provide valuable insights into the understanding of biomineralization. In this thesis work, Ca-P formation, octacalcium phosphate (OCP) to hydroxyapatite (HA) transformation and bone minerals were systematically studied by transmission electron microscopy (TEM) techniques. Ca-P formations on various bioceramics in simulated body fluid and in rabbit muscle sites were investigated. The bioceramics included sintered bioglass RTM, A-W glass-ceramics, HA, alpha-tricalcium phosphate (TCP), beta-TCP and HA-TCP. The comparative studies showed that OCP formation occurred on all types of bioceramic surfaces in vitro and in vivo, except on beta-TCP; however HA formation did not occur on every type of bioceramics; it less likely occurred on the surfaces of HA and alpha-TCP. These findings were contradicted to the common statements in literatures. OCP to HA transformations in vitro and in vivo were observed by high-resolution TEM (HRTEM). The in vitro transformation was induced by electron beam irradiations of in situ TEM on synthetic OCP crystals. The in vivo transformation was revealed on rod-like HA precipitates formed in dog muscle sites. Based on HRTEM examinations and image simulations, OCP/HA crystallographic orientations were determined to be OCP (010) // HA (01¯0) and OCP (001) // HA (001¯), which differed from a well known model proposed by Brown et al. The minerals of cortical bone were extracted from human tibiae and rat femurs using 10% neutral ethylenediamine tetraacetic acid (EDTA) solution. TEM examinations showed that the dominance of bone minerals was plate-like and a few were needle-like. The length of most plate-like minerals ranged from 50 to 150 nm but could be up to 200 nm. To the author's knowledge, OCP structure was for the first time, identified in a number of plate-like bone minerals by selected area

  14. Automated S/TEM metrology on advanced semiconductor gate structures

    NASA Astrophysics Data System (ADS)

    Strauss, M.; Arjavac, J.; Horspool, D. N.; Nakahara, K.; Deeb, C.; Hobbs, C.

    2012-03-01

    Alternate techniques for obatining metrology data from advanced semiconductor device structures may be required. Automated STEM-based dimensional metrology (CD-STEM) was developed for complex 3D geometries in read/write head metrology in teh hard disk drive industry. It has been widely adopted, and is the process of record for metrology. Fully automated S/TEM metrology on advanced semiconductor gate structures is viable, with good repeatability and robustness. Consistent automated throughput of 10 samples per hour was achieved. Automated sample preparation was developed with sufficient throughput and quality to support the automated CD-STEM.

  15. A Fast 4-D TEM System for UXO Characterization

    DTIC Science & Technology

    2004-11-01

    eliminates the need to transport all gear back and forth between the field site and the hotel . At Aberdeen, the only piece of gear we transported back to...the hotel after work was the NT-32II transceiver. We had a problem with getting our GPS system operational and lost a few hours while we troubleshot...Orleans Mariott : U.S. Dept. of Defense. 9. Carlson, N.E., and Kenneth L. Zonge. The utility of horizontal component measurements in random-walk TEM

  16. Modeling of planar quasi-TEM superconducting transmission lines

    NASA Technical Reports Server (NTRS)

    Antsos, Dimitrios; Chew, Wilbert; Riley, A. L.; Hunt, Brian D.; Foote, Marc C.; Bajuk, Louis J.; Rascoe, Daniel L.; Cooley, Thomas W.

    1992-01-01

    An application of the phenomenological loss equivalence method (Lee and Itoh, 1989) in modeling the microwave behavior of planar quasi-TEM superconducting transmission lines is presented. For validation of the model, data are used from measurements of a YBCO superconducting thin-film coplanar-waveguide lowpass filter on a lanthanum aluminate substrate. Measured and modeled S-parameters of an existing superconducting coplanar waveguide lowpass filter agree to within 0.3 dB in magnitude and 0.5 radians in phase. Extracted values for penetration depth and real part of the conductivity of the superconducting film are within 10 percent of other researchers' findings.

  17. Studying dynamic processes in liquids by TEM/STEM/DTEM

    NASA Astrophysics Data System (ADS)

    Abellan, Patricia; Evans, James; Woehl, Taylor; Jungjohann, Katherine; Parent, Lucas; Arslan, Ilke; Ristenpart, William; Browning, Nigel; Mater. Sci. Group Team; Microsc. Group Team; Catal. Sci. Group Collaboration; Ristenpart Res. Group Collaboration

    2013-03-01

    In order to study dynamic phenomena such as corrosion or catalysis, extreme environmental conditions must be reproduced around the specimen - these include high-temperatures, high-pressures, specific oxidizing/reducing atmospheres or a liquid environment. The use of environmental stages specifically designed to fit in any transmission electron microscope (TEM) allows us to apply the distinct capabilities of each instrument to study dynamic processes. Localized gas/fluid conditions are created around the sample and separated from the high vacuum inside the microscope using hermetically sealed windowed-cells. Advanced capabilities of these techniques include spatial resolutions of ~1 Angstrom or better in aberration corrected instruments or temporal resolutions in the microsecond-nanosecond range in a dynamic TEM (DTEM). Here, unique qualities of the DTEM that benefit the in-situ experiments with gas/fluid environmental cells will be discussed. We also present our results with a liquid stage allowing atomic resolution imaging of nanomaterials in a colloidal suspension, core EEL spectra acquisition, continuous flow, controlled growth of nanocrystals and systematic calibration of the effect of the electron dose on silver nuclei formation.

  18. TEM investigations on the local microstructure of electrodeposited galfenol nanowires

    NASA Astrophysics Data System (ADS)

    Pohl, D.; Damm, C.; Pohl, D.; Schultz, L.; Schlörb, H.

    2016-01-01

    The local microstructure of Fe-Ga nanowires is investigated considering dependence on the deposition technique. Using a complexed electrolyte, smooth and homogeneous Fe80Ga20 nanowires are deposited into anodic aluminum oxide templates by either applying pulse potential or potentiostatic deposition technique. At optimized deposition conditions the wires show the desired composition of Fe80±2Ga20±2 without a gradient along the growth direction. Composition distribution, structure and microstructure are examined in detail and reveal only minor differences. Line EELS and crystal lattice measurements reveal a negligible oxygen content for both preparation routines. Neither Fe/Ga oxides nor hydroxides were found. Both potentiostatically deposited as well as pulse deposited nanowires exhibit a preferred <110> orientation, the latter with slightly larger crystals. Different contrast patterns were found by TEM that appear more pronounced in the case of pulse deposited wires. High resolution transmission electron microscopy analysis and comparison of differently prepared focused ion beam lamellas reveal that these contrasts are caused by defects in the alternating potential deposition itself and are not induced during the TEM preparation process. The alternating potential mode causes periodic growth thereby inducing different layers with reduced wire thickness/defects at the layer interfaces.

  19. A modified relativistic magnetron with TEM output mode

    NASA Astrophysics Data System (ADS)

    Shi, Di-Fu; Qian, Bao-Liang; Wang, Hong-Gang; Li, Wei; Ju, Jin-Chuan; Du, Guang-Xing

    2017-01-01

    A modified relativistic magnetron (RM) with TEM output mode is proposed. By setting the coupling slots at the bottom of the resonant cavities in the transmission region rather than in the interaction region, besides possessing the original RM's advantages of high power conversion efficiency and radiating the lowest order mode, the modified RM not only improves the compactness and miniaturization of the magnetic field system, which is beneficial to realize the RMs packed by a permanent magnet, but also improves the robustness of operating frequency to structural perturbations of the coupling slots, which contributes to optimize the RM performance by adjusting the coupling slot dimensions with a relatively stable operating frequency. In the three-dimensional particle-in-cell (PIC) simulation, the modified RM with a reduction of 27.2% in the weight of the coils, 35.8% in the occupied space of the coils, and 18.6% in the operating current, can output a relatively pure TEM mode, which has been demonstrated as the dominant output mode by simulation, corresponding to an output power of 495.0 MW and a power conversion efficiency of 56.4%, at the resonant frequency of 4.30 GHz. In addition, an output power of above 2 GW can also be obtained from the RM in simulations.

  20. TEM transmission line coil with double nuclear capability.

    PubMed

    Erickson, Matthew G; Kurpad, Krishna N; Holmes, James H; Fain, Sean B

    2007-10-01

    MR imaging and spectroscopy requires RF fields of high homogeneity. Quadrature volume coils meeting this requirement include the birdcage coil and the TEM resonator. We describe here a quadrature volume coil designed around a modified coaxial transmission line in which multiple inner conductors are arrayed on a circular perimeter and surrounded by a common shield. Current antinodes are established at appropriate points on the inner conductors by series transmission line stubs, either open circuit or short circuit, which terminate the line. Quadrature phasing is generated by a novel circuit constructed from a pair of high-performance current baluns and a commercial quadrature hybrid. The coil is a "pure" TEM coil as it is simply a resonant transmission line. There is no mode structure to consider. The construction of a prototype quadrature four-element coil is described and preliminary test results from this coil in a 4.7T horizontal bore magnet are reported. A related double nuclear coil design for (3)He and (1)H in which two linear transmission line coils are arrayed on a circular perimeter and simultaneously tuned and matched to their respective frequencies is also described. Preliminary tests from this coil in a 1.5T clinical scanner are reported.

  1. Characterization of diamond-like carbon films by SEM, XRD and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Pang, Hua; Wang, Xingquan; Zhang, Guling; Chen, Huan; Lv, Guohua; Yang, Size

    2010-08-01

    Diamond-like carbon films were deposited by electrolysis of a water-ethanol solution on Cu at low voltages (60-100 V) at 2 mm interelectrode separation. The films were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and Raman spectroscopy. The films were found to be continuous and compact with uniform grain distribution. Raman spectroscopy analysis revealed two broad bands at ˜1350 and ˜1580 cm -1. The downshift of the G band of graphite is indicative of the presence of DLC. For XRD analysis, the three strong peaks located at 2 θ values of 43.2°, 74.06° and 89.9° can be identified with reflections form (1 1 1), (2 2 0) and (3 1 1) plane of diamond.

  2. Applying high resolution SyXRD analysis on sulfate attacked concrete field samples

    SciTech Connect

    Stroh, J.; Schlegel, M.-C.; Irassar, E.F.; Meng, B.; Emmerling, F.

    2014-12-15

    High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments.

  3. Mössbauer and XRD study of Al-Sn linished steel bimetal alloy

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Silva, L. da; Stichleutner, S.; El-Sharif, M.; Homonnay, Z.; Klencsár, Z.; Sziráki, L.; Chisholm, C. U.; Lak, B.

    2016-12-01

    Aluminium alloy free CS1 type steel (0.06 wt% C, 0.45 wt% Mn) and samples of cold roll bonded steel bimetal alloys (MAS15 and MAS16) were fabricated and investigated by X-ray diffraction (XRD), 57Fe conversion electron Mössbauer spectroscopy (CEMS) at room temperature. XRD has revealed only the existence of the alpha iron solid solution (steel) phase in the steel only sample, while identified steel and metallic Al and Sn constituent phases in the bimetallic alloys. 57Fe Mössbauer spectroscopy revealed the presence of 4 % secondary iron-bearing phase attributed mainly to iron oxide/ oxyhydroxides (ferrihydrite) besides the steel matrix on the surface of the steel sample. A significant difference between the occurrences of the secondary phase of differently prepared bimetal alloys found in their 57Fe CEM spectra allowed to identify the main phase of debris as different iron oxide/ oxyhydroxides.

  4. A Raman, IR and XRD analysis of the deterioration on historical monuments: Case study from Mexico

    NASA Astrophysics Data System (ADS)

    Ostrooumov, Mikhail

    2009-08-01

    Raman, infrared and XRD analysis have been applied to the examination of deterioration on historical monuments (Morelia, Mexico). Forty-three samples pyroclastic volcanic rocks (ignimbrites) have been studied, all originating from two ex-convents San Francisco and San Agustin, which were the first architectonic complexes in the city of Morelia. Several new mineral neoformation such as sulfates, carbonates, halides, and phosphates were identified in these samples with spectrometric and XRD technique. The observed Raman and infrared spectra are reported and some mineral compound assignments in unaltered and deteriorated volcanic rocks have been made. This survey is the first Raman and infrared spectrometric examination of the environmental mineralogy in Mexico under conditions of urban weathering that are characterized mainly by one secondary alteration formations of low scale.

  5. Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD.

    PubMed

    Zhang, Jiafu; Wang, Yixun; Zhang, Liye; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

    2014-01-01

    X-ray diffraction (XRD) was used to understand the interactions of cellulose in lignocellulosic biomass with ionic liquids (ILs). The experiment was designed in such a way that the process of swelling and solubilization of crystalline cellulose in plant cell walls was followed by XRD. Three different feedstocks, switchgrass, corn stover and rice husk, were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. At a 5 wt.% biomass loading, increasing pretreatment temperature led to a drop in biomass crystallinity index (CrI), which was due to swelling of crystalline cellulose. After most of the crystalline cellulose was swollen with IL molecules, a low-order structure was found in the pretreated samples. Upon further increasing temperature, cellulose II structure started to form in the pretreated biomass samples as a result of solubilization of cellulose in [C4mim][OAc] and subsequent regeneration.

  6. Structural characterization of TiN/NbN multilayers: X-ray diffraction, energy-filtered TEM and Fresnel contrast techniques compared.

    PubMed

    Lloyd, S J; Molina-Aldareguia, J M; Clegg, W J

    2005-03-01

    Two TiN/NbN multilayers with wavelength 13.6 and 6.15 nm have been characterized by X-ray diffraction (XRD), Fresnel contrast analysis (FCA) and energy-filtered transmission electron microscopy (EFTEM). Good agreement between the composition profile obtained by FCA and EFTEM is obtained if the lower resolution of the EFTEM images is taken into account. The relative advantages and disadvantages of the techniques are discussed. Used together the two TEM techniques provide a quantitative characterization that is consistent with, and for some parameters provides more precise values than, that from XRD. The analysis shows that the multilayers have narrow interfaces (< 1 nm) and a composition amplitude close to 95% for the longer wavelength.

  7. Lattice Expansion of LSCF-6428 Cathodes Measured by In-situ XRD during SOFC Operation

    SciTech Connect

    Hardy, John S.; Templeton, Jared W.; Edwards, Danny J.; Lu, Zigui; Stevenson, Jeffry W.

    2012-01-03

    A new capability has been developed for analyzing solid oxide fuel cells (SOFCs). This paper describes the initial results of in-situ x-ray diffraction (XRD) of the cathode on an operating anode-supported solid oxide fuel cell. It has been demonstrated that XRD measurements of the cathode can be performed simultaneously with electrochemical measurements of cell performance or electrochemical impedance spectroscopy (EIS). While improvements to the technique are still to be made, the XRD pattern of a lanthanum strontium cobalt ferrite (LSCF) cathode with the composition La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428) was found to continually but gradually change over the course of more than 60 hours of operation in air under typical SOFC operating conditions. It was determined that the most significant change was a gradual increase in the cubic lattice parameters of the LSCF from 3.92502 Å (as determined from the integration of the first 20 hours of XRD patterns) to 3.92650 Å (from the integration of the last 20 hours). This analysis also revealed that there were several peaks from unidentified minor phases that increased in intensity over this timeframe. After a temporary loss of airflow early in the test, the cell generated between 225 and 250 mW/cm2 for the remainder of the test. A large low frequency arc in the impedance spectra suggests the cell performance was gas diffusion limited and that there is room for improvement in air delivery to the cell.

  8. Mineralogical composition of the meteorite El Pozo (Mexico): a Raman, infrared and XRD study.

    PubMed

    Ostrooumov, Mikhail; Hernández-Bernal, Maria del Sol

    2011-12-01

    The Raman (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of El Pozo meteorite (an ordinary chondrite L5 type; village Valle of Allende, founded in State of Chihuahua, Mexico: 26°56'N and 105°24'W, 1998). RMP measurements in the range of 100-3500 cm(-1) revealed principal characteristic bands of the major minerals: olivine, two polymorph modifications of pyroxene (OPx and CPx) and plagioclase. Some bands of the minor minerals (hematite and goethite) were also identified. All these minerals were clearly distinguished using IR and XRD techniques. XRD technique has shown the presence of some metallic phases such as kamacite and taenite as well as troilite and chromite. These minerals do not have characteristic Raman spectra because Fe-Ni metals have no active modes for Raman spectroscopy and troilite is a weak Raman scatterer. Raman mapping microspectroscopy was a key part in the investigation of El Pozo meteorite's spatial distribution of the main minerals because these samples are structurally and chemically complex and heterogeneous. The mineral mapping by Raman spectroscopy has provided information for a certain spatial region on which a spatial distribution coexists of the three typical mineral assemblages: olivine; olivine+orthopyroxene; and orthopyroxene.

  9. Study the oxidation kinetics of uranium using XRD and Rietveld method

    NASA Astrophysics Data System (ADS)

    Zhang, Yanzhi; Guan, Weijun; Wang, Qinguo; Wang, Xiaolin; Lai, Xinchun; Shuai, Maobing

    2010-03-01

    The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50~300°C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO2 was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO2 can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

  10. [Study on the vibrational spectra and XRD characters of Huanglong jade from Longling County, Yunnan Province].

    PubMed

    Pei, Jing-cheng; Fan, Lu-wei; Xie, Hao

    2014-12-01

    Based on the conventional test methods, the infrared absorption spectrum, Raman spectrum and X-ray diffraction (XRD) were employed to study the characters of the vibration spectrum and mineral composition of Huanglong jade. The testing results show that Huanglong jade shows typical vibrational spectrum characteristics of quartziferous jade. The main infrared absorption bands at 1162, 1076, 800, 779, 691, 530 and 466 cm(-1) were induced by the asymmetric stretching vibration, symmetrical stretching vibration and bending vibration of Si-O-Si separately. Especially the absorption band near 800 cm(-1) is split, which indicates that Huanglong jade has good crystallinity. In Raman spectrum, the main strong vibration bands at 463 and 355 cm(-1) were attributed to bending vibration of Si-O-Si. XRD test confirmed that Quartz is main mineral composition of Huanglong jade and there is a small amount of hematite in red color samples which induced the red color of Huanglong jade. This is the first report on the infrared, Raman and XRD spectra feature of Huanglong jade. It will provide a scientific basis for the identification, naming and other research for huanglong jade.

  11. Mineralogical composition of the meteorite El Pozo (Mexico): A Raman, infrared and XRD study

    NASA Astrophysics Data System (ADS)

    Ostrooumov, Mikhail; Hernández-Bernal, Maria del Sol

    2011-12-01

    The Raman (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of El Pozo meteorite (an ordinary chondrite L5 type; village Valle of Allende, founded in State of Chihuahua, Mexico: 26°56'N and 105°24'W, 1998). RMP measurements in the range of 100-3500 cm -1 revealed principal characteristic bands of the major minerals: olivine, two polymorph modifications of pyroxene (OPx and CPx) and plagioclase. Some bands of the minor minerals (hematite and goethite) were also identified. All these minerals were clearly distinguished using IR and XRD techniques. XRD technique has shown the presence of some metallic phases such as kamacite and taenite as well as troilite and chromite. These minerals do not have characteristic Raman spectra because Fe-Ni metals have no active modes for Raman spectroscopy and troilite is a weak Raman scatterer. Raman mapping microspectroscopy was a key part in the investigation of El Pozo meteorite's spatial distribution of the main minerals because these samples are structurally and chemically complex and heterogeneous. The mineral mapping by Raman spectroscopy has provided information for a certain spatial region on which a spatial distribution coexists of the three typical mineral assemblages: olivine; olivine + orthopyroxene; and orthopyroxene.

  12. (S)TEM analysis of functional transition metal oxides

    NASA Astrophysics Data System (ADS)

    Chi, Miaofang

    Perovskite vanadates (AVO3) form an ideal family to study the structure-property relationships in transition metal oxides because their physical properties can easily be tailored by varying the A-site cations. (S)TEM is an ideal tool for this type of study due to its capacity for simultaneous imaging and chemical analysis. Determination of the oxidation state of vanadium in complex oxides have been carried out by electron energy loss spectroscopy. SrVO3/LaAlO3 is then studied both experimentally and theoretically as a prototype system. Extra electrons have been detected on the interface layer, and further proven to originate mainly from a change in the local bonding configuration of V at the La-O terminated substrate surface. Cr-containing stainless steel deposited with a LaCrO3 thin-film layer is a promising interconnect material of Solid Oxide Fuel Cells (SOFC). Our investigation on its microstructural evolution reveals that the LaCrO 3 thin film plays a role in inhibiting the growth of an oxide layer on the metal surface and thus protects the surface of the stainless steel. Ca-doped LaCoO3 is a promising SOFC cathode material. The domain structures and the oxidation state of Co in Ca-doped LaCoO3, which are directly related to its mechanical properties and electronic conductivity, are investigated by in-situ TEM and EELS. The formation of microcracks is observed during thermal cycles. Ca-doping in LaCoO3 is shown to not only improve the electronic conductivity of the material, but is also likely to strengthen the grain boundaries. The realization of its application in SOFCs depends on depressing the ferroelastisity to reduce strain formation during thermal cycles. The application of the (S)TEM techniques used for studying the perovskite systems are further extended to other compounds containing transition metal elements. The refractory minerals from Comet 81 P/Wild-2 are studied to investigate the formation of the early solar system. A relatively high Ti3+/Ti 4

  13. A TEM analysis of nanoparticulates in a Polar ice core

    SciTech Connect

    Esquivel, E.V.; Murr, L.E

    2004-03-15

    This paper explores the prospect for analyzing nanoparticulates in age-dated ice cores representing times in antiquity to establish a historical reference for atmospheric particulate regimes. Analytical transmission electron microscope (TEM) techniques were utilized to observe representative ice-melt water drops dried down on carbon/formvar or similar coated grids. A 10,000-year-old Greenland ice core was melted, and representative water drops were transferred to coated grids in a clean room environment. Essentially, all particulates observed were aggregates and either crystalline or complex mixtures of nanocrystals. Especially notable was the observation of carbon nanotubes and related fullerene-like nanocrystal forms. These observations are similar with some aspects of contemporary airborne particulates including carbon nanotubes and complex nanocrystal aggregates.

  14. AFM, SEM and TEM Studies on Porous Anodic Alumina

    PubMed Central

    2010-01-01

    Porous anodic alumina (PAA) has been intensively studied in past decade due to its applications for fabricating nanostructured materials. Since PAA’s pore diameter, thickness and shape vary too much, a systematical study on the methods of morphology characterization is meaningful and essential for its proper development and utilization. In this paper, we present detailed AFM, SEM and TEM studies on PAA and its evolvements with abundant microstructures, and discuss the advantages and disadvantages of each method. The sample preparation, testing skills and morphology analysis are discussed, especially on the differentiation during characterizing complex cross-sections and ultrasmall nanopores. The versatility of PAAs is also demonstrated by the diversity of PAAs’ microstructure. PMID:20672104

  15. AFM, SEM and TEM Studies on Porous Anodic Alumina

    NASA Astrophysics Data System (ADS)

    Zhu, Yuan Yuan; Ding, Gu Qiao; Ding, Jian Ning; Yuan, Ning Yi

    2010-04-01

    Porous anodic alumina (PAA) has been intensively studied in past decade due to its applications for fabricating nanostructured materials. Since PAA’s pore diameter, thickness and shape vary too much, a systematical study on the methods of morphology characterization is meaningful and essential for its proper development and utilization. In this paper, we present detailed AFM, SEM and TEM studies on PAA and its evolvements with abundant microstructures, and discuss the advantages and disadvantages of each method. The sample preparation, testing skills and morphology analysis are discussed, especially on the differentiation during characterizing complex cross-sections and ultrasmall nanopores. The versatility of PAAs is also demonstrated by the diversity of PAAs’ microstructure.

  16. Correlation Analysis of TEM Images of Nanocrystal Molecules

    SciTech Connect

    Micheel, Christine; Zanchet, Daniele; Alivisatos, A. Paul

    2008-05-21

    Quantitative characterizataion of images of naocrystals and nanostructures is a challenging but important task. The development and optimization of methods for the construction of complex nanostructures rely on imaging techniques. Computer programs were developed to quantify TEM images of nanocrystal/DNA nanostructures, and results are presented for heterodimers annd trimers of gold nanocrystals. The programs presented here have also been used to analyze more complex trimers and tetramers linked by branched DNA, as well as for structures made from attaching gold nanocrystals to CdSe/ZnS core-shell quantum dots. This work has the additional goal of enabling others to quickly and easily adapt the methods for their own use.

  17. Examination of subaerially altered basaltic glass with TEM and EELS

    SciTech Connect

    Luo, J.-S.

    1998-06-17

    We have examined the weathered surfaces of 720 year old Hawaiian basalt glasses that were recovered from a subaerial environment with high-resolution transmission electron microscopy (TEM) and energy filtered imaging and electron energy loss spectroscopy (EELS) techniques. Whereas the alteration products (palagonite) were physically detached from the underlying glass in most samples, a gel-like amorphous layer was observed adjacent to the glass in a few samples. To our knowledge, this is the first time a gel layer has been observed on weathered basalt. This is significant because analogous gel layers have been observed on nuclear waste glasses reacted in laboratory tests, and this demonstrates an important similarity in the mechanisms of the weathering of basalt and the corrosion of waste glasses.

  18. Enabling direct nanoscale observations of biological reactions with dynamic TEM

    PubMed Central

    Evans, James E.; Browning, Nigel D.

    2013-01-01

    Biological processes occur on a wide range of spatial and temporal scales: from femtoseconds to hours and from angstroms to meters. Many new biological insights can be expected from a better understanding of the processes that occur on these very fast and very small scales. In this regard, new instruments that use fast X-ray or electron pulses are expected to reveal novel mechanistic details for macromolecular protein dynamics. To ensure that any observed conformational change is physiologically relevant and not constrained by 3D crystal packing, it would be preferable for experiments to utilize small protein samples such as single particles or 2D crystals that mimic the target protein's native environment. These samples are not typically amenable to X-ray analysis, but transmission electron microscopy has imaged such sample geometries for over 40 years using both direct imaging and diffraction modes. While conventional transmission electron microscopes (TEM) have visualized biological samples with atomic resolution in an arrested or frozen state, the recent development of the dynamic TEM (DTEM) extends electron microscopy into a dynamic regime using pump-probe imaging. A new second-generation DTEM, which is currently being constructed, has the potential to observe live biological processes with unprecedented spatiotemporal resolution by using pulsed electron packets to probe the sample on micro- and nanosecond timescales. This article reviews the experimental parameters necessary for coupling DTEM with in situ liquid microscopy to enable direct imaging of protein conformational dynamics in a fully hydrated environment and visualize reactions propagating in real time. PMID:23315566

  19. TEM-EDS study of metals' partition at particle level after their sorption in soil

    NASA Astrophysics Data System (ADS)

    Sipos, Peter; Kovács Kis, Viktória; Németh, Tibor; Balázs, Réka

    2016-04-01

    Association of soil mineral particles could significantly modify the sorption capacity of the individual soil components. We studied this phenomena using single element and competitive batch Cd, Cu, Pb and Zn sorption experiments on six soil samples with contrasting characteristics. Their sorption properties were characterized by XRD and FTIRS analyses, as well as sorption curve evaluation. TEM-EDS analyses were used to characterize the soil mineral particle associations and their metal sorption capacities. Submicron sized smectite particles were found to be associated to tiny ferryhidrite and goethite patches in the acidic forest soil samples, whereas the alkaline meadow soils could be characterized by goethite and smectite particles attached to large carbonate grains. Point chemical analyses carried out on such associations showed that significant metal separation may occur at particle level within the mineral associations observed. This is primarily obvious for Cu and Pb, which are preferentially sorbed by iron oxides over clay mineral particles. This phenomenon is more pronounced in competitive situation. Highest affinity to clay minerals was found for Zn and it may be also characteristic for Cd in acid conditions. However, decrease in available sorption sites and increase in pH may result in enhanced precipitation for the studied metals. Our results suggest that estimation of the role of soil components in metals' sorption can not be adequate enough when the sorption properties of a set of bulk soils are studied exclusively. Direct observation of metals' partition at particle level may result in a deeper insight into soil-metal interaction. This study was financially supported by the Hungarian Scientific Research Fund (OTKA K105009).

  20. A Raman, infrared and XRD analysis of the instability in volcanic opals from Mexico.

    PubMed

    Ostrooumov, Mikhail

    2007-12-15

    A series of natural volcanic opal samples with the destabilization phenomena from Mexican deposits (states of Queretaro and Jalisco) was investigated by Raman microprobe (RMP), infrared spectrometry and XRD analysis. These techniques show that at low and room temperatures the unaltered transparent opals may be transformed into destabilized white opals, which are a mixture of different polymorphs of tridymite and alpha-cristobalite with various degrees of crystallinity. We found systematic changes in frequencies of both the Raman and the infrared bands, caused by increasing regularities of bond-lengths and bond-angles Si-O-Si groups under the effect of stability. Micro-Raman spectrometry confirms that in the destabilized opal the principal mineral phases are MC (monoclinic ordered)- and MX (incommensurate monoclinic)-tridymites that are characterized by more structural order in comparison with other structural modification of this phase in unaltered opal (POn pseudo-orthorhombic disordered tridymite). XRD investigations show that in the sequence from unaltered to destabilized opal the position of principal maximum (4.30, 4.10 and 2.50 A) shifts towards higher d-spacing. This XRD shifting to higher d-spacing can largely be explained by an increasing amount of tridymite stacking and unresolved superposition of cristobalite and tridymite reflections. The destabilization phenomena in volcanic opals is due to the structural ordering/disordering that is characterized mainly by the formation of the different tridymite polymorphs (MC and MX) in the destabilized opal-CT as well as the decreasing content of molecular water in the structure.

  1. A Raman, infrared and XRD analysis of the instability in volcanic opals from Mexico

    NASA Astrophysics Data System (ADS)

    Ostrooumov, Mikhail

    2007-12-01

    A series of natural volcanic opal samples with the destabilization phenomena from Mexican deposits (states of Queretaro and Jalisco) was investigated by Raman microprobe (RMP), infrared spectrometry and XRD analysis. These techniques show that at low and room temperatures the unaltered transparent opals may be transformed into destabilized white opals, which are a mixture of different polymorphs of tridymite and α-cristobalite with various degrees of crystallinity. We found systematic changes in frequencies of both the Raman and the infrared bands, caused by increasing regularities of bond-lengths and bond-angles Si-O-Si groups under the effect of stability. Micro-Raman spectrometry confirms that in the destabilized opal the principal mineral phases are MC (monoclinic ordered)- and MX (incommensurate monoclinic)-tridymites that are characterized by more structural order in comparison with other structural modification of this phase in unaltered opal (POn pseudo-orthorhombic disordered tridymite). XRD investigations show that in the sequence from unaltered to destabilized opal the position of principal maximum (4.30, 4.10 and 2.50 Å) shifts towards higher d-spacing. This XRD shifting to higher d-spacing can largely be explained by an increasing amount of tridymite stacking and unresolved superposition of cristobalite and tridymite reflections. The destabilization phenomena in volcanic opals is due to the structural ordering/disordering that is characterized mainly by the formation of the different tridymite polymorphs (MC and MX) in the destabilized opal-CT as well as the decreasing content of molecular water in the structure.

  2. Quantitative XRD HW-IR plot for clay mineral domain size and lattice strain analyses

    NASA Astrophysics Data System (ADS)

    Wang, H. J.; Chen, D. Z.; Zhou, J.; Chen, T.; Wang, H.; Zhang, Z. Q.

    2003-04-01

    Based on integral-breadth method, the one of three basic XRD methods (Klug &Alexander, 1974), authors (2000) proposed a qualitative half width (HW)-intensity ratio (IR) plot for clay mineral domain size and lattice strain analyses. In this study, the quantitative HW-IR plot is further developed on the basis of i) the curve relation between the Voigt function and the Pearson VII function; ii) the relationship between the Kübler index and the Weaver index. By numerical simulating, it is derived a curve relation between shape indexes k of the Voigt function and u of the Pearson VII function. With this curve relation, k and u can be converted each other in an accuracy of ten thousandth and therefore the domain size and the lattice strain contributions can be precisely separated from an XRD peak according to Langford's (1978) formula. For micaceous minerals, the HW-IR plot requires only a pair of values of the Kübler index and the Weaver index from 1nm reflection. For other clay minerals, the plot needs a pair of values of the (00l) peak's half width and intensity ratio IR. IR is a ratio of peak maximum to the intensity at the position of maximum minus 0.422oΔ2Θ in CuKα radiation. This quantitative plot renders a mean dimension of clay particles perpendicular to the reflection plane (00l) and an approximate upper limit strain normal to d001. The accuracy for domain size analysis reaches one tenth of nanometre and that for the lattice strain analysis is in ten thousandth respectively. This plot method can be widely used with any digital X-ray diffractometer, whose XRD data can be converted into text format. Excel 5.0 or latter versions in both English and Chinese can well support the HW-IR plot. This study was supported by NNSFC (Grant No 40272022)

  3. [Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

    PubMed

    Zhang, Zhi-Dan; Luo, Xiang-Li; Jiang, Hai-Chao; Li, Qiao; Shen, Cong-Ying; Liu, Hang; Zhou, Ya-Juan; Zhao, Lan-Po; Wang, Ji-Hong

    2014-07-01

    The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study.

  4. Quantitative chemical analysis of ocular melanosomes in the TEM.

    PubMed

    Eibl, O; Schultheiss, S; Blitgen-Heinecke, P; Schraermeyer, U

    2006-01-01

    Melanosomes in retinal tissues of a human, monkey and rat were analyzed by EDX in the TEM. Samples were prepared by ultramicrotomy at different thicknesses. The material was mounted on Al grids and samples were analyzed in a Zeiss 912 TEM equipped with an Omega filter and EDX detector with ultrathin window. Melanosomes consist of C and O as main components, mole fractions are about 90 and 3-10 at.%, respectively, and small mole fraction ratios, between 2 and 0.1 at.%, of Na, Mg, K, Si, P, S, Cl, Ca. All elements were measured quantitatively by standardless EDX with high precision. Mole fractions of transition metals Fe, Cu and Zn were also measured. For Fe a mole fraction ratio of less than 0.1at.% was found and gives the melanin its paramagnetic properties. Its mole fraction is however close to or below the minimum detectable mass fraction of the used equipment. Only in the human eye and only in the retinal pigment epitelium (rpe) the mole fractions of Zn (0.1 at.% or 5000 microg/g) and Cu were clearly beyond the minimum detectable mass fraction. In the rat and monkey eye the mole fraction of Zn was at or below the minimum detectable mass fraction and could not be measured quantitatively. The obtained results yielded the chemical composition of the melanosomes in the choroidal tissue and the retinal pigment epitelium (rpe) of the three different species. The results of the chemical analysis are discussed by mole fraction correlation diagrams. Similarities and differences between the different species are outlined. Correlation behavior was found to hold over species, e.g. the Ca-O correlation. It indicates that Ca is bound to oxygen rich sites in the melanin. These are the first quantitative analyses of melanosomes by EDX reported so far. The quantitative chemical analysis should open a deeper understanding of the metabolic processes in the eye that are of central importance for the understanding of a large number of eye-related diseases. The chemical analysis also

  5. The XRD Amorphous Component in John Klein Drill Fines at Yellowknife Bay, Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Morris, R. V.; Ming, D. W.; Blake, D.; Vaniman, D.; Bish, D. L.; Chipera, S.; Downs, R.; Morrison, S.; Gellert, R.; Campbell, I.; Treiman, A. H.; Achilles, C.; Bristow, T.; Crisp, J. A.; McAdam, A.; Archer, P. D.; Sutter, B.; Rampe, E. B.; Team, M.

    2013-12-01

    Drill fines of mudstone (targets John Klein and Cumberland) from the Sheepbed unit at Yel-lowknife Bay were analyzed by MSL payload elements including the Chemistry and Mineralogy (CheMin), APXS (Alpha Particle X-Ray Spectrometer), and Sample Analysis at Mars (SAM) instruments. CheMin XRD results show a variety of crystalline phases including feldspar, pyrox-ene, olivine, oxides, oxyhydroxides, sulfates, sulfides, a tri-octahedral smectite, and XRD amorphous material. The drill fines are distinctly different from corresponding analyses of the global soil (target Rocknest) in that the mudstone samples contained detectable phyllosilicate. Here we focus on John Klein and combine CheMin and APXS data to calculate the chemical composition and concentration of the amorphous component. The chemical composition of the amorphous plus smectite component for John Klein was cal-culated by subtracting the abundance-weighted chemical composition of the individual XRD crystalline components from the bulk composition of John Kline as measured by APXS. The chemical composition of individual crystalline components was determined either by stoichiome-try (e.g., hematite and magnetite) or from their unit cell parameters (e.g., feldspar, olivine, and pyroxene). The chemical composition of the amorphous + smectite component (~71 wt.% of bulk sample) and bulk chemical compositon are similar. In order to calculate the chemical composition of the amorphous component, a chemical composition for the tri-octahedral smectite must be assumed. We selected two tri-octahedral smectites with very different MgO/(FeO + Fe2O3) ratios (34 and 1.3 for SapCa1 and Griffithite, respectively). Relative to bulk sample, the concentration of amorphous and smectite components are 40 and 29 wt.% for SapCa1 and 33 and 36 wt.% for Griffithite. The amount of smectite was calculated by requiring the MgO concentration to be~0 wt.% in the amporphous component. Griffithite is the preferred smectite because the position

  6. Hydration Characteristics of Metakaolin Admixtured Cement using DTA, XRD and SEM Techniques

    NASA Astrophysics Data System (ADS)

    Govindarajan, D.; Gopalakrishnan, R.

    2008-04-01

    The paper aims to investigate hydration and pozzolanic reaction in Portland cement paste with different replacement percentages (0%, 10%, 20% and 30%) of metakaolin. The compressive strength of the metakaolin admixtured cement was measured at 1 day, 1 week and 4 weeks. The compressive strength developments of the metakaolin admixtured cement are compared with Portland cement. It is found that metakaolin contributes significantly to strength development as an accelerating admixture for Portland cement. The pozzolanic reactions and the reaction products were determined by DTA, XRD and SEM.

  7. The XRD Amorphous Component in John Klein Drill Fines at Yellowknife Bay, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Ming,, Douglas W.; Blake, David; Vaniman, David; Bish, David L; Chipera, Steve; Downs, Robert; Morrison, Shaunna; Gellert, Ralf; Campbell, Iain; Treiman, Alan H.; Achilles, Cherie; Bristow, Thomas; Crisp, Joy A.; McAdam, Amy; Archer, Paul Douglas; Sutter, Brad; Rampe, Elizabeth B.

    2013-01-01

    Drill fines of mudstone (targets John Klein and Cumberland) from the Sheepbed unit at Yel-lowknife Bay were analyzed by MSL payload elements including the Chemistry and Mineralogy (CheMin), APXS (Alpha Particle X-Ray Spectrometer), and Sample Analysis at Mars (SAM) instruments. CheMin XRD results show a variety of crystalline phases including feldspar, pyroxene, olivine, oxides, oxyhydroxides, sulfates, sulfides, a tri-octahedral smectite, and XRD amorphous material. The drill fines are distinctly different from corresponding analyses of the global soil (target Rocknest) in that the mudstone samples contained detectable phyllosilicate. Here we focus on John Klein and combine CheMin and APXS data to calculate the chemical composition and concentration of the amorphous component. The chemical composition of the amorphous plus smectite component for John Klein was calculated by subtracting the abundance-weighted chemical composition of the individual XRD crystalline components from the bulk composition of John Kline as measured by APXS. The chemical composition of individual crystalline components was determined either by stoichiometry (e.g., hematite and magnetite) or from their unit cell parameters (e.g., feldspar, olivine, and pyroxene). The chemical composition of the amorphous + smectite component (approx 71 wt.% of bulk sample) and bulk chemical composition are similar. In order to calculate the chemical composition of the amorphous component, a chemical composition for the tri-octahedral smectite must be assumed. We selected two tri-octahedral smectites with very different MgO/(FeO + Fe2O3) ratios (34 and 1.3 for SapCa1 and Griffithite, respectively). Relative to bulk sample, the concentration of amorphous and smectite components are 40 and 29 wt.% for SapCa1 and 33 and 36 wt.% for Griffithite. The amount of smectite was calculated by requiring the MgO concentration to be approx 0 wt.% in the amorphous component. Griffithite is the preferred smectite because

  8. XRD, lead equivalent and UV-VIS properties study of Ce and Pr lead silicate glasses

    SciTech Connect

    Alias, Nor Hayati Abdullah, Wan Shafie Wan Isa, Norriza Mohd Isa, Muhammad Jamal Md Zali, Nurazila Mat; Abdullah, Nuhaslinda Ee; Muhammad, Azali

    2014-02-12

    In this work, Cerium (Ce) and Praseodymium (Pr) containing lead silicate glasses were produced with 2 different molar ratios low (0.2 wt%) and high (0.4wt%). These types of glasses can satisfy the characteristics required for radiation shielding glasses and minimize the lead composition in glass. The radiation shielding properties of the synthesized glasses is explained in the form of lead equivalent study. The XRD diffraction and UV-VIS analysis were performed to observe the structural changes of the synthesis glasses at 1.5 Gy gamma radiation exposures.

  9. A mathematical method for XRD pattern interpretation in clay containing nano composites

    NASA Astrophysics Data System (ADS)

    Khederlou, Kh.; Bagheri, R.; Shojaei, A.

    2014-11-01

    X-ray diffraction and rheological measurements were used to characterize nanoparticle dispersion in LDPE/LLDPE/nanoclay hybrid nanocomposites. XRD patterns were interpreted with a novel distribution formula and rheological measurements were used to confirm the results. Results of these two methods indicated that increasing clay in all the prepared nanocomposites exhibited a significant improvement in filler-matrix interaction because of increasing the probability of polymer diffusion but further exfoliation need more compatibilizing situations. It seems that this mathematical method could be used for predicting the overall change in clay gallery d-spacing and the extent of intercalation-exfoliation of nanoclay in these systems.

  10. XRD, lead equivalent and UV-VIS properties study of Ce and Pr lead silicate glasses

    NASA Astrophysics Data System (ADS)

    Alias, Nor Hayati; Abdullah, Wan Shafie Wan; Isa, Norriza Mohd; Isa, Muhammad Jamal Md; Muhammad, Azali; Zali, Nurazila Mat; Abdullah, Nuhaslinda Ee

    2014-02-01

    In this work, Cerium (Ce) and Praseodymium (Pr) containing lead silicate glasses were produced with 2 different molar ratios low (0.2 wt%) and high (0.4wt%). These types of glasses can satisfy the characteristics required for radiation shielding glasses and minimize the lead composition in glass. The radiation shielding properties of the synthesized glasses is explained in the form of lead equivalent study. The XRD diffraction and UV-VIS analysis were performed to observe the structural changes of the synthesis glasses at 1.5 Gy gamma radiation exposures.

  11. IN-SITU XRD OF OPERATING LSFC CATHODES: DEVELOPMENT OF A NEW ANALYTICAL CAPABILITY

    SciTech Connect

    Hardy, John S.; Templeton, Jared W.; Stevenson, Jeffry W.

    2012-11-19

    A solid oxide fuel cell (SOFC) research capability has been developed that facilitates measuring the electrochemical performance of an operating SOFC while simultaneously performing x-ray diffraction on its cathode. The evolution of this research tool’s development is discussed together with a description of the instrumentation used for in-situ x-ray diffraction (XRD) measurements of operating SOFC cathodes. The challenges that were overcome in the process of developing this capability, which included seals and cathode current collectors, are described together with the solutions that are presently being applied to mitigate them.

  12. Application of quantitative XRD on the precipitation of struvite from Brine Water

    NASA Astrophysics Data System (ADS)

    Heraldy, E.; Rahmawati, F.; Heryanto; Putra, D. P.

    2017-02-01

    The present studies have been conducted to quantify the varied phases in struvite formation from brine water as the magnesium source. The quantitative X-ray Diffraction (QXRD) method was performed to quantitatively determine the crystal phases and amorphous content of struvite samples. Substantial phase samples were employed quantitative analysis to calibrate against known phase composition information by Rietveld refinement on powder XRD data. The results showed that brine water could be considered as magnesium source the formation of struvite products. The study demonstrated that in general, the high N:P molar ratio (both pH 9 and 10) might lead to the significant formation of struvite.

  13. XRD studies of cement embedding matrices containing complexing reagents from decontamination practices

    SciTech Connect

    Ionascu, L.; Nicu, M.; Turcanu, M.; Dragolici, F.; Rotarescu, Ghe.

    2013-07-01

    The study of embedding matrix of radioactive waste is an important issue concerning the need to assure the radiological safety requirements for final disposal. The conditioning of the radioactive wastes by cementation process involves also a structural investigation by X-ray diffraction (XRD) of the samples prepared with cement and complexing agents at different concentration. This paper gives useful information about the influence of complexing agents related to damages produced in concrete microstructures. The experimental data obtained on samples kept in real repository environment for a period up to 15 years, offer structural information regarding the interaction between the different decontamination agents with the major components of the matrix. (authors)

  14. PIXE, SR-XRD and EXAFS analysis of Cu-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Yang, C.; Wang, J. Z.; Shi, L. Q.; Cheng, H. S.

    2014-08-01

    Cu-doped ZnO films were prepared by rf magnetron sputtering on sapphire substrate at different atmosphere. Microstructure of these films and Cu occupation sites were investigated using PIXE, SR-XRD and EXAFS. Only 2.9 at.% Cu, no other magnetic impurities (e.g., Fe, Co and Ni) were detected. The ZnO:Cu films possessed the wurtzite ZnO structures and no precipitates (e.g., CuO and Cu2O or Cu cluster) were found. Cu atoms were incorporated into ZnO crystal lattice by occupying Zn atomic sites.

  15. Investigation of Mg and Zn doped 45S5 bioactive materials by XRD, FTIR and SEM techniques

    NASA Astrophysics Data System (ADS)

    Anand, Vikas; Singh, K. J.; Kaur, Kulwinder

    2014-04-01

    Magnesium and zinc doped 45S5 samples were prepared in the laboratory by sol gel technique., Structural properties of the samples have been studied by XRD, FTIR and SEM techniques. Both FTIR and XRD data indicate the primary bioactive behavior of the samples. Presented results may be useful to improve the antibacterial as well as osteoblast properties of the currently available bioactive materials.

  16. TEM study of impurity segregations in beryllium pebbles

    NASA Astrophysics Data System (ADS)

    Klimenkov, M.; Chakin, V.; Moeslang, A.; Rolli, R.

    2014-12-01

    Beryllium is planned to be used as a neutron multiplier in the Helium-cooled Pebble Bed European concept of a breeding blanket of demonstration power reactor DEMO. In order to evaluate the irradiation performance, individual pebbles and constrained pebble beds were neutron-irradiated at temperatures typical of fusion blankets. Beryllium pebbles 1 mm in diameter produced by the rotating electrode method were subjected to a TEM study before and after irradiation at High Flux Reactor, Petten, Netherlands at 861 K. The grain size varied in a wide range from sub-micron size up to several tens of micrometers, which indicated formation bimodal grain size distribution. Based on the application of combined electron energy loss spectroscopy and energy dispersive X-ray spectroscopy methods, we suggest that impurity precipitates play an important role in controlling the mechanical properties of beryllium. The impurity elements were present in beryllium at a sub-percent concentration form beryllide particles of a complex (Fe/Al/Mn/Cr)B composition. These particles are often ordered along dislocations lines, forming several micron-long chains. It can be suggested that fracture surfaces often extended along these chains in irradiated material.

  17. Aquifer characterisation in East Timor, with ground TEM

    NASA Astrophysics Data System (ADS)

    Ley-Cooper, A.

    2011-12-01

    An assessment of Climate Change Impacts on Groundwater Resources in East Timor led by Geosciences Australia is aimed at assisting East Timor's government to better understand and manage their groundwater resources. Form the current known information most aquifers in Timor-Leste are recharged by rainfall during the wet season. There is a concern that without a regular recharge, the stored groundwater capacity will decrease. Timor's population increase has caused a higher demand for groundwater which is currently been met by regulated pumping bores which are taped into deep aquifers, plus the sprouting of unregulated spear point bores in the shallow aquifers . Both groundwater recharge and the aquifers morphology need to be better understood in order to ensure supply and so groundwater can be managed for the future. Current weather patterns are expected to change and this could cause longer periods of drought or more intense rainfall, which in turn, would affect the availability and quality of groundwater. Salt water intrusions pose a threat on the low-lying aquifers as sea level rises. Australia's CSIRO has undertaken a series hydrogeophysical investigations employing ground TEM to assist in the characterisation of three aquifers near Dili, Timor Leste's capital. Interpreting ground water chemistry and dating; jointly with EM data has enhanced the understanding of the aquifers architecture, groundwater quality and helped identify potential risks of seawater intrusions.

  18. TEM in situ lithiation of tin nanoneedles for battery applications

    SciTech Connect

    Janish, Matthew T.; Mackay, David T.; Liu, Yang; Jungjohann, Katherine L.; Carter, C. Barry; Norton, M. Grant

    2015-08-12

    Materials such as tin (Sn) and silicon that alloy with lithium (Li) have attracted renewed interest as anode materials in Li-ion batteries. Although their superior capacity to graphite and other intercalation materials has been known for decades, their mechanical instability due to extreme volume changes during cycling has traditionally limited their commercial viability. This limitation is changing as processes emerge that produce nanostructured electrodes. The nanostructures can accommodate the repeated expansion and contraction as Li is inserted and removed without failing mechanically. Recently, one such nano-manufacturing process, which is capable of depositing coatings of Sn “nanoneedles” at low temperature with no template and at industrial scales, has been described. The present work is concerned with observations of the lithiation and delithiation behavior of these Sn nanoneedles during in situ experiments in the transmission electron microscope, along with a brief review of how in situ TEM experiments have been used to study the lithiation of Li-alloying materials. Individual needles are successfully lithiated and delithiated in solid-state half-cells against a Li-metal counter-electrode. Furthermore the microstructural evolution of the needles is discussed, including the transformation of one needle from single-crystal Sn to polycrystalline Sn–Li and back to single-crystal Sn.

  19. TEM in situ lithiation of tin nanoneedles for battery applications

    DOE PAGES

    Janish, Matthew T.; Mackay, David T.; Liu, Yang; ...

    2015-08-12

    Materials such as tin (Sn) and silicon that alloy with lithium (Li) have attracted renewed interest as anode materials in Li-ion batteries. Although their superior capacity to graphite and other intercalation materials has been known for decades, their mechanical instability due to extreme volume changes during cycling has traditionally limited their commercial viability. This limitation is changing as processes emerge that produce nanostructured electrodes. The nanostructures can accommodate the repeated expansion and contraction as Li is inserted and removed without failing mechanically. Recently, one such nano-manufacturing process, which is capable of depositing coatings of Sn “nanoneedles” at low temperature withmore » no template and at industrial scales, has been described. The present work is concerned with observations of the lithiation and delithiation behavior of these Sn nanoneedles during in situ experiments in the transmission electron microscope, along with a brief review of how in situ TEM experiments have been used to study the lithiation of Li-alloying materials. Individual needles are successfully lithiated and delithiated in solid-state half-cells against a Li-metal counter-electrode. Furthermore the microstructural evolution of the needles is discussed, including the transformation of one needle from single-crystal Sn to polycrystalline Sn–Li and back to single-crystal Sn.« less

  20. Investigation of NaCl deliquescence in porous substrates using RH-XRD

    NASA Astrophysics Data System (ADS)

    Linnow, Kirsten; Juling, Herbert; Steiger, Michael

    2007-03-01

    We report on the use of X-ray diffractometry under controlled conditions of temperature and relative humidity (RH-XRD) for the investigation of NaCl deliquescence in the pore space of glass filter frits, which were used as model substrates. The study confirms that RH-XRD is an appropriate experimental technique for the in situ observation of phase transformation in porous materials. It is used for an investigation of both the deliquescence kinetics and the deliquescence humidity within pores of different median pore diameter. Several major influences affecting deliquescence rates in the pore space close to the surface of a porous material are discussed. It appears that quite short-term variation of ambient relative humidity, e.g., typical daily fluctuations, might induce damaging deliquescence-crystallization cycles within the pore space of building materials. In agreement with theoretical considerations it was found that confinement of NaCl crystals in pores with median diameters in the range 1.4-70 μm does not affect the deliquescence humidity of the salt.

  1. Determination of equilibrium humidities using temperature and humidity controlled X-ray diffraction (RH-XRD).

    PubMed

    Linnow, Kirsten; Steiger, Michael

    2007-01-30

    Confined growth of crystals in porous building materials is generally considered to be a major cause of damage. We report on the use of X-ray diffraction under controlled conditions of temperature and relative humidity (RH-XRD) for the investigation of potentially deleterious phase transition reactions. An improved procedure based on rate measurements is used for the accurate and reproducible determination of equilibrium humidities of deliquescence and hydration reactions. The deliquescence humidities of NaCl (75.4+/-0.5% RH) and Ca(NO3)2 x 4 H2O (50.8+/-0.7% RH) at 25 degrees C determined with this improved RH-XRD technique are in excellent agreement with available literature data. Measurement of the hydration of anhydrous Ca(NO3)2 to form Ca(NO3)2 x 2 H2O revealed an equilibrium humidity of 10.2+/-0.3%, which is also in reasonable agreement with available data. In conclusion, dynamic X-ray diffraction measurements are an appropriate method for the accurate and precise determination of equilibrium humidities with a number of interesting future applications.

  2. Crystal growth in Se70Te30 thin films followed by SEM and in situ XRD

    NASA Astrophysics Data System (ADS)

    Martinková, Simona; Barták, Jaroslav; Málek, Jiri; Segawa, Hiroyo

    2016-10-01

    The isothermal crystal growth kinetics in Se70Te30 thin films was investigated using the microscopy and in situ X-ray diffraction (XRD) measurements. Plate-like crystals grew linearly with time which is the sign of liquid-crystal interface kinetics. In the studied temperature range, from 68 °C to 88 °C, crystal growth rates exhibit simple exponential behavior with an activation energy of crystal growth EG = 168 ± 12 kJ mol-1. The growth data obtained from the microscopy measurements were combined with viscosity data, melting parameters and the appropriate crystal growth model was assessed. The relation between the kinetic coefficient of crystal growth and viscosity (u∝η-ξ) is described in detail, and a correction of the standard growth model is suggested. The crystal growth data obtained from the in situ XRD measurements were described using the Johnson-Mehl-Avrami nucleation-growth model with the Avrami exponent m = 2.2 ± 0.2. The activation energy of the overall crystallization process EA was estimated and its value is 171 ± 11 kJ mol-1.

  3. Trace elemental analysis of Indian natural moonstone gems by PIXE and XRD techniques.

    PubMed

    Venkateswara Rao, R; Venkateswarulu, P; Kasipathi, C; Sivajyothi, S

    2013-12-01

    A selected number of Indian Eastern Ghats natural moonstone gems were studied with a powerful nuclear analytical and non-destructive Proton Induced X-ray Emission (PIXE) technique. Thirteen elements, including V, Co, Ni, Zn, Ga, Ba and Pb, were identified in these moonstones and may be useful in interpreting the various geochemical conditions and the probable cause of their inceptions in the moonstone gemstone matrix. Furthermore, preliminary XRD studies of different moonstone patterns were performed. The PIXE technique is a powerful method for quickly determining the elemental concentration of a substance. A 3MeV proton beam was employed to excite the samples. The chemical constituents of moonstones from parts of the Eastern Ghats geological formations of Andhra Pradesh, India were determined, and gemological studies were performed on those gems. The crystal structure and the lattice parameters of the moonstones were estimated using X-Ray Diffraction studies, trace and minor elements were determined using the PIXE technique, and major compositional elements were confirmed by XRD. In the present work, the usefulness and versatility of the PIXE technique for research in geo-scientific methodology is established.

  4. XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

    SciTech Connect

    Borodi, G.; Pascuta, P.; Dan, V.; Pop, V.; Stefan, R.; Radulescu, D.

    2013-11-13

    X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} glass ceramics system, with 0 ≤ x ≤ 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB{sub 4}O{sub 7}, Zn{sub 4}O(B{sub 6}O{sub 12}), Zn{sub 3}(BO{sub 3}){sub 2} and GdBO{sub 3}. From the XRD data, the average unit-cell parameter and the quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO{sub 3}, BO{sub 4} and ZnO{sub 4} are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed.

  5. Mössbauer and XRD study of hot dip galvanized alloy

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Speakman, R.; El-Sharif, M.; Stichleutner, S.; Homonnay, Z.; Klencsár, Z.; Sziráki, L.; Chisholm, C. U.; Lak, Gy. B.

    2016-12-01

    Mössbauer spectroscopy has been used to investigate the nature of the Zinc-Iron alloys present within the Hot Dip Galvanized (HDG) layers of steel with a silicon content of 0.35 %. The investigation also studied the impact of the powder coating pretreatment on the nature of the alloy layers. The acid etching process within the pretreatment process in particular would be expected to have a significant impact on the HDG layer. This study utilized 57Fe Mössbauer spectroscopy to examine identically processed samples prior to and post pre treatment. XRD and 57Fe CEMS measurements were performed on hot galvanized S355J2 + N samples, forming sandwiched structure. Both XRD and CEMS reveal the presence of dominant steel phase in accordance with its estimated occurrence on the surface of the sandwiched samples. Minor Γ-Fe3Zn10, ζ-FeZn15 and solid solution Fe-Zn as well as minor Fe-Si phases could also be identified.

  6. The chaotic points and XRD analysis of Hg-based superconductors

    NASA Astrophysics Data System (ADS)

    Aslan, Ö.; Güven Özdemir, Z.; Keskin, S. S.; Onbaşli, Ü.

    2009-03-01

    In this article, high Tc mercury based cuprate superconductors with different oxygen doping rates have been examined by means of magnetic susceptibility (magnetization) versus temperature data and X-ray diffraction pattern analysis. The under, optimally and over oxygen doping procedures have been defined from the magnetic susceptibility versus temperature data of the superconducting sample by extracting the Meissner critical transition temperature, Tc and the paramagnetic Meissner temperature, TPME, so called as the critical quantum chaos points. Moreover, the optimally oxygen doped samples have been investigated under both a.c. and d.c. magnetic fields. The related a.c. data for virgin(uncut) and cut samples with optimal doping have been obtained under a.c. magnetic field of 1 Gauss. For the cut sample with the rectangular shape, the chaotic points have been found to occur at 122 and 140 K, respectively. The Meissner critical temperature of 140 K is the new world record for the high temperature oxide superconductors under normal atmospheric pressure. Moreover, the crystallographic lattice parameters of superconducting samples have a crucial importance in calculating Josephson penetration depth determined by the XRD patterns. From the XRD data obtained for under and optimally doped samples, the crystal symmetries have been found in tetragonal structure.

  7. An Integrated XRF/XRD Instrument for Mars Exobiology and Geology Experiments

    NASA Technical Reports Server (NTRS)

    Koppel, L. N.; Franco, E. D.; Kerner, J. A.; Fonda, M. L.; Schwartz, D. E.; Marshall, J. R.

    1993-01-01

    By employing an integrated x-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details characterizing the past and present environment on Mars and those relevant to the possibility of the origin and evolution of life will be acquired. A combined x-ray fluorescence/x-ray diffraction (XRF/XRD) instrument was breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for MESUR and future Mars missions. Among others, primary objectives for the exploration of Mars include the intense study of local areas on Mars to establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance, and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epoches; and to establish the global chemical and physical characteristics of the Martian surface. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment. Preliminary breadboard experiments confirmed the fundamental instrument design approach and measurement performance.

  8. FTIR, XRD and DSC studies of nanochitosan, cellulose acetate and polyethylene glycol blend ultrafiltration membranes.

    PubMed

    Vinodhini, P Angelin; K, Sangeetha; Thandapani, Gomathi; P N, Sudha; Jayachandran, Venkatesan; Sukumaran, Anil

    2017-03-29

    In the present work, a series of novel nanochitosan/cellulose acetate/polyethylene glycol (NCS/CA/PEG) blend flat sheet membranes were fabricated in different ratios (1:1:1, 1:1:2, 2:1:1, 2:1:2, 1:2:1, 2:2:1) in a polar solvent of N,N'-dimethylformamide (DMF) using the most popular phase inversion method. Nanochitosan was prepared by the ionotropic gelation method and its average particle size has been analyzed using Dynamic Light Scattering (DLS) method. The effect of blending of the three polymers was investigated using FTIR and XRD studies. FTIR results confirmed the formation of well-blended membranes and the XRD analysis revealed enhanced amorphous nature of the membrane ratio 2:1:2. DSC study was conducted to find out the thermal behavior of the blend membranes and the results clearly indicated good thermal stability and single glass transition temperature (Tg) of all the prepared membranes. Asymmetric nature and rough surface morphology was confirmed using SEM analysis. From the results it was evident that the blending of the polymers with higher concentration of nanochitosan can alter the nature of the resulting membranes to a greater extent and thus amorphous membranes were obtained with good miscibility and compatibility.

  9. TEM Study of Manganese Biosorption by Cyanobacterium Synechocystis 6803

    SciTech Connect

    Dohnalkova, Alice; Bilskis, Christina L.; Kennedy, David W.

    2006-09-01

    The capture of solar energy and its conversion into chemical energy in photosynthetic organisms involves a series of charge reactions across photosynthetic membranes. Oxygen is generated by a proton-electron coupling in photosystem II (PSII) during a water oxidation process where hydrogen is extracted from water terminally bound to a Mn4Ca1Clx inorganic cluster [1]. Manganese is, therefore, an essential catalytic element for photosynthetic growth in cyanobacteria and plants. Since bioavailability of this micronutrient largely depends on the Mn concentration in natural environments, cells have to manage its uptake in order to endure Mn fluctuations. Previous studies have shown that metal biosorption in cyanobacteria can occur by passive adsorption to their outer membrane (pool A), and by metabolically mediated internal uptake [2]. The fresh water cyanobacterium Synechocystis 6803 has been widely used as a model organism for studying photosynthetic processes. This Gram-negative organism has an intricate architecture of internal thylakoid membranes where photosynthetic electron transfer takes place. Here we report on the spatial distribution of Mn biosorbed by cells in both external pool A and intracellular pool B, as observed and analyzed by methods of TEM. The Synechocystis 6803 cells were cultured in BG11 medium at 30 C with continuous irradiance and constant air bubbling. To determine the influence of solid or liquid Mn substrate and its oxidation state on the cell biosorption ability, cells were exposed to two Mn substrates: 1mM solution of MnCl2, and 0.5mM suspension of nanocrystalline MnO2. Cells were incubated with the respective Mn solutions for 48 hours, harvested, and processed using a modified protocol for plastic embedding of bacterial samples containing minerals that was developed in our laboratory [3]. In order to preserve the fragile redox conditions within the cells, all the common heavy metal-based fixatives and stains were omitted, resulting in

  10. Three Dimensional TEM Forward Modeling Using FDTD Accelerated by GPU

    NASA Astrophysics Data System (ADS)

    Li, Z.; Huang, Q.

    2015-12-01

    Three dimensional inversion of transient electromagnetic (TEM) data is still challenging. The inversion speed mostly depends on the forward modeling. Finite-difference time-domain (FDTD) method is one of the popular forward modeling scheme. In an explicit type, which is based on the Du Fort-Frankel scheme, the time step is under the constraint of quasi-static approximation. Often an upward-continuation boundary condition (UCBC) is applied on the earth-air surface to avoid time stepping in the model air. However, UCBC is not suitable for models with topography and has a low parallel efficiency. Modeling without UCBC may cause a much smaller time step because of the resistive attribute of the air and the quasi-static constraint, which may also low the efficiency greatly. Our recent research shows that the time step in the model air is not needed to be constrained by the quasi-static approximation, which can let the time step without UCBC much closer to that with UCBC. The parallel performance of FDTD is then largely released. On a computer with a 4-core CPU, this newly developed method is obviously faster than the method using UCBC. Besides, without UCBC, this method can be easily accelerated by Graphics Processing Unit (GPU). On a computer with a CPU of 4790k@4.4GHz and a GPU of GTX 970, the speed accelerated by CUDA is almost 10 times of that using CPU only. For a model with a grid size of 140×140×130, if the conductivity of the model earth is 0.02S/m, and the minimal space interval is 15m, it takes only 80 seconds to evolve the field from excitation to 0.032s.

  11. In-situ TEM characterization of Copper Growth

    NASA Astrophysics Data System (ADS)

    Shelberg, Daniel T.

    In-situ liquid experiments in the transmission electron microscope (TEM) allow dynamic phenomena to be imaged at the nanoscale. This opens the opportunity to view electrochemical depositions at the nano scale in real time. However, there are a number of issues regarding in situ imaging that prevent a straightforward approach. This thesis addresses two issues regarding in-situ experiments; the fabrication of electron transparent windows and the nucleation of a metal from an electrolyte as a result of beam damage. Silicon chips that were 2.6mm x 2.6mm with 50mum x 50mum windows consisting of 50nm S3N 4 were fabricated with the goal of minimizing fabrication complexity at a cost significantly below commercial prices. These silicon nitride windows were used to sandwich a small volume of CuSO4 solution and observe copper nucleation as a result of the radiolysis damage of water due to the electron beam. Scanning transmission electron microscopy (STEM) was used to image growth, and reducing species are shown to diffuse on the order of hundreds of nanometers in solution. Copper nanoparticle growth was compared to Oswald ripening, and diffusion limited growth was observed at high electron dose rates. The diffusion limited growth was suppressed and led to a slower growth rate, with a calculated diffusion coefficient for Cu 2+ of 2 x 10--10 m2/s. Low electron dose rates corresponding to low magnifications in STEM yielded kinetic limited or mixed growth and yielded faceted nanoparticles. Atomic resolution was achieved in copper film deposited at low magnifications, and lattice fringes corresponding to the copper <111> were observed.

  12. The high - low-p clinoenstatite transition: in situ xrd and ultrasonic study

    NASA Astrophysics Data System (ADS)

    Müller, H. J.; Wunder, B.; Lathe, C.; Schilling, F. R.

    2003-04-01

    Using single-crystal X-ray diffraction analyses in a diamond anvil cell Angel et al. (1992) published the transformation of MgSiO_3 from LCEn to a C2/c-polymorph (HCEn) at around 5.5 - 8.0 GPa and room-T (RT)conditions. This LCEn - HCEn-transition is not quenchable. However, the knowledge of the exact phase boundary positions for the MgSiO_3-transitions is essential as pyroxene is an important component of the Earth's mantle and will significantly influence elastic properties (e.g. v_p, v_s) of the mantle. We determined the HCEn - LCEn-transition by in-situ XRD experiments under high P, T using the multi-anvil appar atus MAX80 at the synchrotron facility HASYLAB, Hamburg. Our preliminary results only represent the minimum P-conditions of the HCEn - LCEn phase boundary, which is approximated by equation P (GPa) = 0.0021T (/C) + 6.06. Nevertheless, our results are in good agreement to data published by Angel & Hugh-Jones (1994). The invariant point defined by the intersection of the HCEn - LCEn equilibrium determined within this study and the OEn - LCEn reaction after Angel &Hugh-Jones (1994) lies at about 7.9 GPa and 875/C. This is in contrast to earlier experimental results of Kanzaki (1991) and Ulmer &Stalder (2001). The samples for the ultrasonic interferometry experiments were prepared by hot-isostatic pressing also using the MAX80. Adjacent XRD ruled out any phase transition during the hip-process. For the ultrasonic measurements one of the six anvils of MAX80 were exchanged by an anvil equipped with lithium niobate p- and s-wave transducers of 33.3 MHz natural frequency (Mueller et al., 2002). Corresponding to the XRD experiments HCEn was formed by increasing the pressure at RT. The velocities of elastic compressional and shear waves were measured under in situ conditions using the classical digital sweep technique. After the phase transition to LCEn as a result of rising the temperature at given pressure the measurements were repeated. The newly developed

  13. Evaluation of rock powdering methods to obtain fine-grained samples for CHEMIN, a combined XRD/XRF instrument

    SciTech Connect

    Chipera, S. J.; Vaniman, D. T.; Bish, D. L.; Sarrazin, P.; Feldman, S.; Blake, D.; Bearman, G. H.; Bar-Cohen, Yoseph

    2004-01-01

    A miniature XRD/XRD (X-ray diffraction/X-ray fluorescence) instrument, CHEMIN, is currently being developed for definite mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed to enable remote XRD analysis is how best to obtain a representative sample powder for analysis. For powder XRD analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a two-dimensional detector as used in the CHEMIN instrument produces good results even with poorly prepared powder, the quality of the data improves and the time required for data collection is reduced if the sample is fine-grained and randomly oriented. A variety of methods have been proposed for XRD sample preparation. Chipera et al. presented grain size distributions and XRD reuslts from powders generated with an Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL. The USDC was shown to be an effective instrument for sampling rock to produce powder suitable for XRD. In this paper, they compare powder prepared using the USDC with powder obtained with a miniaturized rock crusher developed at JPL and with powder obtained with a rotary tungsten carbide bit to powders obtained from a laboratory bench-scale Retsch mill (provides benchmark mineralogical data). These comparisons will allow assessment of the suitability of these methods for analysis by an XRD/XRD instrument such as CHEMIN.

  14. High temperature XRD of Cu{sub 2}GeSe{sub 3}

    SciTech Connect

    Premkumar, D. S.; Malar, P.; Chetty, Raju; Mallik, Ramesh Chandra

    2015-06-24

    The Cu{sub 2}GeSe{sub 3} is prepared by solid state synthesis method. The high temperature XRD has been done at different temperature from 30 °C to 450 °C. The reitveld refinement confirms Cu{sub 2}GeSe{sub 3} phase and orthorhombic crystal structure. The lattice constants are increasing with increase in the temperature and their rate of increase with respect to temperature are used for finding the thermal expansion coefficient. The calculation of the linear and volume coefficient of thermal expansion is done from 30 °C to 400 °C. Decrease in the values of linear expansion coefficients with temperature are observed along a and c axis. Since thermal expansion coefficient is the consequence of the distortion of atoms in the lattice; this can be further used to find the minimum lattice thermal conductivity at given temperature.

  15. Laboratory Detection and Analysis of Organic Compounds in Rocks Using HPLC and XRD Methods

    NASA Technical Reports Server (NTRS)

    Dragoi, D.; Kanik, I.; Bar-Cohen, Y.; Sherrit, S.; Tsapin, A.; Kulleck, J.

    2004-01-01

    In this work we describe an analytical method for determining the presence of organic compounds in rocks, limestone, and other composite materials. Our preliminary laboratory experiments on different rocks/limestone show that the organic component in mineralogical matrices is a minor phase on order of hundreds of ppm and can be better detected using high precision liquid chromatography (HPLC). The matrix, which is the major phase, plays an important role in embedding and protecting the organic molecules from the harsh Martian environment. Some rocks bear significant amounts of amino acids therefore, it is possible to identify these phases using powder x-ray diffraction (XRD) by crystallizing the organic. The method of detection/analysis of organics, in particular amino acids, that have been associated with life will be shown in the next section.

  16. Formation of nickel-manganese oxide thermistors studied by XRD, SEM and auger spectroscopy

    NASA Astrophysics Data System (ADS)

    Azimi-Nam, S.; Golestani-Fard, F.; Hashemi, T.

    1987-03-01

    This paper describes the formation of nickel-manganeses oxide thermistor bodies at 1000 1340° C, employing analytical techniques of XRD, SEM/EPMA and AES. The micro-structural studies revealed that the main phase of nickel manganite coexists with a solid solution of NiO in Mn3O4 in the final product. The optimum firing conditions to achieve the necessary electrical properties as well as the development of the desired microstructure could be selected around 1200° C, for 4 hrs in an ambient atmosphere. Above this temperature, the density begins to decrease while the resistivity increases. These anomalous electrical resistivity variations could be partly attributed to the trapped oxygen which was evolved from the decomposition of the unreacted α-Mn2O3. At-lower temperatures, unreacted nickel oxide residuals as well as a high porosity of the samples would yield specimens with high resistivity.

  17. EXAFS and XRD characterization of palladium sorbents for high temperature mercury capture from fuel gas.

    PubMed

    Poulston, Stephen; Hyde, Timothy I; Hamilton, Hugh; Mathon, Olivier; Prestipino, Carmelo; Sankar, Gopinathan; Smith, Andrew W J

    2010-01-14

    Removal of pollutants such as mercury at elevated temperatures provides improvements in the overall thermal efficiency during the process of coal gasification. The two high temperature sorbents studied were 5 wt% Pd/Al(2)O(3) and 5 wt% Pd/SiO(2): materials shown to have significantly different Hg adsorption capacities. A combination of XRD and EXAFS has been used to characterize the Pd-Hg alloy formed when these Pd-based sorbents were exposed to fuel gas (CO, CO(2), H(2)) containing Hg vapour at 204 degrees C. Significant differences were found in the nature of the alloy formed on the two sorbents following Hg exposure. The Pd/Al(2)O(3) sorbent produced a single homogeneous solid solution of Pd-Hg whilst the silica-supported Pd produced an alloy of varying composition.

  18. Studying Cellulose Fiber Structure by SEM, XRD, NMR and Acid Hydrolysis

    SciTech Connect

    Zhao, Haibo; Kwak, Ja Hun; Zhang, Z. Conrad; Brown, Heather M.; Arey, Bruce W.; Holladay, John E.

    2007-03-21

    Cotton linters were partially hydrolyzed in dilute acid and the morphology of remaining macrofibrils studied with Scanning Electron Microscopy (SEM) under various magnifications. The crystal region (microfibril bundles) in the macrofibrils was not altered by hydrolysis, and only amorphous cellulose was hydrolyzed and leached out from the macrofibrils. The diameter of microfibril bundles was 20-30 nm after the amorphous cellulose was removed by hydrolysis. XRD experiments confirm the unaltered diameter of the microfibrils after hydrolysis. The strong stability of these microfibril bundles in hydrolysis limits both the total sugar monomer yield and the size of nano particles or rods produced in hydrolysis. The large surface potential on the remaining microfibril bundles drives the agglomeration of macrofibrils.

  19. Powder XRD and dielectric studies of gel grown calcium pyrophosphate crystals

    NASA Astrophysics Data System (ADS)

    Parekh, Bharat; Parikh, Ketan; Joshi, Mihir

    2013-06-01

    Formation of calcium pyrophosphate dihydrate (CPPD) crystals in soft tissues such as cartilage, meniscus and synovial tissue leads to CPPD deposition diseases. The appearance of these crystals in the synovial fluid can give rise to an acute arthritic attack with pain and inflammation of the joints, a condition called pseudo-gout. The growth of CPP crystals has been carried out, in the present study, using the single diffusion gel growth technique, which can broadly mimic in vitro the condition in soft tissues. The crystals were characterized by different techniques. The FTIR study revealed the presence of various functional groups. Powder XRD study was also carried out to verify the crystal structure. The dielectric study was carried out at room temperature by applying field of different frequency from 500 Hz to 1 MHz. The dielectric constant, dielectric loss and a.c. resistivity decreased as frequency increased, whereas the a.c. conductivity increased as frequency increased.

  20. Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

    PubMed

    Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

    2015-11-28

    Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

  1. Thermal behavior of polyhalite: a high-temperature synchrotron XRD study

    NASA Astrophysics Data System (ADS)

    Xu, Hongwu; Guo, Xiaofeng; Bai, Jianming

    2017-02-01

    As an accessory mineral in marine evaporites, polyhalite, K2MgCa2(SO4)4·2H2O, coexists with halite (NaCl) in salt formations, which have been considered as potential repositories for permanent storage of high-level nuclear wastes. However, because of the heat generated by radioactive decays in the wastes, polyhalite may dehydrate, and the released water will dissolve its neighboring salt, potentially affecting the repository integrity. Thus, studying the thermal behavior of polyhalite is important. In this work, a polyhalite sample containing a small amount of halite was collected from the Salado formation at the WIPP site in Carlsbad, New Mexico. To determine its thermal behavior, in situ high-temperature synchrotron X-ray diffraction was conducted from room temperature to 1066 K with the sample powders sealed in a silica-glass capillary. At about 506 K, polyhalite started to decompose into water vapor, anhydrite (CaSO4) and two langbeinite-type phases, K2Ca x Mg2- x (SO4)3, with different Ca/Mg ratios. XRD peaks of the minor halite disappeared, presumably due to its dissolution by water vapor. With further increasing temperature, the two langbeinite solid solution phases displayed complex variations in crystallinity, composition and their molar ratio and then were combined into the single-phase triple salt, K2CaMg(SO4)3, at 919 K. Rietveld analyses of the XRD data allowed determination of structural parameters of polyhalite and its decomposed anhydrite and langbeinite phases as a function of temperature. From the results, the thermal expansion coefficients of these phases have been derived, and the structural mechanisms of their thermal behavior been discussed.

  2. Synchrotron-based XRD from rat bone of different age groups.

    PubMed

    Rao, D V; Gigante, G E; Cesareo, R; Brunetti, A; Schiavon, N; Akatsuka, T; Yuasa, T; Takeda, T

    2017-05-01

    Synchrotron-based XRD spectra from rat bone of different age groups (w, 56 w and 78w), lumber vertebra at early stages of bone formation, Calcium hydroxyapatite (HAp) [Ca10(PO4)6(OH)2] bone fill with varying composition (60% and 70%) and bone cream (35-48%), has been acquired with 15keV synchrotron X-rays. Experiments were performed at Desy, Hamburg, Germany, utilizing the Resonant and Diffraction beamline (P9), with 15keV X-rays (λ=0.82666 A(0)). Diffraction data were quantitatively analyzed using the Rietveld refinement approach, which allowed us to characterize the structure of these samples in their early stages. Hydroxyapatite, received considerable attention in medical and materials sciences, since these materials are the hard tissues, such as bone and teeth. Higher bioactivity of these samples gained reasonable interest for biological application and for bone tissue repair in oral surgery and orthopedics. The results obtained from these samples, such as phase data, crystalline size of the phases, as well as the degree of crystallinity, confirm the apatite family crystallizing in a hexagonal system, space group P63/m with the lattice parameters of a=9.4328Å and c=6.8842Å (JCPDS card #09-0432). Synchrotron-based XRD patterns are relatively sharp and well resolved and can be attributed to the hexagonal crystal form of hydroxyapatite. All the samples were examined with scanning electron microscope at an accelerating voltage of 15kV. The presence of large globules of different sizes is observed, in small age groups of the rat bone (8w) and lumber vertebra (LV), as distinguished from, large age groups (56 and 78w) in all samples with different magnification, reflects an amorphous phase without significant traces of crystalline phases. Scanning electron microscopy (SEM) was used to characterize the morphology and crystalline properties of Hap, for all the samples, from 2 to 100μm resolution.

  3. Spectroscopic, DFT, and XRD Studies of Hydrogen Bonds in N-Unsubstituted 2-Aminobenzamides.

    PubMed

    Mphahlele, Malose Jack; Maluleka, Marole Maria; Rhyman, Lydia; Ramasami, Ponnadurai; Mampa, Richard Mokome

    2017-01-04

    The structures of the mono- and the dihalogenated N-unsubstituted 2-aminobenzamides were characterized by means of the spectroscopic (¹H-NMR, UV-Vis, FT-IR, and FT-Raman) and X-ray crystallographic techniques complemented with a density functional theory (DFT) method. The hindered rotation of the C(O)-NH₂ single bond resulted in non-equivalence of the amide protons and therefore two distinct resonances of different chemical shift values in the ¹H-NMR spectra of these compounds were observed. 2-Amino-5-bromobenzamide (ABB) as a model confirmed the presence of strong intramolecular hydrogen bonds between oxygen and the amine hydrogen. However, intramolecular hydrogen bonding between the carbonyl oxygen and the amine protons was not observed in the solution phase due to a rapid exchange of these two protons with the solvent and fast rotation of the Ar-NH₂ single bond. XRD also revealed the ability of the amide unit of these compounds to function as a hydrogen bond donor and acceptor simultaneously to form strong intermolecular hydrogen bonding between oxygen of one molecule and the NH moiety of the amine or amide group of the other molecule and between the amine nitrogen and the amide hydrogen of different molecules. DFT calculations using the B3LYP/6-311++G(d,p) basis set revealed that the conformer (A) with oxygen and 2-amine on the same side predominates possibly due to the formation of a six-membered intramolecular ring, which is assisted by hydrogen bonding as observed in the single crystal XRD structure.

  4. XRD and VCD: a marriage of love or convenience? Honeymoon around a cyclic urea derivative.

    PubMed

    Gherase, Dragos; Naubron, Jean-Valère; Roussel, Christian; Giorgi, Michel

    2012-07-01

    The structures and absolute configurations of the enantiomers (3aR,8aR)-2,2-dimethyl-4,4,8,8-tetraphenyl-4,5,6,7,8,8a-hexahydro-3aH-1,3-dioxolo[4,5-e][1,3]diazepin-6-one 0.33-hydrate, C(32)H(30)N(2)O(3)·0.33H(2)O, (Ia), and (3aS,8aS)-2,2-dimethyl-4,4,8,8-tetraphenyl-4,5,6,7,8,8a-hexahydro-3aH-1,3-dioxolo[4,5-e][1,3]diazepin-6-one 0.39-hydrate, C(32)H(30)N(2)O(3)·0.39H(2)O, (Ib), have been elucidated unambiguously using the complementary power of single-crystal X-ray diffraction (XRD) and vibrational circular dichroism (VCD). The enantiomers crystallize in the Sohncke space group P2(1)2(1)2 and pack as dimers stabilized by two symmetric hydrogen bonds involving one amide group each of the cyclic urea moiety. This double interaction is capped by a water molecule that partially occupies a site lying on the twofold axis and forms an uncommon hydrogen bond between the two monomers. A comparison between the solid-state VCD characterizations and the Bayesian statistics on Bijvoet differences determined from the XRD measurements reveals a tendency towards the correct determination of the absolute configuration by this latter method.

  5. Thermal behavior of polyhalite: a high-temperature synchrotron XRD study

    NASA Astrophysics Data System (ADS)

    Xu, Hongwu; Guo, Xiaofeng; Bai, Jianming

    2016-09-01

    As an accessory mineral in marine evaporites, polyhalite, K2MgCa2(SO4)4·2H2O, coexists with halite (NaCl) in salt formations, which have been considered as potential repositories for permanent storage of high-level nuclear wastes. However, because of the heat generated by radioactive decays in the wastes, polyhalite may dehydrate, and the released water will dissolve its neighboring salt, potentially affecting the repository integrity. Thus, studying the thermal behavior of polyhalite is important. In this work, a polyhalite sample containing a small amount of halite was collected from the Salado formation at the WIPP site in Carlsbad, New Mexico. To determine its thermal behavior, in situ high-temperature synchrotron X-ray diffraction was conducted from room temperature to 1066 K with the sample powders sealed in a silica-glass capillary. At about 506 K, polyhalite started to decompose into water vapor, anhydrite (CaSO4) and two langbeinite-type phases, K2Ca x Mg2-x (SO4)3, with different Ca/Mg ratios. XRD peaks of the minor halite disappeared, presumably due to its dissolution by water vapor. With further increasing temperature, the two langbeinite solid solution phases displayed complex variations in crystallinity, composition and their molar ratio and then were combined into the single-phase triple salt, K2CaMg(SO4)3, at ~919 K. Rietveld analyses of the XRD data allowed determination of structural parameters of polyhalite and its decomposed anhydrite and langbeinite phases as a function of temperature. From the results, the thermal expansion coefficients of these phases have been derived, and the structural mechanisms of their thermal behavior been discussed.

  6. Carbonate Mineral Assemblages as Inclusions in Yakutian Diamonds: TEM Verifications

    NASA Astrophysics Data System (ADS)

    Logvinova, A. M.; Wirth, R.; Sobolev, N. V.; Taylor, L. A.

    2014-12-01

    Carbonate mineral inclusions are quite rare in diamonds from the upper mantle, but are evidence for a carbonate abundance in the mantle. It is believed that such carbonatitic inclusions originated from high-density fluids (HDFs) that were enclosed in diamond during its growth. Using TEM and EPMA, several kinds of carbonate inclusions have been identified in Yakutian diamonds : aragonite, dolomite, magnesite, Ba-, Sr-, and Fe-rich carbonates. Most of them are represented by multi-phase inclusions of various chemically distinct carbonates, rich in Ca, Mg, and K and associated with minor amounts of silicate, oxide, saline, and volatile phases. Volatiles, leaving some porosity, played a significant role in the diamond growth. A single crystal of aragonite (60μm) is herein reported for the first time. This inclusion is located in the center of a diamond from the Komsomolskaya pipe. Careful CL imaging reveals the total absence of cracks around the aragonite inclusion - i.e., closed system. This inclusion has been identified by X-ray diffraction and microprobe analysis. At temperatures above 1000 0C, aragonite is only stable at high pressures of 5-6 GPa. Inside this aragonite, we observed nanocrystalline inclusions of titanite, Ni-rich sulfide, magnetite, water-bearing Mg-silicate, and fluid bubbles. Dolomite is common in carbonate multi-phase inclusions in diamonds from the Internatsionalnaya, Yubileinaya, and Udachnaya kimberlite pipes. Alluvial diamonds of the northeastern Siberian Platform are divided into two groups based on the composition of HDFs: 1) Mg-rich multi-phase inclusions (60% magnesite + dolomite + Fe-spinel + Ti-silicate + fluid bubbles); and 2) Ca-rich multi-phase inclusions (Ca,Ba-, Ca,Sr-, Ca,Fe-carbonates + Ti-silicate + Ba-apatite + fluid bubbles). High-density fluids also contain K. Volatiles in the fluid bubbles are represented by water, Cl, F, S, CO2, CH4, and heavy hydrocarbons. Origin of the second group of HDFs may be related to the non

  7. Evolution of the Mobile Information SysTem (MIST)

    NASA Technical Reports Server (NTRS)

    Litaker, Harry L., Jr.; Thompson, Shelby; Archer, Ronald D.

    2008-01-01

    The Mobile Information SysTem (MIST) had its origins in the need to determine whether commercial off the shelf (COTS) technologies could improve intervehicular activities (IVA) on International Space Station (ISS) crew maintenance productivity. It began with an exploration of head mounted displays (HMDs), but quickly evolved to include voice recognition, mobile personal computing, and data collection. The unique characteristic of the MIST lies within its mobility, in which a vest is worn that contains a mini-computer and supporting equipment, and a headband with attachments for a HMD, lipstick camera, and microphone. Data is then captured directly by the computer running Morae(TM) or similar software for analysis. To date, the MIST system has been tested in numerous environments such as two parabolic flights on NASA's C-9 microgravity aircraft and several mockup facilities ranging from ISS to the Altair Lunar Sortie Lander. Functional capabilities have included its lightweight and compact design, commonality across systems and environments, and usefulness in remote collaboration. Human Factors evaluations of the system have proven the MIST's ability to be worn for long durations of time (approximately four continuous hours) with no adverse physical deficits, moderate operator compensation, and low workload being reported as measured by Corlett Bishop Discomfort Scale, Cooper-Harper Ratings, and the NASA Total Workload Index (TLX), respectively. Additionally, through development of the system, it has spawned several new applications useful in research. For example, by only employing the lipstick camera, microphone, and a compact digital video recorder (DVR), we created a portable, lightweight data collection device. Video is recorded from the participants point of view (POV) through the use of the camera mounted on the side of the head. Both the video and audio is recorded directly into the DVR located on a belt around the waist. This data is then transferred to

  8. The proposed icy mineralogy package (XRD/XRF) for TandEM

    NASA Astrophysics Data System (ADS)

    Fortes, Andrew Dominic; Wood, Ian G.; Dobson, David P.; Fewster, Paul F.; Coustenis, Athena; Lebreton, Jean-Pierre

    Introduction: Understanding the geology of Titan's crust, and its interaction with the atmosphere, requires determination of the chemistry and mineralogy of surface materials which can only be achieved unambiguously using a combination of X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD). Here we describe an icy mineralogy package (IMP) consisting of a miniaturised XRD/XRF instrument designed primarily with Titan (and the TandEM ESA Cosmic Vision proposal [1]) in mind; however, the instrument is not predicated upon an a priori knowledge of surface mineralogy and consequently is applicable with little modification to any solar system body (rocky or icy). The proposed instrument is well suited to integration with other analytical tools, such as IR and UV Raman spectrometers. Instrument design: Two design concepts are currently under study, which differ in the complexity of the sample handling system, and the range of Bragg angles which may be observed. Both are focusing cameras, one (IMP senior) working in transmission, and the other (IMP junior) working in back-reflection. IMP jnr is intended for deployment on a static surface probe with no sample acquisition capability, collecting a single diffraction pattern through a window in the probe's underside. IMP snr is intended for deployment on a balloon with a sample collection arm able to deliver scoops of surface material to a rotating specimen stage. The latter may therefore be used to analyse many samples at geographically dispersed points. In each case we will use X-rays generated by high specific-activity radioisotope sources, 55 Fe and 241 Am. Our paper will present the results of the following activities: (a) compilation of a crystallographic database of materials expected on Titan's surface; (b) simulation of single-phase and polyphase diffraction data to illustrate the ease with which substances may be distinguished (even in complex mixtures); (c) blind tests of peak-matching software against

  9. Application of Mythen detector: In-situ XRD study on the thermal expansion behavior of metal indium

    NASA Astrophysics Data System (ADS)

    Du, Rong; Chen, ZhongJun; Cai, Quan; Fu, JianLong; Gong, Yu; Wu, ZhongHua

    2016-07-01

    A Mythen detector has been equipped at the beamline 4B9A of Beijing Synchrotron Radiation Facility (BSRF), which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction (XRD) full-profiles. In this paper, the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector. The indium was heated from 303 to 433 K with a heating rate of 2 K/min. The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds. Rietveld refinement was used to extract the structural parameters. The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis. The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point (429.65 K). The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature, while the c-axis contracts with a cubic dependency on temperature. By the time-resolved XRD measurements, it was observed that the [200] preferred orientation can maintain to about 403.15 K. While (110) is the last and detectable crystal plane just before melting of the polycrystalline indium foil. This study is not only beneficial to the application of metal indium, but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.

  10. The Lactamase Engineering Database: a critical survey of TEM sequences in public databases

    PubMed Central

    Thai, Quan Ke; Bös, Fabian; Pleiss, Jürgen

    2009-01-01

    Background TEM β-lactamases are the main cause for resistance against β-lactam antibiotics. Sequence information about TEM β-lactamases is mainly found in the NCBI peptide database and TEM mutation table at . While the TEM mutation table is manually curated by experts in the lactamase field, who guarantee reliable and consistent information, the rapidly growing sequence and annotation information from the NCBI peptide database is sometimes inconsistent. Therefore, the Lactamase Engineering Database has been developed to collect the TEM β-lactamase sequences from the NCBI peptide database and the TEM mutation table, systematically compare sequence information and naming, identify inconsistencies, and thus provide a versatile tool for reconciliation of data and for an investigation of the sequence-function relationship. Description The LacED currently provides 2399 sequence entries and 37 structure entries. Sequence information on 150 different TEM β-lactamases was derived from the TEM mutation table which provides a unique number to each protein classified as TEM β-lactamase. 293 TEM-like proteins were found in the NCBI protein database, but only 113 TEM β-lactamase were common to both data sets. The 180 TEM β-lactamases from the NCBI protein database which have not yet been assigned to a TEM number fall in three classes: (1) 89 proteins from microbial organisms and 35 proteins from cloning or expression vectors had a new mutation profile; (2) 55 proteins had inconsistent annotation in terms of TEM assignment or reported mutation profile; (3) 39 proteins are fragments. The LacED is web accessible at and contains multisequence alignments, structure information and reconciled annotation of TEM β-lactamases. The LacED is weekly updated and supplies all data for download. Conclusion The Lactamase Engineering Database enables a systematic analysis of TEM β-lactamase sequence and annotation data from different data sources, and thus provides a valuable tool to

  11. XRD Analysis of Cement Paste Samples Exposed to the Simulated Environment of a Deep Repository - 12239

    SciTech Connect

    Ferreira, Eduardo G.A.; Marumo, Julio T.; Vicente, Roberto; Gobbo, Luciano

    2012-07-01

    Portland cement materials are widely used as engineered barriers in repositories for radioactive waste. The capacity of such barriers to avoid the disposed of radionuclides to entering the biosphere in the long-term depends on the service life of those materials. Thus, the performance assessment of structural materials under a series of environmental conditions prevailing at the environs of repositories is a matter of interest. The durability of cement paste foreseen as backfill in a deep borehole for disposal of disused sealed radioactive sources is investigated in the development of the repository concept. Results are intended to be part of the body of evidence in the safety case of the proposed disposal technology. This paper presents the results of X-Ray Diffraction (XRD) Analysis of cement paste exposed to varying temperatures and simulated groundwater after samples received the radiation dose that the cement paste will accumulate until complete decay of the radioactive sources. The XRD analysis of cement paste samples realized in this work allowed observing some differences in the results of cement paste specimens that were submitted to different treatments. The cluster analysis of results was able to group tested samples according to the applied treatments. Mineralogical differences, however, are tenuous and, apart from ettringite, are hardly observed. The absence of ettringite in all the seven specimens that were kept in dry storage at high temperature had hardly occurred by natural variations in the composition of hydrated cement paste because ettringite is observed in all tested except the seven specimens. Therefore this absence is certainly the result of the treatments and could be explained by the decomposition of ettringite. Although the temperature of decomposition is about 110-120 deg. C, it may be initially decomposed to meta-ettringite, an amorphous compound, above 50 deg. C in the absence of water. Influence of irradiation on the mineralogical

  12. Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane.

    PubMed

    Adebajo, Moses O; Long, Mervyn A; Frost, Ray L

    2004-03-01

    The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination

  13. Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane

    NASA Astrophysics Data System (ADS)

    Adebajo, Moses O.; Long, Mervyn A.; Frost, Ray L.

    2004-03-01

    The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination

  14. Modal mineralogy of CV3 chondrites by X-ray diffraction (PSD-XRD)

    NASA Astrophysics Data System (ADS)

    Howard, K. T.; Benedix, G. K.; Bland, P. A.; Cressey, G.

    2010-09-01

    Using position sensitive detector X-ray diffraction (PSD-XRD) we determine a complete modal mineralogy for all phases present in abundances greater than 1 wt% in Vigarano, Efremovka, Mokoia, Grosnaja, Kaba and Allende. Reduced CV3 samples are comprised of (vol%): olivine (83-85%); enstatite (6.5-8.1%); anorthite (1.1-1.2%); magnetite (1.4-1.8%); sulphide (2.4-5.1%); Fe, Ni metal (2-2.2%). The oxidized samples are comprised of: olivine (76.3-83.9%); enstatite (4.8-7.8%); anorthite (1.1-1.7%); magnetite (0.3-6.1%); sulphide (2.9-8.1%); Fe, Ni metal (0.2-1.1%); Fe-oxide (0-2.7%) and phyllosilicate (1.9-4.2%). When our modal data is used to calculate a bulk chemistry that is compared to literature data a near 1:1 correlation is observed. PSD-XRD data indicates that olivine compositions may span almost the entire Fe-Mg solid solution series in all CV samples and that these contain a component (4-13%) of fine-grained olivine that is more Fe-rich (>Fa 60) than is typically reported. Modal mineralogy shows that there are mineralogic differences between CV3 samples classified as oxidized and reduced but that these sub-classes are most clearly distinguished by the relative abundance of metal and Ni content of sulphide, rather than abundance of magnetite. The most significant difference in modal mineralogy observed is the relative absence of phyllosilicate in reduced CV that essentially escaped aqueous alteration. Fayalite, ferrous olivine and magnetite are typically considered secondary alteration products. The abundances of these minerals overlap in oxidized and reduced samples and correlate positively supporting common conditions of formation in a relatively oxidizing environment. The abundances of fayalite, ferrous olivine and magnetite show no relationship to petrographic type and if these abundances were used as a proxy for alteration, Allende would be the least altered CV - contrary to all previous data. The implication is that thermal metamorphism on the parent body

  15. Data from the Mars Science Laboratory CheMin XRD/XRF instrument

    NASA Astrophysics Data System (ADS)

    Vaniman, David; Bristow, , David Blake, Tom; Des Marais, David; Achilles, Cherie; Spanovich, Ashwin Vasavada, , Robert Anderson, Joy Crisp, John Michael Morookian, Nicole; Yen, Albert; Bish, David; Chipera, Steve; Downs, Robert; Morrison, Shaunna; Farmer, Jack; Grotzinger, John; Stolper, Edward; Morris, , Douglas Ming, Richard; Rampe, Elizabeth; Treiman, Allan; Sarrazin, Philippe; MSL Science Team

    2013-04-01

    The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity uses a Co tube source and a CCD detector to acquire mineralogy from diffracted primary X-rays and chemical information from fluoresced X-rays. CheMin has been operating at the MSL Gale Crater field site since August 5, 2012 and has provided the first X-ray diffraction (XRD) analyses in situ on a body beyond Earth. Data from the first sample collected, the Rocknest eolian soil, identify a basaltic mineral suite, predominantly plagioclase (~An50), forsteritic olivine (~Fo58), augite and pigeonite, consistent with expectation that detrital grains on Mars would reflect widespread basaltic sources. Minor phases (each <2 wt% of the crystalline component) include sanidine, magnetite, quartz, anhydrite, hematite and ilmenite. Significantly, about a third of the sample is amorphous or poorly ordered in XRD. This amorphous component is attested to by a broad rise in background centered at ~27° 2θ (Co Kα) and may include volcanic glass, impact glass, and poorly crystalline phases including iron oxyhydroxides; a rise at lower 2θ may indicate allophane or hisingerite. Constraints from phase chemistry of the crystalline components, compared with a Rocknest bulk composition from the APXS instrument on Curiosity, indicate that in sum the amorphous or poorly crystalline components are relatively Si, Al, Mg-poor and enriched in Ti, Cr, Fe, K, P, S, and Cl. All of the identified crystalline phases are volatile-free; H2O, SO2 and CO2 volatile releases from a split of this sample analyzed by the SAM instrument on Curiosity are associated with the amorphous or poorly ordered materials. The Rocknest eolian soil may be a mixture of local detritus, mostly crystalline, with a regional or global set of dominantly amorphous or poorly ordered components. The Rocknest sample was targeted by MSL for "first time analysis" to demonstrate that a loose deposit could be scooped, sieved to <150 µm, and delivered to

  16. Data from the Mars Science Laboratory CheMin XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Vaniman, David; Blake, David; Bristow, Tom; DesMarais, David; Achilles, Cherie; Anderson, Robert; Crips, Joy; Morookian, John Michael; Spanovich, Nicole; Vasavada, Ashwin; Yen, Albert; Bish, David; Chipera, Steve; Downs, Robert; Morrison, Shaunna; Farmer, Jack; Grotzinger, John; Stolper, Edward; Ming, Douglas; Morris, Richard; Rampe, Elizabeth; Treiman, Allan; Sarrazin, Philippe

    2013-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity uses a Co tube source and a CCD detector to acquire mineralogy from diffracted primary X-rays and chemical information from fluoresced X-rays. CheMin has been operating at the MSL Gale Crater field site since August 5, 2012 and has provided the first X-ray diffraction (XRD) analyses in situ on a body beyond Earth. Data from the first sample collected, the Rocknest eolian soil, identify a basaltic mineral suite, predominantly plagioclase (approx.An50), forsteritic olivine (approx.Fo58), augite and pigeonite, consistent with expectation that detrital grains on Mars would reflect widespread basaltic sources. Minor phases (each <2 wt% of the crystalline component) include sanidine, magnetite, quartz, anhydrite, hematite and ilmenite. Significantly, about a third of the sample is amorphous or poorly ordered in XRD. This amorphous component is attested to by a broad rise in background centered at approx.27deg 2(theta) (Co K(alpha)) and may include volcanic glass, impact glass, and poorly crystalline phases including iron oxyhydroxides; a rise at lower 2(theta) may indicate allophane or hisingerite. Constraints from phase chemistry of the crystalline components, compared with a Rocknest bulk composition from the APXS instrument on Curiosity, indicate that in sum the amorphous or poorly crystalline components are relatively Si, Al, Mg-poor and enriched in Ti, Cr, Fe, K, P, S, and Cl. All of the identified crystalline phases are volatile-free; H2O, SO2 and CO2 volatile releases from a split of this sample analyzed by the SAM instrument on Curiosity are associated with the amorphous or poorly ordered materials. The Rocknest eolian soil may be a mixture of local detritus, mostly crystalline, with a regional or global set of dominantly amorphous or poorly ordered components. The Rocknest sample was targeted by MSL for "first time analysis" to demonstrate that a loose deposit could be scooped, sieved to

  17. XRD monitoring of α self-irradiation in uranium-americium mixed oxides.

    PubMed

    Horlait, Denis; Lebreton, Florent; Roussel, Pascal; Delahaye, Thibaud

    2013-12-16

    The structural evolution under (241)Am self-irradiation of U(1-x)Am(x)O(2±δ) transmutation fuels (with x ≤ 0.5) was studied by X-ray diffraction (XRD). Samples first underwent a preliminary heat treatment performed under a reducing atmosphere (Ar/H2(4%)) aiming to recover the previously accumulated structural defects. Over all measurements (carried out over up to a full year and for integrated doses up to 1.5 × 10(18) α-decay events·g(-1)), only fluorite U(1-x)Am(x)O(2±δ) solid solutions were observed. Within a few days after the end of the heat treatment, each of the five studied samples was slowly oxidized as a consequence of their move to air atmosphere, which is evidenced by XRD by an initial sharp decrease of the unit cell parameter. For the compounds with x ≤ 0.15, this oxidation occurred without any phase transitions, but for U0.6Am0.4O(2±δ) and U0.5Am0.5O(2±δ), this process is accompanied by a transition from a first fluorite solid solution to a second oxidized one, as the latter is thermodynamically stable in ambient conditions. In the meantime and after the oxidation process, (241)Am α self-irradiation caused a structural swelling up to ∼0.8 vol %, independently of the sample composition. The kinetic constants of swelling were also determined by regression of experimental data and are, as expected, dependent on x and thus on the dose rate. The normalization of these kinetic constants by sample α-activity, however, leads to very close swelling rates among the samples. Finally, evolutions of microstrain and crystallite size were also monitored, but for the considered dose rates and cumulated doses, α self-irradiation was found, within the limits of the diffractometer used, to have almost no impact on these characteristics. Microstrain was found to be influenced instead by the americium content in the materials (i.e., by the impurities associated with americium starting material and the increase of cationic charge heterogeneity with

  18. Synchrotron Radiation XRD Analysis of Indialite in Y-82094 Ungrouped Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Hagiya, K.; Sawa, N.; Kimura, M.; Ohsumi, K.; Komatsu, M.; Zolensky, M.

    2016-01-01

    Y-82094 is an ungrouped type 3.2 carbonaceous chondrite, with abundant chondrules making 78 vol.% of the rock. Among these chondrules, an unusual porphyritic Al-rich magnesian chondrule is reported that consists of a cordierite-like phase, Al-rich orthopyroxene, cristobalite, and spinel surrounded by an anorthitic mesostasis. The reported chemical formula of the cordierite-like phase is Na(0.19)Mg(1.95)Fe(0.02)Al(3.66)Si(5.19)O18, which is close to stoichiometric cordierite (Mg2Al3[AlSi5O18]). Although cordierite can be present in Al-rich chondrules, it has a high temperature polymorph (indialite) and it is therefore necessary to determine whether it is cordierite or indialite in order to better constrain its formation conditions. In this abstract we report on our synchrotron radiation X-ray diffraction (SR-XRD) study of the cordierite-like phase in Y-82094.

  19. [Spectroscopic analysis of the crystallization mechanism of synthesized zeolite with XRD and FTIR approaches].

    PubMed

    Fan, Chun-hui; Ma, Hong-rui; Hua, Li

    2012-04-01

    Zeolites were synthesized from fly ash using modified one-stage method. The changes in cation exchange capacity (CEC) and chemical elements of zeolite were investigated during the synthesis process to reveal the materials and elements transformation in solid-liquid system. The approaches of XRD, SEM and FTIR were used to indicate the crystallization characteristics and mechanism. The zeolite NaP1 was synthesized, and the CEC value reached to the maximum of 135 mmol/100g at 24 h. After the hydrothermal reaction for 12 h, the characteristic peak and metastable crystalline structure of zeolite NaP1 appeared, then the hydroxy sodalite products formed at 48 h. The crystallization process was the result of materials transformation: the elements of fly ash released into the liquid system for the melting effect of alkali solution, and the solid system played the role of skeleton in crystallization process, being the "source" and the "sink" of the reaction, respectively, and the achievements presented the crystallization mechanism of liquid-phase and solid-phase transformation.

  20. XRD and XANES study of some Cu-doped MnBi materials

    NASA Astrophysics Data System (ADS)

    Mishra, Ashutosh; Patil, Harsha

    2016-10-01

    High purity MnBi low temperature phase has been prepared and analyzed using X- ray diffraction (XRD) and X-ray absorption near edge structure (XANES) measurements. The X-ray diffraction measurements were carried out using Bruker D8 Advance X-ray diffractometer. The X-rays were produced using a sealed tube and the wavelength of X-ray was 154 nm (Cu K-alpha). and X-rays were detected using a fast counting detector based on Silicon strip technology (Bruker LynxEye detector)[1]. and the X-ray absorption spectra has emerged as a powerful technique for local structure determination, which can be applied to any type of material. The X-ray absorption measurements of two Cu-doped MnBi alloys have been performed at the recently developed BL-8 Dispersive EXAFS beam line at 2.5 GeV Indus-2 synchrotron at RRCAT, Indore, India[2]. The X-ray absorption near edge structure (XANES) data obtained has been processed using data analysis program Athena. The energies of the K absorption edge, chemical shifts, edge-widths, shifts of the principal absorption maximum in the alloys have been determined.

  1. Void-species nanostructure of chalcogenide glasses studied with FSDP-related XRD

    NASA Astrophysics Data System (ADS)

    Kavetskyy, T. S.; Shpotyuk, O. I.; Boyko, V. T.

    2007-05-01

    Void-species nanostructure is studied in glassy arsenic selenide g-As2Se3 and sulphide g-As2S3 using X-ray diffraction in respect to the first sharp diffraction peak (FSDP-related XRD) treated within Elliott's void-based model. It is shown that the previously established analytical relationship between the FSDP position Q1 and nanovoid diameter D in the form of Q1=2.3·π/D seems to be close to ones reported by Gaskell [Medium-range structure in glasses and low-Q structure in neutron and X-ray scattering data, J. Non-Cryst. Solids 351 (2005) 1003 1013] and Rachek [X-ray diffraction study of amorphous alloys Al Ni Ce Sc with using Ehrenfest's formula, J. Non-Cryst. Solids 352 (2006) 3781 3786]. Following to this correlation, it is concluded that internal nanostructural voids in chalcogenide glasses are responsible for low-Q structure observed in X-ray scattering.

  2. Multielemental analyses of isomorphous Indian garnet gemstones by XRD and external pixe techniques.

    PubMed

    Venkateswarulu, P; Srinivasa Rao, K; Kasipathi, C; Ramakrishna, Y

    2012-12-01

    Garnet gemstones were collected from parts of Eastern Ghats geological formations of Andhra Pradesh, India and their gemological studies were carried out. Their study of chemistry is not possible as they represent mixtures of isomorphism nature, and none of the individual specimens indicate independent chemistry. Hence, non-destructive instrumental methodology of external PIXE technique was employed to understand their chemistry and identity. A 3 MeV proton beam was employed to excite the samples. In the present study geochemical characteristics of garnet gemstones were studied by proton induced X-ray emission. Almandine variety of garnet is found to be abundant in the present study by means of their chemical contents. The crystal structure and the lattice parameters were estimated using X-Ray Diffraction studies. The trace and minor elements are estimated using PIXE technique and major compositional elements are confirmed by XRD studies. The technique is found very useful in characterizing the garnet gemstones. The present work, thus establishes usefulness and versatility of the PIXE technique with external beam for research in Geo-scientific methodology.

  3. XRD Technique: A way to disseminate structural changes in iron-based amorphous materials

    SciTech Connect

    Saw, C K; Lian, T; Day, D; Farmer, J

    2007-05-24

    Prevention of corrosion is a vital goal for the Department of Defense when billions of dollars are spent every year. Corrosion resistant materials have applications in all sort of military vehicles, and more importantly in naval vessels and submarines which come in contact with the seawater. It is known that corrosion resistance property can be improved by the used of structurally designed materials in the amorphous state where the atoms are arranged in a non-periodic fashion and specific atoms, tailored to the required properties can be interjected into the matrix for specific application. The XRD techniques reported here is to demonstrate the optimal conditions for characterization of these materials. The samples, which normally contain different compositions of Fe, Cr, B, Mo, Y, Mn, Si and W, are in the form of powders, ribbons and coatings. These results will be compared for the different forms of the sample which appears to correlate to the cooling rate during sample processing. In most cases, the materials are amorphous or amorphous with very small amount of crystallinity. In the ribbon samples for different compositions we observed that the materials are essentially amorphous. In most cases, starting from an amorphous powder sample, the coatings are also observed to be amorphous with a small amount of iron oxide on the surface, probably due to exposure to air.

  4. FTIR spectroscopic, thermal and XRD characterization of hydroxyapatite from new natural sources

    NASA Astrophysics Data System (ADS)

    Shaltout, Abdallah A.; Allam, Moussa A.; Moharram, Mohamed A.

    2011-12-01

    The inorganic constituents of 5 different plants (leaves and stalks) were investigated by using Fourier transformer infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis including thermal gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). These plants are Catha edulis (Khat), basil, mint, green tea and trifolium. The absorption bands of carbonate ions CO 32- was exhibited at 1446 cm -1, and the phosphate ions PO 43- was assigned at 1105 and 1035 cm -1. At high temperatures (600, 700 and 600 °C) further absorption bands of the phosphate ions PO 43- was assigned at the frequencies 572, 617, 962, 1043 and 1110 cm -1 and the vibrational absorption band of the carbonate ions CO 32- was assigned at 871, 1416 and 1461 cm -1. X-ray diffraction and thermal analysis confirm the obtained results of FITR. Results showed that the main inorganic constituents of C. edulis and basil leaves are hydroxyapatite whereas the hydroxyapatite content in the other plant samples is less than that in case of C. edulis and basil plant leaves.

  5. Modeling the PbI2 formation in perovskite solar cells using XRD/XPS patterns

    NASA Astrophysics Data System (ADS)

    Sohrabpoor, Hamed; Elyasi, Majid; Aldosari, Marouf; Gorji, Nima E.

    2016-09-01

    The impact of prolonged irradiation and air humidity on the stability of perovskite solar cells is modeled using X-ray diffraction and X-ray photoelectron spectroscopy patterns reported in the literature. Light or air-moisture causes the formation of a thin PbI2 or oxide defective layers (in nanoscale) at the interface of perovskite/hole-transport-layer or at the junction with metallic back contact. This thin layer blocks the carrier transport/passivation at the interfaces and cause degradation of device parameters. Variation in thickness of defective layers, changes the XRD and XPS peaks. This allows detection and estimation of the type, crystallinity and thickness of the defective layer. A simple model is developed here to extract the thickness of such thin defective layers formed in nanometer scale at the back region of several perovskite devices. Based on this information, corrected energy band diagram of every device before and after degradation/aging is drawn and discussed in order to obtain insight into the carrier transport and charge collection at the barrier region. In addition, graphene contacted perovskite devices are investigated showing that honey-comb network of graphene contact reduces the effect of aging leading to formation of a thinner defective layer at the perovskite surface compared to perovskite devices with conventional inorganic contacts i.e. Au, Al.

  6. Spectral, XRD, SEM and biological activities of transition metal complexes of polydentate ligands containing thiazole moiety

    NASA Astrophysics Data System (ADS)

    Neelakantan, M. A.; Marriappan, S. S.; Dharmaraja, J.; Jeyakumar, T.; Muthukumaran, K.

    2008-11-01

    Metal complexes of o-vanillidene-2-aminobenzothiazole have been prepared and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as magnetic susceptibility measurements and thermo gravimetric analysis (TG/DTA). The low molar conductance values reveal the non-electrolytic nature of these complexes. The elemental analysis suggests that the stoichiometry to be 1:2 (metal:ligand). Magnetic susceptibility data coupled with electronic spectra suggest that two ligands coordinate to each metal atom by phenolic oxygen and imino nitrogen to form high spin octahedral complex with Co(II), Mn(II) and Ni(II). The fifth and sixth position of metal ion is satisfied with water molecules. The thermal behaviour (TG/DTA) of the synthesised complexes shows that the complexes loss water molecules in the first step followed by decomposition of the ligand. Spin Hamiltonian parameters predict a distorted tetrahedral geometry for the copper complex. XRD and SEM analysis provide the crystalline nature and the morphology of the metal complexes. The in vitro biological activity of the metal chelates is tested against the Gram positive bacteria ( Bacillus amyloliquifacians) and gram negative bacteria ( Pseudomonas species), fungus ( Aspergillus niger) and yeast ( Sacchromyces cereviaceae). Most of the metal chelates exhibited higher biological activities.

  7. XRD, Electron Microscopy and Vibrational Spectroscopy Characterization of Simulated SB6 HLW Glasses - 13028

    SciTech Connect

    Stefanovsky, S.V.; Nikonov, B.S.; Omelianenko, B.I.; Choi, A.; Marra, J.C.

    2013-07-01

    Sample glasses have been made using SB6 high level waste (HLW) simulant (high in both Al and Fe) with 12 different frit compositions at a constant waste loading of 36 wt.%. As follows from X-ray diffraction (XRD) and optical and scanning electron microscopy (SEM) data, all the samples are composed of primarily glass and minor concentration of spinel phases which form both isometric grains and fine cubic (∼1 μm) crystals. Infrared spectroscopy (IR) spectra of all the glasses within the range of 400-1600 cm{sup -1} consist of the bands due to stretching and bending modes in silicon-oxygen, boron-oxygen, aluminum-oxygen and iron-oxygen structural groups. Raman spectra showed that for the spectra of all the glasses within the range of 850-1200 cm{sup -1} the best fit is achieved by suggestion of overlapping of three major components with maxima at 911-936 cm{sup -1}, 988-996 cm{sup -1} and 1020-1045 cm{sup -1}. The structural network is primarily composed of metasilicate chains and rings with embedded AlO{sub 4} and FeO{sub 4} tetrahedra. Major BO{sub 4} tetrahedra and BO{sub 3} triangles form complex borate units and are present as separate constituents. (authors)

  8. A 4-(o-chlorophenyl)-2-aminothiazole: Microwave assisted synthesis, spectral, thermal, XRD and biological studies

    NASA Astrophysics Data System (ADS)

    Rajmane, S. V.; Ubale, V. P.; Lawand, A. S.; Nalawade, A. M.; Karale, N. N.; More, P. G.

    2013-11-01

    A 4-(o-chlorophenyl)-2-aminothiazole (CPAT) has been synthesized by reacting o-chloroacetophenone, iodine and thiourea under microwave irradiation as a green chemistry approach. The reactions proceed selectively and within a couple of minutes giving high yields of the products. The compound was characterized by elemental, spectral (UV-visible, IR, NMR and GC-MS), XRD and thermal analyses. The TG curve of the compound was analyzed to calculate various kinetic parameters (n, E, Z, ΔS and ΔG) by using Coats-Redfern (C.R.), MacCallum-Tanner (M.T.) and Horowitz-Metzger (H.M.) method. The compound was tested for the evaluation of antibacterial activity against B. subtilis and E. coli and antifungal activity against A. niger and C. albicans. The compound was evaluated for their in vitro nematicidal activity on plant parasitic nematode Meloidogyne javanica and molluscicidal activity on fresh water helminthiasis vector snail Lymnea auricularia. The compound is biologically active in very low concentration. X-ray diffraction study suggests a triclinic crystal system for the compound.

  9. Retrofit implementation of Zernike phase plate imaging for cryo-TEM

    PubMed Central

    Marko, Michael; Leith, ArDean; Hsieh, Chyongere; Danev, Radostin

    2011-01-01

    In-focus phase-plate imaging is particularly beneficial for cryo-TEM because it offers a substantial overall increase in image contrast, without an electron dose penalty, and it simplifies image interpretation. We show how phase-plate cryo-TEM can be implemented with an appropriate existing TEM, and provide a basic practical introduction to use of thin-film (carbon) phase plates. We point out potential pitfalls of phase-plate operation, and discuss solutions. We provide information on evaluating a particular TEM for its suitability. PMID:21272647

  10. OSCE vs. TEM: Different Approaches to Assess Clinical Skills of Nursing Students

    PubMed Central

    Jelly, Prasuna; Sharma, Rakesh

    2017-01-01

    Introduction: Nurses are trained with specific clinical skills, and objective structured clinical examination (OSCE) could be a better approach to assess clinical skills of nursing students. Materials and Methods: A comparative study was conducted by observational checklist regarding antenatal care and opinionnaire on the usefulness of OSCE and tradition evaluation method (TEM) was used to assess the clinical skills and to get opinion. Results: The mean score of OSCE was more than TEM and the difference was statistically significant (P < 0.001). The opinion of students regarding the usefulness of OSCE was higher than TEM. Conclusions: The study concluded that implementing OSCE will overweigh the advantages of the TEM.

  11. Evaluation of Rock Powdering Methods to Obtain Fine-grained Samples for CHEMIN, a Combined XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Chipera, S. J.; Vaniman, D. T.; Bish, D. L.; Sarrazin, P.; Feldman, S.; Blake, D. F.; Bearman, G.; Bar-Cohen, Y.

    2004-01-01

    A miniature XRD/XRF (X-ray diffraction / X-ray fluorescence) instrument, CHEMIN, is currently being developed for definitive mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed to enable remote XRD analysis is how best to obtain a representative sample powder for analysis. For powder XRD analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a two-dimensional detector as used in the CHEMIN instrument will produce good results even with poorly prepared powder, the quality of the data will improve and the time required for data collection will be reduced if the sample is fine-grained and randomly oriented. A variety of methods have been proposed for XRD sample preparation. Chipera et al. presented grain size distributions and XRD results from powders generated with an Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL. The USDC was shown to be an effective instrument for sampling rock to produce powder suitable for XRD. In this paper, we compare powder prepared using the USDC with powder obtained with a miniaturized rock crusher developed at JPL and with powder obtained with a rotary tungsten carbide bit to powders obtained from a laboratory bench-scale Retsch mill (provides benchmark mineralogical data). These comparisons will allow assessment of the suitability of these methods for analysis by an XRD/XRF instrument such as CHEMIN.

  12. Spectral studies on a series of metal ion complexes derived from pyrimidine nucleus, TEM, biological and γ-irradiation effect

    NASA Astrophysics Data System (ADS)

    Al-Ashqer, Sawsan; Abou-Melha, Khlood S.; Al-Hazmi, G. A. A.; Saad, Fawaz A.; El-Metwaly, Nashwa M.

    2014-11-01

    A series of thiouracil complexes was prepared, all the prepared compounds are investigated by all possible tools. The ligand coordinates towards two central atoms as a neutral hexadentate mode. The octahedral structure was proposed with Ni(II), Pt(IV) and UO2(II) complexes. Square-pyramidal and square planar with VO(II) and Pd(II) complexes, respectively. VO(II) complex was irradiated by using Gamma radiation to through a light on the probability of geometry changes with the effect of radiation. The parameters calculated from ESR spectra before and after γ-irradiation reflect the rigidity of the complex towards the effect. Such may discuss the unaffected biological behavior before and after irradiation. XRD patterns were carried out to emphasis on the nature of the particles and the purity of products. The ligand, Pt(IV) and Pd(II) are found in nanometer range. TEM is a sensitive tool used to justify on the microstructure and surface morphology. All the investigated compounds are in nanorange. TG curves reflect a lower thermal stability of all investigated complexes due to the presence of water of crystallization. Finally, a toxic effect was observed with all investigated complexes towards Gram positive bacterium as well as a resistant behavior was observed with Gram negative bacteria.

  13. Transient Measurements Under Simulated Mantle Conditions - Simultaneous DTF-Ultrasonic Interferometry, X-Radiography, XRD

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Schilling, F. R.; Lathe, C.; Wunder, B.

    2004-12-01

    The interpretation of seismic data from the Earth's deep interior requires measurements of the physical properties of Earth materials under experimental simulated mantle conditions. Elastic wave velocity measurement by ultrasonic interferometry is an important tool for the determination of the elastic properties in multi-anvil devices. Whereas the classical sweep method is very time-consuming, the ultrasonic data transfer function technique (DTF), simultaneously generating all the frequencies used in the experiment, first described by Li et al. (2002), requires just few seconds to save the response of the system. The success of the technique substantially depends on the excitation function and the resolution used for saving the DTF (Mueller et al., 2004a). Background discussion as well as high pressure AƒA_A,A¿A,A 1/2 high temperature results demonstrate how to optimize the technique. All Ultrasonic interferometry allows highly precise travel time measurement at a sample enclosed in a high-pressure multi-anvil device. But under high pressure conditions the influence of sample deformation on the frequencies for destructive and constructive interference used for the evaluation of the elastic properties might be stronger than that from the shift of the elastic moduli. Consequently ultrasonic interferometry requires the exact sample length measurement under in situ conditions. X-ray imaging using brillant synchrotron radiation, called X-radiography, produces grey-scale images of the sample under in situ conditions by converting the X-ray image to an optical one by a CE-YAG-crystal. Saving the optical image by a CCD-camera after redirection by a mirrow, also requires few seconds. To derive the sample length, the different brightness of sample, buffer rod and reflector at the electronic image is evaluated (Mueller et al., 2004b). Contrary to XRD measurements, imaging the sample by X-rays requires a beam diameter larger than the sample length. Therefore the fixed

  14. Annealing dynamics of WO{sub 3} by in situ XRD

    SciTech Connect

    Righettoni, Marco; Pratsinis, Sotiris E.

    2014-11-15

    Highlights: • Flame-made WO{sub 3} nanoparticles with closely controlled crystal and grain size. • Dynamic phase transition of annealing of pure and Si-doped WO{sub 3} by in situ XRD. • Irreversible evolution of WO{sub 3} crystallinity by heating/cooling during its annealing. • Si-doping alters the WO{sub 3} crystallinity dynamics and stabilizes nanosized WO{sub 3}. • Flame-made nano-WO{sub 3} can sense NO at the ppb level. - Abstract: Tungsten trioxide is a semiconductor with distinct applications in gas sensors, catalysis, batteries and pigments. As such the transition between its different crystal structures during its annealing are of interest, especially for sensor applications. Here, WO{sub 3} nanoparticles with closely controlled crystal and grain size (9–15 nm) and phase composition are made by flame spray pyrolysis and the formation of different WO{sub 3} phases during annealing is investigated. Most notably, the dynamic phase transition and crystal size evolution of WO{sub 3} during heating and cooling is monitored by in situ X-ray diffraction revealing how metastable WO{sub 3} phases can be captured stably. The effect of Si-doping is studied since it is used in practise to control crystal growth and phase transition during metal oxide synthesis and processing. Finally the influence of annealing on the WO{sub 3} sensing performance of NO, a lung inflammation tracer in the human breath, is explored at the ppb-level.

  15. Replica extraction method on nanostructured gold coatings and orientation determination combining SEM and TEM techniques.

    PubMed

    Bocker, Christian; Kracker, Michael; Rüssel, Christian

    2014-12-01

    In the field of electron microscopy the replica technique is known as an indirect method and also as an extraction method that is usually applied on metallurgical samples. This contribution describes a fast and simple transmission electron microscopic (TEM) sample preparation by complete removal of nanoparticles from a substrate surface that allows the study of growth mechanisms of nanostructured coatings. The comparison and combination of advanced diffraction techniques in the TEM and scanning electron microscopy (SEM) provide possibilities for operators with access to both facilities. The analysis of TEM-derived diffraction patterns (convergent beam electron diffraction) in the SEM/electron backscatter diffraction software simplifies the application, especially when the patterns are not aligned along a distinct zone axis. The study of the TEM sample directly by SEM and transmission Kikuchi diffraction allows cross-correlation with the TEM results.

  16. Ceftazidime and aztreonam resistance in Providencia stuartii: characterization of a natural TEM-derived extended-spectrum beta-lactamase, TEM-60.

    PubMed

    Franceschini, N; Perilli, M; Segatore, B; Setacci, D; Amicosante, G; Mazzariol, A; Cornaglia, G

    1998-06-01

    A plasmid-encoded beta-lactamase produced from a clinical strain of Providencia stuartii has been purified and characterized. The gene coding for the beta-lactamase was cloned and sequenced. It appears to be a new natural TEM-derived enzyme, named TEM-60. Point mutations (Q39K, L51P, E104K, and R164S) are present with respect to the TEM-1 enzyme; the mutation L51P has never been previously reported, with the exception of the chromosomally encoded extended-spectrum beta-lactamase PER-1. Kinetic parameters relative to penicillins, cephalosporins, and monobactams other than mechanism-based inactivators were related to the in vitro susceptibility phenotype.

  17. Interaction of selenite with reduced Fe and/or S species: An XRD and XAS study.

    PubMed

    Finck, Nicolas; Dardenne, Kathy

    2016-05-01

    In this study, we investigated the interaction between selenite and either Fe((II))aq or S((-II))aq in solution, and the results were used to investigate the interaction between Se((IV))aq and FeS in suspension. The reaction products were characterized by a combination of methods (SEM, XRD and XAS) and the reaction mechanisms were identified. In a first experiment, Se((IV))aq was reduced to Se((0)) by interaction with Fe((II))aq which was oxidized to Fe((III)), but the reaction was only partial. Subsequently, some Fe((III)) produced akaganeite (β-FeOOH) and the release of proton during that reaction decreased the pH. The pH decrease changed the Se speciation in solution which hindered further Se((IV)) reduction by Fe((II))aq. In a second experiment, Se((IV))aq was quantitatively reduced to Se((0)) by S((-II))aq and the reaction was fast. Two sulfide species were needed to reduce one Se((IV)), and the observed pH increase was due to a proton consumption. For both experiments, experimental results are consistent with expectations based on the oxidation reduction potential of the various species. Upon interaction with FeS, Se((IV))aq was reduced to Se((0)) and minute amounts of pyrite were detected, a consequence of partial mackinawite oxidation at surface sulfur sites. These results are of prime importance with respect to safe deep disposal of nuclear waste which contains the long-lived radionuclide (79)Se. This study shows that after release of (79)Se((IV)) upon nuclear waste matrix corrosion, selenite can be reduced in the near field to low soluble Se((0)) by interaction with Fe((II))aq and/or S((-II))aq species. Because the solubility of Se((0)) species is significantly lower than that of Se((IV)), selenium will become much less (bio)available and its migration out of deep HLW repositories may be drastically hindered.

  18. FT-IR and XRD analysis of natural Na-bentonite and Cu(II)-loaded Na-bentonite.

    PubMed

    Zhirong, Liu; Azhar Uddin, Md; Zhanxue, Sun

    2011-09-01

    Na-bentonite has been studied extensively because of its strong adsorption capacity and complexation ability. In this work, surface area, total pore volume, mean pore diameter, TG, DTA, FT-IR and XRD were carried out in order to reveal the characteristics of natural Na-bentonite. XRD and FT-IR of natural Na-bentonite (China) and Cu-loaded Na-bentonite as a function of Na-bentonite dosage and temperature using batch technique were characterized in detail, respectively.

  19. FT-IR and XRD analysis of natural Na-bentonite and Cu(II)-loaded Na-bentonite

    NASA Astrophysics Data System (ADS)

    Zhirong, Liu; Azhar Uddin, Md.; Zhanxue, Sun

    2011-09-01

    Na-bentonite has been studied extensively because of its strong adsorption capacity and complexation ability. In this work, surface area, total pore volume, mean pore diameter, TG, DTA, FT-IR and XRD were carried out in order to reveal the characteristics of natural Na-bentonite. XRD and FT-IR of natural Na-bentonite (China) and Cu-loaded Na-bentonite as a function of Na-bentonite dosage and temperature using batch technique were characterized in detail, respectively.

  20. The analysis on IP signals in TEM response based on SVD

    NASA Astrophysics Data System (ADS)

    Yu, Chuan-Tao; Liu, Hong-Fu; Zhang, Xin-Jun; Yang, De-Yi; Li, Zi-Hong

    2013-03-01

    During transient electromagnetic method (TEM) exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon (a voltage change from positive to negative) caused by the influence of the induced polarization (IP) effect, which affects the depth and precision of the TEM detection. The conventional inversion method is inefficient because it is difficult to process the data. In this paper, the Cole-Cole model is adopted to analyze the effect of Dc resistivity, chargeability, time constant, and frequency exponent on the TEM response in an homogeneous half space model. Singular Value Decomposition (SVD) is used to invert the measured TEM data, and the Dc resistivity, chargeability, time constant and frequency exponent were extracted from the measured TEM data in the mine area. The extracted parameters are used for interpreting the detection result as a supplement. This reveals why the TEM data acquired in the area has a low resolution. It was found that the DC resistivity and time constant do not significantly change the results, however, the chargeability and frequency exponent have a significant effect. Because of these influences, the SVD method is more accurate than the conventional method in the apparent resistivity profile. The area of the copper mine is confined accurately based on the SVD inverted data. The conclusion has been verified by drill and is identical to the practical geological situation.

  1. TEM00 mode Nd:YAG solar laser by side-pumping a grooved rod

    NASA Astrophysics Data System (ADS)

    Vistas, Cláudia R.; Liang, Dawei; Almeida, Joana; Guillot, Emmanuel

    2016-05-01

    A simple TEM00 mode solar laser system with a grooved Nd:YAG rod pumped through a heliostat-parabolic mirror system is reported here. The radiation coupling capacity of a fused silica tube lens was combined with the multipass pumping ability of a 2 V-shaped cavity to provide efficient side-pumping along a 4.0 mm diameter grooved Nd:YAG single-crystal rod. TEM00 mode solar laser power of 3.4 W was measured by adopting an asymmetric large-mode laser resonant cavity. Record TEM00 mode solar laser collection efficiency of 3.4 W/m2and slope efficiency of 1.9% was achieved, which corresponds to 1.8 and 2.4 times more than the previous TEM00 mode Nd:YAG solar laser using the PROMES-CNRS heliostat-parabolic mirror system, respectively.

  2. Preparation of GaN-based cross-sectional TEM specimens by laser lift-off.

    PubMed

    Zilan, Li; Xiaodong, Hu; Ke, Chen; Ruijuan, Nie; Xuhui, Luo; Xiaoping, Zhang; Tongjun, Yu; Bei, Zhang; Song, Chen; Zhijian, Yang; Zhizhong, Chen; Guoyi, Zhang

    2005-01-01

    Laser lift-off (LLO) technology is successfully used to prepare GaN-based TEM cross-sectional specimens. Detailed procedures of the method to prepare the specimens are demonstrated. Large thin areas suitable for TEM analysis were obtained. TEM images of the resulting GaN interface are studied, and the changes in structural quality are confined to approximately the first 250 nm of the epilayer. Clear TEM images of the whole epilayer and the InGaN quantum wells and the HRTEM images of the superlattice layer are demonstrated, showing that LLO is a quick and ideal method to study the crystal structure of the epilayer, especially if only the upper layers are of interest.

  3. Genomic sequence of temperate phage TEM126 isolated from wild type S. aureus.

    PubMed

    Lee, Young-Duck; Chang, Hyo-Ihl; Park, Jong-Hyun

    2011-04-01

    Bacteriophage TEM126, a newly isolated temperate phage from a mitomycin-C-induced lysate of wild-type Staphylococcus aureus isolated from food, has an isometric head, a noncontractile tail, and a double-stranded DNA genome with a length of 33,540 bp and a G+C content of 33.94%. Bioinformatics analysis of the phage genome revealed 44 putative open reading frames (ORFs). Predicted protein products of the ORFs were determined and described. Temperate phage TEM126 can be classified as a member of the family Siphoviridae by morphology and genome structure. Temperate phage TEM126 showed 84% similarity with Staphylococcus phage phiNM1. To our knowledge, this is the first report of genomic sequencing and characterization of temperate phage TEM126 from a wild-type S. aureus isolated from foods in Korea.

  4. TEM Study of Alteration Assemblages in the Nakhlites: Variation with Burial Depth on Mars

    NASA Astrophysics Data System (ADS)

    Changela, H. C.; Bridges, J. C.

    2009-03-01

    TEM study of nakhlites shows a variation in secondary minerals between different meteorites. Lafayette from the greatest depth on Mars shows coarse crystalline Ca-Mn-Mg siderite and phyllosilicate whereas Y-000593 veins are amorphous silicate gel.

  5. Development of 124I-Immuno-PET Targeting Tumor Vascular TEM1/Endosialin

    PubMed Central

    Nayak, Madhura; Mikitsh, John L.; Hu, Jia; Hou, Catherine; Grasso, Luigi; Nicolaides, Nicholas C.; Muzykantov, Vladimir R.; Divgi, Chaitanya R.; Coukos, George

    2014-01-01

    Tumor endothelial marker 1 (TEM1/endosialin) is a tumor vascular marker highly overexpressed in multiple human cancers with minimal expression in normal adult tissue. In this study, we report the preparation and evaluation of 124I-MORAb-004, a 124I-labeled humanized monoclonal antibody targeting an extracellular epitope of human TEM1 (hTEM1), for its ability to specifically and sensitively detect vascular cells expressing hTEM1 in vivo. Methods MAb MORAb-004 was directly iodinated with 125I and 124I, and in vitro binding and internalization parameters were characterized. The in vivo behavior of radioiodinated-MORAb-004 was characterized in mice bearing subcutaneous ID8 tumors enriched with mouse endothelial cells expressing hTEM1, or control tumors, by biodistribution studies and small animal immuno-PET studies. Results MORAb-004 was radiolabeled with high efficiency and isolated in high purity. In vitro studies demonstrated specific and sensitive binding of MORAb-004 to MS1 mouse endothelial cells expressing hTEM1, with no binding to control MS1 cells. 125I-MORAb-004 and 124I MORAb-004 both had an immunoreactivity of approximately 90%. In vivo biodistribution experiments revealed rapid, highly specific and sensitive uptake of MORAb-004 in MS1-TEM1 tumors at 4 h (153.2 ± 22.2 percent of injected dose per gram [%ID/g]), 24 h (127.1 ± 42.9 %ID/g), 48 h (130.3 ± 32.4 %ID/g), 72 h (160.9 ± 32.1 %ID/g), and 6 d (10.7 ± 1.8 %ID/g). Excellent image contrast was observed with 124I-immuno-PET. MORAb-004 uptake was statistically higher in TEM1-positive tumors versus control tumors, as measured by biodistribution and immuno-PET studies. Binding specificity was confirmed by blocking studies using excess nonlabeled MORAb-004. Conclusion In our preclinical model, with hTEM1 exclusively expressed on engineered murine endothelial cells that integrate into the tumor vasculature, 124I-MORAb-004 displays high tumor–to–background tissue contrast fordetection of hTEM1 in

  6. The role of Poisson's binomial distribution in the analysis of TEM images.

    PubMed

    Tejada, Arturo; den Dekker, Arnold J

    2011-11-01

    Frank's observation that a TEM bright-field image acquired under non-stationary conditions can be modeled by the time integral of the standard TEM image model [J. Frank, Nachweis von objektbewegungen im lichtoptis- chen diffraktogramm von elektronenmikroskopischen auf- nahmen, Optik 30 (2) (1969) 171-180.] is re-derived here using counting statistics based on Poisson's binomial distribution. The approach yields a statistical image model that is suitable for image analysis and simulation.

  7. Applications of the FIB lift-out technique for TEM specimen preparation.

    PubMed

    Giannuzzi, L A; Drown, J L; Brown, S R; Irwin, R B; Stevie, F A

    1998-05-15

    A site-specific technique for cross-section transmission electron microscopy specimen preparation of difficult materials is presented. A focused ion beam was used to slice an electron transparent membrane from a specific area of interest within a bulk sample. Micromanipulation lift-out procedures were then used to transport the electron-transparent specimen to a carbon-coated copper grid for subsequent TEM analysis. The FIB (focused ion beam) lift-out technique is a fast method for the preparation of site-specific TEM specimens. The versatility of this technique is demonstrated by presenting cross-sectioned TEM specimens from several types of materials systems, including a multi-layered integrated circuit on a Si substrate, a galvanized steel, a polycrystalline SiC ceramic fiber, and a ZnSe optical ceramic. These specimens have both complex surface geometry and interfaces with complex chemistry. FIB milling was performed sequentially through different layers of cross-sectioned materials so that preferential sputtering was not a factor in preparing TEM specimens. The FIB lift-out method for TEM analysis is a useful technique for the study of complex materials systems for TEM analysis.

  8. Joint use of TEM and MRS methods in a complex geological setting

    NASA Astrophysics Data System (ADS)

    Legchenko, Anatoly; Ezersky, Michael; Camerlynck, Christian; Al-Zoubi, Abdallah; Chalikakis, Konstantinos

    2009-10-01

    Transient Electromagnetic (TEM), known also as Time Domain Electromagnetic (TDEM) and Magnetic Resonance Sounding (MRS) methods were applied jointly to investigate variations in lithology and groundwater salinity in the Nahal Hever South area (Dead Sea coast of Israel). The subsurface in this area is highly heterogeneous and composed of intercalated sand and clay layers over a salt formation, which is partly karstified. Groundwater is very saline, with a chloride concentration of 100-225 g/l. TEM is known as an efficient tool for investigating electrically conductive targets like saline water, but it is sensitive to both the salinity of groundwater and the porosity of rocks. MRS, however, is sensitive primarily to groundwater volume, but it also allows delineating of lithological variations in water-saturated formations. MRS is much less sensitive to variations in groundwater salinity in comparison with TEM. We show that MRS enables us to resolve the fundamental uncertainty in TEM interpretation caused by the equivalence between groundwater resistivity and lithology. Combining TEM and MRS, we found that the sandy Dead Sea aquifer filled with Dead Sea brine is characterized by a bulk resistivity of ρx > 0.4 Ωm, whereas zones with silt and clay in the subsurface are characterized by a bulk resistivity of ρx < 0.4 Ωm. These observations are confirmed by calibration of the TEM method performed near 18 boreholes.

  9. Identification of TEM-135 β-Lactamase in Neisseria gonorrhoeae Strains Carrying African and Toronto Plasmids in Argentina

    PubMed Central

    Gianecini, R.; Oviedo, C.; Littvik, A.; Mendez, E.; Piccoli, L.; Montibello, S.

    2014-01-01

    One hundred forty-three penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates obtained in Argentina from 2008 and 2012 were examined to detect blaTEM-135 genes and to investigate plasmid profiles and multiantigen sequence types. Forty-two PPNG isolates were found to carry TEM-135, and two contained a new TEM derivative characterized as TEM-220. The blaTEM-135 allele was carried by the Toronto/Rio and African plasmids. Molecular epidemiology revealed that two blaTEM-135 isolates were related to previously described isolates from Thailand and China, indicating a common evolutionary origin. PMID:25367903

  10. Identification of TEM-135 β-lactamase in Neisseria gonorrhoeae strains carrying African and Toronto plasmids in Argentina.

    PubMed

    Gianecini, R; Oviedo, C; Littvik, A; Mendez, E; Piccoli, L; Montibello, S; Galarza, P

    2015-01-01

    One hundred forty-three penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates obtained in Argentina from 2008 and 2012 were examined to detect blaTEM-135 genes and to investigate plasmid profiles and multiantigen sequence types. Forty-two PPNG isolates were found to carry TEM-135, and two contained a new TEM derivative characterized as TEM-220. The blaTEM-135 allele was carried by the Toronto/Rio and African plasmids. Molecular epidemiology revealed that two blaTEM-135 isolates were related to previously described isolates from Thailand and China, indicating a common evolutionary origin.

  11. Improvement of microtome cutting process of carbon nanotube composite sample preparation for TEM analysis

    NASA Astrophysics Data System (ADS)

    Trayner, Sarah

    As research progresses towards nanoscale materials, there has become a need for a more efficient and effective way to obtain ultra-thin samples for imaging under transmission electron microscope (TEM) for atomic resolution analysis. There are various methods used to obtain thin samples (<50 nm in thickness). However, most of the resultant TEM images of soft materials, such as CNT/epoxy composites, are of poor quality due to the sample cutting difficulties. Such poor quality samples are characterized by uneven sample thicknesses, objective overlapping, overall darkness due to large thickness, and defects such as cutting scratches. This research is a continuous effort to study and improve the ultra-microtome cutting technique to provide an effective and reliable approach of obtaining an ultra-thin (25-50 nm) cross section of a CNT/polymer composite for high resolution TEM analysis. Improvements were achieved by studying the relationships between the chosen cutting parameters, sample characteristics and TEM image quality. From this information, a cutting protocol was established so that ultra-thin sample slices can be achieved by different microtome operators for high resolution TEM analysis. In addition, a custom tool was created to aid in the sample collection process. In this research, three composite samples were studied for both microtome cutting and TEM analysis: 1) Unidirectional (UD) IM7/BMI composite; 2) Single-layer CNT buckypaper (BP)/epoxy nanocomposite; 3) 3-layer CNT BP/BMI nanocomposite. The resultant TEM images revealed a clear microstructure consisting of amorphous resin and graphite crystalline packing. UD IM7/BMI composite TEM results did not reveal an interfacial region resulting in a need for even thinner sliced cross sections. TEM results for the single-layer CNT BP/epoxy nanocomposite revealed the alignment direction of the nanotubes and numerous stacks of CNT bundles. In addition, there was visible flattening of CNT packing into dumbbell shapes

  12. Some critical aspects of FT-IR, TGA, powder XRD, EDAX and SEM studies of calcium oxalate urinary calculi.

    PubMed

    Joshi, Vimal S; Vasant, Sonal R; Bhatt, J G; Joshi, Mihir J

    2014-06-01

    Urinary calculi constitute one of the oldest afflictions of humans as well as animals, which are occurring globally. The calculi vary in shape, size and composition, which influence their clinical course. They are usually of the mixed-type with varying percentages of the ingredients. In medical management of urinary calculi, either the nature of calculi is to be known or the exact composition of calculi is required. In the present study, two selected calculi were recovered after surgery from two different patients for detailed examination and investigated by using Fourier-Transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy and energy dispersive analysis of X-rays (EDAX) techniques. The study demonstrated that the nature of urinary calculi and presence of major phase in mixed calculi could be identified by FT-IR, TGA and powder XRD, however, the exact content of various elements could be found by EDAX only.

  13. Petrography, XRD and Wet Chemistry os Sassanid Rock Reliefs at Khan Tahkti (230 a.d.), Iran : A Case Study.

    NASA Astrophysics Data System (ADS)

    Samaniana, Kouros; Shirvanib, Maryam; Bakhshaeia, Hooman

    At Khan Takhti at North West of Iran a sculpted monument commemorating a war waged against the Romans by Shapour I, the second Sassanid king, has been archaeometrically studied. This relief monument carved into the rock in the mountains has faced a considerable destruction process. Petrography, wet chemistry experiments and X-ray diffraction (XRD) analysis were performed to identify rock samples for conservation and preservation purposes. The rock used in this monument is limestone and dolomite. According to XRD analysis, a significant amount of quartz is present in the stone structure. The results of analysis and stone type identification show that a significant quantity of surface sediments and dissolved sulphate, chloride and nitrate salts have been deposited on the surface of the monument due to its proximity to the salty Urmia Lake, which is considered an important factor in the destruction process.

  14. Leonardo da Vinci's drapery studies: characterization of lead white pigments by µ-XRD and 2D scanning XRF

    NASA Astrophysics Data System (ADS)

    Gonzalez, Victor; Calligaro, Thomas; Pichon, Laurent; Wallez, Gilles; Mottin, Bruno

    2015-11-01

    This work focuses on the composition and microstructure of the lead white pigment employed in a set of paintworks, using a combination of µ-XRD and 2D scanning XRF, directly applied on five drapery studies attributed to Leonardo da Vinci (1452-1519) and conserved in the Département des Arts Graphiques, Musée du Louvre and in the Musée des Beaux- Arts de Rennes. Trace elements present in the composition as well as in the lead white highlights were imaged by 2D scanning XRF. Mineral phases were determined in a fully noninvasive way using a special µ-XRD diffractometer. Phase proportions were estimated by Rietveld refinement. The analytical results obtained will contribute to differentiate lead white qualities and to highlight the artist's technique.

  15. An exploratory method to detect tephras from quantitative XRD scans: Examples from Iceland and east Greenland marine sediments

    USGS Publications Warehouse

    Andrews, John T.; Eberl, D.D.; Kristjansdottir, G.B.

    2006-01-01

    Tephras, mainly from Iceland, are becoming increasingly important in interpreting leads and lags in the Holocene climate system across NW Europe. Here we demonstrate that Quantitative Phase Analysis of x-ray diffractograms of the 150 um fraction and identify these same peaks in XRD scans - two of these correlate geochemically and chronologically with Hekla 1104 and 3. At a distal site to the WNW of Iceland, on the East Greenland margin (core MD99-2317), the weight% of volcanic glass reaches values of 11% at about the time of the Saksunarvatn tephra. The XRD method identifies the presence of volcanic glass but not its elemental composition; hence it will assist in focusing attention on specific sections of sediment cores for subsequent geochemical fingerprinting of tephras. ?? 2006 SAGE Publications.

  16. TEM-1-encoding small plasmids impose dissimilar fitness costs on Haemophilus influenzae and Haemophilus parainfluenzae.

    PubMed

    Søndergaard, Annette; Lund, Marianne; Nørskov-Lauritsen, Niels

    2015-12-01

    Only two beta-lactamases, TEM-1 and ROB-1, have been observed in Haemophilus influenzae, while four different TEM but no ROB enzymes have been found in Haemophilus parainfluenzae. In order to investigate the mechanisms behind the dissemination of small beta-lactamase-encoding plasmids in H. influenzae and H. parainfluenzae, we assessed the fitness cost of three TEM-1- (pPN223, pA1209, pA1606), one TEM-15- (pSF3) and one ROB-1-bearing (pB1000) plasmid when expressed in either bacterial species. All plasmids were stable in H. influenzae and H. parainfluenzae except pB1000, which showed on average (sample mean) 76% curing in H. parainfluenzae after 5  days of subculture. Competition assays between isogenic strains with and without plasmid showed no competitive disadvantage of pPN223 and pA1606 in H. influenzae, or of pA1209 in H. parainfluenzae. In contrast, pSF3 and pB1000 were associated with significant competitive disadvantages in both species. Some of the competitive disadvantages may be related to differences in plasmid copy number and mRNA expression of the beta-lactamase genes, as revealed by quantitative PCR analysis. In conclusion, plasmids encoding TEM beta-lactamases isolated from H. influenzae and H. parainfluenzae can be stably transferred between species. The fast curing of pB1000 in H. parainfluenzae observed in this study correlates to the fact that ROB-1 has never been reported for this species. TEM-1-encoding plasmids are associated with the lowest level of fitness cost, but different TEM-1 plasmids confer different levels of fitness cost on the two hosts.

  17. In-line TEM sample preparation and wafer return strategy for rapid yield learning

    NASA Astrophysics Data System (ADS)

    Bicaïs-Lépinay, N.; André, F.; Brevers, S.; Guyader, P.; Trouiller, C.; Kwakman, L. F. Tz.; Pokrant, S.; Verkleij, D.; Schampers, R.; Ithier, L.; Sicurani, E.; Wyon, C.

    2006-03-01

    Full wafer dual beam FIB-SEM systems have received a lot of industrial interest in the last years and by now are operational in several 200mm and 300mm fabs. These tools offer a 3D-physical characterization capability of defects and device structures and as such allow for more rapid yield learning and increased process control. Moreover, if SEM resolution is insufficient to reveal defect origin or the necessary process details, it is now also possible to prepare TEM samples using a controlled, easy to learn in-situ process and to efficiently continue the characterization with a high resolution TEM inspection. Thanks to latest hardware developments and the high degree of automation of this TEM sample preparation process, wafers no longer need to be broken and remain essentially free from contamination. Hence, the TEM lamella process can be considered as non-destructive and wafers may continue the fabrication process flow. In this paper we examine the SEM and TEM application capabilities offered by in-line dual beam systems. To qualify the wafer return strategy, the particle contamination generated by the system hardware as well as the process-induced contamination have been investigated. The particle levels measured are fully acceptable to adopt the wafer return strategy. Ga-contamination does exist but is sufficiently low and localized so that the wafer return strategy can be applied safely in the back-end of line process. Yield analysis has confirmed that there is no measurable impact on device yield. Although yet to be proven for the frond-end of line processes, the wafer return strategy has been demonstrated as a valuable one already in the backend of line processes. The as developed non-destructive 3-D SEM-TEM characterization capability does offer value added data that allow to determine the root cause of critical process defects in almost real-time and this for both standard (SEM) and more advanced (TEM) technologies.

  18. Transmission X-ray Diffraction (XRD) Patterns Relevant to the MSL Chemin Amorphous Component: Sulfates And Silicates

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Rampe, E. B.; Graff, T. G.; Archer, P. D., Jr.; Le, L.; Ming, D. W.; Sutter, B.

    2015-01-01

    The Mars Science Laboratory (MSL) CheMin instrument on the Curiosity rover is a transmission X-ray diffractometer (Co-Kalpha radiation source and a approx.5deg to approx.52deg 2theta range) where the analyzed powder samples are constrained to have discrete particle diameters <150 microns by a sieve. To date, diffraction patterns have been obtained for one basaltic soil (Rocknest (RN)) and four drill fines of coherent rock (John Klein (JK), Cumberland (CB), Windjana (WJ), and Confidence Hills (CH)). The CheMin instrument has detected and quantified the abundance of both primary igneous (e.g., feldspar, olivine, and pyroxene) and secondary (e.g., Ca-sulfates, hematite, akaganeite, and Fe-saponite) minerals. The diffraction patterns of all CheMin samples are also characterized by a broad diffraction band centered near 30deg 2theta and by increasing diffraction intensity (scattering continuum) from approx.15deg to approx.5deg, the 2theta minimum. Both the broad band and the scattering continuum are attributed to the presence of an XRD amorphous component. Estimates of amorphous component abundance, based on the XRD data itself and on mass-balance calculations using APXS data crystalline component chemistry derived from XRD data, martian meteorites, and/or stoichiometry [e.g., 6-9], range from approx.20 wt.% to approx.50 wt.% of bulk sample. The APXSbased calculations show that the amorphous component is rich in volatile elements (esp. SO3) and is not simply primary basaltic glass, which was used as a surrogate to model the broad band in the RN CheMin pattern. For RN, the entire volatile inventory (except minor anhydrite) is assigned to the amorphous component because no volatile-bearing crystalline phases were reported within detection limits [2]. For JK and CB, Fesaponite, basanite, and akaganeite are volatile-bearing crystalline components. Here we report transmission XRD patterns for sulfate and silicate phases relevant to interpretation of MSL-CheMin XRD amorphous

  19. Characterizing the Phyllosilicates and Amorphous Phases Found by MSL Using Laboratory XRD and EGA Measurements of Natural and Synthetic Materials

    NASA Technical Reports Server (NTRS)

    Rampe, Elizabeth B.; Morris, Richard V.; Chipera, Steve; Bish, David L.; Bristow, Thomas; Archer, Paul Douglas; Blake, David; Achilles, Cherie; Ming, Douglas W.; Vaniman, David; Crisp, Joy A.; DesMarais, David J.; Downs, Robert; Farmer, Jack D.; Morookian, John Michael; Morrison, Shaunna; Sarrazin, Philippe; Spanovich, Nicole; Treiman, Allan H.; Yen, Albert S.

    2013-01-01

    The Curiosity Rover landed on the Peace Vallis alluvial fan in Gale crater on August 5, 2012. A primary mission science objective is to search for past habitable environments, and, in particular, to assess the role of past water. Identifying the minerals and mineraloids that result from aqueous alteration at Gale crater is essential for understanding past aqueous processes at the MSL landing site and hence for interpreting the site's potential habitability. X-ray diffraction (XRD) data from the CheMin instrument and evolved gas analyses (EGA) from the SAM instrument have helped the MSL science team identify phases that resulted from aqueous processes: phyllosilicates and amorphous phases were measure in two drill samples (John Klein and Cumberland) obtained from the Sheepbed Member, Yellowknife Bay Fm., which is believed to represent a fluvial-lacustrine environment. A third set of analyses was obtained from scoop samples from the Rocknest sand shadow. Chemical data from the APXS instrument have helped constrain the chemical compositions of these secondary phases and suggest that the phyllosilicate component is Mg-enriched and the amorphous component is Fe-enriched, relatively Si-poor, and S- and H-bearing. To refine the phyllosilicate and amorphous components in the samples measured by MSL, we measured XRD and EGA data for a variety of relevant natural terrestrial phyllosilicates and synthetic mineraloids in laboratory testbeds of the CheMin and SAM instruments. Specifically, Mg-saturated smectites and vermiculites were measured with XRD at low relative humidity to understand the behavior of the 001 reflections under Mars-like conditions. Our laboratory XRD measurements suggest that interlayer cation composition affects the hydration state of swelling clays at low RH and, thus, the 001 peak positions. XRD patterns of synthetic amorphous materials, including allophane, ferrihydrite, and hisingerite were used in full-pattern fitting (FULLPAT) models to help

  20. Novel techniques of preparing TEM samples for characterization of irradiation damage.

    PubMed

    Zhang, H K; Long, F; Yao, Z; Daymond, M R

    2013-12-01

    Focus ion beam preparation of transmission electron microscopy (TEM) samples has become increasingly popular due to the relative ease of extraction of TEM foils from specific locations within a larger sample. However the sputtering damage induced by Ga ion bombardment in focus ion beam means that traditional electropolishing may be a preferable method. First, we describe a special electropolishing method for the preparation of irregular TEM samples from ex-service nuclear reactor components, spring-shaped spacers. This method has also been used to prepare samples from a nonirradiated component for a TEM in situ heavy ion irradiation study. Because the specimen size is small (0.7 × 0.7 × 3 mm), a sandwich installation is adopted to obtain high quality polishing. Second, we describe some modifications to a conventional TEM cross-section sample preparation method that employs Ni electroplating. There are limitations to this method when preparing cross-section samples from either (1) metals which are difficult to activate for electroplating, or (2) a heavy ion irradiated foil with a very shallow damage layer close to the surface, which may be affected by the electroplating process. As a consequence, a novel technique for preparing cross-section samples was developed and is described.

  1. TEM Analysis of Interfaces in Diffusion-Bonded Silicon Carbide Ceramics Joined Using Metallic Interlayers

    NASA Technical Reports Server (NTRS)

    Ozaki, T.; Tsuda, H.; Halbig, M. C.; Singh, M.; Hasegawa, Y.; Mori, S.; Asthana R.

    2016-01-01

    Silicon Carbide (SiC) is a promising material for thermo-structural applications due to its excellent high-temperature mechanical properties, oxidation resistance, and thermal stability. However, joining and integration technologies are indispensable for this material in order to fabricate large size and complex shape components with desired functionalities. Although diffusion bonding techniques using metallic interlayers have been commonly utilized to bond various SiC ceramics, detailed microstructural observation by Transmission Electron Microscopy (TEM) of the bonded area has not been carried out due to difficulty in preparing TEM samples. In this study, we tried to prepare TEM samples from joints of diffusion bonded SiC ceramics by Focused Ion Beam (FIB) system and carefully investigated the interfacial microstructure by TEM analysis. The samples used in this study were SiC fiber bonded ceramics (SA-Tyrannohex: SA-THX) diffusion bonded with metallic interlayers such as Ti, TiMo, and Mo-B. In this presentation, the result of microstructural analysis obtained by TEM observations and the influence of metallic interlayers and fiber orientation of SA-THX on the joint microstructure will be discussed.

  2. Structure and Output Characteristics of a TEM Array Fitted to a Fin Heat Exchanger

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Chen, L. N.; Chen, Z. J.; Xiao, G. Q.; Liu, Z. J.

    2015-06-01

    In the design of a thermoelectric generator, both the heat transfer area and the number of thermoelectric modules (TEMs) should be increased accordingly as the generator power increases; crucially, both aspects need to be coordinated. A kilowatt thermoelectric generator with a fin heat exchanger is proposed for use in a constant-speed diesel generator unit. Interior fins enhance convective heat transfer, whereas an exterior fin segment increases the heat transfer area. The heat transfer surface is double that of a plane heat exchanger, and the temperature field over the exterior fins is constrained to a one-dimensional distribution. Between adjoining exterior fins, there is a cooling water channel with trapezoid cross-section, enabling compact TEMs and cooling them. Hence, more TEMs are built as a series-parallel array of TEMs with lower resistance and more stable output current. Under nonuniform conditions, to prevent circulation and energy loss, bypass diodes and antidiodes are added. Experiments and numerical calculations show that, with matching and optimization of the heat exchanger and TEM array, a stable maximum output power is obtainable from the interior of the thermoelectric generator system, which can be connected to an external maximum power point tracking system.

  3. The Tem1 small GTPase controls actomyosin and septin dynamics during cytokinesis.

    PubMed

    Lippincott, J; Shannon, K B; Shou, W; Deshaies, R J; Li, R

    2001-04-01

    Cytokinesis in budding yeast involves an actomyosin-based ring which assembles in a multistepped fashion during the cell cycle and constricts during cytokinesis. In this report, we have investigated the structural and regulatory events that occur at the onset of cytokinesis. The septins, which form an hour-glass like structure during early stages of the cell cycle, undergo dynamic rearrangements prior to cell division: the hourglass structure splits into two separate rings. The contractile ring, localized between the septin double rings, immediately undergoes contraction. Septin ring splitting is independent of actomyosin ring contraction as it still occurs in mutants where contraction fails. We hypothesize that septin ring splitting may remove a structural barrier for actomyosin ring to contract. Because the Tem1 small GTPase (Tem1p) is required for the completion of mitosis, we investigated its role in regulating septin and actomyosin ring dynamics in the background of the net1-1 mutation, which bypasses the anaphase cell cycle arrest in Tem1-deficient cells. We show that Tem1p plays a specific role in cytokinesis in addition to its function in cell cycle progression. Tem1p is not required for the assembly of the actomyosin ring but controls actomyosin and septin dynamics during cytokinesis.

  4. Structural characterization of amphiphilic homopolymer micelles using light scattering, SANS, and cryo-TEM

    PubMed Central

    Patterson, Joseph P.; Kelley, Elizabeth G.; Murphy, Ryan P.; Moughton, Adam O.; Robin, Mathew; Lu, Annhelen; Colombani, Olivier; Chassenieux, Christophe; Cheung, David; Sullivan, Millicent O.

    2013-01-01

    We report the aqueous solution self-assembly of a series of poly(N-isopropylacrylamide) (PNIPAM) polymers end-functionalized with a hydrophobic sulfur-carbon-sulfur (SCS) pincer ligand. Although the hydrophobic ligand accounted for <5 wt% of the overall homopolymer mass, the polymers self-assembled into well-defined spherical micelles in aqueous solution, and these micelles are potential precursors to solution-assembled nanoreactors for small molecule catalysis applications. The micelle structural details were investigated using light scattering, cryogenic transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS). Radial density profiles extracted from the cryo-TEM micrographs suggested that the PNIPAM chains formed a diffuse corona with a radially decreasing corona density profile and provided valuable a priori information about the micelle structure for SANS data modeling. SANS analysis indicated a similar profile in which the corona surrounded a small hydrophobic core containing the pincer ligand. The similarity between the SANS and cryo-TEM results demonstrated that detailed information about the micelle density profile can be obtained directly from cryo-TEM and highlighted the complementary use of scattering and cryo-TEM in the structural characterization of solution-assemblies, such as the SCS pincer-functionalized homopolymers described here. PMID:24058209

  5. Structural characterization of amphiphilic homopolymer micelles using light scattering, SANS, and cryo-TEM.

    PubMed

    Patterson, Joseph P; Kelley, Elizabeth G; Murphy, Ryan P; Moughton, Adam O; Robin, Mathew; Lu, Annhelen; Colombani, Olivier; Chassenieux, Christophe; Cheung, David; Sullivan, Millicent O; Epps, Thomas H; O'Reilly, Rachel K

    2013-08-13

    We report the aqueous solution self-assembly of a series of poly(N-isopropylacrylamide) (PNIPAM) polymers end-functionalized with a hydrophobic sulfur-carbon-sulfur (SCS) pincer ligand. Although the hydrophobic ligand accounted for <5 wt% of the overall homopolymer mass, the polymers self-assembled into well-defined spherical micelles in aqueous solution, and these micelles are potential precursors to solution-assembled nanoreactors for small molecule catalysis applications. The micelle structural details were investigated using light scattering, cryogenic transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS). Radial density profiles extracted from the cryo-TEM micrographs suggested that the PNIPAM chains formed a diffuse corona with a radially decreasing corona density profile and provided valuable a priori information about the micelle structure for SANS data modeling. SANS analysis indicated a similar profile in which the corona surrounded a small hydrophobic core containing the pincer ligand. The similarity between the SANS and cryo-TEM results demonstrated that detailed information about the micelle density profile can be obtained directly from cryo-TEM and highlighted the complementary use of scattering and cryo-TEM in the structural characterization of solution-assemblies, such as the SCS pincer-functionalized homopolymers described here.

  6. Atom-counting in High Resolution Electron Microscopy:TEM or STEM - That's the question.

    PubMed

    Gonnissen, J; De Backer, A; den Dekker, A J; Sijbers, J; Van Aert, S

    2016-10-27

    In this work, a recently developed quantitative approach based on the principles of detection theory is used in order to determine the possibilities and limitations of High Resolution Scanning Transmission Electron Microscopy (HR STEM) and HR TEM for atom-counting. So far, HR STEM has been shown to be an appropriate imaging mode to count the number of atoms in a projected atomic column. Recently, it has been demonstrated that HR TEM, when using negative spherical aberration imaging, is suitable for atom-counting as well. The capabilities of both imaging techniques are investigated and compared using the probability of error as a criterion. It is shown that for the same incoming electron dose, HR STEM outperforms HR TEM under common practice standards, i.e. when the decision is based on the probability function of the peak intensities in HR TEM and of the scattering cross-sections in HR STEM. If the atom-counting decision is based on the joint probability function of the image pixel values, the dependence of all image pixel intensities as a function of thickness should be known accurately. Under this assumption, the probability of error may decrease significantly for atom-counting in HR TEM and may, in theory, become lower as compared to HR STEM under the predicted optimal experimental settings. However, the commonly used standard for atom-counting in HR STEM leads to a high performance and has been shown to work in practice.

  7. Developing of an environmental cell TEM holder for dynamic in situ observation

    NASA Astrophysics Data System (ADS)

    Bataineh, Khaled M.

    2016-02-01

    This paper deals with the subject of "in situ" development of environmental-transmission electron microscope (E-TEM) holder assemblies. In E-TEM, the sample is continuously subjected to gases as opposed to conventional TEM where the sample is under high vacuum. E-TEM offers the possibility of achieving a new level of material analysis. E-TEM allows obtaining information about chemical information during the reaction at atomic level. Rarefied gas dynamics analysis is used to assess the proposed design. The analysis is focused on determining the molecular distribution inside the vacuum chamber and calculating the impingement rate on the target surface of the specimen. Simulations are performed to predict the molecular interaction with the specimen at given pressures to determine the proper position of a specimen within a vacuum chamber to optimize and predict reaction characteristics. Results of direct simulation Monte Carlo show that the two sides of the sample operate at different temperatures due to the gas flow and experience different molecular distributions.

  8. 1D Cole-Cole inversion of TEM transients influenced by induced polarization

    NASA Astrophysics Data System (ADS)

    Seidel, Marc; Tezkan, Bülent

    2017-03-01

    Effects of induced polarization (IP) can have an impact on time-domain electromagnetic measurements (TEM) and may lead to sign reversals in the recorded transients. To study these IP effects on TEM data, a new 1D inversion algorithm was developed for both, the central-loop and the separate-loop TEM configurations using the Cole-Cole relaxation model. 1D forward calculations for a homogeneous half-space were conducted with the aim of analyzing the impacts of the Cole-Cole parameters on TEM transients with respect to possible sign reversals. The forward modelings showed that the variation of different parameters have comparable effects on the TEM transients. This leads to an increasing number of equivalent models as a result of inversion calculations. Subsequently, 1D inversions of synthetic data were performed to study the potentials and limitations of the algorithm regarding the resolution of the Cole-Cole parameters. In order to achieve optimal inversion results, it was essential to error-weight the data points in the direct vicinity of sign reversals. The obtained findings were eventually adopted on the inversion of real field data which contained considerable IP signatures such as sign reversals. One field data set was recorded at the Nakyn kimberlite field in Western Yakutiya, Russia, in the central-loop configuration. Another field data set originates from a waste site in Cologne, Germany, and was measured utilizing the separate-loop configuration.

  9. Two-in-one sample preparation for plan-view TEM.

    PubMed

    Sáfrán, György; Szász, Noémi; Sáfrán, Eszter

    2015-07-01

    Transmission electron microscopy (TEM) sample preparation requires special skills, it is time consuming and costly, hence, an increase of the efficiency is of primary importance. This article describes a method that duplicates the yield of the conventional mechanical and ion beam preparation of plan-view TEM samples. As a modification of the usual procedures, instead of one two different samples are comprised in a single specimen. The two pre-cut slabs, one from each samples, are embedded side by side in the window of a 3 mm dia Ti disk and the specimen is thinned mechanically and by ion milling until perforation that occurs at the interface of the two different slabs. That, with proper implementation, provides acceptable size thin area for the TEM study of both samples. The suitability of the two-in-one method has been confirmed through examples.

  10. Generation of entangled TEM01 modes with periodically poled KTiOPO4 crystal

    NASA Astrophysics Data System (ADS)

    Rong-Guo, Yang; Jing-jing, Wang; Jing, Zhang; Heng-Xin, Sun

    2016-07-01

    Spatial quantum optics based on the high-order transverse mode is important for the super-resolution measurement and quantum image beyond the shot noise level. Quantum entanglement of the transverse plane Hermite-Gauss TEM01 mode has been demonstrated experimentally in this paper. Two squeezed TEM01 modes, which are generated by a pair of degenerate optical parametric amplifiers (DOPA) with the nonlinear crystals of periodically poled KTiOPO4, have been combined to produce TEM01 mode entanglement using a beam splitter. The 1.5 dB for the sum of amplitude and 1.2 dB for the difference of phase below shot-noise level is achieved with the measurement system of a Bell state detection. Project supported by the National Natural Science Foundation of China (Grant Nos. 11504218 and 61108003) and the Natural Science Foundation of Shanxi Province, China (Grant No. 2013021005-2).

  11. An automatic algorithm for determination of the nanoparticles from TEM images using circular hough transform.

    PubMed

    Mirzaei, Mohsen; Rafsanjani, Hossein Khodabakhshi

    2017-02-28

    Nanoparticles have a wide range of applications in science and technology, and the size distribution of nanoparticles is one of the most important statistical properties. Transmission electron microscopy (TEM) or X-ray diffraction is commonly used for the characterization and measuring particle size distributions, but manual analysis of the micrographs is extremely labor-intensive. Here, we have developed an image processing algorithm for measuring particle size distributions from TEM images in the presence of overlapped particles and uneven background. The approach is based on the modified circular Hough transform, and pre and post processing techniques on TEM image to improve the accuracy and increase the detection rate of the nano particles. Its application is presented through several images with different noises, uneven backgrounds and over lapped particles. The merits of this robust quantifying method are demonstrated by comparing the results with the data obtained through manual measurement. The algorithm allows particles to be detected and characterized with high accuracy.

  12. TEM measurement in a low resistivity overburden performed by using low temperature SQUID

    NASA Astrophysics Data System (ADS)

    Ji, Yanju; Du, Shangyu; Xie, Lijun; Chang, Kai; Liu, Yang; Zhang, Yi; Xie, Xiaoming; Wang, Yuan; Lin, Jun; Rong, Liangliang

    2016-12-01

    Exploration of areas with thick low resistivity overburden is still a challenge for time domain transient electromagnetic method (TEM). We report modeling of a sandwich-layered earth by simulating the B field response with different conductive target layer thicknesses, thus obtaining a relationship between the resolution of the B field and the exploration depth. A low temperature Superconducting Quantum Interference Device (SQUID) is an ideal sensor for measuring the secondary magnetic field B in TEM measurements, because its sensitivity of several fT/√Hz is independent of frequency. In our TEM experiments, we utilized two different coils as receivers, a simple SQUID system, and a large transmitter loop of 200 × 200 m2 to compare the detected decay curves. At some measurement points, a decay signal of more than 300 ms duration was obtained by using the SQUID. Apparent resistivity profiles of about 9 km length are presented.

  13. Graphene oxide single sheets as substrates for high resolution cryoTEM.

    PubMed

    van de Put, Marcel W P; Patterson, Joseph P; Bomans, Paul H H; Wilson, Neil R; Friedrich, Heiner; van Benthem, Rolf A T M; de With, Gijsbertus; O'Reilly, Rachel K; Sommerdijk, Nico A J M

    2015-02-04

    CryoTEM is an important tool in the analysis of soft matter, where generally defocus conditions are used to enhance the contrast in the images, but this is at the expense of the maximum resolution that can be obtained. Here, we demonstrate the use of graphene oxide single sheets as support for the formation of 10 nm thin films for high resolution cryoTEM imaging, using DNA as an example. With this procedure, the overlap of objects in the vitrified film is avoided. Moreover, in these thin films less background scattering occurs and as a direct result, an increased contrast can be observed in the images. Hence, imaging closer to focus as compared with conventional cryoTEM procedures is achieved, without losing contrast. In addition, we demonstrate an ~1.8 fold increase in resolution, which is crucial for accurate size analysis of nanostructures.

  14. TEM CHARACTERIZATION OF IRRADIATED U3SI2/AL DISPERSION FUEL

    SciTech Connect

    J. Gan; B. Miller; D. Keiser; A. Robinson; P. Medvedev; D. Wachs

    2010-10-01

    The silicide dispersion fuel of U3Si2/Al has been recognized as a reasonably good performance fuel for nuclear research and test reactors except that it requires the use of high enrichment uranium. An irradiated U3Si2/Al dispersion fuel (~75% enrichment) from the high flux side of a RERTR-8 (U0R040) plate was characterized using transmission electron microscopy (TEM). The fuel plate was irradiated in the advanced test reactor (ATR) for 105 days. The average irradiation temperature and fission density of the fuel particles for the TEM sample are estimated to be approximately ~110 degrees C and 5.4 x 10-21 f/cm3. The characterization was performed using a 200KV TEM with a LaB6 filament. Detailed microstructural information along with composition analysis is obtained. The results and their implication on the performance of this silicide fuel are discussed.

  15. Resolution Improvement in Aberration-Corrected Low- Voltage TEM with Monochromator at 60 kV

    NASA Astrophysics Data System (ADS)

    Morishita, S.; Mukai, M.; Sasaki, T.; Suenaga, K.; Sawada, H.

    2015-10-01

    We have developed a low-voltage electron microscope equipped with a monochromator and Delta-type Cs correctors, which shows atomic resolution at accelerating voltages of 60, 30 and 15 kV. In theory, resolution of TEM images at 60 kV is severely affected by chromatic aberration, which is proven by our calculations of contrast transfer functions and multi-slice image simulation taking chromatic aberration into account with experimental conditions. Experimentally, TEM images of gold nano-particles were observed with non-monochromated and monochromated electron sources at 60 kV. Detectable spatial frequency in the image with the monochromated source was higher than that with non- monochromated source. We have demonstrated that the TEM image resolution at the low- voltage is improved by using a monochromated electron source, which reduce the energy spread of the electron source.

  16. E240V substitution increases catalytic efficiency toward ceftazidime in a new natural TEM-type extended-spectrum beta-lactamase, TEM-149, from Enterobacter aerogenes and Serratia marcescens clinical isolates.

    PubMed

    Perilli, Mariagrazia; Celenza, Giuseppe; De Santis, Francesca; Pellegrini, Cristina; Forcella, Chiara; Rossolini, Gian Maria; Stefani, Stefania; Amicosante, Gianfranco

    2008-03-01

    The aim of this study was to characterize a novel extended-spectrum beta-lactamase that belongs to the TEM family, the TEM-149 enzyme, and that was isolated from the urine of two hospitalized patients from different hospitals in southern Italy. The peculiarity of this enzyme was the finding of a valine residue at position 240. The array of amino acid substitutions found in TEM-149 was as follows: E104K, R164S, M182T, and E240V. A reversion of a threonine residue at position 182 was also performed to create a new mutant, TEM-149 T182M, in order to assess the contribution of this substitution on the kinetic profile and the stability of TEM-149. The bla TEM-149 and bla TEM-149/T182M genes were cloned into pBC-SK, and the corresponding enzymes were purified from recombinant Escherichia coli HB101 by the same procedure. Both enzymes hydrolyzed all beta-lactams tested, with a preference for ceftazidime, which was found to be the best substrate. By comparison of the kinetic parameters of the TEM-149 and the TEM-149 T182M enzymes, a reduction of the catalytic efficiency for the TEM-149 T182M mutant was observed against all substrates tested except benzylpenicillin, cefotaxime, and aztreonam. Tazobactam, clavulanic acid, and sulbactam were good inhibitors of the TEM-149 beta-lactamase.

  17. Effectiveness of Shield Termination Techniques Tested with TEM Cell and Bulk Current Injection

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T.; Hare, Richard J.

    2009-01-01

    This paper presents experimental results of the effectiveness of various shield termination techniques. Each termination technique is evaluated by two independent noise injection methods; transverse electromagnetic (TEM) cell operated from 3 MHz 400 MHz, and bulk current injection (BCI) operated from 50 kHz 400 MHz. Both single carrier and broadband injection tests were investigated. Recommendations as to how to achieve the best shield transfer impedance (i.e. reduced coupled noise) are made based on the empirical data. Finally, the noise injection techniques themselves are indirectly evaluated by comparing the results obtained from the TEM Cell to those from BCI.

  18. SANS and TEM studies of carbide precipitation and creep damage in type 304 stainless steel

    SciTech Connect

    Yoo, M.H.; Ogle, J.C.; Schneibel, J.H.; Swindeman, R.W.

    1984-01-01

    Small-angle neutron scattering (SANS) and transmission electron microscopy (TEM) studies were performed to characterize the carbide (M/sub 23/C/sub 6/) precipitation and creep damage induced in type 304 stainless steel in the primary creep stage. The size distribution of matrix carbides evaluated from SANS analyses was consistent with TEM data, and the expected accelerated kinetics of precipitation under applied stress was confirmed. Additional SANS measurements after the postcreep solution annealing were made in order to differentiate cavities from the carbides. Potential advantages and difficulties associated with characterization of creep-induced cavitation by the SANS techniques are discussed.

  19. Investigating Processes of Materials Formation via Liquid Phase and Cryogenic TEM

    SciTech Connect

    De Yoreo, James J.; Sommerdijk, Nico

    2016-06-14

    The formation of materials in solutions is a widespread phenomenon in synthetic, biological and geochemical systems, occurring through dynamic processes of nucleation, self-assembly, crystal growth, and coarsening. The recent advent of liquid phase TEM and advances in cryogenic TEM are transforming our understanding of these phenomena by providing new insights into the underlying physical and chemical mechanisms. The techniques have been applied to metallic and semiconductor nanoparticles, geochemical and biological minerals, electrochemical systems, macromolecular complexes, and selfassembling systems, both organic and inorganic. New instrumentation and methodologies currently on the horizon promise new opportunities for advancing the science of materials synthesis.

  20. High-Resolution Imaging and Spectroscopy at High Pressure: A Novel Liquid Cell for the TEM

    PubMed Central

    Tanase, Mihaela; Winterstein, Jonathan; Sharma, Renu; Aksyuk, Vladimir; Holland, Glenn; Liddle, J. Alexander

    2016-01-01

    We demonstrate quantitative core-loss electron energy-loss spectroscopy of iron oxide nanoparticles and imaging resolution of Ag nanoparticles in liquid down to 0.24 nm, in both transmission and scanning-transmission modes, in a novel, monolithic liquid cell developed for the transmission electron microscope (TEM). At typical SiN membrane thicknesses of 50 nm the liquid layer thickness has a maximum change of only 30 nm for the entire TEM viewing area of 200 μm × 200 μm. PMID:26650072

  1. Composite fillings microleakage after TEM00 Er: YAG laser texturing of human tooth enamel surface

    NASA Astrophysics Data System (ADS)

    Belikov, A. V.; Shatilova, K. V.; Skrypnik, A. V.; Fedotov, D. Y.

    2010-11-01

    The results of comparative investigation of methylene-blue microleakage between tooth enamel surface and light-cure composites various fluidity are presented. An enamel surface was treated by traditional methods or laser method (laser texturing). The role of adhesive systems is investigated at enamel texturing by the TEM00 Er: YAG radiation. It is shown, that microleakage was not observed when enamel was textured by the TEM00 Er: YAG laser radiation and covered with flowable composite "Revolution" (Kerr) without adhesive system. It is established, that for laser textured surfaces methylene-blue microleakage depends on distance between microcraters.

  2. Sorption processes and XRD analysis of a natural zeolite exchanged with Pb(2+), Cd(2+) and Zn(2+) cations.

    PubMed

    Castaldi, Paola; Santona, Laura; Enzo, Stefano; Melis, Pietro

    2008-08-15

    In this study the Pb(2+), Cd(2+) and Zn(2+) adsorption capacity of a natural zeolite was evaluated in batch tests at a constant pH of 5.5 by polluting this mineral with solutions containing increasing concentrations of the three cations to obtain adsorption isotherms. In addition X-ray powder diffraction (XRD) was used to investigate the changes of zeolite structure caused by the exchange with cations of different ionic radius. The zeolite adsorption capacity for the three cations was Zn>Pb>Cd. Moreover a sequential extraction procedure [H(2)O, 0.05 M Ca(NO(3))(2) and 0.02 M EDTA] was applied to zeolite samples used in the adsorption experiments to determine the chemical form of the cations bound to the sorbent. Using this approach it was shown that low concentrations of Pb(2+), Cd(2+) and Zn(2+) were present as water-soluble and exchangeable fractions (<25% of the Me adsorbed), while EDTA extracted most of the adsorbed cations from the zeolite (>27% of the Me adsorbed). The XRD pattern of zeolite, analysed according to the Rietveld method, showed that the main mineralogical phase involved in the adsorption process was clinoptilolite. Besides structure information showed that the incorporation of Pb(2+), Cd(2+) and Zn(2+), into the zeolite frameworks changed slightly but appreciably the lattice parameters. XRD analysis also showed the occurrence of some isomorphic substitution phenomena where the Al(3+) ions of the clinoptilolite framework were replaced by exchanged Pb(2+) cations in the course of the ion exchange reaction. This mechanism was instead less evident in the patterns of the samples doped with Cd(2+) and Zn(2+) cations.

  3. Powder-XRD and (14) N magic angle-spinning solid-state NMR spectroscopy of some metal nitrides.

    PubMed

    Kempgens, Pierre; Britton, Jonathan

    2016-05-01

    Some metal nitrides (TiN, ZrN, InN, GaN, Ca3 N2 , Mg3 N2 , and Ge3 N4 ) have been studied by powder X-ray diffraction (XRD) and (14) N magic angle-spinning (MAS) solid-state NMR spectroscopy. For Ca3 N2 , Mg3 N2 , and Ge3 N4 , no (14) N NMR signal was observed. Low speed (νr  = 2 kHz for TiN, ZrN, and GaN; νr  = 1 kHz for InN) and 'high speed' (νr  = 15 kHz for TiN; νr  = 5 kHz for ZrN; νr  = 10 kHz for InN and GaN) MAS NMR experiments were performed. For TiN, ZrN, InN, and GaN, powder-XRD was used to identify the phases present in each sample. The number of peaks observed for each sample in their (14) N MAS solid-state NMR spectrum matches perfectly well with the number of nitrogen-containing phases identified by powder-XRD. The (14) N MAS solid-state NMR spectra are symmetric and dominated by the quadrupolar interaction. The envelopes of the spinning sidebands manifold are Lorentzian, and it is concluded that there is a distribution of the quadrupolar coupling constants Qcc 's arising from structural defects in the compounds studied.

  4. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    PubMed

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study.

  5. Astrobiological Significance of Definitive Mineralogical Analysis of Martian Surface Samples Using the CheMin XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Feldman, S. M.; Blake, D. F.; Sarrazin, P.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

    2004-01-01

    The search for evidence of habitability, or of extant or extinct life on Mars, will initially be a search for evidence of past or present conditions supportive of life. The three key requirements for the emergence of life are thought to be liquid water; a suitable energy source; and chemical building blocks. CheMin is a miniaturized XRD/XRF (X-Ray diffraction / X-ray fluorescence) instrument which has been developed for definitive mineralogic analysis of soils and rocks on the Martian surface. The CheMin instrument can provide information that is highly relevant to each of these habitability requirements as summarized below.

  6. Rapid characterisation of archaeological midden components using FT-IR spectroscopy, SEM-EDX and micro-XRD.

    PubMed

    Shillito, Lisa-Marie; Almond, Matthew J; Nicholson, James; Pantos, Manolis; Matthews, Wendy

    2009-07-01

    Samples taken from middens at the Neolithic site of Catalhöyük in Turkey have been analysed using IR spectroscopy backed up by powder XRD and SEM-EDX. Microcomponents studied include fossil hackberries (providing evidence of ancient diet and seasonality), mineral nodules (providing evidence of post-depositional change) and phytoliths (mineralised plant cells, providing evidence of usage of plant species). Finely laminated ashy deposits have also been investigated allowing chemical and mineralogical variations to be explored. It is found that many layers which appear visually to be quite distinctive have, in fact, very similar mineralogy.

  7. Comparative investigation of Fourier Transform Infrared (FT-IR) spectroscopy and X-ray Diffraction (XRD) in the determination of cotton fiber crystallinity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite considerable efforts in developing the curve-fitting protocol to evaluate the crystallinity index (CI) from the X-ray diffraction (XRD) measurement, in its present state XRD procedure can only provide a qualitative or semi-quantitative assessment of the amounts of crystalline or amorphous po...

  8. Simple and rapid methods for SEM observation and TEM immunolabeling of rubber particles.

    PubMed

    Singh, Adya P; Wi, Seung Gon; Kang, Hunseung; Chung, Gap Chae; Kim, Yoon Soo

    2003-08-01

    We developed a method involving air-drying of a rubber suspension after fixation in glutaraldehyde-tannic acid and postfixation in osmium tetroxide for SEM observation. For TEM immunolabeling the suspension was air-dried after osmium-only fixation. Whereas conventional methods failed to satisfactorily stabilize rubber particles, the methods described here proved successful in preserving their integrity.

  9. Molecular dynamics simulations and morphology analysis of TEM imaged PVDF nanofibers

    NASA Astrophysics Data System (ADS)

    Miao, Jiayuan; Reneker, Darrell; Tsige, Mesfin; Taylor, Philip

    With the goal of elucidating the structure of polyvinylidene fluoride (PVDF) nanofibers, all-atom molecular dynamics simulations were performed, and the results compared with structures observed in high resolution transmission electron microscopy (TEM) at the molecular level. Simulation shows that the stability of the β-phase component in a PVDF nanofiber is influenced by its thickness and processing history. When exposed to irradiation, as in a TEM observation, the structure is then further modified by the effects of chain scission. The transformation from the β phase into a paraelectric phase can explain the spindle formation and serpentine motion of molecular segments observed by Zhong et al. (Polymer, 54, 2013, 3745-3756) in irradiated PVDF nanofibers. From a comparison between simulated and experimental TEM images it was possible to identify numerous features that are useful in unveiling the inherent structure of PVDF nanofibers. The experimental TEM images appear to match well with those predicted by a model based on α-phase PVDF, while also being consistent with an alternative model (Nanoscale 2015, DOI: 10.1039/c5nr01619c). Work supported by the Petroleum Research Fund of the ACS.

  10. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    NASA Astrophysics Data System (ADS)

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 Å = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  11. Occurrence of Siliceous Impact Melt in Netschaëvo IIE? A FIB-TEM Study

    NASA Astrophysics Data System (ADS)

    Hamann, C.; Van Roosbroek, N.; Greshake, A.; Pittarello, L.; Hecht, L.; Debaille, V.; Wirth, R.; Claeys, Ph.

    2015-07-01

    A silicate inclusion in a sample of the Netschaëvo IIE iron meteorite was studied with FIB-TEM. We present petrographic features indicating that this inclusion is quenched impact melt and suggest that Netschaëvo is an impact melt breccia.

  12. Bonding and structure of a reconstructed (001) surface of SrTiO3 from TEM.

    PubMed

    Zhu, Guo-zhen; Radtke, Guillaume; Botton, Gianluigi A

    2012-10-18

    The determination of the atomic structure and the retrieval of information about reconstruction and bonding of metal oxide surfaces is challenging owing to the highly defective structure and insulating properties of these surfaces. Transmission electron microscopy (TEM) offers extremely high spatial resolution (less than one ångström) and the ability to provide systematic information from both real and reciprocal space. However, very few TEM studies have been carried out on surfaces because the information from the bulk dominates the very weak signals originating from surfaces. Here we report an experimental approach to extract surface information effectively from a thickness series of electron energy-loss spectra containing different weights of surface signals, using a wedge-shaped sample. Using the (001) surface of the technologically important compound strontium titanate, SrTiO(3) (refs 4-6), as a model system for validation, our method shows that surface spectra are sensitive to the atomic reconstruction and indicate bonding and crystal-field changes surrounding the surface Ti cations. Very good agreement can be achieved between the experimental surface spectra and crystal-field multiplet calculations based on the proposed atomic surface structure optimized by density functional calculations. The distorted TiO(6-x) units indicated by the proposed model can be viewed directly in our high-resolution scanning TEM images. We suggest that this approach be used as a general method to extract valuable spectroscopic information from surface atoms in parallel with high-resolution images in TEM.

  13. Critical hydrogen bonding by serine 235 for cephalosporinase activity of TEM-1 beta-lactamase.

    PubMed Central

    Imtiaz, U; Manavathu, E K; Lerner, S A; Mobashery, S

    1993-01-01

    The role of Ser-235 in the catalytic mechanism of the TEM-1 beta-lactamase has been explored by the study of a mutant enzyme in which Ser-235 has been substituted by alanine (Ala-235 mutant enzyme). A comparative kinetic analysis of both the wild-type and the Ala-235 TEM-1 enzymes revealed little effect of this substitution of residue 235 on the turnover of penicillins but a greater effect on the turnover of cephalosporins. Susceptibility testing of Escherichia coli strains harboring the wild-type TEM-1 beta-lactamase and the Ala-235 mutant enzyme revealed an effect of the mutation similar to that observed in the enzymological studies. The MICs of two representative cephalosporins for the strain containing the mutant enzyme were much lower than those for the isogenic strain bearing the wild-type TEM-1 beta-lactamase. On the other hand, the strain with the mutant enzyme was still highly resistant to penicillins. PMID:8285630

  14. XAS and HR-TEM Analyses of the Nakhlite Hydrothermal Minerals

    NASA Astrophysics Data System (ADS)

    Hicks, L. J.; Bridges, J. C.; Gurman, S. J.

    2012-09-01

    We use Fe-K XANES and EXAFS, with HR-TEM observations, to show that the phyllosilicate minerals found in the Lafayette nakhlite are saponite and serpentine. An increase in ferric/ferrous ratio is identified as part of the hydrothermal activity.

  15. Thinning of large mammalian cells for cryo-TEM characterization by cryo-FIB milling.

    PubMed

    Strunk, K M; Wang, K; Ke, D; Gray, J L; Zhang, P

    2012-09-01

    Focused ion beam milling at cryogenic temperatures (cryo-FIB) is a valuable tool that can be used to thin vitreous biological specimens for subsequent imaging and analysis by cryo-transmission electron microscopy (cryo-TEM) in a frozen-hydrated state. This technique offers the potential benefit of eliminating the mechanical artefacts that are typically found with cryo-ultramicrotomy. However, due to the additional complexity in transferring samples in and out of the FIB, contamination and devitrification of the amorphous ice is commonly encountered. To address these problems, we have designed a sample cryo-shuttle that directly and specifically accepts Polara TEM cartridges to simplify the transfer process between FIB and TEM. We optimized several parameters in the cryo-FIB and cryo-TEM processes using the quality of the samples' ice as an indicator and demonstrated high-quality milling with large mammalian cells. By comparing the results from HeLa cells to those from Escherichia coli cells, we discuss some of the artefacts and challenges we have encountered using this technique.

  16. Structure and Dynamics of Domains in Ferroelectric Nanostructures. In-situ TEM Studies

    SciTech Connect

    Pan, Xiaoqing

    2015-06-30

    The goal of this project was to explore the structure and dynamic behaviors of ferroelectric domains in ferroelectric thin films and nanostructures by advanced transmission electron microscopy (TEM) techniques in close collaboration with phase field modeling. The experimental techniques used include aberration-corrected sub-Å resolution TEM and in-situ TEM using a novel scanning tunneling microscopy (STM) - TEM holder that allows the direct observation of nucleation and dynamic evolution of ferroelectric domains under applied electric field. Specifically, this project was aimed to (1) to study the roles of static electrical boundary conditions and electrical charge in controlling the equilibrium domain structures of BiFeO3 thin films with controlled substrate constraints, (2) to explore the fundamental mechanisms of ferroelectric domain nucleation, growth, and switching under an applied electric field in both uniform thin films and nanostructures, and to understand the roles of crystal defects such as dislocations and interfaces in these processes, (3) to understand the physics of ferroelectric domain walls and the influence of defects on the electrical switching of ferroelectric domains.

  17. Aberration-corrected STEM/TEM imaging at 15kV.

    PubMed

    Sasaki, Takeo; Sawada, Hidetaka; Hosokawa, Fumio; Sato, Yuta; Suenaga, Kazu

    2014-10-01

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192nm, and the power spectrum of the image showed spots corresponding to distances of 0.111nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314nm and 0.192nm, respectively. At an accelerating voltage of 15kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase.

  18. The phase relations in Earth's mid-lower mantle: constraints from in-situ XRD and quantitative chemical analysis

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Meng, Y.; Prakapenka, V.; Mao, W. L.

    2011-12-01

    Determining the phase relations in the system MgO-FeO-SiO2 at high pressure (P) and high temperature (T) is of fundamental importance for understanding the geochemical and geophysical properties of Earth's deep interior. The phase relations in the upper lower mantle have been investigated both in a diamond anvil cell (DAC) [1] and a multi-anvil apparatus [2]. In this study, we investigated the phase relations in (Mg0.6Fe0.4)SiO3 at elevated P-T conditions (up to 80 GPa and 3000 K) by in-situ X-ray diffraction (XRD) measurements in a DAC. Each sample was compressed to the P of interest and then heated to high T. In-situ XRD data were collected at high P-T and then the sample was quenched to preserve the high P-T chemical composition. Samples were recovered and phase chemistry was obtained by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis. Fe solubility in Pv phase increases with increasing P up to 80 GPa. (Mg0.6Fe0.4)SiO3 Pv formed at 80 GPa and its unit-cell volume is 1.8 % larger than that of Fe-free Pv (Lundin et al., 1991). Our improved knowledge of the phase relations in the mid-lower mantle and related geophysical implications will be discussed.

  19. Lead Speciation in House Dust from Canadian Urban Homes Using EXAFS Micro-XRF and Micro-XRD

    SciTech Connect

    L MacLean; S Beauchemin; P Rasmussen

    2011-12-31

    X-ray absorption fine-structure (XAFS) spectroscopy, micro-X-ray fluorescence ({mu}XRF), and micro-X-ray diffraction ({mu}XRD) were used to determine the speciation of Pb in house dust samples from four Canadian urban homes having elevated Pb concentrations (>1000 mg Pb kg{sup -1}). Linear combination fitting of the XAFS data, supported by {mu}XRF and {mu}XRD, shows that Pb is complexed in a variety of molecular environments, associated with both the inorganic and organic fractions of the dust samples. The inorganic species of lead identified were as follows: Pb metal, Pb carbonate, Pb hydroxyl carbonate, Pb oxide, and Pb adsorbed to iron oxyhydroxides. Pb carbonate and/or Pb hydroxyl carbonate occurred in all four dust samples and accounted for 28 to 75% of total Pb. Pb citrate and Pb bound to humate were the organic species identified. The results of this study demonstrate the ability of XAFS to identify Pb speciation in house dust and show the potential to identify Pb sources from new homes versus older homes. Understanding Pb speciation and how it influences bioaccessibility is important for human health risk assessment and risk management decisions which aim to improve indoor environmental health.

  20. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: spectral, thermal, XRD and antimicrobial studies.

    PubMed

    Sundararajan, M L; Jeyakumar, T; Anandakumaran, J; Karpanai Selvan, B

    2014-10-15

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, (1)H NMR, (13)C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base.

  1. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: Spectral, thermal, XRD and antimicrobial studies

    NASA Astrophysics Data System (ADS)

    Sundararajan, M. L.; Jeyakumar, T.; Anandakumaran, J.; Karpanai Selvan, B.

    2014-10-01

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, 1H NMR, 13C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, 1H NMR, 13C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base.

  2. Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO4:Dy TL material

    NASA Astrophysics Data System (ADS)

    Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Hamid, Muhammad Azmi Abdul; Dollah, Mohd Taufik

    2014-09-01

    This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO4) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO4 with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO4:Dy was studied using a TLD reader after exposure to gamma ray by Co60 source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.

  3. The Crystal Structure of Micro- and Nanopowders of ZnS Studied by EPR of Mn2+ and XRD

    NASA Astrophysics Data System (ADS)

    Nosenko, Valentyna; Vorona, Igor; Grachev, Valentyn; Ishchenko, Stanislav; Baran, Nikolai; Becherikov, Yurii; Zhuk, Anton; Polishchuk, Yuliya; Kladko, Vasyl; Selishchev, Alexander

    2016-11-01

    The crystal structure of micro- and nanopowders of ZnS doped with different impurities was analyzed by the electron paramagnetic resonance (EPR) of Mn2+ and XRD methods. The powders of ZnS:Cu, ZnS:Mn, ZnS:Co, and ZnS:Eu with the particle sizes of 5-7 μm, 50-200 nm, 7-10 μm, and 5-7 nm, respectively, were studied. Manganese was incorporated in the crystal lattice of all the samples as uncontrolled impurity or by doping. The Mn2+ ions were used as EPR structural probes. It is found that the ZnS:Cu has the cubic structure, the ZnS:Mn has the hexagonal structure with a rhombic distortion, the ZnS:Co is the mixture of the cubic and hexagonal phases in the ratio of 1:10, and the ZnS:Eu has the cubic structure and a distorted cubic structure with stacking defects in the ratio 3:1. The EPR technique is shown to be a powerful tool in the determination of the crystal structure for mixed-polytype ZnS powders and powders with small nanoparticles. It allows observation of the stacking defects, which is revealed in the XRD spectra.

  4. Development and Application of Operando TEM to a Ruthenium Catalyst for CO Oxidation

    NASA Astrophysics Data System (ADS)

    Miller, Benjamin Kyle

    Operando transmission electron microscopy (TEM) is an extension of in-situ TEM in which the performance of the material being observed is measured simultaneously. This is of great value, since structure-performance relationships lie at the heart of materials science. For catalyst materials, like the SiO2-supported Ru nanoparticles studied, the important performance metric, catalyst activity, is measured inside the microscope by determining the gas composition during imaging. This is accomplished by acquisition of electron energy loss spectra (EELS) of the gas in the environmental TEM while catalysis is taking place. In this work, automated methods for rapidly quantifying low-loss and core-loss EELS of gases were developed. A new sample preparation method was also established to increase catalytic conversion inside a differentially-pumped environmental TEM, and the maximum CO conversion observed was about 80%. A system for mixing gases and delivering them to the environmental TEM was designed and built, and a method for locating and imaging nanoparticles in zone axis orientations while minimizing electron dose rate was determined. After atomic resolution images of Ru nanoparticles observed during CO oxidation were obtained, the shape and surface structures of these particles was investigated. A Wulff model structure for Ru particles was compared to experimental images both by manually rotating the model, and by automatically determining a matching orientation using cross-correlation of shape signatures. From this analysis, it was determined that most Ru particles are close to Wulff-shaped during CO oxidation. While thick oxide layers were not observed to form on Ru during CO oxidation, thin RuO2 layers on the surface of Ru nanoparticles were imaged with atomic resolution for the first time. The activity of these layers is discussed in the context of the literature on the subject, which has thus far been inconclusive. We conclude that disordered oxidized ruthenium

  5. Landed XRD/XRF analysis of prime targets in the search for past or present Martian life.

    PubMed

    Vaniman, D; Bish, D; Blake, D; Elliott, S T; Sarrazin, P; Collins, S A; Chipera, S

    1998-12-25

    Mars landers seeking evidence for past or present life will be guided by information from orbital mapping and from previous surface exploration. Several target options have been proposed, including sites that may harbor extant life and sites most likely to preserve evidence of past life These sites have specific mineralogic characteristics. Extant life might be gathered around the sinters and associated mineral deposits of rare active fumaroles, or held within brine pockets and inclusions in a few evaporite-mineral deposits. Possibilities for fossilization include deltaic and lake-bottom sediments of once-flooded craters, sinters formed by ancient hot-spring deposits, and the carbonate deposits associated with some evaporite systems. However, the highly varied mineralogy of fossil occurrences on Earth leads to the inference that Mars, an equally complex planet, could host a broad variety of potential fossilizing deposits. The abundance of volcanic systems on Mars and evidence for close associations between volcanism and water release suggest possibilities of organism entrapment and mineralization in volcaniclastic deposits, as found in some instances on Earth. Thus the targets being considered for exploration include a wide variety of unique deposits that would be characterized by silica or various nonsilicate minerals. Beyond these "special" deposits and in the most general case, an ability to distinguish mineralized from uncemented volcanic detritus may be the key to success in finding possible fossil-bearing authigenic mineralogies. A prototype miniaturized X ray diffraction/X ray fluorescence (XRD/XRF) instrument has been evaluated with silica, carbonate, and sulfate minerals and with a basalt, to examine the capabilities of this tool in mineralogic and petrologic exploration for exobiological goals. This instrument. CHEMIN (chemical and mineralogical analyzer), is based on an innovative low-power X ray tube, transmission geometry, and CCD collection and

  6. Characterization of minerals in air dust particles in the state of Tamilnadu, India through FTIR, XRD and SEM analyses

    NASA Astrophysics Data System (ADS)

    Senthil Kumar, R.; Rajkumar, P.

    2014-11-01

    The abstract of this paper explains the presence of minerals in air which causes great concern regarding public health issues. The spectroscopic investigation of air dust particles of several samples in various locations in the state of Tamilnadu, India is reported. Qualitative analyses were carried out to determine the major and minor constituent minerals present in the samples based on the FTIR, XRD absorption peaks. This study also identified the minerals like quartz, asbestos, kaolinite, calcite, hematite, montmorillonite, nacrite and several other trace minerals in the air dust particles. The presents of quartz is mainly found in all the samples invariably. Hence the percentage of quartz and its crystalline nature were determined with the help of extinction co-efficient and crystallinity index respectively. The shape and size of the particulates are studied with SEM analysis.

  7. Real-Time XRD Studies of Li-O2 Electrochemical Reaction in Nonaqueous Lithium-Oxygen Battery.

    PubMed

    Lim, Hyunseob; Yilmaz, Eda; Byon, Hye Ryung

    2012-11-01

    Understanding of electrochemical process in rechargeable Li-O2 battery has suffered from lack of proper analytical tool, especially related to the identification of chemical species and number of electrons involved in the discharge/recharge process. Here we present a simple and straightforward analytical method for simultaneously attaining chemical and quantified information of Li2O2 (discharge product) and byproducts using in situ XRD measurement. By real-time monitoring of solid-state Li2O2 peak area, the accurate efficiency of Li2O2 formation and the number of electrons can be evaluated during full discharge. Furthermore, by observation of sequential area change of Li2O2 peak during recharge, we found nonlinearity of Li2O2 decomposition rate for the first time in ether-based electrolyte.

  8. Investigation of structural resorption behavior of biphasic bioceramics with help of gravimetry, μCT, SEM, and XRD.

    PubMed

    de Wild, Michael; Amacher, Fabienne; Bradbury, Christopher R; Molenberg, Aart

    2016-04-01

    Resorbable bone substitute materials are widely used for bone augmentation after tumor resection, parallel to implant placement, or in critical size bone defects. In this study, the structural dissolution of a biphasic calcium phosphate bone substitute material with a hydroxyapatite (HA)/tricalcium phosphate (β-TCP) ratio of 60/40 was investigated by repeatedly placing porous blocks in EDTA solution at 37 °C. At several time points, the blocks were investigated by SEM, µCT, and gravimetry. It was found that always complete 2-3 µm sized grains were removed from the structure and that the β-TCP is dissolved more rapidly. This selective dissolution of the β-TCP grains was confirmed by XRD measurements. The blocks were eroded from the outside toward the center. The structure remained mechanically stable because the central part showed a delayed degradation and because the slower dissolving HA grains preserved the integrity of the structure.

  9. Spectral Resolution for Five-Element, Filtered, X-Ray Detector (XRD) Arrays Using the Methods of Backus and Gilbert

    SciTech Connect

    FEHL,DAVID LEE; BIGGS,F.; CHANDLER,GORDON A.; STYGAR,WILLIAM A.

    2000-01-17

    The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining spectra from a 5-channel, filtered array of x-ray detectors (XRD's). This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({le}2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with the unfold method currently in use. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV black-body) and the unfold. This function may be used as an initial trial function for iterative methods or a regularization model.

  10. Reciprocal space XRD mapping with varied incident angle as a probe of structure variation within surface depth

    SciTech Connect

    Yang, Qiguang; Williams, Frances; Zhao, Xin; Reece, Charles E.; Krishnan, Mahadevan

    2013-09-01

    In this study, we used a differential-depth X-Ray diffraction Reciprocal Spacing Mapping (XRD RSM) technique to investigate the crystal quality of a variety of SRF-relevant Nb film and bulk materials. By choosing different X-ray probing depths, the RSM study successfully revealed evolution the of materials microstructure after different materials processes, such as energetic condensation or surface polishing. The RSM data clearly measured the materials crystal quality at different thickness. Through a novel differential-depth RSM technique, this study found: I. for a heteroepitaxy Nb film Nb(100)/MgO(100), the film thickening process, via a cathodic arc-discharge Nb ion deposition, created a near-perfect single crystal Nb on the surfaces top-layer; II. for a mechanically polished single-crystal bulk Nb material, the microstructure on the top surface layer is more disordered than that in-grain.

  11. Degradation of dental ZrO2-based materials after hydrothermal fatigue. Part I: XRD, XRF, and FESEM analyses.

    PubMed

    Perdigão, Jorge; Pinto, Ana M; Monteiro, Regina C C; Braz Fernandes, Francisco M; Laranjeira, Pedro; Veiga, João P

    2012-01-01

    The aim was to investigate the effect of simulated low-temperature degradation (s-LTD) and hydrothermal fatigue on the degradation of three ZrO(2)-based dental materials. Lava, IPS, and NanoZr discs were randomly assigned to (1) Control-Storage in distilled water at 37°C; (2) Aging at 134°C for 5 h (s-LTD); (3) Thermocycling in saliva for 30,000 cycles (TF). XRD revealed that ZrO(2) m phase was identified in all groups but TF increased the m phase only for Lava. Under the FESEM, Lava showed no alterations under s-LTD, but displayed corrosion areas up to 60 µm wide after TF. We conclude that TF accelerated the degradation of Lava through an increase in the m phase and grain pull-out from the material surface.

  12. Identification of reaction compounds in micrometric layers from gothic paintings using combined SR-XRD and SR-FTIR.

    PubMed

    Salvadó, Nati; Butí, Salvador; Nicholson, James; Emerich, Hermann; Labrador, Ana; Pradell, Trinitat

    2009-07-15

    Synchrotron radiation X-ray diffraction (micro-SR-XRD) and Fourier transform infrared spectroscopy (micro-SR-FTIR) are used in the non-destructive identification of reaction and aging compounds from micrometric ancient painting layers. The combination of the micrometer size and non-destructive nature of the techniques together with the high resolution and brilliance of the synchrotron radiation has proved to be a procedure most advantageous for the study of reaction, aging and degradation processes. Copper, lead and calcium carboxylates and oxalates are determined in the chromatic, preparation and alteration layers from 15th century egg tempera and oil paintings. Their nature and crystallinity have been assessed. Some hypothesis about the mechanisms of development of both carboxylates and oxalates are presented.

  13. Scalable pumping approach for extracting the maximum TEM(00) solar laser power.

    PubMed

    Liang, Dawei; Almeida, Joana; Vistas, Cláudia R

    2014-10-20

    A scalable TEM(00) solar laser pumping approach is composed of four pairs of first-stage Fresnel lens-folding mirror collectors, four fused-silica secondary concentrators with light guides of rectangular cross-section for radiation homogenization, four hollow two-dimensional compound parabolic concentrators for further concentration of uniform radiations from the light guides to a 3 mm diameter, 76 mm length Nd:YAG rod within four V-shaped pumping cavities. An asymmetric resonator ensures an efficient large-mode matching between pump light and oscillating laser light. Laser power of 59.1 W TEM(00) is calculated by ZEMAX and LASCAD numerical analysis, revealing 20 times improvement in brightness figure of merit.

  14. Direct observation of catalytic oxidation of particulate matter using in situ TEM

    PubMed Central

    Kamatani, Kohei; Higuchi, Kimitaka; Yamamoto, Yuta; Arai, Shigeo; Tanaka, Nobuo; Ogura, Masaru

    2015-01-01

    The ability to observe chemical reactions at the molecular level convincingly demonstrates the physical and chemical phenomena occurring throughout a reaction mechanism. Videos obtained through in situ transmission electron microscopy (TEM) revealed the oxidation of catalytic soot under practical reaction conditions. Carbon oxidation reactions using Ag/SiO2 or Cs2CO3/nepheline catalysts were performed at 330 °C under an O2 flow of 0.5 Pa in the TEM measurement chamber. Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction. In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction. Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms. PMID:26154580

  15. Size Dependent Pore Formation in Germanium Nanowires Undergoing Reversible Delithiation Observed by In Situ TEM

    SciTech Connect

    Lu, Xiaotang; He, Yang; Mao, Scott X.; Wang, Chong-min; Korgel, Brian A.

    2016-12-22

    Germanium (Ge) nanowires coated with an amorphous silicon (Si) shell undergoing lithiation and delithiation were studied using in situ transmission electron microscopy (TEM). Delithiation creates pores in nanowires with diameters larger than ~25 nm, but not in smaller diameter nanowires. The formation of pores in Ge nanowires undergoing delithiation has been observed before in in situ TEM experiments, but there has been no indication that a critical diameter exists below which pores do not form. Pore formation occurs as a result of fast lithium diffusion compared to vacancy migration. We propose that a short diffusion path for vacancies to the nanowire surface plays a role in limiting pore formation even when lithium diffusion is fast.

  16. A High-Power Reflector Impulse Antenna with Dual-Tem Source

    NASA Astrophysics Data System (ADS)

    Guo, Chen; Zhang, An-Xue; Wu, Hui; Jiang, Yan-Sheng; Wang, Wen-Bing

    2008-09-01

    There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative optimal feeding structure.

  17. Watching the dehydrogenation of alane (AlH3) in a TEM

    NASA Astrophysics Data System (ADS)

    Beattie, Shane; Humphries, Terry; Weaver, Louise; McGrady, Sean

    2008-03-01

    Alane (AlH3) is a promising candidate for on-board hydrogen storage applications. Its theoretical gravimetric capacity is 10.1 percent and decomposition is achieved with modest heating (60-200 deg C). We studied the dehydrogenation of alane, insitu, in a TEM. Alane powder was loaded into the TEM and heated at 80 deg C. We were able to `watch' the dehydrogenation of the alane to aluminum. Electron diffraction and dark fiend images are used to show how and where the aluminum crystallites grow. Although crystalline aluminum phases were successfully identified, some of the sample remained amorphous. We will discuss the nature of the amorphous material and present images clearly identifying the nature of the aluminum crystallites.

  18. Experimental Space Weathering of Ordinary Chondrites by Nanopulse Laser: TEM Results

    NASA Technical Reports Server (NTRS)

    Noble, S. K.; Hiroi, T.; Keller, L. P.; Pieters, C. M.

    2011-01-01

    A set of ordinary chondrite meteorites has been subjected to artificial space weathering by nanopulse laser to simulate the effects of micrometeorite bombardment. Three meteorites, an H (Ehole), L (Chateau Renard - CR), and LL (Appley Bridge - AB) were lasered following the method of Sasaki et al [1]. Near IR spectra were taken before and after exposure to examine the optical changes induced and the samples were examined by scanning and transmission electron microscopy (SEM and TEM) to understand the physical changes.

  19. TEM and HRXRD Analysis of LP MOVPE Grown InGaP/GaAs epilayers

    SciTech Connect

    Pelosi, Claudio; Bosi, Matteo; Attolini, Giovanni; Germini, Fabrizio; Frigeri, Cesare; Prutskij, Tatiana

    2007-04-10

    The diffusion phenomena at interfaces between GaAs/InGaP layers grown by low pressure MOVPE have been studied by dark field (DF) transmission Electron Microscopy (TEM) and High resolution X-ray Diffractometry (HRXRD). By comparing the results of the two techniques a mismatched layer containing P or P and In has been evidenced. The causes of this behavior are briefly discussed.

  20. Optimized Ar(+)-ion milling procedure for TEM cross-section sample preparation.

    PubMed

    Dieterle, Levin; Butz, Benjamin; Müller, Erich

    2011-11-01

    High-quality samples are indispensable for every reliable transmission electron microscopy (TEM) investigation. In order to predict optimized parameters for the final Ar(+)-ion milling preparation step, topographical changes of symmetrical cross-section samples by the sputtering process were modeled by two-dimensional Monte-Carlo simulations. Due to its well-known sputtering yield of Ar(+)-ions and its easiness in mechanical preparation Si was used as model system. The simulations are based on a modified parameterized description of the sputtering yield of Ar(+)-ions on Si summarized from literature. The formation of a wedge-shaped profile, as commonly observed during double-sector ion milling of cross-section samples, was reproduced by the simulations, independent of the sputtering angle. Moreover, the preparation of wide, plane parallel sample areas by alternating single-sector ion milling is predicted by the simulations. These findings were validated by a systematic ion-milling study (single-sector vs. double-sector milling at various sputtering angles) using Si cross-section samples as well as two other material-science examples. The presented systematic single-sector ion-milling procedure is applicable for most Ar(+)-ion mills, which allow simultaneous milling from both sides of a TEM sample (top and bottom) in an azimuthally restricted sector perpendicular to the central epoxy line of that cross-sectional TEM sample. The procedure is based on the alternating milling of the two halves of the TEM sample instead of double-sector milling of the whole sample. Furthermore, various other practical aspects are issued like the dependency of the topographical quality of the final sample on parameters like epoxy thickness and incident angle.

  1. Comparison of preparation techniques for nuclear materials for transmission electron microscopy (TEM)

    SciTech Connect

    Aitkaliyeva, Assel; Madden, James W.; Miller, Brandon D; Cole, James I; Gan, Jian

    2015-04-01

    Preparation of highly radioactive and irradiated nuclear fuels and materials for transmission electron microscopy (TEM) is conjoined with a set of unique challenges, including but not limited to personnel radiation exposure and contamination. The paper evaluates three specimen preparation techniques for preparation of irradiated materials and determines which technique yields to the most reliable characterization of radiation damage microstructure. Various specimen preparation artifacts associated with each technique are considered and ways of minimizing these artifacts are addressed.

  2. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures

    PubMed Central

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-01-01

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires. PMID:27571919

  3. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures.

    PubMed

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-08-30

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires.

  4. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures

    NASA Astrophysics Data System (ADS)

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-08-01

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires.

  5. Molecular dynamics simulations of the TEM-1 beta-lactamase complexed with cephalothin.

    PubMed

    Díaz, Natalia; Suárez, Dimas; Merz, Kenneth M; Sordo, Tomás L

    2005-02-10

    Herein, we present theoretical results aimed at elucidating the origin of the kinetic preference for penicillins over cephalosporins characteristic of the TEM/SHV subgroup of class A beta-lactamases. First, we study the conformational properties of cephalothin showing that the C2-down conformer of the dihydrothiazine ring is preferred over the C2-up one by approximately 2 kcal/mol in solution (0.4-1.4 kcal/mol in the gas phase). Second, the TEM-1 beta-lactamase complexed with cephalothin is investigated by carrying out a molecular dynamics simulation. The DeltaG(binding) energy is then estimated using molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) and quantum chemical PBSA (QM-PBSA) computational schemes. The preferential binding of benzylpenicillin over cephalothin is reproduced by the different energetic calculations, which predict relative DeltaDeltaG(binding) energies ranging from 1.8 to 5.7 kcal/mol. The benzylpenicillin/cephalothin DeltaDeltaG(binding) energy is most likely due to the lower efficacy of cephalosporins than that of penicillins in order to simultaneously bind the "carboxylate pocket" and the "oxyanion hole" in the TEM-1 active site.

  6. Differential Dependence on N-Glycosylation of Anthrax Toxin Receptors CMG2 and TEM8

    PubMed Central

    Friebe, Sarah; Deuquet, Julie; van der Goot, F. Gisou

    2015-01-01

    ANTXR 1 and 2, also known as TEM8 and CMG2, are two type I membrane proteins, which have been extensively studied for their role as anthrax toxin receptors, but with a still elusive physiological function. Here we have analyzed the importance of N-glycosylation on folding, trafficking and ligand binding of these closely related proteins. We find that TEM8 has a stringent dependence on N-glycosylation. The presence of at least one glycan on each of its two extracellular domains, the vWA and Ig-like domains, is indeed necessary for efficient trafficking to the cell surface. In the absence of any N-linked glycans, TEM8 fails to fold correctly and is recognized by the ER quality control machinery. Expression of N-glycosylation mutants reveals that CMG2 is less vulnerable to sugar loss. The absence of N-linked glycans in one of the extracellular domains indeed has little impact on folding, trafficking or receptor function of the wild type protein expressed in tissue culture cells. N-glycans do, however, seem required in primary fibroblasts from human patients. Here, the presence of N-linked sugars increases the tolerance to mutations in cmg2 causing the rare genetic disease Hyaline Fibromatosis Syndrome. It thus appears that CMG2 glycosylation provides a buffer towards genetic variation by promoting folding of the protein in the ER lumen. PMID:25781883

  7. Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM

    NASA Astrophysics Data System (ADS)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren; Skoglundh, Magnus; Helveg, Stig

    2016-06-01

    The coarsening of supported palladium nanoparticles in an oxidizing atmosphere was studied in situ by means of transmission electron microscopy (TEM). Specifically, the Pd nanoparticles were dispersed on a planar and amorphous Al2O3 support and were observed during the exposure to 10 mbar technical air at 650 °C. Time-resolved TEM image series reveal that the Pd nanoparticles were immobile and that a few percent of the nanoparticles grew or shrank, indicating a coarsening process mediated by the Ostwald ripening mechanism. The TEM image contrast suggests that the largest nanoparticles tended to wet the Al2O3 support to a higher degree than the smaller nanoparticles and that the distribution of projected particle sizes consequently broadens by the appearance of an asymmetric tail toward the larger particle sizes. A comparison with computer simulations based on a simple mean-field model for the Ostwald ripening process indicates that the observed change in the particle size distribution can be accounted for by wetting of the Al2O3 support by the larger Pd nanoparticles.

  8. Automated determination of size and morphology information from soot transmission electron microscope (TEM)-generated images

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Chan, Qing N.; Zhang, Renlin; Kook, Sanghoon; Hawkes, Evatt R.; Yeoh, Guan H.; Medwell, Paul R.

    2016-05-01

    The thermophoretic sampling of particulates from hot media, coupled with transmission electron microscope (TEM) imaging, is a combined approach that is widely used to derive morphological information. The identification and the measurement of the particulates, however, can be complex when the TEM images are of low contrast, noisy, and have non-uniform background signal level. The image processing method can also be challenging and time consuming, when the samples collected have large variability in shape and size, or have some degree of overlapping. In this work, a three-stage image processing sequence is presented to facilitate time-efficient automated identification and measurement of particulates from the TEM grids. The proposed processing sequence is first applied to soot samples that were thermophoretically sampled from a laminar non-premixed ethylene-air flame. The parameter values that are required to be set to facilitate the automated process are identified, and sensitivity of the results to these parameters is assessed. The same analysis process is also applied to soot samples that were acquired from an externally irradiated laminar non-premixed ethylene-air flame, which have different geometrical characteristics, to assess the morphological dependence of the proposed image processing sequence. Using the optimized parameter values, statistical assessments of the automated results reveal that the largest discrepancies that are associated with the estimated values of primary particle diameter, fractal dimension, and prefactor values of the aggregates for the tested cases, are approximately 3, 1, and 10 %, respectively, when compared with the manual measurements.

  9. TEM in situ micropillar compression tests of ion irradiated oxide dispersion strengthened alloy

    NASA Astrophysics Data System (ADS)

    Yano, K. H.; Swenson, M. J.; Wu, Y.; Wharry, J. P.

    2017-01-01

    The growing role of charged particle irradiation in the evaluation of nuclear reactor candidate materials requires the development of novel methods to assess mechanical properties in near-surface irradiation damage layers just a few micrometers thick. In situ transmission electron microscopic (TEM) mechanical testing is one such promising method. In this work, microcompression pillars are fabricated from a Fe2+ ion irradiated bulk specimen of a model Fe-9%Cr oxide dispersion strengthened (ODS) alloy. Yield strengths measured directly from TEM in situ compression tests are within expected values, and are consistent with predictions based on the irradiated microstructure. Measured elastic modulus values, once adjusted for the amount of deformation and deflection in the base material, are also within the expected range. A pillar size effect is only observed in samples with minimum dimension ≤100 nm due to the low inter-obstacle spacing in the as received and irradiated material. TEM in situ micropillar compression tests hold great promise for quantitatively determining mechanical properties of shallow ion-irradiated layers.

  10. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures

    SciTech Connect

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-08-30

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires.

  11. Method for semiautomated serial section reconstruction and visualization of neural tissue from TEM images

    NASA Astrophysics Data System (ADS)

    Montgomery, Kevin N.; Ross, Muriel D.

    1993-07-01

    A simple method to reconstruct details of neural tissue architectures from transmission electron microscope (TEM) images will help us to increase our knowledge of the functional organization of neural systems in general. To be useful, the reconstruction method should provide high resolution, quantitative measurement, and quick turnaround. In pursuit of these goals, we developed a modern, semiautomated system for reconstruction of neural tissue from TEM serial sections. Images are acquired by a video camera mounted on TEM (Zeiss 902) equipped with an automated stage control. The images are reassembled automatically as a mosaicked section using a crosscorrelation algorithm on a Connection Machine-2 (CM-2) parallel supercomputer. An object detection algorithm on a Silicon Graphics workstation is employed to aid contour extraction. An estimated registration between sections is computed and verified by the user. The contours are then tessellated into a triangle-based mesh. At this point the data can be visualized as a wireframe or solid object, volume rendered, or used as a basis for simulations of functional activity.

  12. Novel Transrotational Solid State Order Discovered by TEM in Crystallizing Amorphous Films

    NASA Astrophysics Data System (ADS)

    Kolosov, Vladimir

    Exotic thin crystals with unexpected transrotational microstructures have been discovered by transmission electron microscopy (TEM) for crystal growth in thin (10-100 nm) amorphous films of different chemical nature (oxides, chalcogenides, metals and alloys) prepared by various methods. Primarily we use our TEM bend contour technique. The unusual phenomenon can be traced in situ in TEM column: dislocation independent regular internal bending of crystal lattice planes in a growing crystal. Such transrotation (unit cell trans lation is complicated by small rotationrealized round an axis lying in the film plane) can result in strong regular lattice orientation gradients (up to 300 degrees per micrometer) of different geometries: cylindrical, ellipsoidal, toroidal, saddle, etc. Transrotation is increasing as the film gets thinner. Transrotational crystal resembles ideal single crystal enclosed in a curved space. Transrotational micro crystals have been eventually recognized by other authors in some vital thin film materials, i.e. PCMs for memory, silicides, SrTiO3. Atomic model and possible mechanisms of the phenomenon are discussed. New transrotational nanocrystalline model of amorphous state is also proposed Support of RF Ministry of Education and Science is acknowledged.

  13. 2.5 D Transrotational Microcrystals and Nanostructures Revealed by TEM in Crystallizing Amorphous Films

    NASA Astrophysics Data System (ADS)

    Kolosov, Vladimir

    2015-03-01

    Unexpected transrotational microcrystals can be grown in thin 10-100 nm amorphous films. Crystals of different morphology (from nanowhiskers to spherulites, complex textures) and chemical nature (oxides, chalcogenides, metals and alloys) grown in thin films prepared by various methods are studied by transmission electron microscopy (TEM). We use primarily our TEM bend-contour method and SAED (HREM, AFM are also performed). The phenomenon resides in strong (up to 300 degrees/ μm) regular internal bending of crystal lattice planes in a growing crystal. It can be traced inside TEM in situ. Usual translation is complicated by slight regular rotation of the crystal unit cell (transrotation) most prominent at the mesoscale. Different geometries of transrotation of positive and negative curvature are revealed. Transrotational crystal resembles ideal single crystal enclosed in a curved space. It can be also considered similar to hypothetical endless 2.5 D analogy of MW nanotube/nano-onion halves. Transrotation is strongly increasing as the film gets thinner in the range 100-15 nm. Transrotations supplement dislocations and disclinations. New transrotational nanocrystalline model of amorphous state is proposed. Support of Ministry of Higher Education and Science is acknowledged.

  14. AFM-TEM observations of effect of ``melt'' time on polytetrafluoroethylene morphology.

    NASA Astrophysics Data System (ADS)

    Kalish, J. P.; Williams, R. A.; Wang, J.; Geil, P. H.; Long, T.-C.; Xu, P.

    2006-03-01

    TEM observations of PTFE dispersion particles dispersed on glass and held at 350 C or above for various times indicates that individual, > 0.1 mm long molecules wander individually on the substrate and can, with time in the ``melt,'' aggregate and form either flat-on or on-edge, folded chain single crystals. If ``trapped'' by cooling before aggregation, on-edge, single molecule, single crystals can form. All on-edge crystals, both individually and as the shish of shish-kebabs, have a ``double-striation'' appearance, suggested to arise from nucleation of the Pt/C shadowing material, used for the TEM image, on the folds at the top edge of the crystals. AFM observations have confirmed these suggestions and, furthermore, indicate the nascent, rod-like dispersion particles of a ``nano-emulsion,'' with a volume corresponding to a single molecule, have faceted ends. Combined with the TEM and ED observations that the molecular axis is parallel with the rod axis, not only must chain-folding occur during polymerization but the chain folds must be staggered on the end surfaces. P. H. Geil, et al., Adv. Polym. Sci., 180, 89 (2005).

  15. In Situ Environmental TEM in Imaging Gas and Liquid Phase Chemical Reactions for Materials Research.

    PubMed

    Wu, Jianbo; Shan, Hao; Chen, Wenlong; Gu, Xin; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2016-11-01

    Gas and liquid phase chemical reactions cover a broad range of research areas in materials science and engineering, including the synthesis of nanomaterials and application of nanomaterials, for example, in the areas of sensing, energy storage and conversion, catalysis, and bio-related applications. Environmental transmission electron microscopy (ETEM) provides a unique opportunity for monitoring gas and liquid phase reactions because it enables the observation of those reactions at the ultra-high spatial resolution, which is not achievable through other techniques. Here, the fundamental science and technology developments of gas and liquid phase TEM that facilitate the mechanistic study of the gas and liquid phase chemical reactions are discussed. Combined with other characterization tools integrated in TEM, unprecedented material behaviors and reaction mechanisms are observed through the use of the in situ gas and liquid phase TEM. These observations and also the recent applications in this emerging area are described. The current challenges in the imaging process are also discussed, including the imaging speed, imaging resolution, and data management.

  16. GISAXS modelling of helium-induced nano-bubble formation in tungsten and comparison with TEM

    NASA Astrophysics Data System (ADS)

    Thompson, Matt; Sakamoto, Ryuichi; Bernard, Elodie; Kirby, Nigel; Kluth, Patrick; Riley, Daniel; Corr, Cormac

    2016-05-01

    Grazing-incidence small angle x-ray scattering (GISAXS) is a powerful non-destructive technique for the measurement of nano-bubble formation in tungsten under helium plasma exposure. Here, we present a comparative study between transmission electron microscopy (TEM) and GISAXS measurements of nano-bubble formation in tungsten exposed to helium plasma in the Large Helical Device (LHD) fusion experiment. Both techniques are in excellent agreement, suggesting that nano-bubbles range from spheroidal to ellipsoidal, displaying exponential diameter distributions with mean diameters μ=0.68 ± 0.04 nm and μ=0.6 ± 0.1 nm measured by TEM and GISAXS respectively. Depth distributions were also computed, with calculated exponential depth distributions with mean depths of 8.4 ± 0.5 nm and 9.1 ± 0.4 nm for TEM and GISAXS. In GISAXS modelling, spheroidal particles were fitted with an aspect ratio ε=0.7 ± 0.1. The GISAXS model used is described in detail.

  17. Cross-sectional TEM analysis of porcelain fused to gold-coated titanium.

    PubMed

    Tanaka, Yasuhiro; Watanabe, Ikuya; Okabe, Toru

    2007-01-01

    This study investigated the interfacial microstructure between gold-coated titanium and low-fusing porcelain. The square surfaces of cast titanium split rods were sputter-coated with gold using a sputter coater at 40 mA for 1,000 seconds. Specimens were prepared for transmission electron microscopy (TEM) by cutting and polishing two pieces of the gold-coated split-rod specimens, which were glued and embedded in Cu tubes with an epoxy adhesive. TEM observation was also conducted for the gold-coated specimens after degassing and porcelain fusing. Due to the gold coating, intermetallic compounds of Au-Ti formed under the sputtered gold layer after degassing and porcelain fusing. Ti3Au and Ti3Al layers were also observed beneath the Au-Ti intermetallic compound layer. There was good adhesion of porcelain to the Au-Ti compound and Ti oxides without any gaps or formation of a Ti-deficient intermediate layer, which is normally observed at the titanium-porcelain interface. The results of this TEM study suggested that gold-sputter-coating the cast titanium surface produced a Ti-Au intermetallic compound and suppressed the formation of a Ti-deficient intermediate layer, resulting in improved adherence between porcelain and titanium.

  18. 3D TEM reconstruction and segmentation process of laminar bio-nanocomposites

    SciTech Connect

    Iturrondobeitia, M. Okariz, A.; Fernandez-Martinez, R.; Jimbert, P.; Guraya, T.; Ibarretxe, J.

    2015-03-30

    The microstructure of laminar bio-nanocomposites (Poly (lactic acid)(PLA)/clay) depends on the amount of clay platelet opening after integration with the polymer matrix and determines the final properties of the material. Transmission electron microscopy (TEM) technique is the only one that can provide a direct observation of the layer dispersion and the degree of exfoliation. However, the orientation of the clay platelets, which affects the final properties, is practically immeasurable from a single 2D TEM image. This issue can be overcome using transmission electron tomography (ET), a technique that allows the complete 3D characterization of the structure, including the measurement of the orientation of clay platelets, their morphology and their 3D distribution. ET involves a 3D reconstruction of the study volume and a subsequent segmentation of the study object. Currently, accurate segmentation is performed manually, which is inefficient and tedious. The aim of this work is to propose an objective/automated segmentation methodology process of a 3D TEM tomography reconstruction. In this method the segmentation threshold is optimized by minimizing the variation of the dimensions of the segmented objects and matching the segmented V{sub clay} (%) and the actual one. The method is first validated using a fictitious set of objects, and then applied on a nanocomposite.

  19. The importance of XRD analysis in provenance and palaeoenvironmental studies of the Piedras de Afilar Formation, Neoproterozoic of Uruguay

    NASA Astrophysics Data System (ADS)

    Pamoukaghlian, K.; Poiré, D. G.; Gaucher, C.; Uriz, N.; Cingolani, C.; Frigeiro, P.

    2009-04-01

    The Piedras de Afilar Formation crops out in the southeast part of Uruguay, forming part of the Tandilia Terrane (sensu Bossi et al. 2005). Pamoukaghlian et al. (2006) and Gaucher et al. (2008) have published δ13C, δ18O and U/Pb SHRIMP results, which indicate a Neoproterozoic age for this formation. The palaeoenvironment has been defined as a shallow marine platform based on the presence of interference ripples, hummocky and mega-hummocky cross-stratification. X-ray diffraction (XRD) analyses help to better constrain the palaeoenvironment: the presence of chlorite/smectite found in black shales, suggest a reducing environment, and abundant illite indicates a cold to temperate climate. Provenance studies have been undertaken that utilise a combination of detailed palaeocurrent measurements, petrographic descriptions, XRD analyses, and geochemical isotopic analyses, including U/Pb SHRIMP determinations. Mineral compositional diagrams for sandstones suggest a stable cratonic provenance. Palaeocurrents are mainly from the NNE, indicating a provenance from the cratonic areas of the Tandilia Terrane. The illite crystal index indicates diagenetic to low-metamorphic conditions for the sequence; this is important to confirm that the identified minerals are authigenic. Clay minerals identified by XRD analysis of sandstones from the siliciclastic member are illite (80 - 90%), kaolinite (5 - 10%), and chlorite (5 - 10%). This is consistent with a provenance from the cratonic areas (quartz-feldspar dominated rock types). Isotopic analyses have been undertaken to provide better constraints on the tectonic setting. U/Pb SHRIMP ages for the youngest zircons are 990 Ma (Gaucher et al. 2008), and the basal granite (Granito de la Paz) is 2056 ± 11 Ma (Hartmann et al. 2001), suggesting a provenance from the Archaean basement for the Piedras de Afilar Formation, like its counterparts in the Rio de la Plata Craton. References Bossi, J., Piñeyro, D., Cingolani, C. (2005). El l

  20. Multivariate analysis of DSC-XRD simultaneous measurement data: a study of multistage crystalline structure changes in a linear poly(ethylene imine) thin film.

    PubMed

    Kakuda, Hiroyuki; Okada, Tetsuo; Otsuka, Makoto; Katsumoto, Yukiteru; Hasegawa, Takeshi

    2009-01-01

    A multivariate analytical technique has been applied to the analysis of simultaneous measurement data from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) in order to study thermal changes in crystalline structure of a linear poly(ethylene imine) (LPEI) film. A large number of XRD patterns generated from the simultaneous measurements were subjected to an augmented alternative least-squares (ALS) regression analysis, and the XRD patterns were readily decomposed into chemically independent XRD patterns and their thermal profiles were also obtained at the same time. The decomposed XRD patterns and the profiles were useful in discussing the minute peaks in the DSC. The analytical results revealed the following changes of polymorphisms in detail: An LPEI film prepared by casting an aqueous solution was composed of sesquihydrate and hemihydrate crystals. The sesquihydrate one was lost at an early stage of heating, and the film changed into an amorphous state. Once the sesquihydrate was lost by heating, it was not recovered even when it was cooled back to room temperature. When the sample was heated again, structural changes were found between the hemihydrate and the amorphous components. In this manner, the simultaneous DSC-XRD measurements combined with ALS analysis proved to be powerful for obtaining a better understanding of the thermally induced changes of the crystalline structure in a polymer film.

  1. Weathering and hydrothermal alteration of basalts in Iceland: mineralogy from VNIR, TIR, XRD, and implications for Mars

    NASA Astrophysics Data System (ADS)

    Ehlmann, B. L.; Mustard, J. F.; Bish, D. L.

    2009-12-01

    thomsonite, basalts with silica/quartz-bearing veins, basalts bearing celadonite, and basalts partially altered to montmorillonite, Fe/Mg smectite, or mixed smectite-chlorite. Analyses included: (1) measurement of reflectance spectra of the whole rock by the ASD; (2) measurement of VNIR and TIR spectra in RELAB of particle-size separates (<25um and <125um) derived from the bulk rock and from precipitated minerals extracted from the vesicles; (3) measurement of X-ray diffraction (XRD) patterns, including quantitative XRD; and (4) electron microprobe chemical analyses. These data emulate orbital data from CRISM, OMEGA, and TES, which detect the infrared active components, linked to in-situ data on whole rock modal mineralogy such as will be measured by the ChemMin instrument on the MSL rover.

  2. Diagnosis of the heating effect on the electrical resistivity of Ouargla (Algeria) dunes sand using XRD patterns and FTIR spectra

    NASA Astrophysics Data System (ADS)

    Mechri, Mohammed Laïd; Chihi, Smaïl; Mahdadi, Naouia; Beddiaf, Samiha

    2017-01-01

    XRD patterns and FTIR spectra have shown that dunes sand of Ouargla's region, in its natural state, is formed of a high percentage of quartz, gypsum and very low percentage of kaolinite and hematite, in addition to some organic compounds. The electrical resistivity of the natural sand has been measured, it was 6 × 1014 Ω cm. Six samples of the sand were heated separately at 200, 400, 600, 800, 1000 and 1200 °C. The XRD patterns and FTIR spectra of these samples were carried out. On the other hand, the electrical resistivities of these samples have been measured. The change of the electrical resistivity with heat shows a nonlinear behavior. The heated sample of sand at 200 °C has lost some water. Most of the gypsum in the 200 °C heated sample has transformed into anhydrite, and the rest has transformed into bassanite, and its electrical resistivity has fallen down to 3.5 × 1014 Ω cm. By heating at 400 °C, the gypsum has lost all its water and it has transformed entirely to anhydrite, and its electrical resistivity became 6.75 × 1012 Ω cm, it has the lowest measured resistivity. At 600 °C and 800 °C, in addition to anhydrite, the kaolinite transformed to meta-kaolin due to the continuous breaking of OH bond and formation of water vapor, and the electrical resistivity increased to (1.5-1.9) × 1014 Ω cm. Heating at 1000 °C leads to the initiation of the interaction between anhydrite and quartz, the wollastonite appears, and the meta-kaolin transforms to aluminum-silicon and cristobalite. The wollastonite is a good electrical insulator. It raises the electrical resistivity of sand to 2.6 × 1014 Ω cm. The heating at 1200 °C makes all anhydrite to interact with quartz due to the increasing of volume of wollastonite, the anhydrite disappears completely, the quartz transforms into cristobalite. The cristobalite increases due to the dissociation of aluminium-silicon into mullite and cristobalite, as well as the transformation of quartz into cristobalite at

  3. On the structural affinity of macromolecules with different biological properties: Molecular dynamics simulations of a series of TEM-1 mutants

    SciTech Connect

    Giampaolo, Alessia Di; Mazza, Fernando; Daidone, Isabella; Amicosante, Gianfranco; Perilli, Mariagrazia; Aschi, Massimiliano

    2013-07-12

    Highlights: •We have performed molecular dynamics simulations of TEM-1 mutants. •Mutations effects on the mechanical properties are considered. •Mutants do not significantly alter the average enzymes structure. •Mutants produce sharp alterations in enzyme conformational repertoire. •Mutants also produce changes in the active site volume. -- Abstract: Molecular Dynamics simulations have been carried out in order to provide a molecular rationalization of the biological and thermodynamic differences observed for a class of TEM β-lactamases. In particular we have considered the TEM-1(wt), the single point mutants TEM-40 and TEM-19 representative of IRT and ESBL classes respectively, and TEM-1 mutant M182T, TEM-32 and TEM-20 which differ from the first three for the additional of M182T mutation. Results indicate that most of the thermodynamic, and probably biological behaviour of these systems arise from subtle effects which, starting from the alterations of the local interactions, produce drastic modifications of the conformational space spanned by the enzymes. The present study suggests that systems showing essentially the same secondary and tertiary structure may differentiate their chemical–biological activity essentially (and probably exclusively) on the basis of the thermal fluctuations occurring in their physiological environment.

  4. Single crystal XRD structure and theoretical analysis of the chiral Au30S(S-t-Bu)18 cluster.

    PubMed

    Crasto, David; Malola, Sami; Brosofsky, Grace; Dass, Amala; Häkkinen, Hannu

    2014-04-02

    Au30S(S-t-Bu)18 cluster, related closely to the recently isolated "green gold" compound Au30(S-t-Bu)18, has been structurally solved via single-crystal XRD and analyzed by density functional theory calculations. The molecular protecting layer shows a combination of monomeric (RS-Au-SR) and trimeric (RS-Au-SR-Au-SR-Au-SR) gold-thiolate units, bridging thiolates, and a single sulfur (sulfide) in a novel μ3-coordinating position. The chiral gold core has a geometrical component that is identical to the core of the recently reported Au28(SPh-t-Bu)20. Both enantiomers of Au30S(S-t-Bu)18 are found in the crystal unit cell. The calculated CD spectrum bears a close resemblance to that of Au28(SPh-t-Bu)20. This is the first time when two structurally characterized thiol-stabilized gold clusters are found to have such closely related metal core structures and the results may increase understanding of the formation of gold clusters when stabilized by bulky thiolates.

  5. Influence of temperature on layer growth as measured by in situ XRD observation of nitriding of austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Manova, D.; Günther, C.; Bergmann, A.; Mändl, S.; Neumann, H.; Rauschenbach, B.

    2013-07-01

    Investigating the formation of expanded austenite has resulted in several, different models trying to explain the particular diffusion and phase formation behaviour. However, only ex situ information, influenced by cooling and annealing processes of the samples after ion implantation has been available until now. Here, the time and temperature dependent layer growth is reported using in situ XRD measurements obtained from low energy broadbeam nitrogen ion implantation into polycrystalline austenitic stainless steel 304 in the temperature range from 300 to 500 °C for a process time of up to 1 h. Expanded austenite was observed at all temperatures without any CrN, in agreement with already published lifetime data for this metastable phase. The layer growth was derived from the time evolution of the substrate peak intensity. Using the temperature dependence of the layer growth, an activation energy of nearly 0.8 eV was estimated for the nitrogen diffusion. In contrast, a complex behaviour was observed for the lattice expansion and peak width of the expanded peak, indicating additional dynamic annealing during implantation.

  6. XRD analysis of undoped and Fe doped TiO{sub 2} nanoparticles by Williamson Hall method

    SciTech Connect

    Bharti, Bandna; Barman, P. B.; Kumar, Rajesh

    2015-08-28

    Undoped and Fe doped titanium dioxide (TiO{sub 2}) nanoparticles were synthesized by sol-gel method at room temperature. The synthesized samples were annealed at 500°C. For structural analysis, the prepared samples were characterized by X-ray diffraction (XRD). The crystallite size of TiO{sub 2} and Fe doped TiO{sub 2} nanoparticles were calculated by Scherer’s formula, and was found to be 15 nm and 11 nm, respectively. Reduction in crystallite size of TiO{sub 2} with Fe doping was observed. The anatase phase of Fe-doped TiO{sub 2} nanoparticles was also confirmed by X-ray diffraction. By using Williamson-Hall method, lattice strain and crystallite size were also calculated. Williamson–Hall plot indicates the presence of compressive strain for TiO{sub 2} and tensile strain for Fe-TiO{sub 2} nanoparticles annealed at 500°C.

  7. Structural studies with the use of XRD and Mössbauer spectroscopy of new high Manganese steels

    NASA Astrophysics Data System (ADS)

    Jablonska, Magdalena Barbara

    2014-04-01

    New high-strength austenitic and austenitic-ferritic manganese steels represent a significant potential in applications for structural components in the automotive and railway industry due to the excellent combination of high mechanical properties and good plasticity. They belong to the group of steels called AHSS (Advanced High Strength Steels) and UHSS (Ultra High Strength Steels). Application of this combination of properties allows a reduction in the weight of vehicles by the use of reduced cross-section components, and thus to reduce fuel consumption. The development and implementation of industrial production of such interesting and promising steel and its use as construction material requires an improvement of their casting properties and susceptibility to deformation in plastic working conditions. In this work, XRD, Transmission Mössbauer Spectroscopy and Conversion Electron Mössbauer Spectroscopy were employed in a study of the new high-manganese steels with a austenite and austenite-ferrite structure. The influence of the plastic deformation parameters on the changes in the structure, distribution of ferrite and disclosure of the presence of carbides was determined. The analysis of phase transformations in various times using CEMS method made possible to reveal their fine details.

  8. Mechanical properties and XRD studies of silicon carbide inert matrix fuel fabricated by a low temperature polymer precursor route

    NASA Astrophysics Data System (ADS)

    Shih, Chunghao; Rohbeck, Nadia; Gopalakrishnan, Karthik; Tulenko, James S.; Baney, Ronald H.

    2013-01-01

    The mechanical properties of silicon carbide (SiC) inert matrix fuel (IMF) pellets fabricated by a low temperature (1050 °C) polymer precursor route were evaluated at room temperature. The Vickers hardness was mainly related to the chemical bonding strength between the amorphous SiC phase and the β-SiC particles. The biaxial fracture strength with pre-notch and fracture toughness were found to be mostly controlled by the pellet density. The maximum Vickers hardness, biaxial fracture strength with pre-notch and fracture toughness achieved were 5.6 GPa, 201 MPa and 2.9 MPa m1/2 respectively. These values appear to be superior to the reference MOX or UO2 fuels. Excellent thermal shock resistance for the fabricated SiC IMF was proven and the values were compared to conventional UO2 pellets. XRD studies showed that ceria (PuO2 surrogate) chemically reacted with the polymer precursor during sintering, forming cerium oxysilicate. Whether PuO2 will chemically react in a similar manner remains unclear.

  9. Composite uranium carbide targets at TRIUMF: Development and characterization with SEM, XRD, XRF and L-edge densitometry

    NASA Astrophysics Data System (ADS)

    Kunz, Peter; Bricault, Pierre; Dombsky, Marik; Erdmann, Nicole; Hanemaayer, Vicky; Wong, John; Lützenkirchen, Klaus

    2013-09-01

    The production of radioactive ion beams (RIB) from spallation targets by irradiation with a continuous 500 MeV proton beam, has been routine at TRIUMF for several years. Based on the experience with composite refractory carbide targets a procedure for the fabrication of UC2/C targets was developed. It includes the preparation of UC2 by carbothermal reduction of UO2, the slip-casting of fine-grained UC2/C slurry on graphite foil under inert gas atmosphere and the cutting of composite target discs which are stacked up to a lamellar structure. The thermal properties of such an arrangement are adequate to withstand the high power deposition of an intense, continuous proton beam and also beneficial for the fast release of short-lived radioactive isotopes. Molecular structure, particle size and the impact of sintering of the target discs were investigated via XRD and SEM. Thickness and mass distribution were measured with position-sensitive LIII-edge densitometry. The results confirm that the properties of the UC2/C target material are well suited for RIB production at TRIUMF while there is still room for improvement with regard to uniformity of mass distribution in target disc thickness.

  10. Simplified Procedure for Estimating Epitaxy of La2Zr2O7-Buffered NiW RABITS Using XRD

    SciTech Connect

    Rikel, Mark O.; Isfort, Dirk; Klein, Marcel; Ehrenberg, Jurgen; Bock, Joachim; Specht, Eliot D; Sun-Wagener, Ming; Weber, Oxana; Sporn, Dieter; Engel, Sebastian; de Haas, Oliver; Semerad, Robert; Schubert, Margitta; Holzapfel, Bernhard

    2009-01-01

    Abstract A procedure is developed for assessing the epitaxy of La(2-x)Zr(2+x)O(7) (LZO) layers on NiW RABITS. Comparing XRD patterns (theta / 2-theta scans and 2D rocking curves) of LZO films of known thickness (ellipsometry or reflectometry measurements) with those of standard samples (100% epitaxial LZO film and an isotropic LZO pellet of known density), we estimate the epitaxial (EF), and polycrystalline (PF) fractions of LZO within the layer. The procedure was tested using MOD-LZO(100 nm)/NiW tape samples with varied from 3 to 90% (reproducibly prepared by varying the humidity of Ar-5%H2 gas during heat treatment). A qualitative agreement with RHEED and quantitative (within 10%) agreement with the EBSD results was shown. Correlation between EF and Jc in 600 nm thick YBCO layer deposited on MOD-LZO/NiW using thermal coevaporation enables us to impose the EF=80% margin on the quality of LZO layer for the particular conductor architecture.

  11. Structural Consequences of the Inhibitor-Resistant Ser130Gly Substitution in TEM β-Lactamase†‡

    PubMed Central

    Thomas, Veena L.; Golemi-Kotra, Dasantila; Kim, Choonkeun; Vakulenko, Sergei B.; Mobashery, Shahriar; Shoichet, Brian K.

    2006-01-01

    β-Lactamase confers resistance to penicillin-like antibiotics by hydrolyzing their β-lactam bond. To combat these enzymes, inhibitors covalently cross-linking the hydrolytic Ser70 to Ser130 were introduced. In turn, mutant β-lactamases have emerged with decreased susceptibility to these mechanism-based inhibitors. Substituting Ser130 with glycine in the inhibitor-resistant TEM (IRT) mutant TEM-76 (S130G) prevents the irreversible cross-linking step. Since the completely conserved Ser130 is thought to transfer a proton important for catalysis, its substitution might be hypothesized to result in a nonfunctional enzyme; this is clearly not the case. To investigate how TEM-76 remains active, its structure was determined by X-ray crystallography to 1.40 Å resolution. A new water molecule (Wat1023) is observed in the active site, with two configurations located 1.1 and 1.3 Å from the missing Ser130 Oγ; this water molecule likely replaces the Ser130 side-chain hydroxyl in substrate hydrolysis. Intriguingly, this same water molecule is seen in the IRT TEM-32 (M69I/M182T), where Ser130 has moved significantly. TEM-76 shares other structural similarities with various IRTs; like TEM-30 (R244S) and TEM-84 (N276D), the water molecule activating clavulanate for cross-linking (Wat1614) is disordered (in TEM-30 it is actually absent). As expected, TEM-76 has decreased kinetic activity, likely due to the replacement of the Ser130 side-chain hydroxyl with a water molecule. In contrast to the recently determined structure of the S130G mutant in the related SHV-1 β-lactamase, in TEM-76 the key hydrolytic water (Wat1561) is still present. The conservation of similar accommodations among IRT mutants suggests that resistance arises from common mechanisms, despite the disparate locations of the various substitutions. PMID:15981999

  12. First application of time-domain electromagnetic technology (TEM) for permafrost mapping on the Arctic shelf.

    NASA Astrophysics Data System (ADS)

    Koshurnikov, A.; Gunar, A.; Tumskoy, V. E.; Shakhova, N. E.; Semiletov, I. P.; Valuyskiy, S.

    2015-12-01

    Different geophysical methods are used to study and map submarine permafrost on the Arctic Shelf. Due to specific features of submarine permafrost, none of geophysical methods can provide conclusive data when gas-charged sediments and taliks occur within permafrost. Experimental data show that electrical properties of frozen grounds change significantly. For example, depending on ground lithology and wetness, electrical resistivity can increase up to 103 times upon freezing. Thus, electromagnetic methods could be considered more informative and valuable tool for characterizing subsea permafrost. Investigation of submarine permafrost on the shallow Arctic Shelf requires modifications of electromagnetic methods to cover specific needs of working from the fast ice. Winter expeditions devoted to subsea permafrost investigations were performed in March-April of 2012-2015 in the near-shore area of the Laptev Sea. TEM was applied to predict permafrost down to 1 km depth. TEM systems are advantageous when many stations are required, because many short deployments can be performed in a single survey. Working from the fast ice allowed collection of few tens of stations to cover the entire polygon. Interpretation of data collected in 2012 allowed to predict position of the permafrost table near-shore near Muostakh Island, which was validated by followed up permafrost drilling. Surveys performed in 2013-2015 also confirmed good agreement between electromagnetic data and observational data obtained by drilling. Accuracy of the methods reached 3.5%. Note, that in March-April of 2014 and 2015, we used the modified TEM which allows obtaining continuous subsea permafrost table profiles.

  13. Systematic mutagenesis of the active site omega loop of TEM-1 beta-lactamase.

    PubMed Central

    Petrosino, J F; Palzkill, T

    1996-01-01

    Beta-Lactamase is a bacterial protein that provides resistance against beta-lactam antibiotics. TEM-1 beta-lactamase is the most prevalent plasmid-mediated beta-lactamase in gram-negative bacteria. Normally, this enzyme has high levels of hydrolytic activity for penicillins, but mutant beta-lactamases have evolved with activity toward a variety of beta-lactam antibiotics. It has been shown that active site substitutions are responsible for changes in the substrate specificity. Since mutant beta-lactamases pose a serious threat to antimicrobial therapy, the mechanisms by which mutations can alter the substrate specificity of TEM-1 beta-lactamase are of interest. Previously, screens of random libraries encompassing 31 of 55 active site amino acid positions enabled the identification of the residues responsible for maintaining the substrate specificity of TEM-1 beta-lactamase. In addition to substitutions found in clinical isolates, many other specificity-altering mutations were also identified. Interestingly, many nonspecific substitutions in the N-terminal half of the active site omega loop were found to increase ceftazidime hydrolytic activity and decrease ampicillin hydrolytic activity. To complete the active sight study, eight additional random libraries were constructed and screened for specificity-altering mutations. All additional substitutions found to alter the substrate specificity were located in the C-terminal half of the active site loop. These mutants, much like the N-terminal omega loop mutants, appear to be less stable than the wild-type enzyme. Further analysis of a 165-YYG-167 triple mutant, selected for high levels of ceftazidime hydrolytic activity, provides an example of the correlation which exists between enzyme instability and increased ceftazidime hydrolytic activity in the ceftazidime-selected omega loop mutants. PMID:8606154

  14. Geological Hypothesis Testing and Investigations of Coupling with Transient Electromagnetics (TEM)

    NASA Astrophysics Data System (ADS)

    Adams, A. C.; Moeller, M. M.; Snyder, E.; Workman, E. J.; Urquhart, S.; Bedrosian, P.; Pellerin, L.

    2014-12-01

    Transient electromagnetic (TEM) data were acquired in Borrego Canyon within the Santo Domingo Basin of the Rio Grande Rift, central New Mexico, during the 2014 Summer of Applied Geophysical Experience (SAGE) field program. TEM surveys were carried out in several regions both to investigate geologic structure and to illustrate the effects of coupling to anthropogenic structures. To determine an optimal survey configuration, 50, 100 and 200 m square transmitter loops were deployed; estimates of depth-of-investigation and logistical considerations determined that 50 m loops were sufficient for production-style measurements. A resistive (100s of ohm-m) layer was identified at a depth of 25-75 m at several locations, and interpreted as dismembered parts of one or more concealed volcanic flows, an interpretation consistent with Tertiary volcanic flows that cap the Santa Anna Mesa immediately to the south. TEM soundings were also made across an inferred fault to investigate whether fault offset is accompanied by lateral changes in electrical resistivity. Soundings within several hundred meters of the inferred fault strand were identical, indicating no resistivity contrast across the fault, and possibly an absence of recent activity. An old windmill and water tank, long-abandoned, offered an excellent laboratory to study the effect of coupling to metallic anthropogenic structures. The character of the measured data strongly suggests the water tank is in electrical contact with the earth (galvanic coupling), and an induced response was persistent to more than 1 second after current turn-off. Coupling effects could be identified at least 150 meters from the tank. Understanding the mechanism behind such coupling and the ability to identify coupled data are critical skills, as one-dimensional modeling of data is affected by such coupling producing artificial conductive layers at depth.

  15. High Spatial Resolution Study of Microbe-Carbonate-Silicate Interfaces by FIB and TEM

    NASA Astrophysics Data System (ADS)

    Benzerara, K.; Menguy, N.; Guyot, F.; Vanni, C.; Gillet, P.

    2003-12-01

    High resolution transmission electron microscopy (HRTEM), chemical micro-analysis (EDX) and electron energy loss spectroscopy (EELS) are among the most powerful analytical techniques for studying microbe-mineral interactions, allowing to observe the microbe-mineral interface at almost the angstrom scale, to evidence transformations of the mineral structure and chemical alterations at the nanometer scale. However, the samples must be very thin and only a small area can be investigated. A key limitation for using this technique is thus to prepare natural geomicrobiological samples which combine hard minerals, preventing use of ultramicrotomy, with soft organic matter inadequate to ion milling procedures. Additionaly the areas of interest are usually restricted to few micrometer large areas which have to be selected from macroscopic samples. In this study we present two procedures : micromanipulation and FIB (Focused Ion Beam) which allow the study of microbe-mineral interfaces with TEM. The micromanipulation procedure has been presented in Benzerara et al (2003, PNAS). We have evidenced nannobacteria-like objects at the surface of the Tatahouine orthopyroxenite meteorite fallen in the tunisian desert in 1931. SEM observations suggest a complex interaction pattern between the nannobacteria-like objects, the pyroxene and microorganisms which have colonized the surface of the meteorite during its seventy years of residence on Earth. The TEM study on the very same area shows that the nannobacteria-like rods are actually well-crystallized nanometric calcite single crystals surrounded by an amorphous layer of carbonate composition. Those morphologies and structures are unusual for calcite single crystals. We discuss these observations in regard to the criteria of biogenicity i.e. biosignatures. Moreover, we examine the implications for carbonate production associated to silicate bio-weathering under aridic conditions. This work is relevant both to astrobiological and

  16. Soot Precursor Material: Visualization Via Simultaneous LIF-LII and Characterization Via TEM

    NASA Technical Reports Server (NTRS)

    VanderWal, Randall L.

    1996-01-01

    Simultaneous combined laser-induced fluorescence and laser-induced incandescence (LIF-LII) images are presented for both a normal and inverse diffusion flame. The excitation wavelength dependence distinguishes the LIF and LII signals in images from the normal diffusion flame while the temporal decay distinguishes the signals in images of the inverse diffusion flame. Each flame presents a minimum in the combined LIF-LII intensity in a region separating the fuel pyrolysis and soot containing regions. Opacity, geometric in definition, and extent of crystallinity measured through both bright and dark field Transmission Electron Microscopy (TEM) characterizes the thermophoretically sampled material from within this minimal LIF-LII intensity region. TEM analysis reveals rather different soot processes occurring within the normal and inverse diffusion flame. In the normal diffusion flame, rapid chemical and physical coalescence of PAHs results in initial formation of soot precursor particles that are highly crystalline and evolve toward fully formed soot. In the inverse diffusion flame, rapid coalescence of pyrolysis products occurs, producing tarlike, globular structures equivalent in size to fully formed soot aggregates but with markedly less crystallinity than normal-appearing soot. These different material properties are interpreted as reflecting different relative rates of chemical and physical coalescence of fuel pyrolysis products versus carbonization. Significantly, these TEM images support qualitative photophysical arguments suggesting that, in general, this 'dark' region observed in the LIF-LII images demarcates a transitional region in which a fundamental change in the material the material chemical/physical properties occurs between solid carbonaceous soot and condensed or gaseous molecular growth material.

  17. In-Situ TEM-STM Observations of SWCNT Ropes/Tubular Transformations

    NASA Technical Reports Server (NTRS)

    Sola, F.; Lebron-Colon, M.; Ferreira, P. J.; Fonseca, L. F.; Meador, M. A.; Marin, C.

    2010-01-01

    Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.

  18. Tantalum oxide nanoscale resistive switching devices: TEM/EELS study (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Norris, Kate J.; Zhang, Jiaming; Merced-Grafals, Emmanuelle; Musunuru, Srinitya; Zhang, Max; Samuels, Katy; Yang, Jianhua J.; Kobayashi, Nobuhiko P.

    2015-08-01

    The field of non-volatile memory devices has been boosted by resistive switching, a reversible change in electrical resistance of a dielectric layer through the application of a voltage potential. Tantalum oxide being one of the leading candidates for the dielectric component of resistance switching devices was investigated in this study. 55nm TaOx devices in all states were compared through cross sectional TEM techniques including HRTEM, EELS, and EFTEM and will be discussed in this presentation. Based on the chemical and physical features found in the cross sectioned nanodevices we will discuss the switching mechanism of these nanoscale devices.

  19. Comparison of ion milling techniques for cross-sectional TEM of semiconductors

    NASA Astrophysics Data System (ADS)

    Luck, J. T.; Boggs, C. W.; Pennycook, S. J.

    1985-03-01

    The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving with the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.

  20. Microorganisms found in secondary cataract material of ECCE patients, a study with SEM and TEM.

    PubMed

    Kalicharan, D; Jongebloed, W L; Los, L I; Worst, J G

    1993-01-01

    Globular secondary cataract material, removed from 24 patients with ECCE after ophthalmic cleaning of the anterior capsule, were investigated with SEM and TEM. Besides spherical, somewhat oval shaped bodies of various shape and size comparable with those found in cataractous lenses, (an)aerobic bacteria and yeast cells were found in approximately 70% of the cases, all of them in eyes without intra-ocular inflammation. Probably these bacteria have been transferred from the conjunctiva during IOL.-implantation and were encapsulated without starting an inflammation.

  1. Effect of displacement damage on the stability of oxide nanoparticles in model ODS alloys: TEM studies

    SciTech Connect

    Santra, Sumita; Balaji, S.; Panigrahi, B. K.; Serruys, Yves; Robertson, C.; Ana, Alamo; Sundar, C. S.

    2012-06-05

    Model ODS alloy containing Fe-0.3% yttria was prepared by ball milling and hipping at high temperature and the effect of irradiation on stability of yttria nanoclusters in model ODS alloy is studied by dual beam ion irradiation using 5 MeV Fe{sup +} and 1.5 MeV He{sup +} ions. TEM studies on irradiated sample show that these particles are stable at 25 dpa and 40 appm He concentration. However, at 80 dpa and 360 appm He concentration Yttria particles were found to be unstable as evidenced from increase in average particle size and particle size distribution.

  2. Estimation of the electron beam energy spread for TEM information limit

    SciTech Connect

    O'Keefe, Michael A.; Tiemeijer, Peter C.; Sidorov, Maxim V.

    2002-02-20

    Sub-Angstrom TEM of materials requires focal-series reconstruction (FSR) or electron holography to retrieve the electron wave at the specimen exit-surface to very high resolution. As a consequence, we need to measure the microscope information limit. With a sub-Angstrom information limit, the one-Angstrom microscope (OAM) project at the NCEM has achieved sub-Angstrom resolution by FSR. We present a new method of estimating the information limit of the microscope, based on energy-spread measurements with an image filter.

  3. A Survey of Jet Aircraft PM by TEM in APEX III

    NASA Technical Reports Server (NTRS)

    VanderWal, Randy L.; Bryg, Victoria M.

    2014-01-01

    Based upon field testing during the NASA led APEX III campaign conducted in November 2005 at the NASA Glenn Research Center in coordination with Continental Airlines and Cleveland Hopkins International Airport. This paper reports observations of particulate emissions collected from a suite of jet engine aircraft to assess differences and similarities in soot macro- micro- and nanostructure using transmission electron microscopy (TEM). Aggregates are compact, primary particle sizes varied and nanostructure mixed. Comparisons are made to more familiar laboratory flame-generated soot as a well-studied point of reference. Results are interpreted in terms of turbulence interacting with the different stages of particle formation and growth.

  4. Thermophysical ESEM and TEM Characterization of Carbon Fibers CTE, Spectroscopy and Roughness Studies at High Temperatures

    NASA Technical Reports Server (NTRS)

    Ochoa, Ozden O.

    2004-01-01

    Accurate determination of the transverse properties of carbon fibers is important for assessment and prediction of local material as well as global structural response of composite components. However the measurements are extremely difficult due to the very small diameters of the fibers (few microns only) and must be conducted within a microscope. In this work, environmental scanning electron microscope (ESEM) and transmission electron microscope (TEM) are used to determine the transverse coefficient of thermal expansion of different carbon fibers as a function of temperature.

  5. A survey of jet aircraft PM by TEM in APEX III

    NASA Astrophysics Data System (ADS)

    Huang, Chung-Hsuan; Bryg, Victoria M.; Vander Wal, Randy L.

    2016-09-01

    Results are reported for sampling non-volatile particulate matter from field tests during the NASA led APEX III campaign. This paper reports observations of particulate emissions collected from a suite of jet engine aircraft to assess differences and similarities in soot macro- micro- and nanostructure using TEM. Aggregates are compact, primary particle sizes varied and nanostructure is mixed. Comparisons are made to soot from a laboratory flame as a well-studied reference. Results are interpreted in terms of turbulence interacting with the different stages of particle formation and growth with implications for atmospheric processing and climate impact.

  6. Drill Core Mineral Analysis by Means of the Hyperspectral Imaging Spectrometer HySpex, XRD and Asd in Proximity of the MÝTINA Maar, Czech Republic

    NASA Astrophysics Data System (ADS)

    Koerting, F.; Rogass, C.; Kaempf, H.; Lubitz, C.; Harms, U.; Schudack, M.; Kokaly, R.; Mielke, C.; Boesche, N.; Altenberger, U.

    2015-12-01

    Imaging spectroscopy is increasingly used for surface mapping. Therefore different expert systems are being utilized to identify surface cover materials. Those expert systems mainly rely on the spectral comparison between unknown and library spectra, but their performances were only limited qualified. This study aims on the comparative analysis of drill core samples from the recently discovered maar system in the Czech Republic. Drill core samples from the surrounding area of the Mýtina maar were analyzed by X-Ray diffraction (XRD) and the hyperspectral spectrometer HySpex. Additionally, soil samples were measured in-situ by the ASD FieldSpec4 and in the laboratory by the HySpex VNIR/SWIR spectrometer system. The data was then analyzed by the MICA-algorithm and the results were compared to the results of the XRD -analysis. The XRD-analysis served here as validation basis. The results of the hyperspectral and the XRD analyses were used to densify a volcanic map that also integrates in-situ soil measurements in the surrounding area of Mýtina. The comparison of the XRD- and solaroptical remote sensing results showed a good correlation of qualified minerals if the soil organic carbon content was significantly low. Contrary to XRD, smectites and muscovites were also straightforward identified that underlines the overall performance of the approach to identify minerals. Basically, in this work an operable approach is proposed that enables the fast, repeatable and detailed analysis of drill cores, drill core samples and soil samples and, hence, provides a higher performance than state-of-the-art XRD-analyses.

  7. Feasibility of central loop TEM method for prospecting multilayer water-filled goaf

    NASA Astrophysics Data System (ADS)

    Yan, Shu; Xue, Gou-Qiang; Qiu, Wei-Zhong; Li, Hai; Zhong, Hua-Sen

    2016-12-01

    With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic (TEM) method is favorable for prospecting conductive layers because of the coupling relationship between its field structure and formation. However, the shielding effect of conductive overburden would not only require a longer observation time when prospecting the same depth but also weaken the anomalous response of underlying layers. Through direct time domain numerical simulation and horizontal layered earth forward modeling, this paper estimates the length of observation time required to prospect the target, and the distinguishable criterion of multilayer water-filled goaf is presented with observation error according to the effect of noise on observation data. The observed emf curves from Dazigou Coal Mine, Shanxi Province can distinguish multilayer water-filled goaf. In quantitative inversion interpretation of observed curves, using electric logging data as initial parameters restrains the equivalence caused by coal formation thin layers. The deduced three-layer and two-layer water-filled goafs are confirmed by the drilling hole. The result suggests that when observation time is long enough and with the anomalous situation of underlying layers being greater than the observation error, the use of the central loop TEM method to prospect a multilayer water-filled goaf is feasible.

  8. Characterizing size and porosity of hollow nanoparticles: SAXS, SANS, TEM, DLS, and adsorption isotherms compared.

    PubMed

    Chen, Zhi Hong; Kim, Chanhoi; Zeng, Xiang-bing; Hwang, Sun Hye; Jang, Jyongsik; Ungar, Goran

    2012-10-30

    A combination of experimental methods, including transmission and grazing incidence small-angle X-ray scattering (SAXS and GISAXS), small-angle neutron scattering (SANS), transmission electron microscopy (TEM), dynamic light scattering (DLS), and N(2) adsorption-desorption isotherms, was used to characterize SiO(2)/TiO(2) hollow nanoparticles (HNPs) of sizes between 25 and 100 nm. In the analysis of SAXS, SANS, and GISAXS data, the decoupling approximation and the Percus-Yevick structure factor approximation were used. Brunauer-Emmett-Teller, t-plot, and a spherical pore model based on Kelvin equation were applied in the treatment of N(2) isotherms. Extracted parameters from the scattering and TEM methods are the average outer and inner diameters and polydispersity. Good agreement was achieved between different methods for these extracted parameters. Merits, advantages, and disadvantages of the different methods are discussed. Furthermore, the combination of these methods provided us with information on the porosity of the shells of HNPs and the size of intrawall pores, which are critical to the applications of HNPs as drug delivery vehicles and catalyst supports.

  9. High-resolution methane emission estimates using the InTEM inversion system

    NASA Astrophysics Data System (ADS)

    Connors, S.; Manning, A.; Robinson, A. D.; Riddick, S. N.; Forster, G.; Oram, D.; O'Doherty, S.; Harris, N. R. P.

    2014-12-01

    There is a growing need for comparisons between emission estimates produced using bottom-up and top-down techniques at high spatial resolution. In response to this, an inversion approach, InTEM, was adapted to estimate methane emissions for a region in the South East of the UK (~100 x 150 km). We present results covering a 2-year period (July 2012 - July 2014) in which atmospheric methane concentrations were recorded at 1 - 2 minute time-steps at four locations within the region of interest. Precise measurements were obtained using gas chromatography with flame ionisation detection (GC-FID) for all sites except one, which used a PICARRO Cavity Ring-Down Spectrometer (CRDS). These observations, along with the UK Met Office's Lagrangian particle dispersion model (NAME) were used within InTEM to produce the methane emission fields. Emission estimates were produced at varying spatial resolutions, for annual and seasonal time frames . We present results indicating the optimum number of observation sites required for this region, and how this can affect our uncertainty estimates. These results are compared with the UK National Atmospheric Emissions Inventory (NAEI) which is compiled using bottom-up methods and available at 1x1 km resolution. To our knowledge, no inversion technique has been implemented on such a fine spatial resolution. This is a pilot project which, given proof of concept, could be scaled up as an alternative method for producing national scale emission inventories.

  10. Methods for TEM analysis of NIST's single-walled carbon nanotube Standard Reference Material

    NASA Astrophysics Data System (ADS)

    Mansfield, Elisabeth; Geiss, Roy; Fagan, Jeffrey A.

    2009-08-01

    The National Institute of Standards and Technology (NIST) will soon release a series of single-walled carbon nanotube (SWCNT) reference materials (RMs) to provide users with a well-characterized material for their applications. The SWCNT reference material will be introduced as a series of three types of material: (1) raw soot characterized for composition, which will be certified as a Standard Reference Material, (2) purified (greater than 90 % SWCNT by weight) bucky paper and (3) dispersed, length-sorted populations characterized by length. The instrumental characterization of NIST's SWCNT reference materials is extensive, and this paper aims to provide researchers with dispersion preparation methods for TEM (transmission electron microscopy) analysis of the SWCNT raw soot. A selection of dispersing solvents, including organic solvents, aqueous surfactants and DNA dispersions, were prepared and examined by TEM. Recommendations for sample preparation of the SWCNT SRM 2483 to yield images similar to those presented here are given. Examples of images of the length-sorted SWCNT reference material are also shown. These results illustrate the importance of optimal dispersion to enable imaging of SWCNT characteristics.

  11. Structural changes in collagen fibrils across a mineralized interface revealed by cryo-TEM.

    PubMed

    Quan, Bryan D; Sone, Eli D

    2015-08-01

    The structure of the mineralized collagen fibril, which is the basic building block of mineralized connective tissues, is critical to its function. We use cryo-TEM to study collagen structure at a well-defined hard-soft tissue interface, across which collagen fibrils are continuous, in order to evaluate changes to collagen upon mineralization. To establish a basis for the analysis of collagen banding, we compared cryo-TEM images of rat-tail tendon collagen to a model based on the X-ray structure. While there is close correspondence of periodicity, differences in band intensity indicate fibril regions with high density but lacking order, providing new insight into collagen fibrillar structure. Across a mineralized interface, we show that mineralization results in an axial contraction of the fibril, concomitant with lateral expansion, and that this contraction occurs only in the more flexible gap region of the fibril. Nevertheless, the major features of the banding pattern are not significantly changed, indicating that the axial arrangement of molecules remains largely intact. These results suggest a mechanism by which collagen fibrils are able to accommodate large amounts of mineral without significant disruption of their molecular packing, leading to synergy of mechanical properties.

  12. Deformation mechanisms of a 20Mn TWIP steel investigated by in situ neutron diffraction and TEM

    SciTech Connect

    Shen, Yongfeng; Wang, Y. D.; Liu, Xiaopeng; Sun, Xin; Peng, R. Lin; Zhang, S. Y.; Zuo, Liang; Liaw, Peter K.

    2013-07-25

    The deformation mechanisms and associated microstructure changes during tensile loading of an annealed twinning-induced plasticity (TWIP) steel with the chemical composition of Fe–20Mn–3Si–3Al–0.045C (wt.%) were systematically investigated using in situ time-of-flight (TOF) neutron diffraction in combination with postmortem transmission electron microscopy (TEM). The initial microstructure of the investigated alloy consists of equiaxed austenitic grains with the initial α´-phase of ~7% in volume. In addition to dislocation slip, twinning and two kinds of martensitic transformations from the austenite to α´- and epsilon martensites were observed as the main deformation modes during the tensile deformation. In situ neutron diffraction provides a powerful tool to establish the deformation mode map for elucidating the role of different deformation modes in different strain regions. The critical stress is 520 MPa for the martensitic transformation from the austenite to α´-martensite, whereas a higher stress (>600 MPa) is required for actuating the deformation twin and/or the martensitic transformation from -martensite. Both epsilon- and α´-martensites act as the hard phases whereas mechanical twinning contributes to both strength and ductility of the studied steel. TEM observations confirmed that the twinning process was facilitated by the parent grains orientated with <111> or <110> parallel to the loading direction. The nucleation and growth of twins are attributed to the pole and self-generation formation mechanisms, as well as the stair-rod cross-slip mechanism.

  13. In-situ TEM observation of nano-void formation in UO2 under irradiation

    NASA Astrophysics Data System (ADS)

    Sabathier, C.; Martin, G.; Michel, A.; Carlot, G.; Maillard, S.; Bachelet, C.; Fortuna, F.; Kaitasov, O.; Oliviero, E.; Garcia, P.

    2014-05-01

    Transmission electron microscopy (TEM) observations of UO2 polycrystals irradiated in situ with 4 MeV Au ions were performed at room temperature (RT) to better understand the mechanisms of cavity and ultimately fission products nucleation in UO2. Experiments were carried out at the JANNuS Orsay facility that enables in situ ion irradiations inside the microscope to be carried out. The majority of 4 MeV gold ions were transmitted through the thin foil, and the induced radiation defects were investigated by TEM. Observations showed that nano-void formation occurs at ambient temperature in UO2 thin foils irradiated with energetic heavy ions under an essentially nuclear energy loss regime. The diameter and density of nano-objects were measured as a function of the gold irradiation dose at RT. A previous paper has also revealed a similar nano-object population after a Xe implantation performed at 390 keV at 870 K. The nano-object density was modelled using simple concepts derived from Classical Molecular Dynamics simulations. The results are in good agreement, which suggests a mechanism of heterogeneous nucleation induced by energetic cascade overlaps. This indicates that nano-void formation mechanism is controlled by radiation damage. Such nanovoids are likely to act as sinks for mobile fission products during reactor operation.

  14. Characterization of mineral particles in winter fog of Beijing analyzed by TEM and SEM.

    PubMed

    Li, Weijun; Shao, Longyi

    2010-02-01

    Aerosol samples were collected during winter fog and nonfog episodes in Beijing. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were applied to study morphologies, sizes, and compositions of aerosol particles. TEM observation indicates that most mineral particles collected in fog episode are scavenged in fog droplets. Number-size distributions of mineral particles collected in fog and nonfog episodes show two main peaks at the ranges of 0.1-0.3 and 1-2.5 microm, respectively. Based on their major compositions, mineral particles mainly include Si-rich, Ca-rich, and S-rich. Average S/Ca ratio of mineral particles collected in fog episode is 6.11, being eight times higher than that in nonfog episodes. Development mechanism of individual mineral particles in fog droplets is proposed. It is suggested that mineral particles with abundant alkaline components (e.g., "Ca-rich" particles) occurred in air should alleviate acidic degree of fog and contribute to complexity of fog droplets in Beijing.

  15. TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates

    SciTech Connect

    Liliental-Weber, Z.; Ni, X.; Morkoc, H.

    2006-01-05

    Transmission electron microscopy (TEM) was used to study pendeo-epitaxial GaN layers grown on polar and non-polar 4H SiC substrates. The structural quality of the overgrown layers was evaluated using a number of TEM methods. Growth of pendeo-epitaxial layers on polar substrates leads to better structural quality of the overgrown areas, however edge-on dislocations are found at the meeting fronts of two wings. Some misorientation between the 'seed' area and wing area was detected by Convergent Beam Electron Diffraction. Growth of pendeo-epitaxial layers on non-polar substrates is more difficult. Two wings on the opposite site of the seed area grow in two different polar directions with different growth rates. Most dislocations in a wing grown with Ga polarity are 10 times wider than wings grown with N-polarity making coalescence of these layers difficult. Most dislocations in a wing grown with Ga polarity bend in a direction parallel to the substrate, but some of them also propagate to the sample surface. Stacking faults formed on the c-plane and prismatic plane occasionally were found. Some misorientation between the wings and seed was detected using Large Angle Convergent Beam Diffraction.

  16. Applying compressive sensing to TEM video: A substantial frame rate increase on any camera

    SciTech Connect

    Stevens, Andrew; Kovarik, Libor; Abellan, Patricia; Yuan, Xin; Carin, Lawrence; Browning, Nigel D.

    2015-08-13

    One of the main limitations of imaging at high spatial and temporal resolution during in-situ transmission electron microscopy (TEM) experiments is the frame rate of the camera being used to image the dynamic process. While the recent development of direct detectors has provided the hardware to achieve frame rates approaching 0.1 ms, the cameras are expensive and must replace existing detectors. In this paper, we examine the use of coded aperture compressive sensing (CS) methods to increase the frame rate of any camera with simple, low-cost hardware modifications. The coded aperture approach allows multiple sub-frames to be coded and integrated into a single camera frame during the acquisition process, and then extracted upon readout using statistical CS inversion. Here we describe the background of CS and statistical methods in depth and simulate the frame rates and efficiencies for in-situ TEM experiments. Depending on the resolution and signal/noise of the image, it should be possible to increase the speed of any camera by more than an order of magnitude using this approach.

  17. Applying compressive sensing to TEM video: A substantial frame rate increase on any camera

    DOE PAGES

    Stevens, Andrew; Kovarik, Libor; Abellan, Patricia; ...

    2015-08-13

    One of the main limitations of imaging at high spatial and temporal resolution during in-situ transmission electron microscopy (TEM) experiments is the frame rate of the camera being used to image the dynamic process. While the recent development of direct detectors has provided the hardware to achieve frame rates approaching 0.1 ms, the cameras are expensive and must replace existing detectors. In this paper, we examine the use of coded aperture compressive sensing (CS) methods to increase the frame rate of any camera with simple, low-cost hardware modifications. The coded aperture approach allows multiple sub-frames to be coded and integratedmore » into a single camera frame during the acquisition process, and then extracted upon readout using statistical CS inversion. Here we describe the background of CS and statistical methods in depth and simulate the frame rates and efficiencies for in-situ TEM experiments. Depending on the resolution and signal/noise of the image, it should be possible to increase the speed of any camera by more than an order of magnitude using this approach.« less

  18. In-situ TEM investigations of graphic-epitaxy and small particles

    NASA Technical Reports Server (NTRS)

    Heinemann, K.

    1983-01-01

    Palladium was deposited inside a controlled-vacuum specimen chamber of a transmission electron microscope (TEM) onto MgO and alpha-alumina substrate surfaces. Annealing and various effects of gas exposure of the particulate Pd deposits were studied in-situ by high resolution TEM and electron diffraction. Whereas substrate temperatures of 500 C or annealing of room temperature (RT) deposits to 500 C were needed to obtain epitaxy on sapphire, RT deposits on MgO were perfectly epitaxial. For Pd/MgO a lattice expansion of 2 to 4% was noted; the highest values of expansion were found for the smallest particles. The lattice expansion of small Pd particles on alumina substrates was less than 1%. Long-time RT exposure of Pd/MgO in a vacuum yielded some moblity and coalescence events, but notably fewer than for Pd on sapphire. Exposure to air or oxygen greatly enhanced the particle mobility and coalescence and also resulted in the flattening of Pd particles on MgO substrates. Electron-beam irradiation further enhanced this effect. Exposure to air for several tens of hours of Pd/MgO led to strong coalescence.

  19. TEM and SIMS Analysis of (100), (110), and (111) Single Crystal Niobium

    SciTech Connect

    A. D. Batchelor; D. N. Leonard; P. E. Russell; F. A. Stevie; D. P. Griffis; G. R. Myneni

    2006-10-30

    Single crystal niobium specimens of (100), (110) and (111) crystal orientations have been analyzed using TEM and SIMS. The TEM specimens were prepared using Focused Ion Beam (FIB) and show niobium oxide thicknesses ranging from 4.9 to 8.3 nm for the three specimens after buffer chemical polishing. The oxide layers appear uniform and no significant sub-oxide region was noted. SIMS analysis was made for all three orientations on hydrogen, carbon, and oxygen before and after heat treatments at 90, 600, and 1250ºC. Hydrogen is at a high level between the oxide layer and niobium, but at a relatively low level in the oxide. No high oxygen concentration region was noted in the niobium below the oxide. C contamination on the surface is detected mainly at the surface. Analysis after heat treatments showed some decrease in hydrogen after the 600ºC heat treatment, and significant oxidation of the niobium after the 1250ºC heat treatment.

  20. EBSD and TEM Characterization of High Burn-up Mixed Oxide Fuel

    SciTech Connect

    Teague, Melissa C.; Gorman, Brian P.; Miller, Brandon D.; King, Jeffrey

    2014-01-01

    Understanding and studying the irradiation behavior of high burn-up oxide fuel is critical to licensing of future fast breeder reactors. Advancements in experimental techniques and equipment are allowing for new insights into previously irradiated samples. In this work dual column focused ion beam (FIB)/scanning electron microscope (SEM) was utilized to prepared transmission electron microscope samples from mixed oxide fuel with a burn-up of 6.7% FIMA. Utilizing the FIB/SEM for preparation resulted in samples with a dose rate of <0.5 mRem/h compared to approximately 1.1 R/h for a traditionally prepared TEM sample. The TEM analysis showed that the sample taken from the cooler rim region of the fuel pellet had approximately 2.5x higher dislocation density than that of the sample taken from the mid-radius due to the lower irradiation temperature of the rim. The dual column FIB/SEM was additionally used to prepared and serially slice approximately 25 um cubes. High quality electron back scatter diffraction (EBSD) were collected from the face at each step, showing, for the first time, the ability to obtain EBSD data from high activity irradiated fuel.

  1. Advantages and limitations of OM, SEM, TEM and AFM in the study of ancient decorated pottery

    NASA Astrophysics Data System (ADS)

    Arenas-Alatorre, J.; Silva-Velazquez, Y.; Alva Medina, A.; Rivera, M.

    2010-03-01

    This paper presents results from the study of two fragments of pre-Hispanic pottery, decorated with red pigment, using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Atomic Force Microscopy (AFM) and Magnetic Force Microscopy (MFM). Capabilities and limitations of these techniques in the analysis of archaeological material are highlighted with special emphasis on TEM, AFM and MFM due to their contribution in the study of the pigment layer at micro and nano scale. The analyzed samples come from the archaeological sites of El Tajin and Xochicalco, both in Mexico. Results of conventional TEM and HRTEM analysis of the red pigment showed nanometric Fe2O3 particles in both samples but different particle shape and size distributions: specimen from El Tajin presented irregular particles between 50-100 nm while that from Xochicalco exhibited semispherical shapes in the 3-25 nm range. AFM images showed the topography of the pigments, which are related to the texture of their surface and thus to the production process. Finally, MFM showed different contrast regions suggesting the presence of ferromagnetic elements forming clusters and domain orientations on the color layer.

  2. SEM, TEM and SLEEM (scanning low energy electron microscopy) of CB2 steel after creep testing

    NASA Astrophysics Data System (ADS)

    Kasl, J.; Mikmeková, Š.; Jandová, D.

    2014-03-01

    The demand to produce electrical power with higher efficiency and with lower environmental pollution is leading to the use of new advanced materials in the production of power plant equipment. To understand the processes taking place in parts produced from these materials during their operation under severe conditions (such as high temperature, high stress, and environmental corrosion) requires detailed evaluation of their substructure. It is usually necessary to use transmission electron microscopy (TEM). However, this method is very exacting and time-consuming. So there is an effort to use new scanning electron microscopy techniques instead of TEM. One of them is scanning low energy electron microscopy (SLEEM). This paper deals with an assessment of the possibility to use SLEEM for describing the substructure of creep resistant steel CB2 after long-term creep testing. In the SLEEM images more information is contained about the microstructure of the material in comparison with standard scanning electron microscopy. Study of materials using slow and very slow electrons opens the way to better understanding their microstructures.

  3. Design of TEM00 mode side-pumped Nd:YAG solar laser

    NASA Astrophysics Data System (ADS)

    Almeida, Joana; Liang, Dawei

    2014-12-01

    An alternative solar laser pumping approach is here proposed to improve substantially TEM00 mode solar laser power. The solar radiation is both collected and concentrated by four Fresnel lenses, and redirected towards a laser head by four plane folding mirrors. A secondary concentrator with four semi-cylindrical fused silica lenses is designed to compress the highly concentrated solar radiation to a Nd:YAG single-crystal rod. Optimum pumping conditions and laser resonator parameters are found through ZEMAX© and LASCAD© numerical analysis. The proposed design offers a uniform absorbed pump distribution along the laser rod which has a minimum in its central region, reducing considerably thermal lensing effects. High order mode laser power of 83 W is numerically attained with a short symmetric laser resonant cavity, leading to high collection efficiency of 20.8 W/m2 for side-pumped Nd:YAG solar laser. Large spatial overlap between the pumped volume and the fundamental mode volume is found for an asymmetric laser resonator with concave end mirrors of large radius of curvature. 47.4 W TEM00 laser output power is numerically achieved, leading to a solar laser beam brightness figure of merit of 32 W. This value is 16.8 times more than the previous record for solar-pumped laser.

  4. Microstructural modifications in tungsten induced by high flux plasma exposure: TEM examination

    NASA Astrophysics Data System (ADS)

    Dubinko, A.; Bakaeva, A.; Hernández-Mayoral, M.; Terentyev, D.; De Temmerman, G.; Noterdaeme, J.-M.

    2016-02-01

    We have performed microstructural characterization using transmission electron microscopy (TEM) techniques to reveal nanometric features in the sub-surface region of tungsten samples exposed to high flux, low energy deuterium plasma. TEM examination revealed formation of a dense dislocation network and dislocation tangles, overall resulting in a strong increase in the dislocation density by at least one order of magnitude as compared to the initial one. Plasma-induced dislocation microstructure vanishes beyond a depth of about 10 μm from the top of the exposed surface where the dislocation density and its morphology becomes comparable to the reference microstructure. Interstitial edge dislocation loops with Burgers vector a 0/2<111> and a 0<100> were regularly observed within 6 μm of the sub-surface region of the exposed samples, but absent in the reference material. The presence of these loops points to a co-existence of nanometric D bubbles, growing by loop punching mechanism, and sub-micron deuterium flakes, resulting in the formation of surface blisters, also observed here by scanning electron microscopy.

  5. Speciation of Iron in Silicic Glasses: Inferences From Spectroscopic Methods and TEM

    NASA Astrophysics Data System (ADS)

    Galoisy, L.; Calas, G.; Menguy, N.

    2007-05-01

    Iron environment in silicic glasses has been investigated using optical absorption spectroscopy (OAS), X-ray Absorption Near Edge Structure (XANES), Electron Paramagnetic Resonance (EPR) and TEM. The samples are calco-alkaline silicic glasses from different localities and containing 0.5 to 2 wt% Fe. The redox state of iron in silicate glasses and the local environment around Fe2+ and Fe3+ is known to influence properties such as color or viscosity and crystal-liquid element partitioning, for glasses and melts, respectively. Considering eruption conditions, this information can give a better understanding of the cooling conditions and setting of lava flows. The spectra of silicic glasses are strongly different from that of synthetic glasses and tektites. All spectroscopic methods show the presence of Fe3+ and Fe2+ cations belonging to the glassy network associated with clustered superparamagnetic Fe-oxides. TEM data indicate that nanometric Fe-oxide clusters are poorly crystallized. The spectroscopic data on obsidians have been compared to those recorded on magnetite and synthetic glasses to assess the importance of Fe oxide clusters. These clusters are responsible for the variety of coloration of these obsidians. The speciation of iron in these glasses and associated clusters will be discussed in terms of formation conditions.

  6. TEM and SIMS Analysis of (100), (110), and (111) Single Crystal Niobium

    SciTech Connect

    Batchelor, A. D.; Stevie, F. A.; Leonard, D. N.; Russell, P. E.; Griffis, D. P.; Myneni, G. R.

    2007-08-09

    Single crystal niobium specimens of (100), (110) and (111) crystal orientations have been analyzed using TEM and SIMS. The TEM specimens were prepared using Focused Ion Beam (FIB) and show niobium oxide thicknesses ranging from 4.9 to 8.3 nm for the three specimens after buffer chemical polishing. The oxide layers appear uniform and no significant sub-oxide region was noted. SIMS analysis was made for all three orientations on hydrogen, carbon, and oxygen before and after heat treatments at 90, 600, and 1250 deg. C. Hydrogen is at a high level between the oxide layer and niobium, but at a relatively low level in the oxide. No high oxygen concentration region was noted in the niobium below the oxide. C contamination on the surface is detected mainly at the surface. Analysis after heat treatments showed some decrease in hydrogen after the 600 deg. C heat treatment, and significant oxidation of the niobium after the 1250 deg. C heat treatment.

  7. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV

    NASA Astrophysics Data System (ADS)

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max.; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-01

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed Cc/Cs corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  8. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV.

    PubMed

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-12

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  9. Mercury in polluted soils: speciation using micro-XRF, micro-XRD, and micro- and bulk XAFS.

    NASA Astrophysics Data System (ADS)

    Terzano, R.; Santoro, A.; Spagnuolo, M.; Vekemans, B.; Medici, L.; Janssens, K.; Goettlicher, J.; Denecke, M. A.; Mangold, S.; Ruggiero, P.

    2009-04-01

    In this research, mercury speciation was assessed for soil samples collected inside and outside an industrial polluted area of National environmental interest located in "Val Basento" (Basilicata, Italy). Hg concentration in these soil samples ranged from 12 up to 240 mg/kg. Mercury chemical forms in these samples were identified by a combination of sequential extraction procedures, thermal desorption analyses, and different bulk- and micro-analytical techniques exploiting high intensity synchrotron generated X-rays. Bulk XANES (X-ray Absorption Near Edge Structure) and EXAFS (Extended X-ray Absorption Fine Structure) spectra were collected for direct Hg-speciation in soil samples sieved at 2mm as well as in the clay fraction (<2um), where the highest amount of mercury was concentrated. The interpretation of the complex mixture of Hg-chemical forms in the soil samples was made simpler by performing, beside bulk XAS investigations, microanalyses on soil thin sections by combined u-XRF/u-XRD (micro X-ray Fluorescence/micro X-ray Diffraction) and u-XANES, with a resolution of 20 um. The information deriving from the micro-scale was then used to understand the bulk data. m-XRF maps were collected to localize microscopic Hg-containing particles in areas of several hundreds of mm2. Simultaneous to u-XRF spectra, microdiffraction patterns were collected in each point of the map, to identify possible crystalline Hg-mineral forms or mineral associations. Once points of interest were localized, u-XANES spectra were also collected. In general, two main representative XANES spectra (S1 and S2) were observed from Hg-rich spots at the microscopic level. Interestingly, all the bulk XANES spectra from all soil samples could be fitted by a linear combination of the microscopic S1 and S2 spectra. Therefore, by fitting the S1 and S2 spectra by means of known standard spectra it was then possible to decipher Hg-speciation for all the soil samples. In conclusion, the main constituents

  10. High Resolution Imaging with an Aberration Corrected JEOL 2200FS-AC STEM/TEM

    SciTech Connect

    Blom, Douglas Allen; Allard Jr, Lawrence Frederick; O'Keefe, Michael A.; Mishina, Satoshi

    2005-01-01

    A new JEOL 2200FS 200kV field emission STEM/TEM with a hexapole Cs-corrector (CEOS GmbH) for the probe-forming lens and an in-column Omega-type energy filter has recently been installed at the Advanced Microscopy Laboratory (AML) at Oak Ridge National Laboratory (ORNL). The microscope is intended primarily for high-resolution imaging of catalyst systems that are of interest to the U.S. Department of Energy for increased energy efficiency and energy security. In this paper we report on the high-resolution imaging characteristics of our microscope for both conventional high-resolution TEM and STEM imaging. The TEM Scherzer point resolution for our objective lens polepiece (C{sub s} = 0.5 mm) is 0.19 nm, but more significantly the information limit has been demonstrated to be better than 0.09 nm, as shown in Fig. 1. This figure shows a Young's fringe experiment carried out on an amorphous Ge specimen which was estimated to be 10 nm thick. The thickness of the sample damps out the Thon rings to some extent, but the information transfer to sub 0.1 nm resolution is clearly evident. The electron wave at the specimen exit surface with resolution out to the information limit of a microscope may be reconstructed via computational processing of a focal or tilt series of images. The extension of the TEM information limit to the sub-0.1 nm range in our microscope can be attributed primarily to the improved objective lens and high tension power supply stabilities provided by JEOL Co. to satisfy our instrument specifications. A contrast transfer function (CTF) calculated using the parameters for our microscope is shown in Fig. 2, computed at the alpha-null defocus condition used for FSR processing. The CTF closely matches the demonstrated Young's fringe pattern, indicating the ability of the microscope to achieve ultimate performance in TEM mode. Characterization of catalyst systems will be a primary focus of the aberration-corrected JEOL 2200FS and therefore high-resolution STEM

  11. Molecular analyses of TEM genes and their corresponding penicillinase-producing Neisseria gonorrhoeae isolates in Bangkok, Thailand.

    PubMed

    Nakayama, Shu-Ichi; Tribuddharat, Chanwit; Prombhul, Sasiprapa; Shimuta, Ken; Srifuengfung, Somporn; Unemo, Magnus; Ohnishi, Makoto

    2012-02-01

    Neisseria gonorrhoeae is a major public health problem globally, especially because the bacterium has developed resistance to most antimicrobials introduced for first-line treatment of gonorrhea. In the present study, 96 N. gonorrhoeae isolates with high-level resistance to penicillin from 121 clinical isolates in Thailand were examined to investigate changes related to their plasmid-mediated penicillin resistance and their molecular epidemiological relationships. A β-lactamase (TEM) gene variant, bla(TEM-135), that may be a precursor in the transitional stage of a traditional bla(TEM-1) gene into an extended-spectrum β-lactamase (ESBL), possibly causing high resistance to all extended-spectrum cephalosporins in N. gonorrhoeae, was identified. Clonal analysis using multilocus sequence typing (MLST) and N. gonorrhoeae multiantigen sequence typing (NG-MAST) revealed the existence of a sexual network among patients from Japan and Thailand. Molecular analysis of the bla(TEM-135) gene showed that the emergence of this allele might not be a rare genetic event and that the allele has evolved in different plasmid backgrounds, which results possibly indicate that it is selected due to antimicrobial pressure. The presence of the bla(TEM-135) allele in the penicillinase-producing N. gonorrhoeae population may call for monitoring for the possible emergence of ESBL-producing N. gonorrhoeae in the future. This study identified a bla(TEM) variant (bla(TEM-135)) that is a possible intermediate precursor for an ESBL, which warrants international awareness.

  12. Tem1 localization to the spindle pole bodies is essential for mitotic exit and impairs spindle checkpoint function

    PubMed Central

    Valerio-Santiago, Mauricio

    2011-01-01

    The mitotic exit network (MEN) is a signaling cascade that triggers inactivation of the mitotic cyclin-dependent kinases and exit from mitosis. The GTPase Tem1 localizes on the spindle pole bodies (SPBs) and initiates MEN signaling. Tem1 activity is inhibited until anaphase by Bfa1-Bub2. These proteins are also part of the spindle position checkpoint (SPOC), a surveillance mechanism that restrains mitotic exit until the spindle is correctly positioned. Here, we show that regulation of Tem1 localization is essential for the proper function of the MEN and the SPOC. We demonstrate that the dynamics of Tem1 loading onto SPBs determine the recruitment of other MEN components to this structure, and reevaluate the interdependence in the localization of Tem1, Bfa1, and Bub2. We also find that removal of Tem1 from the SPBs is critical for the SPOC to impede cell cycle progression. Finally, we demonstrate for the first time that localization of Tem1 to the SPBs is a requirement for mitotic exit. PMID:21321099

  13. Identification of small molecules that inhibit the interaction of TEM8 with anthrax protective antigen using a FRET assay

    PubMed Central

    Cryan, Lorna M.; Habeshian, Kaiane A.; Caldwell, Thomas P.; Morris, Meredith T.; Ackroyd, P. Christine; Christensen, Kenneth A.; Rogers, Michael S.

    2013-01-01

    Tumor marker endothelial 8 (TEM8) is a receptor for the Protective Antigen (PA) component of anthrax toxin. TEM8 is upregulated on endothelial cells lining the blood vessels within tumors, compared to normal blood vessels. A number of studies have demonstrated a pivotal role for TEM8 in developmental and tumor angiogenesis. We have also shown that targeting the anthrax receptors with a mutated form of PA inhibits angiogenesis and tumor formation in vivo. Here we describe the development and testing of a high-throughput fluorescence resonance energy transfer assay to identify molecules that strongly inhibit the interaction of PA and TEM8. The assay we describe is sensitive and robust, with a Z-prime value of 0.8. A preliminary screen of 2310 known bioactive library compounds identified ebselen and thimerosal as inhibitors of the TEM8-PA interaction. These molecules each contain a cysteine-reactive transition metal, and complimentary studies indicate that their inhibition of interaction is due to modification of a cysteine residue in the TEM8 extracellular domain. This is the first demonstration of a high-throughput screening assay that identifies inhibitors of TEM8, with potential application for anti-anthrax and anti-angiogenic diseases. PMID:23479355

  14. Nano-Structural Elucidation in Carbon Black Loaded NR Vulcanizate by 3D-TEM and In Situ WAXD Measurements

    SciTech Connect

    Ikeda,Y.; Kato, A.; Shimanuki, J.; Kohjiya, S.; Tosaka, M.; Poompradub, S.; Toki, S.; Hsiao, B.

    2007-01-01

    Three dimensional (3D) visualization of nanometer structure of carbon black dispersion in rubbery matrix has successfully been studied and reported in this paper. Use of 3D-TEM, which is computerized tomography combined with transmission electron microscopy (TEM), enabled us to reconstruct 3D images of carbon black aggregates in natural rubber (NR) matrix. The TEM measurements were conducted by a bright-field method on thin samples without any electron staining. The sample was subject to uni-axial tilting (+65 degree to -65 degree with 2 degree increment) in the sample chamber, and 66 TEM images were taken on each sample. These TEM images were used for computerized tomography to reconstruct the 3D image. This technique is designated as 3D-TEM. The nano-structural features observed by 3D-TEM were in conformity with the electron-conductivity results, and the percolation behavior was recognized. These results were further supplemented by in situ wide-angle X-ray diffraction (WAXD), i.e., simultaneous WAXD and tensile measurements on the sample to observe the strain-induced crystallization in NR vulcanizate. Upon tensile elongation, the crystallization was clearly observed in WAXD in the presence of carbon black, and it contributed to the tensile properties. In order to understand the performances of filled NR vulcanizates, it surely is necessary to know the structural states of the mixed nano-filler and the crystallites produced upon elongation.

  15. Tem1 localization to the spindle pole bodies is essential for mitotic exit and impairs spindle checkpoint function.

    PubMed

    Valerio-Santiago, Mauricio; Monje-Casas, Fernando

    2011-02-21

    The mitotic exit network (MEN) is a signaling cascade that triggers inactivation of the mitotic cyclin-dependent kinases and exit from mitosis. The GTPase Tem1 localizes on the spindle pole bodies (SPBs) and initiates MEN signaling. Tem1 activity is inhibited until anaphase by Bfa1-Bub2. These proteins are also part of the spindle position checkpoint (SPOC), a surveillance mechanism that restrains mitotic exit until the spindle is correctly positioned. Here, we show that regulation of Tem1 localization is essential for the proper function of the MEN and the SPOC. We demonstrate that the dynamics of Tem1 loading onto SPBs determine the recruitment of other MEN components to this structure, and reevaluate the interdependence in the localization of Tem1, Bfa1, and Bub2. We also find that removal of Tem1 from the SPBs is critical for the SPOC to impede cell cycle progression. Finally, we demonstrate for the first time that localization of Tem1 to the SPBs is a requirement for mitotic exit.

  16. Characterizing the Phyllosilicate Component of the Sheepbed Mudstone in Gale Crater, Mars Using Laboratory XRD and EGA

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Morris, R. V.; Ming, D. W.; Archer, P. D.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Blake, D. F.; Bristow, T. F.; Sutter, B.; Farmer, J. D.; Downs, R. T.; Leveille, R.; Achilles, C. A.; Crisp, J. A.; Des Marais, D. J.; Morookian, J. M.; Morrison, S. M.; Sarrazin, P. C.; Spanovich, N.; Treiman, A. H.; Yen, A. S.

    2014-01-01

    The Curiosity rover investigated the mineralogy of the Sheepbed mudstone member of the Yellowknife Bay formation in Gale crater. Data from the Chemistry and Mineralogy (CheMin) X-ray diffractometer (XRD) helped identify phyllosilicates in the two drilled samples, John Klein and Cumberland. These patterns showed peaks at low angles, consistent with (001) peaks in 2:1 swelling phyllosilicates [1]. Evolved gas analyses (EGA) by the Sample Analysis at Mars (SAM) instrument of these samples confirmed the presence of phyllosilicates through the release of H2O at high temperatures, consistent with dehydroxylation of octahedral OH in phyllosilicates [2]. CheMin data for the phyllosilicates at John Klein and Cumberland show that they are structurally similar in that their (02l) peaks are near 22.5 deg 2theta, suggesting both samples contain trioctahedral 2:1 phyllosilicates [1]. However, the positions of the (001) peaks differ: the phyllosilicate at John Klein has its (001) peak at 10 Angstroms, whereas the phyllosilicate at Cumberland has an (001) peak at 14 Angstroms. Such differences in (001) dspacings can be ascribed to the type of cation in the interlayer site [3]. For example, large monovalent cations (e.g., K(+)) have low hydration energies and readily lose their H2O of hydration, whereas small divalent cations (e.g., Mg(2+)) have high energies of hydration and retain H2O in the phyllosilicate interlayers [3,4]. The goal of this study is to determine whether differences in the interlayer cation composition can explain the CheMin data from John Klein and Cumberland and to use this knowledge to better understand phyllosilicate formation mechanisms.

  17. Bone matrix calcification during embryonic and postembryonic rat calvarial development assessed by SEM-EDX spectroscopy, XRD, and FTIR spectroscopy.

    PubMed

    Henmi, Akiko; Okata, Hiroshi; Anada, Takahisa; Yoshinari, Mariko; Mikami, Yasuto; Suzuki, Osamu; Sasano, Yasuyuki

    2016-01-01

    Bone mineral is constituted of biological hydroxyapatite crystals. In developing bone, the mineral crystal matures and the Ca/P ratio increases. However, how an increase in the Ca/P ratio is involved in maturation of the crystal is not known. The relationships among organic components and mineral changes are also unclear. The study was designed to investigate the process of calcification during rat calvarial bone development. Calcification was evaluated by analyzing the atomic distribution and concentration of Ca, P, and C with scanning electron microscopy (SEM)-energy-dispersive X-ray (EDX) spectroscopy and changes in the crystal structure with X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Histological analysis showed that rat calvarial bone formation started around embryonic day 16. The areas of Ca and P expanded, matching the region of the developing bone matrix, whereas the area of C became localized around bone. X-ray diffraction and FTIR analysis showed that the amorphous-like structure of the minerals at embryonic day 16 gradually transformed into poorly crystalline hydroxyapatite, whereas the proportion of mineral to protein increased until postnatal week 6. FTIR analysis also showed that crystallization of hydroxyapatite started around embryonic day 20, by which time SEM-EDX spectroscopy showed that the Ca/P ratio had increased and the C/Ca and C/P ratios had decreased significantly. The study suggests that the Ca/P molar ratio increases and the proportion of organic components such as proteins of the bone matrix decreases during the early stage of calcification, whereas crystal maturation continues throughout embryonic and postembryonic bone development.

  18. Synthesis, dynamic NMR characterization and XRD studies of novel N,N’-substituted piperazines for bioorthogonal labeling

    PubMed Central

    Pretze, Marc; Gott, Matthew; Köckerling, Martin

    2016-01-01

    Novel, functionalized piperazine derivatives were successfully synthesized and fully characterized by 1H/13C/19F NMR, MS, elemental analysis and lipophilicity. All piperazine compounds occur as conformers resulting from the partial amide double bond. Furthermore, a second conformational shape was observed for all nitro derivatives due to the limited change of the piperazine chair conformation. Therefore, two coalescence points were determined and their resulting activation energy barriers were calculated using 1H NMR. To support this result, single crystals of 1-(4-nitrobenzoyl)piperazine (3a, monoclinic, space group C2/c, a = 24.587(2), b = 7.0726(6), c = 14.171(1) Å, β = 119.257(8)°, V = 2149.9(4) Å3, Z = 4, D obs = 1.454 g/cm3) and the alkyne derivative 4-(but-3-yn-1-yl)-1-(4-fluorobenzoyl)piperazine (4b, monoclinic, space group P21/n, a = 10.5982(2), b = 8.4705(1), c = 14.8929(3) Å, β = 97.430(1)°, V = 1325.74(4) Å3, Z = 4, D obs = 1.304 g/cm3) were obtained from a saturated ethyl acetate solution. The rotational conformation of these compounds was also verified by XRD. As proof of concept for future labeling purposes, both nitropiperazines were reacted with [18F]F–. To test the applicability of these compounds as possible 18F-building blocks, two biomolecules were modified and chosen for conjugation either using the Huisgen-click reaction or the traceless Staudinger ligation. PMID:28144316

  19. Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy

    PubMed Central

    2009-01-01

    Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline calcium (alumino-)silicate hydrate (Al-CSH) forms as a precursor solid to the cement mineral tobermorite. Rate constants for tobermorite growth were found to be k = 0.6 (± 0.1) × 10-5 s-1 for a solution:solid of 10:1 and 1.6 (± 0.8) × 10-4 s-1 for a solution:solid of 5:1 (batch mode; T = 150°C). This data indicates that reaction rates for tobermorite growth are faster when the solution volume is reduced by half, suggesting that rates are dependent on solution saturation and that the Gibbs free energy is the reaction driver. However, calculated solution saturation indexes for Al-CSH and tobermorite differ by less than one log unit, which is within the measured uncertainty. Based on this data, we consider both heterogeneous nucleation as the thermodynamic driver and internal restructuring as possible mechanistic pathways for growth. We also use NMR spectroscopy to characterize the site symmetry and bonding environment of Al and Si in a reacted tobermorite sample. We find two [4]Al coordination structures at δiso = 59.9 ppm and 66.3 ppm with quadrupolar product parameters (PQ) of 0.21 MHz and 0.10 MHz (± 0.08) from 27Al 3Q-MAS NMR and speculate on the Al occupancy of framework sites by probing the protonation environment of Al metal centers using 27Al{1H}CP-MAS NMR. PMID:19144195

  20. TEM-187, a new extended-spectrum β-lactamase with weak activity in a Proteus mirabilis clinical strain.

    PubMed

    Corvec, Stéphane; Beyrouthy, Racha; Crémet, Lise; Aubin, Guillaume Ghislain; Robin, Frédéric; Bonnet, Richard; Reynaud, Alain

    2013-05-01

    A Proteus mirabilis clinical strain (7001324) was isolated from urine sample of a patient hospitalized in a long-term-care facility. PCR and cloning experiments performed with this strain identified a novel TEM-type β-lactamase (TEM-187) differing by four amino acid substitutions (Leu21Phe, Arg164His, Ala184Val, and Thr265Met) from TEM-1. This characterization provides further evidence for the diversity of extended-spectrum β-lactamases (ESBL) produced by P. mirabilis and for their potential spread to other Enterobacteriaceae due to a lack of sensitive detection methods used in daily practice.

  1. Focused ion beam preparation techniques dedicated for the fabrication of TEM lamellae of fibre-reinforced composites.

    PubMed

    Mucha, Herbert; Kato, Takeharu; Arai, Shigeo; Saka, Hiroyasu; Kuroda, Kotaro; Wielage, Bernhard

    2005-01-01

    Two Focused Ion Beam based transmission electron microscopy (TEM) thin film preparation techniques are introduced. One is dedicated to the preparation of single fibres, the other to fibre/matrix interfaces of fibre reinforced composites. Due to their thin film quality, reliability and predictable processing times both techniques are suited for routine applications in material science like TEM studies of fibre microtextures and fibre/matrix interfaces. Exemplarily they are applied to Carbon Fibres and Carbon Fibre reinforced Carbon Matrix Composites (C/C). The achieved preparation standard in both cases is substantiated by TEM investigations.

  2. Characterization of nanoscale local lattice strains in silicon CMOS devices by TEM/CBED

    NASA Astrophysics Data System (ADS)

    Huang, Jiang

    Strained-Si technology has become one of the leading approaches to further improve the performance of the metal-oxide-semiconductor field effect transistors (MOSFETs) as traditional device scaling faces its physical limitation. In particular, mechanical strain induced in the Si channel region is used to increase the carrier mobility and the transistor drive current. To be able to understand and engineer the local lattice strain incorporated in the nanoscale device region, a strain measurement technique with high spatial resolution and high sensitivity is essential. Currently, transmission electron microscope (TEM)/convergent beam electron diffraction (CBED) is the only method to measure local changes in lattice parameters due to strain in advanced CMOS devices, because this technique provides nanometer spatial resolution and strain sensitivity on the order of 10-4. In this study, a novel experimental methodology is developed to measure the strain effectively and efficiently. Site-specific TEM samples are prepared by focused ion beam (FIB) with controlled thickness. Zone axes such as <230>, <340>, <560> and <910> are evaluated for obtaining CBED patterns. The specimen-tilt projection and dynamical effects related to the zone axis are discussed. CBED pattern simulation and matching procedures are explained to extract the strain tensors. The accuracy of the strain measurement depends on the clarity of the CBED pattern, which can be improved by using an energy-filter or sample cooling stage. The direct strain measurements are performed in sub-100 nm CMOS devices with either structure-induced or process-induced strains. It is found that the compressive strains are induced when the shallow trench structure (STI) is filled with isolation films. The compressive strains on the order of 10 -3 are observed under the gate region in a Si <110> PMOS transistor with a 37 nm gate length. One-dimensional quantitative strain-mapping is demonstrated using the nanometer probe. The

  3. Optical and TEM study of shock metamorphism from the Sedan test site

    NASA Technical Reports Server (NTRS)

    Gratz, A. J.

    1992-01-01

    Thus far, detailed petrologic studies of shock metamorphism have been performed on samples recovered from laboratory experiments and on a few natural impactites. The loading history of these samples is quite different: In particular, laboratory experiments spend only a short time (less than 1 microsec) at peak pressure, whereas natural impactites may have stress pulses from 0.1 - 1 ms. On the other hand, laboratory experiments have known stress histories; natural impactites do not. Natural samples are also subjected to thousands or millions of years of postshock annealing and/or weathering. A useful intermediate case is that of nuclear detonation. Stress pulses for these events can reach 0.1 ms or higher, and samples are obtained in pristine condition. All three types of loading produce stresses of hundreds of kilobars. Samples studied were taken from the Sedan nulcear test site, and consist of a coarse-grained granodiorite containing quartz, K-feldspar, cordierite, and hornblende. Samples were studied optically in this section, then were thinned with an ion mill and studied by transmission electron microscopy (TEM). Optically, quartz and K-feldspar displayed numerous sets of planar deformation features (PDF's) identical to the nondecorated PDF's seen in laboratory samples and many natural impactites. TEM study showed that the PDF's in quartz and feldspar corresponded to densely packed wide transformation lamellae identical to those described in laboratory studies. The transformation lamellae in both minerals were amorphous, with no sign of high-pressure phases. In the case of K-feldspar only, narrow sublamellae extended outward from some wide lamellae. Quartz, which was more abundant and studied more extensively, contained no shock-induced dislocations. Some planar features were also seen in cordierite, but could not be identified due to rapid beam damage. No shock defects were seen in hornblende in TEM. The shock-induced defects present at the Sedan site are very

  4. In situ TEM visualization of superior nanomechanical flexibility of shear-exfoliated phosphorene

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Ma, Hongyu; Lei, Shuangying; Sun, Jun; Chen, Jing; Ge, Binghui; Zhu, Yimei; Sun, Litao

    2016-07-01

    Recently discovered atomically thin black phosphorus (called phosphorene) holds great promise for applications in flexible nanoelectronic devices. Experimentally identifying and characterizing nanomechanical properties of phosphorene are challenging, but also potentially rewarding. This work combines for the first time in situ transmission electron microscopy (TEM) imaging and an in situ micro-manipulation system to directly visualize the nanomechanical behaviour of individual phosphorene nanoflakes. We demonstrate that the phosphorene nanoflakes can be easily bent, scrolled, and stretched, showing remarkable mechanical flexibility rather than fracturing. An out-of-plane plate-like bending mechanism and in-plane tensile strain of up to 34% were observed. Moreover, a facile liquid-phase shear exfoliation route has been developed to produce such mono-layer and few-layer phosphorene nanoflakes in organic solvents using only a household kitchen blender. The effects of surface tensions of the applied solvents on the ratio of average length and thickness (L/T) of the nanoflakes were studied systematically. The results reported here will pave the way for potential industrial-scale applications of flexible phosphorene nanoelectronic devices.Recently discovered atomically thin black phosphorus (called phosphorene) holds great promise for applications in flexible nanoelectronic devices. Experimentally identifying and characterizing nanomechanical properties of phosphorene are challenging, but also potentially rewarding. This work combines for the first time in situ transmission electron microscopy (TEM) imaging and an in situ micro-manipulation system to directly visualize the nanomechanical behaviour of individual phosphorene nanoflakes. We demonstrate that the phosphorene nanoflakes can be easily bent, scrolled, and stretched, showing remarkable mechanical flexibility rather than fracturing. An out-of-plane plate-like bending mechanism and in-plane tensile strain of up to

  5. Surprising microscopy subtleties: Measuring picoscale thicknesses, visualizing core orbitals, and detecting charge transfer using the TEM

    NASA Astrophysics Data System (ADS)

    Odlyzko, Michael Luke

    50 years ago, Richard Feynman delivered a now-famous address outlining why there was "plenty of room left at the bottom": there remained much progress to be made in seeing and manipulating matter all the way down to the atomic scale. One of many means to that end, argued Feynman, was to make electron microscopes better. Why could not electrons with wavelengths of a few picometers not be used to clearly image atoms hundreds of picometers in size? Why could not electron beams be used to pattern miniscule wires a handful of metal atoms across? Over the course of decades, Feynman's vision has been pursued zealously with rich reward, not least in the electron microscopy field. Enabled by the development of bright field-emission electron sources, high-resolution polepieces, and now aberration correctors, transmission electron microscopy (TEM) at atomic resolution has become routine. Seemingly, there is little room left at the bottom; after all, once you can clearly see atoms, what more is there left to do? Thankfully, there is plenty. Much of the hard work has been in the development of equipment that expands TEM to allow unprecedented spatially resolved analysis of elemental composition, inelastic scattering, and temporal processes. But there are also many opportunities to uncover new information using now widely available techniques and equipment. In the studies presented here, there has been some success in following the latter path. In tandem with careful computational analysis, selected-area electron diffraction allows not only determination of crystal symmetry, lattice parameter, and microstructure, but also measurements of material thickness on the scale of atomic layers. Supported by careful data processing and rigorous simulations, spatially resolved X-ray spectroscopy data is converted into real-space measurements of core-level electronic orbitals, in addition to providing routine atomic resolution chemical mapping. And aided by the development of novel bonding

  6. In situ TEM investigations of mineral growth through oriented attachment of nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, D.; Nielsen, M.; Lee, J. R.; Frandsen, C.; Banfield, J. F.; Kisailus, D.; De Yoreo, J.

    2012-12-01

    The growth of crystals through aggregation and coalescence of nanoparticles is now recognized as a widespread phenomenon in biomineral, biomimetic and natural systems, and during synthetic production of nanoparticles and nanowires. The resulting crystals often exhibit complex forms ranging from quasi-one-dimensional chains to 3D hierarchical and self-similar superstructures. Yet the final structure typically diffracts as a single crystal, implying that the primary particles aligned during growth. When coalignment is accompanied by coalescence, this growth process is often referred to as oriented attachment (OA). OA is now recognized as an important mechanism of crystal growth in many materials in the environment. However, the pathway by which OA occurs has not been established. Although the preservation of primary particle morphology and formation of twins and stacking faults at particle-particle boundaries strongly suggest a sequence of whole particle alignment followed by interface elimination, atom-by-atom reorientation via dislocation and grain-boundary migration after attachment are another potential mechanism. If indeed the primary particles align before attachment, the dynamics of that process and the forces that drive it have yet to be revealed. To achieve this understanding we are investigating crystal nucleation and oriented attachment in a number of systems, such as iron oxides and oxyhydroxide as well as titanium dioxide, through in situ and ex situ TEM. We performed high-resolution TEM using a fluid cell to directly observe oriented attachment of iron oxyhydroxide nanoparticles. The particles undergo continuous rotation and interaction until they find a perfect lattice match. A sudden jump to contact then occurs over less than 1 nanometer, followed by lateral atom-by-atom addition initiated at the contact point. Interface elimination proceeds at a rate consistent with the curvature dependence of the Gibbs free energy. Measured translational and

  7. Use of an ultrasonic/sonic driller/corer to obtain sample powder for chemin, a combined XRD/XRF instrument.

    SciTech Connect

    Chipera, S. J.; Bish, D. L.; Vaniman, D. T.; Sherrit, S.; Bar-Cohen, Yoseph; Blake, D.

    2003-01-01

    One of the technical issues that must be addressed before landing an XRD,iXRF spectrometer on an extraterrestrial body is how best to obtain a representative sample powder for analysis. For XRD powder diffraction analyses, it is beneficial to have a powder that is extremely fine grained to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the Xray beam. Although a 2 dimensional detector as used in the CHEMIN instrument will produce good results with poorly prepared powders, the quality of the data will improve with the quality of the sample powder.

  8. Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS/XAFS/XRD Technique

    SciTech Connect

    Sankar, Gopinathan; Fiddy, Steven; Harvey, Ian; Hayama, Shusaku; Bushnell-Wye, Graham; Beale, Andrew M.

    2007-02-02

    Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD/EXAFS/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III); DAF-8 containing about 25 percent cobalt is not stable and does not show change in oxidation state.

  9. Stereological substructure analysis in hot-deformed metals from TEM-images

    NASA Astrophysics Data System (ADS)

    Barthel, M.; Klimanek, P.; Stoyan, D.

    1985-03-01

    In the present paper three possible methods of stereological evaluation of particle arrangements are discussed: determination of mean particle diameters by means of the so-called Poisson-Voronoi mosaics, evaluation of the spatial particle-diameter distribution using the interception-length method of Spektor and determination of the spatial distribution of grain or subgrain diameters on the basis of an intercept-area method of Saltykov. Practical application of the procedures is demonstrated by results which were obtained from hot-deformation of several material under different hot-working conditions. It can be shown that stereological interpretation of TEM images renders refined conclusions concerning the mechanisms of structure changes occurring in hot-deformation.

  10. Mechanical properties and TEM examination of RAFM steels irradiated up to 70 dpa in BOR-60

    NASA Astrophysics Data System (ADS)

    Gaganidze, E.; Petersen, C.; Materna-Morris, E.; Dethloff, C.; Weiß, O. J.; Aktaa, J.; Povstyanko, A.; Fedoseev, A.; Makarov, O.; Prokhorov, V.

    2011-10-01

    Mechanical properties of Reduced Activation Ferritic/Martensitic (RAFM) steels were studied after irradiation in BOR-60 reactor to a neutron displacement damage of 70 dpa at 330-340 °C. Yield stress and Ductile-to-Brittle-Transition-Temperature of EUROFER97 indicate saturation of hardening and embrittlement. The phenomenological models for description of microstructure evolution and resulting irradiation hardening and embrittlement are discussed. The evolution of yield stress with dose is qualitatively understood within a Whapham and Makin model. Dislocation loops examined in TEM are considered a main source for low-temperature irradiation hardening. The analysis of the fatigue data in terms of the inelastic strain reveals comparable fatigue behaviour both for unirradiated and irradiated conditions, which can be described by a common Manson-Coffin relation. The study of helium effects in B-doped model steels indicated progressive material embrittlement with helium content. Post-irradiation annealing of RAFM steels yielded substantial recovery of mechanical properties.

  11. A FIB/TEM Study of a Complex Wark-Lovering Rim on a Vigarano CAI

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Needham, A. W.; Messenger, S.

    2013-01-01

    Wark-Lovering (WL) rims are thin multilayered mineral sequences that surround most Ca, Al-rich inclusions (CAIs). Several processes have been proposed for WL rim formation, including condensation, flash-heating or reaction with a nebular reservoir, or combinations of these [e.g. 1-7], but no consensus exists. Our previous coordinated transmission electron microscope (TEM) and NanoSIMS O isotopic measurements showed that a WL rim experienced flash heating events in a nebular environment with planetary O isotopic composition, distinct from the (16)O-rich formation environment [6]. Our efforts have focused on CAIs from the CV(sub red) chondrites, especially Vigarano, because these have escaped much of the parent body alteration effects that are common in CAIs from CV(sub ox) group.

  12. Quantitative nanoscopy: Tackling sampling limitations in (S)TEM imaging of polymers and composites.

    PubMed

    Gnanasekaran, Karthikeyan; Snel, Roderick; de With, Gijsbertus; Friedrich, Heiner

    2016-01-01

    Sampling limitations in electron microscopy questions whether the analysis of a bulk material is representative, especially while analyzing hierarchical morphologies that extend over multiple length scales. We tackled this problem by automatically acquiring a large series of partially overlapping (S)TEM images with sufficient resolution, subsequently stitched together to generate a large-area map using an in-house developed acquisition toolbox (TU/e Acquisition ToolBox) and stitching module (TU/e Stitcher). In addition, we show that quantitative image analysis of the large scale maps provides representative information that can be related to the synthesis and process conditions of hierarchical materials, which moves electron microscopy analysis towards becoming a bulk characterization tool. We demonstrate the power of such an analysis by examining two different multi-phase materials that are structured over multiple length scales.

  13. (An)aerobic bacteria found in secondary-cataract material. A SEM/TEM study.

    PubMed

    Kalicharan, D; Jongebloed, W L; Los, L I; Worst, J G

    1992-01-01

    Twenty four patients, who had marked reduction of vision due to secondary-cataract developed after an ECCE, were treated by surgical cleaning of the posterior lens capsule. During this procedure globular secondary-cataract material was removed and collected for morphological examination by SEM and TEM. Fragments of various sizes and shapes, including some with a 'golf ball' structure, were seen; these closely resembled particles frequently found in cataractous lenses. In addition, in 18 patients micro-organisms were found: rod-shaped bacteria, cocci, and in 2 cases yeasts. These findings were the more remarkable because these were clinically quiet eyes with no signs of intra-ocular inflammation and cultures have been persistently negative. We imagine that these bacteria must have entered the eye during the cataract extraction and have settled there without causing an infection.

  14. Image processing enhancement of high-resolution TEM micrographs of nanometer-size metal particles

    NASA Technical Reports Server (NTRS)

    Artal, P.; Avalos-Borja, M.; Soria, F.; Poppa, H.; Heinemann, K.

    1989-01-01

    The high-resolution TEM detectability of lattice fringes from metal particles supported on substrates is impeded by the substrate itself. Single value decomposition (SVD) and Fourier filtering (FFT) methods were applied to standard high resolution micrographs to enhance lattice resolution from particles as well as from crystalline substrates. SVD produced good results for one direction of fringes, and it can be implemented as a real-time process. Fourier methods are independent of azimuthal directions and allow separation of particle lattice planes from those pertaining to the substrate, which makes it feasible to detect possible substrate distortions produced by the supported particle. This method, on the other hand, is more elaborate, requires more computer time than SVD and is, therefore, less likely to be used in real-time image processing applications.

  15. LD bar corner-pumped TEM00 CW composite Nd:YAG laser.

    PubMed

    Gao, Song; Liu, Huan; Wang, Dongsheng; Gong, Mali

    2009-11-23

    Ray-tracing algorithm was used to simulate the pump absorption efficiency and pump absorption distribution of LD corner-pumped laser with different parameters of Nd:YAG composite slab crystal. Resonator experiment was performed to suppress the oscillation of higher-order modes and realize TEM(00) operation. Experiment results showed that the output power was 11.94 W with an optical-optical efficiency of over 26%, and the M2 factors of beam quality at width and thickness directions were 1.18 and 1.34, respectively. It has been proven that the corner-pumped configuration could obtain laser output with good beam quality as a result of high pump efficiency and good pump uniformity.

  16. Bacterium Wrapping with Graphene for Non-destructive TEM Imaging and Raman Enhancement

    NASA Astrophysics Data System (ADS)

    Mohanty, Nihar; Nagaraja, Ashvin; Frey, Monica; Berry, Vikas

    2010-03-01

    Graphene - a single atom thick layer of sp^2 carbon atoms arranged in a honeycomb lattice - exhibits atomic impermeability, high electric conductivity and mesoscale flexibility. We demonstrate that graphene's functionalization with cell-adhesion-peptides makes it highly specific to bacterial cells and stable in suspensions. Upon interaction with live gram-positive bacterial cells, these graphene-peptide microcarpets (GPMCs) instantaneously (< 1 min) wrap the bacterial cells. Dye permeation studies confirm the impermeability of the GPMCs, consistent with the theory. Further, concurrent microscopic and spectroscopic analysis of the wrapping process would also be presented. Time-lapse TEM imaging studies on both wrapped and unwrapped bacteria, showed a ˜ 30 % reduction in efflux of the cellular material from the wrapped bacteria. We will also present the Raman spectroscopy results, showing a ˜ 400 % enhancement of the scattering signal after graphene wrapping.

  17. Materials science applications of a 120 kV FEG TEM/STEM: Triskaidekaphilia

    SciTech Connect

    Bentley, J.; Fisher, A.T.; Kenik, E.A.; Wang, Z.L.

    1991-01-01

    The introduction by several manufacturers of 200kV transmission electron microscopes (TEM) equipped with field emission guns affords the opportunity to assess their potential impact on materials science by examining applications of similar 100-120kV instruments that have been in use for more than a decade. This summary is based on results from a Philips EM400T/FEG configured as an analytical electron microscope (AEM) with a 6,585 scanning transmission (STEM) unit, EDAX 9100/70 or 9900 energy dispersive X-ray spectroscopy (EDS) systems, and Gatan 607 serial- or 666 parallel-detection electron energy-loss spectrometers (EELS). Examples in four areas that illustrate applications that are impossible or so difficult as to be impracticable with conventional thermionic electron guns are described.

  18. A Microanalytical (TEM) Study of Fine-grained Chondrule Rims in NWA 5717

    NASA Technical Reports Server (NTRS)

    Bigolski, J. N.; Frank, D. R.; Zolensky, Michael E.; Weisberg, M. K.; Ebel, D. S.; Rahman, Z.

    2013-01-01

    Northwest Africa (NWA) 5717 is a highly primitive ordinary chondrite of petrologic type 3.05 with ubiquitous fine-grained chondrule rims [1, 2]. Rims appear around approximately 60% of chondrules and are comprised of micron-sized mineral and lithic fragments and microchondrules that are embdedded in an FeO-rich submicron groundmass that compositionally resembles fayalitic olivine. Some rim clasts appear overprinted with FeO-rich material, suggesting secondary alteration that postdates rim formation. Here we present a microanalytical (TEM) study of the submicron component (i.e. the groundmass) of the rims in order to determine the crystal structures and compositions of their constituent phases and decipher the accretion and alteration history recorded in rims.

  19. Laser Based In Situ Techniques: Novel Methods for Generating Extreme Conditions in TEM Samples

    SciTech Connect

    Taheri, M; Lagrange, T; Reed, B; Armstrong, M; Campbell, G; DeHope, W; Kim, J; King, W; Masiel, D; Browning, N

    2008-02-25

    The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

  20. TEM and HRTEM of Soot-in-oil particles and agglomerates from internal combustion engines

    NASA Astrophysics Data System (ADS)

    Fay, M. W.; La Rocca, A.; Shayler, P. J.

    2014-06-01

    Over time, the performance of lubricating oil in a diesel engine is affected by the build-up of carbon soot produced by the combustion process. TEM and HRTEM are commonly used to investigate the characteristics of individual and agglomerated particles from diesel exhaust, to understand the structure and distribution of the carbon sheets in the primary particles and the nanostructure morphology. However, high resolution imaging of soot-in-oil is more challenging, as mineral oil is a contaminant for the electron microscope and leads to instability under the electron beam. In this work we compare solvent extraction and centrifugation techniques for removing the mineral oil contaminant, and the effect on particle size distribution.

  1. A TEM Investigation of the Fine-Grained Matrix of the Martian Basaltic Breccia NWA 7034

    NASA Technical Reports Server (NTRS)

    Muttik, N.; Keller, L. P.; Agee, C. B.; McCubbin, F. M.; Santos, A. R.; Rahman, Z.

    2014-01-01

    The martian basaltic breccia NWA 7034 is characterized by fine-grained groundmass containing several different types of mineral grains and lithologic clasts. The matrix composition closely resembles Martian crustal rock and soil composition measured by recent rover and orbiter missions. The first results of NWA 7034 suggest that the brecciation of this martian meteorite may have formed due to eruptive volcanic processes; however, impact related brecciation processes have been proposed for paired meteorites NWA 7533 and NWA 7475]. Due to the very fine grain size of matrix, its textural details are difficult to resolve by optical and microprobe observations. In order to examine the potential nature of brecciation, transmission electron microscopy (TEM) studies combined with focused ion-beam technique (FIB) has been undertaken. Here we present the preliminary observations of fine-grained groundmass of NWA 7034 from different matrix areas by describing its textural and mineralogical variations and micro-structural characteristics.

  2. In situ TEM/SEM electronic/mechanical characterization of nano material with MEMS chip

    NASA Astrophysics Data System (ADS)

    Yuelin, Wang; Tie, Li; Xiao, Zhang; Hongjiang, Zeng; Qinhua, Jin

    2014-08-01

    Our investigation of in situ observations on electronic and mechanical properties of nano materials using a scanning electron microscope (SEM) and a transmission electron microscope (TEM) with the help of traditional micro-electro-mechanical system (MEMS) technology has been reviewed. Thanks to the stability, continuity and controllability of the loading force from the electrostatic actuator and the sensitivity of the sensor beam, a MEMS tensile testing chip for accurate tensile testing in the nano scale is obtained. Based on the MEMS chips, the scale effect of Young's modulus in silicon has been studied and confirmed directly in a tensile experiment using a transmission electron microscope. Employing the nanomanipulation technology and FIB technology, Cu and SiC nanowires have been integrated into the tensile testing device and their mechanical, electronic properties under different stress have been achieved, simultaneously. All these will aid in better understanding the nano effects and contribute to the designation and application in nano devices.

  3. Quantitative TEM analysis of precipitation and grain boundary segregation in neutron irradiated EUROFER 97

    NASA Astrophysics Data System (ADS)

    Dethloff, Christian; Gaganidze, Ermile; Aktaa, Jarir

    2014-11-01

    Characterization of irradiation induced microstructural defects is essential for assessing the applicability of structural steels like the Reduced Activation Ferritic/Martensitic steel EUROFER 97 in upcoming fusion reactors. In this work Transmission Electron Microscopy (TEM) is used to analyze the types and structure of precipitates, and the evolution of their size distributions and densities caused by neutron irradiation to a dose of 32 displacements per atom (dpa) at 330-340 °C in the irradiation experiment ARBOR 1. A significant growth of MX and M23C6 type precipitates is observed after neutron irradiation, while the precipitate density remains unchanged. Hardening caused by MX and M23C6 precipitate growth is assessed by applying the Dispersed Barrier Hardening (DBH) model, and shown to be of minor importance when compared to other irradiation effects like dislocation loop formation. Additionally, grain boundary segregation of chromium induced by neutron irradiation was investigated and detected in irradiated specimens.

  4. Comparison of different sample preparation techniques in TEM observation of microstructure of INCONEL alloy 783 subjected to prolonged isothermal exposure.

    PubMed

    Ma, Longzhou

    2004-01-01

    INCONEL alloy 783 was annealed and aged following the standard heat treatment procedure. One set of specimens was then isothermally exposed at 500 degrees C for 3000 h. Mechanical properties were measured at room temperature and 650 degrees C, and the results showed the prolonged exposure increased the strength and decreased elongation of alloy 783. The microstructures of as-produced and exposed material were examined using optical microscope, SEM and TEM, respectively. Three techniques, jet electro-polishing, ion milling, and focused ion beam, were employed to prepare the TEM samples to observe the variation of microstructure of alloy 783 due to isothermal exposure. TEM images of samples prepared by different methods were analyzed and compared. The results indicate that the jet electro-polishing technique allows the detail microstructure of alloy 783 subjected to different treatments to be well revealed, and thereby the TEM images can be used to explain the enhancement of strength of alloy 783 caused by isothermal exposure.

  5. Compositional and Microstructural Evolution of Olivine During Pulsed Laser Irradiation: Insights Based on a FIB/Field-Emission TEM Study

    NASA Astrophysics Data System (ADS)

    Christoffersen, R.; Loeffler, M. J.; Dukes, C. A.; Baragiola, R. A.

    2015-11-01

    Field-emission TEM shows multi-layer vapor and melt deposits produced on olivine by pulsed laser irradiation contain abundant nanophase metallic Fe and have some microstructural similarities to melt deposits in micrometeorite impact craters.

  6. Problems at the Leading Edge of Space Weathering as Revealed by TEM Combined with Surface Science Techniques

    NASA Astrophysics Data System (ADS)

    Christoffersen, R.; Dukes, C. A.; Keller, L. P.; Rahman, Z.; Baragiola, R. A.

    2015-11-01

    Analytical field-emission TEM techniques cross-correlated with surface analyses by X-ray photoelectron spectroscopy (XPS) provides a unique two-prong approach for characterizing how solar wind ion processing contributes to space weathering.

  7. Assessment of lower-voltage TEM performance using 3D Fourier transform of through-focus series.

    PubMed

    Kimoto, Koji; Kurashima, Keiji; Nagai, Takuro; Ohwada, Megumi; Ishizuka, Kazuo

    2012-10-01

    We assess the imaging performance of a transmission electron microscopy (TEM) system operated at a relatively low acceleration voltage using the three-dimensional (3D) Fourier transform of through-focus images. Although a single diffractogram and the Thon diagram cannot distinguish between the linear and non-linear TEM imaging terms, the 3D Fourier transform allows us to evaluate linear imaging terms, resulting in a conclusive assessment of TEM performance. Using this method, information transfer up to 98 pm is demonstrated for an 80 kV TEM system equipped with a spherical aberration corrector and a monochromator. We also revisit the Young fringe method in the light of the 3D Fourier transform, and have found a considerable amount of non-linear terms in Young fringes at 80 kV even from a typical standard specimen, such as an amorphous Ge thin film.

  8. Ceftazidime-Resistant Enterobacteriaceae Isolates from Three Polish Hospitals: Identification of Three Novel TEM- and SHV-5-Type Extended-Spectrum β-Lactamases

    PubMed Central

    Gniadkowski, Marek; Schneider, Ines; Jungwirth, Renate; Hryniewicz, Waleria; Bauernfeind, Adolf

    1998-01-01

    Twelve ceftazidime-resistant isolates of the family Enterobacteriaceae (11 Klebsiella pneumoniae isolates and 1 Escherichia coli isolate) were collected in 1995 from three Polish hospitals located in different cities. All were identified as producers of extended-spectrum β-lactamases (ESBLs). Detailed analysis of their β-lactamase contents revealed that six of them expressed SHV-5-like ESBLs. The remaining six were found to produce three different TEM enzymes, each characterized by a pI value of 6.0 and specified by new combinations of amino acid substitutions. The amino acid substitutions compared to the TEM-1 β-lactamase sequence were Gly238Ser, Glu240Lys, and Thr265Met for TEM-47; Leu21Phe, Gly238Ser, Glu240Lys, and Thr265Met for TEM-48; and Leu21Phe, Gly238Ser, Glu240Lys, Thr265Met, and Ser268Gly for TEM-49. The new TEM β-lactamases, TEM-47, TEM-48, and TEM-49, belong to a subfamily of TEM-2-related enzymes. Genes coding for TEM-47 and TEM-49 could have originated from the TEM-48-encoding sequence by various single genetic events. The new TEM derivatives probably document the already advanced microevolution of ESBLs ongoing in Polish hospitals, in a majority of which no monitoring of ESBL producers was performed before 1996. PMID:9517925

  9. In-depth TEM characterization of block copolymer pattern transfer at germanium surfaces

    NASA Astrophysics Data System (ADS)

    Cummins, Cian; Collins, Timothy W.; Kelly, Roisin A.; McCarthy, Eoin K.; Morris, Michael A.

    2016-12-01

    Dry plasma etching for the pattern transfer of mask features is fundamental to semiconductor processing and the development of device and electrically conducting elements becomes more challenging as features reach the deep nanoscale regime. In this work, high resolution transmission electron microscopy (TEM) coupled with energy dispersive x-ray (EDX) characterization were used to analyze the pattern transfer of graphoepitaxially aligned block copolymer (BCP) features to germanium (Ge) substrates as a function of time. The BCP patterns were converted into metal oxide hardmasks in order to affect good aspect ratios of the transferred features. An unusual interface layer between metal oxide nanowires and the germanium-on-insulator substrate was observed. EDX analysis shows that the origin of this interface layer is a result of the presence of a negative tone e-beam resist material, HSQ (hydrogen silsesquioxane). HSQ was employed as a guiding material to align line-space features of poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) BCP with 16 nm half-pitch topography. Additionally, the existence of a metal oxide layer (from the initial PS-b-P4VP film) is also shown through ex situ TEM and EDX characterization. Three dimensional modeling of features is also provided giving a unique insight into the arrangement and structure of BCP features prior to and after the pattern transfer process. The results presented in this article highlight the accuracy of high resolution electron microscopy and elemental mapping of BCP generated on-chip etch masks to observe and understand through-film features affecting pattern transfer.

  10. High-resolution methane emission estimates using surface measurements and the InTEM inversion system.

    NASA Astrophysics Data System (ADS)

    Connors, Sarah; Manning, Alistair; Robinson, Andrew; Riddick, Stuart; Forster, Grant; Oram, Dave; O'Doherty, Simon; Harris, Neil

    2015-04-01

    High quality GHG emission estimates will be required to successfully tackle climate change. There is a growing need for comparisons between emission estimates produced using bottom-up and top-down techniques at high spatial resolution. Here, a top-down inversion approach combining multi-year atmospheric measurements and an inversion model, InTEM, was used to estimate methane emissions for a region in the South East of the UK (~100 x 150 km). We present results covering a 2-year period (July 2012 - July 2014) in which atmospheric methane concentrations were recorded at 1 - 2 minute time-steps at four locations within the region of interest. Precise measurements were obtained using gas chromatography with flame ionisation detection (GC-FID) for all sites except one, which used a PICARRO Cavity Ring-Down Spectrometer (CRDS). These observations, along with the UK Met Office's Lagrangian particle dispersion model, NAME, were used within InTEM to produce the methane emission fields. We present results from both Bayesian and non-prior based inversion analysis at varying spatial resolutions, for annual, seasonal and monthly time frames. These results are compared with the UK National Atmospheric Emissions Inventory (NAEI) which is compiled using bottom-up methods and available at 1x1 km resolution. A thorough assessment of uncertainty is incorporated into this technique which is represented in the results. This project is part of the UK GAUGE campaign which aims to produce robust estimates of the UK GHG budget using new and existing measurement networks (e.g. the UK DECC GHG network) and modelling activities at a range of scales.

  11. Characterization of Pebax angioplasty balloon surfaces with AFM, SEM, TEM, and SAXS.

    PubMed

    Warner, Jacob A; Forsyth, Bruce; Zhou, Fang; Myers, Jason; Frethem, Chris; Haugstad, Greg

    2016-04-01

    In the medical device industry, angioplasty balloons have been widely used in the less invasive treatment of heart disease by expanding and relieving clogged structures in various arterial segments. However, new applications using thin coatings on the balloon surface have been explored to enhance therapeutic value in the delivery of pharmaceuticals (drug-elution) or control thermal energy output (RF ablation). In this study, angioplasty balloon materials comprised of poly(ether-block-amide) (Pebax) were investigated via atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS) to characterize physical properties at the balloon surface that may affect coating adhesion. The soft segment of this Pebax 1074 material is polyethylene oxide (PEO) and the hard segment is nylon-12. The morphology of the hard segments of this block co-polymer are found via AFM stiffness measurements to be (40 ± 20) nm by (300 ± 150) nm and are oriented parallel to the surface of the balloon. SAXS measurements found the lamellar spacing to be (18.5 ± 0.5) nm, and demonstrate a preferential orientation in agreement with TEM and AFM measurements. Fixation of this balloon in resin, followed by cryo-sectioning is shown to provide a novel manner in which to investigate surface characteristics on the balloon such as material or coating thickness as well as uniformity in comparison to the bulk structure. These outputs were deemed critical to improve overall balloon processing such as molding and surface treatment options for robust designs toward better procedural outcomes targeting new therapeutic areas.

  12. Characterization of TEM-1 β-Lactamase-Producing Kingella kingae Clinical Isolates

    PubMed Central

    Banerjee, Anushree; Kaplan, Jeffrey B.; Soherwardy, Amenah; Nudell, Yoav; Mackenzie, Grace A.; Johnson, Shannon

    2013-01-01

    Kingella kingae is a human pathogen that causes pediatric osteoarticular infections and infective endocarditis in children and adults. The bacterium is usually susceptible to β-lactam antibiotics, although β-lactam resistance has been reported in rare isolates. This study was conducted to identify β-lactam-resistant strains and to characterize the resistance mechanism. Screening of a set of 90 K. kingae clinical isolates obtained from different geographic locations revealed high-level resistance to penicillins among 25% of the strains isolated from Minnesota and Iceland. These strains produced TEM-1 β-lactamase and were shown to contain additional ≥50-kb plasmids. Ion Torrent sequencing of extrachromosomal DNA from a β-lactamase-producing strain confirmed the plasmid location of the blaTEM gene. An identical plasmid pattern was demonstrated by multiplex PCR in all β-lactamase producers. The porin gene's fragments were analyzed to investigate the relatedness of bacterial strains. Phylogenetic analysis revealed 27 single-nucleotide polymorphisms (SNPs) in the por gene fragment, resulting in two major clusters with 11 allele types forming bacterial-strain subclusters. β-Lactamase producers were grouped together based on por genotyping. Our results suggest that the β-lactamase-producing strains likely originate from a single plasmid-bearing K. kingae isolate that traveled from Europe to the United States, or vice versa. This study highlights the prevalence of penicillin resistance among K. kingae strains in some regions and emphasizes the importance of surveillance for antibiotic resistance of the pathogen. PMID:23796935

  13. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

    NASA Astrophysics Data System (ADS)

    Liang, D.; Almeida, J.

    2014-08-01

    The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

  14. Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

    SciTech Connect

    Zieliński, W. Płociński, T.; Kurzydłowski, K.J.

    2015-06-15

    We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens prepared by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.

  15. Nano-scale Petrography of Permian-Basin Halite by TEM

    NASA Astrophysics Data System (ADS)

    Nemer, M. B.; Powers, D. W.; Ismail, A. E.

    2009-12-01

    Halite from the upper Permian Salado Formation of the Permian basin has been extensively studied over the last century. Few researchers, however, have looked at these units at the nano-scale. This is partially due to the difficulty of preparing soft-ionic-crystal samples for TEM studies, and because of the inherent artifacts created in the sectioning and imaging process. We have ultramicrotomed and imaged halite from the Salado in a 200kV TEM. An interesting find is the presence of a ≈ 30 nm transition zone of crystal surrounding some (but not all) fluid inclusions in primary halite (chevron crystal). The transition-zone crystal appears to be oriented differently than the bulk halite crystal away from the transition zone. The thickness of the transition zone does not seem to be sensitive to the dimensions of the inclusion which rules out pressure-temperature changes in solubility in such a small volume. The cause of these transition zones is unknown. Several interesting petrofabrics can also be seen in the primary halite. Fluid-inclusion-banded halite contains bands of very small (< 100 nm) fluid inclusions. Some inclusions appear to have trails of smaller drops, as if due to a drop-breakup event. This is curious because we don’t expect breakup events in a primary crystal. A “myrmekite” like texture has been observed that contains a series of indentations and spurs along the bedding plane. A turbulent fabric has been observed which contains small eddy-like structures . At this time, we are not able to interpret these fabrics with confidence or determine which are real and which are artifacts. This work is considered preliminary and should not be cited, as some samples were not collected under the Waste Isolation Pilot Plant (WIPP) Quality Assurance (QA) program. This work will be repeated in the future with full WIPP QA.

  16. Deep sounding TEM investigation method based on a modified fixed central-loop system

    NASA Astrophysics Data System (ADS)

    Xue, Guo-qiang; Bai, Chao-ying; Yan, Shu; Greenhalgh, Stewart; Li, Mei-fang; Zhou, Nan-nan

    2012-01-01

    The central-loop TEM technology has been widely used in mineral exploration, engineering and environmental investigations and assorted geologic studies. For easy and efficient working conditions, a square (or rectangular) loop is generally employed instead of a circular one. Any position within the inner one ninth of the central part of the loop is often designated as the central survey location (within which the field is assumed to be uniform), and referred to as a modified central-loop configuration. However, the deduced field parameters at such non-central positions when calculated by a central-loop formula result in decreased accuracy and possibly erroneous interpretation. A large-fixed loop offers the advantage of being able to determine the induced potential at any point inside or outside the loop. In this study we provide the formula for the large-fixed loop and receiver positions within the modified central-loop system and solve the problem. Specifically, we compute the electromagnetic response of any field point by using an electric dipole integration method. The full time-domain apparent resistivity values are then extracted by using an iterative method. Both theoretical modeling and real data examples indicate that such a configuration not only improves the accuracy for the TEM survey, but also enlarges the exploration depth, due to a large loop used in the deployment. The method is used for locating the water enriched areas in coal mines in Yangquan region of Shanxi province and in Bin County of Shaanxi province, China. The interpreted results are tested by later drilling, which confirmed our combined method to be a reliable and efficient method for deep sounding.

  17. Quasi-TEM electromagnetic modes of a plasma waveguide with a nonsimply connected cross section in an external magnetic field

    SciTech Connect

    Kartashov, I. N. Kuzelev, M. V.

    2014-12-15

    Electromagnetic modes of a plasma waveguide with a nonsimply connected cross section in an external magnetic field are investigated. The existence of quasi-TEM modes in a finite-strength magnetic field is demonstrated. It is shown that, in the limits of infinitely strong and zero magnetic fields, this mode transforms into a true TEM mode. The possibility of excitation of such modes by an electron beam in the regime of the anomalous Doppler effect is analyzed.

  18. Coupling spindle position with mitotic exit in budding yeast: The multifaceted role of the small GTPase Tem1.

    PubMed

    Scarfone, Ilaria; Piatti, Simonetta

    2015-10-02

    The budding yeast S. cerevisiae divides asymmetrically and is an excellent model system for asymmetric cell division. As for other asymmetrically dividing cells, proper spindle positioning along the mother-daughter polarity axis is crucial for balanced chromosome segregation. Thus, a surveillance mechanism named Spindle Position Checkpoint (SPOC) inhibits mitotic exit and cytokinesis until the mitotic spindle is properly oriented, thereby preventing the generation of cells with aberrant ploidies. The small GTPase Tem1 is required to trigger a Hippo-like protein kinase cascade, named Mitotic Exit Network (MEN), that is essential for mitotic exit and cytokinesis but also contributes to correct spindle alignment in metaphase. Importantly, Tem1 is the target of the SPOC, which relies on the activity of the GTPase-activating complex (GAP) Bub2-Bfa1 to keep Tem1 in the GDP-bound inactive form. Tem1 forms a hetero-trimeric complex with Bub2-Bfa1 at spindle poles (SPBs) that accumulates asymmetrically on the bud-directed spindle pole during mitosis when the spindle is properly positioned. In contrast, the complex remains symmetrically localized on both poles of misaligned spindles. We have recently shown that Tem1 residence at SPBs depends on its nucleotide state and, importantly, asymmetry of the Bub2-Bfa1-Tem1 complex does not promote mitotic exit but rather controls spindle positioning.

  19. Coupling spindle position with mitotic exit in budding yeast: The multifaceted role of the small GTPase Tem1

    PubMed Central

    Scarfone, Ilaria; Piatti, Simonetta

    2015-01-01

    The budding yeast S. cerevisiae divides asymmetrically and is an excellent model system for asymmetric cell division. As for other asymmetrically dividing cells, proper spindle positioning along the mother-daughter polarity axis is crucial for balanced chromosome segregation. Thus, a surveillance mechanism named Spindle Position Checkpoint (SPOC) inhibits mitotic exit and cytokinesis until the mitotic spindle is properly oriented, thereby preventing the generation of cells with aberrant ploidies. The small GTPase Tem1 is required to trigger a Hippo-like protein kinase cascade, named Mitotic Exit Network (MEN), that is essential for mitotic exit and cytokinesis but also contributes to correct spindle alignment in metaphase. Importantly, Tem1 is the target of the SPOC, which relies on the activity of the GTPase-activating complex (GAP) Bub2-Bfa1 to keep Tem1 in the GDP-bound inactive form. Tem1 forms a hetero-trimeric complex with Bub2-Bfa1 at spindle poles (SPBs) that accumulates asymmetrically on the bud-directed spindle pole during mitosis when the spindle is properly positioned. In contrast, the complex remains symmetrically localized on both poles of misaligned spindles. We have recently shown that Tem1 residence at SPBs depends on its nucleotide state and, importantly, asymmetry of the Bub2-Bfa1-Tem1 complex does not promote mitotic exit but rather controls spindle positioning. PMID:26507466

  20. Cooperative use of VCD and XRD for the determination of tetrahydrobenzoisoquinolines absolute configuration: a reliable proof of memory of chirality and retention of configuration in enediyne rearrangements.

    PubMed

    Mondal, Shovan; Naubron, Jean-Valère; Campolo, Damien; Giorgi, Michel; Bertrand, Michéle P; Nechab, Malek

    2013-12-01

    The absolute configurations (AC) of azaheterocylic compounds resulting from the cascade rearrangement of enediynes involving only light atoms were unambiguously assigned by the joint use of vibrational circular dichroism (VCD) and copper radiation single crystal X-ray diffraction (XRD). These AC determinations proved that the rearrangements of enediynes proceeded with memory of chirality and retention of configuration.

  1. Mineralogical In-Situ Investigation of Acid-Sulfate Samples from the Rio Tinto River, Spain, with a Portable XRD/XRF Instrument

    NASA Astrophysics Data System (ADS)

    Sarrazin, P.; Ming, D. W.; Morris, R. V.; Fernández-Remolar, D.; Amils, R.; Arvidson, R. E.; Blake, D.; Bish, D. L.

    2007-03-01

    The CheMin 4 XRD/XRF prototype was deployed in Rio Tinto, Spain, for a field campaign to study river bed sediments and test the potential of an instrument suite in an astrobiological investigation context for future Mars surface robotic missions.

  2. Quantitative In Situ TEM Studies of Small-Scale Plasticity in Irradiated and Unirradiated Metals

    NASA Astrophysics Data System (ADS)

    Chisholm, Claire

    In this work, unirradiated and irradiated model body centered cubic (BCC) and face centered cubic (FCC) materials are investigated using advanced electron microscopy techniques to quantitatively measure local stresses and strains around defects, with the overarching goal of obtaining a fundamental understanding of defect physics. Quantitative in-situ transmission electron microscopy (TEM) tensile tests are performed with Molybdenum-alloy nano-fibers, functioning as a model BCC structural material. Local true stress and strain around an active Frank-Read type dislocation source are obtained using quantitative load-displacement data and digital image correlation. A mixed Frank-Read dislocation source, b=a/2[-1-11](112) with a line direction 20° from a screw orientation and length 177 nm, is observed to begin operating at a measured local stress of 1.38 GPa. The measured local true stress values compare very well to estimated stresses using dislocation radius of curvature, and a line-tension model of a large bow-out configuration, with differences of only ˜1%. The degree to which the local true stresses can be measured is highly promising. However, the ultimate failure mode of these fibers, sudden strain softening after dislocation starvation and exhaustion, cannot be captured at the typical camera frame rate of 30 frames per second. Thus, fibers are mechanically tested while under observation with the Gatan K2-IS direct electron detector camera, where the frame rate is an order of magnitude larger at 400 fps. Though the increase in frame rate adds to the overall understanding of the sudden failure, by definitively showing that the nano-fibers break rather than strain soften, the failure mechanism still operates too quickly to be observed. In the final investigation of this BCC model structural alloy, the mechanical behavior of heavily dislocated, but unirradiated, and He1+ and Ni 2+ irradiated nano-fibers are compared. Remarkable similarities are found in the

  3. Correlated NanoSIMS, TEM, and XANES Studies of Presolar Grains

    NASA Astrophysics Data System (ADS)

    Groopman, Evan Edward

    The objective of this thesis is to describe the correlated study of individual presolar grains via Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS), Transmission Electron Microscopy (TEM), and Scanning Transmission X-ray Microscopy (STXM) utilizing X-ray Absorption Near Edge Structure (XANES), with a focus on connecting these correlated laboratory studies to astrophysical phenomena. The correlated isotopic, chemical, and microstructural studies of individual presolar grains provide the most detailed description of their formation environments, and help to inform astrophysical models and observations of stellar objects. As a part of this thesis I have developed and improved upon laboratory techniques for micromanipulating presolar grains and embedding them in resin for ultramicrotomy after NanoSIMS analyses and prior to TEM characterization. The new methods have yielded a 100% success rate and allow for the specific correlation of microstructural and isotopic properties of individual grains. Knowing these properties allows for inferences to be made regarding the condensation sequences and the origins of the stellar material that condensed to form these grains. NanoSIMS studies of ultramicrotomed sections of presolar graphite grains have revealed complex isotopic heterogeneities that appear to be primary products of the grains' formation environments and not secondary processing during the grains' lifetimes. Correlated excesses in 15N and 18O were identified as being carried by TiC subgrains within presolar graphite grains from supernovae (SNe). These spatially-correlated isotopic anomalies pinpoint the origin of the material that formed these grains: the inner He/C zone. Complex microstructures and isotopic heterogeneities also provide evidence for mixing in globular SN ejecta, which is corroborated by models and telescopic observations. In addition to these significant isotopic discoveries, I have also observed the first reported nanocrystalline core

  4. The Formation Mechanism of Mesoporous Materials studied by EPR Spectroscopy and Cryo-TEM

    NASA Astrophysics Data System (ADS)

    Ruthstein, Sharon

    Ordered mesoporous materials raised a wide interest in the scientific community due to their unique structural properties which encompasses nanosize ordered channels. These materials have potential applications in diverse technological fields such as catalysis, membranes, microelectronics and sensors. The formation of these materials is initiated by the interaction of micelle of surfactant molecules with precursors of an inorganic oxide, usually silica, which further polymerizes to form solids with a well defined pore structure and amorphous walls. The aim of this study is to explore the details of this intriguing reaction mechanism on two types of materials, hexagonal and cubic, prepared with Pluronic block-copolymers as surfactants. The Pluronic micelles are characterized by a hydrophobic polypropylene oxide core and a hydrophilic polyethylene oxide corona. Examples of questions we address are: How does a homogeneous micellar solution transforms into an ordered phase? What kinds of interactions are responsible to this transformation? Our work focused on processes that take place on two levels, the molecular one and the mesoscale, which were investigated by combining electron paramagnetic resonance (EPR) and cryogenic transmission electron microscopy (cryo-TEM) techniques. The molecular level studies combine in-situ and freeze quench EPR spectroscopic techniques applied to nitroxide spin-probes introduced (at minute quantities) into the reaction mixtures. The nitroxide radicals serve as paramagnetic probes in the reaction mixture. They do not react or affect the reaction product but they sense in-situ the changes that occur in their environment during the reaction. The EPR spectrum provides information regarding the dynamic of the probe, which is affected by its surrounding, and the polarity of its environment. Fine structural details, such as the distribution of water and additives within the micelle, can be obtained from Electron Spin Echo Envelope Modulation

  5. XRD measurement of mean thickness, thickness distribution and strain for illite and illite-smectite crystallites by the Bertaut-Warren-Averbach technique

    USGS Publications Warehouse

    Drits, V.A.; Eberl, D.D.; Srodon, J.

    1998-01-01

    A modified version of the Bertaut-Warren-Averbach (BWA) technique (Bertaut 1949, 1950; Warren and Averbach 1950) has been developed to measure coherent scattering domain (CSD) sizes and strains in minerals by analysis of X-ray diffraction (XRD) data. This method is used to measure CSD thickness distributions for calculated and experimental XRD patterns of illites and illite-smectites (I-S). The method almost exactly recovers CSD thickness distributions for calculated illite XRD patterns. Natural I-S samples contain swelling layers that lead to nonperiodic structures in the c* direction and to XRD peaks that are broadened and made asymmetric by mixed layering. Therefore, these peaks cannot be analyzed by the BWA method. These difficulties are overcome by K-saturation and heating prior to X-ray analysis in order to form 10-A?? periodic structures. BWA analysis yields the thickness distribution of mixed-layer crystals (coherently diffracting stacks of fundamental illite particles). For most I-S samples, CSD thickness distributions can be approximated by lognormal functions. Mixed-layer crystal mean thickness and expandability then can be used to calculate fundamental illite particle mean thickness. Analyses of the dehydrated, K-saturated samples indicate that basal XRD reflections are broadened by symmetrical strain that may be related to local variations in smectite interlayers caused by dehydration, and that the standard deviation of the strain increases regularly with expandability. The 001 and 002 reflections are affected only slightly by this strain and therefore are suited for CSD thickness analysis. Mean mixed-layer crystal thicknesses for dehydrated I-S measured by the BWA method are very close to those measured by an integral peak width method.

  6. TEM Cell Testing of Cable Noise Reduction Techniques From 2 MHz to 200 MHz - Part 1

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T.; Evans, William C.; Reed, Joshua L.; Shimp, Samuel K.; Fitzpatrick, Fred D.

    2008-01-01

    This paper presents empirical results of cable noise reduction techniques as demonstrated in a TEM cell operating with radiated fields from 2 - 200 MHz. It is the first part of a two-paper series. This first paper discusses cable types and shield connections. In the second paper, the effects of load and source resistances and chassis connections are examined. For each topic, well established theories are compared to data from a real-world physical system. Finally, recommendations for minimizing cable susceptibility (and thus cable emissions) are presented. There are numerous papers and textbooks that present theoretical analyses of cable noise reduction techniques. However, empirical data is often targeted to low frequencies (e.g. <50 KHz) or high frequencies (>100 MHz). Additionally, a comprehensive study showing the relative effects of various noise reduction techniques is needed. These include the use of dedicated return wires, twisted wiring, cable shielding, shield connections, changing load or source impedances, and implementing load- or source-to-chassis isolation. We have created an experimental setup that emulates a real-world electrical system, while still allowing us to independently vary a host of parameters. The goal of the experiment was to determine the relative effectiveness of various noise reduction techniques when the cable is in the presence of radiated emissions from 2 MHz to 200 MHz. The electronic system (Fig. 1) consisted of two Hammond shielded electrical enclosures, one containing the source resistance, and the other containing the load resistance. The boxes were mounted on a large aluminium plate acting as the chassis. Cables connecting the two boxes measured 81 cm in length and were attached to the boxes using standard D38999 military-style connectors. The test setup is shown in Fig. 2. Electromagnetic fields were created using an HP8657B signal generator, MiniCircuits ZHL-42W-SMA amplifier, and an EMCO 5103 TEM cell. Measurements were

  7. Experimental Space Weathering: A coordinated LIBS, TEM, VIS and NIR/MIR study

    NASA Astrophysics Data System (ADS)

    Stojic, Aleksandra N.; Pavlov, Sergey; Markus, Kathrin; Morlok, Andreas; Wirth, Richard; Weber, Iris; Schreiber, Anja; Hiesinger, Harald; Sohn, Martin; Huebers, Heinz-Wilhelm

    2016-04-01

    We conducted pulsed infrared laser irradiation experiments, in order to simulate space weathering triggered modifications of planetary surfaces not protected by an enveloping atmosphere [1,2], e.g., Mercury. Our work is embedded in the framework of the BepiColombo space mission to Mercury [3]. The MErcury Radiometer and Thermal Infrared Spectrometer (MERTIS), an onboard spectrometer will deliver surface data in the range of 7 - 14 μm once it reaches orbit in 2024 [4]. Space weathering effects known from other Solar System bodies are likely to be very prominent on Mercury due to its proximity to the Sun, the lack of a protective atmosphere and its weak magnetic field [5]. Space weathering effects, e.g., implantation of solar wind in regolith material, sputtering and (micro) meteorite impacts modify the planetary surface and thus, therefrom obtained spectral data in the VIS/NIR range considerably (e.g., reddening and darkening of spectra) [6-9]. We expect modifications induced by space weathering, known from the VIS/NIR range also to show in the mid infrared range, probably by amorphisation or similar still unknown effects [2,10]. Our approach is therefore threefold: a) alter analog material artificially by pulsed laser experiments, b) investigate altered analog material spectrally (VIS/NIR and MIR range) and c) conduct transmission electron microscopy (TEM) studies on selected weathered grains to better understand the nanostratigraphy developed by irradiation and its impact on the resulting infrared spectra. Here, we report on results obtained from the first set of experiments. Characteristic upper mantle minerals were taken as analog material, Mg-rich olivine and pyroxene, were ground into a powder (< 160 μm), slightly compressed into pellets and subsequently irradiated under high vacuum conditions (˜ 10-6 mbar) with a pulsed (˜ 8ns) infrared laser at a fluence of ˜ 2 Jcm-2. From the irradiated pellet surfaces, VIS/NIR and MIR spectra were obtained and

  8. Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

    PubMed

    Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

    2013-11-26

    The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (μ) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ∼2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of μ on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ∼3.5 nm thick layer (mean dissociation pK ∼ 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ∼ 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film.

  9. He Transport and Fate of Tempered Martensitic Steels: Summary of Recent TEM Observations

    SciTech Connect

    Edwards, Danny J.; Kurtz, Richard J.; Odette, G Robert; Yamamoto, Takuya

    2010-02-26

    As an extension of prior work [1-4], we summarize recent observations made on a He-implanted tempered martensitic steel (TMS), F82H mod 3, irradiated in the HFIR, in both as-tempered (AT) and cold-worked (CW) conditions. A novel implantation technique was used to uniformly inject He into 3-mm diameter TEM discs to depths ranging from ≈ 5-8 µm. The He is generated by two-step transmutation reactions in Ni contained in a NiAl coating layer adjacent to paired 3 mm TEM discs. NiAl layers from 1 to 4 μm thick produced He/dpa ratios between 5 and 40 appm/dpa. The irradiations were at temperatures of 300, 400 and 500°C from 3.9 to 9 dpa and 90 to 380 appm He. Electron transparent samples were prepared by a cross-sectional thinning technique that allowed investigating microstructural evolution over a range of implantation depths. Irradiation of the AT alloy to 9 dpa at 500°C and 380 appm He resulted in relatively large, faceted cavities, that are likely voids, along with a much higher density of smaller He bubbles. The cavities were most often aligned in pearl necklace like strings, presumably due to their formation on pre-existing dislocations. A finer distribution of cavities was also present on precipitate interfaces, lath and grain boundaries. Nine dpa irradiations that produced 190 appm He resulted in a somewhat more random distribution and lower density of smaller matrix cavities; but lower He levels had a less noticeable effect on bubbles in the lath and precipitate boundaries. Corresponding irradiations of the CW F82H produced a larger number of smaller cavities. Irradiation of the AT alloy to 3.9 dpa and 90 ppm He at 400°C produced a similar cavity population to that observed at 500°C at 190 appm He, while the corresponding cavities at 500°C are slightly larger and more numerous at 380 appm He. The cavity strings were less obvious for the 400°C irradiations, and the bubble distribution appeared to be more random. No cavities were observed in the case of

  10. TEM-1 AND ROB-1 PRESENCE AND ANTIMICROBIAL RESISTANCE IN HAEMOPHILUS INFLUENZAE STRAINS, ISTANBUL, TURKEY.

    PubMed

    Kuvat, Nuray; Nazik, Hasan; Berkiten, Rahmiye; Öngen, Betigül

    2015-03-01

    Resistance of 235 Haemophilus influenzae clinical isolates from Istanbul Medical Faculty Hospital, Turkey were determined against 19 antibiotics by disc diffusion method, and minimum inhibitory concentrations (MICs) of those found resistant to ampicillin, cefuroxim, chloramphenicol and meropenem were measured using E-test. Ampicillin-resistant isolates producing beta-lactamase as demonstrated by a nitrocefin assay were analyzed for the presence of TEM-1 and ROB-1 genes by PCR. Eleven percent of the isolates were resistant to ampicillin (10 µg/ml), of which 73% were beta-lactamase positive and carried TEM-1 gene, but none were positive for ROB-1 gene. All isolates susceptible to amoxicillin-clavulanate (20/10 µg/ml), azithromycin (15 µg/ml), aztreonam (30 µg/ml), cefotaxime (30 µg/ml), ceftriaxone (30 µg/ml), ciprofloxacin (5 µg/ml), levofloxacin (5 µg/ml), and telithromycin (15 µg/ml) but 24%, 15%, 4%, 4%, 2%, 1%, 1%, 0.5%, 0.5% and 0.5% were resistant to trimethoprim-sulfamethoxazole (1.25/23.75 µg/ml), tetracycline (30 µg/ml), cefaclor (30 µg/ml), clarithromycin (15 µg/ml), cefuroxime (30 µg/ml), meropenem (10 µg/ml), chloramphenicol (30 µg/ml), ampicillin-sulbactam (10/10 µg/ml), nalidixic acid (30 µg/ml), and fosfomycin (30 µg/ml), respectively. MIC values of three cefuroxime-resistant isolates was 24, 48 and > 256 µg/ml, respectively; of two meropenem-resistant strains > 256 µg/ml; and of two chloramphenicol-susceptible isolates (by disc diffusion method) 6 µg/ml (considered as intermediate susceptible). Multiple- antibiotics resistance was detected in 15% of the strains, with resistance to 2, 3, 4, 5 and 6 antibiotics in 8.5%, 4%, 2%, 0.5% and 0.5% of the isolates, respectively. By identifying beta-lactamase-negative ampicillin-resistant H. influenzae, empirical therapy with beta-lactam/beta-lactamase inhibitor combinations and second generation cephalosporins would be inappropriate for such patients (approximately 3%). Our findings will

  11. The Telemedical Rescue Assistance System "TemRas"--development, first results, and impact.

    PubMed

    Büscher, Christian; Elsner, Jesko; Schneiders, Marie-Thérèse; Thelen, Sebastian; Brodziak, Tadeusz; Seidenberg, Peter; Schilberg, Daniel; Tobias, Michael; Jeschke, Sabina

    2014-04-01

    German emergency medical services (EMS) face the challenge of ensuring high-quality emergency care against a background of continuously increasing numbers of emergency missions, resource shortages concomitant with greatly increased arrival times, particularly in rural areas. Because German EMS physicians are at maximum capacity, an immediate response is not always possible, and thus delays in commencing advanced life support measures sometimes occur. In such scenarios, paramedics start the initial treatment until the EMS physician arrives. The delayed availability of a physician can defer the decision process of the paramedics and thus postpone the start of the patient's essential treatment, which is particularly dangerous during the care of cardiovascular emergencies. Therefore, the project Telemedical Rescue Assistance System (TemRas) has developed an innovative concept to improve quality of emergency care. The objective is to introduce so-called tele-EMS physicians providing remote medical support for the emergency team on site by transmitting audio and video data as well as vital signs and 12-lead-ECG from the emergency site to a teleconsultation center. In this article, the development process as well as the first results of the evaluation phase and the impact for further use of telemedicine in EMS are presented.

  12. TEM characterization of in-reactor neutron irradiated CANDU spacer material Inconel X-750

    NASA Astrophysics Data System (ADS)

    Zhang, He Ken; Yao, Zhongwen; Morin, Gregory; Griffiths, Malcolm

    2014-08-01

    The irradiation induced defects in CANDU Inconel X-750 spacers, which were removed from reactors after about 14 effective full power years, were examined by transmission electron microscopy (TEM). The spacers in the form of garter springs were reported to operate at various temperatures depending on locations. Two samples from different locations with different estimated irradiation temperatures were tested: (1) ∼180 °C at 6 o’clock position and (2) ⩾300 °C at 12 o’clock position. Obvious temperature effects were observed. In the ∼180 °C irradiated sample, a high density of small lattice defects (1-3 nm) developed during irradiation, including stacking fault tetrahedra and both 1/3 <1 1 1> and ½ <1 1 0> type dislocation loops. A uniform distribution of small cavities (∼1-3 nm) was observed. In >300 °C irradiated sample, apart from small point defect clusters, large Frank type interstitial loops presented. The sizes of the cavities were also greater than those in the ∼180 °C irradiated sample. The distribution of cavities was more heterogeneous and an obvious agglomeration of cavities to grain boundaries and phase boundaries were observed. In both samples, dissolution of the primary strengthening phase γ‧ was noted.

  13. Chemical mapping of DNA and counter-ion content inside phage by energy-filtered TEM.

    PubMed

    Nevsten, Pernilla; Evilevitch, Alex; Wallenberg, Reine

    2012-03-01

    Double-stranded DNA in many bacterial viruses (phage) is strongly confined, which results in internal genome pressures of tens of atmospheres. This pressure is strongly dependent on local ion concentration and distribution within the viral capsid. Here, we have used electron energy loss spectroscopy (EELS), energy-filtered TEM (EFTEM) and X-ray energy dispersive spectroscopy to provide such chemical information from the capsid and the phage tail through which DNA is injected into the cell. To achieve this, we have developed a method to prepare thin monolayers of self-supporting virus/buffer films, suitable for EELS and EFTEM analysis. The method is based on entrapment of virus particles at air-liquid interfaces; thus, the commonly used method of staining by heavy metal salts can be avoided, eliminating the risk for chemical artifacts. We found that Mg(2 + ) concentration was approximately 2-4 times higher in the DNA-filled capsid than in the surrounding TM buffer (containing 10 mM Mg(2 + )). Furthermore, we also analyzed the DNA content inside the phage tail by mapping phosphorus and magnesium.

  14. Cryo-TEM structural analysis of conjugated nonionic engineered-micelles.

    PubMed

    Patchornik, Guy; Wachtel, Ellen; Kesselman, Ellina; Danino, Dganit

    2014-07-21

    Conjugated engineered-micelles, i.e. micelles that are composed of nonionic detergents and hydrophobic chelators and subsequently conjugated in the presence of divalent metal ions, have been shown to be remarkably suited to the task of membrane protein purification, maintaining these proteins in their native state. They also efficiently solubilize highly hydrophobic antibiotics. To date, however, the morphological changes induced in the initially spherical or ellipsoidal micelles by conjugation have not been explored. In this study, the very rapid sample-vitrification protocol of cryogenic transmission electron microscopy (cryo-TEM) has been used to capture structural transformations that engineered-micelles undergo immediately following conjugation with the [(bathophenanthroline)3:Fe(2+)] hydrophobic complex. We found that condensed thread-like aggregates are formed when the detergents used are: octyl β-D-glucopyranoside (OG), octyl β-D-thioglucopyranoside (OTG) or pentaethylene glycol monododecyl ether (C12E5). However, with β-D-maltoside (DM), n-dodecyl β-D-maltoside (DDM) or β-D-glucopyranoside (DDG), lamellar structures, some of which appear as stacked lamellae or multilamellar vesicles (MLV's), were observed. Such architectural changes occur under very mild conditions i.e. low detergent concentration, no temperature or pH alterations and without the presence of any precipitants such as PEG or ammonium sulfate.

  15. TEM Cell Testing of Cable Noise Reduction Techniques from 2 MHz to 200 MHz -- Part 2

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T.; Evans, William C.; Reed, Joshua L.; Shimp, Samuel K., III; Fitzpatrick, Fred D.

    2008-01-01

    This paper presents empirical results of cable noise reduction techniques as demonstrated in a TEM cell operating with radiated fields from 2 - 200 MHz. It is the second part of a two-paper series. The first paper discussed cable types and shield connections. In this second paper, the effects of load and source resistances and chassis connections are examined. For each topic, well established theories are compared to data from a real-world physical system. Finally, recommendations for minimizing cable susceptibility (and thus cable emissions) are presented. There are numerous papers and textbooks that present theoretical analyses of cable noise reduction techniques. However, empirical data is often targeted to low frequencies (e.g. <50 KHz) or high frequencies (>100 MHz). Additionally, a comprehensive study showing the relative effects of various noise reduction techniques is needed. These include the use of dedicated return wires, twisted wiring, cable shielding, shield connections, changing load or source impedances, and implementing load- or source-to-chassis isolation. We have created an experimental setup that emulates a real-world electrical system, while still allowing us to independently vary a host of parameters. The goal of the experiment was to determine the relative effectiveness of various noise reduction techniques when the cable is in the presence of radiated emissions from 2 MHz to 200 MHz.

  16. Observation of thermally etched grain boundaries with the FIB/TEM technique

    SciTech Connect

    Palizdar, Y.; San Martin, D.; Ward, M.; Cochrane, R.C.; Brydson, R.; Scott, A.J.

    2013-10-15

    Thermal etching is a method which is able to reveal and characterize grain boundaries, twins or dislocation structures and determine parameters such as grain boundary energies, surface diffusivities or study phase transformations in steels, intermetallics or ceramic materials. This method relies on the preferential transfer of matter away from grain boundaries on a polished sample during heating at high temperatures in an inert/vacuum atmosphere. The evaporation/diffusion of atoms at high temperatures results in the formation of grooves at the intersections of the planes of grain/twin boundaries with the polished surface. This work describes how the combined use of Focussed Ion Beam and Transmission Electron Microscopy can be used to characterize not only the grooves and their profile with the surface, but also the grain boundary line below the groove, this method being complementary to the commonly used scanning probe techniques. - Highlights: • Thermally etched low-carbon steel samples have been characterized by FIB/TEM • Grain boundary (GB) lines below the groove have been characterized in this way • Absence of ghost traces and large θ angle suggests that GB are not stationary but mobile • Observations correlate well with previous works and Mullins' investigations [22].

  17. Giant radiolytic dissolution rates of aqueous ceria observed in-situ by liquid-cell TEM.

    PubMed

    Asghar, Muhammad Sajid Ali; Inkson, Beverley J; Moebus, Guenter

    2017-03-09

    Dynamics of cerium oxide nanoparticle aqueous corrosion are revealed in-situ. We use innovative liquid-cell transmission electron microscopy (TEM) combined with deliberate high-intensity electron-beam irradiation of nanoparticle suspensions. This enables life video-recording of materials reactions in liquid, with nm-resolution. We introduce image-quantification to measure detailed rates of dissolution as a function of time and particle size to be compared with literature data. Giant dissolution rates, exceeding any previous reports for chemical dissolution rates at room temperature by many orders of magnitude, are discovered. Reasons for accelerated dissolution are outlined, including the importance of radiolysis of water preceding ceria-attack. Electron-water interaction generates radicals, ions and hydrated electrons, which assist in hydration and reductive dissolution of oxide minerals. The presented methodology has the potential to become a novel accelerated testing procedure to compare multiple nanoscale materials for relative aqueous durability. The ceria-water system is of crucial importance for the fields of catalysis, abrasive polishing, environmental remediation, and as simulant for actinide-oxide behaviour in contact with liquid for nuclear engineering.

  18. In Situ TEM Scratch Testing of Perpendicular Magnetic Recording Multilayers with a Novel MEMS Tribometer

    NASA Astrophysics Data System (ADS)

    Hintsala, Eric D.; Stauffer, Douglas D.; Oh, Yunje; Asif, S. A. Syed

    2017-01-01

    Utilizing a newly developed two-dimensional (2D) transducer designed for in situ transmission electron microscope (TEM) nanotribology, deformation mechanisms of a perpendicular magnetic recording film stack under scratch loading conditions were evaluated. These types of films are widely utilized in storage devices, and loss of data by grain reorientation in the recording layers is of interest. The observed deformation was characterized by a stick-slip mechanism, which was induced by a critical ratio of lateral to normal force regardless of normal force. At low applied normal forces, the diamond-like carbon (DLC) coating and asperities in the recording layer were removed during scratching, while, at higher applied forces, grain reorientation and debonding of the recording layer was observed. As the normal force and displacement were increased, work for stick-slip deformation and contact stress were found to increase based upon an Archard's Law analysis. These experiments also served as an initial case study demonstrating the capabilities of this new transducer.

  19. Outbreak of TEM-24-producing Enterobacter aerogenes in a Spanish hospital.

    PubMed

    Salso, S; Culebras, E; Andrade, R; Picazo, J J

    2003-01-01

    Organisms encoding multidrug resistance genes are becoming increasingly prevalent. During a 2-month period (December, 2000, to January, 2001), 83 consecutive isolates of Enterobacter spp. were collected in our microbiology department. Antibiotic susceptibility was determined using the Vitek II automatic system. We selected strains with decreased susceptibility to extended-spectrum cephalosporins. The double-disk potentiation test was positive in 10 of these strains, indicating the presence of extended-spectrum beta-lactamases (ESBLs). Polymerase chain reaction (PCR), isoelectric focusing (IEF), and sequencing identified TEM 24 beta-lactamase in the 10 selected E. aerogenes. Random amplification of polymorphic DNA (RAPD-PCR) revealed the same clonal origin for all the strains tested and strongly suggest an outbreak of multidrug-resistant E. aerogenes. To follow up the trends in ESBLs-producing Enterobacter infections in the hospital over time, we repeated the study 1 year later (December, 2001, to February, 2002). Only three ESBLs-producing Enterobacter were found. All of them corresponded to the previously characterized clone.

  20. Lte1 contributes to Bfa1 localization rather than stimulating nucleotide exchange by Tem1

    PubMed Central

    Spanos, Adonis; de Bettignies, Geoffroy; Sedgwick, Steven G.

    2009-01-01

    Lte1 is a mitotic regulator long envisaged as a guanosine nucleotide exchange factor (GEF) for Tem1, the small guanosine triphosphatase governing activity of the Saccharomyces cerevisiae mitotic exit network. We demonstrate that this model requires reevaluation. No GEF activity was detectable in vitro, and mutational analysis of Lte1’s putative GEF domain indicated that Lte1 activity relies on interaction with Ras for localization at the bud cortex rather than providing nucleotide exchange. Instead, we found that Lte1 can determine the subcellular localization of Bfa1 at spindle pole bodies (SPBs). Under conditions in which Lte1 is essential, Lte1 promoted the loss of Bfa1 from the maternal SPB. Moreover, in cells with a misaligned spindle, mislocalization of Lte1 in the mother cell promoted loss of Bfa1 from one SPB and allowed bypass of the spindle position checkpoint. We observed that lte1 mutants display aberrant localization of the polarity cap, which is the organizer of the actin cytoskeleton. We propose that Lte1’s role in cell polarization underlies its contribution to mitotic regulation. PMID:19948498

  1. Power Line Noise in Transient Electromagnetic (TEM) Data: Identification and Removal in a Practical Field Study.

    NASA Astrophysics Data System (ADS)

    Jernsletten, J. A.

    2004-05-01

    INTRODUCTION: To evaluate the appropriateness of TEM in mapping deep groundwater tables (in Mars analog environmnets), a field study was carried out in the desert ~30 miles SW of Tucson, Arizona. The study was also designed to observe effects of powerline noise on TEM data. The clay-rich soil in the area is quite conductive. The study consisted of 40 in-loop TEM stations, divided into 3 lines, for 4 line-km of data. The survey was carried out by a crew of one person, with square Tx wire loops 100 m on a side, and a ferrite-core magnetic coil Rx antenna in the center of each Tx loop. Maximum useful depth of investigation achieved was ~600 m. TEM DATA: The field area is surrounded by powerlines on all 4 sides: Line 1 has the outside of the first Tx loop under the powerline to the West; Line 2 starts with the powerline to the North passing above just inside its first Tx loop, and ends with the outside of the last station's transmitter loop ~20 m shy of the powerline to the South; finally, Line 3 starts ~50 m East of the powerline to the West, and runs parallel to the powerline to the South along its entire length, at a separation distance of ~70 m. Line 3 was placed largely in an effort to obeserve powerline noise. The decay curve for the first station on Line 1(Line 1/Station 50) is raised above the other curves from Line 1. This is due to the charge (noise) from the adjacent powerline, which is at a distance of ~50 m from the Rx coil. In effect, the transient decay is recorded as being slower than it would be without the presence of the powerline. This also artficially lowers the apparent resistivity, readily observed in Line 1/Station 50 data. These effects are present to a lesser extent (lower magnitude noise) in the data from Line1/Station 150, the second station on Line 1. On the smooth-model inversion cross-section of the data from Line 1, the effects of the powerline noise appears as a pulling up of the low-resistivity water table contact towards the surface

  2. TEM Observation of the Ti Interlayer Between SiC Substrates During Diffusion Bonding

    NASA Technical Reports Server (NTRS)

    Tsuda, Hiroshi; Mori, Shigeo; Halbig, Michael C.; Singh, Mori

    2012-01-01

    Diffusion bonding was carried out to join SiC to SiC substrates using titanium interlayers. In this study, 10 m and 20 m thick physical vapor deposited (PVD) Ti surface coatings, and 10 and 20 m thick Ti foils were used. Diffusion bonding was performed at 1250 C for PVD Ti coatings and 1200 C for Ti foil. This study investigates the microstructures of the phases formed during diffusion bonding through TEM and selected-area diffraction analysis of a sample prepared with an FIB, which allows samples to be taken from the reacted area. In all samples, Ti3SiC2, Ti5Si3Cx and TiSi2 phases were identified. In addition, TiC and unknown phases also appeared in the samples in which Ti foils were used as interlayers. Furthermore, Ti3SiC2 phases show high concentration and Ti5Si3Cx formed less when samples were processed at a higher temperature and thinner interlayer samples were used. It appears that the formation of microcracks is caused by the presence of intermediate phase Ti5Si3Cx, which has anisotropic thermal expansion, and by the presence of an unidentified Ti-Si-C ternary phase with relatively low Si content.

  3. TEM Characterization of High Burn-up Microstructure of U-7Mo Alloy

    SciTech Connect

    Jian Gan; Brandon Miller; Dennis Keiser; Adam Robinson; James Madden; Pavel Medvedev; Daniel Wachs

    2014-04-01

    As an essential part of global nuclear non-proliferation effort, the RERTR program is developing low enriched U-Mo fuels (< 20% U-235) for use in research and test reactors that currently employ highly enriched uranium fuels. One type of fuel being developed is a dispersion fuel plate comprised of U-7Mo particles dispersed in Al alloy matrix. Recent TEM characterizations of the ATR irradiated U-7Mo dispersion fuel plates include the samples with a local fission densities of 4.5, 5.2, 5.6 and 6.3 E+21 fissions/cm3 and irradiation temperatures of 101-136?C. The development of the irradiated microstructure of the U-7Mo fuel particles consists of fission gas bubble superlattice, large gas bubbles, solid fission product precipitates and their association to the large gas bubbles, grain subdivision to tens or hundreds of nanometer size, collapse of bubble superlattice, and amorphisation. This presentation will describe the observed microstructures specifically focusing on the U-7Mo fuel particles. The impact of the observed microstructure on the fuel performance and the comparison of the relevant features with that of the high burn-up UO2 fuels will be discussed.

  4. TEM investigation of the microporous compound VSB-1: Building units and crystal growth mechanisms

    SciTech Connect

    Colmont, Marie Terasaki, Osamu

    2007-03-15

    Surface fine structure and structural defects in the open framework material VSB-1 have been investigated by electron microscopy. Crystal growth phenomena are proposed by a building unit model: (i) a unit is formed by two building units; (ii) they are linked to form first channels; and (iii) the whole network is grown via a layer-by-layer growth mechanism. A planar defect was observed in high-resolution transmission electron microscope (HRTEM) image taken with the [0001] incidence, and diffuse streaks related to the presence of defects were observed in a series of electron diffraction (ED) patterns. The microstructure model derived from the defect structure gives information on crystal growth. These defects highlight an open site that could be the pillar of a new crystal growth process. The study of defects and crystal growth is important in understanding physical properties such as catalytic or magnetic properties, and in synthesising a new open framework structure. - Graphical abstract: TEM investigation of the microporous compound VSB-1 evidenced defects and information about building units and crystal growth. As usually observed for microporous materials, the crystal growth via a layer by layer mechanism.

  5. TEM in situ deformation study of the interaction of lattice dislocations with grain boundaries in metals

    SciTech Connect

    Lee, T.C.; Robertson, I.M.; Birnbaum, H.K. )

    1990-01-01

    The passage of dislocations across grain boundaries in metals has been studied by using the in situ TEM deformation technique. A detailed analysis of the interaction of glissile matrix dislocations with grain-boundary dislocations has been performed. The results show that the dislocations piled-up at the grain boundary can: (1) be transferred directly through the grain boundary into the adjoining grain; (2) be absorbed and transformed into extrinsic grain-boundary dislocations; (3) be accommodated in the grain boundary, followed by the emission from the grain boundary of a matrix dislocation; and (4) be ejected back into their original grain. To predict which slip system is favorable for slip transfer, three criteria have been considered, namely: (1) the angle between the lines of intersection of the incoming and outgoing slip lanes with the grain boundary, this should be as small as possible; (2) the resolved shear stress acting on the possible slip systems in the adjoining grain, this should be large and (3) the magnitude of the Burgers vector of the extrinsic dislocations left at the grain boundary following emission of dislocations, this should be a minimum. The Burgers vector of the generated dislocation is dictated primarily by condition (3).

  6. Role of pleiotropy during adaptation of TEM-1 β-lactamase to two novel antibiotics

    PubMed Central

    Schenk, Martijn F; Witte, Sariette; Salverda, Merijn L M; Koopmanschap, Bertha; Krug, Joachim; de Visser, J Arjan G M

    2015-01-01

    Pleiotropy is a key feature of the genotype–phenotype map, and its form and extent have many evolutionary implications, including for the dynamics of adaptation and the evolution of specialization. Similarly, pleiotropic effects of antibiotic resistance mutations may affect the evolution of antibiotic resistance in the simultaneous or fluctuating presence of different antibiotics. Here, we study the role of pleiotropy during the in vitro adaptation of the enzyme TEM-1 β-lactamase to two novel antibiotics, cefotaxime (CTX) and ceftazidime (CAZ). We subject replicate lines for four rounds of evolution to selection with CTX and CAZ alone, and in their combined and fluctuating presence. Evolved alleles show positive correlated responses when selecting with single antibiotics. Nevertheless, pleiotropic constraints are apparent from the effects of single mutations and from selected alleles showing smaller correlated than direct responses and smaller responses after simultaneous and fluctuating selection with both than with single antibiotics. We speculate that these constraints result from structural changes in the oxyanion pocket surrounding the active site, where accommodation of CTX and the larger CAZ is balanced against their positioning with respect to the active site. Our findings suggest limited benefits from the combined or fluctuating application of these related cephalosporins for containing antibiotic resistance. PMID:25861383

  7. Coevolutionary Landscape Inference and the Context-Dependence of Mutations in Beta-Lactamase TEM-1

    PubMed Central

    Figliuzzi, Matteo; Jacquier, Hervé; Schug, Alexander; Tenaillon, Oliver; Weigt, Martin

    2016-01-01

    The quantitative characterization of mutational landscapes is a task of outstanding importance in evolutionary and medical biology: It is, for example, of central importance for our understanding of the phenotypic effect of mutations related to disease and antibiotic drug resistance. Here we develop a novel inference scheme for mutational landscapes, which is based on the statistical analysis of large alignments of homologs of the protein of interest. Our method is able to capture epistatic couplings between residues, and therefore to assess the dependence of mutational effects on the sequence context where they appear. Compared with recent large-scale mutagenesis data of the beta-lactamase TEM-1, a protein providing resistance against beta-lactam antibiotics, our method leads to an increase of about 40% in explicative power as compared with approaches neglecting epistasis. We find that the informative sequence context extends to residues at native distances of about 20 Å from the mutated site, reaching thus far beyond residues in direct physical contact. PMID:26446903

  8. TEM and HRTEM studies of ball milled 6061 aluminium alloy powder with Zr addition.

    PubMed

    Lityńska-Dobrzyńska, L; Dutkiewicz, J; Maziarz, W; Rogal, Ł

    2010-03-01

    The effect of mechanical alloying on the microstructure of atomized 6061 aluminium alloy powder and 6061 powder with a zirconium addition was studied in the work. The atomized 6061 aluminium alloy powder and 6061 powder with addition of 2 wt.% Zr were milled in a planetary ball mill and investigated using X-ray diffraction measurements, conventional and high-resolution electron microscopy (TEM/HRTEM) and high-angle annular dark field scanning transmission electron microscopy combined with energy dispersive X-ray microanalysis. An increase of stresses was observed in milled powders after the refinement of crystallites beyond 100 nm. In the powder with zirconium addition, some part of the Zr atoms diffused in aluminium forming a solid solution containing up to 0.5 wt.% Zr. The remaining was found to form Zr-rich particles containing up to 88 wt.% Zr and were identified as face centred cubic (fcc) phase with lattice constant a= 0.48 nm. That fcc phase partially transformed into the L1(2) ordered phase. Eighty-hour milling brought an increase of microhardness (measured with Vickers method) from about 50 HV (168 MPa) for the initial 6061 powder to about 170 HV (552 MPa). The addition of zirconium had no influence on the microhardness.

  9. In-situ TEM observation of dislocation evolution in Kr-irradiated UO2 single crystal

    SciTech Connect

    Lingfeng He; Mahima Gupta; Clarissa A. Yablinsky; Jian Gan; Marquis A. Kirk; Xian-Ming Bai; Janne Pakarinen; Todd R. Allen

    2013-11-01

    In-situ transmission electron microscopy (TEM) observation of UO2 single crystal irradiated with Kr ions at high temperatures was conducted to understand the dislocation evolution due to high-energy radiation. The dislocation evolution in UO2 single crystal is shown to occur as nucleation and growth of dislocation loops at low-irradiation doses, followed by transformation to extended dislocation segments and networks at high doses, as well as shrinkage and annihilation of some loops and dislocations due to high temperature annealing. Generally the trends of dislocation evolution in UO2 are similar under Kr irradiation at different ion energies and temperatures (150 keV at 600 degrees C and 1 MeV at 800 degrees C) used in this work, although the specific dislocation loop size and density are quite different. Interstitial-type dislocation loops with Burgers vector along <110> were observed in the Kr-irradiated UO2.The irradiated specimens were denuded of dislocation loops near the surface.

  10. Microstructural characterization of XLPE electrical insulation in power cables: determination of void size distributions using TEM

    NASA Astrophysics Data System (ADS)

    Markey, L.; Stevens, G. C.

    2003-10-01

    In an effort to progress in our understanding of the ageing mechanisms of high voltage cables submitted to electrical and thermal stresses, we present a quantitative study of voids, the defects which are considered to be partly responsible for cable failure. We propose a method based on large data sets of transmission electron microscopy (TEM) observations of replicated samples allowing for the determination of void concentration distribution as a function of void size in the mesoscopic to microscopic range at any point in the cable insulation. A theory is also developed to calculate the effect of etching on the apparent size of the voids observed. We present the first results of this sort ever obtained on two industrial cables, one of which was aged in an AC field. Results clearly indicate that a much larger concentration of voids occur near the inner semiconductor compared to the bulk of the insulation, independently of ageing. An effect of ageing can also be seen near the inner semiconductor, resulting in an increase in the total void internal surface area and a slight shift of the concentration curve towards larger voids, with the peak moving from about 40 nm to about 50 nm.

  11. In situ TEM visualization of superior nanomechanical flexibility of shear-exfoliated phosphorene.

    PubMed

    Xu, Feng; Ma, Hongyu; Lei, Shuangying; Sun, Jun; Chen, Jing; Ge, Binghui; Zhu, Yimei; Sun, Litao

    2016-07-14

    Recently discovered atomically thin black phosphorus (called phosphorene) holds great promise for applications in flexible nanoelectronic devices. Experimentally identifying and characterizing nanomechanical properties of phosphorene are challenging, but also potentially rewarding. This work combines for the first time in situ transmission electron microscopy (TEM) imaging and an in situ micro-manipulation system to directly visualize the nanomechanical behaviour of individual phosphorene nanoflakes. We demonstrate that the phosphorene nanoflakes can be easily bent, scrolled, and stretched, showing remarkable mechanical flexibility rather than fracturing. An out-of-plane plate-like bending mechanism and in-plane tensile strain of up to 34% were observed. Moreover, a facile liquid-phase shear exfoliation route has been developed to produce such mono-layer and few-layer phosphorene nanoflakes in organic solvents using only a household kitchen blender. The effects of surface tensions of the applied solvents on the ratio of average length and thickness (L/T) of the nanoflakes were studied systematically. The results reported here will pave the way for potential industrial-scale applications of flexible phosphorene nanoelectronic devices.

  12. In situ TEM visualization of superior nanomechanical flexibility of shear-exfoliated phosphorene

    SciTech Connect

    Xu, Feng; Ma, Hongyu; Lei, Shuangying; Sun, Jun; Chen, Jing; Ge, Binghui; Zhu, Yimei; Sun, Litao

    2016-06-20

    Recently discovered atomically thin black phosphorus (called phosphorene) holds great promise for applications in flexible nanoelectronic devices. Experimentally identifying and characterizing nanomechanical properties of phosphorene are challenging, but also potentially rewarding. Our work combines for the first time in situ transmission electron microscopy (TEM) imaging and an in situ micro-manipulation system to directly visualize the nanomechanical behaviour of individual phosphorene nanoflakes. Furthermore, we demonstrate that the phosphorene nanoflakes can be easily bent, scrolled, and stretched, showing remarkable mechanical flexibility rather than fracturing. An out-of-plane plate-like bending mechanism and in-plane tensile strain of up to 34% were observed. Moreover, a facile liquid-phase shear exfoliation route has been developed to produce such mono-layer and few-layer phosphorene nanoflakes in organic solvents using only a household kitchen blender. The effects of surface tensions of the applied solvents on the ratio of average length and thickness (L/T) of the nanoflakes were studied systematically. These results reported here will pave the way for potential industrial-scale applications of flexible phosphorene nanoelectronic devices.

  13. In situ TEM visualization of superior nanomechanical flexibility of shear-exfoliated phosphorene

    DOE PAGES

    Xu, Feng; Ma, Hongyu; Lei, Shuangying; ...

    2016-06-20

    Recently discovered atomically thin black phosphorus (called phosphorene) holds great promise for applications in flexible nanoelectronic devices. Experimentally identifying and characterizing nanomechanical properties of phosphorene are challenging, but also potentially rewarding. Our work combines for the first time in situ transmission electron microscopy (TEM) imaging and an in situ micro-manipulation system to directly visualize the nanomechanical behaviour of individual phosphorene nanoflakes. Furthermore, we demonstrate that the phosphorene nanoflakes can be easily bent, scrolled, and stretched, showing remarkable mechanical flexibility rather than fracturing. An out-of-plane plate-like bending mechanism and in-plane tensile strain of up to 34% were observed. Moreover, a facilemore » liquid-phase shear exfoliation route has been developed to produce such mono-layer and few-layer phosphorene nanoflakes in organic solvents using only a household kitchen blender. The effects of surface tensions of the applied solvents on the ratio of average length and thickness (L/T) of the nanoflakes were studied systematically. These results reported here will pave the way for potential industrial-scale applications of flexible phosphorene nanoelectronic devices.« less

  14. The dependence of TEM turbulence on magnetic geometry in the HSX stellarator

    NASA Astrophysics Data System (ADS)

    Smoniewski, J.; Faber, B. J.; Pueschel, M. J.; Likin, K. M.; Deng, C. B.; Talmadge, J. N.

    2016-10-01

    The Helically Symmetric eXperiment (HSX) is equipped with a set of auxiliary coils that can modify the designed Quasi-Helical Symmetry (QHS), and is well suited to probe the effect of geometry on turbulence. Configuration optimization to reduce turbulent transport could provide the next big confinement improvement in fusion devices. The first step towards optimization is to develop a predictive understanding of the relevant physics. Particularly in the case of density-gradient-driven TEM turbulence relevant to HSX scenarios, quasilinear models fail to predict transport. Here, moving beyond linear physics, nonlinear Gene simulations in the large density gradient region are compared in the QHS configuration, and in a configuration where the symmetry is broken by the addition of mirror terms to the magnetic spectrum. Investigations into zonal flow physics provide another perspective into differences between geometries. In parallel, power balance on experimental profiles in each configuration provides a scaling of electron thermal diffusivity χe with electron temperature and density gradient as a first step towards direct comparison to experimental fluctuation measurements. Supported by US DoE Award DE-FG02-93ER54222.

  15. XRD and mineralogical analysis of gypsum dunes at White Sands National Monument, New Mexico and applications to gypsum detection on Mars

    NASA Astrophysics Data System (ADS)

    Lafuente, B.; Bishop, J. L.; Fenton, L. K.; King, S. J.; Blake, D.; Sarrazin, P.; Downs, R.; Horgan, B. H.

    2013-12-01

    A field portable X-ray Diffraction (XRD) instrument was used at White Sands National Monument to perform in-situ measurements followed by laboratory analyses of the gypsum-rich dunes and to determine its modal mineralogy. The field instrument is a Terra XRD (Olympus NDT) based on the technology of the CheMin (Chemistry and Mineralogy) instrument onboard the Mars Science Laboratory (MSL) rover Curiosity which is providing the mineralogical and chemical composition of scooped soil samples and drilled rock powders collected at Gale Crater [1]. Using Terra at White Sands will contribute to 'ground truth' for gypsum-bearing environments on Mars. Together with data provided by VNIR spectra [2], this study clarifies our understanding of the origin and history of gypsum-rich sand dunes discovered near the northern polar region of Mars [3]. The results obtained from the field analyses performed by XRD and VNIR spectroscopy in four dunes at White Sands revealed the presence of quartz and dolomite. Their relative abundance has been estimated using the Reference Intensity Ratio (RIR) method. For this study, particulate samples of pure natural gypsum, quartz and dolomite were used to prepare calibration mixtures of gypsum-quartz and gypsum-dolomite with the 90-150μm size fractions. All single phases and mixtures were analyzed by XRD and RIR factors were calculated. Using this method, the relative abundance of quartz and dolomite has been estimated from the data collected in the field. Quartz appears to be present in low amounts (2-5 wt.%) while dolomite is present at percentages up to 80 wt.%. Samples from four dunes were collected and prepared for subsequent XRD analysis in the lab to estimate their composition and illustrate the changes in mineralogy with respect to location and grain size. Gypsum-dolomite mixtures: The dolomite XRD pattern is dominated by an intense diffraction peak at 2θ≈36 deg. which overlaps a peak of gypsum, This makes low concentrations of dolomite

  16. Helical superstructure of continuum graphene cone uncovered by TEM analysis of herringbone-striped pattern in graphitic whiskers

    NASA Astrophysics Data System (ADS)

    Saito, Yukie; Nishio-Hamane, Daisuke

    2016-10-01

    Cone-shaped graphitic whiskers (CGWs) are a form of pyrolytic carbon, consisting of conically stacked hexagonal carbon layers with an apex angle of 135-140°. Under transmission electron microscopy (TEM), CGWs often exhibit herringbone-striped patterns. Bright-field (BF) and dark-field (DF) TEM images indicated that the stripes are due to periodical appearance of a strong inter-planar reflection, which is consistent with helical rotation of layers with stepwise "layer overlap". High-resolution TEM revealed that the period was 14-15 layers. The relationship between apex angle and stripe periodicity of CGWs could be consistently explained in terms of a helical superstructure of tightly coiled continuous graphene cone.

  17. Novel microchip for in situ TEM imaging of living organisms and bio-reactions in aqueous conditions.

    PubMed

    Liu, Kuo-Liang; Wu, Chien-Chen; Huang, Ying-Jung; Peng, Hwei-Ling; Chang, Hwan-You; Chang, Pin; Hsu, Long; Yew, Tri-Rung

    2008-11-01

    A novel and disposable microchip (K-kit) with SiO(2) nano-membranes was developed and used as a specimen kit for in situ imaging of living organisms in an aqueous condition using transmission electron microscopy (TEM) without equipment modification. This K-kit enabled the successful TEM observation of living Escherichia coli cells and the tellurite reduction process in Klebsiella pneumoniae. The K. pneumoniae and Saccharomyces cerevisiae can stay alive in K-kit after continuous TEM imaging for up to 14 s and 42 s, respectively. Besides, different tellurite reduction profiles in cells grown in aerobic and anaerobic environments can be clearly revealed. These results demonstrate that the K-kit developed in this paper can be useful for observing living organisms and monitoring biological processes in situ.

  18. Network Analysis of Sequence-Function Relationships and Exploration of Sequence Space of TEM β-Lactamases.

    PubMed

    Zeil, Catharina; Widmann, Michael; Fademrecht, Silvia; Vogel, Constantin; Pleiss, Jürgen

    2016-05-01

    The Lactamase Engineering Database (www.LacED.uni-stuttgart.de) was developed to facilitate the classification and analysis of TEM β-lactamases. The current version contains 474 TEM variants. Two hundred fifty-nine variants form a large scale-free network of highly connected point mutants. The network was divided into three subnetworks which were enriched by single phenotypes: one network with predominantly 2be and two networks with 2br phenotypes. Fifteen positions were found to be highly variable, contributing to the majority of the observed variants. Since it is expected that a considerable fraction of the theoretical sequence space is functional, the currently sequenced 474 variants represent only the tip of the iceberg of functional TEM β-lactamase variants which form a huge natural reservoir of highly interconnected variants. Almost 50% of the variants are part of a quartet. Thus, two single mutations that result in functional enzymes can be combined into a functional protein. Most of these quartets consist of the same phenotype, or the mutations are additive with respect to the phenotype. By predicting quartets from triplets, 3,916 unknown variants were constructed. Eighty-seven variants complement multiple quartets and therefore have a high probability of being functional. The construction of a TEM β-lactamase network and subsequent analyses by clustering and quartet prediction are valuable tools to gain new insights into the viable sequence space of TEM β-lactamases and to predict their phenotype. The highly connected sequence space of TEM β-lactamases is ideally suited to network analysis and demonstrates the strengths of network analysis over tree reconstruction methods.

  19. Comparative studies of thin film growth on aluminium by AFM, TEM and GDOES characterization

    NASA Astrophysics Data System (ADS)

    Qi, Jiantao; Thompson, George E.

    2016-07-01

    In this present study, comparative studies of trivalent chromium conversion coating formation, associated with aluminium dissolution process, have been investigated using atomic force microscopy (AFM), transmission electron microscopy (TEM) and glow-discharge optical emission spectroscopy (GDOES). High-resolution electron micrographs revealed the evident and uniform coating initiation on the whole surface after conversion treatment for only 30 s, although a network of metal ridges was created by HF etching pre-treatment. In terms of conversion treatment process on electropolished aluminium, constant kinetics of coating growth, ∼0.30 ± 0.2 nm/s, were found after the prolonged conversion treatment for 600 s. The availability of electrolyte anions for coating deposition determined the growth process. Simultaneously, a proceeding process of aluminium dissolution during conversion treatment, of ∼0.11 ± 0.02 nm/s, was found for the first time, indicating constant kinetics of anodic reactions. The distinct process of aluminium consumption was assigned with loss of corrosion protection of the deposited coating material as evidenced in the electrochemical impedance spectroscopy. Based on the present data, a new mechanism of coating growth on aluminium was proposed, and it consisted of an activation period (0-30 s), a linear growth period (0.30 nm/s, up for 600 s) and limited growth period (0.17 nm/s, 600-1200 s). In addition, the air-drying post-treatment and a high-vacuum environment in the microscope revealed a coating shrinkage, especially in the coatings after conversion treatments for longer time.

  20. Ethiopian Geothermal Resources Inferred from Electromagnetic (AMT/MT, TEM) Data and Seismic Noise Interferometry

    NASA Astrophysics Data System (ADS)

    Lindsey, N. J.; Whaler, K. A.; Johnson, N.; Baptie, B.; Lemma, Y.; Desissa, M.; Ebinger, C. J.; Belachew, M.; Keir, D.; Fisseha, S.; Dawes, G.; Hautot, S.

    2012-12-01

    In Ethiopia, modern energy (hydroelectricity and foreign petroleum) is expensive and unpredictable, yet energy access is key to sustainable development. Active volcanoes and hot springs located in the slow-spreading rift zone of the Afar Depression suggest an abundant geothermal energy resource; however, before this energy can be utilized subsurface geophysical analysis is needed to study the geothermal system, its potential and identify drilling targets. The aim of this project is to use geophysical data (audio-magnetotelluric (AMT), magnetotelluric (MT), transient-electromagnetic (TEM) and passive seismic data), recently recorded in the Northern Tendaho Graben of Afar, Ethiopia, to constrain geothermal system parameters (i.e. geology, temperature, fluid properties, etc.). Recovery of these parameters enables the understanding of reservoir heat flow, geothermal energy potential, economic viability and development of an optimal drilling strategy. The AMT/MT data were recorded at 28 sites along two parallel profiles oriented perpendicular to regional geologic strike. Two-dimensional joint inversion of the TE and TM modes from all sites identifies two very strong conducting layers (~1 Ohm-m), at <500 m and 5-10 km, separated by a more resistive layer (~50 Ohm-m). This model is strongly correlated with borehole information. The deeper high conductivity anomaly shallows toward the center of the profile, at the location of highest recorded fluid temperature from early drilling operations. MT impedance tensor decomposition, phase tensor analysis and induction vector calculations, as well as forward modelling of the inversion results are mutually consistent. Two-dimensional surface wave tomography results from seismic noise interferometry add another layer of geophysical information to this interdisciplinary study, complementing the AMT/MT survey. This project was funded by the US-UK Fulbright Commission and the University of Edinburgh, and benefited from strong

  1. From olivine to ringwoodite: a TEM study of a complex process

    NASA Astrophysics Data System (ADS)

    Pittarello, Lidia; Ji, Gang; Yamaguchi, Akira; Schryvers, Dominique; Debaille, Vinciane; Claeys, Philippe

    2015-05-01

    The study of shock metamorphism of olivine might help to constrain impact events in the history of meteorites. Although shock features in olivine are well known, so far, there are processes that are not yet completely understood. In shock veins, olivine clasts with a complex structure, with a ringwoodite rim and a dense network of lamellae of unidentified nature in the core, have been reported in the literature. A highly shocked (S5-6), L6 meteorite, Asuka 09584, which was recently collected in Antarctica by a Belgian-Japanese joint expedition, contains this type of shocked olivine clasts and has been, therefore, selected for detailed investigations of these features by transmission electron microscopy (TEM). Petrographic, geochemical, and crystallographic studies showed that the rim of these shocked clasts consists of an aggregate of nanocrystals of ringwoodite, with lower Mg/Fe ratio than the unshocked olivine. The clast's core consists of an aggregate of iso-oriented grains of olivine and wadsleyite, with higher Mg/Fe ratio than the unshocked olivine. This aggregate is crosscut by veinlets of nanocrystals of olivine, with extremely low Mg/Fe ratio. The formation of the ringwoodite rim is likely due to solid-state, diffusion-controlled, transformation from olivine under high-temperature conditions. The aggregate of iso-oriented olivine and wadsleyite crystals is interpreted to have formed also by a solid-state process, likely by coherent intracrystalline nucleation. Following the compression, shock release is believed to have caused opening of cracks and fractures in olivine and formation of olivine melt, which has lately crystallized under postshock equilibrium pressure conditions as olivine.

  2. TEM-1 beta-lactamase as a scaffold for protein recognition and assay.

    PubMed

    Legendre, Daniel; Vucic, Bénédicte; Hougardy, Vincent; Girboux, Anne-Lise; Henrioul, Christophe; Van Haute, Julien; Soumillion, Patrice; Fastrez, Jacques

    2002-06-01

    A large number of different proteins or protein domains have been investigated as possible scaffolds to engineer antibody-like molecules. We have previously shown that the TEM-1 beta-lactamase can accommodate insertions of random sequences in two loops surrounding its active site without compromising its activity. From the libraries that were generated, active enzymes binding with high affinities to monoclonal antibodies raised against prostate-specific antigen, a protein unrelated to beta-lactamase, could be isolated. Antibody binding was shown to affect markedly the enzyme activity. As a consequence, these enzymes have the potential to be used as signaling molecules in direct or competitive homogeneous immunoassay. Preliminary results showed that beta-lactamase clones binding to streptavidin could also be isolated, indicating that some enzymes in the libraries have the ability to recognize proteins other than antibodies. In this paper, we show that, in addition to beta-lactamases binding to streptavidin, beta-lactamase clones binding to horse spleen ferritin and beta-galactosidase could be isolated. Affinity maturation of a clone binding to ferritin allowed obtaining beta-lactamases with affinities comprised between 10 and 20 nM (Kd) for the protein. Contrary to what was observed for beta-lactamases issued from selections on antibodies, enzyme complexation induced only a modest effect on enzyme activity, in the three cases studied. This kind of enzyme could prove useful in replacement of enzyme-conjugated antibodies in enzyme-linked immunosorbant assays (ELISA) or in other applications that use antibodies conjugated to an enzyme.

  3. SEM and TEM Characterization of As-Fabricated U-7Mo Disperson Fuel Plates

    SciTech Connect

    D. D. Keiser, Jr.; B. Yao; E. Perez; Y. H. Sohn

    2009-11-01

    The starting microstructure of a dispersion fuel plate can have a dramatic impact on the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of dispersion fuel plates, SEM and TEM analysis have been performed on RERTR-9A archive fuel plates, which went through an additional hot isostatic procsssing (HIP) step during fabrication. The fuel plates had depleted U-7Mo fuel particles dispersed in either Al-2Si or 4043 Al alloy matrix. For the characterized samples, it was observed that a large fraction of the ?-phase U-7Mo alloy particles had decomposed during fabrication, and in areas near the fuel/matrix interface where the transformation products were present significant fuel/matrix interaction had occurred. Relatively thin Si-rich interaction layers were also observed around the U-7Mo particles. In the thick interaction layers, (U)(Al,Si)3 and U6Mo4Al43 were identified, and in the thin interaction layers U(Al,Si)3, U3Si3Al2, U3Si5, and USi1.88-type phases were observed. The U3Si3Al2 phase contained some Mo. Based on the results of this work, exposure of dispersion fuel plates to relatively high temperatures during fabrication impacts the overall microstructure, particularly the nature of the interaction layers around the fuel particles. The time and temperature of fabrication should be carefully controlled in order to produce the most uniform Si-rich layers around the U-7Mo particles.

  4. Corrugated waveguide mode purifier for TEM output in a dual-mode operation overmoded coaxial millimeter-wave generator

    NASA Astrophysics Data System (ADS)

    Bai, Zhen; Zhang, Jun; Zhong, Huihuang; Zhang, Dian

    2017-01-01

    A coaxial corrugated waveguide mode purifier is designed for a dual-mode operation overmoded coaxial millimeter-wave generator. With the purifier, the mixed TEM and TM01 modes output are purified into a pure TEM mode. Particle-in-cell (PIC) simulation shows that the purifier would not decrease the total output power of the generator, and plays an independent role to the upstream structure. Effects of mode composition ratio and phase difference on the purification ability of the purifier are also researched by both electromagnetism and PIC simulations, which show that the purifier has a certain tolerance for both the mode composition ratio and phase difference.

  5. Measurement of 2-5 keV x-ray emission from laser-target interactions by using fluor-MCP and CsI-XRD detectors

    SciTech Connect

    Lee, P.H.Y.; Tirsell, K.G.; Leipelt, G.R.; Laird, W.B.

    1981-09-29

    For inertial confinement fusion plasma diagnostics, x-ray diode (XRD) detectors using conventional cathodes are not sensitive enough to measure x-rays above approx. 1.5 keV. However, for laser driver fusion targets, x-rays in the range of 2 to 5 keV are important because of their mobility in the target. We have successfully used fluor-microchannel plate (MCP) detectors to obtain absolute x-ray measurements in the 2 to 5 keV range. Recent data obtained from experiments on the Shiva laser system are presented. In addition, designs for a variety of channels in the range using fluor-MCP and CsI-XRD's above 1.5 keV will be discussed.

  6. Quantitative assessment of alkali-reactive aggregate mineral content through XRD using polished sections as a supplementary tool to RILEM AAR-1 (petrographic method)

    SciTech Connect

    Castro, Nelia; Sorensen, Bjorn E.; Broekmans, Maarten A.T.M.

    2012-11-15

    The mineral content of 5 aggregate samples from 4 different countries, including reactive and non-reactive aggregate types, was assessed quantitatively by X-ray diffraction (XRD) using polished sections. Additionally, electron probe microanalyzer (EPMA) mapping and cathodoluminescence (CL) were used to characterize the opal-CT identified in one of the aggregate samples. Critical review of results from polished sections against traditionally powdered specimen has demonstrated that for fine-grained rocks without preferred orientation the assessment of mineral content by XRD using polished sections may represent an advantage over traditional powder specimens. Comparison of data on mineral content and silica speciation with expansion data from PARTNER project confirmed that the presence of opal-CT plays an important role in the reactivity of one of the studied aggregates. Used as a complementary tool to RILEM AAR-1, the methodology suggested in this paper has the potential to improve the strength of the petrographic method.

  7. High temperature XRD of Cu{sub 2.1}Zn{sub 0.9}SnSe{sub 4}

    SciTech Connect

    Chetty, Raju Mallik, Ramesh Chandra

    2014-04-24

    Quaternary compound with chemical composition Cu{sub 2.1}Zn{sub 0.9}SnSe{sub 4} is prepared by solid state synthesis. High temperature XRD (X-Ray Diffraction) of this compound is used in studying the effect of temperature on lattice parameters and thermal expansion coefficients. Thermal expansion coefficient is one of the important quantities in evaluating the Grüneisen parameter which further useful in determining the lattice thermal conductivity of the material. The high temperature XRD of the material revealed that the lattice parameters as well as thermal expansion coefficients of the material increased with increase in temperature which confirms the presence of anharmonicty.

  8. Combining µXANES and µXRD mapping to analyse the heterogeneity in calcium carbonate granules excreted by the earthworm Lumbricus terrestris.

    PubMed

    Brinza, Loredana; Schofield, Paul F; Hodson, Mark E; Weller, Sophie; Ignatyev, Konstantin; Geraki, Kalotina; Quinn, Paul D; Mosselmans, J Frederick W

    2014-01-01

    The use of fluorescence full spectral micro-X-ray absorption near-edge structure (µXANES) mapping is becoming more widespread in the hard energy regime. This experimental method using the Ca K-edge combined with micro-X-ray diffraction (µXRD) mapping of the same sample has been enabled on beamline I18 at Diamond Light Source. This combined approach has been used to probe both long- and short-range order in calcium carbonate granules produced by the earthworm Lumbricus terrestris. In granules produced by earthworms cultured in a control artificial soil, calcite and vaterite are observed in the granules. However, granules produced by earthworms cultivated in the same artificial soil amended with 500 p.p.m. Mg also contain an aragonite. The two techniques, µXRD and µXANES, probe different sample volumes but there is good agreement in the phase maps produced.

  9. X-ray powder diffraction of high-absorption materials at the XRD1 beamline off the best conditions: Application to (Gd, Nd)5Si4 compounds

    NASA Astrophysics Data System (ADS)

    Carvalho, A. M. G.; Nunes, R. S.; Coelho, A. A.

    2017-03-01

    Representative compounds of the new family of magnetic materials Gd5-xNdxSi4 were analyzed by X-ray diffraction at the XRD1 beamline at LNLS. To reduce X-ray absorption, thin layers of the powder samples were mounted outside the capillaries and measured in Debye-Scherrer geometry as usual. The X-ray diffraction analyses and the magnetometry results indicate that the behavior of the magnetic transition temperature as a function of Nd content may be directly related to the average of the four smallest interatomic distances between different rare earth sites of the majority phase of each compound. The quality and consistency of the results show that the XRD1 beamline is able to perform satisfactory X-ray diffraction experiments on high-absorption materials even off the best conditions.

  10. Laser Raman, XRD, DSC and Ac-Impedance Analysis of Polymer Blend Electrolyte Based on Eco-Friendly Pva-Pvp Blend with NH4NO3

    NASA Astrophysics Data System (ADS)

    Rajeswari, N.; Selvasekarapandian, S.; Prabaharan, S. R. S.; Kawamura, J.; Iwai, Y.; Karthikeyan, S.

    2013-07-01

    Proton conducting polymer blend electrolytes have attractive interest because of their advantages such as processability, flexibility, electrochemical stability, easy handling and their applications to a variety of electrochemical devices such as fuel cells, chemical sensor and electrochemical displays. In the present work, the films of 50PVA-50PVP blend with different MWt% concentrations of NH4NO3 have been prepared by solution casting techniques using distilled water as a solvent. The prepared films have been investigated by different techniques such as XRD, DSC, Laser Raman and AC Impedance spectroscopy. XRD studies reveal the amorphous nature of the polymer blend-salt complexes. The glass transition temperature has been calculated from the DSC analysis. From the AC Impedance spectroscopy, the high conductivity of the 30MWt% of NH4NO3 doped 50PVA-50PVP polymer complex has been found to be the order of 1.41 × 10-3S cm-1 at room temperature.

  11. Synthesis, thermal, XRD and spectroscopic studies characterization of Tutton salt K2M (SO4)2·6H2O (M = Mg, Ni)

    NASA Astrophysics Data System (ADS)

    Marzougui, H.; Attia-Essaies, S.; Ben Hassen-Chehimi, D.

    2016-09-01

    Tutton's salts K2M(SO4)2·6H2O (M = Mg, Ni) have been synthesized by the slow evaporation method at room temperature. A complete structural characterization has been carried out by means of powder X-ray diffraction (XRD). The results indicate that the structure of these salts is monoclinic system with the space group P21/a (Z = 2). IR and Raman spectra of KMS6 (M = Mg,Ni) have been recorded and analyzed. From the spectra, the vibrations due to SO42- ion, the complex [M(H2O)6]2+ and the water molecules have been identified. Thermogravimetry, differential thermal analysis and XRD at high-temperature investigations show that the dehydration of these salts occurs between 300 and 500 K. This indicates the removal of all water molecules around 426 K.

  12. Instrumental Characterization Of Coir PITH By XRD, FTIR and SEM After Radium Adsorption From Aqueous Solution Under The Presence Of Humic Acids

    NASA Astrophysics Data System (ADS)

    Laili, Zalina; Omar, Muhamat; Yasir, Muhamad Samudi; Ibrahim, Mohd Zaidi; Yahaya, Mohd Yusri; Murshidi, Julie Andrianny

    2010-01-01

    Adsorption interactions of radium (Ra) ions onto coir pith (CP) under the presence of humic acid (HA) in the aqueous solution were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectrophotometer (FTIR) and Scanning Electron Microscopy (SEM) techniques. XRD, IR and SEM characterization of the CP has revealed differences in the native CP and Ra ions loaded CP under the presence of HA in the aqueous solution. The X-Ray patterns showed that crystalline structure of the loaded CP exhibited a decrease in crystalline structure at around 49°-51° compared with unloaded CP. Characterization by IR revealed that participation of some surface functional groups during the Ra adsorption. SEM images for the morphological studies showed that there were slightly changes of the CP surfaces after the adsorption process.

  13. Studies on the intercalation of naproxen into layered double hydroxide and its thermal decomposition by in situ FT-IR and in situ HT-XRD

    NASA Astrophysics Data System (ADS)

    Wei, Min; Shi, Shuxian; Wang, Ji; Li, Yong; Duan, Xue

    2004-07-01

    Layered double hydroxides, novel anionic clay, meet the first requirement as inorganic matrices for encapsulating functional drugs or biomolecules with negative charge in aqueous media. In this study, naproxen has been intercalated into Mg-Al layered double hydroxide by the methods of ion exchange. The structure and composition of the intercalated material have been studied by X-ray diffraction (XRD), UV-vis spectroscopy and inductively coupled plasma emission spectroscopy. A schematic model has been proposed. Furthermore, in situ Fourier transform infrared spectroscopy, in situ high-temperature XRD, and thermogravimetry (TG) have been used to characterize the thermal decomposition of the hybrid material. It has been found that the thermal stability of the intercalated naproxen is significantly enhanced compared with the pure form before intercalation, which suggests that this drug-inorganic layered material may have prospective application as the basis of a novel drug delivery system.

  14. [Study on the damage of SiO2 thin films on LiNbO3 crystal in optical parametric oscillator by XRD spectrometry].

    PubMed

    Niu, Rui-Hua; Han, Jing-Hua; Luo, Jin; Lu, Feng; Zhu, Qi-Hua; Li, Tong; Yang, Li-Ming; Feng, Guo-Ying; Zhou, Shou-Huan

    2010-12-01

    In an attempt to elucidate the damage in high transmission thin films on LiNbO3 crystal in optical parametric oscillator, the authors employed XRD spectrometry to investigate the spectrum of laser-induced damage in thin film as well as the morphology of the damage. The authors observed that the damage of thin film was characterized by the depressions/craters in the surface of the films, which were surrounded by a deposition layer with the deceasing thickness from the center of the craters. The XRD measurements indicate that the film was crystallized. The authors analyzed the causes of morphologies and the mechanism of crystallization with the aid of the model for impurity-induced damage in thin solid films. The crystallization was due to the solidification of liquid and gaseous mixtures that result from the strong absorbing to the incident laser. The crater was generated because the mixtures were ejected under the extensive pressure of the laser plasma shock wave. During the process that the mixtures deposit around the craters, the density of the mixtures will decrease and crystallization takes place. As a result, the color of the deposition layer becomes lighter from inside to outside, and the crystallization of the thin film materials was observed by XRD spectrometry.

  15. Characterizing the Phyllosilicates and Amorphous Phases Found by MSL Using Laboratory XRD and EGA Measurements of Natural and Synthetic Materials (Invited)

    NASA Astrophysics Data System (ADS)

    Rampe, E. B.; Morris, R. V.; Chipera, S.; Bish, D. L.; Bristow, T.; Archer, P. D.; Blake, D.; Achilles, C.; Ming, D. W.; Vaniman, D.; Crisp, J. A.; Des Marais, D. J.; Downs, R.; Farmer, J. D.; Morookian, J.; Morrison, S.; Sarrazin, P.; Spanovich, N.; Treiman, A. H.; Yen, A. S.; Team, M.

    2013-12-01

    The Curiosity Rover landed on the Peace Vallis alluvial fan in Gale crater on August 5, 2012. A primary mission science objective is to search for past habitable environments, and, in particular, to assess the role of past water. Identifying the minerals and mineraloids that result from aqueous alteration at Gale crater is essential for understanding past aqueous processes at the MSL landing site and hence for interpreting the site's potential habitability. X-ray diffraction (XRD) data from the CheMin instrument and evolved gas analyses (EGA) from the SAM instrument have helped the MSL science team identify phases that resulted from aqueous processes: phyllosilicates and amorphous phases were measure in two drill samples (John Klein and Cumberland) obtained from the Sheepbed Member, Yellowknife Bay Fm., which is believed to represent a fluvial-lacustrine environment. A third set of analyses was obtained from scoop samples from the Rocknest sand shadow. Chemical data from the APXS instrument have helped constrain the chemical compositions of these secondary phases and suggest that the phyllosilicate component is Mg-enriched and the amorphous component is Fe-enriched, relatively Si-poor, and S- and H-bearing. To refine the phyllosilicate and amorphous components in the samples measured by MSL, we measured XRD and EGA data for a variety of relevant natural terrestrial phyllosilicates and synthetic mineraloids in laboratory testbeds of the CheMin and SAM instruments. Specifically, Mg-saturated smectites and vermiculites were measured with XRD at low relative humidity to understand the behavior of the 001 reflections under Mars-like conditions. Our laboratory XRD measurements suggest that interlayer cation composition affects the hydration state of swelling clays at low RH and, thus, the 001 peak positions. XRD patterns of synthetic amorphous materials, including allophane, ferrihydrite, and hisingerite were used in full-pattern fitting (FULLPAT) models to help

  16. TEM characterization of Au-based alloys to join YSZ to steel for SOFC applications

    SciTech Connect

    Lin, Kun-Lin; Singh, Mrityunjay; Asthana, Rajiv

    2012-01-15

    The microstructures of two gold-based alloys with compositions (in wt.%) of 96.4Au-3Ni-0.6Ti and 97.5Au-0.75Ni-1.75V following oxidation at 850 Degree-Sign C for 200 min were characterized by analytical transmission electron microscopy with energy dispersive spectroscopy and by scanning electron microscopy. In the oxidized 96.4Au-3Ni-0.6Ti interlayer, a dense scale composed of nickel oxide (NiO) and nickel titanate (NiTiO{sub 3}) formed at the alloy surface. No evidence of titanium oxide was found because there was not enough Ti present to form titanium oxide. In the oxidized 97.5Au-0.75Ni-1.75V interlayer, loose vanadium oxide (V{sub 2}O{sub 5}) and nickel vanadate (Ni{sub 2}V{sub 2}O{sub 7}) formed and were distributed within the oxidized 97.5Au-0.75Ni-1.75V interlayer. Similarly, because of the low Ni content in the alloys, no NiO formed. The oxide products in the 96.4Au-3Ni-0.6Ti and 97.5Au-0.75Ni-1.75V interlayers after oxidation are consistent with the Pilling-Bedworth (PB) ratio considerations. - Highlights: Black-Right-Pointing-Pointer Two commercial Au-based reactive metallic interlayers were oxidized at 850 Degree-Sign C for 200 min. Black-Right-Pointing-Pointer The oxidized products at the surface were characterized by TEM/EDS and SEM. Black-Right-Pointing-Pointer NiO and NiTiO{sub 3} formed at the oxidized 96.4Au-3Ni-0.6Ti interlayer. Black-Right-Pointing-Pointer V{sub 2}O{sub 5} and Ni{sub 2}V{sub 2}O{sub 7} were found in the oxidized 97.5Au-0.75Ni-1.75V interlayer. Black-Right-Pointing-Pointer These oxide products are consistent with the Pilling-Bedworth (PB) ratio considerations.

  17. A Concept for the Development of Spatially Resolved Measurements for Soil Moisture with TEM Waveguides

    NASA Astrophysics Data System (ADS)

    Lapteva, Yulia; Schmidt, Felix; Bumberger, Jan

    2014-05-01

    's equations. It describes the one-dimensional wave propagation in a multi-layered medium, assuming the wave to be transverse electromagnetic (TEM). In the particular case of transmission lines with perpendicularly arranged layer transitions this assumption is very close to reality. Such waveguides and their frequency domain measurements in layered media are promising concerning a development ways working with soil moisture detection.

  18. High-Resolution Electron Energy-Loss Spectroscopy (HREELS) Using a Monochromated TEM/STEM

    NASA Technical Reports Server (NTRS)

    Sai, Z. R.; Bradley, J. P.; Erni, R.; Browning, N.

    2005-01-01

    A 200 keV FEI TF20 XT monochromated (scanning) transmission electron microscope funded by NASA's SRLIDAP program is undergoing installation at Lawrence Livermore National Laboratory. Instrument specifications in STEM mode are Cs =1.0 mm, Cc =1.2 mm, image resolution =0.18 nm, and in TEM mode Cs =1.3 mm, Cc =1.3 mm, information limit =0.14 nm. Key features of the instrument are a voltage-stabilized high tension (HT) supply, a monochromator, a high-resolution electron energy-loss spectrometer/energy filter, a high-resolution annular darkfield detector, and a solid-state x-ray energy-dispersive spectrometer. The high-tension tank contains additional sections for 60Hz and high frequency filtering, resulting in an operating voltage of 200 kV plus or minus 0.005V, a greater than 10-fold improvement over earlier systems. The monochromator is a single Wien filter design. The energy filter is a Gatan model 866 Tridiem-ERS high resolution GIF spec d for less than or equal to 0.15 eV energy resolution with 29 pA of current in a 2 nm diameter probe. 0.13 eV has already been achieved during early installation. The x-ray detector (EDAX/Genesis 4000) has a take-off angle of 20 degrees, an active area of 30 square millimeters, and a solid angle of 0.3 steradians. The higher solid angle is possible because the objective pole-piece allows the detector to be positioned as close as 9.47 mm from the specimen. The voltage-stabilized HT supply, monochromator and GIF enable high-resolution electron energy-loss spectroscopy (HREELS) with energy resolution comparable to synchrotron XANES, but with approximately 100X better spatial resolution. The region between 0 and 100 eV is called the low-loss or valence electron energy-loss spectroscopy (VEELS) region where features due to collective plasma oscillations and single electron transitions of valence electrons are observed. Most of the low-loss VEELS features we are detecting are being observed for the first time in IDPs. A major focus of

  19. Geophysical investigation of a freshwater lens on the island of Langeoog, Germany - Insights from combined HEM, TEM and MRS data

    NASA Astrophysics Data System (ADS)

    Costabel, Stephan; Siemon, Bernhard; Houben, Georg; Günther, Thomas

    2017-01-01

    A multi-method geophysical survey, including helicopter-borne electromagnetics (HEM), transient electromagnetics (TEM), and magnetic resonance sounding (MRS), was conducted to investigate a freshwater lens on the North Sea island of Langeoog, Germany. The HEM survey covers the entire island and gives an overview of the extent of three freshwater lenses that reach depths of up to 45 m. Ground-based TEM and MRS were conducted particularly on the managed western lens to verify the HEM results and to complement the lithological information from existing boreholes. The results of HEM and TEM are in good agreement. Salt- and freshwater-bearing sediments can, as expected, clearly be distinguished due to their individual resistivity ranges. In the resistivity data, a large transition zone between fresh- and saltwater with a thickness of up to 20 m is identified, the existence of which is verified by borehole logging and sampling. Regarding lithological characterisation of the subsurface, the MRS method provides more accurate and reliable results than HEM and TEM. Using a lithological index derived from MRS water content and relaxation time, thin aquitard structures as well as fine and coarse sand aquifers can be distinguished. Complementing the existing borehole data with the lithology information estimated from MRS, we generate a map showing the occurrence of aquitard structures, which significantly improves the hydrogeological model of the island. Moreover, we demonstrate that the estimates of groundwater conductivity in the sand aquifers from geophysical data are in agreement with the fluid conductivity measured in the boreholes.

  20. Homology modeling and virtual screening of inhibitors against TEM- and SHV-type-resistant mutants: A multilayer filtering approach.

    PubMed

    Baig, Mohammad H; Balaramnavar, Vishal M; Wadhwa, Gulshan; Khan, Asad U

    2015-01-01

    TEM and SHV are class-A-type β-lactamases commonly found in Escherichia coli and Klebsiella pneumoniae. Previous studies reported S130G and K234R mutations in SHVs to be 41- and 10-fold more resistant toward clavulanic acid than SHV-1, respectively, whereas TEM S130G and R244S also showed the same level of resistance. These selected mutants confer higher level of resistance against clavulanic acid. They also show little susceptibility against other commercially available β-lactamase inhibitors. In this study, we have used docking-based virtual screening approach in order to screen potential inhibitors against some of the major resistant mutants of SHV and TEM types β-lactamase. Two different inhibitor-resistant mutants from SHV and TEM were selected. Moreover, we have retained the active site water molecules within each enzyme. Active site water molecules were placed within modeled structure of the mutant whose structure was unavailable with protein databank. The novelty of this work lies in the use of multilayer virtual screening approach for the prediction of best and accurate results. We are reporting five inhibitors on the basis of their efficacy against all the selected resistant mutants. These inhibitors were selected on the basis of their binding efficacies and pharmacophore features.

  1. PROPOSED ASTM METHOD FOR THE DETERMINATION OF ASBESTOS IN AIR BY TEM AND INFORMATION ON INTERFERING FIBERS

    EPA Science Inventory

    The draft of the ASTM Test Method for air entitled: "Airborne Asbestos Concentration in Ambient and Indoor Atmospheres as Determined by Transmission Electron Microscopy Direct Transfer (TEM)" (ASTM Z7077Z) is an adaptation of the International Standard, ISO 10312. It is currently...

  2. Backbone resonance assignments of an artificially engineered TEM-1/PSE-4 Class A β-lactamase chimera.

    PubMed

    Morin, Sébastien; Clouthier, Christopher M; Gobeil, Sophie; Pelletier, Joelle N; Gagné, Stéphane M

    2010-10-01

    The rapid evolution of Class A β-lactamases, which procure resistance to an increasingly broad panel of β-lactam antibiotics, underscores the urgency to better understand the relation between their sequence variation and their structural and functional features. To date, more than 300 clinically-relevant β-lactamase variants have been reported, and this number continues to increase. With the aim of obtaining insights into the evolutionary potential of β-lactamases, an artificially engineered, catalytically active chimera of the Class A TEM-1 and PSE-4 β-lactamases is under study by kinetics and NMR. Here we report the (1)H, (13)C and (15)N backbone resonance assignments for the 30 kDa chimera cTEM-17m. Despite its high molecular weight, the data provide evidence that this artificially-evolved chimeric enzyme is well folded. The hydrolytic activity of cTEM-17m was determined using the chromogenic substrate CENTA, with K (M) = 160 ± 35 μM and k (cat) = 20 ± 4 s(-1), which is in the same range as the values for TEM-1 and PSE-4 β-lactamases.

  3. Folding and aggregation of TEM beta-lactamase: analogies with the formation of inclusion bodies in Escherichia coli.

    PubMed Central

    Georgiou, G.; Valax, P.; Ostermeier, M.; Horowitz, P. M.

    1994-01-01

    The enzyme TEM beta-lactamase has been used as a model for understanding the pathway leading to formation of inclusion bodies in Escherichia coli. The equilibrium denaturation of TEM beta-lactamase revealed that an intermediate that has lost enzymatic activity, native protein fluorescence, and UV absorption, but retains 60% of the native circular dichroism signal, becomes populated at intermediate (1.0-1.4 M) concentrations of guanidium chloride (GdmCl). This species exhibits a large increase in bis-1-anilino-8-naphthalene sulfonic acid fluorescence, indicating the presence of exposed hydrophobic surfaces. When TEM beta-lactamase was unfolded in different initial concentrations of GdmCl and refolded to the same final conditions by dialysis a distinct minimum in the yield of active protein was observed for initial concentrations of GdmCl in the 1.0-1.5 M range. It was shown that the lower reactivation yield was solely due to the formation of noncovalently linked aggregates. We propose that the aggregation of TEM beta-lactamase involves the association of a compact state having partially exposed hydrophobic surfaces. This hypothesis is consistent with our recent findings that TEM beta-lactamase inclusion bodies contains extensive secondary structure (Przybycien TM, Dunn JP, Valax P, Georgiou G, 1994, Protein Eng 7:131-136). Finally, we have also shown that protein aggregation was enhanced at higher temperatures and in the presence of 5 mM dithiothreitol and was inhibited by the addition of sucrose. These conditions exert a similar effect on the formation of inclusion bodies in vivo. PMID:7703842

  4. TEM and EELS characterization of a Sr2CuO3+δ superconductor post-annealed at different temperatures: enhancement of Tc by apical oxygen reordering

    NASA Astrophysics Data System (ADS)

    Yang, H.; Liu, Q. Q.; Li, F. Y.; Jin, C. Q.; Yu, R. C.

    2007-10-01

    A 75 K Sr2CuO3+δ superconductor (nominal δ = 0.4), detected to be a K2NiF4-type tetragonal single phase from x-ray powder diffraction (XRD) data, was annealed in a N2 atmosphere at different temperatures, and with raising the annealing temperature, the superconducting transition temperature (Tc) is found to increase from 75 K (as-prepared), in turn, to 89 K (post-annealed at 150 °C), 95 K (post-annealed at 250 °C), and then to disappear when further increasing the annealing temperature above 250 °C. Transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) techniques are utilized to characterize both as-prepared and post-annealed samples in order to further identify the superconducting phases. TEM investigations reveal that almost all grains in the as-prepared sample exhibit modulated structures having the K2NiF4-type tetragonal structure of Sr2CuO3+δ as their basic substructure, and two types of modulated phase, i.e., Fmmm modulated phase (a \\approx b=5\\sqrt 2 a_{p} and c = cp) and C 2/m modulated phase (a=5\\sqrt 2 a_{p} , b = cp, c=\\sqrt {26} \\sqrt 2 /2a_{p} and β = 101.3°), are found in the sample. With increasing annealing temperature, successive structure phase transitions starting from the C 2/m modulated phase are observed, i.e., C 2/m modulated phase \\to Cmmm modulated phase (a = cp, b=5\\sqrt 2 a_{p} and c=5\\sqrt 2 a_{p} ) (annealed at 150 °C) \\to Pmmm modulated phase (a \\approx b=4\\sqrt 2 a_{p} and c = cp) (annealed at 250 °C) \\to unmodulated orthorhombic structure (annealed at 350 °C), while no obvious changes are found for the Fmmm modulated phase up to 250 °C. The experimental results strongly suggest that the C 2/m modulated phase is responsible for Tc at 75 K, the Cmmm modulated phase for Tc at 89 K, and the Pmmm modulated phase for Tc at 95 K, while the Fmmm modulated phase is nonsuperconducting. The absence of superconductivity in the Fmmm modulated phase can be explained by the oxygen vacancies

  5. Quantification of Electrochemical Nanoscale Processes in Lithium Batteries By OperandoEC-(S)TEM

    SciTech Connect

    Mehdi, Beata L.; Qian, Jiangfeng; Nasybulin, Eduard; Welch, David A.; Park, Chiwoo; Faller, Roland; Mehta, Hardeep S.; Henderson, Wesley A.; Xu, Wu; Evans, James E.; Liu, Jun; Zhang, Jiguang; Mueller, Karl T.; Browning, Nigel D.

    2015-07-27

    Lithium (Li)-ion batteries are currently used for a wide variety of portable electronic devices, electric vehicles and renewable energy applications. In addition, extensive worldwide research efforts are now being devoted to more advanced “beyond Li-ion” battery chemistries - such as lithium-sulfur (Li-S) and lithium-air (Li-O2) - in which the carbon anode is replaced with Li metal. However, the practical application of Li metal anode systems has been highly problematic. The main challenges involve controlling the formation of a solid-electrolyte interphase (SEI) layer and the suppression of Li dendrite growth during the charge/discharge process (achieving “dendrite-free” cycling). The SEI layer formation continuously consumes the electrolyte components creating highly resistive layer, which leads to the rapid decrease of cycling performance and degradation of the Li anode. The growth of Li metal dendrites at the anode contributes to rapid capacity fading (the presence of “dead Li” created during the discharge leads to an increased overpotential) and, in the case of continuous growth, leads to internal short circuits and extreme safety issues. Here we demonstrate the application of an operando electrochemical scanning transmission electron microscopy (ec-(S)TEM) cell to study the SEI layer formation and the initial stages of Li dendrite growth - the goal is to develop a mechanism for mitigating the degradation processes and increasing safety. Bright field (BF) STEM images in Figure 1 A-C show Li metal deposition and dissolution processes at the interface between the Pt working electrode and the lithium hexafluorophosphate (LiPF6) in propylene carbonate (PC) electrolyte during three charge/discharge cycles. A contrast reversal caused by Li metal being lighter/less dense than surrounding electrolyte (Li appears brighter than the background in BF STEM images) allows Li to be uniquely identified from the other components in the system - the only solid

  6. PyXRD v0.6.2: a FOSS program to quantify disordered, layered minerals using multi-specimen X-ray diffraction profile fitting

    NASA Astrophysics Data System (ADS)

    Dumon, M.; Van Ranst, E.

    2015-03-01

    This paper presents a free and open-source model called PyXRD (short for Python X-ray diffraction) to improve the quantification of complex, poly-phasic mixed-layer phyllosilicate assemblages. The novelty of this model is the ab initio incorporation of the multi-specimen method, making it possible to share phases and (a selection of) their parameters across multiple specimens. By effectively reducing the number of parameters and increasing the number of observations, this approach speeds up the manual refinement process significantly when automated algorithms are used. To check the hypothesis that the multi-specimen set-up can improve automatic parameter refinement, we calculated X-ray diffraction patterns for four theoretical mineral assemblages. These patterns were then used as input for a refinement employing the multi-specimen set-up and one employing the single-pattern set-ups. For all of the assemblages, PyXRD was able to reproduce or approximate the input parameters with the multi-specimen approach. Diverging solutions only occurred in single-pattern set-ups which do not contain enough information (e.g. patterns of heated samples) to discern all the different minerals. Assuming a correct qualitative interpretation was made and a single pattern exists in which all phases are sufficiently discernible, the obtained results indicate a good quantification can often be obtained with just that pattern. For naturally occurring samples, this could mean modelling air-dry and/or ethylene-glycolated patterns might be sufficient. However, these results from theoretical experiments cannot automatically be extrapolated to all real-life experiments. In any case, PyXRD has proven to be very useful when X-ray diffraction patterns are modelled for complex mineral assemblages containing mixed-layer phyllosilicates with a multi-specimen approach.

  7. Synthetic spinels in the (Mg, Fe2+)(Cr, Fe3+)2O4 join: Mossbauer, optical absorption, single crystal XRD and electron microprobe analyses

    NASA Astrophysics Data System (ADS)

    Lenaz, D.; Skogby, H.; Princivalle, F.; Halenius, U.

    2003-04-01

    Single crystals along the Mg-chromite -- Mg-ferrite and Mg-chromite -- chromite joins were synthesized using a flux-growth method (24 hours at 1200^oC and 4^oC/h cooling rate to 900^oC in air and gas-controlled atmosphere) in order to evaluate the influence of composition on structure and cation distribution using optical absorption (OAS), Mössbauer (MS), single-crystal X-ray diffraction (XRD) and microprobe analyses (EPMA). At present, most of the analyses were carried out on the (Mg,Fe2+)Cr_2O_4 series. MgCr_2O_4 end-member: OAS shows prominent absorption bands at 23,700 and 17,300 cm-1. XRD analyses on three single crystals show a_0 equal to 8.3329 (1) Å and u (oxygen positional parameter) equal to 0.2612 (1), close to the values reported by O'Neill and Dollase (1994) as determined by powder diffraction on samples annealed at 900 to 1400^oC. The T-O and M-O calculated bond distances are equal to 1.965 and 1.995, respectively. These results are consistent with the set of optimised bond distances for Mg and Cr proposed by Lavina et al. (2002). (Mg,Fe2+)Cr_2O_4 series: Mössbauer spectra were measured at room temperature on different samples with nominal chromite components in the 10 to 70 mol % range. All the spectra show a single absorption line. For compositions close to the Mg-chromite end-member the line is narrow, however, for intermediate compositions the line broadens progressively and is best fitted with a quadrupole doublet (dq=0.22 for 50 mol % chromite). Towards the chromite end-member the peak becomes narrower again. XRD data shows that there is a linear positive correlation between a_0 and u with increasing Fe2+.

  8. Comprehensive analysis of TEM methods for LiFePO4/FePO4 phase mapping: spectroscopic techniques (EFTEM, STEM-EELS) and STEM diffraction techniques (ACOM-TEM).

    PubMed

    Mu, X; Kobler, A; Wang, D; Chakravadhanula, V S K; Schlabach, S; Szabó, D V; Norby, P; Kübel, C

    2016-11-01

    Transmission electron microscopy (TEM) has been used intensively in investigating battery materials, e.g. to obtain phase maps of partially (dis)charged (lithium) iron phosphate (LFP/FP), which is one of the most promising cathode material for next generation lithium ion (Li-ion) batteries. Due to the weak interaction between Li atoms and fast electrons, mapping of the Li distribution is not straightforward. In this work, we revisited the issue of TEM measurements of Li distribution maps for LFP/FP. Different TEM techniques, including spectroscopic techniques (energy filtered (EF)TEM in the energy range from low-loss to core-loss) and a STEM diffraction technique (automated crystal orientation mapping (ACOM)), were applied to map the lithiation of the same location in the same sample. This enabled a direct comparison of the results. The maps obtained by all methods showed excellent agreement with each other. Because of the strong difference in the imaging mechanisms, it proves the reliability of both the spectroscopic and STEM diffraction phase mapping. A comprehensive comparison of all methods is given in terms of information content, dose level, acquisition time and signal quality. The latter three are crucial for the design of in-situ experiments with beam sensitive Li-ion battery materials. Furthermore, we demonstrated the power of STEM diffraction (ACOM-STEM) providing additional crystallographic information, which can be analyzed to gain a deeper understanding of the LFP/FP interface properties such as statistical information on phase boundary orientation and misorientation between domains.

  9. Evaluating mineralogy at terrestrial analogs for early Mars: Detection and characterization of clays with XRD and investigation of iron substitution in natroalunite

    NASA Astrophysics Data System (ADS)

    Beckerman, Laura Grace

    The Mars Science Laboratory (MSL) Curiosity rover is equipped with CheMin, the first x-ray diffraction (XRD) instrument on Mars, for in situ mineralogy as part of its mission to seek evidence of past habitability at Gale Crater. Detection and characterization of hydrated minerals like clays and sulfates provides crucial insight into Mars' early geochemistry. For example, clays are often interpreted as having formed in lacustrine environments at neutral pHs, while sulfates such as jarosite are evidence of acid sulfate alteration. However, CheMin's inability to remove non-clay minerals and to preferentially orient samples may pose significant challenges to clay detection and characterization at Gale Crater. To evaluate the effect of particle size separation (<0.2 microm), removal of non-clay minerals, preferred orientation, and ethylene glycol solvation on XRD analyses of clays, we used both a CheMin analog instrument and a traditional laboratory XRD to identify clays in acid sulfate altered basalt from Mars analog sites in Costa Rica. We detected kaolinite in four of the fourteen samples studied, one of which also contained montmorillonite. Kaolinite was not detected in two samples with the analog instrument prior to clay isolation. These results suggest that CheMin may miss detection of some clays at Gale Crater, which could affect interpretations of early Mars' habitability. Mistaking iron-rich natroalunite (Na[Al,Fe]3(SO4) 2(OH)6) for jarosite (KFe3(SO4) 2(OH)6) could also impact interpretations of early Mars, as natroalunite can form over a broader range of pH, water:rock ratios, and redox conditions than can jarosite. To determine if iron-rich natroalunite is a common alteration product at Mars analog sites, we assessed iron content in natroalunite from Costa Rica. We detected up to 30% iron substitution in natroalunite at diverse geochemical settings. We also evaluated the feasibility of using XRD or Raman spectroscopy for in situ iron-rich natroalunite

  10. Use of an Ultrasonic/Sonic Driller/Corer to Obtain Sample Powder for CHEMIN, a Combined XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Chipera, S. J.; Bish, D. L.; Vaniman, D. T.; Sherrit, S.; Bar-Cohen, Y.; Sarrazin, P.; Blake, D. F.

    2003-01-01

    A miniature CHEMIN XRD/XRF (X-Ray Diffraction/X-Ray Fluourescence) instrument is currently being developed for definitive mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed in order to enable XRD analysis on an extraterrestrial body is how best to obtain a representative sample powder for analysis. For XRD powder diffraction analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a 2-dimensional detector as used in the CHEMIN instrument will produce good results with poorly prepared powders, the quality of the data will improve if the sample is fine-grained and randomly oriented. An Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL is an effective mechanism of sampling rock to produce cores and powdered cuttings. It requires low axial load (< 5N) and thus offers significant advantages for operation from lightweight platforms and in low gravity environments. The USDC is lightweight (<0.5kg), and can be driven at low power (<5W) using duty cycling. It consists of an actuator with a piezoelectric stack, ultrasonic horn, free-mass, and drill bit. The stack is driven with a 20 kHz AC voltage at resonance. The strain generated by the piezoelectric is amplified by the horn by a factor of up to 10 times the displacement amplitude. The tip impacts the free-mass and drives it into the drill bit in a hammering action. The free-mass rebounds to interact with the horn tip leading to a cyclic rebound at frequencies in the range of 60-1000 Hz. It does not require lubricants, drilling fluid or bit sharpening and it has the potential to operate at high and low temperatures using a suitable choice of piezoelectric material. To assess whether the powder from an ultrasonic drill would be adequate for analyses by an XRD/XRF spectrometer such as CHEMIN, powders obtained from the JPL

  11. XRD and xanes studies of copper complexes using (diethyl 4-amino-1-phenyl-1H-pyrazole-3,5 dicarboxylate) as ligand

    NASA Astrophysics Data System (ADS)

    Mishra, Ashutosh; Jain, Garima

    2013-06-01

    X-ray diffraction (XRD) and X-ray absorption spectroscopic (XAS) studies have been done on three copper complexes using (diethyl 4-amino-1-phenyl-1H-pyrazole-3,5 dicarboxylate) as ligand. The X-ray diffraction studies of copper complexes have been recorded using Rigaku RINT-2000 X-ray diffractometer equipped with a rotating anode with tube voltage of 40 kV and current of 100 mA. The X-ray absorption spectra of the complexes have been recorded at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore and is called beamline.

  12. {beta}{prime} and {beta} precipitation in an Al-Mg alloy studied by DSC and TEM

    SciTech Connect

    Starink; Zahra, A.M.

    1998-06-12

    Precipitation in Al-16 at. % Mg is investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The shape of the {beta}{prime} formation DSC effect is interpreted with a novel theory and the curves obtained on the basis of this new theory fit well to the experimental curves. The s parameter derived from these fits, which is akin to the Avrami parameter n appearing in the Johnson-Mehl-Avrami-Kolmogorov model, is larger than 2.5, indicating that {beta}{prime} precipitation is an autocatalytic process. TEM showed the abundant presence of defects (mostly dislocation loops) but no evidence of nucleation of {beta}{prime} precipitates on these defects. The enthalpies of formation of the {beta} and {beta}{prime} phases are derived as 15.7 and 11.5 kJ per mol Mg, respectively.

  13. In-situ TEM crystallization of anorthite-glass films on {alpha}-Al{sub 2}O{sub 3}

    SciTech Connect

    Mallamaci, M.P.; Carter, C.B.; Bentley, J.

    1993-12-31

    Anorthite-glass films have been grown by pulsed-laser deposition on single-crystal {alpha}-Al{sub 2}O{sub 3} substrates which were pre-thinned to electron transparency. The glass films were crystallized in the transmission electron microscope (TEM), which allowed direct observation and video-recording of the crystallization process. Crystallization of these films in the TEM resulted in the formation of hexagonal and orthorhombic anorthite. The orthorhombic phase was the predominant product of glass films grown at elevated substrate temperatures and displayed strong epitaxy with the underlying substrate. In contrast, the hexagonal phase was the major constituent of films grown at ambient substrate temperature and displayed no clear epitaxy with the substrate. The difference in degree of epitaxy and phase structure may be evidence of ordering at the original glass/oxide interface.

  14. In Vivo Inflammatory Effects of Ceria Nanoparticles on CD-1 Mouse: Evaluation by Hematological, Histological, and TEM Analysis

    PubMed Central

    Poma, Anna; Ragnelli, Anna Maria; de Lapuente, Joaquin; Ramos, David; Borras, Miquel; Di Gioacchino, Mario; Santucci, Sandro; De Marzi, Laura

    2014-01-01

    The attention on CeO2-NPs environmental and in vivo effects is due to their presence in diesel exhaust and in diesel filters that release a more water-soluble form of ceria NPs, as well as to their use for medical applications. In this work, acute and subacute in vivo toxicity assays demonstrate no lethal effect of these NPs. Anyhow, performing in vivo evaluations on CD-1 mouse systems, we demonstrate that it is even not correct to assert that ceria NPs are harmless for living systems as they can induce status of inflammation, revealed by hematological-chemical-clinical assays as well as histological and TEM microscope observations. TEM analysis showed the presence of NPs in alveolar macrophages. Histological evaluation demonstrated the NPs presence in lungs tissues and this can be explained by assuming their ability to go into the blood stream and lately into the organs (generating inflammation). PMID:25032226

  15. TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.

    PubMed

    Dubiel, B; Kruk, A; Stepniowska, E; Cempura, G; Geiger, D; Formanek, P; Hernandez, J; Midgley, P; Czyrska-Filemonowicz, A

    2009-11-01

    The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical.

  16. Photosensing performance of branched CdS/ZnO heterostructures as revealed by in situ TEM and photodetector tests.

    PubMed

    Zhang, Chao; Tian, Wei; Xu, Zhi; Wang, Xi; Liu, Jiangwei; Li, Song-Lin; Tang, Dai-Ming; Liu, Dequan; Liao, Meiyong; Bando, Yoshio; Golberg, Dmitri

    2014-07-21

    CdS/ZnO branched heterostructures have been successfully synthesized by combining thermal vapour deposition and a hydrothermal method. Drastic optoelectronic performance enhancement of such heterostructures was revealed, compared to plain CdS nanobelts, as documented by comparative in situ optoelectronic studies on corresponding individual nanostructures using an originally designed laser-compatible transmission electron microscopy (TEM) technique. Furthermore, flexible thin-film based photodetectors based on standard CdS nanobelts and newly prepared CdS/ZnO heterostructures were fabricated on PET substrates, and comparative photocurrent and photo-responsivity measurements thoroughly verified the in situ TEM results. The CdS/ZnO branched heterostructures were found to have better performance than standard CdS nanobelts for optoelectronic applications with respect to the photocurrent to dark current ratio and responsivity.

  17. Efficient single-mode (TEM{sub 00}) Nd : YVO{sub 4} laser with longitudinal 808-nm diode pumping

    SciTech Connect

    Donin, V I; Yakovin, D V; Yakovin, M D

    2013-10-31

    A single-mode Nd : YVO{sub 4} laser with unidirectional longitudinal pumping by laser diodes with λ = 808 nm and a power of 40 W is studied. In the TEM{sub 00} mode, the output laser power is 24 W with the optical efficiency η{sub opt} = 57.1 % (slope efficiency 63.3 %), which, as far as we know, is the best result for Nd{sup 3+} : YVO{sub 4} lasers with longitudinal pumping at λ = 808 nm from one face of the active crystal. Estimates of thermal effects show that, using a Nd : YVO{sub 4} crystal (length 20 mm, diameter 3 mm, dopant concentration 0.27 at%) with two undoped ends and bidirectional diode pumping with a total power of 170 W, one can obtain an output power of ∼100 W in the TEM{sub 00} mode from one active element. (lasers)

  18. Fibre-coupled red diode-pumped Alexandrite TEM00 laser with single and double-pass end-pumping

    NASA Astrophysics Data System (ADS)

    Arbabzadah, E. A.; Damzen, M. J.

    2016-06-01

    We report the investigation of an Alexandrite laser end-pumped by a fibre-coupled red diode laser module. Power, efficiency, spatial, spectral, and wavelength tuning performance are studied as a function of pump and laser cavity parameters. It is the first demonstration, to our knowledge, of greater than 1 W power and also highest laser slope efficiency (44.2%) in a diode-pumped Alexandrite laser with diffraction-limited TEM00 mode operation. Spatial quality was excellent with beam propagation parameter M 2 ~ 1.05. Wavelength tuning from 737-796 nm was demonstrated using an intracavity birefringent tuning filter. Using a novel double pass end-pumping scheme to get efficient absorption of both polarisation states of the scrambled fibre-delivered diode pump, a total output coupled power of 1.66 W is produced in TEM00 mode with 40% slope efficiency.

  19. Recent Advances in Electron Tomography: TEM and HAADF-STEM Tomography for Materials Science and IC Applications

    SciTech Connect

    Kubel, C; Voigt, A; Schoenmakers, R; Otten, M; Su, D; Lee, T; Carlsson, A; Engelmann, H; Bradley, J

    2005-11-09

    Electron tomograph tomography is a well y well-established technique for three-dimensional structure determination of (almost) amorphous specimens in life science applications. With the recent advances in nanotechnology and the semiconductor industry, there is also an increasing need for high-resolution 3D structural information in physical sciences. In this paper, we evaluate the capabilities and limitations of TEM and HAADF-STEM tomography for the 3D structural characterization of partially crystalline to highly crystalline materials. Our analysis of catalysts, a hydrogen storage material, and different semiconductor devices shows that features with a diameter as small as 1-2 nm can be resolved in 3D by electron tomography. For partially crystalline materials with small single crystalline domains, TEM tomography provides reliable 3D structural information. HAADF-STEM tomography is more versatile and can also be used for high-resolution 3D imaging of highly crystalline materials such as semiconductor devices.

  20. TEM study on the effects of intermediate quenching on some defects in high Jc Bi-2223 tapes

    NASA Astrophysics Data System (ADS)

    Yao, P.; Zeng, R.; Liu, H. K.; Dou, S. X.

    2000-07-01

    The microstructure of the 69-filamentary Bi-2223 tapes with high Jc of 51 000 A/cm 2 at 77 K and self-field has been studied by using the transmission electron microscopy (TEM) method. The tapes were treated by two steps sintering with intermediate quenching (IQ) and pressing [S.X. Dou, R. Zeng, T.P. Beals, H.K. Liu, Physica C 303 (1998) 21]. The diversified defects in the grains or colonies that influence the properties of the tapes were thoroughly observed by TEM. IQ is an effective method to promote the healing of the cracks, prevent the forming of the large secondary phases, and affects the critical current density of the tapes.

  1. TEM studies of Ge nanocrystal formation in PECVD grown SiO2:Ge/SiO2 multilayers

    NASA Astrophysics Data System (ADS)

    Agan, S.; Dana, A.; Aydinli, A.

    2006-06-01

    We investigate the effect of annealing on the Ge nanocrystal formation in multilayered germanosilicate-oxide films grown on Si substrates by plasma enhanced chemical vapour deposition (PECVD). The multilayered samples were annealed at temperatures ranging from 750 to 900 °C for 5 min under nitrogen atmosphere. The onset of formation of Ge nanocrystals, at 750 °C, can be observed via high resolution TEM micrographs. The diameters of Ge nanocrystals were observed to be between 5 and 14 nm. As the annealing temperature is raised to 850 °C, a second layer of Ge nanocrystals forms next to the original precipitation band, positioning itself closer to the substrate SiO2 interface. High resolution cross section TEM images, electron diffraction and electron energy-loss spectroscopy as well as energy-dispersive x-ray analysis (EDAX) data all indicate that Ge nanocrystals are present in each layer.

  2. Structural characterizaiton and gas reactions of small metal particles by high-resolution, in-situ TEM and TED

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The existing in-situ transmission electron microscopy (TEM) facility was improved by adding a separately pumped mini-specimen chamber. The chamber contains wire-evaporation sources for three metals and a specimen heater for moderate substrate temperatures. A sample introduction device was constructed, installed, and tested, facilitating rapid introduction of a specimen into the mini-chamber while maintaining the background pressure in that chamber in the 10(-9) millibar range. Small particles and clusters of Pd, grown by deposition from the vapor phase in an in-situ TEM facility on amorphous and crystalline support films of alumina and on ultra-thin carbon films, were analyzed by conventional high-resolution TEM and image analysis in terms of detectability, number density, and size distribution. The smallest particles that could be detected and counted contained no more than 6 atoms; size determinations could be made for particles 1 nm in diameter. The influence of various oxygen plasma treatments, annealing treatments, and of increasing the substrate temperature during deposition was investigated. The TEM technique was employed to demonstrate that under otherwise identica l conditions the lattice parameter of Pd particles in the 1 to 2 nm size range and supported in random orientation on ex-situ prepared mica films is expanded by some 3% when compared to 5 nm size particles. It is believed that this expansion is neither a small-particle diffraction effect nor due to pseudomorphism, but that it is due to a annealing-induced transformation of the small as-deposited particles with predominantly composite crystal structures into larger particles with true f.c.c. structure and thus inherently smaller lattice parameter.

  3. TEM Characterization of a Titanium Nitride (TiN) Inclusion in a Fe-Ni-Co Maraging Steel

    NASA Astrophysics Data System (ADS)

    Descotes, Vincent; Migot, Sylvie; Robaut, Florence; Bellot, Jean-Pierre; Perrin-Guérin, Valérie; Witzke, Sylvain; Jardy, Alain

    2015-07-01

    A TEM observation of a TiN inclusion associated to a spinel (MgAl2O4) and calcium sulfide germs is reported. It shows an orientation relationship between these three phases, indicating an epitaxial growth of the TiN over the spinel and CaS. This observation strengthens the hypothesis of a heterogeneous nucleation of TiN particles during the solidification of a maraging steel.

  4. Photosensing performance of branched CdS/ZnO heterostructures as revealed by in situ TEM and photodetector tests

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Tian, Wei; Xu, Zhi; Wang, Xi; Liu, Jiangwei; Li, Song-Lin; Tang, Dai-Ming; Liu, Dequan; Liao, Meiyong; Bando, Yoshio; Golberg, Dmitri

    2014-06-01

    CdS/ZnO branched heterostructures have been successfully synthesized by combining thermal vapour deposition and a hydrothermal method. Drastic optoelectronic performance enhancement of such heterostructures was revealed, compared to plain CdS nanobelts, as documented by comparative in situ optoelectronic studies on corresponding individual nanostructures using an originally designed laser-compatible transmission electron microscopy (TEM) technique. Furthermore, flexible thin-film based photodetectors based on standard CdS nanobelts and newly prepared CdS/ZnO heterostructures were fabricated on PET substrates, and comparative photocurrent and photo-responsivity measurements thoroughly verified the in situ TEM results. The CdS/ZnO branched heterostructures were found to have better performance than standard CdS nanobelts for optoelectronic applications with respect to the photocurrent to dark current ratio and responsivity.CdS/ZnO branched heterostructures have been successfully synthesized by combining thermal vapour deposition and a hydrothermal method. Drastic optoelectronic performance enhancement of such heterostructures was revealed, compared to plain CdS nanobelts, as documented by comparative in situ optoelectronic studies on corresponding individual nanostructures using an originally designed laser-compatible transmission electron microscopy (TEM) technique. Furthermore, flexible thin-film based photodetectors based on standard CdS nanobelts and newly prepared CdS/ZnO heterostructures were fabricated on PET substrates, and comparative photocurrent and photo-responsivity measurements thoroughly verified the in situ TEM results. The CdS/ZnO branched heterostructures were found to have better performance than standard CdS nanobelts for optoelectronic applications with respect to the photocurrent to dark current ratio and responsivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00963k

  5. Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

    NASA Astrophysics Data System (ADS)

    Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

    2014-12-01

    High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

  6. Mechanism of Rhabdophane-(La) And Lanthanite-(La) Formation during Reduction of Bioavailabe Nutrients in Water based on SEM and XRD Study

    NASA Astrophysics Data System (ADS)

    Szopa, Krzysztof; Banasik, Kamila; Krzykawski, Tomasz

    2012-01-01

    This study presents results of SEM and XRD investigation of products formed after La-rich bentonite application into water containing PO43- and CO32- ions. The main product of the investigated reaction with phosphate and carbonate anions is rabdophane-(La) and lanthanite-(La), respectively. Studied material has adaptation in many water reservoirs only for phosphorus ions reduction. Further studies might find application in case of reduction others hazardous ions. They could be precipitated in the same fast and effective way, to other stable, nontoxic mineral phases. Niniejszy artykuł traktuje o możliwości redukcji nutrientów (np. PO43-, CO32-) za pomocą bentonitu wzbogaconego w lantan. Jak dotąd jedynym zastosowaniem wspomnianego bentonitu jest redukcja jonów fosfonowych w środowiskach wodnych (np. jeziora, rzeki, zastoiska) do stabilnego i nietoksycznego związku mineralnego jakim jest rabdofan-(La). Na podstawie analiz SEM oraz XRD wykazano, że badany materiał umożliwia również redukcję jonów węglanowych do stabilnej i nietoksycznej fazy mineralnej-węglanowej (lantanit-(La)). Dalsze studia nad bentonitem lantanowym, poczynione względem innych, niepożądanych jonów (np. jonów azotanowych czy arsenianowych) mogą przynieść odpowiedzi względem ewentualnego i dalszego, środowiskowego zastosowania bentonitu lantanowego.

  7. Magnetic composites from minerals: study of the iron phases in clay and diatomite using Mössbauer spectroscopy, magnetic measurements and XRD

    NASA Astrophysics Data System (ADS)

    Cabrera, M.; Maciel, J. C.; Quispe-Marcatoma, J.; Pandey, B.; Neri, D. F. M.; Soria, F.; Baggio-Saitovitch, E.; de Carvalho, L. B.

    2014-01-01

    Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic derivative can be easily removed from the reaction mixture by a magnetic field. This work presents a study about the synthesis and characterization of iron phases into magnetic montmorillonite clay (mMMT) and magnetic diatomaceous earth (mDE) by 57Fe Mössbauer spectroscopy (MS), magnetic measurements and X-ray diffraction (XRD). Also these magnetic materials were assessed as matrices for the immobilization of invertase via covalent binding. Mössbauer spectra of the magnetic composites performed at 4.2 K showed a mixture of magnetite and maghemite about equal proportion in the mMMT, and a pure magnetite phase in the sample mDE. These results were verified using XRD. The residual specific activity of the immobilized invertase on mMMT and mDE were 83 % and 92.5 %, respectively. Thus, both magnetic composites showed to be promising matrices for covalent immobilization of invertase.

  8. Mineralogical In-situ Investigation of Acid-Sulfate Samples from the Rio Tinto River, Spain, with a Portable XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Sarrazin, P.; Ming, D. W.; Morris, R. V.; Fernandez-Remolar, D.; Amils, R.; Arvidson, R. E.; Blake, D.; Bish, D. L.

    2007-01-01

    A field campaign was organized in September 2006 by Centro de Astobiologica (Spain) and Washington University (St Louis, USA) for the geological study of the Rio Tinto river bed sediments using a suite of in-situ instruments comprising an ASD reflectance spectrometer, an emission spectrometer, panoramic and close-up color imaging cameras, a life detection system and NASA's CheMin 4 XRD/XRF prototype. The primary objectives of the field campaign were to study the geology of the site and test the potential of the instrument suite in an astrobiological investigation context for future Mars surface robotic missions. The results of the overall campaign will be presented elsewhere. This paper focuses on the results of the XRD/XRF instrument deployment. The specific objectives of the CheMin 4 prototype in Rio Tinto were to 1) characterize the mineralogy of efflorescent salts in their native environments; 2) analyze the mineralogy of salts and oxides from the modern environment to terraces formed earlier as part of the Rio Tinto evaporative system; and 3) map the transition from hematite-dominated terraces to the mixed goethite/salt-bearing terraces where biosignatures are best preserved.

  9. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    PubMed

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±δ ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±δ phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD.

  10. Structural and morphological characterization of Poly(o-ethoxyaniline) Emeraldine-salt form using FTIR, XRD, LeBail Method and SEM

    NASA Astrophysics Data System (ADS)

    Silva, Adriano de S.; Soares, Juliana C.; Mafud, Ana Carolina; de Souza, Sérgio M.; Fernandes, Edson G. R.; Mascarenhas, Yvonne P.; Sanches, Edgar A.

    2014-08-01

    The introduction of polar functional and alkyl groups into the main chain of Polyaniline (PANI) is a mechanism to obtain soluble polymers in a wider variety of organic solvents. Poly(o-ethoxyaniline) (POEA) is a derivative of PANI and its structural difference is the presence of the group (-OC2H5) in the ortho position of the carbon rings. Despite the large number of studies performed with PANI and its derivatives, there are few that focus on a structural study of these materials in doped form (ES). Poly(o-ethoxyaniline) Emeraldine-salt form (POEA-ES) was synthesized in polymerization times of 3, 24 and 48 h. Through XRD measurements were observed that different polymerization times did not cause structural changes in polymer structures. It were found in XRD patterns peaks at 2θ = 8°, 12°, 16°, 24°, 26°, 38°, 44° and 52°. Crystallinity percentage was calculated using the Peak Fitting Module Program and showed that POEA-ES has around 39% of crystallinity. FTIR analysis allowed to identify characteristic absorption bands in the structure of POEA-ES. By Scanning Electron Microscopy (SEM) it was observed micrometric particles of varying sizes, with morphologies similar to interconnected vesicular microspheres. Through LeBail Method, it was observed that crystallites of POEA-ES are present in the order of 26 Å. It was found a conductivity value of 0.3 × 10-7 S/cm for POEA-ES.

  11. Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO{sub 4}:Dy TL material

    SciTech Connect

    Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Dollah, Mohd Taufik; Hamid, Muhammad Azmi Abdul

    2014-09-03

    This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO{sub 4}) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO{sub 4} with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO{sub 4}:Dy was studied using a TLD reader after exposure to gamma ray by Co{sup 60} source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.

  12. Structure analysis and spectroscopic characterization of 2-Fluoro-3-Methylpyridine-5-Boronic Acid with experimental (FT-IR, Raman, NMR and XRD) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Alver, Özgür; Dikmen, Gökhan

    2016-03-01

    Possible stable conformers, geometrical molecular structures, vibrational properties as well as band assignments, nuclear magnetic shielding tensors of 2-Fluoro-3-Methylpyridine-5-Boronic Acid (2F3MP5BA) were studied experimentally and theoretically using FT-IR, Raman, (CP/MAS) NMR and XRD spectroscopic methods. FT-IR and Raman spectra were evaluated in the region of 3500-400 cm-1, and 3200-400 cm-1, respectively. The optimized geometric structures, vibrational wavenumbers and nuclear magnetic shielding tensors were examined using Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. 1H, 13C NMR chemical shifts were calculated using the gauge invariant atomic orbital (GIAO) method. 1H, 13C, APT and HETCOR NMR experiments of title molecule were carried out in DMSO solution. 13C CP/MAS NMR measurement was done with 4 mm zirconium rotor and glycine was used as an external standard. Single crystal of 2F3MP5BA was also prepared for XRD measurements. Assignments of vibrational wavenumbers were also strengthened by calculating the total energy distribution (TED) values using scaled quantum mechanical (SQM) method.

  13. An experimental study of the (Ti-6Al-4V)-xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques.

    SciTech Connect

    Sun, Pei; Fang, Z. Zak; Koopman, Mark; Paramore, James D.; Chandran, K. S. Ravi; Ren, Yang; Lu, Jun

    2015-02-01

    Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in the (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.

  14. Characterization of Inhibitor-Resistant TEM β-Lactamases and Mechanisms of Fluoroquinolone Resistance in Escherichia coli Isolates.

    PubMed

    Ríos, Esther; López, Maria Carmen; Rodríguez-Avial, Iciar; Pena, Irene; Picazo, Juan Jose

    2015-10-01

    The aim of present work was to characterize the inhibitor-resistant TEM (IRT) β-lactamases produced by Escherichia coli in Hospital Clínico San Carlos (Madrid, Spain). Mechanisms of fluoroquinolone resistance among IRT-producing strains were also studied. Isolates with susceptibility to cephalosporins and amoxicillin-clavulanate (AMC) resistance were collected in our hospital (November 2011-July 2012) from both outpatients and hospitalized patients. Among 70 AMC-resistant E. coli strains, 28 (40%) produced IRT enzymes. Most of them were uropathogens (82.1%) and recovered from outpatients (75%). Seven different IRT enzymes were identified with TEM-30 (IRT-2) being the most prevalent, followed by TEM-40 (IRT-11). A high rate of ciprofloxacin resistance was found among IRT-producing strains (50%). Most of the ciprofloxacin-resistant isolates showed ciprofloxacin minimum inhibitory concentration >32 mg/L and contained two mutations in both gyrA and parC genes. Four IRT enzyme producers harbored the qnr gene. ST131 clone was mainly responsible for both IRT enzyme production and ciprofloxacin resistance. In conclusion, data from this study show that the frequency of IRT producers was 40% and a high rate of ciprofloxacin resistance was found among IRT-producing isolates. Current and future actions should be taken into account to avoid or reduce the development of AMC and fluoroquinolone resistance in E. coli.

  15. Direct correlation of structural and electrical properties of electron-doped individual VO2 nanowires on devised TEM grids

    NASA Astrophysics Data System (ADS)

    Jo, Y.-R.; Kim, M.-W.; Kim, B.-J.

    2016-10-01

    Nano-scale VO2 wires with controlled parameters such as electron-doping have attracted intense interest due to their capability of suppressing the temperature of the metal-insulator transition (MIT). However, because their diameters are smaller than the spatial resolutions of the conventional measuring equipment, the ability to perform a thorough examination of the wires has been hindered. Here, we report the fabrication of a transmission electron microscopy (TEM) grid with an optimum design of Si3N4 windows on which the photolithography for individual electron-doped VO2 nanowire devices can be safely accomplished, allowing the cross-examination of the structural and electrical properties. TEM dark-field imaging was used to quantitatively investigate the fractions of rutile and M1 phases, and their lattice alignments were observed using high-resolution TEM (HRTEM) with small area diffraction. Moreover, electron energy loss spectroscopy (EELS) revealed that the rutile domain would be created by the strain induced by oxygen vacancies. Importantly, we successfully tuned the transition temperature by changing the rutile fraction while maintaining a high level of resistivity change. The resistivity at room temperature linearly decreased with the rutile fraction, following a simple model. Furthermore, the T dependence of the threshold voltage can be attributed to the Joule heating, exhibiting an identical thermal dependence, irrespective of the rutile fraction.

  16. In situ targeting TEM8 via immune response and polypeptide recognition by wavelength-modulated surface plasmon resonance biosensor

    PubMed Central

    Wang, Yimin; Luo, Zewei; Liu, Kunping; Wang, Jie; Duan, Yixiang

    2016-01-01

    There is an increasing interest in real-time and in situ monitoring of living cell activities in life science and medicine. This paper reports a whole cell sensing protocol over the interface of Au film coupled in a wavelength-modulated surface plasmon resonance (WMSPR) biosensor. With dual parabolic mirrors integrated in the sensor, the compact and miniaturized instrument shows satisfactory refractive index sensitivity (2220 nm/RIU) and a high resolution of resonance wavelength shift of 0.3 nm to liquid samples. The affinity interactions between the biomarker of human tumor endothelial marker 8 (TEM8) and antibody (Ab) or specific polypeptide (PEP) were firstly introduced to WMSPR biosensor analysis. Both the interaction events of Ab-cell and PEP-cell over the Au film interface can be recognized by the sensor and the balance time of interactions is about 20 min. The concentration range of Ab for quantitative monitoring of the TEM8 expression on human colon carcinoma SW620 cells was investigated. The present low-cost and time-saving method provides a time resolution of binding specificity between Ab/PEP and TEM8 for real-time analysis of antigen on living tumor cell surface. PMID:26822761

  17. Investigation of a catalyst ink dispersion using both ultra-small-angle X-ray scattering and cryogenic TEM.

    PubMed

    Xu, Fan; Zhang, HangYu; Ilavsky, Jan; Stanciu, Lia; Ho, Derek; Justice, Matthew J; Petrache, Horia I; Xie, Jian

    2010-12-21

    The dispersion of Nafion ionomer particles and Pt/C catalyst aggregates in liquid media was studied using both ultra-small-angle X-ray scattering (USAXS) and cryogenic TEM. A systematic approach was taken to study first the dispersion of each component (i.e., ionomer particles and Pt/C aggregates), then the combination of the components, and last the catalyst ink. Multiple-level curve fitting was used to extract the particle size, size distribution, and geometry of the Pt/C aggregates and the Nafion particles in liquid media from the scattering data. The results suggest that the particle size, size distribution, and geometry are not uniform throughout the systems but rather vary significantly. It was found that the interaction of each component (i.e., the Nafion ionomer particles and the Pt/C aggregates) occurs in the dispersion. Cryogenic TEM was used to observe the size and geometry of the particles in liquid directly and to validate the scattering results. The TEM results showed excellent agreement.

  18. Transrotational Micro-, Nanocrystals Revealed by TEM: New Solid State Order or Novel Extended Imperfection in Crystallizing Amorphous Films

    NASA Astrophysics Data System (ADS)

    Kolosov, Vladimir Yu.

    2012-02-01

    Unexpected transrotational structure [1] has been revealed by transmission electron microscopy (TEM) for crystal growth in thin (10-100nm) amorphous films of different chemical nature (oxides, chalcogenides, metals and alloys) prepared by various methods. Primarily we use our TEM bend contour technique but also HREM, EDX, CBED and AFM are used in due cases. The unusual phenomenon can be traced in situ in TEM column: strong dislocation independent regular internal bending of crystal lattice planes in a growing crystal. Such transrotation (unit cell translation is complicated by small rotation realized round an axis lying in the film plane) can result in strong regular lattice orientation gradients (up to 300^o/μm) of different geometries: cylindrical, ellipsoidal, toroidal, etc. Transrotational crystal corresponds to ideal single crystal enclosed in a curved space. It can be considered also as hypothetical endless 2.5 D analogy of MW nanotube/nano-onion halves. Transrotation is strongly increasing as the film gets thinner. Transrotations supplement dislocations (in crystals) and disclinations (in liquid crystals). Transrotational order can be regarded as intermediate one between amorphous and crystalline. [1] V. Yu. Kolosov and A. R.Tholen, Acta Mater., 48 (2000) 1829.

  19. The function and benefits of a multifunctional heating holder developed for use with conventional high resolution analytical TEMs

    NASA Astrophysics Data System (ADS)

    Kamino, T.

    2008-08-01

    Specimen heating holder consisting of a gas injector and two sets of heating element has been developed for use with conventional high resolution analytical TEMs. One of the heating elements is used for specimen heating and the other for metal deposition. Both heating elements are made of fine wire of tungsten. The specimen holder allows high resolution in-situ TEM observation of a process of gas-solid reaction followed by a metal deposition on the reactant product. The microscope used in the study was a standard TEM equipped with EDX detector and TV camera system. Thanks to the high speed pumping system and well designed column, the pressure of the electron gun area was kept at 5x10-5Pa or lower for more than 5 hours while the specimen chamber was gas injected to the pressure of 10-1Pa. Oxidation of Al to synthesize A12O3 carrier, deposition of AuPd catalyst on the Al2O3 carrier and behaviour of the deposited AuPd nano-particles at high temperatures in the air injected environment were successfully observed at atomic resolution.

  20. Inactivation of TEM-1 by avibactam (NXL-104): insights from quantum mechanics/molecular mechanics metadynamics simulations.

    PubMed

    Sgrignani, Jacopo; Grazioso, Giovanni; De Amici, Marco; Colombo, Giorgio

    2014-08-12

    The fast and constant development of drug-resistant bacteria represents a serious medical emergence. To overcome this problem, the development of drugs with new structures and modes of action is urgently needed. In this context, avibactam represents a promising, innovative inhibitor of beta-lactamases with a novel molecular structure compared to previously developed inhibitors, showing a promising inhibitory activity toward a significant number of beta-lactamase enzymes. In this work, we studied, at the atomistic level, the mechanisms of formation of the covalent complex between avibactam and TEM-1, an experimentally well-characterized class A beta-lactamase, using classical and quantum mechanics/molecular mechanics (QM/MM) simulations combined with metadynamics. Our simulations provide a detailed structural and energetic picture of the molecular steps leading to the formation of the avibactam/TEM-1 covalent adduct. In particular, they support a mechanism in which the rate-determining step is the water-assisted Glu166 deprotonation by Ser70. In this mechanistic framework, the predicted activation energy is in good agreement with experimental kinetic measurements. Additionally, our simulations highlight the important role of Lys73 in assisting the Ser70 and Ser130 deprotonations. While based on the specific case of the avibactam/TEM-1, the simple protocol we present here can be immediately extended and applied to the study of covalent complex formation in different enzyme-inhibitor pairs.