Bridging the Gap: MXRF Technique Rapidly Maps Centerline Segregation

Joydeep Sengupta, Jackie Leung, Kenny Witherspoon

http://digital.library.aist.org/pages/PR-370-272.htm

Abstract: Advanced High Strength Steel (AHSS) and Ultra High Strength Steel (UHSS) slabs produced form ArcelorMittal casters worldwide have high alloy contents-manganese up to 5%, silcon up to 2% and aluminum up to 2% – for achieving desired mechanical properties for automotive customers. These specialty steel grade groups include Dual Phase (DP) and TRIP steel grades. High Strenght Low Alloy (HSLA) steel grades slated for the line pipe industry also have high manganese content (upt to 1%) and relatively higher sulphur (>50ppm) and phosophorus (>100ppm) contents comparted to other steel grades

Keywords: Continuous Casting, Centerline Segregtaion, Advanced High Strength Steels, X-Ray Fluorescence

Comparing the Detection of Iron-Based Pottery Pigment on a Carbon-Coated Sherd by SEM-EDS and by Micro-XRF-SEM

Michael W. PendletonDorothy K. WashburnE. Ann Ellis, and Bonnie B. Pendleton

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941461

Abstract: The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis.

Keywords: scanning electron microscopy, pottery pigment, archeology

Macroscopic X-Ray Fluorescence Capability for Large-Scale Elemental Mapping

https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-11-02172

Heather M. Volz, George J. Havrilla, Robert M. Aikin, Jr., Velma M. Montoya

Abstract: Compositional information at moderate resolution over many centimeters will be powerful in materials research, not only to validate casting models but also to understand large-scale phenomena during solidification. These elemental differences across a part have a huge impact on materials properties so that identifying variations will help industry immensely with process optimization and quality control. Therefore, a nondestructive method of obtaining spatially resolved elemental compositions over large areas would be very useful. To this end, we have developed an enhanced macro-x-ray fluorescence (XRF) capability in conjunction with IXRF Systems, Inc. (Houston, Texas) to accommodate samples larger than those that typically fit into an XRF instrument chamber. Our system can accommodate samples up to 70 cm x 70 cm x 25 cm, which is unique in that most systems are trending toward smaller micro- and nano-XRF. This system uses a rhodium tube having a maximum power of 35 kV and 100 JlA; the detector is a liquid-nitrogen cooled, lithium-drifted silicon detector, and the smallest spot size is approximately 400 micrometers. Reference standard specimens will enable quantitative elemental mapping and analysis. Challenges to modifying the equipment are described. Nonuniformities in the INCONEL 718 system will be shown and discussed. As another example, segregation of niobium and molybdenum in depleted uranium (DU) castings has been known to occur based on wet chemical analysis [inductively coupled-plasma mass spectrometry (ICPMS)], but this destructive and time-consuming measurement is not practical for routine inspection of ingots. The U-Nb system is complicated because of overlap of the Nb K-alpha line with the U L-beta. Preliminary quantitative results are included on the distribution ofNb across slices from DU castings with different cooling rates. We foresee this macro-XRF elemental mapping capability becoming a valuable asset to the materials industry. 

Study of the possibility of using IXRF technique to detect the elements present in dust using Monte Carlo N Particles 

  1. R. Dehghan , A. Negarestani , M. R. Rezaie

http://bcc.bas.bg/BCC_Volumes/Volume_49_Number_4_2017/BCC-49-4-2017-4456-Dehghan-874-878%20.pdf

Abstract: Detecting heavy metals present in soil and dust as a major factor of environmental pollution has got a particular importance. An experimental (laboratory) method based on energy-dispersive X-ray fluorescence (EDXRF) technique was utilized so far to detect the elements. In this research, the Monte Carlo method based on the EDXRF technique was used to detect the elements. MCNPX2.7 code is based on Monte Carlo calculations and is able to trace 32 particles including photons within the range of X-rays and γ-rays. In this paper, the outcomes of multi-source EDXRF simulation technique were compared with the experimental results. The comparison shows that multi-source EDXRF technique(IXRF) is able to detect the percentage of elements present in soil and dust with a high compatibility. 

Keywords: IXRF; Elements; Dust; EDXRF; Multi Source; MCNPX; Detection

Micro X-Ray Fluorescence in Food Forensics & Food Safety

Var L. St. Jeor, Carrie A. Lendon

http://www.icdd.com/resources/axa/VOL57/V57_19.pdf

Abstract: For this study, Energy Dispersive Micro X-ray Fluorescence (µXRF) is applied in a practical sense to real problems existing within the food industry.  It is also compared to electron-based Energy Dispersive Spectroscopy (EDS). Both systems are generally considered non-destructive methods for determining elemental composition; however µXRF demonstrates specific advantages for elements heavier than phosphorus, or above ~2KeV in the energy spectrum.  Elements such as iron, nickel and copper, can be detected in smaller concentrations by µXRF than EDS. Although the X-ray probe is fixed, two-dimensional elemental dot maps can be collected by robotically scanning the SEM stage using available software. Since µXRF employs small probe sizes (focal points are usually 10-50µm), and X-ray probes are not usually optically visible, a simple method for aligning and “aiming” of that probe is presented so that very small, specific regions, or very small particles can be analyzed. When combined with SEM, µXRF becomes a very powerful tool.

Detecting iron-based pigments on ruthenium-coated ancestral Pueblo pottery using variable pressure scanning electron microscopy

M.W.Pendleton, D.K.Washburn, E.A.Ellis and B.B.Pendleton

https://core.ac.uk/reader/81545449

Abstract: Ancestral Puebloan black-on-white ceramics of the American Southwest can be classified as containing pigments within their painted designs containing high levels of organic-based elements such as potassium, or mineral-based elements such as iron, or a mixture of these elements. The identification of pigment elements of the pottery of a site is fundamental in determining the site’s cultural and temporal context. This paper will concentrate only on the analysis of mineral based pigment which was shown by previous researchers to exhibit greater concentrations of iron than organic based pigment. Although the visual discrimination of these pigments can be difficult if the pigment is a mixture of both pigment types or if the pigment is worn, this paper will describe a sherd sample previously shown to contain only mineral pigment. For the present study, a Tescan variable pressure scanning electron microscope, a JEOL 6400 scanning electron microscope, and a Hitachi S-3400N scanning electron microscope were used with the same sherd. This sherd was coated with ruthenium to reduce charging without the visual color change associated with sputtered metal coatings. A reduction in microscope chamber vacuum also greatly reduced charging of unpainted areas. An energy dispersive spectrometry detector produced a map of the iron present in the sherd. Areas of iron in the sherd were identified using a backscatter electron detector. Iron as well as other elements present in the paint pigment was also detected using micro-X-ray fluorescence on the same sherd.

Keywords: Iron, Pigment, Archeological pottery, Scanning electron microscopy

A Test of Diagenetic Ordering in Siliceous Lithofacies, Montery Formation, Southwestern Casmalia Hills: Santa Maria Basin, Ca

Idu Opral C. Ijeoma and Richard J. Behl

http://www.searchanddiscovery.com/abstracts/html/2014/90191pacsec/abstracts/1.7.html

Abstract: A detailed analysis of a well-exposed section through the Sisquoc and Monterey formations test the results of previous silica diagenesis studies by Isaacs (1981), Pisciotto (1981), and Murata and Nakata (1974). From these studies a key understanding was that for each compositional range, there would be a regular progression of opal-A opal-CT progressive ordering of opal-CT d101 spacing quarts. This progression should apply to any stratigraphic succession for strata of a particular compositional range, and opal-CT d101 could be used as a geothermometer and indicator of maximum burial depth. Surprisingly, these classic studies analyzed only limited numbers of samples in single successions, so we decided to test if the same trends are evident in a very dense data set in one stratigraphic sequence, 230 outcrop and road-cut samples were collected from a 700-meter thick sections and analyzed for composition, silica phase, and d101-spacing using combined EDS/XRF and XRD. 

Hematite spherules in basaltic tephra altered under aqueous, acid-sulfate conditions on Mauna Kea volcano, Hawaii: Possible clues for the occurrence of hematite-rich spherules in the Burns formation at Meridiani Planum, Mars

R.V. Morris ,*, D.W. Ming , T.G. Graff , R.E. Arvidson  , J.F. Bell III , S.W. Squyres , S.A. Mertzman , J.E. Gruener  , D.C. Golden f , L. Le , G.A. Robinson

http://molokai.sese.asu.edu/~jimbo/indexed/publications/other_co_author/0077_Morris_RV_Hematite_Spherules_in_Basaltic_tephra_altered_Earth_Planet_2005.pdf

Abstract: Iron-rich spherules (>90% Fe2O3 from electron microprobe analyses) ~10-100 µm in diameter are found within sulfate-rich rocks formed by aqueous, acid-sulfate alteration of basaltic tephra on Mauna Kea volcano, Hawaii. Although some spherules are nearly pure Fe, most have two concentric compositional zones, with the core having a higher Fe/Al ratio than the rim. Oxide totals less than 100% (93-99%) suggest structural H2O and or OH-1.  The grey color of the spherules implies specular hematite. Whole-rock powder X-ray diffraction spectra are dominated by peaks from smectite and the hydroxyl sulfate mineral natroalunite as alteration products and plagioclase feldspar that was present in the precursor basaltic tephra. 

Keywords: Mars; Meridiani Planum; Mars Exporation Rover; Spherule; hematite; concretions; sulfate

Characteristics of centrifugally cast GX25CrNiSi18-9 steel

By R. Zapała, B. Kalandyk and A. Rakowska

https://core.ac.uk/reader/27260690

Abstract: The paper presents the results of microstructural examinations of the industrial heat-resistant centrifugally cast  GX25CrNiSi18-9 steel characterized by increased content of Cu. The study included changes in the microstructure of base cast steel respective of the steel held at a temperature of 900 and 950°C for 48 hours. Based on the results obtained, an increase in microhardness of the examined cast steel matrix with  increasing temperature was stated, which was probably caused by fine precipitates enriched in Cr, M o, and C forming inside the matrix grains. The layer of scale formed on the tested cast steel oxidized in the atmosphere of air at 900 and 950°C was characterized by an increased tendency to degradation with increasing temperature of the conducted tests.

Keywords: Metallography, Heat resistance 18Cr-9Ni cast steel, Microstructure

Investigations of high-temperature corrosion of Cr-Ni cast steel

  1. Zapała and B. Kalandyk

https://core.ac.uk/reader/25874085

Abstract: Austenitic cast steels of Cr25-Ni32-Nb grade have found wide application in chemical and petrochemical industries. This study discusses the  problem of the kinetics of oxidation of these materials in the atmosphere of laboratory air at temperatures of 930 and 1000 °C.  Considering the operating conditions of castings centrifugally cast reformer tubes), the results of the oxidation test of specimens taken  from the zone of columnar crystals and equiaxial grains were presented. 

Keywords: Fe-Cr-Ni alloys; Oxidation; High temperature corrosion; Oxidation kinetic; Scale 

Mechanism of Pinhole Formation in Membrane Electrode Assemblies for PEM Fuel Sells

 Vesna Stanic Teledyne Energy Systems, Inc., West Palm Beach, FL, 33417 Mark Hoberecht NASA Glenn Research Center, Cleveland, OH, 44135

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050198939.pdf

Abstract: The pinhole formation mechanism was studied with a variety of MEAs using ex-situ and in-situ methods. The ex-situ tests included the MEA aging in oxygen and MEA heat of ignition. In-situ durability tests were performed in fuel cells at different operating conditions with hydrogen and oxygen. After the in-situ failure, MEAs were analyzed with an Olympus BX 60 optical microscope and Cambridge 120 scanning electron microscope. MEA chemical analysis was performed with an IXRF EDS microanalysis system. The MEA failure analyses showed that pinholes and tears were the MEA failure modes. The pinholes appeared in MEA areas where the membrane thickness was drastically reduced. Their location coincided with the stress concentration points, indicating that membrane creep was responsible for their formation. Some of the pinholes detected had contaminant particles precipitated within the membrane. This mechanism of pinhole formation was correlated to the polymer blistering.

Silica nanoparticles aid in structural leaf coloration in the Malaysian tropical rainforest understorey herb Mapania caudata

Greg Strout, Scott D. Russell, Drew P. Pulsifer, Sema Erten, Akhlesh Lakhtakia and David W. Lee,

https://www.researchgate.net/publication/255987009_Silica_nanoparticles_aid_in_structural_leaf_coloration_in_the_Malaysian_tropical_rainforest_understorey_herb_Mapania_caudata

Abstract: Background and AimsBlue-green iridescence in the tropical rainforest understorey sedge Mapania caudata creates structural coloration in its leaves through a novel photonic mechanism. Known structures in plants producing iridescent blues consist of altered cellulose layering within cell walls and in special bodies, and thylakoid membranes in specialized plastids. This study was undertaken in order to determine the origin of leaf iridescence in this plant with particular attention to nano-scale components contributing to this coloration. Methods Adaxial walls of leaf epidermal cells were characterized using high-pressure-frozen freeze-substituted specimens, which retain their native dimensions during observations using transmission and scanning microscopy, accompanied by energy-dispersive X-ray spectroscopy to identify the role of biogenic silica in wall-based iridescence. Biogenic silica was experimentally removed using aqueous Na2CO3 and optical properties were compared using spectral reflectance. Key Results and Conclusions Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue colour. Addition of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural colour in organisms.

Keywords: Mapania, Cyperaceae, leaf, epidermis, cell wall, silica, helicoids, nanoparticle, iridescence, circular polarization, photonics.

Novel Synthesis of Kanamycin Conjugated Gold Nanoparticles with Potent Antibacterial Activity

By Jason N. Payne, Hitesh K. Waghwani, Michael G. Connor, William Hamilton, Sarah Tockstein, Harsh Moolani, Fenil Chavda, Vivek Badwaik, Matthew B. Lawrenz and Rajalingam Dakshinamurthy

https://core.ac.uk/reader/82866225

Abstract: With a sharp increase in the cases of multi-drug resistant (MDR) bacteria all over the world, there is a huge demand to develop a new generation of antibiotic agents to fight them. As an alternative to the traditional drug discovery route, we have designed an effective antibacterial agent by modifying an existing commercial antibiotic, kanamycin, conjugated on the surface of gold nanoparticles (AuNPs).  In this study, we report a single-step synthesis of kanamycin-capped AuNPs (Kan-AuNPs) utilizing the combined reducing and capping properties of kanamycin. While Kan-AuNPs have increased toxicity to a primate cell line (Vero 76), antibacterial assays showed dose-dependent broad spectrum activity of Kan-AuNPs against both Gram-positive and Gram-negative bacteria, including Kanamycin resistant bacteria. Further, a significant reduction in the minimum inhibitory concentration (MIC) of Kan-AuNPs was observed when compared to free kanamycin against all the bacterial strains tested.  Mechanistic studies using transmission electron microscopy and fluorescence microscopy indicated that at least part of Kan-AuNPs increased efficacy may be through disrupting the bacterial envelope, resulting in the leakage of cytoplasmic content and the death of bacterial cells. Results of this study provide critical information about a novel method for the development of antibiotic capped AuNPs as potent next-generation antibacterial agents.

Keywords: gold nanoparticles, kanamycin, antibiotic resistance, antibacterial activity, characterization

High-Temperature Superconducting Fiber

By Daniel Homa, Yongxuan Liang and Gary Pickrell

https://core.ac.uk/reader/81569271

Abstract: In  this  study,  we demonstrated  superconductivity in  a fiber with an yttrium  barium copper oxide core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and post-process annealing treatment in excess oxygen. The fibers maintained overall diameters ranging from 100–900 microns and core diameters of 50–700 microns. Superconductivity of this fiber design was validated via the traditional four-point probe test method in a bath of liquid nitrogen at temperatures on the order of 93 K. The high-temperature superconducting fiber provides a glimpse of its cross cutting potential in fields of electromagnetism, healthcare, optics, and energy and lends credence to the promise for superconductivity.

Keywords: Superconductivity, Superconductor cables, Fiber optics, Optical fiber, High-temperature superconductors

Cellular Immunologic Responses to Cochlear Implantation in the Human

Joseph B. Nadol, Jr., M.D., Jennifer T. O’Malley, Barbara J. Burgess, and Donald Galler

https://www.sciencedirect.com/science/article/pii/S037859551400152X?via%3Dihub

Abstract: A cochlear implant array consists of biomaterials, including metal and polymeric in type which are biocompatible, but not necessarily bio-inert. Histologic evidence of a foreign body reaction has been described in temporal bones in patients who in life had undergone cochlear implantation. In the current study, the cellular immune response was characterized using immunohistochemical stains for B-cell lymphocytes (CD20), T-cell lymphocytes (CD3), and macrophages (CD68). In addition, energy dispersive spectroscopy by scanning electron microscopy (EDS-SEM) was performed to characterize the nature of particulate foreign material seen near the electrode array. Infiltrations of B-cell and Tcell lymphocytes and macrophages were identified immunohistochemically. The track of the electrode array was frequently lined by multi-nucleated foreign body giant cells. Energy dispersive X-ray spectroscopy identified the particulate material found in the fibrous sheeth surrounding the cochlear implant to be consistent with platinum.

Bridging the Gap: MXRF Technique Rapidly Maps Centerline Segregation

Joydeep Sengupta, Jackie Leung, Kenny Witherspoon

http://digital.library.aist.org/pages/PR-370-272.htm

Abstract: Advanced High Strength Steel (AHSS) and Ultra High Strength Steel (UHSS) slabs produced form ArcelorMittal casters worldwide have high alloy contents-manganese up to 5%, silcon up to 2% and aluminum up to 2% – for achieving desired mechanical properties for automotive customers. These specialty steel grade groups include Dual Phase (DP) and TRIP steel grades. High Strenght Low Alloy (HSLA) steel grades slated for the line pipe industry also have high manganese content (upt to 1%) and relatively higher sulphur (>50ppm) and phosophorus (>100ppm) contents comparted to other steel grades

Keywords: Continuous Casting, Centerline Segregtaion, Advanced High Strength Steels, X-Ray Fluorescence

Comparing the Detection of Iron-Based Pottery Pigment on a Carbon-Coated Sherd by SEM-EDS and by Micro-XRF-SEM

Michael W. PendletonDorothy K. WashburnE. Ann Ellis, and Bonnie B. Pendleton

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941461

Abstract: The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis.

Keywords: scanning electron microscopy, pottery pigment, archeology

Macroscopic X-Ray Fluorescence Capability for Large-Scale Elemental Mapping

https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-11-02172

Heather M. Volz, George J. Havrilla, Robert M. Aikin, Jr., Velma M. Montoya

Abstract: Compositional information at moderate resolution over many centimeters will be powerful in materials research, not only to validate casting models but also to understand large-scale phenomena during solidification. These elemental differences across a part have a huge impact on materials properties so that identifying variations will help industry immensely with process optimization and quality control. Therefore, a nondestructive method of obtaining spatially resolved elemental compositions over large areas would be very useful. To this end, we have developed an enhanced macro-x-ray fluorescence (XRF) capability in conjunction with IXRF Systems, Inc. (Houston, Texas) to accommodate samples larger than those that typically fit into an XRF instrument chamber. Our system can accommodate samples up to 70 cm x 70 cm x 25 cm, which is unique in that most systems are trending toward smaller micro- and nano-XRF. This system uses a rhodium tube having a maximum power of 35 kV and 100 JlA; the detector is a liquid-nitrogen cooled, lithium-drifted silicon detector, and the smallest spot size is approximately 400 micrometers. Reference standard specimens will enable quantitative elemental mapping and analysis. Challenges to modifying the equipment are described. Nonuniformities in the INCONEL 718 system will be shown and discussed. As another example, segregation of niobium and molybdenum in depleted uranium (DU) castings has been known to occur based on wet chemical analysis [inductively coupled-plasma mass spectrometry (ICPMS)], but this destructive and time-consuming measurement is not practical for routine inspection of ingots. The U-Nb system is complicated because of overlap of the Nb K-alpha line with the U L-beta. Preliminary quantitative results are included on the distribution ofNb across slices from DU castings with different cooling rates. We foresee this macro-XRF elemental mapping capability becoming a valuable asset to the materials industry. 

Study of the possibility of using IXRF technique to detect the elements present in dust using Monte Carlo N Particles 

  1. R. Dehghan , A. Negarestani , M. R. Rezaie

http://bcc.bas.bg/BCC_Volumes/Volume_49_Number_4_2017/BCC-49-4-2017-4456-Dehghan-874-878%20.pdf

Abstract: Detecting heavy metals present in soil and dust as a major factor of environmental pollution has got a particular importance. An experimental (laboratory) method based on energy-dispersive X-ray fluorescence (EDXRF) technique was utilized so far to detect the elements. In this research, the Monte Carlo method based on the EDXRF technique was used to detect the elements. MCNPX2.7 code is based on Monte Carlo calculations and is able to trace 32 particles including photons within the range of X-rays and γ-rays. In this paper, the outcomes of multi-source EDXRF simulation technique were compared with the experimental results. The comparison shows that multi-source EDXRF technique(IXRF) is able to detect the percentage of elements present in soil and dust with a high compatibility. 

Keywords: IXRF; Elements; Dust; EDXRF; Multi Source; MCNPX; Detection

Micro X-Ray Fluorescence in Food Forensics & Food Safety

Var L. St. Jeor, Carrie A. Lendon

http://www.icdd.com/resources/axa/VOL57/V57_19.pdf

Abstract: For this study, Energy Dispersive Micro X-ray Fluorescence (µXRF) is applied in a practical sense to real problems existing within the food industry.  It is also compared to electron-based Energy Dispersive Spectroscopy (EDS). Both systems are generally considered non-destructive methods for determining elemental composition; however µXRF demonstrates specific advantages for elements heavier than phosphorus, or above ~2KeV in the energy spectrum.  Elements such as iron, nickel and copper, can be detected in smaller concentrations by µXRF than EDS. Although the X-ray probe is fixed, two-dimensional elemental dot maps can be collected by robotically scanning the SEM stage using available software. Since µXRF employs small probe sizes (focal points are usually 10-50µm), and X-ray probes are not usually optically visible, a simple method for aligning and “aiming” of that probe is presented so that very small, specific regions, or very small particles can be analyzed. When combined with SEM, µXRF becomes a very powerful tool.

Detecting iron-based pigments on ruthenium-coated ancestral Pueblo pottery using variable pressure scanning electron microscopy

M.W.Pendleton, D.K.Washburn, E.A.Ellis and B.B.Pendleton

https://core.ac.uk/reader/81545449

 

Abstract: Ancestral Puebloan black-on-white ceramics of the American Southwest can be classified as containing pigments within their painted designs containing high levels of organic-based elements such as potassium, or mineral-based elements such as iron, or a mixture of these elements. The identification of pigment elements of the pottery of a site is fundamental in determining the site’s cultural and temporal context. This paper will concentrate only on the analysis of mineral based pigment which was shown by previous researchers to exhibit greater concentrations of iron than organic based pigment. Although the visual discrimination of these pigments can be difficult if the pigment is a mixture of both pigment types or if the pigment is worn, this paper will describe a sherd sample previously shown to contain only mineral pigment. For the present study, a Tescan variable pressure scanning electron microscope, a JEOL 6400 scanning electron microscope, and a Hitachi S-3400N scanning electron microscope were used with the same sherd. This sherd was coated with ruthenium to reduce charging without the visual color change associated with sputtered metal coatings. A reduction in microscope chamber vacuum also greatly reduced charging of unpainted areas. An energy dispersive spectrometry detector produced a map of the iron present in the sherd. Areas of iron in the sherd were identified using a backscatter electron detector. Iron as well as other elements present in the paint pigment was also detected using micro-X-ray fluorescence on the same sherd.

Keywords: Iron, Pigment, Archeological pottery, Scanning electron microscopy

A Test of Diagenetic Ordering in Siliceous Lithofacies, Montery Formation, Southwestern Casmalia Hills: Santa Maria Basin, Ca

Idu Opral C. Ijeoma and Richard J. Behl

http://www.searchanddiscovery.com/abstracts/html/2014/90191pacsec/abstracts/1.7.html

Abstract: A detailed analysis of a well-exposed section through the Sisquoc and Monterey formations test the results of previous silica diagenesis studies by Isaacs (1981), Pisciotto (1981), and Murata and Nakata (1974). From these studies a key understanding was that for each compositional range, there would be a regular progression of opal-A opal-CT progressive ordering of opal-CT d101 spacing quarts. This progression should apply to any stratigraphic succession for strata of a particular compositional range, and opal-CT d101 could be used as a geothermometer and indicator of maximum burial depth. Surprisingly, these classic studies analyzed only limited numbers of samples in single successions, so we decided to test if the same trends are evident in a very dense data set in one stratigraphic sequence, 230 outcrop and road-cut samples were collected from a 700-meter thick sections and analyzed for composition, silica phase, and d101-spacing using combined EDS/XRF and XRD. 

Hematite spherules in basaltic tephra altered under aqueous, acid-sulfate conditions on Mauna Kea volcano, Hawaii: Possible clues for the occurrence of hematite-rich spherules in the Burns formation at Meridiani Planum, Mars

R.V. Morris ,*, D.W. Ming , T.G. Graff , R.E. Arvidson  , J.F. Bell III , S.W. Squyres , S.A. Mertzman , J.E. Gruener  , D.C. Golden f , L. Le , G.A. Robinson

http://molokai.sese.asu.edu/~jimbo/indexed/publications/other_co_author/0077_Morris_RV_Hematite_Spherules_in_Basaltic_tephra_altered_Earth_Planet_2005.pdf

Abstract: Iron-rich spherules (>90% Fe2O3 from electron microprobe analyses) ~10-100 µm in diameter are found within sulfate-rich rocks formed by aqueous, acid-sulfate alteration of basaltic tephra on Mauna Kea volcano, Hawaii. Although some spherules are nearly pure Fe, most have two concentric compositional zones, with the core having a higher Fe/Al ratio than the rim. Oxide totals less than 100% (93-99%) suggest structural H2O and or OH-1.  The grey color of the spherules implies specular hematite. Whole-rock powder X-ray diffraction spectra are dominated by peaks from smectite and the hydroxyl sulfate mineral natroalunite as alteration products and plagioclase feldspar that was present in the precursor basaltic tephra. 

Keywords: Mars; Meridiani Planum; Mars Exporation Rover; Spherule; hematite; concretions; sulfate

Characteristics of centrifugally cast GX25CrNiSi18-9 steel

By R. Zapała, B. Kalandyk and A. Rakowska

https://core.ac.uk/reader/27260690

Abstract: The paper presents the results of microstructural examinations of the industrial heat-resistant centrifugally cast  GX25CrNiSi18-9 steel characterized by increased content of Cu. The study included changes in the microstructure of base cast steel respective of the steel held at a temperature of 900 and 950°C for 48 hours. Based on the results obtained, an increase in microhardness of the examined cast steel matrix with  increasing temperature was stated, which was probably caused by fine precipitates enriched in Cr, M o, and C forming inside the matrix grains. The layer of scale formed on the tested cast steel oxidized in the atmosphere of air at 900 and 950°C was characterized by an increased tendency to degradation with increasing temperature of the conducted tests.

Keywords: Metallography, Heat resistance 18Cr-9Ni cast steel, Microstructure

Investigations of high-temperature corrosion of Cr-Ni cast steel

  1. Zapała and B. Kalandyk

https://core.ac.uk/reader/25874085

Abstract: Austenitic cast steels of Cr25-Ni32-Nb grade have found wide application in chemical and petrochemical industries. This study discusses the  problem of the kinetics of oxidation of these materials in the atmosphere of laboratory air at temperatures of 930 and 1000 °C.  Considering the operating conditions of castings centrifugally cast reformer tubes), the results of the oxidation test of specimens taken  from the zone of columnar crystals and equiaxial grains were presented. 

Keywords: Fe-Cr-Ni alloys; Oxidation; High temperature corrosion; Oxidation kinetic; Scale 

Mechanism of Pinhole Formation in Membrane Electrode Assemblies for PEM Fuel Sells

 Vesna Stanic Teledyne Energy Systems, Inc., West Palm Beach, FL, 33417 Mark Hoberecht NASA Glenn Research Center, Cleveland, OH, 44135

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050198939.pdf

Abstract: The pinhole formation mechanism was studied with a variety of MEAs using ex-situ and in-situ methods. The ex-situ tests included the MEA aging in oxygen and MEA heat of ignition. In-situ durability tests were performed in fuel cells at different operating conditions with hydrogen and oxygen. After the in-situ failure, MEAs were analyzed with an Olympus BX 60 optical microscope and Cambridge 120 scanning electron microscope. MEA chemical analysis was performed with an IXRF EDS microanalysis system. The MEA failure analyses showed that pinholes and tears were the MEA failure modes. The pinholes appeared in MEA areas where the membrane thickness was drastically reduced. Their location coincided with the stress concentration points, indicating that membrane creep was responsible for their formation. Some of the pinholes detected had contaminant particles precipitated within the membrane. This mechanism of pinhole formation was correlated to the polymer blistering.

Silica nanoparticles aid in structural leaf coloration in the Malaysian tropical rainforest understorey herb Mapania caudata

Greg Strout, Scott D. Russell, Drew P. Pulsifer, Sema Erten, Akhlesh Lakhtakia and David W. Lee,

https://www.researchgate.net/publication/255987009_Silica_nanoparticles_aid_in_structural_leaf_coloration_in_the_Malaysian_tropical_rainforest_understorey_herb_Mapania_caudata

Abstract: Background and AimsBlue-green iridescence in the tropical rainforest understorey sedge Mapania caudata creates structural coloration in its leaves through a novel photonic mechanism. Known structures in plants producing iridescent blues consist of altered cellulose layering within cell walls and in special bodies, and thylakoid membranes in specialized plastids. This study was undertaken in order to determine the origin of leaf iridescence in this plant with particular attention to nano-scale components contributing to this coloration. Methods Adaxial walls of leaf epidermal cells were characterized using high-pressure-frozen freeze-substituted specimens, which retain their native dimensions during observations using transmission and scanning microscopy, accompanied by energy-dispersive X-ray spectroscopy to identify the role of biogenic silica in wall-based iridescence. Biogenic silica was experimentally removed using aqueous Na2CO3 and optical properties were compared using spectral reflectance. Key Results and Conclusions Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue colour. Addition of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural colour in organisms.

Keywords: Mapania, Cyperaceae, leaf, epidermis, cell wall, silica, helicoids, nanoparticle, iridescence, circular polarization, photonics.

Novel Synthesis of Kanamycin Conjugated Gold Nanoparticles with Potent Antibacterial Activity

By Jason N. Payne, Hitesh K. Waghwani, Michael G. Connor, William Hamilton, Sarah Tockstein, Harsh Moolani, Fenil Chavda, Vivek Badwaik, Matthew B. Lawrenz and Rajalingam Dakshinamurthy

https://core.ac.uk/reader/82866225

Abstract: With a sharp increase in the cases of multi-drug resistant (MDR) bacteria all over the world, there is a huge demand to develop a new generation of antibiotic agents to fight them. As an alternative to the traditional drug discovery route, we have designed an effective antibacterial agent by modifying an existing commercial antibiotic, kanamycin, conjugated on the surface of gold nanoparticles (AuNPs).  In this study, we report a single-step synthesis of kanamycin-capped AuNPs (Kan-AuNPs) utilizing the combined reducing and capping properties of kanamycin. While Kan-AuNPs have increased toxicity to a primate cell line (Vero 76), antibacterial assays showed dose-dependent broad spectrum activity of Kan-AuNPs against both Gram-positive and Gram-negative bacteria, including Kanamycin resistant bacteria. Further, a significant reduction in the minimum inhibitory concentration (MIC) of Kan-AuNPs was observed when compared to free kanamycin against all the bacterial strains tested.  Mechanistic studies using transmission electron microscopy and fluorescence microscopy indicated that at least part of Kan-AuNPs increased efficacy may be through disrupting the bacterial envelope, resulting in the leakage of cytoplasmic content and the death of bacterial cells. Results of this study provide critical information about a novel method for the development of antibiotic capped AuNPs as potent next-generation antibacterial agents.

Keywords: gold nanoparticles, kanamycin, antibiotic resistance, antibacterial activity, characterization

High-Temperature Superconducting Fiber

By Daniel Homa, Yongxuan Liang and Gary Pickrell

https://core.ac.uk/reader/81569271

Abstract: In  this  study,  we demonstrated  superconductivity in  a fiber with an yttrium  barium copper oxide core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and post-process annealing treatment in excess oxygen. The fibers maintained overall diameters ranging from 100–900 microns and core diameters of 50–700 microns. Superconductivity of this fiber design was validated via the traditional four-point probe test method in a bath of liquid nitrogen at temperatures on the order of 93 K. The high-temperature superconducting fiber provides a glimpse of its cross cutting potential in fields of electromagnetism, healthcare, optics, and energy and lends credence to the promise for superconductivity.

 

Keywords: Superconductivity, Superconductor cables, Fiber optics, Optical fiber, High-temperature superconductors

Cellular Immunologic Responses to Cochlear Implantation in the Human

Joseph B. Nadol, Jr., M.D., Jennifer T. O’Malley, Barbara J. Burgess, and Donald Galler

https://www.sciencedirect.com/science/article/pii/S037859551400152X?via%3Dihub

Abstract: A cochlear implant array consists of biomaterials, including metal and polymeric in type which are biocompatible, but not necessarily bio-inert. Histologic evidence of a foreign body reaction has been described in temporal bones in patients who in life had undergone cochlear implantation. In the current study, the cellular immune response was characterized using immunohistochemical stains for B-cell lymphocytes (CD20), T-cell lymphocytes (CD3), and macrophages (CD68). In addition, energy dispersive spectroscopy by scanning electron microscopy (EDS-SEM) was performed to characterize the nature of particulate foreign material seen near the electrode array. Infiltrations of B-cell and Tcell lymphocytes and macrophages were identified immunohistochemically. The track of the electrode array was frequently lined by multi-nucleated foreign body giant cells. Energy dispersive X-ray spectroscopy identified the particulate material found in the fibrous sheeth surrounding the cochlear implant to be consistent with platinum.