“Real-World” Microscopy: Understanding Environment-Sensitive Behavior of Ni-Base Welds

1998 ◽  
Vol 4 (S2) ◽  
pp. 528-529
Author(s):  
M. G. Burke ◽  
R. J. Wehrer ◽  
C.M. Brown
Keyword(s):  
Nuclear Power ◽  
Base Alloy ◽  
Analytical Electron Microscopy ◽  
Furnace Cool ◽  
Environmental Embrittlement ◽  
Reported Study ◽  
Compositional Changes ◽  
Insight Into ◽  
Sensitive Behavior

Ni-base alloy welds such as EN82H weld metal are frequently employed in nuclear power applications where resistance to corrosion is required. Results of a recently reported study of the mechanical properties of EN82H welds show that this alloy is susceptible to low-temperature (∼100°C) environmental embrittlement (LTEE) in hydrogenated water. LTEE is a manifestation of hydrogen embrittlement in these alloys.1 Recent LTEE tests have demonstrated a beneficial effect of a high-temperature (∼1100°C) anneal and furnace-cool in alleviating the material's susceptibility to LTEE. Understanding the reason for the reduction in LTEE susceptibility requires detailed characterization of the microstructure so that the specific structural and compositional changes that have been induced by the solution-anneal can be identified. This study reports the results of light optical and analytical electron microscopy (AEM) characterization of the microstructures of as-fabricated and as-solution-annealed EN82H welds with the objective of providing insight into the observed LTEE behavior.

scholarly journals Irradiation-Induced Microstructural Changes in Alloy X-750

1997 ◽  
Vol 3 (S2) ◽  
pp. 551-552
Author(s):  
E.A. Kenik
Keyword(s):  
Power Systems ◽  
Neutron Irradiation ◽  
Nuclear Power ◽  
Base Alloy ◽  
Analytical Electron Microscopy ◽  
Air Cooling ◽  
Probe Diameter ◽  
Before And After ◽  
Radiation Induced ◽  
Composition Profiles

Alloy X-750 is a γ´-strengthened Ni-base alloy that is often used in nuclear power systems for its excellent corrosion resistance and good mechanical properties. However, radiation-induced segregation (RIS) and irradiation-assisted stress corrosion cracking (IASCC) can occur under neutron irradiation. The present study examines the microstructure and composition profiles in a heat of Alloy X-750 before and after neutron irradiation.The material was in the HTH commercial heat treatment (lh at 1121°C + air cooling + 20h at 704°C). Specimens were prepared from both control material and material irradiated at 360°C to a fluence of 2.3 × 1020 n/cm2 (E > 1 MeV), which was estimated to produce -0.4 displacements per atom. High spatial resolution analytical electron microscopy was performed in a Philips EM400T/FEG operated in the STEM mode with a probe diameter of ∼1.4 nm (FWHM). Composition profiles were acquired in two different ways: all energy dispersive X-ray spectrometry (EDS) and some parallel-detection electron energy-loss spectrometry (PEELS) profiles were acquired as individual spot analyses, whereas the majority of the PEELS profiles were acquired as spectrum lines with ∼10 s acquisition times per point. The quoted compositions are as measured (wt%); no deconvolution for the effect of the excited volume was performed.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Interface structures in polycrystalline ceramic materials

1986 ◽  
Vol 44 ◽  
pp. 468-471
Author(s):  
K. J. Morrissey
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Physical And Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Polycrystalline Materials ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

Applications of ultramicrotomy for materials characterization

1993 ◽  
Vol 51 ◽  
pp. 232-233
Author(s):  
R.T. Blackham ◽  
J.J. Haugh ◽  
C.W. Hughes ◽  
M.G. Burke
Keyword(s):  
Materials Science ◽  
Microstructural Analysis ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Thermally Induced ◽  
Radiation Induced ◽  
Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

SANICRO 71

Alloy Digest ◽  
1965 ◽  
Vol 14 (12) ◽  
Keyword(s):  
Nuclear Power ◽  
Elevated Temperatures ◽  
Power Reactor ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Resistance ◽  
Nuclear Power Reactor ◽  
Temperature Performance ◽  
Resistance To Stress ◽  
Nickel Base

Abstract Sanicro 71 is a nickel-base alloy having good resistance to stress-corrosion, oxidation and creep at elevated temperatures. It is recommended for nuclear power reactor heat exchanger tubes, aircraft turbojet engines and for equipment in the textile, plastic, and chemical industries. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-108. Producer or source: Sandvik.

scholarly journals First Insight into Nutraceutical Properties of Local Salento Cichorium intybus Varieties: NMR-Based Metabolomic Approach

2021 ◽  
Vol 18 (8) ◽  
pp. 4057
Author(s):  
Chiara Roberta Girelli ◽  
Francesca Serio ◽  
Rita Accogli ◽  
Federica Angilè ◽  
Antonella De Donno ◽  
...  
Keyword(s):  
1H Nmr ◽  
Cichorium Intybus ◽  
Resonance Spectroscopy ◽  
Metabolic Profiles ◽  
Whole Plant ◽  
Different Content ◽  
Insight Into ◽  
Nutraceutical Properties ◽  
Metabolomic Approach

Background: Plants of genus Cichorium are known for their therapeutic and nutraceutical properties determined by a wealth of phytochemical substances contained in the whole plant. The aim of this paper was to characterize the metabolic profiles of local Salento chicory (Cichorium intybus L.) varieties (“Bianca”, “Galatina”, “Leccese”, and “Otranto”) in order to describe their metabolites composition together with possible bioactivity and health beneficial properties. Methods: The investigation was performed by 1H-NMR spectroscopy and Multivariate Analysis (MVA), by which the metabolic profiles of the samples were easily obtained and compared. Results: The supervised Partial Least Squares Discriminant Analysis (PLS-DA) analysis showed as “Bianca” and “Galatina” samples grouped together separated by “Leccese” and “Otranto” varieties. A different content of free amino acids and organic acids was observed among the varieties. In particular a high content of cichoric and monocaffeoyl tartaric acid was observed for the “Leccese” variety. The presence of secondary metabolites adds significant interest in the investigation of Cichorium inthybus, as this vegetable may benefit human health when incorporated into the diet. Conclusions: The 1H-NMR (Nuclear Magnetic Resonance Spectroscopy) based characterization of Salento chicory varieties allowed us to determine the potential usefulness and nutraceutical properties of the product, also providing a method to guarantee its authenticity on a molecular scale.

scholarly journals Specificities and Synergistic Actions of Novel PL8 and PL7 Alginate Lyases from the Marine Fungus Paradendryphiella salina

2021 ◽  
Vol 7 (2) ◽  
pp. 80
Author(s):  
Bo Pilgaard ◽  
Marlene Vuillemin ◽  
Jesper Holck ◽  
Casper Wilkens ◽  
Anne S. Meyer
Keyword(s):  
Alginate Lyase ◽  
Marine Fungus ◽  
Brown Macroalgae ◽  
Polysaccharide Lyases ◽  
Alginate Lyases ◽  
Encoding Genes ◽  
Substrate Affinities ◽  
Alginate Degradation ◽  
Insight Into

Alginate is an anionic polysaccharide abundantly present in the cell walls of brown macroalgae. The enzymatic depolymerization is performed solely by alginate lyases (EC 4.2.2.x), categorized as polysaccharide lyases (PLs) belonging to 12 different PL families. Until now, the vast majority of the alginate lyases have been found in bacteria. We report here the first extensive characterization of four alginate lyases from a marine fungus, the ascomycete Paradendryphiella salina, a known saprophyte of seaweeds. We have identified four polysaccharide lyase encoding genes bioinformatically in P. salina, one PL8 (PsMan8A), and three PL7 alginate lyases (PsAlg7A, -B, and -C). PsMan8A was demonstrated to exert exo-action on polymannuronic acid, and no action on alginate, indicating that this enzyme is most likely an exo-acting polymannuronic acid specific lyase. This enzyme is the first alginate lyase assigned to PL8 and polymannuronic acid thus represents a new substrate specificity in this family. The PL7 lyases (PsAlg7A, -B, and -C) were found to be endo-acting alginate lyases with different activity optima, substrate affinities, and product profiles. PsAlg7A and PsMan8A showed a clear synergistic action for the complete depolymerization of polyM at pH 5. PsAlg7A depolymerized polyM to mainly DP5 and DP3 oligomers and PsMan8A to dimers and monosaccharides. PsAlg7B and PsAlg7C showed substrate affinities towards both polyM and polyG at pH 8, depolymerizing both substrates to DP9-DP2 oligomers. The findings elucidate how P. salina accomplishes alginate depolymerization and provide insight into an efficient synergistic cooperation that may provide a new foundation for enzyme selection for alginate degradation in seaweed bioprocessing.

Healing Fukushima: Radiation hazards and disaster medicine in post-3.11 Japan

2019 ◽  
Vol 49 (3) ◽  
pp. 333-354 ◽  
Author(s):  
Shi Lin Loh ◽  
Sulfikar Amir
Keyword(s):  
Public Health ◽  
Nuclear Power ◽  
Radiation Risk ◽  
Disaster Medicine ◽  
Radiation Hazards ◽  
Medical Practitioners ◽  
Life And Death ◽  
Nuclear Disaster ◽  
Fukushima Nuclear Disaster

What happens when expertise is forced to face disasters of unprecedented scales? How is knowledge produced in critical moments when every action and decision is a matter of life and death? And how are local social networks mobilized to cope with unforeseen crisis? This paper addresses these questions by examining the emergence of disaster medicine expertise in the aftermath of Fukushima nuclear disaster that struck Japan in 2011. Studies on Fukushima’s impact have to date revolved around the suffering of Tōhoku citizens and the development of Japan’s nuclear energy industry. Acknowledging the gravity of such work, this paper offers an alternative, but equally crucial angle on the disaster: that of the medical caregiving and public health system built in response to radiation hazards resulting from the triple meltdowns at Fukushima Daiichi nuclear power station. Through detailed interviews conducted with eight medical practitioners in Fukushima Prefecture, this paper analyses the significance and impact of Japan’s most recent radiation disaster on its public health infrastructure. To describe the contingent nature of radiation disaster medicine developed in response to radiation risk in Fukushima, we draw on Jasanoff’s characterization of scientific knowledge as ‘serviceable truths’ with regards to public policy and the law, suggesting that expertise in relation to disasters is usefully understood in analogous terms.

scholarly journals Substrate-dependent competition and cooperation relationships between Geobacter and Dehalococcoides for their organohalide respiration

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yongyi Liang ◽  
Qihong Lu ◽  
Zhiwei Liang ◽  
Xiaokun Liu ◽  
Wenwen Fang ◽  
...  
Keyword(s):  
Electron Donors ◽  
Community Stability ◽  
Organohalide Respiration ◽  
Competition And Cooperation ◽  
Free Competition ◽  
Isolation And Characterization ◽  
Geochemical Cycling ◽  
New Strategy ◽  
Insight Into

AbstractObligate and non-obligate organohalide-respiring bacteria (OHRB) play central roles in the geochemical cycling and environmental bioremediation of organohalides. Their coexistence and interactions may provide functional redundancy and community stability to assure organohalide respiration efficiency but, at the same time, complicate isolation and characterization of specific OHRB. Here, we employed a growth rate/yield tradeoff strategy to enrich and isolate a rare non-obligate tetrachloroethene (PCE)-respiring Geobacter from a Dehalococcoides-predominant microcosm, providing experimental evidence for the rate/yield tradeoff theory in population selection. Surprisingly, further physiological and genomic characterizations, together with co-culture experiments, revealed three unique interactions (i.e., free competition, conditional competition and syntrophic cooperation) between Geobacter and Dehalococcoides for their respiration of PCE and polychlorinated biphenyls (PCBs), depending on both the feeding electron donors (acetate/H2 vs. propionate) and electron acceptors (PCE vs. PCBs). This study provides the first insight into substrate-dependent interactions between obligate and non-obligate OHRB, as well as a new strategy to isolate fastidious microorganisms, for better understanding of the geochemical cycling and bioremediation of organohalides.

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