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At least 37 records · Page 2

Magnetic order effects on the electronic structure of K M MnS 2 ( M = Cu , Li ) with the ThCr 2 Si 2 -type structure

We study the relationship between antiferromagnetic order and the electronic properties of KCuMnS 2 with the ThCr 2 Si 2 -type structure. We propose two magnetic structures for KCuMnS 2 with the ThCr 2 Si 2 -type structure. Powder samples of KCuMnS 2 and KLiMnS 2 were prepared for structural studies and magnetization measurements. In both compounds, the Mn 2+ site is alloyed by either Cu + or Li + . We also prepared single crystals of KCuMnS 2 for x-ray and neutron-diffraction studies and resistivity measurements. We relate these properties to the electronic structure calculated with density functional theory. Neutron-diffraction studies reveal that KCuMnS 2 exhibits long-range magnetic ordering with a Néel temperature near 160 K and a moment of 0.92(2) μ B /Mn 2+ at 6 K. In contrast, KLiMnS 2 never exhibits long-range magnetic ordering down to 3.5 K. Here, both sulfides never display a crystallographic phase transition from our temperature-dependent x-ray and neutron-diffraction studies. We discuss the magnetic phases in detail and how they relate to isostructural phases such as iron-based superconductors and related chalcogenides. Electrical resistance measurements indicate that while KCuMnS 2 is semiconducting, there is an anomaly around the Néel temperature, which indicates that long-range magnetism influences its electronic structure.

36 MATERIALS SCIENCE↗

Memory behavior of an MNS capacitor.

Metal-/Si nitride/-Si/MNS/ capacitor memory behavior due to high voltage pulses, discussing charge transfer, stored charge location and tunneling conduction

Oconnell, M.↗

Coherent to incoherent transition of precipitates during rupture test in TP347H austenitic stainless steels

Precipitation of various particles and their growth during rupture test have been investigated in TP347H austenitic stainless steels using a transmission electron microscopy. Various precipitates of MnS, Nb-rich MC, and MnS + MC and MnS + M{sub 2}P complexes are observed in the γ matrix after rupture test at 750 °C. The MnS particles formed independently in the γ matrix show a coherency or semi-coherency with the γ matrix. The Nb-rich MC carbides show also a coherency with the γ matrix. The Nb-rich MC carbides showing a semi-coherency with the MnS also form on the surface of the coherent or semi-coherent MnS particles, and they show a cube-cube orientation relationship with the MnS particles. The MnS + MC complex loses the initial coherency with the γ matrix, as the MC in the complex grows. The Nb-rich M{sub 2}P precipitates formed on the surface of the MnS particles do not show an orientation relationship with the MnS particles or the γ matrix. The MnS particles in the MnS + M{sub 2}P complex hold the initial coherency with the γ matrix. Effects of MnS precipitation followed by the formation of the complexes on rupture life of the TP347H austenitic stainless steels are discussed from the viewpoint of MnS precipitates acting as sinks of free sulfur segregating to the grain boundaries. - Highlights: • Coherent to incoherent transition of precipitates during rupture test in TP347H steels is clarified. • MnS precipitation actively retards the time to intergranular fracture. • Effect of the coherency of secondary precipitates on the coherency loss of the complex particle is compared.

36 MATERIALS SCIENCE↗

Relationship between crystallographic structure of the Ti{sub 2}O{sub 3}/MnS complex inclusion and microstructure in the heat-affected zone (HAZ) in steel processed by oxide metallurgy route and impact toughness

A new method based on electron back scattered diffraction (EBSD) is proposed to determine the structure of titanium oxide/MnS complex inclusion which induced the formation of intragranular acicular ferrite (IAF) in heat-affected zone (HAZ) in steel processed by oxide metallurgy route. It was found that the complex inclusion was Ti{sub 2}O{sub 3}/MnS, the orientation relationship between Ti{sub 2}O{sub 3} and MnS was also examined, and the crystallographic orientation relationship among IAF, Ti{sub 2}O{sub 3}/MnS complex inclusion, austenite, bainite formed at lower temperature is researched systematically. It was observed that MnS precipitated on Ti{sub 2}O{sub 3} at specific habit plane and direction and MnS had a specific orientation relationship ((0001) Ti{sub 2}O{sub 3}//(111) MnS), <10–10> Ti{sub 2}O{sub 3}//<110> MnS) with respect to Ti{sub 2}O{sub 3}. Intragranular acicular ferrite (IAF) nucleated on MnS part of the Ti{sub 2}O{sub 3}/MnS complex inclusion had no specific orientation relationship with MnS. IAF and the surrounding bainite had different Bain groups, so that there was an increase in high angle boundaries, which was beneficial for the toughness of HAZ. - Highlights: • The inclusion of TiO{sub x}/MnS that induced IAF formation is identified to be Ti{sub 2}O{sub 3}/MnS. • The inclusion is identified based on electron back scattered diffraction (EBSD). • MnS and Ti{sub 2}O{sub 3} had specific orientation relationship of Ti{sub 2}O{sub 3}/MnS complex inclusion. • The IAFs formed on the same inclusion tend to be in one Bain group. • IAF and the surrounding bainite tend to be in different Bain groups.

36 MATERIALS SCIENCE↗

Invasive intraductal papillary mucinous neoplasms of the pancreas: relationships between mural nodules detected on thin-section contrast-enhanced MDCT and invasive components

Purpose: To elucidate the relationships between mural nodules (MNs) and invasive components in patients with invasive intraductal papillary mucinous neoplasm (IPMN) on the basis of thin-section contrast-enhanced multidetector CT (CE-MDCT) and pathologic findings. Methods: This retrospective study included 28 patients with surgically confirmed invasive IPMN. Two radiologists independently evaluated the thin-section (1-mm section thickness, no overlap) triple-phase CE-MDCT images for MNs, invasive components, and the continuity between them using a five-point scale (confidence scores of 1–3 as negative, 4 and 5 as positive). Kappa statistic was used to evaluate interobserver agreement. The CE-MDCT findings were correlated with pathologic findings. Results: Interobserver agreement was good or excellent. MNs consisting of tumor cells were recognized in 12 (42.9%) of 28 patients with no discrepancy between the two radiologists. Invasive components were detected in 85.7% and 82.1% in the pancreatic parenchymal phase for radiologist 1 and 2, respectively, and recognized as hypoattenuating areas. Pathologic continuities between MNs and invasive components were confirmed in five (41.7%) of 12 patients with MNs and these were detected on CE-MDCT. When combined seven patients without continuities between MNs and invasive components and 16 patients without MNs, the invasive components pathologically derived from non-nodular low-height papillary epithelium in 23 (82.1%) of 28 patients. Conclusions: The invasive components derived more often from low-height papillary epithelium without MN appearance on CE-MDCT than from MN. Careful attention should be paid to the existence of an invasive component even in the absence of an enhancing MN.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Precipitation Behaviors of TiN Inclusion in GCr15 Bearing Steel Billet

There are many types of non-metallic TiN-based inclusions observed in GCr15 bearing steel, including single-particle TiN, multi-particle polymerized TiN, and complex inclusions like TiN-MnS, TiN-MgO-MgAl{sub 2}O{sub 4} (TiN-MgO-MA), and TiN-MgAl{sub 2}O{sub 4}-MnS (TiN-MA-MnS). Thermodynamic calculations suggest that single-particle TiN precipitates dominate the mushy zone of GCr15 bearing steel. Kinetic calculations regarding TiN growth suggest that the final size of the single-particle TiN ranges between 1 and 6 μm in the initial concentration range of [pct Ti] = 0.0060 to 0.0079 and [pct N] = 0.0049 to 0.0070, at 1620 to 1640 K and a local cooling rate of 0.5 to 10 K/s. The multi-particle polymerized TiN are formed by single TiN particles in three stages: single-particle TiN inclusions approach each other drawn by the cavity bridge force (CBF), local active angles consolidate, and neck region sintering occurs. Based on the thermodynamic calculations of TiN, MnS, and MgO precipitation, the formation behaviors of complex inclusions of TiN-MnS, TiN-MgO-MA, and TiN-MA-MnS were investigated.

36 MATERIALS SCIENCE↗

EBSD analysis of magnesium addition on inclusion formation in SS400 structural steel

In this study, the effect of magnesium addition on the inclusion formation in SS400 steel was investigated. The experimental specimens with and without Mg addition treatment were compared. The microstructure was observed using optical microscopy after etching with 3% nital. The morphology and chemical composition of the inclusions were analyzed via scanning electron microscopy and energy dispersive spectrometry. The lattice structure and orientation of the inclusions were identified by electron backscattering diffraction. The average size of inclusions in SS400 was between 0.67 and 0.75 μm, and between 0.65 and 0.68 μm in SS400 + Mg. The 2 ppm Mg addition resulted in the oxide formation change from Al{sub 2}O{sub 3} to MgO·Al{sub 2}O{sub 3} and in the inclusion formation change from Al{sub 2}O{sub 3}–MnS to MgO·Al{sub 2}O{sub 3}–MnS. Moreover, a simple-phase MnS with an average grain size of 1 μm to 2 μm was observed in rod-like, globular, and polyhedron forms. - Highlights: • The effect of magnesium addition was investigated for SS400 steel. • 2 ppm Mg addition changes the inclusion formation from Al2O3-MnS to MgO·Al2O3-MnS. • MnS observed in inclusions exhibits rod-like, globular, and polyhedron forms.

36 MATERIALS SCIENCE↗

Introducing Molecular Hypernetworks for Discovery in Multidimensional Metabolomics Data

Orthogonal separations of data from high-resolution mass spectrometry can provide insight into sample composition and address challenges of complete annotation of molecules in untargeted metabolomics. “Molecular networks” (MNs), as used in the Global Natural Products Social Molecular Networking platform, are a prominent strategy for exploring and visualizing molecular relationships and improving annotation. MNs are mathematical graphs showing the relationships between measured multidimensional data features. MNs also show promise for using network science algorithms to automatically identify targets for annotation candidates and to dereplicate features associated with a single molecular identity. Here, this paper introduces “molecular hypernetworks” (MHNs) as more complex MN models able to natively represent multiway relationships among observations. Compared to MNs, MHNs can more parsimoniously represent the inherent complexity present among groups of observations, initially supporting improved exploratory data analysis and visualization. MHNs also promise to increase confidence in annotation propagation, for both human and analytical processing. We first illustrate MHNs with simple examples, and build them from liquid chromatography- and ion mobility spectrometry-separated MS data. We then describe a method to construct MHNs directly from existing MNs as their “clique reconstructions”, demonstrating their utility by comparing examples of previously published graph-based MNs to their respective MHNs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Sulfide Transformation with Tellurium Treatment for Y15 Free-Cutting Steel

To investigate the effect of tellurium on the morphology of sulfide, various amounts of tellurium powders were added to the Y15 free-cutting commercial steel melt and then the melt was cooled in different cooling modes. The composition and morphology of sulfide and telluride in steel were analyzed to investigate the mechanism of MnS transformation combined with in situ observation. The results showed that the precipitation of chain-like MnS inclusions was significantly inhibited due to the addition of tellurium, and these MnS inclusions were transformed into complex inclusions with lower aspect ratios, which were composed of MnS and MnTe. In air-cooling mode, the MnS inclusions were effectively spheroidized when the w([Te])/w([S]) in steel was 0.2, whereas tellurium had almost no effect on the morphology of sulfide in furnace-cooling mode. The mechanism of sulfide spheroidization is discussed. The mechanism was verified by in situ observation experiment through high-temperature laser confocal microscopy.

36 MATERIALS SCIENCE↗

Effects of Mg-Al-O-Mn-S inclusion on the nucleation of acicular ferrite in magnesium-containing low-carbon steel

Highlights: • We redefine the mechanism of AF nucleation from Gibbs free energy of nucleation. • Complex inclusions present a better ability of inducing AF formation due to the Mn-depleted zone. • The lattice misfit and the thermal strain are calculated in this study. - Abstract: The effects of inclusion size and chemical composition on acicular ferrite (AF) nucleation and possible nucleation mechanisms were discussed. With the use of low-carbon structure steel containing 13 ppm Mg, the chemical composition and size of inclusions were quantified by scanning electron microscopy combined with an energy dispersive spectroscopy system. Results showed that the complex inclusions MgO-MnS and MgO-Al{sub 2}O{sub 3}-MnS are the most effective inclusions for inducing AF nucleation in Mg-containing A36, and their probabilities of AF nucleation are 35.8% and 41.4%, respectively. Moreover, the inclusion size in the range of 1–2 μm exhibits the most remarkable ability to induce AF formation. AF nucleates at the interface of MgO and MgO-Al{sub 2}O{sub 3} because of the low lattice misfit with AF. Complex inclusions, such as MgO-MnS and MgO-Al{sub 2}O{sub 3}-MnS, present a better ability of inducing AF formation than that of MnS due to the Mn-depleted zone.

36 MATERIALS SCIENCE↗

IR Spectroscopic Study of Interatomic Interaction in [(CoFeB){sub 60}C{sub 40}/SiO{sub 2}]{sub 200} and [(CoFeB){sub 34}(SiO{sub 2}){sub 66}/C]{sub 46} Multilayer Nanostructures with Metal-Containing Composite Layers

This paper presents an IR spectroscopic study of chemical bonds between components of amorphous [(CoFeB){sub 60}C{sub 40}/SiO{sub 2}]{sub 200} and [(CoFeB){sub 34}(SiO{sub 2}){sub 66}/C]{sub 46} multilayer nanostructures (MNS’s) made up of metal-containing composite layers and different interlayers, which influence their electromagnetic properties. Our results demonstrate that, even though the MNS’s have identical elemental compositions, their IR spectra differ significantly. The reason for this is that the main contribution to the IR spectrum of the [(CoFeB){sub 60}C{sub 40}/SiO{sub 2}]{sub 200} MNS is made by its SiO{sub 2} interlayers. The formation of other bonds with oxygen and silicon is blocked by the carbon present in the (CoFeB){sub 60}C{sub 40} composite layers, as evidenced by the presence of the strongest mode in the IR spectra of this structure, which corresponds to boron carbide, BC. The considerable intensity redistribution to the low-frequency region in the IR spectrum of the [(CoFeB){sub 34}(SiO{sub 2}){sub 66}/C]{sub 46} MNS, containing carbon interlayers, is due to the incorporation of nominal SiO2 into the metal-containing composite layers and the partial redistribution of oxygen bonds from the SiO{sub 2} to the 3d transition metals, resulting in the formation of metal oxides and a silicon suboxide. The interaction of the carbon present in the interlayers between the composite layers with elements of the composite layers, in particular with boron, is considerably weaker in comparison with the other MNS, [(CoFeB){sub 60}C{sub 40}/SiO{sub 2}]{sub 200}, which has oxide interlayers.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Molecular Hypernetworks for Exploration of Multi-Dimensional Metabolomics Data (Chyper)

Orthogonal separations of data from high-resolution mass spectrometry can provide insight into sample composition and help address the challenge of complete annotation of molecules in untargeted metabolomics. “Molecular networks” (MNs), as used, for example, in the Global Natural Products Social Molecular Networking platform, are an increasingly popular computational strategy for exploring and visualizing molecular relationships and improving annotation. MNs use graph representations to show the relationships between measured multidimensional data features. MNs also show promise for using network science algorithms to automatically identify targets for annotation candidates and to dereplicate features associated to a single molecular identity. However, more advanced methods may better represent the complexity present in samples. Our work aims to increase confidence in annotation propagation by extending molecular network methods to include “molecular hypernetworks” (MHNs), able to natively represent multiway relationships among observations supporting both human and analytical processing. In this paper we first introduce MHNs illustrated with simple examples, and demonstrate how to build them from liquid chromatography- and ion mobility spectrometry- separated MS data. We then describe a method to construct MHNs directly from existing MNs as their “clique reconstructions”, demonstrating their utility by comparing examples of previously published graph-based MNs to their respective MHNs.

59 BASIC BIOLOGICAL SCIENCES↗

Development of Stretch Flangeable Grade Steels by Inclusion Engineering Approach

The demand for good stretch flangeability in high-strength automotive steels has necessitated due attention on steel cleanliness and processes. The presence of elongated MnS stringers and centerline segregation of nonmetallic inclusions adversely affects the transverse mechanical property. In the present investigation, stretch flangeability of industrially produced steel, with and without Ca treatment, has been compared with Ti-added steel, produced at 40 kg scale without Ca treatment. The study brings out the influence of centerline segregation and modification of nonmetallic inclusions on HER performance. The microstructural analysis of industrial steel revealed that the method of hole formation (punching/drilling) determines crack initiation mechanism. The inclusions, along with the second phase present in the centerline, drive the crack propagation. An addition of Ti in liquid steel promotes formation of Al-Ti-O-based oxide, prior to MnS precipitation, during solidification and acts as nucleation site for MnS inclusion. This obviates the elongated stringer-type MnS inclusions. The centerline segregation-free Ti-modified steel, prepared at the laboratory scale, showed consistent HER property compared with industrial steel. It is also concluded that calcium treatment can be circumvented by modifying the sulfide stringer with the addition of Ti in the steel for further improvement in HER property.

36 MATERIALS SCIENCE↗

Atomic-scale decoration for improving the pitting corrosion resistance of austenitic stainless steels

Stainless steels are susceptible to the localized pitting corrosion that leads to a huge loss to our society. Studies in the past decades confirmed that the pitting events generally originate from the local dissolution in MnS inclusions which are more or less ubiquitous in stainless steels. Although a recent study indicated that endogenous MnCr 2 O 4 nano-octahedra within the MnS medium give rise to local nano-galvanic cells which are responsible for the preferential dissolution of MnS, effective solutions of restraining the cells from viewpoint of electrochemistry are being tantalizingly searched. Here we report such a galvanic corrosion can be greatly resisted via bathing the steels in Cu 2+ -containing solutions. This chemical bath generates Cu 2–δ S layers on the surfaces of MnS inclusions, invalidating the nano-galvanic cells. Our study provides a low-cost approach via an atomic scale decoration to improve the pitting corrosion resistance of stainless steels in a volume-treated manner.

36 MATERIALS SCIENCE↗