Material tests of 316L austenitic stainless-clad steel at elevated temperatures

[EN] Mechanical properties of stainless-clad (SC) steel plates at elevated temperatures are key parameters for fire resistant design and numerical simulation analysis of SC steel structures. Compared with pure stainless steel and pure ordinary steel, SC steel not only combines advantages of the two component metals, but may also balance the performance and cost; however, it behaves quite differently in terms of material properties. In order to quantify this performance, tension coupon tests at room as well as elevated temperatures are conducted on the SC steel plate. Based on the test results, failure modes of the tension coupons are analysed, and full-range stress-strain curves are obtained; material properties are accordingly determined and described herein, and analyses are performed on several properties including yield strength, ultimate tensile stress, elastic modulus and elongation after fracture. It is found that with an increase of the temperature, both the elastic modulus and strengths are reduced remarkably. For determining these material properties quantitatively and developing robust constitutive models of the SC steel at elevated temperatures, more test data are needed, and the incorporation of the effects of the clad ratio on the material properties at both room and elevated temperatures is also necessary. The present research outcomes may provide valuable reference for fire design and calculations of the SC steel.This work was financially supported by the National Natural Science Foundation of China (Nos. 51608300, 51778329), which are gratefully acknowledged.Bai, R.; Ban, H.; Chung, K.; Bai, Y. (2018). Material tests of 316L austenitic stainless-clad steel at elevated temperatures. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 851-855. https://doi.org/10.4995/ASCCS2018.2018.7011OCS85185

Research progress on material properties of clad steel

[EN] Clad steel possesses benefits of the both component metals in terms of mechanical performance, corrosion resistance, sustainability and lower full lifecycle cost, etc. As a result, it has been more and more widely used in the petroleum, chemical, marine, shipbuilding and metallurgical industries, including stainless-clad steel and titanium clad steel. Such clad steel has also great potential for application in building and bridge structures. For better understanding material properties of such clad steel, a review of research progress available in the literature is conducted herein, as well as recent research undertaken by the authors’ group at Tsinghua University. It can be found that very limited research reported in the literature mainly concerns static material properties of the clad steel, and primary relations between clad ratio and strength are suggested. The authors carried out material tests on both titanium and stainless-clad steel plates, with different clad ratios being incorporated. For the stainless-clad steel tests, both material and butt welded connections are tested, and various elevated temperatures are considered. In addition, tension coupon tests under cyclic loadings are also briefly introduced herein. Primary constitutive relations developed by the authors are reviewed in this paper. All the research findings and proposed formulae may provide an essential basis for future structural analysis, and may promote its application in structural engineering.This work was financially supported by the National Natural Science Foundation of China (Nos. 51778329, 51608300), which are gratefully acknowledged.Ban, H.; Bai, R.; Chung, K.; Zhu, J.; Bai, Y. (2018). Research progress on material properties of clad steel. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 653-658. https://doi.org/10.4995/ASCCS2018.2018.7010OCS65365

gCAPjoint, A Software Package for Full Moment Tensor Inversion of Moderately Strong Earthquakes with Local and Teleseismic Waveforms

Earthquake moment tensors and focal depths are crucial to assessing seismic hazards and studying active tectonic and volcanic processes. Although less powerful than strong earthquakes (M 7+), moderately strong earthquakes (M 5–6.5) occur more frequently and extensively, which can cause severe damages in populated areas. The inversion of moment tensors is usually affected by insufficient local waveform data (epicentral distance <5°⁠) in sparse seismic networks. It would be necessary to combine local and teleseismic data (epicentral distance 30°–90°) for a joint inversion. In this study, we present the generalized cut‐and‐paste joint (gCAPjoint) algorithm to jointly invert full moment tensor and centroid depth with local and teleseismic broadband waveforms. To demonstrate the effectiveness and explore the limitations of this algorithm, we perform case studies on three earthquakes with different tectonic settings and source properties. Comparison of our results with global centroid moment tensor and other catalog solutions illustrates that both non‐double‐couple compositions of the focal mechanisms and centroid depths can be reliably recovered for very shallow (⁠<10  km⁠) earthquakes and intermediate‐depth events with this software package

Structural insights into Ca2+-activated long-range allosteric channel gating of RyR1

Ryanodine receptors (RyRs) are a class of giant ion channels with molecular mass over 2.2 mega-Daltons. These channels mediate calcium signaling in a variety of cells. Since more than 80% of the RyR protein is folded into the cytoplasmic assembly and the remaining residues form the transmembrane domain, it has been hypothesized that the activation and regulation of RyR channels occur through an as yet uncharacterized long-range allosteric mechanism. Here we report the characterization of a Ca2+-activated open-state RyR1 structure by cryo-electron microscopy. The structure has an overall resolution of 4.9 angstrom and a resolution of 4.2 angstrom for the core region. In comparison with the previously determined apo/closed-state structure, we observed long-range allosteric gating of the channel upon Ca2+ activation. In-depth structural analyses elucidated a novel channel-gating mechanism and a novel ion selectivity mechanism of RyR1. Our work not only provides structural insights into the molecular mechanisms of channel gating and regulation of RyRs, but also sheds light on structural basis for channel-gating and ion selectivity mechanisms for the six-transmembrane-helix cation channel family.Strategic Priority Research Program of Chinese Academy of Sciences [XDB08030202]; National Basic Research Program (973 Program); Ministry of Science &amp; Technology of China [2012CB917200, 2014CB910700]; National Natural Science Foundation of China [31270768]; Ministry of Education of China (111 Program China)SCI(E)PubMed中国科技核心期刊(ISTIC)[email protected]; [email protected]

Neuroanatomical Circuitry Associated with Exploratory Eye Movement in Schizophrenia: A Voxel-Based Morphometric Study

Schizophrenic patients present abnormalities in a variety of eye movement tasks. Exploratory eye movement (EEM) dysfunction appears to be particularly specific to schizophrenia. However, the underlying mechanisms of EEM dysfunction in schizophrenia are not clearly understood. To assess the potential neuroanatomical substrates of EEM, we recorded EEM performance and conducted a voxel-based morphometric analysis of gray matter in 33 schizophrenic patients and 29 well matched healthy controls. In schizophrenic patients, decreased responsive search score (RSS) and widespread gray matter density (GMD) reductions were observed. Moreover, the RSS was positively correlated with GMD in distributed brain regions in schizophrenic patients. Furthermore, in schizophrenic patients, some brain regions with neuroanatomical deficits overlapped with some ones associated with RSS. These brain regions constituted an occipito-tempro-frontal circuitry involved in visual information processing and eye movement control, including the left calcarine cortex [Brodmann area (BA) 17], the left cuneus (BA 18), the left superior occipital cortex (BA 18/19), the left superior frontal gyrus (BA 6), the left cerebellum, the right lingual cortex (BA 17/18), the right middle occipital cortex (BA19), the right inferior temporal cortex (BA 37), the right dorsolateral prefrontal cortex (BA 46) and bilateral precentral gyri (BA 6) extending to the frontal eye fields (FEF, BA 8). To our knowledge, we firstly reported empirical evidence that gray matter loss in the occipito-tempro-frontal neuroanatomical circuitry of visual processing system was associated with EEM performance in schizophrenia, which may be helpful for the future effort to reveal the underlying neural mechanisms for EEM disturbances in schizophrenia

Titanium-rich TS-1 zeolite for highly efficient oxidative desulfurization

The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions. Herein, we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1 (MFI) zeolites by replacing tetrabutyl orthotitanate (TBOT) with tetrabutyl orthotitanate tetramer (TBOT-tetramer) as the titanium source. The introduced TBOT-tetramer slowed down the zeolite crystallization process, and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species. Notably, the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40. The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area. It also impeded the formation of anatase species, resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT

Titanium-rich TS-1 zeolite for highly efficient oxidative desulfurization

The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions. Herein, we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1 (MFI) zeolites by replacing tetrabutyl orthotitanate (TBOT) with tetrabutyl orthotitanate tetramer (TBOT-tetramer) as the titanium source. The introduced TBOT-tetramer slowed down the zeolite crystallization process, and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species. Notably, the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40. The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area. It also impeded the formation of anatase species, resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.The authors thank the National Natural Science Foundation of China, China (Grant 21920102005, 21621001, and 21835002), the 111 Project, China (B17020), the European Union through the European Research Council, European Union (grant ERC-AdG-2014-671093, SynCatMatch), and the Spanish Government through “Severo Ochoa”, Spain (SEV-2016-0683, MINECO) for supporting this work. R. Bai acknowledges the financial support from China Scholarship Council, China.Peer reviewe

Area-Selective Atomic Layer Deposition of Metal Oxides on DNA Nanostructures and its Applications

We demonstrate area-selective atomic layer deposition (ALD) of oxides on DNA nanostructures. Area-selective ALD of Al2O3, TiO2, and HfO2 was successfully achieved on both 2D and 3D DNA nanostructures deposited on a polystyrene (PS) substrate. The resulting DNA-inorganic hybrid structure was used as a hard mask to achieve deep etching of a Si wafer for antireflection applications. ALD is a widely used process in coating and thin film deposition; our work points to a way to pattern oxide materials using DNA templates and to enhance the chemical/physical stability of DNA nanostructures for applications in surface engineering

Switching between classical/nonclassical crystallization pathways of TS-1 zeolite: implication on titanium distribution and catalysis

In the MFI zeolite crystallization process, the classical crystallization mechanism based upon the addition of silica species is often concomitant with the nonclassical route that is characteristic of the attachment of silica nanoparticle precursors. However, the factors that govern the preferences for each mechanism remain unclear. In this work, we present the impact of switching between these two crystallization pathways on the active sites and the resulting catalytic performance of the titanosilicate TS-1 zeolite. By controlling the self-assembled precursor structures in the early crystallization stage which are mediated by the Ti and H2O in the reaction system, we could achieve the preferred modes of crystal growth of the TS-1 zeolite. We indicate that by directing the predominant crystallization path from the classical to the nonclassical route, it is possible to generate more stable bridging peroxo species upon reaction with hydrogen peroxide, as confirmed by O-17 solid-state nuclear magnetic resonance spectroscopy, thus substantially increasing the catalytic performance of the resulting TS-1 for olefin epoxidation.ISSN:2041-6520ISSN:2041-653