Magnesium alloys containing long period stacking ordered(LPSO) phase have been received a great deal of attention in the last decade owing to their excellent comprehensive properties of mechanical ...strength and corrosion resistance. In this paper, some fundamental aspects of LPSO containing Mg alloys have been reviewed, including:(1) microstructural characterization, formation conditions and the associated phase transformation of LPSO phases in Mg alloys;(2) deformation mechanism of LPSO phases and their in fl uence on the deformation mechanism of the Mg matrix;(3) effect of LPSO structure on the mechanical performance such as tensile strength, creep resistance, fracture toughness and fatigue strength;(4) corrosion behavior of LPSO containing Mg alloys and their possible applications as the biomaterials.Moreover, some remaining unsolved issues of the LPSO containing Mg alloys and the future target about how to further improve their service properties have been also described.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Three factors govern adiabatic shear localization: strain hardening (or softening), strain-rate hardening, and thermal softening. It is typically associated with large shear strains (>1), high strain ...rates (103–107 s−1), and high temperatures (40–100% of melting point), all of which happen within narrow regions with widths of about 1–200 μm.
It is often an undesirable phenomenon, leading to failure, but there are situations where it is desirable, e. g., the generation of machining chips. Here, we review the development of both theoretical and experimental achievements, from the initiation of shear bands to their propagation with emphasis on three aspects: novel experimental techniques, novel materials, and nano/microstructural effects. The principal characteristics of adiabatic shear bands in metallic materials at the nano- and micro-scale are described. Bands that were formerly identified as transformed actually consist of nanocrystalline/ultrafine grains. These grains result from the breakup of the microstructure by a rotational recrystallization process.
The evolution of the microstructure inside shear bands and their interactions for hcp, bcc, and fcc alloys, high-entropy alloys, nanocrystalline alloys, and metallic glasses are analyzed mechanistically.
The gaps in the field and opportunities for future research are identified. Modern experimental characterization and computational techniques enable a more profound and predictive understanding of adiabatic shear localization and its avoidance in advanced materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To investigate the damage threshold and mechanism of a mid-infrared HgCdTe focal plane array (FPA) detector, relevant experimental and theoretical studies were conducted. The line damage threshold of ...a HgCdTe FPA detector may be within the range of 0.59 Jcm
to 0.71 Jcm
. The full frame damage threshold of the detector may be in the range of 0.86 Jcm
to 1.17 Jcm
. Experimental results showed that when the energy density reaches 1.17 Jcm
, the detector exhibits irreversible full frame damage and is completely unable to image. Based on the finite element method, a three-dimensional model of HgCdTe FPAs detector was established to study the heat transfer mechanism, internal stress, and damage sequence. When HgCdTe melts, we think that the detector is damaged. Under these conditions, the theoretical damage threshold calculated using the detector model is 0.55 Jcm
. The difference between theoretical and experimental values was analyzed. The relationship between damage threshold and pulse width was also studied. It was found that when the pulse width is less than 1000 ns, the damage threshold characterized by peak power density is inversely proportional to pulse width. This relationship can help us predict the experimental damage threshold of an FPA detector. This model is reasonable and convenient for studying the damage of FPA detectors with a mid-infrared pulse laser. The research content in this article has important reference significance for the damage and protection of HgCdTe FPA detectors.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Investigations made by the authors and collaborators into the microstructural aspects of adiabatic shear localization are critically reviewed. The materials analyzed are low-carbon steels, 304 ...stainless steel, monocrystalline Fe-Ni-Cr, Ti and its alloys, Al-Li alloys, Zircaloy, copper, and Al/SiC
p
composites. The principal findings are the following: (a) there is a strain-rate-dependent critical strain for the development of shear bands; (b) deformed bands and white-etching bands correspond to different stages of deformation; (c) different slip activities occur in different stages of band development; (d) grain refinement and amorphization occur in shear bands; (e) loss of stress-carrying capability is more closely associated with microdefects rather than with localization of strain; (f) both crystalline rotation and slip play important roles; and (g) band development and band structures are material dependent. Additionally, avenues for new research directions are suggested.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Purpose
Denitrification has been extensively studied in soils from temperate zones in industrialized countries. However, few studies quantifying denitrification rates in soils from tropical and ...subtropical zones have been reported. Denitrification mechanisms in tropical/subtropical soils may be different from other soils due to their unique soil characteristics. The identification of denitrification in the area is crucial to understand the role of denitrification in the global nitrogen (N) cycle in terrestrial ecosystems and in the interaction between global environmental changes and ecosystem responses.
Materials and methods
We review the existing literature on microbially mediated denitrification in tropical/subtropical soils, attempting to provide a better understanding about and new research directions for denitrification in these regions.
Results and discussion
Tropical and subtropical soils might be characterized by generally lower denitrification capacity than temperate soils, with greater variability due to land use and management practices varying temporally and spatially. Factors that influence soil water content and the nature and rate of carbon (C) and N turnover are the landscape-scale and field-scale controls of denitrification. High redox potential in the field, which is mainly attributed to soil oxide enrichment, may be at least one critical edaphic variable responsible for slow denitrification rates in the humid tropical and subtropical soils. However, soil pH is not responsible for these slow denitrification rates. Organic C mineralization is more important than total N content and C/N in determining denitrification capacity in humid subtropical soils. There is increasing evidence that the ecological consequence of denitrification in tropical and subtropical soils may be different from that of temperate zones. Contribution of denitrification in tropical and subtropical regions to the global climate warming should be considered comprehensively since it could affect other greenhouse gases, such as methane (CH
4
) and carbon dioxide (CO
2
), and N deposition.
Conclusions
Tropical/subtropical soils have developed several N conservation strategies to prevent N losses via denitrification from the ecosystems. However, the mechanisms involved in the biogeochemical regulation of tropical and subtropical ecosystem responses to environmental changes are largely unknown. These works are important for accurately modeling denitrification and all other simultaneously operating N transformations.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•This manuscript analyses the dazzling/damage mechanism of InGaAs detectors under 1064 nm continuous laser. Introduced two innovative conceptual models for the dazzling/damage effects of continuous ...laser on InGaAs detectors.•Taking into account both accuracy and computational speed, the single-pixel liquid charge overflow model can calculate the point spread function, which includes scattering and diffraction factors, enabling the simulation of pixel saturation charge.•The damage model not only enables the acquisition of damage effect data but also addresses the challenge of real-time observation of temperature changes and distributions within the detector during experiments.
To investigate the dazzling/damage mechanism of InGaAs detectors by continuous laser, InGaAs detectors irradiated by continuous laser were analyzed theoretically and verified experimentally. Constructing the dazzling model of InGaAs detectors, saturated pixel data at different power levels were obtained. After comparing these data with verified experiments, it was observed that the magnitude and regularity of saturated pixel were relatively consistent at the same power levels. A finite element theoretical model of laser-irradiated InGaAs detectors was designed by Comsol. After calculation, the corresponding laser damage threshold for InGaAs detector was about 9.13 × 105 W/cm2 and 2.63 × 105 W/cm2 for irradiation times of 40 ms and 400 ms, respectively. These values were in relatively good agreement with the experimentally obtained damage thresholds of 1.07 × 106 W/cm2 and 3.95 × 105 W/cm2. The verified experiments confirmed the validity of the simulation methods and the dazzling/damage model employed in this paper. This study serves as a reference for further research on the laser irradiation effects and damage mechanisms of InGaAs detectors, as well as for laser protection and performance optimization in imaging systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The retrograde semi-retrieval technique (RESET) has been described as a modified technique for endovascular thrombectomy (EVT) whose safety and efficacy for intracranial atherosclerosis stenosis ...(ICAS) patients remain uncertain. This article presents our single-center experience, comparing RESET vs. non-RESET in ICAS patients.
We analyzed 327 consecutive ICAS patients who underwent EVT at Tianjin Huanhu Hospital from January 2018 and December 2022. Patients were categorized into two groups: RESET and non-RESET. The primary outcome was the first-pass effect (FPE). Secondary outcomes included successful reperfusion, functional independence at 90 days, mortality, and symptomatic intracranial hemorrhage (sICH).
RESET was significantly associated with FPE adjusted odds ratio (aOR) 2.00, 95% confidence interval (CI) 1.03-3.87,
= 0.040. RESET was not significantly associated with successful reperfusion (aOR 1.5, CI 0.55-4.06,
= 0.425), an mRS of 0-2 at 90 days (aOR 1.36, CI 0.83-2.21,
= 0.223), sICH (aOR 0.39, CI 0.12-1.23,
= 0.108), and mortality (aOR 0.49, CI 0.16-1.44,
= 0.193). After propensity score matching, the results were consistent with the primary analysis.
Compared to non-RESET, patients treated with RESET showed increased FPE incidence and significantly decreased puncture-to-reperfusion time. RESET was proven to be safe and effective in enhancing reperfusion for LVO patients receiving EVT with underlying ICAS.
Thin-walled parts are widely used in shock wave and detonation physics experiments, which require high surface accuracy and equal thickness. In order to obtain the wall thickness of thin-walled ...spherical shell parts accurately, a new measurement method is proposed. The trajectories, including meridian and concentric trajectories, are employed to measure the thickness of thin-walled spherical shell parts. The measurement data of the inner and outer surfaces are unified in the same coordinate system, and the thickness is obtained based on a reconstruction model. The meridian and concentric circles' trajectories are used for measuring a spherical shell with an outer diameter of Φ210.6 mm and an inner diameter of Φ206.4 mm. Without the data in the top area, the surface errors of the outer and inner surfaces are about 5 μm and 6 μm, respectively, and the wall-thickness error is about 8 μm with the meridian trajectory.
The effect of milling time on the microstructural evolution and magnetic properties of Ti50Fe50 alloys prepared by mechanical alloying were investigated. The results showed that the powder size was ...decreased sharply and then stabilized. Correspondingly, the milled powders experienced a transition from the lamellar shape to the spherical shape due to severe plastic deformation as well as the competition of cold welding and fracturing when the milling time was increased. Compared with the detailed composition primary powder (composed of Ti and α-Fe phases), the nanocrystalline Ti and α-Fe phase gradually disappeared and the amorphous phase were formed in the Ti50Fe50 alloys after milling for 40 h. When the milling time was increased to 60–90 h, the nanocrystalline disappeared and the complete amorphization of the milled Ti50Fe50 alloys occurred. However, a small amount of the nanocrystalline TiFe was formed except for a large of amorphous phase in Ti50Fe50 alloys for 100 h. Meanwhile, the formation of paramagnetic amorphous/nanocrystalline Ti and TiFe phase resulted in the saturation magnetization and coercive of the milled Ti50Fe50 alloys were decreased. Therefore, they exhibited excellent soft magnetic (0–90 h) and paramagnetic properties (100 h).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The effect of milling time on the microstructure evolution and soft magnetic properties of Ti50Fe50 alloy produced by mechanical alloying (MA) has been investigated. With the increase of milling ...time, the morphologies of Ti50Fe50 alloys experience a transition from lamellar structure to spherical structure, the α-Fe(Ti) solid solution containing a supersaturated Ti is formed, the grain sizes of Fe and Ti are decreased to nanoscale and their internal microstrains are increased. When the milling time is increased to 20h, the nanocrystalline TiFe intermetallic phase appears and the Ti-rich amorphous phase is formed along with the complete disappearance of crystal Ti phase. Additionally, the saturation magnetization (Ms) of the milled Ti50Fe50 alloys is reduced gradually, while the coercivity (Hc) exhibits an increasing trend. This is attributed to the combination reactions of nanocrystalline, microstrain, grain boundaries, paramagnetic Ti-rich amorphous, paramagnetic nanocrystalline TiFe and ferromagnetic α-Fe(Ti) phases. The magnetic hysteresis loops, the field cooled (FC) and zero field cooled (ZFC) curves confirm that the amorphous/nanocrystalline Ti50Fe50 alloys produced by MA can sever as excellent soft magnetic materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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