Many established, but also potential future applications of NiTi-based shape memory alloys (SMA) in biomedical devices and solid-state refrigeration require long fatigue life with 10
-10
duty cycles
.... However, improving the fatigue resistance of NiTi often compromises other mechanical and functional properties
. Existing efforts to improve the fatigue resistance of SMA include composition control for coherent phase boundaries
and microstructure control such as precipitation
and grain-size reduction
. Here, we extend the strategy to the nanoscale and improve fatigue resistance of NiTi via a hybrid heterogenous nanostructure. We produced a superelastic NiTi nanocomposite with crystalline and amorphous phases via severe plastic deformation and low-temperature annealing. The as-produced nanocomposite possesses a recoverable strain of 4.3% and a yield strength of 2.3 GPa. In cyclic compression experiments, the nanostructured NiTi micropillars endure over 10
reversible-phase-transition cycles under a stress of 1.8 GPa. We attribute the enhanced properties to the mutual strengthening of nanosized amorphous and crystalline phases where the amorphous phase suppresses dislocation slip in the crystalline phase while the crystalline phase hinders shear band propagation in the amorphous phase. The synergy of the properties of crystalline and amorphous phases at the nanoscale could be an effective method to improve fatigue resistance and strength of SMA.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
An easily prepared platinum nanoparticle (PtNP) probe for the sensitive and selective detection of Hg2+ ions is developed here. The PtNPs with an average size of approximately 2.5 nm were prepared by ...a reduction method with sodium borohydride and trisodium citrate serving as reductant and stabilizer, respectively. The resulting PtNPs could catalyze the reduction of Hg2+ by surface-capping citrate. The effect of Hg2+ uptake implies amalgam formation, which leads to remarkable inhibition of the peroxidase-like activity of citrate-capped PtNPs. On the basis of this effect, a colorimetric mercury sensor was established through the use of citrate-capped PtNPs to catalyze the colorimetric system of 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2. The high specificity of the Hg–Pt interaction provides the excellent selectivity for Hg2+ over interfering metal ions. The sensitivity of this smart probe to Hg2+ is extremely excellent with a limit of detection (LOD) as low as 8.5 pM. In view of these advantages, as well as the cost-effectiveness, minimized working steps, and naked-eye observation, we expect that this colorimetric sensor will be a promising candidate for the field detection of toxic Hg2+ ions in environmental, biological, and food samples.
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IJS, KILJ, NUK, PNG, UL, UM
Low impact development (LID) is generally regarded as a more sustainable solution for urban stormwater management than conventional urban drainage systems. However, its effects on urban flooding at a ...scale of urban drainage systems have not been fully understood particularly when different rainfall characteristics are considered. In this paper, using an urbanizing catchment in China as a case study, the effects of three LID techniques (swale, permeable pavement and green roof) on urban flooding are analyzed and compared with the conventional drainage system design. A range of storm events with different rainfall amounts, durations and locations of peak intensity are considered for holistic assessment of the LID techniques. The effects are measured by the total flood volume reduction during a storm event compared to the conventional drainage system design. The results obtained indicate that all three LID scenarios are more effective in flood reduction during heavier and shorter storm events. Their performance, however, varies significantly according to the location of peak intensity. That is, swales perform best during a storm event with an early peak, permeable pavements perform best with a middle peak, and green roofs perform best with a late peak, respectively. The trends of flood reduction can be explained using a newly proposed water balance method, i.e., by comparing the effective storage depth of the LID designs with the accumulative rainfall amounts at the beginning and end of flooding in the conventional drainage system. This paper provides an insight into the performance of LID designs under different rainfall characteristics, which is essential for effective urban flood management.
•Effects of swales, permeable pavements and green roofs on urban flooding are analyzed.•They are more effective in flood reduction during heavier and shorter storm events.•Their performance varies significantly according to the location of storm peak.•The trends of flood reduction can be explained by a proposed water balance method.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
AbstractThis paper presents an approach for evaluating concrete cracking growth and structural resistance deterioration due to reinforcement corrosion and for predicting future structural performance ...during the service life of the corroded concrete beams. The evolution of corrosion-induced concrete cracking is analytically predicted and then adopted for estimating the residual bond strength of the corroded steel rebar. The flexural capacity deterioration of a corroded concrete beam is accurately determined with consideration of rebar cross-section loss, yielding strength reduction and bond strength degradation caused by reinforcement corrosion. The concrete cracking growth and flexural capacity deterioration rates are chosen as random variables for modeling structural performance deterioration over time during the life cycle. The gamma process is then used for time-dependent stochastic deterioration modeling and the remaining life estimate of the corroded concrete beams. The results for the worked example show that the proposed approach can provide reliable predictions for concrete crack development and structural strength deterioration, and also give an effective method for lifetime performance assessment of the corroded concrete structures.
In this paper, via closure (resp. interior) operators on a bounded lattice L, we propose a rather effective method to construct uninorms on L with a given triangular norm T (resp. triangular conorm ...S) on the subinterval 0,e (resp. e,1) of L. Our method encompasses as special cases the construction methods introduced by F. Karaçal and R. Mesiar (2015) 16 as well as by G.D. Çaylı et al. (2016) 5. We also exploit a pair of novel closure and interior operators on complete lattices and utilize this pair of operators to construct uninorms. Several interesting examples are included to illustrate our method.
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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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•Impedance matching by simultaneous magnetism and conductivity within single MOF.•Simple, facile and environment-friendly microwave solvothermal preparation method.•Significant ...improvement of absorbing performance by adjusting reaction temperature.•Superior absorption (−73.5 dB, 3 mm-thickness) than former MOF-based porous carbons.•High-efficiency, lightweight and tunable microwave absorber.
The excellent properties including high porosity, large specific surface area, low density, and strong controllability of metal–organic frameworks (MOFs) make them one of the preferred materials for a plethora of applications. One particular intriguing application, among others, is microwave absorption, to which majority of research has been devoted by using MOF as templates to prepare porous carbon via carbonization. Contrary to such approach, in this study we propose a novel strategy based on leveraging the intrinsic attributes of MOF. Through a simple and rapid microwave solvothermal method, lamellar redox-active iron-quinoid MOFs were synthesized and their morphology and crystallinity are modulated as a function of reaction temperature. The conductivity of the prepared MOF reached up to 2 × 10−3 S/m, which is comparable to that of semiconductors. In addition, magnetic hysteresis was observed at 300 K. The reaction temperature proved pivotal to attain maximum microwave absorption of −73.5 dB at 13.8 GHz with a matching thickness of 3.3 mm. Effective absorbing bandwidth with a reflection loss below −10 dB can be also gained in a wide frequency range of 9.8–15.9 GHz. The optimal microwave absorbing performance was mainly attributed to the simultaneous implementation of magnetic and electrical loss in a single iron-quinoid MOF resulting in adequate impedance matching through modulable magnetic and electric properties. The developed iron-quinoid MOF material opens up new opportunities to achieve high-efficiency, lightweight and tunable microwave absorbers. The material-structure coupling strategy here is instrumental to developing next-generation high-performance microwave absorbing materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The development of lightweight composites with desirable thermo‐mechanical properties is progressively increasing. Phthalonitrile (PN) based composites have shown great potential in this regard. ...However, the basic thermal properties of PN composites required for engineering design are not yet fully understood. In this work, we investigated the thermal stability, thermal expansion behavior and thermal conductivity of PN composites reinforced with carbon fiber (CF) and high silicon fiberglass (HSF) via combined experimental studies and numerical simulations. The results indicated that CF/PN performs better in thermostability than HSF/PN at temperatures below 500°C. Moreover, the incorporation of CF and HSF lowered the coefficient of thermal expansion (CTE) and thermal insulation of PN. At room temperature, the in‐plane CTE of CF/PN and HSF/PN were 1.97E‐6 and 9.24E‐6°C−1, respectively, while the out‐plane thermal conductivities of CF/PN and HSF/PN were 0.65 and 0.34 W/(m K). It is worth noting that an excessively high fiber volume fraction would lead to poor thermal insulation and lightweight properties of the PN composites, while a low fiber volume fraction would result in poor stiffness and thermal dimensional stability. Determined via TOPSIS model, a fiber volume fraction range of 50%–60% was ideal for both composites with comprehensive optimal properties, respectively.
Preparation and simulation of PN composites.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Magnesium, the lightest structural metal, usually exhibits limited ambient plasticity when compressed along its crystallographic c-axis (the "hard" orientation of magnesium). Here we report large ...plasticity in c-axis compression of submicron magnesium single crystal achieved by a dual-stage deformation. We show that when the plastic flow gradually strain-hardens the magnesium crystal to gigapascal level, at which point dislocation mediated plasticity is nearly exhausted, the sample instantly pancakes without fracture, accompanying a conversion of the initial single crystal into multiple grains that roughly share a common rotation axis. Atomic-scale characterization, crystallographic analyses and molecular dynamics simulations indicate that the new grains can form via transformation of pyramidal to basal planes. We categorize this grain formation as "deformation graining". The formation of new grains rejuvenates massive dislocation slip and deformation twinning to enable large plastic strains.
Background and Aims
Hepatic ischemia‐reperfusion (I/R) injury, which mainly involves inflammatory responses and apoptosis, is a common cause of organ dysfunction in liver transplantation (LT). As a ...critical mediator of inflammation and apoptosis in various cell types, the role of tripartite motif‐containing (TRIM) 27 in hepatic I/R injury remains worthy of study.
Approach and Results
This study systemically evaluated the putative role of TRIM27/transforming growth factor β–activated kinase 1 (TAK1)/JNK (c‐Jun N‐terminal kinase)/p38 signaling in hepatic I/R injury. TRIM27 expression was significantly down‐regulated in liver tissue from LT patients, mice subjected to hepatic I/R surgery, and hepatocytes challenged by hypoxia/reoxygenation (H/R) treatment. Subsequently, using global Trim27 knockout mice (Trim27‐KO mice) and hepatocyte‐specific Trim27 transgenic mice (Trim27‐HTG mice), TRIM27 functions to ameliorate liver damage, reduce the inflammatory response, and prevent cell apoptosis. In parallel in vitro studies, activating TRIM27 also prevented H/R‐induced hepatocyte inflammation and apoptosis. Mechanistically, TRIM27 constitutively interacted with the critical components, TAK1 and TAK1 binding protein 2/3 (TAB2/3), and promoted the degradation of TAB2/3, leading to inactivation of TAK1 and the subsequent suppression of downstream JNK/p38 signaling.
Conclusions
TRIM27 is a key regulator of hepatic I/R injury by mediating the degradation of TAB2/3 and suppression of downstream TAK1‐JNK/p38 signaling. TRIM27 may be a promising approach to protect the liver against I/R‐mediated hepatocellular damage in transplant recipients.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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