Abstract
H-H binding energies in tetragonal and octahedral sites (TS & OS) of
α
-Fe lattice were calculated by density functional theory (DFT) under correction of elastic energy. Strong attractive ...interactions were identified as H atoms were incorporated in 3rd and 4th nearest OS neighbors. OS-type H-aggregated clusters with binding energies exceeding 200 meV were identified. Monte Carlo simulation of H-loading indicates abnormal H-aggregation behavior around a 1/2111
(
10
1
¯
)
edge dislocation in relation with the enhanced H-H binding specifically in OS of
α
-Fe lattice.
Wearable pressure sensors are crucial for real-time monitoring of human activities and biomimetic robot status. Here, the ultrasensitive pressure sensor sponge is prepared by a facile method, ...realizing ultrasensitive pressure sensing for wearable health monitoring. Since the liquid metal in the sponge-skeleton structure under pressure is conducive to adjust the contact area with nitrogen-doped graphene nanosheets and thus facilitates the charge transfer at the interface, such sensors exhibit a fast response and recovery speed with the response/recovery time 0.41/0.12 s and a comprehensive response range with a sensitivity of up to 476 KPa–1. Notably, the liquid metal-based spongy pressure sensor can accurately monitor the human body’s pulse, the pressure on the skin, throat swallowing, and other activities in real time, demonstrating a broad application prospect. Those results provide a convenient and low-cost way to fabricate easily perceptible pressure sensors, expanded the application potential of liquid metal-based composites for future electronic skin development.
A enchanced surface plasmon resonance (SPR) biosensor system was developed using magnetic nanoparticles (MNPs) as amplifying element for the determination of estradiol (E2) based on indirect ...competition method.
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•Surface plasmon resonance (SPR) biosensor was developed for the determination of estradiol (E2).•Chitosan on the sensor chip surface significantly improved the performance and stability of the immobilized E2-BSA.•Magnetic nanoparticles (MNPs) as signal amplification material improved the detection sensitivity.•The milk sample was dealed in simple pretreatment.
An enhanced surface plasmon resonance (SPR) biosensor system using magnetic nanoparticles as amplifying element was developed for the real-time determination of estradiol (E2) based on indirect competition method. The anti-estradiol monoclonal antibody (E2-mAb) was conjugated with the magnetic nanoparticles (MNPs) via protein A for signal amplification to improve the detection sensitivity. The chitosan, spin-coated on the sensor chip surface, was used to immobilize the antigen (E2-BSA) by glutaraldehyde. The chitosan could significantly improve the performance and stability of the immobilized E2-BSA. During the detection, E2-BSA competed with E2 in samples for binding with the E2-mAb-MNPs conjugates. Then the SPR response decreased in the presence of E2 because E2 prevented the combination of E2-mAb-MNPs conjugates and E2-BSA. In other words, the response of SPR sensor was inversely proportional to E2 concentration. Assay parameters, such as the amount of antibody and MNPs, the amount of immobilized E2-BSA and E2-mAb-MNPs concentration, were optimized in detail and E2-spiked milk samples were detected. A good linear relationship was obtained between inhibition and lgC(E2) ranging from 1.95 to 2000ng/mL and the limit of detection (LOD) was 0.81ng/mL. The result implied that the detection sensitivity was improved compared with the traditionnal sensor without magnetic nanoparticles. Meanwhile, an ELISA method was conducted to detect E2 in milk as comparation with the enhanced SPR method, and the results indicated that these two methods had good consistency. The present study demonstrated a presumable general way and the enhanced sensors possessed a promising application for detection of various kinds of small molecules.
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•A dense CrN layer with excellent oxidation resistance was deposited on Zircaloy.•The steam oxidation mechanism of CrN coating at 1000 ℃ and 1200 ℃ was discussed.•The internal ...oxidation of Zr inside the nitride coating was observed.•The nitrogen diffusion behaviors in CrN coating at high temperature were studied.•A ZrN nano-twins layer formed at the coating/substrate interface after oxidation.
CrN-coated Zircaloy samples were prepared by cathodic arc ion plating, and the microstructure, stability, and oxidation behaviors of the CrN coatings in high-temperature steams were comprehensively investigated. The CrN coating significantly increased the oxidation resistance of Zircaloy exposed to steam through the formation of a dense Cr2O3 oxide layer without cracking or spallation. Two different multi-layered coatings were produced after the steam exposures. The nitrogen diffusion properties of the CrN coatings during oxidation were examined. The internal oxidation of Zr particles inside the nitride coating was observed. A ZrN nano-twinned layer formed at the coating/substrate interface.
The isothermal oxidation behavior of the Cr-coated Zircaloy-4 at 1200 °C in steam is comprehensively investigated. Oxidation kinetics transition is observed when outward diffusion of Zr and ...precipitation of ZrO2 along the Cr coating grain boundaries are reaching the Cr2O3/Cr interface. The outward diffused Zr reduces the Cr2O3 scale to Cr. Pores form on the Cr2O3/Cr interface and inside the Cr2O3 scale after transition. These interfacial pores affect the oxidation mechanism of the Cr-coated Zry-4. The coating failure and the oxidation of the Zry-4 substrate occur when the thickness of the outer Cr2O3 scale decreases to a certain value.
•Four stages in the oxidation of the Cr-coated Zry-4 were studied and discussed.•The Cr2O3 reduction and the formation of ZrO2 in coating cause coating degradation.•Transition occurs when Zr in Cr coating diffuses outward to the Cr2O3/Cr interface.•The reaction between the outward diffused Zr and Cr2O3 reduces the Cr2O3 scale.•Pores form at the Cr2O3/Cr interface and inside the Cr2O3 scale after transition.
•Sn precipitated in Cr2O3 layer after steam oxidation of Cr-coated Zry-4 at 1000 ℃.•The outward diffusion and selective oxidation of Zr in Cr layer were studied.•Larger outward mass flow caused in ...Kirkendall cavities close to Zr/ZrCr2 interface.•Voids formed at oxide/metal interface of coating due to vacancy condensation.•Amorphization of Cr2O3 was observed which due to the decomposition of Cr2O3 grains.
In this study, the steam oxidation behavior of Cr-coated Zry-4 alloy at 1000 °C and the various interesting phenomena observed during the oxidation process were investigated. During oxidation, Sn in the Zry-4 substrate diffused into the coating and precipitated in the Cr2O3 scale. The Kirkendall effect of these Sn-containing precipitates then generated microcavities. Furthermore, the outward diffusion behavior of Zr and the selective oxidation mechanism of the Zr particles were studied. Voids detected at the Cr2O3/Cr interface result mainly from vacancy condensation. The amorphization of Cr2O3 was also observed adjacent to the voids, and the amorphization mechanism was discussed.
It is generally believed that the H-induced reduction in dislocation energy plays a key role in modifying dislocation behaviors in the process of hydrogen embrittlement. Here, we examine the factors ...that lead to H reducing the line energies of the edge and screw dislocations in bcc Fe by atomistic simulations. Grand canonical Monte Carlo simulations are conducted to obtain the distribution of H around the dislocations. We find that H mainly aggregates at the dislocation cores and the H concentration in the elastic field of dislocations is extremely low. The direct consequences of such a distribution pattern of H are as follows. (i) In contrast with previous studies, H induces no change in the shear modulus of the systems containing dislocations. (ii) H increases the core radii and decreases the core energies of the dislocations, which are the only factors leading to the reduction of dislocation line energy by H. (iii) H brings little effect on the stress field of either the edge or screw dislocation, implying that H induces almost no stress-shielding effect on dislocations. A linear relation between the critical shear stress for homogeneous dislocation nucleation and logarithmic bulk H concentration is thus revealed, based on the atomistic result of the H-induced increase in the core radius and decrease in the core energy of the dislocations. The present results indicate that the dislocation-dislocation interaction in the presence of H, which is the key ingredient for the H-enhanced localized plasticity mechanism for hydrogen embrittlement, can be easily evaluated by the linear elastic theory of dislocations if the core radius and energy of dislocations are properly described.
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•The dense CrAlN and CrAlSiN coatings with Cr interlayer were deposited on the Zircaloy samples by multi-arc ion plating.•The oxidation resistance of Zircaloy samples in high-temperature steam was ...effectively improved by surface coating.•The oxidation behaviors and mechanisms of two types of coatings in 1000 °C and 1200 °C steam were studied and discussed.•The distribution and diffusion behaviors of nitrogen bubbles in two types of coatings during oxidation were studied.•The added silicon in the CrAlSiN coating can improve the corrosion resistance but impact the structural integrity of coating.
CrAlN and CrAlSiN coatings were deposited on Zircaloy samples by multi-arc ion plating (MAIP) and the microstructure, hardness, and oxidation resistance of the two types of coatings in high-temperature steams were investigated. The coatings can effectively protect the substrate from oxidation during exposure in 1000 °C steam for 2 h and can delay the oxidation of substrate for more than 15 min in 1200 °C steam. Mixed oxide layers formed and suppressed the elemental diffusion during oxidation. Nitrogen bubbles were found inside the mixed oxide. The CrAlSiN coatings showed better oxidation resistance but they cracked more easily.
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