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This paper studies the dynamic contact response of a piezoelectric half-space under the action of an insulating elastic spherical punch. By means of the perturbation method, the dynamic contact pressure distribution is deduced. Utilizing Hankel transform, the dynamic contact displacement is obtained. Combining the elastic spherical punch oscillation and the piezoelectric half-space motion through contact-displacement boundary conditions, the resonant frequency shift of the elastic sphere is derived. Numerical calculations are given to discuss the influences of the material constant, piezoelectric effect, internal friction and static force on the dynamic contact pressure and resonance frequency shift. The results show that the difference between the dynamic and static contact pressures is small at the center of the contact region, while it is large near the edge of the contact region.

The remarkable architecture of nanoparticles with anisotropy or hierarchically multicavity mesoporous structure is critical for multifunctional application. However, it is still a great challenge to simultaneously tailor their composition, external morphology and interior structure. Herein, an emulsion-induced interfacial self-assembly strategy has been developed for the first time to fabricate mesoporous carbon@mesoporous silica nanoparticles (MC@MSs) with manipulatable morphology from hollow rambutan-like nanospheres to hollow bowl-like MC@MSs (HBMC@MSs) with different concave degree and surface roughness. Impressively, the cavity number and location of MC@MSs can be modulated, i.e., the evolution of internal structure can be transformed from hollow to multicavity and flower-like by varying the solution polarity of primary emulsion, which is a great breakthrough. A novel swelling-double penetration mechanism is proposed to shed light on the growth kinetics of multimorphology nanoparticles. Moreover, the multifunctional platforms ingeniously overcome three disadvantages: (1) the agglomeration during high-temperature annealing process; (2) low biocompatibility caused by high hydrophobicity; (3) poor affinity with hydrophobic drug molecules. Noticeably, the cellular uptake property of HBMC@MSs with red blood cell biomimetic morphology is more favorable than that of spherical nanoparticles. This strategy endows new understanding of fabricating well-defined MC@MSs and rationally designing the nanomedicine carrier for efficient delivery.

To investigate the risk factors and outcomes regarding acute kidney injury (AKI) after AngioJet thrombectomy for acute lower-extremity deep vein thrombosis (DVT).Patients were divided into AKI and non-AKI groups according to whether AKI occurred postoperatively. The demographic data, pre-operative and post-operative laboratory data and surgical differences were compared between the two groups. Logistic regression and Wilcoxon signed-rank test were used to identify the AKI risk factors and outcomes, respectively.Among the 341 patients who met the inclusion criteria, 45 developed AKI (AKI group) and 296 had normal renal function (non-AKI group) post-surgery. There were significant differences between the two groups in the course (t = 10.885, P = 0.000); preoperative history of a major surgery within 3 months (3M-MS) (odds ratio [OR] = 5.492, P = 0.001); duration of aspiration thrombectomy (Z = -8.803, P = 0.000); volumes of aspiration (Z = -8.215, P = 0.000); contrast volume (Z = -3.204, P = 0.001) and pulmonary thrombectomy (OR = 18.200, P = 0.002); and preoperative complications of hypertension (OR = 4.637, P = 0.002), diabetes (OR = 18.088, P = 0.000), or pulmonary embolism (OR = 0.085, P = 0.011). Wilcoxon signed-rank test showed that the renal function of every patient in the AKI group returned to normal 3 months after the surgery.The course, preoperative complications of diabetes or hypertension, 3M-MS, contrast volume, duration and volume of aspiration thrombectomy, and pulmonary thrombectomy are risk factors for post-AngioJet-thrombectomy AKI, which is temporary.

Based on the perturbation method, axisymmetric contact vibration of a rigid spherical punch on a piezoelectric half-space is studied in this paper. It is assumed that the rigid punch is a perfect insulating body with zero electric charge distribution. A compressive force composed of a static force and a time-harmonic force is applied to the spherical punch normally on the top of the surface. The variable contact radius and contact pressure are caused at the contact region for this dynamic contact problem. With the aid of Hankel integral transform technique, the dynamic contact model is established and the dynamic contact stiffness is derived from different contact displacement conditions, including two-point and one-point displacement conditions. Numerical examples are provided to show the effects of the oscillating frequency, contact displacement condition, internal friction, piezoelectric effect and material constants on the dynamic contact stiffness.

As a promising commercial hydrogen-rich gas turbine combustion technology, micro-mixing combustion has been characterized for its excellent performance with low NOx emissions. New flame stabilization mechanism of micro-mixing flames may produce new design criteria. In order to explore that, cold flow characteristics of a novel Micromix model burner based on multiple confluent round jets has been studied experimentally and numerically, which is considered to be the basis for the exploration. A three-dimensional laser Doppler velocimetry system (3D-LDV) was used to measure the flow field of the model burner. It was found that the cold flow characteristics of the burner were different from the twin plane jets, the twin round jets, and the low Reynolds number confluent round jets. Compared to which, the interior of the micro-mixing nozzle is at a very high turbulence intensity level, and the jets merging point of the burner moved upstream; however, the position of the combined point of the burner was close to the confluent round jets. There is no recirculation region between jets near the burner outlet when the nozzle spacing was equal to 3 times the nozzle diameter and the Reynolds number was less than 16,702. The steady computational Reynolds averaged equations (RANS) model results were used to compare with the experimental results. It was found that the RANS results can match the experimental results well, and the three RANS models predict the spatial mixing deficiency less than 1% at the outlet, indicating that the fuel and air were almost completely premixed uniformly.

The genome-wide DNA methylation assay was used to analyze the difference in methylation between the breeding and conservation populations of Shaoxing ducks. The methylation level of the breeding population was higher than that of the two conservation populations, and the proportion of CG methylation sites was the largest in the three populations, most of the methylation sites were located in the exon region. There were 1247 different methylation regions in the two populations (group A and B), and 927 different methylation regions in the two groups (group A and group C). The differential methylation regions of the three groups were evenly distributed in the gene and intergene regions. GO and KEGG enrichment analysis showed that the differentially expressed genes in the A and B groups were mainly involved in synaptic and cell connections and the signaling pathways were significantly enriched in cAMP and oxytocin signaling pathways. The results showed that the group C was significantly enriched in eight signaling pathways, including the cAMP signaling pathway and long-term enhancement, compared to the group A. There were thirty-five differentially methylated genes, including

In-situ spheroidal graphene film (SGF) may be a hopeful candidate of sensor matrix for space exploration. A poor understanding of the influence of interfacial layer on graphene structure restricts its benefit fulfillment. In this work, the SGF was in-situ grown on a cemented carbide substrate, and its influence on the graphene structure was investigated. An amorphous silicon carbide (a-SiC) layer was deposited on the carbide substrate by magnetron sputtering catalyzed by Co, a binding phase of carbide substrate, to form SGF under thermal annealing at 1000 °C. The influence of the interfacial layer on the graphene structure was investigated as a function of annealing time. As a result, the phase of the interfacial layer is a critical factor affecting the formation and structure of SGF. As the annealing time increases, the interfacial phase is transformed from CoSi to Co2Si, and then a pure Co2Si particles layer is formed. The C atoms, attached to the Co2Si particles, gather thereon and form the SGF. When the interfacial phase is a mixture of CoSi and Co2Si, multilayer graphene comprising many defects is formed. A bilayer graphene is obtained when the interfacial layer is composed of pure Co2Si.

Integrating high electrocatalytic activities for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) into one nonprecious catalyst entity is highly desired for simplifying the fabrication, operation as well as lowering the production cost of rechargeable Zn-air batteries. Herein, zeolite imidazole framework-67 (ZIF-67) polyhedron nanocrystals are used as N-containing carbonaceous precursors to synthesize N-rich hollow carbon cage composites with Co nanoparticles (Co@NHCC) in the presence of silica nanoparticles and graphitic carbon nitride (g-C3N4), an additional high-temperature decomposable nitrogen source. The assembly of dense silica nanoparticles on ZIF-67 surface may serve as hard encapsulation layers, which not only facilitates the incorporation of nitrogen atoms onto graphitized carbon skeletons, but also prevents the ZIF-67 polyhedrons from collapsing and effectively impedes the growth of carbon nanotubes during pyrolysis through surface confinement. Gasification in such an encapsulated environment concurrently generates abundant mesopores in the thin walls of carbonized ZIF-67 polyhedrons, which contributes to a high specific surface area of 910.71 m2 g−1 in the resulting Co@NHCC-800 sample, and hence endows an efficient bifunctional electrocatalyst, with a half-wave potential of +0.837 V for ORR in 0.1 M KOH aqueous solution and a required potential of only +1.512 V to reach 10 mA cm−2 in OER catalysis. When used as a breathable electrode for Zn-air batteries, Co@NHCC-800 shows a much higher open-circuit voltage of 1.490 V, a higher discharge power density of 248 mW cm−2 as well as a smaller increasement of only 0.100 V for the charge-discharge voltage gap after cycling for 12 h, as compared with commercial Pt/C catalyst. The results in present work pave a new avenue to the synthesis of sophisticated carbon nanomaterials for electrocatalysis.

We report a sensitive fluorescence probe Ratio-ALP for in vivo ratiometric imaging of alkaline phosphatase (ALP). The probe was designed by conjugating a naphthalimide with a phosphate group as the responsive moiety for enzymatic reactions. The fluorescence intensity ratio displayed a linear relationship against the concentration of ALP in the concentration range from 0 to 200 U/L, its LOD is as low as 0.25 U/L. Ratio-ALP has good selectivity and sensitivity, high cell permeability, and low cytotoxicity. Furthermore, probe Ratio-ALP was also successfully applied to image endogenous ALP activity in living cells.

Compared with the traditional atmospheric carburization, low-pressure carburization has the benefits of producing no surface oxidation and leaving fine, uniformly dispersed carbides in the carburized layer. However, the process parameters for low-pressure carburization of 16Cr3NiWMoVNbE steel have yet to be optimized. Thus, we use the saturation-value method to optimize these parameters for aviation-gear materials. Toward this end, the microstructure and properties of 16Cr3NiWMoVNbE steel after different carburization processes are studied by optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron probe microanalysis. Considering the saturated austenite carbon concentration, we propose a model of carbon flux and an alloy coefficient for low-pressure carburization to reduce the carbon concentration in austenite and avoid the surface carbide network. At the early stage of carburization (˜30 s), the gas-solid interface has a higher concentration gradient. The averaging method is not ideal in practical applications, but the carbon flux measured by using the segmented average method is 2.5 times that measured by the overall average method, which is ideal in practical applications. The corresponding carburization time is reduced by 60%. By using the integral average method, the actual carburization time increases, which leads to the rapid formation of carbide on the surface and affects the entire carburization process. Nb and W combine with C to form carbides, which hinders carbon diffusion and consumes carbon, resulting in a sharp decrease in the rate of C diffusion in austenite (the diffusion rate is reduced by ˜52% for 16Cr3NiWMoVNbE steel). By changing the diffusion coefficient model and comparing the hardness gradient of different processes, the depth of the actual layer is found to be very similar to the design depth.

In recent years, nickel oxide has attracted much attention for the supercapacitor application because of the advantages of low toxicity, cheapness and environment friendliness. This review focuses on the performance of nickel oxide and its composites in supercapacitors and their synthesizing strategies. It is concluded that the supercapacitor performance depends on morphologies, surface area, particle size, porosity and crystallinity of nickel oxide materials. Their three-dimensional morphology with porous structures usually presents higher specific capacitance. Compared with pure NiO nanocrystals, NiO-based composites often show higher specific capacitance resulting from the synergetic effects between the components. Furthermore, the strategies for preparing NiO-based materials including hydrothermal/solvothermal methods, electrospinning technique and microwave-assisted method, and the factors affecting their electrochemical performance have also been summarized.

Hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are two important electrochemical reactions for various energy conversion and storage systems, hence have continuously encouraged tremendous efforts for seeking new catalysts with excellent efficiency and durable long-term stability. Herein, core-shelled Fe@Ru nanoparticles encapsulated in nitrogen-doped porous dodecahedron carbon (Fe@Ru/NC-x, x denotes the initial Ru mass loading percentage) are employed as efficient catalysts for both HER and ORR. Among all the samples, Fe@Ru/NC-9% exhibits superior bi-functional catalytic performance. Its HER activity is close to the state-of-art Pt/C catalyst in alkalic electrolyte, while it also has markedly outperformed long-term stability compared with Pt/C. Moreover, it has a superior ORR activity and stability, along with stronger methanol tolerance than Pt/C in alkalic electrolyte, while in acidic electrolyte, its ORR activity is in the same level with Pt/C but outperformance is demonstrated in durability measurement and methanol poisoning test. Such remarkable electrocatalytic behaviors could be largely attributable to the distinct Fe@Ru core-shell structure resulted lattice strain in the interface, in conjunction with the synergistic catalytic effects between the core-shell structure and the porous dodecahedron carbon support.