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[Objective] The aim is to reveal and validate the wave-like climbing pattern of land green use efficiency in urban agglomerations, providing decision support for promoting integrated enhancement of land green use efficiency and collaborative use of land resources within urban agglomerations. [Methods] Using panel data from 2006 to 2020, taking urban agglomerations of China as the research object, this study first analyzed the basic principles of the evolution of land green use efficiency in urban agglomerations based on the theories of urban functional interaction, spatial justice, and the adaptability theory of human-environment systems. Subsequently, methods including the non-expected output super-efficiency SBM model, joint intensity and threshold model, and numerical simulation were employed to explore the spatial-temporal characteristics and climbing patterns of land green use efficiency in these urban agglomerations. [Results] (1) The overall trend of land green use efficiency in urban agglomerations of China is upward, and spatially exhibiting a distribution of “higher in the north and south, lower in the middle, and higher in the west and lower in the east”; (2) The joint intensity of land green use between the central cities and neighboring cities continues to increase, with a threshold limitation. The process of central cities jointly arranging land green use with surrounding cities presents a step-like diffusion pattern from the central cities to the periphery; (3) The fluctuating climbing curve of land green use efficiency in urban agglomerations with the changes in time and the joint development of cities has been verified in practice, and the fitting is reasonable. [Conclusion] Cooperation between the central city and neighboring cities in the field of land green use of land resources in urban agglomerations should be strengthened. Clarifying the functional positioning of cities， through functional streamlining or aggregation, industrial chain integration, and the integrated development of industrial interactions can promote the formation of a high-quality development pattern of national land space.

Recently, dockless bikeshare (DBS), a new bikeshare program that does not feature fixed dock stations, has been developed rapidly in China and has also offered a decent solution to the first- and last-mile problem. In addition, the integration of DBS and metro strongly promotes the transit-oriented development, particularly in the metropolitan areas of China. To achieve the seamless connection between DBS and metro transit, the spatial variation of the effects of urban built environment, particularly in high-density metropolitan areas, should be explored to advance the targeted policy interventions in different urban spaces. Using data from one of the largest DBS operators in China (ofo), this study measured the integrated use of DBS and the metro quantitatively, and it employed geographically and semiparametric geographically weighted regression (GWR and SGWR, respectively) to examine the effects of the built environment on the integrated use, using Shenzhen as a case study. The findings show that (1) The SGWR model performs better than GWR and OLS in explaining the relationship between built environment and access integrated use, whereas SGWR is not applicable for the egress integrated use. (2) Three positive determinants of population density, major road length and inbound metro ridership, and three negative determinants of metro density, secondary school, and intersection density have been examined with spatial effects on the access integration. (3) For egress integration, official land use, park, bus stops, and outbound metro ridership have positive and spatial effects, while residential land use, number of secondary school, metro density and distance to CBD (Central Business District) exert negative spatial effects. The results indicate that the built environment elements usually affect the integrated use with spatial variation. Furthermore, the access and egress integration use of DBS metro largely depends on the characteristics of built environment of the origin and destination metro catchment, respectively. This work provides insight into how the DBS-metro integration, which is divided into access and egress patterns, is spatially affected by urban built environment in the Chinese metropolitan context. The results will also provide a reference for the local government to carry out the targeted policies and planning to encourage the connection between DBS and metro transit more successfully. For DBS operators, the results also contribute to allocating the bikes more efficiently, which is adapted to the dynamic demand-supply at different urban spaces.

JZTX-V is a toxin isolated from the venom of the Chinese spider Chilobrachys jingzhao. Previous studies had shown that JZTX-V could inhibit the transient outward potassium current of Kv4.2 and Kv4.3 expressed in Xenopus oocytes but had no effects on Kv1.2–1.4. However, the underlying action mechanism of JZTX-V on Kv4.3 remains unclear. In our study, JZTX-V could inhibit not only transient outward potassium currents evoked in small-sized DRG neurons but also Kv4.3-encoded currents expressed in HEK293T cells in the concentration and voltage dependence. The half maximal inhibitory concentration of JZTX-V on Kv4.3 was 9.6 ± 1.2 nM. In addition, the time course for JZTX-V inhibition and release of inhibition after washout were 15.8 ± 1.54 s and 58.8 ± 4.35 s. Electrophysiological assays indicated that 25 nM JZTX-V could shift significantly the voltage dependence of steady-state activation and steady-state inactivation to depolarization. Meanwhile, 25 nM JZTX-V decreased markedly the time constant of activation and inactivation but had no effect on the time constant of recovery from inactivation. To study the molecular determinants of Kv4.3, we performed alanine scanning on a conserved motif of Kv4.3 and assayed the affinity between mutants and JZTX-V. The results not only showed that I273, L275, V283, and F287 were molecular determinants in the conserved motif of Kv4.3 for interacting with JZTX-V but also speculated the underlying action mechanism that the hydrophobic interaction and steric effects played key roles in the binding of JZTX-V with Kv4.3. In summary, our studies have laid a scientific theoretical foundation for further research on the interaction mechanism between JZTX-V and Kv4.3.

The citizenization of the floating population is a primary task of the people-centered new urbanization. Taking the Yangtze River Delta urban agglomeration as an example, this paper analyzes the spatial distribution and influencing factors of the long-term residence intention of the urban floating population using a multilevel logistic regression method. The findings were as follows. (1) The proportion of the floating population with long-term residence intention was 38.09% in the Yangtze River Delta urban agglomeration. Cities with the highest and higher proportions of long-term residence intention were mainly concentrated in Anhui Province in the west of the urban agglomeration and the Shanghai-Nanjing development axis, while the floating population that migrated to Zhejiang Province generally had medium and low residence intention. The spatial difference of the long-term residence intention of the floating population was different from that of the floating population size. As for the types of floating population, for most cities in the coastal provinces, their floating populations were comprised mainly of inter-provincial migrants. Shanghai and Zhejiang Province, especially, were the main destinations of inter-provincial migrants. Anhui was a typical area of population outflow, and the floating population staying there was made up mainly of intra-provincial migrants. (2) The rent-to-income ratio had a significant negative effect on the long-term residence intention of the floating population. Among the personal and family factors, high education, social and psychological identity, and affordable housing were strong motivating factors, but working in the labor-intensive sector had a strong negative effect on long-term residence intention. Among the factors of the destination cities, megacities strongly influenced the long-term residence intention of the floating population. (3) The housing rent was positively related to the long-term residence intention in the Yangtze River Delta, while the average income of residents in the city did not promote the long-term residence intention of the floating population. Migrant age was negatively correlated with their long-term residence intention. These are new findings of the study. (4) The influencing factors of the long-term residence intention of the floating population varied according to the city size. Age and inter-provincial migration were the limiting factors for long-term residence intention in general cities, but they were not significant in megacities. The long-term residence intention in megacities was more related to high education and employment type. This indicates that megacities are more inclusive of inter-provincial migrants and friendly to various ages; migrants' residence intention in megacities depends more on personal qualities and employability. Besides, the average income level of the destination city only had a negative effect on the residence intention in general cities.

In order to investigate the response law of moisture content to the characteristic stress and acoustic emission characteristics of red sandstone, the uniaxial compression tests of red sandstone under different moisture content conditions were conducted using RMT-150C rock mechanical pressure testing machine and PCI-Ⅱ AE win acoustic emission system. The physical and mechanical parameters and characteristic stress evolution mechanism of red sandstone under water erosion are analyzed, and the evolution law of acoustic emission (wide and narrow-band) time series mode under different moisture content conditions is also investigated. At the same time, the damage evolution model of red sandstone is constructed based on cumulative acoustic emission event number and statistical mechanics theory. The results show that: 1) The P-wave velocity decreases first and then increases with the increase of moisture content. When the water saturation reaches a critical value, the P-wave velocity will drop to the lowest value. 2) The acoustic emission signal received by the narrow-band receiving sensor is closely related to the friction between the particles in the red sandstone, and the acoustic emission signal received by the wide-band receiving sensor is intrinsically related to the evolution of the internal cracks in the red sandstone. 3) The moisture content has a significant effect on the acoustic emission event rate (wide-band) at the stage of unstable crack propagation, and has a minor effect on the ratio of characteristic stress to peak strength, but it has a relatively obvious effect on the strain percentage at each stage. With the increase of moisture content, the failure mode of red sandstone specimens gradually changes from brittle failure to ductile failure. 4) As the moisture content increases, a "backward" change trend can be observed for the active period of acoustic emission event rate (narrow-band), and the acoustic emission modes of dry, natural, and saturated rock samples correspond to mass shocks, pre-main-later shocks and swarm shocks type, respectively. (5) According to the damage model based on the cumulative number of acoustic emission events (wide and narrow-band), the damage process of red sandstone can be divided into four stages: initial damage stage, stable damage development stage, accelerated damage development stage and damage destruction stage.

High unstable rock masses are widely distributed in the upper part of a railway tunnel entrance in the southwestern mountainous area, which causes serious hazards to the construction of the lower tunnel. The Rockfall Analyst software was used to simulate the three-dimensional movement track of five kinds of high unstable rock masses in the upper part of the tunnel, and it shows that the rockfalls in the study area have the characteristics of high bounce height, fast speed and high impact energy. There is no relation between the bounce height, the movement speed and the mass of rockfall, while the impact energy is proportional to the mass of rockfall. The analysis shows that multiple and comprehensive protective measures should be recommended for the protection of unstable rock masses in this area instead of single protective measure.

In most perovskite nanocrystal (PeNC)-based optoelectronic and photonic applications, surface ligands inevitably lead to a donor–bridge–acceptor charge transfer configuration. In this article, we demonstrate successful modulation of electron transfer (ET) rates from all-inorganic CsPbBr3 PeNCs to mesoporous titanium dioxide films, by using different surface ligands including single alkyl chain oleic acid and oleylamine, cross-linked insulating (3-aminopropyl)triethoxysilane and aromatic naphthoic acid molecules as the ligand-bridge. We systematically investigated the ET process through time-resolved photoluminescence spectroscopy. Calculations verified the ligand-bridge barrier effect of the three species upon the ET process. Transient absorption measurements excluded carrier-delocalization effect of the naphthoic acid ligands and confirmed the bridge-barrier effect. Our work provides a perspective for composable and appropriate ligands design for diverse practical purposes.

Recently, two special photonic jets, photonic hooks and twin photonic jets, have been proposed to deal with complex conditions in nanoscale manipulation. Photonic hooks are generated by a single light plane wave and an asymmetric microparticle, while the twin photonic jets are produced by two incident light beams. In this letter, we presented and demonstrated a method to combine photonic hooks and twin photonic jets. A single light plane wave and a symmetric microparticle, twin-ellipse microcylinder, are used in this research. The curvature degree, length and maximum E2 field enhancement of twin photonic hooks are varied significantly, with the change of refractive indices and shape of twin-ellipse microcylinder. And a liquid-immersed core-shell is built to achieve a flexible tunability.

A novel mechanism of sensitivity enhancement of D-shaped fiber-based surface plasmon resonance (SPR) sensors for the optofluidic device has been proposed. The sandwiched structure optofluidic platform is developed with metal-coated D-shaped fiber as the sensing device, while another thin metal layer is situated under the inner wall of the substrate as a second metal layer to construct the sandwiched microchannel. It has been found that the sensitivity of the D-type fiber SPR sensor is enhanced significantly with the sandwiched metal-coated structure of microchannel. In the proposed structure, the measurand analyte is considered as a sandwich channel layer between two thin metal layers. The sensitivity of the proposed structure is dependent on the volume of the measurand and the thickness of the metal layers. The computed sensitivity with a double metal layer and sandwich measurand layer concept is 4085 nm/RIU in the region of 1.33 to 1.36. The sensitivity is enhanced by more than a factor of `2.3' in comparison with the sensitivity of the normal D-shape fiber SPR sensor. It can be enhanced further up to ~12,500 nm/RIU by the deposition of higher RI polymeric overlay just above the second metal layer. The computed resolution of the proposed sensor with standard interrogation technique is ~1 × 10-7 which is quite competitive within the optical fiber sensor domain. A detailed numerical analysis has been accomplished. This structure will be useful in distinct chemical and biological sensing applications where the volume of an analyte is critical. This new concept of enhancement of sensitivity with limited measurand volume will open a new designing methodology for optical fiber biosensors.

This paper studies the microstructure and mechanical properties of MIG (Melt Inert Gas) lap welded 6005 aluminum alloy plates. Microstructure analysis (OM) of the joint showed that 15~30 μm small grains were observed at the fusion line. Mechanical analysis shows that the small grains are broken by shielding gas and molten pool flow force. Hardness test shows that there is a softening zone (41~43 HV) in HAZ much lower than BM and WZ. The low cycle fatigue test showed that the performance of lap joint decreased sharply, and the fatigue strength of weld decreased significantly, which was only 27.34% of the base metal. The fatigue fracture (SEM) of the weld observed slip band cracking and a large number of brittle fracture characteristics. Using the stress concentration factor Kt for analysis, it was found that the cause of brittle fracture was mostly stress concentration. Lap joint stress concentration model appears in two ways: firstly, at the weld toe, the weld is subjected to eccentric force, secondly, there is a small gap between the two plates at the weld root, which cracks along the direction of 45° of the maximum shear stress.

In this study, metal inert gas welding (MIG) was applied to 4 mm thick 6005A-T6 aluminum alloy welding. Compared with other parts, the hardness of the weld zone (WZ) was the lowest, about 67 HV. There was the Softening in WZ, which might make WZ the weakest zone. Then, fatigue tests were carried out on MIG welded joints. All the fatigue specimens fractured at the weld toe of the lap joint, and the fracture was characterized by a cleavage fracture. Crack closure induced by oxide was observed during the steady propagation of the fatigue crack. Impurities hindered crack propagation, changed the direction of crack propagation, and appeared in stepped fatigue strip distribution morphology; in the process of the main crack propagation, the initiation and propagation of small cracks were easily restricted and hindered by the main crack, which slowed down the propagation rate and even stopped the propagation directly.

Objective: Despite the potential therapeutic approaches of bone marrow-derived mesenchymal stem cells (BMSCs) in orthopaedic, their applications are hampered by harsh oxidative stress conditions after transplantation. In this study, the anti- apoptotic and anti-oxidative properties of lithospermic acid (LSA) on BMSCs exposed to hydrogen peroxide (H2O2) were investigated. Methods: In the present study, we used H2O2 to induce oxidative injury on BMSCs. Reactive oxygen species (ROS) staining and superoxide dismutase (SOD) assay were performed. The expression levels of phosphorylated (p)-Akt, Bcl-2-associated X protein (Bax) and B-cell lymphoma 2 (Bcl-2) were measured by Western blotting. Results: LSA can significantly reduce H2O2-induced chromatin condensation and intracellular ROS levels, enhance the activity of SOD. Moreover, it can alleviate H2O2-induced apoptosis by up- regulating Bcl-2 and p-Akt, down-regulating Bax, which was blocked by the PI3K inhibitor, LY294002. Conclusions: Our results demonstrated that pretreatment with LSA could attenuate oxidative stress-induced apoptosis in BMSCs, which may be related with anti-oxidant properties and partly via modulating PI3K/Akt pathway, suggesting that pharmacologically manipulating BMSCs with LSA could be a promising drug to increase cell survival for BMSCs transplantation in musculoskeletal disorders of orthopaedic. Keywords: Oxidative stress, Lithospermic acid, Apoptosis, BMSCs, PI3K/Akt

In this paper, 316L stainless steel powder was processed and formed by selective laser melting (SLM). The microstructure of the sample was studied using an optical microscope, and the fatigue failure of the sample and the characteristics of crack initiation and propagation were analyzed, providing a research basis for the application of SLM-316L. Due to the influence of microstructure and SLM process defects, the fatigue cracks of SLM-316L mainly emerged due to defects such as lack of fusion and pores, while the cracks of rolled 316L initiated at the inclusions near the surface of the specimen. After fatigue microcrack initiation of the SLM-316L specimen, due to the existence of shear stress and tear stress, the crack tip was passivated and Z-shaped propagation was formed. The existence of internal defects in SLM-316L made the microcrack initiation random and diverse. At the same time, the existence of defects affected the crack propagation in the form of bending, bifurcation and bridge, which made the main crack propagation deviate from the maximum load direction.

In the application of additive manufacturing, it is inevitable to use some formed parts with a smaller height. The analysis of various mechanical properties of these formed parts is the focus of research. In this paper, the fatigue performance of a titanium alloy specimen with a 10 mm height and electron beam selective melting is studied. By analyzing the structure and phase of the overall fatigue specimen, and then cutting the overall specimen parallel and perpendicular to the additive manufacturing direction, the tensile and fatigue tests in different directions are performed to detect the fatigue cracks at the fracture propagation the way to research. It is found that there are two ways of secondary crack propagation between fatigue bands, and three cracks are generated during the fatigue secondary crack propagation.

Nanotechnology is a technology with high requirements of science and technology and involves many comprehensive disciplines. With the continuous development of science and technology, nanotechnology has penetrated into all aspects of our lives. Now nano materials, nano pumps, Nano Electronics and nanotechnology have been applied in the competitive field of China. It is these nanotechnologies that have made great progress in the field of sports competition in China. Looking to the future, we have to pay attention to the physical and mental health of athletes in the era of sports competition. At the same time, we should be good at using nanotechnology to promote the healthy and harmonious development of sports competition in China.