The preparation of large-area, high-quality, two-dimensional metallene films often necessitates the use of high-vacuum equipment due to the high surface tension of metals. Herein, we report the growth of large-area coastline-like fractal bismuthene films with intrinsic statistical self-similarity through an interlayer-confined alloying dissolution–precipitation epitaxy method via the construction of a sandwich structure of h-BN/Cu/Mo foil with a nanoconfined space and a sequential dissolution–precipitation process. The resulting bismuthene film manifests a coastline-like fractal feature with a tunable fractal dimension and thickness regulated by the thickness of Cu film. The fractal bismuthene film can be seamlessly transferred to other substrates without incurring oxidation, impurity residues, or structural damage. A 50-nm-thick bismuthene film exhibits semimetallic properties, while an 8-nm-thick bismuthene film behaves as a p-type semiconductor, confirming a typical metal-to-semiconductor transition behavior. This study suggests the significant potential of interlayer-confined precipitation epitaxy strategy in producing large-area two-dimensional metallene films, thereby advancing the development of cutting-edge nanodevices.
Two-dimensional (2D) bismuthene is predicted to possess intriguing physical properties, but its preparation remains challenging due to the high surface energy constraint. Herein, we report a sandwiched epitaxy growth strategy for the controllable preparation of 2D bismuthene between a Cu foil substrate and a h-BN covering layer. The top h-BN layer plays a crucial role in suppressing the structural transformation of bismuthene and compensating for the charge transfer from the bismuthene to the Cu(111) surface. The bismuthene nanoflakes present a superior thermal stability up to 500 °C in air, attributed to the passivation effect of the h-BN layer. Moreover, the bismuthene nanoflakes demonstrate an ultrahigh faradaic efficiency of 96.3% for formate production in the electrochemical CO2 reduction reaction, which is among the highest reported for Bi-based electrocatalysts. This study offers a promising approach to simultaneously synthesize and protect 2D bismuthene nanoflakes, which can be extended to other 2D materials with a high surface energy.
Purpose Infrastructure projects are pivotal for regional economic development, but also face low project effectiveness. Leadership is always regarded as a key enabler for project team effectiveness, including vertical leadership and team-level leadership. The purpose of this paper is to examine how vertical leadership facilitates shared leadership in infrastructure project teams. Design/methodology/approach This paper develops the conceptual model based on the literature review. Then the questionnaire survey was conducted. The empirical data obtained from 117 infrastructure project teams in China were analyzed by partial least squares structural equation modeling (PLS-SEM) for validating the proposed model. Finally, the results were comparatively discussed to explain the dual-pathway between vertical leadership and shared leadership. And the practical implications were presented for the project managers in infrastructure project teams. Findings Drawing on social learning theory and social cognitive theory, the results show that both participative leadership and task-oriented leadership can facilitate shared leadership. Further, team atmosphere fully mediates the link between participative leadership and shared leadership. Team efficacy fully mediates the relation between task-oriented leadership and shared leadership. Also, role clarity has a negative moderating effect on the former path. Originality/value The study extends the knowledge of leadership theory in the construction field. Based on the proposed conceptual model and PLS-SEM results, this study unveils the black box between vertical leadership and shared leadership and contributes to the theory of leadership on how the impact of different vertical leadership on team process promotes shared leadership.
Ultrasound radiation force has been proposed to increase the targeting efficiency in ultrasonic molecular imaging and drug delivery. A chirp excitation technique is proposed to increase the radiation force induced microbubble displacement and might potentially be used for enhancing the targeting efficiency of microbubble clouds. In this study, a modified Rayleigh-Plesset equation is used to estimate the radius-time behavior of insonified microbubbles, and the translation of insonified microbubbles is calculated by using the particle trajectory equation. Simulations demonstrate that the chirp excitation is superior to the sinusoidal one in displacing microbubbles with a wide-size distribution, and that the performance is dependent on the parameters of the chirp signal such as the center frequency and frequency range. For Gaussian size distributed microbubble clouds with mean diameter of 3.5 microm and variance of 1, a 2.25 MHz chirp with frequency range of 1.5 MHz induces about 59.59% more microbubbles over a distance of 10 microm during 200 micros insonification, compared to a 2.25 MHz sinusoidal excitation with equal acoustic pressure.
The study evaluated the comparability of two branded computer-aided sperm analysis (CASA) systems commonly used in andrology laboratories in China. The same semen sample was analysed using two branded CASA systems (WLJY-9000 and CFT-9200) by one well-trained technician. Results of semen analysis obtained from two branded CASA systems were then compared. The accuracy of counting results of CASA systems was evaluated using latex bead solutions with known concentrations of (35 ± 5) × 106 ml−1 and (18 ± 2.5) × 106 ml−1. There were significant differences in all parameters (P < 0.01) except for LIN and WOB. The counting results of CFT-9200 were close to the standard solutions [(38.86 ± 3.79) × 106 ml−1 and (19.03 ± 1.99) × 106 ml−1], while those of WLJY-9000 were underestimated [(28.53 ± 2.06) × 106 ml−1 and (14.62 ± 0.95) × 106 ml−1]. But the coefficient of variation of WLJY-9000 was lower than that of CFT-9200 (7.22%, 6.50% vs. 9.82%, 10.46%). It is concluded that factors such as parameter settings and evaluation algorithms could significantly affect the results obtained from these two branded CASA systems. Great attention should also be paid to the quality control in semen analysis with CASA.
Currently the vast regional areas in China are confronted with spatial restructuring and problems aroused by rapid economic development, and uneven development between regions is in desperate need of solution in particular. Base on the annual economic development statistic data in the Yangtze River Delta city group, this paper uses GeoDA and Arcgis to generate thematic map for economic spatial evolution feature analysis of geographic data. The results show that: there has been a significant absolute difference for the economic development of the Yangtze River Delta city group, and this trend is further exacerbated. Meanwhile, the paper makes exploring research on economic space evolution in China from the aspects of global spatial evolution characteristics and local spatial evolution characteristics by using geographic information technology.
Epitaxial growth and subsequent processing of 2D materials are mostly confined to xy plane parallel to the substrate. Introducing another degree of freedom, i.e., the vertical direction perpendicular to the base plane, is very intriguing, as the resulting vertically aligned 2D materials will intuitively have a high aspect ratio, anisotropic structure, and abundant edge sites, holding great promise in field emission, photoelectronics, piezoelectricity, clean energy catalysis, etc. However, the key factors governing the spatially anisotropic growth to selectively obtain vertically or horizontally aligned 2D nanoflakes remain elusive. Herein, we report a controllable and general strategy to vertically grow representative 2D metal chalcogenide materials, including but not limited to SnS, SnSe, Bi2Se3, MoO3, and MoS2 nanoflakes, via a rapid heating-cooling process on various optional substrates. The rapid heating-cooling process allows rapid desublimation and nucleation of highly-supersaturated precursor vapor, leading to ultrafast growth of vertically aligned nanoflakes with exposed side surfaces and edges. As an example, the vertically grown SnS nanoflakes exhibit anisotropic spectroscopic features, superior photoelectric properties and enhanced electrocatalytic performances for the nitrate reduction and CO2 reduction reactions. This work provides a feasible approach to controllably synthesize versatile vertically aligned 2D metal chalcogenide nanoflakes on various substrates, which can advance the mechanistic understanding of anisotropic growth and physicochemical properties of 2D materials towards photoelectric devices and clean energy conversion.
Abstract The challenge of multispecies bacterial biofilms involves secondary infections from biofilm dispersion while failing to clear resident‐bacteria, along with health risks from endotoxins. Although photodynamic therapy simultaneously eliminates biofilms and resident‐bacteria, its effectiveness is limited by the short half‐life of reactive oxygen species (ROS). And the slightly acidic properties of biofilms offer opportunities to mitigate anionic endotoxin hazards. Consequently, a nanoproducer is developed that releases nitric oxide by leveraging its prolonged half‐life and interaction with superoxide anions to extend the range of ROS oxidation. Meanwhile, the nanoproducer can respond to the biofilm's pH, gaining a strong positive charge to effectively capture released endotoxin during treatment. This research indicates that nanoproducers effectively disperse biofilms and improve their penetration into polymeric substances, leading to efficient reduction of bacterial burden in mice harboring biofilm and abscess models. Additionally, nanoproducers effectively reduce inflammatory cytokine levels and immune cell infiltration caused by endotoxin. The nanoplatform, therefore, demonstrates remarkable promise in combating bacterial biofilm infections and alleviating the risks associated with endotoxins.
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