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In light of the profound advancements in information and communication technologies ushering in the knowledge economy, the urban space is undergoing a transformation from the traditional “space of places” to the emerging “space of flows.” This shift poses questions about the influence of knowledge flows on urban economic centrality. This paper seeks to address this knowledge gap by introducing a theoretical framework that elucidates how knowledge contributes to urban economic centrality. Our analysis focuses on both intra-city knowledge stocks and inter-city knowledge flows. Empirical findings in China highlight that knowledge stocks based on R&D and education levels, along with knowledge flows, significantly and positively influence all four dimensions of centrality. In contrast, knowledge spatial agglomeration within the knowledge stocks exhibits a significant positive correlation solely with power centrality. Additionally, although the knowledge stock structures don't yield significant results in the diffusion centrality model, for agglomeration and power centralities, a combination of specialized knowledge and telecommunications enhances urban economic centrality, while face-to-face communication strengthens the positive impact of diverse knowledge on urban economic centrality. The results suggest implementing knowledge-based policies tailored to different nodes in the city network is expected to promote sustainable competitiveness in the urban system.

Industrial activity is widely regarded as one of the important sources of air pollution. However, existing studies still debate the complex effects of industrial patterns on air pollution. This study proposes a multidimensional framework to explore the multiple effects of industrial enterprises on the air quality index in China. We examine the industrial core-edge, structure, and technology effects on air pollution by using spatial Durbin models based on geospatial databases. Results show that industrial core agglomeration exerts a spatial spillover effect on air pollution, especially continuous pollution. The increasing industrial scale and diversity intensify air pollution, reflecting the structure effect. Enterprises with long business lifespans are conducive to mitigating air pollution through the technical alleviation effect. The high ratio of state-owned enterprises exacerbates air pollution in northern China. The industrial spatial spillover effect contributed remarkably to air pollution, calling for cross-regional and intergovernmental collaboration on air quality improvement.

The incidence of central nervous system tuberculosis is a rare entity that accounts about 1% of all tuberculosis and remains a major health problem in developing countries. We report a case of 1-year-old baby boy who presented with a three-week history of vomiting, seizure and progressive right-sided weakness. Brain magnetic resonance imaging performed on the admission day revealed a large lesion measuring (4.3*3.5cm) involving the left thalamus with extensive perilesional edema producing enfacement of third ventricle, midline shifting and obstructive hydrocephalus.

In this article, we presented the detailed measurements and comparisons of skeletal muscle perfusion parameters in a canine hind limb ischemia model. Data presented here is related to and supportive to the research article “Evaluation of skeletal muscle perfusion in canine hind limb ischemia model using color-coded digital subtraction angiography” [1], where interpretation of the research data presented here is available.

Summary: The development of efficient catalysts for ammonia synthesis under mild conditions is critical for establishing a carbon-neutral society powered by renewable ammonia. While significant effort has been focused on Fe and Ru-based catalysts, there have been very limited studies on manganese-based catalysts for ammonia synthesis because of their low intrinsic catalytic activity. Herein, we report that the synergy between manganese nitride (Mn4N) and europium nitride (EuN) yields an ammonia synthesis rate that is 41 and 25 times higher than that of neat Mn4N and EuN, respectively. Detailed studies suggest that a [Eu-N-Mn] species at the interface of Mn4N and EuN plays a pivotal role in ammonia synthesis. Compositing of Mn4N with other rare earth metal nitrides such as LaN, PrN, and CeN also leads to a significant enhancement in catalytic activity. This work broadens the scope of advanced nitride catalysts for ammonia synthesis.

To investigate the dynamic changes in dry matter accumulation in maize after anthesis, we established a logistic model to describe grain filling characteristics (GFC), and analyzed differences between spring and summer maize, and the influence of meteorological factors. The results showed that the logistic model accurately simulated the dynamic changes in grain growth. For spring maize, the fitted hundred-grain weight at maturity was closely related to the average grain filling rate until maturity, days of the active grain filling period, time of the maximum grain filling rate, and duration of the rapid increase in grain weight. For summer maize, it was closely related to the time of the maximum grain filling rate, days of active grain filling period, duration of gradual grain weight, and the rapidly increasing period. The filling characteristics of spring and summer maize differed because of the different meteorological conditions and biological characteristics. The grain filling duration of spring maize was longer than that of summer maize. The maximum grain filling rate of spring maize occurred later than that of summer maize. Temperature and precipitation were the main meteorological factors affecting the hundred-grain weight of spring maize, whereas temperature was the main factor affecting summer maize. The response of spring maize GFC to meteorological factors was more complex than that of summer maize. These results are important for the development of appropriate strategies for improving maize productivity in China.

Flexoelectric and photo-flexoelectricity are scientifically intriguing and hold considerable potential for various applications such as soft strain sensing, photovoltaics, energy harvesting, etc. Among flexoelectric materials, freestanding ferroelectric thin films are believed to have huge flexoelectricity and tunability due to their excellent lattice regulatory freedom and sustainability to larger strain gradients. In this work, we demonstrated a freestanding BiFeO3(BFO) thin film-based soft strain sensor and explored their flexoelectric coefficient and flexoelectric photovoltaic effect under different strain gradients. Under different bending scales, the photocurrent of the thin film exhibits a step-like variation, indicating that the sensor can measure strain gradient with high sensitivity. These results show the potential application of freestanding ferroelectric films in flexible devices.

In this study, we design a one-dimensional periodic ring multi-connected optical waveguide network to solve the problem of obtaining ultra-wide photonic band gaps that are too complex for the photonic band gap width to be tuned. Analysing the spatial structures and numerical relations of our network reveals a common characteristic that the photonic band gap width is independent of the number of nodes in a unit cell of the optical waveguide network. Based on this character, we explore the potential practicability of our network by comparing it with existing optical waveguide network schemes. Our network has the advantages of lower complexity for the spatial topology, better scalability of the spatial topology, and better structural invariance.

Summary: The fixation of atmospheric dinitrogen to ammonia is crucial for the sustainable growth of human society. The reduction of N2 to NH3 needs the inputs of electrons and hydrogens, which could be supplied by hydridic hydrogens. Hydrides are thus at the forefront of research on homogeneous, biological, and heterogeneous nitrogen fixation. In the present report, we discuss representative progress on the exploration of molecular and bulk-phase hydrides for dinitrogen activation and reduction with a focus on the active involvement and function mechanism of reactive hydride compounds in facilitating ammonia production under mild conditions. We conclude that, with the versatile and important roles discovered, hydrides have the power to mediate electron and/or hydrogen transfers for N2 fixation via energetically more accessible pathways, which in turn would stimulate new ideas for the design and development of more efficient catalysts or processes for green ammonia production.

In this paper, we use the rotating elliptical Gaussian beams (REGBs) to impinge the surfaces coated with cross-anisotropic metasurfaces (CMs) to investigate the Goos–Hänchen (GH) and Imbert–Fedorov (IF) shifts. The effect of the CM coating on the reflection coefficient in this system is considered. In particular, we will show that the angle of incidence and the relative permittivity of the weakly absorbing medium have an influence on the GH and the IF shifts. A comparison with the case of surfaces without the CM is also discussed.

Modulated by the spatial phase, Airy-like beams that possess the faster and better self-healing as well as the greater acceleration along the desired arbitrary trajectory are introduced. Airy-like beams have the strong spontaneous-focusing ability and the peak value of the focal plane is 5.4 times that of the initial plane when traveling along the quadratic function trajectory. Besides, the larger quadratic coefficient and the smaller constant term of the quadratic function can enhance the self-healing and the spontaneous-focusing of the beams. When the beams transmit along the snakelike trajectory, the original main lobe separates a new main lobe, and the energy will concentrate on the new main lobe. Airy-like beams, along a hyperbolic-secant trajectory, can remain non-diffraction over long distances. However, when traveling along a hyperbolic trajectory, the evolution process is very similar to that of Airy-Gaussian vortex beams. These excellent properties can be applied to the special beams’ modulation and optimization. Furthermore, it may provide a way for constructing beams along the special trajectory with the desired spontaneous-focusing and self-healing.

Assessing the impacts of future climate change on crop yields requires basic research into both the major meteorological factors that affect crop yield and the influence that changes to global circulation patterns have on local meterological parameters. For example, the atmospheric circulation and crop “meteorological yield” and the response of meteorological yield to climate change are positively correlated. Using apple (Malus domestica) production as an example, the present work investigated the link between fruit yield and global circulation factors by using yield data from 28 apple-producing counties in Shaanxi province, China, from 1980 to 2015. We used four methods to isolate apple production and applied a Grey relational analysis of 88 meteorological factors and the associated sequential correlation. We extracted the major climate factors based on the high consistency of climatic factors and the variation trend of meteorological yield of apple, and analyzed the main meteorological factors for the meteorological apple yield of three major apple producing areas by analyzing high-impact atmospheric circulation indices. The climate factors included solar radiation, pan evaporation, accumulated temperature, precipitation, wind speed, maximum temperature, minimum temperature, mean temperature, heat injury over several days, number of frost days during flowering, number of freezing days during dormancy, and annual temperature range. The main meteorological factors affecting annual apple meteorological yield were total solar radiation from April to October, evaporation from April to September, precipitation in April and June to August, and minimum temperature in mid-April. The Southern Oscillation Index (SOI) was the circulation index most closely related to total summer solar radiation, pan evaporation, and precipitation. Correlation analysis showed that the polar vortex area index and sea surface temperature index were important circulation indices affecting climate yield in apple regions. The meteorological yields of apples in zones Ⅰ and Ⅲ were significantly correlated with the ENSO period index, mainly in the autumn and winter. Similar to the conclusions of previous studies, the uncertainty of meteorological yield in the Shaanxi fruit region is predicted to increase under future climate change. Keywords: Apple yield, Shaanxi province, Grey relational analysis, Climate factors, Circulation index