电子雷管技术的推广应用助力爆破器材安全管理工作

电子雷管技术提高了爆破器材的本质安全。通过对电子雷管技术发展历程的介绍,对其推广应用的可行性进行了深入分析,论述了电子雷管技术的推广应用对爆破器材安全管理工作的促进作用,并提出了今后推广应用中还需加强的工作。     

How does time spent on WeChat bolster subjective well-being through social integration and social capital?

Although WeChat has recently spawned significant resolutions in technology-mediated social contact and interpersonal communication, the research regarding the social and psychological impacts of the newly emerging technology is relatively few. The primary purpose of the current empirical research is to unearth whether and how WeChat interaction could enhance overseas students’ sense of subjective well-being by concentrating on social integration, bridging relationships, and bonding relationships. Using web-based data of 228 Chinese subjects, the obtained results reveal that the time spent on WeChat significantly and directly impacts users’ subjective well-being. Additionally, the findings demonstrate that social integration, bridging relationships, bonding relationships are all significant predictors to subjective well-being. Furthermore, the perceptions of social integration and social capital could play the crucial mediating roles in the connection between WeChat use and the dependent variable of subjective well-being. Therefore, these outcomes may shed light on a more nuanced comprehending of the influence of the new social media interaction on sojourner’s social adaption and overall life quality in the digital age.     

Can lanthanum doping enhance catalytic performance of silver in direct propylene epoxidation over NaMoAg/SiO_2?

In the attempt to reduce surface free energy of silica to improve interaction of silica with silver, silica was doped by different amounts of low surface energy lanthanum, La_2O_3, through impregnation. The doped and undoped silica were used as supports for preparation of Na/Ag/Mo/La_2O_3-SiO_2 catalysts. Catalytic performances of the catalysts were evaluated in direct epoxidation of propylene(DPO) using molecular oxygen under atmospheric pressure and without adding hydrogen. Adding 5 wt%La to the Na/Ag/Mo/SiO_2 catalyst improves both the catalysts electivity in DPO and its stability over 20h of time-on-stream.The characterization results show that La_2O_3 species interact strongly with silver particles on the silica surface which result in significant improvement in the dispersion profile of silver and marked decrease in the size of silver nanoparticles(AgNPs). The estimated mean diameter of AgNPs is ca. 4.0 nm in Na/Ag/Mo/5 wt%La_2O_3-SiO_2, which is smaller than that(53.9 nm) found in Na/Ag/SiO_2. The presence of subnanometer AgNPs on Ag/La_2O_3-SiO_2 prior addition of MoO_3 and NaCl to the sample can enhance the mutual electronic synergism between Ag, MoO_3 and Na for selective production of propylene oxide.     

Influence of lanthanum on enhancement of mechanical and electrical properties of Cu-Al_2O_3 composites

Two kinds of Cu-Al_2O_3 composites(with and without La) were prepared via mechanical alloying-spark plasma sintering(MA-SPS) method. Microstructure, mechanical properties and electrical resistivity were investigated systematically using metallography, scanning electron microscopy, transmission electron microscopy, mechanical and electrical properties testing. The results indicate that an appropriate amount of La can homogenize the distribution of Al_2O_3. As such, yield strength, ultimate tensile strength and elongation of Cu-Al_2O_3-La are greatly increased. Some semi-coherent interface between Cu and Al_2O_3 is found, which means a low interface energy. The grain shape of Cu changes to irregular band with the addition of La. This change results in a density decrease of grain boundary and reduces electrical resistance. Lanthanum may exist in the form of La_2O_3.     

Prediction methods and applications in the science of science: A survey

Science of science has become a popular topic that attracts great attentions from the research community. The development of data analytics technologies and the readily available scholarly data enable the exploration of data-driven prediction, which plays a pivotal role in finding the trend of scientific impact. In this paper, we analyse methods and applications in data-driven prediction in the science of science, and discuss their significance. First, we introduce the background and review the current state of the science of science. Second, we review data-driven prediction based on paper citation count, and investigate research issues in this area. Then, we discuss methods to predict scholar impact, and we analyse different approaches to promote the scholarly collaboration in the collaboration network. This paper also discusses open issues and existing challenges, and suggests potential research directions.     

新城市科学背景下的城市设计新可能

本文面对智慧城市和新城市科学 迅速发展的背景，立足新时期城市设计转型 需求，针对新近涌现出的以机器学习、虚拟 现实、计算机可视化等为代表的多种新技术 和以街景数据、兴趣点数据、位置服务数据 等为代表的多源城市数据开展讨论。继而对 其所带来的城市设计新可能进行了探讨和展 望，并对于相关典型工具和代表性案例进行 了介绍。这些伴随新城市科学涌现的数据和 技术不仅能够为城市设计在场地分析、设计 开展和方案评估上带来工作方式的革新，而 且有望进一步明确城市设计的专属技术体 系，并以此推动城市设计的领域构建。     

Effects of sintering method and BiFeO3 dopant on the dielectric and ferroelectric properties of BaTiO3–BiYbO3 based solid solution ceramics

(0.95–x) BaTiO₃–0.05 BiYbO₃–x BiFeO₃ (x?=?0, 0.01, 0.02, and 0.04) (abbreviated as (0.95–x) BT–0.05 BY–x BFO) ceramics were fabricated by conventional sintering (CS) and microwave sintering (WS) methods. Effects of sintering method and BFO dopant on the microstructure and electric properties of (0.95–x) BT–0.05 BY–x BFO ceramics were comparatively investigated. X-ray diffraction showed that all CS and WS samples presented a single perovskite phase. It was also found that WS ceramics possessed denser microstructure and finer grains compared to CS samples as indicated by the surface morphology characterization. Dielectric measurements revealed that all samples exhibited the weak relaxation behavior; however, the degree of relaxation behavior of BT–BY based ceramic could be strengthened by addition of BFO and by WS method. Moreover, the temperature and frequency stability could be improved with doped BFO. The density of 0.93BT–0.05BY–0.02BFO ceramic was found to be the largest while that of 0.94BT–0.05BY–0.01BFO ceramic was the smallest, thus, the dielectric constant of 0.93BT–0.05BY–0.02BFO was significantly larger than that of 0.94BT–0.05BY–0.01BFO and 0.94BT–0.05BY–0.04 BFO ceramics. minimum dielectric constant of (0.95–x) BT–0.05 BY–x BFO ceramic was obtained at x?=?0.01. Ferroelectric measurements indicated that all samples showed the slim hysteresis loop. The remnant polarization (P_r) and coercive field (E_C) of (0.95–x) BT–0.05 BY–x BFO ceramics first decreased and then increased with increasing x，the minimum values were obtained at x?=?0.01. Moreover, P_r and E_C of WS ceramics were slightly larger than those of CS ceramics, indicating that higher density and larger grain sizes contributed to enhancing the ferroelectric characteristic. These findings indicate that addition of moderate amount of BFO and use of WS technique can strengthen the degree of relaxation behavior and improve the ferroelectric properties of BT–BY based ceramics.     

Regional science: economy and geography in France and French-speaking countries

The objective of this paper is to assess the French-speaking countries contributions to regional science since its creation in the 1950s. France, and other French-speaking countries, very quickly adhered to the approach of the founding fathers of regional science. French-language research developed for several years without maintaining major relations with the main streams that flow through regional science. However, the years 2000 and 2010 saw the emergence of streams of thought that strongly irrigate at the international level. The authors of this paper are part of this movement. Here we trace the origins and development of the French-speaking contribution to regional sciences, while highlighting the originality of the French-language approach. First, the question of academic and institutional contexts is discussed, with the role of the founders and the peculiar place of Journals and public institutions. Further sections analyse the main contributions coming from economics (local systems of production and innovation, innovative milieus and proximity analysis) and geography (regional development at a global scale, and urban systems and complexity). We conclude with cross-disciplinary contributions including intra-urban organization and mobility, territorial governance and territorial development, as well as other approaches to the social sciences, in the contemporary issues of city and territorial governance.     

Effects of Sr2+ substitution on the crystal structure,Raman spectra,bond valence and microwave dielectric properties of Ba3-xSrx(VO4)2 solid solutions

The effects of Sr²⁺ substitution for Ba²⁺ on microwave dielectric properties and crystal structure of Ba_3-xSr_x(VO₄)₂ (0 ≤ x ≤ 3, BSVO) solid solution were investigated. Such Sr²⁺ substitution contributes to significant reduction in sintering temperature from 1400 °C to 1150 °C. Both permittivity (∑_r) and quality factor (Q × f) values decreased with increasing x value, which was determined to be related with the descending values of average polarizability and packing fraction, whereas the increase in τ_f value was explained by the decreased average VO bond length, A-site bond valence. BSVO ceramics possessed encouraging dielectric performances with ∑_r = 12.2–15.6 ± 0.1, Q × f = 44,340 - 62,000 ± 800 GHz, and τ_f = 24.5–64.5 ± 0.2 ppm/°C. Low-temperature sintering was manipulated by adding B₂O₃ as sintering additive for the representative Sr₃V₂O₈ (SVO) ceramic and only 1 wt.% B₂O₃ addition successfully contributed to a 21.7% decrease in sintering temperature to 900 °C, showing good chemical compatibility with silver electrodes, which render BSVO series and SVO ceramics potential candidates in multilayer electronic devices fabrication.     

NaWuReT-Workshop: Forschung in der Reaktionstechnik für und mit der Gesellschaft

In this article, the results of the NaWuReT (Early Career Reaction Engineers) workshop on the topic “Are we doing relevant science?” are presented. The topics “(In)surmountable hurdles for Citizen Scientists in reaction engineering?” and “Circular Economy in reaction engineering with/for society?” were discussed. Therefrom, a variety of ideas and suggestions were extracted.