A Two Step Synthesis Route of WC Nanopowders

Here, a novel molten salt route to synthesize ceramic WC nanopowders was presented. Compared to the traditional synthesis procedures, this method is relatively low cost involving two-step synthesis route. In the argon atmosphere at 650 oC, the powders were the mixed WC and W2C phases. These synthesized powders were transferred to a small crucible (30 mL) containing molten salt, which were put into a 500 mL crucible with some carbon powder in it as reducing atmosphere, followed by maintaining the reaction temperature at 1100 °C for 1 h. The phase purity and composition were characterized by the powder X-ray diffractometer (XRD). It was found that W2C was transformed thoroughly into WC, which indicated the successful synthesis of WC powders using this method. The mechanism of the reaction process in molten salt has been discussed finally. The thermogravimetric analysis indicated that the as-prepared samples showed good thermal stability and oxidation resistance in high temperature. The methodology reported in this work was fundamentally important, which may find potential industrial applications

Global urban environmental change drives adaptation in white clover.

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Comparing forceps and self-assembled intraocular rare earth magnet in removing metallic intraocular foreign bodies in 25-guage vitrectomy

Abstract Purpose To compare the efficacy and efficiency of self-assembled intraocular rare earth magnet and forceps in removing intraocular foreign bodies(IOFBs) undergoing 25-gauge(G) pars plana vitrectomy. Methods A total of 30 patients with metallic IOFB underwent 25-G PPV were enrolled into this study. Self-assembled intraocular rare earth magnet were used in 15 patients(bar group), and forceps were used in 15 patients(forceps group). Success rate of removing IOFB, time taken to remove IOFB, incidence of IOFB slippage and fall, iatrogenic retinal damages were compared between the two groups. Results There was no significant difference in success rate of removing IOFBs between the groups(93.3% and 100%, P > 0.99). The median time taken of removing FB was significantly shorter in bar group than in forceps group(112 and 295 s, P = 0.001). None of the patients in bar group had IOFB slippage and fall, or related iatrogenic retinal damage in the process of removal. In forceps group, IOFB slippage and fall during removal were observed in 7 of 15(47.6%) patients, related iatrogenic retinal injuries were recorded in 6 of 15(40.0%) patients, both were significantly higher than bar group(P = 0.003 and P = 0.017, respectively). Conclusions Compared with forceps, the assembled intraocular magnet can greatly reduce the possibility of IOFB slippage and fall, prevent related iatrogenic retinal damage, and shorten the time taken to remove IOFB. The assembled intraocular magnet can be an useful tool in removing metallic IOFBs in PPV

Earthquake-resistant performance investigation for rural buildings in Zhongxiang area, China

We carried out a census of the rural residential buildings of Zhongxiang area’s 17 towns. Next, we conducted a sample survey in four townships: Huji, Shipai, Zhangji, and Jiuli. According to the census and sample survey data of the rural residence buildings, we evaluated the quality and earthquake-resistant performance of the rural buildings for the various local rural residential structural types. The results showed that there are four main factors affecting the seismic performance of the local rural residences: (1) Foundations are not made appropriately (such as by compaction or some other fill) but are built directly in the farming soil. (2) Seismic measures are not completely implemented. Structure construction measures are not in place at the junction of the vertical and horizontal wall. The vertical wall joints are not the result of the same masonry techniques as the horizontal joints. There are no lintels above the door and window openings, or if there are any, the length of the lintels is less than 240 mm. (3) The brick masonry wall has low strength. The greatest housing wall mortar strength is between M0. 4–1.5, much lower than the strength of the brick. (4) The building material and construction quality are poor. The quality of the mortar masonry wall is poor. The cracks between the bricks are uneven, even in the seams

An Evaluation Framework for Online Courses Based on Sentiment Analysis Using Machine Learning

Online course evaluation is critical to both course selection and teaching effectiveness for students and teachers. However, the current online course evaluation methods have been criticized for neglecting learners’ needs and their inefficiency. Therefore, a course evaluation framework based on sentiment analysis using machine learning is proposed in this study to analyze a large number of online course review comments from learners. Initially, massive open online course review comments were collected through web crawling. Then, sentence- and aspect-based sentiment analyses were performed. Finally, a list of aspect terms that reflected the learners’ requirements was compiled based on the model-generated outcomes. The model was utilized to evaluate an online intellectual property law online course. Results demonstrate that the training models built in this study achieve over 90% accuracy and that 90%–95% of learners are satisfied with the intellectual property law online course. The learners are particularly satisfied with the teacher’s teaching style and course schedule. However, the models also highlight the insufficient interactivity in the class and the scarcity of novel course cases. The proposed framework provides a learner-centric approach to evaluating online courses, thereby enhancing the credibility of online course evaluation. This framework also serves as a practical reference for online course recommendation and construction