Science achievement and the factors related to it are frequently discussed in science education community. However, less researchers tend to consider student achievement in other subjects, especially ...reading and mathematics as included in the Programme for International Student Assessment (PISA). This research examined the relationship between student achievement in reading, mathematics, and science. Based on the theoretical analysis, we proposed several hypotheses that students' reading achievement can influence their mathematics achievement, reading achievement can influence science achievement, and mathematics achievement can influence science achievement, and we can use a triangular model to represent such relationship. To test the hypotheses, we used the dataset of PISA 2018 as the data source, selected 12,058 Chinese students as the participants, and employed Structural Equation Modelling (SEM) for data analysis. The results confirmed the hypotheses. Our findings indicated that reading and mathematics were important predictors of science achievement, and the effects of reading significantly exceeded mathematics. We, therefore, concluded that reading should be more important than mathematics and received with more concern in science learning. The inconsistency of the results in this research with previous works is also discussed below.
In recent years, research on students' scientific competencies has generated much discussion. According to the PISA 2015 Assessment and Analytical Framework, both scientific competencies and ...attitudes towards science - interest in science, valuing scientific approaches to enquiry (or epistemological beliefs about science), and environmental awareness - are integral aspects of scientific literacy. However, few studies have focused on the relationships between them. This article examines how students' scientific competencies are affected by their attitudes. Based on a theoretical analysis, the present study argues that the three attitudinal factors have a direct impact on scientific competencies, interest has an immediate influence on the other two attitudes, and epistemological beliefs are directly affected by environmental awareness. To test this hypothesis, a model was constructed to verify such relationships. PISA 2015 assessment instruments were used for data collection. The participants were 25,658 students from different parts of China, containing Beijing, Shanghai, Jiangsu, Guangdong, Taiwan, Hong Kong, and Macao. Structural Equation Modelling (SEM) was employed for data analysis. The results confirmed our hypothesis. The way in which Chinese students' attitudes affected their scientific competencies did not differ (to a statistically significant level) by gender or district. The limitations and implications of this research are discussed below.
Understanding the nature of science (NOS) is an important goal of science education, and textbooks are a key factor in shaping students' conceptions of NOS. In this study, we analysed NOS represented ...in middle school chemistry textbooks in the Chinese mainland. The selected materials were three most commonly adopted textbook series, which were published in 2001, 2001, and 2012. The analysis was conducted from 11 aspects - empirical, inferential, creative, theory-driven, tentative, myth of 'the scientific method', scientific theories, scientific laws, social dimensions of science, social and cultural embeddedness of science, limitations of science - to determine the distribution of different representation types (explicit-informed, implicit-informed, implicit-naïve, and explicit-naïve) in each NOS aspect in each textbook series. Textbook analysis results indicated that each textbook series had mixed conceptions of NOS and most NOS representations were informed and implicit. The frequencies of NOS representations in the selected textbook series were roughly identical; however, the last two textbook series had relatively higher error rates than the first one. Moreover, there was an overall imbalance in the representations of NOS aspects. Our findings, combined with previous studies, were also discussed.
The normal operation of lithium‐ion batteries (LIBs) at ultralow temperature (<−40 °C) is significant for cold‐climate applications; however, their operation is plagued by the low capacity of the ...conventional intercalation cathodes due to their sluggish kinetics and the slow solid diffusion of Li+ in their frameworks. Here, it is demonstrated that amorphization is an effective strategy to promote the low‐temperature dynamics of cathodes by relieving the blocking effect of a dense lattice structure on ion transport under cryogenic conditions. As a result, due to the decreased charge transport impedance and enhanced Li+ diffusion rate, the obtained covalent amorphous polymer (CAP) with an abundance of pyrazine and carbonyl active sites displays a remarkably outstanding specific capacity of 141 mAh g−1 at −80 °C, which is superior to its structural analog, a covalent crystalline polymer (43.8 mAh g−1). Furthermore, 84.7% of the initial capacity of the CAP can be retained after 500 cycles of charge and discharge at −60 °C. Molecular dynamic simulations show that the channel‐rich amorphous structure is highly conducive for lithium ions to diffuse quickly in the interstitial space of organic solids. This work provides an effective strategy regarding the amorphization of crystalline cathodes to develop low‐temperature (Low‐T) batteries.
Amorphization is an effective strategy to promote low‐temperature dynamics of cathodes by promoting fast charge transfer at the electrolyte–electrode interface and relieving the blocking effect of dense lattice structure on ion transport under cryogenic conditions. The synthesized amorphous organic electrode exhibits an unprecedented specific capacity of 141 mAh g−1 at an ultralow temperature of −80 °C.
Effective recycling of spent Li metal anodes is an urgent need for energy/resource conservation and environmental protection, making Li metal batteries more affordable and sustainable. For the first ...time, we explore a unique sustainable healable lithium alloy anode inspired by the intrinsic healing ability of liquid metal. This lithium alloy anode can transform back to the liquid state through Li-completed extraction, and then the structure degradation generated during operation could be healed. Therefore, an ultralong cycle life of more than 1300 times can be successfully realized under harsh conditions of 5 mA h cm–2 capacitance by a process of two healing behaviors. This design improves the sustainable utilization of Li metal to a great extent, bringing about unexpected effects in the field of lithium-based anodes even at an unprecedentedly high discharge current density (up to 25 mA cm–2) and capacity (up to 50 mA h cm–2).
Solid composite electrolytes (SCEs) synergize inorganic and polymer merits for viable commercial application. However, inferior filler–polymer interfacial stability ultimately leads to the ...agglomeration of inorganic particles and greatly impedes Li+ migration. Herein, triethoxyvinylsilane (VTEO) is employed to form a strong chemical interaction between poly(vinylene carbonate) (PVC) and montmorillonite (MMT) via in situ solidification, which eliminates the agglomeration and improves interfacial compatibility. Consequently, the obtained solid composite electrolytes (PVC-s-MMT) achieve increased Li+ conductivity (0.4 mS cm–1 at 25 °C), enhanced transference number (0.74), and increased oxidation potential (5.2 V). The Li/PVC-s-MMT/LiFePO4 cells exhibit outstanding cycling performance (>99.5% after 600 cycles) at 1C at room temperature. Moreover, density functional theory (DFT) calculations are applied to uncover the fast interfacial conducting channels of PVC-s-MMT. Our work provides a feasible in situ synthesis method to prepare agglomeration-free SCEs, which is highly compatible with existing battery production processes of liquid electrolytes.
The environmentally friendly, low toxic or nontoxic, and functional material to solve the needs of agricultural development are the key to current scientific research. Here, acrylic thiazole ...copolymer clusters (AcTPCs) were successfully synthesized by using common methacrylic acid as an induced source, combined with the antimicrobial monomers acrylic thiazole (AcT) and Zn2+, which are of great value for agricultural applications. Utilizing the “cluster effect,” under the synergistic effect of the fully exposed active ingredients, they not only have long‐lasting antimicrobial effects against bacteria and fungi, but also promote the growth of plant roots and stems and increase the chlorophyll content. Therefore, this study provides a novel, environmental‐friendly, and low‐toxic method to solve the microbe infection problem, which is expected to improve the agriculture.
The environmentally friendly and low‐toxic acrylic thiazole copolymer clusters (AcTPCs) were constructed to inhibit the growth of bacteria and fungi. It has long‐acting antibacterial efficiency more than 7 days and promotes the growth of corn roots, stems, leaves, and so on, which is expected to solve the microbe infection problem and improve the agriculture.
Multispectral image change detection is an important application in the field of remote sensing. Multispectral images usually contain many complex scenes, such as ground objects with diverse scales ...and proportions, so the change detection task expects the feature extractor is superior in adaptive multi-scale feature learning. To address the above-mentioned problems, a multispectral image change detection method based on multi-scale adaptive kernel network and multimodal conditional random field (MSAK-Net-MCRF) is proposed. The multi-scale adaptive kernel network (MSAK-Net) extends the encoding path of the U-Net, and designs a weight-sharing bilateral encoding path, which simultaneously extracts independent features of bi-temporal multispectral images without introducing additional parameters. A selective convolution kernel block (SCKB) that can adaptively assign weights is designed and embedded in the encoding path of MSAK-Net to extract multi-scale features in images. MSAK-Net retains the skip connections in the U-Net, and embeds an upsampling module (UM) based on the attention mechanism in the decoding path, which can give the feature map a better expression of change information in both the channel dimension and the spatial dimension. Finally, the multimodal conditional random field (MCRF) is used to smooth the detection results of the MSAK-Net. Experimental results on two public multispectral datasets indicate the effectiveness and robustness of the proposed method when compared with other state-of-the-art methods.
•The n-heptane spray was treated by nickel foam with diverse air and heating.•The flow and heat transfer characteristics of fuel spray were greatly improved.•A criterion number was set to evaluate ...the atomization performance of all sprays.
Air-assist atomization is the main way to organize the liquid fuel combustion in gas turbine. The atomization and vaporization enhancement of n-heptane was investigated experimentally with porous media (PM) process, revealing the effects of atomizing air temperature, air-to-liquid mass ratio, and porous media heating power. The nickel foam has over 0.9 porosity, large specific surface area and excellent thermal conductivity make it the best choice of porous media. The n-heptane spray processed by nickel foam may present cohesion or sputtering effusion, and increasing air temperature, air flow rate or heating power can avoid liquid cohesion. Although the average velocity of the droplets is reduced significantly by nickel foam, the spray with porous media can obtain the Sauter mean diameter (SMD) about 15 μm, equal to the no-PM case. Porous media heating performs remarkable improvement on the droplet size and distribution. The PM also results in obvious rises of spray temperature and the mass flow rate of n-heptane vapor. The air temperature and heating power perform with stronger than air flow rate. It is found by calculating the volumetric heat transfer power of nickel foam that PM substantially enhanced the fluid–solid heat transfer to six times with the addition of air temperature and porous media heating. A criterion number, θT was proposed to evaluate the atomization and vaporization, and 400 K is the basic condition for better atomization. Both high air temperature and heating power may does not result in further improvement of θT which presents similar peak values around 7.
ABSTRACT Fe(II) is of great importance in iron-based advanced oxidation processes. However, traditional methods to maintain Fe(II) concentration, such as the addition of chelating agents or reducing ...agents, may lead to an increase in chemical oxygen demand of secondary pollution. Therefore, in this study, iron sulfides, namely ferrous sulfide (FeS), pyrite (FeS2), and sulfidated nanoscale zero-valent iron (S-nZVI), were applied for not only the regeneration of Fe(II) but also the direct dissolution of Fe(II). Nanoscale calcium peroxide (nCaO2) was synthesized and used as the oxidant. The removal of 1,2-dichloroethane (1,2-DCA) were significantly promoted from 8.8 to 98.2, 79.2, and 80.8% with the aid of FeS, FeS2, and S-nZVI within 180 min, respectively. The dominant reactive oxygen species were demonstrated and their steady-state concentrations were quantified. Besides, the dechlorination of 1,2-DCA reached 90.4, 69.5, and 83.9% in nCaO2/Fe(III) systems coupled with FeS, FeS2, and S-nZVI, respectively. All three systems had high tolerance to the complex water conditions, of which FeS-enhanced nCaO2/Fe(III) system displayed the best performance, which could be recommended to put into practice for the remediation of 1,2-DCA contaminated groundwater.
