Characterization and Flame-Retardant Properties of Cobalt-Coordinated Cyclic Phosphonitrile in Thermoplastic Polyurethane Composites.

Halogen-free organophosphorus flame retardants have promising application prospects due to their excellent safety and environmental protection properties. A cobalt-coordinated cyclic phosphonitrile flame retardant (Co@CPA) was synthesized via a hydrothermal method using hexachlorocyclotriphosphonitrile (HCCP), 5-amino-tetrazolium (5-AT), and cobalt nitrate hexahydrate (Co(NO3)2∙6H2O) as starting materials. The structure was characterized using Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Thermoplastic polyurethane (TPU) composites were prepared by incorporating 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphame-10-oxide (ODOPB), Co@CPA, and silicon dioxide (SiO2) via melt blending. The flame-retardant performance and thermal stability of the TPU composites were evaluated through limiting oxygen index (LOI), vertical combustion (UL-94), TG, and cone calorimetric (CCT) tests. SEM and Raman spectroscopy were used to analyze the surface morphology and structure of the residual carbon. A synergistic flame-retardant effect of ODOPB and Co@CPA was observed, with the most effective flame retardancy achieved at a TPU:ODOPB:Co@CPA:SiO2 ratio of 75:16:8:1. This composition exhibited an LOI value of 26.5% and achieved a V-0 rating in the UL-94 test. Furthermore, compared to pure TPU, the composite showed reductions in total heat release, CO production, and CO2 production by 6.6%, 39.4%, and 48.9%, respectively. Our research findings suggest that Co@CPA demonstrates outstanding performance, with potential for further expansion in application areas. Different metal-based cyclic phosphonitrile compounds are significant in enriching phosphorus-based fine chemicals.

A Richer Vocabulary of Chinese Personality Traits: Leveraging Word Embedding Technology for Mining Personality Descriptors.

This study uses a data-driven approach to mine the distribution of personality traits among Chinese people in the Chinese social context. Based on the hypothesis of personality lexicology, word embedding technology was employed in machine learning to mine personality vocabulary from Tencent's word embedding database. More than 10,000 Chinese personality descriptors were extracted and analyzed using Gaussian Mixture Model Cluster and Hierarchical clustering analysis. The data was collected from 658 Chinese people randomly from all parts of China through an online questionnaire method. The results reveal six personality traits in the Chinese context, expanding the personality thesaurus and providing examples to illustrate each trait. The findings coincide with previous research on the five-factor model, which partially describes the personality traits of Chinese people, but does not offer a complete explanation of their typical social behavior patterns. Additionally, the study supports the notion of cultural particularity in personality traits. The approach used in this study offers a richer personality vocabulary than traditional personality mining methods, and word embedding technology captures richer semantic information in Chinese. The six Chinese personality traits identified in this study will also be used to explore how to quantify and evaluate personality traits based on word embedding and personality descriptors.

Optimizing pre-carbonization temperature of sesame residue for hierarchical porous carbon materials in high-performance supercapacitor applications.

In this paper, the sesame residue, a common biomass waste, was used as a precursor to synthesize N,O co-doped porous carbon materials via a simple pre-carbonization and KNO3activation two-step strategy. The apparent morphology and supercapacitor performance of the obtained materials can be regulated by changing the pre-carbonization temperature (0 °C, 300 °C and 600 °C). The consequences demonstrate that a large number of C-C and C-O bonds in sesame residue undergo cleavage and form abundant pore structure at the pre-carbonization temperature of 300 °C. After KNO3activation, the material has a moderate specific surface area (1073.4 m2g-1) and affluent heteroatom content (N: 7.52 at%, O: 17.65 at%). As a result, the SS-300 electrode displays exceptional capacitive performance (specific capacitance up to 312.7 F g-1at 0.5 A g-1) and outstanding cyclic stability (capacitance retention reaching 98.3% at 10 A g-1after 8000 charge-discharge cycles). Moreover, the symmetric supercapacitor assembled by SS-300 exhibits high energy densities in both 6 M KOH (4.58 Wh kg-1) and 1 M Na2SO4(15.60 Wh kg-1), highlighting the potential of this material for energy storage applications.

Formulation improvement of a concentrated enzyme detergent for high-speed rail trains through life cycle assessment methodology.

High-speed rail has been operating in more than 25 countries (mainly in Asia, Europe and North America), and has become an important part of global economic development. However, the cleaning and maintenance of high-speed rail is a comprehensive task, which may easily cause environmental pollution. This study aims to analyze and improve the sustainability of the formulation and production process of a concentrated complex enzyme detergent used as the maintenance agent for high-speed trains via the life cycle assessment (LCA) method. The eFootprint software system with built-in China, European and Swiss Ecoinvent databases was used to establish the LCA model with the system boundary being from cradle to gate. The LCA model showed that the production of 1 kg of concentrated detergent generates the global warming potential of 2.53 kg CO2 eq, and other environmental emissions including acidification potential of 0.01 kg SO2 eq, eutrophication potential of 3.76E-03 kg PO43-eq, inhalable inorganic matter of 3.17E-03 kg PM2.5 eq, ozone depletion potential of 5.3E-06 kg CFC-11 eq, photochemical ozone formation potential of 3.44E-03 kg NMVOC eq, primary energy demand of 3.17 MJ, abiotic depletion potential of 4.97E-6 kg antimony eq, and water use of 0.84 kg. LCA results are not strongly dependent to the assumptions of the research, and the uncertainties of LCA results are between 8 and 16%, which is mainly due to the regional differences in technology sources, the year of technical data collection, and the representativeness of technology collection companies. Carbon footprint analysis showed that the production processes of enzyme stabilizer (glycerol) and surfactants contributed the most, while changes in power consumption during production and transportation distance of raw materials had limited effect on total carbon emissions. Therefore, the formulation of the concentrated complex enzymatic detergent was improved based on the LCA results. The new formulations with less enzyme stabilizer showed similar detergency to the original formulation. The new formulations could reduce carbon emissions by 5,500-9,200 tons per year and save between $4.4 and $7.4 million in annual production of 10,000 tons. Supplementary Information: The online version contains supplementary material available at 10.1007/s10668-023-03122-2.

Tailoring abundant active-oxygen sites of Prussian blue analogues-derived adsorbents for highly efficient Yb(III) capture.

The removal of rare earth elements in mineral processing wastewater is highly desirable but still challenging. In this study, three bimetallic Prussian blue analogues (PBA) and six corresponding oxides are prepared by co-precipitation and calcination methods, and then utilized to adsorb aqueous Yb(III) solution. The results of XRD, SEM, BET, and XPS indicate the successful synthesis of all the adsorbents. Among them, three PBA-oxide samples (PBO-800) exhibit the superior adsorption capacities (˃250 mg/g). The adsorption processes of Yb(III) are in accordance with the pseudo-second-order kinetic model and Langmuir model, simultaneously showing the spontaneous and endothermic thermodynamics. Moreover, PBO-800 can be reused after alkaline solution regeneration with less than 10% degradation after five consecutive adsorption-desorption cycles. More importantly, PBO-800 exhibits the impressive separation selectivity of Yb(III) and most light rare earth ions (e.g., 5.51 of Yb/La, 4.03 of Yb/Pr), as well as the selectivity of Yb(III) and alkali metal ions (e.g., 300.5 of Yb/Na, 256.2 of Yb/Ca). According to the characterization analysis and DFT calculation, the adsorption mechanism of Yb(III) by PBO-800 is mainly attributed to the strong interaction between the abundant active-oxygen sites and Yb(III), and the significant electrostatic attraction.

Tuning the Dual Active Sites of Functionalized UiO-66 for Selective Adsorption of Yb(III).

The recovery of rare earth elements (REEs) from discharged electronic devices or mineral waste water is highly essential but still facing challenges. In this work, two amino-functionalized carboxyl-UiO-66 (UiO-66-COOH-TETA and UiO-66-(COOH)2-ED) prepared via the postmodification method were employed as the adsorbents for Yb(III) capture. The experimental results revealed their superior adsorption capacities of 161.5 and 202.6 mg/g, respectively. Meanwhile, their adsorption processes can be described by the pseudo-second-order kinetic model and Langmuir model. Effects of initial pH and temperature on adsorptions were systematically evaluated, affording an optimal operating condition (i.e., pH of 5.5-6, T of 65 °C, t of 10 h). Moreover, the fabricated materials exhibited great reusability after five adsorption-regeneration cycles. UiO-66-COOH-TETA demonstrated good separation selectivity for Yb(III) over light REEs (i.e., 3.98 of Yb/Ce, 3.51 of Yb/Nd). Based on the density functional theory calculations and characterization analysis (XPS, Zeta, mapping, and IR), the adsorption mechanisms were mainly attributed to significant electrostatic attraction and strong surface complexation between N and O sites and Yb(III).

Two birds with one stone: facile fabrication of an iron-cobalt bimetallic sulfide nanosheet-assembled nanosphere for efficient energy storage and hydrogen evolution.

Transition metal sulfides are widely regarded as the most promising electrode materials for supercapacitors. Herein, we utilized a straightforward electrodeposition method to prepare an iron-cobalt bimetallic sulfide nanosheet-assembled nanosphere on nickel foam (FeCo2S4/NF). The synergistic effect between bimetals and the unique three-dimensional structure significantly improved its capacitive performance. As a result, it demonstrated a remarkable specific capacitance, brilliant long-term stability and acceptable rate capability. Moreover, FeCo2S4/NF and active carbon (AC) were used to assemble an asymmetric supercapacitor (ASC), and FeCo2S4//AC displays a maximum energy density of 29.4 W h kg-1 at 800 W kg-1. Moreover, when adopted as an electrocatalyst for the hydrogen evolution reaction (HER), FeCo2S4/NF exhibited excellent catalytic properties (η10 = 165 mV). Our research provides a valuable insight into the multidisciplinary integration of high-performance energy materials.

Preparation of N/O co-doped porous carbon by a one-step activation method for supercapacitor electrode materials.

Heteroatom-doped carbon materials used in supercapacitors are low in cost and demonstrate extraordinary performance. Here, ethylenediamine tetraacetic acid (EDTA) with intrinsic N and O elements is selected as a raw material for the preparation of heteroatom self-doped porous carbon. Furthermore, N/O self-doped porous carbon with a large surface area has been successfully prepared using K2CO3 as the activator. The derived sample with a 1 : 2 molar ratio of EDTA to K2CO3 (EK-2) demonstrates a porous structure, rich defects, a large surface area of 2057 m2 g-1 and a micropore volume of 0.25 cm3 g-1. Benefiting from high N content (2.89 at%) and O content (10.75 at%), EK-2 exhibits superior performance, including high capacitance of 325 F g-1 at 1 A g-1 and outstanding cycling stability with 96.8% retention after 8000 cycles at 10 A g-1, which strongly confirms its immense potential toward many applications. Additionally, the maximum energy density of EK-2 reaches was 17.01 W h kg-1 at a power density of 350 W kg-1 in a two-electrode system. This facile and versatile strategy provides a scalable approach for the batch synthesis of N/O co-doped carbonaceous electrode materials for energy storage.

COVID-19's impacts on the scope, effectiveness, and interaction characteristics of online learning: A social network analysis.

The COVID-19 outbreak brought online learning to the forefront of education. Scholars have conducted many studies on online learning during the pandemic, but only a few have performed quantitative comparative analyses of students' online learning behavior before and after the outbreak. We collected review data from China's massive open online course platform called icourse.163 and performed social network analysis on 15 courses to explore courses' interaction characteristics before, during, and after the COVID-19 pan-demic. Specifically, we focused on the following aspects: (1) variations in the scale of online learning amid COVID-19; (2a) the characteristics of online learning interaction during the pandemic; (2b) the characteristics of online learning interaction after the pandemic; and (3) differences in the interaction characteristics of social science courses and natural science courses. Results revealed that only a small number of courses witnessed an uptick in online interaction, suggesting that the pandemic's role in promoting the scale of courses was not significant. During the pandemic, online learning interaction became more frequent among course network members whose interaction scale increased. After the pandemic, although the scale of interaction declined, online learning interaction became more effective. The scale and level of interaction in Electrodynamics (a natural science course) and Economics (a social science course) both rose during the pan-demic. However, long after the pandemic, the Economics course sustained online interaction whereas interaction in the Electrodynamics course steadily declined. This discrepancy could be due to the unique characteristics of natural science courses and social science courses.

Adsorption of low concentrations of bromide ions from water by cellulose-based beads modified with TEMPO-mediated oxidation and Fe(III) complexation.

Due to strong activity, it is very difficult to remove low concentrations of bromide in medical wastewater by traditional method, thus highly effective and greener adsorbents should be utilized to design. In this work, the cellulose beads (CBs) were modified by the TEMPO-mediated oxidation and then bonded with Fe3+ to fabricate Fe(III)-complexed carboxylated cellulose beads (Fe-CCBs) adsorbents. Structure and properties of Fe-CCBs were analyzed using Energy dispersive spectrum (EDS), Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), total acidity and basicity groups, X-ray diffraction (XRD), N2 adsorption-desorption and Thermogravimetric (TGA). Moreover, batch adsorption experiments showed that the adsorption of Br- was better consistent with general-order kinetic model and Liu isotherm model, which could also further clarify the adsorption process mechanism. Meanwhile, the results revealed that removal of Br- was a spontaneous exothermic process and was more suitable to be carried out under neutral or acidic conditions. Furthermore, the mechanism of adsorption behavior of bromide ions on Fe-CCBs was based on a combination of electrostatic attraction and outer-sphere complexation. The results of this study can provide guidance for the design of novel material adsorbents and the removal of harmful anions from aqueous solutions.

Electronic engineering of CoSe/FeSe2 hollow nanospheres for efficient water oxidation.

First-row non-precious metal-based catalysts are widely studied and recognized as potential substitutes for precious metal-based catalysts in the oxygen evolution reaction (OER) for hydrogen generation but their application remains challenging. In this study, a unique class of Co-Fe selenide hollow nanospheres (CoSe@FeSe2) is well-designed through a facile hydrothermal method. The in situ formed hybrid composites possess numerous interfaces allowing partial electron transfer via O2- bridges to optimize the adsorption feature of the reaction intermediates, *OH, *O, and *OOH, on the catalysts. The collected surface valence band spectra evidence the optimization of the intermediate adsorption and active sites. The as-synthesized CoSe@FeSe2 exhibits excellent OER activity with a low overpotential of 281 mV to drive a current density of 10 mA cm-2 and a low Tafel slope of 34.3 mV dec-1 in an alkaline electrolyte. Additionally, the advanced catalyst also shows super stability with negligible current density decay after 12 h. This work presents a prototype for the fabrication of highly efficient electrocatalysts using an electronic engineering strategy.

Fabrication of a highly dispersed/active Pd nanoparticle supported catalyst: a cation-assisted reduction method in ethylene glycol-water solution at mild temperature.

Development of sustainable routes to synthesize precious metal supported catalysts is of great importance because of their wide applications in the catalysis field. This paper reported a controllable and recyclable cation-assisted reduction route to fabricate a palladium nanoparticle supported catalyst. At 323 K, highly dispersed Pd/Al2O3-CARM was prepared through introducing M2+ (M = Mn, Zn or Cu) ions to promote the reduction of H2PdCl4 in ethylene glycol-water solution, and the residual filtrate after preparation could be recycled to prepare Pd/Al2O3 catalysts. A turnover frequency of 300 × 102 h-1 was obtained for Pd/Al2O3-CARMn in solvent-free aerobic oxidation of benzyl alcohol to benzaldehyde.

Mesoporous Carbon and Ceria Nanoparticles Composite Modified Electrode for the Simultaneous Determination of Hydroquinone and Catechol.

In this work, a novel material that was based on mesoporous carbon and ceria nanoparticles composite (MC⁻CeNPs) was synthesized, and a modified electrode was fabricated. When compared with a bare glass electrode, the modified electrode exhibited enhanced electrocatalytic activity towards the simultaneous determination of hydroquinone (HQ) and catechol (CC), which is attributed to the large specific area and fast electron transfer ability of MC⁻CeNPs. Additionally, it exhibited linear response ranges in the concentrations of 0.5⁻500 µM and 0.4⁻320 µM for HQ and CC, with detection limits (S/N = 3) of 0.24 µM and 0.13 µM, respectively. This method also displayed good stability and reproducibility. Furthermore, the modified electrode was applied to the simultaneous determination of HQ and CC in tap and lake water samples, and it exhibited satisfactory recovery levels of 98.5⁻103.2% and 98⁻103.4% for HQ and CC, respectively. All of these results indicate that a MC⁻CeNPs modified electrode could be a candidate for the determination of HQ and CC.

The Preparation, Characterization and Formation Mechanism of a Calcium Phosphate Conversion Coating on Magnesium Alloy AZ91D.

The poor corrosion resistance of magnesium alloys is one of the main obstacles preventing their widespread usage. Due to the advantages of lower cost and simplicity in operation, chemical conversion coating has drawn considerable attention for its improvement of the corrosion resistance of magnesium alloys. In this study, a calcium phosphate coating was prepared on magnesium alloy AZ91D by chemical conversion. For the calcium phosphate coating, the effect of processing parameters on the microstructure and corrosion resistance was studied by scanning electron microscope (SEM) and electrochemical methods, and the coating composition was characterized by X-ray diffraction (XRD). The calcium phosphate coating was mainly composed of CaHPO4·2H2O (DCPD), with fewer cracks and pores. The coating with the leaf-like microstructure provided great corrosion resistance to the AZ91D substrate, and was obtained under the following conditions: 20 min, ambient temperature, and no stirring. At the same time, the role of NH4H2PO4 as the coating-forming agent and the acidifying agent in the conversion process was realized, and the formation mechanism of DCPD was discussed in detail in this work.