Employing a Narrow-Band-Gap Mediator in Ternary Solar Cells for Enhanced Photovoltaic Performance.

Ternary organic solar cells (OSCs) provide a convenient and effective means to further improve the power conversion efficiency (PCE) of binary ones via composition control. However, the role of the third component remains to be explored in specific binary systems. Herein, we report ternary blend solar cells by adding the narrow-band-gap donor PCE10 as the mediator into the PBDB-T:IDTT-T binary blend system. The extended absorption, efficient fluorescence resonance energy transfer, enhanced charge dissociation, and induced tighter molecular packing of the ternary blend films enhance the photovoltaic properties of devices and deliver a champion PCE of 10.73% with an impressively high open-circuit voltage (VOC) of 1.03 V. Good miscibility and similar molecular packing behavior of the components guarantee the desired morphology in the ternary blend films, leading to solar cell devices with over 10% PCEs at a range of compositions. Our results suggest that ternary systems with properly aligned energy levels and overlapping absorption among the components hold great promises to further enhance the performance of corresponding binary ones

Characterization of Montmorillonite–Biochar Composite and Its Application in the Removal of Atrazine in Aqueous Solution and Soil

Atrazine is a widely used triazine herbicide, which poses a serious threat to human health and aquatic ecosystem. A montmorillonite–biochar composite (MMT/BC) was prepared for atrazine remediation. Biochar samples were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectrometer (XPS). Structural and morphological analysis of raw biochar (BC) and MMT/BC showed that MMT particles have been successfully coated on the surface of biochar. Sorption experiments in aqueous solution indicated that the MMT/BC has higher removal capacity of atrazine compared to BC (about 3.2 times). The sorption of atrazine on the MMT/BC was primarily controlled by both physisorption and chemisorption mechanisms. The amendment of MMT/BC increased the sorption capacity of soils and delayed the degradation of atrazine. Findings from this work indicate that the MMT/BC composite can effectively improve the sorption capacity of atrazine in aquatic environment and farmland soil and reduce the environmental risk.Characterization of Montmorillonite–Biochar Composite and Its Application in the Removal of Atrazine in Aqueous Solution and SoilpublishedVersio

Comparison of properties of biochar produced from different types of lignocellulosic biomass by slow pyrolysis at 600 °C

Production of biochar from corn cob and corn stalk has gained great interest for efficient waste management with benefits of improving soil properties, increasing crop productivity, and contributing to carbon sequestration. This study investigated slow pyrolysis of corn cob and corn stalk at 600 °C to characterize yields and properties of products, with focus on solid biochar. Spruce wood, a rather well studied woody biomass, was also included for comparison purposes. It was observed that yields of biochar and condensates from corn cob, corn stalk, and spruce wood were comparable. However, gas release profiles and yields from the three biomasses were quite different, which is mainly related to the different chemical compositions (i.e., hemicellulose, cellulose, lignin, and inorganic species) of the studied raw feedstocks. The produced biochars were analyzed for proximate analysis, CHNS-elemental analysis, specific surface area and specific pore volume for pores in the nm-range, inorganic composition, solid functional groups, and aromaticity. The corn cob and corn stalk biochar presented significantly higher concentration of inorganic elements, especially P and K, favoring soil application. The SEM analysis results showed that the spruce wood biochar has different microstructure than corn cob and corn stalk biochars. Condensates and light gases, as by-products from biochar production, contained over 50% of the energy and 40% of the total carbon of the initial biomass. Utilization of the condensates and light gases as valuable resources is therefore critical for improving environmental and energy benefits of the biochar production process.Comparison of properties of biochar produced from different types of lignocellulosic biomass by slow pyrolysis at 600 °CpublishedVersio

Substitution Effect on Thiobarbituric Acid End Groups for High Open-Circuit Voltage Non-Fullerene Organic Solar Cells

Recent advances in non-fullerene acceptors (NFAs) have resulted in significant improvement in the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In our efforts to boost open-circuit voltage (VOC) for OSCs, the molecular design employing thiobarbituric acid (TBTA) end groups and an indacenodithieno[3,2-b]thiophene (IDTT) core gives rise to NFAs with significantly raised lowest unoccupied molecular orbital (LUMO) energy level, which, when paired with PCE10, can achieve VOC's over 1.0 V and decent PCEs that outperform the equivalent devices based on the benchmark ITIC acceptor. While the use of a TBTA end group is effective in tuning energy levels, very little is known about how the alkyl substitution on the TBTA group impacts the solar cell performance. To this end, TBTA end groups are alkylated with linear, branched, and aromatic sidechains to understand the influence on thin-film morphology and related device performances. Our study has confirmed the dependence of solar cell performance on the end-group substituents. More importantly, we reveal the presence of an ideal window of crystallinity associated with the medium-length hydrocarbon chains such as ethyl and benzyl. Deviation to the shorter methyl group makes the acceptor too crystalline to mix with the polymer donor and form proper domains, whereas longer and branched alkyl chains are too sterically bulky and hinder charge transport due to nonideal packing. Such findings underline the comprehensive nature of thin-film morphology and the subtle end-group effects for the design of non-fullerene acceptors

What Matters for Regional Economic Resilience Amid Multi Shock Situations: Structural or Agency? Evidence from Resource-Based Cities in China

This paper contributes to the study of regional economic resilience by analyzing the characteristics and mechanisms of resilience under different shock situations. The paper focuses on the resistance dimension of resilience and analyzes the mechanisms of influence from structural and agency-based factors. Our findings reflect that the regional economic resilience characteristics of resource-based cities in China in response to the 2008 financial crisis and the COVID-19 pandemic vary significantly. We find that the economic resilience has positive spatial autocorrelation characteristics. The regions with strong ability to deal with the shocks can promote resistance in the surrounding regions through their spatial spillover effect. Both structural and agency-based factors play significant roles in regional economic resilience under different shock situations, but the direction of the effect varies significantly. The agency-based factors have a more important role in regional economic resilience. The findings suggest that the nature of different shock situations deserves greater attention in the analysis of regional economic resilience. The mechanisms of structural and agency-based factors may change under different shock situations, and the spatial correlation characteristics of regional economic resilience and the spatial spillover effects should be taken into consideration

Research on process and simulation of the isothermal forging of a spur bevel gear

This paper took the lead in applying isothermal forging technology to form a spur bevel gear in a single operation. According to the isothermal forging process, the forging part drawing of the spur bevel gear was defined. The 20CrMnTi was chosen as the gear materials. A closed-die structure was used in the forging process. Then, the model of the dies and workpiece were built by UG software. After the models was imported into DEFORM-3D, the simulation of the isothermal forging process of the bevel gear was executed. Through simulation, the shape of the gear, the distributions of effective stress and strain, the forming load of the dies, the laws of metal flow and the filling of the metal during the forging process were gained and thoroughly discussed. The results revealed that the full forging process can be divided into four periods and precision spur bevel gear can be obtained without causing under-filling and folding defect by using the isothermal forging with closed-die forging structure, which provides guidance to manufacturing the spur bevel gear

Substitution Effect on Thiobarbituric Acid End Groups for High Open-Circuit Voltage Non-Fullerene Organic Solar Cells.

Recent advances in non-fullerene acceptors (NFAs) have resulted in significant improvement in the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In our efforts to boost open-circuit voltage (VOC) for OSCs, the molecular design employing thiobarbituric acid (TBTA) end groups and an indacenodithieno[3,2-b]thiophene (IDTT) core gives rise to NFAs with significantly raised lowest unoccupied molecular orbital (LUMO) energy level, which, when paired with PCE10, can achieve VOC's over 1.0 V and decent PCEs that outperform the equivalent devices based on the benchmark ITIC acceptor. While the use of a TBTA end group is effective in tuning energy levels, very little is known about how the alkyl substitution on the TBTA group impacts the solar cell performance. To this end, TBTA end groups are alkylated with linear, branched, and aromatic sidechains to understand the influence on thin-film morphology and related device performances. Our study has confirmed the dependence of solar cell performance on the end-group substituents. More importantly, we reveal the presence of an ideal window of crystallinity associated with the medium-length hydrocarbon chains such as ethyl and benzyl. Deviation to the shorter methyl group makes the acceptor too crystalline to mix with the polymer donor and form proper domains, whereas longer and branched alkyl chains are too sterically bulky and hinder charge transport due to nonideal packing. Such findings underline the comprehensive nature of thin-film morphology and the subtle end-group effects for the design of non-fullerene acceptors

What Matters for Regional Economic Resilience Amid Multi Shock Situations: Structural or Agency? Evidence from Resource-Based Cities in China

This paper contributes to the study of regional economic resilience by analyzing the characteristics and mechanisms of resilience under different shock situations. The paper focuses on the resistance dimension of resilience and analyzes the mechanisms of influence from structural and agency-based factors. Our findings reflect that the regional economic resilience characteristics of resource-based cities in China in response to the 2008 financial crisis and the COVID-19 pandemic vary significantly. We find that the economic resilience has positive spatial autocorrelation characteristics. The regions with strong ability to deal with the shocks can promote resistance in the surrounding regions through their spatial spillover effect. Both structural and agency-based factors play significant roles in regional economic resilience under different shock situations, but the direction of the effect varies significantly. The agency-based factors have a more important role in regional economic resilience. The findings suggest that the nature of different shock situations deserves greater attention in the analysis of regional economic resilience. The mechanisms of structural and agency-based factors may change under different shock situations, and the spatial correlation characteristics of regional economic resilience and the spatial spillover effects should be taken into consideration

Emerging Applications of Silica Nanoparticles as Multifunctional Modifiers for High Performance Polyester Composites

Nano-modification of polyester has become a research hotspot due to the growing demand for high-performance polyester. As a functional carrier, silica nanoparticles show large potential in improving crystalline properties, enhancing strength of polyester, and fabricating fluorescent polyester. Herein, we briefly traced the latest literature on synthesis of silica modifiers and the resultant polyester nanocomposites and presented a review. Firstly, we investigated synthesis approaches of silica nanoparticles for modifying polyester including sol-gel and reverse microemulsion technology, and their surface modification methods such as grafting silane coupling agent or polymer. Then, we summarized processing technics of silica-polyester nanocomposites, like physical blending, sol-gel processes, and in situ polymerization. Finally, we explored the application of silica nanoparticles in improving crystalline, mechanical, and fluorescent properties of composite materials. We hope the work provides a guideline for the readers working in the fields of silica nanoparticles as well as modifying polyester