Materials
·
2024
·Vol. 17
·期 8
·1812
·
IF 3.1
Wanlu Xu,Wenwu Wang,Xiaoshan Zhang,Ping Yu
Positive temperature coefficient of electrical resistivity (PTCR) materials with low Curie temperature have been paid increasing attention lately. In this study, PTCR materials with a Curie temperature of approximately −15 °C were investigated by La3+doping Ba0.55Sr0.45TiO3ceramics. It could be expected to meet the requirements of thermal management systems for low-temperature control. In addition, a trace amount of Bi0.5Na0.5TiO3(BNT) was employed to improve the resistivity and the PTCR performance. A significant PTCR effect was achieved with a high resistivity jump of nearly four orders of magnitude, a high temperature coefficient of ~28.76%/°C, and a narrow transition temperature span of 22 °C in the (Ba0.55Sr0.45)0.99875La0.00125Ti1.01O3-0.0025Bi0.5Na0.5TiO3ceramics. The PTCR enhancement mechanism of BNT is discussed.
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Qingke Wang,Qin Wang,Yanqiang Wei,Jingyu Chen,Tangyin Cui,Haibo Yan,Jinzhe Duan,Kai Li,Jie Ding
In this study, two types of high-temperature adhesives were prepared using molybdenum-modified phenolic resin (MoPF) as the matrix and TiB 2 or TiB 2 /ZrSi 2 particles as active fillers for bonding Al 2 O 3 ceramic substrates. Shear strength testing, thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to investigate the bonding properties, thermal properties, microstructure, compositional evolution, and bonding mechanism of the adhesives. The results demonstrate that MoPF-TiB 2 /ZrSi 2 adhesive exhibits superior bonding properties than MoPF-TiB 2 adhesive. It is noteworthy that the incorporation of ZrSi 2 can mitigate the internal stress induced by rapid volume expansion of the adhesive, and ensuring high density and mechanical strength through the generation of ZrB 2 and ZrTiO 4 , which effectively prevents the sudden decline in bonding performance beyond 1200℃. The mechanical strength of the adhesive can still be maintained at 31.5 MPa after treatment at 1400℃.
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JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2011
·Vol. 49
·期 12
·2755-2760
·
IF 3.894
Jing Xu,Yuhong Ma,Jingyi Xie,F.J. Xu,Wantai Yang
A universal photoassisted pathway to functionalize polymeric surfaces is presented by transferring the inert surface sp 3 C H bonds into reactive groups, such as SO 3 H, NH 2 , SH, and COOH. The proposed method uses acetone as photoinitiator and different phenols with a para substituent XR as the reactants. Acetone excited by UV irradiation acts as a pair of scissors cutting both the surface C H bonds of the polymer substrate and the O H bonds of phenol, leading to the formation of carbon-centered surface chain free radicals and oxygen-centered phenoxy free radicals. By coupling of these two radicals, a variety of functional X groups with an R spacer from XR species of different phenol reactants were readily bonded to the polymeric surfaces, where phenol reactants included 4-hydroxylbenzene sulfonic acid for SO 3 H, p -aminophenol and tyramine for NH 2 , 4-hydroxythiophenol for SH, and tyrosine for COOH. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
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Science Bulletin
·
2025
·
IF 21.1
Qingyu Wang,Yangyang Wan,Qichen Liu,Yida Zhang,Zhentao Ma,Zirui Xu,Pengting Sun,Gongming Wang,Hai-Long Jiang,Wenping Sun,Xusheng Zheng
Photocatalytic urea production from nitrogen (N 2 ) and carbon dioxide (CO 2 ) is a sustainable and eco-friendly alternative to the Bosch-Meiser route. However, it remains a significant challenge in developing highly efficient photocatalysts for enhancing C-N coupling to high-yield urea synthesis. Herein, we propose a multi-site photocatalyst concept to address the concern of low yield by simultaneously improving photogenerated carrier separation and reactant activation. As a proof of concept, a well-defined multi-site photocatalyst, Ru nanoparticles and Cu single atoms decorated CeO 2 nanorods (Ru-Cu/CeO 2 ), is developed for efficient urea production. The incorporation of Ru and Cu sites is crucial not only to generate high-density photogenerated electrons, but also to facilitate N 2 and CO 2 adsorption and conversion. The in situ formed local nitrogen-rich area at Ru sites increases the encounter possibility with the carbon-containing species generated from Cu sites, substantially promoting C-N coupling. The Ru-Cu/CeO 2 photocatalyst exhibits an impressive urea yield rate of 16.7 μmol g −1 h −1 , which ranks among the best performance reported to date. This work emphasizes the importance of multi-site catalyst design concept in guaranteeing rapid C-N coupling in photocatalytic urea synthesis and beyond.
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APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Songhao Yu,Guifen Tian,Liduan Li,Fei Wang,Kefeng Wang,Junyu Lei,Haijun Hao,Qinghong Xu
TpFO-PA, a novel spherical hollow mesoporous polyamide, was firstly synthesized by the reaction among 1,3,5-tris(4-aminophenyl)benzene (TAPB), furylamine and oxalyl chloride in using silica-gel nanoparticle as hard template, and the composite Cu(I)@TpFO-PA with high catalytic activities in C-N coupling reactions between (hetero)aryl bromide and (hetero)aryl amines under mild conditions was prepared basing on presence of N in the framework. A maximum activity of the catalyst with yield of C-N coupling product were about 311.9 g (product) /mol Cu(I) ·h and 95 % respectively, and the activity could be maintained at least 5 times after the catalyst was reused. The composite Cu(I)@TpFO-PA is a few heterogeneous catalysts reported in catalyzing coupling reaction between aromatic amines and brominated aromatic compounds.
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IONICS
·
2017
·Vol. 24
·期 3
·671-679
·
IF 2.062
Yan Yinglin,Li Qiaole,Ren Bing,Yang Rong,Xu Yunhua,Zhong Lisheng,Wu Hong
Hierarchical lithium iron phosphate/carbon (LiFePO 4 /C) microspheres were fabricated successfully using a facile spray drying-assisted coprecipitation method. A relatively short calcination time and a relatively low calcination temperature were adopted to prepare the hierarchical LiFePO 4 /C microspheres. The hierarchical microspheres consisted of nanoparticles with a uniform coating of amorphous carbon. The thickness of the carbon layer was controlled by the addition of glucose. The hierarchical LiFePO 4 /C microspheres exhibited a high tap density and a large specific surface area. The electrochemical properties of the sample were investigated. The sample exhibited a better rate capability and a better cyclability than the coral-like LiFePO 4 /C cathode material, and these were ascribed to the highly uniform carbon coating and the self-assembled nanoparticles.
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FOOD CHEMISTRY
·
2017
·
IF 4.529
Hua Zhou,Hai-Mei Li,Yang-Min Du,Ri-An Yan,Shi-Yi Ou,Tian-Feng Chen,Yong Wang,Li-Xin Zhou,Liang Fu
YingDe black tea is produced from crude tea prepared from leaves of Camellia sinensis var. assamica . In this work, we isolated and identified five novel flavanones, namely, amelliaone A – E ( 1 – 5 ), along with seven known compounds 6 – 12 from the ethanol extract of YingDe black tea. The structures of these five novel phenolic compounds were determined using extensive 1D and 2D nuclear magnetic resonance spectroscopy experiments. The compounds were further evaluated for antioxidant, α -glucosidase inhibitory, and cytotoxic activities. Compound 1 exhibited higher α -glucosidase inhibitory activity with a half-maximum inhibitory concentration value (IC 50 ) of 10.2 µM compared with acarbose (18.2 µM).
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POWDER TECHNOLOGY
·
2024
·
IF 4.5
Mingci Hu,Shan Qing,Xiaohui Zhang,Hao Zhang,Zichang Shi
Instability is a key issue that limits the application of magnetic nanofluids. In this study, Fe 3 O 4 @C nanoparticles were obtained using a carbon layer coated with a ferromagnetic material, which improved the instability of the magnetic nanofluid while obtaining higher thermal conductivity and showed excellent photothermal conversion performance in photothermal conversion experiments. Firstly, we prepared Fe 3 O 4 @C nanoparticles via the solvothermal method. We then compared different sizes of Fe 3 O 4 @C nanoparticles in terms of structure, composition, heat transfer characteristics and photothermal efficiency. The results indicate that contrary to the conventional belief that smaller nanoparticles have higher thermal conductivity, the 90.30 nm Fe 3 O 4 @C nanofluids has better thermal conductivity than 58.17 nm due to its larger proportion of carbon shells. In the photothermal conversion experiment for DASCs, the 58.17 nm group performed best, with the temperature of the 0.2 wt% sample reaching 45.80 °C and a photothermal efficiency of 60.32%.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Xiaoqing Wang,Ze Zhu,Zhenfeng Guo,Chenyu Mi,Ziting Huang,Yunguang Yin,Luyi Zhu,Guanghui Zhang,Benxue Liu,Yongshuai Xie,Xinqiang Wang
The rapid development of aerospace requires radomes to achieve the effect of thermal insulation and electromagnetic wave transmission. However, traditional interlayer materials in radomes for thermal insulation are eligible to structural collapse and brittle fracture at high temperatures. Here, MgAl 2 O 4 nanofibers (MANFs) are successfully fabricated from a quasi inorganic/block-copolymer chain segment via molecular design. The MANFs have a laminated geometrical form with tiny pore size, high porosity, and frameworks connected by nanoparticles, resulting in both ultralow density and thermal conductivity that endow them with excellent thermal insulation properties. The MANFs possess unprecedented elasticity from –196 to 1600 °C with a recoverable compression strain of up to 80 % and excellent fatigue resistance for long-term use, which exceeds the reported results of existing fibers. Excitingly, the low dielectric constant enhances the electromagnetic wave transparency of MANFs, making them suitable as a signal transmission material in radomes. The tremendous potential of MANFs promotes the development of thermal insulators with wave-transparent properties used in extreme environments.
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Journal of Energy Storage
·
2024
·
IF 8.9
Xuexian Yu,Jun Liu,Junmin Wu,Sainan Ma,Yingwu Luo,Xiang Gao
Among practical anode materials for next-generation lithium-ion batteries (LIBs), SiO x has garnered substantial attention owing to its relatively low volumetric variation and high theoretical capacity. Nevertheless, the volumetric change of micro-SiO x remains a formidable challenge for existing adhesives. Here, we propose an innovative design strategy that amalgamates both rigidity and flexibility, in which rigid anion gum Arabic (GA), flexible acrylic random copolymer (ARC), and carbon nanotubes (CNTs) interwoven into a 3D network with strong interfacial adhesion and excellent mechanical properties. These attributes effectively restrict SiO x particles and favor a stable solid electrolyte interphase (SEI) layer formed on SiO x . Here, GA plays a pivotal role in dispersing CNTs and maintaining their consistent proximity to SiO x , thereby establishing stable electron conduction networks. The SiO x electrode still sustains a specific capacity of 760 mAh g −1 after 350 cycles under a high current of 1C. Additionally, at 0.2C, the SiO x electrode attains a notably high capacity of 1105 mAh g −1 with a capacity retention of 72.9 % at the 300th cycle, while exhibiting an excellent areal capacity of 1.4 mAh cm −2 even after 400 cycles. This work develops a straightforward yet highly efficacious approach for fabricating high areal capacity electrodes and offers promising prospects for improving the stableness of Si-based anodes.
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Forests
·
2024
·Vol. 15
·期 2
·384
·
IF 2.4
Yang Liu,Yi Zhang,Jianhui Guo,Gaiping Guo,Cheng Li
Transparent wood has excellent optical and thermal properties and has great potential utilization value in energy-saving building materials, optoelectronic devices, and decorative materials. In this work, transparent wood with soft-/hard-switchable and shape recovery capabilities was prepared by introducing an epoxy-based polymer with a glass transition temperature of about 0 °C into the delignified wood template. The epoxy resin was well filled in the pore structure of the delignified wood, and the as-prepared wood exhibited excellent transparency; the optical transmittance and haze of the transparent wood with a thickness of 2.0 mm were approximately 70% and 95%, respectively. Because the glass transition temperature of the epoxy-based polymer was about 0 °C, the prepared transparent wood was rigid below 0 °C and flexible above °C; meanwhile, the transparent wood exhibited shape change and shape recovery properties. Incorporating optical transparency and soft-/hard-switchable ability into the transparent wood opens a new avenue for developing advanced functional wood-based materials.
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Materials
·
2024
·Vol. 17
·期 8
·1921
·
IF 3.1
Yu Wang,Tao Xing,Lifeng Yan
Hydrogen is a dangerous gas as it reacts very easily with oxygen and may explode; therefore, the accumulation of hydrogen in confined spaces is a safety hazard. Composites consisting of unsaturated polymers and catalysts are a common getter, where the commonly used polymer is 1,4- diphenylethynyl benzene (DEB). Silicone rubber (SR) is a good carrier for hydrogen-absorbing materials due to its excellent chemical stability and gas permeability. In this work, polysiloxane, water, and a emulsifier are ultrasonically injected into a uniform emulsion, and the hydrogen getter DEB-Pd/C (Palladium on carbon) is then added. Under the catalysis of platinum (Pt), the cross-linking agent undergoes a hydrosilylation reaction to cross-link polysiloxane in emulsion to form silicone rubber. Then, the water was removed by freeze-drying, and the loss of water constructed a porous frame structure for silicone rubber, thus obtaining porous silicone rubber. The difference in hydrogen absorption performance between porous silicone rubber and ordinary silicone rubber was compared. It was found that, with the increase in water in the emulsion, the porous frame of silicone rubber was gradually improved, and the hydrogen absorption performance was improved by 243.4% at the highest, almost reaching the theoretical saturated hydrogen absorption capacity. Porous silicone rubber was prepared by emulsion mixing, which provided a new idea for further improving the hydrogen absorption performance of silicone rubber.
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