Journal of Sustainable Cement-Based Materials
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2025
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IF 4.2
Kun Wang,Jinjun Guo
Structural polymerization is a primary factor driving intrinsic property changes in calcium silicate (aluminate) hydrate (C–(A)–S–H). However, the mechanisms by which erosive media induce structural polymerization of C–(A)–S–H gel during the service life of cement-based materials remain unclear. This study investigates the effects of both alkaline and acidic sulfates on the composition and microstructural evolution of C–(A)–S–H through various physical and microstructural analyses. The findings indicate that dehydration condensation reactions of Si–OH groups, resulting from decalcification and carbonation processes, are the main contributors to the polymerization silicate tetrahedra. As the aluminum phase increases, the leaching of Al[IV] from the C–(A)–S–H gel after sulfate erosion becomes more pronounced, leading to a tendency for the original silicate–aluminate chain structure to undergo polymerization and reconstruction. Furthermore, aluminum can only promote the polymerization of silicate tetrahedra within a specific range. This study provides a theoretical foundation for regulating concrete microstructure and optimizing its durability.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Wenhao Luo,Canfeng Wu,Liangjie Li,Tingting Jia,Shuhui Yu,Yingbang Yao
In this study, hexagonal boron nitride (h-BN) - polyetherimide (PEI) composites were prepared by a simple solution casting method, where the h-BN particles were aligned by an external magnetic field. Prior to the preparation of the composite samples, the h-BN platelets were firstly decorated by iron oxide nanoparticles (Fe 3 O 4 ) to achieve the desired magnetic properties . Due to the alignment of h-BN particles, the composite exhibited greatly enhanced thermal conductivity along that direction. At a filler loading of 20 wt%, an enhancement of 166% was obtained, compared to that of the unaligned composite. Furthermore, the composite samples showed a low dielectric loss (~ 0.01) with the filling ratio below 20 wt% and a tensile modulus of up to 2.34 GPa. Bearing such thermal conductivity , electrical insulation properties, and mechanical properties , these composites with magnetically aligned h-BN particles show potentials for microelectronic packaging applications.
研究领域:
材料科学
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热管理材料
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复合材料
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FUEL
·
2020
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IF 5.578
Jing-Pei Cao,Tao Xie,Xiao-Yan Zhao,Chen Zhu,Wei Jiang,Ming Zhao,Yun-Peng Zhao,Xian-Yong Wei
Selective hydrogenolysis, the aromatic ether C-O bonds under mild conditions, is crucial for the valorization of lignin. In this context, the effects of H 2 and solvent on the hydrogenolysis of lignin model compounds over Ru catalysts were explored. With H 2 as hydrogen donor, the Ru/AC exhibited the highest activity for converting lignin model compounds into monomeric compounds, whereas H 2 led to low selectivity of aromatics. However, isopropanol was the good H-donor solvent, which could provide a large amount of active hydrogen to promote the cleavage of C-O bonds. Additionally, the yield of aromatics in isopropanol was higher than that under H 2 atmosphere. It could be ascribed to the fact that isopropanol is the protic solvent which displays Lewis basicity, and is a good H-bond donor and a good H-bond acceptor. The higher electron-releasing inductive effect of isopropanol made it easier to provide active hydrogen. Based on the experiments, the mechanism of benzyl phenyl ether hydrogenolysis in H 2 and isopropanol system was presented.
研究领域:
化学工程
·
催化科学
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MOLECULES
·
2023
·Vol. 28
·期 5
·2205
·
IF 4.6
Shengli Shi,Xinsha Zhang,Xianbin Liu,Zhen Chen,Hewen Tang,Dongbao Hu,Hongmei Li
The essential oil (EO) was extracted from aerial parts with insecticidal and fungicidal activity. Herein, the hydro-distilled essential oils ofSeseli maireiH. Wolff roots were determined by GC-MS. A total of 37 components were identified, (E)-beta-caryophyllene (10.49%),β-geranylgeranyl (6.64%), (E)-2-decenal (6.17%) and germacrene-D (4.28%). The essential oil ofSeseli maireiH. Wolff had nematicidal toxicity againstBursaphelenchus xylophiluswith a LC50value of 53.45 μg/mL. The subsequent bioassay-guided investigation led to the isolation of three active constituents: falcarinol, (E)-2-decenal, and octanoic acid. The falcarinol demonstrated the strongest toxicity againstB. Xylophilus(LC50= 8.52 μg/mL). The octanoic acid and (E)-2-decenal also exhibited moderate toxicity againstB. xylophilus(LC50= 65.56 and 176.34 μg/mL, respectively). The LC50of falcarinol for the toxicity ofB. xylophiluswas 7.7 and 21 times than that of octanoic acid and (E)-2-decenal, respectively. Our findings demonstrate that the essential oil fromSeseli maireiH. Wolff roots and their isolates may be developed as a promising natural nematicide.Keywords:Seseli maireiH. Wolff;Bursaphelenchus xylophilus;falcarinol
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Shuquan Yang,Lan Zhang,Meihui Xiao,Lin Chen,Jun Sun,Jianjun Ding,Xiaoxiao Li,Yi Gong,Kang Zheng,Xian Zhang,Xingyou Tian
Microwave devices with reduced dielectric loss and electronic components with increased integration density necessitate the higher performance of electronic packaging materials. The h-BN/AlN/CaCO 3 -MgO-B 2 O 3 -SiO 2 -Li 2 CO 3 glass composites were prepared via tape-casting and then sintered by pressureless and hot-pressing, respectively. The thermal conductivity of pressureless sintered composite was increased to 6.55 W/(m·K) by incorporating 3 wt% h-BN, and the thermal expansion of 4.47 ppm/K was achieved along with low dielectric constant of 5.76 and dielectric loss of 7.02 × 10 −4 at 24 GHz. In contrast, the hot-pressing sintered composite containing 4 wt% h-BN exhibited higher thermal conductivity of 10.3 W/(m·K) and lower dielectric loss of 4.77 × 10 −4 . The microstructure characterization indicated the construction of heat conduction networks, and XRD analysis illustrated the formation of crystallization in the glass. Such low-temperature co-fired ceramic (LTCC) with high thermal conductivity and low dielectric loss would be a promising candidate for electronic packaging and 5G communication applications.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Zhonghuan Zhu,Pengbo Liu,Pingping Du,Bo Yu,Xiaopeng Li,Yong Wang,Li-Ping Lv
Rational design of effective non-noble metal-based electrocatalysts with high conductivity, abundant active sites, and superior stability for zinc–air batteries (ZABs) with long-term cycling ability is highly demanded. A suitable carrier that can provide a high specific surface and porous structure to facilitate the exposure of active sites and the diffusion of reactants, products, and charges is of great importance. Herein, one-dimensional (1D) Fe–Zn-doped porous carbon fibers (Fe–Zn@NCF) are prepared from a polymer fiber matrix encapsulated with Fe-doped ZIF-8 nanocrystals by pyrolysis. The Fe–Zn@NCF exhibits good performance toward the oxygen reduction reaction or oxygen evolution reaction. Impressively, the assembled ZAB with Fe–Zn@NCF as the catalyst delivers a maximum peak power density of 184.6 mW cm–2, excellent rechargeability with a round-trip efficiency of 66.5%, and stable operation over 1600 h (800 cycles). These excellent electrocatalytic performances can be attributed to the Fe/Zn-based dual catalytic active sites and the 1D carbon fiber support of the catalyst with a hierarchical porous structure, a large surface area, and high conductivity that can facilitate fast mass and electron transportation and maintain the structural stability of the catalyst during cycling.
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ACS Applied Materials & Interfaces
·
2023
·
IF 9.5
Ying Zhang,Bin Wei,Hao Liang
An organometallic complex-catalyzed artificial coenzyme regeneration system has attracted widespread attention. However, the combined use of organometallic complex catalysts and natural enzymes easily results in mutual inactivation. Herein, we establish a rhodium-based metal–organic framework (MOF)-on-MOF difunctional core–shell nanoreactor as an artificial enzymatic NAD(P)H regeneration system. UiO67 as the core is used to capture rhodium molecules for catalyzing NAD(P)H regeneration. UiO66 as the shell is used to specifically immobilize His-tagged lactate dehydrogenase (LDH) and serve as a protection shield for LDH and [Cp*Rh(bpy)Cl]+ to prevent mutual inactivation. A variety of results indicate that UiO67@Rh@UiO66 has good activity in realizing NAD(P)H regeneration. Noteworthily, UiO67@Rh@UiO66@LDH maintains a high activity level even after 10 cycles. This work reports a novel NAD(P)H regeneration platform to open up a new avenue for constructing chemoenzyme coupling systems.
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Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Xixi Chen,Wanyi Fu,Yulong Yang,Yanjun Li,Kai Yang,Xuanbo Xu,Xihui Zhang
Atomic H* has been reported to be thermodynamically feasible for activating hydrogen peroxide (H 2 O 2 ) to produce radicals, while the nonradical pathway and the contributions of metal sites and atomic H* in H 2 O 2 activation need further exploration. In this study, a TiO 2 @MnO 2 catalyst was synthesized via a facile hydrothermal method and surprisingly found to produce atomic H* over Mn sites in water without external energy input (e.g., light and electricity). Atomic H* plays an essential role in the activation of H 2 O 2 via a nonradical pathway, which induces the removal of tiamulin up to 80.4–91.7% in 20 min at a wide pH range of 4.0–11.0. Density function theory calculations prove that atomic H* owns a much lower total energy barrier (ΔG total = 0.68 eV) for the decomposition of H 2 O 2 to generate superoxide and singlet oxygen than Mn sites (ΔG total = 2.90 eV). This study is a re-visit to the mechanism of activating H 2 O 2 via atomic H* for efficient degradation of emerging organic contaminants .
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ICARUS
·
2022
·
IF 3.657
A. García Muñoz
Photoelectrons , the fast electrons produced in the photoionization of planetary atmospheres , drive transformations in the atmospheric gas that are often inhibited by energy considerations for thermal electrons. The transformations include excitation and ionization of atoms and molecules, which affect the detectability of these gases and constrain the fraction of incident stellar radiation that transforms into heat. To gain insight into these important questions, we build a Monte Carlo model that solves the slowing down of photoelectrons in a gas with arbitrary amounts of H and He atoms and thermal electrons. Our novel multi-score scheme differs from similar tools in that it efficiently handles rare collisional channels, as in the case of low-abundance excited atoms that undergo superelastic and inelastic collisions . The model is validated and its performance demonstrated. Further, we investigate whether photoelectrons might affect the population of the excited hydrogen H(2) detected at some exoplanet atmospheres by transmission spectroscopy in the H- α line. For the ultra-hot Jupiter HAT-P-32b, we find that photoelectron-driven excitation of H(2) is inefficient at the pressures probed by the line core but becomes significant (yet sub-dominant) deeper in the atmosphere where the line wings form. The contribution of photoelectrons to the destruction of H(2) either by collisional deexcitation or ionization is entirely negligible, a conclusion likely to hold for exoplanet atmospheres at large. Importantly, photoelectrons dominate the gas ionization at the altitudes probed by the H- α line, a fact that will likely affect, even if indirectly, the population of H(2) and other tracers such as metastable helium. Future modeling of these excited levels should incorporate photoelectron-driven ionization.
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Polymers
·
2023
·Vol. 15
·期 17
·3574
·
IF 5
Guang Yang,Zhonghua Chen,Changwei Lv,Lei Deng,Xiaofeng Luo,Yi Li,Songtao He,Qibin Liu
Hemihydrate phosphogypsum, an industrial solid waste product of phosphoric acid production, is abundant and inexpensive. If the problem of poor water resistance is solved, this material could be substituted for cement and other traditional energy-consuming cementitious materials in the construction industry. This approach would confer important economic and environmental benefits while promoting the resource utilization of phosphogypsum (PG). In this study, hydrophobic and self-cleaning coatings of H-PDMS/PMHS/OTS hybrid nanosilica were prepared on a post-hydroxylated PG surface using sol–gel and impregnation methods. The water contact angle, Fourier-transform infrared spectroscopy, Three-dimensional surface morphology and roughness analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, surface abrasion tests, and tape adhesion tests were used to evaluate the hydrophobicity of the coatings. The results demonstrated that the in situ reaction produced a hydrophobic siloxane/nanosilica hybrid network that bonded to the PG surface via hydrogen bonding, making the otherwise completely hydrophilic PG hydrophobic (PGH-3, contact angle (CA) = 144.1°). The PGH-3 sample exhibited excellent chemical stability, maintaining a contact angle greater than 135° under strongly acidic or alkaline conditions. The contact angle remained at 123.7° after 50 tape-bonding tests. After 100 wear cycles, the contact angle remained at 121.9°. This study presents an environmentally friendly method and a straightforward application procedure to impart hydrophobicity to solid waste PG. Its potential is thus demonstrated in the field of PG-based construction materials and the comprehensive utilization of solid waste.
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FOOD CHEMISTRY
·
2023
·
IF 8.8
Ping Yang,Xumei Wang,Hui Wang,Yueming Hu,Pingwei Wen,Zongcai Tu
The mechanism of the effect of reducing sugar chain length and isomers on the allergenicity of Ara h 2 after glycation was investigated. Ara h 2 was more prone to glycation with ribose which had a short chain length. The glycation sites of Ara h 2 after glycation with galactose were higher than the glycation sites in galactose’s isomers-Ara h 2 conjugates, which might be affected by the configuration differences at position C-4 and the small steric effects in terminal groups –CHO of galactose. Ara h 2-ribose conjugate had the lowest allergenicity, and glycation with galactose was more capable of reducing Ara h 2 allergenicity than its isomers. The results indicated that glycation with ribose caused conformational epitope destruction and linear epitope masking of Ara h 2 greatly. Furthermore, since the small steric effects of –CHO, galactose was more capable of reducing Ara h 2 allergenicity than fructose. This study will provide a theoretical basis for selecting appropriate reducing sugars and preparing hypoallergenic products containing peanuts.
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Catalysis Science & Technology
·
2022
·Vol. 12
·期 20
·6268-6284
·
IF 6.177
Tingyu Liang,Jialing Chen,Sen Wang,Pengfei Wang,Zhangfeng Qin,Fang Jin,Mei Dong,Jianguo Wang,Weibin Fan
A series of H-MCM-22 zeolites with different Si/Al ratios (H-M22-x, x = 15–90) were hydrothermally synthesized by boron incorporation to investigate the influences of acid density on the methanol-to-hydrocarbon (MTH) performances and deactivation behaviors. The acid density of H-M22-x zeolites is nearly proportional to their aluminum contents; the residual boron barely affects the overall acidity of H-M22-x zeolites. 27Al and 29Si MAS NMR experiments support the existence of competitive occupancy of various framework T sites among boron, aluminum and silicon during zeolite synthesis, which leads to different distribution of Brønsted acid sites/framework aluminum among three types of pores in H-MCM-22 zeolites. Increasing the Si/Al ratio of H-M22-x zeolites leads to a gradual increase in the proportion of Brønsted acid sites in supercages while those in sinusoidal channels decrease. However, the acid density has a significantly larger impact than acid distribution on the MTH performances of H-M22-x zeolites. Increasing the acid density can accelerate the hydrogen transfer reactions in the MTH conversion and promote the formation of aromatics, ethene, and alkanes. The deactivation of H-M22-x zeolites with low acid density (x = 50–90) is mainly ascribed to coke covering the acid sites inside the micropores and partly blocking the pore mouths. Nevertheless, the deactivation of H-M22-x zeolites with high acid density (x = 15–30) is mainly caused by massive coke deposition on the external surface which blocks the pore mouths of inner micropores. The coke on the external surface exhibits a lower decomposition temperature than that inside the micropores. The deactivation behaviors of H-M22-x zeolites for the MTH reaction can be divided into three stages. Firstly, rapid deactivation of supercages occurred for all the H-M22-x zeolites in spite of their different acid densities, suggesting a much stronger influence of pore structure than acidity on the initial deactivation behaviors of H-M22-x zeolites. Secondly, the acid sites in sinusoidal channels of H-M22-x zeolites are highly resistant to coke formation, which dominates the MTH reaction in the second stage. Finally, with the continuous formation of coke in the surface pockets, which gradually covers the acid sites and pore mouths of sinusoidal channels, complete deactivation of H-M22-x zeolites can be observed. GC-MS and UV-vis analysis of partly or completely deactivated H-M22-x zeolites reveals that the retained species in H-M22-x zeolites gradually condense into bulky hydrocarbon species through successive hydrogen transfer reactions and form methylbenzenes, naphthalene, polymethylnaphthalenes, phenalenone, pyrenes and eventually graphite-like carbonaceous species.
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