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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高影响因子
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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PubMed
高影响因子
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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PubMed
高影响因子
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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高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Junqiao Jiang,Zhen Li,Min Xiao,Shuanjin Wang,Kenji Miyatake,Yuezhong Meng
Phosphoric acid (PA)-doped polymer electrolyte membranes are the most promising materials for high-temperature proton exchange membranes (HT-PEMs). However, their development is subject to the compromise between proton conductivity and phosphoric acid (PA) doping level. Here, an ether-free QPAF-4 membrane (a copolymer containing perfluoroalkylene and fluorenyl groups with pendant ammonium groups) is directly doped with phosphoric acid and studied as HT-PEMs. Due to the intrinsic micro-phase separation structure of QPAF-4 matrix and strong interaction of quaternary ammonium (QA)-PA, the PA-doped membranes possess high proton conductivity and eminent PA retention at comparatively low PA doping level, respectively. The QPAF-4 membrane with 150% PA uptake (QPAF-4-150%PA) offers a proton conductivity of 52 mS cm −1 at 160 °C. As expected, the single cell with QPAF-4-150%PA membrane shows the maximum peak power density of 683 mW cm −2 at 160 °C under anhydrous condition. Meanwhile, the single cell exhibits excellent durability over a period of 60 h with only a slight reduction in voltage of 3.1%. These results indicate that the as-prepared PA-doped quaternized polymer with micro-phase separation structure seems to offer a promising way to develop performing and long-life HT-PEMs with low PA doping levels.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Tian-Yu Liu,Cong Wang,Yong-Zhe Han,Chang Bai,Hai-Tao Ren,Yong Liu,Xu Han
Bi 2+x WO 6 are a group of reactive photocatalysts in the photooxidation of various contaminants. However, their catalytic reactivity in the persulfate (PS)-based oxidation processes in the absence of light is still unknown. In this study, Bi 2.15 WO 6 shows a high reactivity in the catalytic oxidation of bisphenol A (BPA) by PS in the absence of light under alkaline conditions, and 20 mg L -1 BPA can be rapidly removed within 30 min at pH 10.0 with the low stoichiometry ratio of 1.79 between consumed PS and removed BPA. Characterizations of the oxidation products indicate that 98.4% of soluble BPA has been oxidatively polymerized to BPA polymers, instead of being oxidized to CO 2 and H 2 O. FTIR, Raman, XPS and electrochemical analyses confirm that surface Bi(III) is the reactive site for the adsorption of BPA and PS, which then initiates reactions between BPA and PS. DFT calculations reveal that the O-O bond in PS is moderately activated via the nonradical pathway after adsorbing on Bi(III), instead of being decomposed to SO 4 •− , followed by H-abstraction from BPA by the activated PS with the formation of phenoxyl radicals and the subsequent polymerization to BPA polymers. The apparently lower energy barrier from adsorbed BPA (Δ G = 0.056 eV) than that from dissolved BPA (Δ G = 0.263 eV) further reveals that H-abstraction from adsorbed BPA to the activated PS on the surface of Bi 2.15 WO 6 is more favorable than that from dissolved BPA. This study gives new insight on the efficient removal of recalcitrant contaminants via the H-abstraction pathway.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Chenxiao Yin,Zhi-Xiong Fei,Jingrui Sun,Lin Weng,Xu Wang,Ke-Ke Yang,Ling-Ying Shi
Low-temperature solid–liquid organic phase change materials (OPCMs) offer tremendous opportunities in thermal management techniques but suffer from leakage problems above the melting temperature. Here, inspired with the universal hydro/organogels using three-dimensional polymer networks capable of holding large amounts of liquid solvents, a kind of form-stable high-enthalpy biphasic phase change organogels (BPCOGs) were developed by the integration of hydrophobic association for synthesizing intrinsic phase change matrices and H-bonding interaction for binding OPCM liquids. The porous phase separated poly(acrylamide-octadecyl acrylate) (P(AM- co -OA)) matrices with uniformly dispersed thermal conductive carbon nanotubes were fabricated from the hydrophobically associating hydrogels (HAHs), in which POA segments provide the phase change energy storage microdomains and the PAM network is capable of binding a series of melted OPCMs by hydrogen bond engineering. The fabricated BPCOGs possess form-stability, high phase change enthalpy (high up to 215.5 J g −1 ) and high energy storage efficiency (>90%), and show excellent electrical/optical-thermal energy conversion as well as shape memory performances. This study provides a universal strategy to prepare flexible biphasic OPCMs suitable for a variety of solid–liquid OPCMs including fatty alcohols, fatty acids and polyethylene glycol, and demonstrates the great potentials of these BPCOGs in solar energy utilization and functional flexible devices.
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高影响因子
Advanced Science
·
2023
·Vol. 10
·期 32
·2302618
·
IF 15.1
Wei Zhou,Changsheng Song,Shuyang Li,Miao Liu,Huiwen He,Shaoyu Yang,Jin Xie,Fei Wang,Fang Fang,Dalin Sun,Jie Zhao,Yun Song
All-solid-state sodium-ion batteries have the potential to improve safety and mitigate the cost bottlenecks of the current lithium-ion battery system if a high-performance electrolyte with cost advantages can be easily synthesized. In this study, a one-step dehydrogenation-assisted strategy to synthesize the novel thio-borohydride (Na-B-H-S) electrolyte is proposed, in which both raw material cost and preparation temperature are significantly reduced. By using sodium borohydride (NaBH 4 ) instead of B as a starting material, B atoms can be readily released from NaBH 4 with much less energy and thus became more available to generate thio-borohydride. The synthesized Na-B-H-S (NaBH 4 /Na-B-S) electrolyte exhibits excellent compatibility with current cathode materials, including FeF 3 (1.0–4.5 V), Na 3 V 2 (PO 4 ) 3 (2.0–4.0 V), and S (1.2–2.8 V). This novel Na-B-H-S electrolyte will take a place in mainstream electrolytes because of its advantages in preparation, cost, and compatibility with various cathode materials.
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PubMed
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2023
·
IF 8.7
Xiao-Ai Ye,Si-Ying Zhang,Da-Qiang Zhao,Ling Ding,Kan Fang,Xu Zhou,Gui-Gen Wang
2D MXene are showing great prospects for EMI shielding by virtue of abundant surface functional groups and outstanding metallic electrical conductivity . However, it remains a great challenge to simultaneously achieve flexible, lightweight and high stability in MXene shielding materials due to inferior mechanical strength and poor oxidation stability. Gelation paves up an effective and facile strategy to develop highly stable and conductive 3D porous Ti 3 C 2 T x architectures. Herein, super-flexible and highly conductive H-Ti 3 C 2 T x MXene composite films with 3D macro-assemblies for EMI shielding were fabricated through a gelation-densification process initiated by hydrochloric acids, and two-step vacuum-assisted filtration followed by freeze-casting approach. The obtained nanocomposite films manifest satisfactory mechanical properties with a tensile strength of 116.51 MPa, excellent EMI SE of 55.14 dB, superior SSE/t and high EMI SE retention after 5000 cycles of bending deformation. In addition, the as-prepared nanocomposite papers demonstrate outstanding thermal management performances such as rapid response time, high Joule heating temperature (118 °C) at low applied voltage (2.5 V) and eminent working stability (4000 s).
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高影响因子
APPLIED CLAY SCIENCE
·
2021
·
IF 5.467
Xinyu Li,Shunyu Han,Dongdong Guan,Nanzhe Jiang,Jingzhe Xu,Sang-Eon Park
The direct synthesis of H-ZSM-5 catalysts from natural aluminosilicate clays is important for the conversion of raw clay resources to high-value-added products. Herein, the solid-like-state conversion was used to directly prepare nano-H-ZSM-5 with uniform morphology and particle size (~300 nm) from leached illite (ISR) as both Si and Al source. Crystallization kinetics indicated that the reactivity of ISR is similar to that of commercially fabricated products and ISR could be rapidly (within 5 h) converted into nano-H-ZSM-5, the crystallinity , morphology, and crystal size of which were strongly affected by the amount of tetrapropylammonium hydroxide (TPAOH). Additionally, the residual Al of ISR uniformly intruded the H-ZSM-5 framework to provide active sites for the methanol-to-aromatics reaction. The catalytic performance stability and BTX selectivity of nano-H-ZSM-5 for this reaction surpassed those of a commercial ZSM-5 catalyst because of the synergistic effect among the specific surface area and volume of micropores , uniform morphology and particle size, and homogeneously distributed acidic sites. This rapid, efficient, and cleaner synthesis reported herein was shown to have no necessity of ion exchange with ammonium salts, to be H-form of ZSM-5 as well as improve the productivity of HZSM-5 catalysts. And consequently, it is expected to reduce the cost of synthesis and provide an opportunity for the comprehensive development and utilization of illite clay resources.
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高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xiao Zhao,Xuan Shi,Zhongshun Chen,Long Xu,Chengyi Dai,Yazhou Zhang,Xinwen Guo,Dongyuan Yang,Xiaoxun Ma
A series of ZnO-ZrO 2 solid solutions with different Zn contents were synthesized by the urea co-precipitation method, which were coupled with H-ZSM-5 zeolite to form bifunctional catalysts. As a new benzene alkylation reagent, syngas was used instead of methanol to realize the efficient conversion of syngas and benzene into toluene and xylene. A suitable ratio of ZnO-ZrO 2 led to the significant improvement in the catalytic performance, and a suitable amount of acid helped to increase the selectivity of toluene/xylene and reduce the selectivity of the by-products ethylbenzene and C 9 + aromatics. The highest benzene conversion of 89.2% and toluene/xylene selectivity of 88.7% were achieved over 10% ZnO-ZrO 2 &H-ZSM-5 (Si/Al = 23) at a pressure of 3 MPa and a temperature of 450 °C. In addition, the effect of the zeolite framework structure on product distribution was examined. Similar to the molecular dynamics of aromatic hydrocarbons , H-ZSM-5 zeolites comprise 10-membered-ring pores, which are beneficial to the activation of benzene; hence, the conversion of benzene is higher. H-ZSM-35 and H-MOR zeolites exhibited small eight-membered-ring channels, which were not conducive to the passage of benzene; hence, the by-product ethylbenzene exhibits a higher selectivity. The distance between the active centers of the bifunctional catalysts was the main factor affecting the catalytic performance, and the powder mixing method was more conducive to the conversion of syngas and benzene.
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高影响因子
CEMENT AND CONCRETE RESEARCH
·
2020
·
IF 8.328
Xin Liu,Pan Feng,Wei Li,Guoqing Geng,Jiale Huang,Yun Gao,Song Mu,Jinxiang Hong
Calcium silicate hydrate (C-S-H), the most important Portland cement hydration product , determines the mechanical properties and durability of cementitious materials . In marine environment, C-S-H often suffers from sulfate attack – one of the most common and severe degradations for concrete. pH is considered as a critical factor in determining the deterioration behavior of C-S-H during sulfate attack, of which the significance may be overlooked. This study focused on the role of pH on the deterioration of C-S-H in terms of the composition and nano/micro structure under sulfate attack. The results show that lowering pH aggravates the decalcification of C-S-H, whereas a strong alkaline condition is beneficial to increase the resistance to deterioration. An increase in the mean chain length together with the proportion of large pores (>10 nm) is observed when C-S-H is subjected to low-pH sulfate attack (pH = 10–12), resulting in a relatively loose structure. The deep analysis on defective tobermorite model reveals that calcium at the interlayer of C-S-H nanostructure is readily removed under sulfate attack, thereby improving the potential of Si-O-Si groups formation and increases the mean chain length of C-S-H.
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高影响因子
危险品化学品经营许可证（带存储）