Nanomanufacturing and Metrology
·
2024
·Vol. 7
·期 1
·1-16
·
IF 0
Wang Tao,Tian Yanling,Lu Zhilai,Wang Weijie,Zhang Zhao,Zhu Guangwei,Tang Hui,Zhang Dawei
As a promising micro/nanofabrication method, electrical-assisted nanomachining has obtained substantial attention due to its high material removal rate and attainable superior surface quality. In this study, a rectangular wave electrical signal was applied for nanomachining by a customized tungsten tip. Owing to the coupling effect between the electric field and mechanical force, the cutting depth of the machined grooves can be expanded. In electrical-assisted groove processing, a depth of 270 nm and an aspect ratio of 0.6 on the copper sample can be achieved. The influence of operation parameters including applied voltage, frequency, duty ratio, normal force and cutting speed on the machining performance was investigated in terms of the groove depth, width, aspect ratio, and surface roughness. The potential machining mechanisms should be a combination of electric field force, nanoscale electric discharge, electric contact thermal effects, possible annealing behavior, and scraping and plowing actions induced by mechanical forces.
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RARE METALS
·
2023
·Vol. 42
·期 11
·3886-3896
·
IF 8.8
Xu Can,Hu Xian-Wei,Yu Jiang-Yu,Li Peng-Wei,Liu Ai-Min,Luo Shao-Hua,Shi Zhong-Ning,Wang Zhao-Wen
The knowledge on the ionic structure of YCl 3 -KCl molten system is of guiding significance for the practical production of yttrium metals and yttrium alloys via molten salt electrolysis using this system as electrolyte. In this paper, the theoretical Raman spectra of the ionic groups which may exist in YCl 3 -KCl molten system are simulated by quantum chemical calculation using Gaussian 09 and GaussView 5.0 programs based on density functional theory (DFT). Then the ionic structures of 20 mol%–60 mol% YCl 3 -KCl molten salt systems are studied by comparing the Raman shift values of the bands in the theoretical Raman spectra of different ionic groups with the experimental spectra of this system. YCl 6 3− , Y 2 Cl 7 − , Y 2 Cl 8 2− and Y 2 Cl 9 3− are thought to exist in the molten system. With the increase of temperature, the relative content of YCl 6 3− ionic groups increases while those of Y 2 Cl 7 − , Y 2 Cl 8 2− and Y 2 Cl 9 3− ionic groups decrease. Moreover, the "lifetime" of all ionic groups decreases within the temperature range of 692–730 °C. Meanwhile, the relative contents of Y 2 Cl 7 − , Y 2 Cl 8 2− and Y 2 Cl 9 3− increase with the increase of YCl 3 content, while that of YCl 6 3− decreases. The wave function analysis of the four ionic groups (YCl 6 3− , Y 2 Cl 7 − , Y 2 Cl 8 2− , and Y 2 Cl 9 3− ) is carried out by Multiwfn program. The net charge in each group, the direction of electron migration during the formation of each group, the sites where electrophilic and nucleophilic reactions are most likely to occur in each ionic group, and the order of bond breaking during chemical reactions for the four groups are obtained. Graphical abstract
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2024
·Vol. 59
·期 4
·1235-1252
·
IF 3.5
Wang Jianjun,Chen Jiaqi,Li Dongning,Liu Jiao,Shi Zhichun,Xu Liang,Zang Yu
The rapid development of industrialization generated an urgent requirement for the catalytic conversion of CO 2 into high-value-added chemical products. Herein, a class of novel bifunctional metalloporphyrin-based hyper-crosslinked ionic polymer (ImHCP-Co) was synthesized via one-pot Friedel–Crafts alkylation and quaternization reactions. The obtained bifunctional ImHCP-Co showed a high BET surface area and sufficient CO 2 adsorption capacity. Relying on the synergistic effect of the electrophilic and nucleophilic functionalities, the as-prepared ImHCP-Co showed an excellent performance in CO 2 cycloaddition using epichlorohydrin as the substrate (99% conversion and 99% selectivity) and can be carried out without any solvents or cocatalysts to afford a high turnover number. Importantly, it could also convert various epoxide substrates into the corresponding cyclic carbonates and can maintain 82.5% of its catalytic ability after 5 cycles. The catalytic mechanism was systematically explained by DFT calculation and proved the cooperative effect of Co 2+ centers and nucleophilic Cl − in the catalytic process. This study provides a new avenue for the design and preparation of HCP-based multifunctional catalysts used for the treatment of greenhouse gases. Graphical abstract
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高影响因子
CATALYSIS LETTERS
·
2024
·Vol. 154
·期 7
·3787-3797
·
IF 2.3
Han Zhaohao,Chu Qingyan,Wang Hao,Jia Xiaoqiong,Jiang Peng,Li Tong
We successfully synthesized a bifunctional alkaline catalyst (Co@CTS-1), on the one hand, which demonstrates exceptional catalytic performance in the aerobic oxidation of alkenes, particularly in the epoxidation of styrene, in the absence of both an initiator and a co-reducing agent, achieving a conversion rate of 74.94%, a selectivity of 71.84% for styrene oxide; on the other hand, the catalyst maintained its high activity throughout a cyclic reaction run lasting up to 2500 min, demonstrating exceptional stability in the epoxidation of styrene. The Co@CTS-1 catalyst utilizes TS-1 as the carrier, and it is modified with cobalt and cerium elements. Through the embedding of cobalt elements within the TS-1 cage, the catalyst gains the ability to activate O 2 , and by inserting cerium elements into the atomic positions of silicon, the conversion rate is further enhanced. This encapsulated structure stabilizes cobalt nanoparticles, overcoming the short lifespan issues caused by sintering and leaching in conventional supported catalysts. This work provides practical clues for the development and application of novel catalysts, and will inspire the advancement of olefin air epoxidation. Graphical
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高影响因子
CATALYSIS LETTERS
·
2024
·Vol. 154
·期 7
·3494-3502
·
IF 2.3
Zhou Shuolin,Wen Sha,Xu Qiong,Liu Xianxiang,Yin Dulin
5-Hydroxymethylfurfural (HMF) serves as a versatile platform compound bridging the realms of biomass resources and the fine chemicals industry, with its selective oxidation holding significant value. In this study, nitrogen-doped porous carbon (NDPC) materials were synthesized by using urea as the nitrogen source and sucrose as the carbon source via a hard-template approach. These materials were subsequently employed in the selective oxidation of HMF to produce 2,5-diformylfuran (DFF) under specific oxygen pressure conditions. The morphology and structure of NDPC were elucidated through SEM, XPS and XRD analyses. The impact of varying the molar ratio of N/C and nitrogen sources on the catalyst was examined, as well as the effects of different reaction conditions on HMF conversion and DFF selectivity were investigated. The results demonstrated an impressive 81.0% HMF conversion and a remarkable 97.9% DFF selectivity under the suitable conditions. Furthermore, the catalyst exhibited consistent catalytic performance throughout the recycling experiments. Graphical
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高影响因子
COLLOID AND POLYMER SCIENCE
·
2024
·Vol. 302
·期 5
·819-828
·
IF 2.2
Ji Xinyuan,Yang Zhe,Fang Jiahui,Hu Sheng
In this study, a novel molecularly imprinted polymer (MIP) was synthesized with attapulgite (ATP) and acrylamide (AM) and ethyl methacrylate (MMA) for controlled release carrier of 5-fluorouracil (5-FU). The MIPs (PAM-PMMA) were characterized by XRD, FESEM, HRTEM, and FTIR. The drug loading and in vitro controlled release ability of MIP on 5-FU was investigated by adsorption property analysis and in vitro release analysis. MIPs (PAM-PMMA) reached a maximum drug loading of 12 mg/g and a maximum release of 80% at an ATP dosage of 0.2 g (0.4%), an initial concentration of 5-FU of 100 mg/L, and an adsorption time of 240 min. Cytotoxicity analysis showed that the maximum inhibition of cells could reach 25% at 72 h of cell culture time under the above conditions. The results showed that MIPs synthesized with ATP as the substrate and AM and MMA as the functional monomers were successfully synthesized and could be used as a drug delivery system for 5-FU. Graphical
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高影响因子
Nanoscale Research Letters
·
2019
·Vol. 14
·期 1
·1-11
·
IF 3.159
Lu Lu,Li Sheng,Li Jun,Lan Lifang,Lu Yan,Xu Shuaijun,Huang Si,Pan Chunyang,Zhao Fenghua
The FeF 3 ·0.33H 2 O cathode material can exhibit a high capacity and high energy density through transfer of multiple electrons in the conversion reaction and has attracted great attention from researchers. However, the low conductivity of FeF 3 ·0.33H 2 O greatly restricts its application. Generally, carbon nanotubes (CNTs) and graphene can be used as conductive networks to improve the conductivities of active materials. In this work, the FeF 3 ·0.33H 2 O cathode material was synthesized via a liquid-phase method, and the FeF 3 ·0.33H 2 O/CNT + graphene nanocomposite was successfully fabricated by introduction of CNTs and graphene conductive networks. The electrochemical results illustrate that FeF 3 ·0.33H 2 O/CNT + graphene nanocomposite delivers a high discharge capacity of 234.2 mAh g −1 in the voltage range of 1.8–4.5 V (vs. Li + /Li) at 0.1 C rate, exhibits a prominent cycling performance (193.1 mAh g −1 after 50 cycles at 0.2 C rate), and rate capability (140.4 mAh g −1 at 5 C rate). Therefore, the electronic conductivity and electrochemical performance of the FeF 3 ·0.33H 2 O cathode material modified with CNTs and graphene composite conductive network can be effectively improved.
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高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 24
·期 28
·22450-22457
·
IF 2.741
Deng Chao,Li Ying,Li Jinhui,Chen Yuan,Li Huafen
Though mechanical recycling of WEEE plastics is supposed to be a promising method, PBDEs release and the resulting contamination during its processing remain unclear yet. The distribution of PBDEs pollution in production lines was investigated from two flame-retardant plastic modification plants in Southern China. This was followed by laboratory simulation experiments to characterize the emission processes. PBDEs concentrations ranged from 37 to 31,305 ng/L in cooling water and from 40,043 to 216,653 ng/g dry wt in solid samples taken during the field investigation. In the laboratory simulation, concentrations ranged from 146 to 433 ng/L in cooling water and from 411,436 to 747,516 ng/Nm 3 in flue gas. All samples were dominated by BDE-209 among the congeners. Temperatures and impurities in plastic substrate can significantly affect PBDEs release. Special attention should be paid to the risks of water directly discharge from the cooling system, especially for the biological sludge and sediments, as well as flue gas emissions to the environment.
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高影响因子
Journal of Geographical Sciences
·
2024
·Vol. 34
·期 6
·1128-1156
·
IF 4.3
Zhao Shengbo,Qi Junheng,Li Dongxue,Wang Xingping
Railways are a crucial part of the African transport network and have a significant impact on the socio-economy and urban development. Previous studies have mainly considered the impacts of railways in Africa from the perspective of economy, politics, security, and natural environment with few attempts to consider land use. Based on Landsat remote sensing data for the 10 km buffer zone along the Ethiopian section of the Addis Ababa–Djibouti Railway (ADR) in 2013, 2017, and 2021, we studied the land use change (LUC) in the area and explored its influencing factors using the ordinary least square model (OLS) and geographical weighted regression model (GWR). There were six key results. (1) Farmland, forest, grassland, and others (including sandy land and bare land) were the primary types of land use, but from 2013 to 2021, the area of built-up land and farmland increased, whereas the area of forest, grassland, and other land decreased. (2) There was a noticeable pattern in the degree of change in the area of built-up land, farmland, and forest as the buffer distance increased along the railway. This pattern indicated a gradual shift in land use and LUC gradients. (3) The land use structure and its changes in the areas surrounding different stations displayed obvious differences. (4) The construction and operation of the ADR is one of the direct factors affecting landscape change along the railway. (5) The distance from the train station, whether the station provides a passenger service, the population size, and the distance from the central city had a positive effect on the expansion of built-up land surrounding the station. The factor of whether the station provides a freight service had a negative correlation with the expansion of built-up land. Socio-economic factors have gradually replaced railway factors as the main driving force of the expansion of built-up land around the stations. (6) The effect strength of different factors on the expansion of built-up land varied in the areas surrounding different stations.
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高影响因子
Science China-Materials
·
2021
·Vol. 64
·期 9
·2313-2324
·
IF 8.273
Gao Yang,Wang Yuanrui,Xia Shan,Gao Guanghui
Ionic hydrogel-based sensors have shined a spotlight on wearable electronics. However, the sensitivity and reliability of hydrogel devices are significantly hampered by the weak adhesion of skin-sensor interface as well as inferior temperature tolerance. Here, inspired by the structure and composition of dermis, a novel skin-attachable and environment-stable hydrogel was designed by integrating collagen into the LiCl-containing chemically cross-linked polyacrylamide hydrogel. The hydrogel exhibited skin-like mechanical properties of low modulus, superior stretchability as well as excellent elasticity. Furthermore, the introduction of collagen endowed the hydrogel with robust and seamless interfaces with diverse materials, including the curved skin. As a result, the hydrogel is capable of serving as a human-machine interface for collecting reliable electrocardiography (ECG) signals and discerning various human motions, with high sensitivity (gauge factor = 10.7), fast response, negligible hysteresis as well as extensive monitoring range. Notably, the hydrogel that can mimick the temperature-tolerant mechanism of most organisms possesses persistent stabilization of adhesive, conductive, sensory and mechanical performances at subzero or ambient conditions. The skin-inspired strategy paves an effective way for the design of multifunctional materials with potential applications in next-generation electronics.
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高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2016
·Vol. 23
·期 8
·7627-7638
·
IF 2.76
Zhu Nengwu,Cao Yanlan,Shi Chaohong,Wu Pingxiao,Ma Haiqin
Recovery of gold from aqueous solution using simple and economical methodologies is highly desirable. In this work, recovery of gold as gold nanoparticles (AuNPs) by Shewanella haliotis with sodium lactate as electron donor was explored. The results showed that the process was affected by the concentration of biomass, sodium lactate, and initial gold ions as well as pH value. Specifically, the presence of sodium lactate determines the formation of nanoparticles, biomass, and AuCl 4
− concentration mainly affected the size and dispersity of the products, reaction pH greatly affected the recovery efficiency, and morphology of the products in the recovery process. Under appropriate conditions (5.25 g/L biomass, 40 mM sodium lactate, 0.5 mM AuCl 4
− , and pH of 5), the recovery efficiency was almost 99 %, and the recovered AuNPs were mainly spherical with size range of 10–30 nm (~85 %). Meanwhile, Fourier transforms infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that carboxyl and amine groups might play an important role in the process. In addition, the catalytic activity of the AuNPs recovered under various conditions was testified by analyzing the reduction rate of p -nitrophenol by borohydride. The biorecovered AuNPs exhibited interesting size and shape-dependent catalytic activity, of which the spherical particle with smaller size showed the highest catalytic reduction activity with rate constant of 0.665 min −1 .
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高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 25
·期 3
·2285-2292
·
IF 2.741
Zhao Zhiyong,Chen Lei,Bai Bing,Yang Xianli,Tan Yanglan,Wang Jianhua,Zhao Xiaoyan,Zhou Changyan
Providing guidance on the reasonable use of pesticide in agricultural production is of particular importance for ensuring food safety. In the present study, a field trial was performed to study the dissipation and accumulative pattern of cyromazine (CA) and its metabolite in Agaricus bisporus ( A . bisporus ) cultivation. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was first developed and validated for the determination of CA and melamine (MEL) in the casing soil and fruiting body. During the cultivation period, the dissipation rates of CA in the casing soil were between 51.57 and 63.48% at three dose groups. The fruiting body presented higher accumulation ability for MEL compared with CA. The terminal residues of MEL never exceeded the maximum residue limits (MRLs) in food. In addition, the intake health risk from the CA and MEL residues in the fruiting body were negligible to humans. This study will help to provide valuable guidance on the application strategies of CA in A . bisporus cultivation.
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高影响因子
危险品化学品经营许可证（带存储）