CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
R.Q. Yin,P. Zheng,J.C. Wang,B.W. Dai,L.M. Zheng,J. Du,L. Zheng,J.X. Deng,K.X. Song,H.B. Qin
Lead-free piezoelectric ceramics Sr 1.85 Ca 0.15 Na 1− x K x Nb 5 O 15 (0.00≤ x ≤0.40) were prepared using the conventional solid state reaction method. The structural, dielectric and piezoelectric properties were systematically studied. All the ceramics are single orthorhombic tungsten bronze phase at room temperature, and the lattice constants increase with K + content. The dielectric spectra of each composition had two dielectric anomalies. The Curie temperature T c gradually decreases from 291 °C to 266 °C as x increase from 0.00 to 0.40, and the transition temperature T s from orthorhombic phase to tetragonal phase increases from 39 °C to 109 °C. With increasing K + contents, the piezoelectric coefficient d 33 increases rapidly initially, reaches a maximum and then gradually decreases. The highest piezoelectric performance was obtained at x =0.10, with piezoelectric coefficient d 33 =114 pC/N. Mechanisms that lead to the enhancement of d 33 were discussed from the viewpoint of polarization and crystal structure.
研究领域:
材料科学
·
物理学
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产品关联
DOI
高影响因子
Science China-Materials
·
2021
·Vol. 64
·期 7
·1598-1608
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IF 8.273
Hu Jiahui,Tang Wu,Liu Sihong,Hu Yang,Yan Yichao,Lai Huanhuan,Xu Liang,Fan Cong
A new organic cathode namely potassium 2,6-dihydroxyanthraquinone (AQ26OK, theoretical capacity ( C T ) = 169 mA h g −1 ) is synthesized and fully characterized for K-ion batteries. AQ26OK is called polyanionic organic cathode because it has a polyanionic organic skeleton (−2 valent) and two strong ionic K-O bonds. Consequently, the polyanionic AQ26OK is hardly soluble into most organic liquid electrolytes. In half cells (0.3–3.4 V vs. K + /K) using 1 mol L −1 KPF 6 in dimethoxyethane, AQ26OK delivers a highly stable specific capacity of 201 mA h g −1 @50 mA g −1 over 450 cycles (4-month test) and realizes ~106 mA h g −1 for 3200 cycles at 500 mA g −1 . Using the reduced state (K 4 TP) of potassium terephthalate (K 2 TP) as the organic anode, the resulting K 4 TP II AQ26OK organic potassium ion batteries can display a highly stable average discharge capacity of 135 mA h g −1 cathode over 250 cycles at 100 mA g −1 and ~47 mA h g −1 for 1000 cycles at 500 mA g −1 during the working voltage of 0.01–3.1 V. To the best of our knowledge, AQ26OK is among the best stable cathodes reported for K ion batteries.
研究领域:
电化学
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能源材料
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有机电池
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电极材料
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储能技术
✓ 已验证
DOI
高影响因子
SOLID STATE PHENOMENA
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2018
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IF 0
Li Qian Cheng,Mei Feng,Kai Chen
Single crystalline lead-free (K, Na)NbO3 (KNN) nanostructures have attracted much attention for the high piezoelectricity and environmental compatibility. Especially, the plate-like KNN structures are supposed to be utilized in the synthesis of textured KNN-based ceramics. The KNN plate-like templates were prepared by a two-step molten salt reaction. The layered-perovskite Bi2.5Na3.5Nb5O18 (BNN5) was first prepared by using Bi2O3, Nb2O5, Na2CO3, NaCl as raw materials. The BNN5 precursors possess high aspect ratio with an average size of 15 - 20 μm in width and 0.5 - 1 μm in thickness. Then Bi element in the BNN5 was replaced by Na/K through topochemical reaction, and KNN plate-like products which have anisotropic crystal structure were fabricated. It should be emphasized that piezoresponse force microscopy (PFM) was used to confirm three-dimensional (3-D) morphology, while piezoelectric properties of single crystalline KNN platelets were acquired simultaneously. The as-synthesized KNN structures are expected to play an important role in the study of textured KNN ceramics. Meanwhile, the methodology investigated in this paper can also be applied for further fundamental studies on KNN system as well as other lead-free piezoelectric materials.
研究领域:
材料科学
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无机化学
✓ 已验证
产品关联
DOI
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2023
·
IF 6
Wenpeng Hong,Yu Zhang,Jiaxing Song,Haipeng Liu,Ling Zhang,Hang Wang,Yan Zhang,Haifeng Jiang
The extraction of phenolic compounds from biomass is an important way to replace chemical synthesis techniques, and catalytic pyrolysis of biomass is an effective method to obtain phenolic compounds with high selectivity. In this work, cobalt-modified montmorillonite K-10(CMT) catalyst was prepared by using cobalt salt and montmorillonite K-10(MMT), and used to catalyze the pyrolysis of corn stalk(CS) to produce phenol-rich bio-oil. The catalytic pyrolysis characteristics reflected by the liquid and gaseous components were compared using gas chromatography-mass spectrometry(GC-MS) and online mass spectrometry(online MS), and the catalytic pyrolysis behavior of corn stalk was analyzed by using the thermogravimetric analyzer(TGA). The addition of catalyst resulted in the increase of apparent activation energy of pyrolysis process but increased selectivity for phenolic compounds. Compared with the blank sample, the relative content of phenolic compounds in bio-oil increased by 11.99 %, and the selectivity of alkyl-phenols was stronger. In addition, the results also showed that the synthesized catalyst promoted the production of H 2 and CH 4 during the catalytic pyrolysis. The optimum ratio of the prepared catalyst was 6%Co/15%MMT. These works provide an alternative approach to upgrading bio-oil product.
研究领域:
能源与燃料化学
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催化材料科学
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产品关联
DOI
高影响因子
Bioanalysis
·
2024
·
IF 1.9
Xiemin Qi,Ning Chen,Qinxin Song,Yanan Chu,Haiping Wu,Jingwen Shan,Huijie Yue,Guohua Zhou
Aim: Differences are existed in the bioactivity among various vitamin K (VK) forms. To investigate the correlation between clinical parameters of initial anticoagulation and plasma levels of VK1 and VK2 (MK-4 and MK-7), it was necessary to establish a quantitative method for simultaneous determination.Materials & methods: Plasma samples in cardiovascular patients were extracted by cyclohexane and analyzed using a C18 column. Baseline concentrations of VK1, MK-4 and MK-7 were 0.98 ± 0.52 ng/ml, 0.45 ± 0.13 ng/ml and 0.65 ± 0.31 ng/ml, respectively. The concentrations of MK-7 and total VKs were significantly relevant to INR0, respectively (p = 0.010 and p = 0.048, respectively).Conclusion: Thus, when adjusting anticoagulation dosage, concentrations of various VK homologues might be considered.
研究领域:
医学
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药理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
·
2010
·Vol. 27
·期 1
·129-136
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IF 1.082
Tang Xiaoling,Liu Ji,Wang Bo,Yu Hongwei
Thirty-one ester hydrolases were cloned from Escherichia coli K-12 and an efficient screening strategy was applied to screen and characterize them, emphasizing on their enantioselectivity. We are the first to investigate the enantioselectivity of these enzymes, although their activity had been reported by other researchers. The enzyme XL3 from gene b0349, XL10 from gene b0494, XL15 from gene b3412, XL27 from gene b2154 and XL31 from gene b3825 exhibited high activity towards p -nitrophenyl esters with short chain. The enzyme XL15 from gene b3412 was demonstrated for the first time to show high enantioselectivity to ( R )-1-phenylethyl acetate both in hydrolysis and esterification with enantioselectivity value ( E) > 100 at the conversion of 31.2 and 36.8%, respectively.
研究领域:
生物化学
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分子生物学
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2021
·
IF 3.882
Binyao Liu,Xiaoqin Nie,Yi Tang,Shan Yang,Liang Bian,Faqin Dong,Huichao He,Yong Zhou,Kun Liu
The thermal-condensation method is widely used for the synthesis of K-doped g-C3N4 photocatalysts, but the presence of organic byproducts in the resultant products is often overlooked in previous reports. Here, we demonstrated the universal presence of organic byproducts in K-doped g-C3N4 synthesized by typical thermal condensation of KOH/melamine, KOH/dicyandiamide, or KOH/urea. Taking the K-doped g-C3N4 photocatalysis for the degradation of dimethyl phthalate as an example, the negative influence of the organic byproducts on K-doped g-C3N4 photocatalysis was confirmed. Specifically, the organic byproducts can be gradually dissolved into the photocatalytic system of K-doped g-C3N4 as new and stable pollutants. Based on the solubility investigations on the byproducts in several solvents, hot-water washing was demonstrated to be a relatively effective approach to remove the organic byproducts from K-doped g-C3N4. The formation of organic byproducts during the synthesis of K-doped g-C3N4 could be ascribed to the fact that the presence of K salts in melamine, dicyandiamide, or urea molecules results in their insufficient thermal condensation into expected g-C3N4. The present work provides objective information about the K-doped g-C3N4 photocatalysts and reminds researchers about the influence of the organic byproducts on the applications of the other impurity-doped g-C3N4 photocatalysts.
研究领域:
材料化学
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环境催化
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光催化
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纳米材料
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污染物降解
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Fan Fu,Jian Yang,Hao Xu,Yang Li,Shaobo Cao,Kang Da,Wenting Chen,Ximei Fan
Doping or constructing heterojunctions by coupling with other semiconductors are effective methods to improve the photocatalytic performance of graphitic carbon nitride (g-C 3 N 4 ) in toluene degradation. Herein, thermally condensed synthesized K-doped g-C 3 N 4 (KCN) is coupled with BiOCl via a hydrothermal method, and KCN/BOC heterostructures are obtained. The optimal KCN 1 /BOC heterojunction exhibits approximately 85% removal of toluene after 150 min irradiation under simulated solar light, which is 12.4 and 9.6 times higher than those of g-C 3 N 4 and BiOCl, respectively. The superior performance of KOH-modified g-C 3 N 4 is attributed to the electron transfer channels formed by the insertion of K + into the g-C 3 N 4 layers, which facilitate efficient charge separation and rapid electron transfer. Furthermore, the KCN/BOC heterostructure with the Z-scheme further improves the surface charge separation efficiency, which plays a critical role in the photocatalytic process. This work provides a facile and promising strategy for dual-strategy modification of g-C 3 N 4 to enhance photocatalytic degradation activity.
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2012
·Vol. 59
·期 11
·1415-1420
·
IF 0.678
Jinyun Peng,Keliang Nong,Lingping Cen
Acid chrome blue K (ACBK) was electropolymerized on the surface of a glassy carbon electrode (GCE) by cyclic voltammetric sweep in the potential range from –0.2 to 0.9 V. The characteristic of poly-ACBK film was studied by different methods such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. This modified electrode showed excellent electrocatalytic response to curcumin with the increase of the electrochemical responses. Under the optimal conditions a good linear voltammetric response could be obtained over the range of 1.0 × 10 −7 -7.0 × 10 −5 M and the detection limit was got as 4.1 × 10 −8 M (S/N = 3). The method was successfully applied for the determination of curcumin in human urinev samples.
研究领域:
分析化学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Analysis and Testing
·
2022
·Vol. 7
·期 2
·157-162
·
IF 0
Gao Su,Ye Ming-Liang,Ma Rui,Liu Ai-Rong,Gao Hong-Wen
Based on the Mg 2 + complexation with acid chrome blue K (ACBK) at pH 10.2, an automatic system was designed to determine total hardness of water. The system consists of a vector colorimeter, a multi-channel sampling pump and both reagents A and B. Two kinds of reagent solutions were prepared and used in this system, i.e., ammoniacal buffer and ACBK—disodium magnesium EDTA solutions. The experimental results of the standard solutions containing 2 and 3 mg/L of total hardness showed that the relative standard deviations (RSDs) were 1.9% and 2.2%, respectively, and the limit of detection (LOD) was only 0.035 mg/L. The detection of four natural water samples showed that the recoveries were between 85.0% and 108.6%, consistent with those obtained by ICP-AES method.
研究领域:
分析化学
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环境科学
✓ 已验证
产品关联
DOI
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 34
·14389-14400
·
IF 3.288
Wenyi Yu,Qianwei Liang,Yuwei Yin,Junjie Geng,Wei Chen,Xuanyi Tan,Hanjin Luo
Arsenite (As(III)) is more toxic and more difficult to remove from water than arsenate (As(V)). A new nano core–shell-structured K-OMS-2@UiO-66 (K-OMS-2, formula KMn8O16·nH2O) was fabricated via a facile one-step oxidation–coprecipitation method for enhanced As(III) removal. Results showed that the maximal adsorption capacity of As(III) achieved was 180.10 mg g−1. The as-synthesized K-OMS-2@UiO-66 adsorbent functions excellently across a broad pH range of 1.5 to 10.0, and the residual concentrations of As(III) can drop under 10.0 μg L−1. Based on XPS and FTIR measurements, it is proposed that the removal mechanism was mainly controlled through a synergistic interaction of surface complexation and hydrogen bonding. As(III) was sorbed onto the surface of the sorbent by Zr–O bonds and Mn–O bonds. Mn(IV) and Mn(III) in K-OMS-2@UiO-66 effectively oxidized As(III) to As(V). Then, some negatively charged As(V) were adsorbed at the positive sites of the adsorbent through electrostatic attraction, while others formed bidentate complexes with the Zr–O bonds. This study develops an attractive sorbent for As(III) removal from contaminated water and has a facile and low-cost synthesis process, good As(III) sorption performance, and reusability.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
·
2020
·Vol. 217
·期 8
·1900806
·
IF 1.759
Jingbo Li,Yu Liu,Fang Xu,Junping Hu,Nan Chen,Guoping Du,Changshuang Jiang
As a 2D material, Ti 3 C 2 (MXene) has been recently used as electrodes for electrochemical capacitors. Herein, a two-step procedure is used to obtain a highly opened layer structure for Ti 3 C 2 , which differs from the methods used in the literature for synthesizing exfoliated MXene. First, the mild NH 4 HF 2 etching agent is used to prepare the regular Ti 3 C 2 MXene. Second, KOH is added into the obtained solution for K + to intercalate the MXene. The K + intercalation is found to greatly increase the (002) crystal planar spacing of the Ti 3 C 2 from 10.8 to 12.4 Å. More importantly, this K + -intercalated MXene exhibits a highly opened layer structure, whereas the regular MXene only has a partially opened layer structure. Consequently, the former is expected to allow much more active sites exposed to liquid electrolyte, and also facilitates remarkably higher ion and electron transport efficiency. To investigate their electrochemical capacitance properties, the regular and K + -intercalated Ti 3 C 2 MXenes are used to fabricate binder-free electrodes on nickel foams by an electrophoretic deposition method. The K + -intercalated MXene-based electrode is found to have twice higher specific capacitance than the regular MXene. Furthermore, the K + -intercalated Ti 3 C 2 MXene-based electrode exhibits an excellent cyclic stability.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）