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Tuning nitrogen defects and doping sulfur in carbon nitride for enhanced visible light photocatalytic

《化学科学与工程前沿（英文）》 2023年 第17卷 第1期   页码 93-101 doi: 10.1007/s11705-022-2175-x

摘要： Defect construction and heteroatom doping are effective strategies for improving photocatalytic activity of carbon nitride (g-C3N4). In this work, N defects were successfully prepared via cold plasma. High-energy electrons generated by plasma can produce N defects and embed sulfur atoms into g-C3N4. The N defects obviously promoted photocatalytic degradation performance that was 7.5 times higher than that of pure g-C3N4. The concentration of N defects can be tuned by different power and time of plasma. With the increase in N defects, the photocatalytic activity showed a volcanic trend. The g-C3N4 with moderate concentration of N defects exhibited the highest photocatalytic activity. S-doped g-C3N4 exhibited 11.25 times higher photocatalytic activity than pure g-C3N4. It provided extra active sites for photocatalytic reaction and improved stability of N defects. The N vacancy-enriched and S-doped g-C3N4 are beneficial for widening absorption edge and improving the separation efficiency of electron and holes.

关键词： g-C3N4     nitrogen defect     sulfur doping     photodegradation     plasma    

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Acoustic fault signal extraction via the line-defect phononic crystals

《机械工程前沿（英文）》 2022年 第17卷 第1期   页码 10-10 doi: 10.1007/s11465-021-0666-y

摘要： Rotating machine fault signal extraction becomes increasingly important in practical engineering applications. However, fault signals with low signal-to-noise ratios (SNRs) are difficult to extract, especially at the early stage of fault diagnosis. In this paper, 2D line-defect phononic crystals (PCs) consisting of periodic acrylic tubes with slit are proposed for weak signal detection. The defect band, namely, the formed resonance band of line-defect PCs enables the incident acoustic wave at the resonance frequency to be trapped and enhanced at the resonance cavity. The noise can be filtered by the band gap. As a result, fault signals with high SNRs can be obtained for fault feature extraction. The effectiveness of weak harmonic and periodic impulse signal detection via line-defect PCs are investigated in numerical and experimental studies. All the numerical and experimental results indicate that line-defect PCs can be well used for extracting weak harmonic and periodic impulse signals. This work will provide potential for extracting weak signals in many practical engineering applications.

关键词： phononic crystals     line-defect     fault signal extraction     acoustic enhancement    

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Research progress of defect-engineered UiO-66(Zr) MOFs for photocatalytic hydrogen production

《能源前沿（英文）》 2021年 第15卷 第3期   页码 656-666 doi: 10.1007/s11708-021-0765-9

摘要： In recent years, defect-engineered Zr-based UiO-66 metal-organic frameworks (UiO-66(Zr) metal-organic frameworks (MOFs)) have shown huge advantages in catalytic, functional materials, adsorption, and other fields due to their large surface areas, well-ordered porous structures, and flexible tailorability. It is extremely challenging to introduce defect sites in the synthesis of MOFs to regulate the physicochemical properties of materials such as (energy band structure, pore structure, etc.) to obtain an excellent performance. This paper reviews the recent research results of synthesis methods, characterization technologies, and application fields of defect-engineered UiO-66(Zr) MOFs materials in order to provide new insights to synthesize high-performance UiO-66(Zr) MOFs materials and promote the development of UiO-66(Zr) in various fields.

关键词： defect engineering     metal-organic frameworks     UiO-66     photocatalysis    

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The defect-length effect in corrosion detection with magnetic method for bridge cables

Qiwei ZHANG, Rongya XIN

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 662-671 doi: 10.1007/s11709-018-0512-4

摘要：

Quantitative evaluation of the steel corrosion in cables is significant for the safe operation of cable-supported bridges. The magnetic flux (MF) examination shows great potential to detect the corrosion defect, or loss of metallic cross-sectional area (LMA). An LMA defect in steel cables can be measured accurately when it is longer than a certain length. However, for defects in early stage, where the length of corrosion area is short, the MF examination may produce unacceptable error. In this study, the effect of defect length on the MF examination for corrosion detection of bridge cables is investigated through theoretical analysis and model experiments. An original analytical model to quantify the influence of defect length is proposed based on the equivalent magnetic circuit method. Then, MF examination experiments are performed on a series of cable models with different defect lengths and locations to verify the analytical model. Further, parameter study is conducted based on the proposed analytical model to clarify the mechanism of the defect-length effect. The results show that the area loss caused by short corrosion damage will be underestimated if the defect-length effect is neglected, and this effect can be quantified efficiently with the proposed analytical model.

关键词： bridge cable     corrosion detection     defect length     MF examination     quantitative evaluation    

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Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

《机械工程前沿（英文）》 2021年 第16卷 第1期   页码 186-195 doi: 10.1007/s11465-020-0608-0

摘要： This paper presents a single-electromagnet levitation device to measure the densities and detect the internal defects of antimagnetic materials. The experimental device has an electromagnet in its lower part and a pure iron core in the upper part. When the electromagnet is activated, samples can be levitated stably in a paramagnetic solution. Compared with traditional magnetic levitation devices, the single-electromagnet levitation device is adjustable. Different currents, electromagnet shapes, and distances between the electromagnet and iron core are used in the experiment depending on the type of samples. The magnetic field formed by the electromagnet is strong. When the concentration of the MnCl aqueous solution is 3 mol/L, the measuring range of the single-electromagnet levitation device ranges from 1.301 to 2.308 g/cm . However, with the same concentration of MnCl aqueous solution (3 mol/L), the measuring range of a magnetic levitation device built with permanent magnets is only from 1.15 to 1.50 g/cm . The single-electromagnet levitation device has a large measuring range and can realize accurate density measurement and defect detection of high-density materials, such as glass and aluminum alloy.

关键词： single-electromagnet     electromagnetic levitation     density measurement     defect detection    

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Statistical analysis of recombination properties of the boron-oxygen defect in p-type Czochralski silicon

Nitin NAMPALLI,Tsun Hang FUNG,Stuart WENHAM,Brett HALLAM,Malcolm ABBOTT

《能源前沿（英文）》 2017年 第11卷 第1期   页码 4-22 doi: 10.1007/s11708-016-0442-6

摘要： This paper presents the application of lifetime spectroscopy to the study of carrier-induced degradation ascribed to the boron-oxygen (BO) defect. Specifically, a large data set of p-type silicon samples is used to investigate two important aspects of carrier lifetime analysis: ① the methods used to extract the recombination lifetime associated with the defect and ② the underlying assumption that carrier injection does not affect lifetime components unrelated to the defect. The results demonstrate that the capture cross section ratio associated with the donor level of the BO defect ( ) vary widely depending on the specific method used to extract the defect-specific recombination lifetime. For the data set studied here, it was also found that illumination used to form the defect caused minor, but statistically significant changes in the surface passivation used. This violation of the fundamental assumption could be accounted for by applying appropriate curve fitting methods, resulting in an improved estimate of (11.90±0.45) for the fully formed BO defect when modeled using the donor level alone. Illumination also appeared to cause a minor, apparently injection-independent change in lifetime that could not be attributed to the donor level of the BO defect alone and is likely related to the acceptor level of the BO defect. While specific to the BO defect, this study has implications for the use of lifetime spectroscopy to study other carrier induced defects. Finally, we demonstrate the use of a unit-less regression goodness-of-fit metric for lifetime data that is easy to interpret and accounts for repeatability error.

关键词： Czochralski silicon     boron-oxygen defect     injection dependent lifetime spectroscopy     goodness-of-fit     repeatability error    

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桥面铺装病害检测技术研究

郭成超,许朋飞,崔璨

《中国工程科学》 2017年 第19卷 第6期   页码 38-43 doi: 10.15302/J-SSCAE-2017.06.006

摘要：

在桥梁的全生命周期中，桥面板是最容易出现病害的部分。桥面铺装层常常由于施工方法选择不当、混凝土老化、钢筋锈蚀等原因产生各种病害，这对桥梁结构、使用性能都会造成不利影响，因此有必要对相关病害进行检测，并对桥面质量做出相关评价。本文介绍了国内外四种主要无损检测方法（半电池电位法、探地雷达法、冲击回波法、红外热成像法）的工作原理以及相应的检测设备，利用其中一种或几种方法能准确评估桥面板的恶化情况，对桥面板状况进行快速、无损检测，为实现桥面铺装的准确检测提供技术支持，从而减少结构病害，延长桥梁的使用寿命。

关键词： 桥面铺装     病害     无损检测    

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Effect of cavity defect on the triaxial mechanical properties of high-performance concrete

Yanbin ZHANG; Zhe WANG; Mingyu FENG

《结构与土木工程前沿（英文）》 2022年 第16卷 第5期   页码 600-614 doi: 10.1007/s11709-022-0821-5

摘要： The stress concentration of pipe structure or cavity defect has a great effect on the mechanical properties of the high-performance concrete (HPC) members in deep underground locations. However, the behaviour of HPC with cavities under triaxial compression is not understood, especially when pressurized liquid flows into the fractures from the cavity. This study aims to investigate the effect of the cavity and the confining pressure on the failure mechanisms, strengths, and deformation properties of HPC with a new experimental scheme. In this experiment, the pressurized liquid can only contact the surface of the sample in the cavity, while the other surfaces are isolated from the pressurized liquid. To further explore the effect of the cavity, the same experiments are also conducted on sealed and unsealed intact samples without a cavity. The failure modes and stress-strain curves of all types of the samples are presented. Under various confining pressures, all the samples with a cavity suffer shear failure, and there are always secondary tensile fractures initiating from the cavity sidewall. Additionally, it can be determined from the failure modes and the stress-strain curves that the shear fractures result from the sidewall failure. Based on the different effects of the cavity on the lateral deformations in different directions, the initiation of the sidewall fracture is well predicted. The experimental results show that both the increase of the confining pressure and the decrease of the cavity size are conducive to the initiation of sidewall fracture. Moreover, the cavity weakens the strength of the sample, and this study gives a modified Power-law criterion in which the cavity size is added as an impact factor to predict the strength of the sample.

关键词： high-performance concrete     cavity     conventional triaxial compression     pressurized liquid     modified power-law criterion    

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Construction of defect-containing UiO-66/MoSe heterojunctions with superior photocatalytic performance

《化学科学与工程前沿（英文）》 2023年 第17卷 第4期   页码 449-459 doi: 10.1007/s11705-022-2226-3

摘要： Metal–organic frameworks are recognized as promising multifunctional materials, especially metal–organic framework-based photocatalysts, which are considered to be ideal photocatalytic materials. Herein, a new type of UiO-66/MoSe2 composite was prepared using the solvothermal method. The optimum composite was selected by adjusting the mass ratio of UiO-66 and MoSe2. X-ray diffraction analysis showed that the mass ratio influenced the crystal plane exposure rate of the composite, which may have affected its photocatalytic performance. The composite is composed of ultra-thin flower-like MoSe2 that wrapped around cubic UiO-66, a structure that increases the abundance of active sites for reactions and is more conducive to the separation of carriers. The photocatalytic properties of the composite were evaluated by measuring the degradation rate of Rhodamine B and the catalyst’s ability to reduce Cr(VI)-containing wastewater under visible light irradiation. Rhodamine B was decolorized completely in 120 min, and most of the Cr(VI) was reduced within 150 min. The photochemical mechanism of the complex was studied in detail. The existence of Mo6+ and oxygen vacancies, in addition to the Z-type heterojunction promote the separation of electrons and holes, which enhances the photocatalytic effect.

关键词： UiO-66/MoSe2     photocatalysis     dye-containing wastewater     heavy metal wastewater     oxygen vacancies    

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SUSTAINABLE NITROGEN MANAGEMENT IN AUSTRALIAN AGROECOSYSTEMS: CHALLENGES AND OPPORTUNITIES

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 366-372 doi: 10.15302/J-FASE-2022447

摘要：

● There is huge potential for improvement of nitrogen management in Australia.

关键词： Australian agroecosystems     reactive nitrogen     sustainable development    

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SUSTAINABLE NITROGEN MANAGEMENT FOR VEGETABLE PRODUCTION IN CHINA

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 373-385 doi: 10.15302/J-FASE-2022455

摘要：

● Sustainable nitrogen management strategies for Chinese vegetable production are summarized.

关键词： enhanced-efficiency nitrogen fertilizer     integrated knowledge and products strategy     nitrogen rate     reactive nitrogen loss     vegetable     yield    

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EFFECTS OF SUBSTITUTION OF MINERAL NITROGEN WITH ORGANIC AMENDMENTS ON NITROGEN LOSS FROM SLOPING CROPLAND

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 396-406 doi: 10.15302/J-FASE-2022456

摘要：

● Interflow acts as the dominant pathway for N loss loadings.

关键词： improved fertilization regime     interflow     nitrogen forms     nitrogen leaching     purple soil     sloping cropland    

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Nitrogen distribution in the products from the hydrothermal liquefaction of sp. and sp.

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 985-995 doi: 10.1007/s11705-021-2126-y

摘要： The high contents of nitrogen-containing organic compounds in biocrude obtained from hydrothermal liquefaction of microalgae are one of the most concerned issues on the applications and environment. In the project, Chlorella sp. and Spirulina sp. were selected as raw materials to investigate the influence of different reaction conditions (i.e., reaction temperature, residence time, solid loading rate) on the distribution of nitrogen in the oil phase and aqueous phase. Three main forms of nitrogen-containing organic compounds including nitrogen-heterocyclic compounds, amide, and amine were detected in biocrudes. The contents of nitrogen-heterocyclic compounds decreased with temperature while amide kept increasing. The effect of residence time on the components of nitrogen-containing organic compounds was similar with that of temperature. However, the influence of solid loading rate was insignificant. Moreover, it was also found that the differences of amino acids in the protein components in the two microalgae might affect the nitrogen distribution in products. For example, nitrogen in basic amino acids of Spirulina sp. preferred to go into the aqueous phase comparing with the nitrogen in neutral amino acids of Chlorella sp. In summary, a brief reaction map was proposed to describe the nitrogen pathway during microalgae hydrothermal liquefaction.

关键词： microalgae     hydrothermal liquefaction     biocrude     nitrogen distribution    

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SOIL NITROGEN CYCLING AND ENVIRONMENTAL IMPACTS IN THE SUBTROPICAL HILLY REGION OF CHINA: EVIDENCE FROM

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 407-424 doi: 10.15302/J-FASE-2022448

摘要：

● Soil nitrogen fluxes and influencing factors were reviewed in the subtropical hilly regions.

关键词： nitrogen cycling     soil nitrogen     nitrogen deposition     greenhouse gases emission     non-point source pollution     nitrogen use efficiency    

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PROGRESS ON IMPROVING AGRICULTURAL NITROGEN USE EFFICIENCY: UK-CHINA VIRTUAL JOINT CENTERS ON NITROGEN

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 475-489 doi: 10.15302/J-FASE-2022459

摘要：

● Virtual joint centers on N agronomy were established between UK and China.

关键词： CINAg     N-CIRCLE     nitrogen use efficiency     reactive nitrogen     sustainable production    

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标题 作者 时间 类型 操作

Tuning nitrogen defects and doping sulfur in carbon nitride for enhanced visible light photocatalytic

期刊论文

Acoustic fault signal extraction via the line-defect phononic crystals

期刊论文

Research progress of defect-engineered UiO-66(Zr) MOFs for photocatalytic hydrogen production

期刊论文

The defect-length effect in corrosion detection with magnetic method for bridge cables

Qiwei ZHANG, Rongya XIN

期刊论文

Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

期刊论文

Statistical analysis of recombination properties of the boron-oxygen defect in p-type Czochralski silicon

Nitin NAMPALLI,Tsun Hang FUNG,Stuart WENHAM,Brett HALLAM,Malcolm ABBOTT

期刊论文

桥面铺装病害检测技术研究

郭成超,许朋飞,崔璨

期刊论文

Effect of cavity defect on the triaxial mechanical properties of high-performance concrete

Yanbin ZHANG; Zhe WANG; Mingyu FENG

期刊论文

Construction of defect-containing UiO-66/MoSe heterojunctions with superior photocatalytic performance

期刊论文

SUSTAINABLE NITROGEN MANAGEMENT IN AUSTRALIAN AGROECOSYSTEMS: CHALLENGES AND OPPORTUNITIES

期刊论文

SUSTAINABLE NITROGEN MANAGEMENT FOR VEGETABLE PRODUCTION IN CHINA

期刊论文

EFFECTS OF SUBSTITUTION OF MINERAL NITROGEN WITH ORGANIC AMENDMENTS ON NITROGEN LOSS FROM SLOPING CROPLAND

期刊论文

Nitrogen distribution in the products from the hydrothermal liquefaction of sp. and sp.

期刊论文

SOIL NITROGEN CYCLING AND ENVIRONMENTAL IMPACTS IN THE SUBTROPICAL HILLY REGION OF CHINA: EVIDENCE FROM

期刊论文

PROGRESS ON IMPROVING AGRICULTURAL NITROGEN USE EFFICIENCY: UK-CHINA VIRTUAL JOINT CENTERS ON NITROGEN

期刊论文