Micromachines
·
2021
·Vol. 12
·期 9
·1034
·
IF 2.891
Lvhan Zhou,Qian Zhang,Xiangchun Xu,Xinming Huo,Qian Zhou,Xiaohao Wang,Quan Yu
The coupling of the microfluidic chip to mass spectrometry (MS) has attracted considerable attention in the area of chemical and biological analysis. The most commonly used ionization technique in the chip–MS system is electrospray ionization (ESI). Traditional chip-based ESI devices mainly employ direct electrical contact between the electrode and the spray solvent. In this study, a microchip ESI source based on a novel polarization-splitting approach was developed. Specifically, the droplet in the microchannel is first polarized by the electric field and then split into two sub-droplets. In this process, the charge generated by polarization is retained in the liquid, resulting in the generation of two charged droplets with opposite polarities. Finally, when these charged droplets reach the emitter, the electrospray process is initiated and both positive and negative ions are formed from the same solution. Preliminary experimental results indicate that the coupling of this polarization-splitting ESI (PS-ESI) chip with a mass spectrometer enables conventional ESI-MS analysis of various analytes.Keywords:microfluidic chip;mass spectrometry;electrospray ionization;induced polarization
研究领域:
分析化学
·
生物分析
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Bing Li,Shenglong Wang,Chang Liu,Yangguang Xu,Weili Deng,Jianghong Yuan,Jinjin Zhao,Weiqing Yang,Xiangyu Li
Owing to the flexibility, lightweight, long-life and low cost, polymers are promising candidates to realize electromechanical conversion in wearable electronics. The flexoelectric effect enables non-piezoelectric materials to achieve electromechanical coupling, thereby broadening application ranges of nonpolar polymers. In this work, the porous samples of polydimethylsiloxane (PDMS) with various pore sizes and porosities are fabricated by the sacrificial salt template method and the chemical gas foaming method. The flexoelectric polarization response can be tuned directly by the structural characters of the porous PDMS . The transverse flexoelectric coefficient of porous PDMS can reach approximately 2.9 times the counterpart of the bulk one. The competitive mechanism between strain gradient and permittivity is proposed on flexoelectricity of random porous media by dielectric impedance spectrums and finite element analyses. The present regulation of flexoelectricity provides an alternative to electromechanical conversion. With the deep learning technique based on one-dimensional convolution neural networks, actions of both sick and normal legs of various stroke patients can be well recognized by the designed device of rehabilitation. The present rehabilitation monitoring system, which is an innovative application of the flexoelectricity in the porous polymers, offers a new approach to support physical therapy for post-stroke patients.
研究领域:
生物医学工程
·
材料科学
·
康复医学
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Minerals Metallurgy and Materials
·
2025
·Vol. 32
·期 3
·645-656
·
IF 7.2
Wang Long,Liu Jiurong,Xie Shenghui,Deng Yanli,Wang Zhou,Hou Shanyue,Yue Shengying,Wang Gang,Wu Na,Zeng Zhihui
W-type barium–nickel ferrite (BaNi 2 Fe 16 O 27 ) is a highly promising material for electromagnetic wave (EMW) absorption because of its magnetic loss capability for EMW, low cost, large-scale production potential, high-temperature resistance, and excellent chemical stability. However, the poor dielectric loss of magnetic ferrites hampers their utilization, hindering enhancement in their EMW-absorption performance. Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but remains challenging. Here, an efficient strategy substituting Ba 2+ with rare earth La 3+ in W-type ferrite was proposed for the preparation of novel La-substituted ferrites (Ba 1− x La x Ni 2 Fe 15.4 O 27 ). The influences of La 3+ substitution on ferrites’ EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed. La 3+ efficiently induced lattice defects, enhanced defect-induced polarization, and slightly reduced the ferrites’ bandgap, enhancing the dielectric properties of the ferrites. La 3+ also enhanced the ferromagnetic resonance loss and strengthened magnetic properties. These effects considerably improved the EMW-absorption performance of Ba 1− x La x Ni 2 Fe 15.4 O 27 compared with pure W-type ferrites. When x = 0.2, the best EMW-absorption performance was achieved with a minimum reflection loss of −55.6 dB and effective absorption bandwidth (EAB) of 3.44 GHz.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
CARBON
·
2025
·
IF 11.6
Shijie Zhang,Jiajun Zheng,Changpeng Lv,Di Lan,Qingfeng Tian,Zhenguo Gao,Siyuan Zhang,Zhiwei Zhao,Shichang Cai,Guanglei Wu
The incorporation of a built-in electric field (BIEF) in nanocomposites has been well-recognized as a mainstream approach for enhancing the interface polarization. Nevertheless, the effect of sole BIEF on the dielectric loss is insufficient, and its combination with other loss mechanisms is necessary to achieve optimized electromagnetic wave performances. Herein, the nano carbon hybrids with Cu–ZnO Schottky BIEF with abundant defects were designed and derived through an etching and ligand exchange process, which involved the conversion of CuZn-BTC into a bimetallic ZIF structure. The conversion process effectively controlled the morphologies and induced a significant density of defects in the derivatives, thereby imparting diverse electrical conductivities and dielectric properties to the composites. This was achieved through the modulation of the cell volumes of Cu–ZnO polycrystals, the oxygen vacancies in ZnO, the nitrogen defects within the carbon matrix, and the creation of extensive heterointerfaces. The analysis indicated that the polarization relaxation dominated the dielectric loss. When the H 2 O/methanol in etching solvent was 3:7, the derived composite (S2) exhibited well matched impedance, and synergistic enhancement of BIEF effect and defect-induced polarization. Attributed to these merits, S2 achieved an ultra-wide effective absorption bandwidth (EAB) of 7.12 GHz at 2.3 mm. Notably, the EAB exceeded 6.0 GHz when the matched thickness ranged from 1.8 mm to 2.7 mm. This study can introduce a novel approach for the development of advanced absorbers based on the Schottky BIEF.
研究领域:
材料科学
·
电磁学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale
·
2024
·
IF 5.8
Haitao Li,Yingying Zhang,Han Dai,Veronica Pereir,Junfeng Zhao,Hiang Kwee Lee
Polyvinylidene fluoride (PVDF)-based piezoelectric catalysts show promise in mechanical force-driven catalysis due to their good biocompatibility, flexibility, and ease of fabrication. However, the catalytic activity of pristine PVDF is limited due to its low piezoelectric phase content (<20%), poor orientation, and low surface carrier concentration. Here, we introduce an efficient PVDF-based composite nano-catalyst (rGO/PVDF) with high piezoelectric catalytic performance. We achieve this by employing a composite strategy that combines nanoscale water-induced polarization with polar functional group-modified graphene (rGO) serving as a nanoelectrode. The nanoscale water polarization effect, together with the two-dimensional planar structure of PVDF and the modified graphene's polar functional groups, effectively induces orientation in the PVDF piezoelectric phase to increase the functional β phase content. As a result, the β phase content and crystallinity of rGO/PVDF reach 95% and 40%, respectively, which are 600% and 170% higher compared to those of pristine PVDF. This enhancement plays a crucial role in endowing the material with strong force-to-electricity conversion characteristics. Additionally, the surface-modified rGO also boosts PVDF's surface carrier concentration and provides active sites for catalysis on the rGO/PVDF composite. Notably, under optimized conditions, our catalyst achieves a ∼99.1% degradation rate of organic pollutants (10 mg L−1) after 12 minutes of sonication at 240 W and maintains a high efficiency of ∼93.7% even at a 10 times higher pollutant concentration (100 mg L−1). Our piezoelectric catalyst also demonstrates efficient H2O2 production at 95.8 mmol grGO−1 h−1, which is ∼9-fold and ∼134-fold higher than those of untreated PVDF and previously reported PVDF-based piezoelectric catalysts, respectively. This work paves the way for the development of highly efficient PVDF-based piezoelectric catalysts, thereby offering valuable insights for the advancement of mechanically driven catalysis in the environmental, energy, and chemical sectors.
研究领域:
材料科学
·
环境科学
·
催化
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）