Journal of Applied Spectroscopy
·
2018
·Vol. 85
·期 1
·84-89
·
IF 0.611
Zhang J.,Xia T.,Chen Q.,Sun Q.,Deng Y.,Wang C.
The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as "fingerprints" to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient–mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.
研究领域:
化学
·
光谱学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING COMMUNICATIONS
·
2023
·
IF 2.5
Junxiao Luo,Weidong Shi,Guofeng Fang,Liang Chen,Liang Zhang
Adding nanoparticles with high thermal conductivity into the work fluid is one of the most significant ways to enhance heat transfer. In this article, the influences of nanoparticle mass concentration (0.5–10.0 wt.%) and temperature (5–25 °C) were investigated on the viscosity of TiO2-propylene glycol nanofluid. At the same time, eight kinds of mass concentrations (0.5–10.0 wt.%) were used to investigate the changing regularity on the surface tension of nanofluid; Accordingly, the modified correlations including nanoparticle concentration were proposed respectively. The experimental results show that the viscosity of the nanofluid increases with the increase in particle concentration. Within the concentration of 10.0 wt.%, the viscosity increases by about 7.0% for every 1.0 wt.%. While the viscosity decreases with the increase in the temperature. The surface tension of the mixture increases slowly with the increase in particle concentration. Within 2.0 wt.%, the surface tension of nanofluid increases by less than 1.0% for every 0.5 wt.%, when the concentration of nanofluid exceeds 2.0 wt.%, surface tension raises less than 1.0% per 2.0 wt.%.
研究领域:
热能工程
·
流体力学
·
纳米技术
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DOI
高影响因子
COLLOID AND POLYMER SCIENCE
·
2014
·Vol. 293
·期 2
·473-479
·
IF 2.41
Jiang Yanping,Li Xianggao,Wang Shirong,Xiao Yin
In this paper, we reported a novel non-aqueous electrorheological (ER) fluid structured by TiO 2 nano-particle-modified poly (methyl methacrylate) (PMMA/TiO 2 ) dispersed in low viscosity Isopar L and its electrorheological behaviors were researched. Titanium dioxide nano-particles modified with poly (methyl methacrylate) were prepared via in situ polymerization and characterized by Fourier transform infrared, thermogravimetry, and transmission electron microscopy. The thickness of the cladding layer of nano-titanium dioxide surface was about 2∼3 nm, and the cladding rate was 1.437 %. A non-aqueous electrorheological (ER) fluid was constituted by PMMA/TiO 2 particles dispersed in Isopar L. The influence of the electric field intensity, the mass concentration of the PMMA/TiO 2 , and the temperature on the electrorheological properties of ER fluid were discussed, respectively. The research results showed that the ER fluid performed a well rheological property when an external electric field was applied, and with the increase of the electric field intensity, from 0 to 4.5 kV/mm, the shear stress was increased from about 3 to 30 Pa. Meanwhile, the electrorheological effect and shear stress were also strengthened with temperature elevated, and the mass concentration of PMMA/TiO 2 particles increased in dispersed system, respectively.
研究领域:
材料科学
·
化学工程
·
纳米技术
·
流变学
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产品关联
DOI
高影响因子
ENVIRONMENTAL RESEARCH
·
2025
·
IF 7.7
Qingcun Li,Qingsheng Bai,Ronggang Zheng,Peng Li,Rui Liu,Sujuan Yu,Jingfu Liu
Micro- and nanoplastics (MNPs) have drawn growing concerns because of their potential adverse effects on aquatic ecosystems. However, limited information is available regarding their concentration and distribution in the actual environment, particularly for nanoplastics (NPs). Herein, forty-eight sampling sites were established across the entire Taihu Lake to comprehensively investigate small MNP (<100 μm) pollution. By pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), six kinds of MNPs in Taihu Lake, namely polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polystyrene (PS), and polymethyl methacrylate (PMMA) were quantified. Total mass concentrations of the six MNPs in the collected surface water samples ranged from 381 to 1356 μg/L. Specifically, the concentrations of small microplastics (1–100 μm) ranged from 229 to 1182 μg/L, and those of nanoplastics (<1 μm) ranged from 88 to 305 μg/L. The mass concentrations of the six MNPs were as follows: 20.3–635.7 μg/L for PE, 46.6–281.4 μg/L for PP, 81.8–410.6 μg/L for PET, 62.8–445.8 μg/L for PVC,
研究领域:
环境科学
·
生态毒理学
·
水污染
·
微塑料污染
·
分析化学
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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）