scholarly journals Study of 2,4-D Spectral Characteristics and Its Detection in Zizania Latifolia Using Terahertz Time-Domain Spectroscopy

2019 ◽  
Vol 9 (11) ◽  
pp. 2248
Author(s):  
Pengcheng Nie ◽  
Chengyong Cai ◽  
Fangfang Qu ◽  
Lei Lin ◽  
Tao Dong ◽  
...  
Keyword(s):  
Time Domain ◽  
Density Functional ◽  
Terahertz Spectroscopy ◽  
Spectral Characteristics ◽  
Geometry Optimization ◽  
Main Peak ◽  
Terahertz Time Domain Spectroscopy ◽  
Zizania Latifolia ◽  
Time Domain Spectroscopy ◽  
2,4 Dichlorophenoxyacetic Acid

2,4-Dichlorophenoxyacetic acid (2,4-D) is a common plant growth regulator, which can remain in food and, with long-term consumption, threaten human health. Therefore, it is necessary to propose an effective detection method. Terahertz time-domain spectroscopy technique (THz-TDS) has good advantages in the quantitative and qualitative analysis of most biomolecules due to its rich fingerprint characteristics. In this paper, density functional theory (DFT) was applied to geometry optimization and frequency vibration calculation of 2,4-D, and THz-TDS was used to quantitatively detect 2,4-D in Zizania latifolia. The results showed that there were three characteristic absorption peaks of 2,4-D at 1.36, 1.60, and 2.38 THz, respectively, and the theoretical spectra were in good consistency with experimental spectra, with slight discrepancies. Additionally, the absorption peak at 1.36 THz had the best absorption characteristics and was chosen as the main peak for 2,4-D quantitative analysis. It was demonstrated that the limits of detection (LOD) of 2,4-D in Zizania latifolia were found to be as low as 5%, the absorbance intensity at 1.36 THz showed a good linear relationship (R2 = 0.9854) with 2,4-D concentration from 5% to 30%, and the recovery was 93.29%–98.75%. Overall, this work enriched the fingerprint database of pesticide molecules on the basis of terahertz spectroscopy and could provide a technical support for the detection of 2,4-D in food by terahertz spectroscopy.

Determination of pesticides in a flour substrate by chemometric methods using terahertz spectroscopy

2018 ◽  
Vol 10 (42) ◽  
pp. 5097-5104 ◽  
Author(s):  
Binghua Cao ◽  
Hui Li ◽  
Mengbao Fan ◽  
Wei Wang ◽  
Mengyun Wang
Keyword(s):  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Chemometric Methods ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy

Terahertz time-domain spectroscopy combined with chemometrics is utilized to identify imidacloprid and carbendazim in a flour substrate.

scholarly journals Transformation and dehydration kinetics of methylene blue hydrates detected by terahertz time-domain spectroscopy

RSC Advances ◽  
2017 ◽  
Vol 7 (66) ◽  
pp. 41667-41674 ◽  
Author(s):  
Shihan Yan ◽  
Hua Zhang ◽  
Zhongbo Yang ◽  
Mingjie Tang ◽  
Mingkun Zhang ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Dehydration Kinetics ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Thz Absorption ◽  
Kinetics Of ◽  
Absorption Features ◽  
Crystalline Hydrates

Three methylene blue crystalline hydrates were identified by terahertz spectroscopy according to their different THz absorption features.

scholarly journals Flow cell to study crystallisation processes in-situ using terahertz time-domain spectroscopy

2021 ◽  
Author(s):  
Qi Li ◽  
Johanna Kölbel ◽  
Terry Threlfall ◽  
Axel Zeitler
Keyword(s):  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Relaxation Dynamics ◽  
Terahertz Time Domain Spectroscopy ◽  
Great Opportunity ◽  
Time Domain Spectroscopy ◽  
Wide Range ◽  
Crystallisation Process ◽  
Static Conditions

A versatile setup based on terahertz time-domain spectroscopy was developed to monitor the process of crystallisation and characterise the structure of the crystals as well as the dynamics of the solvent in situ. The setup can be used to investigate crystallisation processes over a wide range of temperature, either under static conditions or during continuous flow. An attached optical imaging probe can be used to monitor the process in parallel to the terahertz spectroscopy investigation. The implementation of terahertz spectroscopy offers a great opportunity to investigate the dielectric relaxation dynamics of the solvent and the vibrational modes characteristic for the crystalline phases simultaneously. The details of the crystallisation setup are demonstrated at the example of the crystallisation process of magnesium sulphate heptahydrate from its aqueous phase.

scholarly journals Terahertz spectroscopy and imaging for gastric cancer diagnosis

2020 ◽  
Author(s):  
Faustino Wahaia ◽  
Irmantas Kašalynas ◽  
Linas Minkevičius ◽  
Catia Carvalho Silva ◽  
Andrzej Urbanowicz ◽  
...  
Keyword(s):  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Human Cancer ◽  
Terahertz Waves ◽  
Terahertz Time Domain Spectroscopy ◽  
Tissue Samples ◽  
Time Domain Spectroscopy ◽  
Affected Tissue ◽  
Gastrointestinal Tissue ◽  
Thz Absorption

Terahertz waves are sensitive to differences in biological tissue hydration, we present promising results regarding the feasibility of applying this with terahertz time-domain spectroscopy and imaging for early detection of cancer through the characterisation of human gastrointestinal tissue with cancer-affected regions. To do that, healthy (normal) and carcinoma-affected gastric tissue samples at different stages were measured using transmission terahertz time-domain spectroscopy in the frequency range of 0.15–2.00 THz. Absorption coefficients and refractive index spectra of both normal and carcinoma-affected tissue were extracted and analysed. The results confirm that the techniques may be powerful tools to perform qualitative, early diagnosis of human cancer.

The Study of Terahertz Time-Domain Spectroscopy of Benzoyl Peroxide

2014 ◽  
Vol 633-634 ◽  
pp. 521-525
Author(s):  
Zhi Long Zhou ◽  
Xiai Chen ◽  
Lu Han ◽  
Qing Hua Zhang ◽  
Xian Li
Keyword(s):  
Experimental Study ◽  
Benzoyl Peroxide ◽  
Absorption Spectra ◽  
Time Domain ◽  
Spectral Characteristics ◽  
Experimental Result ◽  
Wave Band ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Terahertz Absorption

The spectral characteristics of benzoyl peroxide in the range of 0.3 to 1.6 in THz region is obtained by THz time-domain spectroscopy, the refraction and absorption spectra of benzoyl peroxide is got,meanwhile. The experimental result shows that, the benzoyl peroxide has the absorption peak at the wave band of 0.36621THz,0.498THz,0.92285THz,1.11328THz, the most obvious of which is at the wave band of 0.92285THz.The terahertz absorption spectra of the mixture of flour and benzoyl peroxide is studied at the same time.This experimental study provides a new method to detect benzoyl peroxide illegally added in food.

scholarly journals Terahertz Time Domain Spectroscopy of Transformer Insulation Paper after Thermal Aging Intervals

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2124 ◽  
Author(s):  
Liang Wang ◽  
Chao Tang ◽  
Shiping Zhu ◽  
Shengling Zhou
Keyword(s):  
Time Domain ◽  
Thermal Aging ◽  
Density Functional ◽  
Degree Of Polymerization ◽  
Transformer Oil ◽  
Optical Parameters ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Paper Insulation ◽  
Transformer Insulation

An accelerated thermal aging process was used to simulate the condition of paper insulation in transformer oil-paper systems. Optical parameters of the insulation paper after various aging intervals were analyzed with terahertz time-domain spectroscopy (THz-TDS) over the range 0.1~1.8 THz. The result shows that the paper had seven absorption peaks at 0.19, 0.49, 0.82, 1.19, 1.43, 1.53, and 1.74 THz, and density functional theory of B3LYP/6-311G+ (d, p) was used to simulate the molecular dynamics of the repeating component (cellobiose) of the cellulose paper. Theoretical spectra were consistent with experiment, which had absorption peaks at 0.18, 0.82, 1.47, and 1.53 THz in the same frequency range. At the same time, the paper samples after various aging intervals had different refractive indexes, and least squares fitting revealed a linear relationship between the degree of polymerization and the refractive index of the paper. Hence, this paper demonstrates that THz-TDS could be used to analyze the aging condition of transformer insulation paper and provides the theoretical and experimental basis for detection.

scholarly journals The Application of Terahertz Time-Domain Spectroscopy to Identification of Potato Late Blight and Fusariosis

Pathogens ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1336
Author(s):  
Nikita V. Penkov ◽  
Mikhail V. Goltyaev ◽  
Maxim E. Astashev ◽  
Dmitry A. Serov ◽  
Maxim N. Moskovskiy ◽  
...  
Keyword(s):  
Late Blight ◽  
Time Domain ◽  
Spectral Characteristics ◽  
Potato Tubers ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
New Methods ◽  
Focus Of Infection ◽  
First Time

Fusarium and late blight (fungal diseases of cereals and potatoes) are among the main causes of crop loss worldwide. A key element of success in the fight against phytopathogens is the timely identification of infected plants and seeds. That is why the development of new methods for identifying phytopathogens is a priority for agriculture. The terahertz time-domain spectroscopy (THz-TDS) is a promising method for assessing the quality of materials. For the first time, we used THz-TDS for assessing the infection of seeds of cereals (oats, wheat and barley) with fusarium and potato tubers of different varieties (Nadezhda and Meteor) with late blight. We evaluated the refractive index, absorption coefficient and complex dielectric permittivity in healthy and infected plants. The presence of phytopathogens on seeds was confirmed by microscopy and PCR. It is shown, that Late blight significantly affected all the studied spectral characteristics. The nature of the changes depended on the variety of the analyzed plants and the localization of the analyzed tissue relative to the focus of infection. Fusarium also significantly affected all the studied spectral characteristics. It was found that THz-TDS method allows you to clearly establish the presence or absence of a phytopathogens, in the case of late blight, to assess the degree and depth of damage to plant tissues.

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