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 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.

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.

STANDOFF SENSING AND IMAGING OF EXPLOSIVE RELATED CHEMICAL AND BIO-CHEMICAL MATERIALS USING THz-TDS

2007 ◽  
Vol 17 (02) ◽  
pp. 239-249 ◽  
Author(s):  
Hua Zhong ◽  
Albert Redo-Sanchez ◽  
Xi-Cheng Zhang
Keyword(s):  
Remote Sensing ◽  
Glutamic Acid ◽  
Time Domain ◽  
Large Scale ◽  
Imaging System ◽  
Terahertz Time Domain Spectroscopy ◽  
Multiple Absorption ◽  
Thz Absorption ◽  
Absorption Features ◽  
Chemical Materials

We report the sensing and imaging of explosive related chemical and bio-chemical materials by using terahertz time domain spectroscopy (THz-TDS) at standoff distance. The 0.82 THz absorption peak of RDX is observed at a distance up to 30 m away from the emitter and receiver. Multiple absorption features of RDX, 2,4-DNT and Glutamic Acid are identified by using a large scale 2-D imaging system. These results support the feasibility of using THz-TDS technique in remote sensing and detection of chemical materials.

SIGNATURE AND SIGNAL GENERATION ASPECTS OF EXPLOSIVE DETECTION USING TERAHERTZ TIME-DOMAIN SPECTROSCOPY

2008 ◽  
Vol 18 (02) ◽  
pp. 295-306 ◽  
Author(s):  
ROBERT OSIANDER ◽  
MICHAEL J. FITCH ◽  
MEGAN LEAHY-HOPPA ◽  
YAMAC DIKMELIK ◽  
JAMES B. SPICER
Keyword(s):  
Time Domain ◽  
Explosive Detection ◽  
Reflection Spectra ◽  
Terahertz Time Domain Spectroscopy ◽  
Reflection And Transmission ◽  
Time Domain Spectroscopy ◽  
Grain Sizes ◽  
Full Analysis ◽  
Characteristic Features ◽  
Absorption Features

In the last few years, a number of researchers including our collaboration have assembled databases of terahertz (THz) time-domain spectroscopy (TDS) absorption spectra from bulk explosives. While this was a necessary and important step in demonstrating the feasibility of THz TDS for explosives detection, the goal of our research is to demonstrate selectivity of THz spectra from the clutter of background spectra coming from the substrate such as soil or sand. We have investigated THz TDS reflection spectra from sand with different grain sizes as well as from metallic powders in order to distinguish between the signals reflected from the rough surfaces compared to distributed reflections at finite depths in the granular material. With marker materials such as tartaric acid, which have absorption features in the 1-2 THz range, we have investigated the reflection spectra of granular substrates with marker chemicals, and compared this to reflection and transmission spectra of solid materials prepared in polyethylene sample pellets. In principle, the same experiments can then be performed using TNT, RDX, HMX and PETN, which all have characteristic features in the 0.5-8 THz frequency range. Absolute molecular absorption coefficients can be measured as well, and we include here preliminary values for RDX. A full analysis will be reported elsewhere.

Characteristic fingerprint spectrum of neurotransmitter norepinephrine with broadband terahertz time-domain spectroscopy

The Analyst ◽  
2019 ◽  
Vol 144 (8) ◽  
pp. 2504-2510 ◽  
Author(s):  
Zhongjie Zhu ◽  
Chao Cheng ◽  
Chao Chang ◽  
Guanhua Ren ◽  
Jianbing Zhang ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Time Domain ◽  
Vibrational Modes ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Thz Absorption ◽  
Broadband Terahertz

A broadband THz absorption spectrum of NE corresponds to specific vibrational modes.

scholarly journals Terahertz Time-domain Spectroscopy as a Novel Tool for Crystallographic Analysis in Cellulose: Cellulose I to Cellulose Ii, Tracing the Structural Changes Under Chemical Treatment

2021 ◽  
Author(s):  
Han Wang ◽  
Hiroki Kataoka ◽  
Satoru Tsuchikawa ◽  
Tetsuya Inagaki
Keyword(s):  
Absorption Coefficient ◽  
Time Domain ◽  
Structural Changes ◽  
Crystalline Lattice ◽  
Thz Radiation ◽  
Cellulose Ii ◽  
Cellulose I ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Thz Absorption

Abstract Terahertz time-domain spectroscopy (THz-TDS) has expanded possibilities in cellulose crystallography research, as THz radiation detects most intermolecular vibrations and responds to the phonons of crystalline lattices. In this study, we traced the transformation of the cellulose crystalline lattice from cellulose I to cellulose II by THz-TDS and X-ray powder diffraction. Cellulose II was obtained by treating cellulose I with NaOH of different concentrations (0 wt%–20 wt%, at 2 wt% intervals). The THz absorption coefficient spectra of cellulose II showed three characteristic peaks (at 1.32 THz, 1.76 THz, and 2.77 THz). The THz absorption coefficient spectra of cellulose II treated with 20-wt% NaOH and cellulose I without NaOH treatment were fitted by a seventh-order Fourier series. Thus, the THz absorption coefficient spectra of samples treated with NaOH of other concentrations could be considered a combination of these two fitted profiles of cellulose I and cellulose II, multiplied by different coefficients. Furthermore, the coefficients could reflect the relative contents of cellulose I and cellulose II in the samples.

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.

Study of the Drying Kinetics of a Hyaluronic Acid Pellet by Using Terahertz Time-Domain Spectroscopy

2019 ◽  
Vol 75 (11) ◽  
pp. 895-898
Author(s):  
Hee Jun Shin ◽  
Jae Hun Park ◽  
Eun-Kyung Lim ◽  
Hyeung Mun Kim ◽  
Young-Min Huh ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Time Domain ◽  
Drying Kinetics ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Acid Pellet ◽  
Kinetics Of
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