The frequency range in THz spectroscopy and its relationship to the water content in food: A first approach

2021 ◽  
Vol 12 (4) ◽  
pp. 625-634
Author(s):  
Hubert Arteaga ◽  
Noemí León-Roque ◽  
Jimy Oblitas
Keyword(s):  
Water Content ◽  
Thz Spectroscopy ◽  
Frequency Range

scholarly journals Temperature dependent poly(L-lactide) crystallization investigated by Fourier transform terahertz spectroscopy

2021 ◽  
Author(s):  
Seiichiro Ariyoshi ◽  
Satoshi Ohnishi ◽  
Hikaru Mikami ◽  
Hideto Tsuji ◽  
Yuki Arakawa ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Absorption Spectra ◽  
Terahertz Spectroscopy ◽  
Thz Spectroscopy ◽  
Frequency Range ◽  
Temperature Dependent ◽  
Thz Absorption

Poly(L-lactide) (PLLA) was investigated by Fourier transform terahertz (THz) spectroscopy over the frequency range of 1.0 – 8.5 THz. THz absorption spectra were acquired for PLLA samples isothermally crystallized at...

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

scholarly journals Soil Moisture Estimate Uncertainties from the Effect of Soil Texture on Dielectric Semiempirical Models

2020 ◽  
Vol 12 (14) ◽  
pp. 2343
Author(s):  
Jing Liu ◽  
Qinhuo Liu
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Texture ◽  
Dielectric Behavior ◽  
Volumetric Water Content ◽  
Frequency Range ◽  
Dielectric Model ◽  
Texture Effect ◽  
Semi Empirical ◽  
Semiempirical Models

Soil texture has been shown to affect the dielectric behavior of soil over the entire frequency range. Three universally employed dielectric semiempirical models (SEMs), the Dobson model, the Wang–Schmugge model and the Mironov model, as well as a new improved SEM known as the soil semi-empirical mineralogy-related-to-water dielectric model (SSMDM), incorporate a significant soil texture effect in different ways. In this paper, soil moisture estimate uncertainties from the effect of soil texture on these four SEMs are systematically and widely investigated over all soil texture cases at different frequencies between 1.4 and 18 GHz for volumetric water content levels between 0.0 and 0.4 m3/m3 from the perspective of two aspects: soil dielectric model discordance and soil texture discordance. Firstly, the effect of soil texture on these four dielectric SEMs is analyzed. Then, soil moisture estimate uncertainties due to the effect of soil texture are carefully investigated. Finally, the applicability of these SEMs is discussed, which can supply references for their choice. The results show that soil moisture estimate uncertainties are small and satisfy the 4% volumetric water content retrieval requirement in some cases. However, in other cases, it may contribute relatively significant uncertainties to soil moisture estimates and correspond to a difference that exceeds the 4% volumetric water content requirement, with potential for the largest deviations to exceed 0.22 m3/m3.

THz SPECTROSCOPY OF PROTEINS IN WATER: DIRECT ABSORPTION AND CIRCULAR DICHROISM

2007 ◽  
Vol 17 (04) ◽  
pp. 709-718 ◽  
Author(s):  
JING XU ◽  
KEVIN W. PLAXCO ◽  
S. JAMES ALLEN
Keyword(s):  
Circular Dichroism ◽  
Absorption Spectra ◽  
Magnetic Circular Dichroism ◽  
Broad Band ◽  
Thz Spectroscopy ◽  
Direct Absorption ◽  
Frequency Range ◽  
Egg White Lysozyme ◽  
Terahertz Absorption ◽  
Circular Dichroïsm

Many of the functionally relevant collective vibrations of proteins and other biopolymers are expected to occur at terahertz frequencies. Precise absorption measurements combined with careful titration of biopolymers in water have allowed us to directly measure the terahertz absorption spectra associated with these motions, despite the strong background absorption of the solvent. We have also explored the circular dichroism spectroscopy of biomolecules over this same frequency range. Since circular dichroism requires the presence of net chirality in a molecule and chirality is present in nearly all biomaterial, it has the potential to capture the background free spectral features in biopolymers. To undertake these studies we have developed a broad band terahertz spectrometer suitable for both direct absorption and circular dichroism measurements of proteins in water between 0.75 – 3.72 THz. Direct terahertz absorption spectra of prototypical proteins bovine serum albumin (BSA) and hen egg white lysozyme have been documented and are described here. We have also successfully demonstrated the magnetic circular dichroism in semiconductors, and placed an upper bound on the terahertz circular dichroism signature of solvated BSA. In the terahertz frequency range, it appears that circular dichroism signatures are exceedingly small and detection remains a challenge.

scholarly journals Monitoring the Effect of Transdermal Drug Delivery Patches on the Skin Using Terahertz Sensing

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2052
Author(s):  
Hannah Lindley-Hatcher ◽  
Jiarui Wang ◽  
Arturo I. Hernandez-Serrano ◽  
Joseph Hardwicke ◽  
Gabit Nurumbetov ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Water Content ◽  
Biomedical Applications ◽  
Skin Barrier ◽  
High Sensitivity ◽  
Thz Spectroscopy ◽  
Transdermal Patches ◽  
Patch Removal ◽  
Terahertz Sensing

Water content of the skin is an important parameter for controlling the penetration rate of chemicals through the skin barrier; therefore, for transdermal patches designed for drug delivery to be successful, the effects of the patches on the water content of the skin must be understood. Terahertz (THz) spectroscopy is a technique which is being increasingly investigated for biomedical applications due to its high sensitivity to water content and non-ionizing nature. In this study, we used THz measurements of the skin (in vivo) to observe the effect of partially and fully occlusive skin patches on the THz response of the skin after the patches had been applied for 24 h. We were able to observe an increase in the water content of the skin following the application of the patches and to identify that the skin remained hyper-hydrated for four hours after the removal of the fully occlusive patches. Herein, we show that THz spectroscopy has potential for increasing the understanding of how transdermal patches affect the skin, how long the skin takes to recover following patch removal, and what implications these factors might have for how transdermal drug patches are designed and used.

THz Spectroscopy of Food, Industrial and Pharmaceutical Paraffin Wax

2014 ◽  
Vol 602-605 ◽  
pp. 2675-2679
Author(s):  
Xu Sheng Kang ◽  
Ping Jie Huang ◽  
Xian Li ◽  
Di Bo Hou ◽  
Jin Hui Cai ◽  
...  
Keyword(s):  
Paraffin Wax ◽  
Thz Spectroscopy ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Waves ◽  
Terahertz Time Domain Spectroscopy ◽  
Experimental Conditions ◽  
Food Grade ◽  
Industrial Grade ◽  
Different Types

The absorption coefficient spectra and refractive index spectra of food grade, industrial grade and pharmaceutical grade paraffin wax, the three different types of paraffin wax within the terahertz frequency range from 0.2 to 2.2 THz are measured using transmission-type terahertz time-domain spectroscopy. The average refractive indexes of food grade, industrial grade and pharmaceutical grade paraffin wax in the frequency range are respectively 1.50, 1.49 and1.46. The three different types of paraffin wax all have weak absorption for terahertz waves and each paraffin wax have several obvious absorption peaks. However, all found absorption peak positions of the three different types of paraffin wax are so close that the three are relatively difficult to be identified using transmission-type terahertz technique in present experimental conditions.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

A modified dielectric probe for increased measurement volume of soil water content

2020 ◽  
Author(s):  
Aleksandra Woszczyk ◽  
Justyna Szerement ◽  
Arkadiusz Lewandowski ◽  
Marcin Kafarski ◽  
Agnieszka Szypłowska ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Water Content ◽  
Electromagnetic Waves ◽  
Mechanical Damage ◽  
Direct Methods ◽  
Soil Disturbance ◽  
Sample Volume ◽  
Time Domain Reflectometry ◽  
Frequency Range ◽  
Probe Calibration

<p>The information of water amount in soil is essential in many fields (e.g. agriculture, forestry, hydrology). Methods to determine water content (WC) can be classified as direct and indirect. Direct methods are connected with the destruction of a sample, are time-consuming and impractical for the measurements in the crop fields. Indirect methods ensure non-destructive and in situ measurements and depend on monitoring a dielectric soil property which is a function of WC. The soil dielectric permittivity is one of the used properties which may be determined by time domain reflectometry (TDR) or frequency domain reflectometry (FDR) techniques. TDR probes are expensive and can be easily damaged at multiple insertions to soil. The open-ended (OE) probes, well-known for their application in the measurements of the complex dielectric permittivity of materials in broadband frequency range, are more resistant to mechanical damage but they are characterized by low penetration depth of electromagnetic waves. Therefore, there is a need to develop sensors able to measure bigger volumes and at the same time sufficiently durable for multiple insertions in soil.     </p><p>The objective of this work was to test the performance of an open-ended dielectric probe with an antenna (OE-A) in the frequency range 1 MHz – 6 GHz for two mineral soils using vector network analyzer (VNA) one port (reflective) measurements. Firstly, numerical simulations of the probe using Ansys HFSS software were performed. Secondly, the probe calibration was done on the reference materials (air, distilled water and ethanol). Thirdly, the soils measurements were done to check the possibility to determine soil moisture.   </p><p>The obtained results show that the tested probe can be applied for fast moisture measurement with minimal soil disturbance. The real part of dielectric permittivity (ε’) obtained for the tested soils was connected with their moisture and the relation between ε’ and volumetric water content was determined. Additionally, the effect of the sample volume was considered and the relation between the high-frequency limit and diameter of the sample was determined.     </p><p>Acknowledgement:</p><p>This research was supported by the National Centre for Research and Development (BIOSTRATEG/343547/8/NCBR/2017).</p>

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