UCMMT2021, UK-Europe-China International Workshop on Millimeter Waves and Terahertz Technologies 2021, 13 -15 September 2021.

The 14th UK, Europe, China Millimeter Waves and Terahertz Technology Workshop will be held virtually, organised by Lancaster University, UK, on 13-15 September 2021.

UCMMT is a unique forum, where lead scientists, in particular from China, Europe and United Kingdom share their knowledge in the field of millimeter waves and THz sources, devices, systems and applications.

For the first time, nine relevant thematic tracks are proposed to cover the broad field of millimeter waves and THz and offer a topic oriented submission process.

 – Eight extraordinary plenary speakers live.
 – Invited talks from the best submitted papers.
 – Special session THz Communications Beyond 5G
 – Multimedia poster session.

for more information see http://wp.lancs.ac.uk/ucmmt2021/

Terahertz Permittivity of Pressed ZnO and CuO Powder in Polyethylene Pellets: Effect of Porosity

de la Rosa, Jaume Calvo, Alexandre Locquet, Denis Bouscaud, Sophie Berveiller, and David Citrin. "Terahertz permittivity of pressed ZnO and CuO powder in polyethylene pellets: Effect of porosity." IEEE Transactions on Terahertz Science and Technology (2021). 

for full paper see https://ieeexplore.ieee.org/abstract/document/9371419

Abstract:

Terahertz (THz) spectroscopy is used to measure permittivity (100 GHz–2.5 THz) of ZnO and CuO powders with low fill factor pressed into pellets in a polyethylene binder. We show that porosity (air) of such pressed pellets has a large effect on effective pellet permittivity (∼10%) and on the extracted permittivity of the oxide constituent (∼150%). We explore a two-step analysis based on sequential application of different effective medium models, first to account for the air, and subsequently to extract the oxide's dielectric properties. We show that the combination of Vegard's law and the Maxwell-Garnett model is the best combination to account, respectively, for the air and the oxide powders. In this regard, the capacity that this approach has to adapt to each phase's physical characteristics by using multiple EMMs is an advantage. The resulting oxide permittivities are significantly larger than previously reported for such pellets as a consequence of the porosity. We find for the real relative permittivities of CuO and ZnO ∼12.1 and ∼8.9, respectively, in the THz range.

… The analysis revealed that scattering should not be expected and that the oxides are
homogenously distributed in the pellets' volume. THz-TDS measurements were performed
on a TeraView TPS Spectra 3000. Pellets were placed in a sample holder in N2 …

Terahertz time-domain spectroscopy for powder compact porosity and pore shape measurements: An error analysis of the anisotropic bruggeman model

 Anuschek, Moritz, Prince Bawuah, and J. Axel Zeitler. "Terahertz time-domain spectroscopy for powder compact porosity and pore shape measurements: An error analysis of the anisotropic bruggeman model." International journal of pharmaceutics: X 3 (2021): 100079.

for full paper see https://www.sciencedirect.com/science/article/pii/S2590156721000086

Abstract

Terahertz time-domain spectroscopy (THz-TDS) is a novel technique which has been applied for pore structure analysis and porosity measurements. For this, mainly the anisotropic Bruggeman (AB-EMA) model is applied to correlate the effective refractive index (neff) of a tablet and the porosity as well as to evaluate the pore shape based on the depolarisation factor L. This paper investigates possible error sources of the AB-EMA for THz-TDS based tablet analysis. The effect of absorption and tablet anisotropy – changes of pore shape with porosity and density distribution – have been investigated. The results suggest that high tablet absorption has a negligible effect on the accuracy of the AB-EMA. In regards of tablet anisotropy the accuracy of the porosity determination is not impaired significantly. However, density distribution and variations in the pore shape with porosity resulted in an unreliable extraction of the tablet pore shape. As an extension of the AB-EMA a new concept was introduced to convert the model into bounds for L. This new approach was found useful to investigate tablet pore shape but also the applicability of the AB-EMA for an unknown set of data.

Reproducibility of Terahertz Peaks in a Frozen Aqueous Solution of 5-Methylcytidine

 Tao, Yu Heng, Stuart I. Hodgetts, Alan R. Harvey, and Vincent P. Wallace. "Reproducibility of Terahertz Peaks in a Frozen Aqueous Solution of 5-Methylcytidine." Journal of Infrared, Millimeter, and Terahertz Waves 42, no. 5 (2021): 588-606.

for full paper see https://link.springer.com/article/10.1007/s10762-021-00793-8

Abstract

Abnormally high level of methylation in the epigenome is a biomarker for various forms of cancer. It has been reported that a methylated nucleoside, 5-methylcytidine, when dissolved in water and then frozen, has a resonance absorption peak around 1.6 THz, which could allow for the determination of the degree of methylation using terahertz spectroscopy. This study attempts to replicate the experiment and reproduce this observation independently. Samples of ice were measured at 173 K to establish a baseline and frozen solutions of 5-methylcytidine were measured. Normal (physiological) 0.15 M saline, which is known to have a peak at 1.6 THz, was also measured. The use of a Gaussian function to fit a baseline to the broad (0.2 to 2.5 THz) absorption spectra consistently produced a peak residual around 1.6 THz for all three types of samples, with saline having the highest peak followed by ice. The peak for 5-methylcytidine was found to be smaller than that for ice, which contradicts previously published findings and illustrates the strong dependence of the result on the method of baseline fitting.

… the former. Methods. Experimental Design. Terahertz spectra were acquired with
a commercial THz-TDS system, Terapulse 4000 (TeraView Ltd, Cambridge, UK)
using the fibre coupled emitter/detector devices [15]

Discrimination of authenticity of Fritillariae Cirrhosae Bulbus based on terahertz spectroscopy and chemometric analysis

 Du, Hua, Wenli Chen, Yutian Lei, Fengchao Li, Huiming Li, Wei Deng, and Guihua Jiang. "Discrimination of authenticity of Fritillariae Cirrhosae Bulbus based on terahertz spectroscopy and chemometric analysis." Microchemical Journal (2021): 106440.

for full paper see https://www.sciencedirect.com/science/article/abs/pii/S0026265X21005245

Abstract

A rapid, simple and non-destructive analysis methodology for discriminating the authenticity of Fritillariae Cirrhosae Bulbus (FCB) was established based on terahertz spectroscopy and chemometric analysis. 150 authentic FCB and 100 counterfeit FCB samples (Non-FCB) were analyzed. Then, different modeling algorithms including orthogonal projection to latent structure discriminant analysis (OPLS-DA), stepwise linear discriminant analysis (SLDA), support vector machine (SVM), back-propagation neural network (BPNN) and random forest (RF) were applied and were compared to obtain the best classification and model. Meanwhile, variable importance analysis (VIP) and 5 kinds of data pre-treatment technologies were investigated for improving the discriminant ability of the model. The results showed FCB and Non-FCB samples could be successfully discriminated by combining chemometric tools, and the OPLS-DA had the best identification effect than others. Meanwhile, it could be found that the VIP analysis could significantly increase the discriminant ability of the model and the discrimination accuracy of models based on UV-scaling was significantly better than others, which proved VIP was a powerful way to select useful variables and proper data pre-treatment technologies were very important for improving the discriminant effect. In addition, according to the best OPLS-DA model (vip-uv-OPLS-DA), the test samples could be successfully predicted with 100% accuracy, and the validation parameters R2X, R2Y and Q2 were 0.97, 1.0 and 1.0, respectively, which proved the model had powerful discriminant and predictive ability. In conclusion, terahertz spectroscopy combined with chemometric analysis is an effective method for the authenticity of FCB.

… A THz-TDS detection system (TPS TM spectra 3000, Teraview Co., Ltd) that is consisted of a femtosecond laser, a THz emitter and a THz detector, can perform in transmission and normal reflection model in the time domain … 

Optical properties and potential of LB4 for THz wave generation

 Huang, Jingguo, Yang Li, Zhiming Huang, Yanqing Gao, Dmitry Ezhov, Dmitry Lubenko, and Yury Andreev. "Optical properties and potential of LB4 for THz wave generation." In Fourth International Symposium on High Power Laser Science and Engineering (HPLSE 2021), vol. 11849, p. 1184913. International Society for Optics and Photonics, 2021.

for full paper see https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11849/1184913/Optical-properties-and-potential-of-LB4-for-THz-wave-generation/10.1117/12.2599075.short

Influence of Al, Fe, and Cu on the microstructure, diffused reflectance, THz, and dielectric properties for ZnTiO3 nanocrystalline

Bakr, Ahmed M., Ali B. Abou Hammad, Ahmed R. Wassel, Amany M. El Nahrawy, and A. M. Mansour. "Influence of Al, Fe, and Cu on the microstructure, diffused reflectance, THz, and dielectric properties for ZnTiO3 nanocrystalline." International Journal of Materials Engineering Innovation 12, no. 2 (2021): 115-133.

Abstract

Structural, diffused reflectance, THz, and dielectric features of perovskite ZnTiO₃ (doped with 5 mol.% of Al, Cu, and Fe) prepared using the sol-gel and calcined at 800°C have been investigated. The Al, Cu, and Fe can replace the titanium ions and form sols solutions in the ZnTiO₃ phase, and the spectroscopic and dielectric of the ZnTiO₃ peaks changed with the dopant addition. X-ray diffraction patterns elucidate the creation of the ZnTiO₃ rhombohedral phase, while the introduction of Al and Fe within the ZnTiO₃ structure is composed of two phases identified as cubic phase Zn₂TiO₄ structure and TiO₂ besides the rhombohedral of zinc-titanate. The various dopants induce a surface morphology modification observed by SEM. Diffusive reflection for ZnTiO₃ doped Al, Cu, and Fe indicated higher transparent over the wavelength 400 nm which making them a choice as excellent transparent semiconductor oxides for different optoelectronic applications. The electric modulus has the least values nearly reach zero at low frequency denoting that a neglected contribution of electrode polarisation to the total polarisation. THz and dielectric performance of a material is closely related to its composition and microstructure.

Insights into the Control of Drug Release from Complex Immediate Release Formulations

 Dong, Runqiao, James C. DiNunzio, Brian P. Regler, Walter Wasylaschuk, Adam Socia, and J. Axel Zeitler. "Insights into the Control of Drug Release from Complex Immediate Release Formulations." Pharmaceutics 13, no. 7 (2021): 933.

Abstract: 

The kinetics of water transport into tablets, and how it can be controlled by the formulation as well as the tablet microstructure, are of central importance in order to design and control the dissolution and drug release process, especially for immediate release tablets. This research employed terahertz pulsed imaging to measure the process of water penetrating through tablets using a flow cell. Tablets were prepared over a range of porosity between 10% to 20%. The formulations consist of two drugs (MK-8408: ruzasvir as a spray dried intermediate, and MK-3682: uprifosbuvir as a crystalline drug substance) and NaCl (0% to 20%) at varying levels of concentrations as well as other excipients. A power-law model is found to fit the liquid penetration exceptionally well (average R 2 > 0.995). For each formulation, the rate of water penetration, extent of swelling and the USP dissolution rate were compared. A factorial analysis then revealed that the tablet porosity was the dominating factor for both liquid penetration and dissolution. NaCl more significantly influenced liquid penetration due to osmotic driving force as well as gelling suppression, but there appears to be little difference when NaCl loading in the formulation increases from 5% to 10%. The level of spray dried intermediate was observed to further limit the release of API in dissolution.

Terahertz data processing for imaging and spectroscopy of artwork

  Odlyanitskiy, Evgeniy L., Olga A. Smolyanskaya, Sergei Sirro, Jean-Paul Guillet, Vincent Detalle, and Michel Menu. "Terahertz data processing for imaging and spectroscopy of artwork." In Optics for Arts, Architecture, and Archaeology VIII, vol. 11784, p. 117840D. International Society for Optics and Photonics, 2021.

for full paper see https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11784/117840D/Terahertz-data-processing-for-imaging-and-spectroscopy-of-artwork/10.1117/12.2592597.short?SSO=1

Abstract

Terahertz (THz) radiation in the frequency range 0.1 - 10 THz began to be used for the analysis of artwork in 2006. Terahertz images of paintings require computer processing in order to optimize the process of detecting defects and their visualization. In this work, an algorithm for solving this problem is proposed in relation to the terahertz analysis of paintings. A program is written in Python that searches, group and highlight defects in an image. To work with images, the methods of the OpenCV library is used, designed to solve computer vision problems. They are used to binarize images and search the defect contours on them, as well as to isolate defects when visualizing the results. The grouping of defects is carried out by the method of agglomerative hierarchical clustering. Scientific analysis of the materials used in art items allows to determine the period in which they were created, how they were preserved over the centuries and how they were restored. As part of the study, in this work, a 3D-model of the crystal structure of the red pigment was created. For this, the terahertz spectrum of the pigment was modeled by the density functional method. To experimentally study the optical characteristics of the pigment, measurements are carried out on a TeraView-4000 instrument in transmission mode. The pigment is measured in powder and tableted form.

Syntheses of ‘Hemtex’ Simulants of Energetic Materials and Millimetre Wave Characterisation Using the Teraview CW400 Spectrometer: Fundamental Studies for Detection Applications

 Desai, Hemant J., Richard Lacey, Daniel O. Acheampong, Anthony Clark, Philip Dixon, Matthew Hogbin, Robert Hudson, Sam Pollock, Usman Waheed, and Hannah Whitmore. "Syntheses of ‘Hemtex’Simulants of Energetic Materials and Millimetre Wave Characterisation Using the Teraview CW400 Spectrometer: Fundamental Studies for Detection Applications." In Technology Development for Security Practitioners, pp. 181-195. Springer, Cham, 2021.

Abstract

Explosives or energetic materials are hazardous, expensive and difficult to handle safely. As such there is a need for simulant explosive materials in order to conduct work without these issues being present. This chapter describes characterisation of a set of simulant materials with respect to millimetre wave and submillimetre wave threat detection technologies. The properties examined were the real and imaginary parts of the relative permittivity. The simulants are based on a modular approach to design appropriate chemical and physical properties which mimic explosives. Collectively, these materials are referred to as Hemtex and can be tailored to match various requirements. The subset of Hemtex materials used in this study were designed to reflect the properties of Semtex and the results of the characterisation showed promise for use as Semtex substitutes. 

For full paper see https://link.springer.com/chapter/10.1007/978-3-030-69460-9_11

Diagnosis of injection-molded weld lines in ABS thermoplastic by polarized terahertz reflective imaging

Zhai, Min, Esam T. Ahmed Mohamed, Alexandre Locquet, G. Schneider, R. Kalmar, M. Fendler, N. F. Declercq, and D. S. Citrin. "Diagnosis of injection-molded weld lines in ABS thermoplastic by polarized terahertz reflective imaging." NDT & E International (2021): 102497.

for full paper see https://www.sciencedirect.com/science/article/abs/pii/S0963869521000967

Abstract

We carry out a non destructive study of injection-mold weld lines in an acrylonitrile butadiene styrene (ABS) thermoplastic electrical receptacle plate. Terahertz techniques show morphological features at the weld lines and reveal terahertz birefringence properties localized about the welds, indicating frozen-in molecular orientation and stress proximate to the welds. Surface acoustic microscopy corroborates the morphological features at the welds shown by terahertz imaging and also reveals anomalous mechanical properties at the weld lines. These results indicate that THz-based techniques provide non destructive reliability assessment and quality control for injection-molded thermoplastic products.

 

The 9th International Conference on Optical Terahertz Science and Technology (OTST 2022)

The 9th International Conference on Optical Terahertz Science and Technology (OTST 2022) will bring researchers from around the world to present and discuss most recent advances in terahertz (THz) research, ranging from fundamental science to cutting edge developments in THz technology. The conference will be held in the heart of Central Europe, in Budapest, the capital city of Hungary between 24–29 April 2022 (Sunday to Friday). It follows the previous eight conferences held six times in the USA, once in Japan, and once in the UK, Europe. An introductory workshop with tutorials for students and those who are new to the field of THz science and technology will be organised on the first day (24 April 2022).

The conference date has been postponed from the previous year to 2022 because of the worldwide travel restrictions. We do hope that OTST 2022 will give the scientific community a new impulse and the possibility to meet each other in person after a long time.

The Conference Chairs:

József A. Fülöp - University of Pécs and ELI-ALPS, Hungary

János Hebling - University of Pécs, Hungary

Deadlines

• Abstract submission: January 10, 2022
• Abstract acceptance notification: January 31, 2022
• Payment of early-bird registration fee: February 7, 2022
• Payment of normal registration fee: March 31, 2022

see https://www.otst2022.hu/

A Fast and Non-destructive Terahertz Dissolution Assay for Immediate Release Tablets

 Bawuah, Prince, Daniel Markl, Alice Turner, Mike Evans, Alessia Portieri, Daniel Farrell, Ralph Lucas, Andrew Anderson, Daniel J. Goodwin, and J. Axel Zeitler. "A fast and non-destructive terahertz dissolution assay for immediate release tablets." Journal of Pharmaceutical Sciences 110, no. 5 (2021): 2083-2092.

For full paper see https://www.sciencedirect.com/science/article/abs/pii/S0022354920307796

Abstract

There is a clear need for a robust process analytical technology tool that can be used for on-line/in-line prediction of dissolution and disintegration characteristics of pharmaceutical tablets during manufacture. Tablet porosity is a reliable and fundamental critical quality attribute which controls key mass transport mechanisms that govern disintegration and dissolution behavior. A measurement protocol was developed to measure the total porosity of a large number of tablets in transmission without the need for any sample preparation. By using this fast and non-destructive terahertz spectroscopy method it is possible to predict the disintegration and dissolution of drug from a tablet in less than a second per sample without the need of a chemometric model. The validity of the terahertz porosity method was established across a range of immediate release (IR) formulations of ibuprofen and indomethacin tablets of varying geometries as well as with and without debossing. Excellent correlation was observed between the measured terahertz porosity, dissolution characteristics (time to release 50% drug content) and disintegration time for all samples. These promising results and considering the robustness of the terahertz method pave the way for a fully automated at-line/on-line porosity sensor for real time release testing of IR tablets dissolution.

For more information also see https://teraview.com/terasolve/