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Chemosensors, Volume 12, Issue 9 (September 2024) – 3 articles

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21 pages, 4181 KiB  
Article
Detection of Harmful H2S Concentration Range, Health Classification, and Lifespan Prediction of CH4 Sensor Arrays in Marine Environments
by Kai Zhang, Yongwei Zhang, Jian Wu, Tao Wang, Wenkai Jiang, Min Zeng and Zhi Yang
Chemosensors 2024, 12(9), 172; https://doi.org/10.3390/chemosensors12090172 - 29 Aug 2024
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Abstract
Underwater methane (CH4) detection technology is of great significance to the leakage monitoring and location of marine natural gas transportation pipelines, the exploration of submarine hydrothermal activity, and the monitoring of submarine volcanic activity. In order to improve the safety of [...] Read more.
Underwater methane (CH4) detection technology is of great significance to the leakage monitoring and location of marine natural gas transportation pipelines, the exploration of submarine hydrothermal activity, and the monitoring of submarine volcanic activity. In order to improve the safety of underwater CH4 detection mission, it is necessary to study the effect of hydrogen sulfide (H2S) in leaking CH4 gas on sensor performance and harmful influence, so as to evaluate the health status and life prediction of underwater CH4 sensor arrays. In the process of detecting CH4, the accuracy decreases when H2S is found in the ocean water. In this study, we proposed an explainable sorted-sparse (ESS) transformer model for concentration interval detection under industrial conditions. The time complexity was decreased to O (n logn) using an explainable sorted-sparse block. Additionally, we proposed the Ocean X generative pre-trained transformer (GPT) model to achieve the online monitoring of the health of the sensors. The ESS transformer model was embedded in the Ocean X GPT model. When the program satisfied the special instructions, it would jump between models, and the online-monitoring question-answering session would be completed. The accuracy of the online monitoring of system health is equal to that of the ESS transformer model. This Ocean-X-generated model can provide a lot of expert information about sensor array failures and electronic noses by text and speech alone. This model had an accuracy of 0.99, which was superior to related models, including transformer encoder (0.98) and convolutional neural networks (CNN) + support vector machine (SVM) (0.97). The Ocean X GPT model for offline question-and-answer tasks had a high mean accuracy (0.99), which was superior to the related models, including long short-term memory–auto encoder (LSTM–AE) (0.96) and GPT decoder (0.98). Full article
(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors and Humidity Sensors)
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16 pages, 6134 KiB  
Article
Fiber Optic-Based Portable Sensor for Rapid Evaluation and In Situ Real-Time Sensing of Scale Formation in Geothermal Water
by Takuma Matsuura, Takuya Okazaki, Kazuto Sazawa, Ai Hosoki, Akira Ueda and Hideki Kuramitz
Chemosensors 2024, 12(9), 171; https://doi.org/10.3390/chemosensors12090171 - 25 Aug 2024
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Abstract
The formation of scale in hot springs and geothermal brines can be detected quickly and easily using optical fiber-based scale sensors. This paper describes the development of a portable sensor for the in situ detection of scale in geothermal water. This sensor was [...] Read more.
The formation of scale in hot springs and geothermal brines can be detected quickly and easily using optical fiber-based scale sensors. This paper describes the development of a portable sensor for the in situ detection of scale in geothermal water. This sensor was used to detect the formation of calcium carbonate and silica scale and to assess the effectiveness of their inhibitors. The performance of the sensor was evaluated using calcium carbonate scale. In laboratory experiments using both the newly developed sensor and a conventional nonportable sensor, the strength of the transmitted signal was found to decrease significantly as the amount of scale increased. It was considered that this sensor can accurately evaluate only scale formation without being affected by turbidity. The scale that was deposited on each material (optical fiber core, glass plate, polyvinyl chloride (PVC), and SUS304) was observed using a shape analysis laser microscope. Based on these observations, we concluded that this sensor could be used to predict the amount of scale deposited in real time. In situ evaluation of the sensor was conducted at a blowout carbonated hot spring on Rishiri Island, which is located off the coast of Hokkaido, Japan. The results obtained from experiments using hot spring water showed a similar sensor response within a comparable time range as those obtained from the laboratory experiments. The results of this study thus demonstrate that this novel portable scale sensor is suitable for use in geothermal power plants and investigating effectiveness of inhibiters under different conditions. Full article
(This article belongs to the Section Optical Chemical Sensors)
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9 pages, 2754 KiB  
Communication
Circular Dichroism Reflectance Anisotropy of Chiral Atomically Thin Films
by Ilaria Tomei, Filippo Pierucci, Beatrice Bonanni, Anna Sgarlata, Massimo Fanfoni, Seong-Jun Yang, Cheol-Joo Kim and Claudio Goletti
Chemosensors 2024, 12(9), 170; https://doi.org/10.3390/chemosensors12090170 - 24 Aug 2024
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Abstract
Recently, a technical modification of a Reflectance Anisotropy Spectroscopy (RAS) spectrometer has been proposed to investigate the circular dichroism (CD) of samples instead of the normally studied linear dichroism. CD-RAS measures the anisotropy of the optical properties of a sample under right-handed and [...] Read more.
Recently, a technical modification of a Reflectance Anisotropy Spectroscopy (RAS) spectrometer has been proposed to investigate the circular dichroism (CD) of samples instead of the normally studied linear dichroism. CD-RAS measures the anisotropy of the optical properties of a sample under right-handed and left-handed circularly polarized light. Here, we present the application of CD-RAS to measure the circular dichroism of a twisted bilayer of graphene, purposely prepared as a possible substrate for the adsorption of thin molecular layers, in air, in liquid or in a vacuum. This result demonstrates the performance of the apparatus and shows interesting perspectives for the investigation of chiral organic assemblies deposited in solid film. Full article
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