Quantum cascade lasers (QCLs) and interband cascade lasers (ICLs) are widely used as light sources in tunable laser absorption spectroscopy because they emit in the mid-infrared region where many strong and characteristic absorption bands are present. In this paper, we compare the performance of these lasers emitting at about 2310.1 cm to determine an optimal light source for detecting isotopic ratios of carbon dioxide (CO). Our results show that the QCL has a higher relative intensity noise of up to 15 dBc/Hz compared to the ICL over the entire measured frequency range. In addition, it has a higher frequency fluctuation. However, the maximum tuning range of the QCL is up to 5.2 cm compared to up to 3.8 cm for the ICL. Both lasers lose more than half of their tuning range when the tuning rate is increased to 10 kHz. When measuring the isotope ratio of CO, an uncertainty in the value of ‰ was achieved with the ICL and of ‰ with the QCL, both at an integration time of 0.2 s. In summary, the QCL is more appropriate for applications that require a larger spectral tuning range, such as the measurement of a complex gas mixture, while the ICL has an excellent signal-to-noise ratio and is therefore better suited for applications that require higher precision.
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http://dx.doi.org/10.1177/00037028241291157 | DOI Listing |
Chemistry
December 2024
University of Pardubice: Univerzita Pardubice, Institute of Organic Chemistry and Technology, CZECHIA.
Differently substituted pyrrole-azo‑benzene molecular photoswitches were prepared in a straightforward synthetic way. Their fundamental properties were investigated by XRD analysis, differential scanning calorimetry, thermogravimetric analysis, cyclic voltammetry, UV‑Vis absorption spectroscopy, Hyper-Rayleigh Scattering, and NMR spectroscopy; the experimental results were further corroborated by DFT calculations. Thermal robustness, the HOMO/LUMO levels, and the absorption properties were altered mostly by substituting the N‑methylpyrrole moiety and further fine-tuned by modifying the benzene substituents.
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December 2024
Department of Electronics, Information and Communication Engineering, Kangwon National University, Samcheok, 25913, Republic of Korea.
Autism spectrum disorder (ASD) is a neurologic disorder considered to cause discrepancies in physical activities, social skills, and cognition. There is no specific medicine for treating this disorder; early intervention is critical to improving brain function. Additionally, the lack of a clinical test for detecting ASD makes diagnosis challenging.
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December 2024
Nuclear, Plasma & Radiological Engineering, University of Illinois Urbana-Champaign, Urbana, USA.
This study introduces a physics-regularized neural network (PRNN) as a computational approach to predict silicon carbide's (SiC) swelling under irradiation, particularly at high temperatures. The PRNN model combines physics-based regularization with neural network methodologies to generalize the behavior of SiC, even in conditions beyond the traditional empirical model's valid range. This approach ensures continuity and accuracy in SiC behavior predictions in extreme environments.
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December 2024
Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California 90089, United States.
Conventional artificial intelligence (AI) systems are facing bottlenecks due to the fundamental mismatches between AI models, which rely on parallel, in-memory, and dynamic computation, and traditional transistors, which have been designed and optimized for sequential logic operations. This calls for the development of novel computing units beyond transistors. Inspired by the high efficiency and adaptability of biological neural networks, computing systems mimicking the capabilities of biological structures are gaining more attention.
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December 2024
Department of Endocrinology, Diabetes Mellitus, Nutrition and Metabolic Disorders, "Carol Davila" University of Medicine and Pharmacy, 050474 Bucharest, Romania.
Background: Insulin pumps coupled with continuous glucose monitoring sensors use algorithms to analyze real-time blood glucose levels. This allows for the suspension of insulin administration before hypoglycemic thresholds are reached or for adaptive tuning in hybrid closed-loop systems. This longitudinal retrospective study aims to analyze real-world glycemic outcomes in a pediatric population transitioning to such devices.
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