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The management of radiant exposure to ultraviolet (UV) radiation, especially in the wavelength range from 100 nm to 280 nm (i.e. UV-C), is important for virus inactivation or photobiological safety. Recently, many commercial UV radiometers have been used to measure UV-C irradiance for industrial and public applications. The accuracy of the four types of commercial UV radiometers was investigated by comparing the reference irradiance values obtained from the spectral irradiance standard. It was found that the displayed values of the UV radiometers have discrepancies, such that the measured value can be more than twice the actual value in a certain case. The spectral mismatch between the calibration and test sources is a major factor in the discrepancies in the UV-C measurements. With spectral mismatch correction, most corrected values show a tendency to improve the result to approaching the reference values within 20%. Users need to provide spectral information about the source and radiometer used for UV-C measurement.
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http://dx.doi.org/10.1111/php.13765 | DOI Listing |
ACS Omega
September 2025
Materials and Manufacturing Directorate, AFRL/RXEE, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States.
This study addresses a critical limitation in direct bonded copper (DBC) materials used in power electronics by introducing a copper-zirconium (Cu/Zr) alloy interposing layer at the copper-ceramic interface. This novel design aims to mitigate mechanical stress induced by mismatched material properties, such as the coefficient of thermal expansion (CTE) and elastic modulus, during thermal cycling. The key findings of this study are (1) thermal fatigue improvement: Test samples with the Cu/Zr interface layer (Cu-Cu/Zr-AlN) three times enhanced thermal fatigue resistance, surviving 30 thermal cycles from -55 to 300 °C before delamination, while standard DBC substrates without the Cu/Zr layer failed after just 10 cycles, indicating a performance improvement with the Cu/Zr alloy, (2) durability projections: Based on the Coffin-Manson model, if the upper temperature is capped at 150 °C, the Cu-Cu/Zr-AlN substrates are projected to survive approximately 1372 cycles, underscoring their potential for long-term reliability, and (3) stress mitigation: The Cu/Zr alloy layer bridges the CTE disparity between copper and ceramic, reducing mechanical stress and improving structural integrity across a broad temperature range (-55 to 300 °C).
View Article and Find Full Text PDFACS Appl Mater Interfaces
September 2025
Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
The development of high-performance wearable haptic actuators remains challenging for immersive virtual reality (VR) applications due to limitations in voltage efficiency, low-voltage operation, and tactile fidelity. This work presents conformal elastic electret actuators composed of silica and poly(dimethylsiloxane) (PDMS) nanocomposites and liquid-metal (LM) electrodes, which overcome limitations in skin-device mechanical mismatch and energy efficiency. Through parametric polarization optimization under coupled thermal-electric fields (4 MV/m, 180 °C), the actuators demonstrate low threshold voltage (38.
View Article and Find Full Text PDFPolymers (Basel)
August 2025
School of Semiconductor∙Display Technology, Hallym University, Chuncheon 24252, Republic of Korea.
Organic photodetectors (OPDs) offer considerable promise for low-power, solution-processable biosensing and imaging applications; however, their performance remains limited by spectral mismatch and interfacial trap states. In this study, a highly sensitive polymer photodiode was developed via trace incorporation (0.8 wt%) of InP/ZnSe/ZnS quantum dots (QDs) into a PTB7-Th:PCBM bulk heterojunction (BHJ) matrix.
View Article and Find Full Text PDFIEEE Trans Signal Inf Process Netw
May 2025
Halıcıoğlu Data Science Institute and the Neurosciences Graduate Program, UC San Diego, CA 92093 USA.
Graph signal processing (GSP) is a prominent framework for analyzing signals on non-Euclidean domains. The graph Fourier transform (GFT) uses the combinatorial graph Laplacian matrix to reveal the spectral decomposition of signals in the graph frequency domain. However, a common challenge in applying GSP methods is that in many scenarios the underlying graph of a system is unknown.
View Article and Find Full Text PDFJ Sleep Res
August 2025
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
Understanding the detection of salient auditory stimuli by the deep layer of the superior colliculus (dSC) during REM and NREM sleep offers valuable insights into the neurophysiological mechanisms of state-dependent auditory information processing. We recorded local field potentials (LFP) from dSC, electrocorticogram (ECoG) from frontal/parietal cortical regions, and neck electromyogram (EMG) in freely moving rats during sleep and awake states under oddball paradigm auditory stimulations. Our analysis focused on mismatch negativity (MMN) responses and event-related spectral perturbation (ERSP) in slow gamma (30-60 Hz) activity (SGA) and medium gamma (60-95 Hz) activity (MGA) frequency bands in wakefulness, REM and NREM sleep using three different intensities (35-, 55-, 80-dB) of stimulation.
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