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A novel gourd-type photoacoustic cell (GTPAC) has been developed, featuring a highly reflective, polished gold film-coated inner wall that minimizes optical loss and maximizes light utilization efficiency. GTPAC integrates two coupled spherical chambers with a radius ratio 2:3, which is close to the golden ratio. Its unique Gaussian curvature distribution enables multi-directional, disordered light beam reflection without complex optical alignment. It creates a non-periodic three-dimensional (3D) optical trajectory, significantly enhancing light-molecule interactions. GTPAC achieves an exceptionally high sensitivity of up to 3.36 μV/ppm using a distributed feedback butterfly laser with central wavelength of 1532 nm (±1.5 nm) to detect acetylene gas. When the integration time is extended to 100 s, the minimum detection limit is as low as 0.59 ppb. Moreover, its flexible design and broad spectral compatibility enable significant potential for extension to other gases, such as methane and nitrogen oxides, offering new prospects for ultra-sensitive trace gas detection.
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http://dx.doi.org/10.1016/j.pacs.2025.100762 | DOI Listing |
J Phys Condens Matter
September 2025
Department of Physics, Tuskegee University, 1200 West Montgomery Road, 106 Chappie James, Tuskegee, Alabama, 36088-1920, UNITED STATES.
Spin qubit defects in two-dimensional materials have a number of advantages over those in three-dimensional hosts including simpler technologies for the defect creation and control, as well as qubit accessibility. In this work, we select the VBCB defect in the hexagonal boron nitride (hBN) as a possible optically controllable spin qubit and explain its triplet ground state and neutrality. In this defect a boron vacancy is combined with a carbon dopant substituting the closest boron atom to the vacancy.
View Article and Find Full Text PDFPhotoacoustics
October 2025
Hubei Key Laboratory of Intelligent Wireless Communications, Hubei Engineering Research Center of Intelligent IOT technology, College of Electronics and Information Engineering, South-Central Minzu University, Wuhan 430074, China.
A novel gourd-type photoacoustic cell (GTPAC) has been developed, featuring a highly reflective, polished gold film-coated inner wall that minimizes optical loss and maximizes light utilization efficiency. GTPAC integrates two coupled spherical chambers with a radius ratio 2:3, which is close to the golden ratio. Its unique Gaussian curvature distribution enables multi-directional, disordered light beam reflection without complex optical alignment.
View Article and Find Full Text PDFTransl Vis Sci Technol
September 2025
Department of Ophthalmology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA.
Purpose: To evaluate choroidal vasculature using a novel three-dimensional algorithm in fellow eyes of patients with unilateral chronic central serous chorioretinopathy (cCSC).
Methods: Patients with unilateral cCSC were retrospectively included. Automated choroidal segmentation was conducted using a deep-learning ResUNet model.
ACS Omega
September 2025
Institute of Physics, University of Brasília, Brasília, Federal District 70910-900, Brazil.
The exploration of three-dimensional (3D) carbon allotropes has received increasing attention due to their potential in advanced materials and nanotechnology. Irida-Graphene (IG), a two-dimensional carbon allotrope with a structure consisting of 3-6-8 carbon rings, can be used as a precursor for creating 3D materials with tailored properties. This work presents a comprehensive computational characterization of four novel 3D structures derived from IG, named 3D-IG-α, -β, -γ, and -δ.
View Article and Find Full Text PDFBiomed Eng Lett
September 2025
Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju, South Korea.
Unlabelled: Purpose: Idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is a sleep disorder considered to be a prodromal stage of neurodegeneration disease and is often accompanied by cognitive impairments. The purpose of this study was to investigate spatiotemporal characteristics of abnormal oscillatory cortical activity associated with dysfunction of visuospatial attention in iRBD based on an explainable machine learning approach. Methods: EEGs were recorded from 49 iRBD patients and 49 normal controls while they were performing Posner's cueing task and transformed to cortical current density time-series.
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