We demonstrate the frequency stabilization of a terahertz quantum-cascade laser (QCL) to the Lamb dip of the absorption line of a DO rotational transition at 3.3809309 THz. To assess the quality of the frequency stabilization, a Schottky diode harmonic mixer is used to generate a downconverted QCL signal by mixing the laser emission with a multiplied microwave reference signal. This downconverted signal is directly measured by a spectrum analyzer showing a full width at half maximum of 350 kHz, which is eventually limited by high-frequency noise beyond the bandwidth of the stabilization loop.
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http://dx.doi.org/10.1364/OE.483883 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Department of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
Developing damping materials that are both optically transparent and mechanically robust, while offering broad frequency damping capacity, is a significant challenge─particularly for devices that require protection without compromising visual clarity. Conventional methods often either fail to maintain transparency or involve complex designs that are difficult to implement. Here, we present an ionogel system that integrates a physically cross-linked elastic copolymer network with a viscous ionic liquid.
View Article and Find Full Text PDFPLoS One
January 2025
Department of Mathematics, College of Natural and Computational Science, Debre Berhan University, Debre Berhan, Adis Ababa, Ethiopia.
Tuberculosis (TB) is one of the deadly infectious diseases affecting millions of individuals throughout the world. The main objective of this study is to investigate the impact of media coverage on the transmission dynamics of TB with vaccine and treatment strategy using mathematical model analysis. In the qualitative analysis of the proposed model we proved the existence, uniqueness, positivity, and boundedness of the model solutions, investigated both the disease-free and endemic equilibrium points, computed the basic and effective reproduction numbers using next generation matrix approach, analyzed the stability analysis of the equilibrium points, the backward bifurcation using the Castillo-Chavez and Song theorem and we re-formulated the corresponding optimal control problem and analyzed by applying the Pontryagin's Minimum Principle.
View Article and Find Full Text PDFmBio
January 2025
Department of Microbiology, UMass Chan Medical School, Worcester, Massachusetts, USA.
Unlabelled: (Mtb) exhibits an impressive ability to adapt to rapidly changing environments, despite its genome's apparent stability. Recently, phase variation through indel formation in homopolymeric tracts (HT) has emerged as a potentially important mechanism promoting adaptation in Mtb. This study examines the impact of common phase variants associated with the ESX-1 type VII secretion system, focusing on a highly variable HT upstream of the ESX-1 regulatory factor, .
View Article and Find Full Text PDFChemistry
January 2025
The Hong Kong Polytechnic University, Department of Applied Biology and Chemical Technology, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Hom, Hong Kong (P.R. China), 000000, Hong Kong, HONG KONG.
A series of new (donor)₂-donor-π-acceptor (D2-D-π-A) and (acceptor)₂-donor-π-acceptor (A2-D-π-A) organic photosensitizers based on the framework of (Z)-2-cyano-3-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)acrylic acid have been synthesized and characterized. By incorporating groups with different electron-donating or withdrawing abilities, such as dibenzothiophene (DBT), dibenzofuran (DBF), and triazine (TA), into the triphenylamine segment, their photophysical properties have been regulated. Theoretical calculations were used to explore how various donor-acceptor combinations influence their hydrogen production performance.
View Article and Find Full Text PDFGlob Chang Biol
January 2025
Scripps Institution of Oceanography, UC San Diego, La Jolla, California, USA.
High spatial or temporal variability in community composition makes it challenging for natural resource managers to predict ecosystem trajectories at scales relevant to management. This is commonly the case in nearshore marine environments, where the frequency and intensity of disturbance events vary at the sub-kilometer to meter scale, creating a patchwork of successional stages within a single ecosystem. The successional stage of a community impacts its stability, recovery potential, and trajectory over time in predictable ways.
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