17 research outputs found
Single-pixel imaging based on deep learning
Single-pixel imaging can collect images at the wavelengths outside the reach
of conventional focal plane array detectors. However, the limited image quality
and lengthy computational times for iterative reconstruction still impede the
practical application of single-pixel imaging. Recently, deep learning has been
introduced into single-pixel imaging, which has attracted a lot of attention
due to its exceptional reconstruction quality, fast reconstruction speed, and
the potential to complete advanced sensing tasks without reconstructing images.
Here, this advance is discussed and some opinions are offered. Firstly, based
on the fundamental principles of single-pixel imaging and deep learning, the
principles and algorithms of single-pixel imaging based on deep learning are
described and analyzed. Subsequently, the implementation technologies of
single-pixel imaging based on deep learning are reviewed. They are divided into
super-resolution single-pixel imaging, single-pixel imaging through scattering
media, photon-level single-pixel imaging, optical encryption based on
single-pixel imaging, color single-pixel imaging, and image-free sensing
according to diverse application fields. Finally, major challenges and
corresponding feasible approaches are discussed, as well as more possible
applications in the future
Enzymatic properties and inhibition tolerance analysis of key enzymes in β-phenylethanol anabolic pathway of Saccharomyces cerevisiae HJ
Huangjiu is known for its unique aroma, primarily attributed to its high concentration of β-phenylethanol (ranging from 40 to 130 mg/L). Phenylalanine aminotransferase Aro9p and phenylpyruvate decarboxylase Aro10p are key enzymes in the β-phenylethanol synthetic pathway of Saccharomyces cerevisiae HJ. This study examined the enzymatic properties of these two enzymes derived from S. cerevisiae HJ and S288C. After substrate docking, Aro9pHJ (−24.05 kJ/mol) and Aro10pHJ (−14.33 kJ/mol) exhibited lower binding free energies compared to Aro9pS288C (−21.93 kJ/mol) and Aro10pS288C (−12.84 kJ/mol). ARO9 and ARO10 genes were heterologously expressed in E. coli BL21. Aro9p, which was purified via affinity chromatography, showed inhibition by l-phenylalanine (L-PHE), but the reaction rate Vmax(Aro9pHJ: 23.89 μmol·(min∙g)−1) > Aro9pS288C: 21.3 μmol·(min∙g)−1) and inhibition constant Ki values (Aro9pHJ: 0.28 mol L−1>Aro9pS288C 0.26 mol L−1) indicated that Aro9p from S. cerevisiae HJ was more tolerant to substrate stress during Huangjiu fermentation. In the presence of the same substrate phenylpyruvate (PPY), Aro10pHJ exhibited a stronger affinity than Aro10pS288C. Furthermore, Aro9pHJ and Aro10pHJ were slightly more tolerant to the final metabolites β-phenylethanol and ethanol, respectively, compared to those from S288C. The study suggests that the mutations in Aro9pHJ and Aro10pHJ may contribute to the increased β-phenylethanol concentration in Huangjiu. This is the first study investigating enzyme tolerance mechanisms in terms of substrate and product, providing a theoretical basis for the regulation of the β-phenylethanol metabolic pathway
Incoherent phonon population and exciton-exciton annihilation dynamics in monolayer WS2 revealed by time-resolved Resonance Raman scattering
Atomically thin layer transition metal dichalcogenides have been intensively
investigated for their rich optical properties and potential applications in
nano-electronics. In this work, we study the incoherent optical phonon and
exciton population dynamics in monolayer WS2 by time-resolved spontaneous Raman
scattering spectroscopy. Upon excitation of the exciton transition, both the
Stokes and anti-Stokes optical phonon scattering strength exhibit a large
reduction. Based on the detailed balance, the optical phonon population is
retrieved, which shows an instant build-up and a relaxation lifetime of around
4 ps at an exciton density E12 cm-2. The corresponding optical phonon
temperature rises by 25 K, eventually, after some 10s of picoseconds, leading
to a lattice heating by only around 3 K. The exciton relaxation dynamics
extracted from the transient vibrational Raman response shows a strong
excitation density dependence, signaling an important bi-molecular contribution
to the decay. The exciton relaxation rate is found to be (70 ps)-1 and
exciton-exciton annihilation rate 0.1 cm2s-1. These results provide valuable
insight into the thermal dynamics after optical excitation and enhance the
understanding of the fundamental exciton dynamics in two-dimensional transition
metal materials.Comment: 16 pages, 4 figure
Enzyme production potential of penicillium oxalicum m1816 and its application in ferulic acid production
10.3390/foods10112577Foods1011257
Excitonic Transport and Intervalley Scattering Dynamics in Large-Size Exfoliated MoSe2 Monolayer Investigated by Heterodyned Transient Grating Spectroscopy
Exciton intervalley scattering, annihilation, relaxation dynamics, and diffusive transport in monolayer transition metal dichalcogenides are central to the functionality of devices based on them. Here, these properties in a large-size exfoliated high-quality monolayer MoSe2 are addressed directly using heterodyned transient grating spectroscopy at room temperature. While the free exciton population is found to be long-lived (approximate to 230 ps), an extremely fast intervalley scattering (<= 170 fs) is observed, leading to a negligible valley polarization, consistent with steady state photoluminescence measurements and theoretical calculation. The exciton population decay shows an appreciable contribution from the exciton-exciton annihilation, with an annihilation rate of approximate to 0.01 cm(2) s(-1). The annihilation process also leads to a significant distortion of the transient grating evolution. Taking this distortion into account, consistent exciton diffusion constants D approximate to 1.4 cm(2) s(-1) are found by a model simulation in the excitation density range of 10(11)-10(12) cm(-2). The presented results highlight the importance of correctly considering the many-body annihilation processes to obtain a pronounced understanding of the excitonic properties of monolayer transition metal dichalcogenides