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Time-of-flight functional near-infrared spectroscopy (fNIRS) is a promising technology for non-invasive functional neuroimaging due to the capability to monitor absolute blood oxygen information. Moreover, it holds promise in addressing the spatial resolution limitations of continuous-wave fNIRS through the confocal array. However, ToF-fNIRS requires extensive data measurement and transmission, complex channel calibration, as well as high costs. Perhaps more importantly, absolute value is unnecessary in fNIRS. In light of this, a time-gated photon counting is designed to facilitate the acquisition of depth-resolved data in both confocal and offset optode configurations for cost-effective enhancement of functional near-infrared spectroscopy. To demonstrate the capabilities of the developed system, measurement performance analysis and image performance evaluation are conducted on the experimental data. The findings have demonstrated the efficacy and viability of the developed system: achieving a fluctuation level below 0.5%, relative quantitative enhancement of 32.9%, alongside improvements of 31.6% in signal-to-noise ratio, and 29.5% in spatial resolution during reconstruction. In summary, this time-gated photon counting fNIRS imaging system has the imaging quality equivalent to traditional time-correlated single-photon counter measurement in a cost-effective manner, thereby significantly augmenting the expansiveness of fNIRS-linked studies in the daily life. [ABSTRACT FROM AUTHOR]

Edge structures, thiophene adsorption and hydrodesulfurization (HDS) mechanisms are investigated on the S-edge of triangular MoS2 nanoclusters using density functional theory. The calculated formation energies for different S coverages on the S-edge suggest that the formation of coordinative unsaturated site at the vertex and edge-I (close to the vertex) sites is preferred over the edge-II (away from the vertex) sites. The adsorption of thiophene on the top site of Mo atom mainly occurs at the edge-I, whereas bridge adsorption occurs at the edge-II. The 92% and 50% S-edge coverages involve relatively larger adsorption energies (− 0.68 and − 0.79 eV) among all the possible adsorption configurations. On the S edge with 92% S coverage, the hydrogenation route is more favorable, producing 1-butene. On the S edge with 50% S coverage, the direct desulfurization route is preferred, yielding butadiene. These findings deepen the understanding of edge structures of MoS2 nanoclusters and the corresponding HDS mechanisms for MoS2-based HDS catalysts. [ABSTRACT FROM AUTHOR]

Methanol steam reforming (MSR) is studied on a Pt3Sn surface using the density functional theory (DFT). An MSR network is mapped out, including several reaction pathways. The main pathway proposed is CH3OH + OH → CH3O → CH2O → CH2O + OH → CH2OOH → CHOOH → COOH → COOH + OH → CO2 + H2O. The adsorption strengths of CH3OH, CH2O, CHOOH, H2O and CO2 are relatively weak, while other intermediates are strongly adsorbed on Pt3Sn(111). H2O decomposition to OH is the rate-determining step on Pt3Sn(111). The promotion effect of the OH group is remarkable on the conversions of CH3OH, CH2O and trans-COOH. In particular, the activation barriers of the O–H bond cleavage (e.g., CH3OH → CH3O and trans-COOH → CO2) decrease substantially by ~1 eV because of the involvement of OH. Compared with the case of MSR on Pt(111), the generation of OH from H2O decomposition is more competitive on Pt3Sn(111), and the presence of abundant OH facilitates the combination of CO with OH to generate COOH, which accounts for the improved CO tolerance of the PtSn alloy over pure Pt. [ABSTRACT FROM AUTHOR]

Cross-river tunnel as one of the underground constructions is complicated during its construction. For stability of tunnel excavation, it is emergency to analyze the dynamic characteristics of tunnel deformation under high water pressure. Therefore, a cross-river tunnel model is proposed based on DEM in this paper. Stiffness of particles decreases during excavation process which is as one of excavation methods. Porosity ratio of original porosity over its value at different excavation time has been considered. Radial displacements of particles at different angle around the tunnel are detected during excavation process. It shows that large deformation occurs at the vault of the excavation zone which accompanies with large radial displacement. The upper half of the tunnel performs larger deformation than the lower half part which results in many cracks in the concrete lining, the high water pressure may play an crucial role in it.