Search

Despite the gradual development of students' sedentary habits and associated health problems, only a few studies have extensively and systematically measured campus built environments (CBE) and their impact on street walking activity. This study explores the association between CBEs and pedestrian volume (PV). Comprehensive questionnaires, field audits, and GIS were used to measure the CBE variables and PV of 892 street segments on eight Chinese campuses in Tianjin. We used negative binomial regression models without spatial autocorrelations to investigate the relationship between the CBEs and PV. The findings indicated that campus Walk Score, facility and residential land ratio, campus design qualities, sidewalk conditions, street amenities, and other streetscape features were positively associated with PV. This study presents implications for campus research and planning practices in designing a pedestrian-friendly, sustainable, and healthy campus. [ABSTRACT FROM AUTHOR]

The commonly utilized nitriding steel 38CrMoAl is employed for components subjected to low-impact loads but high wear. In this investigation, 38CrMoAl underwent plasma nitrocarburizing using a hollow cathode plasma source, with variations in gas ratios aimed at process optimization. The findings revealed a noteworthy influence of the NH3 to CO2 ratio on the phase composition and properties of the nitrocarburizing layers. Two distinct surface types were observed: one composed of ɛ-Fe2–3(N, C) and γ'-Fe4N and the other consisting of nitrogen-containing martensite with a small quantity of nitride. The surface comprising iron nitride was formed via downslope diffusion, leading to increased surface hardness through nitride formation. Nitrogen-containing martensite was formed via uphill diffusion due to spinodal decomposition, reinforced by mechanisms including fine-grain strengthening, solid-solution strengthening, secondary hardening during tempering, and the pinning effect of metal nitrides precipitated at the grain boundaries. The spinodal structure exhibited superior properties, with a wear rate of 1.26e − 8 mm3/Nm. Thermodynamic calculations confirmed that nitrogen diffusion facilitated spinodal decomposition by expanding the spinodal gap and reducing system energy. This study successfully overcame the performance constraints associated with such nitrided layers, which holds promise for applications to other nitride materials. [ABSTRACT FROM AUTHOR]

This study focuses on the shale fracture characteristics and their developmental master factors in the southeastern Sichuan Basin, aiming to gain a deeper understanding of the fracture network in shale gas reservoirs and its impact on hydrocarbon exploration. Through geological investigation and core sample analysis of Longmaxi Formation shales within the Dingshan-Dongxi and Songkan formations, the characteristics and main controlling factors of shale fractures were deeply studied by using fracture measurements, chi-square projection method and electron microscopy. The results show that: the inclination of cracks is mainly dominated by high-angle cracks and upright cracks, with the upright cracks of the Silurian system accounting for 57.35%, and the high-angle cracks of the Triassic system accounting for 43.85%. The fracture filler is mainly calcite and pyrite, in which the calcite and the analysis of fracture density shows that the density of Silurian fracture lines is mainly 3-8 lines/m, accounting for 70.5% of the total number; the development of microfractures also plays an important role in shale gas storage and transportation, and there are various types of microfractures, including open and filled seams, which provide an important storage space for shale gas exploration; the degree of development of shale fractures is related to the mineral components, organic carbon content and thickness of the rock formation. The degree of shale fracture development is closely related to the mineral fraction, organic carbon content and formation thickness. Shales with high brittle mineral content and organic carbon content have a higher degree of fracture development, while the greater the thickness of the formation, the lower the fracture density. These findings indicate that the development degree and types of shale fractures vary significantly among different geological periods and tectonic blocks, and that their complexity and diversity have important implications for shale gas storage and transportation. [ABSTRACT FROM AUTHOR]

Objective: Dysphagia is one of the most common complications of acute ischemic stroke, and prediction of dysphagia is crucial for post-stroke treatment. We aimed to identify predictors of dysphagia and swallowing function recovery following ischemic stroke and to investigate dysphagia-associated lesion location. Methods: We prospectively enrolled patients with acute ischemic stroke confirmed on diffusion-weighted imaging. All patients received swallowing evaluation within 48 h after admission. Follow-up oral intake ability was measured on 7 and 30 days after stroke onset. Voxel-based lesion-symptom mapping was performed to determine locations associated with dysphagia. Results: Of 126 patients included in the final analysis, 23 patients (18.3%) were classified as initial dysphagia. The presence of facial palsy (P = 0.008) and larger white matter hyperintensity (WMH) volume (P = 0.003) was associated with initial dysphagia. Initial risk of aspiration assessed by Any2 score (P = 0.001) at baseline was identified as independent predictor for dysphagia at day 7. Patients with higher Any2 score (P < 0.001), aphasia (P = 0.013), and larger WMH volume (P = 0.010) were less likely to have a full swallowing function recovery at 1 month. Acute infarcts in right corona radiata and right superior longitudinal fasciculus were correlated with impaired recovery of swallowing ability at 1 month. Conclusions: Initial risk of aspiration was identified as risk factor for short-term and long-term dysphagia. Aphasia and larger WMH volume were revealed to be significant predictors for swallowing function recovery at 1 month. Right corona radiata was identified as an essential brain area for dysphagia. [ABSTRACT FROM AUTHOR]

Due to inter-frequency clock bias (IFCB), the dual-frequency precise clock products cannot be directly applied to BDS-2 triple-frequency precise point positioning (PPP). In this study, the datasets collected at 195 ground tracking stations for a whole year are employed to investigate the modeling and prediction of BDS-2 IFCB. The modeling periods of IFCB are consistent with orbital repeat periods, namely a week for medium earth orbit (MEO) satellites and a day for geostationary orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites. The harmonic analysis results show that the IFCB of MEO satellites has seven significant periods of (168, 84, 56, 42, 33.6, 28, 12.9) h, while there are six obvious periods of (24, 12, 8, 6, 4.8, 4) h for GEO and IGSO satellites. Two function models composed of a linear term and a harmonic term with seven orders for MEO satellites and six orders for GEO and IGSO satellites are established to describe the IFCB variations, and the model coefficients are fitted by least squares. The IFCB modeling accuracies are 4 mm for MEO satellites and 2 mm for GEO and IGSO satellites. The established model can predict the IFCBs with single-day prediction accuracies of 5.0 and 3.9 mm for GEO and IGSO satellites and single-week prediction accuracies of 5.0 mm for MEO satellites, respectively. After applying these predicted IFCBs to BDS-2 triple-frequency PPP, the positioning accuracies are improved by 14–29%. [ABSTRACT FROM AUTHOR]

High voltage electric pulse (HVEP) was used to perform concrete cracking experiments to demonstrate the feasibility of this technique for cracking hard objects. The results of the study show that HVEP fracturing technology has great potential for application. This article uses a high-speed camera to record the crack expansion process, and analyze the relationship between crack expansion speed and time. The Hilbert–Huang Transform (HHT) is used to analyze the vibration signal generated by the shock waves (SWs). The energy evolution law of SWs is elaborated by the time–frequency characteristics of the vibration. The distribution of the vibration energy is more concentrated between 0 and 100 Hz. The increase of capacitance value will produce stronger vibration peak energy and force. The presence of cracks will cause the vibration energy propagation to be blocked and the energy decay rate to be accelerated. Also, the energy will be shifted in the frequency domain due to the presence of cracks. [ABSTRACT FROM AUTHOR]

GO@S/C composite with a multilayered sandwich structure was prepared by a moderate sol-gel method, which was based on porous acetylene black (C) loading sulfur and insertion into multilayered graphene oxide (GO). When evaluated as a cathode for lithium-sulfur batteries (LSBs), it shows an improved capacity of 1433 mAh/g at 0.1 C and 433 mAh/g at 5 C with almost 100% coulombic efficiency for comparison with pure sulfur electrode. It also effectively hinders the expansion of sulfur, the dissolution of polysulfides, and the shuttle effect due to the adsorption and local confinement of polysulfide by porous C and GO. [ABSTRACT FROM AUTHOR]