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  • MDPI AG  (7)
  • 1
    Online Resource
    Online Resource
    Artificial Light-at-Night Exposure and Overweight and Obesity across GDP Levels among Chinese Children and Adolescents
    MDPI AG ; 2023
    In:  Nutrients Vol. 15, No. 4 ( 2023-02-13), p. 939-
    Details
    In: Nutrients, MDPI AG, Vol. 15, No. 4 ( 2023-02-13), p. 939-
    Abstract: Background: Evidence in adults suggests that exposure to artificial light-at-night (ALAN) leads to obesity. However, little is known about whether this effect exists in children and adolescents. We aimed to investigate whether ALAN exposure was associated with overweight and obesity in school-aged children and adolescents and whether this association varied with socioeconomic status. Methods: Data on the height and weight of 129,500 children and adolescents aged 10–18 years from 72 cities were extracted from the 2014 Chinese National Survey on Students’ Constitution and Health (CNSSCH). The ALAN area percentage and average ALAN intensity were calculated using the Visible/Infrared Imager/Radiometer Suite. The subjects were separated into three categories based on the cities’ gross domestic product per capita (GDPPC). A mixed-effect logistic regression model and generalized additive model (GAM) were utilized to evaluate the association between ALAN exposure and overweight and obesity in children and adolescents stratified by municipal GDPPC. Results: Both ALAN area (OR = 1.194, 95% CI: 1.175–1.212) and ALAN intensity (OR = 1.019, 95% CI: 1.017–1.020) were positively associated with overweight and obesity in children and adolescents, and the associations remained robust after adjusting for covariates. ORs for overweight and obesity and ALAN area decreased as GDPPC level increased (first tertile: OR = 1.457, 95% CI: 1.335–1.590; second tertile: OR = 1.350, 95% CI: 1.245–1.464; third tertile: OR = 1.100, 95% CI: 1.081–1.119). Similar results were observed for ALAN intensity. In the GAM models, thresholds existed in almost all these spline trends, indicating that ALAN might have a nonlinear association with overweight and obesity. Conclusions: ALAN contributed to the development of overweight and obesity in children and adolescents and this effect differed with GDPPC. Future longitudinal studies should confirm the causal relationship between ALAN and obesity. Moreover, reducing unnecessary exposure to artificial light at night may have beneficial implications for controlling childhood and adolescent obesity, particularly in low-income areas.
    Type of Medium: Online Resource
    ISSN: 2072-6643
    URL: Article
    DOI: 10.3390/nu15040939
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2518386-2
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  • 2
    Online Resource
    Online Resource
    Experimental Study on the Evolution Law of the Mechanical and Pore Characteristic Parameters of Set Cement under High- and Ultra-High-Temperature Treatments
    MDPI AG ; 2024
    In:  Buildings Vol. 14, No. 1 ( 2024-01-22), p. 303-
    Details
    In: Buildings, MDPI AG, Vol. 14, No. 1 ( 2024-01-22), p. 303-
    Abstract: Cement has been widely used as a structural material in many underground projects, and these projects often face high- or ultra-high-temperature environments, leading to the deterioration of the mechanical, porosity, and permeability properties of set cement, thereby increasing the risk of instability of underground structures. In response to this, two new temperature-resistant cement slurry systems were designed. Experiments were conducted on the changes in porosity and permeability of set cement after thermal treatment using low-field nuclear magnetic resonance technology (NMR), visual studies of pore and crack development were carried out using the argon-ion polishing field emission scanning electron microscopy (FE-SEM) and computed tomography (CT) methods. The research results show that as the thermal treatment temperature continued to rise, the compressive strength first increased (25 °C–200 °C) and then decreased (200 °C–600 °C). The porosity of the set cement first decreased (25 °C–115 °C) and then increased (115 °C–600 °C), and the penetration first slowly increased (25 °C–400 °C) and then rapidly increased (400 °C–600 °C). Visualization experiments were conducted on micro-cracks and the pore distribution of the set cement under high- and ultra-high-temperatures, which proved the evolution law of these characteristic parameters. The research results have vital reference significance for the protection of the structural stability of cement components when encountering high-temperature environments.
    Type of Medium: Online Resource
    ISSN: 2075-5309
    URL: Article
    DOI: 10.3390/buildings14010303
    Language: English
    Publisher: MDPI AG
    Publication Date: 2024
    detail.hit.zdb_id: 2661539-3
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  • 3
    Online Resource
    Online Resource
    L2 Motivational Self System, International Posture and the Sustainable Development of L2 Proficiency in the COVID-19 Era: A Case of English Majors in China
    MDPI AG ; 2022
    In:  Sustainability Vol. 14, No. 13 ( 2022-07-01), p. 8087-
    Details
    In: Sustainability, MDPI AG, Vol. 14, No. 13 ( 2022-07-01), p. 8087-
    Abstract: The L2 motivation self system (L2MSS) has been extensively researched in a variety of contexts, but few studies have delved into its relationship with international posture and the sustainable development of L2 proficiency in the COVID-19 era. To address this issue, we surveyed 156 English majors in China and analyzed their response data with structural equation modelling. The results show that the ideal L2 self positively predicts the L2 learning experience, while the ought-to L2 self has a negative predictive power. The international posture exerts a positive influence on the ideal L2 self and L2 experience, and a negative insignificant influence on the ought-to L2 self. The L2 experience and ideal L2 self have a positive influence on L2 proficiency, while the ought-to L2 self has a negative influence. Our results not only contribute to the generalizability of L2MSS but also deepen the understanding of possible contextual variations of L2 motivation, as well as the uniqueness in the sustainable development of English majors in China during the COVID-19 pandemic.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su14138087
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2518383-7
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  • 4
    Online Resource
    Online Resource
    Broadband Spin-Dependent Directional Coupler via Single Optimized Metallic Catenary Antenna
    MDPI AG ; 2021
    In:  Materials Vol. 14, No. 2 ( 2021-01-10), p. 326-
    Details
    In: Materials, MDPI AG, Vol. 14, No. 2 ( 2021-01-10), p. 326-
    Abstract: With the rapid development of on-chip optics, integrated optical devices with better performance are desirable. Waveguide couplers are the typical integrated optical devices, allowing for the fast transmission and conversion of optical signals in a broad working band. However, traditional waveguide couplers are limited by the narrow operation band to couple the spatial light into the chip and the fixed unidirectional transmission of light flow. Furthermore, most of the couplers only realize unidirectional transmission under the illumination of the linear polarized light. In this work, a broadband polarization directional coupler based on a metallic catenary antenna integrated on a silicon-on-insulator (SOI) waveguide has been designed and demonstrated under the illumination of the circularly polarized light. By applying the genetic algorithm to optimize the multiple widths of the metallic catenary antenna, the numerical simulation results show that the extinction ratio of the coupler can be maintained larger than 18 dB in a wide operation band of 300 nm (from 1400 to 1700 nm). Moreover, the coupler can couple the spatial beam into the plane and transmit in the opposite direction by modulating the rotation direction of the incident light. The broadband polarization directional coupler might have great potential in integrated optoelectronic devices and on-chip optical devices.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma14020326
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2487261-1
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  • 5
    Online Resource
    Online Resource
    Case Study: Impacts of Air-Conditioner Air Supply Strategy on Thermal Environment and Energy Consumption in Offices Using BES–CFD Co-Simulation
    MDPI AG ; 2023
    In:  Sensors Vol. 23, No. 13 ( 2023-06-27), p. 5958-
    Details
    In: Sensors, MDPI AG, Vol. 23, No. 13 ( 2023-06-27), p. 5958-
    Abstract: Due to energy constraints and people’s increasing requirements for indoor thermal comfort, improving energy efficiency while ensuring thermal comfort has become the focus of research in the design and operation of HVAC systems. This study took office rooms with few people occupying them in Wuhan as the research object. The EnergyPlus-Fluent co-simulation method was used to study the impact of 12 forms of air distribution on the thermal environment and air-conditioner energy consumption. The results indicate that 3 m/s supply air velocity and 45° supply air angle are more suitable for the case model in this study. The EnergyPlus-Fluent co-simulation method used in this paper provides a reference for the study of indoor environments in offices with few people occupying them.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s23135958
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2052857-7
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  • 6
    Online Resource
    Online Resource
    Dynamic Calibration Method of Sensor Drift Fault in HVAC System Based on Bayesian Inference
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 14 ( 2022-07-18), p. 5348-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 14 ( 2022-07-18), p. 5348-
    Abstract: Sensor drift fault calibration is essential to maintain the operation of heating, ventilation and air conditioning systems (HVAC) in buildings. Bayesian inference (BI) is becoming more and more popular as a commonly used sensor fault calibration method. However, this method focused mainly on sensor bias fault, and it could be difficult to calibrate drift fault that changes with time. Therefore, a dynamic calibration method for sensor drift fault of HVAC systems based on BI is developed. Taking the drift fault calibration of the chilled water supply temperature sensor of the chiller as an example, the performance of the proposed dynamic calibration method is evaluated. Results show that the combination of the Exponentially Weighted Moving-Average (EWMA) method with high detection accuracy and the proposed BI dynamic calibration method can effectively improve the calibration accuracy of drift fault, and the Mean Absolute Percentage Error (MAPE) value between the calibrated and normal data is less than 5%.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22145348
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 7
    Online Resource
    Online Resource
    Anisotropic PDMS/Alumina/Carbon Fiber Composites with a High Thermal Conductivity and an Electromagnetic Interference Shielding Performance
    MDPI AG ; 2022
    In:  Materials Vol. 15, No. 22 ( 2022-11-15), p. 8078-
    Details
    In: Materials, MDPI AG, Vol. 15, No. 22 ( 2022-11-15), p. 8078-
    Abstract: The development of polymer-based composites with a high thermal conductivity and electromagnetic interference (EMI) shielding performance is crucial to the application of polymer-based composites in electronic equipment. Herein, a novel strategy combining ice-templated assembly and stress-induced orientation was proposed to prepare polydimethylsiloxane (PDMS)/alumina/carbon fiber (CF) composites. CF in the composites exhibited a highly oriented structure in the horizontal direction. Alumina was connected to the CF, promoting the formation of thermal conductive pathways in both the horizontal and vertical directions. As the CF content was 27.5 vol% and the alumina content was 14.0 vol%, the PDMS/alumina/CF composite had high thermal conductivities in the horizontal and vertical directions, which were 8.44 and 2.34 W/(m·K), respectively. The thermal conductivity in the horizontal direction was 40.2 times higher than that of PDMS and 5.0 times higher than that of the composite with a randomly distributed filler. The significant enhancement of the thermal conductivity was attributed to the oriented structure of the CF and the bridging effect of alumina. The PDMS/alumina/CF composite exhibited an excellent EMI shielding effectiveness of 40.8 dB which was 2.4 times higher than that of the composite with a randomly distributed filler. The PDMS/alumina/CF composite also exhibited a low reflectivity of the electromagnetic waves. This work could provide a guide for the research of polymer-based composites with a high thermal conductivity and an EMI shielding performance.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma15228078
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2487261-1
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