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  • MDPI AG  (18)
  • 1
    Online Resource
    Online Resource
    Effects of Atmospheric Cold Plasma Treatment on the Storage Quality and Chlorophyll Metabolism of Postharvest Tomato
    MDPI AG ; 2022
    In:  Foods Vol. 11, No. 24 ( 2022-12-17), p. 4088-
    Details
    In: Foods, MDPI AG, Vol. 11, No. 24 ( 2022-12-17), p. 4088-
    Abstract: Atmospheric cold plasma (ACP) is a potential green preservation technology, but its preservation mechanism is still unclear, and the effects of different plasma intensities on postharvest tomatoes are little studied. In this study, the effects of different ACP treatments (0 kV, 40 kV, 60 kV, and 80 kV) on the sensory quality, physiological indexes, key enzyme activities, and gene expression related to the chlorophyll metabolism of postharvest tomatoes were investigated during the storage time. The results showed that compared with the control group, the tomatoes in the plasma treatment group had a higher hardness and total soluble solid (TSS) and titratable acid (TA) contents, a lower respiratory intensity and weight loss rate, a higher brightness, and a lower red transformation rate, especially in the 60 kV treatment group. In addition, chlorophyll degradation, carotenoid accumulation, and chlorophyllase and pheophorbide a mono-oxygenase (PAO) enzyme activities in the postharvest tomatoes were inhibited in the 60 kV treatment group, and the expressions of three key genes related to chlorophyll metabolism, chlorophyll (CLH1), pheophytinase (PPH), and red chlorophyll catabolic reductase (RCCR) were down-regulated. The results of the correlation analysis also confirmed that the enzyme activity and gene expression of the chlorophyll metabolism were regulated by the ACP treatment, aiming to maintain the greenness of postharvest tomatoes.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    URL: Article
    DOI: 10.3390/foods11244088
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704223-6
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  • 2
    Online Resource
    Online Resource
    Variations in the Effects of Landscape Patterns on the Urban Thermal Environment during Rapid Urbanization (1990–2020) in Megacities
    MDPI AG ; 2021
    In:  Remote Sensing Vol. 13, No. 17 ( 2021-08-27), p. 3415-
    Details
    In: Remote Sensing, MDPI AG, Vol. 13, No. 17 ( 2021-08-27), p. 3415-
    Abstract: Deterioration of the urban thermal environment, especially in megacities with intensive populations and high densities of impervious surfaces, is a global issue resulting from rapid urbanization. The effects of landscape patterns on the urban thermal environment within a single area or single period have been well documented. Few studies, however, have explored whether the effects can be adapted to various cities at different urbanization stages. This paper investigated the variations of these effects in the five largest and highly urbanized megacities of China from 1990 to 2020 using various geospatial approaches, including concentric buffer analysis, correlation analysis, and hierarchical ridge regression models. The results indicated that the effects of landscape patterns on the urban thermal environment were greatly variable at different urbanization stages. Although landscape composition was more important than landscape configuration in determining the urban thermal environment, the standard coefficients of composition metrics continuously decreased from 1990 to 2020. However, configuration metrics, such as patch density, edge density, and shape complexity, could affect the land surface temperature (LST) to a larger extent at the highly urbanized stage. The urbanization process could also affect the cooling effect of urban green space. At the initial stage of rapid urban expansion in approximately 2000, urban green space explained the most variation in LST, with a value as high as 10%. To maximize the cooling effect, the spatial arrangement of urban green space should be highlighted in the region that was 10–15 km from the city center, where the mean LST experienced a significant decline. These results may provide deeper insights into improving the urban thermal environment by targeted strategies in optimizing landscape patterns for areas at different urbanization stages.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    URL: Article
    DOI: 10.3390/rs13173415
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2513863-7
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  • 3
    Online Resource
    Online Resource
    Crystal Structure and Microwave Dielectric Property of xMgO-SiO2 (x = 1~2) System for 5G Applications
    MDPI AG ; 2023
    In:  Crystals Vol. 13, No. 9 ( 2023-08-23), p. 1296-
    Details
    In: Crystals, MDPI AG, Vol. 13, No. 9 ( 2023-08-23), p. 1296-
    Abstract: Mg2SiO4 and MgSiO3 ceramics with superior microwave dielectric properties are considered to be promising candidates for 5G applications. However, a slight deviation from the stoichiometric Mg/Si ratio will significantly influence their microwave dielectric properties, which will hinder their practical applications. In this work, the xMgO-SiO2 (x = 1~2) ceramics were synthesized by a solid-state reaction method. The influence of the Mg/Si ratio x on the crystalline phase, microstructure, and microwave dielectric properties was investigated through X-ray diffraction (XRD), a scanning electron microscope (SEM), and the resonant cavity method. The XRD patterns revealed the coexistence of Mg2SiO4 and MgSiO3 within the x range of 1~2, which was further demonstrated by the energy-dispersive X-ray spectra. The SEM images show a typical polycrystalline morphology of ceramics with an inhomogeneous grain size distribution. It is found that the microwave dielectric properties fluctuate at both sides of the x range while those remain relatively stable with minor changes at the intermediate components, indicating an obvious low composition dependence helpful for practical applications. Further, a demonstrator of a microstrip patch antenna for 5G applications using the 1.5MgO-SiO2 ceramic was designed and fabricated, and a return loss of −16.2 dB was demonstrated, which demonstrated the potential applications.
    Type of Medium: Online Resource
    ISSN: 2073-4352
    URL: Article
    DOI: 10.3390/cryst13091296
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2661516-2
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  • 4
    Online Resource
    Online Resource
    Spatiotemporal Patterns of Urbanization in the Three Most Developed Urban Agglomerations in China Based on Continuous Nighttime Light Data (2000–2018)
    MDPI AG ; 2021
    In:  Remote Sensing Vol. 13, No. 12 ( 2021-06-08), p. 2245-
    Details
    In: Remote Sensing, MDPI AG, Vol. 13, No. 12 ( 2021-06-08), p. 2245-
    Abstract: Urban agglomeration is an advanced spatial form of integrating cities, resulting from the global urbanization of recent decades. Understanding spatiotemporal patterns and evolution is of great importance for improving urban agglomeration management. This study used continuous time-series NTL data from 2000 to 2018 combined with land-use images to investigate the spatiotemporal patterns of urbanization in the three most developed urban agglomerations in China over the past two decades: the Beijing–Tianjin–Hebei urban agglomeration (BTH), the Yangtze River Delta urban agglomeration (YRD), and the Guangdong–Hong Kong–Macao Greater Bay Area (GBA). The NTL intensity indexes, dynamic thresholds, extracted urban areas, and landscape metrics were synthetically used to facilitate the analysis. This study found that the urbanization process in the study areas could be divided into three stages: rapid urbanization in core cities from 2000 to 2010, a fluctuating urbanization process in both core cities and surrounding cities from 2010 to 2015, and stable urbanization, mainly in surrounding cities with a medium size after 2015. Meanwhile, the urbanization level of GBA was higher than that of YRD and BTH. However, with the acceleration of urban development in YRD, the gap in the urbanization level between GBA and YRD narrowed significantly in the third stage. In addition, this study confirmed that the scattered, medium-sized cities in YRD and GBA were more developed than those in BTH. This study showed that continuous NTL data could be effectively applied to monitor the urbanization patterns of urban agglomerations.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    URL: Article
    DOI: 10.3390/rs13122245
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2513863-7
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  • 5
    Online Resource
    Online Resource
    Quantitative Evaluation Method for Construction Disturbance and Ecological Restoration of Waterway Engineering and Its Application
    MDPI AG ; 2023
    In:  Water Vol. 15, No. 3 ( 2023-01-23), p. 460-
    Details
    In: Water, MDPI AG, Vol. 15, No. 3 ( 2023-01-23), p. 460-
    Abstract: With the increasing emphasis on the ecology and environment of rivers, the construction of ecological waterway projects has become a development trend in China. In recent years, more and more attention has been paid to the qualitative and quantitative evaluation of the ecological effects of ecological waterway construction. Based on pressure-state-response (PSR) and driver-pressure-state-impact-response (DPSIR) logical frameworks, this paper established a state-pressure-impact-response (SPIR) conceptual model. The model took the river ecology and environment state as the main line, and described the disturbance pressure of the engineering construction on the river state, the impacts of the project on the river comprehensive function, and the positive responses taken in the full lifetime cycle of the project. The analytic hierarchy process (AHP) and fuzzy evaluation model were used to study the changes of the river ecosystem status after suffering from the construction pressure and taking positive responses. Taking the 12.5 m deep water waterway project in the Taicang-Nantong section of the lower reaches of the Yangtze River as an example, the disturbance on the ecology and environment at different stages of the project construction and the effort of relieving the negative impacts of the project on the ecology and environment were evaluated by the health level of the ecosystem. The paper can provide a scientific method for the evaluation of ecological projects in river ecosystems.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    URL: Article
    DOI: 10.3390/w15030460
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2521238-2
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  • 6
    Online Resource
    Online Resource
    Considerations for the Variable Density Lattice Structure of Additive Manufacturing: A Review
    MDPI AG ; 2022
    In:  Sustainability Vol. 14, No. 18 ( 2022-09-11), p. 11404-
    Details
    In: Sustainability, MDPI AG, Vol. 14, No. 18 ( 2022-09-11), p. 11404-
    Abstract: In recent decades, the additive manufacturing technology has made great progress in software and methods in various fields, and gradually explored in a deeper and broader manner. It has changed from the mature homogenized lattice type and model design to a non-uniform direction. It has also started to improve from the aspects of material innovation, additive manufacturing printing technology, etc., to change the additive manufacturing technology and control parameters in the manufacturing process, Furthermore, the model or part can be improved to have better mechanical properties, such as stiffness, strength and wear resistance, which provides an important research methodology for the better development of this direction. These aspects include the software used, the type of structural analysis, the software used and verification, as well as the methods applied in the study of variable density lattices and the application and verification of improved research methods. In addition, there are density design optimization, variable density lattice design and lattice geometric characteristics’ design in geometric topology optimization design. The expected design of the model or part at the design level has reached the ideal model or part, which provides both a framework and ideas for the future research direction of non-uniform lattice design and a broader field of application, and will promote the future research and development prospects of variable density lattices.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su141811404
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2518383-7
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  • 7
    Online Resource
    Online Resource
    Long-Term Impacts of COVID-19 Lockdown on the NO2 Concentrations and Urban Thermal Environment: Evidence from the Five Largest Urban Agglomerations in China
    MDPI AG ; 2022
    In:  Remote Sensing Vol. 14, No. 4 ( 2022-02-14), p. 921-
    Details
    In: Remote Sensing, MDPI AG, Vol. 14, No. 4 ( 2022-02-14), p. 921-
    Abstract: Under the threat of COVID-19, many regions around the world implemented lockdown policies to control the spread of the virus. This restriction on both social and economic activities has improved the quality of the environment in certain aspects. However, most previous studies have only focused on the short-term impact of lockdown policies on the urban environment. The long-term effects of lockdown require a more focused exploration and analysis. Thus, five major urban agglomerations in China were selected as the research area; changes in the numerical and spatial distribution of NO2 concentration and surface temperature during four different lockdown stages in 2019, 2020, and 2021 were investigated to analyze the long-term effects of lockdown policies on the urban environment. The results indicated that the impact of shorter lockdowns was short-term and unsustainable; the NO2 concentrations increased again with the resumption of production. Compared with air pollutants, thermal environmental problems are more complex. The effect of the lockdown policy was not reflected in the decrease in the area proportions of the high- and sub-high-temperature regions but rather in the spatial distribution of the high-temperature area, which was manifested as a fragmentation and dispersion of heat source patches. In addition to the severity of the lockdown, the impact of the lockdown policy was also closely related to the level of development and industrial structure of each city. Among the urban environments of the five agglomerations, the most affected were the Yangtze River Delta and Yangtze River Middle-Reach urban agglomerations, which had the largest decline in NO2 concentrations and the most notable fragmentation of heat source patches.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    URL: Article
    DOI: 10.3390/rs14040921
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2513863-7
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  • 8
    Online Resource
    Online Resource
    Insights into Factors Affecting Traffic Accident Severity of Novice and Experienced Drivers: A Machine Learning Approach
    MDPI AG ; 2021
    In:  International Journal of Environmental Research and Public Health Vol. 18, No. 23 ( 2021-12-02), p. 12725-
    Details
    In: International Journal of Environmental Research and Public Health, MDPI AG, Vol. 18, No. 23 ( 2021-12-02), p. 12725-
    Abstract: Traffic accidents have significant financial and social impacts. Reducing the losses caused by traffic accidents has always been one of the most important issues. This paper presents an effort to investigate the factors affecting the accident severity of drivers with different driving experience. Special focus was placed on the combined effect of driving experience and age. Based on our dataset (traffic accidents that occurred between 2005 and 2021 in Shaanxi, China), CatBoost model was applied to deal with categorical feature, and SHAP (Shapley Additive exPlanations) model was used to interpret the output. Results show that accident cause, age, visibility, light condition, season, road alignment, and terrain are the key factors affecting accident severity for both novice and experienced drivers. Age has the opposite impact on fatal accident for novice and experienced drivers. Novice drivers younger than 30 or older than 55 are prone to suffer fatal accident, but for experienced drivers, the risk of fatal accident decreases when they are young and increases when they are old. These findings fill the research gap of the combined effect of driving experience and age on accident severity. Meanwhile, it can provide useful insights for practitioners to improve traffic safety for novice and experienced drivers.
    Type of Medium: Online Resource
    ISSN: 1660-4601
    URL: Article
    DOI: 10.3390/ijerph182312725
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2175195-X
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  • 9
    Online Resource
    Online Resource
    2D/1D V2O5 Nanoplates Anchored Carbon Nanofibers as Efficient Separator Interlayer for Highly Stable Lithium–Sulfur Battery
    MDPI AG ; 2020
    In:  Nanomaterials Vol. 10, No. 4 ( 2020-04-08), p. 705-
    Details
    In: Nanomaterials, MDPI AG, Vol. 10, No. 4 ( 2020-04-08), p. 705-
    Abstract: Quick capacity loss due to the polysulfide shuttle effects is a critical challenge for high-performance lithium–sulfur (Li–S) batteries. Herein, a novel 2D/1D V2O5 nanoplates anchored carbon nanofiber (V-CF) interlayer coated on standard polypropylene (PP) separator is constructed, and a stabilization mechanism derived from a quasi-confined cushion space (QCCS) that can flexibly accommodate the polysulfide utilization is demonstrated. The incorporation of the V-CF interlayer ensures stable electron and ion pathway, and significantly enhanced long-term cycling performances are obtained. A Li–S battery assembled with the V-CF membrane exhibited a high initial capacity of 1140.8 mAh·g−1 and a reversed capacitance of 1110.2 mAh·g−1 after 100 cycles at 0.2 C. A high reversible capacity of 887.2 mAh·g−1 is also maintained after 500 cycles at 1 C, reaching an ultra-low decay rate of 0.0093% per cycle. The excellent electrochemical properties, especially the long-term cycling stability, can offer a promising designer protocol for developing highly stable Li–S batteries by introducing well-designed fine architectures to the separator.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano10040705
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2662255-5
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  • 10
    Online Resource
    Online Resource
    Optimizing Airfoil Aerodynamic Characteristics by Using Proposed CSA-KJ Method
    MDPI AG ; 2023
    In:  Applied Sciences Vol. 13, No. 2 ( 2023-01-09), p. 924-
    Details
    In: Applied Sciences, MDPI AG, Vol. 13, No. 2 ( 2023-01-09), p. 924-
    Abstract: Combined with the cuckoo search algorithm (CSA) and the Kutta–Joukowski (KJ) theorem, a CSA-KJ optimization method was proposed to improve the airfoil aerodynamic characteristics in this work. The fourth-order constant-free polynomial function was employed to describe the airfoil profile. The KJ loop lift of the airfoil was taken as the objective function, and the CSA was applied to iteratively update this method, which was used to optimize the NACA4412 airfoil. The results demonstrate that the optimized effect of the CSA-KJ method on the lift-drag ratio becomes increasingly more significant with the increase of incoming wind speed, and it has the best performance at an angle of attack of 0°. Compared with the NACA4412 airfoil, the average and the maximum lift-drag ratio coefficients of the CSA-KJ4412 airfoil have increased. Meanwhile, the pressure difference distribution is improved, and the aerodynamic characteristic is better. From this, it can be seen that the CSA-KJ method can provide an effective way to optimize the aerodynamic performance of other airfoils.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app13020924
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704225-X
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