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  • MDPI AG  (34)
  • 1
    In: Polymers, MDPI AG, Vol. 10, No. 10 ( 2018-10-22), p. 1175-
    Abstract: A hyper-branched sulfonated polyimide (s-PI) was synthesized successfully and composited with polyvinylidene fluoride (PVDF) to achieve ultra-high methanol-permeation resistive for direct methanol fuel cell application. The optimized s-PI-PVDF composite membrane exhibited methanol resistivity low to 1.80 × 10−8 cm2/s, two orders of magnitude lower than the value of the commercial Nafion 117 membrane (60 × 10−7 cm2/s). At the same time, the tensile strength of the composite membrane is 22 MPa, which is comparable to the value of the Nafion 117 membrane. Therefore, the composite membrane is promising for application in direct methanol fuel cell.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2527146-5
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  • 2
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 20 ( 2022-10-13), p. 7777-
    In: Sensors, MDPI AG, Vol. 22, No. 20 ( 2022-10-13), p. 7777-
    Abstract: Soil organic matter (SOM) is an important source of nutrients required during crop growth and is an important component of cultivated soil. In this paper, we studied the possibility of using deep learning methods to establish a multi-feature model to predict SOM content. Moreover, using Nong’an County of Changchun City as the study area, Sentinel-2A remote sensing images were taken as the data source to construct the dataset by using field sampling and image processing. The LeNet-5 convolutional neural network model was chosen as the deep learning model, which was improved based on the basic model. The evaluation metrics were selected as the root mean square error (RMSE) and the coefficient of determination R2. Through comparison, the R2 of the improved model was found to be higher than that of the linear regression method, Support Vector Machines (SVM) (RMSE = 2.471, R2 = 0.4035), and Random Forest (RF) (RMSE = 2.577, R2 = 0.4913). The result shows that: (1) It is feasible to use the multispectral data extracted from remote sensing images for soil organic matter content inversion based on the deep learning model with a minimum RMSE of 2.979 and with the R2 reaching 0.89. (2) The choice of features has an impact on the prediction of the model to a certain extent. After ranking the importance of features, selecting the appropriate number of features for inversion provides better results than full feature inversion, and the computational speed is improved.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 3
    In: Remote Sensing, MDPI AG, Vol. 6, No. 11 ( 2014-11-19), p. 11494-11517
    Type of Medium: Online Resource
    ISSN: 2072-4292
    Language: English
    Publisher: MDPI AG
    Publication Date: 2014
    detail.hit.zdb_id: 2513863-7
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  • 4
    In: Polymers, MDPI AG, Vol. 12, No. 5 ( 2020-04-26), p. 1000-
    Abstract: Although sulfonic acid (SA)-based proton-exchange membranes (PEMs) dominate fuel cell applications at low temperature, while sulfonation on polymers would strongly decay the mechanical stability limit the applicable at elevated temperatures due to the strong dependence of proton conduction of SA on water. For the purpose of bifunctionally improving mechanical property and high-temperature performance, Nafion membrane, which is a commercial SA-based PEM, is composited with fabricated silica nanofibers with a three-dimensional network structure via electrospinning by considering the excellent water retention capacity of silica. The proton conductivity of the silica nanofiber–Nafion composite membrane at 110 °C is therefore almost doubled compared with that of a pristine Nafion membrane, while the mechanical stability of the composite Nafion membrane is enhanced by 44%. As a result, the fuel cell performance of the silica nanofiber-Nafion composite membrane measured at high temperature and low humidity is improved by 38%.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2527146-5
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  • 5
    In: Polymers, MDPI AG, Vol. 14, No. 9 ( 2022-04-20), p. 1658-
    Abstract: The demands for carbon fiber reinforced composites (CFRCs) are growing in the aviation industry for fuel consumption savings, despite the increasing risk of electromagnetic interference (EMI). In this work, polyacrylonitrile (PAN) sheets were prepared by electrospinning. Carbon nanofiber (CNF) sheets were obtained by the carbonization of PAN sheets. The laminate structures of the CF reinforced bismaleimide (BMI)-based composites were specially designed by introducing two thin CNF sheets in the upper and bottom plies, according to EMI shielding theory. The results showed that the introduction of CNF sheets led to a substantial increase in the EMI shielding effectiveness (SE) by 35.0% compared with CFRCs free of CNF sheets. The dominant EMI shielding mechanism was reflection. Noticeably, the introduction of CNF sheets did not impact the interlaminar shear strength (ILSS) of CFRCs, indicating that the strategy provided in this work was feasible for fabricating CFRCs with a high EMI shielding performance without sacrificing their mechanical properties. Therefore, the satisfactory EMI shielding and ILSS properties, coupled with a high service temperature, made BMI-based composites a promising candidate in some specific fields, such as high-speed aircrafts and missiles.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527146-5
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  • 6
    In: Polymers, MDPI AG, Vol. 9, No. 12 ( 2017-12-14), p. 703-
    Type of Medium: Online Resource
    ISSN: 2073-4360
    Language: English
    Publisher: MDPI AG
    Publication Date: 2017
    detail.hit.zdb_id: 2527146-5
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  • 7
    In: Land, MDPI AG, Vol. 11, No. 5 ( 2022-05-17), p. 742-
    Abstract: Protected areas are critical for biodiversity conservation and ecosystem services. In the last few years, there has been growing recognition of the role of indigenous peoples and local communities in the management of government designated protected areas, and thus their perceptions and adaptability were paid much attention. Drawing on a survey of 487 residents in the Qilian Mountain National Park Pilot of Northwestern China, this study used the adaptive analysis framework to study the adaptability of local residents. The main contribution of this paper is to select a typical social-ecological system to study the adaptability of local residents, and using Elinor Ostrom’s Social-Ecological System framework to analyze the adaptability mechanism. The results show that different types of residents had different adaptability to environmental change. People whose income mainly depends on work salary with a small part of herding have the highest level of adaptability, while people whose income mostly comes from farming with a small part of herding have the lowest level. This result is related to people’s living location, as people living in the core zone and buffer zone of the reserve mainly earned from grazing, and people living in the experimental zone and peripheral zone earned mainly from outside work. Moreover, people living in the core zone and buffer zone are mostly elders and ethnic groups, while people in the experimental zone and buffer zone are Han people. To improve management effectiveness and to avoid conflict between local residents and managers, this paper suggests that more attention should be paid to these who have lived for a long time in the core zone and buffer zone. They are the most vulnerable groups and show low adaptability in almost all domains. For the long run, education quality should be improved to decrease the population in the reserve.
    Type of Medium: Online Resource
    ISSN: 2073-445X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2682955-1
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  • 8
    In: Atmosphere, MDPI AG, Vol. 13, No. 10 ( 2022-09-20), p. 1540-
    Abstract: The transportation sector is a major source of greenhouse gases and air pollutants, and it has a crucial effect on the synergistic reduction of NOx and carbon. In order to find the energy-efficient vehicle technologies with the highest net reduction potential and lowest net reduction cost over the life cycle, this study traced the CO2 and NOx emission streams of 33 energy-efficient technologies, hidden in the supply chain during the production phase, through structural path analysis, and measured the emission reductions during the use phase using the emission factor method. Moreover, we applied structural decomposition analysis to quantify the three main drivers, including emission intensity, industrial structure, and final demand, of changes in CO2 and NOx emissions from 11 transport subsectors during 2012–2018. Results indicate that CO2 emissions of the transport sector more than doubled from 2012 to 2018; however, the influence of NOx was less significant. The final demand of the road subsector was the most significant driver contributing to CO2 emission changes, with an increase of 109.27 Mt. The emission intensity of road transportation caused the greatest mitigation effect on NOx emission changes, with a decrease of 1902 Kt. The findings of the scenario analysis demonstrate that the most efficient action of the pure electric technology for passenger cars reduces 20.92 Mt NOx emissions, and the parallel hybrid technology for heavy trucks offers the greatest cost effectiveness with a net abatement of 2577 Mt CO2 over its life cycle. Consequently, the aggressive development of new energy technology has become a prerequisite strategy to synergistically reduce CO2 and NOx emissions.
    Type of Medium: Online Resource
    ISSN: 2073-4433
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2605928-9
    SSG: 23
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  • 9
    In: Agronomy, MDPI AG, Vol. 13, No. 6 ( 2023-05-28), p. 1486-
    Abstract: Plant growth-promoting rhizobacteria (PGPR) can promote plant growth and induce systemic resistance to biological and abiotic stresses. However, do all PGPR have significant effects in arid environments, and which PGPR have the most optimal effects? This study used a pot experiment to investigate the effects of inoculation with two different PGPR on the physiological and ecological characteristics of walnut (Juglans regia) seedlings under drought stress: Bacillus subtilis GE1, which secretes protease only, and Pseudomonas brassicacearum X123, which secretes protease and indoleacetic acid (IAA). The leaves inoculated with X123 under drought stress had higher net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs), especially stomatal length and stomatal width, compared to GE1 inoculation under drought stress. Moreover, inoculation with X123 significantly increased the leaf superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities by 20.84% and 12.41%, respectively, and the gibberellin (GA) and zeatin (ZT) contents by 72.07% and 19.17%, respectively, whereas the leaf soluble sugar and soluble protein contents significantly decreased compared with GE1 inoculation. These results indicated that the effects of GE1 inoculation on the physiological and ecological characteristics of walnut seedling leaves were significantly weaker in comparison with X123 inoculation as a result of its functional characteristics. The application of different PGPR on the drought tolerance of J. regia showed significant differences. Therefore, the selection of appropriate PGPR is key to achieving positive treatment effects under drought conditions.
    Type of Medium: Online Resource
    ISSN: 2073-4395
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2607043-1
    SSG: 23
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  • 10
    In: Molecules, MDPI AG, Vol. 21, No. 1 ( 2015-12-23), p. 7-
    Type of Medium: Online Resource
    ISSN: 1420-3049
    Language: English
    Publisher: MDPI AG
    Publication Date: 2015
    detail.hit.zdb_id: 2008644-1
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