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  • MDPI AG  (5,474)
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  • MDPI AG  (5,474)
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  • 1
    In: Electronics, MDPI AG, Vol. 9, No. 8 ( 2020-07-28), p. 1211-
    Abstract: Active phased array antennas (APAAs) can suffer from the effects of harsh thermal environments, which are caused by the large quantity of power generated by densely packed T/R modules and external thermal impacts. The situation may be worse in the case of limited room and severe thermal loads, due to heat radiation and a low temperature sink. The temperature field of the antenna can be changed. Since large numbers of temperature-sensitive electronic components exist in T/R modules, excitation current output can be significantly affected and the electromagnetic performance of APAAs can be seriously degraded. However, due to a lack of quantitative analysis, it is difficult to directly estimate the effect of temperature on the electromagnetic performance of APAAs. Therefore, this study investigated the electromagnetic performance of APAAs as affected by two key factors—the uniformly distributed temperature field and the temperature gradient field—based on different antenna shapes and sizes, to provide theoretical guidance for their thermal design.
    Type of Medium: Online Resource
    ISSN: 2079-9292
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2662127-7
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  • 2
    In: Vaccines, MDPI AG, Vol. 9, No. 12 ( 2021-12-15), p. 1483-
    Abstract: Newcastle disease virus (NDV) and infectious bursal disease virus (IBDV) are the two most important and widespread viruses causing huge economic losses in the global poultry industry. Outbreaks of genotype VII NDV and IBDV variants in vaccinated poultry flocks call for genetically matched vaccines. In the present study, a genetic matched chimeric NDV LaSota vaccine strain expressing VP2 gene of IBDV variant, rLaS-VIIF/HN-VP2 was generated for the first time, in which both the F and HN genes of LaSota were replaced with those of the genotype VII NDV strain FJSW. The cleavage site of the FJSW strain F protein in the rLaS-VIIF/HN-VP2 genome was mutated to the avirulent motif found in LaSota. Expression of IBDV VP2 protein was confirmed by western blot. The rLaS-VIIF/HN-VP2 maintained the efficient replication ability in embryonated eggs, low pathogenicity and genetic stability comparable to that of parental LaSota virus. One dose oculonasal vaccination of one-week-old SPF chickens with rLaS-VIIF/HN-VP2 induced full protection against genotype VII NDV and IBDV lethal challenge. These results indicate that the rLaS-VIIF/HN-VP2 is a promising bivalent vaccine to prevent infections of IBDV and genotype VII NDV.
    Type of Medium: Online Resource
    ISSN: 2076-393X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2703319-3
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  • 3
    In: Molecules, MDPI AG, Vol. 27, No. 13 ( 2022-06-24), p. 4075-
    Abstract: Phytotherapy offers obvious advantages in the intervention of Coronary Artery Disease (CAD), but it is difficult to clarify the working mechanisms of the medicinal materials it uses. DGS is a natural vasoprotective combination that was screened out in our previous research, yet its potential components and mechanisms are unknown. Therefore, in this study, HPLC-MS and network pharmacology were employed to identify the active components and key signaling pathways of DGS. Transgenic zebrafish and HUVECs cell assays were used to evaluate the effectiveness of DGS. A total of 37 potentially active compounds were identified that interacted with 112 potential targets of CAD. Furthermore, PI3K-Akt, MAPK, relaxin, VEGF, and other signal pathways were determined to be the most promising DGS-mediated pathways. NO kit, ELISA, and Western blot results showed that DGS significantly promoted NO and VEGFA secretion via the upregulation of VEGFR2 expression and the phosphorylation of Akt, Erk1/2, and eNOS to cause angiogenesis and vasodilation. The result of dynamics molecular docking indicated that Salvianolic acid C may be a key active component of DGS in the treatment of CAD. In conclusion, this study has shed light on the network molecular mechanism of DGS for the intervention of CAD using a network pharmacology-driven strategy for the first time to aid in the intervention of CAD.
    Type of Medium: Online Resource
    ISSN: 1420-3049
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2008644-1
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  • 4
    In: Agriculture, MDPI AG, Vol. 13, No. 2 ( 2023-01-20), p. 254-
    Abstract: The deep application of liquid fertilizer in paddy fields is a fertilization technique that applies liquid fertilizer deep near the root system of paddy field crops, which can effectively improve the absorption rate of the crops and reduce the amount of fertilizer applied. In the cold regions of China, the soil return rate of the furrowing operation of the deep application of liquid fertilizer in paddy fields is low, which can easily cause the excessive liquid leakage of fertilizer and affect crop growth. Therefore, it is difficult to popularize in large areas. According to the characteristics of paddy soil in the cold regions of China and the operating requirements of a high backfill rate and low disturbance rate of the soil of the deep application of liquid fertilizer, this paper designed a bionic liquid fertilizer deep application furrow opener based on the claw-toe structure of the muskrat. In this study, an indoor soil bin test was conducted by constructing a deep application environment for the liquid fertilizer in paddy fields. The results of the soil bin test showed the effects of the key operating parameters of the bionic design of the liquid fertilizer deep application furrow opener, spraying pressure of the liquid fertilizer and operating speed on the furrowing resistance, soil disturbance rate and the leakage amount of liquid fertilizer. The bionic design of the liquid fertilizer deep application furrow opener has a low soil disturbance rate and leakage amount of fertilizer when the operating speed is 0.8 m s−1, and the spraying pressure is 0.2 MPa. This furrow opener significantly improves the operating performance of the deep application of liquid fertilizer in the cold regions of China and is suitable for the deep application of liquid fertilizer in the paddy fields of this region.
    Type of Medium: Online Resource
    ISSN: 2077-0472
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2651678-0
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  • 5
    In: Metabolites, MDPI AG, Vol. 12, No. 11 ( 2022-10-29), p. 1040-
    Abstract: Gestational diabetes mellitus (GDM), a common perinatal disease, is related to increased risks of maternal and neonatal adverse perinatal outcomes. We aimed to establish GDM risk prediction models that can be widely used in the first trimester using four different methods, including a score-scaled model derived from a meta-analysis using 42 studies, a logistic regression model, and two machine learning models (decision tree and random forest algorithms). The score-scaled model (seven variables) was established via a meta-analysis and a stratified cohort of 1075 Chinese pregnant women from the Northwest Women’s and Children’s Hospital (NWCH) and showed an area under the curve (AUC) of 0.772. The logistic regression model (seven variables) was established and validated using the above cohort and showed AUCs of 0.799 and 0.834 for the training and validation sets, respectively. Another two models were established using the decision tree (DT) and random forest (RF) algorithms and showed corresponding AUCs of 0.825 and 0.823 for the training set, and 0.816 and 0.827 for the validation set. The validation of the developed models suggested good performance in a cohort derived from another period. The score-scaled GDM prediction model, the logistic regression GDM prediction model, and the two machine learning GDM prediction models could be employed to identify pregnant women with a high risk of GDM using common clinical indicators, and interventions can be sought promptly.
    Type of Medium: Online Resource
    ISSN: 2218-1989
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2662251-8
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  • 6
    In: Metals, MDPI AG, Vol. 13, No. 8 ( 2023-08-03), p. 1394-
    Abstract: The Pt–Ir alloy is an important electrical contact material in the aerospace field, and its electrical contact performance directly affects the reliability and stability of the circuit system. In order to elucidate the effect of Y on the breaking arc behavior of Pt–Ir alloys at different voltages, Pt-10Ir-1Y and Pt-25Ir-1Y alloys were prepared using melting and thermal processing, and the electrical contact tests were carried out at DC 15 A 12 V, 24 V, and 36 V. When comparing the results of Pt-10Ir and Pt-25Ir electrical contact tests, they showed that Y doping provided a tendency to concentrate individual arc erosion regions. Meanwhile, the comparative study showed that the addition of Y could inhibit the tendency of the Pt–Ir arc time to increase with voltage. At 36 V, the overall arc time of Pt–Ir–Y was significantly lower than that of Pt–Ir, and the fluctuation in arc time and arc energy was reduced. In addition, Y reduced the welding force of Pt–Ir alloys at 12 V, while Y improved the stability of the welding force of Pt–Ir alloys at 24 V. It could be seen that Y was favorable to improving the arc erosion resistance of the Pt–Ir alloy under certain conditions. The contact resistance analysis showed that there was an obvious partitioning phenomenon in the contact resistance of Pt–Ir alloys, and Y changed in this phenomenon at a certain voltage range. In addition, the material transfer direction of the Pt–Ir alloy was from the anode to the cathode, which was not affected by the voltage change, while the addition of Y changed the material transfer direction from the cathode to the anode, which was likely caused by the change from the metal-phase arc dominance to gas-phase arc dominance.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2662252-X
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  • 7
    In: Remote Sensing, MDPI AG, Vol. 15, No. 10 ( 2023-05-16), p. 2601-
    Abstract: To better understand the possible role of projected land use and cover change (LUCC) in future regional climate projections, we explored the regional climate change response from land use/cover change under different climate scenarios. To do so, we propose a research framework based on different SSP-RCPs to simulate and explore the impacts of future land use/cover changes on the future climate of Zhengzhou City, China, using the Weather Research and Forecasting (WRF) model with land use/cover and meteorological data under different SSP-RCP scenarios based on CMIP6. Two scenarios, SSP2-4.5 and SSP5-8.5, were compared and analyzed by simulating changes in future climate factors of temperature at 2 m height above ground(T2) and precipitation. The results show that T2 is higher for all 4 months by the year 2060 compared to that in the year 2030. Furthermore, a comparison of the abovementioned years showed that the mean temperatures of January and July were higher than those of SSP2-4.5 under the SSP5-8.5 scenario in both years, but in 2030, the mean T2 of April and October were lower than those of SSP2-4.5 under the SSP5-8.5 scenario. In terms of precipitation, both scenarios have no significant precipitation in July in 2030 and 2060, but there is an unusual increase in January and October.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2513863-7
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  • 8
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  International Journal of Molecular Sciences Vol. 19, No. 3 ( 2018-03-03), p. 721-
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 19, No. 3 ( 2018-03-03), p. 721-
    Type of Medium: Online Resource
    ISSN: 1422-0067
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 9
    In: Metals, MDPI AG, Vol. 13, No. 9 ( 2023-09-13), p. 1589-
    Abstract: In order to explore the influence of rare earth element Y on the electrical contact properties of Pt–Ir alloys, Pt–10Ir–Y and Pt–25Ir–Y were prepared via arc melting combined with thermal processing, and electrical contact experiments were carried out with a DC voltage of 24 V and current ranging from 5 A to 25 A. Comparative analyses were conducted to analyze the changes in the break arc duration and arc energy, as well as the contact resistance before and after the addition of Y. The arc erosion surface morphology was characterized, and the transfer behavior of the alloys was discussed. The results show that at 5 A and 25 A, adding Y improves the stability of the arc duration of the Pt–Ir alloy, but it increases the overall arcing energy and decreases the stability. The contact resistance of the Pt–Ir alloy shows a clear partitioning phenomenon; the partitioning phenomenon disappears after the addition of Y, and the contact resistance fluctuates around the average value. The material transfer direction of the Pt–Ir alloy is affected by the current change, while the material transfer direction of the Pt–Ir–Y alloy is always from cathode to anode. The research results provide a reference for the performance optimization of Pt–Ir alloys.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2662252-X
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  • 10
    In: Agriculture, MDPI AG, Vol. 13, No. 4 ( 2023-04-03), p. 824-
    Abstract: Apples are ranked third, after bananas and oranges, in global fruit production. Fresh apples are more likely to be appreciated by consumers during the marketing process. However, apples inevitably suffer mechanical damage during transport, which can affect their economic performance. Therefore, the timely detection of apples with surface defects can effectively reduce economic losses. In this paper, we propose an apple surface defect detection method based on weight contrast transfer and the MobileNetV3 model. By means of an acquisition device, a thermal, infrared, and visible apple surface defect dataset is constructed. In addition, a model training strategy for weight contrast transfer is proposed in this paper. The MobileNetV3 model with weight comparison transfer (Weight Compare-MobileNetV3, WC-MobileNetV3) showed a 16% improvement in accuracy, 14.68% improvement in precision, 14.4% improvement in recall, and 15.39% improvement in F1-score. WC-MobileNetV3 compared to MobileNetV3 with fine-tuning improved accuracy by 2.4%, precision by 2.67%, recall by 2.42% and F1-score by 2.56% compared to the classical neural networks AlexNet, ResNet50, DenseNet169, and EfficientNetV2. The experimental results show that the WC-MobileNetV3 model adequately balances accuracy and detection time and achieves better performance. In summary, the proposed method achieves high accuracy for apple surface defect detection and can meet the demand of online apple grading.
    Type of Medium: Online Resource
    ISSN: 2077-0472
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2651678-0
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