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Core-shell thermally expandable microspheres (TEMs) were prepared via Pickering suspension polymerization. Acrylonitrile (AN), methacrylic acid (MAA) and N,N-dimethylacrylamide (DMAA) were used as the comonomers, the 2,2′-azobisisobutyronitrile (AIBN) was used as the initiator and the ethyleneglycol dimethacrylate (EGDMA) was used as the crosslinker. The effects of initiator concentration, cross-linking agent concentration and modified monomer type on the morphology, thermal properties and encapsulation content of TEMs were investigated. The results show that the small change in initiator concentration had a significant effect on the properties of TEMs. When the initiator concentration was 0.55%, the microspheres showed core-shell structure and the maximum expansion ratio was 3.06 times. According to the scanning electron microscope (SEM) image, the heat resistance of the microspheres increased with the increase of the content of crosslinking agent. The lower the water solubility of the modified monomer, the more stable the foaming of the TEMs. When methyl acrylate (MA) was used as a modified monomer, the initial expansion temperature of the microspheres was 163.2°C, the maximum expansion temperature was 223.5 °C, and the encapsulation content of the blowing agent was 14.70%.

Background: The prevalence of childhood overweight and obesity in China has been rapidly increasing in recent years. The purposes of this study were to investigate the prevalence of infant overweight in Beijing and to explore the influencing factors using a generalized estimating equation (GEE) model. Methods: This is a birth cohort study from January 2022 to December 2022 in Beijing, involving 2,008 newborns from local residents. Four times of follow-up visits were conducted at 2, 5, 8, and 12 months of age for physical measurements and health information collection. Multiple exposures were considered, including demographic characteristics of infants, maternal pregnancy information, feeding pattern and outdoor activities of infants. The GEE model was utilized to identify influencing factors for infant overweight while adjusting for potential confounders. Results: The prevalence of overweight for 2-, 5-, 8-, and 12-month-old infants were 14.4%, 21.6%, 24.4%, and 24.2%, respectively. Among the influencing factors, irregular exercise during pregnancy (OR = 1.190, P = 0.045), mixed feeding or artificial feeding (non-exclusive breastfeeding) (OR = 1.233, P = 0.025), high birth weight (OR = 1.468, P < 0.001), and high pre-pregnancy body mass index (BMI) (OR = 2.113, P = 0.005) were positively correlated with infant overweight. Conversely, weight gain ≤ 15.0 kg during pregnancy (OR = 0.778, P = 0.016), high birth length (OR = 0.990, P = 0.003), and longer duration of outdoor activity for infants (OR = 0.764, P < 0.001) were negatively correlated with infant overweight. Conclusions: Our findings suggest certain factors are associated with infant overweight risk. Further research is required before making causal inferences and formulating preventive strategies for infant overweight. [ABSTRACT FROM AUTHOR]

This work reports a metal–insulator–semiconductor High-Electron-Mobility-Transistor (HEMT) with Al2O3/in situ GaON bi-layer gate dielectric for improved threshold voltage (VTH) stability and reduced interface state density. With a combination of in situ GaON and large bandgap Al2O3 on top of the recessed gate region, normally-off HEMT was achieved with high On/Off current (ION/IOFF) ratio of 109, low VTH hysteresis less than 60 mV, and low-interface trap density (Dit) in the range of 4 × 1011–2 × 1012 cm−2·eV−1. Thanks to the sharp GaN/oxide interface with narrow distribution of lattice constant, uniform strain distribution and significantly reduced trap density were obtained. More importantly, our proposed bi-layer gate dielectric is perfectly compatible with the conventionally utilized gate recessing technique compared to the conventionally utilized in situ SiNx, demonstrating itself as a promising candidate in GaN power devices. [ABSTRACT FROM AUTHOR]

As a contactless and non-invasive tool, ground penetrating radar (GPR) plays an important role in buried object detection. However, the performance of GPR images is deteriorated severely due to the clutter in radar echo signals, including echoes reflected from ground-air surface and other undesired signals. Low-rank sparse decomposition (LRSD) has been proved to be an effective tool to separate clutter and targets as low-rank and sparse components respectively. However, the properties of targets in images cannot be fully represented by sparsity. To combine LRSD with characters of target images, a robust principal component analysis combined with top-hat transform (RPCA-THT) is proposed. RPCA-THT optimizes the step of shrinking the sparse component in robust principal component analysis (RPCA). It performs a top-hat transform on the sparse component with a specially designed kernel matrix. Then the sparse component shrinks according to the normalized top-hat transform of the sparse matrix. In this way, targets prefer to be left in the sparse component than clutter. We design a well-performed kernel for distinguishing targets in the sparse matrix. The experimental results on simulation and real data show that the proposed method has better performance than several state-of-the-art clutter suppression algorithms. [ABSTRACT FROM AUTHOR]

Ultra‐wideband microwave absorbing (MA) materials covering the low‐frequency range (2–6 GHz) are highly desirable in civil and military fields. These materials can be fabricated based on the design of electromagnetic meta‐structure. Herein, a structural‐functional‐integrated ultra‐wideband SiO2 fiber reinforced cyanate ester (CE) MA composite based on an in situ‐grown graphene meta‐nanointerface layer (GrMI) (SiO2f/GrMI/CE) is reported. The relationship between the periodic structure of the graphene nano‐interface layer and the MA performance is discussed through experiments and simulations. The results show that SiO2f/GrMI/CE with a thickness of 8.78 mm exhibits an effective absorption bandwidth of 15.46 GHz (2.54–18 GHz). Remarkably, the reflection loss remains basically unchanged upon increasing the incident angle from 5° to 50°. Additionally, GrMI is an effective load‐bearing constituent, which increases the interfacial shear stress between SiO2f and the CE by ≈210% and contributes to achieving composites with an ultra‐high flexural strength (552.7 MPa). The excellent structural‐functional‐integrated performances ensure that the SiO2f/GrMI/CE composites are suitable for use as the skin materials of microwave stealth aircraft and other civil facilities. The work provides a novel pathway for the design of thinner, wider, lighter, and stronger MA components. [ABSTRACT FROM AUTHOR]

The lack of funding is one of the most important challenges in achieving the 2030 Sustainable Development Goals (SDGs) in African countries. Can foreign direct investment (FDI) from China as an important source of external financing help African countries achieve their SDGs? This study used the panel data random effects model to analyze the influence of China’s direct investment on SDG scores. Then, the study conducted the ordered probit model to examine the influence of FDI from China on the trend of achieving each SDG in Africa, with the SDGs being grouped into social, economic, and environmental dimensions. Results showed that China’s direct investment contributed to the achievement of SDGs in Africa. FDI from China positively influenced the SDG score in general and some of the 17 SDG scores including SDG 7 (Affordable and Clean Energy), SDG 8 (Decent Work and Economic Growth), SDG 9 (Industry, Innovation, and Infrastructure), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 15 (Life on Land). The relationship between FDI from China and the trends for SDG 7, 8, 9, 11 (Sustainable Cities and Communities), and 14 (Life below Water) was significantly positive. However, the SDG scores above belonged to the economic and environmental dimensions, whereas FDI from China had no significant influence on the social-dimension SDG scores and trends. To further expand the scale of China’s direct investment, more investment scopes, particularly those in the social dimension, should be developed. Moreover, China–Africa cooperation should be deepened to create a good investment environment for the achievement of African countries’ SDGs and to facilitate China’s implementation of promoting the development of developing countries as mentioned in the 2030 Agenda of Sustainable Development and building the China–Africa community with a shared future.