The objective of this study is to gain a deeper understanding of the trade-offs between the aboveground biomass (AGB) and belowground biomass (BGB) due to environmental factors in alpine grasslands, ...including alpine steppes and alpine meadows, on the Tibetan Plateau. We assessed transect surveys to determine the response threshold and critical determinant of trade-offs. Additionally, a non-significant relationship was observed between trade-offs and climate factors and soil properties when the data for the alpine meadow and alpine steppe were analyzed separately. However, the trade-off between AGB and BGB were increased with soil nitrogen and organic carbon gradients across the alpine grassland. The results demonstrate the trade-off effects of AGB and BGB in alpine grasslands, emphasizing the need for an understanding of how the trade-off is affected by drivers of critical environmental factors at the regional scale. Consequently, trade-offs are an ecological indicator and tool for ecological management and decision-making.
Abstract Improving walkability in the campus environment and socio-psychological environments can promote students’ mental health and subjective well-being. This study aimed to propose a theoretical ...model to investigate the link of perceived campus walkability (PCW) with mental health and life satisfaction (LS), and to disentangle the mediating impact of socio-psychological environments and academic performance on this relationship, while simultaneously considering the effect of the COVID-19 pandemic. We applied structural equation modeling to analyze the data collected through a questionnaire survey conducted at six universities and colleges in Yantai, China. PCW had both direct and indirect positive effects on mental health and LS. However, indirect effects are greater than direct effects. Walking attitudes, social capital, and academic performance were critical to the relationship between PCW, mental health, and LS. Academic performance had the strongest indirect effect on mental health, while social capital had the strongest indirect effect on LS. We also found that during the COVID-19 pandemic, body mass index and family income were significantly correlated with mental health and LS. The findings indicate that campus planners and policymakers should improve PCW and support the socio-psychological environment to promote students’ mental and social health during situations like the COVID-19 pandemic.
CO2, despite its role as the primary greenhouse gas, is well-accepted as the most affordable and abundant nontoxic C1 source. Integrated CO2 capture and conversion (ICCC) is an emerging and promising ...process capable of reducing CO2 emissions and in-situ producing value-added products such as CH4 and syngas. This article reviews the recent research progress on the ICCC process, with an emphasis on the development of dual function materials (DFMs). The ICCC process with the combination of different CO2 catalytic conversions is first discussed from a thermodynamic point of view. The influence of operation parameters on the performance of DFMs is also summarized in detail. Then, the development of DFMs categorized by the catalytic component (i.e., Ni, Ru, etc.) is reviewed, including their performance and potential reaction mechanisms. Finally, the challenges and prospects of the ICCC process are highlighted.
•Photocatalytic oxidation of SO2 on TiO2 was improved after Na2CO3 modification.•The improvement was due to the enhanced adsorption and photocatalytic ability.•The recombination of electron-hole was ...suppressed by the formation of CO3−.•The generation of hydroxyl radicals was promoted because of the deposited Na2CO3.
The effects of Na2CO3 on the photocatalytic oxidation (PCO) of SO2 with UV irradiated TiO2 (P25) were studied using a fixed bed reactor. Na2CO3 was loaded onto P25 using a wet coating method. The PCO efficiency for SO2 with P25 was enhanced by 1.6 and 10.6 times using 0.05 M and 0.2 M Na2CO3 modified P25, respectively. The enhancement of the photocatalytic activity of P25 by Na2CO3 was observed only with the presence of water vapor. Low temperature (113 K) electron spinning resonance (ESR) analysis showed that Na2CO3 promoted the photoinduced electron-hole separation by trapping valance band holes and forming carbonate radicals (CO3−). The ESR spin trapping analyses showed a remarkable increase in the intensity of DMPO-OH adducts with the addition of Na2CO3. This increase phenomena indicates that more reactive species were formed on the P25 surface. The deposited Na2CO3 inhibited the recombination of electron-hole pairs and promoted the generation of hydroxyl radicals (OH), most likely through the photo-reduction of O2 adsorbed by the conduction band electrons. The generated •OH radicals reacted with SO2 rapidly and improved the PCO effectiveness of P25.
Two single fed low-profile cavity-backed slot antennas and an antenna array for circular polarization (CP) applications are introduced. By employing the substrate-integrated waveguide (SIW) and ...half-mode SIW (HMSIW) techniques in antenna designs, low-profile cavity-backed structures are realized using the low-cost standard printed circuit board process. First, a novel spoon-shaped slot antenna is proposed to realize CP radiation based on the SIW cavity. Then, to minimize the antenna size and achieve the impedance bandwidth enhancement, the HMSIW cavity is introduced to realize a cavity-backed semicircle slot antenna (SSA). The equivalence between the edge of the HMSIW cavity and the longitude slot curved on the surface of the SIW cavity is proposed to guide the design process of the SSA. In addition, two hybrid modes are used to improve the impedance bandwidth of the SSA. Furthermore, a sequential rotation antenna array is introduced to validate the feasibility of the SSA for antenna array application. Finally, the proposed antennas and the antenna array are designed and fabricated at 28 GHz. The measured and simulated results agree very well.
Using aperture-fed stacked curl elements, a full corporate-fed millimeter-wave planar broadband circularly polarized antenna array is proposed. First, the stacked curl element is aperture-fed, using ...the substrate-integrated waveguide (SIW) feeding network. This element is designed under a specific boundary condition, which leads to an excellent agreement of impedance bandwidth and axial ratio (AR) bandwidth between the designed element and the corresponding antenna array. Simulation results show that the antenna element achieves 35.8% impedance bandwidth and 37.8% 3 dB AR bandwidth with a maximum gain of 8.2 dBic. Then, a 2 × 2 subarray is designed to achieve 33.1% impedance bandwidth. Next, the full-corporate SIW feeding scheme is utilized to construct the 8×8 broadband antenna array. Finally, the 8×8 antenna array is fabricated and its performance is evaluated. Measurement results show that its impedance bandwidth is 35.4%, 3 dB AR bandwidth is 33.8%, and 3 dB gain bandwidth is 32.2% with a peak gain of 23.5 dBic. Considering these three types of bandwidth together, its overall bandwidth is 30.6%. Good efficiency of about 70% is obtained because of the low-loss full-corporate SIW feeding scheme. A 4 × 4 multibeam array is also simulated to verify the multibeam potential of the proposed antenna array.
A single-fed low-profile millimeter-wave substrate-integrated waveguide (SIW) cavity-backed slot antenna for dual-band circular polarization (CP) applications is proposed. First, by employing two ...annular exponential slots carved on the surface of a circular SIW cavity, dual-band CP radiation is achieved. Two different modes, that is, the cavity mode and the surface mode, separately modulated by the cavity field distribution and the surface current, are investigated. They are utilized to achieve the dual-band CP radiation. Next, a two-order matching circuit using inductor windows is introduced to achieve dual-band matching at the low-profile antenna design with the help of the differential evolution method. Finally, for the dual-band CP application at 37.5 and 47.8 GHz, an antenna prototype is fabricated and its performance is evaluated. Simulation and measurement results agree very well.
The poorly differentiated thyroid carcinoma (THCA) subtype is associated with an aggressive disease course, a less favorable overall prognosis, and an increased risk of distant organ metastasis. In ...this study, our objective was to explore the potential utility of the Sprouty-related EVH1 domain-containing protein 3 (SPRED3) as a biomarker for early diagnosis and prognosis in THCA patients. The differentially expressed prognostic-related genes associated with THCA were identified by querying The Cancer Genome Atlas (TCGA) database. The difference in the expression of the SPRED3 gene between thyroid carcinoma (THCA) tissues and normal tissues was analyzed using data from The Cancer Genome Atlas (TCGA) and further validated through immunohistochemistry. Univariate and multivariate Cox regression models were used, along with clinical information from THCA patients, to analyze the prognostic value of the SPRED3 gene in THCA patients. Functional enrichment analysis was subsequently performed to elucidate the molecular mechanisms underlying the regulatory effects of the SPRED3 gene on thyroid carcinoma. Additionally, we calculated the percentage of infiltrating immune cells in THCA patients and evaluated their correlation with SPRED3 gene expression. Compared with those in noncancerous thyroid tissue, the gene and protein expression levels of SPRED3 were found to be elevated in thyroid carcinoma tissues. Furthermore, the expression of SPRED3 in thyroid carcinoma exhibited significant correlations with tumor location, histological grade, pathological stage, and tumor node metastasis classification (TNM) stage. Univariate and multivariate Cox proportional hazards (Cox) regression analyses demonstrated that SPRED3 could serve as an independent prognostic factor for predicting the overall survival of THCA patients. The results of functional enrichment analysis suggested the potential involvement of SPRED3 in the regulation of extracellular matrix organization, epidermal development, signaling receptor activator activity, skin development, receptor ligand activity, glycosaminoglycan binding, neuroactive ligand‒receptor interaction, the IL-17 signaling pathway, and the PI3K-Akt signaling pathway. Additionally, there were significant correlations between the expression level of the SPRED3 gene and the infiltration of various immune cells (eosinophils, central memory T cells, neutrophils, macrophages, and NK cells) within the thyroid tumor microenvironment. SPRED3 can be used as a prognostic biomarker in patients with THCA could potentially be therapeutic target for THCA.
Indoor small-scale spatiotemporal propagation characteristics across multiple 5G millimeter-wave (mmWave) candidate bands are investigated. First, using a custom-designed channel sounder, channel ...measurement campaigns are conducted in indoor environments to capture the delay and angles of departure and arrival of the paths. Measurement results exhibit excellent agreements with physical scatterers and radio propagation environments. Next, the layout-related multipath propagation analyses are utilized to model frequency-dependent channel parameters for different polarimetric combinations, including root-mean-square delay and angular spread. Modeling results not only complete the 3GPP channel model above 6 GHz, but also help to understand the impacts of frequency and polarization on the radio wave propagation at the mmWave bands.
With the rapid development of modern wireless communications and radar, antennas and arrays are becoming more complex, therein having, e.g., more degrees of design freedom, integration and ...fabrication constraints and design objectives. While full-wave electromagnetic simulation can be very accurate and therefore essential to the design process, it is also very time consuming, which leads to many challenges for antenna design, optimization and sensitivity analysis (SA). Recently, machine-learning-assisted optimization (MLAO) has been widely introduced to accelerate the design process of antennas and arrays. Machine learning (ML) methods, including Gaussian process regression, support vector machine (SVM) and artificial neural networks (ANNs), have been applied to build surrogate models of antennas to achieve fast response prediction. With the help of these ML methods, various MLAO algorithms have been proposed for different applications. A comprehensive survey of recent advances in ML methods for antenna modeling is first presented. Then, algorithms for ML-assisted antenna design, including optimization and SA, are reviewed. Finally, some challenges facing future MLAO for antenna design are discussed.
PDF
