Remote sensing and social sensing data reveal scale-dependent and system-specific strengths of urban heat island determinants

Urban natural surfaces and non-surface human activities are key factors determining the urban heat island (UHI), but their relative importance remains highly controversial and may vary at different spatial scales and focal urban systems. However, systematic studies on the scale-dependency system-specificity remain largely lacking. Here, we selected 32 major Chinese cities as cases and used Landsat 8 images to retrieve land surface temperature (LST) and quantify natural surface variables using point of interest (POI) data as a measure of the human activity variable and using multiple regression and relative weight analysis to study the contribution and relative importance of these factors to LST at a range of grain sizes (0.25–5 km) and spatial extents (20–60 km). We revealed that the contributions and relative importance of natural surfaces and human activities are largely scale-dependent and system-specific. Natural surfaces, especially vegetation cover, are often the most important UHI determinants for a majority of scales, but the importance of non-surface human activities is increasingly pronounced at a coarser spatial scale with respect to both grain and spatial extent. The scaling relations of the UHI determinants and their relative importance were mostly linear-like at the city-collective level, but highly diverse across individual cities, so reducing non-surface heat emissions could be the most effective measure in particular cases, especially at relatively large spatial scales. This study advances the understanding of UHI formation mechanisms and highlights the complexity of the scale issue underpinning the UHI effect

Effectiveness of Oral Fluid in Pathogenic Surveillance of Acute Respiratory Infection

Oral fluid (OF) is a new safe, non-invasive, convenient, and efficient biological sample that can be used for virus nucleic acid and antibody detection. Because few studies have performed surveillance of multiple respiratory pathogens, this study sought to explore the application value of OF in this field. OF and throat swabs were collected from December 2020 to December 2021 in patients with acute respiratory tract infections in Beijing. Multiplex real-time PCR was performed, and the detection performance of two samples was compared. A total of 769 OF and throat swab samples were collected. The detection rates of respiratory pathogens in throat swabs and OF were 29.26% (225/769) and 20.81% (160/769), respectively. The sensitivity and specificity of the OF assay, compared with the throat swab assay, were 71.11% (160/225) and 100% (544/544), respectively. The two assays had excellent agreement (kappa = 0.78). The detection consistency varied among pathogens. For OF samples, the most common pathogen was the influenza B virus, and the highest detection rate was in the ≤5-year-old group. The highest positivity rate was observed in December 2021. OF samples have excellent potential for the epidemiological surveillance of respiratory pathogens, and may have application prospects in preventing and controlling infectious diseases

FnnmOS-ELM: A Flexible Neural Network Mixed Online Sequential Elm

The learning speed of online sequential extreme learning machine (OS-ELM) algorithms is much higher than that of convolutional neural networks (CNNs) or recurrent neural network (RNNs) on regression and simple classification datasets. However, the general feature extraction of OS-ELM makes it difficult to conveniently and effectively perform classification on some large and complex datasets, e.g., CIFAR. In this paper, we propose a flexible OS-ELM-mixed neural network, termed as fnnmOS-ELM. In this mixed structure, the OS-ELM can replace a part of fully connected layers in CNNs or RNNs. Our framework not only exploits the strong feature representation of CNNs or RNNs, but also performs at a fast speed in terms of classification. Additionally, it avoids the problem of long training time and large parameter size of CNNs or RNNs to some extent. Further, we propose a method for optimizing network performance by splicing OS-ELM after CNN or RNN structures. Iris, IMDb, CIFAR-10, and CIFAR-100 datasets are employed to verify the performance of the fnnmOS-ELM. The relationship between hyper-parameters and the performance of the fnnmOS-ELM is explored, which sheds light on the optimization of network performance. Finally, the experimental results demonstrate that the fnnmOS-ELM has a stronger feature representation and higher classification performance than contemporary methods

Metal Emulsion-Based Synthesis, Characterization, and Properties of Sn-Based Microsphere Phase Change Materials

A comparative study of the metal emulsion-based synthesis of Sn-based materials in two different types of molten salts (namely LiCl–KCl–CsCl and LiNO3-NaNO3-KNO3 eutectics) is presented, and the properties of Sn, Sn-Cu and Sn-Cu-Zn microsphere phase change materials prepared in chloride salts are evaluated by differential scanning calorimetry (DSC) to understand the effect of element doping. Despite a high ultrasonic power (e.g., 600 W or above) being required for dispersing liquid Sn in the chloride system, well-shaped Sn microspheres with a relatively narrow size range, e.g., about 1 to 15 µm or several micrometers to around 30 µm, can be prepared by adjusting the ultrasonic power (840–1080 W), sonication time (5–10 min) and the volume ratio of salts to metal (25:1–200:1). Such a method can be extended to the synthesis of Sn-based alloy microspheres, e.g., Sn-Cu and Sn-Cu-Zn microspheres. In the nitrate system, however, a very low ultrasonic power (e.g., 12 W) can be used to disperse liquid Sn, and the particles obtained are much smaller. At low ultrasonic power (e.g., 12 W), the particle size is generally less than 10 or 4 µm when the sonication time reaches 2 or 5 min, and at high ultrasonic power, it is typically in the range of hundreds of nanometers to 2 µm, regardless of the change in ultrasonic power (480–1080 W), irradiation time (5–10 min), or volume ratio of salts to metal (25:1–1000:1). In addition, the appearance of a SnO phase in the products prepared under different conditions hints at the occurrence of a reaction between Sn droplets and O2 in situ generated by the ultrasound-induced decomposition of nitrates, and such an interfacial reaction is believed to be responsible for these differences observed in two different molten salt systems. A DSC study of Sn, Sn-Cu, and Sn-Cu-Zn microspheres encapsulated in SiO2 reveals that Cu (0.3–0.9 wt.%) or Cu-Zn (0.9 wt.% Cu and 0.6% Zn) doping can raise the onset freezing temperature and thus suppress the undercooling of Sn, but a broad freezing peak observed in these doped microspheres, along with a still much higher undercooling compared to those of reported Sn-Cu or Sn-Cu-Zn solders, suggests the existence of a size effect, and that a low temperature is still needed for totally releasing latent heat. Since the chloride salts can be recycled by means of the evaporation of water and are stable at high temperature, our results indicate that the LiCl–KCl–CsCl salt-based metal emulsion method might also serve as an environmentally friendly method for the synthesis of other metals and their alloy microspheres

Undercooling, Thermal Stability, and Application in Exothermic Catalytic Reaction of SiO₂ Encapsulated SnZnCu Microspheres

SiO2 encapsulated SnZnCu microspheres (several micrometers to about 30 μm in diameter) with very low undercooling, narrow freezing/melting range, and high thermal cycling stability have been produced and used as the temperature stabilizer of the packed bed in highly exothermic Fischer–Tropsch reaction. The core–shell structured SnZnCu@SiO2 microspheres are prepared in a two-step way, namely SnZnCu microspheres are firstly produced via a molten LiCl–KCl–CsCl eutectic-based metal emulsion method, and then a sol–gel approach is employed to coat them with a uniform, anti-leakage SiO2 layer. It is found that raising the amount of Zn to 4.0 at.% is critical for achieving a very low undercooling (0.04Cux@SiO2 vs. about 84 °C for Sn@SiO2) and a narrow freezing/melting peak width, and both undercooling and peak width are almost unchanged as the Cu content (x) increases from 1.5 to 3.0 at.%. However, their thermal cycling stability depends positively on the amount of Cu and can be remarkably improved when 3.0 at.% Cu is added. The results also show that low undercooling and narrow freezing/melting peak width are associated with the formation of Sn–Zn–Cu ternary eutectic and metastable phase Cu5Zn8, and poor thermal cycling stability of SnZn0.04Cux@SiO2 microspheres with low Cu content is related to the decomposition of Cu5Zn8 during thermal cycling. By embedding thermally stable SnZn0.04Cu0.03@SiO2 microspheres into the Co/SiO2 catalyst for Fischer–Tropsch synthesis, the temperature gradient in the catalyst bed can be significantly reduced by suppressing the formation of hot spots or thermal runaway and thus rapid deactivation of Co catalyst that occurs in the SnZn0.04Cux@SiO2-absent Co/SiO2 catalyst can be avoided

Intra-annual wood formation of subtropical Chinese red pine shows better growth in dry season than wet season

China's subtropical forests play a vital role in sequestering global carbon; therefore, it is critical to conduct a precise investigation of intra-annual wood formation in these ecosystems to clarify the mechanisms behind this. Two field experiments were established in Chinese subtropical forests to monitor weekly the intra-annual xylem formation of Pinus massoniana Lamb. from January to December 2015, using the recently developed micro-sampling approach. The effects of climate on wood formation were also assessed using linear or mixed models. Results indicate that there is an inactive period that might be semi-dormancy in subtropical pine ecosystems in January compared with the complete dormancy in temperate and boreal ecosystems and the fully active or short-term dormancy in tropical ecosystems. The duration of xylem formation of Chinese red pine in subtropical China in 2015 was 4–6 months longer than temperate and boreal forests. Moreover, trees were found to grow better during the dry season than the wet season, indicating that the Chinese red pine ecosystem is more strongly regulated by net energy than by environmental factors. Our findings indicate that China's subtropical pine forests may benefit from the expected longer dry seasons, possibly leading to better forest growth and improved carbon sequestration under continued climate warming

Roles of the MST1-JNK signaling pathway in apoptosis of colorectal cancer cells induced by Taurine

The aim of this study was to observe the impact of the mammalian sterile 20-like kinase 1-c-Jun N-terminal kinase (MST1-JNK) signaling pathway on apoptosis in colorectal cancer (CRC) cells induced by Taurine (Tau). Caco-2 and SW620 cells transfected with p-enhanced green fluorescent protein (EGFP)-MST1 or short interfering RNA (siRNA)-MST1 were treated with Tau for 48 h. Apoptosis was detected by flow cytometry, and the levels of MST1 and JNK were detected by western blotting. Compared with the control group, 80 mM Tau could significantly induce apoptosis of CRC cells, and the apoptotic rate increased with increasing Tau concentration (P < 0.01). Meanwhile, the protein levels of MST1 and phosphorylated (p)-JNK in Caco-2 cells increased significantly (P < 0.01). The apoptotic rate of the p-EGFP-MST1 plasmid-transfected cancer cells was significantly higher than that of the control group (P < 0.05); however, the apoptotic rate of the p-EGFP-MST1+Tau group was increased further (P < 0.01). Silencing the MST1 gene could decrease the apoptotic rate of cancer cells, and Tau treatment could reverse this decrease. Blocking the JNK signaling pathway significantly reduced the Tau-induced apoptotic rate of CRC cells. Thus, the MST1-JNK pathway plays an important role in Tau-induced apoptosis of CRC cells

Climate Factors Affect Above–Belowground Biomass Allocation in Broad-Leaved and Coniferous Forests by Regulating Soil Nutrients

The allocation of plant biomass above and below ground reflects their strategic resource utilization, crucial for understanding terrestrial carbon flux dynamics. In our comprehensive study, we analyzed biomass distribution patterns in 580 broadleaved and 345 coniferous forests across China from 2005 to 2020, aiming to discern spatial patterns and key drivers of belowground biomass proportion (BGBP) in these ecosystems. Our research revealed a consistent trend: BGBP decreases from northwest to southeast in both forest types. Importantly, coniferous forests exhibited significantly higher BGBP compared to broadleaved forests (p p > 0.05). Climatic factors, such as temperature and rainfall, influenced biomass partitioning in both strata by altering soil nutrients, particularly soil pH. These findings provide valuable insights into understanding carbon sequestration dynamics in forest ecosystems and improving predictions of the future trajectory of this critical carbon cycle component

Surface Topographical Engineering of Chiral Au Nanocrystals with Chiral Hot Spots for Plasmon-Enhanced Chiral Discrimination

Surface roughness in chiral plasmonic nanostructures generates asymmetrical localized electromagnetic fields, which hold great promise for applications in chiral recognition, chiroptical spectroscopic sensing, and enantioselective photocatalysis. In this study, we develop a surface topographical engineering approach to precisely manipulate the surface structures of chiral Au nanocrystals. Through carefully controlling the amounts of l- or d-cystine (Cys) and the seed solution in the growth process, we successfully synthesize chiral Au nanocrystals with highly disordered, ordered, and less ordered wrinkled surfaces. An underlying principle governing the relationship between surface roughness, orderliness, and chiroptical response is also proposed. More importantly, the chiral ordered wrinkles on the surfaces of the nanocrystals generate asymmetrical localized electronic fields with enhanced intensity, which achieve excellent plasmon-enhanced chiral discrimination ability for penicillamine (Pen) enantiomers. This work offers exciting prospects for manipulating the surface structures of chiral nanocrystals and designing highly sensitive plasmon-enhanced enantioselective sensors with chiral hot spots