Understanding the balance between the supply and demand of leisure services (LSs) in urban areas can benefit urban spatial planning and improve the quality of life of residents. In cities in ...developing countries, the pursuit of rapid economic growth has ignored residents’ demand for LSs, thereby leading to a high demand for and short supply of these services. However, due to the lack of relevant research data, few studies have focused on the spatial mismatch in the supply and demand of LSs in urban areas. As typical representatives of multisource geographic data, social sensing data are readily available at various temporal and spatial scales, thus making social sensing data ideal for quantitative urban research. The objectives of this study are to use openly accessible datasets to explore the spatial pattern of the supply and demand of LSs in urban areas and then to depict the relationship between the supply and demand by using correlation analysis. Therefore, taking Beijing, China, as an example, the LS supply index (SI) and societal needs index (SNI) are proposed based on open data to reflect the supply and demand of LSs. The results show that the spatial distribution of the LS supply and demand in Beijing varies with a concentric pattern from the urban center to suburban areas. There is a strong correlation between the supply and demand of commercial and multifunctional services in Chaoyang, Fengtai, Haidian and Shijingshan, but there is no obvious correlation between the supply and demand of ecological and cultural services in Beijing. Especially in Dongcheng and Xicheng, there is no obvious correlation between the supply and demand of all services. The proposed approach provides an effective urban LS supply and demand evaluation method. In addition, the research results can provide a reference for the construction of “happy cities” in China.
In this paper, a new magnetic molecular imprinted polymer-cyclodextrin (MMIP-CD) material was prepared by connecting β-cyclodextrin (CD) on the surface of a magnetic molecular imprinted polymer ...(MMIP) and used for the rapid and specific adsorption of zearalenone (ZEN). By using warfarin as the virtual template molecule, tetraethyl orthosilicate (TEOS) as the crosslinking agent, and (3-aminopropyl) triethoxysilane (APTES) as the functional monomer, a MMIP was produced by surface imprinting technology. Sulfobutyl ether-β-cyclodextrin attached to the surface of the MMIP under heating conditions produced a new specific adsorption material with exceptional adsorption capacity and excellent selectivity for ZEN. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and TEM-mapping results showed that the prepared MMIP-CD had a uniform particle size of about 480 nm, and the molecularly imprinted layer was successfully wrapped on the surface of the nanoparticles with a thickness of about 50 nm, whereby the cyclodextrin was effectively attached to the surface of the MMIP. The adsorption mechanism of MMIP-CD was confirmed by kinetic adsorption and thermodynamic adsorption experiments, the maximum adsorption capacity was found to be about 30 mg g-1, and the adsorption equilibrium could be reached within 20 min. The value of IF (QMMIP-CD/QMNIP) is 4.642. This showed that compared with MNIP, MMIP-CD showed a greatly improved specific adsorption capacity of ZEN. Selective experiments proved that MMIP-CD effectively combined the advantages of MMIP and CD, enhancing the adsorption capacity together with reducing the disadvantages that MMIP cannot distinguish structural analogs and CD cannot identify hydrophobic compounds effectively. In actual sample testing, the limit of quantification (LOQ) and limit of detection (LOD) were 0.1 ng kg-1 and 0.3 ng kg-1, respectively. The stability and detection precision of this method were 0.98-2.76% and 1.67-3.88%, respectively. The results proved that MMIP-CD had good development potential in the field of selective adsorption of ZEN, and laid the foundation for follow-up research.
The selective transport of water/ions through conventional forward osmosis (FO) membranes is largely impeded by solution-diffusion and internal concentration polarization (ICP). Herein, we report a ...novel air nanobubbles (ANBs) incorporated sandwich-structured carbon nanotube membrane (CNM) for highly permeable and stable FO desalination by taking advantage of the nanofluidic transport at the solid/liquid/vapor interface. Fluorinated multi-walled carbon nanotubes (F-MWCNTs) were assembled as the superhydrophobic interlayer between a hydrophilic cellulose acetate (CA) layer and a hydrophilic polyacrylonitrile (PAN) nanofibrous layer. The trapped ANBs in the superhydrophobic F-MWCNT layer crucially regulated the continuous water flow and effectively prevented salt diffusion. When tested with DI water as feed solution (FS) and 1 M NaCl as draw solution (DS), the ANBs incorporated sandwich-structured CNM achieved high water flux (158.0 L m−2 h−1) and ultralow reverse salt flux (0.4 g m−2 h−1) simultaneously, far beyond the state-of-the-art FO membranes. The PAN nanofibrous layer well protected the entrapped ANBs to allow a more durable FO performance. An ANBs-regulated nanofluidic flow model was proposed to elucidate selective water/salt transport mechanism. This work revealed the feasibility of ANBs incorporated membranes for osmosis-driven processes.
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The duration of antibodies against SARS-CoV-2 in Covid-19 patients remains uncertain. Longitudinal serological studies are needed to prevent disease and transmission of the virus.
In 2020, 414 blood ...samples were tested, obtained from 157 confirmed Covid-19 patients, in a prospective cohort study in Shanghai.
The seropositive rate of IgM peaked at 40.5% (17/42) within 1 month after illness onset and then declined. The seropositive rate of IgG was 90.6% (58/64) after 2 months, remained above 85% from 2 to 9 months and was 90.9% (40/44) after 9 months. Generalized estimating equations models suggested that IgM (P < 0.001) but not IgG significantly decreased over time. Age ≥ 40 years (adjusted odds ratio aOR 4.531; 95% confidence interval CI 1.879-10.932), and cigarette smoking (aOR 0.344; 95% CI 0.124-0.951) were associated with IgG, and age ≥ 40 years (aOR 2.820; 95% CI 1.579-5.036) was associated with IgM. After seroconversion, over 90% and 75.1% of subjects were estimated to remain IgG-positive 220 and 254 days, respectively. Of 1420 self-reported symptoms questionnaires, only 5% reported symptoms 9 months after onset.
In patients with a history of natural infection, anti-SARS-CoV-2 IgG is long-lived, being present for at least 9 months after illness onset. The long duration of natural immunity can mitigate and eliminate Covid-19 and the ongoing pandemic.
A fundamental aspect of marine benthic foraminiferal δ18O records of the last one million years is their “saw-tooth” pattern, characterized by gradual cooling to full glacial conditions followed by ...very rapid glacial terminations. Understanding the mechanism of this pattern is crucial for understanding ice age dynamics. We investigated the climatic trend within each glacial of the last 880 kyr by comparing the signal of the East Asian winter monsoon (EAWM) with global terrestrial and marine paleoclimate records. Our new grain size record from the Huining loess-paleosol section in the western Chinese Loess Plateau, together with published climate records from the Yimaguan and Luochuan sections in the central Chinese Loess Plateau, demonstrates a strengthening trend of the EAWM within most glacials, which largely mirrors the “saw-tooth” pattern of the benthic foraminiferal δ18O record. However, the EAWM record during Marine Isotope Stage (MIS) 8 shows an unusual weakening trend which is the exception over the last 880 kyr. Based on the linkages between Arctic ice sheets, the Siberian High Pressure system, and the EAWM, we propose that the weakening trend of the EAWM throughout MIS 8 reflects the overall shrinking of Arctic ice sheets towards the glacial termination, in contrast to the increasing trend of the benthic foraminiferal δ18O values. This conclusion is supported by a compilation of global paleoclimate records suggesting that MIS 8 was a unique glacial period over the last 900 kyr, characterized by a mild climate in middle to high northern latitudes and a cold climate in high southern latitudes, during late MIS 8. The inferred changes in Arctic ice sheets would alone cause a decreasing trend in benthic foraminiferal δ18O values during MIS 8, which is the opposite to the observed trend. We suggest that an increased ice volume in high southern latitudes led to the cooling of Antarctic Bottom Water and hence to a decrease in ocean bottom water temperature with an effect to increase benthic foraminiferal δ18O during MIS 8 as observed. Our results highlight the complexity of using the benthic δ18O signal alone as a paleoclimate proxy, and that MIS 8 is an important time window for better understanding glacial dynamics driven by changes in the polar regions of both hemispheres.
•Unusual weakening trend of the East Asian winter monsoon during MIS 8.•Weakening trend of the winter monsoon indicates the shrinking of Arctic ice sheets.•Opposite climate trends in the high latitudes of both hemispheres during MIS 8.•Southern Hemisphere forcing caused Antarctic cooling during MIS 8.
A modified multi-elevated-temperature post-IR infra-red stimulated luminescence (MET-pIRIR) protocol is proposed for dating young samples of Holocene age using K-feldspar. The protocol utilizes a ...five-step MET-pIRIR measurement with a moderate preheating of 200 °C for 60 s, and a narrow IR stimulation temperature increment of 30 °C (i.e., the five measurement temperatures are 50, 80, 110, 140 and 170 °C). Using this method, the residual doses of the MET-pIRIR signals are generally less than 1 Gy. Holocene aeolian samples from Northern China were tested using the 30°C-increment modified MET-pIRIR method. The results demonstrate that similar ages from 140 °C to 170 °C were obtained for our samples, which were consistent with the quartz optically stimulated luminescence (OSL) ages. Based on this observation, the measurement procedures are further simplified to a three-step pIRIR protocol. The first IR stimulation at elevated temperature (110 °C) is used to remove the fading affected signals. This is followed by two steps of IR stimulation at high temperatures (140 and 170 °C) for equivalent dose (De) measurement. Dating results consistent with the expected ages have been obtained at stimulation temperatures of 140 and 170 °C. It is suggested that the first IR stimulation can effectively remove the fading component. The three-step pIRIR method has minimized the experimental procedures, while keeping the age plateau test.
•A modified MET-pIRIR protocol is proposed for dating Holocene samples.•The method measures MET-pIRIR signal with low stimulation and preheating temperatures.•Residual doses are generally less than 1Gy using the new protocol.•The modified MET-pIRIR protocol is further simplified to a three-step pIRIR method.•These new methods are tested on Holocene aeolian samples from northern China.
In the above article <xref ref-type="bibr" rid="ref1">1 , <xref rid="table2" ref-type="table">Tables II , <xref rid="table3" ref-type="table">III , and <xref rid="table2" ref-type="table">V and <xref ...rid="fig1" ref-type="fig">Fig. 6 are incorrect. The correct images are provided below:
•A classification method was developed for syndromes in traditional Chinese medicine.•Symptoms are informative clues to the identification of different syndromes.•Graph convolutional network can ...provide enhanced features for symptoms.•Besides symptoms, state elements can contribute to TCM syndrome classification.
Traditional Chinese Medicine (TCM) diagnosis is a reasoning process through expert knowledge, in which syndrome classification is a key step for prescription recommendation and the treatment of patients. Doctors generally differentiate syndrome types according to patients’ symptoms and state elements. This paper proposes a syndrome classification method based on graph convolutional network with residual structure, to exploit the potential relationship between symptoms and state elements.
We constructed a graph convolutional network by combining symptoms and state elements for syndrome classification, called Symptoms-State elements Graph Convolutional Network (SSGCN), embedding the inherent logic of TCM diagnosis and treatment with a prescription graph. This graph architecture wherein contained the relationship between symptoms and state elements, and a multi-layer perceptron (MLP) was trained to classify different syndromes.
Experiments were conducted on two self-built datasets according to two classic TCM books, i.e., Theories on Febrile Diseases and Traditional Chinese Medicine Prescription Dictionary. Accuracy, precision, recall and F1-score were adopted to evaluate the syndrome classificaiton results. Our proposed SSGCN method achieved accuracy of 75.59%, 69.63%, precision of 69.10%, 76.33%, recall of 75.63%, 66.67% and F1-score of 71.26%, 65.84% in the above two datasets, respectively. The proposed method for syndrome classification outperformed several popular methods including support vector machine, random forest, extreme gradient boosting and convolutional neural network.
By constructing a prescription graph in which symptoms are used as nodes and state elements are taken into account for edges, graph convolution is implemted to capture the relationship of symptoms and state elements. This model improves the performance of syndrome classification and can be further extened for some other related applications in TCM.
By exploiting the uncharted chemical space around “hydrophobic channel” of the NNIBP, a series of novel DAPYs derivatives with benzyl acyl or sulfonyl-substituted methylenepiperidine were rationally ...designed, synthesized and evaluated for their inhibitory activity against HIV-1 in MT-4 cells. Among them, FS2 was identified as the most significant compound, which exhibited excellent activity against the HIV-1 wild-type and K103N mutant strains, which are superior to nevirapine and lamivudine.
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To further explore the chemical space surrounding the “hydrophobic channel” of the NNRTI binding pocket (NNIBP), a new series of diarylpyrimidines (DAPYs) were designed and synthesized as potent HIV-1 non-nucleoside RT inhibitors (NNRTIs). The target compounds were evaluated for anti-HIV potency in MT-4 cells. Most of the synthesized DAPYs exhibited moderate to excellent activity against the HIV-1 wild-type (WT) strain with EC50 values ranging from 16 nM to 0.722 µM. Interestingly, few compounds displayed remarkable activity in inhibiting K103N mutant virus with EC50 values ranging from 39 nM to 1.708 µM. Notably, FS2 (EC50(IIIB) = 16 nM, EC50(K103N) = 39 nM, SI = 294) was identified as the most significant compound, which was considerably more potent than nevirapine, lamivudine, and comparable to zidovudine. Additionally, the HIV-1 RT inhibition assay confirmed their binding target. Preliminary structure–activity relationships (SARs) and molecular modeling studies were also performed, providing significant suggestions for further optimization.
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