COVID-19 had become a pandemic raising concerns of widespread panic and increasing anxiety and stress in individuals all over the world (
World Health Organization, 2020a
). Lots of countries had ...closed their schools. As the first country to do so, Chinese colleges and universities were making use of different modes of learning, including online-learning based on different platforms to achieve the goal suggested by Ministry of Education in China, “suspending classes without suspending learning,” since middle February. This paper is the first one which aims to investigate the anxiety of Chinese university students after the outbreak of COVID-19 right before the start of new spring term. 3611 university students (female: male = 1.48:1) aged between 18 to 24 from all over China were enrolled to this study from a top university in China. The Self-Rating Anxiety Scale – SAS (
Zung, 1971
) was used to assess anxiety 2 days before the start of new spring term in middle February. All four-year undergraduate students were included in the study. The mean SAS score was 40.53 (SD = 10.15), significantly higher than the national norm (Mean = 29.78, SD = 10.07, and
p
≤ .001), and there were still 557 (15.43%, Mean = 58.75, and SD = 8.9) students met the cutoff of 50 and were screened positive. Comparisons among sexes, grades and majors were also conducted. Significant differences were found between all males and all female (
p
≤ .001), and between all students majoring arts and sciences in the anxiety sample (
n
= 557,
p
= 0.05). The results also showed that the mean SAS scores were not correlated with the regions they came from/lived in. This study concluded that the Chinese university students showed higher anxiety for COVID-19.
Xenotransplantation is a promising strategy to alleviate the shortage of organs for human transplantation. In addition to the concerns about pig-to-human immunological compatibility, the risk of ...cross-species transmission of porcine endogenous retroviruses (PERVs) has impeded the clinical application of this approach. We previously demonstrated the feasibility of inactivating PERV activity in an immortalized pig cell line. We now confirm that PERVs infect human cells, and we observe the horizontal transfer of PERVs among human cells. Using CRISPR-Cas9, we inactivated all of the PERVs in a porcine primary cell line and generated PERV-inactivated pigs via somatic cell nuclear transfer. Our study highlights the value of PERV inactivation to prevent cross-species viral transmission and demonstrates the successful production of PERV-inactivated animals to address the safety concern in clinical xenotransplantation.
The South China Craton consists of the Yangtze and Cathaysia blocks that were welded together along the Jiangnan Fold Belt in the Neoproterozoic. The Neoproterozoic magmatism in the western and ...northern margins of the Yangtze Block is characterized by voluminous volcano-sedimentary strata, numerous felsic intrusions and many mafic-ultramafic plutons which provide a good opportunity to examine the geodynamics and tectonic evolution of the South China Craton during the assembly and breakup of Rodinia. Based on the geochronological and geochemical data, our study shows that the Neoproterozoic igneous rocks in the western and northern margins of the Yangtze Block were formed in subduction- and rift-related tectonic settings, respectively.
In the western margin of the Yangtze Block, the Neoproterozoic mafic and ultramafic rocks show arc-affinity trace elemental compositions that are indicative of mantle sources enriched by slab fluids. High-δ18O mafic rocks (850–780 Ma) were derived from mantle wedges that were modified by sediment melts, whereas low-δ18O mafic rocks (750–740 Ma) were formed by partial melting of mantle sources further enriched by altered oceanic crust melts. The widespread calc-alkaline I-type granitoids in this region, generated between 870 and 750 Ma, show negative to positive whole rock εNd (−4.9 to +4.8) and variable zircon εHf values (−1.9 to +10.6), similar to those of the contemporary mafic-ultramafic rocks, suggesting that they were produced by melting of the juvenile crust. The 780–750 Ma adakitic granitoids are characterized by high Sr/Y (19–318) and low Y (1.78–17.9 ppm) and have relatively constant εNd (−2.1 to +2.9) and εHf (+4.3 to +7.1) and mantle-like δ18O values (3.40‰ to 6.86‰), suggesting that they were partial melts of a subducted oceanic slab. These three types of igneous rocks demonstrate that the Neoproterozoic magmatism in the western margin of the Yangtze Block was controlled by a continuous subduction system.
However, Neoproterozoic magmatism in the South Qinling Belt at the northern margin of the Yangtze Block generated both arc- and rift-related igneous rocks. The arc-like mafic-ultramafic rocks are thought to have been derived from a subduction-modified lithospheric mantle source, whereas the MORB-affinity mafic rocks were probably sourced from an asthenosphere mantle. Associated Neoproterozoic granitoids were produced by melting of the juvenile mafic crust, except minor felsic rocks derived from the ancient basement. Widespread 800–700 Ma volcano-sedimentary sequences and 650 Ma mafic dike swarms suggest an extensional environment. Neoproterozoic magmatic zircons from felsic volcanic rocks and HP/UHP metamorphic rocks preserve low-δ18O values that were inherited from their protolith which underwent high temperature hydrothermal interaction in a rift setting. On the basis of these observations, the Neoproterozoic magmatism in the South Qinling Belt is proposed to have been controlled by a subduction-transform edge propagator (STEP) in relation to the continuous subduction system at the western margin of the Yangtze Block.
A mild, practical method for direct arylation of unactivated C(sp3)–H bonds with heteroarenes has been achieved via photochemistry. Selectfluor is used as a hydrogen atom transfer reagent under ...visible light irradiation. A diverse range of chemical feedstocks, such as alkanes, ketones, esters, and ethers, and complex molecules readily undergo intermolecular C(sp3)–C(sp2) bond formation. Moreover, a broad array of heteroarenes, including pharmaceutically useful scaffolds, can be alkylated effectively by the protocol presented here.
Primary liver cancer is the third leading cause of cancer-related death worldwide. Most patients are diagnosed at late stages with poor prognosis; thus, identification of modifiable risk factors for ...primary prevention of liver cancer is urgently needed. The well-established risk factors of liver cancer include chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), heavy alcohol consumption, metabolic diseases such as obesity and diabetes, and aflatoxin exposure. However, a large proportion of cancer cases worldwide cannot be explained by current known risk factors. Dietary factors have been suspected as important, but dietary aetiology of liver cancer remains poorly understood. In this review, we summarised and evaluated the observational studies of diet including single nutrients, food and food groups, as well as dietary patterns with the risk of developing liver cancer. Although there are large knowledge gaps between diet and liver cancer risk, current epidemiological evidence supports an important role of diet in liver cancer development. For example, exposure to aflatoxin, heavy alcohol drinking and possibly dairy product (not including yogurt) intake increase, while intake of coffee, fish and tea, light-to-moderate alcohol drinking and several healthy dietary patterns (e.g. Alternative Healthy Eating Index) may decrease liver cancer risk. Future studies with large sample size and accurate diet measurement are warranted and need to consider issues such as the possible aetiological heterogeneity between liver cancer subtypes, the influence of chronic HBV or HCV infection, the high-risk populations (e.g. cirrhosis) and a potential interplay with host gut microbiota or genetic variations.
Mesophilic alkaline serine proteases from various bacteria have been commercially applied in a range of industries owing to their high catalytic efficiency and wide substrate specificity. However, ...these proteases have an optimal catalytic temperature of approximately 50 °C, and their activity decreases significantly at low temperature. Therefore, to enhance their cold activity, it is necessary to improve the catalytic performance of these proteases at low temperature. The alkaline serine protease (DHAP) from Bacillus pumilus BA06 is a typical mesophilic enzyme, which has demonstrated great potential in various industrial applications. Here we attempted to improve the cold activity of DHAP via directed evolution.
Seven variants (P9S, A1G/K27Q, A38V, A116T, T162I, S182R, and T243S) of DHAP from B. pumilus were obtained via directed evolution. The results showed that all of the variants had increased proteolytic activity at 15 °C towards both the casein and synthetic peptide substrates. With the exception of variant T243S, the thermostability of these variants did not decrease in comparison with the wild-type enzyme. Kinetic analysis indicated that the increase in catalytic efficiency was largely attributed to the increase in turnover number (k
). Furthermore, the combined variants generated by site-directed mutagenesis showed a further increase in specific caseinolytic activity and the k
value for hydrolysis of the synthetic peptide. The combined variants of P9S/K27Q and P9S/T162I exhibited an approximate 5-fold increase in caseinolytic activity at 15 °C and almost no loss of thermostability. Finally, the possible mechanism responsible for the change in catalytic properties for these variants was interpreted based on structural modeling.
Directed evolution and site-directed mutagenesis were combined to engineer variants of the DHAP from B. pumilus. All of the variants exhibited an increase in hydrolytic efficiency at low temperature towards both of the substrates, casein and synthetic peptide, without any loss of thermostability compared with the wild-type. These data suggest that engineering low-temperature activity for a bacterial protease is not always associated with the loss of thermostability. Furthermore, our findings demonstrate that enhanced cold activity and thermostability could be integrated into a single variant.
Curcumin has exhibited a protective effect against development of renal fibrosis in animal models, however, its underlying molecular mechanisms are largely unclear. Therefore, we investigated the ...anti-fibrosis effects of curcumin in transforming growth factor-β1 (TGF-β1)-induced epithelial-to-mesenchymal transition (EMT), and the mechanism by which it mediates the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Human kidney tubular epithelial cells (HKCs) were treated with TGF-β1 or curcumin alone, or TGF-β1 in combination with curcumin. The effect of curcumin on cell proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Expression of E-cadherin, cytokeratin, vimentin, alpha smooth muscle actin (α-SMA), fibroblast-specific protein 1 (FSP1) and key proteins of Akt/mammalian target of rapamycin (mTOR) pathway were analyzed by immunocytochemistry, real-time PCR and Western blot. Low dose curcumin (3.125 and 25 µmol/L) effectively promoted HKC proliferation. When HKCs were co-incubated with TGF-β1 and curcumin for 72 h, curcumin maintained the epithelial morphology in a dose-dependent manner, decreased expression of vimentin, α-SMA and FSP1 normally induced by TGF-β1, and increased expression of E-cadherin, cytokeratin. Importantly, we found that curcumin reduced Akt, mTOR and P70S6K phosphorylation, effectively suppressing the activity of the Akt/mTOR pathway in HKCs. Curcumin also promoted HKC proliferation, and antagonized TGF-β1-driven EMT through the inhibition of Akt/mTOR pathway activity, which may suggest an alternative therapy for renal fibrosis.
•Carboxylated cellulose nanocrystal (CCN)-sodium alginate hydrogel beads were prepared.•CCN-Alg beads were used for Pb(II) adsorption from aqueous solution.•This adsorbent is efficient, recyclable, ...and environmentally friendly.•Experimental data were fitted to kinetic, thermodynamic, and isotherm models.
Carboxylated cellulose nanocrystal-sodium alginate (CCN-Alg) hydrogel beads were easily prepared through a cross-linking method. The structure and properties of the composite beads were characterized by TEM, FTIR, SEM, XPS, thermogravimetric analysis (TGA), and zeta potential measurement. A high ratio of 76% of the Pb(II) ion was adsorbed within the first 2h, and the adsorption equilibrium was nearly reached after 3h. The experimental isotherm could be fitted by the Langmuir model, yielding an extreme adsorption capacity of 338.98mgg−1. The adsorption process followed a pseudo-second-order kinetic model, and thermodynamic analyses confirmed that the adsorption is a spontaneous and endothermic process. Regeneration tests with acid treatment indicated that the CCN-Alg beads performed well in repeated Pb(II) adsorptions, as they could maintain an adsorption capacity of 223.2mgg−1 after five repeated cycles. These results indicate that these CCN-Alg beads are a potentially effective and sustainable adsorbent for application in wastewater treatment.
•A parallel batch scheduling problem with non-identical capacities is considered.•The objective of scheduling is to minimize the total completion time.•A modified elite ant system algorithm with the ...local search is proposed.
This paper considers the problem of scheduling a group of jobs with arbitrary release times, non-identical sizes, and different processing times on non-identical parallel batch processing machines to minimize the total completion time. A mixed-integer programming (MIP) model is firstly constructed in this paper to solve this problem. Then since the studied problem is strongly NP-hard, a modified elite ant system algorithm with the local search (MEASL) is also proposed to solve it, which is compared with several meta-heuristic algorithms and the commercial optimization solver (Gurobi) through extensive simulation experiments. Finally, the experimental results verify the effectiveness of the proposed algorithm.
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