Background and aimsPrevious research has established risk factors for problematic smartphone use (PSU), but few studies to date have explored the structure of PSU symptoms. This study capitalizes on network analysis to identify the core symptoms of PSU in a large sample of students.MethodsThis research investigated 26,950 grade 4 students (male = 13,271) and 11,687 grade 8 students (male = 5,739) using the smartphone addiction proneness scale (SAPS). The collected data were analyzed using a network analysis method, which can provide centrality indexes to determine the core symptoms of PSU. The two networks from the different groups were compared using a permutation test.ResultsThe results indicated that the core symptoms of students' problematic smartphone use were the loss of control and continued excessive use across the two samples.Discussion and conclusionsThese findings suggest that loss of control is a key feature of problematic smartphone use. The results also provide some evidence relevant to previous research from the perspective of network analysis and some suggestions for future treatment or prevention of students' problematic smartphone use.

To address Superpave graded and AC graded asphalt mixture, bending test at low temperature and thermal stress restrained sample tests are used respectively to evaluate the low temperature performance of asphalt mixture. Meanwhile, contrast analysis of the two test methods and the low temperature performance of two asphalt mixture are studied, too. The results show that Superpave method can effectively improve low temperature perfomance of asphalt mixture. In the thermal stress restrained sample tests, freezing temperature and transition point temperature can evaluate the low temperature cracking resistance of Superpave asphalt mixture well. In bending test at low temperature, bending strain energy density should be considered as evaluation index to the characterization for low temperature performance of asphalt mixture. That also closely meets the result of the rmal stress restrained sample tests.

The project logistics indicators system of risk evaluation is established through analyzing the project logistics risk characteristics. Risk evaluation model is proposed based on matter-element theory.The project logistics risk、evaluation index and the characteristic value are taken as the matter-element. The logistics risk grade can be gained by calculating the risk coefficient of correlation, using subjective and objective combination weighting methods and the integrated risk correlation calculating in the end. An example is used to validate the proposed method. The results show this model can solve the problem of uncertainty index and the risk quantitative analysis then risk decision can be made.

This article studies the low-temperature anti-cracking properties of plain asphalt mixtures and rubber-modified asphalt mixtures at different aging condition. Laboratory flexural test was conducted on the beam specimens of plain asphalt mixtures and rubber-modified asphalt mixtures. Experiment results indicate that rubber-modified asphalt mixtures have superior low-temperature anti-cracking performance than that of plain asphalt mixtures. Compared with the short term oven aging test, the long term oven aging test has more significant effect on the low-temperature anti-cracking of the mixture. In order to better represent the low-temperature anti-cracking of in-service aging asphalt pavement, the long term oven aging test should be used to appraise the low-temperature anti-cracking of asphalt pavements in china.

This study aimed to investigate the inhibitory effects of the different concentrations of Tanshinone IIA (Tan IIA) on the proliferation of human alveolar epithelial cell line A549 and its regulatory mechanism in epithelial-mesenchymal transition (EMT). The proliferation activity of cells was examined using the thiazolyl blue tetrazolium bromide (MTT) method. The changes in the expression of epithelial cell marker protein E-cadherin (E-cad) and interstitial marker protein alpha-smooth muscle actin (α-SMA) were detected using the cellular immunochemical method. The changes in cell morphology and ultrastructure were observed under the inverted microscope and transmission electron microscope, respectively. Western blot analysis was used to detect the expression of E-cad, α-SMA, Smad7, and Smad3. The MTT assay showed that the cell viability in the transforming growth factor beta 1 (TGF-β1) induced group was higher than that in the normal group, but the difference was not obvious. However, the cell viability of the Tan IIA-treated groups obviously decreased compared with the TGF-β1-induced and normal groups. Meanwhile, the expression of E-cad and Smad7 decreased, and the expression of α-SMA and Smad3 increased after A549 cells were induced by 5 ng/mL TGF-β1 for 24 h. However, their expression levels were close to the expression level of the control group after the cells were treated with Tan IIA for 24 h. In conclusion, the results demonstrated that Tan IIA could inhibit EMT of alveolar epithelial cells induced by TGF-β1, probably by regulating the expression of TGF-β/Smad pathway protein. Therefore, Tan IIA might serve as a potential anti-fibrosis drug in treating pulmonary fibrosis.