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[en] On July 4, 2006, a MS5.1 earthquake occurred in Wen’an county of Hebei Province of which the epicenter is near the Beijing city. The six geoelectric field monitoring stations have been in operation for several years around the Beijing area to examine the relationship between electric field changes and earthquake. This paper firstly explains the principle of the eliminating noise method by using multi-dipole observation system of the geoelectric field. Then the data observed at the stations are studied and a lot of abnormal signals preceding the Wen’an earthquake are selected, of which five abnormal signals of the geoelectric field are finally recognized as the precursory signals. The result shows that ➀ there probably exists the precursory signals of the geoelectric field preceding the Wen’an earthquake; ➁ there are sensitive sites in the spatial distribution of the abnormal variation of the geoelectric field before the quack; ➂ the anomalous signals do not appear synchronously, and their durations are not same at different stations; ➃ the amplitudes of the abnormal signals recorded at Baodi station are small, but large at Changli station, while the latter is farther from the epicentral area than the former.
[en] LAG3 is a surface molecule found on a subset of immune cells. The precise function of LAG3 appears to be context-dependent. In this study, we investigated the effect of LAG3 on CD4+CD25- T cells from non-small cell lung cancer (NSCLC) patients. We found that in the peripheral blood mononuclear cells of NSCLC patients, LAG3 was significantly increased in CD4+ T cells directly ex vivo and primarily in the CD4+CD25- fraction, which was regulated by prolonged TCR stimulation and the presence of IL-27. TCR stimulation also increased CD25 expression, but not Foxp3 expression, in LAG3-expressing CD4+CD25- cells Compared to LAG3-nonexpressing CD4+CD25- cells, LAG3-expressing CD4+CD25- cells presented significantly higher levels of PD1 and TIM3, two inhibitory receptors best described in exhausted CD8+ T effector cells. LAG3-expressing CD4+CD25- cells also presented impaired proliferation compared with LAG3-nonexpressing CD4+CD25- cells but could be partially rescued by inhibiting both PD1 and TIM3. Interestingly, CD8+ T cells co-incubated with LAG3-expressing CD4+CD25- cells at equal cell numbers demonstrated significantly lower proliferation than CD8+ T cells incubated alone. Co-culture with CD8+ T cell and LAG3-expressing CD4+CD25- T cell also upregulated soluble IL-10 level in the supernatant, of which the concentration was positively correlated with the number of LAG3-expressing CD4+CD25- T cells. In addition, we found that LAG3-expressing CD4+CD25- T cells infiltrated the resected tumors and were present at higher frequencies of in metastases than in primary tumors. Taken together, these data suggest that LAG3-expressing CD4+CD25- T cells represent another regulatory immune cell type with potential to interfere with anti-tumor immunity.
[en] Objective: To compare dual-energy subtraction (DES) and conventional digital chest radiography (DCR). Methods: 200 patients with chest trauma or lung diseases were examined by DES DCR in the posterior anterior projection. The conventional DCR, bone, and soft tissue images were also obtained and compared with those of DES DCR. Results: Of 600 DES images obtained on the 200 patients, there were more rib fractures (59 patients), pneumonia (38), pulmonary tuberculosis (24) and small lung nodules (54) detected than conventional DCR (47, 38, 24, 50). Conclusion: DES is more sensitive to rib fracture and lung diseases than conventional DCR. (authors)
[en] Cylinder-shaped Cu80 Ni20 alloy melt is undercooled and solidified by the combination of the electromagnetic levitation technique and the flux treatment method. Nearly constant temperature gradient of 8-10K/cm is realized for the cylindrical melts with different undercooling levels at the bottom ends. The experimental results reveal that with the increase of the undercooling of the melts from 35 to 220K, the microstructures undergo transition from coarse dendrites to granular grains, unidirectional dendrites, and finally to equiaxed grains
[en] Pb(Zr0.52Ti0.48)O3 nanocrystals were synthesized by a hydrothermal method. The poly(vinyl pyrrolidone) (PVP) was used as the surfactant to control growth of the Pb(Zr0.52Ti0.48)O3 nanocrystals. The effect of PVP concentration, reaction temperature and time on morphologies and crystallinity of Pb(Zr0.52Ti0.48)O3 nanocrystals were investigated. The tetragonal PbZr0.52Ti0.48O3 grains were obtained, as they were prepared at 200 °C for 4 h with PVP concentration from 0.1 to 10.0 g/L. With increasing the PVP concentration from 0.1 to 10.0 g/L, the size of PbZr0.52Ti0.48O3 grains decreased. When the PbZr0.52Ti0.48O3 grains were prepared at 200 °C for 12 h with PVP concentration of 6.0 g/L, the PbZr0.52Ti0.48O3 nanocrystals with average diameter of 30 nm were formed.
[en] Highly arsenic-doped Si-on-insulator (SOI) substrate incorporated with buried MoSi2 layers is fabricated aiming at decreasing the collector series resistance of SiGe heterojunction bipolar transistors (HBTs) on SOI, thereby enhancing cutoff frequency (fT) performance and increasing the maximum value of fT (fTMAX). The fT performance at medium current is enhanced and current required for fT = 15 GHz is reduced by half. The value of fTMAX is improved by 30%
[en] Highlights: • The model considering contact angle for a thermosyphon is developed. • The model with contact angle has lower relative error than without contact angle. • Mechanism of the effect of evaporator wettability on heat performance is discussed. • Mechanism of the effect of filling ratio on heat performance is discussed. • Heat performance is best at filling ratios of 20–30% for hydrophilic evaporator. - Abstract: A thermosyphon is considered an efficient heat dissipation device in engineering fields due to its low thermal resistance. The heat transfer mechanisms for thermosyphons at different evaporator wettability and filling ratios are not well detailed. A model considering evaporator wettability in terms of a contact angle is developed to detail the phase change process to explore the heat transfer mechanism for a thermosyphon in this study. The effects of evaporator wettability and filling ratio on the heat performances of a thermosyphon charged with water are investigated. It is observed that the simulated absolute temperatures with a contact angle are in better agreement with the experimental results with an average relative error of 0.15% than the simulation results without a contact angle (0.28%). The results show that a hydrophilic surface causes bubbles to easily depart the evaporator wall, thereby increasing the heat performance, whereas a hydrophobic surface causes bubbles to adhere to the evaporator wall, decreasing the heat performance. Further study shows that a low filling ratio of 12% will result in drying out, but a high filling ratio of 40% will prevent large bubbles from reaching the liquid surface, thereby decreasing the heat performance. The heat performance is best at filling ratios of 20–30% for an evaporator with a hydrophilic surface.
[en] Poly (para-phenylene terephthamide) PPTA-based specialty paper suffers from limited mechanical and electrical insulation properties due to weak interfacial interactions between chemically inert PPTA microfibers. Herein, in order to activate the fiber surface, PPTA nanofibers were prepared through DMSO/KOH deprotonation process. Whereafter, a composite paper with reinforced concrete structure was constructed by combining PPTA microfibers and PPTA nanofibers through vacuum-assisted filtration process. The results show that the composite paper has a high mechanical strength of ~ 84.8 MPa, high Young’s modulus of ∼ 2.4 GPa, and elongation at break of ∼ 7%. Meanwhile, the Weibull distribution model predicts the dielectric breakdown strength of composite paper as high as 74.4 kV/mm. In addition, the composite paper also exhibited high-temperature resistance and UV resistance, indicating great advantages for operating under high temperature and electrical insulation conditions.
[en] A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress–strain relationship is first measured under conditions of uniaxial compression with additional lateral stress and strain, then the elastic modulus of the material is determined by the linear fitting method. It is found that the modulus is positively correlated to the grain size and negatively correlated to the container size. Arching and dragging are revealed to be the mechanism of such correlations by using the digital image correlation method and the pressure film technology based on the statistical method. (paper)
[en] Graphitic carbon nitride quantum dots (g-CNQDs) are rarely used in the field of electrochemiluminescence. In this paper, g-CNQDs have a strong and stable electrochemiluminescence (ECL) signal generated in the presence of co-reactant K_2S_2O_8. The ECL signal of g-CNQDs was quenched by the mechanism of resonance energy transfer (RET) between donor g-CNQDs and receptor riboflavin (RF) that is proved by UV-vis absorption spectroscopy, electrochemiluminescence and fluorescence emission spectroscopy analysis technology. Therefore, we achieved detection of the riboflavin content in the drug tablets of vitamin B_2 using ECL and FL. The determination results of ECL showed that the riboflavin content of the drug vitamin B_2 (VB_2) tablets was consistent with the fluorescence (FL) analysis, with wider linear range of 0.02–11 μM and lower minimum detection limit of 0.63 nM (S/N = 3) than FL. Hence, the riboflavin content in human serum was further detected using ECL. The relative standard deviation is less than 6.5%, with an acceptable recovery of 95.33%–104.22%, which means that this sensor has potential applications in the actual sample analysis. As a new ECL luminary, g-CNQDs have opened a new field for the development and application of ECL sensor. - Highlights: • G-CNQDs proposed as a new luminophore for ECL. • ECL signal was strong and stable in the presence of co-reactant K_2S_2O_8. • Based on the resonance energy transfer between g-CNQDs and riboflavin. • ECL has wider linear range and lower detection limit than FL.