[en] To biomimic the spinning process of silkworm or spider, a capillary spinning equipment was applied to spin regenerated silk fibroin (RSF) fibers from RSF aqueous solutions in air. This equipment exhibits a wide processing window for various RSF aqueous solutions. The effects of pH, metal ions, RSF concentration and spinning parameters on the spinnability of the spinning dope and the mechanical properties of the obtained fibers were investigated. As a result, spinning dopes with a pH from 5.2 to 6.9 have good spinnability, especially for the dope with a pH of 6.0 and a Ca²⁺ concentration of 0.3 M. The RSF concentration of this dope ranges from 44% to 48%. Under optimized conditions of our dry spinning experiments (L/D, 133; take-up speed, 30 mm/s), the obtained as-spun fiber has a breaking strength of 46 MPa, which can be improved up to 359 MPa after a preliminary post-drawing in 80 vol.% ethanol aqueous solution. Highlights: → Regenerated silk fibroin fibers were prepared by using a dry spinning method. → Dope compositions affect dope spinnability. → Spinning parameters affect dope spinnability and fiber properties. → The breaking stress of the post-treated fiber was up to 359 MPa.

[en] Considering variation of environment temperature and unhomogeneity of background gravitational field, an improved correlation method was proposed to determine the variational period of a torsion pendulum with high precision. The result of processing experimental data shows that the uncertainty of determining the period with this method has been improved about twofolds than traditional correlation method, which is significant for the determination of gravitational constant with time-of-swing method.

[en] The field application of digital radiographic imaging in nuclear power can improve the efficiency and reliability of radiographic inspection. Based on the sensitivity requirements of RCCM standard image quality meter, this paper compares the inspection results of γ-ray digital ray and film photography on weld seam of nuclear power pipeline. At the same time, by introducing the unique advantages of the digital imaging system, the feasibility of the application of γ-ray digital imaging of pipeline weld and special workpiece in nuclear power field is analyzed. The results show that the IQI sensitivity of the γ-ray digital radiography for the pipeline weld in nuclear power can reach the level of film radiography, which is feasible to apply it to the nuclear power plant. Moreover, the special functions of the digital radiographic system can realize some special applications of nuclear power plant. (authors)

[en] Based on detailed analysis of the structure and key techniques of a virtual reality system, the applications of virtual reality to simulation in nuclear power plant (NPP) were developed. In order to meet the requirement of simulation in NPP, motion simulation of control rod drive system, walking system inside the containment and virtual main control room were presented. A simulator of NPP was connected to interchange dynamic data between virtual main control room and the simulator. The simulating results show that the technique of virtual reality can be applied well to the simulation inside containment, which is filled with activity material, and the simulation of virtual main control room, where human factors must be considered. It also can be used well to design virtual education and training system of NPP. (authors)

[en] Objective: To further explore the affinity of paclitaxel-loaded and trastuzumab (Herceptin) -targeted poly (lactic-co-glycolic acid, PLGA) -COOH ultrasound contrast agent (Pac-PLGA-HER) for human breast cancer cell line MCF-7 and study their effect on ultrasound imaging in vitro. Methods: Paclitaxel-loaded PLGA-COOH ultrasound contrast agents (Pac-PLGA) were prepared by the double emulsion technique and conjugated with Herceptin monoclonal antibody by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)/N-hyalroxysuccinimide (NHS). MCF-7 cells were plated in culture dishes for 24 h and divided into 4 groups with 3 dishes in each group, i. e. Pac-PLGA group, Pac-PLGA-HER group, ultrasound + Pac-PLGA-HER group and antibody blocking group. Binding of polymer ultrasound contrast agents to MCF-7 cells was observed by laser scanning confocal microscopy. In vitro experiments were employed to study the effects of Pac-PLGA-HER on the enhancement of ultrasound imaging as compared with Pac-PLGA, the control group. Independent samples t-test was used for statistical analysis with the help of DFY. Results: The average diameter of Pac-PLGA-HER was (596 ± 12) nm. In the in vitro targeting study,a number of Pac-PLGA-HER bound with MCF-7 cells tightly; while, no conjugation was observed in the control group. During in vitro ultrasound imaging,the average sound intensity of Pac-PLGA-HER and Pac-PLGA was (134.50 ± 10.19) and (135.11 ±11.49) dB (t=-0.097, P>0.05) and the average grey scale was 147.83 ± 11.12 and 148.50 ± 12.63 (t=-0.097, P>0.05), respectively. There was no difference between the two. Conclusion: Pac-PLGA-HER could bind to high HER2-expressing MCF-7 cells specifically and effectively and was an effective ultrasound contrast agent in vitro. (authors)

[en] Discharge vessel is an important equipment in the absorber sphere shutdown system of pebble-bed high-temperature gas-cooled reactor. The visualization pneumatic conveying test of the optimized fluidising discharge vessel was performed at ambient temperature and pressure by using glass balls instead of absorber sphere on a positive pressure system. Experimental results show that the performance of the optimized fluidizing discharge vessel is stable and reliable. With the increase of gas velocity from 8 m/s to 29 m/s, the flow rate of the glass sphere increases from 4.7 × 10⁴ min^-1 to 1.25 × 10⁵ min^-1 and then remains constant. The solid-gas mass flow ratio increases first and then decreases with the increase of gas velocity. The pressure drop of discharge vessel increases first and then decreases and then increases again with the increase of gas velocity. When the gas velocity is above 19 m/s, the process is a stable dilute-phase pneumatic conveying, in which the pressure drop of the vertical tube increases slowly. (authors)

[en] The additional pressure drop due to solids in the riser for the pneumatic conveying of the absorber spheres is investigated in the positive pressure transport system. The glass spheres are transported with the ambient air as the source gas. The air velocity at the riser inlet, u_g , is in the range of 15 m/s∼31 m/s. Experimental results show that the additional pressure drop per unit length due to solids in the riser first decreases from 2.7 kPa/m to 2.0 kPa/m and then increases to 2.3 kPa/m with the increase of U_g. The additional pressure drop coefficient due to solids in the riser, λ_z, first sharply decreases from 0.036 to 0.023 and then slowly decreases to remain at ∼0.016. The particle velocity correlation reported by Sankar et al and the solid friction coefficient correlations reported by Gari ć et al and Yang can be used in the engineering design when u_g is above 21 m/s. The ratio of the pressure from gas gravity, solids gravity, gas friction and solids friction to the riser total pressure drop is below 1%, about 11%∼18%, about 3%∼12% and about 75%, respectively. The appropriate increase the inner diameter of the riser and/or decrease the solid hold up is recommended to reduce the pressure drop from solids friction, which is the dominant part of the total pressure drop of the riser. (authors)

[en] Guiyu is known as one of the largest e-waste disposal and recycling sites in China, which suffers greatly from heavy metal pollution. By evaluating the concentrations and distribution of 21 metal elements with Principal Component Analyses (PCA), five principal components were identified, which accounted for 70.4% of the information of the initial data matrix, including one e-waste recycling source, two geological sources, one source of human activities and one ocean aerosol source. Among them, the source of human activities cannot be detailed only by PCA. By using Pb isotope, the unexplained source was judged as battery sludge. Combining 21 metallic and metalloid element datasets with Pb isotope concentrations is more accurate and effective to identify uncertain sources in soil.

[en] The falling process of small absorber ball in the drop-ball device of HTR absorber ball shutdown system has been studied in this paper. Glass ball with the identical dimension of the actual absorber ball diameter (Φ6 mm), and drop-ball device made of plexiglass tube with the identical inside diameter (Φ60 mm)of the actual absorber ball falling canal in the core have been applied. Experiments of glass ball falling due to gravity in the air environment have been accomplished. The calculation results coming from Beverloo empirical formula, which has been used to calculate mass flow rate of particle at orifice owing to gravity, agrees well with experimental results in this research with the deviation of 4% to 12%. The angle of repose of the measured glass ball in a ball storage vessels made of plexiglass is about 23°. Experimental results showed that glass ball in the vertically above center orifice firstly begin to flow, and then the circumambient particles supply to the orifice center in the ball storage vessels designed with the cone angle of the funnel. Glass balls gradually decline freely and smoothly from ball storage vessels. (authors)

[en] In this study, we introduce a tunable topological insulator (TI) system consisting of a hexagonal aluminum plate with rotatable droplet-shaped holes to produce topologically protected edge waves (TPEWs) along a topological interface. By rotating the round plate in the unit cells to break the unit cells’ mirror symmetry while preserving C3 symmetry, a new band gap is produced from the dispersion relations’ Dirac point. A topological protection state is generated at the interface due to the valley Hall effect. We also simulate different TPEWs along disparate interface routes and further prove their robustness, which means that they are immune to the vast majority of backscattering along interfaces. We also demonstrate that TPEWs at specific frequencies can be transported to different locations in hexagonal TIs, which is an innovative technique for precise control of acoustic guidance. This study provides a new method to modulate guide waves and energy accumulation of different frequency waves in topological systems. (paper)