[en] Highlights: • The slope of P_m_a_x versus U_r_m_s is greater for nano-Al powder than for micro-Al powder. • The u_e_f_f_,_m_a_x of micro-Al and nano-Al powder-air mixtures increases linearly with U_r_m_s. • For micro- and nano-Al powders, u_e_f_f_, _m_a_x increases as the percentage of nano-Al increases. - Abstract: The environmental turbulence intensity has a significant influence on the explosion parameters of both micro- and nano-Al at the time of ignition. However, explosion research on turbulence intensity with respect to micro- and nano-Al powders is still insufficient. In this work, micro- and nano-aluminum powders were investigated via scanning electron microscopy (SEM), and their particle size distributions were measured using a laser diffraction analyzer under dispersing air pressures of 0.4, 0.6, and 0.8 MPa in a 20 L cylindrical, strong plexiglass vessel. The particle size distributions in three different mass ratio mixtures of micro- and nano-Al powders (micro-Al:nano-Al_[_m_a_s_s_r_a_t_i_o_] = 95:5, 90:10, and 85:15) were also measured. The results show that the agglomerate size of nano-Al powder is an order of magnitude larger than the nanoparticles’ actual size. Furthermore, the turbulence intensity ranges (U_r_m_s) of the Al powder-air mixtures were measured using particle image velocimetry (PIV) under dispersing air pressures of 0.4, 0.6, and 0.8 MPa. The effect of turbulence intensity on the explosion characteristics of the micro- and nano-Al powders was investigated using a 20 L cylindrical explosion vessel. The results of micro-Al and nano-Al powder-air mixtures with a stoichiometric concentration of 337.00 g·m"−"3 were discussed for the maximum explosion pressure, the maximum rate of pressure increase and the maximum effective burning velocity under the different turbulence intensity.

[en] Objective: To explore the diagnostic value of dual-phase contrast enhancement CT combined with virtual non-enhanced images by dual-energy CT in clear cell renal cell carcinoma. Methods: Sixty patients who were suspected of clear cell renal cell carcinoma underwent non-enhanced CT and contrast enhancement CT of early interface-phase between cortex -medulla and parenchymal phase on a dual-energy CT. The true non-enhanced kidney CT (TNCT) was performed in a single-energy acquisition mode, but the dual-phase contrast enhancement CT were performed in a dual-energy mode of 80 kV and 140 kV respectively. The virtual non-enhanced CT (VNCT) images were derived from the data of early interface phase using liver virtual non-contrast software. The diagnose according to VNCT combined dual-phase contrast enhancement CT and dual-phase contrast enhancement CT only were made respectively and compared with χ"2 test. Between the true non-contrast CT and the virtual non-contrast CT, the image quality was compared with Wilcoxon test; The radiation dose of volume CT dose index (CTDIvol) and dose length product(DLP) in a single-phase and total examination, the mean CT HU values of the tumours were compared with t test. Results: The accuracy of VNCT combined dual-phase contrast enhancement CT was higher than that of dual-phase contrast enhancement CT only [93.3% (56/60) vs.78.3% (47/60); χ"2=5.6, P<0.05]. The detective ability (score) of VNCT was near to that of TNCT and the difference was not obvious (Z=0.00, P>0.05). The radiation dose of volume CT dose index (CTDIvol) and dose length product (DLP) in a single phase and total examination of VNCT [(8.85 ± 1.28) mGy, (196.45 ±21.12) mGy·cm, (17.69±2.35) mGy, (392.90±42.25) mGy · cm] were lower than that of TNCT [(10.20 ± 1.44) mGy,(218.29 ± 29.60) mGy · cm, (30.61 ± 3.27) mGy and (654.86 ± 88.81) mGy ·cm], t=4.21, 3.58, 23.63, 16.12 respectively, P<0.05. The mean CT HU values of tumours on VNCT images was higher than that on TNCT images and the difference was significant [(39.37 ± 6.35) vs.(34.94 ± 7.00)HU, t=-14.39, P<0.05]. Conclusions: The diagnostic value of dual-phase contrast enhancement CT combined virtual non-enhanced CT by dual-energy CT for clear cell renal cell carcinoma was obvious, most tumours can be diagnosed correctly, and the radiate dose can be decreased obviously, the normal single-energy non-enhanced and contrast enhancement CT might be replaced in the future. (authors)

[en] In order to study seismic response of the landslide with micropiles, shaking table tests were performed on two landslide models (i.e., micropiles-reinforced landslide and unreinforced landslide). El Centro waves, Wenchuan waves, Kobe waves and sinusoidal waves were applied to the model. A comparison was made on the acceleration response between reinforced landslide and unreinforced landslide. Furthermore, the residual bending moment of micropile was analyzed. The results indicate that micropiles have a good seismic performance for landslide, and it can suppress the seismic waves that propagated to landslide. Under the same seismic wave, the acceleration response of reinforced landslide is smaller than that of unreinforced, especially in the toe of landslide. The residual bending moment of micropiles shows reverse “S”-type. The maximum residual bending moment of micropile mainly distribute in 3.7 times pile diameter above the sliding surface and 1.4 times pile diameter below the sliding surface. (paper)

[en] Highlights: • The features of a three-dimensional CLPHP charged with deionized water and surfactant are probed. • The effects of initial pressure and surfactant concentration on heat transfer performance are investigated. • Suitable combination of surfactant concentration and heat load can improve heat transfer performance. • Surfactant can improve the wettability of the tube wall and effectively prevent the occurrence of “dry-out”. -- Abstract: A three-dimensional closed-loop pulsating heat pipe (CLPHP) charged with deionized water and surfactant is numerically investigated in present work. The surfactant used in present work is hexadecyl trimethyl ammonium chloride (CTAC). The start-up performance and heat transfer characteristics of CLPHP with deionized water and surfactant are compared by changing the initial pressure (0.1 MPa, 0.07 MPa, 0.05 MPa) and input heat load (10 W, 20 W, 30 W, 40 W). It’s found that the performance of CLPHP is affected by the initial pressure, surfactant concentration and input heat load jointly. Under the condition of high initial pressure, the performance of CLPHP with surfactant is not as good as that with deionized water. However, under the condition of low initial pressure, especially at higher input heat load, the superiority of the surfactant begins to appear. Compared with the CLPHP with deionized water, the thermal resistance could be decreased by 4.78% when the initial pressure, the input heat load and the surfactant concentration is 0.05 MPa, 40 W and 50 ppm, respectively. It is also found that the CLPHP with 2000 ppm CTAC has a much lower heat transfer performance than that with deionized water under any conditions. Finally, surfactant can improve the wettability of the CLPHP wall, reduce the contact angle, and absolutely prevent the occurrence of “dry-out”.

[en] Highlights: • A new thermodynamic cycle is proposed and analyzed. • The proposed cycle can achieve the function of CCHP by a thermodynamic cycle. • The effects of various cycle layouts on the thermodynamic performance are probed. • The performances of various cycle layouts at different temperatures are compared. • A three-dimensional optimization model is established by the Pareto method. A new thermodynamic cycle is proposed for the utilization of medium–low grade heat energy. The feasibility investigation is conducted for various horizontal ‘8’ cycles (named after the shape of cycle in T-s diagram). The thermodynamic analyses based on the combination of single-pressure Organic Rankine Cycle (horizontal ‘8’ SPORC) and double-pressure Organic Rankine Cycle (horizontal ‘8’ DPORC) are performed. Furthermore, the Pareto method is used to optimize the horizontal ‘8’ SPORC and horizontal ‘8’ DPORC. The horizontal ‘8’ SPORC and horizontal ‘8’ DPORC are compared for various objectives under different heat source temperatures. The results indicate that the proposed cycle is feasible and can realize refrigerating, heating, and power output simultaneously. When objective of proposed cycle is to obtain power output, horizontal ‘8’ SPORC has an advantage at all heat source temperatures, especially when the heat source temperature is over 170℃, the advantage becomes progressively remarkable. When objective is optimal comprehensive performance, for net output power, the horizontal ‘8’ SPORC is more advantageous at heat source temperatures below 180℃, but the advantage decreases with the raise of the heat source temperature. For refrigerating and heating performances, horizontal ‘8’ DPORC is more advantageous when the heat source temperature is below 190℃, but the advantage decreases with the raise of heat source temperature.

[en] Highlights: • The injection temperature and variation of production temperature are considered. • The thermodynamic performance of DPORC with different layouts are compared. • Heat distribution between HP and LP cycles determines the system performance. In the utilization of hot dry rock geothermal energy, the temperature of production well varies with the injection temperature of the recharge well and operation time. Taking into account of the variation of production well temperature, three kinds of double-pressure Organic Rankine Cycle (DPORC) with different layouts are constructed in present work, and the effects of different layouts on the thermodynamic performance of DPORC are probed. The results indicate that present DPORCs can effectively improve the thermodynamic performance of the system, and the net output power of the systems can be improved by at least 5.68%, 6.42% and 15.75%, compared with those of single-pressure Organic Rankine Cycle (SPORC). In addition, one of proposed DPORCs can reduces the irreversible loss in system and has better thermodynamic performance. When the injection temperature of the recharge well remains constant, the net output power, thermal efficiency and exergy efficiency reach maximum at the same k (the ratio of absorbed heat in high-pressure stage cycle to that in DPORC). After 40 years of operation, the net output power of the three arrangements and SPORC decrease by 434.07 kW, 438.04 kW, 463.94 kW and 465.72 kW, respectively. Therefore, it’s significant to reduce the temperature drop of hot dry rock production well to maintain the stable output of the system. It’s found that the exergy loss in system is mainly concentrated in evaporator, condenser and turbine. Reasonable layout can reduce the exergy loss of the system. The variation trend of cycle perfection with k is the same as other parameters do, and the maximum cycle perfection is achieved when the net output power of system is near the maximum. With the increase of running time, the cycle perfection of DPORC increases slightly. Specifically, the cycle perfection of one proposed DPORC rises in a wavy manner.

[en] Highlights: • Heat transfer characteristics were tested when sands with clay minerals. • Heat transfer characteristics were tested in different injected water temperature. • Then influence of clay mineral content on heat transfer characteristics was analyzed. -- Abstract: In this paper, a one-dimensional sand column experiment system was set up to study the heat transfer characteristics of brine aquifer, and the effective thermal diffusivity was calculated. In the conditions of different injected water temperatures and water head differences when the sand samples contained different kind of clay minerals and different contents, the temperature in sand column were tested. Based on the temperature change with time, the effective thermal diffusivities were obtained, also the function relationship between thermal diffusivity and injected temperature was obtained. Results indicate that the composition and content of clay minerals have the largest effect on the heat transfer performance of brine aquifer, followed by the temperature of injected water and the injected water head difference. For the three tested clay minerals, montmorillonite has the greatest influence on the heat transfer characteristics and the effective thermal diffusivity in the aquifer.

[en] Objective: To detect the best phase and best tube voltage for the diagnosis of small (diameter ≤ 3 cm) clear cell renal cell carcinoma with dual-energy dual-phase CT. Methods: Image manifestations of 27 patients with small (diameter ≤ 3 cm) ccRCCs confirmed by pathology were retrospectively analyzed. All subjects underwent dual-energy biphase (early corticomedullary and delayed phase) scan preoperatively. Two senior radiologists analyzed the images in consensus. The definition of images in different phases and with different tube voltage was classified into 4 levels and was compared by Wilcoxon and Friedman test. The attenuation of the lesions and the adjacent renal parenchyma, the SD value of the anterior abdomen fat were measured. The contrast noise ratio(CNR), lesion kidney ratio(LKR) and the early corticomedullary phase and delayed phase value were calculated. They were all compared with one-way ANOVA. Results: The score of definition of lesions in early corticomedullary phase at 80 kV, 140 kV and average-weighted 120 kV were 3.30 ± 0.87, 2.81 ± 0.92 and 3.11 ± 0.85, respectively, which in delayed phase were 3. 70 ±0. 54,3. 30 ±0. 82 and 3. 52 ±0. 64, respectively. Definition of lesions was better in delayed phase than that in early corticomedullary phase (Z = -2.296, -2.446 and -2.392, respectively; P < 0.05). Either in early corticomedullary phase or in delayed phase, CT value, noise value and CNR were the highest on 80 kV images, which were(302 ± 80) HU, (16.2 ± 2.2) and (4.1 ± 3.4) in corticomedullary phase and (152 ± 31) HU, (16.4 ± 2.7) HU, and (4.7 ± 1.7) in delayed phase. The change of lesion attenuation between early corticomedullary phase and delayed phase on 80 kV, 140 kV and average-weighted 120 kV images were (150 ± 76), (72 ± 33) and (96 ± 46) HU, respectively. There was significant difference among the three groups (F = 4.541, P < 0.01). Conclusions: Delayed phase scan is in favor of small clear cell renal cell carcinoma display. 80 kV images are the best for detecting and qualitation of small clear cell renal cell carcinoma when compared with 140 kV and the average-weighted 120 kV images. (authors)

[en] Electro-deposition is a smart, safe and efficient method for biomaterial manufacturing. Collagen, a functional protein with excellent biocompatibility and biosafety, is a promising candidate for tissue engineering and biomedical applications. However, there are few reports on electro-deposition of biomaterials using collagen without electrically or magnetically active nanoparticles. In this study, electro-deposition was employed to swiftly fabricate tube-like collagen–chitosan hydrogels in a mild environment. Fourier transform infrared spectroscopy was employed to analyze the ingredients of the tube-like hydrogels. The result showed that the hydrogels contained both collagen and chitosan. The distribution and content of collagen in the hydrogels was further measured by hematoxylin–eosin staining and hydroxyproline titration. Collagen was distributed homogeneously and its content was related to the initial collagen:chitosan ratio. The tension resistance of the composite gels and the thermal stability of collagen in the composites were obviously enhanced by the chitosan doping. Meanwhile, the tube-like hydrogels retained a good ability to promote cell proliferation of collagen. This method offers a convenient approach to the design and fabrication of collagen-based materials, which could effectively retain the bioactivity and biosafety of collagen and furnish a new way to enhance the stability of collagen and the tensile strength of collagen-based materials. (paper)

[en] Although nickel–titanium (NiTi) alloys have many excellent material properties, micro structures of NiTi alloys are rarely machined by conventional mechanical machining due to its high elasticity and severe tool wear. A micro tube as an active catheter with typical driving structures made from a NiTi shape memory alloy (SMA) is a key part in an interventional micro robot system. The driving structures, as complex 3D micro structures pierced through the thin-walled micro tube, are mainly fabricated by a lithography-based process at present. However, not only is the process inefficient and costly, but its etching depth is also limited. In this research, a novel process of 3D servo scanning micro electro discharge machining (EDM) with the movement of two-axis linkage and one-axis servo is proposed for efficiently machining 3D micro structures. The processing procedures are presented, including 3D model design, scanning paths planning, 3D NC codes generation and 3D micro EDM. The emphasis is focused on the methods for planning the scanning paths and generating the CNC codes considering the special 3D micro structures. By using the planned complementary scanning paths, the processing stability is improved for successfully machining the typical driving structures within 5 h. The machining experiments verify the feasibility of the proposed process and related methods. (paper)