Abstract: Based on the fracture mechanics, a finite element model of plane strain is employed to make a comparison analysis on the stress and strain field of reflective crack tip under the impacts of wheel load and thermal load of two different kinds of asphalt overlay—one overlay is set with stress absorption interlayer and the other is not. Results show that, under the impact of wheel load, the most unfavorable load position of reflective crack tip is 15cm of load center line away from the crack tip level. Under the effect of wheel load and thermal load, the stress and strain field of reflective crack tip has been greatly improved after setting the stress absorption interlayer and the stress intensity factor K and J-integral decrease obviously, which show that stress absorption interlayer plays a good role in anti-crack.
Abstract: Microwave absorbing material is currently being more and more widely applied in the world. However, conventional absorbent coating material cannot fulfill the complex current requirements of science and technology to have a wide absorption frequency band, and high absorption. This paper describes composite material plates with a multi-layer absorbing structure designed according to impedance-matching and attenuation principles, producing two- and three-layer absorbing structures. Twelve samples were made, containing graphite powder and manganese dioxide at varying concentrations. The results show that in the frequency range 8-18 GHz, the peak absorption of double-layer samples is -12.3dB, the effective bandwidth (R < -10 dB) is 1.8GHz. The absorption peak of three-layer samples is -18 dB, and the effective bandwidth (R < -10 dB) is 8GHz. The findings of this research are useful in improving the absorption bandwidth of absorbing material.
Abstract: One of the main hurdles for the wide use of current Ag-filled conductive composites is the high cost of Ag fillers, while the challenge for low cost copper-filled composites is their poor reliability. In this study, the Ag-coated Cu flakes was chosen as conductive fillers and a surface modification with coupling agent, to achieve good bonding between the flakes and the Polydimethylsiloxane (PDMS) matrix, was applied to improve the mechanical and conductive properties of the PDMS based composites. The resulting composites obtained through modification showed an increase in hardness by 13.1% and tensile strength by 28.4% relative to the composites without coupling agent. In addition, the reliability of conducting composites was discussed and the results showed that the coupling agent played a great role in preventing the corrosion of the exposed Cu during aging. The volume resistivity of the composites, filled with untreated Ag-coated Cu flakes, increased from 0.0039Ω·cm to 0.0059Ω·cm under aging at 85°C and 85% room humidity (RH) in a temperature/humidity chamber for 48 h, in contrary, the volume resistivity shift of the composites with treated flakes was almost negligible, just changed from 0.0043Ω·cm to 0.0045Ω·cm. More importantly, the prepared conductive silicone rubber filled with Ag-coated Cu flakes with the resistivity (0.004Ω·cm) comparable to the relative commercial products can be used for electro-magnetic interference (EMI).
Abstract: In this paper, single crystal of CuAlNiBe quaternary shape memory alloy was prepared in a high temperature gradient directional solidification furnace with a selective growing crystallizer. And its shape memory performance characters were systematically compared with other series copper base shape memory alloys. The results show that the single crystal of CuAlNiBe quaternary shape memory alloy has better shape memory properties.
Abstract: Structure, microhardness and fracture features of coatings produced by atmospheric electron-beam cladding of amorphous boron were investigated. The coatings were produced by cladding of one, two and three layers of powder. Produced coatings thickness is 550, 750 and 900 μm respectively. The peak level of microhardness is 14000…16000 MPa. By the means of XRD analysis it is stated that the main phases of strengthened layers are FeB and Fe2B borides and eutectic (α-Fe + Fe2B). The coatings after one layer cladding have non-uniform structure with microvolumes having lack of borides. Three-layered coatings are noted for their high brittleness. The best properties are presented by two-layer coatings.
Abstract: In this paper, we report the first study on cytotoxicity of single-walled carbon nanotubes (SWCNTs) and theirs derivatives with human ocular cells, such as ARPE-19 cells. In particular, we have systematically investigated the cytotoxicity of SWCNTs, hydroxyl-functionalized SWCNTs (SWCNT-OH), and carboxylic functionalized SWCNTs (SWCNT-COOH) with ARPE-19 cells by examining their influence on the cell morphology, viability, oxidative stress, membrane integrity and apoptosis. To this end, various methods, including optical micrography, CCK-8 assay, LDH assay, SOD assay, TEM and Apoptosis assay, have been used in this study. Our results suggest that SWCNTs could cause an decrease in the cell survival rate, changes in the SOD level, membrane integrity and cell apoptosis, indicating a high toxicity to ARPE-19 cells. However, chemical functionalization of SWCNTs with –OH and –COOH groups was found to significantly improve the biocompatibility of SWCNTs. Among the SWCNTs and their derivatives studied in this work, the SWCNT-COOH exhibits the best biocompatibility to ARPE-19 cells.
Abstract: The interaction of the single azo dye, carmine with ﬁsh-sperm dsDNA is inspected in pH 3.2 H2SO4 with electrochemical method on the surface of nanometer TiO2 modified carbon paste electrode. After the addition of dsDNA, the peak currents of oxidation and reduction peaks of carmine decrease with a positive shift of potential, indicating that intercalation interaction between the dye and dsDNA is taken place. This is consistent with ﬂuorescence spectra results. The binding constant and binding ratio is calculated as 4.92×108 and 1:2, respectively. Furthermore, the decrease in the oxidation peak currents is found proportional to dsDNA concentration in the range of 21.24-127.44 μg·mL-1 with a detection limit of 16.04 μg•mL-1.
Abstract: Heat-resistant Al-8.5Fe-1.3V-1.7Si alloys were prepared by spray forming technique. The effect of temperature on microstructure and mechanical properties of the alloys was studied by optical microscope(OM), transmission electron microscope(TEM) with energy dispersive spectrometer(EDS), X-ray diffraction(XRD), differential scanning calorimeter(DSC) in this paper. The research results show that the microstructure of the material doesn’t change obviously after being hold for 3 hours at 420°C temperature. When the temperature is over 420°C, the second coarse phases are found in the alloy. The study on the microstructure of the alloy exposed at 400°C for 100 hours shows that the alloy has excellent high temperature stability. And the main second phase in the alloy is spherical a-Al12(Fe,V)3Si, with a little other phases such as Al13Fe4, Al6Fe, Al9FeSi3 and so on.
Abstract: Digital printing ink imaging is one of main technical fields in digital printing technology development, fluorescence inkjet digital printing is provided with favorable anti-falsification, which is used widely in Securities anti-counterfeiting and labels anti-counterfeiting etc. Printings coated with fluorescence inkjet ink that emits fluorescence under using short-wave ultraviolet light excitation get more favorable anti-falsification. Green fluorescent inkjet ink is composed of phosphor, resin, solvent, assistant agent etc, resin is main one of green fluorescent inkjet ink, which has a significant implication for its property. In order to discuss resins to green fluorescent inkjet ink properties, five samples of fluorescent inkjet ink are prepared, and test various performance parameters of ink samples, such as luminous intensity, surface tension, adhesive force, aridity, and so on. The study result indicated that resins have a great influence on luminous intensity, surface tension, aridity of fluorescence inkjet ink samples, surface tension and viscosity of resins immediately impact surface tension and viscosity of fluorescent inkjet ink.