Search

A ternary complex of Tb(SSA)3Phen was synthesised based on terbium(III) (Tb3+) ion and the ligands including 1,10-phenanthroline (Phen) and 5-sulfosalicylic acid (SSA). Then a series of polylactic acid (PLA)/Tb(SSA)3Phen composites were prepared by the melt-mixing process. The luminescent properties of PLA/Tb(SSA)3Phen composite films were investigated by fluorescence spectrophotometry. The spectra of all composites indicated that PLA/Tb(SSA)3Phen composites shown the characteristic bright green fluorescence which originated from Tb(SSA)3Phen. Moreover, the energy absorption and transfers of Tb(SSA)3Phen were slightly affected by the PLA matrix. The optical transmittance of the composites was measured by the UV–vis spectrometer. The results demonstrated that Tb(SSA)3Phen can ameliorate the PLA film transparence, which well dispersed in the PLA matrix. Moreover, the thermal properties, crystal structure and the mechanical properties of PLA/Tb(SSA)3Phen composite were also investigated to determine the potential usage as a green fluorescent material.

Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories: unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.

Dealloying has been recognized as an effective way to fabricate metallic nanoporous structure. In this experimental study, a novel in-situ nanostructure forming route is proposed, which combines surface alloying and dealloying processes. By controlling the in-situ reaction–diffusion process of surface alloying and the in-situ nano-porosity forming process of dealloying, 3-D well ordered nanoporous copper surface (NPCS) was obtained. The NPCS shows significant enhancement in heat transfer coefficient and reduction in wall superheat compared with those of flat surface in visualization designed pool boiling experiments, which can be attributed to the higher active nucleation site and the improvement in wettability on nanoporous surface. The NPCS presents good stability in chemical composition and 3D nanoporous structure, which indicates a promising prospect for long-term application.

Hydrogen isotope catalytic exchange between hydrogen and liquid water is a very effective process for deuterium-depleted potable water production and heavy water detritiation. To improve the characteristics of hydrophobic catalysts for this type of reaction, foamed and cellular structures of hydrophobic carbon-supported platinum catalysts were successfully prepared. Separation of deuterium or tritium from liquid water was carried out by liquid-phase catalytic exchange. At a gas–liquid ratio of 1.53 and exchange temperature of 70 °C, the theoretical plate height of the hydrophobic catalyst (HETP = 34.2 cm) was slightly lower than previously reported values. Changing the concentration of the exchange column outlet water yielded nonlinear changes in the height of the packing layer. Configurations of deuterium-depleted potable water and detritiation of heavy water provide references for practical applications.

Zr-based bulk metallic glasses (BMG) Zr65+xCu17.5Fe10-xAl7.5 (x = 0, 2.5, 5, 7.5) with high zirconium content were prepared by an injection copper-mold casting method. The influence of Zr partially substituted Fe and isothermal annealing on the microstructure and mechanical properties of the Zr65+xCu17.5Fe10-xAl7.5 BMGs has been systematically studied. The as-prepared BMG with a Zr content of 70 at.% achieves superior glass forming ability with a large supercooled liquid region width of 82 K and compressive performance. An optimized isothermal annealing (0.5 h) below the glass transition temperature of the as-cast Zr70Cu17.5Fe5Al7.5 BMG contributes significant enhancement in compressive fracture strength and plasticity, from 1845 MPa and 7.4% (as-cast) to 2096 MPa and 12.7% (annealed), respectively. The result of the present study provides a new strategy for designing high-performance BMG-based alloys.

The temperature distribution of a long-span structures is not uniform due to solar radiation. Assumptions of uniform and nonuniform temperature field make the analysis results different. A mathematical model of solar radiation is established to calculate the hourly radiation intensity on the surface of a building at any geographical location. The temperature distribution of a 100m span spherical reticulated shell located in Guiyang city in China is calculated. The mechanical performance of the structure is analysed by finite element method. The following results gives: 1. the highest temperature is 48.5°C and the lowest temperature is 23.0°C. 2. The nonuniform temperature distribution makes the deformation of the reticulated shell no longer symmetrical.

A method of water injection to flow field using distributed holes on the suction surface of hydrofoil is presented in this article to control cavitation flow. Modified renormalization group k–ε turbulence model is coupled with full-cavitation model to calculate periodical cavitation patterns and the dynamic characteristics of the NACA66(MOD) hydrofoil. Water injection is found to be highly effective for cavitation suppression. The cavitation suppression effect of distributed regulation of jet holes and porosities along three-dimensional spanwise hydrofoil is also investigated. The appropriate porosities of single row spanwise jet holes and optimal jet position of double row jet holes are revealed for both cavitation suppression and good hydrodynamic performance. Double row jet holes setting in forward trapezoidal arrangement shows great potential for cavitation suppression and hydrodynamic performance. This research provides a method of water injection to flow field to actively control cavitation, which will facilitate development of engineering designs.

Since many industrial materials have micro or submicro structures on the surface or subsurface, utrahigh-resolution is required in the inspection of these materials. Ultrahigh-resolution optical coherence tomography uses broadband light sources to achieve axial image resolutions on the scale of a few microns. We have been investigating an ultrahigh-resolution spectral-domain optical coherence tomography (SD-OCT) system using supercontinuum sources (SC) in free space. The effective SC spectrum has a full width at half maximum of 230 nm centered around 665 nm, and the imaging setup has an ultrahigh axial resolution of 0.9 μm in air, and a lateral resolution of 3.9 μm, with the system measurement range being 0.6 mm in axial direction. At a 50 μm axial position, the sensitivity can be 63 dB with 28600 axial scans per second at 2048 pixels per axial scan. Images of polystyrene microspheres solution with an average diameter of 5 μm and different sizes of industrial abrasive papers are presented to illustrate the performance of the system.

A novel slow-wave structure called V-shape folded rectangular groove waveguide is proposed. This structure evolves from a conventional rectangular groove waveguide bending the groove with V-shape along its longitudinal direction, and the gap between metal plates forms a sheet electron beam channel naturally. Compared with the traditional U-shape structure, it can increase the interaction area without changing good high-frequency properties, which can adopt the sheet electron beam with a larger area to acquire more output power. In this paper, the high-frequency properties of this structure are analyzed, the interaction circuit for the V-band TWT is designed and the PIC simulation is performed to predict the operating characteristics. From our calculations, this tube can produce average saturation output power over 1000 Watts in a frequency range from 58 GHz to 64 GHz when the cathode voltage and beam current are set to be 12.8 kV and 600 mA respectively. The corresponding saturation gain and electron efficiency can reach over 33 dB and 13.2% respectively.

A series of polycrystaline bulk (La1-xRx)2/3Sr1/3MnO3(R=Sm,Tb) over a wide composition range were prepared by two different techniques, and their structure nd magnetostriction effect were studied carefully at room temperature. The X-ray diffraction pattern indicated that the structure of samples transformed from rhombohedral type to orthorhombic phase with decreasing R contents. The sample, composition near the transformation point, had the maximum value of magnetostriction. The magnetostriction may come from the exchange magnetostriction in the samples at room temperature.

A series of bulk (La1-xPrx)2/3Sr1/3MnO3 polycrystaline samples were prepared by sol-gel technique and the electrical, magnetic properties and magnetostriction effect were studied. At low temperatures, the magnetostriction was mainly about linear magnetostriction and saturated at low magnetic field, and the saturation field decreased with decreasing Pr content. At x=0.3, we found maximum value of -90×10-6.

Characteristic X-ray intensity ratios of M and L lines I(M)/I(L) from a series of pure elements were measured in the analytical electron microscope at 75-200kV. Compiling the previous measured ratios together, all the data have been compared with the calculated values from eight cross-section formulas after normalization in order to eliminate the uncertain parameters, leaving only the voltage dependence of the cross-section. These formulas can be divided into four groups for I(L)/I(K) or three groups for I(M)/I(L) ratios. Only one group, containing two formulas suggested by Fabre de la Ripelle and Schreiber and Wims, is in good agreement with all the experimental data.

Delivery of drugs and biomolecules into skin has significant advantages. To achieve this, herein, a nanomaterial-strengthened dissolving microneedle patch for transdermal delivery is reported. The patch comprises thousands of microneedles, which are composed of dissolving polymers, nanomaterials, and drug/biomolecules in their interior. With the addition of nanomaterials, the mechanical property of generally weak dissolving polymers can be dramatically improved without sacrificing dissolution rate within skin. In this experiments, layered double hydroxides (LDH) nanoparticles are incorporated into sodium carboxymethylcellulose (CMC) to form a nanocomposite. The results show that, by adding 5 wt% of LDH nanoparticles into CMC, the mechanical strength significantly increased. Small and densely packed CMC-LDH microneedles penetrate human and pig skin more reliably than pure CMC ones and attractively the nanocomposite-strengthened microneedles dissolve in skin and release payload within only 1 min. Finally, the application of using the nanocomposite-strengthened microneedle arrays is tested for in vivo vaccine delivery and the results show that significantly stronger antibody response could be induced when compared with subcutaneous injection. These data suggest that nanomaterials could be useful for fabricating densely packed and small polymer microneedles that have robust mechanical properties and rapid dissolution rates and therefore potential use in clinical applications. Refereed/Peer-reviewed