Bacteria adhesion and encrustation formation on the surface of ureteral stents have been common complications clinically. Herewith, the Cu grafting polydopamine coating was prepared on 316L stainless steel via polydopamine graft agent assisted electroless Cu plating method, in order to create a coating with performance of anti-infection, anti-stone formation and good biocompatibility for the ureteral stent surface. While the surface morphology, composition and copper ions release of the coatings were assessed by means of scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma mass spectrometry. Samples were incubated with bacteria and cells respectively, so that to examine the antibacterial ability, encrustation resistance and biocompatibility of coatings. The results show that the coating is evenly distributed. The copper in the coating consists of Cu, CuO and Cu₂O and its thickness is 27.0 nm. The content of releasing copper for each day remains nearly constant after immersion in artificial urine. The antibacterial rates against Escherichia coli and Staphylococcus aureus are 96.2% and 95.9% after incubating for 24 hours, respectively. The contents of calcium and magnesium of samples, which are deposited in the human urine coupled with Staphylococcus aureus for 30 days, are 48.7 mg/L and 235.3 mg/L, respectively, which is significantly lower than that of the control group. Cells proliferation assay shows no cytotoxicity.

Deformation behavior at different temperatures of the cast and annealed 2024 Al-alloy was investigated by means of MMS thermal simulation test machine. The constitutive equation and DMM (Dynamic material model) processing map of the alloy were established. The theoretical support for 2024 Al-alloy extrusion part with an extrusion ratio of 26.9 was provided by the results obtained from DMM map. The microstructures and mechanical properties of the alloys in different situations, namely, the cast plus post annealing, isothermally extruded and isothermally extruded plus post annealing were characterized by OM(Optical microscope), TEM (Transmission electron microscope) and tension tester. The results show that the test articles of 2024 Al-alloy experienced isothermal extrusion with large extrusion ratio can be obtained by strain rate within the range of 0.01~0.1 s^-1 at temperatures within 395~450℃, according to the proposed DMM processing map, consequently, the resulted test articles present refined microstructure with excellent mechanical properties.

The Hydrogen embrittlement (HE) susceptibility of the quenched boron steel B1500HS before and after being electrochemical hydrogen charging by applying different stresses, such as simple shear, uniaxial tensile and analogous plane strain, respectively was investigated via slow strain rate tensile test. Meanwhile, the stress-strain curves for both the H-free and H-charged steels were acquired and then the HE susceptibility of the test steels was calculated based on the equivalent plastic strain to reveal the effects of the stress state on the HE susceptibility of the quenched boron steel. Furthermore, the fracture features of the steels were characterized by SEM and EBSD to analyze the HE mechanism for the different applied stress. The results show that the HE mechanisms of the quenched boron steel by simple shear stress is substantial different to those by tensile stress, which indicated that the HE susceptibility during testing by simple shear stress is much lower than that by tensile stress.

In order to analyze and explore the changes of deformation, mechanical behavior and structure of spider major ampullate gland silk (abbr: Mas) during repetitive stretching and their relationship, the mechanical behavior of spider Mas and the changes of protein secondary structure after repetitive stretching were tested and investigated through the design of different combinations of loading elongation and the interval relaxation between the two stretching via electronic universal testing machine and laser Raman spectrometer. The results show that spider Mas presents excellent repetitive stretching characteristics with the gradual increase of the initial modulus but the a marginal variation in yield stress; When two groups of spider Mas fibers were stretched in the condition of gradual increase of the set stretching length and the set time intervals as 15~25 s and 5 min respectively, as a result, the acquired tensile curves of the two groups overlapped fairly well, even for the samples were stretched over the yield point, or even over the yield zone and into the strengthening zone as well; It reveals that in case the stretching test of the above two groups of samples has been interrupted for a long time interval of ≥23 min in between two stretching tests, the mechanical behavior of samples may be reproduced as soon as only one stretch again independent from the previous loading history. In other word, the above findings show that the mechanical behavior of spider Mas is similar to those of rubber's viscoelasticity. The results of Raman spectra showed that with the increase of the number of repetitive stretching and the set stretching length, the hydrogen bond between the random coils was broken. The interval after stretching seems to allow some structures to recover and contribute to the formation of the new β-turn or β-bend and PGⅡ β-sheet structure, After repetitive stretching for many times, the primitive β-sheet structure will be gradually destroyed, and almost all of it will be destroyed when Mas breaks. These findings may be helpful to guide the biomimetic design of novel fiber materials.

Bi_7-x Er _x Ti_4.5W_0.5O₂₁(BTW-BIT-xEr³⁺, x=0.05, 0.10, 0.15, 0.25, 0.35) lead-free piezoelectric ceramics with intergrowth bismuth-layered structure was fabricated via solid phase synthesizing method. While the effect of Er³⁺-doping on their up conversion fluorescence and electrical properties was systemically investigated. The results of XRD and SEM reveal the formation of a single phase with bismuth-layered structure of Bi_7-x Er _x Ti_4.5W_0.5O₂₁ (BTW-BIT-xEr³⁺(x=0.05, 0.10, 0.15, 0.25, 0.35)). Three emissions of two green and one red were observed for all the BTW-BIT-xEr³⁺ products with chemical compositions within the desired range under 980nm light excitation. The three emissions centered at 532 nm, 548 nm and 660 nm, and the intensity ratio of red to green emissions could be adjusted by changing the doping amount of Er³⁺ ions. According to the intensity ratio of 532 nm to 548 nm for BTW-BIT-0.15Er³⁺ in the range of 290~440 K, the temperature sensitivity was fitted and showed the maximum temperature sensitivity of 0.0023 K^-1 at 440 K. The dielectric and impedance of BTW-BIT-xEr³⁺ ceramics were analyzed. The results show that Er³⁺ ions replaced Bi³⁺ ions in the pseudo-perovskite layer, therewith the oxygen vacancy concentration decreases, which may be accounted for the decrease of high-temperature dielectric loss, the raising of activation energy and the enhancement of piezoelectric constant. The BTW-BIT-0.15Er³⁺ ceramic possesses the comprehensive properties: d₃₃=14pC/N, T_c=697℃ and tanδ=0.53%, as well as the optimal photoluminescence and good thermal stability.

The Cu-W composites with three different microstructures, namely quadrilateral, hexagonal and rhomboidal microdirectional skeleton structure were designed and prepared, and their static welding properties were investigated, by taking the Cu-W composites with disordered skeleton structure as comparison. According to the principle of fluid mechanics, the variation of temperature and conduction heat flux for composites of various macrostructures with time were analyzed by means of finite element method, and their thermal conductivity was calculated. The results show that the contact resistance of Cu-W composites with microscopically oriented skeleton structure is lower and more stable, among others, the composite with rhombic dodecahedral skeleton has the lowest contact resistance, and where may exist a heat conducting chain, and even an uniformly distributed heat conducting network, which reduces the regional thermal resistance to a greater extent. According to the Marangoni effect, the molten pool morphology of the composites with different microstructures is compared, and it is found that the regular distribution of Cu and W two-phase materials can facilitate the reduction of the size of aggressed area induced by the static fusion welding, accordingly the rhomboidal dodecahedron matrix composites have the lowest aggressed area.

Graphene nanosheets (GNP) reinforced Cu-based composites GNP-Cu and GNP-Ni/Cu were prepared via a three-step process, i.e. wet mixing powders of Cu, Ni and GNP, then spark plasma sintering and finally hot extrusion. The phase composition, microstructure, density, electrical conductivity, and mechanical properties of GNP-Ni/Cu composites were characterized, and the mechanism of GNP and Ni strengthening GNP-Ni /Cu composites was also investigated. The results show that the microhardness and yield strength of GNP-Ni/Cu composite with 0.2% GNP and 1.5% Ni (in mass fraction) are 38% and 50% higher than those of simple Cu, and 14.0% and 11.6% higher than those of 0.2GNP/Cu composite, respectively. These results indicate that the interface bonding between GNP and Cu was improved by Ni addition, and the mechanical properties of GNP-Ni/Cu composites were significantly improved. The load transfer strengthening and thermal mismatch strengthening of GNP and the Ni solution strengthening are the main causes for the improvement of mechanical properties of materials.

A super martensitic stainless steel was alloyed with nitrogen, and afterwards subjected to quenching and partitioning treatments. Then the performance of three super martensite stainless steels without and with 0.23% and 0.35% nitrogen (in mass fraction), respectively were characterized by means of OM, SEM, TEM, EBSD, BSD, universal testing machine and Vickers hardness tester, in terms of the effect of nitrogen on their microstructure and mechanical properties. The results show that: The addition of nitrogen refines the martensitic slats of the steels, and of which the average width was reduced from 2.93 μm to 0.65 μm. During the partitioning treatment, the high nitrogen concentration provides a driving force for the formation of inverting austenite and facilitates its stabilizing at room temperature. The strength and plasticity of the steels alloyed with nitrogen are obviously higher than those of the nitrogen free ones, the tensile strength and elongation of steels with 0.23 N and 0.35 N are 1510 MPa and 24.2%, and 1215 MPa and 35.1%, respectively. It can be seen that nitrogen alloying is beneficial to improve the mechanical properties of super martensitic stainless steel.

Laccase (LAC) was immobilized onto a framework-like material of metal-organic compound (ZIF-90) by means of internal encapsulation and surface physical-adsorption, herewith, two composites of LAC@ZIF-90 and LAC-ZIF-90 were prepared respectively. The structure, property, stability and degradation performance for catechol of the free- and immobilized-laccase were comparatively characterized by means of scanning electron microscopy (SEM), laser confocal electron microscopy (CLSM), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), fluorescence analysis and high performance liquid chromatography (HPLC) etc. The results show that: laccase molecules were fixed on the surface and inside of ZIF-90, and the molecular structure was stable before and after being fixed; the removal rates for catechol by lac-ZIF-90 and LAC@ZIF-90 were 97% and 19.4%, respectively for the solution with proper pH value, whilst by vibrating for 6 h; the lac-ZIF-90 and LAC@ZIF-90 still showed high vitality after repeatedly used for 5 times; it is especially worthy that the removal rate of catechol was higher than 78% even after repeatedly used for 5 times for the lac-ZIF-90.