The Effect of Plasma Treatment on the Mechanical and Biological Properties of Polyurethane Artificial Blood Vessel.

In recent years, the incidence of cardiovascular disease has increased annually, and the demand for artificial blood vessels has been increasing. Due to the formation of thrombosis and stenosis after implantation, the application of many materials in the human body has been inhibited. Therefore, the choice of surface modification process is very important. In this paper, small-diameter polyurethane artificial blood vessels were prepared through electrospinning, and their surfaces were treated with plasma to improve their biological properties. The samples before and after plasma treatment were characterized by SEM, contact angle, XPS, and tensile testing; meanwhile, the cell compatibility and blood compatibility were evaluated. The results show that there are no significant changes to the fiber morphology or diameter distribution on the surface of the sample before and after plasma treatment. Plasma treatment can increase the proportion of oxygen-containing functional groups on the surface of the sample and improve its wettability, thereby increasing the infiltration ability of cells and promoting cell proliferation. Plasma treatment can reduce the risk of hemolysis, and does not cause platelet adhesion. Due to the etching effect of plasma, the mechanical properties of the samples decreased with the extension of plasma treatment time, which should be used as a basis to balance the mechanical property and biological property of artificial blood vessels. But on the whole, plasma treatment has positive significance for improving the comprehensive performance of samples.

A dual-modification strategy for P2-type layered oxide via bulk Mg/Ti co-substitution and MgO surface coating for sodium ion batteries.

P2-type materials are regarded as competitive cathodes for next generation sodium ion batteries. However, the unfavorable P2 â†’ O2 phase transition usually leads to severe capacity decay. Moreover, the cathode material always suffers from destruction of surface crystal structure caused by trace amount of HF. In this study, a dual-modification method containing Mg/Ti co-doping and MgO surface coating is designed to solve the defects of P2-type Na0.67Ni0.17Co0.17Mn0.66O2 cathode. Results turn out that the P2 structure can be stabilized via Mg/Ti co-substitution and MgO layer could effectively prevent the surface from corroding by HF and promote migration of Na+. Moreover, the as-prepared MgO-coated Na0.67Ni0.17Co0.17Mn0.66Mg0.1O2 exhibits improved electrochemical performance than the raw material. It delivers 111.6 mAh g-1 initial discharge capacity and maintains 90.6% at high current density of 100 mA g-1 within 2-4.5 V, which has been obviously enhanced than that of Na0.67Ni0.17Co0.17Mn0.66O2. The significant improvement can be attributed to the synergistic effect of Mg/Ti co-substitution and MgO surface coating. This dual-modification strategy based on the synergetic effect of Mg/Ti co-doping and MgO surface coating might be a resultful step forward to develop cathode materials for sodium ion batteries.

A process of leaching recovery for cobalt and lithium from spent lithium-ion batteries by citric acid and salicylic acid.

There is great economic and environmental value in recovering valuable metal ions from spent lithium-ion batteries (LIBs). A novel method that employs organic acid recovery using citric acid and salicylic acid was used to enhance the leaching of metal ions from the cathode materials of spent LIBs. The effects of the acid concentration, reducing agent content, solid to liquid (S : L) ratio, temperature, and leaching time were systematically analyzed and the optimal acid leaching process condition was determined through the results. The kinetics of the leaching process with different temperatures was analyzed to explore and verify the relationship between the leaching mechanism and temperature. The results of TG/DSC analysis showed that the optimum calcination temperature was 500 °C for 1 h and 600 °C for 3 h. The XRD and micromorphology analysis results showed that cathode material powders without impurities were obtained after pretreatment. The experimental results demonstrated that the optimal leaching efficiencies of the metals ions were 99.5% Co and 97% Li and the optimal corresponding condition was 1.5 M citric acid, 0.2 M salicylic acid, a 15 g L-1 S : L ratio, 6 vol% H2O2, 90 °C, and 90 min. Afterward, the infrared tests and SEM morphologies results indicated that only salicylic acid was present in the residue after filtration because of the microsolubility of the salicylic acid. Finally, it was obvious that the temperature had a great influence on the leaching process as observed through the kinetics and thermodynamics analyses, while the E a values for Co and Li were obtained as 37.96 kJ mol-1 and 25.82 kJ mol-1 through the kinetics model. The whole process was found to be efficient and reasonable for recovering valuable metals from the industrial electrodes of spent LIBs.

Facile Synthesis of Nitrogen-Doped Green-Emission Carbon Dots as Fluorescent Off-On Probes for the Highly Selective Sensing Mercury and Iodine Ions.

In this work, green-emission carbon dots (CDs) were prepared for detecting mercury ions (Hg(II)) and iodine ions via a facile hydrothermal method using ethylenediamine and methyl red as nitrogen and carbon sources, respectively, without any other complex reagents. The bacteriostasis experiment showed that the CDs were not toxic to the growth of four kinds of bacteria: Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), which indicated that the CDs had good security and could be used for analysis and detection. The CDs exhibited excitation-independent emission, the fluorescence of which could be quenched by Hg(II), and could be recovered by iodine ions. An approach was established to detect Hg(II) based on the fluorescence quenching of CDs by the synergistic action of a photo induced electron transfer (PET) mechanism, and iodine ions were detected based on the fluorescence recovery of CDs by a HgI2 precipitate formation mechanism. The detection limits for Hg(II) and iodine reached 0.89 µM and 0.50 µM, respectively. Compared to most methods, the method mentioned in this paper has good selectivity, a wider linear range, a lower detection limit and higher security. The synthesized CDs could be probes for sensing Hg(II) and iodine ions.

[Design and fabrication of the nickel-free stainless steel coronary stent].

A kind of coronary stent was made from Nickel-free stainless steel, and the technological process of the stent was studied. A preferable flexible and support force stent was simulated by a commercial finite element code ANSYS with laser cutting, pickling and vacuum annealing. This kind of coronary stent has more superiority. It was also presented that a self designed automatic stent electro-polishing device, which greatly improve efficiency and quality, and the optimization electro-polishing process was put forward.