Strain-induced phase transformation behavior of stabilized zirconia ceramics studied via nanoindentation.

To study the tetragonal-to-monoclinic (T-M) phase transformation behavior under different strain rates and indentation depths, nanoindentation tests were performed on stabilized zirconia ceramics with Continuous Stiffness Measurements. The results indicate decreased phase transformation velocities at both lower and higher strain rates, but increased velocity under medium strain rate during loading. The phase transformation process is sensitive to P/P but the final volume fractions are almost identical (45%). Furthermore, most of the phase transformation is completed during a short initial time followed by slight linear increase of the M-phase volume fraction with holding time. The phase transformation continuously slowed with increasing indentation depth when indented with a constant strain rate.

Studies of the mechanism of an antibacterial peptide (cecropinA-magainin) on methicillin-resistant Staphylococcus aureus membranes.

As bacterial resistance becomes increasingly common, a new hybrid peptide, cecropinA-magainin (KWALSKEGPGKFLGKKKKF), has been developed that can kill a broad spectrum of bacteria without damaging human cells. The mechanism of antibacterial toxicity for the hybrid peptides is unknown. Herein, we investigate the localization of the hybrid peptide in methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentration was 64 µg/mL. The hybrid peptides could enhance the hydrophobicity of MRSA. Dye leakage experiments showed that the hybrid peptides caused dye leakage from liposomes. The hybrid peptides influenced the permeability of the outer membrane and plasma membrane of MRSA. After cecropinA-magainin treatment of MRSA, the membrane ultrastructure was damaged and the concentration of K+ increased. Ultimately, the peptide destroyed the integrity of the bacterial cell membrane, allowing the dye propidium iodide to enter the cytoplasm. Therefore, the hybrid antibacterial peptide can kill MRSA.

Microstructure, corrosion and tribological and antibacterial properties of Ti-Cu coated stainless steel.

A Ti-Cu coated layer on 316L stainless steel (SS) was obtained by using the Closed Field Unbalanced Magnetron Sputtering (CFUBMS) system to improve antibacterial activity, corrosion and tribological properties. The microstructure and phase constituents of Ti-Cu coated layer were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and glow discharge optical emission spectrometry (GDOES). The corrosion and tribological properties of a stainless steel substrate, SS316L, when coated with Ti-Cu were investigated in a simulated body fluid (SBF) environment. The viability of bacteria attached to the antibacterial surface was tested using the spread plate method. The results indicate that the Ti-Cu coated SS316L could achieve a higher corrosion polarization resistance and a more stable corrosion potential in an SBF environment than the uncoated SS316L substrate. The desirable corrosion protection performance of Ti-Cu may be attributable to the formation of a Ti-O passive layer on the coating surface, protecting the coating from further corrosion. The Ti-Cu coated SS316L also exhibited excellent wear resistance and chemical stability during the sliding tests against Si3N4 balls in SBF environment. Moreover, the Ti-Cu coatings exhibited excellent antibacterial abilities, where an effective reduction of 99.9% of Escherichia coli (E.coli) within 12h was achieved by contact with the modified surface, which was attributed to the release of copper ions when the Ti-Cu coatings are in contact with bacterial solution.

Controlled hydrogenation of P(VDF-co-CTFE) to prepare P(VDF-co-TrFE-co-CTFE) in the presence of CuX (X = Cl, Br) complexes.

An environmentally friendly and controllable P(VDF-co-CTFE) hydrogenation route involving the transition-metal complex mediated radical chain transfer reaction is successfully developed to synthesize P(VDF-co-CTFE-co-TrFE). The typical transition metal catalysts of ATRP reaction could be applied in this process.