Surface modification of Ti-49.8at%Ni alloy by Ti ion implantation: phase transformation, corrosion, and cell behavior

The Ti-49.8at%Ni alloy was modified by Ti ion implantation to improve its corrosion resistance and biocompatibility. The chemical composition and morphologies of the Ti Ni alloy surface were determined using atomic force microscopy(AFM), auger electron spectroscopy(AES), and X-ray photoelectron spectroscopy(XPS). The results revealed that Ti ion implantation caused the reduction of Ni concentration and the formation of a Ti O2 nano-film on the Ti Ni alloy. The phase transformation temperatures of the Ti–Ti Ni alloy remained almost invariable after Ti ion implantation. Electrochemical tests indicated that the corrosion resistance of Ti Ni increased after Ti ion implantation. Moreover, the Ni ion release rate in 0.9% Na Cl solution for the Ti Ni alloy remarkably decreased due to the barrier effect of the Ti O2 nano-film. The cell proliferation behavior on Ti-implanted Ti Ni was better than that on the untreated Ti Ni after cell culture for 1 d and 3 d.

Effect of Solution Heat Treatment in α+β Phase Region on Shape Memory Characteristics of Cu-Al-Ni-Mn-Ti Alloys

The effect of aluminium content and solution heat treatment in α+β phase region on the shape memory characteristics and mechanical properties of cold wrought Cu-Al-Ni-Mn-Ti alloy are studied in this paper. Results indicate that the transformation temperature (Tt) of Cu-Al-Ni-Mn-Ti alloy reduces obviously with the increase of the amount of α-phase. During aging at 623 K, Tt increases at first up to a peak value, then decreases with prolongation of aging time. Life time of heat resistance of the alloy at high temperatures is improved with increase of the amount of α-phase, this life time becomes poor with Bainite precipitation. When the amount of α-phase is less than 5%, the ratio of shape recovery brought about by the solution heat treatment in α+β phase region is almost not effected. However, plasticity of the alloy increases obviously as aluminium content decreases. We believe that improving cold workability of Cu-Al-Ni-Mn-Ti alloy and keeping good heat resistant property and shape memory effects are possible by means of reducing the content of aluminium and solulion heat treatment in α+β phase region.

EVALUATION OF A TUBULAR MESH AND A SPIRAL STENT WOVEN FROM TITANIUM NICKEL ALLOY FOR PROSTATIC OBSTRUCTION IN PATIENTS AT HIGH RISK FOR SURGERY REPORT OF 62 CASES

The use of two urethral stents woven from titanium nickel alloy (TiNi) in the form of a tubular mesh or a spiral stent (both made in China) is described. They were implanted in 62 patients,vith prostatic outflow obstruction. till patients were considered contraindicated for surgery. They were divided into a spiral stent group (group I) treated between March 1992 and May 1993, comprising 35 cases, and a tubular mesh group (group 2) treated between October 1993 and December 1994, comprising 31 cases, including four failures in group 1. Thirty-three out of the 35 patients in group 1 were treated successfully. Good results were achieved in eight cases (22.8%) and significant improvements occurred in 24 (68.5%), giving a total effective rate of 91.3%, with a follow-up of 11 to 27 months. Fourteen stents were removed within 6 months after the insertion and six more were removed within 12 months. The mean effective time of the stent in situ was 10.8 months. All 31 cases in the mesh group were treated successfully. Dramatically good effects were obtained in 28 cases (over 90%) and distinct improvements were achieved in two, giving a total effective rate of over 96.5%, with a follow-up of 6 to 14 months (mean 10.5 months). Cystoscopy was carried out in 12 patients after 6 months following the insertion. The major part of the meshes became covered by urothelium. Compared with the spiral, the mesh makes it possible to insert a prosthesis with a larger diameter and anti-pressure. The spiral, however, can be used as a temporary alternative for the relief of prostatic obstruction. A tubular mesh can work well for the relief of prostatic obstruction and remain in situ without causing major problems for at least I year.

Facile fabrication of novel cobalt-based carbonaceous coatings on nickel-titanium alloy fiber substrate for selective solid-phase microextraction

Fabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction(SPME).Herein,new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on the nickel-titanium alloy(Ni Ti)fiber substrate using ZIF-67 as a precursor and template through the chemical reaction of ZIF-67 with glucose,dopamine(DA)and melamine,respectively.The adsorption performance of the resulting coatings was evaluated using representative aromatic compounds coupled to high-performance liquid chromatography(HPLC)with ultraviolet detection(HPLC-UV).The results clearly demonstrated that the adsorption selectivity was subject to the surface elemental composition of the fiber coatings.The cobalt and nitrogen co-doped carbonaceous coating showed better adsorption selectivity for ultraviolet filters.In contrast,the cobalt-doped carbonaceous coating exhibited higher adsorption selectivity for polycyclic aromatic hydrocarbons.The fabricated fibers present higher mechanical stability and higher adsorption capability for model analytes than the commercial polydimethylsiloxane and polyacrylate fibers.These new strategies will continue to expand the Ni Ti fibers as versatile fiber substrates for metal-organic frameworks(MOFs)-derived coating materials with controllable nanostructures and tunable properties.

Selective inhibition effects on cancer cells and bacteria of Ni–Ti–O nanoporous layers grown on biomedical NiTi alloy by anodization

Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion.The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification.Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization,and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus,human lung epithelial cancer cells(A549),as well as human endothelial cells(EA.hy926).The nanoporous layer with a thickness of 10.1 lm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells.Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells.The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.