ABSTRACT
A nano-grained layer including line defects was formed on the surface of a Ti alloy (Tialloy, Ti-6Al-4V ELI). Then, the micro- and nano-grained Tialloy with the formation of TiO2 on its top surface was coated with a bioactive Ta layer with or without incorporating an antibacterial agent of Ag that was manufactured by magnetron sputtering. Subsequently, the influence of the charged defects (the defects that can be electrically charged on the surface) on the interfacial bonding strength and hardness of the surface system was studied via an electronic model. Thereby, material systems of (i) Ta coated micro-grained titanium alloy (Ta/MGTialloy), (ii) Ta coated nano-grained titanium alloy (Ta/NGTialloy), (iii) TaAg coated micro-grained titanium alloy (TaAg/MGTialloy) and (iv) TaAg coated nano-grained titanium alloy (TaAg/NGTialloy) were formed. X-ray photoelectron spectroscopy was used to probe the electronic structure of the micro- and nano-grained Tialloy, and so-formed heterostructures. The thin film/substrate interfaces exhibited different satellite peak intensities. The satellite peak intensity may be related to the interfacial bonding strength and hardness of the surface system. The interfacial layer of TaAg/NGTialloy exhibited the highest satellite intensity and maximum hardness value. The increased bonding strength and hardness in the TaAg/NGTialloy arises due to the negative core charge of the dislocations and neighbor space charge accumulation, as well as electron accumulation in the created semiconductor phases of larger band gap at the interfacial layer. These two factors generate interfacial polarization and enhance the satellite intensity. Consequently, the interfacial bonding strength and hardness of the surface system are improved by the formation of mixed covalent-ionic bonding structures around the dislocation core area and the interfacial layer. The bonding strength relationship by in situ XPS on the metal/TiO2 interfacial layer may be examined with other noble metals and applied in diverse fields.
ABSTRACT
The incidence of fascial dehiscence and incisional hernia after two methods for abdominal wound closure (rectus sheath relaxation incisions and conventional mass closure) was studied in a randomized prospective clinical trial in a consecutive series of 100 patients undergoing midline laparotomy for peritonitis. The two groups were well matched for etiologies of peritonitis, the surgical procedures performed, and the presence of known risk factors for fascial dehiscence. Fifty patients each were randomized either to the conventional continuous mass closure procedure or the rectus sheath relaxation incision technique (designed to increase wound elasticity and decrease tension in the suture line) using identical polypropylene sutures. The incidence of postoperative complications such as duration of ileus, chest infection, and wound infection were not statistically different between the two groups. The intensity of postoperative pain in the rectus sheath relaxation incision group was significantly less. The incidence of wound hematoma was significantly increased in the rectus sheath relaxation incision group. The incidences of fascial dehiscence (16% vs,28%; p < 0.05) and incisional hernia (18% vs, 30%; p < 0.05) were significantly lower after rectus sheath relaxation incisions compared to conventional mass closure. Closure of the midline laparotomy wound in cases of peritonitis using the rectus sheath relaxation technique is safe and less painful, provides increased wound elasticity and decreased tension on the suture line, and significantly decreases the incidence of wound dehiscence.
