Influence of Size Effect in Milling of a Single-Crystal Nickel-Based Superalloy.

This paper details an experimental investigation on the influence of the size effect when slot-milling a CMSX-4 single-crystal nickel-based superalloy using 1 mm- and 4 mm-diameter TiAlN-coated tungsten carbide (WC) end-mills. With all tools having similar cutting-edge radii (re) of ~6 µm, the feed rate was varied between 25-250 mm/min while the cutting speed and axial depth of cut were kept constant at 126 m/min and 100 µm, respectively. Tests involving the Ø 4 mm end-mills exhibited a considerable elevation in specific cutting forces exceeding 500 GPa, as well as irregular chip morphology and a significant increase in burr size, when operating at the lowest feed rate of 25 mm/min. Correspondingly for the Ø 1 mm micro-end-mills, high levels of specific cutting forces up to ~1000 GPa together with severe material ploughing and grooving at the base of the machined slots were observed. This suggests the prevalence of the size effect in the chip formation mechanism as feed per tooth/uncut chip thickness decreases. The minimum uncut chip thickness (hmin) when micromilling was subsequently estimated to be less than 0.10 re, while this increased to between 0.10-0.42 re when machining with the larger Ø 4 mm tools.

Improving tribological and anti-bacterial properties of titanium external fixation pins through surface ceramic conversion.

In this study, an advanced ceramic conversion surface engineering technology has been applied for the first time to self-drilling Ti6Al4V external fixation pins to improve their performance in terms of biomechanical, bio-tribological and antibacterial properties. Systematic characterisation of the ceramic conversion treated Ti pins was carried out using Scanning electron microscope, X-ray diffraction, Glow-discharge optical emission spectroscopy, nano- and micro-indentation and scratching; the biomechanical and bio-tribological properties of the surface engineered Ti pins were evaluated by insertion into high density bone simulation material; and the antibacterial behaviour was assessed with Staphylococcus aureus NCTC 6571. The experimental results have demonstrated that the surfaces of Ti6Al4V external fixation pins were successfully converted into a TiO2 rutile layer (~2 µm in thickness) supported by an oxygen hardened case (~15 µm in thickness) with very good bonding due to the in-situ conversion nature. The maximum insertion force and temperature were reduced from 192N and 31.2 °C when using the untreated pins to 182N and 26.1 °C when the ceramic conversion treated pins were tested. This is mainly due to the significantly increased hardness (more than three times) and the effectively enhanced wear resistance of the cutting edge of the self-drilling Ti pins following the ceramic conversion treatment. The antibacterial tests also revealed that there was a significantly reduced number of bacteria isolated from the ceramic conversion treated pins compared to the untreated pins of around 50 % after 20 h incubation, P < 0.01 (0.0024). The results reported are encouraging and could pave the way towards high-performance anti-bacterial titanium external fixation pins with reduced pin-track infection and pin loosing.

Nasal myiasis: A case report.

Nasal myiasis is a rare condition, with only a few reported cases and no treatment consensus. We propose a conservative treatment approach with saline irrigation and debridement. Two patients in the ICU of Norfolk General Hospital, a tertiary academic referral center, presented simultaneously with nasal myiasis. Both patients were negative for necrotic masses or tumors, and neither patient had any contributory medical comorbidities. Both patients were treated conservatively with a single dose of pyrantel pamoate, daily sinus irrigation with saline, and daily bedside endoscopic debridement. After 2 days, the nasal myiasis resolved, and both patients recovered without sequelae. We conclude that this conservative, nonsurgical approach to management is both safe and effective.

Three-dimensional electroanatomic mapping of the coronary veins during cardiac resynchronization therapy implant: feasibility and possible applications.

PURPOSE: Left ventricular (LV) electrical activation pattern could determine optimal LV lead placement site during cardiac resynchronization therapy (CRT) device implant. We sought to determine the feasibility of using EnSite NavX™ electroanatomic mapping system (St. Jude Medical Inc., St. Paul, MN) to assess LV electrical activation during CRT implant. METHODS: Patients (n = 32; NYHA III, LVEF <35%, QRSd >120 ms) underwent NavX™ mapping during CRT implant. Left bundle branch block (LBBB) was present during sinus rhythm in group A (n = 17), whereas LBBB was induced by permanent RV apical pacing in group B (n = 15). Following coronary sinus (CS) cannulation, a coil tip 0.014-in. guidewire was introduced into all available CS branches as a mapping electrode. Each patient's unipolar activation map was successfully constructed within 10 min, using the onset of surface QRS as reference. RESULTS: LV activation patterns were complex and varied in both groups. Earliest activation was usually apical, but latest activation was more heterogenous. The lateral or posterolateral branches were the sites of latest activation in 47% of group A and 73% of group B. An LV lead positioned conventionally by a physician blinded to the mapping data was concordant with the latest activated segment in 18% of group A and none of group B patients. CONCLUSIONS: Electroanatomic mapping of the CS tributaries is feasible and clinically practicable. Mapping revealed heterogenous conduction patterns that vary between patients in each group and between groups. An LV lead empirically placed in a lateral branch rarely paces the optimal, latest activated vein segment.

Cassowary pediatrics.

Abduction at the stifle joint is a common deformity upon hatching often referred to as splay leg. One possible cause hypothesized is larger yolk sacs force apart the cassowary chick's legs (see Fig. 17). Splay leg is most common in the first 2 or 3 chicks of the season. Usually 1 leg is affected but both can be involved. Treatment is generally successful with bandaging techniques. This is done by hobbling with bandage tape. (above the hock) for 3 days and observing closely for correct alignment.