Scheimpflug imaging for grading and measurement of corneo-scleral-profile in different quadrants.

PURPOSE: The corneo-scleral-profile (CSP) describes the transition from cornea to sclera, while the corneo-scleral junction angle (CSJ), is the angle formed between the cornea and the sclera. The aims of this study were (i) to analyse the CSP and CSJ in different quadrants and (ii) to test correlation and repeatability of an established observational grading and measurement method, using Scheimpflug images. METHODS: The nasal, temporal, superior and inferior CSP of 35 healthy eye participants (mean age 25.5 SD ± 3.1 years; 20 female) was imaged using the corneo-scleral-profile module of the Pentacam (Oculus, Wetzlar, Germany). On the captured Scheimpflug images CSP was subjectively graded into five different corneo-scleral transitions, using the Meier grading scale (profile 1 fluid-convex; profile 2 fluid-tangential; profile 3 marked-convex; profile 4 marked-tangential; profile 5 concave). The CSJ was measured on the same images using ImageJ v1.8.0. Grading and measurement was repeated at a second session. Intra-observer reliability for the CSP-grading was analysed by Cohen's Kappa. Differences between repeated CSJ-measurements and different quadrants were analysed by paired-t-test and ANOVA. The eta-coefficient was used to determine the association between subjective CSP-grading and CSJ-measurement. RESULTS: Intra-observer reliability for the CSP grading system was poor (kappa = 0.098) whereas repeated measurements of CSJ angle showed no statistically significant difference between sessions (0.04°; 95 % CI - 0.21° to 0.29°; p = 0.77). CSJ angles ranged from 172° to 180° with no statistically significant differences between nasal, temporal, superior and inferior (p = 0.24). Eta-coefficient indicated a weak association between CSP-grading and CSJ-measurement (η = 0.27; p = 0.04). CONCLUSIONS: The subjective CSP-grading showed poorer repeatability than the objective CSJ-measurement, which did not detect any differences in angles between the meridians. The weak association between CSP-grading and CSJ-measurement is likely caused by the limited intra-observer reliability of the Meier grading scale. Furthermore, the CSP-grading scale seems to consider other aspects beside the CSJ angle, such as scleral radius.

Turning Copper and Aluminum Alloys with Natural Rocks as Cutting Tools.

The need for rare resources, such as tungsten or cobalt, combined with the high energy requirements to produce cutting materials, is forcing research and development to work out environmentally friendly alternatives. Natural rocks could be an alternative since they are available in large quantities worldwide, have a potentially suitable property profile, and do not require energy-intensive processes to make them usable as cutting materials. However, there are only a few studies on the usability and suitability of natural rocks as cutting materials for machining processes. Therefore, in this article, inserts made of natural rocks were ground and used in turning operations. First, the properties of various natural rocks were determined, as were the tool properties after grinding. Then, the tool load and wear during the machining process were recorded and evaluated to assess the potential applications of this alternative cutting material more accurately. It is therefore becoming apparent that flint and quartz are suitable for use as alternative cutting materials and should be further researched.