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Modern manufacturing industry is beginning to benefit greatly from the ability to control the three-dimensional, or areal, structure of a surface. To underpin areal surface manufacturing, a traceable measurement infrastructure is required. In this paper, the development of a new traceable instrument for the measurement of areal surface texture is presented. The instrument uses a two-axis coplanar air-bearing slideway to move the measured surface beneath a stylus probe. The motion of the slideway is measured using linear and angular interferometers. The key to the new instrument is a novel probing system incorporating a cylindrical air-bearing guideway and an electromagnetic system to maintain a constant stylus force on the surface. The deflection of the stylus is measured using a differential plane mirror interferometer thereby minimizing the effect of any error motion in the metrology frame. The uncertainties of the instrument are calculated using a Monte Carlo approach and are evaluated to be 5 nm in the z axis and 16 nm in the x and y axes (all at k = 2). The results are given for the instrument and are compared to results from a traceable profile measuring instrument and a coherence scanning interferometer.

Background:Several factors are known to influence osseous union of femoral neck fractures. Numerous clinical studies have reported different results, hence with different recommendations regarding treatment of Pauwels III fractures: femoral neck fractures with a more vertically oriented fracture line. The current study aimed to analyze biomechanically whether this fracture poses a higher risk of nonunion.Objectives:To analyze the influence of one designated factor, authors believe that a computerized fracture model, using a finite element Finite Element Method (FEM), may be essential to negate the influence of other factors. The current study aimed to investigate a single factor, i.e. orientation of the fracture line toward a horizontal line, represented by Pauwels classification. It was hypothesized that a model with a vertically oriented fracture line maintaining parity of all other related factors has a higher stress at the fracture site, which would delay fracture healing. This result can be applicable to other types of pinning.Patients and Methods:The finite element models were constructed from computed tomography data of the femur. Three fracture models, treated with pinning, were constructed based on Pauwels classification: Type I, 30° between the fracture line and a horizontal line; Type II, 50°; and Type III, 70°. All other factors were matched between the models. The Von Mises stress and principal stress distribution were examined along with the fracture line in each model.Results:The peak Von Mises stresses at the medial femoral neck of the fracture site were 35, 50 and 130 MPa in Pauwels type I, II, and III fractures, respectively. Additionally, the peak Von Mises stresses along with the fracture site at the lateral femoral neck were 140, 16, and 8 MPa in Pauwels type I, II, and III fractures, respectively. The principal stress on the medial femoral neck in Pauwels type III fracture was identified as a traction stress, whereas the principal stress on the lateral femoral neck in Pauwels type I fracture was a compression stress.Conclusions:The most relevant finding was that hook pinning in Pauwels type III fracture may result in delayed union or nonunion due to significantly increased stress of a traction force at the fracture site that works to displace the fracture. However, in a Pauwels type I fracture, increased compression stress contributes to stabilize it. Surgeons are recommended not to treat Pauwels type III femoral neck fractures by pinning.

Surface roughness calibration services of 16 countries from four metrology regions are compared through measurements of roughness and step height standards. The artefacts circulated include three steps of nominal depths 0.4 µm, 2.4 µm and 10 µm, whereas the roughness sections of both type C and type D profiles have nominal Ra values of 0.2 µm, 0.95 µm, 1.5 µm and 3.1 µm. Two soft-gauges were also circulated for comparison of software independent of hardware. For the steps, parameter d is reported, while for the type C and type D standards and soft-gauges, 14 different roughness parameters are reported between them. Concluding measurements from the pilot in general show good standard stability; however, for some parameters on the artefacts of larger roughness, stability may be considered less certain and this may be an issue in additional outliers in results from the last few laboratories in the schedule. For each parameter, a key comparison reference value (KCRV) is determined using a weighted mean with outliers excluded based on the Birge ratio method until all accepted values form a statistically consistent population. For the five artefacts, out of 35 separate parameters, only ten have good agreement of all submitted results. Where some parameters had to be excluded from the KCRV, some laboratories had consistent problems with particular types of parameter over the different artefacts, while for other laboratories the types of parameters excluded seemed to be random. Comparison of soft-gauge results and artefact results has proven to be inconclusive.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

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