Goniometer

About: Goniometer is a research topic. Over the lifetime, 1417 publications have been published within this topic receiving 21750 citations.

A semi-empirical method of absorption correction

Abstract: An extension of Furnas's method is described. The variation of intensity of an axial reflection as the crystal is rotated about the goniometer axis is used to give a curve of relative transmission T against azimuthal angle ϕ for the corresponding reciprocal lattice level. Transmission coefficients for any general reflexion hkl are then given approximately by T(hkl) = [T(ϕinc) + T(ϕret)]/2 where ϕinc and ϕret are the azimuthal angles of the incident and reflected beams. Equations are derived for (ϕinc and ϕret and the accuracy of the method is discussed.

Surface-wetting characterization using contact-angle measurements.

Abstract: Wetting, the process of water interacting with a surface, is critical in our everyday lives and in many biological and technological systems. The contact angle is the angle at the interface where water, air and solid meet, and its value is a measure of how likely the surface is to be wetted by the water. Low contact-angle values demonstrate a tendency of the water to spread and adhere to the surface, whereas high contact-angle values show the surface’s tendency to repel water. The most common method for surface-wetting characterization is sessile-drop goniometry, due to its simplicity. The method determines the contact angle from the shape of the droplet and can be applied to a wide variety of materials, from biological surfaces to polymers, metals, ceramics, minerals and so on. The apparent simplicity of the method is misleading, however, and obtaining meaningful results requires minimization of random and systematic errors. This article provides a protocol for performing reliable and reproducible measurements of the advancing contact angle (ACA) and the receding contact angle (RCA) by slowly increasing and reducing the volume of a probe drop, respectively. One pair of ACA and RCA measurements takes ~15–20 min to complete, whereas the whole protocol with repeat measurements may take ~1–2 h. This protocol focuses on using water as a probe liquid, and advice is given on how it can be modified for the use of other probe liquids.

Two-Dimensional X-Ray Diffraction

Abstract: Preface. 1. Introduction. 1.1 X-Ray Technology and Its Brief History. 1.2 Geometry of Crystals. 1.3 Principles of X-Ray Diffraction. 1.4 Reciprocal Space and Diffraction. 1.5 Two-Dimensional X-Ray Diffraction. 2. Geometry Conventions. 2.1 Introduction. 2.2 Diffraction Space and Laboratory Coordinates. 2.3 Detector Space and Detector Geometry. 2.4 Sample Space and Goniometer Geometry. 2.5 Transformation from Diffraction Space to Sample Space. 2.6 Summary of XRD2 Geometry. References. 3. X-Ray Source and Optics. 3.1 X-Ray Generation and Characteristics. 3.2 X-Ray Optics. References. 4. X-Ray Detectors. 4.1 History of X-Ray Detection Technology. 4.2 Point Detectors in Conventional Diffractometers. 4.3 Characteristics of Point Detectors. 4.4 Line Detectors. 4.5 Characteristics of Area Detectors. 4.6 Types of Area Detectors. 5. Goniometer and Sample Stages. 5.1 Goniometer and Sample Position. 5.2 Goniometer Accuracy. 5.3 Sample Alignment and Visualization Systems. 5.4 Environment Stages. References. 6. Data Treatment. 6.1 Introduction. 6.2 Nonuniform Response Correction. 6.3 Spatial Correction. 6.4 Detector Position Accuracy and Calibration. 6.5 Frame Integration. 6.6 Lorentz, Polarization, and Absorption Corrections. 7. Phase Identification. 7.1 Introduction. 7.2 Relative Intensity. 7.3 Geometry and Resolution. 7.4 Sampling Statistics. 7.5 Preferred Orientation Effect. References. 8. Texture Analysis. 8.1 Introduction. 8.2 Pole Density and Pole Figure. 8.3 Fundamental Equations. 8.4 Data Collection Strategy. 8.5 Texture Data Process. 8.6 Orientation Distribution Function. 8.7 Fiber Texture. 8.8 Other Advantages of XRD2 for Texture. References. 9. Stress Measurement. 9.1 Introduction. 9.2 Principle of X-Ray Stress Analysis. 9.3 Theory of Stress Analysis with XRD2. 9.4 Process of Stress Measurement with XRD2. 9.5 Experimental Examples. Appendix 9.A Calculation of Principal Stresses from the General Stress Tensor. Appendix 9.B Parameters for Stress Measurement. References. 10. Small-Angle X-Ray Scattering. 10.1 Introduction. 10.2 2D SAXS Systems. 10.3 Application Examples. 10.4 Some Innovations in 2D SAXS. References. 11. Combinatorial Screening. 11.1 Introduction. 11.2 XRD2 Systems for Combinatorial Screening. 11.3 Combined Screening with XRD2 and Raman. 12. Quantitative Analysis. 12.1 Percent Crystallinity. 12.2 Crystal Size. 12.3 Retained Austenite. References. 13. Innovation and Future Development. 13.1 Introduction. 13.2 Scanning Line Detector for XRD2. 13.3 Three-Dimensional Detector. 13.4 Pixel Direct Diffraction Analysis. References. Appendix A. Values of Commonly Used Parameters. Appendix B. Symbols. Index.

Reliability of Goniometric Measurements and Visual Estimates of Knee Range of Motion Obtained in a Clinical Setting

Abstract: The purpose of this study was to examine the intratester and intertester reliability for goniometric measurements of knee flexion and extension passive range of motion (PROM). In addition, parallel-forms reliability for PROM measurements of the knee obtained by use of a goniometer and by visual estimation was examined. The intertester reliability for visual estimates of the PROM of the knee was also examined. Repeated measurements were obtained on 43 patients in a clinical setting. The intraclass correlation coefficients (ICCs) for intratester reliability of measurements obtained with a goniometer were .99 for flexion and .98 for extension. Intertester reliability for measurements obtained with a goniometer was .90 for flexion and .86 for extension. The ICCs for parallel-forms reliability for measurements obtained with a goniometer and by visual estimation ranged from .82 to .94. The intertester reliability for measurements obtained by visual estimation was .83 for flexion and .82 for extension. Results suggest clinicians should use a goniometer to take repeated PROM measurements of a patient's knee to minimize the error associated with these measurements.

A comparative assessment of alignment angle of the knee by radiographic and physical examination methods.

Abstract: Objective To compare the knee-alignment angle from a full-limb radiograph (mechanical axis) with the anatomic-axis angle as measured by physical examination using a goniometer and by 2 other radiographic methods. Methods The knee-alignment angle was measured in 114 knees of 57 subjects who had radiographic osteoarthritis (OA), with a Kellgren/Lawrence grade of ≥1 in at least one knee. The mechanical axis was defined as the angle formed by the intersection of 2 lines, one from the center of the head of the femur to the center of the tibial spines, and a second from the center of the talus to the center of the tibial spines. The anatomic axis was defined as the angle formed by 2 lines, each originating from a point bisecting the femur and tibia and converging at the center of the tibial spine tips. The anatomic-axis angle was measured by 3 methods: 1) physical examination using a goniometer, 2) a posteroanterior (PA) fixed-flexion knee radiograph (anatomicPA axis), and 3) an anteroposterior (AP) full-limb radiograph (anatomicAP axis). Results Significant correlations were found between the mechanical-axis angle and the anatomic-axis angle measured by each of the 3 methods: by goniometer (r = 0.70, P < 0.0001), by anatomicPA axis (r = 0.75, P < 0.0001), and by anatomicAP axis (r = 0.65, P < 0.0001). The anatomic axis was offset a mean 4.21° valgus from the mechanical axis (3.5° in women, 6.4° in men), which was consistent across all methods. Conclusion Knee alignment assessed clinically by goniometer or measured on a knee radiograph is correlated with the angle measured on the more cumbersome and costly full-limb radiograph. These alternative measures have the potential to provide useful information regarding the risk of progression of knee OA when a full-limb radiograph is not available.