scholarly journals Fibre directions at a branch-stem junction in Norway spruce: a microscale investigation using X-ray computed tomography

2022 ◽  
Author(s):  
Min Hu ◽  
Anders Olsson ◽  
Stephen Hall ◽  
Thomas Seifert
Keyword(s):  
Norway Spruce ◽  
Wood Specimen ◽  
Radius Of Curvature ◽  
Continuous Change ◽  
Fibre Direction ◽  
Voxel Size ◽  
X Ray ◽  
Original Specimen ◽  
Resolution Level ◽  
Four Levels

AbstractThe connection between branch and trunk in a tree must be strong enough to transfer all loads acting on the branch, and it is well known that such branch-stem connections are indeed very strong. In this paper, X-ray computer tomography is employed to investigate the local fibre orientation in the close surrounding of a knot in a Norway spruce specimen to better understand the origins of the mechanical strength of the branch-trunk connection. First, a wood specimen containing an entire knot from pith to bark was imaged with a voxel size of 52 µm. Subsequently, smaller specimens were cut from this original specimen and imaged again with increasingly higher resolution over four levels. With the highest resolution level (2.6 µm voxel size), the tracheids with smallest lumen were successfully traced. The results revealed how the direction of the fibre paths that start below the knot curve around it as the paths progress upwards to the region just above the knot, where the paths divide into two: one set of paths integrating with the knot on its top side and the other set continuing up along the trunk. Fibres that integrate with the knot at its top follow paths just before they continue into the knot, with a radius of curvature of only about 1 mm in both vertical and horizontal directions. No abrupt change of fibre pattern between latewood and earlywood is observed; rather, a continuous change of fibre direction across annual layers can be seen. The detailed characterisation of the local fibre structure around the knot provides new data that can explain the remarkable strength of the branch-trunk connection.

A Study of the Effect of Extended Hounsfield Unit Range and Voxel Size on Defect Detection in Friction Stir Welds

2020 ◽  
Author(s):  
Ahmad M. R. Baydoun ◽  
Ramsey F. Hamade
Keyword(s):  
Gamma Rays ◽  
Dissimilar Materials ◽  
Hounsfield Unit ◽  
Ct Scanning ◽  
Ultrasonic Waves ◽  
X Rays ◽  
Internal Defects ◽  
Voxel Size ◽  
X Ray ◽  
Friction Stir

Abstract Friction stir welding (FSW) is a novel welding method that is garnering attention, in part, due to its ability to join dissimilar materials. One of the challenges in producing dissimilar friction welded joints is ensuring the welds are defect-free. Nondestructive testing (NDT) methods such as ultrasonic waves, gamma rays, X-rays, and X-ray CT, are gaining popularity as a method to detect internal defects in FSW joints. In this study, dissimilar AA1050-AA6061-T6 FSW lap welds are Manufactured and then examined using an NDT X-ray CT technique. The effects of two critical X-ray CT scanning parameters (voxel size and Hounsfield unit (HU)) on the detection of internal defects are investigated. The samples are scanned via X-ray CT at two different voxel sizes (2.457 E−02 and 1.420 E−03 mm3) and two HU ranges (12-bit and 16-bit depth). The generated Digital Imaging and Communications in Medicine (DICOM) images are segmented based on a proper HU threshold found via the Otsu thresholding method. The findings show that Small voxel size (higher resolution) improves the ability of detecting internal defects and improves the effectiveness of the thresholding process. Higher HU range results in a wider separation between detected material peaks, thus enhancing the effectiveness of the thresholding process as well.

Linear parabolic single-crystal diamond refractive lenses for synchrotron X-ray sources

2017 ◽  
Vol 24 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Sergey Terentyev ◽  
Maxim Polikarpov ◽  
Irina Snigireva ◽  
Marco Di Michiel ◽  
Sergey Zholudev ◽  
...  
Keyword(s):  
Single Crystal ◽  
Focal Spot ◽  
Synthetic Diamond ◽  
Picosecond Laser ◽  
Radius Of Curvature ◽  
High Quality ◽  
X Ray ◽  
Single Crystal Diamond ◽  
Refractive Lens ◽  
Focusing Properties

Linear parabolic diamond refractive lenses are presented, designed to withstand high thermal and radiation loads coming from upgraded accelerator X-ray sources. Lenses were manufactured by picosecond laser treatment of a high-quality single-crystal synthetic diamond. Twelve lenses with radius of curvature at parabola apex R = 200 µm, geometrical aperture A = 900 µm and length L = 1.5 mm were stacked as a compound refractive lens and tested at the ESRF ID06 beamline. A focal spot of size 2.2 µm and a gain of 20 were measured at 8 keV. The lens profile and surface quality were estimated by grating interferometry and X-ray radiography. In addition, the influence of X-ray glitches on the focusing properties of the compound refractive lens were studied.

Structural and superconducting properties of melt-grown Y–Ba–Cu–O superconductors

1996 ◽  
Vol 11 (10) ◽  
pp. 2406-2415 ◽  
Author(s):  
R. Gopalan ◽  
T. Rajasekharan ◽  
T. Roy ◽  
G. Rangarajan ◽  
V. Ganesan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Strain Field ◽  
Crack Width ◽  
Growth Process ◽  
Critical Radius ◽  
Radius Of Curvature ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

YBa2Cu3O7 (123) samples with varying Y2BaCuO5 (211) concentrations (0 mol%, 20 mol%, 28 mol%, and 50 mol%) were synthesized by the melt-growth process. Microstructural characterizations were done using x-ray diffraction (XRD), optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). It was found that 123 platelet width, crack width between the platelets, and 211 particle size decreased systematically with increasing 211 concentration. TEM study showed that there is a critical radius of curvature (rc ≤ 0.2 μm-0.3 μm) of the 123/211 interface where defects/contrasts of strain field start to appear, and these defects are believed to be responsible for pinning the magnetic flux. Microhardness measurements showed that Vickers hardness (VHN) increases with increasing 211 content. Critical current density (Jc) values obtained from magnetization measurements using a SQUID magnetometer were found to increase in melt-grown samples by the addition of 211 content.

scholarly journals Selection of CVD Diamond Crystals for X-ray Monochromator Applications Using X-ray Diffraction Imaging

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 396 ◽  
Author(s):  
Stanislav Stoupin ◽  
Thomas Krawczyk ◽  
Zunping Liu ◽  
Carl Franck
Keyword(s):  
Spline Interpolation ◽  
Cvd Diamond ◽  
Effective Radius ◽  
Radius Of Curvature ◽  
X Ray Diffraction ◽  
Average Width ◽  
Rocking Curve ◽  
X Ray ◽  
Single Crystal Diamond ◽  
Diffraction Imaging

A set of 20 single crystal diamond plates synthesized using chemical vapor deposition (CVD) was studied using X-ray diffraction imaging to determine their applicability as side-bounce (single-reflection) Laue monochromators for synchrotron radiation. The crystal plates were of optical grade (as provided by the supplier) with (001) nominal surface orientation. High dislocation density was found for all samples. Distortions in the crystal lattice were quantified for low-index Laue reflections of interests using rocking curve topography. Maps of effective radius of curvature in the scattering plane were calculated using spline interpolation of the rocking curve peak position across the studied plates. For several selected plates, nearly flat regions with large effective radius of curvature were found ( R 0 ≳ 30 - 70 m, some regions as large as 1 × 4 mm 2 ). The average width of the rocking curve for these regions was found to be about 150 μ rad (r.m.s.). These observations suggest that the selected CVD diamond plates could be used as intermediate-bandwidth monochromators refocusing the radiation source to a specific location downstream with close to 1:1 distance ratio.

scholarly journals Comparison of the Efficacy of Different Fluoride Varnishes on Dentin Remineralization During a Critical pH Exposure Using Quantitative X-Ray Microtomography

2018 ◽  
Vol 43 (6) ◽  
pp. E308-E316
Author(s):  
A Sleibi ◽  
A Tappuni ◽  
D Mills ◽  
GR Davis ◽  
A Baysan
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Mineral Content ◽  
Test Group ◽  
Control Group ◽  
Mineral Concentration ◽  
Voxel Size ◽  
X Ray ◽  
Casein Phosphopeptide

SUMMARY Objectives: The objective of this in vitro study was to quantify the amount of mineral change in demineralized dentin at pH 5.5 after the application of dental varnishes containing fluoride with casein phosphopeptide–amorphous calcium phosphate, fluoride and bioglass, or fluoride alone. Methods and Materials: A total of 12 extracted human sound mandibular premolar root samples were coated with an acid-resistant varnish, leaving a 2 × 3 mm window at the outer root surface. These root specimens were then randomly divided into four groups and separately subjected to the demineralizing cycle at a pH of 4.8 for five days to create artificial caries-like lesions in dentin. Subsequently, each sample was imaged using quantitative x-ray microtomography (XMT) at a 15-μm voxel size. Each test group then received one of the following treatments: dental varnish containing casein phosphopeptide–amorphous calcium phosphate and fluoride (CPP-ACP, MI varnish, GC Europe), bioglass and fluoride (BGA, Experimental, Dentsply Sirona), or fluoride alone (NUPRO, Dentsply Sirona), as well as a control group, which received no treatment. These samples were kept in deionized water for 12 hours. The thin layer of varnish was then removed. All samples including the nonvarnish group were subjected to the second demineralizing cycle at pH 5.5 for five days. The final XMT imaging was then carried out following the second demineralizing cycle. XMT scan was also carried out to varnish samples at 25 μm voxel size. The change in mineral concentration in the demineralized teeth was assessed using both qualitative and quantitative image analysis. Results: There was an increase in radiopacity in the subtracted images of all varnish groups; a significant increase in mineral content, 12% for the CPP-ACP and fluoride (p≤0.05 and p≤0.001), 25% BGA (p≤0.001), and 104% fluoride alone varnish (p≤0.001). There was an increase in the size of radiolucency in the lesion area with a significant decrease in mineral content in the nonvarnish group, 10% (p≤0.05 and p≤0.001). Conclusions: There was encouraging evidence of a remineralization effect following the application of dental varnish on dentin and also an observed resistance to demineralization during the acidic challenge in all cases. However, a dental varnish containing fluoride alone appeared to have a much greater effect on dentin remineralization when compared with CPP-ACP with fluoride and bioglass with fluoride.

Predicting the Stiffness of Sawn Products by X-ray Scanning of Norway Spruce Saw Logs

2001 ◽  
Vol 16 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Johan Oja ◽  
Stig Grundberg ◽  
Anders Grönlund
Keyword(s):  
Norway Spruce ◽  
X Ray

An X-ray Microtomographic Study of Natural White-spot Enamel Lesions

2011 ◽  
Vol 91 (2) ◽  
pp. 185-191 ◽  
Author(s):  
N.J. Cochrane ◽  
P. Anderson ◽  
G.R. Davis ◽  
G.G. Adams ◽  
M.A. Stacey ◽  
...  
Keyword(s):  
Surface Layer ◽  
Mineral Content ◽  
White Spot ◽  
Line Profiles ◽  
Surface Layers ◽  
Voxel Size ◽  
Early Presentation ◽  
X Ray ◽  
Non Invasive ◽  
Surface Layer Thickness

White-spot enamel lesions are an early presentation of dental caries and are ideally managed by non-invasive procedures. The aim of this study was to characterize white-spot enamel lesions by x-ray microtomography. In particular, mineral content across the lesion from the surface to the base of the lesion was measured and surface layers defined. Molars with long buccal white-spot enamel lesions were collected, photographed, and each sectioned to produce 3 500-µm-thick sections. The sections were mounted and imaged by quantitative x-ray microtomography at a 15-µm voxel size. We analyzed line profiles through the middle of each 3D image to determine mineral content and depth. The surface layer thickness of the lesions ranged from 35 to 130 µm, with the maximum mineral content in this layer being 74% to 100% of that of sound enamel. The average mineral content across the lesions ranged from 1.73 to 2.48 g/cm3. No significant differences could be found between lesions clinically categorized as active and those categorized as inactive. However, for depth-matched active and inactive lesions, the active lesions exhibited a more porous surface layer than the inactive lesions. White-spot enamel lesions are highly variable, with surface layers of considerable thickness.

Nanosecond Exposure Time Soft X-Ray Contact Imaging

1985 ◽  
Vol 43 ◽  
pp. 600-601
Author(s):  
R. J. Rosser
Keyword(s):  
High Resolution ◽  
Light Microscopy ◽  
Visible Light ◽  
Biological Material ◽  
Electronics Industry ◽  
Recording Medium ◽  
Contact Printing ◽  
X Ray ◽  
Original Specimen ◽  
Recording Material

Soft x-ray contact microscopy has been pursued for many years because of the potential advantages of 1 to 10 nm electro-magetic radiation for imaging biological materials. These are the lower damage and greater penetration than electrons and considerably higher resolution than visible light microscopy, both possible without exotic optics.The technique is similar to contact printing. The object to be viewed is placed as close as possible to the recording medium which is then exposed to a suitable x-ray source.. The sample is removed from the recording medium which is then chemically developed. The result is map of the x-ray opacity of the original specimen.The high resolution has only become reality in recent years with the use of x-ray photo-resists as the recording material. These were origionally developed for use in the electronics industry but have been used for contact images of biological material.

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