Effect of freezing on the microstructure of a highly decomposed peat material close to water saturation when used prior to X-ray micro computed tomography

Abstract. The modelling of peatland functioning, in particular the impact of anthropogenic warming and direct human disturbance on CO2, CH4 and N2O, requires detailed knowledge of the peat structure and of both water and gas flow with respect to the groundwater table level. To this end, freezing is nowadays increasingly used to obtain small size peat samples for X-ray micro computed tomography (X-ray μ-CT) as required by the need to increase the resolution of the 3D X-ray CT images of the peat structure recorded. The aim of this study was to analyze the structure of a peat material before and after freezing using X-ray μ-CT and to look for possible alterations in the structure by investigating looking at the air-filled porosity. A highly decomposed peat material close to water saturation was selected for study and collected between 25 and 40 cm depth. Two samples 4 × 4 × 7 cm3 in volume were analyzed before and after freezing using an X-ray μ-CT Nanotom 180NF (GE Phoenix X-ray, Wunstorf, Germany) with a 180 kV nanofocus X-ray tube and a digital detector array (2304 × 1152 pixels Hamamatsu detector). Results showed that the continuity and cross section of the air-filled tubular pores several hundreds to about one thousand micrometers in diameter were altered after freezing. Many much smaller air-filled pores not detected before freezing were also recorded after freezing with 470 and 474 pores higher than one voxel in volume (60 × 60 × 60 μm3 in volume each) before freezing, and 4792 and 4371 air-filled pores higher than one voxel in volume after freezing for the two samples studied. Detailed analysis showed that this increase resulted from a difference in the whole range of pore size studied and particularly from a dramatic increase in the number of air-filled pores ranging between 1 voxel (216 103 μm3) and 50 voxels (10.8 106 μm3) in volume. Theoretical calculation of the consequences of the increase in the specific volume of water by 8.7 % when it turns from liquid to solid because of freezing led to the creation of a pore volume in the organic matrix which remains saturated by water when returning to room temperature and consequently to the desaturation of the largest pores of the organic matrix as well as the finest tubular pores which were water-filled before freezing. These new air-filled pores are those measured after freezing using X-ray μ-CT and their volume is consistent with the one calculated theoretically. They correspond to small air-filled ovoid pores several voxels in volume to several dozen voxels in volume and to discontinuous air-filled fine tubular pores which were both detected after freezing. Finally, the increase in the specific volume of water because of freezing appears also be also responsible for the alteration of the already air-filled tubular pores before freezing as shown by the 3D binary images and the pore volume distribution.

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Quantifying the impact of soil compaction on root system architecture in tomato (Solanum lycopersicum) by X-ray micro-computed tomography

Annals of Botany ◽

10.1093/aob/mcs031 ◽

2012 ◽

Vol 110 (2) ◽

pp. 511-519 ◽

Cited By ~ 86

Author(s):

Saoirse R. Tracy ◽

Colin R. Black ◽

Jeremy A. Roberts ◽

Craig Sturrock ◽

Stefan Mairhofer ◽

...

Keyword(s):

Computed Tomography ◽

Root System ◽

Solanum Lycopersicum ◽

System Architecture ◽

Soil Compaction ◽

Root System Architecture ◽

Micro Computed Tomography ◽

X Ray ◽

The Impact

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Assessment of the Density Loss in Anobiid Infested Pine Using X-ray Micro-Computed Tomography

Buildings ◽

10.3390/buildings11040173 ◽

2021 ◽

Vol 11 (4) ◽

pp. 173

Author(s):

João Parracha ◽

Manuel Pereira ◽

António Maurício ◽

Paulina Faria ◽

Daniel F. Lima ◽

...

Keyword(s):

Computed Tomography ◽

Apparent Density ◽

Residual Strength ◽

Pinus Pinaster ◽

Assessment Method ◽

Micro Computed Tomography ◽

X Ray ◽

Definition Of ◽

The Impact ◽

Density Results

The present study aims at evaluating the impact of anobiid damage on pine timber elements. Anobiid attack produces a diffuse damage of the elements with a set of tunnels in random directions and sizes, thus confusing quantification. Therefore, a method was developed based on X-ray micro-computed tomography (μ-XCT) to obtain, for naturally infested timber samples, an empirical correlation between lost material percentage (consumed by beetles) and timber apparent density (original, before degradation—OTD and residual, after degradation—RTD). The quantified density loss can then be used in further assessment of the structure. The results of the tests performed showed high correlation between original apparent density and lost material percentage (r2 = 0.60) and between residual apparent density and lost material percentage (r2 = 0.83), which confirms μ-XCT as a valuable tool to the required quantification. The loss of density results can be further applied on the definition of an assessment method for the evaluation of the residual strength of anobiids infested timber, thus contributing to reducing unnecessary replacement. The optimized procedure of the μ-XCT study for infested Maritime pine (Pinus pinaster) is presented and discussed in this article.

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X-ray micro-computed tomography analysis of impact damage morphology in composite sandwich structures due to cold temperature arctic condition

Journal of Composite Materials ◽

10.1177/0021998318785671 ◽

2018 ◽

Vol 52 (25) ◽

pp. 3509-3522 ◽

Cited By ~ 5

Author(s):

MH Khan ◽

Mohammed Elamin ◽

Bing Li ◽

KT Tan

Keyword(s):

Computed Tomography ◽

Low Temperature ◽

Impact Damage ◽

Fiber Reinforced Polymer ◽

Carbon Fiber Reinforced Polymer ◽

Foam Core ◽

Micro Computed Tomography ◽

X Ray ◽

Reinforced Polymer ◽

The Impact

In this study, X-ray micro-computed tomography is employed to characterize the impact damage mechanisms in foam core sandwiched composites, paying particular attention to the influence of extreme low temperature effects. Investigation on impact response reveals that more energy absorption with lower impact damage force occurs at lower temperature. Results evidently show that test temperature has a significant influence on the impact damage behavior. Post-mortem inspection portrays clear relationships between damages in both foam core and carbon fiber reinforced polymer facesheets, as well as exposed test temperature. Specimens impacted at extreme low temperature (−70℃) exhibit less strength, and higher susceptibility to damage, verified by severer penetration of the impactor. Micro-computed tomography is exploited to examine cross-sectional views of the impacted specimens, showing detailed damage mechanisms of the carbon fiber-reinforced polymer facesheets and the foam core, thereby evidently revealing multiple complex impact damage modes such as fiber breakage, delamination, core shearing and crushing, facesheet-core debonding, which are all strongly influenced by arctic low temperature. The findings of this work will lead to improved design for advanced composite structures with enhanced impact resistance and damage tolerance in extreme cold environment particularly in the arctic region.

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Identification of Fibrotic Thickening as Early Marker of Aortic Valve Stenosis Using X-Ray Micro Computed Tomography and Optical Coherence Tomography

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0036-1571661 ◽

2016 ◽

Vol 64 (S 01) ◽

Author(s):

A. Jannasch ◽

C. Schnabel ◽

M. Santini ◽

S. Fest-Santini ◽

M. Lorenzi ◽

...

Keyword(s):

Computed Tomography ◽

Optical Coherence Tomography ◽

Aortic Valve ◽

Aortic Valve Stenosis ◽

Optical Coherence ◽

Micro Computed Tomography ◽

X Ray ◽

Early Marker

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Morphology and Affinities of Ampelocissites Seeds (Vitaceae: Ampelopsis clade) from the Paleogene of Texas, USA

Systematic Botany ◽

10.1600/036364420x15935294613400 ◽

2020 ◽

Vol 45 (3) ◽

pp. 478-482

Author(s):

Steven R. Manchester

Keyword(s):

Computed Tomography ◽

Cross Sections ◽

Seed Coat ◽

Ct Scanning ◽

Seed Morphology ◽

Early Eocene ◽

Micro Computed Tomography ◽

X Ray ◽

Fossil Seeds ◽

Fossil Genus

Abstract—The type material on which the fossil genus name Ampelocissites was established in 1929 has been reexamined with the aid of X-ray micro-computed tomography (μ-CT) scanning and compared with seeds of extant taxa to assess the relationships of these fossils within the grape family, Vitaceae. The specimens were collected from a sandstone of late Paleocene or early Eocene age. Although originally inferred by Berry to be intermediate in morphology between Ampelocissus and Vitis, the newly revealed details of seed morphology indicate that these seeds represent instead the Ampelopsis clade. Digital cross sections show that the seed coat maintains its thickness over the external surfaces, but diminishes quickly in the ventral infolds. This feature, along with the elliptical chalaza and lack of an apical groove, indicate that Ampelocissites lytlensis Berry probably represents Ampelopsis or Nekemias (rather than Ampelocissus or Vitis) and that the generic name Ampelocissites may be useful for fossil seeds with morphology consistent with the Ampelopsis clade that lack sufficient characters to specify placement within one of these extant genera.

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