scholarly journals Evolving fracture patterns: columnar joints, mud cracks and polygonal terrain

2013 ◽  
Vol 371 (2004) ◽  
pp. 20120353 ◽  
Author(s):  
Lucas Goehring
Keyword(s):  
Thin Layer ◽  
Crack Formation ◽  
Thick Layer ◽  
Crack Pattern ◽  
Crack Network ◽  
Rectilinear Crack ◽  
Crack Patterns ◽  
Fracture Patterns ◽  
Previous Cycle ◽  
Columnar Joints

When cracks form in a thin contracting layer, they sequentially break the layer into smaller and smaller pieces. A rectilinear crack pattern encodes information about the order of crack formation, as later cracks tend to intersect with earlier cracks at right angles. In a hexagonal pattern, in contrast, the angles between all cracks at a vertex are near 120°. Hexagonal crack patterns are typically seen when a crack network opens and heals repeatedly, in a thin layer, or advances by many intermittent steps into a thick layer. Here, it is shown how both types of pattern can arise from identical forces, and how a rectilinear crack pattern can evolve towards a hexagonal one. Such an evolution is expected when cracks undergo many opening cycles, where the cracks in any cycle are guided by the positions of cracks in the previous cycle but when they can slightly vary their position and order of opening. The general features of this evolution are outlined and compared with a review of the specific patterns of contraction cracks in dried mud, polygonal terrain, columnar joints and eroding gypsum–sand cements.

Three-Dimensional Analysis of Enamel Crack Behavior Using Optical Coherence Tomography

2016 ◽  
Vol 96 (3) ◽  
pp. 308-314 ◽  
Author(s):  
M.S. Segarra ◽  
Y. Shimada ◽  
A. Sadr ◽  
Y. Sumi ◽  
J. Tagami
Keyword(s):  
Optical Coherence Tomography ◽  
Crack Pattern ◽  
Type I ◽  
Optical Coherence ◽  
Type Ii ◽  
Human Teeth ◽  
Posterior Teeth ◽  
Crack Patterns ◽  
Type Iii ◽  
Crack Behavior

The aim of this study was to nondestructively analyze enamel crack behavior on different areas of teeth using 3D swept source-optical coherence tomography (SS-OCT). Ten freshly extracted human teeth of each type on each arch ( n = 80 teeth) were inspected for enamel crack patterns on functional, contact and nonfunctional, or noncontact areas using 3D SS-OCT. The predominant crack pattern for each location on each specimen was noted and analyzed. The OCT observations were validated by direct observations of sectioned specimens under confocal laser scanning microscopy (CLSM). Cracks appeared as bright lines with SS-OCT, with 3 crack patterns identified: Type I – superficial horizontal cracks; Type II – vertically (occluso-gingival) oriented cracks; and Type III – hybrid or complicated cracks, a combination of a Type I and Type III cracks, which may or may not be confluent with each other. Type II cracks were predominant on noncontacting surfaces of incisors and canines and nonfunctional cusps of posterior teeth. Type I and III cracks were predominant on the contacting surfaces of incisors, cusps of canines, and functional cusps of posterior teeth. Cracks originating from the dental-enamel junction and enamel tufts, crack deflections, and the initiation of new cracks within the enamel (internal cracks) were observed as bright areas. CLSM observations corroborated the SS-OCT findings. We found that crack pattern, tooth type, and the location of the crack on the tooth exhibited a strong correlation. We show that the use of 3D SS-OCT permits for the nondestructive 3D imaging and analysis of enamel crack behavior in whole human teeth in vitro. 3D SS-OCT possesses potential for use in clinical studies for the analysis of enamel crack behavior.

A Polarized Light Analysis of the Human Red Cell Ghost

1953 ◽  
Vol 30 (3) ◽  
pp. 397-432
Author(s):  
J. M. MICHISON
Keyword(s):  
Cell Membrane ◽  
Thin Layer ◽  
Polarized Light ◽  
Radial Distance ◽  
Thick Layer ◽  
Red Cell ◽  
Red Cell Membrane ◽  
Cell Ghost ◽  
Protein Gel ◽  
Good Agreement

1. A new method is described for measuring the thickness of thin spherical birefringent membranes. It consists of measuring a curve of retardation against radial distance at the edge of the membrane, and comparing this curve with other curves calculated from theory for membranes of known thickness. Diffraction is taken into account. 2. This method shows that the wet thickness of the human red cell ghost in glycerol is about 0.5µ. A good agreement with the experimental results would be given by a model membrane consisting of a weakly birefringent layer 0.5µ. thick surrounded by a strongly birefringent layer 40 A. thick. It is suggested that the thick layer is a 2 % protein gel, and that the thin layer is a bimolecular layer of lipids. 3. The birefringence indicates that there is radial molecular and tangential micellar orientation in the protein gel. This can be explained by an arrangement of the protein chains in looped bundles. 4. On the basis of these results a new model is put forward for the structure of the red cell membrane, and some of its implications are discussed.

Comparison of Different Soil Leaching Techniques with Four Herbicides

Weed Science ◽  
1975 ◽  
Vol 23 (6) ◽  
pp. 508-511 ◽  
Author(s):  
Chu-Huang Wu ◽  
P. W. Santelmann
Keyword(s):  
Thin Layer ◽  
Column Chromatography ◽  
Waiting Times ◽  
Thick Layer ◽  
Working Hours ◽  
Laboratory Methods ◽  
Thin Layer Method ◽  
Rf Values ◽  
Layer Chromatography ◽  
Herbicide Mobility

Herbicide mobility in soils was compared by three laboratory methods. The Rf values calculated from soil thin-layer chromatography correlated closely with those obtained from soil thick-layer chromatography (r = 0.96). Herbicides leached slightly further in slotted column chromatography as compared with the other methods. The working hours required to conduct a study with each method were in the increasing order of thin-layer, thick-layer, and column chromatography. However, the thin-layer method required the longest waiting times, followed by the column and thick-layer chromatography. If radioactive herbicides are not available or obtainable, the thick-layer chromatography is simplest and quickest. The relative mobility of herbicides studied was fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] > napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] > terbutryn [2-(tert-butyl-amino)-4-(ethylamino)-6-(methylthio)-s-triazine] > trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine). Less herbicide mobility was observed in heavier soil than in sandy soil.

Resin production and glandular hairs in Beyeria viscosa (Labill.) Miq. (Euphorbiaceae)

1974 ◽  
Vol 22 (2) ◽  
pp. 195 ◽  
Author(s):  
B Dell ◽  
AJ Mccomb
Keyword(s):  
Endoplasmic Reticulum ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Thick Layer ◽  
Dry Weight ◽  
Young Leaf ◽  
Mesophyll Cells ◽  
Glandular Hairs ◽  
Resin Layer ◽  
Layer Chromatography

Leaves of Beyeria viscosa secrete resin with components related to the gibberellins. Two-celled glandular hairs are well developed on the young leaf, and are coated with a thick layer of resin, which makes up almost half the dry weight associated with the young leaf. Plastids of the glandular hairs have poorly developed internal membranes but are enveloped in tubules, apparently derived from endoplasmic reticulum. As the leaf expands, resin secretion ceases; the resin layer is torn apart and is seen largely as caps over the hairs. Resin accounts for some 20% of the dry weight associated with the mature leaf. Resin components also accumulate in the epidermis and certain mesophyll cells. No significant changes take place in the chemistry of the secreted components as the leaves mature, as seen by thin-layer chromatography.

scholarly journals Visualisasi Dan Identifikasi Pola Retak Dinding Bata Akibat Penurunan Pondasi Struktur Bangunan Di Kota Banjarmasin

2018 ◽  
Vol 2 (1) ◽  
pp. 61
Author(s):  
Darmansyah Tjitradi ◽  
Eliatun Eliatun
Keyword(s):  
Stress Distribution ◽  
Crack Pattern ◽  
Foundation Settlement ◽  
Brick Wall ◽  
Building Structure ◽  
Structural Elements ◽  
Structural Components ◽  
Crack Patterns ◽  
Longitudinal Cracks ◽  
The City

The City of Banjarmasin has very low soil bearing capacity leading to a significant number of buildings experiencing foundation settlement. This causes many elements of the buildings to develop cracks and to lean. The foundation settlement is modelled using ANSYS by taking five building structure models with brick walls loaded with their selves weight. Through this modelling the crack pattern and the stress distribution on both walls and the structural elements can be visualised and identified. The results show that the following columns experiencing foundation settlement develop longitudinal cracks, crack patterns on brick walls are diagonal at every bottom corner of the columns and vertical at the edge of the inner columns if there is no foundation settlement. Crack patterns on brick walls take form of a letter V if only one or two outer column experience foundation settlement, and crack patterns on brick walls also take form of an inverted letter V if only the inner columns or two adjacent columns experience foundation settlement. Foundation settlement experienced by inner columns of a brick wall is a major cause of damage to structural components.

Performance of a Direct Bonded Sub-Millimeter Peek Coating for Hydrodynamic Plain Bearings

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Christoph Weißbacher ◽  
Angelika Kiefel ◽  
Hardwig Blumenthal ◽  
Jonas Marheineke ◽  
Sebastien Piton
Keyword(s):  
Thin Layer ◽  
Steel Substrate ◽  
Thick Layer ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Sample Test ◽  
And Behavior ◽  
Peek Coating ◽  
Very High ◽  
Mild Steel Substrate

Abstract Despite their superior tribological properties, thick-layer bearing coatings based on polyetheretherketone (PEEK) have up to now not been applied in a very high number of plain bearings for industrial applications. This can at least partly be credited to the high costs and low flexibility associated with the coating process for these materials. At the same time, while thick-layer polytetrafluoroethylene (PTFE) coatings have been successfully applied in industrial plain bearings for around 50 years, thin-layer PTFE coatings today constitute the majority of applications of PTFE in plain bearings. It is therefore reasonable to assume a similar approach for thin-layer PEEK coatings. This article reports the performance of a thin-layer PEEK coating directly applied on a mild steel substrate, with results ranging from first sample test through component tests to application in an actual machine and behavior during realistic operating conditions and induced bearing failure.

scholarly journals Geometric Attributes of Polygonal Crack Patterns in Columnar Joints

2020 ◽  
Author(s):  
Yuri Akiba ◽  
Aika Takashima ◽  
Akio Inoue ◽  
Hiroshi Ishidaira ◽  
Hiroyuki Shima
Keyword(s):  
Crack Patterns ◽  
Columnar Joints

Gold Nanolayers Prepared on Poly(ethyleneterephtalate)

2007 ◽  
Vol 567-568 ◽  
pp. 261-264
Author(s):  
Jakub Siegel ◽  
Petr Slepička ◽  
Vladimír Kotál ◽  
Miroslava Novotná ◽  
Olga Bláhová ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Modification ◽  
Thin Layer ◽  
Plasma Treatment ◽  
Ftir Spectroscopy ◽  
Surface Topography ◽  
Thick Layer ◽  
Gold Coating ◽  
Experimental Conditions ◽  
Water Etching

Ablation, water etching and gold coating were studied on poly(ethyleneterephtalate) (PET) exposed to DC Ar plasma for 240 s at 8.3 W power. Au layers were sputtered on pristine and modified PET and their adhesion and topography were investigated. The roughness and changes of topography after plasma treatment, subsequent water etching and gold coating were followed using AFM microscopy. The thicknesses of ablated layer and water dissolved layer were determined using gravimetry. A nanoindentor was used to perform microstratch tests of sputtered layers. Water dissolving of thin layer after plasma treatment was confirmed by FTIR spectroscopy. We have found that under the present experimental conditions ca 30 nm thick layer of PET is plasma ablated. The surface topography changes dramatically and surface roughness increases. Another ca 16 nm thick layer was removed under present laboratory conditions after 24hour water etching. Subsequent coating with 50 nm thick gold layer increases surface roughness in all cases of surface modification.

Potential of the Ultra-thin Layer Fabricated by Wet-process as a Pore-seal for Porous Low-k Films

2010 ◽  
Vol 1249 ◽  
Author(s):  
Shoko Sugiyama Ono ◽  
Kazuo Kohmura ◽  
Hirofumi Tanaka ◽  
Kentaro Nakayama ◽  
Akifumi Kagayama ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thick Layer ◽  
Ph Control ◽  
Adhesion Property ◽  
Wet Process ◽  
Mobile Ions ◽  
Low K

AbstractWe succeeded in fabricating ultra-thin (<3 nm-thick) layer on top of the surface of porous low-k. The roughness of the surface of porous low-k remains homogeneous even after covering by the thin layer. Furthermore, we found that such ultra-thin layer suppresses the diffusion of metal into porous low-k film. Concerning adhesion property, the abrasion between the thin layer and copper was not detected after annealing at 350 deg C in forming gas. TVS measurement suggested that pH control of solution is the key to reduce damages of porous low-k and mobile ions. We believe that such ultra-thin layer, which we propose here, has a potential as a pore seal layer for porous low-k films.

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