scholarly journals Tooth Structure and Replacement of the Triassic Keichousaurus (Sauropterygia, Reptilia) From South China

2021 ◽  
Vol 9 ◽  
Author(s):  
Jun-ling Liao ◽  
Tian Lan ◽  
Guang-hui Xu ◽  
Ji Li ◽  
Yan-jiao Qin ◽  
...  
Keyword(s):  
South China ◽  
Cross Sections ◽  
Detailed Examination ◽  
Tooth Structure ◽  
Marine Reptiles ◽  
New Information ◽  
Functional Tooth ◽  
Tooth Histology ◽  
Computed Microtomography ◽  
Marine Reptile

The small-sized sauropterygian Keichousaurus hui was one of the most abundant marine reptiles from the Triassic Yangtze Sea in South China. Although Keichousaurus has been studied in many aspects, including the osteology, ontogeny, sexual dimorphism, and reproduction, the dentition of this marine reptile was only briefly described in external morphology. In this study, we provide new information on Keichousaurus tooth implantation, histology, and replacement based on a detailed examination of well-preserved specimens collected in the past decades. The tooth histology has been investigated for the first time by analyzing cross-sections of premaxillary teeth and the tooth attachment and implantation have been further revealed by X-ray computed microtomography. We refer the tooth replacement of Keichousaurus to the iguanid replacement type on the basis of the observed invasion of small replacement tooth into the pulp cavity of the functional tooth. Given the resemblance to other extinct and modern piscivorous predators in the morphology and structure of teeth, Keichousaurus might mainly feed on small or juvenile fishes and some relatively soft-bodied invertebrates (e.g., mysidacean shrimps) from the same ecosystem.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

Fluorine binding with dentin adjacent to fluoride-containing luting materials

2017 ◽  
Vol 27 (01n02) ◽  
pp. 1-9 ◽  
Author(s):  
K. Okuyama ◽  
Y. Tamaki ◽  
H. Yamamoto ◽  
K. Yagi ◽  
M. Hayashi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Calcium Concentration ◽  
Acrylic Resin ◽  
Caries Prevention ◽  
The Other ◽  
Fluoride Release ◽  
Tooth Root ◽  
Tooth Structure ◽  
Dentin Surface ◽  
Acid Solubility

Tooth-bound (KOH-insoluble) fluoride contributes to caries prevention because of its low acid solubility and long retention within tooth structure. The purpose of this study was to evaluate tooth-bound fluoride in dentin, taken up from fluoride-containing luting materials, using an in-air [Formula: see text]PIXE/PIGE system. The dentin surface of tooth root cross-sections and an acrylic resin were cemented with four different fluoride-containing luting materials. Specimens were stored in a remineralizing solution for 4 or 8 weeks and then sectioned into two slices. Two adjacent slices were used for measurement of fluorine and calcium concentration using in-air [Formula: see text]PIXE/PIGE. For analysis of the KOH-insoluble fluoride ((KOH(+)), one slice was immersed in 1 mol/L KOH solution for 24 h. The other slice was not treated with KOH in order to analyze KOH-soluble and -insoluble fluoride (whole fluoride, KOH(−)). KOH(+) levels were lower than KOH(−) levels for all materials at both duration periods. Higher concentration of fluorine was detected at deeper areas in the 8-week groups than in the 4-week groups for all materials. The material, which has the largest fluoride release, shows the lowest ratio of KOH(+) to KOH(−). PIXE/PIGE analysis confirmed the presence of tooth-bound fluoride in dentin adjacent to fluoride-containing luting materials.

scholarly journals Computed microtomography in the analysis of fiber migration in yarn

2013 ◽  
Vol 13 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Marta Toda ◽  
Katarzyna Ewa Grabowska
Keyword(s):  
Cross Sections ◽  
Two Dimensional ◽  
X Ray ◽  
Testing Method ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Nondestructive Testing Method ◽  
2D And 3D ◽  
Migration Testing ◽  
Non Destructive

Abstract This study is a short analysis of the use of computer microphotography in fiber migration testing as a modern nondestructive testing method. Microtomography operates similarly to X-ray computed tomography systems used in medicine, but with much better resolution owing to the use of a smaller radiation spot. The internal structure is reconstructed as a series of two-dimensional cross-sections that are then used to create 2D and 3D morphological objects. This process is non-destructive and does not require special preparation of a testing material.

Electron–ion interactions for trapped highly charged Ge ions

2006 ◽  
Vol 84 (1) ◽  
pp. 67-81 ◽  
Author(s):  
G Machtoub ◽  
J.R. Crespo López-Urrutia ◽  
X Zhang ◽  
H Tawara
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Ion Trap ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Theoretical Simulation ◽  
X Ray ◽  
New Information ◽  
Excitation Processes

A theoretical simulation of complex K X-ray spectra including those from dielectronic recombination and excitation processes is presented for trapped highly charged germanium ions ( Geq+, q = 27–30) interacting with a dense electron beam. We carried out numerical calculations of transition rates, level energies, transition wavelengths, resonance and collision strengths, and satellite intensity factors. Analytical results related to cross sections of B- through He-like Ge ions were obtained as well. The simulated spectra, including the contribution from different charge states of Ge27+–Ge30+, show good overall agreement over a wide electron energy range with the available X-ray measurements from the Heidelberg electron beam ion trap (EBIT). We have also predicted the electron impact excitation cross-section ratios for different transitions of Ge29+ and Ge30+ ions. It should be emphasized that the present analysis can also provide new information and clues of possible temperature measurements for EBIT and other plasma diagnostics.PACS No.: 32.30.Rj

The Middle Triassic marine reptile biodiversity in the Germanic Basin, in the centre of the Pangaean world

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Cajus Diedrich
Keyword(s):  
Middle Triassic ◽  
Coastal Areas ◽  
Skeletal Remains ◽  
Southern Germany ◽  
Shallow Marine ◽  
Germanic Basin ◽  
Marine Reptiles ◽  
Marine Habitats ◽  
Reptile Species ◽  
Marine Reptile

AbstractThe Middle Triassic fossil reptile localities near Bayreuth (Bavaria, southern Germany) consist of shallow marine autochthonous glauconitic marls and terebratulid-rich tempestite carbonates of the newly defined Bindlach and Hegnabrunn formations. Single bones and incomplete skeletons of marine reptiles have been recorded in bone beds within in the Illyrian and Fassanian stages. These include the remains of the sauropterygians Neusticosaurus sp., Lariosaurus cf. buzzii [1], Nothosaurus mirabilis [2], Paranothosaurus giganteus [2], Placodus gigas [3], Cyamodus rostratus [4], Cyamodus münsteri [5], Pistosaurus longaevus [6], and ichthyosaursOmphalosaurus sp., and Shastasaurus sp. or proterosaur Tanystrophaeus conspicuus [7]. New skeletal reconstructions are based on the osteological analysis of three dimensionally preserved bones and skeletal remains. The large number of marine endemic placodont macroalgae feeders (P. gigas) in the Bayreuth sites coincides with the presence of invertebrate palaeocommunities that are characteristic of macroalgae meadow paleoenvironments. Most of the reptile species and genera from the Bayreuth localities also occur in beds of similar ages from the Monte San Giorgio (Switzerland/Italy) or Perledo (Italy) lagoonal areas. Ichthyosaurs and pistosaurs were adapted for open marine conditions, and may have migrated from the Panthalassa Oceans into the shallow marine Germanic Basin to reproduce, whereas placodonts and many other sauropterygians seem to have lived permanently in those shallow marine habitats, with large squamates and thecodont or smaller archosaurs in coastal areas.

Maastrichtian marine reptiles of the Mediterranean Tethys: a palaeobiogeographical approach

2012 ◽  
Vol 183 (6) ◽  
pp. 573-596 ◽  
Author(s):  
Nathalie Bardet
Keyword(s):  
New Jersey ◽  
Northern Margin ◽  
Marine Reptiles ◽  
Global Comparison ◽  
The Mediterranean ◽  
And Cluster Analysis ◽  
Marine Reptile ◽  
Warm Temperate ◽  
Relative Scarcity ◽  
Southern Tethys

AbstractA global comparison of coeval Maastrichtian marine reptiles (squamates, plesiosaurs, chelonians and crocodyliformes) of Europe, New Jersey, northwestern Africa and Middle-East has been performed. More than twenty outcrops and fifty species (half of them being mosasaurids) have been recorded. PEA and Cluster Analysis have been performed using part of this database and have revealed that marine reptile faunas (especially the mosasaurid ones) from the Mediterranean Tethys are clearly segregated into two different palaeobiogeographical provinces: 1) The northern Tethys margin province (New Jersey and Europe), located around palaeolatitudes 30-40°N and developping into warm-temperate environments, is dominated by mosasaurid squamates and chelonioid chelonians; it is characterized by the mosasaurid association of Mosasaurus hoffmanni and Prognathodon sectorius. 2) The southern Tethys margin province (Brazil and the Arabo-African domain), located between palaeolatitudes 20°N-20°S and developping into intertropical environments, is dominated by mosasaurid squamates and bothremydid chelonians; it is characterized by the mosasaurid association of Globidens phosphaticus as well as by Halisaurus arambourgi and Platecarpus (?) ptychodon (Arabo-African domain). These faunal differences are interpreted as revealing palaeoecological preferences probably linked to differences in palaeolatitudinal gradients and/or to palaeocurrents.On a palaeoecological point on view and concerning mosasaurids, the mosasaurines (Prognathodon, Mosasaurus, Globidens and Carinodens) prevail on both margins but with different species. The ichthyophageous plioplatecarpines Plioplatecarpus (Northern margin) and Platecarpus (?) ptychodon (Southern margin) characterise respectively each margin. The halisaurine Halisaurus is present on both margins but with different species. Of importance, the tylosaurines remain currently unknown on the southern Tethys margin and are restricted to higher palaeolatitudes. Chelonians (bothremydids and chelonioids) are respective of each margin, which probably indicates lower dispersal capabilities compared to mosasaurids. The relative scarcity of plesiosaurs and crocodyliformes could be linked to different ecological preferences. The noteworthy crocodyliforme diversity increase in the Palaeogene is probably linked to mosasaurid extinction during the biological crisis of the K/Pg boundary.

scholarly journals An injured pachypleurosaur (Diapsida: Sauropterygia) from the Middle Triassic Luoping Biota indicating predation pressure in the Mesozoic

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qiling Liu ◽  
Tinglu Yang ◽  
Long Cheng ◽  
Michael J. Benton ◽  
Benjamin C. Moon ◽  
...  
Keyword(s):  
Middle Triassic ◽  
Large Body ◽  
Morphological Characters ◽  
Predation Pressure ◽  
The Body ◽  
West China ◽  
Marine Reptiles ◽  
Large Predator ◽  
The Right ◽  
Marine Reptile

AbstractThe Middle Triassic Luoping Biota in south-west China represents the inception of modern marine ecosystems, with abundant and diverse arthropods, fishes and marine reptiles, indicating recovery from the Permian–Triassic mass extinction. Here we report a new specimen of the predatory marine reptile Diandongosaurus, based on a nearly complete skeleton. The specimen is larger than most other known pachypleurosaurs, and the body shape, caniniform teeth, clavicle with anterior process, and flat distal end of the anterior caudal ribs show its affinities with Diandongosaurus acutidentatus, while the new specimen is approximately three times larger than the holotype. The morphological characters indicate that the new specimen is an adult of D. acutidentatus, allowing for ontogenetic variation. The fang-like teeth and large body size confirm it was a predator, but the amputated hind limb on the right side indicate itself had been predated by an unknown hunter. Predation on such a large predator reveals that predation pressure in the early Mesozoic was intensive, a possible early hint of the Mesozoic Marine Revolution.

scholarly journals Systematic Distortion Factor and Unrecognized Source of Uncertainties in Nuclear Data Measurements and Evaluations

Metrology ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 1-18
Author(s):  
Nikolay V. Kornilov ◽  
Vladimir G. Pronyaev ◽  
Steven M. Grimes
Keyword(s):  
Cross Sections ◽  
Nuclear Data ◽  
Fission Neutron ◽  
Model Case ◽  
Distortion Factor ◽  
True Value ◽  
New Information ◽  
Measurement Results ◽  
Prompt Fission ◽  
Prompt Fission Neutron

Each experiment provides new information about the value of some physical quantity. However, not only measured values but also the uncertainties assigned to them are an important part of the results. The metrological guides provide recommendations for the presentation of the uncertainties of the measurement results: statistics and systematic components of the uncertainties should be explained, estimated, and presented separately as the results of the measurements. The experimental set-ups, the models of experiments for the derivation of physical values from primary measured quantities, are the product of human activity, making it a rather subjective field. The Systematic Distortion Factor (SDF) may exist in any experiment. It leads to the bias of the measured value from an unknown “true” value. The SDF appears as a real physical effect if it is not removed with additional measurements or analysis. For a set of measured data with the best evaluated true value, their differences beyond their uncertainties can be explained by the presence of Unrecognized Source of Uncertainties (USU) in these data. We can link the presence of USU in the data with the presence of SDF in the results of measurements. The paper demonstrates the existence of SDF in Prompt Fission Neutron Spectra (PFNS) measurements, measurements of fission cross sections, and measurements of Maxwellian spectrum averaged neutron capture cross sections for astrophysical applications. The paper discusses introducing and accounting for the USU in the data evaluation in cases when SDF cannot be eliminated. As an example, the model case of 238U(n,f)/235U(n,f) cross section ratio evaluation is demonstrated.

Eastern Boulder-Weld fault zone, Colorado: A gravity slide with pop-up structures

2020 ◽  
Vol 57 (3) ◽  
pp. 177-198
Author(s):  
Richard H. Groshong ◽  
Ken Kittleson
Keyword(s):  
Fault Zone ◽  
Cross Sections ◽  
Upper Cretaceous ◽  
Sedimentary Rocks ◽  
Detailed Examination ◽  
Contour Map ◽  
Pierre Shale ◽  
Structural Style ◽  
Transport Direction ◽  
Gravity Slide

The Boulder-Weld fault zone, located southeast of Boulder, Colorado, is about 10 km (6 mi) wide, 34 km (21 mi) long, and involves at least 335 m (1100 ft) of upper Cretaceous sedimentary rocks. It affects the Cretaceous upper Pierre Shale, Fox Hills Sandstone, and the coal–bearing lower Laramie Formation. This study is a detailed examination of the eastern portion of the fault zone which consists of undisturbed areas separated by three long, narrow, fault-bounded uplifts that have received a variety of interpretations over the years. The fault zone geometry is determined from 21 closely spaced cross sections that use more subsurface data than previous studies, incorporate the elevations of the major economic coal seam derived from a published composite structure-contour map, and are area balanced using area-depth-strain (ADS) analysis. The most common structural style is a pop-up structure in which the uplifts are bounded on both sides by reverse faults. At larger-displacement the pop-ups are at the tip of the ramp and a second fault has formed close to the base of the ramp. A few sections show simple ramp anticlines developed above listric thrusts. The lower detachment for all structures is the distinctive Kp2 marker in the upper Pierre Shale. ADS analysis of the best-controlled uplifts shows that the uplifts are area balanced and confirms the lower detachment to be near Kp2. The structures are interpreted to have formed as a gravity slide because they formed in a break-back sequence, a characteristic of gravity gliding, and because the transport direction is approximately down the current southeast dip of the Kp2 detachment.

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