scholarly journals Early formation and taphonomic significance of kaolinite associated with Burgess Shale fossils

Geology ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 355-359
Author(s):  
Ross P. Anderson ◽  
Nicholas J. Tosca ◽  
Erin E. Saupe ◽  
Jon Wade ◽  
Derek E.G. Briggs
Keyword(s):  
Soft Tissue ◽  
Soft Tissues ◽  
Heterotrophic Bacteria ◽  
Burgess Shale ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Shale Formation ◽  
Area X

Abstract The role of minerals in Burgess Shale–type fossilization is controversial, particularly that of the clay mineral kaolinite. Kaolinite may have formed on carcasses or attached to them as they decayed, stabilizing organic matter. Alternatively, kaolinite may have formed during metamorphism, playing no role in the preservation of soft tissues. Evaluating the formation and taphonomic role of kaolinite is difficult, because the mineralogy of Burgess Shale–type fossils is incompletely known. We used in situ selected-area X-ray diffraction to constrain the mineralogy of fossils from the classic Burgess Shale Formation in British Columbia, Canada. Fossils can be distinguished from the matrix that surrounds them by the presence of dolomite, kaolinite, and pyrite. Chlorite may be more abundant in the matrix. The preferential survival of kaolinite in association with fossils provides evidence of early diagenetic clay-organic interactions that protected the clay from metamorphic transformation. Kaolinite likely played a crucial role in fossilization, inhibiting the growth of heterotrophic bacteria and aiding polymerization of soft tissue biomolecules. This may result in biases in soft-tissue preservation to areas and times where kaolinite was prevalent.

scholarly journals Quantification of assembly forces during creation of head-neck taper junction considering soft tissue bearing: a biomechanical study

Arthroplasty ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Toni Wendler ◽  
Torsten Prietzel ◽  
Robert Möbius ◽  
Jean-Pierre Fischer ◽  
Andreas Roth ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Work Experience ◽  
Soft Tissues ◽  
Force Sensor ◽  
Biomechanical Study ◽  
Measuring System ◽  
Wide Range ◽  
Head Neck

Abstract Background All current total hip arthroplasty (THA) systems are modular in design. Only during the operation femoral head and stem get connected by a Morse taper junction. The junction is realized by hammer blows from the surgeon. Decisive for the junction strength is the maximum force acting once in the direction of the neck axis, which is mainly influenced by the applied impulse and surrounding soft tissues. This leads to large differences in assembly forces between the surgeries. This study aimed to quantify the assembly forces of different surgeons under influence of surrounding soft tissue. Methods First, a measuring system, consisting of a prosthesis and a hammer, was developed. Both components are equipped with a piezoelectric force sensor. Initially, in situ experiments on human cadavers were carried out using this system in order to determine the actual assembly forces and to characterize the influence of human soft tissues. Afterwards, an in vitro model in the form of an artificial femur (Sawbones Europe AB, Malmo, Sweden) with implanted measuring stem embedded in gelatine was developed. The gelatine mixture was chosen in such a way that assembly forces applied to the model corresponded to those in situ. A study involving 31 surgeons was carried out on the aforementioned in vitro model, in which the assembly forces were determined. Results A model was developed, with the influence of human soft tissues being taken into account. The assembly forces measured on the in vitro model were, on average, 2037.2 N ± 724.9 N, ranging from 822.5 N to 3835.2 N. The comparison among the surgeons showed no significant differences in sex (P = 0.09), work experience (P = 0.71) and number of THAs performed per year (P = 0.69). Conclusions All measured assembly forces were below 4 kN, which is recommended in the literature. This could lead to increased corrosion following fretting in the head-neck interface. In addition, there was a very wide range of assembly forces among the surgeons, although other influencing factors such as different implant sizes or materials were not taken into account. To ensure optimal assembly force, the impaction should be standardized, e.g., by using an appropriate surgical instrument.

Kalana Lagerstätte crinoids: Early Silurian (Llandovery) of central Estonia

2019 ◽  
Vol 94 (1) ◽  
pp. 131-144 ◽  
Author(s):  
William I. Ausich ◽  
Mark A. Wilson ◽  
Oive Tinn
Keyword(s):  
Soft Tissue ◽  
Clay Minerals ◽  
Late Ordovician ◽  
Marine Biota ◽  
Organic Residue ◽  
Elemental Mapping ◽  
Shallow Marine ◽  
The Matrix

AbstractThe Kalana Lagerstätte of early Aeronian (Llandovery, Silurian) age in central Estonia preserves a diverse shallow marine biota dominated by non-calcified algae. This soft-tissue flora and decalcified and calcified crinoids are preserved in situ, in a lens of microlaminated, dolomitized micrite interbedded in a sequence of dolomitized packstones and wackestones. Although the Lagerstätte is dominated by non-calcified algae, crinoids (together with brachiopods and gastropods) are among the most common organisms that were originally comprised of a carbonate skeleton. Two new crinoids are described from this unit, Kalanacrinus mastikae n. gen. n. sp. (large camerate) and Tartucrinus kalanaensis n. gen. n. sp. (small disparid). Interestingly, these two crinoids display contrasting preservation, with the more common large camerate preserved primarily as a decalcified organic residue, whereas the smaller disparid is preserved primarily in calcite. Preservation was assessed using elemental mapping of C, Ca, S, and Si. Columns have the highest portion of Ca, once living soft tissue is indicated by C, S was dispersed as pyrite or associated with organics, and Si is probably associated with clay minerals in the matrix. This new fauna increases our understanding of the crinoid radiation on Baltica following Late Ordovician extinctions.UUID: http://zoobank.org/fb1f98c4-d35a-43f4-aa0d-75e4f8154a13

Effect of Milling Speed on the Synthesis of In-Situ Cu-25 Vol. % WC Nanocomposite by Mechanical Alloying

2012 ◽  
Vol 59 (2) ◽  
Author(s):  
Nurulhuda Bashirom ◽  
Nurzatil Ismah Mohd Arif
Keyword(s):  
Stainless Steel ◽  
Mechanical Alloying ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Steel Balls

This paper presents a study on the effect of milling speed on the synthesis of Cu-WC nanocomposites by mechanical alloying (MA). The Cu-WC nanocomposite with nominal composition of 25 vol.% of WC was produced in-situ via MA from elemental powders of copper (Cu), tungsten (W), and graphite (C). These powders were milled in the high-energy “Pulverisette 6” planetary ball mill according to composition Cu-34.90 wt% W-2.28 wt% C. The powders were milled in different milling speed; 400 rpm, 500 rpm, and 600 rpm. The milling process was conducted under argon atmosphere by using a stainless steel vial and 10 mm diameter of stainless steel balls, with ball-to-powder weight ratio (BPR) 10:1. The as-milled powders were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD result showed the formation of W2C phase after milling for 400 rpm and as the speed increased, the peak was broadened. No WC phase was detected after milling. Increasing the milling speed resulted in smaller crystallite size of Cu and proven to be in nanosized. Based on SEM result, higher milling speed leads to the refinement of hard W particles in the Cu matrix. Up to the 600 rpm, the unreacted W particles still existed in the matrix showing 20 hours milling time was not sufficient to completely dissolve the W.

In situobservation of morphological changes of γ′ precipitates in a pre-deformed single-crystal Ni-base superalloy

2011 ◽  
Vol 44 (5) ◽  
pp. 935-944 ◽  
Author(s):  
Pavel Strunz ◽  
Gerhard Schumacher ◽  
Hellmuth Klingelhöffer ◽  
Albrecht Wiedenmann ◽  
Jan Šaroun ◽  
...  
Keyword(s):  
External Load ◽  
Morphological Changes ◽  
The Past ◽  
Subsequent Heating ◽  
Detailed Evaluation ◽  
The Matrix ◽  
Base Superalloy

Exposure of a superalloy to an external load results in anisotropic coarsening of the γ′ precipitates, so-called rafting. It was reported in the past that γ′ rafting can also occur as a result of purely thermal treatment, without the simultaneous presence of an external load, if the specimen has been pre-deformed at relatively low temperature. The evolution of γ′ morphology in pre-deformed specimens of SCA425 Ni-base superalloy was examined in the present study. Unlike in the previous experiments, the compressive stress was used for pre-straining.In situsmall-angle neutron scattering (SANS) was employed, which enabled the determination of the morphology directly at high temperature. Both for strong and for weak pre-straining, rounding of the originally cuboidal precipitates towards an ellipsoidal shape on heating was observed. Weak pre-straining (0.1, 0.5%) does not cause rafting on subsequent heating. On the other hand, the detailed evaluation of SANS data provides some indication of rafting during the subsequent heating after severe compressive pre-straining (2%). The experiment indicates the role of dislocation rearrangement at the matrix/precipitate interface during pre-straining.

Fabrication of TiAl/Ti2AlC Composite by Reaction Hot Pressing

2011 ◽  
Vol 52-54 ◽  
pp. 842-845 ◽  
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Yi Ping Gong
Keyword(s):  
Electron Microscopy ◽  
Reaction Process ◽  
Hot Press ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Composite ◽  
The Matrix ◽  
Morphology Characteristics ◽  
Scanning Electron

TiAl/Ti2AlC in situ composite was successfully fabricated by hot-press-assisted reaction process from the mixture of Ti, Al and carbon black. The phase formation and transformation were investigated in detail by X-ray diffraction (XRD) and the morphology characteristics were also studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that when the mixed powders were hot pressed at 1300 °C for 1 h, full dense and highly pure TiAl/Ti2AlC composite was synthesized. The TiAl was the matrix phase and the in situ synthesized Ti2AlC was reinforcing phase. The reaction process was also discussed.

Preparation and Wear Properties of (Al3Zr+ZrB2)P/2124 Composites Material with In Situ Process

2012 ◽  
Vol 616-618 ◽  
pp. 1736-1740
Author(s):  
Lei Jiao ◽  
Yu Tao Zhao ◽  
Zhong Zhong Zhang ◽  
Yan Wei Yang ◽  
Ming Rui Zhang
Keyword(s):  
Magnetic Field ◽  
Composite Materials ◽  
Sliding Friction ◽  
Testing Machine ◽  
Test Methods ◽  
X Ray Diffraction ◽  
Wear Properties ◽  
Matrix Metal ◽  
The Matrix

With pulse magnetic field, it is use 2124-K2ZrF6-KBF4 as matrix metal to produce chemical reaction to gain (Al3Zr+ZrB2) p/2124 composite materials in this paper. In this paper, For the sake of researching the microstructure, the morphology, the size and the matrix distribution characteristics of the reinforced grain of prepared composite material , those test methods are used, such as optical microscopy, scanning electron microscope, X-ray diffraction analysis and so on. We will research the magnetic field strength how to influence size and distribution of Al3Zr +ZrB2 particle and the abrasion performance of (Al3Zr+ZrB2)P/2124 composite materials in the room temperature. Wear experiment is proceeding in the CETR UMT 3-V the testing machine and sliding friction is friction way with pin-disc but without lubricant, then analyzes the wear mechanism.

The taphonomy and affinities of the problematic fossilMyoscolexfrom the Lower Cambrian Emu Bay Shale of South Australia

1997 ◽  
Vol 71 (1) ◽  
pp. 22-32 ◽  
Author(s):  
Derek E. G. Briggs ◽  
Christopher Nedin
Keyword(s):  
Muscle Tissue ◽  
Lower Cambrian ◽  
Soft Tissues ◽  
South Australia ◽  
Variable Number ◽  
Trunk Muscles ◽  
Burgess Shale ◽  
Organic Residues ◽  
Striking Contrast

Most of the specimens ofMyoscolex atelesGlaessner, 1979, the most abundant soft-bodied taxon in the Big Gully fauna from the Lower Cambrian Emu Bay Shale of South Australia, preserveonlythe phosphatized trunk muscles, in striking contrast to the organic residues that characterize other Burgess-Shale-type biotas. This is the oldest phosphatized muscle tissue and the first thus far reported from the Cambrian. The extent of phosphatization implies a source in addition to the animal itself, and this is reflected in high levels of phosphate in the Big Gully sequence compared to other shales. The apparent anomaly posed by the extensive preservation of labile muscle tissue as opposed to the more decay resistant cuticle is explained by the role of bacterial processes in the preservation of soft tissues. New specimens ofMyoscolexreveal a variable number of trunk somites with possible tergites, and flap-like appendages. There is evidence for at least three eyes on the head, and a proboscis may have been present. An annelid affinity is rejected andMyoscolexis reinterpreted as anOpabinia-likeanimal with possible affinities with the arachnomorph arthropods.

The Role of Hyaluronic Acid in the Correction of Soft Tissue Deficiencies: Review and Clinical Considerations

2015 ◽  
Vol 638 ◽  
pp. 270-273
Author(s):  
Andrei Carantino
Keyword(s):  
Hyaluronic Acid ◽  
Soft Tissue ◽  
Soft Tissues ◽  
Years Of Experience ◽  
Clinical Considerations ◽  
Surgical Operations

This paper presents some aspects from last 10 years of experience, when we used the hyaluronic acid produced and traded by a certain company, to obtain aesthetic good results in the treatment of the facial wrinkles, nazolabial folds, augmentation of the lips, face rejuvenation and hydration, correction of soft tissues deficiencies after major surgical operations.

scholarly journals Revealing the role of microstructure architecture on strength and ductility of Ni microwires by in-situ synchrotron X-ray diffraction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ravi raj purohit Purushottam raj purohit ◽  
Abhinav Arya ◽  
Girish Bojjawar ◽  
Maxime Pelerin ◽  
Steven Van Petegem ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Strength And Ductility

scholarly journals The Effect of γ″ and δ Phase Precipitation on the Mechanical Properties of Inconel 718 Manufactured by Selective Laser Melting: An In Situ Neutron Diffraction and Acoustic Emission Study

JOM ◽  
2020 ◽  
Vol 73 (1) ◽  
pp. 223-232 ◽  
Author(s):  
Jan Čapek ◽  
Efthymios Polatidis ◽  
Michal Knapek ◽  
Christophe Lyphout ◽  
Nicola Casati ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Neutron Diffraction ◽  
Annealed Sample ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Δ Phase ◽  
Emission Study ◽  
Acoustic Emission Study ◽  
In Situ Neutron Diffraction

AbstractThe deformation behavior of additively manufactured Alloy 718 in as-built condition and after annealing was studied in situ under tensile loading along the build direction. Pre-characterization by synchrotron X-ray diffraction and electron microscopy revealed a significant amount of γ″ precipitates in the as-built samples, whereas the γ″ phase was entirely consumed and needle-like δ precipitates appeared in the annealed sample. In situ neutron diffraction (ND) and acoustic emission (AE) enabled indirect observation of the role of the precipitates on the mechanical behavior. ND provided information on the load accommodation in the matrix, while AE detected a strong signal from the interaction of dislocations with the δ-phase precipitates during deformation of the annealed samples. The results imply that in the annealed samples the matrix sheds the load to the precipitates, while in the as-built material the matrix bares a significant load.

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