Reinterpretation of the Miocene Sea-Snake Egg Moniopterus Japonicus as a Boring of Rock-Boring Bivalve Lithophaga (Mytilidae: Mollusca)

2010 ◽  
Vol 84 (5) ◽  
pp. 848-857 ◽  
Author(s):  
Takuma Haga ◽  
Yukito Kurihara ◽  
Tomoki Kase
Keyword(s):  
Middle Miocene ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Sea Snake ◽  
Senior Synonym ◽  
Coleopteran Insect ◽  
Pointed End ◽  
Oval Shape ◽  
Northern Japan

The enigmatic fossil Moniopterus japonicus Hatai et al., 1974 from the early Middle Miocene Moniwa Formation of northern Japan has been described as the only known example of fossil sea-snake eggs and also as fossilized pupal chambers of a coleopteran insect. A reexamination of the holotype provides no evidence in support of these previous interpretations. Scanning electronic microscopy and computed tomography observations on the holotype reveal that the calcareous lining, previously interpreted as eggshell, is instead composed of irregular spherulitic prisms, thin in the middle and becoming thicker toward both ends. In addition to the elongate oval shape and the presence of an opening at the more pointed end, these observations strongly suggest that M. japonicus is a boring of the mytilid boring bivalve Lithophaga isolated from the host rock. This reinterpretation is further supported by the occurrence of similar isolated and in situ borings with Lithophaga shells within the type and a nearby locality. Regarding this fossil as an ichnofossil makes the generic name Moniopterus a junior synonym of Gastrochaenolites Leymerie, 1842 and the species name japonicus is a senior synonym of Gastrochaenolites torpedo Kelly and Bromley, 1984. G. torpedo should thus be replaced with Gastrochaenolites japonicus (Hatai et al., 1974).

Microstructure of In Situ Particles/7055Al Matrix Composites with Deep Cryogenic Treatment

2012 ◽  
Vol 217-219 ◽  
pp. 114-118 ◽  
Author(s):  
Xun Yin Zhang ◽  
Gui Rong Li ◽  
Ting Wang Zhang ◽  
Lei Cao ◽  
Hong Ming Wang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Cryogenic Treatment ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Deep Cryogenic Treatment ◽  
X Ray ◽  
Diffraction Peaks

Al2O3，Al3Ti and Al3Zr particles reinforced 7055 aluminium matrix composites were fabricated via melt reaction method. The volume fraction is controlled at about 4-5%. After extrusion and solution-aging heat treatment the sample was prepared for deep cryogenic treatment, The microstructure and evolution of mechanical properties of (Al3Ti+Al3Zr)p/7055 composites were analyzed using optical microscopy(OM),scanning electronic microscopy(SEM) and X-ray diffraction(XRD). Some θ(Al2Cu) phases with nanometer size precipitate in the inner grain. As some grains preferred orient the intensity of some main diffraction peaks increase. Compared with those of as-cast and squeezed states the micro hardness has increased by 16.8% and 10.0% separately.

In-Situ Sol–Gel Synthesis of Nanophosphors M2Y8(SiO4)6O2:Eu3+(M = Ca, Sr) Derived from Novel Crosslinking Reagents as Silicon Sources

2008 ◽  
Vol 8 (3) ◽  
pp. 1261-1265 ◽  
Author(s):  
Lei Zhou ◽  
Bing Yan
Keyword(s):  
High Temperature ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Strong Emission ◽  
X Ray ◽  
Sol Gel Synthesis ◽  
Silicon Sources

M2Y8(SiO4)6O2:Eu3+(M = Ca, Sr) nanophosphors were synthesized using sol–gel technology by adopting eight different kinds of silicon sources of novel crosslinging reagents. X-ray diffraction and scanning electronic microscopy show that these materials have sizes of 20–80 nm with different configurations due to the diversity of the silicate sources. Some nanophosphors present the regular microstructure despite high temperature thermolysis. In addition, all these nanophosphors exhibit strong emission at 618 nm.

scholarly journals Tribological Performance of CoCrMo Alloys with Boron Additions in As-Cast and Heat-Treated Conditions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 355
Author(s):  
Marco A. L. Hernandez-Rodriguez ◽  
Diego E. Lozano ◽  
Gabriela M. Martinez-Cazares ◽  
Yaneth Bedolla-Gil
Keyword(s):  
Boron Content ◽  
Tribological Performance ◽  
Secondary Phases ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Hardness Tests ◽  
Heat Treated ◽  
Cocrmo Alloys ◽  
Cast Condition ◽  
Ball On Disc

The present study evaluates the effect of boron additions on the tribological performance of CoCrMo alloys. The alloys were prepared with boron ranging from 0.06 to 1 wt%. The materials were characterized using metallographic techniques, scanning electronic microscopy, and roughness and hardness tests. Tribological evaluation was made by means of ball-on-disc tests for sliding distances of 4, 8 and 12 km. The samples were in the as-cast condition and after a heat treatment at 1200 °C for 1 h, finished by water quenching. The results showed that wear resistance was influenced by the microstructure and the number of secondary phases. The volume loss decreased as the boron content increased. Due to hard phases, abrasion wear was observed. Delamination fatigue was also detected after long sliding distances. Both wear mechanisms diminished in higher boron content alloys.

Ag-TiO2 Nanocomposites: visible or solar light driven plasmonic photocatalysis?

2021 ◽  
Vol 02 ◽  
Author(s):  
Larissa Bach-Toledo ◽  
Patricio G. Peralta-Zamora ◽  
Liziê Daniela Tentler Prola
Keyword(s):  
Photocatalytic Activity ◽  
Solar Radiation ◽  
Noble Metals ◽  
Halogen Lamp ◽  
Tio2 Surface ◽  
Electronic Microscopy ◽  
Visible Radiation ◽  
Artificial Uv ◽  
Positive Effect

Background: The demand for photocatalytic processes assisted by solar radiation has stimulated the upgrading of established systems, as the semiconductor modification with noble metals. Objective: the synthesis, characterization, and photocatalytic activity evaluation of the Ag-TiO2, against sulfamethoxazole molecule, and investigate the significance of the plasmonic phenomenon in Visible (450 - 1000nm) and UV-Vis (315-800 nm) radiation. Methods: Different nanocomposites Ag/TiO2 ratios were synthesized by the deposition of Ag nanoparticles on the TiO2 surface by in-situ photoreduction, and then calcinated at 400°C for 2 hr. The chemical-physical properties of the materials were examined by UV-Vis Diffuse Reflectance (UV-Vis DRS) Scanning Electronic Microscopy (SEM), Transmission Electronic Microscopy (TEM), X-Ray Energy Dispersive Spectroscopy (EDS). The experiments were conducted in a cooled photochemical reactor irradiated by halogen lamp (250W). The degradation of Sulfamethoxazole was monitored by HPLC-DAD. Results: Although the prepared photocatalysts show an intense plasmonic band centered at 500 nm, no photocatalytic activity was observed in the process assisted by artificial visible radiation ( ≥ 450 nm). In processes assisted by artificial UV-Vis radiation, the photolysis rate of the model compound (sulfamethoxazole) was higher than the photocatalytic rate, and in the absence of UV radiation, all the reactions were inhibited. The positive effect of the presence of silver nanoparticles onto the TiO2 surface was only evidenced in studies involving solar radiation. Conclusion: The results suggest the need for a balance between UV and Vis radiation to activate the nanocomposite and perform the sulfamethoxazole degradation.

scholarly journals IMPROVEMENT OF MICROMERITIC, COMPRESSIBILITY AND SOLUBILITY CHARACTERISTICS OF LINEZOLID BY CRYSTALLO-CO-AGGLOMERATION TECHNIQUE

2017 ◽  
Vol 9 (4) ◽  
pp. 47 ◽  
Author(s):  
Atul M. Kadam ◽  
Shitalkumar S. Patil
Keyword(s):  
Drug Release ◽  
Methyl Cellulose ◽  
Mechanical Deformation ◽  
Angle Of Repose ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Fourier Transformation Infrared Spectroscopy ◽  
Time Required ◽  
Good Flow

Objective: The purpose of current study was to improve physicochemical properties such as micrometric, compressibility and solubility of linezolid (LNZ) by preparing crystallo-co-agglomerates (CCA) in the presence of polymer for the enhancement of overall physicochemical performance.Methods: The process of agglomeration involves the use of dichloromethane (DCM) as a good solvent and chloroform as bridging liquid were used to prepare agglomerates. Agglomerates were characterised in the solid state using several techniques such as Scanning electronic microscopy(SEM), Fourier transformation infrared spectroscopy (FTIR), X-ray powder diffraction analysis (XRPD) The agglomerates obtained were evaluated for micrometric, mechanical, deformation, compressibility and drug release properties.Results: It was found that micrometric properties and dissolution characteristics of agglomerates were significantly improved than that of pure linezolid. Solubility was found to be increased than pure linezolid. The solubility of crystallo co-agglomerates was found an increase in 5 fold 3 fold and 3.7 fold for PVPK30 (0.5%), PVPK30 (0.25%) and PVPK30 (0.75%) respectively. The angle of repose for all batches was found between 22 ° to 30 °Carrs index was between 12.27±0.6 to 18.73±0.4 and Hausners ratio Near to 1, indicated good flow ability of agglomerates. The time required for drug release over a period of 60 min, is as LA1>LA2>LA3. LA3 shows fast drug release than LA1 and LA2, due to solubilization of drug due to more concentration of PVPK30 and less concentration of talc.Conclusion: Based on the above results, it was revealed that CCA of linezolid prepared with DCM and HPMC (Hydroxypropyl methyl cellulose)/PEG (Polyethylene glycol)/PVP (Polyvinylpyrrolidone) K30 exhibited improved micrometric properties, compressibility and in addition to improving solubility and dissolution rate.

scholarly journals Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

2007 ◽  
Vol 39 (2) ◽  
pp. 145-152 ◽  
Author(s):  
Z. Andjic ◽  
M. Korac ◽  
Z. Kamberovic ◽  
A. Vujovic ◽  
M. Tasic
Keyword(s):  
Mechanical Properties ◽  
Chemical Method ◽  
Elevated Temperatures ◽  
Hydrogen Atmosphere ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Composite Powders ◽  
Nanocomposite Powders ◽  
Final Composition

In this paper synthesis of a composite based on Cu-Al2O3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electric-mechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al2O3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al2O3. Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-ray-structure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900oC for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al2O3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties. .

scholarly journals A Leaf Point Documents Hunting with Spears in the Middle Paleolithic at Hohle Fels, Germany

2021 ◽  
Vol 2021 (30) ◽  
Author(s):  
Veerle Rots ◽  
Justin Coppe ◽  
Nicholas Conard
Keyword(s):  
Life History ◽  
Evolutionary Development ◽  
Functional Study ◽  
Middle Paleolithic ◽  
Projectile Technology ◽  
Excellent Preservation ◽  
The Rich ◽  
Pointed End ◽  
The University

During the 2020 season at Hohle Fels Cave in the Ach Valley of southwestern Germany the excavation team from the University of Tübingen recovered a bifacial leaf point in archaeological horizon (AH) X. This horizon is the fifth deepest of the Middle Paleolithic horizons at the site and is located roughly 120 cm beneath the base of the rich Aurignacian layers of the cave. The new leaf point, or Blattspitze in German, is the first artifact of its kind found in situ in the Swabian caves since Gustav Riek’s excavation at Haldenstein Cave near the source of the Lone River recovered two leaf points in excellent preservation in 1936. The new find allowed our team to conduct the first techno-functional study of a freshly recovered leaf point from the European Middle Paleolithic. This study demonstrates that the leaf point was hafted at the less pointy end of the artifact. The leaf point bears clear damage to the pointed end of the artifact that occurred during a hunting episode. A Neanderthal knapper further damaged the tool during an attempt to resharpen and rejuvenate the tool. This damage was likely the reason the knapper discarded the leaf point at Hohle Fels. This result and a re-examination of the two leaf points from Haldenstein Cave indicate that late Neanderthals used Blattspitzen for hunting large game. The current results do not explicitly prove that spears with hafted leaf points were always thrown or used as thrusting spears, and one can easily imagine scenarios in which a weapon of this kind could be used in both ways. Ideally, the ongoing excavation at Hohle Fels will recover more leaf points, which will give us the opportunity to document the technological variability of this kind of tool with regard to their manufacture, function and life history. We also view the current research at Hohle Fels as an excellent opportunity to gain a better and more strongly contextualized understanding of the technological system linking lithic, botanical and osseous technologies during this phase of the Middle Paleolithic. This paper also considers the place that hafted leaf points have within the broader evolutionary development of hunting and projectile technology.

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