scholarly journals Monitoring Dynamic Recrystallisation in Bioresorbable Alloy Mg-1Zn-0.2Ca by Means of an In Situ Acoustic Emission Technique

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 328
Author(s):  
Dmitry Merson ◽  
Mikhail Linderov ◽  
Alexander Brilevsky ◽  
Alexey Danyuk ◽  
Alexei Vinogradov
Keyword(s):  
Acoustic Emission ◽  
In Situ Monitoring ◽  
Tensile Behaviour ◽  
Median Frequency ◽  
Fine Grained ◽  
Specific Behaviour ◽  
Wide Range ◽  
Dynamic Recrystallisation ◽  
First Time

The tensile behaviour of the biocompatible alloy Mg-1Zn-0.2Ca (in wt.%) in the fine-grained state, obtained by severe plastic deformation via multiaxial isothermal forging, has been investigated in a wide range of temperatures (20 ÷ 300) °C and strain rates (5 × 10−4 ÷ 2 × 10−2) s−1 with the measurements of acoustic emission (AE). The dependences of mechanical properties, including the yield stress, ultimate strength, ductility, and the strain-hardening rate, on the test temperature and strain rate, were obtained and discussed. It is shown for the first time that an acoustic emission method is an effective tool for in situ monitoring of the dynamic recrystallisation (DRX) process. The specific behaviour of the acoustic emission spectral density reflected by its median frequency as a function of strain at various temperatures can serve as an indicator of the DRX process’s completeness.

scholarly journals In situ Impact of the Antagonistic Fungal Strain, Trichoderma gamsii T30 on the Plant Pathogenic Fungus, Rhizoctonia solani in Soil

2019 ◽  
Vol 68 (2) ◽  
pp. 211-216
Author(s):  
MUHAMMAD ANEES ◽  
MUHAMMAD ABID ◽  
SOBIA CHOHAN ◽  
MUHAMMAD JAMIL ◽  
NADEEM AHMED ◽  
...  
Keyword(s):  
Population Density ◽  
Rhizoctonia Solani ◽  
Pathogenic Fungus ◽  
Suppressive Effect ◽  
Fungal Strain ◽  
Soil Microbiome ◽  
Target Dna ◽  
Wide Range ◽  
First Time

Rhizoctonia solani is a soil-borne fungus causing a wide range of plants diseases. Trichoderma gamsii strain T30 has previously been reported as antagonistic against R. solani. Although there are a few studies about the influence of Trichoderma strains on the R. solani densityin a pathosystem in the presence of plant hosts, this report for the first time comprehensively describes in situ effects of a T. gamsii strain on the population density of R. solani in the soil microcosmic conditions. The population dynamics of R. solani were followed in the autoclaved and non-autoclaved soils in artificially prepared microcosms up to day 25 after co-inoculation with T. gamsii in the variable ratios (R1/T1; R1/T0.1; R1/T0.01 of R. solani/T. gamsii). The population density of R. solani was evaluated by qPCR. In the autoclaved soil, target DNA copies of R. solani increased in the control samples from 1 × 105 to 6.5 × 106. At R1/T0.01, the number of target DNA copies were not significantly changed until day 11; however, it decreased by around five times at day 25. At R1/T0.1 and R1/T1, the number of DNA copies was reduced to 2.1 × 106 and 7.6 × 105 at day 11, respectively and the reduction was as much as 17 times at day 25. In the non-autoclaved soil, the number of the fungal cells decreased at day 25 whether inoculated or not with Trichoderma indicating a general suppression by the soil microbiome. In brief, T. gamsii significantly inhibited the growth of R. solani in the soil in situ and there was a general suppressive effect of the natural microbiome.

Plant Taphonomy and Paleoecology of Late Pennsylvanian Intramontane Wetlands in the Graissessac-Lodève Basin (Languedoc, France)

Palaios ◽  
2005 ◽  
Vol 20 (3) ◽  
pp. 249-265 ◽  
Author(s):  
CARLES MARTÍN-CLOSAS ◽  
JEAN GALTIER
Keyword(s):  
Detailed Comparison ◽  
Alluvial Fans ◽  
Fluvial Sediments ◽  
Tree Fern ◽  
Massif Central ◽  
Fine Grained ◽  
Tree Ferns ◽  
First Time ◽  
Diverse Plant

Abstract The Late Pennsylvanian Graissessac-Lodève basin is a small, fluvio-palustrine depocenter located in the southern part of the Massif Central (France). A taphonomic and sedimentologic study carried out in this area allows a reconstruction of Late Carboniferous vegetation in an intramontane context. The paleoecology of such limnic settings is poorly known, and this study permits detailed comparison with paralic basins for the first time. The Graissessac peat mires developed in abandoned fluvial channels, in floodplains, and above distal alluvial fans. The vegetation was dominated by monospecific stands of the arborescent lycopsid Sigillaria brardii, whereas the tree fern Psaronius occurred during the later stages of mire accretion. This is in contrast to coeval North American peat mires, which generally were dominated by tree ferns and pteridosperms throughout the mire profile. Stephanian floodplains and distal alluvial fans of the Graissessac-Lodève Basin were devoid of vegetation, with the exception of isolated thickets of sphenopsids that were composed of Calamites and Sphenophyllum. These plants were found growing in situ in the floodplain mudstones as well as in fine-grained sands of secondary channels. Parautochthonous foliage assemblages of ferns and pteridosperms found in floodplain mudstones represent the most diverse plant community. The plants supplying these remains were growing in exposed areas close to floodplains. Large logs attributed to cordaitaleans and monotypic assemblages of large Cordaites leaves were found in fluvial sediments, and suggest that the plants were riparian elements in the basin.

scholarly journals In-Situ Monitoring and Analysis of the Pitting Corrosion of Carbon Steel by Acoustic Emission

2019 ◽  
Vol 9 (4) ◽  
pp. 706 ◽  
Author(s):  
Junlei Tang ◽  
Junyang Li ◽  
Hu Wang ◽  
Yingying Wang ◽  
Geng Chen
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Monitoring ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology

The acoustic emission (AE) technique was applied to monitor the pitting corrosion of carbon steel in NaHCO3 + NaCl solutions. The open circuit potential (OCP) measurement and corrosion morphology in-situ capturing using an optical microscope were conducted during AE monitoring. The corrosion micromorphology was characterized with a scanning electron microscope (SEM). The propagation behavior and AE features of natural pitting on carbon steel were investigated. After completion of the signal processing, including pre-treatment, shape preserving interpolation, and denoising, for raw AE waveforms, three types of AE signals were classified in the correlation diagrams of the new waveform parameters. Finally, a 2D pattern recognition method was established to calculate the similarity of different continuous AE graphics, which is quite effective to distinguish the localized corrosion from uniform corrosion.

Advances in Wear Measurement by Acoustic Emission Analysis Compared to Radionuclide Technique

2011 ◽  
Author(s):  
A. Albers ◽  
S. G. Kelemen
Keyword(s):  
Particle Size ◽  
Acoustic Emission ◽  
Noise Analysis ◽  
Wear Volume ◽  
Friction Behavior ◽  
Emission Analysis ◽  
Monitoring Method ◽  
Solid Friction ◽  
First Time

Online analysis of a tribological contact without changing the conditions of the system is a challenging exercise until today. Yet, it is not possible to detect wear and the particle size ith one method. Numerous works study different phenomena of the behavior of ultrasonic structure-borne noise in dry friction contacts. However all these experiments are limited to basic pin-disc experiments without any concrete reference to an application. A new application for detecting real contact-geometry, wear and particle size with one in-situ condition monitoring method on a test rigs is presented in this paper. The method of structure-born noise analysis has proven to be suitable for detecting the occurrence of solid friction [1]–[4]. By using a broadband piezoelectric acoustic emission sensor to detect ultrasonic structure-born noise, caused by metal-to-metal contact it is now possible to study different types of phenomena during their time of appearance. The Radionuclide Technology (RNT) was used the first time at dry running friction systems. With the RNT it is possible to correlate ultrasonic structure-borne noise with wear volume in dry running friction systems. The application is used for deeper understanding of the friction behavior and wear phenomena in dry running contacts.

Unique heliophysics science opportunities along the Interstellar Probe journey up to 1000 AU from the Sun

2021 ◽  
Author(s):  
Elena Provornikova ◽  
Pontus C. Brandt ◽  
Ralph L. McNutt, Jr. ◽  
Robert DeMajistre ◽  
Edmond C. Roelof ◽  
...  
Keyword(s):  
Space Mission ◽  
In Situ Measurements ◽  
Unique Determination ◽  
The Sun ◽  
Global Shape ◽  
Wide Range ◽  
First Time ◽  
Interstellar Probe ◽  
Probe Mission

<p>The Interstellar Probe is a space mission to discover physical interactions shaping globally the boundary of our Sun`s heliosphere and its dynamics and for the first time directly sample the properties of the local interstellar medium (LISM). Interstellar Probe will go through the boundary of the heliosphere to the LISM enabling for the first time to explore the boundary with a dedicated instrumentation, to take the image of the global heliosphere by looking back and explore in-situ the unknown LISM. The pragmatic concept study of such mission with a lifetime 50 years that can be implemented by 2030 was funded by NASA and has been led by the Johns Hopkins University Applied Physics Laboratory (APL). The study brought together a diverse community of more than 400 scientists and engineers spanning a wide range of science disciplines across the world.</p><p>Compelling science questions for the Interstellar Probe mission have been with us for many decades. Recent discoveries from a number of space missions exploring the heliosphere raised new questions strengthening the science case. The very shape of the heliosphere, a manifestation of complex global interactions between the solar wind and the LISM, remains the biggest mystery. Interpretations of imaging the heliosphere in energetic neutral atoms (ENAs) in different energy ranges on IBEX and Cassini/INCA from inside show contradictory pictures. Global physics-based models also do not agree on the global shape. Interstellar Probe on outbound trajectory will image the heliosphere from outside for the first time and will provide a unique determination of the global shape.</p><p>The LISM is a completely new area for exploration and discovery. We have a crude understanding of the LISM inferred from in-situ measurements inside the heliosphere of interstellar helium, pick-up-ions, ENAs, remote observations of solar backscattered Lyman-alpha emission and absorption line spectroscopy in the lines of sight of stars. We have no in-situ measurements of most LISM properties, e.g. ionization, plasma and neutral gas, magnetic field, composition, dust, and scales of possible inhomogeneities. Voyagers with limited capabilities have explored 30 AU beyond the heliosphere which appeared to be a region of significant heliospheric influence. The LISM properties are among the key unknowns to understand the Sun`s galactic neighborhood and how it shapes our heliosphere. Interstellar Probe will be the first NASA mission to discover the very nature of the LISM and shed light on whether the Sun enters a new region in the LISM in the near future.</p><p>In this presentation we give an overview of heliophysics science for the Interstellar Probe mission focusing on the critical science questions of the three objectives for the mission. We will discuss in more details a need for direct measurements in the LISM uniquely enabled by the Interstellar Probe.</p>

Efficient Access to Aliphatic Esters by Photocatalyzed Alkoxycarbonylation of Alkenes

2021 ◽  
Author(s):  
Jian-Qiang Chen ◽  
Xiaodong Tu ◽  
Qi Tang ◽  
Ke Li ◽  
Liang Xu ◽  
...  
Keyword(s):  
Natural Product ◽  
Oxalyl Chloride ◽  
Biologically Active ◽  
Formal Synthesis ◽  
Efficient Access ◽  
Wide Range ◽  
New Strategy ◽  
Aliphatic Esters ◽  
First Time

Abstract Aliphatic esters are essential constituents of biologically active compounds and versatile chemical intermediates for the synthesis of drugs. However, their preparation from readily available olefins remains challenging. In this report, a new strategy to access aliphatic esters from olefins through a unique photocatalyzed alkoxycarbonylation reaction is described. Alkyloxalyl chlorides, generated in situ from the corresponding alcohols and oxalyl chloride, are engaged for the first time as alkoxycarbonyl radical fragments under photoredox catalysis. This transformation tolerates a broad scope of electron-rich and electron-deficient olefins and provides the corresponding β-chloro esters in good yields. Additionally, a formal β-selective alkene alkoxycarbonylation is developed. And, a variety of oxindole-3-acetates and furoindolines are prepared in good to excellent yields. A more concise formal synthesis of (±)-physovenine is accomplished as well. With these strategies, a wide range of natural-product-derived olefins and alkyloxalyl chlorides are also successfully employed.

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