Detonation Consolidation of NiFe/SiO2 and Co/SiO2 nanocomposites

2002 ◽  
Vol 759 ◽  
Author(s):  
Xinqing Ma ◽  
Y. D. Zhang ◽  
S. Hui ◽  
Mingzhong Wu ◽  
Shihui Ge ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Oxygen Mixture ◽  
Full Density ◽  
Magnetic Studies ◽  
Powder Morphology ◽  
Hypersonic Propulsion ◽  
Operation Conditions ◽  
Before And After ◽  
Propulsion Force ◽  
Size And Morphology

ABSTRACTConsolidation of nanostructure magnetic particles is required not only for manufacturing bulk component, it is actually a fundamental requirement for obtaining novel magnetic properties from the material. Consolidation (assembly) of nanoparticles to full density without deteriorating their nanostructure (size and morphology) is a big challenge. Here we present the consolidation experiments of NiFe/SiO2 and Co/SiO2 nanocomposites via detonation consolidation. This approach is based on the explosive pressure created when an acetylene and oxygen mixture gas fires in a sample containing tube, the very high hypersonic propulsion force makes nanoparticles deposit onto the target. Depending on the powder morphology and operation conditions, the density of the consolidated sample can reach over 91% of the theoretical density of the bulk materials. X-ray diffraction experiments on the samples before and after consolidation indicate that the denotation consolidations can be optimized such that it does not cause any phase transition. However, a particle size increase was observed. Static magnetic studies carried out on the samples before and after detonation operation shows that the saturation magnetization does not. This indicates that the operation does not cause an oxidation of the nanopowders. These experiments show that detonation approach is a good candidate for consolidating magnetic nanoparticles.

scholarly journals A Tamper-Resistant Algorithm Using Blockchain for the Digital Tachograph

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 581
Author(s):  
Yongbae Kim ◽  
Juyong Back ◽  
Jongweon Kim
Keyword(s):  
Wireless Communication ◽  
Statistical Tests ◽  
Operating Conditions ◽  
External Memory ◽  
Data Recording ◽  
Storage Devices ◽  
Suggested Algorithm ◽  
Operation Conditions ◽  
Before And After ◽  
Verification Test

A tachograph in a vehicle records the vehicle operating conditions, such as speed, distance, brake operation conditions, acceleration, GPS information, etc., in intervals of one second. For accidents, the tachograph records information, such as the acceleration and direction of a vehicle traveling in intervals of 1/100 s for 10 s before and after the accident occurs as collision data. A vehicle equipped with a tachograph is obliged to upload operation data to administrative organizations periodically via other auxiliary storage devices like a USB attached external memory or online wireless communication. If there is a problem with the recorded contents, data may be at risk of being tampered with during the uploading process. This research proposed tamper-resistant technology based on blockchain for data in online and offline environments. The suggested algorithm proposed a new data recording mechanism that operates in low-level hardware of digital tachographs for tamper-resistance in light blockchains and on/offline situations. The average encoding time of the proposed light blockchain was 1.85 ms/Mb, while the average decoding time was 1.65 ms/Mb. With the outliers in statistical tests removed, the estimated average encoding and decoding time was 1.32 ms/Mb and 1.29 ms/Mb, respectively, and the tamper verification test detected all the tampered data.

scholarly journals Quantified abundance of magnetofossils at the Paleocene–Eocene boundary from synchrotron-based transmission X-ray microscopy

2015 ◽  
Vol 112 (41) ◽  
pp. 12598-12603 ◽  
Author(s):  
Huapei Wang ◽  
Jun Wang ◽  
Yu-chen Karen Chen-Wiegart ◽  
Dennis V. Kent
Keyword(s):  
Magnetic Particles ◽  
Strong Field ◽  
Atlantic Coastal Plain ◽  
Magnetic Studies ◽  
Electron Microscopic ◽  
Natural Sediment ◽  
Full Field ◽  
X Ray ◽  
Transmission Electron ◽  
Carbon Isotope Excursion

The Paleocene–Eocene boundary (∼55.8 million years ago) is marked by an abrupt negative carbon isotope excursion (CIE) that coincides with an oxygen isotope decrease interpreted as the Paleocene–Eocene thermal maximum. Biogenic magnetite (Fe3O4) in the form of giant (micron-sized) spearhead-like and spindle-like magnetofossils, as well as nano-sized magnetotactic bacteria magnetosome chains, have been reported in clay-rich sediments in the New Jersey Atlantic Coastal Plain and were thought to account for the distinctive single-domain magnetic properties of these sediments. Uncalibrated strong field magnet extraction techniques have been typically used to provide material for scanning and transmission electron microscopic imaging of these magnetic particles, whose concentration in the natural sediment is thus difficult to quantify. In this study, we use a recently developed ultrahigh-resolution, synchrotron-based, full-field transmission X-ray microscope to study the iron-rich minerals within the clay sediment in their bulk state. We are able to estimate the total magnetization concentration of the giant biogenic magnetofossils to be only ∼10% of whole sediment. Along with previous rock magnetic studies on the CIE clay, we suggest that most of the magnetite in the clay occurs as isolated, near-equidimensional nanoparticles, a suggestion that points to a nonbiogenic origin, such as comet impact plume condensates in what may be very rapidly deposited CIE clays.

scholarly journals Phase Studies of Additively Manufactured Near Beta Titanium Alloy-Ti55511

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1723 ◽  
Author(s):  
Tuerdi Maimaitiyili ◽  
Krystian Mosur ◽  
Tomasz Kurzynowski ◽  
Nicola Casati ◽  
Helena Van Swygenhoven
Keyword(s):  
Phase Composition ◽  
Electron Beam Melting ◽  
Phase Changes ◽  
Full Density ◽  
Apparent Difference ◽  
Beta Titanium Alloy ◽  
Laser Melting ◽  
Powder Morphology ◽  
Beta Titanium ◽  
Powder Characteristics

The effect of electron-beam melting (EBM) and selective laser melting (SLM) processes on the chemical composition, phase composition, density, microstructure, and microhardness of as-built Ti55511 blocks were evaluated and compared. The work also aimed to understand how each process setting affects the powder characteristics after processing. Experiments have shown that both methods can process Ti55511 successfully and can build parts with almost full density (>99%) without any internal cracks or delamination. It was observed that the SLM build sample can retain the phase composition of the initial powder, while EBM displayed significant phase changes. After the EBM process, a considerable amount of α Ti-phase and lamella-like microstructures were found in the EBM build sample and corresponding powder left in the build chamber. Both processes showed a similar effect on the variation of powder morphology after the process. Despite the apparent difference in alloying composition, the EBM build Ti55511 sample showed similar microhardness as EBM build Ti-6Al-4V. Measured microhardness of the EBM build sample is approximately 10% higher than the SLM build, and it measured as 348 ± 30.20 HV.

scholarly journals Pain during Cast Wedging of Forearm Shaft and Distal Forearm Fractures in Children Aged 3 to 12 Years—A Prospective, Observational Study

Children ◽  
2020 ◽  
Vol 7 (11) ◽  
pp. 229
Author(s):  
Florian Freislederer ◽  
Tobias Berberich ◽  
Thomas O. Erb ◽  
Johannes Mayr
Keyword(s):  
Observational Study ◽  
Prospective Observational Study ◽  
Forearm Fracture ◽  
Lateral View ◽  
Oxygen Mixture ◽  
Forearm Fractures ◽  
Vas Score ◽  
Fractures In Children ◽  
Before And After ◽  
Multicenter Prospective Observational Study

Background: Although fracture displacement in children is easily treated by cast wedging, no data on pain associated with the procedure are available. We hypothesized that there is no clinically relevant difference in pain before and after cast wedging in children between 3 and 12 years of age. Patients and Methods: This international, multicenter, prospective, observational study included 68 children (39 male, 29 female) aged 3 to 12 years (median age 8 years) with forearm fractures. Cast wedging was performed 5 to 10 days after the injury. Before starting the procedure, we administered a single oral dose of sodium metamizole (10 mg/kg body weight), and the children inhaled a nitrous oxide/oxygen mixture (50%/50%) during the wedging procedure. Pain was rated on a visual analog scale (VAS) 5 to 10 min before incision of the cast as well as 3 to 5 min and 30 min (maximum remembered pain) after inhalation stop. The degree of bending was judged either by the surgeon or was determined on the basis of first signs of pain expressed by the patient. We assessed the effectiveness of the procedure by obtaining X-ray images in two planes after 3 to 9 days. Results: Among the 68 patients, median VAS score before cast wedging was 0. This increased to a score of 1 (p = 0.015) at 3 to 5 min after the procedure. Median VAS score for the maximum remembered pain measured after 30 min was 0. Median differences in angulation between proximal and distal bone fragments before and after the intervention were 0° (p < 0.0001) in the a.p. view and 8.4° (p < 0.0001) in the lateral view. Conclusion: Cast wedging improved the position of forearm fracture fragments at the expense of minimal short-term pain.

OMG Neutral Deinking Technical Conditions and Mechanism

2011 ◽  
Vol 236-238 ◽  
pp. 1351-1354 ◽  
Author(s):  
Xiao Lin Zhang ◽  
Ru Min Wang
Keyword(s):  
Electron Microscopy ◽  
Fiber Surface ◽  
Single Factor ◽  
Sem Images ◽  
Operation Conditions ◽  
Microscope Images ◽  
Before And After ◽  
Distribution State ◽  
Single Factor Experiment ◽  
Scanning Electron

Single factor experiment was used to investigate neutral deinking technology of old magazine paper (OMG) by self-compounded NTM-2 deinking agent. Olympus inverted biological microscope were used to research distribution state of ink particles in the secondary pulp before and after deinking treatment. Scanning electron microscopy (SEM) was used to analyze fiber surface changing during neutral deinking and ink particles dispersing behaviors in the paper. The results showed that NTM-2 deinking agent had a good deinking effect to OMG, optimum operation conditions of neutral deinking was NTM-2 0.5%, deinking temperature 50°C, deinking time 40min, repulper time 25s, pulp consistence 1.0%, and floatation time 6 min. Under these conditions, brightness of the deinked pulp increased 8.4%SBD, and the ink removal efficiency reached by 90%. Olympus inverted biological microscope images showed that there were a large number of ink particles in the un-treated pulp, and these ink particles integrated with fibers tightly. After treated by neutral deinking, most of ink particles were separated from the fiber, dispersed and suspended in the pulp evenly. SEM images indicated that there were little ink particles in the secondary paper, the fiber surface turned more smoother, and the clean degree would nearly corresponding to the effect of alkaline deinking.

Residual Stress in SLM Ti6Al4V Alloy Specimens

2015 ◽  
Vol 828-829 ◽  
pp. 305-310 ◽  
Author(s):  
Ina Yadroitsava ◽  
Stephen Grewar ◽  
Daniel Hattingh ◽  
Igor Yadroitsev
Keyword(s):  
Residual Stress ◽  
Laser Scanning ◽  
Complex Geometry ◽  
Ti6al4v Alloy ◽  
Innovative Technology ◽  
Full Density ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Principal Stresses ◽  
Before And After

Selective Laser Melting (SLM) presents a modern manufacturing process with an innovative technology which allows the production of full-density objects or fine-structured parts with complex geometry and inner structures. Stability and certification of the properties of SLM parts are important tasks for all producers and end-users. One of the drawbacks of this technology is high residual stress in as-made SLM objects. In this study X-ray diffraction technique was used for investigating the residual stress induced into SLM Ti6Al4V alloy samples. Principal stresses were estimated for the cut rectangular specimen. Two types of the cantilevers were produced and numerical simulation of the stress was performed. The bending of cut cantilevers was measured before and after heat treatment. Next series of the samples had rectangular shapes and different thicknesses from 1 to 46 layers. All as-manufactured specimens attached to the substrate showed the presence of tensile residual stresses near the top surface. Residual stress along the laser scanning direction had magnitudes twice that of the stress in the perpendicular direction. Conclusions regarding directions and values of stresses in SLM objects from Ti6Al4V powder are given.

Biomimetic Magnetic Nanoparticles for Hyperthermia Treatment

2011 ◽  
Vol 493-494 ◽  
pp. 16-19
Author(s):  
E.M. Múzquiz-Ramos ◽  
Dora A. Cortés-Hernández ◽  
C.G. Sánchez-Torres ◽  
José C. Escobedo-Bocardo ◽  
A. Zugasti ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Sol Gel ◽  
Apatite Layer ◽  
Apatite Formation ◽  
Temperature Profiles ◽  
Osteosarcoma Cell ◽  
Hyperthermia Treatment ◽  
Before And After ◽  
Magnetite Particles ◽  
Co Precipitation

The aim of this work was the synthesis of bioactive magnetic particles (BMP) which are expected to form a thin apatite layer on its surface that may bond to bone with the osseous carcinogen tissue. Magnetite and Mg0.6Ca0.4Fe2O4 nanoparticles were obtained by a reverse co-precipitation and sol-gel methods, respectively. Magnetite particles were coated with chitosan in order to obtain a stable ferrofluid. Then both ferrites were biomimetically treated using two different simulated body fluids (SBF and 1.5 SBF). An apatite layer was formed on both types of BMP after the biomimetic treatment. Both ferrites showed superparamagnetic behavior before and after the apatite formation. Their time-dependent temperature profiles were measured under the effect of an AC magnetic field (AMF). After less than 20 min of applying the AMF an appropriate temperature for hyperthermia treatment was obtained. No citotoxicity was observed after osteosarcoma cell culture testing of BMP. Furthermore, after applying an AMF to the cells in contact with the BMP, the cells viability decreased considerably.

scholarly journals Preparation of Associative Polyurethane Thickener and Its Thickening Mechanism Research

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Gao Nan ◽  
Zhang Zhuo ◽  
Dong Qingzhi
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Soft Segment ◽  
Synthesis Process ◽  
Segment Length ◽  
Solvent Ratio ◽  
Aqueous Dispersions ◽  
Before And After ◽  
Size And Morphology ◽  
End Capping

Associative polyurethane (PU) thickener has been synthesized by preparing the prepolymer with the reaction of polyethylene glycol (PEG) and isophorone diisocyanate (IPDI), which then end-capping with long-chain alkanol. The synthesis process, as well as hydrophilic chain length, theoretical molecular weight, solvent ratio, and thickener percentages, has been researched. The results shows that it reaches the upmost thickening effect when the theoretical molecular weight is under 20000, soft-segment length is under 4000, solvent ratio is 1 : 1, and thickener percentages are controlled at 10%. Furthermore, thickening mechanism of PU thickener has been analyzed detailedly through the measurement of the critical micelle concentration (CMC) of PU thickener and analysis of the influence of PU thickener on the particle size and morphology of PU dispersions. It has been observed from the scanning electron microscopy (SEM) that the PU aqueous dispersions produce a certain degree of flocculation when the PU thickener was added, and this flocculation structure has been proved to be a thixotropic structure through the characterization of the change of particle size before and after the thickener is introduced into the PU aqueous dispersions. The CMC measurement results present that the thickening effect will be apparent when the concentration is controlled in a low range.

scholarly journals Differences in the macrozoobenthic fauna colonising empty bivalve shells before and after invasion by Corbicula fluminea

2015 ◽  
Vol 66 (6) ◽  
pp. 549 ◽  
Author(s):  
M. I. Ilarri ◽  
A. T. Souza ◽  
V. Modesto ◽  
L. Guilhermino ◽  
R. Sousa
Keyword(s):  
Species Richness ◽  
Native Species ◽  
Benthic Communities ◽  
Corbicula Fluminea ◽  
Freshwater Bivalve ◽  
Before And After ◽  
Size And Morphology ◽  
Density And Biomass ◽  
Macrozoobenthic Community ◽  
Bivalve Shells

Bivalve shells can potentially alter the structure of aquatic benthic communities. However, little is known about the effect that different shell morphologies have on their associated fauna. This study aimed to understand how empty shells, from four different freshwater bivalve species, affect macrozoobenthic communities, using the River Minho (Iberian Peninsula) as a study area. Three native (Anodonta anatina, Potomida littoralis, Unio delphinus) and one non-indigenous (Corbicula fluminea) species were used for this research. Comparisons among species and between scenarios (i.e. before and after invasion by C. fluminea) were performed. Our results suggest that macrozoobenthic community structure did not vary among treatments, with the exception of species richness, which was higher on shells of native species. Furthermore, little difference was detected when comparing scenarios with and without C. fluminea shells, despite dissimilarities in size and morphology between species. The empty shells of C. fluminea partially (in terms of density and biomass, but not in species richness) replaced the role of empty shells of native species as a physical substratum for the associated macrozoobenthic community.

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