fine dispersion of oxide particles

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Radiation Response of Oxide Dispersion Strengthened Alloy

Radiation Response of Oxide Dispersion Strengthened Alloy

The composition of the 12Cr ODS dual-phase F/M alloy is provided in table 3.1. Elemental powders were mechanically alloyed in an argon gas atmosphere and con- solidated at 1100 ◦ C for 120 minutes. The consolidated specimens were then hot- extruded at 1150 ◦ C, normalized at 1050 ◦ C for 60 minutes before tempering at 800 ◦ C for another 60 mints hour. More extensive details of alloy synthesis have been reported by Ukai et. al [20]. The amount of excess oxygen (O) and titanium (Ti) was specially designed to enhance the strength of the material by achieving ultra-fine nano particles (∼2 nm) through element-compositional control, as shown in Fig 3.1 [19]. The ultra-fine nano particles were critical for to the material strength. Finer particles with a higher density are better at pinning dislocations, so that the grains with finer and denser dispersoids would be harder. Later we would show that ferrite phase preserves the particle distribution, leading to harder grains compared to tempered martensite grains [19].
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Oxide Dispersion Strengthened Steels for Advanced Blanket Systems

Oxide Dispersion Strengthened Steels for Advanced Blanket Systems

Oxide dispersion strengthened (ODS) steels have been developed for application to fuel claddings of fast reac- tors [18–25] where high performance materials properties are required to meet the severer conditions of in-core envi- ronment such as high doses of neutron irradiation at high temperatures. The ODS steel consists of a number of nano- scaled fine oxide particles in the matrix of the RAFM steel, and resultantly, the trapping sites for radiation defects in- crease with the number of the particles in comparison to the RAFM steel since the oxide particles/matrix (P/M) in- terfaces also play a role of trapping defects induced by ir- radiations [26]. The oxide particles also work as obstacles to dislocation motion providing strain field at the P/M in- terfaces, which results in the strengthening of the steel at elevated temperatures. As for compatibility issue, high-Cr ODS steels have much better corrosion resistance in a su- percritical pressurized water than the RAFM steels [27].
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Austenitic Oxide Dispersion Strengthened Steels : A Review

Austenitic Oxide Dispersion Strengthened Steels : A Review

stainless steel have been used widely in nuclear applications due to their excellent void swelling resistance, but their creep resistance is poor due to their open BCC structure. Austenitic stainless steels have high creep resistance but their void swelling resistance is lower when compared with ferritic steels. The creep and void swelling resistance in austenitic stainless steel can be improved by dispersing ultra-fine stable oxide particles. These oxide particles are expected to reduce grain coarsening and grain boundary sliding and thereby increase the creep resistance and the interface between these oxides and matrix can act as a sink for voids and increases the void swelling resistance in austenitic steels. These steels with oxide dispersions are termed as oxide dispersion strengthened steels (ODS). The evolution of oxide dispersion strengthening in steels has improved both high temperature and irradiation properties. Due to these characteristics of ODS steels, they have been widely studied 2,3 .
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Probing the stability of sterically stabilized polystyrene particles by centrifugal sedimentation

Probing the stability of sterically stabilized polystyrene particles by centrifugal sedimentation

particles initially form a more open particle bed structure under the applied centrifugal field (Figure 3b). These larger mass aggregates, when compared to stable individual particles, settle faster, leading to shorter sediment bed formation time, as seen in Figure 3 (Sample 2). Subsequently, as larger centrifugal forces

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Influence Of Adhesive Type And Particles Size On Compressed Charcoal Briquettes Manufacturing

Influence Of Adhesive Type And Particles Size On Compressed Charcoal Briquettes Manufacturing

Different kinds of adhesive have been used for briquettes production. But the most traditional one used was starch. Starch can be used from 4-8 % of adhesive weight by mixing it with hot water. Briquettes manufacturing can be performed by drying charcoal particles, screening and separating the small particles size. The large particles can be grounded and screened, this process followed by adding and mixing adhesive. ((From 15 – 20% of charcoal particles weight,)) then compressed stage was followed after filling the mixture in a small casts (moulds). After compression stage, drying of briquettes began at 80ْ C, the adhesive will hardened after moisture evaporation which lead to particles cohesion. The resulting briquettes can be used and utilized for heating stoves and cooking as any traditional charcoal. Many kinds of additives can be added to the charcoal briquettes to increase its efficiency and usage, such as chemical compound to increase combustion (e.g. wax, sodium nitrate) or emitting good smell during ignition (e.g. Incense, perfume added to hookah (shisha) smoking briquettes) (FAO, 1987). Grover and Mishra (1996) stated that size and shape of charcoal particles have great influence on specific gravity of resulting briquettes, the best particles size are between 6-8 mm, mixed with 10-20% of grounded and small particles in order to improve the strength, filling and packaging technique of the briquettes. Also, they clarify that moisture content have great influence on charcoal particles adhesion. They stated that in addition to adhesives added to charcoal particles, water work as adhesive material producing thin layer connecting charcoal particles with each other by Van Der Wall's forces. This process will increase connectivity area between the particles. Susgumaran and seshardri (2010) found that 200-250 gm of briquettes is enough to cook food in about 45-60 minutes. Also, they reported that the most important benefits which obtained from briquettes manufacturing compared with the traditional wood charcoal can be summarized as follow:
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Greener synthesis of electrospun collagen/hydroxyapatite composite fibers with an excellent microstructure for bone tissue engineering

Greener synthesis of electrospun collagen/hydroxyapatite composite fibers with an excellent microstructure for bone tissue engineering

collagen with HAP sol, the collagen/HAP composite nano- fiber before desalination showed that most of the particles were held along inside the collagen fibers, without any par- ticle exposure on the surface of the fibers (Figure 4B). Our attempts had been performed to figure out the distribution of HAP in the collagen matrix by means of TEM. Unfortunately, the HAP nanoparticles seemed to be covered by the salt accu- mulation, which made it quite difficult to differentiate where the HAP particle was and where the salt was. Although the mechanisms involved in the composite fiber formation were still unclear, the negative effects of salts existing in collagen or collagen/HAP fibers in the potential application were of no doubt. By the way, if these materials containing high salts were implanted inside the body, the excessive salt concen- trations would result in an ionic imbalance and increase the osmotic pressure in the extracellular fluid, which could cause cell dehydration and lead to plasmolysis or loss of cells activ- ity. More seriously, the blood volume would increase, caus- ing hypertension. Moreover, these large particles inside the collagen fibers could probably have a weak interaction with the collagen matrix, resulting in poor mechanical properties. Therefore, the use of PBS/ethanol system for collagen only was insufficient for manufacturing the collagen/HAP fibers, a further desalination for collagen solution was necessary. In this study, removing the salts was effectively achieved by dialysis of collagen solution, and the collagen fibers, after desalination, had a more uniform structure without any sign of particle formation (Figure 4C). More to the point, the collagen/HAP fibers after desalination were totally differ- ent from those before desalination. As clearly seen from Figure 4D, the HAP needles were well distributed within the electrospun fibers, and the HAP nanoparticles seemed to have a directional arrangement. The TEM of collagen/HAP spinning solution was presented in Figure 4E, it demonstrated that the needle-like HAP crystallites with a clear boundary were co-embedded in the collagen solution. After electrospin- ning, the HAP nanoparticles could completely retain their needle-shape in the collagen matrix, and were well-aligned along the axis of the electrospun fiber, which can be seen from the TEM image with a higher resolution (Figure 4F). The HAP crystallites had a crystal particle size range from 20 to 60 nm, close to those found in mammalian bone, 59 and
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The role of surface charge in cellular uptake and cytotoxicity of medical nanoparticles

The role of surface charge in cellular uptake and cytotoxicity of medical nanoparticles

Main influencing factors for cytotoxicity are material, size, shape, composition, surface charge, and surface hydrophobicity. The correlation of cytotoxic effect and size has been studied in many papers. For nonphagocytic cells, small size correlates with increased cytotoxicity. In vitro experiments showed higher cytotoxicity of well-dispersed mesoporous silica and amorphous silica, dolomite, ZnO, Ni, Ag, and polystyrene NPs compared to the respective microparticles. 6–15 When particles smaller than 100 nm are

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Preparation and characterization of nanostructured barium oxide

Preparation and characterization of nanostructured barium oxide

It was found that the basic catalytic property of the metal oxide was increase with high surface area and nanosized particles. In this study, surface modified Barium oxide (BaO) was synthesized by hydration-dehydration method. Barium hydroxide ( Ba(OH) 2 ) has prepared from Barium Peroxide (BaO 2 ) which acted as

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Dispersion of SiO2 Nano Particles on Epoxy Based Polymer Nano Composites and its Characterization

Dispersion of SiO2 Nano Particles on Epoxy Based Polymer Nano Composites and its Characterization

In this work AFM was carried on NT-MDT NEXT Solver (make-Russia) at Physics Laboratory of M.A.N.I.T, Bhopal. AFM grain analysis Fig. 7, Fig. 8 and Fig. 9 it can very well be interpreted that on increasing the weight percentage loading of SiO 2 nanoparticles in the epoxy matrix, the number of grains show a decreasing trend whereas diameter, average size and area show increasing trend, this concludes that high weight percentage loading clustering and agglomerations of the nanoparticles take place inside resin matrix thereby increasing the average size of the grains. at lower weight percentage of nano particles loading within the epoxy polymer matrix there are proper dispersion of nano particles but on increasing the weight percent of nano particles of SiO 2 agglomeration increases drastically within the matrix.
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Evaluation of the search and rescue LEEWAY model in the Tyrrhenian Sea: a new point of view

Evaluation of the search and rescue LEEWAY model in the Tyrrhenian Sea: a new point of view

In many cases, SAR activities may also require fields of interest on a high spatial resolution. Subregional forecast sys- tems that can resolve small-scale processes as well as fronts characteristics of the study area are necessary. A numeri- cal technique widely used in operational oceanography to increase the horizontal resolution is the downscaling pro- cedure (Pinardi et al., 2003). It permits the transmission of information at the interconnecting boundaries (temperature, salinity and velocity) from the coarse-resolution grid to the fine-resolution grid (Sorgente et al., 2003). This has been achieved through implementation of a nested high-resolution ocean model for the central Mediterranean Basin developed in the framework of the project Development of TEchnology for Situational Sea Awareness (TESSA). This hydrodynamic model, named Tyrrhenian Sicily Channel Regional Model (TSCRM), is based on the Princeton Ocean Model (POM) (Blumberg and Mellor, 1987) and has a horizontal resolution of 1/48 ◦ , equal to 3 times that of MFS.
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4746.pdf

4746.pdf

The percent carbon from elemental analysis, %C, number of carbons in the attached ligand, nC, specific surface area, SSA, and molecular weight of the attached ligand, MW are used to calculate the bonding surface coverage of the particles. The presence of the ligand side groups prevents higher surface coverage due to steric hindrance. Variation in the surface coverage and homogeneity occurs when the water content of the solvents is not controlled, there is water remaining on the particle surface, or multidentate ligands are used.[12-13] Multidentate ligands such as di-functional silanes produce attachment with only one siloxane bond one-half of the time while the other half are bonded by two siloxane bonds.[11] This results in no greater surface coverage, but produces slightly more stable bonding chemistry. Furthermore, due to the presence of an additional leaving group on the di-functional ligand with only one siloxane bond, an additional silanol group is produced. Therefore the number of free silanols is the same as for bondings using a mono-functional silane. When a tri- functional silane is used, the amount of free silanols is found to be greater than that for mono- and di-functional slianes since tridentate siloxane bond formation is impossible.[11] Further variation of the bonded phase occurs when di- and tri-functional silanes are used due to the ability of polymerization, particularly when water is present in the system. For these reasons, a mono-functional silane is typically used to ensure production of a reproducible, dense, and homogeneous monomeric layer.[12]
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Synthesis of Thermoelectric Fe0 98Co0 02Si2 with Fine Ag Dispersion by Mechanical Milling with AgO Powder

Synthesis of Thermoelectric Fe0 98Co0 02Si2 with Fine Ag Dispersion by Mechanical Milling with AgO Powder

showed that Ag was hardly detected in both the phase and the " phase, indicating that Ag atoms were not substituted for Fe and Si site in these phases and precipitated as the metallic Ag phase. As shown in Fig. 1, a large proportion of the " phase was also precipitated through the reaction of AgO with phase. These precipitated " particles were found to be dispersed in the phase matrix as compared to those in the conventionally prepared -FeSi 2 samples. 23) As shown in the

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Flame development in pulverised biomass for fine and coarse particles

Flame development in pulverised biomass for fine and coarse particles

Andrews, GE orcid.org/0000-0002-8398-1363, Slatter, DJF, Saeed, MA et al. (3 more authors) (2016) Flame development in pulverised biomass for fine and coarse particles. In: Proceedings of the 11th European Conference on Coal Research and Its Applications, 11th ECCRIA. 11th European Conference on Coal Research and Its Applications, 11th

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Effect of Titanium Dioxide Nanogel Surface Charges and Particle Size on Anti-Corrosion Performances of Epoxy Coatings

Effect of Titanium Dioxide Nanogel Surface Charges and Particle Size on Anti-Corrosion Performances of Epoxy Coatings

charges assist them to increase the dispersion of particles into epoxy coatings and enhance the adhesion force of films to steel substrate. Therefore, it can be concluded that the increment of nanogel layer thickness on the titanium dioxide surfaces increases the surface charges of composite to achieve better corrosion protection performance.

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Semiclassical theory of matter-wave detection

Semiclassical theory of matter-wave detection

In nature particles exist in either of two forms: those with integer spin and those with half-integer spin. The former of these are known as bosons, and the latter as fermions. At a microscopic level, fermions are guided by the Pauli exclusion principle, which states that no two fermions can occupy the same quantum state. On the other hand, there is no such principle affecting bosons, and thus any number can occupy the same state. This is the basis of Bose-Einstein condensation, which was first proposed theoretically by Bose and Einstein in 1924 [1, 2, 3]. A Bose-Einstein condensate (BEC) is a system in which a macroscopic number of bosons occupy a single quantum state. To achieve this with a dilute gas of atomic bosons requires extremely low temperatures, such that the de-Broglie wavelength of the particles become larger than their mean spacing. Hence no BEC was experimentally realized in these systems until 1995 [4, 5, 6] using bosonic isotopes of Rb, Na and Li.
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Translocation of particles and inflammatory responses after exposure to fine particles and nanoparticles in an epithelial airway model

Translocation of particles and inflammatory responses after exposure to fine particles and nanoparticles in an epithelial airway model

of 1 µm and 0.078 µm particles inside MDM was twice the number found in MDDC. This finding confirms what was reported by Kiama et al. [39] who showed that MDM are twice as phagocytic as immature MDDC in vitro. Only a small particle number was found inside epithelial cells for both particle sizes. The quantitative analysis for the NP distribution in the different cell types was performed as described by Mühlfeld et al. [40]. One main conclusion that can be drawn from this analysis is that the distribu- tion of particles within the different cell types is not equal among the different particle sizes. The difference is char- acterized by a significant lower number of NP to be local- ized in the MDDC in comparison to the larger particles. Conversely, the number of particles localized in MDM was higher than expected for 0.078 µm NP and lower than expected for the larger particles. Recently, we have shown that MDDC and MDM collaborate as sentinels against fine particles by building a transepithelial interdigitating network of cell processes [41], so the current data under- line that fine particles might actively be transported from MDM to MDDC, whereas the nano-sized material has dif- ferent translocation characteristics. It is tempting to spec- ulate that the unique entering mechanisms of NP may prevent the physiological interplay between macrophages and dendritic cells to a certain degree. Concluding from our results and from earlier published findings [11,25] we confirmed the phagocytic uptake for 1 µm particles whereas particles < 0.1 µm may have the property of enter- ing cells by unknown mechanisms (what we called adhe- sive interaction).
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Segregation patterns in gas-fluidized systems

Segregation patterns in gas-fluidized systems

New observations of the formation of segregration patterns in fluidized binary systems have been reported and physical models of their development and form are described. It has been shown that a bed consisting of a mixture of particles of different sizes can have a variety of different structures depending on the gas flow rate through it. These structures arise when one or both of the components of the mixture become fluidized so that their weight is supported. This greatly reduces the friction between the particles and thus allows them to become mobile. The different structures occur because they cause the flow through the bed to be heterogeneous and the effect it has on the particles differs according to the local proportions of each component of the mixture. Segregation can persist when the gas flow rate is sufficiently large to fluidize the entire bed. Under such conditions it can be shown that the segregation behaviour can be successfully modelled by drawing an analogy with the sedimentation of particles from a turbulent flow field. The experimental results suggest that the efficiency of mixing by the bubbles in a fluidized bed is very much less than for gas bubbles in a liquid.
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Coarse-particle flotation applied to copper sulfide ores

Coarse-particle flotation applied to copper sulfide ores

One of the recurring problems in most concentrator plants is the significant loss of valuable elements in particle size fractions coarser than 150 µm. As mentioned at the beginning of this document, these losses occurred because of issues related to the mineral liberation needed to be recovered in conventional cells as well as the principle of operation of conventional cells. Conventional cells, due to the turbulence generated by rotors promote loss of adherence of the coarse particles that were collected in the air bubbles. Despite this, copper concentrating plants have been increasing the P80 at which they perform flotation, and currently in Peru most of them have been working with P80 (in rougher stages) greater than 150 µm, even up to 250 µm. This issue was observed in one of the large mining Cu/Mo concentrator plants in southern Peru. A sampling program of the plant allowed identifying that approximately 47% of copper and 43% of moly that is lost in the rougher tailings is contained in particle sizes coarser than 150 µm. Knowing this, it was decided to take a sample from the rougher tailings, and to carry out Coarse-
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Dispersion Polymerization of Polystyrene Particles Using Alcohol as Reaction Medium

Dispersion Polymerization of Polystyrene Particles Using Alcohol as Reaction Medium

In this article, the reactant composition was adjusted by changing the amount of water to study the variation of the size of polystyrene nanospheres. Figure 7 contains the change of particle size as a function of the amount of styrene with respect to the amount of water. As con- tained in the graph of Fig. 7, the size reduction was ob- served as the increasing amount of water, possibly due to the increase of dielectric constant of dispersion medium. Also important to note is that the surface elec- tric charge due to amine groups derived from MTC would increase with increasing amount of water in the reaction medium, affecting the size reduction of the polystyrene nanospheres. Since the miscibility of styrene decreases with increasing amount of water, the addition of water may cause the gradual change from dispersion polymerization to emulsion polymerization, resulting in the size reduction of the polymeric particles. Usually, emul- sion polymerization can be applied to prepare submicron- sized particles whereas dispersion polymerization can be adopted for the synthesis of larger particles with 2 to 12 μm in diameter [22]. If homogeneous solution cannot be maintained due to excess amount of water, hetero-phase polymerization may be started out from the monomer source of immiscible droplets and smaller particles can be favored from the monomer-swollen micelles.
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Accumulation of fine particles onto three coniferous species

Accumulation of fine particles onto three coniferous species

The average mass concentration in the chamber was measured using a 47mm QMA quartz microfiber filter (Whatman, Piscataway, NJ) inside a closed cassette. Filter sampling was conducted at 0.5 LPM using a mass flow controller (MKS Instruments, Andover, MA). A second probe drew sample at 0.3 LPM to a scanning mobility particle sizer (SMPS, TSI Inc., Shoreview, MN) equipped with a condensation particle counter (CPC, TSI Inc., Shoreview, MN), that counted particles by light scattering. These instruments produced particle size distributions at 5-minute intervals. Additional sampling information is found in Appendix B.
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