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Journal articles on the topic 'Wall Nucleation'

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Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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1

de Campos, Marcos Flavio, and José Adilson de Castro. "The Critical Volume for Nucleation." Materials Science Forum 660-661 (October 2010): 279–83. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.279.

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In magnets based in phases with high magnetocrystalline anisotropy like Nd2Fe14B or SmCo5 there is a competition between magnetostatic energy and domain wall energies. If the grain size is large, the formation of domain walls is energetically favorable. When the formation of domain walls is an unfavorable process, coercivity is larger. A better comprehension of this phenomenon is possible if the energy necessary for the first domain wall formation is properly evaluated. To address this problem, the magnetostatic energy of a sphere magnetized in two opposite directions, separated by a domain wall, is calculated using Legendre Polynomials. The data allow the determination of the reversible volume for nucleation. It is predicted a “recoil effect”, the magnetization may be reversible until a given volume of reverse magnetization.

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2

Osuna Ruiz, D., O. Alejos, V. Raposo, and E. Martínez. "Geometrical design for pure current-driven domain wall nucleation and shifting." Applied Physics Letters 121, no. 10 (September 5, 2022): 102403. http://dx.doi.org/10.1063/5.0106689.

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Nucleation of domain walls by current-driving a single domain wall, confined to the junction area of two symmetrical strips, is investigated using systematic micromagnetic simulations. Secondary domain walls (equivalently, bits encoded in domains) are simultaneously nucleated and driven by alternatively applying current pulses between two terminals in the structure. Simulations show that nanosecond-duration current pulses nucleate and drive series of robust up/down domains even under realistic conditions. These results demonstrate a technique for sequentially nucleating and shifting domain walls without using attached external “bit lines,” fields, or modifying the ferromagnetic strip.

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3

Kondo, Seishi. "Quantum nucleation on a wall." Physica B: Condensed Matter 329-333 (May 2003): 384–85. http://dx.doi.org/10.1016/s0921-4526(02)02134-8.

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4

Ehrhart, S., and J. Curtius. "Influence of aerosol lifetime on the interpretation of nucleation experiments with respect to the first nucleation theorem." Atmospheric Chemistry and Physics 13, no. 22 (November 26, 2013): 11465–71. http://dx.doi.org/10.5194/acp-13-11465-2013.

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Abstract. The SAWNUC (Sulphuric Acid Water NUCleation) microphysical aerosol nucleation model is used to study the effect of reactor walls on the interpretation of nucleation experiments with respect to nucleation theory. This work shows that loss processes, such as wall losses, influence the interpretation of nucleation experiments, especially at low growth rates and short lifetimes of freshly nucleated particles. In these cases the power dependency of the formation rates, determined at a certain particle size, with respect to H2SO4 does not correspond to the approximate number of H2SO4 molecules in the critical cluster as expected by the first nucleation theorem. Observed ∂log(J)/∂log([H2SO4]) therefore can vary widely for identical nucleation conditions but different sink terms.

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5

He, X., E. K. H. Salje, X. Ding, and J. Sun. "Immobile defects in ferroelastic walls: Wall nucleation at defect sites." Applied Physics Letters 112, no. 9 (February 26, 2018): 092904. http://dx.doi.org/10.1063/1.5021542.

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6

Hadikhani, Pooria, S. Mohammad H. Hashemi, Steven A. Schenk, and Demetri Psaltis. "A membrane-less electrolyzer with porous walls for high throughput and pure hydrogen production." Sustainable Energy & Fuels 5, no. 9 (2021): 2419–32. http://dx.doi.org/10.1039/d1se00255d.

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7

Ehrhart, S., and J. Curtius. "Influence of aerosol lifetime on the interpretation of nucleation experiments with respect to the first nucleation theorem." Atmospheric Chemistry and Physics Discussions 13, no. 4 (April 12, 2013): 9733–50. http://dx.doi.org/10.5194/acpd-13-9733-2013.

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Abstract. The SAWNUC microphysical aerosol nucleation model is used to study the effect of reactor walls on the interpretation of nucleation experiments with respect to nucleation theory. This work shows that loss processes, such as wall losses, influence the interpretation of nucleation experiments, especially at low growth rates and short lifetime of freshly nucleated particles. In these cases the power dependency of the formation rates, determined at a certain particle size, with respect to H2SO4 does not correspond to the approximate number of H2SO4 molecules in the critical cluster as expected by the first nucleation theorem. Observed ∂log(J)/∂log([H2SO4]) therefore can vary widely for identical nucleation conditions but different sink terms.

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8

Shen, Fanyi, Rongfu Gao, Wenji Liu, Wenjie Zhang, and Qi Zhao. "421 Thermodynamic Analysis on Mechanism of Deep Supercooling of Tissue Water in Winter-hardy Plants." HortScience 35, no. 3 (June 2000): 465F—466. http://dx.doi.org/10.21273/hortsci.35.3.465f.

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It is known that the redistribution of water and the formation of dispersed water units appears to be a prerequisite for deep supercooling. A concentration of the cell solute results from the migration of water during extracelullar freezing and lowers the temperature of homogeneous nucleation, but we are convinced that nucleation of ice within cells may be initiated by a heterogeneous mechanism, except we consider a small spherical cave, the water can freeze on the wall of this cave. We are also convinced that the solid walls of the capillary exert an external potential on the water molecules, causing the shift of the triple point of the confined fluids. Based on Fletcher's work for spherical particle, we have gotten the formula of critical free energy in the process of heterogeneous nucleation of water in a small spherical cave. This presentation introduces the theoretical background and counts the drop of temperature in heterogeneous nucleation. Then, putting two actions (depression of triple point and process of heterogeneous nucleation) together, we have calculated the freezing point. Sometimes it is lower than –38 °C. Some phenomena can be explained by using this theory: 1) Water is at the tension status, which means that it wets plant tissue, so the triple point (melting point) of tissue water can be lowered. 2) The redistribution of water, formation of dispersed water units, and dry region preventing ice from propagating, all allow heterogeneous nucleation, then the two actions can be synthesized and the water would lead to deep supercooling. If the barriers were destroyed, heterogeneous nucleation and deep supercooling would certainly be lost. 3) This theory is only suited to rigid wall of small cave, so we understand why cell wall rigidity has been shown to affect freezing characteristics. Project 39870234 supported by National Nature Science Foundation.

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9

Winkler, S., W. Reim, and K. Schuster. "Domain nucleation and wall movement in TbFeCo." Thin Solid Films 175 (August 1989): 265–71. http://dx.doi.org/10.1016/0040-6090(89)90838-9.

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10

Skomski, R., T. A. George, and D. J. Sellmyer. "Nucleation and wall motion in graded media." Journal of Applied Physics 103, no. 7 (April 2008): 07F531. http://dx.doi.org/10.1063/1.2835483.

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11

Brooks, Caleb S., and Takashi Hibiki. "Wall nucleation modeling in subcooled boiling flow." International Journal of Heat and Mass Transfer 86 (July 2015): 183–96. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.03.005.

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12

Stojanovic, Andrijana, Vladimir Stevanovic, Milan Petrovic, and Dragoljub Zivkovic. "Numerical investigation of nucleate pool boiling heat transfer." Thermal Science 20, suppl. 5 (2016): 1301–12. http://dx.doi.org/10.2298/tsci160404276s.

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Multidimensional numerical simulation of the atmospheric saturated pool boiling is performed. The applied modelling and numerical methods enable a full representation of the liquid and vapour two-phase mixture behaviour on the heated surface, with included prediction of the swell level and heated wall temperature field. In this way the integral behaviour of nucleate pool boiling is simulated. The micro conditions of bubble generation at the heated wall surface are modelled by the bubble nucleation site density, the liquid wetting contact angle and the bubble grow time. The bubble nucleation sites are randomly located within zones of equal size, where the number of zones equals the nucleation site density. The conjugate heat transfer from the heated wall to the liquid is taken into account in wetted heated wall areas around bubble nucleation sites. The boiling curve relation between the heat flux and the heated wall surface temperature in excess of the saturation temperature is predicted for the pool boiling conditions reported in the literature and a good agreement is achieved with experimentally measured data. The influence of the nucleation site density on the boiling curve characteristic is confirmed. In addition, the influence of the heat flux intensity on the spatial effects of vapour generation and two-phase flow are shown, such as the increase of the swell level position and the reduced wetting of the heated wall surface by the heat flux increase.

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13

Zexer, Nerya, and Rivka Elbaum. "Unique lignin modifications pattern the nucleation of silica in sorghum endodermis." Journal of Experimental Botany 71, no. 21 (March 9, 2020): 6818–29. http://dx.doi.org/10.1093/jxb/eraa127.

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Abstract Silicon dioxide in the form of hydrated silica is a component of plant tissues that can constitute several percent by dry weight in certain taxa. Nonetheless, the mechanism of plant silica formation is mostly unknown. Silicon (Si) is taken up from the soil by roots in the form of monosilicic acid molecules. The silicic acid is carried in the xylem and subsequently polymerizes in target sites to silica. In roots of sorghum (Sorghum bicolor), silica aggregates form in an orderly pattern along the inner tangential cell walls of endodermis cells. Using Raman microspectroscopy, autofluorescence, and scanning electron microscopy, we investigated the structure and composition of developing aggregates in roots of sorghum seedlings. Putative silica aggregation loci were identified in roots grown under Si starvation. These micrometer-scale spots were constructed of tightly packed modified lignin, and nucleated trace concentrations of silicic acid. Substantial variation in cell wall autofluorescence between Si+ and Si– roots demonstrated the impact of Si on cell wall chemistry. We propose that in Si– roots, the modified lignin cross-linked into the cell wall and lost its ability to nucleate silica. In Si+ roots, silica polymerized on the modified lignin and altered its structure. Our work demonstrates a high degree of control over lignin and silica deposition in cell walls.

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14

Liao, L., M. Dal Maso, D. Mogensen, P. Roldin, A. Rusanen, V. M. Kerminen, T. F. Mentel, et al. "Modelling the contribution of biogenic VOCs to new particle formation in the Jülich plant atmosphere chamber." Atmospheric Chemistry and Physics Discussions 14, no. 20 (November 12, 2014): 27973–8018. http://dx.doi.org/10.5194/acpd-14-27973-2014.

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Abstract. We used the MALTE-BOX model including near-explicit air chemistry and detailed aerosol dynamics to study the mechanisms of observed new particle formation events in the Jülich Plant Atmosphere Chamber. The modelled and measured H2SO4 (sulfuric acid) concentrations agreed within a factor of two. The modelled total monoterpene concentration was in line with PTR-MS observations, and we provided the distributions of individual isomers of terpenes, when no measurements were available. The aerosol dynamic results supported the hypothesis that H2SO4 is one of the critical compounds in the nucleation process. However, compared to kinetic H2SO4 nucleation, nucleation involving OH oxidation products of monoterpenes showed a better agreement with the measurements, with R2 up to 0.97 between modelled and measured total particle number concentrations. The nucleation coefficient for kinetic H2SO4 nucleation was 2.1 × 10−11 cm3 s−1, while the organic nucleation coefficient was 9.0 × 10−14 cm3 s−1. We classified the VOC oxidation products into two sub-groups including extremely low-volatility organic compounds (ELVOCs) and semi-volatile organic compounds (SVOCs). These ELVOCs and SVOCs contributed approximately equally to the particle volume production, whereas only ELVOCs made the smallest particles to grow in size. The model simulations revealed that the chamber walls constitute a major net sink of SVOCs on the first experiment day. However, the net wall SVOC uptake was gradually reduced because of SVOC desorption during the following days. Thus, in order to capture the observed temporal evolution of the particle number size distribution, the model needs to consider reversible gas-wall partitioning.

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15

Ingle, S. G., H. C. Dutta, and A. P. David. "Domain wall nucleation evidenced on naturally grown surfaces." Journal of Physics D: Applied Physics 21, no. 7 (July 14, 1988): 1239–40. http://dx.doi.org/10.1088/0022-3727/21/7/030.

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16

Kimura, T., and Y. Otani. "Domain wall nucleation assisted by nonlocal spin injection." Journal of Physics D: Applied Physics 40, no. 5 (February 16, 2007): 1285–88. http://dx.doi.org/10.1088/0022-3727/40/5/s14.

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17

Beuneu, F. "Nucleation and growth of single wall carbon nanotubes." Solid State Communications 136, no. 8 (November 2005): 462–65. http://dx.doi.org/10.1016/j.ssc.2005.09.007.

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18

Scott, J. F. "Mesoscopic Dielectrics." Australian Journal of Physics 52, no. 5 (1999): 903. http://dx.doi.org/10.1071/ph98094.

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This paper describes four unsolved theoretical problems in ferroelectrics and related dielectrics with high permittivities: (1) finite size effects in thin films and small particles, and their relationship to depolarisation fields; (2) nucleation and growth kinetics, and especially the recently discovered coherent nucleation of small domains in front of advancing walls; (3) low-temperature quantum effects in ferroelectrics and the process of ‘freeze-out’, in which domain wall mobilities suddenly drop to zero; (4) self-patterning of nanoscale assemblies on the surfaces of substrates, and the consideration of lateral finite size effects.

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19

ZHANG, LI, JIE-GANG PENG, ZHI-YONG ZHONG, and XIAO-TAO ZU. "STUDY OF DOMAIN WALL MOTION OF ROUND MARKS IN AN EXCHANGE-COUPLED CoNi/Pt FILM." Nano 04, no. 01 (February 2009): 41–45. http://dx.doi.org/10.1142/s1793292009001496.

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We study the motion of domain wall in round marks formed in an exchange-coupled CoNi/Pt film, suitable for perpendicular magnetic recording. Marks were written by probe-based magnetic recording, with an average size of 180 nm. By applying external magnetic field on those marks, they begin to shrink. The minimum field required to move the domain wall of marks, i.e., domain wall coercivity, is 60% the nucleation coercivity of the medium. A model of dynamic domain motion was executed to study the stability of magnetic domains in exchange-coupled perpendicular media. It shows that the domain wall coercivity is a better fit than the nucleation coercivity to calculate the minimum stable domain size of the medium.

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20

Kamasaki, Tomoko, Eileen O’Toole, Shigeo Kita, Masako Osumi, Jiro Usukura, J. Richard McIntosh, and Gohta Goshima. "Augmin-dependent microtubule nucleation at microtubule walls in the spindle." Journal of Cell Biology 202, no. 1 (July 1, 2013): 25–33. http://dx.doi.org/10.1083/jcb.201304031.

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The formation of a functional spindle requires microtubule (MT) nucleation from within the spindle, which depends on augmin. How augmin contributes to MT formation and organization is not known because augmin-dependent MTs have never been specifically visualized. In this paper, we identify augmin-dependent MTs and their connections to other MTs by electron tomography and 3D modeling. In metaphase spindles of human cells, the minus ends of MTs were located both around the centriole and in the body of the spindle. When augmin was knocked down, the latter population of MTs was significantly reduced. In control cells, we identified connections between the wall of one MT and the minus end of a neighboring MT. Interestingly, the connected MTs were nearly parallel, unlike other examples of end–wall connections between cytoskeletal polymers. Our observations support the concept of augmin-dependent MT nucleation at the walls of existing spindle MTs. Furthermore, they suggest a mechanism for maintaining polarized MT organization, even when noncentrosomal MT initiation is widespread.

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21

Carey, Van P., Jorge Padilla, and Yu Gan. "Homogeneous Nucleation of Vapor at Preferred Sites During Rapid Transient Heating of Liquid in Micropassages." Journal of Heat Transfer 129, no. 10 (December 9, 2006): 1333–40. http://dx.doi.org/10.1115/1.2754989.

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Rapid heating of a liquid at the wall of a micropassage may produce homogeneous nucleation of vapor in the liquid in contact with the surface. In such circumstances, nucleation is generally expected to be most likely to occur in the hottest liquid closest to the surface. It is known, however, that in many cases, the liquid molecules closest to the surface will experience long-range attractive forces to molecules in the solid, with the result that the equation of state for the liquid near the surface will differ from that for the bulk liquid. In micro- and nanopassages, this wall-affected region may be a significant fraction of the passage interior volume. Recent investigations of wall force effects on the liquid indicate that these forces increase the spinodal temperature in the near-surface region. The results of these previous investigations suggest that for heated surfaces with nanoscale roughness, protrusion of bulk fluid into crevices in the surface may make them preferred sites for homogeneous nucleation during rapid heating. A detailed model analysis of the heat transfer in a model conical crevice is developed and used to explore the plausibility and apparent mechanisms of preferred-site homogeneous nucleation. The analysis predicts that protrusion of bulk liquid into a conical cavity does, under some conditions, make the cavity a preferred site for the first occurrence of homogeneous nucleation. The analysis is used to examine the range of conditions under which a crevice will be a preferred site. The implications for nucleation near a solid surface during rapid heating are also explored for circumstances similar to those for bubble nucleation adjacent to heaters in microheater reservoirs in inkjet printer heads.

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22

Basu, Nilanjana, Gopinath R. Warrier, and Vijay K. Dhir. "Onset of Nucleate Boiling and Active Nucleation Site Density During Subcooled Flow Boiling." Journal of Heat Transfer 124, no. 4 (July 16, 2002): 717–28. http://dx.doi.org/10.1115/1.1471522.

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The partitioning of the heat flux supplied at the wall is one of the key issues that needs to be resolved if one is to model subcooled flow boiling accurately. The first step in studying wall heat flux partitioning is to account for the various heat transfer mechanisms involved and to know the location at which the onset of nucleate boiling (ONB) occurs. Active nucleation site density data is required to account for the energy carried away by the bubbles departing from the wall. Subcooled flow boiling experiments were conducted using a flat plate copper surface and a nine-rod (zircalloy-4) bundle. The location of ONB during the experiments was determined from visual observations as well as from the thermocouple output. From the data obtained it is found that the heat flux and wall superheat required for inception are dependent on flow rate, liquid subcooling, and contact angle. The existing correlations for ONB underpredict the wall superheat at ONB in most cases. A correlation for predicting the wall superheat and wall heat flux at ONB has been developed from the data obtained in this study and that reported in the literature. Experimental data are within ±30 percent of that predicted from the correlation. Active nucleation site density was determined by manually counting the individual sites in pictures obtained using a CCD camera. Correlations for nucleation site density, which are independent of flow rate and liquid subcooling, but dependent on contact angle have been developed for two ranges of wall superheat—one below 15°C and another above 15°C.

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23

Shin, Young-Han, Ilya Grinberg, I.-Wei Chen, and Andrew M. Rappe. "Nucleation and growth mechanism of ferroelectric domain-wall motion." Nature 449, no. 7164 (October 2007): 881–84. http://dx.doi.org/10.1038/nature06165.

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24

Hayashi, Masamitsu, Yukiko K. Takahashi, and Seiji Mitani. "Microwave assisted resonant domain wall nucleation in permalloy nanowires." Applied Physics Letters 101, no. 17 (October 22, 2012): 172406. http://dx.doi.org/10.1063/1.4764053.

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25

Beuneu, François. "Nucleation of single wall carbon nanotubes of various chiralities." Solid State Communications 152, no. 13 (July 2012): 1155–59. http://dx.doi.org/10.1016/j.ssc.2012.03.041.

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26

Mazo-Zuluaga, J., E. A. Velásquez, D. Altbir, and J. Mejía-López. "Controlling domain wall nucleation and propagation with temperature gradients." Applied Physics Letters 109, no. 12 (September 19, 2016): 122408. http://dx.doi.org/10.1063/1.4963181.

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27

O’Brien, L., D. E. Read, D. Petit, and R. P. Cowburn. "Dynamic propagation and nucleation in domain wall nanowire devices." Journal of Physics: Condensed Matter 24, no. 2 (December 15, 2011): 024222. http://dx.doi.org/10.1088/0953-8984/24/2/024222.

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28

Camejo, M. D., and L. L. Bonilla. "Theory of homogeneous vapour condensation and surface deposition from boundary layers." Journal of Fluid Mechanics 706 (July 6, 2012): 534–59. http://dx.doi.org/10.1017/jfm.2012.278.

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AbstractHomogeneous condensation of vapours mixed with a carrier gas in the stagnation point boundary layer flow near a cold wall is considered. There is a condensation region near the wall with supersaturated vapour. Assuming that the surface tension times the molecular area is much larger than the thermal energy far from the wall, droplets are nucleated exclusively in a narrow nucleation layer where the Zeldovich flux of clusters surpassing the critical nucleus size is at a maximum. The vapour condenses in the free molecular regime on the droplets, which are thermophoretically attracted to the wall. Unlike the narrow condensation region for heterogeneous condensation on solid particles, in the case of homogeneous condensation the condensation region is wide even when the rate of vapour scavenging by droplets is large. A singular perturbation theory of homogeneous vapour condensation in boundary layer flow approximates very well the vapour and droplet density profiles, the nucleation layer and the deposition rates at the wall for wide ranges of the wall temperature and the scavenging parameter $B$. A key point in the theory is to select a trial vapour number density profile among a one parameter family of profiles between an upper and a lower bound. The maximum of the Zeldovich flux for supercritical nuclei provides the approximate location of the nucleation layer and an approximate droplet density profile. Then the condensate number of molecules and the vapour density profile are calculated by matched asymptotic expansions that also yield the deposition rates. For sufficiently large wall temperatures, a more precise corrected asymptotic theory is given.

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29

Beveridge, T. J., and W. S. Fyfe. "Metal fixation by bacterial cell walls." Canadian Journal of Earth Sciences 22, no. 12 (December 1, 1985): 1893–98. http://dx.doi.org/10.1139/e85-204.

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All biomass contains a significant quantity of metallic constituents, and mineralization in living and dead biodebris may contribute to element transport from the hydrosphere into sediments. The anionic cell walls of bacteria are remarkable in their ability to fix metals and provide sites for nucleation and growth of minerals. Results presented show the types of cell wall polymers that are responsible for metal binding in walls of Gram-positive and Gram-negative bacteria.

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30

Favieres, Cristina, José Vergara, and Vicente Madurga. "Surface Roughness Influence on Néel-, Crosstie, and Bloch-Type Charged Zigzag Magnetic Domain Walls in Nanostructured Fe Films." Materials 13, no. 19 (September 24, 2020): 4249. http://dx.doi.org/10.3390/ma13194249.

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Charged magnetic domain walls have been visualized in soft magnetic nanostructured Fe thin films under both static and dynamic conditions. A transition in the core of these zigzagged magnetic walls from Néel-type to Bloch-type through the formation of crosstie walls has been observed. This transition in charged zigzagged walls was not previously shown experimentally in Fe thin films. For film thicknesses t < 30 nm, Néel-type cores are present, while at t ≈ 33 nm, walls with crosstie cores are observed. At t > 60 nm, Bloch-type cores are observed. Along with the visualization of these critical parameters, the dependence on the film thickness of the characteristic angle and length of the segments of the zigzagged walls has been observed and analyzed. After measuring the bistable magneto-optical behavior, the values of the wall nucleation magnetic field and the surface roughness of the films, an energetic fit to these nucleation values is presented.

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31

Huang, Chengyu, Wenhua Wang, and Weizhong Li. "A Novel 2D Model for Freezing Phase Change Simulation during Cryogenic Fracturing Considering Nucleation Characteristics." Applied Sciences 10, no. 9 (May 9, 2020): 3308. http://dx.doi.org/10.3390/app10093308.

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A 2D computational fluid dynamics (CFD) model in consideration of nucleation characteristics (homogeneous/heterogeneous nucleation) using the volume of fluid (VOF) method and Lee model was proposed. The model was used to predict the process of a multiphase flow accompanied by freezing phase change during cryogenic fracturing. In this model, nucleation characteristic (homogeneous and heterogeneous nucleation) during the freezing process and the influence of the formed ice phase on the flowing behavior was considered. Validation of the model was done by comparing its simulation results to Neumann solutions for classical Stefan problem. The comparison results show that the numerical results are well consistent with the theoretical solution. The maximum relative differences are less than 7%. The process of multiphase flow accompanied by the freezing of water was then simulated with the proposed model. Furthermore, the transient formation and growth of ice as well as the evolution of temperature distribution in the computational domain was studied. Results show that the proposed method can better consider the difference between homogeneous nucleation in the fluid domain and heterogeneous nucleation on the wall boundary. Finally, the main influence factors such as the flow velocity and initial distribution of ice phase on the fracturing process were discussed. It indicates that the method enable to simulate the growth of ice on the wall and its effect on the flow of multiphase fluid.

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32

Wittig, J. E. "Magnetic domain wall movement in iron silicon." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 1044–45. http://dx.doi.org/10.1017/s0424820100151052.

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Lorentz microscopy in the transmission electron microscope directly images magnetic domains. By changing the magnetic field of the electromagnetic lenses relative to the specimen plane, the movement of the magnetic domain walls and their interaction with microstructural features can be observed in situ. This type of experiment has successfully analyzed the microstructure-domain wall interactions in spinel ferrites and iron-rare-earth-boron magnetic materials. The domain wall motion reveals the qualitative pinning potential of grain boundaries, precipitates, inclusions, stacking faults, and cracks. In addition, these in situ experiments display the dynamics of magnetic domain nucleation. The current study investigates the magnetic domain wall movement in iron silicon alloys. Since magnetic properties such as intrinsic coercivity and permeability are structure sensitive, the influence of microstructure on domain wall movement dictates the soft magnetic behavior.Thin foils of iron-6.5 wt% silicon were prepared by electropolishing ribbons produced by melt spinning techniques. The magnetic domain walls were imaged in the defocused (Fresnel) mode with a Philips CM20T operated at 200 kV.

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33

Young, L. H., D. R. Benson, F. R. Kameel, J. R. Pierce, H. Junninen, M. Kulmala, and S. H. Lee. "Laboratory studies of H<sub>2</sub>SO<sub>4</sub>/H<sub>2</sub>O binary homogeneous nucleation from the SO<sub>2</sub>+OH reaction: evaluation of the experimental setup and preliminary results." Atmospheric Chemistry and Physics 8, no. 16 (August 28, 2008): 4997–5016. http://dx.doi.org/10.5194/acp-8-4997-2008.

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Abstract. Binary homogeneous nucleation (BHN) of sulphuric acid and water (H2SO4/H2O) is one of the most important atmospheric nucleation processes, but laboratory observations of this nucleation process are very limited and there are also large discrepancies between different laboratory studies. The difficulties associated with these experiments include wall loss of H2SO4 and uncertainties in estimation of H2SO4 concentration ([H2SO4]) involved in nucleation. We have developed a new laboratory nucleation setup to study H2SO4/H2O BHN kinetics and provide relatively constrained [H2SO4] needed for nucleation. H2SO4 is produced from the SO2+OH→HSO3 reaction and OH radicals are produced from water vapor UV absorption. The residual [H2SO4] were measured at the end of the nucleation reactor with a chemical ionization mass spectrometer (CIMS). Wall loss factors (WLFs) of H2SO4 were estimated by assuming that wall loss is diffusion limited and these calculated WLFs were in good agreement with simultaneous measurements of the initial and residual [H2SO4] with two CIMSs. The nucleation zone was estimated from numerical simulations based on the measured aerosol sizes (particle diameter, Dp) and [H2SO4]. The measured BHN rates (J) ranged from 0.01–220 cm−3 s−1 at the initial and residual [H2SO4] from 108−1010 cm−3, a temperature of 288 K and relative humidity (RH) from 11–23%; J increased with increasing [H2SO4] and RH. J also showed a power dependence on [H2SO4] with the exponential power of 3–8. These power dependences are consistent with other laboratory studies under similar [H2SO4] and RH, but different from atmospheric field observations which showed that particle number concentrations are often linearly dependent on [H2SO4]. These results, together with a higher [H2SO4] threshold (108–109 cm−3) needed to produce the unit J measured from the laboratory studies compared to the atmospheric conditions (106–107 cm−3), imply that H2SO4/H2O BHN alone is insufficient to explain atmospheric aerosol formation and growth. Particle growth rates estimated from the measured aerosol size distributions, residence times (tr), and [H2SO4] were 100–500 nm h−1, much higher than those seen from atmospheric field observations, because of the higher [H2SO4] used in our study.

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34

Nanev, Christo, Lata Govada, and Naomi E. Chayen. "Theoretical and experimental investigation of protein crystal nucleation in pores and crevices." IUCrJ 8, no. 2 (February 11, 2021): 270–80. http://dx.doi.org/10.1107/s2052252521000269.

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The nucleation ability of pores is explained using the equilibration between the cohesive energy maintaining the integrity of a crystalline cluster and the destructive energy tending to tear it up. It is shown that to get 3D crystals it is vital to have 2D crystals nucleating in the pores first. By filling the pore orifice, the 2D crystal nuclei are more stable because their peripheries are protected from the destructive action of water molecules. Furthermore, the periphery of the 2D crystal is additionally stabilized as a result of its cohesion with the pore wall. The understanding provided by this study combining theory and experiment will facilitate the design of new nucleants.

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35

ZHAO, G. P., CHUN YANG, C. W. XIAN, and Y. P. FENG. "ANALYTICAL DETERMINATION OF NUCLEATION FIELD AND MAGNETIC REVERSAL MODES IN EXCHANGE-COUPLED NANOLAYERS." Modern Physics Letters B 23, no. 25 (October 10, 2009): 2955–61. http://dx.doi.org/10.1142/s0217984909021119.

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General formulae for coherent/incoherent nucleation fields have been obtained as functions of the thickness of the hard and soft layers within a self-contained micromagnetic model for a hard/soft trilayer. The nucleation modes are determined reliably by direct comparison of the nucleation fields for different modes. It is shown that coherent nucleation cannot take place no matter how small the layer thickness. For small soft layer thickness, the magnetic reversal mode is an incoherent nucleation. As the soft layer thickness increases, the dominant magnetic reversal process is domain-wall motion/pinning. Analyses demonstrate that negative nucleation field and very small coercivity occur when the easy axes of neighboring layers are perpendicular. The results could shade light on Brown's coercivity paradox (where the measured coercivity is much smaller than the one given by the previous theories).

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36

Yeoh, Guan Heng, and Xiaobin Zhang. "Computational fluid dynamics and population balance modelling of nucleate boiling of cryogenic liquids: Theoretical developments." Journal of Computational Multiphase Flows 8, no. 4 (November 22, 2016): 178–200. http://dx.doi.org/10.1177/1757482x16674217.

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The main focus in the analysis of pool or flow boiling in saturated or subcooled conditions is the basic understanding of the phase change process through the heat transfer and wall heat flux partitioning at the heated wall and the two-phase bubble behaviours in the bulk liquid as they migrate away from the heated wall. This paper reviews the work in this rapid developing area with special reference to modelling nucleate boiling of cryogenic liquids in the context of computational fluid dynamics and associated theoretical developments. The partitioning of the wall heat flux at the heated wall into three components – single-phase convection, transient conduction and evaporation – remains the most popular mechanistic approach in predicting the heat transfer process during boiling. Nevertheless, the respective wall heat flux components generally require the determination of the active nucleation site density, bubble departure diameter and nucleation frequency, which are crucial to the proper prediction of the heat transfer process. Numerous empirical correlations presented in this paper have been developed to ascertain these three important parameters with some degree of success. Albeit the simplicity of empirical correlations, they remain applicable to only a narrow range of flow conditions. In order to extend the wall heat flux partitioning approach to a wider range of flow conditions, the fractal model proposed for the active nucleation site density, force balance model for bubble departing from the cavity and bubble lifting off from the heated wall and evaluation of nucleation frequency based on fundamental theory depict the many enhancements that can improve the mechanistic model predictions. The macroscopic consideration of the two-phase boiling in the bulk liquid via the two-fluid model represents the most effective continuum approach in predicting the volume fraction and velocity distributions of each phase. Nevertheless, the interfacial mass, momentum and energy exchange terms that appear in the transport equations generally require the determination of the Sauter mean diameter or interfacial area concentration, which strongly governs the fluid flow and heat transfer in the bulk liquid. In order to accommodate the dynamically changing bubble sizes that are prevalent in the bulk liquid, the mechanistic approach based on the population balance model allows the appropriate prediction of local distributions of Sauter mean diameter or interfacial area concentration, which in turn can improve the predictions of the interfacial mass, momentum and energy exchanges that occur across the interface between the phases. Need for further developments are discussed.

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37

Hartmann, U. "Nucleation-field distribution of the Bloch-wall polarization reversal process." Physical Review B 36, no. 7 (September 1, 1987): 3693–96. http://dx.doi.org/10.1103/physrevb.36.3693.

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38

Wette, Patrick, Andreas Engelbrecht, Roushdey Salh, Ina Klassen, Dirk Menke, Dieter M. Herlach, Stephan V. Roth, and Hans Joachim Schöpe. "Competition between heterogeneous and homogeneous nucleation near a flat wall." Journal of Physics: Condensed Matter 21, no. 46 (October 27, 2009): 464115. http://dx.doi.org/10.1088/0953-8984/21/46/464115.

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39

Ingle, S. G., H. S. Dutta, and A. P. David. "Domain wall nucleation by impurity ions in KNbO3 single crystals." Journal of Applied Physics 64, no. 9 (November 1988): 4640–45. http://dx.doi.org/10.1063/1.342482.

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40

Rio, F., P. Bernstein, and M. Labrune. "Magnetization process in RE-TM alloys: Wall mobility and nucleation." IEEE Transactions on Magnetics 23, no. 5 (September 1987): 2266–68. http://dx.doi.org/10.1109/tmag.1987.1065648.

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41

Narayanapillai, Kulothungasagaran, Xuepeng Qiu, Jan Rhensius, and Hyunsoo Yang. "Thermally assisted domain wall nucleation in perpendicular anisotropy trilayer nanowires." Journal of Physics D: Applied Physics 47, no. 10 (February 19, 2014): 105005. http://dx.doi.org/10.1088/0022-3727/47/10/105005.

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42

Kaiser, W., M. Kiechle, G. Žiemys, D. Schmitt-Landsiedel, and S. Breitkreutz-v. Gamm. "Micromagnetic simulation of nanomagnets with geometry-tuned domain wall nucleation." Journal of Physics: Conference Series 903 (October 2017): 012052. http://dx.doi.org/10.1088/1742-6596/903/1/012052.

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43

Hickey, M. C., D. Atkinson, C. H. Marrows, and B. J. Hickey. "Controlled domain wall nucleation and resulting magnetoresistance in Ni81Fe19 nanoconstrictions." Journal of Applied Physics 103, no. 7 (April 2008): 07D518. http://dx.doi.org/10.1063/1.2834713.

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44

Adair, W. S., S. A. Steinmetz, D. M. Mattson, U. W. Goodenough, and J. E. Heuser. "Nucleated assembly of Chlamydomonas and Volvox cell walls." Journal of Cell Biology 105, no. 5 (November 1, 1987): 2373–82. http://dx.doi.org/10.1083/jcb.105.5.2373.

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The Chlamydomonas reinhardtii cell wall is made up of hydroxyproline-rich glycoproteins, arranged in five distinct layers. The W6 (crystalline) layer contains three major glycoproteins (GP1, GP2, GP3), selectively extractable with chaotropic agents, that self-assemble into crystals in vitro. A system to study W6 assembly in a quantitative fashion was developed that employs perchlorate-extracted Chlamydomonas cells as nucleating agents. Wall reconstitution by biotinylated W6 monomers was monitored by FITC-streptavidin fluorescence and quick-freeze/deep-etch electron microscopy. Optimal reconstitution was obtained at monomer concentrations (0.2-0.3 mg/ml) well below those required for nonnucleated assembly. Assembly occurred from multiple nucleation sites, and faithfully reflected the structure of the intact W6 layer. Specificity of nucleated assembly was demonstrated using two cell-wall mutants (cw-2 and cw-15); neither served as a substrate for assembly of wild-type monomers. In addition, W6 sublayers were assembled from purified components: GP2 and GP3 coassembled to form the inner (W6A) sublayer; this then served as a substrate for self-assembly of GP1 into the outer (W6B) sublayer. Finally, evolutionary relationships between C. reinhardtii and two additional members of the Volvocales (Chlamydomonas eugametos and Volvox carteri) were explored by performing interspecific reconstitutions. Hybrid walls were obtained between C. reinhardtii and Volvox but not with C. eugametos, confirming taxonomic assignments based on structural criteria.

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45

Shishkina, E. V., M. A. Chuvakova, V. V. Yuzhakov, A. R. Akhmatkhanov, E. V. Pelegova, M. S. Nebogatikov, A. D. Ushakov, E. A. Linker, L. I. Ivleva, and V. Ya Shur. "Domain structure evolution during polarization reversal in calcium orthovanadate single crystals." Journal of Applied Physics 132, no. 18 (November 14, 2022): 184101. http://dx.doi.org/10.1063/5.0120792.

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We have switched polarization in calcium orthovanadate single crystal with as-grown domain structure consisting of isolated domains with charged domain walls (CDWs) located in the bulk using pretreatment by ac field and subsequent switching in dc field at the elevated temperature. The formation of the domain ledges at the CDW in the bulk and their growth in the polar direction has been revealed. The isolated domains with optically well-defined walls appeared when the ledge tops reached the surface, their shape and sizes remaining constant during further switching. Unlike usual continuous domain wall motion, we have observed the discrete switching by arising of the isolated domains without any input of the traditional domain nucleation at the polar surface. The obtained results have been explained under the assumption that at the used experimental conditions, the applied field is above the threshold value for ledge nucleation at CDW in the bulk, but below the threshold for domain wall motion at the surface. Thus, we have obtained the discrete switching by ledge growth without any sideways motion of the domain walls and domain coalescence. The nonuniform evolution of the domain structure at the surface is due to the dependence of the switching rate on the distance from CDW to the polar surface, which is random in the studied domain structure.

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46

Raposo, Víctor, and Eduardo Martínez. "All optical writing and current-driven shifting of bits in ferrimagnetic strips: A micromagnetic study." AIP Advances 13, no. 1 (January 1, 2023): 015120. http://dx.doi.org/10.1063/9.0000516.

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Nucleation of domains and domain walls by means of ultrashort laser pulses, and their current-driven shifting along a ferrimagnetic strip with high perpendicular magnetic anisotropy on top of a heavy metal, are both explored here by means of advanced micromagnetic modeling. Our results indicate that these systems are ideal candidates to develop high-density and high-efficient domain wall-based memory devices where the information is coded in series of bits in the form of perpendicular up and down domains flanked by chiral domain walls.

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47

Espinoza-Martínez, Adriana, Carlos Avila-Orta, Víctor Cruz-Delgado, Oscar Olvera-Neria, Julio González-Torres, and Francisco Medellín-Rodríguez. "Nucleation Mechanisms of Aromatic Polyesters, PET, PBT, and PEN, on Single-Wall Carbon Nanotubes: Early Nucleation Stages." Journal of Nanomaterials 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/189820.

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Nucleation mechanisms of poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and poly(ethylene naphthalate) (PEN) on single-wall carbon nanotubes (SWNTs) are proposed, based on experimental evidence, theoretical epitaxy analysis, and semiempirical quantum chemical calculations. In order to elucidate early nucleation stages polyester-coated nanotubes were obtained from highly diluted solutions. High-resolution transmission electron microscopy (HRTEM) revealed helical morphologies for PET/SWNTs and PEN/SWNTs and the formation of lobules with different orientations for PBT/SWNTs. To explain the morphological behavior one model was proposed based on crystallographic interactions, that is, epitaxy. Theoretical epitaxy calculations indicated that epitaxy is not possible from the strict epitaxy point of view. Instead, aromatic self-assembly mechanism was proposed based onπ-πinteractions and the chirality of the nanotube. It was proposed that the mechanism implies two steps to produce helical or lobular morphologies with different orientations. In the first step polymer chains were approached, aligned parallel to the nanotube axis and adsorbed due to electrostatic interactions and the flexibility of the molecule. However, due toπ-πinteractions between the aromatic rings of the polymer and the nanotube, in the second step chains reoriented on the nanotube surface depending on the chirality of the nanotube. The mechanism was supported by semi-empirical calculations.

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48

Najim, Abdul, and Anil R. Aacharya. "Experimental Study of Effect of Nucleation Site Size on Bubble Dynamics during Nucleate Pool Boiling Heat Transfer." Applied Mechanics and Materials 592-594 (July 2014): 1596–600. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1596.

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In this paper, effect of nucleation site size on bubble dynamics during nucleate pool boiling heat transfer in saturated water is studied experimentally. Single bubble was generated using right angle tip of a hypodermic needle as a nucleation site. The hypodermic needles were used of inner diameters 0.413mm, 0.514mm, and 0.603 mm with a constant depth of 25mm. The bubble dynamics was studied using SONY Cyber-shot DSC-H100 camera operating at 30 frames per second at atmospheric pressure and at a wall superheat of 5K. The results show that, bubble diameter, bubble height and bubble volume increases with increase in diameter of nucleation site. The bubble growth period is found to be dependent on nucleation site size, and it decreases with increase in diameter of nucleation site. This happens because as volume of vapor bubble increases, buoyancy force starts dominates the capillary force and bubble detaches earlier. Effect of nucleation site size on bubble departure diameter and bubble release frequency is also discussed.

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49

Wang, Zijun, Xingqiao Ma, Houbing Huang, Hongwen Xiao, and Tianfu Li. "Micromagnetic Simulation of Domain Walls in Exchange Spring Trilayers." Advances in Condensed Matter Physics 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/301063.

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Chiral domain wall structures in ferromagnetic exchange spring soft/hard/soft and hard/soft/hard trilayers were investigated with micromagnetic simulation, which enables us to fully characterize the nucleation and growth of buried domain walls in layered ferromagnetic thin films. Simulated results show that the trilayers are both exchange coupled and presenting chiral spin structures. Detailed features of field-dependent domain walls evolution in the spring magnets are also revealed. In process of remagnetization, the spin structure of soft/hard/soft is energetically more stable than that of hard/soft/hard.

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50

Yamazaki, Tomoya, Yuki Kimura, Peter G. Vekilov, Erika Furukawa, Manabu Shirai, Hiroaki Matsumoto, Alexander E. S. Van Driessche, and Katsuo Tsukamoto. "Two types of amorphous protein particles facilitate crystal nucleation." Proceedings of the National Academy of Sciences 114, no. 9 (February 13, 2017): 2154–59. http://dx.doi.org/10.1073/pnas.1606948114.

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Nucleation, the primary step in crystallization, dictates the number of crystals, the distribution of their sizes, the polymorph selection, and other crucial properties of the crystal population. We used time-resolved liquid-cell transmission electron microscopy (TEM) to perform an in situ examination of the nucleation of lysozyme crystals. Our TEM images revealed that mesoscopic clusters, which are similar to those previously assumed to consist of a dense liquid and serve as nucleation precursors, are actually amorphous solid particles (ASPs) and act only as heterogeneous nucleation sites. Crystalline phases never form inside them. We demonstrate that a crystal appears within a noncrystalline particle assembling lysozyme on an ASP or a container wall, highlighting the role of heterogeneous nucleation. These findings represent a significant departure from the existing formulation of the two-step nucleation mechanism while reaffirming the role of noncrystalline particles. The insights gained may have significant implications in areas that rely on the production of protein crystals, such as structural biology, pharmacy, and biophysics, and for the fundamental understanding of crystallization mechanisms.

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