Increase In Domain Size Research Articles

On the sensitivity of hurricane storm surge simulation to domain size

The impact of model domain size on the simulated storm surge under various hurricane and topographic conditions is investigated by using a three-dimensional storm surge model. Idealized experiments are designed to simulate storm surge with different domain sizes under various hurricane intensities, radius of maximum wind (RMW), translation speeds and landfall directions, coastal ocean bottom slopes, and continental shelf extents. The results show that, in general, the simulated storm surge first increases with increasing domain size and then approaches a constant value. A “threshold domain size” is defined accordingly, so that differences among model results with different domain sizes larger than the threshold domain size are negligible. The threshold domain size is shown to be insensitive to hurricane intensities, but increases linearly with increasing hurricane RMWs. It also increases with increasing translation speeds and decreasing bottom slopes, when hurricanes approach land perpendicularly. The threshold domain size can also be affected by other factors such as the direction of the storm track of a landfalling hurricane and the extent of continental shelf. Considering the complex dependence of the threshold domain size on various hurricane parameters, a polar graphic chart is created for estimating the threshold domain size for possible hurricane landfall directions and RMWs. A real case study of hurricane Charley (2004) is conducted with different domain sizes. Model results indicate that the threshold domain size estimated from the idealized experiments is reasonable for practical applications.

Steep Increase in Myonuclear Domain Size During Infancy

AbstractWe investigated whether myonuclear number increases in proportion to the increase in fiber size during maturational growth of skeletal muscle. Thoraco‐abdominal muscle tissue was obtained from twenty 6‐day to 15‐year‐old boys and girls during cardiothoracic surgery. Cross‐sections were stained by anti‐laminin for the basal lamina and by DAPI to identify nuclei. Basal lamina was traced on digital images to measure the fiber cross‐sectional area (FCSA). Nuclei located within the basal lamina were considered myonuclei if pax7‐negative and satellite cell nuclei if pax7‐positive. Samples of two children were excluded from analysis because of clear signs of hypoxia as shown by positive carbonic anhydrase IX staining. Linear regression showed that FCSA increased with age by 187 μm2·per annum (R2 = 0.90; P < 0.001). Satellite cell density showed a dramatic decrease in the first months of life, but this was not accompanied by an increase in myonuclei per muscle fiber cross‐section. Till four years of age the number of myonuclei per muscle fiber cross‐section remained relatively constant but increased thereafter. Myonuclear domain size showed a steep increase during infancy and reached adult values in the young adolescent phase. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.

Phase behavior and domain size in sphingomyelin-containing lipid bilayers

Membrane raft size measurements are crucial to understanding the stability and functionality of rafts in cells. The challenge of accurately measuring raft size is evidenced by the disparate reports of domain sizes, which range from nanometers to microns for the ternary model membrane system sphingomyelin (SM)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/cholesterol (Chol). Using Förster resonance energy transfer (FRET) and differential scanning calorimetry (DSC), we established phase diagrams for porcine brain SM (bSM)/dioleoyl-sn-glycero-3-phosphocholine (DOPC)/Chol and bSM/POPC/Chol at 15 and 25°C. By combining two techniques with different spatial sensitivities, namely FRET and small-angle neutron scattering (SANS), we have significantly narrowed the uncertainty in domain size estimates for bSM/POPC/Chol mixtures. Compositional trends in FRET data revealed coexisting domains at 15 and 25°C for both mixtures, while SANS measurements detected no domain formation for bSM/POPC/Chol. Together these results indicate that liquid domains in bSM/POPC/Chol are between 2 and 7nm in radius at 25°C: that is, domains must be on the order of the 2–6nm Förster distance of the FRET probes, but smaller than the ~7nm minimum cluster size detectable with SANS. However, for palmitoyl SM (PSM)/POPC/Chol at a similar composition, SANS detected coexisting liquid domains. This increase in domain size upon replacing the natural SM component (which consists of a mixture of chain lengths) with synthetic PSM, suggests a role for SM chain length in modulating raft size in vivo.

Correlation of polymeric compatibilizer structure to its impact on the morphology and function of P3HT:PCBM bulk heterojunctions

The impact of various polymeric compatibilizers, including end-functionalized P3HTs and diblock copolymers containing P3HT, on the structure and function of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunctions is presented. Careful analyses of small angle neutron scattering curves provide a measure of the miscibility of PCBM in P3HT, the average PCBM domain size, and the interfacial area between PCBM and the P3HT-rich phase in the uncompatibilized and compatibilized systems. Differential scanning calorimetry (DSC) also provides information regarding the changes in the crystallinity of P3HT due to the presence of the compatibilizer. Results show that most compatibilizers cause the domain sizes to decrease and the P3HT crystallinity to increase; however, some cause an increase in domain size, suggesting that they are not effective interfacial modifiers. The correlation of morphology with photovoltaic activity shows that the decreased domain size, increased crystallinity and increased interfacial area do not always result in improved power conversion efficiency (PCE). It appears that the introduction of an insulating molecule at the PCBM:P3HT interface as a compatibilizer results in a decrease in PCE. Thus, the presence of the compatibilizer at this interface dominates the photovoltaic activity, rather than the morphological control.

High modulus and low-voltage driving nematic liquid-crystalline physical gels for light-scattering displays

Liquid-crystalline (LC) physical gels with a high modulus and low driving voltage were prepared through the self-assembly of sorbitol derivatives as gelators in a nematic liquid crystal, 4-pentyl-4′-cyanobiphenyl (5CB). The structural difference among the used gelators, i.e. 1,3:2,4-di-O-benzylidene-D-sorbitol (DBS), 1,3:2,4-di-O-p-methylbenzylidene-D-sorbitol (MDBS) and 1,3:2,4-di-O-m,p-dimethylbenzylidene-D-sorbitol (DMDBS), is only the number of methyl groups on their phenyl rings. The phase transition temperature, mechanical and electro-optical properties of three LC gels were systematically investigated. Compared with DBS, MDBS and DMDBS with methyl groups on phenyl rings have higher gelation ability in 5CB. The three LC gels exhibit good self-supporting ability with storage moduli higher than 104 Pa when the gelator content is increased to 1.5 wt%. At 3.0 wt% and a gelator content less than 1.0 wt%, both moduli of MDBS and DMDBS gels are obviously higher than that of DBS gel due to the enhanced reinforcement of the more rigid, thicker nano-fibrils and the formed nano-fibrillar network texture in MDBS and DMDBS gels. Also, the driving voltages of LC gels decrease in the order of DBS, MDBS and DMDBS gels with increase of LC domain size and nano-fibril diameter. For DMDBS gel with 3.0 wt% gelators, the threshold voltage and saturation voltage are only 0.5 and 3.5 V μm−1, showing its potential application in self-supporting light-scattering electro-optical displays.

Steep Increase in Myonuclear Domain Size During Infancy

We investigated whether myonuclear number increases in proportion to the increase in fiber size during maturational growth of skeletal muscle. Thoraco-abdominal muscle tissue was obtained from twenty 6-day to 15-year-old boys and girls during cardiothoracic surgery. Cross-sections were stained by anti-laminin for the basal lamina and by DAPI to identify nuclei. Basal lamina was traced on digital images to measure the fiber cross-sectional area (FCSA). Nuclei located within the basal lamina were considered myonuclei if pax7-negative and satellite cell nuclei if pax7-positive. Samples of two children were excluded from analysis because of clear signs of hypoxia as shown by positive carbonic anhydrase IX staining. Linear regression showed that FCSA increased with age by 187 μm(2) ·per annum (R(2) = 0.90; P < 0.001). Satellite cell density showed a dramatic decrease in the first months of life, but this was not accompanied by an increase in myonuclei per muscle fiber cross-section. Till four years of age the number of myonuclei per muscle fiber cross-section remained relatively constant but increased thereafter. Myonuclear domain size showed a steep increase during infancy and reached adult values in the young adolescent phase.

Influence of gas composition on the formation of graphene domain synthesized from camphor

The domain structure of graphene films deposited by the chemical vapor deposition (CVD) process has a great influence on the electrical and physical properties. Here, we tackled the synthesis of increased domain size of single layer and bi-layer graphene along with few-layer graphene on Ni foil using solid camphor as a carbon source. To achieve this, effect of the composition of carrier gas for the evaporated camphor was investigated. Raman mapping and peak width (FWHM) analyses gave the insight of the quality and number of graphene layers. Optical and scanning electron microcopy studies show significance difference in domain structure of the synthesized graphene in different gas atmosphere. As confirmed by optical and scanning electron microscopes, the graphene domain grown with the carrier gas of Ar/H2 mixture was more than 10 times larger than those grown with pure Ar carrier gas.

Coastal numerical modelling of tides: Sensitivity to domain size and remotely generated internal tide

The propagation of remotely generated superinertial internal tides constitutes a difficulty for the modelling of regional ocean tidal variability which we illustrate in several ways.First, the M2 tidal solution inside a control region located along the Southern California Bight coastline is monitored while the extent of the numerical domain is increased (up to 512×512km). While the amplitude and phase of sea level averaged over the region is quasi-insensitive to domain size, a steady increase of kinetic energy, predominantly baroclinic, is observed with increasing domain size. The increasing flux of energy into the control region suggests that this trend is explained by the growing contribution from remote generation sites of internal tide which can propagate up to the control region.Increasing viscosities confirms this interpretation by lowering baroclinic energy levels and limiting their rate of increase with domain size. Doubling the grid spacing allows consideration of numerical domains 2 times larger. While the coarse grid has lower energy levels than the finer grid, the rate of energy increase with domain size appears to be slowing for the largest domain of the coarse grid simulations.Forcing the smallest domain with depth-varying tidal boundary conditions from the simulation in the largest domain produces energy levels inside the control region comparable to those in the control region for the largest domain, thereby confirming the feasibility of a nested approach.In contrast, simulations forced with a subinertial tidal constituent (K1) show that when the propagation of internal tide is limited, the control region kinetic energy is mostly barotropic and the magnitudes of variations of the kinetic energy with domain size are reduced.

Imaging the Magnetization Processes in Epitaxial Exchange Coupled SmCo$_{5}$/Fe/SmCo$_{5}$ Trilayers

A detailed understanding of the magnetization processes in an exchange coupled SmCo5/Fe/SmCo5 trilayer is derived from imaging the domain configuration of the sample in a succession of remanent states by magnetic force microscopy. Domain nucleation and domain wall movement processes are identified and are interpreted in terms of the dominating coercivity mechanism. As in single hard magnetic SmCo5 layers, strong pinning of domain walls governs the magnetization reversal and determines coercivity. The coupling to the Fe layer, however, leads to an increased domain size in the thermally demagnetized state and to a larger nucleation density prior to the irreversible magnetization switching. Due to slightly different switching fields of the two SmCo5 layers, a compensated state can be adjusted, in which the moments of the Fe layer form 180° spin spirals with laterally varying chirality. The magnetic contrast arising from these spin spirals is imaged and the irreversible changes in a small in-plane field perpendicular to the easy axis are studied.

Weakly Forced Mock Walker Cells

Abstract Mock Walker cells driven by weak sea surface temperature (SST) forcing are studied using planetary-scale cloud system–resolving simulations and a simplified framework that represents convection with its linear response functions and parameterizes the large-scale flow based on the gravity wave equation. For sinusoidal SST forcings of the same amplitude, as the horizontal domain size increases, the mock Walker cells strengthen substantially and shorter vertical scales in the vertical velocity profile diminish. This is explained by the fact that temperature anomalies required to sustain a vertical velocity profile of given amplitude are stronger in cases of larger horizontal and smaller vertical scales. Such temperature anomalies become significant at planetary scales so that properly accounting for the horizontal momentum balance, including convective momentum transport (CMT), becomes necessary, while a weak temperature gradient approach that neglects horizontal momentum balance is no longer adequate. The downward advection component of the CMT in particular is important for capturing a number of features of the mock Walker cells. The extent of convective organization also affects the mock Walker cell through its effects on the sensitivities of convective heating and moistening to temperature and moisture anomalies. For strongly organized convection with deep inflows, these sensitivities are consistent with a layer mode of convective overturning, instead of the parcel mode as in unorganized convection, resulting in a weaker second baroclinic component in the mock Walker cells.

First principles study on the boron–nitrogen domains segregated within (5, 5) and (8, 0) single-wall carbon nanotubes: Formation energy, electronic structure and reactivity

The geometries, formation, cohesive energies, electronic properties and reactivity of pristine and boron–nitrogen (BN) co-doped (5,5) and (8,0) single-wall carbon nanotubes (SWNTs) are investigated using density functional calculations. There is a strong tendency for the formation of segregated BN domains within SWNTs and the formation and cohesive energy values increase with increase in number of BN domains, the values intermediate between pristine SWNT and BNNT. Moreover, BN co-doped SWNTs with B excess or N excess impurity exhibits the characteristics of a donor or acceptor as the electronic states are influenced by number of occupied states in the valence and conduction bands. Inclusion of BN domains in (5,5) SWNT exhibits a metallic to semiconductor transition, whereas for (8,0) SWNT, further opening of the band gap is observed with increase in BN domain size. The wavefunction plots at the Γ point show the localization of electronic states around BN domain region.

Phase morphology evolution upon melt annealing treatment and corresponding mechanical performance of impact-resistant polypropylene copolymer

The evolution of phase morphology upon melt annealing and the corresponding changes in mechanical properties of impact-resistant polypropylene copolymers (IPCs) have been systematically investigated. A distinct coarsening process is observed during melt annealing and the statistical analysis of stereology reveals that the increase of dispersed domain size well follows the Ostwald ripening mechanism. Mechanical tests suggest that the notched impact strength and elongation at break decrease gradually with increasing annealing time, while the tensile strength remains relatively constant. The decrease of toughness is consistent with the size increase of dispersed domains, which may result from the development of late-stage phase separation of IPC. However, the tensile strength, which is mainly dominated by the crystalline phase structure, remains relatively constant during the annealing treatment. On the basis of these results, the probable relationship between the change of mechanical properties and phase morphology evolution has been proposed.

Surface Layer Characteristics of S30432 Austenite Stainless Steel after Shot Peening

Three types of shot peening treatments were applied to S30432 stainless steel. The effect of shot peening intensity and shot peening method on the residual stress and microstructure has been investigated. The domain size and micro-strain evolutions in near surface layer were characterized systematically via Voigt method. The results reveal that shot peening could induce compressive residual stress in the deformed layer for all shot peening conditions. As the shot peening step and intensity increase, the compressive residual stresses increase in near surface layer, and decease faster in deeper deformed layer. In the deformed layer, the domain size increases, while the micro-strain decreases with the depth increasing. Comparing with the micro-hardness after shot peening, it is concluded that increasing the shot peening step is a considerable way to improve the shot peening effect. [doi:10.2320/matertrans.M2011390]

Thermodynamic and Structural Changes in Ion-Containing Symmetric Diblock Copolymers: A Small-Angle X-ray Scattering Study

We present temperature-dependent SAXS measurements on symmetric poly(styrene-block-2-vinylpyridine) and poly(styrene-block-ethylene oxide) with added lithium triflate. Salt doping led to a strong increase of the order–disorder transition temperatures and increased domain spacings. Based on a detailed analysis of the scattering data close to the order–disorder transition, three contributions to the structural changes can be distinguished: an increased incompatibility between the different monomers, the additional volume of the added salt, and chain stretching due to coordination between polymer and salt. At the phase transition, i.e. at constant interaction parameter χ, for low concentrations the increase in domain size is quantitatively explained by the volume of the added salt, and at higher concentrations chain stretching sets in. Structural and thermodynamic effects are considerably stronger in PEO than in P2VP.

Surface Characterization and Protein Interactions of Segmented Polyisobutylene-Based Thermoplastic Polyurethanes

The surface properties and biocompatibility of a class of thermoplastic polyurethanes (TPUs) with applications in blood-contacting medical devices have been studied. Thin films of commercial TPUs and novel polyisobutylene (PIB)-poly(tetramethylene oxide) (PTMO) TPUs were characterized by contact angle measurements, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM) imaging. PIB-PTMO TPU surfaces have significantly higher C/N ratios and lower amounts of oxygen than the theoretical bulk composition, which is attributed to surface enrichment of PIB. Greater differences in the C/N ratios were observed with the softer compositions due to their higher relative amounts of PIB. The contact angles were higher on PIB-PTMO TPUs than on commercial polyether TPUs, indicating lower surface energy. AFM imaging showed phase separation and increasing domain sizes with increasing hard segment content. The biocompatibility was investigated by quantifying the adsorption of fouling and passivating proteins, fibrinogen (Fg) and human serum albumin (HSA) respectively, onto thin TPU films spin coated onto the electrode of a quartz crystal microbalance with dissipation monitoring (QCM-D). Competitive adsorption experiments were performed with a mixture of Fg and albumin in physiological ratio followed by binding of GPIIb-IIIa, the platelet receptor ligand that selectively binds to Fg. The QCM-D results indicate similar adsorbed amounts of both Fg and HSA on PIB-PTMO TPUs and commercial TPUs. The strength of the protein interactions with the various TPU surfaces measured with AFM (colloidal probe) was similar among the various TPUs. These results suggest excellent biocompatibility of these novel PIB-PTMO TPUs, similar to that of polyether TPUs.

Magnetohydrodynamic convectons

AbstractNumerical continuation is used to compute branches of spatially localized structures in convection in an imposed vertical magnetic field. In periodic domains with finite spatial period, these branches exhibit slanted snaking and consist of localized states of even and odd parity. The properties of these states are analysed and related to existing asymptotic approaches valid either at small amplitude (Cox and Matthews, Physica D, vol. 149, 2001, p. 210), or in the limit of small magnetic diffusivity (Dawes, J. Fluid Mech., vol. 570, 2007, p. 385). The transition to standard snaking with increasing domain size is explored.

Measurement of Lipid Nanodomain (Raft) Formation and Size in Sphingomyelin/POPC/Cholesterol Vesicles Shows TX-100 and Transmembrane Helices Increase Domain Size by Coalescing Preexisting Nanodomains But Do Not Induce Domain Formation

Mixtures of unsaturated lipids, sphingolipids, and cholesterol form coexisting liquid-disordered and sphingolipid and cholesterol-rich liquid-ordered (Lo) phases in water. The detergent Triton X-100 does not readily solubilize Lo domains, but does solubilize liquid-disordered domains, and is commonly used to prepare detergent-resistant membranes from cells and model membranes. However, it has been proposed that in membranes with mixtures of sphingomyelin (SM), 1-palmitoyl 2-oleoyl phosphatidylcholine (POPC), and cholesterol Triton X-100 may induce Lo domain formation, and therefore detergent-resistant membranes may not reflect the presence of preexisting domains. To examine this hypothesis, the effect of Triton on Lo domain formation was measured in SM/POPC/cholesterol vesicles. Nitroxide quenching methods that can detect ordered nanodomains with radii >12 Å showed that in the absence of Triton X-100 this mixture formed ordered state domains that melt with a midpoint (= Tmid) at ∼45°C. However, Tmid was lower when detected using various fluorescence resonance energy transfer (FRET) pairs. Furthermore, the Tmid value was Ro dependent, and decreased as Ro increased. Because FRET can only readily detect domains with radii >Ro, this result can be explained by domain radii that are close to Ro and decrease as temperature increases. An analysis of FRET and quenching data suggests that nanodomain radius gradually decreases from ≥150 Å to <40 Å as temperature increases from 10 to 45°C. Interestingly, the presence of Triton X-100 or a transmembrane-type peptide did not stabilize ordered state formation when detected by nitroxide quenching, i.e., did not increase Tmid. However, FRET-detected Tmid did increase in the presence of Triton X-100 or a transmembrane peptide, indicating that both increased domain size. Controls showed that the results could not be accounted for by probe-induced perturbations. Thus, SM/POPC/cholesterol, a mixture similar to that in the outer leaflet of plasma membranes, forms nanodomains at physiological temperatures, and TX-100 does not induce domain formation or increase the fraction of the bilayer in the ordered state, although it does increase domain size by coalescing preexisting domains.

Magnetic and structural properties of CoCrPt–SiO2-based graded media prepared by ion implantation

The magnetic and structural properties of graded media fabricated by ion implantation of nitrogen (14 N+), oxygen (16O+), and cobalt (59Co+) ions in the CoCrPt–SiO2 recording layer of prototype disk have been studied. Ion implantation of the species was controlled at the atomic scale to fabricate the graded media. Magnetometric measurements indicated that the coercivity was reduced with an increasing dose of the implanted species. The observation of an increase in magnetic domain size has been attributed to the reduction in magnetocrystalline anisotropy energy, which is desirable for achieving graded media. The study indicates that the magnetic properties can be tailored by the appropriate selection of the implantation dose and species.

Sublimation growth of thick freestanding 3C-SiC using CVD-templates on silicon as seeds

Cubic silicon carbide is a promising material for medium power electronics operating at high frequencies and for the subsequent growth of gallium nitride for more efficient light emitting diodes. We present a new approach to produce freestanding cubic silicon carbide (3C-SiC) with the ability to obtain good crystalline quality regarding increased domain size and reduced defect density. This would pave the way to achieve substrates of 3C-SiC so that the applications of cubic silicon carbide material having selectively (111) or (001) oriented surfaces can be explored. Our method is based on the combination of the chemical vapor deposition method and the fast sublimation growth process. Thin layers of cubic silicon carbide grown heteroepitaxially on silicon substrates are for the first time used for a subsequent sublimation growth step to increase layer thicknesses. We have been able to realize growth of freestanding (001) oriented 3C-SiC substrates using growth rates around 120 μm/h and diameters of more than 10 mm. The structural quality from XRD rocking curve measurements of (001) oriented layers shows good FWHM values down to 78 arcsec measured over an area of 1 × 2 mm 2, which is a quality improvement of 2–3 times compared with other methods like CVD.

Ion implantation induced modification of structural and magnetic properties of perpendicular media

This study reports the effects of implanting various doses of boron (11B+) and argon (40Ar+) ions into the recording layer and the soft underlayer of CoCrPt–SiO2-based perpendicular recording media. Implantation of a lower dose of boron ions (1011 ions cm−2) in the recording layer was found to reduce the out-of-plane coercivity, whereas no changes in the coercivity were observed when they were implanted into the soft underlayer. In the case of argon ions, lower dose implantation did not show any changes in the coercivity, irrespective of the implanted layer. However, higher dose implantations (1016 ions cm−2) of all the species were found to cause a reduction in coercivity, irrespective of the implanted layer. The reduction in coercivity was more significant when the ions were implanted in the recording layer compared with the case of implantation in the soft underlayer. X-ray diffraction (XRD) results on samples where argon was implanted in the recording layer showed a strong shift in the position of Co (0 0 .2) peaks, indicating an increase in the ‘c’ parameter. The shift is explained, on the basis of x-ray photoelectron spectroscopy, to be arising from intra-layer mixing at the CoCrPt–SiO2/Ru interface. Magnetic force microscopy images indicated an increase in domain size arising from the ion implantation.