Surface distortion of Fe dot-decorated TiO2 nanotubular templates using time-of-flight grazing incidence small angle scattering

Physical properties of nanoclusters, nanostructures and self-assembled nanodots, which in turn are concomitantly dependent upon the morphological properties, can be modulated for functional purposes. Here, in this article, magnetic nanodots of Fe on semiconductor TiO2 nanotubes (TNTs) are investigated with time-of-flight grazing incidence small-angle neutron scattering (TOF-GISANS) as a function of wavelength, chosen from a set of three TNT templates with different correlation lengths. The results are found corroborating with the localized scanning electron microscopy (SEM) images. As we probe the inside and the near-surface region of the Fe-dotted TNTs with respect to their homogeneity, surface distortion and long-range order using TOF-GISANS, gradual aberrations at the top of the near-surface region are identified. Magnetization measurements as a function of temperature and field do not show a typical ferromagnetic behavior but rather a supermagnetic one that is expected from a nonhomogeneous distribution of Fe–dots in the intertubular crevasses.

Distorted surfaces of magnetic helium-peculiar stars: an application to a Cen

ABSTRACT Helium-peculiar magnetic chemically peculiar stars show variations of helium abundance across their surfaces. As a result of associated atmospheric scale height variations, the stellar surface becomes distorted, with helium-rich regions dented inwards. Effectively, on top of flux variations due to opacity effects, the depressed helium-rich surface regions become less bright in the optical regions and brighter in the ultraviolet. We study the observational effects of the aspherical surface on the light curves of a Cen. We simulate the light curves of this star adopting surface distributions of He, N, O, Si, and Fe derived from Doppler mapping and introducing the effect of distortion proportional to helium abundance. We show that while most of the optical and UV variations of this star result from flux redistribution due to the non-uniform surface distributions of helium and iron, the reduction of light variations due to the helium-related surface distortion leads to a better agreement between simulated optical light curves and the light curves observed with the BRITE satellites.

Assessment of Secondary Fiber Print-Through Effects on Class-A CFRP Parts Produced with Highly Cost Efficient Processes

Cost-optimized materials and processes are the key to high-performance components at attractive production costs. This study shows that non crimp fabrics (NCF) used as inner layers of high performance Class-A cfrp parts can lead to unwanted print-through effects on Class-A composite surfaces, even though they are not the surface layer. This surface distortion that is expressed in scattered lines in the direction of inner NCF layers can lead to high reject rates and is normally first noticed in the painted state. The presented methodology is able to quantify this secondaryprint-through effect for cured composites as well as for the dry textile intermediates. The surface can be measured with conventional measuring techniques, such as laser triangulation or interferometers, and characterized with the standardized values Sz and Sz25. The results show that the visible and measurable more uneven surface of a 50k biaxial NCF leads to significantly higher Sz and Sz25 values in the dry textile and the cured component. Also the regularity of the measured textiles can be detected by determining the variation of different areas of a 800 by 800mm sized sample. The presented methodology has the potential to optimize the incoming goods inspection of high volume Class-A composite manufacturers, as well as the requirement-orientated and cost-efficient development of textile intermediates by suppliers.