Holography for field theory solitons

We extend a well-known D-brane construction of the AdS/dCFT correspondence to non-abelian defects. We focus on the bulk side of the correspondence and show that there exists a regime of parameters in which the low-energy description consists of two approximately decoupled sectors. The two sectors are gravity in the ambient spacetime, and a six-dimensional supersymmetric Yang-Mills theory. The Yang-Mills theory is defined on a rigid AdS_4 x S^2 background and admits sixteen supersymmetries. We also consider a one-parameter deformation that gives rise to a family of Yang-Mills theories on asymptotically AdS_4 x S^2 spacetimes, which are invariant under eight supersymmetries. With future holographic applications in mind, we analyze the vacuum structure and perturbative spectrum of the Yang-Mills theory on AdS_4 x S^2, as well as systems of BPS equations for finite-energy solitons. Finally, we demonstrate that the classical Yang-Mills theory has a consistent truncation on the two-sphere, resulting in maximally supersymmetric Yang-Mills on AdS_4.Comment: 78 pages plus appendices, 4 figures; v2: references added; v3: typos corrected, published versio

One-Step Deposition Process to Obtain Nanostructured Superhydrophobic Thin Films by Galvanic Exchange Reactions

Superhydrophobic thin films of silver were fabricated on copper substrates by galvanic ion exchange reactions in a one-step process by immersing copper substrates in silver nitrate solution containing fluoroalkylsilane in different quantities. The X-ray diffraction (XRD) analyses confirmed the formation of silver films on copper substrates and the fractal-like morphological features of the silver films were confirmed using scanning electron microscopy (SEM). The contact angle of water on these surfaces is found to be greater than 165°, demonstrating water repellency with water drops rolling off the surfaces. The X-ray photoelectron spectroscopy (XPS) depth profile confirms the presence of fluorine in the silver films

Supersymmetry of the D3/D5 Defect Field Theory

Four-dimensional N=4 super Yang-Mills, with a codimension-one defect breaking half of the supersymmetry, arises as the field theory description of the D3/D5 intersection in the holographic limit. This is one of the earliest, most extensively studied, and commonly used systems in holography. In this note we give the full R-symmetry-covariant supersymmetry variations for this system. We also provide the supercurrents and compute the algebra of the corresponding supercharges, obtaining the full set of central charges. We show that magnetically charged finite-energy field configurations preserving half of the supersymmetry are solutions to a new form of the extended Bogomolny equations, in which the defect fields play the role of jumping data for the Nahm-like part of the equations. In the appendices, we explain the connection between our results and the superspace-based formulations in the literature.Comment: 32 pages, 1 figure, 1 table. In v3: additional section added describing preliminary application of results to BPS solitons; references adde

Superhydrophobic properties of ultrathin rf-sputtered Teflon films coated etched aluminum surfaces

Superhydrophobicity has been demonstrated on ultrathin rf-sputtered Teflon coated etched aluminum surfaces. The etching of aluminum surfaces has been performed using dilute hydrochloric acid. An optimized etching time of 2.5 min is found to be essential, before Teflon coating, to obtain a highest water contact angle of 164 ± 3° with a lowest contact angle hysteresis of 2.5 ± 1.5°, with the water drops simply rolling off these surfaces with even the slightest inclination of the sample. The presence of − CF3 radicals along with − CF2 radicals in the ultrathin rf-sputtered Teflon films, as investigated by X-ray photoelectron spectroscopy (XPS), contributes to the lowering of the surface energy on the aluminum surfaces. The presence of patterned microstructure as revealed by field emission scanning electron microscope (FESEM) together with the low surface energy ultrathin rf-sputtered Teflon films renders the aluminum surfaces highly superhydrophobic

Wetting and superhydrophobic properties of PECVD grown hydrocarbon and fluorinated-hydrocarbon coatings

Wetting characteristics of micro-nanorough substrates of aluminum and smooth silicon substrates have been studied and compared by depositing hydrocarbon and fluorinated-hydrocarbon coatings via plasma enhanced chemical vapor deposition (PECVD) technique using a mixture of Ar, CH4 and C2F6 gases. The water contact angles on the hydrocarbon and fluorinated-hydrocarbon coatings deposited on silicon substrates were found to be 72° and 105°, respectively. However, the micro-nanorough aluminum substrates demonstrated superhydrophobic properties upon coatings with fluorinated-hydrocarbon providing a water contact angle of ∼165° and contact angle hysteresis below 2° with water drops rolling off from those surfaces while the same substrates showed contact angle of 135° with water drops sticking on those surfaces. The superhydrophobic properties is due to the high fluorine content in the fluorinatedhydrocarbon coatings of ∼36 at.%, as investigated by X-ray photoelectron spectroscopy (XPS), by lowering the surface energy of the micro-nanorough aluminum substrates

Polymer masks fabrication by micropatterning surfaces of composite polymer coatings

Micropatterning of surfaces has been demonstrated using composite polymer coatings of PS and PMMA of equal molecular weights in different volume proportions with varying surface topographies on silicon surfaces. The creation of PMMA masks with various surface morphological features has also been demonstrated by removal of PS from the composite coatings using cyclohexane. Atomic force microscopy (AFM) investigations revealed that the surface pattern and the dimensions of these masks significantly changed with the change in the volume proportions of each homopolymer. The composite coatings of 20/80 vol% PS/PMMA, 50/50 vol% PS/PMMA, and 80/20 vol% PS/PMMA resulted in PMMA masks with holes (depth ∼300 nm), wrinkles (height ∼350nm) and pillars (height ∼600 nm), respectively. Surface compositional analysis carried out using FTIR and XPS investigations confirmed the presence of polymer coatings of PS, PMMA and PS/PMMA. XPS investigations also confirmed the successful removal of PS from the PMMA mask by showing the presence of the silicon substrate on those masks where PS was previously present. The water contact angle of the composite polymer masks ranged from 70 to 90° which increased with the increase of PS vol% in the composite. The wetting behavior of certain PMMA masks showed hydrophobicity with water contact angle values above 90°

Superhydrophobic aluminum alloy surfaces by a novel one-step process

A simple one-step process has been developed to render aluminum alloy surfaces superhydrophobic by immersing the aluminum alloy substrates in a solution containing NaOH and fluoroalkyl-silane (FAS-17) molecules. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements have been performed to characterize the morphological features, chemical composition and superhydrophobicity of the surfaces. The resulting surfaces provided a water contact angle as high as ∼162° and a contact angle hysteresis as low as ∼4°. The study indicates that it is possible to fabricate superhydrophobic aluminum surfaces easily and effectively without involving the traditional two-step processes