Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

Metallic seed nanolayers for enhanced nucleation of nanocrystalline diamond thin films

The enhancement of the nucleation and subsequent growth of nanocrystalline diamond (NCD) films with a submicrometer thickness control on silicon substrates is demonstrated by using a sputter deposition of six different metallic (Cr, Mo, Nb, Ti, V and W) seed nanolayers. The effectiveness of altered surface morphology and surface chemistry is discussed. We show that the number density of nanodiamond particles embedded on the nanorough metallic surfaces after an ultrasonic seeding step together with the dynamic surface chemistry during hot-filament chemical vapor deposition of diamond determine the nucleation kinetics, microstructure and surface topography of the NCD films. Overall, the smoothest NCD layer (root-mean-square roughness 10 nm) was obtained with the highest seed density of diamond nanoparticles anchored to the metallic (W) surface. In particular, the rapid carbide-forming metals Mo, Nb and W showed the highest number density of diamond crystallites formed during the NCD nucleation stage, which resulted in dense, uniform and very smooth NCD films. Much rougher NCD films (17-37 nm) were obtained on the Cr, Ti, and V nanolayers that did not form carbides rapidly. Importantly, the carbon phase purity of the grown NCD films remains unaffected by the presence of different metallic seed nanolayers. Furthermore, we have assessed that the metallic nanolayer surface morphology does not play a relevant role in the enhancement of the seeding step. © 2013 American Chemical Society.J.G.B. thanks the Executive Research Agency of the European Union for funding under the Marie Curie Grant “NANODIA” (272448). This work has been partially supported by Comunidad Autónoma de Madrid (Project No. S2009/PPQ-1642, AVANSENS) and Ministerio de Economiá y Competitividad (FIS2012-38866-C05-05).Peer Reviewe

Metallic Seed Nanolayers for Enhanced Nucleation of Nanocrystalline Diamond Thin Films

The enhancement of the nucleation and subsequent growth of nanocrystalline diamond (NCD) films with a submicrometer thickness control on silicon substrates is demonstrated by using a sputter deposition of six different metallic (Cr, Mo, Nb, Ti, V and W) seed nanolayers. The effectiveness of altered surface morphology and surface chemistry is discussed. We show that the number density of nanodiamond particles embedded on the nanorough metallic surfaces after an ultrasonic seeding step together with the dynamic surface chemistry during hot-filament chemical vapor deposition of diamond determine the nucleation kinetics, microstructure and surface topography of the NCD films. Overall, the smoothest NCD layer (root-mean-square roughness 10 nm) was obtained with the highest seed density of diamond nanoparticles anchored to the metallic (W) surface. In particular, the rapid carbide-forming metals Mo, Nb and W showed the highest number density of diamond crystallites formed during the NCD nucleation stage, which resulted in dense, uniform and very smooth NCD films. Much rougher NCD films (17–37 nm) were obtained on the Cr, Ti, and V nanolayers that did not form carbides rapidly. Importantly, the carbon phase purity of the grown NCD films remains unaffected by the presence of different metallic seed nanolayers. Furthermore, we have assessed that the metallic nanolayer surface morphology does not play a relevant role in the enhancement of the seeding step

Coherence approach in neutron, x-ray, and neutron spin-echo reflectometry

Based on the application of coherence theory to neutron scattering a description is given of the propagation of neutrons or x-rays through a reflectometer. Important coherence effects at the sample position are discussed. Further, an outline is given how to determine the measured count rate in a detector on the basis of this method including neutron-polarization effects. It is shown in what way the Born approximation and distorted-wave Born approximation can be used within this theory. An outline is given of the phase-object approximation, describing the specular and diffuse scattering from a surface with large surface structure, extending over the existing capabilities of the distorted-wave Born approximation. The incorporation of neutron-polarization effects enables the detailed discussion of neutron spin-echo coding techniques applied to reflectometry.Radiation, Radionuclides and ReactorsApplied Science

Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals

We report on the surprisingly strong, broadband emission of coherent terahertz pulses from ultrathin layers of semiconductors such as amorphous silicon, germanium and polycrystalline cuprous oxide deposited on gold, upon illumination with femtosecond laser pulses. The strength of the emission is surprising because the materials are considered to be bad (amorphous silicon and polycrystalline cuprous oxide) or fair (amorphous germanium) terahertz emitters at best. We show that the strength of the emission is partly explained by cavity-enhanced optical absorption. This forces most of the light to be absorbed in the depletion region of the semiconductor/metal interface where terahertz generation occurs. For an excitation wavelength of 800 nm, the strongest terahertz emission is found for a 25 nm thick layer of amorphous germanium, a 40 nm thick layer of amorphous silicon and a 420 nm thick layer of cuprous oxide, all on gold. The emission from cuprous oxide is similar in strength to that obtained with optical rectification from a 300 ?m thick gallium phosphide crystal. As an application of our findings we demonstrate how such thin films can be used to turn standard optical components, such as paraboloidal mirrors, into self-focusing terahertz emitters.IST/Imaging Science and TechnologyApplied Science