Designing Complex Tapestries with Photography-Inspired Manipulation of Self-Organized Thin-Films.

Thin-films patterned with complex motifs are of fundamental interest because of their advanced optical, mechanical and electronic properties, but fabrication of these materials remains challenging. Self-organization strategies, such as immersion controlled reaction-diffusion patterning, have shown great potential for production of patterned thin-films. However, the autonomous nature of such processes limits controllable pattern customizability and complexity. Here, it is demonstrated that photography inspired manipulation processes can overcome this limitation to create highly-complex tapestries of micropatterned films (MPF's). Inspired by classical photographic processes, MPF's are developed, bleached, exposed, fixed, and contoured into user-defined shapes and photographic toning reactions are used to convert the chemical composition MPF's, while preserving the original stripe patterns. By applying principles of composite photography, highly complex tapestries composed of multiple MPF layers are designed, where each layer can be individually manipulated into a specific shape and composition. By overcoming fundamental limitations, this synergistic approach broadens the design possibilities of reaction-diffusion processes, furthering the potential of self-organization strategies for the development of complex materials.

Precision waveguide system for measurement of complex permittivity of liquids at frequencies from 60 to 90 GHz.

We describe a variable path length waveguide setup developed to accurately measure the complex dielectric permittivity of liquids. This is achieved by measuring the complex scattering parameter of the liquid in a waveguide section with a vector network analyzer in combination with an E-band frequency converter. The automated measurement procedure allows fast acquisition at closely spaced intervals over the entire measurement bandwidth: 60-90 GHz. The presented technique is an absolute method and as such is not prone to calibration errors. The technique is suited to investigate low-loss as well as high-loss liquids in contrast to similar setups described previously. We present measurements for a high-loss liquid (water), an intermediate-loss sample (ethanol), and for nearly loss-less n-octane. Due to the available phase information, the present data have an improved accuracy in comparison with literature data.

Probing the magnetic field of light at optical frequencies.

Light is an electromagnetic wave composed of oscillating electric and magnetic fields, the one never occurring without the other. In light-matter interactions at optical frequencies, the magnetic component of light generally plays a negligible role. When we "see" or detect light, only its electric field is perceived; we are practically blind to its magnetic component. We used concepts from the field of metamaterials to probe the magnetic field of light with an engineered near-field aperture probe. We visualized with subwavelength resolution the magnetic- and electric-field distribution of propagating light.

Novel instrument for surface plasmon polariton tracking in space and time.

We describe the realization of a phase-sensitive and ultrafast near-field microscope, optimized for investigation of surface plasmon polariton propagation. The apparatus consists of a homebuilt near-field microscope that is incorporated in Mach-Zehnder-type interferometer which enables heterodyne detection. We show that this microscope is able to measure dynamical properties of both photonic and plasmonic systems with phase sensitivity.

Influence of skinfold thickness on heparin absorption.

The absorption of high and low molecular fractions of heparin from the subcutaneous compartment was evaluated in eight healthy males. They were given an intravenous infusion of 4000 U calcium heparin in 4 hours and on another occasion a subcutaneous injection of 12,500 U calcium heparin (washout period of 1 week). Anticoagulation was monitored by anti-Xa, antithrombin activity, and activated partial thromboplastin time. To evaluate factors that might influence absorption, body weight, body fat, and abdominal skinfold thickness were recorded. There was a pronounced inter-individual variability in absorption but the absorption of the two fractions of heparin was similar. The highly variable absorption was related to the abdominal skinfold thickness, and this could have implications for therapeutic and prophylactic heparin regimens.

Collagen metabolism and phenotype after prostaglandin E2 treatment of granuloma: direct and macrophage-modulated effects.

Local administration of PGE2 (2 micrograms) to polyether sponges, implanted s.c. in rats, inhibited hydroxyproline and total protein accumulation, without altering relative amounts of collagen, when administered early during granuloma development. In contrast, while DNA as well as total protein accumulation was inhibited by local PGE2 treatment of established granuloma, hydroxyproline accumulation and the relative amounts of collagen were enhanced. This PGE2-induced collagen enhancement was associated with an increased type III : type I collagen ratio, possibly due to differential intracellular breakdown of newly synthesized collagen. The solubility of granuloma collagen was unaffected by PGE2. Impregnation of sponges with carrageenan before implantation, thereby giving macrophage-dominated granuloma, did not affect the changes in protein and DNA induced by later treatment with PGE2, but did reverse the PGE2-induced accumulation of hydroxyproline. This latter effect probably reflects macrophage-mediated, PGE2 enhancement of collagenolytic activity.