Near-field probing of slow Bloch modes on photonic crystals with a nanoantenna.

We study the near-field probing of the slow Bloch laser mode of a photonic crystal by a bowtie nano-aperture (BNA) positioned at the end of a metal-coated fiber probe. We show that the BNA acts as a polarizing nanoprobe allowing us to extract information about the polarization of the near-field of the slow-light mode, without causing any significant perturbation of the lasing process. Near-field experiments reveal a spatial resolution better than λ/20 and a polarization ratio as strong as 110. We also demonstrate that the collection efficiency is two orders of magnitude larger for the BNA than for a 200 nm large circular aperture opened at the apex of the same metal-coated fiber tip. The BNA allows for overcoming one of the main limitations of SNOM linked to the well-known trade off between resolution and signal-to-noise ratio.

Bowtie nano-aperture as interface between near-fields and a single-mode fiber.

We present the development and study of a single bowtie nano-aperture (BNA) at the end of a monomode optical fiber as an interface between near-fields/nano-optical objects and the fiber mode. To optimize energy conversion between BNA and the single fiber mode, the BNA is opened at the apex of a specially designed polymer fiber tip which acts as an efficient mediator (like a horn optical antenna) between the two systems. As a first application, we propose to use our device as polarizing electric-field nanocollector for scanning near-field optical microscopy (SNOM). However, this BNA-on-fiber probe may also find applications in nanolithography, addressing and telecommunications as well as in situ biological and chemical probing and trapping.

Serum lipids and demyelination in experimental allergic encephalomyelitis induced by the increased encephalitogenicity of myelin basic protein given with galactocerebrospide.

Cholesterol esters and free cholesterol were determined in the serum of guinea pigs with experimental allergic encephalomyelitis (EAE). EAE was induced by immunization with myelin basic protein (MBP) and galactocerebroside (GC). The results showed an increased content of cholesterol arachidonate and cholesterol linoleate during the period of clinical signs of EAE in comparison with the content of cholesterol esters in EAE induced by MBP without galactocerebroside. The content of free cholesterol was significantly reduced. Histological analyses showed intensive inflammatory lesions and demyelination which were not found in EAE induced by MBP without galactocerebroside.

The levels of free cholesterol and cholesterol esters in serum before, during and after the induction of experimental allergic encephalomyelitis in the guinea-pig.

Cholesterol esters and free cholesterol were determined in the serum of guinea-pigs with experimental allergic encephalomyelitis (EAE). EAE was induced by immunization with myelin basic protein (MBP). The results showed a marked decrease in cholesterol esters (CHE) 4 days after immunization. Seven days after immunization the values of esters increased and reached a maximum during the period of manifest clinical signs of EAE. After the cessation of clinical signs, after 2 weeks, the values of esters returned to the initial or somewhat lower values. The level of cholesterol was inverse to the values of cholesterol esters. Histological analyses showed characteristic changes in the brain and spinal cord. A possible correlation between the changes in cholesterol esters and cholesterol of the brain and serum in EAE is suggested.