Glycosylation is the process by which oligosaccharides, termed glycans, are appended onto membrane and secreted proteins and lipids. It is the most common and complex form of post-translational modification, with ϳ50% of all eukaryotic proteins glycosylated (1, 2). A majority of glycans are found on the cell surface, where they are optimally poised to be the first cellular components encountered by approaching cells, pathogens, antibodies, or other molecules, as well as advertise information about the internal state and homeostasis of the cell (3, 4). Therefore, glycans play an essential role in many biological processes, including cell development and differentiation, cell-cell or cell-matrix communication, and pathogen-host recognition (3,(5)(6)(7). In fact, differences in glycan profiles between healthy and diseased states are utilized for clinical diagnosis (7), providing targets for many novel classes of therapeutics including cancer chemotherapy, diabetes treatment, and antibiotic and anti-viral medicine (5, 8). Glycans are highly heterogeneous in nature, varying in the composition of individual monosaccharide building blocks, the positions with which these building blocks link to each other, and the stereochemical disposition of the linkages (␣ or ␤). This complexity has presented a significant challenge for obtaining structural information about glycans at the molecular From the

We have fabricated tapered photonic crystal fibers using a fusion splicer and experimentally observed the near-field mode distribution and the beam divergence of it. We have also compared characteristics of the tapered photonic crystal fiber with those of a tapered standard single-mode fiber. Unlike a tapered standard single-mode fiber, the mode field profile of a tapered photonic crystal fiber shows a good confinement of its field within the core region. The numerical apertures of tapered photonic crystal fibers are increased as the diameter of the fiber is decreased.

We report the fabrication process for several types of photonic crystal fibers (PCFs), which enables mass-production with a 125 µm diameter. Five layers of silica capillary tubes having 2 mm inner and 3 mm outer diameters were stacked in a hexagonal pattern around a silica rod of a 3 mm diameter. By jacketing a large silica tube around the tube stack, the preform for a PCF was obtained. Another type of PCF was made by stacking four tubes in one layer, which had 6 mm inner and 8 mm outer diameters. In order to draw PCFs from both types of preforms, a drawing tower for conventional fibers was used. In the beginning of the drawing process, the temperature was set to be the running temperature for the conventional fiber, and then lowered by a couple of hundreds degrees. The optical properties of the fabricated PCFs were measured with various hole sizes and pitches. In this paper there is included the intensity distribution of the guided beam that was a single mode at 1550 nm, and the transmission loss measured by using the cut back method, and the fundamental mode cut-off characteristic at a short wavelength, and the numerical aperture measured at several wavelengths by using the far field patterns.