A fundamental mode converter based on tapered LiNbO3-on-insulator photonic wire with a laterally asymmetric structure

A number of computing systems devoted to the averaging of electron images of two-dimensional macromolecular crystalline arrays have facilitated the visualization of negatively-stained biological structures. Either by simulation of optical filtering techniques or, in more refined treatments, by cross-correlation averaging, an idealized representation of the repeating asymmetric structure unit is constructed, eliminating image distortions due to radiation damage, stain irregularities and, in the latter approach, imperfections and distortions in the unit cell repeat. In these analyses it is generally assumed that the electron scattering from the thin negativelystained object is well-approximated by a phase object model. Even when absorption effects are considered (i.e. “amplitude contrast“), the expansion of the transmission function, q(x,y)=exp (iσɸ (x,y)), does not exceed the first (kinematical) term. Furthermore, in reconstruction of electron images, kinematical phases are applied to diffraction amplitudes and obey the constraints of the plane group symmetry.

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Cell surface changes during aging of human bladder epithelium examined by lectin probes and SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162429 ◽

1990 ◽

Vol 48 (3) ◽

pp. 966-967

Author(s):

J. Jacob ◽

M.F.M. Ismail

Keyword(s):

The Elderly ◽

Ultrastructural Changes ◽

Pokeweed Mitogen ◽

Asymmetric Structure ◽

Luminal Surface ◽

Bladder Epithelium ◽

Aldehyde Groups ◽

Cell Surface Changes ◽

Phosphate Buffered Saline ◽

Surface Changes

Ultrastructural changes have been shown to occur in the urinary bladder epithelium (urothelium) during the life span of humans. With increasing age, the luminal surface becomes more flexible and develops simple microvilli-like processes. Furthermore, the specialised asymmetric structure of the luminal plasma membrane is relatively more prominent in the young than in the elderly. The nature of the changes at the luminal surface is now explored by lectin-mediated adsorption visualised by scanning electron microscopy (SEM).Samples of young adult (21-31 y old) and elderly (58-82 y old) urothelia were fixed in buffered 2% glutaraldehyde for 10 m and washed with phosphate buffered saline (PBS) containing Ca++ and Mg++ at room temperature. They were incubated overnight at 4°C in 0.1 M ammonium chloride in PBS to block any remaining aldehyde groups. The samples were then allowed to stand in PBS at 37°C for 2 h before incubation at 37°C for 30 m with lectins. The lectins used were concanavalin A (Con A), wheat germ agglutinin (WGA), phytohaemagglutinin (PHA) and pokeweed mitogen (PWM) at a concentration of 500 mg/ml in PBS at pH 7.A.

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