Anisotropic metal nanoparticles: Synthesis, assembly, and optical applications

This feature article highlights work from the authors' laboratories on the synthesis, assembly, reactivity, and optical applications of metallic nanoparticles of nonspherical shape, especially nanorods. The synthesis is a seed-mediated growth procedure, in which metal salts are reduced initially with a strong reducing agent, in water, to produce approximately 4 nm seed particles. Subsequent reduction of more metal salt with a weak reducing agent, in the presence of structure-directing additives, leads to the controlled formation of nanorods of specified aspect ratio and can also yield other shapes of nanoparticles (stars, tetrapods, blocks, cubes, etc.). Variations in reaction conditions and crystallographic analysis of gold nanorods have led to insight into the growth mechanism of these materials. Assembly of nanorods can be driven by simple evaporation from solution or by rational design with molecular-scale connectors. Short nanorods appear to be more chemically reactive than long nanorods. Finally, optical applications in sensing and imaging, which take advantage of the visible light absorption and scattering properties of the nanorods, are discussed.     

Elliptic and Hyperelliptic Curves Over Supersimple Fields

It is proved that if F is an infinite field with characteristicdifferent from 2, whose theory is supersimple, and C is an ellipticor hyperelliptic curve over F with generic ‘modulus’,then C has a generic F-rational point. The notion of generityhere is in the sense of the supersimple field F.     

High-bandwidth transmission of an efficient photonic-crystal mode converter

We have investigated both theoretically and experimentally the spectral behavior and the transmission and reflection performance of a photonic-crystal (PhC) mode converter upon an InP substrate. This taper exhibits 70% transmission efficiency on an 80-nm bandwidth when it couples a ridge access guide to a strongly confined single-missing-row PhC guide. Such a taper design included in a PhC bend contributes a large benefit to the overall transmission budget of the PhC-based link.     

Phase-shifting windowed Fourier ridges for determination of phase derivatives

Determination of the phase or phase derivative from interferometric fringe patterns is an important task in optical interferometry. The use of wavelet ridges was recently shown to be an effective method for phase retrieval from a single fringe pattern. One necessary requirement in this method is the need for carrier frequency. In cases when carrier frequency is not available, the novel phase-shifting windowed Fourier ridges method can be used. Phase derivatives with the proper sign can be directly retrieved even in the presence of noise. An application for curvature determination from speckle shearographic fringes demonstrates the effectiveness of the method.     

Non-linear response of a string to random excitation

The mean square deflection of a non-linear string subjected to nonplanar Gaussian white noise excitation is determined by the perturbation method. It is shown that increase in tension due to stretching, and transverse transverse mode coupling tend to reduce the mean square deflection; while longitudinal-transverse mode coupling tends to counter this effect to some extent. These results are in conformity with the trend observed in the case of periodic excitation.     

Advantages of endoscopic laser arytenoidectomy using yag laser scalpel

The surgical management of bilateral vocal cord paralysis has been performed through an endoscope in the past. The etiology of bilateral vocal cord paralysis is usually secondary to trauma; to secure an adequate airway, a tracheostomy is performed. Endoscopic laser arytenoidectomy offers a safe method of decannulating patients with maintenance of good voice quality and a rima glottidis of 4–6 mm posteriorly. Several wavelengths are available to carry out this procedure, and this article will focus on Nd:Yag laser scalpel applications. The advantage of this method is the preservation of good voice quality with an option of an external procedure, if the need arises. The laser application offers excellent hemostasis, and decreased edema and scar tissue formation. The results of our study on 10 patients appear encouraging and superior with respect to other available wavelengths.     

A tandem mass spectrometric approach to the identification of O‐glycosylated glargine glycoforms in active pharmaceutical ingredient expressed in Pichia pastoris

Glycoforms of glargine expressed in Pichia pastoris were isolated by high‐performance liquid chromatography and analyzed by a series of chemical and mass spectrometric methods for the identification of various glycoforms, glycosylation position, nature and structure of glycans. Reduction and alkylation, peptide mapping techniques were used to decipher the amino acid site at which glycosylation had taken place. Chemical methods were coupled with mass spectrometry techniques such as electrospray ionization and matrix‐assisted laser desorption/ionization for identification of the glycosylation site. Copyright © 2009 John Wiley & Sons, Ltd.