Biomimetic sol-gel mineralization of polysaccharides by silicon and titanium polyolates

In this work, we have demonstrated that in addition to silicon tetraglycerolate, a new water-soluble biocompatible polyolate precursors – silicon tetrapolyethylene glycolate Si[O(CH2CH2O)nH]4 [5, 6] and titanium tetrapolyethylene glycolate Ti[O(CH2CH2O)nH]4 [5] – can be successfully utilized in biomimetical mineralization of polysaccharides of various nature. By the example of chitosan (cationic), xanthan gum (anionic), and hydroxyethyl cellulose (uncharged) polysaccharides, an accelerating effect has been demonstrated on the gelation process and a stabilizing effect has been revealed on the hydrogels formed as transparent monoliths showing resistance to syneresis. Thus formed silicon- and titanium-containing 3D-network of gels is found to be polymeric and appears to have ordered amorphous morphostructure, which can be explained as caused by the influence from the polysaccharides serving as templates. The presence of polyolate bridges between silicon or titanium atoms in the polymeric network is characteristic of polyolate precursors only and is determined mainly by the nature of the precursor and by the contents of polyol and water in the system. The formation of polyolate bridges is facilitated by the low reactivity of the precursor, by low water content, and also by polyol excess in the system. The sol-gel process utilized to obtain the silicon- and titanium-polysaccharide-containing hydrogels proceeds under the mild conditions at room temperature, with no catalyst or any organic solved to be used, and thus can be regarded as belonging to the green chemistry methods that show promise for biomedical materials applications.This work was carried out in the framework of the Russian State Assignment (theme № АААА-А19-119011790134-1)

Fabrication of optical waveguides in RbTiOPO4 single crystals by using different techniques

M.A. Butt, M.C. Pujol, R. Solé, A. Ródenas, G. Lifante, M. Aguiló, F. Díaz, S. N. Khonina, R. V. Skidanov and Payal Verma, "Fabrication of optical waveguides in RbTiOPO4 single crystals by using different techniques", XIII International Scientific and Technical Conference on Optical Technologies in Telecommunications,SPIE 9807 (26 March, 2016): doi: 10.1117/12.2231368. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibitedProceedings of XIII International Scientific and Technical Conference on Optical Technologies in Telecommunications Conference (Ufa, Russian Federation)In this work, we have demonstrated the use of different technologies to fabricate straight channel waveguides, S-bend waveguides, Y-splitter and Mach -Zehnder (MZ) structures on RbTiOPO 4 crystals and its isomorphs. We used reactive ion etching (RIE), inductively coupled plasma-RIE (ICP-RIE), femtosecond pulse laser micro-fabrication and ion diffusion techniques to structure these crystals. Computer simulations have been carried out and compared with the optical characterization of the waveguides which are in agreement with each other.This work is supported by the Ministry of Education and Science of the Russian Federation, Russian Science Foundation (grant No. 14-19-00114), Spanish Government under Projects MAT2011-29255-C02-02, TEC2014-55948-R, MAT2013-47395, C4-4-R/1-R and by the Catalan Authority under Project 2014SGR135

Ultrafast laser micro-nano structuring of transparent materials with high aspect ratio

Ultrafast lasers are ideal tools to process transparent materials because they spatially confine the deposition of laser energy within the material's bulk via nonlinear photoionization processes. Nonlinear propagation and filamentation were initially regarded as deleterious effects. But in the last decade, they turned out to be benefits to control energy deposition over long distances. These effects create very high aspect ratio structures which have found a number of important applications, particularly for glass separation with non-ablative techniques. This chapter reviews the developments of in-volume ultrafast laser processing of transparent materials. We discuss the basic physics of the processes, characterization means, filamentation of Gaussian and Bessel beams and provide an overview of present applications

Minimizing the Bright/Shadow Focal Spot Size with Controlled Side-Lobe Increase in High-Numerical-Aperture Focusing Systems

Minimizing the bright/shadow focal spot size for differently polarized incident waves through the additional apodization of the focusing system output pupil by use of an optical element with the vortex phase dependence on angle and the polynomial amplitude dependence on radius is studied. The coefficients of the radial polynomial were optimized with the aim of fulfilling certain conditions such as the energy efficiency preservation and keeping the side lobes under control. The coefficients were chosen so as to minimize the functional using Brent’s method

Two-point resolution with spherical aberration quadratic amplitude filters

The study deals with the effects of spherical aberration on the Airy distribution of two overlapping point images of equal- or unequal-intensities separated by the distances less than the Rayleigh angular limit of resolution investigated. Aberration considered in this work is the primary spherical aberration. By employing the quadratic amplitude apodization across the aperture, the high resolution is achieved in the form of resolving the two-point images, which is higher than that of the unapodized ones. In this investigation, the apodization mask applied to the aperture and the corresponding intensity distributions of two-point images have been studied numerically