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Study of conjugates of sphingolipids with hyaluronic acid and their application on the skin
Juhaščik, Martin ; Kováčik, Andrej (advisor) ; Gajdziok, Jan (referee) ; Miletín, Miroslav (referee)
1 ABSTRACT Charles University, Faculty of Pharmacy in Hradec Králové Training Workplace Department of Pharmaceutical Technology Doctoral Degree Program Pharmaceutical Technology Candidate Mgr. Martin Juhaščik Supervisor doc. PharmDr. Andrej Kováčik, Ph.D. Advisor Gloria Huerta-Ángeles, Ph.D. Title of Doctoral Thesis Study of conjugates of sphingolipids with hyaluronic acid and their application on the skin The main goal of this study was to systematically design and subsequently prepare conjugates of hyaluronic acid (HA) with selected sphingolipids, which could find application in their topical administration during physiological decline of skin functions. In this study, phytosphingosine and ceramide were chemically linked to HA via biocompatible linkers, enabling successful modification of HA into a hydrophobized conjugate of sphingolipid-linker-hyaluronate. The preparation of succinylceramide-hyaluronate conjugate was found to be the most effective. The developed method of preparing the conjugate using mixed anhydrides brings several advantages, including the possibility of scaling up the preparation and conducting reactions in an aqueous environment. The method was effective over a wide range of molecular weights, from 6 to 442 kgmol-1, achieving a degree of substitution of up to 14.2 %, surpassing the...
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Modification of transmissivity of hydrogen through the surface of Ni3Al by alloying
Čermák, Jiří ; Rothová, Věra
Hydrogen invasion into Ni3Al-M was studied by gas-permeation method in temperature range 573 - 1 223 K. The dependence of hydrogen permeation flux J(d) through the membrane-like samples on the samples thickness d enabled us to assess the influence of the surface upon the rate of permeation. The surface transmissivity was introduced as a quantitative characteristic describing the rate of the process. Influence of three modifying elements M = Fe, Cr and Zr was studied. It was found that Zr supports and, on the contrary, Cr eliminates the inhibiting effect of the surface. The iron did not alter significantly the hydrogen transmissivity, and it causes enhanced grain boundary brittleness in hydrogen environment.
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