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Wyszukujesz frazę "modification methods" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Modification of Nitinol Biomaterial for Medical Applications
Autorzy:
Hryniewicz, Tadeusz
Rokicki, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/1177981.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Nitinol biomaterial
electropolishing
fatigue resistance
magnetoelectropolishing (MEP)
modification methods
sterilization
Opis:
In the paper, a review of modification methods which have been applied to Nitinol intermetallic compound used as biomaterial for medical applications, is carried out. A variety of methods used for Nitinol improvement, beginning from its manufacture, covers mechanical treatment, heat treatment, chemical processing including water boiling, electropolishing, plasma ion implantation, coating to improve the corrosion resistance, minimize nickel leaching, improve osseointegration, and/or vascular compatibility, sterilization and disinfection. Nitinol alloying by addition of a third element to replace Ti or Ni has an enormous effect on phase transformation, corrosion resistance and biocompatibility of the newly created ternary Nitinol alloy. Unfortunately, the ternary nitinol alloys – apart from NiTiCu in actuators and NiTiCr in wires used as a pulling-pushing tool in minimally invasive spine operation – have not found a widespread industrial application yet. One of the most effective surface finishing operations used for metallic biomaterials, with a special attention directed to Nitinol, appears to be magnetoelectropolishing (MEP). A uniform magnetic field used in MEP process can be generated by permanent magnets or by electromagnets. MEP leads to refinement of surface chemical composition impossible to achieve by standard electropolishing. During MEP of alloys and intermetallic compounds, ferromagnetic elements, such as Fe (from stainless steels) or Ni, are primarily removed from the surface so that the passive film on Nitinol is totally composed of titanium oxide. One more unique feature of metal samples after MEP is their de-hydrogenation noticed both in stainless steels, niobium, titanium and Nitinol. In fact, the fatigue resistance of Nitinol after MEP referred to as-received, dependent on the refinement and displacement of inclusions, increases from three to seven times.
Źródło:
World Scientific News; 2018, 96; 35-58
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modification of Salix americana willow bark for removal of heavy metal ions from aqueous solutions
Autorzy:
Rypińska, Iwona
Biegańska, Marta
Powiązania:
https://bibliotekanauki.pl/articles/779386.pdf
Data publikacji:
2014
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
waste
adsorption
heavy metals
willow bark
methods of modification
Opis:
Salix americana willow bark is a waste arising in the process of wicker decortication that so far has not found Any practical application. The bark can adsorb metal ions, because in its composition among others are phenolic groups which may be involved in the removal of metal ions from water solutions. The results of sorption of copper(II) and zinc(II) on modifi ed willow bark of Salix americana were presented. The bark was modifi ed with nitric and sulfuric acids at concentrations ranging from 5 to 15%. The best adsorption results were obtained using 15% nitric acid for modifi cation. Adsorption of metal ions from aqueous solutions at concentrations raging from 20 to 100 mg/dm3 was studied. It was found that an increase in the initial concentration of copper(II) and zinc(II) resulted in an increase in their adsorption on the modifi ed cortex.
Źródło:
Polish Journal of Chemical Technology; 2014, 16, 4; 41-44
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gold catalysts supported on zeolites
Katalizatory złotowe osadzone na zeolitach
Autorzy:
Walkowiak, Adrian
Powiązania:
https://bibliotekanauki.pl/articles/2057912.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
heterogeniczne katalizatory złotowe
nanocząstki złota
zeolity
metody modyfikacji zeolitów złotem
zastosowanie zeolitów modyfikowanych złotem
proces katalityczny
heterogeneous gold catalysts
gold nanoparticles
zeolites
methods of zeolites modification with gold
application of gold-modified zeolites
catalytic process
Opis:
Heterogeneous gold catalysis is a relatively young but dynamically developing field of chemistry. At the end of the 1980s, Masatake Haruta and Graham Hutchings provided experimental evidence of high activity of supported gold catalysts in CO oxidation and acetylene hydrochlorination. Thus, these two researchers challenged the prevailing chemists’ belief that gold is almost completely chemically inert and catalytically inactive. Since then, gold catalysis has been constantly in the centre of attention of a wide array of scientists from around the world. However, there are still many questions about the nature of catalysts containing this noble metal, which inspires in-depth research in this field. From among various potential supports for gold heterogeneous catalysts, zeolites have drawn much attention thanks to several unique properties of this group of materials, among which the most important are high thermal stability and the presence of a system of pores of strictly defined sizes. Zeolites have extremely large surface area, which is desirable to obtain high dispersion of the active phase. The article provides a concise overview of the methods of gold nanoparticles deposition on zeolitic supports and catalytic applications of such materials. The first chapter sheds light on the properties of bulk and nano-sized Au and depicts the background of gold catalysis development. In the following part, a brief description of zeolites and their properties is delivered. The third chapter is devoted entirely to the description of several preparation methods of zeolite-supported gold catalysts and their applications in different catalytic processes. The following post-synthetic methods of zeolite modification with gold are described: impregnation, ion exchange, deposition-reduction, chemical vapour deposition, and grafting. The most important advantages and disadvantages of each method are summarized. The article concludes with a résumé of literature reports concerning the use of zeolitesupported gold catalysts in various processes. Special attention was paid to selective oxidation of alcohols and biomass-derived chemicals (e.g. glucose).
Źródło:
Wiadomości Chemiczne; 2021, 75, 11-12; 1259--1293
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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