14 research outputs found
Badania wpływu budowy i modyfikacji powierzchni na właściwości tribologiczne powłok ditlenku tytanu otrzymywanych metodą zol-żel.
Struktura niniejszej rozprawy habilitacyjnej jest oparta na trzech
częściach. Pierwsza z nich przedstawia przegląd dostępnej literatury
dotyczącej właściwości tribologicznych powłok ditlenku tytanu. Druga
część przedstawia najważniejsze osiągnięcia autora na polu badań
tribologicznych cienkich powłok ditlenku tytanu otrzymywanych metodą
zol-żel. Łącznikiem między nimi jest zwięzły opis przygotowania powłok,
metod ich modyfikacji i zastosowanych technik eksperymentalnych...The structure of this work is based on three parts. The first part
covers the review of the literature available today, related to the issues
concerning the tribological properties of titanium dioxide coatings. The
second part illustrates the most important achievements of the author in
the field of the tribology of the thin titanium dioxide sol-gel coatings. The
link between these two parts is a concise description of the coatings
preparation, methods of their modification and applied experimental
techniques..
Surface area or diameter – which factor really determines the antibacterial activity of silver nanoparticles grown on TiO₂ coatings?
Titanium dioxide coatings were prepared on Si wafers using the sol–gel method. Four different types of coatings with silver nanoparticles (AgNPs) were synthesized. The diameter and surface density of AgNPs were conditioned by the concentration of Ag+ ions in the initial solution, time and UV illumination source. The bactericidal activity of AgNPs on the titanium dioxide coatings against the S. aureus strain were calculated as the percentage of the inhibition of bacterial growth after 24 hour incubation of microorganisms at 37°C on TiO₂ coatings with AgNPs. Control samples were coated with titanium dioxide without AgNPs. We concluded that the titanium dioxide coatings modified with silver nanoparticles had a high antibacterial activity. Moreover, we demonstrated strong dependence between surface areas of AgNPs and inhibition of bacterial growth. The obtained results evidence that the surface area of AgNPs grown on titanium dioxide coatings is a major factor determining their antimicrobial potential
Dialkyldithiophosphate Acids (HDDPs) as Effective Lubricants of Sol–Gel Titania Coatings in Technical Dry Friction Conditions
The goal of this study was the investigation of
the effectiveness of dialkyldithiophosphate acids (HDDPs)
films in improving the tribological properties of thin, sol–
gel derived titania coatings. Amorphous, anatase, and rutile
titania coatings were obtained using sol–gel dip–coating
deposition after treatment at 100, 500, and 1,000 C,
respectively. Titania coatings were then modified from the
liquid phase by HDDPs acids having dodecyl-(C12), tetradecyl-(C14),
and hexadecyl-(C16) alkyl chains deposited by
dip–coating (DC) and Langmuir–Blodgett (LB) methods.
The influence of the deposition procedure, the length of the
HDDPs alkyl chain and the type of titania substrate on the
surface morphology and tribological properties were studied.
It was found, using wetting contact angle measurements,
that these modifications of titania coatings decrease
the surface free energy and increase its hydrophobicity.
The surface topography imaged by Atomic force microscopy
(AFM), exhibit island-like or agglomerate features for
the DC deposition method, while smooth topographies
were observed for LB depositions. Tribological tests were
conducted by means of a microtribometer operating in the
normal load range 30–100 mN. An enhancement of tribological
properties was observed upon modification, as
compared to unmodified titania
Polystyrene nanoparticles: the mechanism of their genotoxicity in human peripheral blood mononuclear cells
Plastic nanoparticles are widely spread in the biosphere, but health risk associated with their
effect on the human organism has not yet been assessed. The purpose of this study was to
determine the genotoxic potential of non-functionalized polystyrene nanoparticles (PS-NPs) of
different diameters of 29, 44, and 72nm in human peripheral blood mononuclear cells (PBMCs)
(in vitro). To select non-cytotoxic concentrations of tested PS-NPs, we analyzed metabolic activity
of PBMCs incubated with these particles in concentrations ranging from 0.001 to 1000 ug/mL.
Then, PS-NPs were used in concentrations from 0.0001 to 100 ug/mL and incubated with tested
cells for 24 h. Physico-chemical properties of PS-NPs in media and suspension were analyzed
using dynamic light scattering (DLS), atomic force microscopy (AFM), scanning electron microscopy
(SEM) and zeta potential. For the first time, we investigated the mechanism of genotoxic
action of PS-NPs based on detection of single/double DNA strand-breaks and 8-oxo-2'-deoxyguanosine
(8-oxodG) formation, as well as determination of oxidative modification of purines
and pyrimidines and repair efficiency of DNA damage. Obtained results have shown that PS-NPs
caused a decrease in PBMCs metabolic activity, increased single/double-strand break formation,
oxidized purines and pyrimidines and increased 8oxodG levels. The resulting damage was completely
repaired in the case of the largest PS-NPs. It was also found that extent of genotoxic
changes in PBMCs depended on the size of tested particles and their f-potential value.Narodowe Centrum Nauki (NCN), Preludium 20 nr 2021/41/N/NZ7/0204