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Povzetek: Enamel demineralization, known as dental caries, is instigated by the bacterium Streptococcus mutans, which generates acid during carbohydrate metabolism. Among carbohydrates, sucrose is the most cariogenic and capable of biofilm formation. This study aimed to explore and comprehend Streptococcus mutans’ adherence to two prevalent dental material surfaces, i.e., a cobalt–chromium(Co-Cr) alloy and a resin-based composite, under the influence of various sucrose concentrations. To understand bacterial adhesion, the surfaces were characterized using profilometry, tensiometry, and surface charge measurements. Bacterial adhesion was evaluated using scanning electron microscopy and crystal violet dye methods. Results revealed that the composite surface exhibited greater rough-ness compared with the Co-Cr alloy surface. Both surfaces displayed hydrophilic properties and a negative surface charge. Bacterial adhesion experiments indicated lower bacterial adherence to the Co-Cr alloy than to the composite surface before the addition of sucrose. However, the introduction of sucrose resulted in biofilm development on both surfaces, showcasing a similar increase in bacterial adhesion, with the highest levels being observed at a 5% sucrose concentration in the bacterial suspension. In conclusion, the findings suggest sucrose-rich foods could facilitate bacterial adaptation despite less favorable surface characteristics, thereby promoting biofilm formation.
Ključne besede: bacterial adhesion, streptococcus mutans, dental material surfaces, sucrose concentration
Objavljeno v DiRROS: 31.01.2024; Ogledov: 204; Prenosov: 81
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Ključne besede: ekosistemske storitve, vrednotenje, kartiranje, Jelovica, kaskadni model
Objavljeno v DiRROS: 26.01.2024; Ogledov: 262; Prenosov: 0

Povzetek: This paper explores the possibility of using flexible polymer adhesives to dissipate energy in CLT buildings during earthquakes. In the first series of tests, pull-off tests of various polyurethane (PUR) adhesives were performed. The connection was tested in pull-pull configuration using monotonic, tension-only loading. The tests have shown that the adhesive can resist large deformations already in tension loading and with small thicknesses of the bond-line. Based on the pull-off test results, one adhesive has been selected for further testing. Monotonic lap-shear tests were performed with the selected adhesive and thick bond-line (3 mm and 6 mm). The results show, that the standard method for lap-shear testing (EN 205) needs to be adapted for thick glue-line. It was found that the strength of 3 mm glue-line is higher than 6mm one, which is in agreement with adhesion theory. The flexible PUR adhesives could potentially be used in CLT structures for anchoring the CLT wall with “flexible” glued-in rods or as a “flexible” vertical shear connection between the CLT walls. Such systems have a potential to dissipate energy in seismic areas.
Ključne besede: CLT connections, flexible adhesive, polyurethane, energy dissipation, pull-off, lap-shear
Objavljeno v DiRROS: 19.01.2024; Ogledov: 187; Prenosov: 84
Celotno besedilo (18,89 MB)
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Ključne besede: projekt Life IP CARE4CLIMATE, raba tal, spremembe rabe tal, gozdarstvo, aktivnosti
Objavljeno v DiRROS: 16.01.2024; Ogledov: 249; Prenosov: 0

Objavljeno v DiRROS: 16.01.2024; Ogledov: 186; Prenosov: 49
Celotno besedilo (484,29 KB)