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The Effect of Different White Spot Lesion Treatments on the Enamel Microhardness—An In Vitro Pilot Study
No full textDental caries, one of the most common oral diseases worldwide, represents a major public health concern. Contemporary dentistry has established several non-invasive approaches and resin infiltration, as a micro-invasive path, in the treatment of white spot lesions (WSLs). This study aimed to evaluate the effect of different WSL treatments on enamel surface microhardness. Materials and Methods: Seventy-five intact human premolars extracted upon orthodontic indication and the demineralizing solution composed of acetic acid, monopotassium phosphate and calcium chloride with pH = 4.4 and exposure time 96 h were used. The samples were randomly divided into five groups (n = 15): I—intact enamel (control group); II—artificial white spot lesion; III—artificial WSL treated with fluoride varnish; IV—artificial WSL treated with casein phosphopeptide—amorphous calcium phosphate (CPP-ACP) paste; V—resin-infiltrated artificial WSL. The surface microhardness was determined using the Oliver–Pharr method and a spherical indenter (Shimadzu Indenter, Kyoto, Japan). One-way analysis of variance (ANOVA) followed by a Post Hoc test (Bonferroni) was used with a level of significance set at p 0.05). Also, resin infiltration increased enamel microhardness compared to WSL values, with a statistically significant difference (p < 0.05). Fluoride varnish and CPP-ACP treatment resulted in equivalent values (50.84 ± 14.35 and 50.99 ± 15.31, respectively). Conclusions: Different WSL treatments (fluoride varnish, CPP-ACP and resin infiltration) produced comparable enamel microhardness values. Among the tested agents, resin infiltration resulted in higher microhardness values, while fluoride varnish and CPP-ACP demonstrated equivalent outcomes
Development of Multi-Doped Mesoporous Bioactive Glass and 3D-Printed Composite Scaffolds for Bone Tissue Engineering
No full textThe repair of large bone defects remains a significant clinical
challenge, driving the development of advanced 3D-printed composite
scaffolds that provide both mechanical stability and promote tissue
regeneration. The incorporation of mesoporous bioactive glass (MBG),
known for its mesoporosity, biocompatibility, and ability to load and release
drugs and ions, enhances the functional properties of these scaffolds,
positioning them as promising candidates for bone tissue engineering
applications
The Influence of TiO2 Nanoparticles on Thermal Decomposition of Polyurethane Hard Segments
No full textPolyurethanes are one of the most versatile materials, used in countless commercial applications,
mainly because of their outstanding performances. Due to the constant market need to push the
boundaries of quality, even with proven good materials, the incorporation of various
nanoparticles has become an established method for properties enhancement of polymer-based
materials. Therefore, the goal of this work was to investigate the influence of TiO2 nanoparticles
on thermal degradation and thermal degradation kinetics of the hard segments of polyurethane
network based on polycaprolactone and aliphatic hyperbranched polyester. For that purpose,
two composites were prepared by embedding 1.0 wt.% of unmodified or surface modified TiO2
nanoparticles into polyurethane matrix. Modified TiO2 nanoparticles were prepared by their
surface modification with lauryl gallate. In order to explore the influence of TiO2 nanoparticles
on thermal degradation kinetics of polyurethane network, thermogravimetric analysis at different
heating rates in nitrogen atmosphere was conducted and obtained results were compared with
results gathered for pure polyurethane. Model-free iso-conversional Ozawa-Flyyn-Wall method
was applied to evaluate kinetic energy of thermal degradation at various degrees of conversion.
Furthermore, Coats-Redfern model-fitting method and forty kinetic models were checked to find
the one that can adequately describe the degradation mechanism of the hard segments in
prepared samples. Obtained results revealed that the presence of unmodified or modified TiO2
nanoparticles led to the small decrease of the temperature of maximum thermal degradation rate
of weak urethane bonds in hard segments. Also, due to the lower crosslinking density, maximum
thermal decomposition rate of examined composites was visibly diminished in comparison to the
pure polymer. After application of different kinetic model functions through Coats-Redfern
equation, it was established that in the case of pure polyurethane network and composite
prepared with unmodified TiO2 nanoparticles, thermal degradation of urethane linkages can be
described by power law model, while two-dimensional diffusion is the best fitting kinetic model
for describing thermal degradation mechanism of urethane linkages in composite prepared with
modified TiO2 nanoparticles
Seasonal variations in the zooplankton population in the coastal waters of the southeastern Adriatic
No full textU radu iznosimo podatke iz sezonskih istraživanja hidrografije i zooplanktona. Uticaj
slatkih voda iz mnogobrojnih obalnih vrela i submarinskih izvora u Bokokotorskom zalivu,
kao i režim reka Bojane i Drima, te interbazenske izmjene vodenih masa na relaciji Jonsko
more – Jadran su stvorili jedinstven i raznolik morski ekosistem. Sastav zooplanktonske
zajednice se menja sa promenama uslova životne sredine. U ovom radu izneli smo neke
podatke o ekologiji i diverzitetu zooplanktona u južnom Jadranu.This paper presents data from seasonal research of hydrography and zooplankton. The
influence of freshwater inflows from numerous coastal springs and submarine sources in the
Bay of Boka Kotorska, as well as the hydrological regimes of the Bojana and Drin rivers
and the inter-basin exchange of water masses between the Ionian Sea and the Adriatic, has
created a unique and diverse marine ecosystem. The composition of the zooplankton
community changes in response to variations in environmental conditions. In this
contribution, we provide some data on the ecology and diversity of zooplankton in the
southern Adriatic Sea
Impact of flaxseed cake hydrolysis on antioxidant capacity
No full textCold pressing of flaxseed produces highquality oil along with a nutritionally rich byproduct—flaxseed cake. While the coldpressing process is valued for its minimal
processing and preservation of oil quality, it is
also characterized by low resource utilization
efficiency and significant by-product
generation. Specifically, the production of 1
kg of flaxseed oil results in approximately 2
kg of residual cake. Given its high protein
content (approximately 30–40%), flaxseed cake holds considerable potential as a source
of bioactive peptides and other value-added
compounds
In this study, flaxseed cake obtained
from cold pressing was milled and sieved to a
particle size below 0.6 mm. Its chemical
composition (protein, oil, fiber) was analyzed.
Controlled enzymatic hydrolysis was
performed with trypsin for 2 h. An E/S ratio
was 5 %, and the temperature used for
hydrolysis was 37 °C. The antioxidant
capacity of the non-hydrolyzed sample and
hydrolysate was determined.
Protein content was 37 %, oil was about
21 %, and fiber was approximately 28 %. The
results showed a degree of hydrolysis of about
5 % and a significant increase in antioxidant
activity. By determining the concentration of
flaxseed powder required to inhibit 50 % of
the DPPH free radicals, it was observed that
this concentration was significantly (p < 0.05)
higher in the non-hydrolyzed sample (11.0
mg/mL) compared to the hydrolysate (9.1
mg/mL)
Influence of Layer Height on Cavitation Rate of 3D-printed PLA
No full textThis study investigates the cavitation erosion behaviour of PLA (polylactic acid) specimens fabricated by Fused Deposition Modelling (FDM) using different layer heights (0.1, 0.2, and 0.3 mm). The samples were exposed to cavitation at a frequency of 20 ± 0.5 kHz for 60 and 120 minutes. Visual inspection revealed that
smaller layer heights resulted in finer surface morphology, better interlayer bonding, and improved resistance to cavitation. After 60 minutes, slight surface roughening and local delamination were observed in all samples, while after 120 minutes, surface degradation became more pronounced, especially for larger layer heights.
Samples printed with a 0.1 mm layer height mainly exhibited plastic deformation and minor delamination, those with 0.2 mm showed a combination of plastic deformation and delamination, whereas the 0.3 mm specimens were dominated by large-scale detachment and severe surface damage. The cavitation rate diagram, obtained from mass loss measurements, confirmed these observations. The lowest mass loss rate (0.77 mg/min) was recorded for the 0.1 mm samples, while the highest rate (1.50 mg/min) corresponded to the 0.3 mm samples. The results demonstrate that increasing layer height significantly reduces the cavitation resistance of FDM-printed PLA due to weaker interlayer cohesion and higher surface roughness
Impact of the composition of alginate-yeast hydrogel beads on dye biosorption
No full textIntroduction: Wastewater from the dyeing industry poses a significant
environmental challenge. Among the various treatment methods, biosorption
is considered both cost-effective and environmentally friendly. In this study,
spent brewery yeast is proposed as a promising biosorbent. Yeast cells
possess a cell wall structure composed of polysaccharides, proteins, and
lipids, which contain various functional groups such as hydroxyl, carboxyl,
phosphate, and amino groups. These groups actively participate in the
binding of contaminants, including heavy metals and synthetic dyes, through
mechanisms like ion exchange, complexation, and physical adsorption.
Alginate, a naturally occurring polysaccharide derived primarily from brown
seaweed, is widely recognized for its biocompatibility, non-toxicity, and gelforming ability. These properties make it an excellent candidate for
biosorption applications. Its porous structure and functional groups allow for
the effective binding dyes. Moreover, alginate beads are easy to produce via
simple techniques like extrusion, making the material both cost-effective and
environmentally sustainable for large-scale applications. ..
Laccase-mediated synthesis of phloridzin oligomers: An insight into the influence of reaction conditions and evaluation of oligomers’ biological activity
No full textThe effect of key experimental factors on phloridzin oligomerization catalyzed by Trametes versicolor laccase was investigated, and biological activity of synthesized oligomers was evaluated. Mass spectrometry analysis of the obtained reaction mixture showed the presence of oligomers with the degrees of polymerization two and three with dimer as the major product. The detected masses of the formed oligomers indicated the repetition of phloridzin units in their structure and the loss of two hydrogen atoms during the linkage formation, while NMR analysis of the major dimer confirmed the presence of two phloridzin molecules linked via a C5-C5 bond. The effect of temperature, substrate, and enzyme concentration on phloridzin conversion and products’ yield was examined, and for achieving the highest products yield (4.1 mg/ml), optimal factors were 40 °C temperature, 5 mg/ml phloridzin concentration and 0.5 mg/ml laccase concentration. Synthesized oligomers showed good antioxidant activity compared to phloridzin and very good potential to be used as skin prebiotics since they exhibited inhibitory effect on opportunistic pathogen Staphylococcus aureus and stimulating effect on commensal bacteria Staphylococcus epidermidis in a broad range of tested concentrations. The highest prebiotic capacity was demonstrated at a concentration of 0.0195 mg/ml in S. epidermidis and S. aureus co-culture
Ultrasound-Assisted Extraction Followed by Inductively Coupled Plasma Mass Spectrometry and Multivariate Profiling of Rare Earth Elements in Coffee
No full textA rapid and efficient ultrasound-assisted extraction (UAE) procedure followed by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of 14 rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), along with yttrium (Y) and scandium (Sc), in coffee samples. The method was validated using certified reference material (NIST SRM 1547), recovery tests at four fortification levels, and comparisons with microwave-assisted digestion (MAD). Excellent accuracy and precision were achieved, with recovery rates ranging from 80.1% to 112% and relative standard deviations (RSD%) below 14%. Limits of detection (LODs) ranged from 0.2 ng/kg (Yb) to 0.16 µg/kg (Nd). Total REE concentrations varied between 8.3 µg/kg and 1.1 mg/kg, with the highest individual mean concentrations (µg/kg) observed for Ce (11.7), La (6.0), and Sc (4.7). The lowest individual mean concentrations (µg/kg) were for Ho (0.16), Lu (0.066), and Tm (0.063). Multivariate analysis of REE profiles from 92 coffee samples collected in Serbia revealed clear distinctions between ground roasted and instant coffees, as well as between different surrogate blends. This study indicated that the determination of coffee’s geographical origin was not possible due to the diverse types, blends, and additives. However, differences in REE profiles suggest potential classification based on variety. REEs pose a negligible health risk to coffee consumers, with HI values ranging from 4.7 × 10−8 to 6.3 × 10−6 and TCR ranging from 2.6 × 10−14 to 3.5 × 10−12