Background: The purpose of this study was to investigate the effect of different light curing modes on the polymerization shrinkage of a bulk-fill composite and to evaluate the impact of two layering techniques on the cuspal deflection. Methods: Nine different light curing modes were tested on bulk-fill composite samples in aluminum MOD cavities. Intensity, duration, and illumination distance were the factors that changed during the different curing modes. The digital image correlation method was used to visually represent the displacement of carbon particles on the materials’ surface caused by shrinkage along both the horizontal and vertical axes. For simulating cuspal deflection, a separate protocol was used, with a bulk and horizontal layering technique. Results: The results showed that the largest horizontal displacements were present in the soft start group (6.00 ± 0.82 µm) and in the X-tra power group (5.67 ± 1.21 µm). The smallest horizontal displacements were detected in normal curing modes (4.00 ± 1.58 µm; 4.00 ± 2.68 µm). The largest vertical displacements, at the bottom layer, were present in the normal curing mode group with a 20 s curing time (5.22 ± 1.56 µm), while the smallest vertical displacements were shown in the X-tra power group (2.89 ± 0.60 µm). The observed particle displacements showing the shrinkage of the composite were correlated with the curing mode. The bulk-fill group showed less cuspal deflection than the horizontal layering group did, but the difference was not statistically significant (p = 0.575). Conclusions: Within the limitations of this in vitro study, it can be concluded that lower intensities of curing lights (1200 mW/cm²) may perform better from the point of view of material shrinkage than high and extreme light intensities do. The pulse delay mode might be recommended in the case of bulk-fill materials. The number of layers did not significantly affect the cuspal deflection in the case of the studied composite.

Lapatinib (Lap) is a lypophilic drug frequently used in cancer treatment; however, due to its limited solubility and permeability, achieving therapeutic dose through oral administration proves to be a challenge. There are various methods for enhancing the solubility of Lap and other similar drugs, one being the preparation of amorphous solid dispersions (ASD). In this study, a Lap-loaded polyvinylpyrrolidone (PVP) fiber mat was created with centrifugal spinning from a PVP/Lap solution in dimethyl formamide and ethanol. The production rate was 12.2 g/h dry fibers, and the fibers had an average thickness of 2.55 ± 0.92 μm. In the differential scanning calorimetry (DSC) thermogram of the fiber mat, the melting peak of the crystalline Lap was not visible, suggesting that Lap was in an amorphous state. A dissolution study was carried out in 0.2 M phosphate buffer saline solution at 37 °C. UV spectrophotometry data indicated that in the sample containing the fiber mat, the Lap concentration was 332 μg/mL (66%) in 10 min, decreasing to 227 μg/mL by 45 min. Meanwhile the crystalline Lap formed a 30–40 μg/mL (6–8%) solution in 5 min, maintaining that concentration. We conclude that centrifugal spinning can be an effective and easy method to produce ASDs.

Fiber-based sorbent materials are an essential part of containing oil spills, thus preventing ecological damage. Poly(styrene-b-isobutylene-b-styrene) thermoplastic elastomer fibers were successfully produced by centrifugal spinning. Scanning electron microscopy revealed that the fibers were bead free and smooth-surfaced, with an average fiber diameter of 5.9 ± 2.3 μm. Contact angle measurements proved the highly hydrophobic (water contact angle of 126.8 ± 6.4°) and highly oleophilic nature of the fiber mat. The sorption and retention capacities of the fiber mat were tested for various oils and benchmarked against polypropylene as the industry standard and polystyrene, which is widely used in the literature. The oil uptake of the fiber mat showed a strong correlation with the viscosity of the oil, resulting in sorption capacities of 10.1 ± 0.8 g/g for sunflower oil, 19.9 ± 2.1 g/g for motor oil, and 23.8 ± 1.8 g/g for gear oil. Oil–water separation tests were also conducted, resulting in ~100% oil removal. The thermoplastic elastomer fiber mat outperformed the industry standard; however, the polystyrene fiber mat demonstrated the best oil sorption performance.

Fibrous structures are promising candidates for oil–water separation applications. In this study, we have produced poly(styrene-b-isobutylene-b-styrene) thermoplastic elastomeric fibers with the centrifugal spinning fiber production method. The optimal fiber production conditions were achieved when using a 25% w/w solution concentration in an 80/20 tetrahydrofuran/toluene (w/w) solvent system at 8000 rpm rotational speed. The produced fibers were bead-free and smooth-surfaced with a diameter of 3.68 µm. The produced fibers were highly hydrophobic and oleophilic, suggested by a water contact angle of 129° and the instantaneous absorption of the oil droplet. The oil absorption study showed fast absorption kinetics with 94% relative oil uptake after 1 min and a maximum of 16.5 g sunflower oil/g fiber. The results suggest that polyisobutylene-based thermoplastic elastomers could be promising alternatives in oil absorption applications.

Plastic spur gears have gained significant attention in the last couple of decades in all industries where rotational motion is involved. Plastic gears have the advantages of light weight, shock absorption, low operation noise levels, and functioning without lubrication. However, the manufacturing precision of gears and gear tooth profiles has a significant effect on the lifetime of the gears. The aim of this study was to investigate the effect of 3D printing (Fused Deposition Modeling) parameters on the precision of the tooth profile. To study the effect of layer thickness, printing speed, and infill parameters, the Box–Behnken experimental design was utilized. The results show that the mean profile deviation was 0.067 ± 0.02 mm, and the printing speed had a statistically significant effect on the precision of the tooth profile. Plastic 3D printing provides more design freedom; therefore, it is a promising technology for low production volumes and special geometry gear manufacturing.

Fiber-based sorbents are widely used and researched for oil spill treatment. The sorption capacity of natural and synthetic fibers ranges from poor to exceptional; however, the preparation of such fiber-based sorbents requires specialized equipment, and the reusability is still unresolved. This paper presents sorbents prepared for the first time by Fused Filament Fabrication 3D printing. The sorbents contain capillaries ranging from 1 to 6 mm that were created by depositing the filament in grid and rectilinear infill patterns. Sorption kinetics and maximum capillary rise were investigated for diesel, and 5W30 and 85W140 oils in the cases of PP, rPET, and PLA as sorbent materials. Capillary size influences sorption capacity and sorption kinetics, 0.7 g/g for 1 mm and 2.7 g/g for 4 mm, whereas at 10 s the relative capillary rise was 64.1% for 1 mm and 86.8% for 4 mm. Viscosity has a significant effect on the sorption kinetics. A special sorbent design is proposed to increase the sorption capacity to 5.26 g/g. Reusability was tested and the sorption capacity stayed constant over 10 cycles. Although the sorption capacity is lower compared to electrospun nanofibers, the oil release does not require any specialty equipment and it takes 7–8 s, making this type of sorbent highly desirable in practical applications.