Journal of Molecular and Engineering Materials

This study was aimed at evaluating the effect of E-glass fibers ($\approx$1.0mm long, $\mathit{ø}=0.017$mm with 1.0wt.% and 5.0wt.%) in two (Megacem^TM and GlassFill^TM) glass-ionomer cements (GIC) to enhance their mechanical properties. The six specimen groups were assigned to MCC, MC1, MC5, GFC, GF1 and GF5, and evaluated after 24h dry storage and 30 days water storage. The results showed considerable increase in surface roughness and the flexural strength values of both cements in both time intervals, whereas a statistically higher elastic modulus was observed in MC1 24h (15.3GPa) and 30 days groups (7.1GPa). On the contrary, no steady improvement in nano-hardness and yield strength were observed with the addition of chopped glass fibers. The SEM images suggest inadequate adhesion of the fibers to GIC matrix. Reinforcing GICs with short chopped E-glass fibers may not improve all the mechanical properties of GIC.

This study evaluated the effects of filling technique and light irradiation distance on the push-out bond strength of dual-cured (DC) and light-cured (LC) core materials to the root canal dentin. DC and LC core materials were filled with a bovine root canal post space of 8mm deep, and polymerized under two different filling procedures, i.e., an 8mm bulk filling (I) and two times of 4mm incremental filling (II), multiplying two different light irradiation distances (0 or 5mm) from top of the root canal. After 24h water storage, specimens were horizontally sectioned to obtain $1\pm 0.1$mm thick core/dentin slices, and five slices were obtained for each root. After the slicing process, push-out tests were performed. Among all groups, the highest bond strength was observed in DCI5 (13.7 $\pm$ 4.3MPa), whereas the lowest was observed in LCI0 ($10.3\pm 3.7$MPa). Consequently, the recommended curing procedure between DC and LC core materials differed. Combination of LC core material with incremental filling technique and of DC core material with bulk filling technique indicated higher bond strength. Higher bond strength was measured at a 5mm light irradiation distance for both LC and DC core materials.

This work presents an experimental study dedicated to the synthesis and characterization of pure and Ni-doped chromium (III) oxide thin films. Sol–gel thin films with doping rates of 3%, 6%, 9%, and 12% were deposited onto glass substrates by the dip-coating method at room temperature using Cr(NO₃)₃: 9H₂O as precursor. Using X-ray diffraction (XRD), infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), and impedance spectroscopy on solids, we noted that the films are polycrystalline with a grain size ranging from 11.2nm to 24.4nm, the synthesized materials are highly transparent in the visible light with more than 90% of transmittance and have an optical bandgap less than 3.0eV overall, and the equivalent circuit of the deposited films is a resistors and capacitors (RC) parallel circuit.

Vitamin C (L-ascorbic acid) has been widely used in dermatological and cosmetic formulations primarily as an antioxidant owing to its excellent electron-donating ability. This property also makes it highly reactive and therefore degradation is unavoidable in the presence of reactive species. Polymers have been used for encapsulation purposes as micelles vesicles or gels.^11–19 A water-soluble polymer, polyvinyl alcohol (PVA) has been investigated as one of the polymeric materials for encapsulation. In cosmetic formulations, PVA is used as emulsion stabilizer, forming protective films, viscosity increasing agent, or a binder. This study used PVA to encapsulate Vitamin C in an attempt to slow down the rate of degradation and therefore preserve the bioactivity of Vitamin C. PVA of varying molecular weights and concentrations were used and the PVA-Vitamin C solutions were subjected to different temperature over seven days. UV and NMR analyses were performed to support the study. It was shown that PVA of Mw 79.2kDa provided the best protection for Vitamin C. Based on the analysis, it was demonstrated that molecular weight (Mw) 9kDa did not provide optimal protection due to shorter chain length. PVA of Mw 130kDa was too big that the polymer prefers to form noncovalent bonds with each other instead of Vitamin C.