Color stability, surface, and physicochemical properties of three-dimensional printed denture base resin reinforced with different nanofillers.

Various materials have been introduced for the three-dimensional (3D) printing of dentures. In this study, the color stability and surface and physicochemical properties of 3D-printed denture base resins with four types of nanofiller particles were evaluated. Al2O3, ZnO, CeZr, and SiO2 nanofillers were added to a 3D printable denture base-resin matrix and subjected to digital light processing. The specimens were immersed in Coke, coffee, black tea, or distilled water for 6 days. For the assessment of color differences, 6 samples were analyzed using a spectrophotometer. In a separate investigation, surface properties of 10 samples were examined, while a different set of 6 samples was used to analyze water sorption and solubility. All experimental groups exhibited higher color stability in Coke than the control group. However, the groups containing ZnO and CeZr had lower color stability in coffee and black tea than the control group. Moreover, they had agglomerated nanofillers and lower gloss than the control group. Compared with that of the control group, the contact angle of the CeZr group and microhardness of the ZnO group were not significantly different. Water sorption was higher in the Al2O3 group, whereas the solubility of the experimental and control groups was not statistically significant. The results demonstrated the significant effect of ZnO and CeZr nanofillers on the color stability of the dentures when exposed to discoloring beverages. These results will facilitate the development of fillers that enhance the resistance of 3D printed denture base resins to discoloration in the oral environment.

QUANTIFICATION OF THE KAERI'S MOVABLE NEUTRON IRRADIATOR BY USING A 6LiI(Eu) SCINTILLATOR.

There is no standardised on-site calibration system for performance testing and calibration of neutron area monitors although there is a mobile irradiation device as like a neutron howitzer. For this reason, neutron area monitors, which legally and periodically require calibration in Korea, are removed from the installation location and tested at the Korea Atomic Energy Research Institute (KAERI) or the Korea Research Institute of Standards and Science (KRISS). To test the possibility of an on-site performance calibration system, the KAERI manufactured a movable neutron irradiator. The movable neutron irradiator is composed of high-density polyethylene and has an overall size of 50 cm (L) × 50 cm (W) × 46 cm (H). In this study, the neutron fields generated by the movable neutron irradiator were quantified at distances of 80, 100, 120, and 140 cm from the centre of the source. Quantification was performed using the initially estimated neutron spectrum from the computer simulation, the count rate data measured using a 6LiI(Eu) scintillator combined with a Bonner sphere spectrometer (BSS), and the response function of the BSS. As a result of the quantification of the neutron field at each distance, the fractions of scattered neutrons to total neutron fluence were almost constant within 5%.

EVALUATION OF NEUTRON SCATTERING CORRECTION USING THE SEMI-EMPIRICAL METHOD AND THE SHADOW-CONE METHOD FOR THE NEUTRON FIELD OF THE KOREA ATOMIC ENERGY RESEARCH INSTITUTE.

When neutron survey metres are calibrated in neutron fields, the results for room- and air-scattered neutrons vary according to the distance from the source and the size, shape and construction of the neutron calibration room. ISO 8529-2 recommends four approaches for correcting these effects: the shadow-cone method, semi-empirical method, generalised fit method and reduced-fitting method. In this study, neutron scattering effects are evaluated and compared using the shadow-cone and semi-empirical methods for the neutron field of the Korea Atomic Energy Research Institute (KAERI). The neutron field is constructed using a 252Cf neutron source positioned in the centre of the neutron calibration room. To compare the neutron scattering effects using the two correction methods, measurements and simulations are performed using respectively KAERI's Bonner sphere spectrometer (BBS) and Monte Carlo N-Particle code at twenty different positions. Neutron spectra are measured by a europium-activated lithium iodide [6LiI(Eu)] scintillator in combination with the BBS. The calibration factors obtained using each methods show good agreement within 1.1%.

Robust optimization for the simultaneous enhancement of nitric oxide inhibition and reduction of hepatotoxicity from green tea catechins.

To provide a platform for evaluating significant interactions contributing to the enhanced physiological efficacy and reduced hepatotoxicity, we used a robust design to determine the optimal combination of six major green tea catechins, epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC), gallocatechin, and catechin. Based on the mixture design, 28 experiments were performed to inhibit nitric oxide (NO) in RAW 264.7 cells and hepatotoxicity in Chang liver cells. Significant candidates, EGCG, EC, gallocatechin and catechin, were selected after optimization. The combination showing simultaneous enhancement of NO inhibition and reduction of hepatotoxicity was EGCG and gallocatechin at a ratio of 0.65 to 0.35 by surface response methodology and desirability function, through which their co-treatment was validated. Here, we describe a platform for simultaneously determining the optimized combination of natural components exerting enhanced efficacy and reduced toxicity.

Sulforaphene Interferes with Human Breast Cancer Cell Migration and Invasion through Inhibition of Hedgehog Signaling.

Although inhibition of mammary tumorigenesis by isothiocyanates has been widely studied, little is known about the effects of sulforaphene on invasiveness of breast cancer. Here, sulforaphene significantly inhibited the migration and invasion of triple-negative SUM159 human breast cancer cells and suppressed the expression and activity of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9). The Hedgehog (Hh) pathway, as an upstream signaling modulator, was significantly suppressed by sulforaphene. In particular, ciliary localization of Gli1 and its nuclear translocation were blocked by sulforaphene in a time-dependent manner. Consistently, downregulation of Hh signaling by vismodegib and Gli1 knockdown reduced the cellular migration and invasion as well as the expression of MMP-2 and MMP-9. These results indicate that the suppression of Hh/Gli1 signaling by sulforaphene may reduce the MMP-2 and MMP-9 activities and cellular invasiveness of human breast cancer cells, suggesting the potential efficacy of sulforaphene against breast cancer invasion and metastasis.

Clinical characteristics and outcomes of varicella zoster virus infection in children with hematologic malignancies in the acyclovir era.

BACKGROUND: Although intravenous acyclovir therapy is recommended for varicella zoster virus (VZV) infection in immunocompromised children, the clinical characteristics and outcomes of VZV infection in the acyclovir era have rarely been reported. METHODS: The medical records of children diagnosed with varicella or herpes zoster virus, who had underlying hematologic malignancies, were retrospectively reviewed, and the clinical characteristics and outcomes of VZV infection were evaluated. RESULTS: Seventy-six episodes of VZV infection (herpes zoster in 57 and varicella in 19) were identified in 73 children. The median age of children with VZV infection was 11 years (range, 1-17), and 35 (46.1%) episodes occurred in boys. Acute lymphoblastic leukemia was the most common underlying malignancy (57.9%), and 90.8% of the episodes occurred during complete remission of the underlying malignancy. Acyclovir was administered for a median of 10 days (range, 4-97). Severe VZV infection occurred in 16 (21.1%) episodes. Although the finding was not statistically significant, a previous history of hematopoietic cell transplantation (HCT) appeared to be associated with the development of more severe episodes of herpes zoster (P=0.075). CONCLUSION: Clinical characteristics of VZV infection in immunocompromised children were not significantly different from those without it, and clinical outcomes improved after the introduction of acyclovir therapy. However, risk factors for severe VZV infection require further investigation in a larger population and a prospective setting.