In this study, the structural, thermal, and mechanical properties of nanocomposites obtained by adding zinc oxide (ZnO) nanoparticles (NPs), produced by phyto-mediated synthesis using Dianthus chinensis plant extract, to a PMMA-based photopolymer resin at different ratios (0.05%, 0.10%, 0.15%, 0.20%, and 0.25%, by weight) were evaluated. The prepared composite resins were produced in different test geometries using a DLP (digital light processing)-based 3D printer (Asiga Ultra). Following the structural characterization of ZnO nanoparticles, tensile, compressive, and flexural mechanical tests were performed on the resulting composites, as well as FTIR, TGA, DSC, and DMA analyses. The FTIR results showed that ZnO NPs were physically integrated into the matrix. TGA and DSC analyses revealed that the addition of ZnO NPs, particularly at an addition rate of 0.15%, increased thermal stability. DMA analyses showed an increase in storage modulus and glass transition temperature as the addition rate increased. In mechanical tests, the highest modulus of elasticity and maximum strength values were obtained at additive ratios of 0.10–0.15%. The highest tensile strength (55.31 MPa) and compressive strength (388.53 MPa) were obtained at ZnO contents of 0.10–0.15 wt%, while the maximum flexural strength reached 125.94 MPa at 0.15 wt% ZnO. In addition, the storage modulus increased from 1.469 × 10⁹ Pa for the control resin to 1.872 × 10⁹ Pa for the composite containing 0.15 wt% ZnO, indicating improved stiffness and thermomechanical stability. The stress–strain curves show that improvements in ductility and deformation capacity of the material are achieved at these additive ratios. The findings demonstrate that green-synthesized ZnO nanoparticles are an effective and sustainable additive material for improving the mechanical and thermal performance of DLP-based photopolymer dental resins.

Background: Overproduction of oxygen-related free radicals and inadequate antioxidant defense are critical in hypothyroidism, as they might lead to future life-threatening diseases. The objectives of this study were to compare serum levels of oxidative stress markers; total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), paraoxonase-1 (PON-1), and arylesterase (ARYL) in patients with subclinical hypothyroidism (SH) and overt hypothyroidism (OH) versus healthy controls in population of Kutahya city, Turkey. Materials & Methods: This cross-sectional study was conducted at Department of Biochemistry, Faculty of Medicine, Kutahya University of Health Sciences, Kutahya, Turkey, from July to December, 2016. Three study groups of 45 each were formed as healthy controls, patients with SH and OH. Serum levels of TOS, TAS, OSI, PON-1, and ARYL were five research variables with ratio scale, but skewed, so described by median and IQR with 95% Cl. Kruskal-Wallis and multiple comparison tests were used for hypotheses testing. Results: Serum levels of TOS and OSI were higher in SH group (p-values 0.032; <.0001; respectively) and OH group (p-values <.0001; <.0001, respectively) than healthy controls, while serum levels of TAS, PON-1 and ARYL were lower in SH group (p-values <.0001; <.0001; <.0001, respectively) and OH group (p-values <.0001; <.0001; <.0001, respectively) than control group. Conclusion: Our study showed that serum levels of TOS and OSI were higher in subclinical and overt hypothyroidism than in healthy controls; while serum levels of TAS, PON-1, and ARYL were lower in subclinical and overt hypothyroidism than in healthy controls.

Nanoteknoloji, malzemelerin nanometre ölçeğinde, özellikle 1 ila 100 nanometre aralığında tasarım ve manipülasyonuna odaklanan öncü bir araştırma alanıdır. Gümüş nanoparçacıkları, antiseptik özellikleri ile bilinir ve genellikle malzemelerin antibakteriyel etkinliğini artırmak amacı ile diş hekimliği gibi alanlarda kullanılır. Son zamanlarda, grafen bazlı malzemeler de antibakteriyel özellikleri nedeniyle önem kazanmıştır. Bu çalışma ile karabiber ekstraktı kullanılarak mikrodalga yöntemi ile sentezlenmiş gümüş nanoparçacıkları ile grafen yapılarının kombinasyonunun antibakteriyel ve antioksidan aktiviteleri incelenmiştir. Sentezlenen malzemeler, UV-Vis spektroskopisi, taramalı elektron mikroskobu (SEM) ve enerji dağıtıcı X-ışını spektroskopisi (EDS) gibi çeşitli analitik yöntemlerle karakterize edilmiştir. Grafen ve gümüş nanoparçacık kompozitlerinin antibakteriyel etkinliği, Staphylococcus aureus (S. aureus) üzerine agar well difüzyon yöntemi kullanılarak değerlendirilmiştir. Ayrıca, kompozitlerin serbest radikal süpürme aktiviteleri DPPH, FRAP ve ABTS testleri ile test edilmiştir. Sonuçlar, grafen oksit ve gümüş nanoparçacıklarının kombinasyonunun 14.40 mm ile en büyük inhibisyon alanını oluşturduğunu, antioksidan aktivitenin ise genel olarak gümüş nanoparçacıklar için grafen ve kompozit yapılara kıyasla daha üstün olduğunu göstermiştir. Bu sonuçlar, sentezlenen grafenin, biyosentezlenmiş gümüş nanoparçacıkları ile entegrasyonunun antibakteriyel aktiviteyi geliştirebileceği ve biyomedikal alanlarda kullanılabileceğini göstermektedir.