Fatih Özkalaycı

Sample-level data preserving dependence among sequential tea infusions remain scarce. This secondary analysis examined a CC BY 4.0 dataset containing 34 black teas with three linked sequential infusions per sample. We reconstructed the cumulative element mass after consuming all three infusions versus discarding the first. The primary hazard index (HI) excluded Pb because no health-protective threshold can be established; Pb exposure and a legacy Pb-based HI were reported separately. At 10 g dry tea/day and 65 kg body weight, the median Pb-excluded HI decreased from 0.419 (IQR 0.258–0.497) to 0.260 (0.157–0.326), with a mean relative reduction of 37.1% (95% bootstrap CI 34.4–39.8%). No sample exceeded HI = 1, but this does not establish safety. When beverage volume was held at 80 mL, the mean HI reduction was only 5.7% (1.5–9.7%), showing that much of the apparent benefit reflected lower consumed volume. The total-As-based As HQ remained below one. Total-As cancer screening decreased by 35.9%; however, the proportion above 10⁻⁴ ranged from 0% to 64.7% across assumed inorganic-As fractions of 10–100%, demonstrating strong speciation dependence. Discarding the first infusion also reduced the estimated brewed yields of Cu, Se, and Zn by amounts equivalent to 2.4% of the adult Cu RDA, 2.5% of the Se RDA, and 0.4–0.5% of the Zn RDA; these estimates describe elemental yield in the beverage rather than absorbed nutrient intake. Overall, discarding the first infusion reduces estimated hazard indices primarily through decreased beverage volume rather than selective removal of toxic elements. Because extraction kinetics heavily depend on preparation techniques—such as traditional two-pot brewing—and regional tea chemistry, these findings cannot be directly extrapolated to Turkish teas. Instead, this study establishes a standardized exposure framework that highlights a critical knowledge gap and underscores the need for paired empirical studies evaluating local cultivars under authentic preparation practices.

Following the Chernobyl accident, Ordu province in Türkiye’s Eastern Black Sea region received significant 137Cs deposition. Mosses and lichens have been used as bioindicators at 50 sampling points in 1997, 2007, and again in 2025. This study presents the third measurement (2025) and calculates ecological half‑lives for the 2007–2025 period. Samples were collected from the same locations and species, and 137Cs activity was measured by HPGe gamma spectrometry. Detectable 137Cs was found in 14 of 30 moss sites (mean 10.1 Bq kg⁻¹) and 3 of 20 lichen sites (mean 5.2 Bq kg⁻¹). Ecological half‑lives for 2007–2025 averaged 4.4 years for mosses and 4.2 years for lichens, similar to values from 1997–2007. Nearly 39 years after Chernobyl, 137Cs remains detectable at very low levels. The consistent short ecological half‑life confirms that environmental removal continues to dominate over radioactive decay. This 28‑year dataset provides a robust baseline for long‑term radiocaesium monitoring.

In this study, 5, 10, and 15 wt% colemanite (Ca₂B₆O₁₁‐5H₂O) and 15 wt% Bi₂O₃ filled high‐density polyethylene (HDPE) composites were fabricated by conventional melt extrusion processing techniques in the form of a layered structure to absorb both neutron radiation and secondary radiation resulting from neutron‐induced reactions. In the layered structure, HDPE was used to slow down neutrons, while colemanite and Bi₂O₃ were used to trap thermal neutrons and secondary gamma radiation respectively. The properties of the colemanite/HDPE and Bi₂O₃/HDPE composites were investigated by scanning electron microscopy (SEM), x‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The mechanical properties (tensile and hardness) of the composites were also investigated. The results showed that the addition of colemanite and Bi₂O₃ particles did not significantly alter the thermal and mechanical properties of the HDPE composites. The total macroscopic cross‐section of the composites was determined using a ²³⁹Pu‐Be (α,n) neutron source, while their linear and mass attenuation coefficients were determined using a ¹³⁷Cs gamma‐ray source. The material with the best neutron absorption rate is 15 wt% colemanite‐filled HDPE (2.31 ± 003 cm⁻¹), while the best gamma‐absorbing material is 15 wt% Bi₂O₃ filled HDPE (0.114 cm⁻¹). The 15 wt% colemanite, 15 wt% Bi₂O₃ doped HDPE layered structure has 1.72 ± 0.05 cm⁻¹ macroscopic cross‐sections and 0.098 linear attenuation coefficient. The results show that filled colemanite HDPE composites improve neutron shielding properties and Bi₂O₃ filled HDPE composites provide good shielding performance for gamma rays.

In this study, 5, 10, and 15 wt% ulexite and 15 wt %Bi2O3 filled high density polyethylene (HDPE) composite materials were fabricated through conventional melt-extrusion processing techniques in the form of a layered structure in order to absorb both neutron radiations and the secondary radiations resulting from neutron radiation. In the layered structure, HDPE was used to slow down neutrons, while ulexite and Bi2O3 were used to capture thermal neutrons and secondary gamma radiations, respectively. The properties of ulexite/HDPE and Bi2O3/HDPE composites were investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA). The mechanical properties (tensile and hardness) of composite materials were also investigated. The results showed that the addition of ulexite and Bi2O3 particles does not change the thermal and mechanical properties of the HDPE composites significantly. Total macroscopic cross-section of the composites was determined using a 239Pu-Be (α,n) neutron source, while their linear and mass attenuation coefficients were determined using a 137Cs gamma-ray source. The results show that ulexite filled HDPE composites enhance neutron shielding property and Bi2O3 filled HDPE composites provide good shielding performance for gamma rays.

In this work, integral cross sections and rate constants of ground states of the Rg-NO+ (X1Σ+) system were calculated from quantum mechanical approach. The Rg separately defines the three inert gaseous of He, Ne and Ar elements. Equilibrium geometry values of the Rg-NO+ (X1Σ+) complexes were calculated employing the CCSD(T)-F12 method with cc-pVTZ-F12 basis set augmented with mid-bond functions. After using analytical forms of the potentials, vibrational frequencies and dissociation energies were calculated. The dissociation energy values of 196.6, 364.4 and 1045.0 cm-1 were found for He-NO+, Ne-NO+ and Ar-NO+ systems, respectively. Zero-point energy (ZPE) values of the systems were found to be 1240.4, 1251.6 and 1284.9 cm-1 for He-NO+, Ne-NO+ and Ar-NO+ systems, respectively. Differential cross sections and rate constants were found in a broad range of energy and temperature for He, Ne and Ar rare gaseous. The rank order of the magnitudes of the rotational transition rate coefficients was compared and it was found that they can differ slightly for a few temperatures. Integral cross sections and collision rate constants were compared to those of experimental and theoretical studies in literature and they were found to be well agreed.

This study ailm was to fabricate and investigate the gamma photon shielding efficiency of antimony (Sb) doped polymer resin composites. The orthophthalic unsaturated polyester resin (C₁₆O₇H₁₄) and antimony powder have been used as matrix and filler material, respectively. Gamma radiation shielding capacities of the polymer resin composites doped with 325 mesh sized-antimony particles from 5 to 20 wt% have been investigated. Experimental measurements of the samples have been obtained using an HPGe detector equipped with gamma spectrometer by 241 Am, 133 Ba, 57 Co, 22 Na, 137 Cs, 152 Eu, 54 Mn and 60 Co radioactive point sources varying from 59.5 to 1408.0 keV energies. To explore the gamma-ray attenuation features, linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective atomic number (Zeff), the radiation protection efficiency (RPE) were evaluated. According to the obtained results, it was found that Sb(20%) showed the superior radiation shielding capacity than the other samples. The measured data have been compared with those of WinXCOM, and they were found to be in a good agreement with each other.