Browsing by Subject "spectral sensitivity"
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Item Luminescence studies of zinc borates activated with different concentrations of Ce and La under x-ray and electron excitation(Elsevier Ltd, 2017) Küçük N.; Ayvacikli M.; Akça S.; Yüksel M.; Guinea J.G.; Karabulut Y.; Canimoglu A.; Topaksu M.; Can N.Several ZnB2O4 powder samples having dopants concentrations of 0.1, 0.01, 0.04 wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL) techniques were used. Unique luminescence properties of Ce doped ZnB2O4 powder samples are reported for the first time. A new luminescence bands appearing in red part of the spectrum and having all the characteristics of Ce3+ were obtained from RL results. Changing the Ce and La concentration of 0.01–0.1 wt% leads to an increase in RL and CL intensities of Ce3+ and La3+ ions and also CL emission spectra of ZnB2O4 show gradual shift towards longer wavelength. When we compare the luminescence intensity of the samples it is seen that Ce doped ZnB2O4 has the highest intense whereas La doped ZnB2O4 has the lowest one. However, emission spectra of both Ce and La doped samples kept unchanged. © 2017 Elsevier LtdItem OP11: DEVELOPMENT OF DIFFERENT PRODUCT GROUPS IN THE CLEANING INDUSTRY WITH SYNTHESIZED NANOSILVER(De Gruyter Open Ltd, 2022) Merdol H.; Yildiz C.; Razlikli A.; Hemen C.Objective: Thanks to the rapid progress of science and technology, the functional properties of the raw materials in the formulations are considered as innovation at the beginning, but today it is a necessity. Silver, with its unique chemical and biological properties, has been used in many studies in the past, such as the disinfection of drinking water1, the prevention of eye infections, and the treatment of cholera and epilepsy in the 17th century. In addition, it has been observed that viruses can bind to - SH structures in proteins and inhibit these structures, thus preventing the reproduction of such micro- organisms. Materials-Method: Nano-sized colloidal silvers were synthesized using the “Turkevich” reduction method using trisodium citrate (C6H5O7Na3). Citrate was used both as a reducing agent and as a coating agent in the reaction. During the study, the synthesis of colloidal nanosilver, characterization studies and the creation of a liquid laundry detergent and disinfectant product selected from the cleaning product range will be carried out with the synthesized colloidal nanosilver. Results: The synthesized colloidal nanosilver structures were characterized by ICP-MS, UV-VIS Spectroscopy and SEM analysis. According to the results of the ICP-MS analysis, the synthesized colloidal nanosilver concentration was found to be 159.08 mg/L. According to the UV-VIS analysis result, the absorbance value was 0.9317, while the wavelength was around 448 nm. The SEM images taken showed that the synthesized particle was 40-50 nm in size. Conclusion: Colloidal nanosilver has been used successfully in 2 different product groups. After preparing liquid laundry detergent and disinfectant product groups containing peroxide, pH, viscosity, stability, microbial product analysis and SEM analyzes were performed. The SEM images taken showed that the colloidal nanosilver in the 2 products was 35-45 nm in size. The 3-month stability results of the product were evaluated as appropriate. In addition, it has been proven by accredited tests that the disinfectant product has antiviral activity. © 2022 De Gruyter. All rights reserved.Item A comparative study of type 1 neovascularization: Neovascular age-related macular degeneration versus pachychoroid neovasculopathy(SAGE Publications Ltd, 2022) Altinisik M.; Kurt E.; Sonmezer P.; Kayikcioglu O.; Ilker S.S.Purpose: This study aimed to compare type 1 choroidal neovascularization (CNV) characteristics in eyes with pachychoroid neovasculopathy (PNV) and neovascular age-related macular degeneration (nAMD) using optical coherence tomography angiography (OCTA). Methods: Treatment naive 23 eyes of 23 patients with PNV and 24 eyes of 24 patients with nAMD were evaluated. The height of pigment epithelial detachment (PED) and the central macular thickness were determined. OCTA sensitivity, CNV area, morphological patterns, and retinal superficial capillary plexus vessel density (SCP-VD) values were compared. The frequency of quiescent CNV, subretinal hyperreflective exudation (SHE), subretinal/intraretinal fluid, serous PED, double-layer sign (DLS), and pachyvessels were noted. Results: CNV was detected on OCTA in 83.3% of nAMD eyes and 91.3% of PNV eyes (p = 0.66). Indistinct pattern was more common (74% vs 50%) and the CNV area (mm2) was smaller in PNV (0.77 ± 0.54 vs 1.57 ± 1.43) but did not reach significant levels (p = 0.27 and 0.33 respectively). SCP-VD was similar between the groups (p = 0.38). Statistically significant differences were found between groups in age and subfoveal choroidal thickness (p < 0.05). DLS and pachyvessels were found to be more frequently in PNV (p < 0.05). However, both groups had similar rates of quiescent CNV, SHE, subretinal/intraretinal fluid, and serous PED (p > 0.05). Conclusion: Morphological features, area, and activation findings of type 1 CNV may play a limited role in differentiating nAMD and PNV cases. © The Author(s) 2021.Item Novel Tb³⁺-Doped LaAl₂B₄O₁₀ phosphors: Structural analysis, luminescent properties, and energy transfer mechanism(Elsevier Ltd, 2024) Kaynar U.H.; Aydin H.; Hakami J.; Altowyan A.S.; Coban M.B.; Ayvacikli M.; Canimoglu A.; Can N.This study explores the structural and luminescent properties of terbium (Tb³⁺)-doped lanthanum aluminium borate (LaAl₂B₄O₁₀, abbreviated as LAB) phosphors, a novel host lattice for Tb³⁺ doping. LAB:Tb³⁺ phosphors, with varying dopant concentrations, were synthesized using a microwave-assisted combustion synthesis approach and characterized using X-ray diffraction (XRD), Rietveld refinement, and photoluminescence spectroscopy at both room and low temperatures. The structural analysis confirmed the hexagonal crystal structure of LAB and revealed successful incorporation of Tb³⁺ ions without altering the fundamental lattice. Luminescence studies demonstrated that the LAB:Tb³⁺ phosphors show strong green emission primarily attributed to the 5D4→7F5 transition of Tb³⁺. The optimal doping concentration was determined to be 5 wt% Tb³⁺, which provided maximum luminescence efficiency. This concentration also allowed for a critical study of energy transfer mechanisms within the phosphor, revealing dipole-dipole interactions with a critical distance of 9.80 Å between Tb³⁺ ions. Additionally, the CIE chromaticity coordinates of LAB:0.05 Tb³⁺ were precisely determined to be (0.289, 0.4460), indicating the potential for high-quality green emission suitable for solid-state lighting and display technologies. This work not only demonstrates the potential of LAB:Tb3+ as a highly efficient green luminescent material, but also sheds light on the mechanisms responsible for energy transfer and concentration quenching. © 2024 Elsevier Ltd