Malzeme Bilimi ve Teknolojileri

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https://hdl.handle.net/20.500.12846/486

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Techno-economic analysis of grid-connected PV and second-life battery systems for net-zero energy houses
(2024) Özcan, Özgür; Duman, A. Can; Gönül, Ömer; Güler, Önder
Net-zero energy houses (ZEHs) rely on energy-efficient building design and the incorporation of distributed generation and battery energy storage units. Nevertheless, two primary concerns arise: high investment cost of these units and harmful environmental impact of batteries. Using second-life batteries can overcome these concerns by reducing the cost of photovoltaic (PV)- battery systems and mitigating the adverse environmental effects of battery supply chain. Therefore, this study examines the techno-economic feasibility of utilizing second-life batteries for PV storage in grid-connected ZEHs in two provinces (Antalya and Istanbul) of Türkiye. First, two ZEHs with air-to-water heat pumps are designed using BEopt software. Next, the optimal PVbattery capacity in the ZEHs is determined using HOMER Grid software. Finally, the economic feasibility of using three types of batteries (new lead acid, new Li-ion, second-life Li-ion) in ZEHs is compared. The optimal design for a typical ZEH comprises a 5.92 kW PV and an 8.96 kWh second-life Li-ion battery in Istanbul (northern Türkiye), yielding an NPV of $10,906, and a 7.54 kW PV and an 11.52 kWh second-life Li-ion battery in Antalya (southern Türkiye), yielding an NPV of $16,402. The results indicate that using second-life Li-ion increases the NPV of PV-battery systems by 15 % in Istanbul and by 21 % in Antalya. The feasible system configuration categories for Türkiye’s economic and climatic conditions are ranked as: PV-second-life Li-ion > PV-no battery ? PV-new Li-ion > PV-new lead acid. Incentivizing the use of second-life batteries due to their environmental contribution could result in an even higher NPV increase.
In vitro bioactivity of laser surface-treated Ti6Al4V alloy
(Springer, 2019) Yoruç, Afife Binnaz Hazar; Keleşoğlu, Ergün; Ekşioğlu Yıldız, Harika
The effects of lasing parameters on the precipitation of hydroxyapatite (HA) on the commercial Ti6Al4Valloy in simulated body fluid (SBF) were investigated. Ti6Al4V plates were polished and ultrasonically cleaned in acetone and ethyl alcohol, respectively. The specimen surfaces were treated with Er:YAG laser using super short pulse (SSP, 50 ?s) and very short pulse (VSP, 100 ?s) modes. Surface roughness was measured before and after laser treatment. The specimens were immersed in simulated body fluid (SBF) for 1, 3, and 7 days and, then the amount of Ca and P precipitation on specimens was determined using SEM/ EDS analysis. An average roughness varying between 0.19 and 0.81 ?m in surface roughness was detected in all laser-treated specimens depending on the lasing parameters. The highest surface roughness and Ca precipitation were found in VSP group (20 Hz and 5 W). Laser treatment of specimen surfaces has dramatically increased the HA precipitation due to the increasing surface roughness. It is also concluded that the immersion time was effective on the HA precipitation as well.
Effects of different bonding agents on the shear bond strength between monolithic zirconia and indirect composite
(2023) Mergen, Elif Saracoğlu; Cömert, Zekeriya Yaşar; İşsever, Dilara Şeyma Alpkılıç; Keleşoğlu, Ergün; Değer, Sabire İşler
Purpose: To investigate the effects of different bonding agents and application of glaze on the shear bond strength (SBS) between monolithic zirconia (MZ) and indirect composite (IC). Materials and Methods: Five different bonding agents (G-Premio Bond [GP]; Tokuyama Universal Bond [TU]; Signum Zirconia bond [SZ]; Clearfil Ceramic Primer Plus [CCP]; Z-Prime Plus [ZP]) were applied to a total of 200 MZ disk-shaped specimens (n = 100 glazed and 100 nonglazed). Half of the specimens then underwent thermocycling and the other half no thermocycling (n = 10 specimens each subgroup). The experimental setup was prepared as two pieces according to the ISO TR 11405 standards. Specimens embedded in acrylic resin were placed into the experimental setup and a universal testing machine at a crosshead speed of 0.5 mm/minute. Mann-Whitney U test and Kruskal-Wallis test were used for statistical analyses. Bonferroni correction was then performed, and test results with P < .05 were accepted as statistically significant. Results: The application of glaze significantly enhanced SBS when ZP or CCP was used; however, it did not have any significant effect when GP, TU, or SZ were used. Thermocycling significantly decreased the SBS in all bonding agent groups except GP specimens with glaze (P = .16). The highest SBS in all conditions was noted when GP and TU were used. Conclusions: These findings suggest that the bonding agents GP and TU may be recommended for better bonding between MZ and IC.
Does intramedullary elastic nail augmentation increase resistance to bending stress in plate fixation of long bones? A biomechanical study on lamb cadaveric femurs
(2023) Eren, E.; Keleşoğlu, Ergün; Özdemir, Jülide Hazal; Büyükdoğan, Halil; Ertürk, Cemil
[Özet yok]
Production of Y2O3 coated AL2O3 reinforced aluminium matrix composites and the coating of interface effects over wettability properties
(2024) Altuner, Serdar; Keleşoğlu, Ergün
Usage of Aluminium metal matrix komposites have been increased in automotive and areospace industry due to physical and mechanical properties of these. Requested properties have been obtained depends on particle’s different particle size and amount is added into matris. In this study, 5-10-15 and 20 % Al2O3 particle has been used as reinforcement. The wettability of Al2O3 is weak by molten aluminium. Weak bond force between aluminium and Al2O3 effects final properties of composite and decrease mechanical properties of it. In order to cope with this problem, Al2O3 powder was coated by Y2O3 and then it was added into aluminium. The aim of this study is the improvement of wettability using by Y2O3 coated Al2O3 particle reinforced aluminium matrix composites produced by squeze casting method so that mechanical properties will be enhanced. Produced composite’s density, hardness and wear behaviour is examined and analysed SEM microstructle. It was aware that during increasing reinforced volume, hardness of MMC was increased,coefficient of friction was decreased so wear resistance was improved.
Effect of equal-channel angular pressing on ordering kinetics and twinning in an 18-carat AuCuAg alloy
(2023) Elibol, Çağatay; Illgen, Christian; Colas, Damien; Bohne, Benjamin; Fritsch, Sebastian; Dietrich, Dagmar
The ability to modify microstructural features and the resulting properties of red gold provides an attractive potential for applications in electronics, dental devices or jewelry. In this study, the effect of severe plastic deformation by equal-channel angular pressing (ECAP) on microstructural evolution in an 18-carat AuCuAg alloy, and on the ordering kinetics during subsequent aging, is investigated. Differential scanning calorimetry measurements show that the ordering process is significantly influenced by a plastically deformed microstructure and lattice defects introduced by one or two passes of ECAP. Electron backscatter diffraction and transmission electron microscopy demonstrate that the microstructural evolution during ordering, accompanied by the formation of an L10 superstructure, substantially depends on the thermo-(mechanical) history of the material: While the undeformed material clearly shows a hierarchical structure of twins on different length scales, only a few nanotwins are observed within the strongly deformed microstructures after ECAP. Moreover, after ECAP, static recrystallization is considerably suppressed during long-term annealing at elevated temperatures close to the phase transition temperature. These results clearly highlight the potential of ECAP in combination with heat treatments for microstructural optimization of AuCuAg alloys and their applications.
Challenges with atomically dispersed supported metal catalysts: Controllingperformance, improving stability, and enhancing metal loading
(Elsevier, 2023) Kurtoğlu-Öztulum, Samira Fatma; Uzun, Alper
Comprehensive Inorganic Chemistry III, a ten-volume reference work, is intended to cover fundamental principles, recent discoveries, and significant applications of elements and their compounds. Authored by renowned experts in the field and edited by a world-class editorial board, each chapter provides a thorough and in-depth overview of the topic covered, featuring resources which will be useful to students, researchers, faculty as well as those in the industry. Comprehensive Inorganic Chemistry III focuses on main group chemistry, biological inorganic chemistry, solid state and materials chemistry, catalysis, and new developments in electrochemistry and photochemistry, as well as NMR and diffraction methods for studying inorganic compounds. The work expands on our 2013 work Comprehensive Inorganic Chemistry II while also adding new volumes on cutting-edge research areas and techniques for studying inorganic compounds. Researchers seeking background information on a specific problem involving the synthesis of inorganic compounds, as well as applications for numerous elements from the periodic table, and their compounds, will be able to rely on and refer to this authoritative scientific resource time and again. This new work complements Comprehensive Coordination Chemistry III (2021) and Comprehensive Organometallic Chemistry IV (2022), constituting a formidable trio of reference resources covering the whole of modern inorganic chemistry.
Reduced graphene aerogel-supported Ir(C2H4)2 complexes at an exceptional Ir loading of 23.8 wt%: Confirming site-isolation by combining XAS and STEM
(Turkish Catalysis Society, 2023) Kurtoğlu-Öztulum, Samira Fatma; Yalçın, Kaan; Zhao, Yuxin; Ünal, Uğur; Uzun, Alper
Atomically dispersed supported metal catalysts offer significant opportunities when compared to conventional analogues. They provide maximum utilization of expensive noble metals, interesting catalytic properties, and understanding of structure-catalytic activity relationships [1]. These novel catalysts consist of supported single metal atoms bonded to ligands as well as clusters incorporating only a few metal atoms. However, they face certain challenges hindering their industrial use. The main challenges are their limited stability and limited metal loading. Typical metal loadings are limited with <1 wt.%. The support material is crucial in overcoming these challenges. Here, we used reduced graphene aerogel (rGA) as a novel support for Ir(C2H4)2 complexes and assessed the maximum metal loading we can reach. Thanks to the outstanding properties of rGA, such as excellent electronic properties, high porosity and surface area, and multiple bonding sites for Ir atoms, an exceptionally high Ir loading of 23.8 wt% was obtained. Aberration-corrected scanning transmission electron microscopy (STEM) images and X-ray absorption spectroscopy (XAS) data confirmed the site-isolation of Ir atoms at this exceptional loading. Figure 1 shows the STEM images of rGA-supported Ir(C2H4)2 complexes at an Ir loading of 23.8 wt%, a challenging sample because of the three-dimensional multilayer wrinkled-sheet structure of rGA. Besides, these images are one of the first atomic resolution images obtained on a Hitachi HF5000 Cs-corrected cold FEG STEM in Koç University. Results demonstrate the potential of rGA as a superior support material for expensive noble metal complexes to reach exceptional loadings.
Characterization of site-isolated iridium atoms supported on reduced graphene aerogel at an exceptional Ir loading of 23.8 wt% with synchrotron and electron microscopy techniques
(2023) Kurtoğlu-Öztulum, Samira Fatma; Kaan, Yalçın; Yuxin, Zhao; Uğur, Ünal; Alper, Uzun
Atomically dispersed supported metal catalysts provide substantial advantages when compared to their traditional counterparts. They offer 100% dispersion of expensive noble metals, exhibit intriguing catalytic properties, and provide insights into the relationship between structure and catalytic activity [1]. However, there are several challenges these novel class of catalysts are facing, such as their limited stability in reaction environment and limited metal loadings (typically below 1 wt%). To overcome these issues, we have used a novel and promising support, reduced graphene aerogel (rGA), consisting of numerous bonding sites for Ir, having a significantly high surface area (>700 m2 /g), and great electronic properties. Thanks to these outstanding features of rGA, we achieved an exceptional Ir loading of 23.8 wt%. The presence of individual Ir atoms at such high loading on the surface of rGA was confirmed by combining atomic-resolution images obtained using a Hitachi HF5000 Cs-corrected cold FEG aberrationcorrected scanning transmission electron microscope and X-ray absorption spectroscopy data. These findings highlight rGA's potential as an exceptional support material for expensive noble metal complexes to achieve extraordinary loadings in atomically dispersed supported metal catalysts.
Active sites and their individual turnover frequencies for ethylene hydrogenation on reduced graphene aerogel
(American Chemical Society, 2024) Kurtoğlu-Öztulum, Samira Fatma; Yalçın, Kaan; Saraç Öztun, F. Eylül; Kanat, Gizem Hasibe; Ünal, Uğur; Uzun, Alper
Graphene aerogel (GA) was reduced at various temperatures to prepare a series of reduced graphene aerogels (rGAs) with different surface characteristics. Detailed characterization demonstrated that an increase in the thermal reduction temperature leads to an increase in surface area accompanied by an increase in surface density of defect sites formed by the removal of the oxygen-containing functional groups. rGA samples were then tested for ethylene hydrogenation under identical conditions. A comparison of catalytic performances of each catalyst demonstrated that the rGA sample prepared by reduction in Ar at 900 °C (rGA-900) provides the highest performance compared with others prepared at lower temperatures. Next, we analyzed the per-gram activity of each catalyst as a sum of individual contributions from different defect sites quantified by Raman spectroscopy and CHNS-O analysis to determine the individual turnover frequencies (TOFs) of each active site. This analysis identified polyene-like structures and interstitial defects associated with amorphous sp2 bonded carbon atoms as the dominant active sites responsible for hydrogenation. A comparison of their TOFs further indicated that the polyene-like structures provide approximately ten times higher TOF compared to those associated with the amorphous carbon defects. These results, identifying the dominant active centers and quantifying their corresponding TOFs, provide opportunities toward the rational design of GA-based carbocatalysts.
Atomically dispersed zeolite-supported rhodium complex: Selective and stable catalyst for acetylene semi-hydrogenation
(Elsevier, 2024) Kurtoğlu-Öztulum, Samira Fatma; Zhao, Yuxin; Hoffman, Adam S.; Uzun, Alper; Demircan, Oktay; Yordanli, Melisa Su; Hong, Jiyun; Perez-Aguilar, Jorge E.; Saltuk, Aylin; Akgül, Deniz; Ateşin, Tülay A.; Aviyente, Viktorya; Gates, Bruce C.; Bare, Simon R.
Supported rhodium catalysts are known to be unselective for semi-hydrogenation reactions. Here, by tuning the electronic structure of supported mononuclear rhodium sites determined by the metal nuclearity and the electron-donor properties of the support, we report that atomically dispersed HY zeolite-supported rhodium with reactive acetylene ligands affords a stable ethylene selectivity > 90 % for acetylene semi-hydrogenation at 373 K and atmospheric pressure, even when ethylene is present in a large excess over acetylene. Infrared and X-ray absorption spectra and measurements of rates of the catalytic reaction complemented with calculations at the level of density functional theory show how the catalyst performance depends on the electronic structure of the rhodium, influenced by the support as a ligand that is a weak electron donor.
Effect of repolishing on the surface roughness and color stability of air-abraded resin composites
(Original ArticleInternational Dental Research, 2022) Sağır, Kadir; Altaş, Nurcan; Aydınoğlu, Aydın; Çil, Burcu Gözeteci; Keleşoğlu, Ergün; Yoruç, Afife Binnaz Hazar
Aim:Air powder polishing (APP) can cause roughness on composite surfaces, and consequently the color change that occurs over time affects the aesthetic negatively. Here, we aim to investigate the effect of repolishing on the roughness and discoloration of resin composites after APP to avoid its negative effects for the first time.Methodology:A total of 39 composite discs were randomly allocated into three groups: Group I: Control (n = 13), Group II: Air Powder Polished (n = 13), and Group III: Air Powder Polished + Re-polished (n = 13). Color and surface roughness of the discs were measured before and after immersion in coffee for 1 week. Color was measured using a colorimeter (CR-400, Konica Minolta, Osaka, Japan), and roughness was measured using a surface roughness analyzer (SJ-400, Mitutoyo, Japan).Results:All specimens in the groups, except those in Group III, showed significant changes in roughness, and all materials showed significant color changes after immersion in the coffee relative to the baseline. There was no statistically significant difference between the groups in terms of roughness and color.Conclusion:In this study, we showed that repolishing after APP does not significantly improve the color stability and roughness of the composite restorations.
Influence of different irrigation solutions on the push-out bond strength of fiber posts to root dentin and root canal dentin microhardness: methodological study
(Türkiye Klinikleri Diş Hekimliği Bilimleri Dergisi, 2023) Hepşenoğlu, Yelda Erdem; Erşahan, Şeyda; Yılmaz, Burcu; Aydınoğlu, Aysu; Sağır, Kadir; Yoruç, Afife Binnaz Hazar
This study aimed to compare the effect of sodium hypochlorite (NaOCl), chlorhexidine (CHX), ethylene diamine tetra acetic acid (EDTA) and etidronic acid (HEBP) solutions and their combinations on a push-out bond strength of fiber posts to root canal dentin and on root dentin microhardness. Material and Methods: Sixty human maxillary central incisors were sectioned below the cementoenamel junction, the roots were endodontically treated and were divided into 6 groups (n=10) according to the final irrigation protocol: (1) Distilled water, (2) CHX, (3) HEBP-NaOCl combination, (4) HEBP, (5) 2.5 % NaOCl, (6) 17% EDTA. The fiber posts were then cemented with self-etching resin cement. Bonded specimens were cut (1-mm-thick), the first slice of the coronal 3rd was used for dentin microhardness analysis, and other slices were used for the push-out bond strength test. The data were statistically analyzed by using Shapiro-Wilk, Oneway ANOVA, and the Games-Howell test. Results: The lowest microhardness was observed in HEBP-NaOCl and NaOCl (p<0.05). CHX, HEBP, and EDTA resulted in less reduction in microhardness as compared to other groups (p<0.05). HEBP-NaOCl and NaOCl showed significantly higher mean bond strength to root dentin in the cervical thirds than in other groups (p<0.05). Conclusion: With regard to the push-out bond strength of the fiber post to dentin, NaOCl and HEBP-NaOCl increased bond strength compared to other groups. NaOCl and HEBP-NaOCl have lower microhardness of dentin. Compared to HEBP, EDTA increases microhardness and does not make a significant difference in push-out bond strength. Therefore, it is recommended to use HEBP alone.
A comparison of the effects of incremental and snowplow techniques on the mechanical properties of composite restorations
(Australian Dental Journal, 2023) Ölçer, Yeşim Su; Sağır, Kadir; Erşahan, Şeyda; Üşümez, Aslıhan; Hepşenoğlu, Yelda Erdem
Background:Glass fibre-reinforced composite (GFRC) has the potential to enhance the mechanical properties of resin-based restorations. Nevertheless, the application technique can influence the cervical margin porosity, potentially reduc-ing the mechanical strength of restorations.Methods:In anin vitrosetup, mould specimens underwent six different treatments to assess the effects of snowplow andincremental curing techniques on the properties of GFRC (EverX) and universal resin composite (Filtek). Mechanicalproperties, namely flexural strength (FS), compressive strength (CS) and Vickers hardness (VH), were evaluated followingISO 4049 standards. Data interpretation utilized the Kruskal–Wallis tests.Results:No significant difference emerged across groups for FS. CS in the snowplow method with lesser EverX thickness(SnPl_1) was comparable with only EverX and Filtek (P>0.05). The CS was reduced in the snowplow technique withgreater EverX thickness (SnPl_2) (P<0.05) and further decreased with the incremental method (P<0.001). VH resultsshowed that EverX Posterior was consistently softer than Filtek, with specific patterns of hardness variations among dif-ferent application methods.Conclusions:Applying EverX and Filtek using the snowplow technique delivers superior CS and VH for restorations incontrast to the incremental method. Utilizing the snowplow approach in high-stress areas can make restorations morefracture-resistant.
Nanoflower hydroxyapatite's effect on the properties of resin-based dental composite
(Journal of Applied Polymer Science, 2024) Sağır, Kadir; Aydınoğlu, Aysu; Yoruç, Afife Binnaz Hazar
To investigate the reinforcing effect of nanoflower-like hydroxyapatite (NFHA) inresin-based dental composites, we synthesized a novel NFHA using microwaveirradiation (MW), hydrothermal treatment (HT), and sonochemical synthesis (SS).Silanized NFHA was then used as the reinforcing filler in dental resin composites.We characterized the structure and morphology of various HA nanostructuresusing x-ray diffraction, scanning electron microscope, and TEM. The mechanicalperformance of dental resin compositesreinforced with silanized NFHA was mea-sured using a universal testing machine. Spherical HA, synthesized throughchemical precipitation (CP), served as the control group. One-way analysis of vari-ance was employed for the statistical analysis of the acquired data. The resultsdemonstrate that the nanoflower morphology significantly was improved mechan-ical and physical properties. After conducting trials, the NFHA synthesized usingMW and HT showed a substantial enhancement in mechanical and physicalproperties compared to the other structures. Therefore, it can be concluded thatNFHA can serve as a novel reinforcing HA filler, providing regenerative proper-ties to resin composites with sufficient mechanical strength.
SARS-CoV-2 main protease targeting potent fluorescent inhibitors : repurposing thioxanthones
(TÜBİTAK Academic Journals, 2023) Batıbay, Gönül Saadet; Metin, Eyüp
The coronavirus disease, COVID-19, is the major focus of the whole world due to insufficient treatment options. It has spread all around the world and is responsible for the death of numerous human beings. The future consequences for the disease survivors are still unknown. Hence, all contributions to understand the disease and effectively inhibit the effects of the disease have great importance. In this study, different thioxanthone based molecules, which are known to be fluorescent compounds, were selectively chosen to study if they can inhibit the main protease of SARS-CoV-2 using various computational tools. All candidate ligands were optimized, molecular docking and adsorption, distribution, metabolism, excretion, and toxicity (ADMET) studies were conducted and subsequently, some were subjected to 100 ns molecular dynamics simulations in conjunction with the known antiviral drugs, favipiravir, and hydroxychlo-roquine. It was found that different functional groups containing thioxanthone based molecules are capable of different intermolecular interactions. Even though most of the studied ligands showed stable interactions with the main protease, para- oxygen-di-acetic acid functional group containing thioxanthone was found to be a more effective inhibitor due to the higher number of intermolecular interactions and higher stability during the simulations.
DNA groove binder and significant cytotoxic activity on human colon cancer cells: Potential of a dimeric zinc (II) phthalocyanine derivative
(2023) Batıbay, Gönül S.; Karaoğlan, Gülnur Keser; Köse, Gülşah Gümrükçü; Kazancıoğlu, Elif Özçelik; Metin, Eyüp; Kalındemirtaş, Ferdane Danışman; Kuruca, Serap Erdem; Arsu, Nergis
The interaction of a multi-component system consisting of benzene-1,4-diyldimethanimine-bridged dimeric zinc-phthalocyanine groups (4OMPCZ) with calf thymus DNA (ct-DNA) was investigated using UV-Vis absorption, fluorescence emission spectroscopy methods, and viscosity measurements. The binding constant, Kb, which is an important parameter to gain information about the binding mode, was found as 9.7 x 107 M-1 from the UV-Vis absorption studies. Another important spectrophotometric tool is competitive displacement assays with Ethidium bromide and Hoechst 33342. Through this experiment, a higher KSV value was obtained with Hoechst for the phthalocyanine derivative, 4OMPCZ, and the ct-DNA complex than with ethidium bromide. Additionally, mo-lecular docking studies were conducted to calculate the theoretical binding constant and visualize the in-teractions of 4OMPCZ with a model DNA. According to docking results, although the interactions are mainly located in the major groove of the DNA helix, due to the wrapping, these interactions can also be extended to the minor groove of the DNA. Spectrophotometric, molecular docking, and viscosity studies revealed that the interaction of 4OMPCZ with DNA is likely to be via the major and minor grooves. The in vitro cytotoxic activity of 4OMPCZ was evaluated by MTT assay on human colon cancer cells (HT29) after 72 h of treatment. 4OMPCZ indicated significant cytotoxic activity when stimulated with UV light compared to the standard chemotherapy drugs, fluorouracil (5-FU), and cisplatin on HT29 colon cancer cells. The IC50 value of 4OMPCZ displayed considerably lower concentrations compared to the standard drugs, 5-FU, and cisplatin.
Synthesis of one-component type II dithioxanthone-disulfide photoinitiator and investigation of photophysical and photochemical properties
(Elsevier, 2021) Koyuncu, Umut; Metin, Eyüp; Öcal, Nüket; Arsu, Nergis
Herein, we report the successful synthesis of dithioxanthone-disulfide [TX-S-](2) as a new one-component type II photoinitiator. Photophysical properties of [TX-S-](2) in terms of fluorescence and phosphorescence properties were investigated and low fluorescence quantum yield was observed, which indicates an efficient intersystem crossing (ISC) that leads to the generation of triplet states. Efficiently produced initiating thiyl radicals from the triplet states lead to polymerization of methyl methacrylate with [TX-S-](2) in air atmosphere. To elucidate the initiating mechanism, a disulfide exchange reaction was performed in the presence of diphenyl disulfide [Ph-S-](2), and the obtained results from HQ-TOF confirmed that [TX-S-](2) disulfide bond cleavage occurs upon irradiation with light. Initiating mechanism of [TX-S-](2) revealed the potential usage of this compound as a self-healing agent due to the efficient cleavage of disulfide bonds. In conjunction with the experimental studies series of Density Functional Theory calculations were performed and various photophysical and photochemical properties, including HOMO and LUMO, were computationally calculated and visualized.
In–situ formation of self-assembled Ag nanoclusters on ct-DNA in the presence of 2-mercaptothioxanthone by using UV–vis light irradiation
(Elsevier, 2018) Metin, Eyüp; Batıbay, Gönül S.; Arsu, Nergis
Self-assembled silver nanoparticles (Ag NPs) on calf thymus DNA (ct-DNA) chains were synthesized in the presence of 2-mercaptothioxanthone (TX-SH) by use of UV irradiation technique. Thioxanthone itself and its derivatives show interesting photochemical and biological properties. The formation of Ag NPs on the ct-DNA was achieved with and without TX-SH as a thioxanthone derivative photoinitiator which played a photoreducing role for the formation of Ag NPs. The photoreducing reaction of Ag ions to Ag NPs was followed by UV-vis absorption spectroscopy. A new band was observed at 428 nm which was a good sign of the surface plasmon resonance (SPR) of Ag NPs. Fluorescence quenching was effectively observed depending on the irradiation time of the solution, possibly as a result of Ag NPs size. Particle size analysis and Scanning Electron Microscopy (SEM) imaging confirmed the size of the formed Ag NPs and silver nanoclusters (Ag NCs) effectively. In this study, we report for the first time the formation of self-assembled Ag NPs on ct-DNA in the presence of 2-mercaptothioxanthone by photoirradiation technique. TX-SH played two important roles; photoreducing and photostabilizing agent for the formation of Ag NCs on ct-DNA. Fluorophore character of synthesized Ag NPs on DNA may help to develop new techniques for biological and medical aspects. (C) 2017 Elsevier B.V. All rights reserved.
Morphological, microstructural and photocatalytic characterization of undoped and Ni, Co doped Fe2O3 particles synthesized by sonochemical method
(Scientific & Technical Research Council Turkey-TUBITAK, 2022) Kaya, Elif Emil; Evren, Burak; Erdöl, Zeynep; Ekinci, Duygu; İpekoğlu, Mehmet; Özenler, Sibel
In this study, an abundant and eco-friendly photocatalytic material, Fe2O3 particles were synthesized by sonochemical method. Morphological and microstructural investigations of synthesized undoped and Ni, Co-doped Fe2O3 particles were performed. The effect of particle morphology and microstructure on its photocatalytic performance was further investigated. Comparative studies for evaluating particle crystallite sizes were conducted by Williamson-Hall (W-H) method and modified Debye-Scherrer (MDS). Crystallite sizes and lattice strains of Fe2O3 induced by process parameters were calculated by W-H method based on uniform deformation model (UDM). The crystallite sizes of the synthesized powders were calculated in the range of 200 nm and 76 nm by Williamson-Hall analysis. In addition to structural investigation, dislocation density of the synthesized particles was calculated by Williamson-Smallman relation. Afterwards, photocatalytic performance of Fe2O3 particles was investigated in detail. The photodegradation of methylene blue solutions in the presence of light in 20 min with samples 3,4, and 5 in 20 min were 0.937, 0.896, and 0.855, respectively. Moreover, the photodegradation of methylene blue solution with sample 5 for 15, 30, and 45 min were 0.9, 0.828, and 0.757, respectively. A photocatalytic activity of 24.25% has been observed under optimum conditions for the time interval of 45 min.

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