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Search Results (9)

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Authors = Burcu Özkan ORCID = 0000-0002-3477-5643

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15 pages, 421 KiB  
Article
Fermentation of Sainfoin Seed Flour with Saccharomyces boulardii: Effects on Total Dietary Fiber, Anti-Nutrients, Antimicrobial Activity, and Bioaccessibility of Bioactive Compounds
by Havva Polat Kaya, Burcu Kaya, Necati Barış Tuncel, Gulay Ozkan, Esra Capanoglu, Seedhabadee Ganeshan and Mehmet Caglar Tulbek
Microorganisms 2025, 13(6), 1421; https://doi.org/10.3390/microorganisms13061421 - 18 Jun 2025
Viewed by 415
Abstract
This study investigates the effects of fermentation on sainfoin seed flour using Saccharomyces boulardii for total dietary fiber (TDF) content, anti-nutritional profiles (including phytates, tannins, saponins, and trypsin inhibitors), and bioactive compounds. It also focused on assessing the in vitro availability of phenolic [...] Read more.
This study investigates the effects of fermentation on sainfoin seed flour using Saccharomyces boulardii for total dietary fiber (TDF) content, anti-nutritional profiles (including phytates, tannins, saponins, and trypsin inhibitors), and bioactive compounds. It also focused on assessing the in vitro availability of phenolic compounds, antioxidant potential, and anti-nutrient compounds after gastrointestinal digestion. Four treatment groups were designed: a non-fermented control group, and flour samples fermented with S. boulardii CNCM I-745 for 24, 48, and 72 h. All fermentations were carried out at 30 °C. The effects of fermentation and the analysis results were statistically evaluated at the significance level of p < 0.05, and significant differences were detected. Fermentation significantly increased soluble dietary fiber (from 3.32% to 4.43%) and reduced anti-nutritional factors, including phytates (by 18%), tannin (by 19%), and trypsin inhibitor activity (TIA) (by 79%). However, saponin content increased by 21% after 72 h of fermentation. Tannin levels of non-fermented and fermented sainfoin flour decreased dramatically after in vitro digestion. Moreover, it was concluded that the bioaccessibility of phytic acid significantly increased through fermentation, while that of tannins declined. Antimicrobial activity against Escherichia coli ATCC 25922 improved after fermentation, while the antioxidant capacity was enhanced post-digestion. In addition, the highest phenolic content (612 mg GAE/100 g) and antioxidant capacity (1745 mg TE/100 g by CUPRAC assay and 1127 mg TE/100 g by DPPH assay) were determined in fermented sainfoin seed flour at 72 h after gastrointestinal digestion. Full article
(This article belongs to the Section Food Microbiology)
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13 pages, 1927 KiB  
Article
Experimental and Theoretical Investigation of Thermal Parameters Influencing the Freezing Process of Ice Cream
by Ömer Alp Atici and Derya Burcu Özkan
Appl. Sci. 2024, 14(14), 6194; https://doi.org/10.3390/app14146194 - 16 Jul 2024
Viewed by 1767
Abstract
Freezing time stands out as the most critical parameter in ice cream production, significantly influencing the final product’s quality and production efficiency. Therefore, it is essential to accurately estimate the freezing time based on ice cream recipes. This research paper focuses on determining [...] Read more.
Freezing time stands out as the most critical parameter in ice cream production, significantly influencing the final product’s quality and production efficiency. Therefore, it is essential to accurately estimate the freezing time based on ice cream recipes. This research paper focuses on determining the thermal properties of ice cream samples by leveraging insights from previous studies. Moreover, a new specific heat correlation is proposed to account for the latent heat effect of water during the freezing process. The results demonstrated that the new specific heat correlation aligns well with established formulas from previous research as well as experimental results with maximum 2.5% deviation. To validate the accuracy of the proposed numerical model, experimental studies were compared with numerical results for the first time in the context of ice cream freezing inside a mold. Additionally, a parametric analysis was conducted using numerical modelling to discern the relative importance of various production process parameters. Notably, the glycol–water mixture temperature emerged as the most influential parameter affecting freezing time, while the amount of air inside the ice cream was identified as the least significant factor. Full article
(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)
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15 pages, 9611 KiB  
Article
Experimental and Theoretical Study of Heat Transfer in a Chilled Ceiling System
by Cüneyt Deniz Küheylan and Derya Burcu Özkan
Appl. Sci. 2024, 14(13), 5908; https://doi.org/10.3390/app14135908 - 6 Jul 2024
Cited by 1 | Viewed by 1773
Abstract
Radiant cooling has been growing in recent years due to energy savings and improved comfort and health. The aim of this study was to reduce energy consumption and provide comfort using a chilled ceiling panel in the zone. In the experimental part of [...] Read more.
Radiant cooling has been growing in recent years due to energy savings and improved comfort and health. The aim of this study was to reduce energy consumption and provide comfort using a chilled ceiling panel in the zone. In the experimental part of this study, a test room was created to investigate the change in the heat transfer performance of a chilled ceiling panel according to different water temperatures, different water flow rates and different heat source values. As a result of the experimental study, it was found that optimum conditions were achieved with a heat rate of 280 Watts and the lowest supply water temperature of 14 °C, with indoor comfort conditions being achieved with water flow rates of 0.93 m3/h. In the theoretical part of this study, a thermal balance was established for ceiling panel cooling applications. An analytical model of the heat transfer between the cold ceiling panel and the room air was also developed. The convection coefficient, convective heat transfer and total heat transfer coefficient were compared using the values obtained from the experiments and those reported in the literature. It was found that the convection coefficient was within the range reported in the literature, and the radiation heat coefficient was within 99.8% of the literature values. Full article
(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)
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14 pages, 1039 KiB  
Article
Children at Risk of Specific Learning Disorder: A Study on Prevalence and Risk Factors
by Leyla Bozatlı, Hasan Cem Aykutlu, Açelya Sivrikaya Giray, Tuğçe Ataş, Çisem Özkan, Burcu Güneydaş Yıldırım and Işık Görker
Children 2024, 11(7), 759; https://doi.org/10.3390/children11070759 - 22 Jun 2024
Cited by 5 | Viewed by 7057
Abstract
Background: Specific learning disorder (SLD) is a neurodevelopmental condition characterised by significant academic difficulties despite normal intelligence and adequate education. The difficulties with reading, writing, and arithmetic may manifest independently or concurrently at different ages. Early symptoms may appear in preschool, including delays [...] Read more.
Background: Specific learning disorder (SLD) is a neurodevelopmental condition characterised by significant academic difficulties despite normal intelligence and adequate education. The difficulties with reading, writing, and arithmetic may manifest independently or concurrently at different ages. Early symptoms may appear in preschool, including delays in social skills, motor skills, and language development. This study aimed to assess the prevalence of preschool children at risk for SLD and related psychiatric disorders. Method: Data were collected from 515 preschool children in Edirne City, Turkey, using a screening scale for early symptoms of SLD. Socio-demographic information was obtained, and children at risk were invited for a psychiatric evaluation. Results: The mean age of the participants was 72.5 ± 5.6 months. It was determined that 5.7% of the preschool children who participated in the questionnaire were at risk of SLD according to the screening scale scores. Factors such as a father’s low education, the mother smoking during pregnancy, a longer stay in the neonatal intensive care unit, longer screen time, and consanguinity between parents were associated with an increased risk of SLD. Conclusion: This study emphasises the importance of early identification and intervention for SLD and the need to consider associated psychiatric comorbidities. Identifying the risk factors in preschool children may facilitate timely intervention and prevent academic and social difficulties in later years. Full article
(This article belongs to the Section Pediatric Mental Health)
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24 pages, 3937 KiB  
Article
Development of an Antiviral Ion-Activated In Situ Gel Containing 18β-Glycyrrhetinic Acid: A Promising Alternative against Respiratory Syncytial Virus
by Burcu Özkan, Ebru Altuntaş, Ümmühan Ünlü, Hasan Hüseyin Doğan, Yıldız Özsoy and Rabia Çakır Koç
Pharmaceutics 2023, 15(8), 2055; https://doi.org/10.3390/pharmaceutics15082055 - 31 Jul 2023
Cited by 2 | Viewed by 2170
Abstract
The human respiratory syncytial virus (hRSV) is a major cause of serious lower respiratory infections and poses a considerable risk to public health globally. Only a few treatments are currently used to treat RSV infections, and there is no RSV vaccination. Therefore, the [...] Read more.
The human respiratory syncytial virus (hRSV) is a major cause of serious lower respiratory infections and poses a considerable risk to public health globally. Only a few treatments are currently used to treat RSV infections, and there is no RSV vaccination. Therefore, the need for clinically applicable, affordable, and safe RSV prevention and treatment solutions is urgent. In this study, an ion-activated in situ gelling formulation containing the broad-spectrum antiviral 18β-glycyrrhetinic acid (GA) was developed for its antiviral effect on RSV. In this context, pH, mechanical characteristics, ex vivo mucoadhesive strength, in vitro drug release pattern, sprayability, drug content, and stability were all examined. Rheological characteristics were also tested using in vitro gelation capacity and rheological synergism tests. Finally, the cytotoxic and antiviral activities of the optimized in situ gelling formulation on RSV cultured in the human laryngeal epidermoid carcinoma (HEp-2) cell line were evaluated. In conclusion, the optimized formulation prepared with a combination of 0.5% w/w gellan gum and 0.5% w/w sodium carboxymethylcellulose demonstrated good gelation capacity and sprayability (weight deviation between the first day of the experiment (T0) and the last day of the experiment (T14) was 0.34%), desired rheological synergism (mucoadhesive force (Fb): 9.53 Pa), mechanical characteristics (adhesiveness: 0.300 ± 0.05 mJ), ex vivo bioadhesion force (19.67 ± 1.90 g), drug content uniformity (RSD%: 0.494), and sustained drug release over a period of 6 h (24.56% ± 0.49). The optimized formulation demonstrated strong anti-hRSV activity (simultaneous half maximal effective concentration (EC50) = 0.05 µg/mL; selectivity index (SI) = 306; pre-infection EC50 = 0.154 µg/mL; SI = 100), which was significantly higher than that of ribavirin (EC50 = 4.189 µg/mL; SI = 28) used as a positive control against hRSV, according to the results of the antiviral activity test. In conclusion, this study showed that nasal in situ gelling spray can prevent viral infection and replication by directly inhibiting viral entry or modulating viral replication. Full article
(This article belongs to the Special Issue In Situ Gel for Sustained Drug Delivery)
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33 pages, 5353 KiB  
Review
Biopolymer-Based Nanogel Approach in Drug Delivery: Basic Concept and Current Developments
by Ebru Altuntaş, Burcu Özkan, Sevgi Güngör and Yıldız Özsoy
Pharmaceutics 2023, 15(6), 1644; https://doi.org/10.3390/pharmaceutics15061644 - 2 Jun 2023
Cited by 47 | Viewed by 4723
Abstract
Due to their increased surface area, extent of swelling and active substance-loading capacity and flexibility, nanogels made from natural and synthetic polymers have gained significant interest in scientific and industrial areas. In particular, the customized design and implementation of nontoxic, biocompatible, and biodegradable [...] Read more.
Due to their increased surface area, extent of swelling and active substance-loading capacity and flexibility, nanogels made from natural and synthetic polymers have gained significant interest in scientific and industrial areas. In particular, the customized design and implementation of nontoxic, biocompatible, and biodegradable micro/nano carriers makes their usage very feasible for a range of biomedical applications, including drug delivery, tissue engineering, and bioimaging. The design and application methodologies of nanogels are outlined in this review. Additionally, the most recent advancements in nanogel biomedical applications are discussed, with particular emphasis on applications for the delivery of drugs and biomolecules. Full article
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17 pages, 3004 KiB  
Article
Elucidation of DNA-Eltrombopag Binding: Electrochemical, Spectroscopic and Molecular Docking Techniques
by Somaye Cheraghi, Pelin Şenel, Burcu Dogan Topal, Soykan Agar, Mahsa Majidian, Mine Yurtsever, Esen Bellur Atici, Ayşegül Gölcü and Sibel A. Ozkan
Biosensors 2023, 13(3), 300; https://doi.org/10.3390/bios13030300 - 21 Feb 2023
Cited by 15 | Viewed by 2682
Abstract
Eltrombopag is a powerful adjuvant anticancer drug used in treating MS (myelodysplastic syndrome) and AML (acute myeloid leukemia) diseases. In this study, the interaction mechanism between eltrombopag and DNA was studied by voltammetry, spectroscopic techniques, and viscosity measurements. We developed a DNA-based biosensor [...] Read more.
Eltrombopag is a powerful adjuvant anticancer drug used in treating MS (myelodysplastic syndrome) and AML (acute myeloid leukemia) diseases. In this study, the interaction mechanism between eltrombopag and DNA was studied by voltammetry, spectroscopic techniques, and viscosity measurements. We developed a DNA-based biosensor and nano-biosensor using reduced graphene oxide-modified glassy carbon electrode to detect DNA-eltrombopag binding. The reduction of desoxyguanosine (dGuo) and desoxyadenosine (dAdo) oxidation signals in the presence of the drug demonstrated that a strong interaction could be established between the eltrombopag and dsDNA. The eltrombopag-DNA interaction was further investigated by UV absorption and fluorescence emission spectroscopy to gain more quantitative insight on binding. Viscosity measurements were utilized to characterize the binding mode of the drug. To shed light on the noncovalent interactions and binding mechanism of eltrombopag molecular docking and molecular dynamics (MD), simulations were performed. Through simultaneously carried out experimental and in silico studies, it was established that the eltrombopag binds onto the DNA via intercalation. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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14 pages, 3071 KiB  
Article
The Interaction between DNA and Three Intercalating Anthracyclines Using Electrochemical DNA Nanobiosensor Based on Metal Nanoparticles Modified Screen-Printed Electrode
by Leyla Karadurmus, Burcu Dogan-Topal, Sevinc Kurbanoglu, Afzal Shah and Sibel A. Ozkan
Micromachines 2021, 12(11), 1337; https://doi.org/10.3390/mi12111337 - 30 Oct 2021
Cited by 20 | Viewed by 2482
Abstract
The screen-printed electrodes have gained increasing importance due to their advantages, such as robustness, portability, and easy handling. The manuscript presents the investigation of the interaction between double-strand deoxyribonucleic acid (dsDNA) and three anthracyclines: epirubicin (EPI), idarubicin (IDA), and doxorubicin (DOX) by differential [...] Read more.
The screen-printed electrodes have gained increasing importance due to their advantages, such as robustness, portability, and easy handling. The manuscript presents the investigation of the interaction between double-strand deoxyribonucleic acid (dsDNA) and three anthracyclines: epirubicin (EPI), idarubicin (IDA), and doxorubicin (DOX) by differential pulse voltammetry on metal nanoparticles modified by screen-printed electrodes. In order to investigate the interaction, the voltammetric signals of dsDNA electroactive bases were used as an indicator. The effect of various metal nanomaterials on the signals of guanine and adenine was evaluated. Moreover, dsDNA/PtNPs/AgNPs/SPE (platinum nanoparticles/silver nanoparticles/screen-printed electrodes) was designed for anthracyclines–dsDNA interaction studies since the layer-by-layer modification strategy of metal nanoparticles increases the surface area. Using the signal of multi-layer calf thymus (ct)-dsDNA, the within-day reproducibility results (RSD%) for guanine and adenine peak currents were found as 0.58% and 0.73%, respectively, and the between-day reproducibility results (RSD%) for guanine and adenine peak currents were found as 1.04% and 1.26%, respectively. The effect of binding time and concentration of three anthracyclines on voltammetric signals of dsDNA bases were also evaluated. The response was examined in the range of 0.3–1.3 ppm EPI, 0.1–1.0 ppm IDA and DOX concentration on dsDNA/PtNPs/AgNPs/SPE. Electrochemical studies proposed that the interaction mechanism between three anthracyclines and dsDNA was an intercalation mode. Full article
(This article belongs to the Special Issue Electrochemical Sensors in Biological Applications)
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15 pages, 11061 KiB  
Article
Effect of Microgravity on Synthesis of Nano Ceria
by Ilgaz I. Soykal, Hyuntae Sohn, Burcu Bayram, Preshit Gawade, Michael P. Snyder, Stephen E. Levine, Hayrani Oz and Umit S. Ozkan
Catalysts 2015, 5(3), 1306-1320; https://doi.org/10.3390/catal5031306 - 20 Jul 2015
Cited by 10 | Viewed by 7727
Abstract
Cerium oxide (CeO2) was prepared using a controlled-precipitation method under microgravity at the International Space Station (ISS). For comparison, ceria was also synthesized under normal-gravity conditions (referred as control). The Brunauer-Emmett-Teller (BET) surface area, pore volume and pore size analysis results [...] Read more.
Cerium oxide (CeO2) was prepared using a controlled-precipitation method under microgravity at the International Space Station (ISS). For comparison, ceria was also synthesized under normal-gravity conditions (referred as control). The Brunauer-Emmett-Teller (BET) surface area, pore volume and pore size analysis results indicated that the ceria particles grown in space had lower surface area and pore volume compared to the control samples. Furthermore, the space samples had a broader pore size distribution ranging from 30–600 Å, whereas the control samples consisted of pore sizes from 30–50 Å range. Structural information of the ceria particles were obtained using TEM and XRD. Based on the TEM images, it was confirmed that the space samples were predominantly nano-rods, on the other hand, only nano-polyhedra particles were seen in the control ceria samples. The average particle size was larger for ceria samples synthesized in space. XRD results showed higher crystallinity as well as larger mean crystal size for the space samples. The effect of sodium hydroxide concentration on synthesis of ceria was also examined using 1 M and 3 M solutions. It was found that the control samples, prepared in 1 M and 3 M sodium hydroxide solutions, did not show a significant difference between the two. However, when the ceria samples were prepared in a more basic medium (3 M) under microgravity, a decrease in the particle size of the nano-rods and appearances of nano-polyhedra and spheres were observed. Full article
(This article belongs to the Special Issue Feature Papers to Celebrate the Landmarks of Catalysts)
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