275 research outputs found
Estimation of Sample Processing Uncertainty of Large-Size Crops in Pesticide Residue Analysis
No full textOmeroglu, Perihan Yolci/0000-0001-8254-3401; BOYACIOGLU, DILEK/0000-0002-8160-0619Sample processing procedure should result in analytical portions that are representative of the analytical sample, even if 1-5 g portion are withdrawn from a large-size crops. Therefore, the efficiency of sample processing should be regularly tested during method validation and internal quality control studies. In the scope of this study, sample processing uncertainty was investigated by surface treatment of the cucumber, papaya, and jackfruit representing large-size crops with radio-labelled chlorpyrifos methyl. After homogenization in a chopper, five small and five large test portions were withdrawn from "statistically" well-mixed materials and their residue content was determined with liquid scintillation counter, which provided a quick and well reproducible mode of quantitative determination of residues. The efficiency of sample processing characterized with the sampling constant, changed between 0.78 and 3.01 kg with typical value of 1.61 kg for processing at ambient temperature. Once the sampling constant was established, it was used to predict the uncertainty of sample processing for different test portion sizes. Uncertainty of sample processing at 30 g analytical portion varied between 4.70 and 10.55 %. Furthermore, addition of dry ice to papaya resulted in well-mixed samples as well as 50 % reduction in sampling constant value.FAO/IAEAThe present study was performed in FAO/IAEA Training and Reference Center for Food and Pesticide Control, Austria. The support of FAO/IAEA in carrying out the study and the member of IAEA Agrochemical Units in Vienna are greatly appreciated
Dilek Güngör: Ich bin Özlem
No full textThis paper analyzes the novel "Ich bin Özlem" of Dilek Güngör, author of post-migration German literature. This article analyzes: structure and narrative style, the complex personality of the protagonist and the first steps towards the perception of one's own identit
A Case Study to Assess the Sample Preparation Error in Pesticide Residue Analysis
No full textOmeroglu, Perihan Yolci/0000-0001-8254-3401; BOYACIOGLU, DILEK/0000-0002-8160-0619In the scope of this study, pesticide residue distribution within a fruit and the possible error deriving from sample preparation step were demonstrated with the analysis of benomyl residues in peel, pulp, and seeds of papaya fruits treated post-harvest. Benomyl residue, measured as carbendazim, in corresponding sections of peel and pulp of papaya fruits ranged from 0.178 to 1.325 mg/kg and 0.025 to 0.087 mg/kg, respectively. Residue concentration decreased in a range between 41 and 83 % by peeling of papaya. All seeds contained residue value below limit of quantification. As the residues are unevenly distributed among the peel, pulp, and seed, pesticide residue analysis should be carried out accurately according to proper sample preparation protocol in peel, pulp, or in whole fruit and evaluated correctly taking into consideration the purpose of the analysis. The proportion of peel and pulp after their separation significantly affected the residues measured in the peel and pulp. It shows how peeling operation can affect the results and how important it is to remove the peel without significant portion of pulp attached to it. Thus, the selected test system could be well used to demonstrate the possible variability of measured residues depending on the uniformity of sample preparation.FAO/IAEAThe present study was performed in FAO/IAEA Training and Reference Centre for Food and Pesticide Control, Austria. The support of FAO/IAEA in carrying out the study and the member of IAEA Agrochemical Units in Vienna are greatly appreciated
An Overview on Steps of Pesticide Residue Analysis and Contribution of the Individual Steps to the Measurement Uncertainty
No full textOmeroglu, Perihan Yolci/0000-0001-8254-3401; BOYACIOGLU, DILEK/0000-0002-8160-0619To facilitate the international food trade as well as to protect consumers from exposure to unacceptable pesticide residue levels, Codex Alimentarius Commission, European Union, and National Authorities set maximum residue limits for different food commodities. The control of pesticide residues at national and international level requires reliable and comparable analytical data that can be obtained by applying validated methods and implementing an effective internal quality control and quality assurance system in the testing laboratories. For the correct interpretation of the analytical results, measurement uncertainty should be estimated. Pesticide residue analysis includes two main steps: sampling performed outside of the laboratory and laboratory operations comprising of sample preparation, sample size reduction, sample processing, extraction, cleanup, and chromatographic determination. By taking into consideration the contribution of the individual steps to the overall uncertainty of the results, the analytical procedures can be optimized to fit for the purpose of the analysis with minimum cost. The scope of this paper is to review major steps of pesticide residue analysis in the light of current developments, to highlight the importance of identification and estimation of the uncertainties associated with the results, to describe suitable methods for their estimation, and to summarize the contribution of each step to the combined uncertainty
Kruskal's minimum spanning tree approach to brain fiber tractography computation
No full textGöksel Duru, Dilek (Arel Author) --- Conference: 22nd Signal Processing and Communications Applications Conference, SIU 2014
Evaluation of Turkish propolis for its chemical composition, antioxidant capacity, anti-proliferative effect on several human breast cancer cell lines and proliferative effect on fibroblasts and mouse mesenchymal stem cell line
No full textOzdal, Tugba/0000-0001-8344-5336; Capanoglu, Esra/0000-0003-0335-9433; mutlu Altundag, ergul/0000-0002-2377-4047; BOYACIOGLU, DILEK/0000-0002-8160-0619; SARI, Gulce/0000-0002-8585-5889Propolis is an extremely complex resinous natural compound collected by honey bees from various plant sources and exhibits pharmacological and biological properties attributed to the presence of polyphenols. This study examined the total phenolic and flavonoid contents as well as the total antioxidant capacity using 2,2 '-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), cupric-reducing antioxidant capacity (CUPRAC), and ferric-reducing antioxidant power (FRAP) methods. Turkish propolis has very high total phenolic (314.36 +/- 3.65 mg GAE/g propolis) and total flavonoid contents (522.71 +/- 11.45 mg QE/g propolis). The highest antioxidant capacity value was obtained by the CUPRAC method (1184.94 +/- 63.27 mg TE/g propolis). Phenolic profile of Turkish propolis was also determined by high performance liquid chromatography with photodiode array detection (HPLC-PDA) method. The main phenolic compounds identified in Turkish propolis was flavonoids including pinocembrin > chrysin > galangin > pinobanksin > pinostrobin and phenolic acids including caffeic acid > p-coumaric acid > ferrulic acid > t-cinnamic acid. In the present work, anti-proliferative and proliferative effects of propolis extracts were also investigated on two different breast cancer cell lines; MDA-MB-231, UACC-3199 and on two normal cell lines; fibroblasts and mouse mesenchymal stem cell lines. According to the XTT results, Turkish propolis sample showed significant anti-proliferative effect on MDA-MB-231 and UACC breast cancer cell lines. Interestingly, Turkish propolis sample had proliferative effect on both fibroblasts and mouse mesenchymal stem cells. These results suggest that Turkish propolis can be considered as a potent agent on breast cancer treatment for further investigations
Uncertainty of the sample size reduction step in pesticide residue analysis of large-sized crops
No full textOmeroglu, Perihan Yolci/0000-0001-8254-3401; BOYACIOGLU, DILEK/0000-0002-8160-0619To estimate the uncertainty of the sample size reduction step, each unit in laboratory samples of papaya and cucumber was cut into four segments in longitudinal directions and two opposite segments were selected for further homogenisation while the other two were discarded. Jackfruit was cut into six segments in longitudinal directions, and all segments were kept for further analysis. To determine the pesticide residue concentrations in each segment, they were individually homogenised and analysed by chromatographic methods. One segment from each unit of the laboratory sample was drawn randomly to obtain 50 theoretical sub-samples with an MS Office Excel macro. The residue concentrations in a sub-sample were calculated from the weight of segments and the corresponding residue concentration. The coefficient of variation calculated from the residue concentrations of 50 sub-samples gave the relative uncertainty resulting from the sample size reduction step. The sample size reduction step, which is performed by selecting one longitudinal segment from each unit of the laboratory sample, resulted in relative uncertainties of 17% and 21% for field-treated jackfruits and cucumber, respectively, and 7% for post-harvest treated papaya. The results demonstrated that sample size reduction is an inevitable source of uncertainty in pesticide residue analysis of large-sized crops. The post-harvest treatment resulted in a lower variability because the dipping process leads to a more uniform residue concentration on the surface of the crops than does the foliar application of pesticides
Erratum: Improvement of design of a surgical interface using an eye tracking device Bioinformatics (Theoretical Biology and Medical Modelling 11:48 (2014))
No full text#nofulltext# --- Duru, Dilek Göksel (Arel Author)
Estimation of the uncertainties of extraction and clean-up steps in pesticide residue analysis of plant commodities
No full textOmeroglu, Perihan Yolci/0000-0001-8254-3401; BOYACIOGLU, DILEK/0000-0002-8160-0619Extraction and clean-up constitute important steps in pesticide residue analysis. For the correct interpretation of analytical results, uncertainties of extraction and clean-up steps should be taken into account when the combined uncertainty of the analytical result is estimated. In the scope of this study, uncertainties of extraction and clean-up steps were investigated by spiking 14C-labelled chlorpyrifos to analytical portions of tomato, orange, apple, green bean, cucumber, jackfruit, papaya and starfruit. After each step, replicate measurements were carried out with a liquid scintillation counter. Uncertainties in extraction and clean-up steps were estimated separately for every matrix and method combination by using within-laboratory reproducibility standard deviation and were characterised with the CV of recoveries. It was observed that the uncertainty of the ethyl acetate extraction step varied between 0.8% and 5.9%. The relative standard uncertainty of the clean-up step with dispersive SPE used in the method known as QuEChERS was estimated to be around 1.5% for tomato, apple and green beans. The highest variation of 4.8% was observed in cucumber. The uncertainty of the clean-up step with gel permeation chromatography ranged between 5.3% and 13.1%, and it was relatively higher than that obtained with the dispersive SPE method.FAO/IAEAThe present study was performed in the FAO/IAEA Training and Reference Centre for Food and Pesticide Control, Austria. 14C-labelled chlorpyrifos was provided by Dow Chemicals. The support of FAO/IAEA in carrying out the study and the member of IAEA Agrochemical Units in Vienna and Dow Chemicals' cooperation are greatly appreciated
ACPA prevents lung fibroblast-to-CAF transformation by reprogramming the tumor microenvironment through NSCLC-derived exosomes.
No full textNemutlu, Emirhan/0000-0002-7337-6215; Boyacioglu, Ozge/0000-0001-5240-8209; Kalali, Berfin Deniz/0009-0005-9528-0344; Korkusuz, Petek/0000-0002-7553-3915; Gelen-Gungor, Dilek/0000-0002-2089-2590; Reçber, Tuba/0000-0001-8257-7628Non-small cell lung cancer (NSCLC) accounts for most lung cancer cases. Current treatments often cause systemic side effects or lead to drug resistance, prompting the development of new therapies targeting tumors and related cells simultaneously. Cancer-associated fibroblasts (CAFs) are crucial stromal cells within the tumor microenvironment (TME), making them potential targets for therapy. Previously, we found that the CB1 receptor agonist ACPA has anti-tumor effects on NSCLC, inhibiting pathways such as Akt/PI3K, JNK, glycolysis, the citric acid cycle, and the urea cycle both in vitro and in vivo. We hypothesize that ACPA could enhance therapy by inhibiting the transformation of lung fibroblasts into CAFs via exosomes. Control and ACPA-treated NSCLC cell exosomes exhibited similar size, PDI, ZP, and high expression of CD9, CD63, and CD81. ACPA-treated exosomes showed reduced levels of miR-21 and miR-23. These exosomes decreased fibroblast viability within 12 h by disrupting pentose phosphate, lipid, and amino acid metabolism, and by lowering PDPN, alpha-SMA, and FAP expressions. This research highlights ACPA as a promising chemotherapeutic agent, capable of improving NSCLC treatment and reprogramming the TME with more targeted therapies.Hacettepe University Scientific Research Projects Coordination Unit [TSA-2023-20427]This study was supported by Hacettepe University Scientific Research Projects Coordination Unit (TSA-2023-20427)
- …
