Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Aspergillus Sojae Tarafından Üretilen Poligalakturonazın Kısmi Saflaştırılması için Kromatografik Bir Yaklaşım(Sidas Medya Ajans Tanıtım Danışmanlık Ltd. Şti., 2017) Şen, İlknur; Mata-Gomez, Marco A.; Palomares, Marco Rito; Tarı, Canan; Dinç, MelikeBu çalışmanın amacı, A. sojae mutantından poligalakturonaz üretilmesi ve ham ekstraktın kromatografik yöntemlerle kısmi saflaştırılmasıdır. Peptitlerin konfirmasyonu için ilk basamak olarak, jel içinde sindirilmiş sodyum-dodesil-sülfatpoliakrilamid-jel-elektroforezi (SDS-PAGE) jellerinde matriks-yardımlı lazer desorpsiyon/iyonlaştırmalı-uçuş zamanlıkütle spektrometresi (Maldi-TOF MS) analizi yapılmıştır. Poligalakturonaz üretimi için, katı-faz ve derin fermentasyonlarda üç farklı karbon kaynağı kullanılmıştır. Ham ekstrakt ilk olarak iyon değişim kromatografisi (IEXC) ile saflaştırılmıştır ve ardından bunu boyut eleme kromatografisi izlemiştir. Derin [acı portakal kabuğu, şeker pancarı melası ve (NH4)2SO4] ve katı-faz (buğday kepeği, şeker pancarı ve HCl) fermentasyonlarından elde edilen ham ekstraktlar yüksek seviyede poligalakturonaz enzim aktivitesi (sırasıyla 95.22 and 50.27 U/mL) göstermiştir. IEXC toplanmış fraksiyonunun (180, 200 ve 220 mM tuz fraksiyonları) boyut elemesi, en yüksek verimi (%36) ve saflaştırma katını (2.00) göstermiştir. SDS-PAGE'den elde edilen olası poligalakturonaz bantları jel içinde sindirilmiş ve peptit konfirmasyonu için Maldi-TOF-MS ile analiz edilmiştir.Article Determination of Triacylglycerol Composition of Ayvalık and Memecik Olive Oils During Storage by Chemometric Methods(Sakarya Üniversitesi, 2017) Köseoğlu, Oya; Sevim, Didar; Özdemir, DurmuşThe aim of present investigation is to discriminate two important Turkish olive cultivars (Ayvalık and Memecik) by studying their triacylglycerol (TAG) compositions during storage (15 months) taken from different orchard in Ayvalık and Aydın region which have a significant potential for olive oil production in Turkey, during 2009 and 2010 harvest years. Olives were harvested by hand at 2 different maturation indices and processed by an Abencor system. The olive oil samples were stored at room temperature and they were divided into two groups including exposed to diffused daylight and dark for a period of 15 months. Multivariate classification and clustering were done by the application of unsupervised chemometrics methods such as principal component analysis (PCA) and hierarchical cluster analysis (HCA) based on the TAG profiles of the olive oil samples. PCA and HCA analysis of olive oils showed significant differences according to harvest years and cultivars. PCA scores plot showed that the samples were classified into two main groups with respect to harvest years based on the first principal component (PC1). In terms of storage effect, there was no significant change in TAG compositions among the samples from beginning of storage to 15 months of storage regardless of storage conditions (either in dark or in daylight). In addition, PCA scores plot indicated that the samples were also successfully clustered into two sub-groups according to cultivars in both years based on the second principal component (PC2).Article Determination of Bitterness Index (k225) and Total Fenol Content of Olive Oils Obtained With Different Regions, Varieties and Processing Systems(Ege Üniversitesi, 2018) Köseoğlu, Oya; Sevim, Didar; Dural, Mehmet Ulaş; Özdemir, DurmuşIn this work the effect of different growing areas on olive (Ayvalık, Memecik, Gemlik, Beylik, Edincik Su, Girit, Kilis Yağlık, Sarı Ulak, Tavşan Yüreği, Topak Aşı) oil bitterness index (K225) were studied at the South Marmara, South and North Aegean, West and East Mediterranean Regions at two, two and a half (2.5), and three phase extraction system, during 2014/2015 crop season. A total of 41 virgin olive oils samples were collected from these Regions. Total phenol content and bitternes index (K225) were analyzed in the research. A Solid-Phase Extraction procedure were carried out for extraction of the bitter compounds. The results of total phenol content and K225 values showed that the Beylik olive oil was determined with the highest total phenol conent and bitterness index (K225) with 330.26 mg CAE kg-1 oil and 1.21 at 2.5 phase extraction system from Manavgat at the West Mediterranean Region, respectively. After the Beylik variety, the highest total phenol content was determined Ayvalık and Edincik Su olive oil with 291.03 and 270.62 mg CAE kg-1 oil, respectively. The Memecik and Ayvalık olive oil bitterness index (K225) was determined 0.86 and 0.85 at two phase extraction system from Muğla and Burhaniye at the South and North Aegean, respectively.Conference Object Citation - WoS: 2Citation - Scopus: 1Determination of Aluminum Oxide Thickness on the Annealed Surface of 8000 Series Aluminum Foil by Fourier Transform Infrared Spectroscopy(Springer, 2017) İnanç Uçar, Özlem; Ekin Meşe, Ayten; Birbaşar, Onur; Dündar, Murat; Özdemir, DurmuşAluminum foil produced with prescribed thermomechanical processing route develop oxide film. Alloy chemistry and annealing practices, particularly its duration and exposed temperature, determine the characteristics of the oxide film. The magnitude and characteristics of the oxide film may impair surface features leading to serious problems in some applications, such as coating, printing and in some severe cases failure in formability. Therefore, it is important for the rolling industry to be able to monitor the oxide formation on the foil products and quantify its thickness. Well known methods to measure an oxide thickness that is in the order of nanometer, require meticulous sample preparation techniques, long duration for measurements and sophisticated equipment. However, in this study, a simple and rapid grazing angle attenuated total reflectance infrared (GA-ATR-FTIR) spectroscopic method combined with chemometrics multivariate calibration has been developed for the oxide thickness determination which is validated with x-ray photoelectron spectroscopy (XPS). 3000 and 8000 series aluminum foil materials which were produced by twin roll casting technique were used in this study. Foil samples were annealed at various different temperatures and annealing times in a laboratory scale furnace. Immediately after collecting GA-ATR-FTIR spectra, the 3000 series alloy samples were sent to a laboratory where XPS reference oxide thickness measurements had been performed. Partial Least Squares (PLS) method was used to develop a multivariate calibration model based on FTIR spectra and XPS reference oxide thickness values in order to predict the aluminum oxide thickness. The correlation coefficient of XPS reference oxide thickness values versus grazing angle ATR-FTIR based PLS predicted values was found as 0.9903 the standard error of cross validation (SECV) was found to be 0.29 nm in range of 4.9–14.0 nm for Al2O3. In addition, the standard error of prediction (SEP) for the validation set was 0.24 nm with the model generated with three principal components (PCs). © The Minerals, Metals & Materials Society 2017.Conference Object Citation - Scopus: 2Utilization of Near Ir Absorbing Gold Nanocolloids by Green Synthesis(Trans Tech Publications, 2018) Elveren, Beste; Yıldız, Ümit Hakan; Arslan Yıldız, AhuThe rapid developments in nanoscience, and its applications on biomedical areas have a large impact on drug delivery, tissue engineering, sensing, and diagnosis. Gold is widely investigated nanomaterial for the last couple of decades, since it has unique surface properties and very low toxicity to biological environment. In this work, we present a novel synthesis of gold nanoparticles (GNPs) exhibiting both visible and near-IR absorbance without agglomeration. The surface of GNPs were analyzed by routine methods and the binding kinetics were investigated by Surface Plasmon Resonance (SPR) Spectroscopy. The unique optical properties of near-IR asorbing GNP colloids hold promise for biological applications.Conference Object Citation - Scopus: 2Fabrication of Polymer Nanofiber-Conducting Polymer Fabric and Noncontact Motion Sensing Platform(Trans Tech Publications, 2018) Mutlu, Mustafa Umut; Akın, Osman; Demir, Mustafa Muammer; Yıldız, Ümit HakanConductive polymer-electrospun polymer nanofiber network was combined to host iron oxide nanoparticles providing micrometer thick sensing interface. The sensor has fabricated as freestanding fabric exhibiting 10 to 100 KOhm base resistivity upon bias applied. The moving object has been sensed through the electrostatic interactions between fibers and object. The sensing range has been found to be 1-5 cm above the surface of fabric. By the controlled combination of conductive polymers electrospun polymer nanofibers effective device miniaturization has been provided without loss of performance. The noncontact motion sensor platform has unique flexibility and light weight holding a potential for wearable sensor technology.Conference Object Citation - WoS: 2Citation - Scopus: 2Effects of Mechanical Treatment on the Formation of Α-Al 2o3 From Gibbsite(Trans Tech Publications, 2004) Şakar Deliormanlı, Aylin; Çiftçioğlu, Muhsin; Polat, HürriyetIn this study preparation of fine alpha alumina powders derived from Bayer gibbsite was studied. Preparation of the alumina powders was performed by decomposition of the gibbsite into transition alumina phase followed by controlled transformation to the alpha phase. Gibbsite was thermally treated at 350°C and 900°C to obtain a transition form of alumina. The purpose of the heat treatment at 350°C was to increase the surface area of the gibbsite particles and obtain a loosely packed structure that may reduce the size of the rather coarse precursor gibbsite during the grinding step. Mechanical treatment (by using ultrasonic forces and impact forces) was utilized to increase the transformation rate to the alpha alumina in the transition phase matrix and influence the nucleation and growth rate of the solid -solid phase transformation. These powders were calcined at 1100, 1200 and 1450°C for 1 to 8 hours. Results indicated that transformation to the alpha phase was accomplished in the powders preheated at 900°C, ultrasonically treated or ground, and then calcined at 1200°C for 2 to 8 hours or at 1450°C for 2 hours. Ultrasonic treatment accelerated the transformation rate to the alpha phase at 1100°C in 2 hours. Powders that were calcined at 1100 to 1200°C for 1 hour had a significant kappa content together with the alpha phase. Additionally the powder prepared without mechanical treatment and calcined at 1100°C was mainly in the kappa phase.Article Citation - WoS: 3Fret Measurements Between Small Numbers of Molecules Identifies Subtle Changes in Receptor Interactions(SPIE, 2013) Özçelik, Serdar; Orr, Galya; Hu, Dehong; Chen, Chii-Shiarng; Reşat, Haluk; Harms, Greg S.; Opresko, Lee K.; John Wiley and Sons Inc., H. Steven; Colson, Steven D.Overexpression of HER2 alters the cellular behavior of EGF receptor (EGFR) and itself,with great implications on cell fate. To understand the molecular interactions underlying these alterations, we quantified the association between the two receptors by looking at efficiency changes in fluorescence resonance energy transfer (FRET) between a small number of molecules at the membrane of living cells. Human mammary epithelial (HME) cells expressing varying degrees of HER2 were studied, to identify and compare the degree of receptors interactions as a function of HER2 overexpression. A high resolution wide-field laser microscope combined with a high sensitivity cooled CCD camera was used to capture simultaneously donor and acceptor emissions. Alternating between green and red lasers every 80 msec, donor, FRET, and acceptor images were acquired and were used to calculate FRET efficiency. Automated image analysis was developed to create FRET efficiency maps from overlapping donor, acceptor and FRET images, and derive FRET efficiency histograms to quantify receptorreceptor interactions pixel by pixel. This approach enabled us to detect subtle changes in the average distance between EGFR molecules, and between EGFR and HER2. We found pre-existing EGFR homoassociations, and EGFR-HER2 heteroassociations in cells overexpressing HER2, and identified the changes in these interactions with ligand stimulation. These observations demonstrate the power of FRET measurements between small numbers of molecules in identifying subtle changes in molecular interactions in living cell.