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Koleksiyondaki öğeler
- MakaleAçık Erişim2014Scopus SJRQ2Two-step numerical procedure for complex permittivity retrieval of dielectric materials from reflection measurements
Hasar, Ugur Cem; Barroso, Joaquim José; Kaya, Yunus; Ertugrul, Mehmet; Bute, Musa; Catalá-Civera, José M.
A two-step measurement procedure has been proposed for measurement of complex permittivity of dielectric materials using one-port reflection measurements. In the procedure, as a first step, a graphical method is applied to analyze on the complex reflection-coefficient plane the general pattern of dielectric behavior of the sample. Then, as a second step, optimization algorithms are utilized for retrieving electrical properties of samples. The procedure requires measurement of complex reflection scattering parameters of at least two samples with different lengths. It has been validated by X-band measurements of three polyvinyl chloride samples with lengths 5, 10, and 20 mm.
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İncele - MakaleAçık Erişim2016Scopus SJRQ3Correlation between the DNA methylation and gene expression of IGFBP5 in breast cancer
Karabulut, Sevgi; Kaya, Zehra; Amuran, Gökçe Gullu; Peker, Irem; Özmen, Tolga; Gulluolu, Bahadir M.; Kaya, Handan; Erzik, Can; Ozer, Ayşe; Akkiprik, Mustafa
BACKGROUND: The insulin-like growth factor binding protein5 (IGFBP5) is often dysregulated in human cancers and considered neither a tumor suppressor nor an oncogene. OBJECTIVE: We aim to examine the reason of the changeable gene regulation of IGFBP5 in the case of methylation in breast cancer. METHODS: We used methyl-specific polymerase (MSP) chain reaction to detect CpG methylation of IGFBP5 promoter and exon-I in breast cancer and adjacent tissues. Gene expression is evaluated by quantative polymerase chain reaction (qPCR). RESULTS: IGFBP5 methylation was detected in 24 of 58 (41%) and 54 of 56 (96.5%) promoter and exon-I site respectively in tumor tissues. In adjacent tissues 17 of 58 (29%) and 53 of 56 (96.5%) was methylated. IGFBP5 expression was higher estrogene receptor (ER)(+) than ER(-) patients (p = 0:0549). Beside, we found a positive correlation between the expression of IGFBP5 and G2 tumor grade (p = 0:0131). However, no correlation was observed between IGFBP5 expression and age, menopause or the presence of lymph node metastasis (p > 0:05). CONCLUSIONS: In summary, our results showed that IGFBP5 promoter and exon-I methylation did not have any differences between tumor and adjacent tissues so that IGFBP5 methylation did not change IGFBP5 gene regulation in breast cancer. This is the first study investigating the IGFBP5 gene methylation in breast cancer.
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İncele - MakaleAçık Erişim2017Scopus SJRQ3Possibility-induced simplified neutrosophic aggregation operators and their application to multi-criteria group decision-making
Şahin, Rıdvan; Liu, Peide
Simplified neutrosophic set (SNS) is an appropriate tool used to express the incompleteness, indeterminacy and uncertainty of the evaluation objects in decision-making process. In this study, we define the concept of possibility SNS including two types of information such as the neutrosophic performance provided from the evaluation objects and its possibility degree using a value ranging from zero to one. Then by extending the existing neutrosophic information, aggregation models for SNSs that cannot be used effectively to fusion the two different information described above, we propose two novel neutrosophic aggregation operators considering possibility, which are named as a possibility-induced simplified neutrosophic weighted arithmetic averaging operator and possibility-induced simplified neutrosophic weighted geometric averaging operator, and discuss their properties. Moreover, we develop a useful method based on the proposed aggregation operators for solving a multi-criteria group decision-making problem with the possibility simplified neutrosophic information, in which the weights of decision-makers and decision criteria are calculated based on entropy measure. Finally, a practical example is utilised to show the practicality and effectiveness of the proposed method.
AtıfScopus32WoS28OpenAlex33İncele - MakaleAçık Erişim2017Scopus SJRQ2Functional and Film-forming Properties of Mechanically Deboned Chicken Meat Proteins
Saricaoglu, Furkan Turker; Turhan, Sadettin
In the present study, the functional properties of mechanically deboned chicken meat proteins (MDCM-Ps) were determined at different pH (2, 4, 6, 8 and 12), and film-forming properties were evaluated depending on MDCM-P (2, 3 and 4%) and glycerol (30, 40 and 50%) concentrations. The highest solubility, emulsifying and foaming properties were determined at pH 12. MDCM-P solutions showed non-polyelectrolyte behavior and gelation onset temperature was determined at 36°C. Film-forming properties of MDCM-P showed that the tensile strength decreased, and elongation at break increased as glycerol concentration increased. Films became more transparent with increasing glycerol and decreasing protein concentration, while water vapor permeability increased with increasing glycerol and protein concentration. Water sorption data of films were fitted to the Guggenheim, Anderson, and De Boer model. In general, equilibrium moisture content of films increased as glycerol level increased. Overall, the results showed that MDCM-P could be useful as a new protein source for both food and packaging industries.
AtıfScopus7WoS6OpenAlex9İncele - MakaleAçık Erişim2015Scopus SJRQ1Analysis of patent documents with weighted association rules
Altuntas, Serkan; Dereli, Turkay; Kusiak, Andrew
Analysis of relationship among various technologies may result in technology maximizing profits. Weighted association rules are proposed to determine dependencies across technologies. The proposed approach recognizes uneven importance of patents and technology class in terms of their technological impact and commercial significance. The proposed analysis approach is illustrated with a case study.
AtıfScopus46WoS39OpenAlex49İncele - MakaleYayıncıda açık erişim2015Scopus SJRQ1Monitoring macro voids in mortars by computerized tomography method
Tekin, Ilker; Birgul, Recep; Ozgur Yaman, Ismail; Gencel, Osman; Yilmaz Aruntas, Huseyin
This study aims to investigate the use of ground pumice powder (PP) in cement production and to monitor void developments in mortars by X-ray Computerized Tomography (CT) which is a nondestructive test method. PP-blended cements were produced by replacing ordinary Portland cement with PP at 0% (control), 5%, 10% and 15% by weight. Paste and mortar specimens were manufactured by these blended cements. Some of the physical and mechanical tests are carried out on these mortar specimens. Experimental results showed that macro void developments in 100-day period for mortars with different PP replacement ratios exhibited different reduction in void ratios.
AtıfScopus19WoS17OpenAlex19İncele - Derleme MakaleAçık Erişim2019Scopus SJRQ2Thermoelectric Coolers (TECs): From Theory to Practice
Guclu, Tamer; Cuce, Erdem
Thermoelectric coolers (TECs) are solid state units, which provide reliable energy conversion with no noise or vibration. They are also lightweight and do not include any moving parts. The current coefficient of performance (COP) range of TECs has shown a trend of improvement, and TECs have a wide range of usage areas. Within the scope of this research, TECs are comprehensively evaluated in terms of several aspects such as type, material, design, modelling, thermal performance, potential applications, economic and environmental issues. It can be achieved through the results that the COP of TECs is highly dependent on the temperature difference between hot and cold side (ΔT), and maximum COP is obtained when ΔT is close to zero. It is also observed that COP can be enhanced by more than 55% when the hot side is thermally regulated by phase change materials (PCMs) or integrated with a water cooling unit.
AtıfScopus69WoS61OpenAlex76İncele - MakaleAçık Erişim2019Scopus SJRQ2Characterization of an interesting selenium-dependent glutathione peroxidase (Se-GPx) protecting cells against environmental stress: The Camelus dromedarius erythrocytes Se-GPx
Chafik, Abdelbasset; Essamadi, Abdelkhalid; Çelik, Safinur Yildirim; Solak, Kübra; Mavi, Ahmet
Camel lives most of its life under high environmental stress in the desert. Glutathione peroxidase plays a key role in protecting cells against oxidative stress. For the first time, selenium-dependent glutathione peroxidase (Se-GPx) was purified from camel erythrocytes, biochemically characterized, and some of its properties were studied. The enzyme was purified using ethanol-chloroform treatment, acetone precipitation and ion exchange chromatography. A purification fold of 33.72 with 0.19% yield were obtained. The native molecular weight of the enzyme was estimated to be about 69 kDa. On SDS-PAGE, the enzyme was composed of two different subunits with a molecular weight of approximately 53 and 21 kDa. An optimum temperature of 47 °C and an optimum pH of 7.2 were found. The activation energy was 41.71 kJ/mol. This enzyme was inhibited by thiol reagents, D,L-Dithiothreitol and β-Mercaptoethanol, and was sensitive to bivalent cations. The enzyme had a general specificity toward hydroperoxides, and high specificity for reduced glutathione. The purified enzyme contained 3.06 mol of selenium per mol of protein. The Km and Vmax values for hydrogen peroxide and reduced glutathione were 0.72 and 1.58 mM, and 25.33 and 31.03 U/mg, respectively. The biochemical properties of camel Se-GPx were different comparing to those of mammalian species. Lower molecular weight, heterodimeric structure, higher optimum temperature, relatively lower optimum pH, lower content of selenium and higher affinity for hydrogen peroxide at low reduced glutathione concentration, these could be explained by the fact that camel is able to live in the intense environmental stress in the desert.
AtıfScopus11WoS10OpenAlex10İncele - MakaleAçık Erişim2016Scopus SJRQ1Use of Q-learning approaches for practical medium access control in wireless sensor networks
Kosunalp, Selahattin; Chu, Yi; Mitchell, Paul D.; Grace, David; Clarke, Tim
This paper studies the potential of a novel approach to ensure more efficient and intelligent assignment of capacity through medium access control (MAC) in practical wireless sensor networks. Q-Learning is employed as an intelligent transmission strategy. We review the existing MAC protocols in the context of Q-learning. A recently-proposed, ALOHA and Q-Learning based MAC scheme, ALOHA-Q, is considered which improves the channel performance significantly with a key benefit of simplicity. Practical implementation issues of ALOHA-Q are studied. We demonstrate the performance of the ALOHA-Q through extensive simulations and evaluations in various testbeds. A new exploration/exploitation method is proposed to strengthen the merits of the ALOHA-Q against dynamic the channel and environment conditions.
AtıfScopus41WoS29OpenAlex37İncele - MakaleAçık Erişim2017Scopus SJRQ2Effect of different levels of pine honey addition on physicochemical, microbiological and sensory properties of set-type yoghurt
Mercan, Emİn; Akın, Nİhat
In this study, the effects of different levels of pine honey addition (3%, 5% and 7% w/v) to the yoghurt milk on starter bacteria, physicochemical and sensory characteristics of set-type yoghurts during the storage were investigated. Antioxidant activity and total phenolic content of yoghurts with added honey increased compared to control yoghurt. There was a significant increase in water-holding capacity (WHC), viscosity, total solids, redness (a*) and yellowness (b*) values of the yoghurt samples with the addition of honey at higher concentrations, whereas water activity (aw), pH and luminosity (L*) values decreased. Viscosity and WHC of the yoghurts increased during the storage.
AtıfScopus17WoS16OpenAlex17İncele - MakaleAçık Erişim2013Scopus SJRQ1Comparison of the effects of different types of tube inserts on two-phase flow instabilities
Omeroglu, Gokhan; Çomaklý, Omer; Karagoz, Sendogan; Karsli, Suleyman
Turbulence promoting inner elements such as rings, wings or winglets, twisted tapes, etc., is widely used in single- and two-phase flows. In this experimental work, the two-phase flow instabilities of forced convection boiling in a horizontal tube with ring- and twisted-tape-type inner elements inside are investigated. In order to analyze the two-phase flow of water, the experiments were conducted under a constant system pressure of 7.5 bar, and a constant heat input of 24 kW was applied to the outer surface of the circular test pipe with constant exit restriction. Three different inlet temperatures (Ti = 15, 25, and 35°C) were used to see the effect of inlet sub-cooling, and the mass flow rate was decreased from 110 to 20 g/s to obtain the characteristic curve. Two different pitch ratios for both the ring and twisted tape were evaluated in terms of stability. The results were evaluated in terms of appropriate variables for both the tube with insertions and the smooth tube. The analysis shows that the pressure drop increases with decreasing mass flow rate for all cases. The presence of the inner elements in the test pipe causes the boundaries of the oscillations to narrow in comparison with smooth tube. On the other hand, with the increase in the effective diameter of the test pipe the boundaries of the oscillations broaden. For each type of insertion, the increase of the pitch ratio makes the system less stable.
AtıfScopus4WoS3OpenAlex6İncele - MakaleAçık Erişim2016Scopus SJRQ1EpsA is an essential gene in exopolysaccharide production in Lactobacillus johnsonii FI9785
Dertli, Enes; Mayer, Melinda J.; Colquhoun, Ian J.; Narbad, Arjan
Lactobacillus johnsonii FI9785 has an eps gene cluster which is required for the biosynthesis of homopolymeric exopolysaccharides (EPS)-1 and heteropolymeric EPS-2 as a capsular layer. The first gene of the cluster, epsA, is the putative transcriptional regulator. In this study we showed the crucial role of epsA in EPS biosynthesis by demonstrating that deletion of epsA resulted in complete loss of both EPS-1 and EPS-2 on the cell surface. Plasmid complementation of the epsA gene fully restored EPS production, as confirmed by transmission electron microscopy and nuclear magnetic resonance (NMR) analysis. Furthermore, this complementation resulted in a twofold increase in the expression levels of this gene, which almost doubled amounts of EPS production in comparison with the wild-type strain. Analysis of EPS by NMR showed an increased ratio of the heteropolysaccharide to homopolysaccharide in the complemented strain and allowed identification of the acetylated residue in EPS-2 as the (1,4)-linked βGlcp unit, with the acetyl group located at O-6. These findings indicate that epsA is a positive regulator of EPS production and that EPS production can be manipulated by altering its expression.
AtıfScopus43WoS38OpenAlex39İncele - MakaleAçık Erişim2018Scopus SJRQ4Development of teacher academic optimism scale: The validity and reliability study
Ergen, Yusuf; Elma, Cevat
The study aims to develop a valid and reliable academic optimism scale that can be used to determine teachers' academic optimism levels. The study was conducted through a total number of 404 primary school teachers who worked in the central districts of Malatya Province during 2014-2015 academic year. The content validity and face validity of the scale were determined via expert recommendations. An explanatory factor analysis and a confirmatory factor analysis were conducted to determine the construct validity of the scale. After the expert opinions, 80 items reduced to 64 and the data was collected by the use of these 64 items. An exploratory factor analysis revealed 5 factors reducing 64 items in to 33 and explaining 58.56% of the total variation in the data. The five-factor model obtained through an explanatory factor analysis after removal of one item as a result of the confirmatory factor analysis was observed to be highly consistent. Different from previous related research, the result showed that a new dimension as "Maneger Trust" emerged as a part of "Teacher Academic Optimism Scale". And finally this scale could be used as a valid and reliable instrument in the future studies.
AtıfScopus2WoS1İncele - MakaleYalnız künye2016Scopus SJRQ1Optical, structural, morphological and compositional characterization of a Co-doped GaAs semiconducting thin film produced by thermionic vacuum arc
Şenay, Volkan; Özen, Soner; Pat, Suat; Korkmaz, Şadan
A 80 nm 2 at% Co-doped GaAs thin film was deposited on a glass substrate under a high vacuum condition by means of the thermionic vacuum arc technique using GaAs and Co pellets as source materials. Tools and techniques such as an optical reflectometer, XRD, UV-VIS-NIR spectrophotometer, FESEM, EDX, and AFM were employed to investigate some of the physical properties of the produced film. From the optical investigations, the refractive index at 632.8 nm and optical band gap of the film were determined to be 3.60 and 1.42 eV respectively. XRD characterization indicated that the film contained GaAs and Co phases. A uniform surface morphology with fine grain covering the entire surface was observed through the FESEM and AFM studies, while 30 nm grain size and 2.72 nm root mean square roughness were obtained. The EDX analysis also confirmed the presence of Ga, As and Co in the film.
AtıfScopus19WoS17OpenAlex18İncele - MakaleYalnız künye2018Scopus SJRQ3Identification of Lactic Acid Bacteria from Spontaneous Rye Sourdough and Determination of Their Functional Characteristics
Ispirli, Hümeyra; Demirbaş, Fatmanur; Yüzer, Mustafa O.; Dertli, Enes
This study aimed to identify Lactic Acid Bacteria (LAB) present in rye and rye bran sourdoughs that were prepared spontaneously and determine their functional characteristics. Genotypic characterization of the isolates revealed the presence of 15 distinct LAB strains belonging to 6 different species; Leuconostoc citreum, Lactobacillus plantarum, Lactobacillus graminis, Lactococcus lactis subsp. cremoris, Weissella confusa, and Weissella cibaria in rye sourdoughs. PCR screening of eps genes required for exopolysaccharide (EPS) production revealed that all strains possessed at least one gene required for EPS production and all strains produced homopolymeric EPS comprised of glucose or fructose two Lactobacillus plantarum strains produced both glucan and fructan type EPS. Antifungal activity of these strains was tested against Aspergillus niger and Penicillium chrysogenum identified in this study and several patterns were observed. The phytase activity of these strains was also determined and all strains showed phytase activity with varying degrees.
AtıfScopus24WoS15OpenAlex24İncele - MakaleYalnız künye2014Scopus SJRQ2A comparative study of selected disperse azo dye derivatives based on spectroscopic (FT-IR, NMR and UV-Vis) and nonlinear optical behaviors
Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet
In the present work, a combined experimental and quantum chemical study on ground state equilibrium structure, spectroscopic and nonlinear optical properties of selected disperse azo dye molecules are reported. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000-400 cm-1 for solid state, simulated IR spectra and total energy distribution (TED) of vibrational modes. The chemical shifts were determined from the results of observed 1H and 13C NMR spectra in chloroform and dimethylsulfoxide solution. The DFT/gauge-invariant atomic orbital (GIAO) methodology was applied to predict the magnetic properties. Electronic properties were carried out by UV-Vis spectroscopy and TD-DFT/CIS approach. The nonlinear optical (NLO) features were addressed theoretically. A detailed description of spectroscopic and NLO behaviors of studied disperse azo dyes was reported with the help of comparison of experimental measurements and theoretical calculations.
AtıfScopus30WoS29OpenAlex29İncele - BildiriAçık Erişim2016Scopus SJRQ3Effect of natural aging on RT and HSR superplasticity of ultrafine grained Zn-22Al alloy
Demirtas, Muhammet; Purcek, Gencaga; Yanar, Harun; Zhang, Zhenjun; Zhang, Zhe-Feng
Zn–22Al alloy was processed using a well-designed two-step equal channel angular extrusion/pressing (ECAE/P), and ultrafine-grained (UFG) microstructure with 200 nm grain size was achieved. UFG Zn-22Al was subjected to long-term (up to 60 days) aging at room temperature (RT) and it was seen that natural aging caused limited grain growth in the microstructure. Grain sizes of about 300 nm, 350 nm and 350 nm were measured after 15, 30 and 60 days aging, which mean that UFG Zn-22Al alloy has a good microstructural stability at RT up to 60 days. ECAPed Zn-22Al alloy showed a maximum elongation of about 400% at a high strain rate of 5×10-2 s-1 and maximum elongation decreased with increasing grain size. Elongation to failures of ~375% and ~350% were obtained with the samples having 300 nm and 350 nm grain sizes, respectively. In addition, natural aging slightly decreased the strain rate at which superplastic region formed. While the maximum elongation occurred at the strain rate of 5×10-2 s-1 in ECAPed UFG alloy, it took place at lower strain rate of 1×10-2 s-1 after aging for all time periods. Also, flow stress of the alloy increased with increasing grain size during natural aging.
AtıfScopus7OpenAlex8İncele - MakaleAçık Erişim2015Scopus SJRQ2Isolation and identification of an exopolysaccharide producer Streptococcus thermophilus strain from Turkish yogurt; [Yoğurttan ekzopolisakkarit üreten Streptococcus thermophilus suşunun izolasyonu ve tanımlanması]
Dertli, Enes
Production of exopolysaccharides (EPS) by starter Lactic acid bacteria (LAB) gained special interest due to technological role of these natural polymers. Yogurt samples were collected from different households in Turkey and bacterial strains were isolated and evaluated for EPS production. Strains potentially producing EPS were then identified to species level with 16S rRNA sequencing. An EPS producer Streptecoccus thermophilus strain was identified from yogurt samples. EPS was extracted from culture supernatants of S. thermophilus and partially purified and structural analysis of the crude EPS by FTIR spectroscopy revealed the presence of typical functional groups related to exopolysaccharides. This study explains the identification of a potential starter culture for yogurt production with EPS production.
AtıfScopus7WoS7OpenAlex1İncele - MakaleAçık Erişim2016Scopus SJRQ1Effects of milk somatic cell counts on some physicochemical and functional characteristics of skim and whole milk powders
Sert, Durmuş; Mercan, Emin; Aydemir, Serdar; Civelek, Mustafa
The aim of this work was to study the influence of milk somatic cell count (SCC) levels on spray-dried milk powders. For this reason, 3 cow milks with different SCC (<300,000, 300,000-700,000, >700,000 SCC/mL) were processed into skim (SMP) and whole milk powder (WMP). The effect of SCC on the physicochemical and functional characteristics of the milk powders and textural properties of set-type yogurts produced from reconstituted milk powders with different SCC was evaluated. A crucial difference was noted between milk powders depending on different SCC. Protein values and ash content of powder samples decreased correlatively with increasing SCC. The hydroxymethylfurfural content of SMP was higher than WMP. We noted an increase in hydroxymethylfurfural content of both SMP and WMP depending on elevated SCC. Solubility index of SMP and WMP was 1.280 to 1.632 and 0.940 to 1.208 mL, respectively; with increasing SCC, solubility index was affected adversely. The highest foam stability was determined in SMP containing >700,000 SCC. Bulk density of SMP and WMP was between 0.682 and 0.708 and 0.660 to 0.685 g/cm3, respectively. An increase was observed in scorched particle of both SMP and WMP depending on increasing SCC. We found significant differences in particle size distribution of milk powders produced from milk with SCC at different levels. Although WMP had more uniform and big particle structure, SMP had more specific area. A negative correlation was noted between yogurt texture and SCC. Results indicate that milk SCC has negative influences on milk powder quality.
AtıfScopus24WoS18OpenAlex27İncele - MakaleAçık Erişim2017Scopus SJRQ2L-shell differential cross-section and alignment of uranium at 59.54-keV photon energy
Akkuş, Tuba; Alım, Bünyamin; Yılmaz, Demet; Şahin, Yusuf
L X-ray differential cross-sections of uranium were calculated at several polar scattering angles (85°, 95°, 105°, 115°, 125°, and 135°) at 59.54-keV photon energy by using a Si(Li) detector. We observed that Ll and Lα X-rays were dependent on the polar scattering angle, whereas Lβ and Lγ X-rays were independent of the polar scattering angle. Therefore, the anisotropy parameters for Ll and Lα X-rays were obtained using the intensity ratios of Ll to Lγ X-rays and of Lα to Lγ X-rays to reduce some systematic errors.
AtıfScopus2WoS2OpenAlex2İncele
