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Koleksiyondaki öğeler
- MakaleAçık Erişim2014Trace/heavy metal accumulation in soil and in the shoots of acacia tree, Gümüşhane-Turkey
Vural, Alaaddin
In this study, heavy metal/trace element accumulation was investigated in soils along the road passing through Gümüshane city center and shoots of 1-2 years of acacia trees (Robinia pseudoacacia L.) grown in these soils. Heavy metal contents in soils and plants were analyzed by Enrichment Factor (EF), Geo-accumulation index (Igeo) parameters, and by Bio Accumulation Factor (BAF), respectively. According to geo-accumulation index (Igeo) data, it is seen that the soil was unpolluted in terms of Cr, Co, Cu, Rb, Sr; unpolluted to moderately polluted in terms of V, Ni and Zn; moderate to excessively polluted in terms of As, and moderate to excessively polluted in terms of Pb. According to EF parameters, on the other hand, it is observed that the soil was non to slightly enriched in terms of Cr, Co, Sr and Ba; non to moderately enriched in terms of Ni and Cu; slightly to significantly enriched in terms of Zn; significant to very highly enriched in terms of As and slightly to over excessively enriched in terms of Pb. Although trace/heavy metal contents of acacia shoots were usually within normal values for acacia, it was determined that Cu, Fe, Mo, Ni, Sr and Zn concentrations were within and/or above upper limits of normal values in certain sampling points.
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İncele - BildiriYalnız künye2012Three-dimensional modeling of the sesamoid bones
Catal, Hatice; Corumluoglu, Ozsen
In this research, digital image processing techniques was used to create 3-dimensional (3D) virtual model of sesamoid bones. As study materials, Ballerina's and sedentary women's axial MDCT (Multidetector Computed Tomography) feet images were utilized. For the determination bone boundaries in each slides, image preprocessing and then segmentation steps were followed. All these processing steps was done in 3DDoctor software. All the measurements were obtained over the 3D model formed. Various statistical ratios were computed regarding the area, volume and length measurements. The comparison done in the study was performed by using these ratios for sedentary and ballerinas. As an outcome, some differences were found in sesamoid bones of ballerina and sedentary women.
- MakaleAçık Erişim2012Scopus SJRQ4Synthesis and characterization of new metallophthalocyanines bearing macrocyclic N 3O 2 groups on peripheral positions
Kaya, Elif Çelenk
The synthesis and characterization of new zinc(II) 3 , nickel(II) 4 and cobalt(II) 5 phthalocyanines complexes carrying macrocyclic N 3 O 2 groups on peripheral positions are described. The compounds were characterized by elemental analysis, IR, 1 H and 13 C NMR, UV-Vis and MS spectral data.
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İncele - MakaleYalnız künye2017Scopus SJRQ2Genome reprogramming in Saccharomyces cerevisiae upon nonylphenol exposure
Bereketoglu, Ceyhun; Arga, Kazim Yalcin; Eraslan, Serpil; Mertoglu, Bulent
Bioaccumulative environmental estrogen, nonylphenol (NP; 4-nonylphenol), is widely used as a nonionic surfactant and can affect human health. Since genomes of Saccharomyces cerevisiae and higher eukaryotes share many structural and functional similarities, we investigated subcellular effects of NP on S. cerevisiae BY4742 cells by analyzing genome-wide transcriptional profiles. We examined effects of low (1 mg/l; <15% cell number reduction) and high (5 mg/l; >65% cell number reduction) inhibitory concentration exposures for 120 or 180 min. After 120 and 180 min of 1 mg/l NP exposure, 187 (63 downregulated, 124 upregulated) and 103 genes (56 downregulated, 47 upregulated), respectively, were differentially expressed. Similarly, 678 (168 repressed, 510 induced) and 688 genes (215 repressed, 473 induced) were differentially expressed in cells exposed to 5 mg/l NP for 120 and 180 min, respectively. Only 15 downregulated and 63 upregulated genes were common between low and high NP inhibitory concentration exposure for 120 min, whereas 16 downregulated and 31 upregulated genes were common after the 180-min exposure. Several processes/pathways were prominently affected by either low or high inhibitory concentration exposure, while certain processes were affected by both inhibitory concentrations, including ion transport, response to chemicals, transmembrane transport, cellular amino acids, and carbohydrate metabolism. While minimal expression changes were observed with low inhibitory concentration exposure, 5 mg/l NP treatment induced substantial expression changes in genes involved in oxidative phosphorylation, cell wall biogenesis, ribosomal biogenesis, and RNA processing, and encoding heat shock proteins and ubiquitin-conjugating enzymes. Collectively, these results provide considerable information on effects of NP at the molecular level.
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İncele - MakaleAçık Erişim2017Scopus SJRQ2Developing web based decision support system for evaluation occupational risks at shipyards
Cebi, Selcuk; Akyuz, Emre; Sahin, Yasin
In this study, a web based decision support system (WBDSS) has been developed to provide decision aid for risk analysis on occupational health and safety at shipyards. The system has been constructed as a modular structure to make its application easy for all kind of firms. The WBDSS is rule based and its database includes safety measures and risks for each tool and machine used in shipbuilding process. In addition, probability and hazard values have been involved in the case of violated measures. The frequencies of the violations that occurred in the work environment are entered to the system by the user. Hence, the system provides a decision support about the risks related to facilities and the cautions to be taken in the workplace. The developed WBDSS has the capability of determining accident, almost accident, and threat formation factors at workplace according to the changing parameters. In this aspect, it enables one to constantly monitor, check and evaluate risk preventive measures. Then, the capabilities of the suggested decision support system have been tested with different scenarios for shipyard processes. When the developed WBDSS is applied to all workplaces, it is aimed at providing a decrease in the number of accidents which cause death, occupational illness, injury, and temporary incapability.
AtıfScopus11WoS11OpenAlex12İncele - MakaleAçık Erişim2019Scopus SJRQ2Determination of the wear performance of diamond saw blades using inductively coupled plasma
Inal, Serkan; Erkan, Ilker; Aydiner, Kerim
Saw blades are one of the most used cutting tools. They compose the expensive parts of a cutting machine. Therefore, saw-blade wear is an important parameter governing the economy of the cutting process. Significant savings could be made when it is controlled effectively. In this study, a new methodology is employed for the determination of the saw-blade wear in the cutting of two types of marble. Wear of segments is determined by high-precision inductively coupled plasma method. Two types of marbles were used to investigate the wear performance of diamond-impregnated segments of circular saw-blade matrix. Taguchi mixed design L16 (43 21) is used as an experimental design and the results are evaluated statistically with Minitab. The results reveal that the specific wear rate (SWR) of Beige marble increases with the increase of the peripheral speed, traverse speed, depth of cut and down-cut mode operation. Additionally, it is demonstrated that the traverse speed and peripheral speed are the dominant cutting parameters affecting the SWR. It is also seen that similar trends are observed for Onyx marble (excluding peripheral speed). Finally, it is concluded that the proposed models can be effectively used for the estimation of the SWR.
AtıfScopus4WoS2OpenAlex6İncele - MakaleYalnız künye2018Scopus SJRQ2Constructal Placement of Discrete Heat Sources with Different Lengths in Vertical Ducts under Natural and Mixed Convection
Sarper, Bugra; Saglam, Mehmet; Aydin, Orhan
In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS FLUENT. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.
AtıfScopus11WoS11OpenAlex12İncele - Kitap BölümüYalnız künye2019The impact of export promotion programs on the technological intensity of export products: The case of Turkey
Mete, Emrullah; Yildiz, Gizem Akbulut
Introduction Exports of high-tech products have gained considerable importance along with globalization and increasing competition in the world economy. Countries have become increasingly in need of exports of high-tech products in order to be competitive and to increase their market shares as well as to protect their current status in markets. In order to overcome the squeeze experienced in world trade, companies and countries increased their research and development expenses to innovate. This process, which manifests itself in producing the current product at a lower cost and/or creating a new product, changed the shares of countries in world trade and hence has become an important part of foreign trade. There is a significant number of studies in the empirical literature indicating that research and development expenses improve innovation which eventually lead to increase in the share of high-tech products in total exports of countries. Since the high-tech product means high value added product at the same time, the increase in exports of high-tech products will also facilitate the economic growth. Thus, it is also important nowadays that countries take the issue of the technology concentration into account and apply it in the scope of their export support programs. It should be taken into consideration by public authorities who design support policies for exporting that the aim of increasing export performance, competitiveness, and market share in foreign trade can be reached through exporting of high-tech products. This study investigates the impact of export….
- MakaleYalnız künye2016Scopus SJRQ2A New Approach for Determination of Volumetric Water Content in Soil Samples by Gamma-Ray Transmission
Celik, Necati; Altin, Duygu; Cevik, Ugur
A new method was presented for the purpose of volumetric water content determination in any soil sample by gamma-ray transmission. Monte Carlo (MC) simulation technique was used to determine the functional behavior of the linear attenuation coefficient of soil samples having different water contents for three soil samples. Using this functional behavior, the linear attenuation coefficients of dry soil and water were obtained from the intercept and the slope, respectively. It was experimentally shown that the mass attenuation coefficients of soil samples were not sensitive to the chemical composition but only to the physical density. This independence was exploited in this study to obtain the linear attenuation coefficient of a completely dry soil which was found to be 0.1409, 0.1274, and 0.1657 cm−1 for Gumushane, Ardahan, and Trabzon soil, respectively. The linear attenuation coefficient of water was determined to be 0.09 cm−1. Then, the volumetric water contents were obtained by measuring the gamma-ray intensities passed through three wet soil samples. The results were found to be 0.186, 0.182, and 0.214 cm3 cm−3 for Gumushane, Ardahan, and Trabzon soil, respectively. The results obtained by the method introduced were compared with the results obtained using gravimetric method. A very good agreement was observed.
AtıfScopus7WoS7OpenAlex8İncele - BildiriYalnız künye2019Module Level Global Maximum Power Point Tracking Strategy
Basoglu, Mustafa Engin
Partial shading of photovoltaic (PV) modules can occur at any time due to the obstacles such as chimney, tree, antenna, bird flock etc. Due to such obstacles, the entire surface of the PV module cannot receive an equal amount of irradiance; Therefore, PV modules cannot operate at its maximum power point (MPP). In this paper, an improved version of a 0.8VOC model based global maximum power point tracking (GMPPT) strategy has been proposed. Single ended primary inductance converter (SEPIC) is used as a power converter between PV module and load. Effectiveness of the proposed technique is presented by experimental studies with the comparison of a full scanning approach. Results of experimental studies show that proposed GMPPT strategy outperforms than full scanning based algorithm known.
AtıfScopus3WoS2OpenAlex2İncele - MakaleYalnız künye2016Scopus SJRQ2Effects of organic solid cattle manure application on nutritive value of winter cereal forages
Yolcu, H.; Gullap, M.K.; Yildirim, M.; Lithourgidis, A.; Deveci, M.
Nutritive value of winter cereal forages is one of interested subjects of farmers for animal feeding. Field experiments were established in 2007–2008 and 2008–2009 growing seasons in northeast Turkey to investigate the effect of organic solid cattle manure application (0, 10 and 20 Mg ha−1 yr−1) on nutritive value of three annual cereals for forage. The winter cereal forages were: wheat (Triticum aestivum L.), oat (Avena sativa L.) and rye (Secela cereale L.). ADF (acid detergent fiber), NDF (neutral detergent fiber) CP (crude protein), nitrogen, phosphorus, potassium, sulfur, calcium, copper, iron, magnesium, manganese, sodium, zinc and boron (N, P, K, S, Ca, Cu, Fe, Mg, Mn, Na, Zn and B) concentrations were researched in this study. Wheat had the highest CP, N, Ca, Cu, Na and Zn concentration, whereas oat had the lowest ADF and NDF and the highest K, Fe and Mn concentrations. The greatest Mg and P concentrations were determined in rye. Organic solid cattle manure applications had no effect on N and CP contents, but it decreased ADF and NDF contents. However, in most cases it positively affected the P, B, Cu, Fe, Mg and Na concentrations, whereas it decreased K, Ca, Mn and Zn concentrations. The results showed that wheat and oat are more nutritive species than rye in terms of animal feeding and the organic solid cattle manure, in some cases increased the nutritive values of wheat, oat and rye under organic agriculture conditions.
AtıfScopus4WoS6OpenAlex6İncele - MakaleYalnız künye2018Scopus SJRQ1Analytical solution to continuous contact problem for a functionally graded layer loaded through two dissimilar rigid punches
Polat, Alper; Kaya, Yusuf; Özşahin, Talat Şükrü
A continuous contact problem of functionally graded layer resting on an elastic semi-infinite plane, which is loaded with through two different blocks is addressed in this study. The elasticity theory and integral transformation techniques are used in solution of the problem. The problem is reduced to a system of singular integral equations, and solved numerically by the aid of appropriate Gauss–Chebyshev integration formula. It is assumed that the elastic semi-infinite homogeneous plane is isotropic and all surfaces are frictionless and continuous. The shear modulus and the mass density of the FG layer vary exponentially along the thickness direction.
AtıfScopus19WoS18OpenAlex15İncele - MakaleYayıncıda açık erişim2016Scopus SJRQ1Effects of non-uniform temperature distribution on critical member temperature of steel tubular truss
Ozyurt, E.; Wang, Y.C.
This paper examines the effects of thermal restraint, caused by non-uniform temperature distribution in different members, on the failure temperatures of critical members of steel tubular trusses. Non-uniform temperature distribution develops in trusses exposed to localised fire attack. The truss member nearest to the fire source experiences the highest temperature, with reduced temperatures in the nearby members. The number of the nearby truss members being heated and their temperatures will affect the failure temperature of the critical truss member which has the highest temperature. The aim of this paper is to develop a simplified method to account for the effects of different numbers of members being simultaneously heated to different temperatures on the development of compression force and failure temperature of the critical member. Finite Element (FE) simulations were carried out for Circular Hollow Section (CHS) trusses using the commercial Finite Element software ABAQUS v6.10-1 which has previously been validated by the authors. The simulation trusses were subjected to constant mechanical loads and then increasing temperatures until failure. The elevated temperature stress-strain curves were based on EN-1993-1-2 [1]. Initial geometrical imperfections were included, based on the lowest buckling mode from eigenvalue analysis.The numerical study examined the effects of truss type, critical member slenderness, applied load ratio and axial restraint stiffness ratio on the failure temperatures of the critical truss members. The numerical simulation results were used to check the accuracy of a proposed simplified calculation method, combining linear elastic static truss analysis at ambient temperature and analytical equations to calculated the failure temperatures of thermally restrained truss members based on the regression equations of Wang et al. [2]. The calculation method was shown to be sufficiently accurate for fire resistant design purpose.
AtıfScopus27WoS24OpenAlex26İncele - MakaleYalnız künye2017Scopus SJRQ1Comparison of low cost 3D structured light scanners for face modeling
Bakirman, Tolga; Gumusay, Mustafa Umit; Reis, Hatice Catal; Selbesoglu, Mahmut Oguz; Yosmaoglu, Serra; Yaras, Mehmet Cem; Seker, Dursun Zafer; Bayram, Bulent
This study aims to compare three different structured light scanner systems to generate accurate 3D human face models. Among these systems, the most dense and expensive one was denoted as the reference and the other two that were low cost and low resolution were compared according to the reference system. One female face and one male face were scanned with three light scanner systems. Point-cloud filtering, mesh generation, and hole-filling steps were carried out using a trial version of commercial software; moreover, the data evaluation process was realized using CloudCompare open-source software. Various filtering and mesh smoothing levels were applied on reference data to compare with other low-cost systems. Thus, the optimum reduction level of reference data was evaluated to continue further processes. The outcome of the presented study shows that low-cost structured light scanners have a great potential for 3D object modeling, including the human face. A considerable cheap structured light system has been used due to its capacity to obtain spatial and morphological information in the case study of 3D human face modeling. This study also discusses the benefits and accuracy of low-cost structured light systems.
AtıfScopus46WoS37OpenAlex42İncele - Derleme MakaleYalnız künye2018Scopus SJRQ1A Review Study on the Using of Diethyl Ether in Diesel Engines: Effects on Fuel Properties and Engine Performance
Sezer, İsmet
This study was compiled from the results of various researches performed on using diethyl ether as a fuel or fuel additive in diesel engines. Three different techniques are used the reduction of the harmful exhaust emissions of diesel engines. The first technique for the reduction of harmful emissions is improved the combustion by modification of engine design and fuel injection system, but this process is expensive and time consuming. The second technique is the using various exhaust gas devices like catalytic converter and diesel particulate filter. However, the use of these devices affects negatively diesel engine performance. The final technique to reduce emissions and also improve diesel engine performance is the use of various alternative fuels or fuel additives. The major pollutants of diesel engines are oxides of nitrogen (NOx) and particulate matter (PM). It is very difficult to reduce NOx and PM simultaneously in practice. The most researches declare that the best way to reduce is the use of various alternative fuels i. e. natural gas, biogas, biodiesel or using the additives with alternative fuels or conventional diesel fuel. Therefore, it is very important that the results of various studies on alternative fuels or fuel additives are evaluated together to practice applications. Especially, this study focus on the use diethyl ether in diesel engines as fuel or fuel additive in various diesel engine fuels. This review study investigates the effects of diethyl ether addition on the fuel properties and performance characteristics.
AtıfScopus17WoS15OpenAlex19İncele - MakaleAçık Erişim2018Scopus SJRQ3Effect of amino acid substitution in New Delhi metallo-β-lactamase on carbapenem susceptibility
Düzgün, Azer Özad
The aim of this work was investigation of clinically important amino acid substitutions of NDM-1 variants. A blaNDM-1 gene was cloned into expression vector pET100/D-TOPO. The sequence of NDM-1 variants with substituted amino acids was determined by ClustalW program. A pET100/D-TOPO + blaNDM-1 was used to generate the alanine mutations at different positions, such as NDM-2 (P28A), NDM-3 (D95A), NDM-4 (M154A), NDM-5 (V88A), NDM-7 (D130A), and NDM-9 (E152A). The mutant variants were transformed into Escherichia coli DH5α. Changes in the activities of alanine mutation variants were determined by E-test. All samples had 32 μg/ml MIC values against ampicillin. The 28th amino acid mutation sample had the highest MIC value against ceftazidime, whereas decreased MIC value for piperacillin. It was observed that the resistance to imipenem was increased in mutant variants D95A, M154A, D130A, and E152A, comparing with P28A and V88A. It was found that NDM-1 has 0.64 μg/ml and the 130th amino acid mutation sample has 0.75 μg/ml meropenem MIC value.
AtıfScopus5WoS5OpenAlex6İncele - MakaleYalnız künye2017Scopus SJRQ2Geochemical and isotopic characteristics of stream and terrace sediments of the harsit stream, NE Turkey
Eker, Çiğdem Saydam
The current study compares and contrasts the elemental concentrations and the Nd, Sr and O isotopic compositions of sediments collected from the Harsit Stream bed sediments (HSBS) and terrace sediments (HSTS). There are positive correlations between Al2O3 and SiO2, TiO2, Na2O and Fe2O3, K2O in HSBS and between Al2O3 and Fe2O3, MnO in the HSTS samples. Major element components of HSBS and HSTS are comparable to average upper continental crust. Both types of sediments are generally classified as greywacke, based on chemical composition and O–Sr isotopic compositions. TheɛNd(0) andɛSr(0) values range from −0.6 to −5.7 and from 7.1 to 45, respectively, in HSBS; and from −0.7 to −4.4 and from 20 to 54, respectively, in HSTS. The δ18O values range from 8.8 to 11.8 (average 10.8) in HSBS and from 11.3 to 13.3 (average 12.2) in HSTS, which are generally controlled by detrital or authigenic minerals in the studied samples. The average chemical index of alteration (CIA) and, plagioclase index of alteration (PIA) values are high in HSTS, whereas the index of compositional variability (ICV) and weathering index (WIP) values are high in HSBS. Several minor differences were observed between HSBS and HSTS in terms of geochemistry and isotopic compositions that reflect different processes involved in their sedimentation.
AtıfScopus10WoS9OpenAlex10İncele - MakaleYalnız künye2019Scopus SJRQ1Performance evaluation of ejector with different secondary flow directions and geometric properties for solid oxide fuel cell applications
Genc, Omer; Timurkutluk, Bora; Toros, Serkan
The mixing chamber length, secondary flow tube inclination angle, diffuser length and diverging angle as well as the direction of secondary flow on the ejector performance are numerically studied. The numerical results of 2560 different design points including the all combinations of the selected parameters indicate that the selected ejector geometric parameters have a great impact on the ejector performance. Within the parameter ranges considered, the best performance based on steam to carbon ratio and the entrainment is obtained from the ejector having a mixing chamber length of 30 mm, secondary flow tube inclination angle of 45°, diffuser length of 90 mm and diffuser diverging angle of 5°, regardless of the secondary flow direction. On the other hand, the parallel flow ejector, where the anode exhaust line flow direction is designed to be parallel to the primary flow direction, is found to exhibit slightly higher steam to carbon ratio and entrainment ratio compared to those of the counter flow ejector. Furthermore, it is seen that the parallel flow ejector can offer wider ranges of the ejector geometric parameters considered for a high performance whereas relatively rigid geometric parameters need to be selected for designing a counter flow ejector.
AtıfScopus17WoS15OpenAlex16İncele - MakaleAçık Erişim2018Scopus SJRQ3ANALYZING THE DYNAMICS OF EBOLA TRANSMISSION WITH RANDOM EFFECTS
Merdan, Mehmet; Bekiryazici, Zafer; Kesemen, Tulay; Khaniyev, Tahir
In this study, a deterministic mathematical model of Ebola transmission is analyzed under random ef-fects. A recent compartmental model of Berge et al. incorporates both direct and indirect transmission in the model. We assume the parameters of this model are normally distributed random variables to investigate the random behavior of disease transmission. Random differential transformation method is used to obtain the ap-proximate expectation of disease recovery. Furthermore, the approximation for expected recovery is modified by using Laplace-Padé method. Comparison of results indicate that the Laplace-Padé modification provides a better approximation. We also interpret the long term random behavior of the disease dynamics using simulation results.
AtıfScopus3WoS2OpenAlex3İncele - MakaleAçık Erişim2019Scopus SJRQ2Volatile constituents and biological properties of essential oils from aerial parts of Gentiana gelida BIEB
Üçüncü, Osman; Karataş, Şeyda Merve; Baltacı, Cemalettin; Karaköse, Mustafa; Türkuçar, Semra Alkan
This work reports the chemical composition, antimicrobial and antioxidant activities of essential oils from the aerial parts of Gentiana gelida BIEB. for the first time in literature. The oils from the aerial parts (flower, leaf and stem) were obtained by Clevenger-type apparatus and characterized by GC-FID and GC-MS. While tricosane (21.67%) was the main component of flower oil, hexadecanoic acid was the most abundant component of leaf and stem oils in ratios 26.46% and 31.89%, respectively. Additionally, all essential oils of G. gelida were investigated for their antimicrobial activity against eight Gram negative bacteria, four Gram positive bacteria and five fungi, using agar dilution method and antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl radical scavenging and Folin-Ciocalteu assays. The flower oil of G. gelida showed stronger antimicrobial and antioxidant activities than those of stem and leaf. The amount of total phenolic content and scavenging activity of the flower oil were found 525.35±8.24 mg GAE/L and 49.30±1.25%, respectively.
AtıfScopus5WoS4OpenAlex4İncele
