Sürdürülebilir Kalkınma Amaçları
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- ArticleYalnız künye2018An experimental study on composite adhesives reinforced with different types of organo-clays
Akpinar, Iclal Avinc; Gültekin, Kürşat; Akpinar, Salih; Gürses, Ahmet; Ozel, Adnan
In this study, the mechanical properties of single lap joints prepared by adding nanoclays with different properties into adhesives with different characteristics (toughened, flexible, paste-type, and rigid) were experimentally investigated. Single lap joints and bulk specimens were produced using DP460, DP125, Araldite 2015, and AV138 as adhesives. High-concentration hydrocarbon-doped organo-clay (HDOC-1) obtained from Çankırı, low-concentration hydrocarbon-doped organo-clay (HDOC-2) obtained from Erzurum, and organo-clay (OC) were incorporated into the adhesives as reinforcements at two different concentrations (1% and 2% wt.). The aluminum alloy AA2024-T3 was used as the adherend material. Evaluation of experiment results showed that both the characteristics of the adhesive (toughened, flexible, paste-type, and rigid) and the different forms of clays significantly influenced failure loads of the joints. Moreover, increasing or decreasing the amount of clay added into the adhesive also affected failure loads of the joints; 1% wt. reinforcement provided the best results.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2018Investigation of mechanical and thermal properties of nanostructure-doped bulk nanocomposite adhesives
Akpinar, Iclal Avinc; Gürses, Ahmet; Akpinar, Salih; Gültekin, Kürşat; Akbulut, Hamit; Ozel, Adnan
In recent years, findings in nanoscience and nanotechnology have deeply influenced many disciplines including the material and mechanical sciences. Polymers including nanostructures have attracted attention as their adoptions in general engineering composites have yielded efficient results. In this study, three different two-component (epoxy-hardener) adhesives were doped with graphene nanoplatelets, graphene oxide nanoplatelets, carbon nanotube, and fullerene C60 at three different rates (0.5%, 1%, and 2% by weight) and the mechanical and thermal properties of the nanocomposite adhesives were examined. The nanocomposite adhesives’ mechanical properties were analyzed via tensile tests and thermal properties were analyzed via Differential Scanning Calorimeter (DSC) thermograms and Fourier Transform Infrared Spectroscopy (FT-IR) spectra. Results showed that doping nanostructures improve the stress-strain capacity of the adhesives. Both mechanical and thermal properties of the nanocomposite adhesives seem to change depending on the amount of nanostructure. Additionally, DSC and FT-IR curves showed an agreement with these improvements in the adhesives’ mechanical properties.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2016The effects of graphene nanostructure reinforcement on the adhesive method and the graphene reinforcement ratio on the failure load in adhesively bonded joints
Gültekin, Kürşat; Akpinar, Salih; Gürses, Ahmet; Eroglu, Zafer; Cam, Salim; Akbulut, Hamit; Keskin, Zeki; Ozel, Adnan
This study experimentally determines the tensile failure load of the nanocomposite adhesive - obtained by adding nanostructures to the adhesive - using four different methods in single-lap joints. For the study, adhesively bonded single-lap joints were produced by using DP460 liquid structural epoxy as the adhesive, AA2024-T3 aluminum alloy as the adherend and graphene as the nanostructure. When the failure load obtained from the experiments was examined, it was seen that, while the nanostructure-reinforced methods indicated in the literature have a great effect on the failure load of the joint and the standard deviation, a new method developed in this study increased the failure load of the joint and minimized the standard deviation. These improvements increased the reliability and reproducibility of the joint.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2015Determination Of Levels Of Use Of Basic Process Skills Of High School Students
Gürses, Ahmet; Çetinkaya, Songul; Dogar, Cetin; Sahin, Elif; Uzunboylu, H
It aims to determine the abilities of use of basic process skills of the students and the levels of conceptual learning of the students as oriented to general chemistry topics. The sampling comprises 160 students whose were studying at 10th and 11th grades of seven different high schools in Turkey. The study design is based on Survey model. The questionnaire prepared by considering the levels of conceptualization of chemistry topics of the students aims to measure their ability of use of science process skills. The questions and items were selected in the manner that it covers basic skills such as observation, classification, measurement, the sensing of space-time relationship and communicating, and also classified on the Bloom Taxonomy of cognitive development which consist of knowledge, comprehension, application, analysis, synthesis, and evaluation. The results from analysis of variance (ANOVA) show that. The differences between students' grade levels, score and order of admission to high school and the type of school have a significantly effect on the potential of use of basic process skills. (C) 2015 The Authors. Published by Elsevier Ltd.
RDL Kalıcı Kaydıİncele - Book ChapterYalnız künye2015Removal of Organic Dyes from Industrial Effluents: An Overview of Physical and Biotechnological Applications
Ejder-Korucu, Mehtap; Gürses, Ahmet; Dogar, Çetin; Sharma, Sanjay K.; Açikyildiz, Metin; Sharma, SK
The textile industry produces a large amount of dye effluents, which are highly toxic as they contain a large number of metal complex dyes. The use of synthetic chemical dyes in various industrial processes, including paper and pulp manufacturing, plastics, dyeing of cloth, leather treatment and printing has increased considerably over the last few years, resulting in the release of dye-containing industrial effluents into the soil and aquatic ecosystems. The textile industry generates highly polluted wastewater and its treatment is a very serious problem due to high total dissolved solids (TDS), the presence of toxic heavy metals and the non-biodegradable nature of the dyestuffs present in the effluents. There are many processes available for the removal of dyes by conventional treatment technologies including biological and chemical oxidation, coagulation and adsorption, but they cannot be effectively used individually. Many approaches, including physical, chemical and/or biological processes have been used in the treatment of industrial wastewater containing dye, but such methods are often very costly and not environmentally safe. Furthermore, the large amount of sludge generated and the low efficiency of treatment with respect to some dyes have limited their use.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2014Analysis of the factors that influence the attitudes of elementary students for the internet
Dogar, Cetin; Kaplan, Mesut; Gürses, Ahmet; IIhan, AC; Miralay, F
It is important that the level of students' access to the internet in the information age. The purpose of this study is to determine certain variables of primary school students on their attitudes to the Internet. Working in the academic year 2011-2012 was made and research method is carried out by using survey method. The sampling consists of 272 elementary school students. Data was obtained by using Internet Attitude Scale (.874) of a 20-item and interpretative analysis were applied to the data. The results showed that preference of binding sites to the Internet, educational level, the Examination of Degree Identity(EDI), and gender aspects of the statistically significant differences on primary students' attitudes toward the Internet were found. (C) 2013 The Authors. Published by Elsevier Ltd.
RDL Kalıcı Kaydıİncele - Conference ObjectYalnız künye2014Investigation of thermal properties of PUF/clay nanocomposites
Doʇar, Çetin; Gürses, Ahmet; Karaca, Semra; Köktepe, Sevda; Mindivan, Ferda; Güneş, Kübra
This study aims to investigate the thermal properties of phenol-urea-formaldehyde (PUF)/organoclay nanocomposites synthesized at various organoclay ratios by using their DSC thermograms, FT-IR spectra, and HRTEM images. From these analyses, it has been concluded that at low organoclay ratios, the platelets exfoliated of organoclay, which dispersed homogenously in the polymer matrix, created a positive effect in conformational arrangement as suitable to crystallization of PUF chains. DSC analyses revealed that two endotherms in all thermograms imply the presence of linear UF, PF, and PUF chains together. Low organoclay content may also lead to a cross-linked lattice, being more predominant than the linear chain arrangement.
RDL Kalıcı Kaydıİncele - Conference ObjectYalnız künye2014The investigation of electrokinetic behaviour of micro-particles produced by CTA + ions and Na-montmorillonite
Gürses, Ahmet; Güneş, Kübra; Mindivan, Ferda; Korucu, Mehtap Ejder; Açikyildiz, Metin; Doʇar, Çetin
In this study, the interactions between clay platelets and CTA + ions in aqueous dispersions of Na-montmorillonite (Na-MMT) were examined in detail by using electro kinetic parameters such as electrical conductivity and zeta potential and by considering XRD patterns and d-spacing values of the organoclay samples as a function of both surfactant concentration (CTAB, cetyltrimethylammonium bromide) and clay amount. The amounts adsorbed and zeta potentials of the particles increased with an increase in the initial concentration of CTAB in parallel with the electrical conductivity values. The adsorption mechanisms which predominate at certain ranges of CTAB concentration were proposed and schematized by considering the d-spacing values calculated and the zeta potential values of particles. For the different solid/liquid ratios, the initial concentrations of CTAB, in which appeared significant increases in the d-spacing values were found as 200, 280 and 300 mg/L, respectively. The d-spacing values which correspond to these concentrations are, respectively 1.82, 1.82 and 1.68 nm. It is remarkable that at first three solid/liquid ratios, a "stress region" to be related with hydrophobic binding appeared. Thermodynamic parameters such as Gibbs free energy (ΔG o ), isosteric enthalpy (ΔH o ads ) q , and isosteric entropy (ΔS o ads ) q were also calculated by using experimental data. These parameters indicate that adsorption of CTAB onto Na-montmorillonite is spontaneous and exothermic in the temperature range studied. The ((ΔS o ads ) q , (ΔH o ads ) q and (ΔG o )) values calculated are highly negative. This reveals that the adsorption of CTA + ions at the interlayer region of clay carried out with more order stacking of CTA + ions.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2012Preparation of PEO/Clay Nanocomposites Using Organoclay Produced via Micellar Adsorption of CTAB
Gürses, Ahmet; Ejder-Korucu, Mehtap; Doǧar, Çetin
The aim of this study was the preparation of polyethylene oxide (PEO)/clay nanocomposites using organoclay produced via micellar adsorption of cethyltrimethyl ammonium bromide (CTAB) and their characterisation by X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectra, and the investigation of certain mechanical properties of the composites. The results show that the basal distance between the layers increased with the increasing CTAB/clay ratio as parallel with the zeta potential values of particles. By considering the aggregation number of CTAB micelles and interlayer distances of organo-clay, it could be suggested that the predominant micelle geometry at lower CTAB/clay ratios is an ellipsoidal oblate, whereas, at higher CTAB/clay ratios, sphere-ellipsoid transition occurs. The increasing tendency of the exfoliation degree with an increase in clay content may be attributed to easier diffusion of PEO chains to interlayer regions. FT-IR spectra show that the intensity of Si-O stretching vibrations of the organoclays (1050 cm -1) increased, especially in the ratios of 1.0 g/g clay and 1.5 g/g clay with the increasing CTAB content. It was observed that the mechanical properties of the composites are dependent on both the CTAB/clay ratios and clay content of the composites.
RDL Kalıcı Kaydıİncele - Conference ObjectYalnız künye2012Biosorption of CR (VI) onto pseudevernia furfuracea /aqueous solution interface
Gürses, Ahmet; Özkan, Esra; Doǧar, Çetin
This study addresses the removal of a heavy metal, Cr (VI), from aqueous solutions by using dried Psedeuvernia furforcea biomass as biosorbent. The effects of factors, such as the initial chromium concentration, contact time, temperature, biosorbent dosage and mixing rate on biosorption of the heavy metal was investigated. Furthermore, the fitting of adsorption data on Langmuir, Freundlich, BET, Temkin, Redlich-Peterson, Henderson, Smith, Halsey and Harkins-Jura adsorption isotherm models was investigated. In order to explain the metal-functional group binding mechanisms, FTIR analysis was carried out. The sorption equilibrium time was determined to be 8 hours. The amount of Cr (VI) adsorbed onto Psedeuvernia furforcea increased with increasing sorbent dosage and increasing temperature indicating endothermic nature of biosorption process. The results suggest that the physical interactions between sorbent particles and sórbate ions play an important role for the adsorption of Cr (VI) onto the biosorbent. It was found that the biosorption data of Cr (VI) by Psedeuvernia furforcea biomass were fit on the Freundlich adsorption isotherms at 293, 313, and 333K. From the experimental results, it can be concluded that Psedeuvernia furforcea can be used as an economical sorbent in the removal of these heavy metal ions.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2011Determining the relationship between students' choice of profession and mission and vision of their high school
Gürses, Ahmet; Kuzey, Büşra; Mindivan, Ferda; Dogar, Çetin; Güneş, Kübra; Yolcu, H. Hasan; Akcamete, G; Uzunboylu, H; Oulmu, S; Karahoca, A
In this study, the investigation of relationship between students' choice of profession and mission and vision of their high school was aimed. The research sample consisted of 180 students attending ninth and twelve grades at three state high schools which to get students with choice examination in Erzurum. The data were obtained by semi-structured interviews. The interviews were conducted in the first semester of 2009-2010 education semester. The data are separated which are obtained from common and different answer and the evaluations are made according to this categories. The 50-60 % of students of A high school said not to be their choice entering this school and the 9 % of students are determined to prefer from themselves field. The 24% of student made the choice exclusive of their field as law, teaching. An important division of student of high school of teacher (70-80%) indicated to made the choice of themselves school, but the students determine who prefer the B high school is only factor which is inclined them They thought to utilize this environment of competition. The students of C high school are determined to make suitably the choice of occupation. However the students of B high school determined to tend majority exclusive of their field. Another conclusion is meanings to be imputed relating the concept of occupation. Although the students of B high school describe as business winning respectability at the rate of 44%, they see it as business making to provide a material earning at the rate of 30%. Although the students of A high school see as a business making to provide a material earning it at the rate of 60%, they describe as stopping on themselves foot at the rate of 24%. While the students of C high school see to provide a material earning at the rate of 50%, they see as a business winning respectability it.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2010Facilitating conceptual change in students understanding of electrochemical concepts; [Facilitar el cambio conceptual en el entendimiento de los estudiantes sobre conceptos de electroquímica]
Dogar, Çetin; Gürses, Ahmet; Geban, Ömer
The main purpose of this study is to investigate the effectiveness of conceptual change approach oriented instruction over traditionally designed instruction on students' understanding of electrochemical cell concepts. Sampling consists of a total of 55 students (age range of 17-18) on two Grade 11 classes of a high school. Prior to instruction, students in both groups were pre-tested in order to determine their previous understanding of electrochemistry, electrochemistry concept test (ECT), science process skills (SPST) and attitude toward chemistry (ATSC) as a school subject. In addition to these, the students' views in the experimental groups related to the computer simulations exercises were determined at the end of the study. After instruction over a period of four weeks, data was analyzed with two-way analysis of covariance (ANCOVA) using science process skill scores as covariate and independent samples t-test was used to compare the students' attitudes scores. The results showed that the experimental group a significantly higher mean scores with respect to achievement related to electrochemistry concepts than the traditionally designed chemistry instruction group. In addition, science process skills were a strong predictor in understanding electrochemistry concepts. Students' attitudes were not changed by treatments. In addition, it was determined that the students in experimental groups displayed a positive attitude toward computer simulations.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2010Thermodynamics and kinetic studies of biosorption of a basic dye from aqueous solution using green algae Ulothrix sp.
Doǧar, Çetin; Gürses, Ahmet; Açikyildiz, Metin; Özkan, Esra
This study addresses removal of a basic dye, methylene blue, from aqueous solutions by using dried Ulothrix sp. biomass as biosorbent. The effects of the initial dye concentration, contact time, temperature, solution equilibrium pH, biosorbent dosage, and mixing rate on biosorption of the dye have been investigated. It was found that 30 min is sufficient in order to reach adsorption equilibrium. The amount of methylene blue adsorbed onto Ulothrix sp. increased with increasing equilibrium pH and mixing rate, in contrary, it decreased with increasing temperature and sorbent dosage. The process followed the pseudo-second-order kinetic model. The isosteric enthalpy and entropy values were calculated as -11.8 kJ/mol and 37.5 J/(mol K), respectively. In addition, the results suggest that the physical interactions between sorbent particles and sorbate ions play an important role for the adsorption of methylene blue onto the biosorbent.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2010Measurement of secondary school student's test-anxiety levels and investigation of their causes
Gürses, Ahmet; Kaya, Özgür; Doǧar, Çetin; Günes, Kübra; Yolcu, H. Hasan; Keser, H; Ozcinar, Z; Kanbul, S
Test anxiety is concerned about a large portion of our society (students, family environment). The portion affected from the test anxiety is increasing year by year. Test anxiety is not related with studying or studying much. The idea that studying much and getting new knowledge cause anxiety and stress is common. A student being tired by studying much can rest after a brief relaxation and exercise. What creates the anxiety is the fear of being unsuccessful and the thought that is the end of some values because of the failure. Determination of students' test anxiety is very important for the success in applied teaching activities. In this study intending to determine secondary school students' test anxiety, test anxiety scale and data collected from interviews were evaluated from the view of gender, class grades and enrolled educational institutions. After the analyses gained by descriptive statistical techniques and One-Way ANOVA, it was found that the students had mid-level test anxiety, and girls had higher test anxiety level than boys.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2010An investigation on teachers to whom positive attitudes were developed by students
Gürses, Ahmet; Çamuroǧlu, Tuba; Açikyildiz, Metin; Doǧar, Çetin; Keser, H; Ozcinar, Z; Kanbul, S
In this study, it is aimed to analyze the effects of out of school activities of teachers to whom positive attitudes were developed by the students in instructional process and heir some personal features on developed attitude. For this aim, semi-structured interviews were applied to 80 students and 10 teachers working in three different high schools under the authority of Erzurum Directorate of National Education in the first semester of the academic year 2009-2010. After the analyses of gained data, it was found that teachers' personal features are much more effective than their professional knowledge in the process of developing positive attitudes.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2010Science and social science teacher's attitudes towards project studies
Gürses, Ahmet; Tutar, Zafer A.; Doǧar, Çetin; Mindivan, Ferda; Açikyildiz, Metin; Gözöm, Seda; Keser, H; Ozcinar, Z; Kanbul, S
This study aims to determine the ideas about project and project studies of teachers working at social and science branches of high schools. To accomplish this, a survey including twenty-five items about project attitudes scale and personal information was administrated to 10 social branch teachers and 15 science branch teachers working in Erzurum, Turkey. Studies of frequency, arithmetic mean, percentage, t-test and ANOVA techniques were used to analyze the obtained data. The results show that teachers are more optimistic in social branches towards project and project studies than those working in science branches. In addition, there is no statistically meaningful relationship among science and social science teachers' approaches to project studies, teachers' experiences, academic careers and project attendance. Finally, with results, suggestions on the effective usage of project studies are given.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2010The investigation of harmony between teacher's thoughts on nature of learning and their applied teaching activities in teaching and learning process
Gürses, Ahmet; Çaǧlayan, Dilek; Doǧar, Çetin; Yolcu, H. Hasan; Korucu, Mehtap Ejder; Köktepe, Sevda
This study is carried out in order to determine what a relation between different branch teachers' thoughts on nature of learning and these teachers' applied teaching activities in school exists. For this aim, observation rapports as data gathering instrument were created in order to assign teachers' teaching methods. Therefore, an interview was prepared to find out the thoughts about nature of learning. The observations and interviews were applied to 15 teachers working at different branches of different high schools like Ziya Gökalp High School, Nevzat Karabaǧ Anatolian Teacher Training High School, Erzurum High School, Nenehatun Girls High School, Cumhuriyet High School, Kazim Karabekir Industrial Vocational High School, 3 Temmuz High School, İMKB High School, Atatürk High School, Rifki Salim Burçak Girls Vocational High School and Atatürk Industrial Vocational High School which are under the authority of Erzurum Directorate of National Education. After the analyses of data, it was found that there is no harmony between teachers' thoughts on nature of learning and their teaching methods chosen in teaching and learning processes.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2007Adsorption studies on the treatment of textile dyeing effluent by activated carbon prepared from olive stone by ZnCl2 activation
Uǧurlu, Mehmet; Gürses, Ahmet; Doǧar, Çetin
This study aimed to investigate the removal of a reactive dye from aqueous solution by adsorption. Activated carbon prepared from olive stone, an agricultural solid by-product, was used as adsorbent. Different amounts of activating agent (ZnCl2) and adsorbent particle size were studied to optimise adsorbent surface area. The adsorption experiments were conducted at different process parameters such as adsorbent dose, temperature, equilibrium time and pH. The experimental results showed that at equilibrium time 120 min, optimum pH ranged between 3 and 4, and adsorbent dosage was 2.0 g 200 ml-1. While the kinetic data support pseudo-second order, a pseudo-first order model shows very poor fit. Adsorption isotherms were obtained at three different temperatures (288, 298 and 308 K). The fitness of adsorption data to the Langmuir and Freundlich isotherms was investigated. In addition, the thermodynamic parameters such as isosteric enthalpy of adsorption (ΔHads)y, isosteric entropy of adsorption (ΔSads)y and free energy of adsorption ΔG0 ads were calculated. BET surface area measurements were made to reveal the adsorptive characteristics of the produced active carbon. The surface area of the activated carbon produced with 20% w/w ZnCl2 solution was 790.25 m2 g-1.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2006An investigation on effects of various parameters on viscosities of coal-water mixture prepared with Erzurum-Aşkale lignite coal
Gürses, Ahmet; Açikyildiz, Metin; Doǧar, Çetin; Karaca, Semra; Bayrak, Ramis
In this study the effects of parameters such as coal loading (wt.%), the initial pH of mixture, the addition of various electrolytes, surfactants and temperature on the viscosity and rheologic parameters of coal-water mixture (CWM) have been investigated. The apparent viscosity was measured with a RV8-Brookfield rotating type viscosimeter. The additives used were AlCl3 and K2HPO4 as the electrolytes and Cetyltrimethyl Ammonium Bromide (CTAB), Sodium Dodecyl Sulphate (SDS) and Borrosperse NA-3A as the surfactants. It was found that the most effective additives, in terms of the viscosity reduction, were CTAB and K2HPO4, and that the CWM which had coal concentrations up to 50% (based on the weight of dry coal) could be prepared by using each additives. In addition, the viscosities of CWM with increasing temperature were found to increase at low speed, and decrease at high speed.
RDL Kalıcı Kaydıİncele - Conference ObjectYalnız künye2005Effect of temperature for the adsorption of methylene blue onto activated carbon produced from waste dogrose seeds
Gürses, Ahmet; Doǧar, Çetin; Açikyildiz, Metin; Özkan, Esra; Bayrak, Ramis
Activated carbon, produced from dogrose (Rosa section Caninae) seeds, was used for the removal of methylene blue (basic dye). Adsorption studies were carried out at 20°C and 40°C at various initial dye concentrations (20, 40, 60, 80, and 100 mg/L) and at different lengths of time (15, 30, 60, and 120 min). Adsorption isotherms of the basic dye on the prepared adsorbent were determined and correlated with common isotherm equations. Fitting of the isotherm data to the BET adsorption isotherm model was better in high concentration ranges than in the other models. Thermodynamic parameters such as change in isosteric adsorption enthalpy (ΔH)y and isosteric adsorption entropy (ΔS)y were also determined to 40.8 kJ and 0.141 kJ, respectively. It was concluded that the adsorption of methylene blue increases with increasing temperature. BET model fitting indicates that the hydrophobic interactions between the dye and the produced active carbon at the first layer and the dipole-dipole interactions between methylene blue molecules and the adsorbed molecules at the secondary layer predominate. To investigate the adsorptive characteristics of the produced active carbon, porosity and BET surface area measurements were made.
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