Seasonal variation in disinfection by-product concentrations in İzmir drinking water

Thesis (Master)--Izmir Institute of Technology, Environmental Engineering, Izmir, 2007Includes bibliographical references (leaves: 80-85)Text in English; Abstract: Turkish and Englishix, 85 leavesThe goal of this study was to investigate the seasonal variation in disinfection byproduct (DBP) concentrations in drinking water zmir. In accordance with this aim, drinking water samples were collected from tap water of five sampling points in the distribution system of three different water sources (Tahtalı Reservoir, Balçova Reservoir and ground water) during a 10 month period, from June 2006 to April 2007. The samples were analyzed by GC-ECD according to EPA Method 551.1. In addition, while the organic matter content (measured as NPOC) and bromide ion concentration were measured in samples from Tahtalı and Balçova Water Treatment Plants, other parameters including pH, temperature and chlorine dose were obtained from the treatment plants. These parameters were used as explanatory variables in the multivariate regression analysis to construct statistical models for DBPs. Trihalomethanes were the most abundant DBPs in all samples, followed by haloacetonitriles, chloropicrin and halogenated ketones. The mean total trihalomethanes (TTHMs) concentration of Balçova, Narlıdere and Güzelbahçe was 20.78 ppb while it was 94.71 ppb at Hatay. Concentrations of DBPs in all sampling locations were found to be the highest in spring and lowest in summer and fall. Although TTHM levels in all samples were found to be in accordance with the current drinking water regulations of Turkey, 41 % of the samples from Hatay exceeded the level that will be come into effect in 2012. Multivariate regression analysis suggested that water temperature and total chlorine dose were the most effective parameters for DBPs. In addition, simple regression analysis between total haloacetonitriles and TTHMs revealed a very high correlation (R2.0.83). Logistic regression models were able to predict the probability of exceedance of the selected TTHM thresholds with 76 % efficiency

Experiencing technology integration in education: children's perceptions

The purpose of this phenomenological study was to explore the experiences of six children using technologies in their education. Data were collected via in-depth interviews, classroom observations, and home observations. The results showed that students have commonperceptions toward their experience with technology integration. Furthermore, the following four themes emerged; the value of technology, authority over learning, misuses and misconceptions, and the border of integration

İnce Kompozit Levhalarda Anizotrop Termal Gerilme Analizi

Konferans Bildirisi-- İstanbul Teknik Üniversitesi, Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2017Conference Paper -- İstanbul Technical University, Theoretical and Applied Mechanical Turkish National Committee, 2017Bu çalışmada, iki farklı malzemeden imal edilmiş kompozit levhaların doğrultuya bağımlı sıcaklık değişimi etkisi altında, birleşim yüzeyi civarında termal gerilme dağılımı incelenmiştir. Bu bölgede ayrıca levhalardan birinde modellenen kusurlar civarında gerilme hali ve gerilme yığılması incelenmiştir. Bahsedilen etki ile eğilme davranışı gösteren modelde gerilme analizi fotoelastisitenin mekanik modelleme yöntemi ile yapılmıştır. Geliştirilen modelde cam levha ile bununla aynı boyutlardaki Araldit levha birleşimi imal edilmiştir. Araldit levhanın düzlemi içerisindeki birbirine dik iki eksen doğrultusunda iki farklı sıcaklık etkisine eşdeğer elastik şekil değiştirmeler mekanik olarak modellenmiştir. Ayrıca bu levhada açılan oyuklar civarında gerilme dağılımı elde edilmiştir.In this work, the distribution of the thermal stress around the interface of the composite bimetal plates under the anisotropic effect of thermal change has been analyzed. Furthermore, the state of stress concentration near the defects modeled on one of the plates has been investigated. The stress analyses have been performed by the method of mechanical modeling of photoelasticity on the model which exhibits the bending behavior under the mentioned effect. The developed model of the composite was produced by a glass and an Araldite plates whose dimensions are the same. The elastic strains have been mechanically modeled which are equivalent to the thermal effects in the plane of the plate different in two perpendicular directions. Moreover, the stress distribution has been obtained around the cavities formed on this plate

Nonlinear behaviour of epoxy and epoxy-based nanocomposites: an integrated experimental and computational analysis

The focus of this study is on the nonlinear mechanical properties of epoxy and epoxy-based nanocomposites, exploring frequency and strain amplitude dependency. Nanocomposite samples of epoxy are reinforced with fumed silica (FS), halloysite nanotubes (HNT) and Albipox 1000 rubber (Evonik) nanoparticles. Considering these particles have different geometries and stiffnesses, they are expected to have significantly different influences on the mechanics of the resulting composite. To enhance the reliability of the results and to reveal the impact of nanofillers on the mechanics of the material more distinctly, the manufacturing process is designed to be the same for all the specimens within the same material groups to eliminate the effects of the manufacturing process. The comprehensive characterization process consists of Fourier-Transform InfraRed Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Dynamic Mechanical Analysis (DMA). The DMA tests are designed so that the material properties are measured depending on the vibration frequency and strain amplitude. Finally, the characterized nonlinear dynamic properties of these nanocomposites are used as the input material properties into a numerical model. In this simulation, a cantilever beam with representative nonlinear material properties, for these nanocomposites, is created, as example and its forced response is plotted under the same levels of excitation in the frequency domain. Key effects of the different nanofillers are identified using the resonance behavior, primarily focusing on the stiffness and damping of the epoxy-based nanocomposites. These experimental and numerical procedures followed show the significant impact of the nanoparticle reinforcements on the nonlinear nature of these epoxy-based composites

Learning to communicate computationally with Flip: a bi-modal programming language for game creation

Teaching basic computational concepts and skills to school children is currently a curricular focus in many countries. Running parallel to this trend are advances in programming environments and teaching methods which aim to make computer science more accessible, and more motivating. In this paper, we describe the design and evaluation of Flip, a programming language that aims to help 11–15 year olds develop computational skills through creating their own 3D role-playing games. Flip has two main components: 1) a visual language (based on an interlocking blocks design common to many current visual languages), and 2) a dynamically updating natural language version of the script under creation. This programming-language/natural-language pairing is a unique feature of Flip, designed to allow learners to draw upon their familiarity with natural language to “decode the code”. Flip aims to support young people in developing an understanding of computational concepts as well as the skills to use and communicate these concepts effectively. This paper investigates the extent to which Flip can be used by young people to create working scripts, and examines improvements in their expression of computational rules and concepts after using the tool. We provide an overview of the design and implementation of Flip before describing an evaluation study carried out with 12–13 year olds in a naturalistic setting. Over the course of 8 weeks, the majority of students were able to use Flip to write small programs to bring about interactive behaviours in the games they created. Furthermore, there was a significant improvement in their computational communication after using Flip (as measured by a pre/post-test). An additional finding was that girls wrote more, and more complex, scripts than did boys, and there was a trend for girls to show greater learning gains relative to the boys

Sorption of platinum on immobilized microorganisms for its on-line preconcentration and chemiluminescent determination in water samples

Fungi of the type Aspergillus sp. were immobilized on a cellulosic resin and used as a biosorbent for the on-line preconcentration and separation of Pt(IV) ions prior to their chemiluminescent determination via flow injection analysis. Biosorption and elution conditions were optimized, and the results compared to biosorbents based on the use of Chlorella vulgaris algae and Saccharomyces cerevisiae yeast in terms of preconcentration and selective retention of Pt(IV). The immobilized fungi presented here have a high potential for use in platinum biosorption. The procedure exhibits the currently lowest limit of detection (0.02 ng mL−1 of Pt) and very high selectivity. The procedure was applied to the determination of Pt(IV) in river water, road run-off, and wastewater samples

Use of nanomaterials in the pretreatment of water samples for environmental analysis

The challenge of providing clean drinking water is of enormous relevance in today’s human civilization, being essential for human consumption, but also for agriculture, livestock and several industrial applications. In addition to remediation strategies, the accurate monitoring of pollutants in water sup-plies, which most of the times are present at low concentrations, is a critical challenge. The usual low concentration of target analytes, the presence of in-terferents and the incompatibility of the sample matrix with instrumental techniques and detectors are the main reasons that renders sample preparation a relevant part of environmental monitoring strategies. The discovery and ap-plication of new nanomaterials allowed improvements on the pretreatment of water samples, with benefits in terms of speed, reliability and sensitivity in analysis. In this chapter, the use of nanomaterials in solid-phase extraction (SPE) protocols for water samples pretreatment for environmental monitoring is addressed. The most used nanomaterials, including metallic nanoparticles, metal organic frameworks, molecularly imprinted polymers, carbon-based nanomaterials, silica-based nanoparticles and nanocomposites are described, and their applications and advantages overviewed. Main gaps are identified and new directions on the field are suggested.publishe

Enzymatic degradation of phthalic acid esters

Thesis (Doctoral)--Izmir Institute of Technology, Chemical Engineering, Izmir, 2013Includes bibliographical references (leaves. (leaves: 81-89)Text in English; Abstract: Turkish an Englishxiii, 89 leavesEndocrine disrupting compounds (EDCs) are environmental pollutants which interfere with the hormone system even at low concentrations resulting in adverse health effects on both human and wildlife. In this study, we aimed to investigate enzymatic degradation of diethylhexyl phthalate (DEHP) and diethyl phthalate (DEP) using both commercial porcine pancreas lipase and lipase from recombinant E.Coli strains that contain lipase genes from thermophilic Bacillus sp. isolated from Balçova Geotermal region in İzmir. Incubation of 20 mg/L DEHP with 20,000 U/L PPL enzyme for 7 days resulted in formation of monoethyl phthalate (MEHP), phthalic acid (PA), and dimethyl phthalate (DMP) which are the possible metabolites of DEHP. The percent decrease in DEHP (20 mg/L) was found to be 92% compared to positive control samples. In the case of DEP, about 53% decrease was obtained after incubation with 20.000 U/L for 7 days. Hydrolysis constants for DEHP ranged between 0.13 and 0.22 d-1, whereas those for DEP ranged 0.43 and 0.54 d-1. As a result of enzymatic hydrolysis of DEHP (1-20 mg/L) with 4000 U PPL enzyme, DEP was produced as hydrolysis product of DEHP after 44 h. In the case of DEP (1-20 mg/L) incubated with 4000 U crude lipase solution for 140 h, DMP was obtained as a possible product of transesterification reaction. The maximum rate (Vmax) of enzymatic hydrolysis reaction for DEHP and DEP was calculated as 0.79 mg/L.h and 1.83 mg/L.h, respectively. The Michealis-Menten constants (Km) for enzymatic hydrolysis of DEHP and DEP were calculated as 2.45 and 2.12 mg/L, respectively