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Use of nano zero-valent iron coated coffee grounds for removal of Zn(II) and Ni(II) from aqueous solutions
Get PDFThis research investigates the adsorption capacity of a novel composite material, namely nano zero-valent iron coated coffee grounds (nZVI-CG), for removal of zinc (Zn) and nickel (Ni). nZVI particles were synthesized and immobilized to the surface of waste coffee grounds (CG) using the ultrasonic-assisted liquid phase method. Characterization of synthesized nZVI-CG composite and bare CG showed that nZVI coating has increased the surface area significantly. Batch tests were conducted to examine the effects of pH, reaction time and initial metal concentrations on Zn2+ and Ni2+ removal. At an initial metal concentration of 10 mg-Ni/L and 10 mg-Zn/L, nZVI-CG removal rates for Zn2+ and Ni2+ were observed as 98.89% and 97.29%, respectively; while removal rates of bare CG have remained at 51% (Zn2+) and 48.1% (Ni2+). Moreover, acidic conditions were observed to deteriorate Ni2+ and Zn2+ adsorption since most functional groups of the metals were protonated. Increasing initial nickel and zinc concentrations decreased removal rates. While the model fittings improved with increasing pH, in the case of nZVI-CG, Langmuir isotherm gave the best fits for Ni2+ and Zn2+ at pH 5 and 7. Also, our experimental results followed the pseudo-second-order kinetic model, regardless of the used adsorbent. Consequently, our results showed that nZVI-CG composite material is a promising alternative adsorbent for pilot scale metal removal/recovery applications
Effect of electric field on interfacial thermal resistance between silicon and water at nanoscales
No full text5th World Congress on Mechanical, Chemical, and Material Engineering, MCM 2019; 15 August 2019 through 17 August 2019In this study, heat transfer rate of a nano-confined liquid is controlled by applying an electric field parallel to the heat transfer direction. Molecular Dynamics simulations are performed for deionized water confined between silicon slabs, where their surfaces oppositely charged to create an electric field perpendicular to the silicon wall to promote the electrowetting. Electric field strengths used in this study are 0, 0.18 and 0.35 V/nm. To investigate the effect of electric field on heat transfer, first water density profiles near the silicon walls are examined. Results shows that by applying electric field, water molecules near the silicon walls develop layering, which indicates the increased solid/liquid coupling. With the increasing electric field strength, an increase in the peak of the density layering is observed. Furthermore, heat transfer at the solid/liquid interface is characterized with the Kapitza length values. The results show that applying electric field reduces the interfacial thermal resistance between water and silicon due to the increased solid/liquid coupling and doubles the total heat flux. © 2019, Avestia Publishing
Preseramik polimerden seramik fiberler üretimi ve karakterizasyonu
No full textThesis (Master)--Izmir Institute of Technology, Materials Science and Engineering, Izmir, 2019Includes bibliographical references (leaves: 36-38)Text in English; Abstract: Turkish and EnglishCeramic fibers which are classified as oxide and non-oxide fibers are preferred to use in applications which are carried out at high temperature since they have high strength, low thermal expansion, corrosion, and oxidation resistance. Non-oxide fibers are generally produced using preceramic polymers by the spinning method. The production of ceramic materials using preceramic polymers by spinning method is more advantageous than other methods since the production of complex materials could be achieved at lower temperatures. The preceramic polymer family is basically classified as polysiloxane, polysilazane and polycarbosilane. In this thesis, it was aimed to obtain ceramic fiber in the most economical way. In this context, a spinning device was designed and made. Additionally, polysiloxane which is the most economical preceramic polymer was used to produce ceramic fiber. Polysiloxanes were spun by melt spinning. Obtained fibers were cured by different methods. As a result of pyrolysis, 65-130 μm thickness SiOC fibers were achieved.Oksit ve oksit olmayan lifler olarak sınıflandırılan seramik liflerin, yüksek
dayanıma, düşük ısıl genleşmeye, korozyona ve oksidasyona karşı dirence sahip oldukları
için yüksek sıcaklıkta gerçekleştirilen uygulamalarda kullanılması tercih edilir. Oksit
olmayan fiberler genellikle eğirme yöntemiyle preseramik polimerler kullanılarak
üretilir. Eğirme yöntemi ile preseramik polimerler kullanarak seramik malzeme üretmek
diğer yöntemlere kıyasla daha avantajlıdır çünkü karmaşık yapılı malzemeler daha düşük
sıcaklıklarda üretilebilir. Preseramik polimer ailesi temel olarak polisiloksan, polisilazan
ve polikarbosilan olarak sınıflandırılır. Bu tezde, seramik elyafın en ekonomik şekilde
elde edilmesi amaçlandı. Bu bağlamda, bir eğirme cihazı tasarlandı ve yapıldı. Ayrıca;
seramik elyafı üretmek için en ekonomik preseramik polimer olan polisiloksanlar
kullanıldı. Polisiloksanlar eriyik (melt) eğirme yöntemiyle elde edildi. Fiberler farklı
yöntemlerle kürlendi. Piroliz sonucunda 65-130 μm kalınlığında SiOC fiberler elde
edildi
Study of the B +→ J / ψ Λ ¯ p decay in proton-proton collisions at √s = 8 TeV
No full textA study of the B+-> J/psi = 8 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.6 fb(-1), is presented. The ratio of branching fractions B+-> J/psi B+-> J/psi K is measured to be (1.054 +/- 0.057(stat) +/- 0.035(syst) +/- 0.011 where the last uncertainty reflects the uncertainties in the world-average branching fractions of and K*(892) (+) decays to reconstructed final states. The invariant mass distributions of the J/psi, J/psi systems produced in the B+-> J/psi decay are investigated and found to be inconsistent with the pure phase space hypothesis. The analysis is extended by using a model-independent angular amplitude analysis, which shows that the observed invariant mass distributions are consistent with the contributions from excited kaons decaying to the (Lambda) over barp system
Removal of metals and metalloids from acidic mining lake (AML) using olive oil solid waste (OSW)
No full textThe acidic mining lakes have low pH values and high metal and metalloid concentrations. In this study, the ability of low-cost olive oil solid waste (OSW) to remove Al, As, Cd, Fe, B and Ti ions from aqueous solutions in short term has been evaluated. Adsorption capacities (mgg(-1)) of OSW (1:5-1:10w/v) were 764.06-411.75 for Al, 0.26 for As, 0.07-0.14 for Cd, 2181.5-2406.5 for Fe, 23.70-82.50 for B and 0.12-0.0.34 for Ti. OSW addition increased acidic mine water (AMW) pH from 2.41 to 3.2 with 1:5 and from 2.41 to 2.7 to 1:10 mixing ratio, respectively, after 10min. The best gradual decrease has been observed with different ratio of OSW applications on B and Ti concentrations. OSW adsorbs 32.41% and 62.68% of B at the ratio of 1:5 and 1:10 and 55.29% and 83.04% of Ti at the ratio of 1:5 and 1:10 (OSW:AMW) mixtures, respectively. The results show that OSW has great potential for metal removal from acidic mine water
Ultrason altında mikroköpükçüklerin stabilitelerinin arttırılması
No full textThesis (Doctoral)--Izmir Institute of Technology, Biotechnology and Bioengineering , Izmir, 2019Includes bibliographical references (leaves: 168-182)Text in English; Abstract: Turkish and EnglishMicrobubbles are used as effective contrast agents in ultrasound imaging. However, low stability of the microbubbles limits their use for prolonged period of time in medical applications. The aim of this dissertation is to increase the stability of microbubbles under ultrasound. The stability and acoustic response of microbubbles were investigated under ultrasound as a function of their shell composition. Microbubbles were fabricated using combinations of phospholipid (DSPC) and an emulsifier (PEG40St) in different molar ratios. It was found that adding the emulsifier decreased the microbubble stability under ultrasound; however, the echogenicity of microbubbles was shown to increase with increasing emulsifier content. A method was developed to estimate the concentration of microbubbles with ultrasound. Hydrostatic pressure studies showed that the microbubbles recovered their spherical structures at low pressure pulses, in contrast, disappeared in a very short time at high pressure pulses. B-mode ultrasound intensity of microbubbles was investigated at different ultrasound powers under Doppler ultrasonography, and for the first time, a model was developed to relate the intensity to effective bubble concentration. We calculated acoustic energy thresholds and explained a possible mechanism for the destruction of microbubbles under ultrasound. The effect of shell loadings on the acoustic response and stability of microbubbles were investigated under ultrasound. It was found that both the echogenicity and stability of microbubbles increased with increasing mass of the loadings on microbubble shell. In-vivo studies showed that the acoustic performance of in-house made microbubbles was comparable to that of commercial standard Vevo MicroMarker® contrast agents.Mikroköpükçükler, ultrason görüntülemede etkili kontrast ajanları olarak kullanılmaktadır. Mikroköpükçüklerin stabilitesinin düşük olması, tıbbi uygulamalarda uzun süre kullanımlarını sınırlamaktadır. Bu tezin amacı, ultrason altında mikroköpükçüklerin stabilitesini artırmaktır. Mikroköpükçükler, farklı molar oranlarda fosfolipid (DSPC) ve emülsifiyer (PEG40St) karışımları kullanılarak üretildi. Farklı formülasyonlarda üretilen mikroköpükçüklerin stabilitesi ve akustik yanıtı, ultrason altında incelendi. Mikroköpükçüğün yüzeyini oluşturan zarın yapısındaki emülsifiyer içeriğinin artmasıyla ultrason altında mikroköpükçüklerin stabilitesinin azaldığı, artan emülsifiyer içeriği ile birlikte mikroköpükçüklerin ekojenitesinin arttığı bulundu. Ultrason ile mikroköpükçük konsantrasyonunu tahmin etmek için yeni bir yöntem geliştirildi. Hidrostatik basınç çalışmaları, mikroköpükçüklerin düşük basınç pulslarında küresel yapılarını geri kazandıklarını, aksine, yüksek basınç pulslarında çok kısa sürede ortadan kaybolduğunu gösterdi. Mikroköpükçüklerin B-mod ultrason intensitesi, Doppler ultrasonografi altında farklı ultrason güçlerinde araştırıldı ve ilk kez, ultrason intensitesini etkin mikroköpükçük konsantrasyonuyla ilişkilendirmek için bir model geliştirildi. Ultrason altında mikroköpükçük yıkımı için akustik enerji eşikleri hesaplandı ve olası bir yıkım mekanizması açıklandı. Mikroköpükçük zarı üzerine eklenen farklı kütleli yüklemelerin mikroköpükçüklerin akustik yanıtı ve stabilitesi üzerindeki etkisi ultrason altında incelendi. Mikroköpükçüklerin ekojenitesinin ve stabilitesinin, yüklemelerin kütlesinin artmasıyla arttığı bulundu. In-vivo çalışmalar, laboratuvarda geliştirilen mikroköpükçüklerin akustik performansının ticari MicroMarker® kontrast maddelerininkiyle karşılaştırılabilir olduğunu gösterdi.TUBITAK (113M270 and 213M668
Privacy issues in post dissemination on Facebook
No full textWith social networks (SNs) being populated by a still increasing numbers of people who take advantage of the communication and collaboration capabilities that they offer, the probability of the exposure of people's personal moments to a wider than expected audience is also increasing. By studying the functionalities and characteristics that modern SNs offer, along with the people's habits and common behaviors in them, it is easy to understand that several privacy risks may exist, many of which people may be unaware of. In this paper, we focus on users' interactions with posts in a social network (SN), using Facebook as our research domain, and we emphasize some privacy leakages currently existing in Facebook's privacy policy. We also propose a solution to detected privacy issues, featuring a reference implementation of a tool based on a simulation, which visualizes the effect of potential privacy risks on Facebook and directs users to control their privacy. The proposed and simulated tool allows a post owner to observe the spreading area of his or her post depending on the selected privacy settings. Moreover, it provides preliminary feedback for all Facebook users that have interacted with this post, to make them aware of the possible privacy changes, aiming to give them a chance to protect the privacy of their interaction on this post by deleting it when an unwanted privacy change takes place. Finally, an online survey to increase privacy awareness in Facebook usage with over 500 volunteer participants has illuminated the need for such a tool or solution
Search for heavy Majorana neutrinos in same-sign dilepton channels in proton-proton collisions at root s = TeV
No full textWOS: 000456243300001A search is performed for a heavy Majorana neutrino (N), produced in leptonic decay of a W boson propagator and decaying into a W boson and a lepton, with the CMS detector at the LHC. The signature used in this search consists of two same-sign leptons, in any flavor combination of electrons and muons, and at least one jet. The data were collected during 2016 in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). The results are found to be consistent with the expected standard model background. Upper limits are set in the mass range between 20 and 1600 GeV in the context of a Type-I seesaw mechanism, on |V-eN|(2), |V-N|(2), and |VeNV *|(2)/(|V-eN|(2)+|V-N|(2)), where V-N is the matrix element describing the mixing of N with the standard model neutrino of flavor = e, . For N masses between 20 and 1600 GeV, the upper limits on |V-N|(2) range between 2.3 x 10(-5) and unity. These are the most restrictive direct limits for heavy Majorana neutrino masses above 430 GeV
Karbon-cam elyaf takviyeli epoksi hibrit kompozitlerin mekanik özelliklerinin ve yorulma performansının incelenmesi
No full textThesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2019Includes bibliographical references (leaves: 45-49)Text in English; Abstract: Turkish and EnglishRecently, hybrid composites have known as high performance engineering materials and they have been used broadly in engineering applications where high strength to weight ratio, reasonable cost and ease of fabrication are requested. Since these composites offer combination of benefits of different kinds of fibers, their usage is increasing day after day. The objective of this thesis is to examine the mechanical properties of carbonglass fiber reinforced epoxy hybrid composites in two different configurations. Also, the fatigue performance under bending tests of these composites were investigated. The hybrid composites were manufactured by using vacuum infusion technique at ambient temperature. To examine the mechanical properties of manufactured composites, a series of mechanical tests such as compression, tensile and three-point bending tests were performed on the samples which were prepared in accordance with the relevant ASTM standards. Load-controlled three-point bending fatigue tests were also carried out to investigate the performance of manufactured composites under fatigue. The fatigue tests were performed at different stress levels varied from 30 percent to 90 percent of average ultimate flexural strength of the samples which were determined from static three-point bending tests. Subsequently stiffness loss and Wöhler curves were constructed using a specific failure criterion.Son zamanlarda, hibrit kompozitler yüksek performanslı mühendislik
malzemeleri olarak bilinmekte ve yüksek dayanım/ağırlık oranı, makul fiyat ve üretim
kolaylığı istenilen mühendislik uygulamalarında yaygın olarak kullanılmaktadırlar. Bu
kompozitler, farklı tiplerdeki elyafların yararlarının kombinasyonlarını sunduklarından,
kullanımları gün geçtikçe artmaktadır.
Bu tezin amacı karbon-cam elyaf takviyeli epoksi hibrit kompozitlerin iki farklı
konfigürasyonda mekanik özelliklerinin incelenmesidir. Aynı zamanda, bu
kompozitlerin üç-nokta eğme testi altında yorulma performansları incelenmiştir. Hibrit
kompozitler ortam sıcaklığında vakum infüzyon tekniğiyle üretilmiştir. Üretilen
kompozitlerin mekanik özelliklerini incelemek için ASTM standartlarına uygun olarak
hazırlanan numunelerde basma, çekme ve üç nokta bükme gibi bir seri mekanik testler
yapılmıştır. Aynı zamanda, kompozitlerin yorulma altındaki performanslarını incelemek
için yük kontrollü üç nokta eğme yorulma testleri uygulanmıştır. Yorulma testleri
numunelerin ortalama nihai eğilme dayanımlarının yüzde otuzu ile doksanı arasında
değişen dayanım seviyelerinde yapıldı. Daha sonra hasar kriterine uygun olarak sertlik
kaybı ve Wöhler eğrileri oluşturuldu
Characterization of antimicrobial activities of olive phenolics on yeasts using conventional methods and mid-infrared spectroscopy
No full textPubMed: 30728556Olive fruit is very rich in terms of phenolic compounds. Antimicrobial activities of various phenolic compounds against bacteria and fungi are well established; however, their effects on yeasts have not been examined. Aim of this study was to investigate the antimicrobial effects induced by olive phenolic compounds, including tyrosol, hydroxytyrosol, oleuropein, luteolin and apigenin against two yeast species, Aureobasidium pullulans and Saccharomyces cerevisiae. For this purpose, yeasts were treated with various concentrations (12.5-1000ppm) of phenolic compounds and reduction in yeast population was followed with optical density measurements with microplate reader, yeast colony forming units and mid-infrared spectroscopy. All phenolic compounds were effective on both yeasts, especially 200ppm and higher concentrations have significant antimicrobial activity; however, effects of lower levels depend on the type of phenolic compound. According to mid-infrared spectral data, significant changes were observed in 1200-900cm(-1) range corresponding to carbohydrates of yeast structure as a result of exposure to all phenolic compounds except tyrosol. Spectra of tyrosol and luteolin treated yeasts also showed changes in 1750-1500cm(-1) related to amide section and 3600-3000cm(-1) fatty acid region. Since phenolic compounds from olives were effective against yeasts, they could be used in food applications where yeast growth showed problem. In addition, FTIR spectroscopy could be successfully used to monitor and characterize antimicrobial activity of phenolic compounds on yeasts as complementary to conventional microbiological methods