Development of novel sorbents for speciation of inorganic and organik selenium prior to determination by atomic spectrometric techniques

Thesis (Master)--İzmir Institute of Technology, Chemistry, İzmir, 2011Includes bibliographical references (leaves: 86-93)Text in English; Abstract: Turkish and Englishxi, 93 leavesSelenium is an essential trace element forplants, animals and the human body. Hovewer, its possible toxicity at high concentrations necessitates the development of analytical methods for theseparation and determination of the several forms of the element in environmental andbiological systems.In the first part of the study, commercially available and newly synthesized ceria (CeO2) and zirconia (ZrO2) were used for the sorption and speciation of inorganic selenium. Sorption parameterswere investigated for both sorbents for selenite (Se(IV)) and selenate (Se(VI))and the optimized parameters were determined to be 25°C for sorption temperature, 50.0 mg for sorbent amount, 30 min for shaking time for 20.0 mLof 100.0 μgL-1of both species. Therelease of Se(IV) and Se(VI) from the sorbents was realizedusing two eluents, 0.10 M NaOH and 0.10 NH4Cl, respectively. The accuracy of the proposedmethodology was verified with spike recovery tests for various water types spiked with 10.0 μgL-1and 100.0 μgL-1Se(IV) and Se(VI). Spike recovery values were determinedto range between 91% and 97% at 10.0 μgL-1level, and between 97% and 113% at100.0 μgL-1level, for ceria and zirconia, respectively. Moreover, the sorption efficiencies of the newly synthesized sorbentswere compared with those of the commercial sorbents.Ceria and zirconia were shown to be applied in the speciation of inorganic selenium. Sorption studies with nZVI-modified zirconia have demonstrated that the sorbent can be utilized for the speciation of inorganic and organoselenium; namely, Se(IV), Se(VI), Seleno-L-cystine and Seleno-DL-methionine. In the final part of the study, it was shown by column-type equilibration studies that alginate beads modified/immobilized with CeO2 or ZrO2through three different synthesis routes can be used for the sorption and speciation of inorganic selenium

Fluorescent Liquid Tetrazines

Tetrazines with branched alkoxy substituents are liquids at ambient temperature that despite the high chromophore density retain the bright orange fluorescence that is characteristic of this exceptional fluorophore. Here, we study the photophysical properties of a series of alkoxy-tetrazines in solution and as neat liquids. We also correlate the size of the alkoxy substituents with the viscosity of the liquids. We show using time-resolved spectroscopy that intersystem crossing is an important decay pathway competing with fluorescence, and that its rate is higher for 3,6-dialkoxy derivatives than for 3-chloro-6-alkoxytetrazines, explaining the higher fluorescence quantum yields for the latter. Quantum chemical calculations suggest that the difference in rate is due to the activation energy required to distort the tetrazine core such that the [Formula: see text] [Formula: see text] and the higher-lying [Formula: see text] [Formula: see text] states cross, at which point the spin-orbit coupling exceeding 10 cm [Formula: see text] allows for efficient intersystem crossing to occur. Femtosecond time-resolved anisotropy studies in solution allow us to measure a positive relationship between the alkoxy chain lengths and their rotational correlation times, and studies in the neat liquids show a fast decay of the anisotropy consistent with fast exciton migration in the neat liquid films

Molecular rotors to probe the local viscosity of a polymer glass

We investigate the local viscosity of a polymer glass around its glass transition temperature using environment-sensitive fluorescent molecular rotors embedded in the polymer matrix. The rotors' fluorescence depends on the local viscosity, and measuring the fluorescence intensity and lifetime of the probe therefore allows to measure the local free volume in the polymer glass when going through the glass transition. This also allows us to study the local viscosity and free volume when the polymer film is put under an external stress. We find that the film does not flow homogeneously, but undergoes shear banding that is visible as a spatially varying free volume and viscosity.Comment: 8 pages, 7 figure

Albümin nanoparçacıklarının iyonik sıvı temelli mikroemülsiyon benzeri metot ile hazırlanması

Thesis (Master)--Izmir Institute of Technology, Materials Science and Engineering, Izmir, 2018Includes bibliographical references (leaves: 30-33)Text in English; Abstract: Turkish and EnglishRich drug transportation ability of serum albumin protein has inspired scientists to obtain drug nanocarriers from albumin. In the literature, different methods have been developed to prepare albumin nanoparticles and their drug delivery properties have been studied. Here, this study aims to obtain albumin nanoparticles for a first time using ionic liquid (IL) included systems. Goal of this project is using imidazolium based ionic liquids (green solvent) to prepare albumin nanoparticles as alternative solvents for the commonly used organic solvents. The use of volatile, toxic and flammable organic solvents in the albumin nanoparticle production has various negative effects on both human health and environment. Ionic liquids as non-flammable, non-volatile and non-toxic solvent candidates have attracted considerable attention in recent years both in the literature and in industry. Their ability to solve different types of solutes, designability, special mixing ability with water in IL/water binary systems and environmentally friendly properties cause ILs to overtake traditional organic solvents. This thesis study proposed a novel and environmentally friendly microemulsionlike method for producing albumin nanoparticles in IL/water binary systems. Various experimental parameters such as pH effects, albumin concentrations, water amount, surfactant effects, glutaraldehyde effects, homogenizer effects, etc. were investigated to obtain uniform albumin nanoparticles. As a result, we achieved to synthesize uniformly distributed 200 nm average size albumin nanoparticles at pH 9.0 using 1.5% (w/w) of bovine serum albumin (BSA) in 1-butyl-3-methylimidazolium tetrafluoroborate using TX-100/n-butanol surfactant mixture.Serum albümin proteininin zengin ilaç taşıma kapasitesine sahip olması, ilaç nanotaşıyıcıları yapılmasında bilim insanlarına ilham kaynağı olmuştur. Albumin nanoparçacıklarının üretilmesi ve ilaç taşıyıcısı olarak değerlendirilmesinde farklı yöntemler geliştirilmiştir. Biz de burada, ilk defa iyonik sıvıların kullanıldığı sistemler içerisinde albümin nanoparçacıklarını elde etmeyi hedefliyoruz. Projemizin amacı ilaç yüklü albümin nanoparçacığı hazırlanmasında şimdiye kadar kullanılan organik çözgenlere alternatif olarak imidazolyum tabanlı iyonik sıvıların (yeşil çözgenler) kullanılmasıdır. Uçucu, toksik ve yanıcı organik çözgenlerin albumin nanoparçacık üretiminde kullanılmasının insan sağlığı ve çevre üzerine pek çok olumsuz etkisi bulunmaktadır. Uçucu, toksik ve yanıcı olmayan çözgen adayları olan iyonik sıvılar son yıllarda hem literatürde hem de endüstride çokça ilgi çekmişlerdir. Farklı tipte malzemeleri çözebilme yetenekleri, tasarlanabilirlikleri, iyonik sıvı/su ikili sistemlerinde su ile özel bir şekilde karışma özelliği ve ayrıca çevre dostu özellikleri iyonik sıvıların geleneksel organik çözgenleri geçmesine ve de malzeme üretim çalışmalarında yeni bir ufuk açılmasına sebep olmuştur. Bu tez çalışması albumin nanoparçacık üretimi için yeni ve çevre dostu mikroemülsiyon benzeri bir metot önermektedir. pH, albümin konsantrasyonu, su miktarı, yüzey aktif madde konsantrasyonu, glutaraldehit etkisi, homojenizatör etkisi vb. gibi pek çok deneysel parametre incelenmiş olup pH 9.0’da %1.5 (w/w) bovin serum albumin kullanılarak düzenli dağılım gösteren ortalama 200 nm boyutlu nanoparçacıklar 1-bütil-3-metilimidazolyum tetrafloroborat içinde TX-100/n-bütanol yüzey aktif madde karışımı kullanılarak sentezlenmiştir.TUBITAK (114Z318) and IZTECH Scientific Research Project (2015_IYTE_01

Albümin nanoparçacıklarının iyonik sıvı temelli mikroemülsiyon benzeri metot ile hazırlanması

Thesis (Master)--Izmir Institute of Technology, Materials Science and Engineering, Izmir, 2018Includes bibliographical references (leaves: 30-33)Text in English; Abstract: Turkish and EnglishRich drug transportation ability of serum albumin protein has inspired scientists to obtain drug nanocarriers from albumin. In the literature, different methods have been developed to prepare albumin nanoparticles and their drug delivery properties have been studied. Here, this study aims to obtain albumin nanoparticles for a first time using ionic liquid (IL) included systems. Goal of this project is using imidazolium based ionic liquids (green solvent) to prepare albumin nanoparticles as alternative solvents for the commonly used organic solvents. The use of volatile, toxic and flammable organic solvents in the albumin nanoparticle production has various negative effects on both human health and environment. Ionic liquids as non-flammable, non-volatile and non-toxic solvent candidates have attracted considerable attention in recent years both in the literature and in industry. Their ability to solve different types of solutes, designability, special mixing ability with water in IL/water binary systems and environmentally friendly properties cause ILs to overtake traditional organic solvents. This thesis study proposed a novel and environmentally friendly microemulsionlike method for producing albumin nanoparticles in IL/water binary systems. Various experimental parameters such as pH effects, albumin concentrations, water amount, surfactant effects, glutaraldehyde effects, homogenizer effects, etc. were investigated to obtain uniform albumin nanoparticles. As a result, we achieved to synthesize uniformly distributed 200 nm average size albumin nanoparticles at pH 9.0 using 1.5% (w/w) of bovine serum albumin (BSA) in 1-butyl-3-methylimidazolium tetrafluoroborate using TX-100/n-butanol surfactant mixture.Serum albümin proteininin zengin ilaç taşıma kapasitesine sahip olması, ilaç nanotaşıyıcıları yapılmasında bilim insanlarına ilham kaynağı olmuştur. Albumin nanoparçacıklarının üretilmesi ve ilaç taşıyıcısı olarak değerlendirilmesinde farklı yöntemler geliştirilmiştir. Biz de burada, ilk defa iyonik sıvıların kullanıldığı sistemler içerisinde albümin nanoparçacıklarını elde etmeyi hedefliyoruz. Projemizin amacı ilaç yüklü albümin nanoparçacığı hazırlanmasında şimdiye kadar kullanılan organik çözgenlere alternatif olarak imidazolyum tabanlı iyonik sıvıların (yeşil çözgenler) kullanılmasıdır. Uçucu, toksik ve yanıcı organik çözgenlerin albumin nanoparçacık üretiminde kullanılmasının insan sağlığı ve çevre üzerine pek çok olumsuz etkisi bulunmaktadır. Uçucu, toksik ve yanıcı olmayan çözgen adayları olan iyonik sıvılar son yıllarda hem literatürde hem de endüstride çokça ilgi çekmişlerdir. Farklı tipte malzemeleri çözebilme yetenekleri, tasarlanabilirlikleri, iyonik sıvı/su ikili sistemlerinde su ile özel bir şekilde karışma özelliği ve ayrıca çevre dostu özellikleri iyonik sıvıların geleneksel organik çözgenleri geçmesine ve de malzeme üretim çalışmalarında yeni bir ufuk açılmasına sebep olmuştur. Bu tez çalışması albumin nanoparçacık üretimi için yeni ve çevre dostu mikroemülsiyon benzeri bir metot önermektedir. pH, albümin konsantrasyonu, su miktarı, yüzey aktif madde konsantrasyonu, glutaraldehit etkisi, homojenizatör etkisi vb. gibi pek çok deneysel parametre incelenmiş olup pH 9.0’da %1.5 (w/w) bovin serum albumin kullanılarak düzenli dağılım gösteren ortalama 200 nm boyutlu nanoparçacıklar 1-bütil-3-metilimidazolyum tetrafloroborat içinde TX-100/n-bütanol yüzey aktif madde karışımı kullanılarak sentezlenmiştir.TUBITAK (114Z318) and IZTECH Scientific Research Project (2015_IYTE_01

Development of novel sorbents for speciation of inorganic and organik selenium prior to determination by atomic spectrometric techniques

Thesis (Master)--İzmir Institute of Technology, Chemistry, İzmir, 2011Includes bibliographical references (leaves: 86-93)Text in English; Abstract: Turkish and Englishxi, 93 leavesSelenium is an essential trace element forplants, animals and the human body. Hovewer, its possible toxicity at high concentrations necessitates the development of analytical methods for theseparation and determination of the several forms of the element in environmental andbiological systems.In the first part of the study, commercially available and newly synthesized ceria (CeO2) and zirconia (ZrO2) were used for the sorption and speciation of inorganic selenium. Sorption parameterswere investigated for both sorbents for selenite (Se(IV)) and selenate (Se(VI))and the optimized parameters were determined to be 25°C for sorption temperature, 50.0 mg for sorbent amount, 30 min for shaking time for 20.0 mLof 100.0 μgL-1of both species. Therelease of Se(IV) and Se(VI) from the sorbents was realizedusing two eluents, 0.10 M NaOH and 0.10 NH4Cl, respectively. The accuracy of the proposedmethodology was verified with spike recovery tests for various water types spiked with 10.0 μgL-1and 100.0 μgL-1Se(IV) and Se(VI). Spike recovery values were determinedto range between 91% and 97% at 10.0 μgL-1level, and between 97% and 113% at100.0 μgL-1level, for ceria and zirconia, respectively. Moreover, the sorption efficiencies of the newly synthesized sorbentswere compared with those of the commercial sorbents.Ceria and zirconia were shown to be applied in the speciation of inorganic selenium. Sorption studies with nZVI-modified zirconia have demonstrated that the sorbent can be utilized for the speciation of inorganic and organoselenium; namely, Se(IV), Se(VI), Seleno-L-cystine and Seleno-DL-methionine. In the final part of the study, it was shown by column-type equilibration studies that alginate beads modified/immobilized with CeO2 or ZrO2through three different synthesis routes can be used for the sorption and speciation of inorganic selenium

Endokrin bozucu kimyasalların tayini için yeni katı faz ekstraksiyon (SPE) sorbentlerinin ve katı faz mikroekstraksiyon (SPME) fiber kaplamalarının geliştirilmesi

Thesis (Doctoral)--İzmir Institute of Technology, Chemistry, İzmir, 2017Full text release delayed at author's request until 2020.01.26Includes bibliographical references (leaves: 97-111)Text in English; Abstract: Turkish and EnglishThis thesis is composed of four chapters. In the first part of the study, molecularly imprinted polymer (MIP) was prepared as SPE sorbent for selective determination of BPA prior to HPLC DAD analysis. The adsorption capacity and selectivity of imprinted polymers were investigated. To improve the MISPE method, the parameters including pH of sample solution, adsorption time, amount of sorbent, desorption solvent were examined. The extraction efficiency of BPA imprinted polymer was investigated by using the spiked samples of ultrapure, drinking and tap water. The second part of the thesis was about determination of estrogen hormones. For this purpose, amino modified silica and molecular imprinted silica were prepared and their SPE performances were compared. The proposed methodology was validated through the analysis of real water samples. The preparation of MIP nanoparticles encapsulated in electrospun polystyrene fibers as the SPME fiber coating was the subject of the third part of the thesis. Developed fibers were used for selective extraction and analysis of parabens in water samples. The optimization parameters affecting the extraction and desorption of parabens were investigated. The validity of the proposed method was verified via spike recovery tests. Finally, fibers having amino functionality prepared by the sol-gel based electrospinning process were used for determination of BPA. The effect of solution pH, extraction time, agitation speed and ionic strength on the extraction performance were investigated. Validity was checked via the application of the proposed methodology on real samples.Bu tez dört bölümden oluşmaktadır. Çalışmanın birinci kısmında, bisfenol A nın HPLC-DAD analizi öncesi tayini için moleküler baskılanmış polimerler (MIP) SPE sorbenti olarak sentezlenmiştir. Baskılanmış polimerlerin adsorpsiyon kapasitesi ve selektivitesi araştırılmıştır. MISPE metotunu geliştirmek için örnek çözelti pH’sı, çalkalama zamanı, sorbent miktarı, desorpsiyon çözeltisi gibi parametreler test edilmiştir. BPA ile baskılanmış polimerin ekstraksiyon verimi ultra saf su içme suyu ve çeşme suyu analizleri ile anlaşılmıştır. Çalışmanın ikinci kısmı estrojen hormonlarının tayini hakkındadır. Bu amaç için yüzeyi amino- grubu ile modifiye edilmiş silika ile yüzeyi moleküler olarak baskılanmış silika hazırlanmış ve bunların SPE performanları kıyaslanmıştır. Önerilen yöntem gerçek örneklerin analizi ile valide edilmiştir. MIP nano parçacıkları gömülmüş elektrodukma polistren fiberleri SPME fiber kaplaması olarak hazırlanması bu tezin üçüncü kısım konusudur. Geliştirilen fiberler sularda bulunan parabenin selektif ekstraksiyonunda ve analizinde kullanılmıştır. Paraben ekstraksiyonunu ve desorpsiyonunu etklileyen parametreler araştırılmıştır. Önerilen yöntemin geçerliliği, gerçek örnekler ile doğrulanmıştır Son olarak, sol-jel esaslı elekrospun işlemi ile hazıranmış amino işlevselliğine sahip fiberler BPA'nın tayini için kullanılmıştır. Çözelti pH, ekstraksiyon zamanı, çalkalama hızı ve iyonik kuvvetin ekstraksiyon perfonması üzerinde ki etkisi araştırıldı. Önerilen metodolojinin geçerliliği, gerçek örnekler üzerinde uygulama yoluyla kontrol edilmiştir.The Scientific and Technological Research Council of Turkey (TUBITAK 114Z777

Friction and wear behaviour of flame-sprayed Cr2O3 coatings as bearing materials

This paper describes the friction and wear behaviour of Cr 2O3/Ni8.5Cr7A15Mo2Si2B2FeTiO2 coatings for bearing materials. These coatings were successfully deposited on low carbon steels using a flame spray technique. The produced samples were characterized by means of an optical microscope and microhardness tester. The microstructural observations showed that the layers contain some inhomogeneities such as porosity, crack-like defects, unmelted particles, oxides and inclusions. The structures with the inhomogeneities strongly influence their wear/friction properties. The friction and wear experiments were performed under dry and acid environments using a pin-on-plate configuration against AISI 303 counter material for different loads. It was found that in acid environment, the amount of wear loss is less than that of in dry condition and applied load level is more effective in dry condition

Friction and wear behaviour of flame-sprayed Cr2O3 coatings as bearing materials

This paper describes the friction and wear behaviour of Cr2O3/Ni8.5Cr7Al5Mo2Si2I32FcTiO(2) coatings for bearing materials. These coatings were successfully deposited on low carbon steels using a flame spray technique. The produced samples were characterized by means of an optical microscope and microhardness tester. The microstructural observations showed that the layers contain some inhomogeneities such as porosity, crack-like defects, unmelted particles, oxides and inclusions. The structures with the inhomogeneities strongly influence their wear/friction properties. The friction and wear experiments were performed under dry and acid environments using a pin-on-plate configuration against AISI 303 counter material for different loads. It was found that in acid environment, the amount of wear loss is less than that of in dry condition and applied load level is more effective in dry condition

Development of an ionic liquid based method for the preparation of albumin nanoparticles

Albumin based nanocarriers have been widely used in drug delivery studies. Here, we developed a water-in-ionic liquid (IL) emulsion-like method to prepare bovine serum albumin (BSA) nanoparticles as alternative to the traditional organic solvents containing techniques. Conformational changes of albumin induced by the imidazolium based ILs at the water-IL interface triggers the BSA nanoparticle formation. The albumin nanoparticle formation are dependent on the experimental parameters and the hydophobicity of the IL. At pH 9.0, using 1.3%wt of BSA in water/1-butyl-3-methyl imidazolium tetrafluoroborate (BmimBF4) (50/50 mol%) and TX-100/butanol surfactant mixture yields uniformly distributed 200 nm average sized BSA nanoparticles. Different than BmimBF4, using a more hydrophilic IL, EmimBF4 yielded albumin aggregates. Instead, using a more hydrophobic IL, HmimBF4 produced albumin nanoparticles but a non-uniform size distribution was obtained. These results indicate that the ionic liquids called green and designer solvents can be also used to synthesize albumin nanoparticles.IZTECH Scientific Research Project 2015_IYTE_0