Knowledge about selenium content of foods containing selenium species is very important in terms of both nutrition and toxicity. Bioavailability of selenium species for human body is different from each other. Hence, speciation of selenium is more important than total selenium determination. In the selenium speciation study, chicken breast samples, selenium supplement tablets and egg samples were analyzed for their selenium contents. In chicken breast study, chickens were randomly categorized into three groups including the control group (25 chickens), inorganic selenium fed group (25 chickens) and organic selenium fed group (25 chickens). After the optimization of all the analytical parameters used throughout the study, selenomethionine, selenocystine, Se(IV) and Se(VI) were determined using Cation Exchange-HPLC-ICP-MS system. In selenium supplement tablet study, anion and cation exchange chromatographies were used to determine selenium species. Arsenic is known as toxic element, and toxicity of inorganic arsenic species, As(III) and As(V), is much higher than organic arsenic species like arsenobetaine and arsenosugars. Hence, speciation of arsenic species in any matrix related with human health is very important. In the arsenic speciation study, Cation Exchange-HPLC-ICP-MS and Cation Exchange-HPLC-ES-MS systems were used to determine arsenobetaine content of DORM-2, DORM-3 and DOLT-4 as CRMs. All of the parameters in extraction, separation and detection steps were optimized. Standard addition method was applied to samples to eliminate or minimize the matrix interference. Thiols play an important role in metabolism and cellular homeostasis. Hence, determination of thiol compounds in biological matrices has been of interest by scientists. In the thiol study, Reverse Phase-HPLC-ICP-MS and Reverse Phase-HPLC-ES-MS systems were used for the separation and detection of thiols. For the thiol determination, thiols containing &ndash / S-S- bond were reduced using dithiothreitol (DTT). Reduction efficiencies for species of interest were found to be around 100%. Reduced and free thiols were derivatized before introduction on the column by p-hydroxymercuribenzoate (PHMB) and then separated from each other by using a C8 column. In the real sample measurement, yeast samples were analyzed using HPLC-ES-MS system.

Antimony is a toxic element which is mostly found in two oxidation states (III and V) in environmental, biological and geological samples. Antimony may form various inorganic and organic compounds that exhibit differences in analytical behavior, toxicity and mobility / inorganic compounds of antimony are more toxic than organic forms and toxicity of Sb(III) has been shown to be 10 times higher than that of Sb(V). Therefore selective determination of Sb(III) and Sb(V) is required in environmental and biological samples. Hydride generation atomic absorption spectrometry is a sensitive, fast and economical technique for the determination of antimony at trace level. A possible non-chromatographic method for antimony speciation is hydride generation atomic absorption spectrometry that is based on the relatively slow kinetics of hydride formation from Sb(V). In this study, continuous flow hydride generation method for the determination of antimony was developed and hydride generation conditions were optimized. Analyte solution was prepared in 0.050 mol/L HCl and 1.2% (w/v) NaBH4 stabilized in 0.30% (w/v) NaOH was used as a reductant solution. Inorganic antimony speciation conditions were determined by continuous flow HGAAS system. For the pre-reduction of Sb(V) to Sb(III), 8.0% (w/v) potassium iodide (KI) and 0.10% (w/v) ascorbic acid were used. Further speciation study was also carried out using Ir coated W-coil Atom Trap Hydride Generation Atomic Absorption Spectrometry. Tungsten coil atom trap was used to enhance the sensitivity. Tungsten coil surface was treated with Ir and totally 250 &amp / #956 / g 1000 mg/L Ir stock solution was used for coating of tungsten coil. LOD and LOQ values were calculated as 152 pg/mL and 508 pg/mL according to 120 seconds trapping. 128 and 37 fold enhancement were obtained for 120 seconds collection with respect to W-coil-ETAAS and ETAAS, respectively.

ABSTRACT SOIL AND WATER ANALYSIS TECHNIQUES FOR AGRICULTURAL PRODUCTION Maral, Nuh M. Sc., Department of Chemistry Supervisor: Prof. Dr. G. inci G&ouml / kmen May 2010, 108 pages In Turkey, usage of increasing amounts of fertilizers and pesticides by some unconscious farmers cause soil pollution and soil infertility for the crop production. Usage of water in excessive amounts and/or in poor quality for irrigation creates problems during the plant production. So in this study, soil and water samples were analyzed by using simple and reliable techniques for the soil and water quality in laboratories of METU and Soil Fertilizer and Water Resources Central Research Institute Laboratory in Ankara. The soil and water samples were collected using the standard techniques from Ankara, Bolu, &Ccedil / orum and Kirikkale. According to the soil test results, the textures of the soil samples are found as loam and clay loam. The total salt content of the soil samples are between 0.033 &ndash / 0.063 % (w/w), meaning they are low salinity soils (total salt less than 0.15 % w/w). The pH of the soil samples are between 7.86&ndash / 8.15, they are slightly alkaline. The phosphorus concentrations of soil samples are in a range 4.95 to 35.45 P2O5 kg/da. Some of the soil samples have too high phosphorus content (greater than 12 P2O5 kg/da). The potassium content of soil samples are found between 141&ndash / 286 K2O kg/da, so the soil is efficient for crop production. Lime content of the soil samples is between 1.04&ndash / 2.67 % (w/w) CaCO3. It means all of the soil samples are calcareous but it is not too high for the agricultural production. Organic matter content of soil samples are found between 0.83&ndash / 2.04 % (w/w). This means the soils are limited in their organic matter content for the crop production. Analysis of 22 water samples yielded EC values between 0.384 &ndash / 1.875 dS/m. Water samples have moderate to high-salinity (if EC values between 0.205 and 2.250 dS/m), yet these can be used for the irrigation of the crops. pH values of water samples are found between 7.18-8.10, meaning that they are slightly alkaline. Bicarbonate concentrations of 19 of the water samples are greater than 200 mg/L. These waters may not be suitable for irrigation of ornamental plants. All of the water samples, except water samples from G&ouml / lbaSi, have sodium absorption ratio (SAR) values between 1 and 9. Water samples with low SAR values, except water samples from G&ouml / lbaSi, can be used for irrigation of almost all soils with little danger of developing harmful levels of sodium. The Residual Sodium Carbonate (RSC) values of water samples Ankara G&ouml / lbaSi and Sincan-1 are greater than 2.50 meq/L and these water samples are not suitable for the irrigation. RSC values of Etimesgut, Sincan-2 and Kazan water samples are positive and lower than the value 2.00 meq /L. All the other water samples have negative RSC values so they are the safe to use for irrigation. It has been observed that development of practical field analysis techniques for all soil and water quality parameters may be possible with exception of micronutrient determination. For determining soil and water quality parameters in the rural areas there is a need to establish a small laboratory with necessary equipment and apparatus and training one or two farmers. With the experience gained in this study, some of these techniques may be adapted to the rural field applications, so soil and water may be tested by the farmers for better yields.

ABSTRACT ARSENIC SPECIATION IN FISH BY HPLC-ICP-MS &Ouml / ZCAN, Sefika Eroglu M.S., Department of Chemistry Supervisor: Prof. Dr. O. Yavuz ATAMAN September 2010, 103 pages Arsenic speciation in fish samples on the market was performed using isocratic elution with cation exchange column high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Total As concentrations were found by ICP-MS using samples digested by nitric acid-hydrogen peroxide solution using microwave oven digestion / the results were in the range of 1.15-12.6 &micro / g/g. Separation of organic arsenicals, namely arsenobetaine (AB), dimethylarsinic acid (DMA) and monomethylarsonic acid (MA), have been achieved in 12 minutes. Freeze-dried samples were extracted by deionized water with a shaker system / the concentrations of AB and DMA in the extract was then determined using HPLC-ICP-MS. The accuracy of the method for determining AB concentration was confirmed using certified reference material (CRM), DOLT 4 (dog fish liver) / for this CRM only preliminary data are available for AB. The arsenic compounds in 6 fish muscle samples were investigated. The predominant arsenic compound found in extracts was AB / the concentrations were in the range of 0.86-12.0 &micro / g/g. DMA concentration was 0.40&plusmn / 0.03 &micro / g/g in one of the samples / in the others it was below the limit of quantation (0.21 &micro / g/g).

In biomedical applications, magnetic nanoparticles have been used as they offer attractive possibilities. First, they have controllable sizes ranging from a few nanometers up to tens of nanometers and second, the nanoparticles are magnetic and magnetic fields can penetrate into human tissue which means that they can be manipulated by an external magnetic field gradient. In this study, Fe

ABSTRACT SENSITIVE AND QUANTITATIVE DETERMINATION OF CYSTEINE BY SURFACE ENHANCED RAMAN SPECTROMETRY BASED ON THEIR INDUCED AGGREGATES OF GOLD AND SILVER NANOSTRUCTURES Y&uuml / ksel, Recep M.Sc., Department of Chemistry Supervisor: Prof. Dr. M&uuml / rvet Volkan September 2011, 76 pages The synthesis of noble metal nanostructures are an active research area and controlling the shape and the size is a challenging task. In this study, nanostructures with different morphologies were prepared using wet chemical synthesis techniques in the aqueous solutions. Gold and silver nanospheres were produced by reducing and capping agent trisodium citrate. Gold nanorods were synthesized by chemical reduction of HAuCl4 by ascorbic acid in the presence of cetyltrimethylammonium bromide (CTAB), AgNO3, and gold nanoseeds (in 1.5 nm diameter) and gold silver core shell nanorods were prepared by addition of silver atoms on the surface of gold nanorods in the presence of CTAB. Parameters that were critical to obtain homogeneous nanostructures were optimized. The characterization of the nanoparticles was performed by UV-VIS spectrometry, High Resolution - Transition Electron Microscopy (HR-TEM), Field Emission - Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDX). Besides, their electromagnetic enhancement properties were demonstrated through SERS measurement of cysteine. Self-assembly or assisted assembly of nanorods or nanospheres into organized arrays allows the realization of their collective properties that arise from the coupling of the optical and electronic properties of the neighbouring individual nanoparticles. In this study cysteine molecule was used as a linker molecule. The controlled addition of cysteine into the gold nanorod solution resulted in their preferential binding to the two ends of the gold nanorods and the formation of gold nanochains. In the usage of gold nanospheres on the other hand, cooperative hydrogen bonding of the cysteine molecules, resulted in the formation of gold nanoclusters. The assembly formation was demonstrated by UV&ndash / vis spectrometry and FE-SEM. Cysteine is a thiol group containing amino acid and deficiency of cysteine results in serious health problems. Therefore, determination of cysteine is an important issue. Herein we report two strategies for the quantitative determination of micromolar concentrations of cysteine by exploiting the interplasmon coupling in Au nanoparticles. One of them is a recently published colorimetric method and the other is a novel SERS method.

Determination of thallium is important due to its toxic effects on the environment and human health. Extremely low abundance of thallium in earth crust requires very sensitive and accurate methods for determination of this element. Although volatile compound generation is a sensitive, fast and economical method, thallium determination by this method has not been sufficiently investigated in literature, because of the fact that the formation of volatile forms of this element is a difficult task. A continuous flow volatile compound generation system was developed and parameters that affect the analytical signal were optimized. Sample solutions were acidified with 0.5 mol/L HNO3 and prepared in 0.0005% (v/v) rhodamine B and 1.0 mg/L Pd while 0.5% (m/v) NaBH4 stabilized in 0.5% (m/v) NaOH was used as reductant. Fast decomposition and unstability of thallium volatile species affected system performance negatively. Flow injection volatile compound generation studies were carried out with a special system. After optimizations, LOD and LOQ values were calculated as 12 ng/mL and 40 ng/mL according to peak height values in HNO3 medium. Similarly, in HCl medium LOD and LOQ values were calculated as 14 ng/mL and 45 ng/mL. Addition of Te and Pd to the sample solution containing co-enhancement reagent rhodamine B improved volatile compound generation efficiency in peak height by 3.6 and 9.3, respectively. Type of the acid used was affected peak heights and peak shapes of Tl+ and Tl3+ volatile species and HNO3 medium gave better results. By changing the location of introduction for Ar gas, the sources of memory effects and reasons of peak broadening were investigated. Most of the memory effects were coming from the gas-liquid separator (GLS) or before the GLS, as well as T-tube atomizer. Nature and behavior of Tl volatile species were also investigated and it was found that Tl and also Pd were generated in the form of nanoparticles. Transmission electron microscopic (TEM) measurements prove the presence of Tl nanoparticles in the analyte species transported to the atomizer by the effect of carrier Ar gas.

Meniscus is a fibrocartilaginous tissue which plays an important role in joint stability, lubrication, and load bearing and transmission. Meniscal tears are commonly encountered in sports activities, or caused by degeneration of the cartilage with ageing. They lead to pain, loss of work, disturbed biomechanics of the knee and inability to walk or even move the legs. As the meniscal tissue is avascular in the inner portion, injury to this part does not heal by itself, and therefore treatments are needed. In some cases when complex tears occur, the tissue cannot be successfully treated with the conventional methods. Tissue engineering appears to be a promising alternative to treat such complex tears. It includes the application of cells on scaffolds (or cell carriers), and provision of bioactive agents to the site of injury in order to regenerate the damaged tissue. The cells and the bioactive agents are involved in the synthesis of the new tissue, while the scaffold acts as a support to guide the cells until the new tissue is formed, and it is slowly absorbed by the body leaving the new tissue behind. Thus, a natural tissue is generated at the end. Few studies have been reported on the tissue engineering of meniscus, but neither of them was able to completely mimic the meniscus structure, nor could they succeed in constructing scaffolds with sufficiently high tensile properties. In the current in vitro study, a novel 3D construct was proposed, in which the natural tissue is perfectly mimicked. The 3D construct consisted of aligned collagen fibers embedded within a foam network which stabilizes the structure. The foam was prepared by freezing a polymer solution with a certain concentration, and lyophilizing it. Aligned fibers were aimed to improve the tensile properties. The construct was impregnated in alginate gel, which was then crosslinked, to improve the compressive properties. The foam was prepared from (poly(L-lactic acid)/poly(lactic-co-glycolic acid) (PLLA/PLGA) solutions of various concentrations (2%, 2.5%, 3%, and 4% w/v) and at different freezing temperatures (-20oC or -80oC) to select the best preparation condition. After analysis of the microstructure and mechanical properties, foams prepared from 3% polymer solution frozen at -20oC were found to be the most appropriate for use as scaffold for the 3D construct, since they had large pores, high and interconnected porosity, as well as high mechanical strength. The 3D constructs were seeded with human meniscus cells and incubated for 21 days. Cell behavior on the constructs was examined. Cell attachment and proliferation was found to be better with the constructs not coated with alginate. However, the constructs coated with alginate demonstrated higher compressive strength. It was also found that incorporation of collagen fibers significantly improved the tensile properties. All the constructs were shown to lead to the production of extracellular components specific for fibrocartilages, and thus it was concluded that they were promising for use in meniscal replacement.

<p>Background: A harmonisation of accounting directions has been taken place, which for most countries has meant an adjustment to the directions of the United States. The Swedish directions of group accounting, RR 1:00, is one such adaptation. At the same time, a new direction of group goodwill, FAS 142, is introduced in the US. </p><p>Purpose: The purpose of this thesis is to map out the Swedish actors’, mainly the companies’, opinion about the direction of group goodwill accounting. </p><p>Procedure: Information from three actors in the market of accounting (accountants at the firms, users, in the form of analysts, and authorised accountants and one issuer of the directions) was collected via questionnaire and complementary telephone interviews. </p><p>Summary: From the investigation we found out that the Swedish actors are content with the Swedish directions of group goodwill accounting but they think that an adjustment to the American direction FAS 142 is inevitable. The analysts had a positive attitude towards FAS 142 while the other actors were a little more doubtful.</p>

La contabilizzazione delle operazioni di M&A è radicalmente mutata nel corso degli ultimi dieci anni, nel contesto statunitense come in quello europeo. A seguito di tali cambiamenti l’ammontare di goodwill (avviamento) iscritto nei bilanci di molte società si è incrementato. Questo studio si propone in primo luogo di far luce sulla reliability di tali valori analizzando le cause della svalutazione del goodwill, a partire dall’ipotesi essa sia causata in molti casi dal pagamento di un prezzo eccessivo da parte dell’impresa acquirente, piuttosto che essere la conseguenza di eventi successivi all’operazione. L’analisi, in secondo luogo, ha lo scopo valutare se l’impairment test del goodwill, reso obbligatorio dallo SFAS 142 raggiunga l’obiettivo di individuare in modo tempestivo le perdite durevoli di valore del goodwill acquisito e, dunque, di evitare che rimangano iscritti in bilancio come assets valori che di fatto non lo sono. Lo studio ha considerato un campione di 929 acquisizioni concluse nel periodo 1999-2007 che hanno coinvolto società statunitensi quotate ed è stato condotto sviluppando un modello predittivo basato su alcune misure indicanti potenziale overpayment da parte dell’acquirente alla data di acquisizione. I risultati mostrano in primo luogo come alcuni indicatori di overpayment, come la percentuale del prezzo pagata in azioni dell’impresa acquirente e un ammontare elevato di goodwill rispetto al prezzo di acquisto, diano un contributo significativo nella stima di future svalutazioni del goodwill. Un risultato piuttosto preoccupante, poiché segnala una almeno parziale incapacità da parte degli attuali Principi Contabili (SFAS 141) di garantire che alla data di acquisizione il valore attribuito a tale asset sia effettivamente fondato sulle sinergie e sul valore di “going-concern” del target (“core goodwill”), escludendo elementi ad esso estranei, come l’ overpayment da parte dell’acquirente. Per quanto attiene al secondo obiettivo, i risultati mostrano che il lasso temporale tra la data di acquisizione e il momento della svalutazione è in media di due - tre anni, a differenza di quanto accadeva precedentemente all’entrata in vigore dello SFAS 142, quando tale distanza temporale è stata stimata essere tra i quattro e i cinque anni. Tale risultato pertanto suggerisce che l’impairment test (almeno) annuale ha ottenuto l’effetto di migliorare la tempestività dell’individuazione di eventuali perdite durevoli di valore, contribuendo a bilanciare l’effetto sopra descritto che potenzialmente si ingenera alla data di acquisizione. / The purpose of this study is to shed light on the reliability of accounting goodwill numbers by examining whether the root cause of many goodwill impairment losses is the overpayment for the target at the time of the original acquisition, rather than the deterioration of goodwill values caused by events occurred after acquisition. A second related objective is to assess whether the annual impairment test of the acquired goodwill introduced by SFAS 142 improved the ability of accounting standards to timely capture situations in which the amount of goodwill is overstated and should thus be written down. I tested these hypotheses over a sample of 929 acquisitions completed by US listed companies over the nine-year period from 1999 to 2007. To assess whether the occurrence of a goodwill impairment loss can be predicted based on overpayment indicators, I developed a prediction model of goodwill impairment losses using some indicators measured at the acquisition date that signal potential overpayment by the acquiring firm. First, I found that certain measures, such as the percentage of stock in the consideration and the amount of purchase price assigned to goodwill, in fact represent powerful indicators of the occurrence of a subsequent goodwill impairment. This result is troubling as it suggests that SFAS 141 provisions are at least partially unable to avoid that components other than “core goodwill” being included in the amount recognized as goodwill, casting some doubt on the credibility of prominent goodwill amounts included in the financial statements of many corporations. I also found that the recognition of goodwill impairments lags behind the acquisition time by an average of two to three years. Compared with findings of earlier studies this result indicates that SFAS 142 requirements for annual impairment tests in fact improved the timeliness of recognizing goodwill write-offs, eventually helping to mitigate the failure of SFAS 141.