02. Fen Fakültesi / Faculty of Science

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Citation - WoS: 4
Citation - Scopus: 4
Synthesis, Characterization and Reactivity of [exo-Nido 9h10me2)]
(Marcel Dekker Inc., 1996) Topaloğlu, Işıl; Sözüer, Işıl; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
In this work, the reaction of the 16-electron species [Rh(η3-C8H13)-(η5-C 2B9H9Me2)] with PPh3 was investigated and the product, [exo-nido-Rh-(PPh3)2(η5-C2B 9H10Me2)], which is in an equilibrium with the closo analogue was characterized by 31p{1H}, 1H, 13C and 11B NMR spectroscopy. A mechanism for the complex formation is suggested which is related to the previously reported reactions between the 16-electron complex and PR3 (R = Me and Et) ligands.
Citation - WoS: 8
Hydrogen Sulfide Determination by Solid Surface Luminescence
(Springer Verlag, 1996) Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; Volkan, Mürvet; Bayramlı, Erdal; Ataman, O. Yavuz; Mark, Harry B.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
In the analytical system suggested, atmospheric hydrogen sulfide reacts with the surface of a filter paper treated with aqueous cadmium chloride and yields a luminescent species whose intensity can be correlated with the analyte concentration in ambient air. It was shown that the luminescent species are CdS solid particles which were formed in a well defined size. The paper luminescence was also tried on polymeric surfaces; polyethyleneoxide, polyvinyl alcohol, ethylcellulose and carboxymethylcellulose were found to give a similar luminescence signal. The system can be used on the tip of an optical fiber for an irreversible, cumulative type of analytical device for hydrogen sulfide determination. The 3s detection limit for the paper luminescence detection system was 7.8 ppb H2S.
Citation - WoS: 22
Citation - Scopus: 24
Prolactin Receptor Gene Expression in Rat Splenocytes and Thymocytes From Birth To Adulthood
(Elsevier Ltd., 1996-03) Güneş, Hatice; Güneş, Hatice; Mastro, Andrea M.; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
In vivo and in vitro studies have indicated that the anterior pituitary hormone prolactin (PRL) is an immunoregulator and functions in the development of the neonatal immune system. In this study, prolactin receptor (PRL-R) expression from birth to adulthood as well as the effect of milk ingestion on the PRL-R expression were examined in splenocytes and thymocytes of neonatal rats. Three approaches were taken to measure PRL-R expression: (i) polymerase chain reaction (RT-PCR); (ii) antibody to PRL-R and Western blotting; (iii) antibody to PRL-R and flow cytometry. RT-PCR analysis revealed the short and long form of PRL-R mRNA in both spleen and thymus at every age tested. However, the long form of PRL-R mRNA was always more abundant than that of the short form. In addition, antipeptide antibody against the long form of PRL-R recognized 84 and 42 kD proteins in the spleen, but only the 84 kD protein in the thymus. A monoclonal antibody U6 recognized 38 and 40 kD proteins in both the spleen and thymus. Although the mRNA level of PRL-R was relatively low at birth and increased with age in both the spleen and thymus, the levels of protein bands detected with both antibodies correlated with development in the spleen; whereas the levels remained steady in the thymus. Therefore, we concluded that the expression of PRL-R at the protein level is developmentally regulated in the spleen but not in the thymus. Finally, milk ingestion in the first seven hours decreased the percentage of cells expressing cell surface PRL-R, suggesting that milk-borne PRL may have a direct effect on lymphocytes.
Optimization of Mass Spectrometric Ionisation Efficiency Data
(Springer Verlag, 1997) Özgen, İsmet Tamerkan; Özgen, İsmet Tamerkan; Altungöz, Oya; Salih, B.; Vandeginste, B. G. M.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
A new method is developed and tested to find out the excited electronic and vibrational energy levels (fine structure) of molecules from mass spectrometric ionisation efficiency data which were obtained by a conventional mass spectrometer ion source having normal electron energy distribution. Electrons emitted in a conventional mass spectrometer ion source are not monoenergetic, therefore, evaluation of Ionisation Potentials (IF) and Appearance Potentials (AP) from experimental data creates some problems. This is even worse in the evaluation of Fine Structure (excited electronic and vibrational energy levels) from ionisation efficiency data [1]. This is overcome either by using specially designed monoenergetic ion sources which have their own problems (manufacture of special design, difficulty of operation, too much decrease of ion current), or by eliminating disturbing effects in the ionisation efficiency data by some deconvolution techniques [2,4,5,6,7,9]. In this study attempts were made to eliminate the deteriorating effects (mainly arising from electron energy distribution and noise) in the ionisation efficiency data by a deconvolution technique. The technique was applied to the ionisation efficiency data of molecular nitrogen,oxygen and methylammine and its fragment and interesting results were obtained.
Citation - WoS: 5
Citation - Scopus: 4
Prolactin Receptor Expression by Splenocytes From Rats in Various Hormonal States
(John Wiley and Sons Inc., 1997) Güneş, Hatice; Güneş, Hatice; Zawilla, S.; Mastro, Andrea M.; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
Prolactin (PRL) is mitogenic for lymphocytes in vitro, but the responsiveness of lymphocytes depends on the in vivo hormonal status of the rats from which the cells were obtained. Lymphocytes from ovariectomized (OVX) rats, but not from rats in oestrus or from male rats, respond to prolactin; administration of oestradiol to OVX rats diminishes the response. In order to determine if a correlation exists between lymphocyte responsiveness to prolactin and levels of cell surface prolactin receptors (PRL-R) expression, the percentage of splenocytes and each splenocyte subpopulation expressing surface PRL-R from rats of various hormonal states (OVX, oestradiol-injected OVX, oestrus and male) was analysed by single-colour and dual-colour flow cytometric analysis. We found that approximately 20% of splenocytes expressed surface PRL-R regardless of hormonal states (n = 16). The majority (85%) of PRL-R positive splenocytes were B lymphocytes whereas 11.1% and 4.8% of splenocytes expressing the PRL-R were CD4 positive T-helper (TH) and CD8 positive T-cytotoxic (TC) lymphocytes, respectively. B lymphocytes also stained more brightly than T lymphocytes. This distribution of PRL-R expression did not show significant alterations on total splenocytes or TH and TC lymphocytes during various hormonal stages. However, the percentage of PRL-R-positive B lymphocytes increased markedly in OVX rats (twofold), compared to rats at oestrus. In summary, no correlation was found between the responsiveness to prolactin as a mitogen and levels of PRL-R expression by lymphocytes from rats at different hormonal states. This result suggests that sex steroid hormones may control prolactin responsiveness of lymphocytes by affecting the signal transduction pathway through PRL-R rather than by altering the level of the cell surface receptor expression.
Citation - WoS: 1
Citation - Scopus: 2
Synthesis and Characterization of Amido and Amido(monoalkylamido)nitrosyl-[tris(3,5 Complexes
(Marcel Dekker Inc., 1997) Topaloğlu, Işıl; Sözüer, Işıl; McCleverty, Jon A.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
The chloro-amido complex [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl(NH 2)] was prepared by treating [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl 2] with an excess of ammonia. The monoalkylamido complexes [Mo{HB(3,5-Me2C3HN2)3}-(NO)(NH 2)(NHR)] (R = Me, Et, Pr-n and Bu-n) were obtained by the reaction of [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl(NH 2)] with the appropriate primary amines. The IR and 1H NMR spectra of the new complexes were investigated.
Native and Light Induced Defect States in Wide Band Gap Hydrogenated Amorphous Silicon-Carbon (a-Si1 : H) Alloy Thin Films
(Springer, 1997) Güneş, Mehmet; Güneş, Mehmet; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
In this study, wide band gap a-Si1-x C-x:H alloy thin films prepared with and without hydrogen diluation of (SiH4, CH4) were characterized using optical absorption, dark conductivity, steady-state photoconductivity, sub-bandgap absorption obtained with both photothermal deflection spectroscopy (PDS) and dual beam photoconductivity (DBP), and electron spin resonance (ESR) techniques. Experimental results of steady-state photoconductivity and sub-bandgap absorption for different generation rates were analyzed using a detailed numerical model based on Simmons-Taylor statistics. The densities, energy location and nature of the native and light induced defect states in diluted and undiluted a-Si1-xCx:H alloy thin films were derived from the best fits to the experimental data. The extracted parameters for defect states were compared with those of a-Si:H films both in the annealed and light degraded states.
Citation - WoS: 37
Citation - Scopus: 40
Differences in the Densities of Charged Defect States and Kinetics of Staebler-Wronski Effect in Undoped (nonintrinsic) Hydrogenated Amorphous Silicon Thin Films
(American Institute of Physics, 1997-04) Güneş, Mehmet; Güneş, Mehmet; Wronski, Christopher R.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
A variety of undoped (nonintrinsic) hydrogenated amorphous silicon (a-Si:H) thin films was studied in greater detail using steady-state photoconductivity, σph, subband-gap absorption, α(hν), steady-state photocarrier grating (SSPG), and electron-spin-resonance (ESR) techniques both in the annealed and stabilized light soaked states. The experimental results were self-consisiently modeled using a detailed numerical analysis. It was found that large differences in the optoelectronic properties of device quality a-Si:H thin films can only be explained using a gap slate distribution which consists of positively charged D+ defect states above the Fermi level, the neutral D0 defect states, and the negatively charged D- defect states below the Fermi level. There are large differences both in the densities of neutral and charged defect states and R ratios in different a-Si:H films in the annealed state. The densities of both neutral and charged defect states increased, however, R ratios decreased in the stabilized light soaked state. Very good agreement was obtained between the densities of neutral defect states measured by ESR and those derived from the numerical analysis in the stabilized light soaked state. The kinetics of the Staebler-Wronski effect was also investigated. There was no direct correlation between the decrease of steady-state photoconductivity and increase of subband-gap absorption. The self-consistent fits to wide range of experimental results obtained with the three Gaussian distributions of charged defect states imply that this model is much better representation of the bulk defect states in undoped hydrogenated amorphous silicon thin films.
Citation - WoS: 15
Citation - Scopus: 14
Prolactin Receptor Gene Expression in Rat Splenocytes and Thymocytes During Oestrous Cycle, Pregnancy and Lactation
(John Wiley and Sons Inc., 1997-05) Güneş, Hatice; Güneş, Hatice; Mastro, Andrea M.; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
Much evidence suggests that prolactin (PRL) has an immunoregulatory function. Part of this evidence is that the receptors for PRL are present on lymphocytes. Probably the effects of PRL on cells of the immune system depend on the level and specific forms of PRL-R present on the target cells. Therefore, PRL-R expression at both protein and mRNA levels was examined during oestrous cycle, pregnancy and lactation using Western blotting and PCR analysis. Antibody to the long form of PRL-R detected 84 and 42 kDa protein bands in the spleen but only 84 kDa band in the thymus. The expression pattern of these two protein bands was different in the spleen, suggesting that these two isoforms of PRL-R long form are differentially regulated by the hormones of oestrous cycle. In addition, depending on the tissue, the level of mRNA for the short and long forms of PRL-R showed a significant change at different stages of oestrous cycle. Moreover, 42 and 84 kDa PRL-R bands were detected in both spleen and thymus throughout the pregnancy and lactation; however, the expression pattern of 84 kDa protein band was different between tissues. This finding suggests that each tissue exhibits differential response to hormones which affect PRL-R content.
Citation - WoS: 2
Citation - Scopus: 3
The Amido and Bisalkoxo-Complexes of [tri(3,5-Dimethylpyrazolyl)borato]molydenum Nitrosyl
(TÜBİTAK, 1998) Topaloğlu, Işıl; Sözüer, Işıl; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
In this study, the amido nitrosyl molybdenum complex, [Mo{HM(3,5-Me2C3HN2)3}(NO)Cl(NH 2)], was prepared. This compound reacts with alocohols, yielding the bisalkoxo complexes, [Mo{HM(3,5-Me2C3HN2)3}(NO)(OR) 2] (R = Me, Et, Prn, Bun). The new complexes were analyzed by IR and 1H-NMR spectroscopy.
Citation - WoS: 5
Citation - Scopus: 7
Higgs Field as the Gauge Field Corresponding To Parity in the Usual Space-Time
(World Scientific Publishing Co. Pte Ltd, 1998-02) Erdem, Recai; Erdem, Recai; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
We find that the local character of field theory requires the parity degree of freedom of the fields to be considered as an additional discrete fifth dimension which is an artifact emerging due to the local description of space-time. Higgs field can be interpreted as the gauge field corresponding to this discrete dimension. Hence the noncommutative geometric derivation of the standard model follows as a manifestation of the local description of the usual space-time.
1/Nc Expansion and Anomaly Cancellation in the Presence of Electroweak Interactions
(IOP Publishing Ltd., 1998-03) Erdem, Recai; Erdem, Recai; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
We study the question of a consistent formulation of the 1/Nc expansion in the presence of electroweak interactions. We show that in some cases the previous formulation leads to an unrealistic picture. We improve the scheme. We derive the corresponding hypercharge and electric charge values of fermions under the requirement that the standard model in the large-Nc limit should be free of chiral gauge anomalies. We find that the resulting hypercharge and the electric charge values for quarks are the same as for the standard model.
Citation - WoS: 57
Determination of Plutonium in Seawater Using Co-Precipitation and Inductively Coupled Plasma Mass Spectrometry With Ultrasonic Nebulisation
(Elsevier Ltd., 1998-07-06) Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; McLeod, Cameron W.; Leonard, Kinson S.; McCubbin, David; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
A flow injection–inductively coupled plasma–mass spectrometric (FI–ICP–MS) procedure, utilising ultrasonic nebulisation with membrane desolvation (USN/MD), has been developed for the determination of plutonium (Pu) in seawater at fg l−1 concentration levels. Seawater samples (1 l), after filtration, were subjected to co-precipitation with NdF3, followed by ion exchange to enrich Pu and to reject seawater matrix ions and co-existing uranium. The seawater concentrate (1.0 ml) was then analysed by FI–ICP–MS. The limit of detection for in seawater based on an enrichment factor of 1000 was 5 fg l−1, and precision at the 0.80 pg l−1 level was 12% RSD. Accuracy was verified via recovery experiments, and by comparing survey data for the Irish Sea with that derived by standard methodology based on co-precipitation and α-spectrometry. Concentrations for dissolved in the Irish Sea were in the range of 0.267–0.941 pg l−1 (0.614–2.164 mBq l−1) and 0.051–0.196 pg l−1 (0.428–1.646 mBq l−1), respectively.
Citation - WoS: 46
Determination of Technetium in Sea-Water Using Ion Exchange and Inductively Coupled Plasma Mass Spectrometry With Ultrasonic Nebulisation
(Royal Society of Chemistry, 1998-09) Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; McLeod, Cameron W.; Leonard, Kinson S.; McCubbin, David; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
An enrichment–separation scheme employing a strong-base type anion-exchange resin was developed for the determination of99Tc in sea-water by inductively coupled plasma mass spectrometry utilising ultrasonic nebulisation with membrane desolvation. Samples were processed through an anion-exchange column to enrich Tc and to eliminate sea-water matrix ions. The limit of detection for 99Tc in sea-water based on processing a 14 ml sample was 0.03 ng l–1. Accuracy was verified with spike recovery experiments. The potential for rapid on-line sample processing via a microcolumn–flow injection system was demonstrated.
Citation - WoS: 9
A novel sorbent tube for ambient hydrogen sulfide determination
(Elsevier Ltd., 1998-11) Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; Volkan, Mürvet; Eroğlu, Tijen; Ataman, O. Yavuz; Mark, Harry B.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
A novel tubular device has been developed for hydrogen sulfide determination in air. Several substrates such as commercial silica gel and alumina TLC plates, silica gel powder, alumina, CaSO4, CaCO3, BaSO4, MgO, chalk, α-cellulose and ethyl cellulose were tested as solid substrates. 30–70-mesh silica gel was finally employed in glass tubes of 4.0 mm internal diameter. Silica gel is treated with 0.5 M aqueous CdCl2 solution, dried, filled into the glass tube and sample gas is passed through the device using nitrogen as the carrier gas where 70% relative humidity is employed. The analyte reacts with the solid substrate to form a luminescent spot whose length in the tube is measured and correlated to concentration. The flow rate was 68 ml min−1. The analytical system is linear in the range of 0.2–1.3 ppm H2S for the specified conditions. The prepared devices are stable at least for 3 months prior to sampling; and after sampling, the luminescing spot is stable also at least for 3 months.
Citation - WoS: 1
Citation - Scopus: 4
Synthesis and Characterization of a New Mono-Molybdenated Metallo-Ligand [mo{hb(3,5-Me2c3hn2)3}(no)cl(oc 6h4pph2-P)]
(Marcel Dekker Inc., 1999) Topaloğlu, Işıl; Sözüer, Işıl; McCleverty, Jon A.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
The "metallo-ligands" can be considered effectively as a modified triphenylphosphine ligand, and used to generate novel transtion metal complexes in which electron-transfer and magnetism is embedded within the stable ligand framework. A new mono-molybdenated metallo-ligand was synthesized and characterized by NMR (1H and 31P-{1H}), IR and mass spectroscopy techniques as a starting material in the search for designing novel bimetallic complexes exhibiting optoelectronic properties and development of non-linear optical materials that possess commercial device applications.
Citation - WoS: 15
Citation - Scopus: 14
1/F-noise Study of Undoped Intrinsic Hydrogenated Amorphous Silicon Thin Films
(American Physical Society, 1999) Güneş, Mehmet; Güneş, Mehmet; Johanson, Robert E.; Kasap, Safa O.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
Conductance fluctuations in four samples of undoped intrinsic hydrogenated amorphous silicon (a-Si:H) were measured in the temperature range of 450 K to 500 K and for frequencies from 2 Hz to 3 kHz. The noise spectra divide into two regions that each fit a 1/fα power law but with different slope parameters α and different temperature dependences. At low frequencies, α is greater than unity and increases with temperature. At high frequencies, α is near 0.6 and temperature independent, but the noise magnitude decreases rapidly with temperature. We infer from the different dependences on temperature that the noise is generated by two independent mechanisms operating simultaneously in a-Si:H. We also observe that the 1/f noise exhibits a quadratic dependence on bias current and Gaussian statistics.
Nonlinear Inorganic Optical Materials
(Ege Üniversitesi, 1999) Topaloğlu, Işıl; Sözüer, Işıl; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
Ticari olarak uygulamaları bulunan nonlinear optik materyallerin geliştirilmesi için yapılmakta olan çalışmalar özellikle 1980 yılından sonra artış göstermiştir. Bu amaçla incelenen sistemler arasında inorganik kristaller, yarı iletkenler, organometalik bileşikler, organik kristalin monomerler, ve delokalize $\Pi$ elektronları içeren uzun zincirli polymerler Informasyon işlemlerinde optik çevirme, telekominikasyon, optoteknoloji, ve optik frekans çevirme amaçlı olarak çok yaygın olarak kullanılmaktadır. Bu derleme makalesinde nonlinear optik özellik gösteren inorganik bileşikler hakkında kısa bilgi verilmiştir.
Sitokinlerin Hücre Döngüsü Üzerinde Etkileri
(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 1999) Güneş, Hatice; Güneş, Hatice; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
Sitokinler hücresel düzenleyici proteinlerdir. Vücudun farklı dokularında çesitli hücreler tarafından belli uyarıcılara karsı salgılanıp pek çok farklı biyolojik fonksiyonları kontrol eden sitokinlerin en önemli etkilerinden biri hücre bölünmesi üzerindedir. Bazı sitokinler hücre döngüsünün ilerlemesinde pozitif rol oynarken, bazıları hücre bölünmesini engelleyici etki gösterirler. Sitokinlerin hücre bölünmesi üzerindeki pozitif ve negatif etkileri hücre tipine baglı olarak degisir. Burada bazı sitokinlerin hücre döngüsü üzerindeki etkilerinin moleküler mekanizmaları anlatılmıstır.
Citation - Scopus: 15
Estimation of the Average Aromatic Cluster Size Based on Solid-State Nmr Measurement of Coal
(Japan Institute of Energy, 1999) Kidena, Koh; Artok, Levent; Murata, Satoru; Artok, Levent; Nomura, Masakatsu; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
Measurements of solid-state NMR of eight Argonne Premium Coal Samples were conducted to estimate the average aromatic cluster size in these coals. Firstly, the carbon distribution was obtained from SPE/MAS 13C-NMR. Secondary, 1H-CRAMPS NMR spectra gave the hydrogen aromaticity of coal. Combination use of the hydrogen aromaticity and elemental analysis data could afford the amount of tertiary aromatic carbon. The parameter of χ b, the mole fraction of aromatic bridgehead carbons in all aromatic carbons, could be derived from above NMR data and elemental analysis of coal. χ b is directly correlated to the number of aromatic carbon atoms per aromatic cluster, C. In this study, the value of C varied from 10 (corresponding to the size of naphthalene) for Beulah-Zap and Wyodak coals to 23 (corresponding to the size of coronene) for Pocahontas No. 3 coal.

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