Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Conference Object Heavy Metal Removal Using Natural Zeolite Packed Ion Exchange Column(American Chemical Society, 2008) Balköse, Devrim; Ülkü, Semra[No abstract available]Book Part A Review: Preparation, Characterization and Applications of Magnesium Stearate, Cobalt Stearate and Copper Stearate(Nova Science Publishers, 2010) Egbuchunam, Theresa O.; Gönen, Mehmet; Balköse, Devrim; İnal, Fikret; Ülkü, SemraMetal soaps, such as zinc, calcium, copper, magnesium are insoluble or sparingly soluble in water. Because of this property, they are commercially important compounds and find applications in industry, such as driers in paints or inks, components of greases, stabilizers for plastics, in fungicides, catalysts, waterproofing agents, fuel additives, components of creams and additive in drug formulation and etc. Magnesium stearate is in widespread use as gelling, sanding and anti-sticking agents, stabilizer, lubricant, emulsifier and plasticizer for polymers, in the paint, food, rubber, paper and pharmaceutical industries. Copper stearate is used mainly for rot-proofing textiles, ropes, etc. It is also used in paints since they are soluble in oils, white spirits, etc. Quartz crystals coated with CuSt2 was used in the detection of volatile organic compounds. Cobalt stearate has applications in producing Co nests, mesoporous silica, as adhesion promoter. © 2014 by Nova Science Publishers, Inc. All rights reserved.Conference Object Citation - Scopus: 1Yapay Sindirim Sıvısında Doğal Zeolitlerde Meydana Gelen Morfolojik Değişmeler(Institute of Electrical and Electronics Engineers Inc., 2009) Demirbüker Kavak, Dilek; Özçelik, Serdar; Ülkü, SemraDoğal zeolitler biyoaktif maddelerdir. Doğal zeolitlerin hayvanlarda biyokütle arttırıcı besi katkı maddesi, insanlarda ülser tedavisinde mide asitliğini tamponlayıcı, asitliği düşürücü ilaç gibi değişik kullanım alanları mevcuttur. Değişik sağlık alanlarında kullanımlarından dolayı, zeolitlerin yapısal stabilitesinin sindirim sırasında belirlenmesi; olası olumlu veya olumsuz etkileşimleri anlamak açısından önem taşımaktadır. Gerçekleştirilen araştırmada, yapay sindirim sırasında zeolitte meydana gelebilecek olası morfolojik değişimlerin incelenmesi hedeflenmiştir. Bu amaçla zeolitin ABTS ile radikal sönümleme kapasitesi araştırılmış, yapay sindirim denemeleri gerçekleştirilerek de uygulama süreci sonrası yapıda olası değişimler ve adsorpsiyonlar taramalı elektron mikroskobu, FTIR, XRD analizleri ile incelenmiştir. 3g/100ml zeolitin ABTS radikalini %45 inhibe ettiği bulunmuştur. Taramalı elektron mikroskobu deneyleri sonucunda yapay sindirilmiş örneklerin yüzey morfolojisinde değişim gözlenmemiştir. Element analizleri yapısal kaybın olmadığını, Al ve Si elementlerinin ağırlıkça yüzdelerinin, kontrol örnekleriyle (Al:8.1; Si: 39) sindirilmiş örneklerde (Al:8.2; Si: 38.3) yaklaşık aynı olduğunu göstermiştir. Infrared spektrum (IR) ve X-ray ışını kırınımı analizleri sonuçları ise bu bulguları doğrulamıştır. Ayrıca taramalı elektron mikroskobu ve IR spektrum sonuçları yapay sindirim ortamındaki maddelerin, zeolit yüzeyinde adsorplanmadıklarıını göstermektedir. Sonuç olarak doğal zeolitler, yapay sindirim sırasında yapısal stabilitelerini kaybetmemektedirler.Article Citation - Scopus: 5Effect of Isotherm Shape on Mass Transfer in an Adsorbent Particle; an Isothermal Adsorption Process(Bentham Science Publishers B.V., 2011) Yıldırım, Zeynep Elvan; Gediz İliş, Gamze; Mobedi, Moghtada; Ülkü, SemraThe mass diffusion equation and corresponding initial and boundary conditions were non-dimensionalized for a spherical adsorbent particle in an infinite adsorptive medium to reduce number of independent governing parameters into two as mass transfer Biot number and dimensionless isotherm. The changes in local and average adsorbate concentration throughout the adsorption process were calculated and plotted for different values of mass transfer Biot numbers (ranging from 0.5 to 750) and for five different isotherm shapes. The obtained results indicated that the isotherm shape influences dimensionless period of adsorption, if the external mass transfer resistance is significant in the process. For those cases, the total dimensionless adsorption period for a convex shape isotherm is shorter than a concave one.Article Citation - WoS: 42Citation - Scopus: 60Pistacia Terebinthus Extract: as a Potential Antioxidant, Antimicrobial and Possible Ss-Glucuronidase Inhibitor(Elsevier Ltd., 2010) Demirbüker Kavak, Dilek; Altıok, Evren; Bayraktar, Oğuz; Ülkü, SemraIn this study, inhibition of Escherichia coli glucuronidase (GUS) by a plant extract of Pistacia terebinthus was investigated. P. terebinthus (from Karaburun region in Turkey) leaf extract exhibits various bioactivities, such as antioxidant, antimicrobial and cytotoxic property because of its flavonoid, phenolic and alkaloid contents. HPLC analyses were performed to evaluate the composition of the extract and main flavonoid compounds such as luteolin, luteolin-7-glucoside and apigenin-7-glucoside were detected in extract. GUS activity and kinetic data of the GUS were obtained by measuring rate of production of resulting fluorescent 4-methylumbelliferone (4-MU) and phenolphthalein fluorometrically and spectrophotometrically, respectively. Plant leaves showed higher antioxidant capacity as 85 TEAC (trolox equivalent antioxidant capacity) value and higher antimicrobial activity towards Staphylococcus aureus. 92.4% GUS enzyme inhibition was achieved with 8.3 μg ml-1 crude extract concentration, where IC50 value was found as 2.1 (±0.2) μg ml-1. Kinetic studies by nonlinear regression revealed that inhibition type caused by plant extract was mixed type (noncompetitive and competitive together). Km and Vmax values were 96.94 ± 9.68 nM and 7.81 ± 0.16 nmol min-1 mg-1, respectively. Inhibition constant (αKi) was found as 7.00 ± 0.93 nM having α value 2.17 ± 0.93. Our results may provide useful information regarding the inhibition of microbial GUS activity, preventing deglucuronidation and reducing possible cancer risk by bioactive P. terebinthus crude extract. © 2010 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 7Citation - Scopus: 8Acylation of 2-Methoxynaphthalene Over Ion-Exchanged Ss-Zeolite(Elsevier Ltd., 2002) Kantarlı, İsmail Cem; Artok, Levent; Bulut, Hatice; Yılmaz, Selahattin; Ülkü, SemraFriedel-Crafts acylation of 2-Methoxynaphthalene was carried out over various ion-exchanged β zeolites (Mn+β, where Mn+: In3+, Zn2+, Al3+, Fe3+, La3+) with various anhydride (acetic, propionic and benzoic anhydrides), or acyl chloride (acetyl, propionyl and benzoyl chlorides) acylating reagents. The results suggested that selectivity towards the 6-substituted products was higher with the larger size anhydrides, propionic and benzoic anhydrides. The metal cation type within the zeolite significantly influenced the extent of conversion and product distribution. That La3+ exchanged zeolite displayed higher selectivity for the 6-position acylated product with anhydrides ascribed mainly to narrowing of channels by the presence of La(OH)2+ ions that leave no room for the formation of more bulky isomeric forms and to enhanced Bronsted acidity of the zeolite. With acyl chlorides, the recovery of ketone products was found to be remarkably low. 1-Acyl-2-methoxynaphthalenes actively underwent deacylation when acyl chlorides were used as the acylation reagent.