Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Research Project Ultrason kontrast ajanlarının geliştirilmesi ve karakterizasyonu(2012) Özdemir, Sevgi Kılıç; Özdemir, Ekrem; Okur, SalihUltrasonografi, bata koroner kalp damar hastalklar (ekokardiografi) olmak üzere, çeitli hastalklarn tehisinde kullanlan ve maliyet etkinli i olan bir diagnostik görüntüleme yöntemidir. Ultrasonda görüntü, transdüserden gönderilen ses dalgalarnn geriye yansmas sonucu olumaktadr. Ancak, baz durumlarda çevreleyen dokulardan gelen arka plan sinyaller yöntemin hassasiyetini azaltmakta, do ru tehis için yeterince net bir görüntü elde edilememektedir. Görüntü kalitesinin artrlmas için kontrast ajan olarak adlandrlan mikroköpükçükler kullanlmaktadr. Ayrca, mikroköpükçükler ilaç, gen, ve DNA tamakta ve kontrollü salmlarda da kullanlmaktadr. Mikroköpükçüklerin bu ve daha nitelikli alanlarda kullanlabilmeleri için, yaplarnn güçlendirilmesi ve stabilitelerinin artrlmalar gerekmektedir.Article Citation - WoS: 9Citation - Scopus: 9Hollow Nano-caco3's Voc Sensing Properties: a Dft Calculation and Experimental Assessments(Elsevier, 2023) Bayram, Abdullah; Farzaneh, Amir; Esrafili, Mehdi D.; Okur, Salih; Özdemir, EkremAir is the most critical and necessary for life, and air quality significantly impacts people's health. Both indoor and outdoor pollution frequently contain volatile organic compounds (VOCs). Such contaminants provide immediate or long-term health risks to the living system. The present study investigates sorption characteristics of VOCs on hollow nano calcite (CaCO3) particles with 250 nm and 40 nm pore sizes to remove from the air ambient using the quartz crystal microbalance (QCM) technique at room temperature both experimentally and theoretically. The results were supported by density functional theory (DFT), and adsorption-desorption characteristics were studied with Langmuir adsorption isotherms. The QCM measurements showed a stable signal without having hysteresis, and the response of polar VOCs on hollow nano-CaCO3 particles such as ethanol, propanol, and humidity with higher polarity was less compared to solvents such as chloroform and dichloromethane, which revealed that the surfaces of CaCO3 particles have mostly non-polar properties. CaCO3 surface and VOC molecule interactions overlap with the Langmuir model. With DFT calculations, VOC and water molecule adsorption changes the CaCO3 Egap. Our findings show that the ΔEgap values increase as chloroform > dichloromethane > propanol > ethanol > water. This order suggests that the sensing response of the hollow CaCO3 structure is linearly proportional to the adsorption energies of VOC and water. The linear adsorption characteristics, high sensing response, and short recovery time illustrated that the newly synthesized nano-CaCO3 could be implemented as a new VOC adsorbent material for health, environmental sustainability, and in vitro microbiome cultures.Article Citation - WoS: 60Citation - Scopus: 66Preparation and Characterization of Calcium Stearate Powders and Films Prepared by Precipitation and Langmuir-Blodgett Techniques(American Chemical Society, 2010) Gönen, Mehmet; Öztürk, Serdar; Balköse, Devrim; Okur, Salih; Ülkü, SemraThe preparation of calcium stearate (CaSt2) using precipitation and Langmuir-Blodgett techniques was investigated in this study. While sodium stearate and calcium chloride were used in the precipitation process, calcium stearate nanofilms were produced from stearic acid and calcium chloride in sodium borate buffer with the Langmuir-Blodgett technique. Fourier transform infrared (FTIR) spectroscopy indicated carboxylate bands at 1577 and 1543 cm-1 in equal intensity in the powder form, but the films had a higher intensity 1577 cm-1 band than the 1543 cm-1 band. This showed the calcium ions associated with the COO- ions in the monodendate and bidendate structures in powders, and it was mainly in the bidendate structure in films. While characteristic peaks of CaSt2 at 2θ values of 6.40° and 19.58° were obtained in the X-ray diffraction (XRD) pattern of the dried powdered product, no sharp peaks were present in the 13 layer CaSt2 film. From scanning electron microscopy (SEM) micrographs, it was seen that calcium stearate powder had lamellar structure and the average particle size was 600 nm. The AFM picture of the CaSt2 film indicated the surface was not smooth with a peak to valley distance of 6 nm. © 2010 American Chemical Society.Article Citation - WoS: 20Citation - Scopus: 23Effect of Humidity on Electrical Conductivity of Zinc Stearate Nanofilms(Elsevier Ltd., 2007) Öztürk, Serdar; Balköse, Devrim; Okur, Salih; Umemura, JunzoIn this work, stearic acid (StAc) and zinc stearate (ZnSt2) nanofilms were deposited on glass and silver substrates using Langmuir-Blodgett (LB) film technique and their structural and electrical properties were investigated. X-ray diffraction and IR techniques revealed that more crystalline and better films were obtained from ZnSt2 compare to StAc. Electrical conductivity of ZnSt2 LB films with 13 layers having 28 nm thickness were measured in the range of humidity of 20-60% and it is seen that the conductivity was very sensitive to relative humidity (RH) above 40% at 25 °C and showed no hysteresis during adsorption and desorption of water vapor. Water vapor adsorption isotherm of ZnSt2 powders was determined and conductivity increase with humidity was attributed to water vapor adsorption. Constant electrical conductivity of the ZnSt2 films at low relative humidities and at low voltage values is an advantageous property which allows using them as organic nanofilms with insulating properties.