Browsing by Subject "Ethanol"
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Item Open Access Encapsulation of gallic acid/cyclodextrin inclusion complex in electrospun polylactic acid nanofibers: release behavior and antioxidant activity of gallic acid(Elsevier, 2016-06) Aytac Z.; Kusku S. I.; Durgun, Engin; Uyar, TamerCyclodextrin-inclusion complexes (CD-ICs) possess great prominence in food and pharmaceutical industries due to their enhanced ability for stabilization of active compounds during processing, storage and usage. Here, CD-IC of gallic acid (GA) with hydroxypropyl-beta-cyclodextrin (GA/HPβCD-IC) was prepared and then incorporated into polylactic acid (PLA) nanofibers (PLA/GA/HPβCD-IC-NF) using electrospinning technique to observe the effect of CD-ICs in the release behavior of GA into three different mediums (water, 10% ethanol and 95% ethanol). The GA incorporated PLA nanofibers (PLA/GA-NFs) were served as control. Phase solubility studies showed an enhanced solubility of GA with increasing amount of HPβCD. The detailed characterization techniques (XRD, TGA and 1H-NMR) confirmed the formation of inclusion complex between GA and HPβCD. Computational modeling studies indicated that the GA made an efficient complex with HPβCD at 1:1 either in vacuum or aqueous system. SEM images revealed the bead-free and uniform morphology of PLA/GA/HPβCD-IC-NF. The release studies of GA from PLA/GA/HPβCD-IC-NF and PLA/GA-NF were carried out in water, 10% ethanol and 95% ethanol, and the findings revealed that PLA/GA/HPβCD-IC-NF has released much more amount of GA in water and 10% ethanol system when compared to PLA/GA-NF. In addition, GA was released slowly from PLA/GA/HPβCD-IC-NF into 95% ethanol when compared to PLA/GA-NF. It was also observed that electrospinning process had no negative effect on the antioxidant activity of GA when GA was incorporated in PLA nanofibers.Item Open Access Generation of InN nanocrystals in organic solution through laser ablation of high pressure chemical vapor deposition-grown InN thin film(Springer, 2012-07-27) Alkis, S.; Alevli, M.; Burzhuev, S.; Vural, H. A.; Okyay, Ali Kemal; Ortaç, B.We report the synthesis of colloidal InN nanocrystals (InN-NCs) in organic solution through nanosecond pulsed laser ablation of high pressure chemical vapor deposition-grown InN thin film on GaN/sapphire template substrate. The size, the structural, the optical, and the chemical characteristics of InN-NCs demonstrate that the colloidal InN crystalline nanostructures in ethanol are synthesized with spherical shape within 5.9-25.3, 5.45-34.8, 3.24-36 nm particle-size distributions, increasing the pulse energy value. The colloidal InN-NCs solutions present strong absorption edge tailoring from NIR region to UV region.Item Open Access Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution(Springer Netherlands, 2016-05) Demirel, A.; Öztaş T.; Kurşungöz, C.; Yılmaz, İ.; Ortaç, B.We demonstrate the synthesis of GaN nanocrystals (NCs) with the sizes of less than the doubled exciton Bohr radius leading quantum confinement effects via a single-step technique. The generation of colloidal GaN nanoparticles (NPs) in organic solution through nanosecond (ns) and femtosecond (fs) pulsed laser ablation (PLA) of GaN powder was carried out. Ns PLA in ethanol and polymer matrix resulted in amorphous GaN-NPs with the size distribution of 12.4 ± 7.0 and 6.4 ± 2.3 nm, respectively, whereas fs PLA in ethanol produced colloidal GaN-NCs with spherical shape within 4.2 ± 1.9 nm particle size distribution. XRD and selected area electron diffraction analysis of the product via fs PLA revealed that GaN-NCs are in wurtzite structure. Moreover, X-ray photoelectron spectroscopy measurements also confirm the presence of GaN nanomaterials. The colloidal GaN-NCs solution exhibits strong blue shift in the absorption spectrum compared to that of the GaN-NPs via ns PLA in ethanol. Furthermore, the photoluminescence emission behavior of fs PLA-generated GaN-NCs in the 295–400 nm wavelength range is observed with a peak position located at 305 nm showing a strong blue shift with respect to the bulk GaN.Item Open Access Utilization of ethanol to enhance photocatalytic NOx oxidation and storage on TiO2(Bilkent University, 2023-06) Türk, Ahmet ArdaNitrogen oxides (NOx), especially nitric oxide (NO) and nitrogen dioxide (NO2) severely affect human health. In this regard, semiconductor photocatalysis present an appealing approach, since the only requirements for this procedure are sunlight, water and oxygen which are naturally abundant. Despite its favorable properties like chemical inertness, long-term stability and low cost, titania (TiO2) has a lower NOx abatement performance due to its low selectivity towards nitrites/nitrates as final product. In this work, we report a simple monohydric alcohol impregnation protocol at mild temperature range to synthesize colored TiO2 nanoparticles for efficient photocatalytic NOx oxidation and storage (PHONOS) application under UVA illumination. The ethanol induced coloration of commercial benchmark TiO2 (P25) and photocatalytic activity for NOx abatement were observed to be dependent on heat-treatment temperature; the highest activity was obtained at 150 °C. Comprehensive analyses of the optimized photocatalyst suggest the presence of surface functionalities of adsorbed formic acid and acetate. The doping of TiO2 with these in situ generated impurities results in the generation of Ti3+ and oxygen vacancies (Vos) (intrinsic defects) which are aimed to be observed using X-Ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy and Diffuse Reflectance UV Visible Spectroscopy (DR-UV-Vis). These fine-tuned materials demonstrated superior photocatalytic performance surpassing conventional P25 benchmark in short (1 h) and long term (15 h) evaluation studies. Special attention has been paid to the selectivity of the designed photocatalyst toward nitrate/nitrite formation and CaO was introduced as NOx storage domains to further improve the stability of best performing photocatalysts for extended time period.