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Öğe Aliphatic Polyester Nanofibers Functionalized with Cyclodextrins and Cyclodextrin-Guest Inclusion Complexes(Mdpi, 2018) Narayanan, Ganesh; Shen, Jialong; Boy, Ramiz; Gupta, Bhupender S.; Tonelli, Alan E.The fabrication of nanofibers by electrospinning has gained popularity in the past two decades; however, only in this decade, have polymeric nanofibers been functionalized using cyclodextrins (CDs) or their inclusion complexes (ICs). By combining electrospinning of polymers with free CDs, nanofibers can be fabricated that are capable of capturing small molecules, such as wound odors or environmental toxins in water and air. Likewise, combining polymers with cyclodextrin-inclusion complexes (CD-ICs), has shown promise in enhancing or controlling the delivery of small molecule guests, by minor tweaking in the technique utilized in fabricating these nanofibers, for example, by forming core-shell or multilayered structures and conventional electrospinning, for controlled and rapid delivery, respectively. In addition to small molecule delivery, the thermomechanical properties of the polymers can be significantly improved, as our group has shown recently, by adding non-stoichiometric inclusion complexes to the polymeric nanofibers. We recently reported and thoroughly characterized the fabrication of polypseudorotaxane (PpR) nanofibers without a polymeric carrier. These PpR nanofibers show unusual rheological and thermomechanical properties, even when the coverage of those polymer chains is relatively sparse (similar to 3%). A key advantage of these PpR nanofibers is the presence of relatively stable hydroxyl groups on the outer surface of the nanofibers, which can subsequently be taken advantage of for bioconjugation, making them suitable for biomedical applications. Although the number of studies in this area is limited, initial results suggest significant potential for bone tissue engineering, and with additional bioconjugation in other areas of tissue engineering. In addition, the behaviors and uses of aliphatic polyester nanofibers functionalized with CDs and CD-ICs are briefly described and summarized. Based on these observations, we attempt to draw conclusions for each of these combinations, and the relationships that exist between their presence and the functional behaviors of their nanofibers.Öğe Blend Films of Cellulose and Soy Protein Isolate Prepared from Gamma Irradiated Solutions(Namık Kemal Üniversitesi, 2018) Boy, Ramiz; Bourham, Mohamed; Kotek, RichardBlend solutions of cellulose and soy protein isolate were prepared by utilizing an amine/salt solvent system. The solutions were gamma irradiated before casting blend films that have more stable molecular network than the ones cast from non-irradiated solutions. Due to irradiation, the interactions between the two polymers altered and shifted that were analyzed by infrared spectroscopy. The thermal analysis showed small differences of thermal stability between the films formed from irradiated and non-irradiated solutions. Up to 10 kGy irradiation dose on the solutions, the resulting films exhibited higher elongation at break. Furthermore, their transparency lowered. Despite their transparency, the films absorbed less water indicating the effect of gamma irradiation on the molecular structure.Öğe Effects of freeze-thawing cycles on the physical and mechanical properties of basaltic and dolomitic rocks evaluated with a decay function model(Springer Science and Business Media Deutschland GmbH, 2021) Aral, İbrahim Feda; Boy, Ramiz; Dinçer, Ali RızaBasalts from Çorlu Karatepe and dolomite from Kırklareli subjected to freeze-thawing (F-T) cycles were studied, and the resulting changes were analyzed. The unweathered rocks and those subjected to 50 F-T cycles after every 10 cycles were tested for the water absorption by weight and volume, P-wave velocity, uniaxial compression strength, point load strength index, and Schmidt hardness values under laboratory conditions. In addition, the relationship between physical and mechanical properties was examined after every 10 cycles, and an exponential model was proposed for the mechanical properties. Two model-generated parameters, i.e., the decay constant and half-life value for each mechanical property, were used to evaluate the disintegration rate of the rocks under the cyclical action of F-T. The evaluation suggests that disintegration behavior was not comparable between the two types of rocks. However, the basalt samples had similar mechanical properties, which indicated a high degree of correlation. © 2021, Springer-Verlag GmbH Germany, part of Springer Nature.Öğe Novel membranes regenerated from blends of cellulose/gluten using ethylenediamine/potassium thiocyanate solvent system(Tech Science Press, 2019) Yu, Yang; Boy, Ramiz; Kotek, RichardCurrent industrial methods for dissolution of cellulose in making regenerated cellulose products are relatively expensive, toxic and dangerous and have environmental problems coming with the hazard chemical wastes. To solve these problems, a novel ethylenediamine and potassium thiocyanate (ED/KSCN) solvent system was developed, that is economical, ecofriendly, and highly efficient. The ED/KSCN solvent system was proven to be a suitable solvent for fabricating cellulose (blended with other polymers) membranes. In this study, gluten was used to develop nonporous membranes with cellulose. The method of casting these membranes provided better ones than the former researchers’ techniques. These composite membranes’ physical and mechanical properties were studied by analysis of morphology, viscosity, crystallinity, thermal behaviors, tensile properties and water absorption of membranes. Results showed that membranes are nonporous, uniform, strong, flexible, ecofriendly and renewable. Mechanical and physical properties were influenced by the ratio of cellulose/gluten. By blending 40% gluten, the tensile strength of cellulose membrane dropped to 15.89 MPa from 35.11 MPa. However, its elongation at break increased from 35.3% to 57.02% accordingly. © 2019 Tech Science Press.Öğe The impact of tomato fruits containing multi-walled carbon nanotube residues on human intestinal epithelial cell barrier function and intestinal microbiome composition(Royal Soc Chemistry, 2019) Lahiani, Mohamed H.; Khare, Sangeeta; Cerniglia, Carl E.; Boy, Ramiz; Ivanov, Ilia N.; Khodakovskaya, MariyaCarbon nanomaterials (CNMs) can positively regulate seed germination and enhance plant growth. However, clarification of the impact of plant organs containing absorbed CNMs on animal and human health is a critical step of risk assessment for new nano-agro-technology. In this study, we have taken a comprehensive approach to studying the effect tomato fruits derived from plants exposed to multiwalled carbon nanotubes (CNTs) have on gastrointestinal epithelial barrier integrity and their impact on the human commensal intestinal microbiota using an in vitro cell culture and batch human fecal suspension models. The effects of CNTs on selected pure cultures of Salmonella enterica Typhimurium and Lactobacillus acidophilus were also evaluated. This study demonstrated that CNT-containing fruits or the corresponding residual level of pure CNTs (0.001 mu g ml(-1)) was not sufficient to initiate a significant change in transepithelial resistance and on gene expression of the model T-84 human intestinal epithelial cells. However, at 10 mu g ml(-1) concentration CNTs were able to penetrate the cell membrane and change the gene expression profile of exposed cells. Moreover, extracts from CNT-containing fruits had minimal to no effect on human intestinal microbiota as revealed by culture-based analysis and 16S rRNA sequencing.Öğe Thermal, mechanical, and topographical evaluation of nonstoichiometric alpha-cyclodextrin/poly(epsilon-caprolactone) pseudorotaxane nucleated poly(epsilon-caprolactone) composite films(Wiley, 2018) Narayanan, Ganesh; Çaydamlı, Yavuz; Tekinalp, Halil; Matai, Ishita; Boy, Ramiz; Chung, Ching-Chang; Tonelli, Alan E.Three pseudorotaxanes (PpR) comprised of poly (epsilon-caprolactone) (PCL) and alpha-cyclodextrin (alpha-CD) with varying stoichiometric ratios were synthesized and characterized. Wide-angle X-ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host alpha-CD. The as-synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I-DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I-DSC analyses showed higher Avrami constant values (n) in the PpR-nucleated composite PCL films (n similar to 3), indicating 3-dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1-dimensions or 2-dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR-nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR-nucleated PCL composites films, demonstrating larger load bearing capabilities. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1529-1537
