Hemiselüloz ekstraksiyon ve ekstrüzyon parametrelerinin farklı lignoselülozik biyokütlelerden elde edilen hemiselüloz temelli polimerik malzemelerin özelliklerine etkisi.

There is growing interest worldwide in utilization of renewable sources for fuels, materials and chemicals due to depletion of fossil sources and the environmental damages of synthetic products. Lignocellulosic biomass is the most promising material to become a substitute for fossil sources because of its abundancy in nature, low price and utilization area which does not compete with the food. Biodegradable films can be produced from hemicellulosic part of biomass and their main use can be especially food packaging due to their low oxygen permeability. In this study, hemicellulose is extracted from corn cobs and cotton stalk by alkaline extraction and extrusion process was utilized for the production of hemicellulose based materials. Within the context of this study, alkali extraction (particle size of the corncobs, extraction time, alkaline concentration and boron compound addition) and extrusion (extrusion temperature and screw speed) parameters were investigated and compared in terms of films mechanical, thermal and morphological properties. The best conditions in the range tested, were found as 1.19 - 0.6 mm particle size corn cobs, 1 h of extraction time with 15% KOH and no boron compound addition. The tensile strength of about 80 MPa and the elongation at break of 48% were obtained for the corn cob based extruded strips. The tensile strength of about 91 MPa was obtained for the solvent casted cotton stalk films. These mechanical properties suggest that the solvent casting was a suitable method for the cotton stalk hemicellulose while the extrusion was more convenient method for the corn cob hemicellulose.M.S. - Master of Scienc

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

HEMİSELÜLOZUN EKSTRÜZYON ÖNCESİ NEM MİKTARININ HEMİSELÜLOZ TEMELLİ FİLMLERİN MEKANİK ÖZELLİKLERİNE ETKİS

HEMİSELÜLOZUN EKSTRÜZYON ÖNCESİ NEM MİKTARININ HEMİSELÜLOZ TEMELLİ FİLMLERİN MEKANİK ÖZELLİKLERİNE ETKİSİ

HEMİSELÜLOZUN EKSTRÜZYON ÖNCESİ NEM MİKTARININ HEMİSELÜLOZ TEMELLİ FİLMLERİN MEKANİK ÖZELLİKLERİNE ETKİS

A ratiometric and switchable fluorescent sensor based on calix[4]arene-HBT with a large Stokes shift for the real-time detecting Zn2+ and Cu2+ in living cells

Though Zn2+ and Cu2+ have several critical roles in biological and environmental media, they may also induce a variety of detrimental effects. Hence, the monitoring of trace amounts of Zn2+ and Cu2+ in biological systems and ecological environment is of great significance due to their harmful impacts on living organisms. To serve this purpose, we designed and constructed a simple benzothiazole-calixarene (C-HBT)-based ratiometric and fluorometric probe with a large Stokes shift of 206 nm to recognize Zn2+ and Cu2+. The detection levels of C-HBT for Zn2+/Cu2+were as low as 35.1 nM and 66.7nM,and high binding constant values were obtained within an extremely short time (10.0 s),respectively. Furthermore, with the assistance of inexpensive, viable and straightforward Smartphone and cotton swab applications, C-HBT was successfully applied for the on-site and naked eye recognition of Zn2+/Cu2+.Finally, the remarkable performance of C-HBT towards Zn2+/Cu2+with negligible cytotoxicity was achieved in living cells

New Fe3+ specific "turn-on" fluorescent sensor based on H-2 saldien-substituted phenanthroimidazole: Fabrication and practical applications

WOS:000681039600099Precise recognition of Fe3+ in a biological system and ecological environment is of great importance. Therefore, a new phenanthroimidazole based chemosensor SP (H-2 saldien-substituted phenanthroimidazole) was designed, fabricated and evaluated as a facile fluorogenic "OFF-ON" type chemosensor toward Fe3+ in aqueous solution. The SP could sensitively and selectively recognize Fe3+ with a limit of detection of 0.36 mu M. The sensing mechanism for the SP-Fe3+ system was successfully proven on FT-IR spectroscopy, TOF-MS and the calculations of DFT (density functional theory). It is found that the SP could be basically recycled through treating with EDTA. Moreover, Fe3+ can be visualized by prepared SP in the test kit and low-cost smartphone sensor applications. Evidently, the experiments manifested that the prepared SP was capable of recognizing of Fe3+ in aqueous media. (C) 2021 Elsevier B.V. All rights reserved

New (NHC)Pd(II)(PPh3) complexes: synthesis, characterization, crystal structure and its application on Sonogashira and Mizoroki-Heck cross-coupling reactions

In this study, new six Pd-based complexes containing mixture N-heterocyclic carbene (NHC) and triphenylphosphine-(PPh3) ligands were synthesized from the reaction of the (NHC)PdI2(pyridine) with-PPh3. The new (NHC)PdI2(PPh3) complexes were characterized using FTIR, H-1-NMR, C-13-NMR, and P-31-NMR spectroscopy and elemental analyses techniques. These spectra are consistent with the proposed formula. Molecular and crystal structure of two complexes was obtained using single-crystal X-ray diffraction method. Based on the crystal results, a cis geometry was assigned to all the complexes. These new complexes have been examined as the catalyst in the Sonogashira cross-coupling reaction. The catalytic conversions of the complexes were obtained between 71 and 99% from the reaction of phenylacetylene and aryl bromides. Also, these new complexes have been examined as the catalyst in the Mizoroki-Heck cross-coupling reaction. The catalytic conversions of the complexes were obtained between 80 and 100% from the reaction of styrene and aryl bromides

2-hydroxyethyl-substituted (NHC)PdI2(pyridine) (Pd-PEPPSI) Complexes: Synthesis, Characterization and the Catalytic Activity in the Sonogashira Cross-coupling Reaction

Here, new series of the 2-hydroxyethyl-substituted (NHC)PdI2(pyridine) (Pd-PEPPSI) complexes have been synthesized. These complexes have been prepared from the 2-hydroxyethyl-substituted N-heterocyclic carbene (NHC) precursors, palladium chloride and pyridine. The synthesized Pd-PEPPSI complexes have been characterized by using H-1 NMR, C-13 NMR, FTIR spectroscopy and elemental analysis techniques. The catalytic activity of the 2-hydroxyethyl-substituted Pd-PEPPSI complexes has been examined in the Sonogashira cross-coupling reaction by using phenylacetylene and aryl bromide. The Pd-PEPPSI complexes have demonstrated great activity in the Sonogashira cross-coupling reaction. The molecular and crystal structures of the three of the Pd-PEPPSI complexes were determined by single-crystal X-ray diffraction method. X-ray studies show that all the molecular structures adopt slightly distorted square-planar geometry around the palladium (II) center

Synthesis, crystal structures, spectral investigations, conformational analysis and DFT studies of N- heterocyclic carbene precursors

Three new 2-hydroxyethyl substituted N-heterocyclic carbene (NHC) precursors were synthesized in this study. These NHC precursors were prepared from 1-(alkyl/aryl)benzimidazole and alkyl halides. Their structural characterizations were performed by elemental analysis, H-1 NMR, C-13 NMR, FT-IR and UV-Vis spectroscopy and single-crystal X-ray diffraction. The spectral features were also characterized by Density Functional Theory (DFT) at B3LYP/Lanl2dz//6-31G++(d,p) basis set. Two most stable conformers belonging to the compounds were found by potential energy surface (PES) scan, and the theoretical ground-state geometries were investigated. Among these conformers, the geometry of the conformer-I for all compounds matches almost well with the experimental results. H-1 and C-13 NMR chemical shifts were calculated with GLAD approach and compared to the observed ones. Detailed vibrational assignments of the wavenumbers of the conformers were carried out based on the potential energy distribution (PED). Natural bond orbital (NBO) analysis was used to analyze the stability of the molecules arising from hyperconjugative interactions and charge delocalization. The HOMO-LUMO energy gap of the stable conformers was calculated for comparing their chemical reactivity behavior. Molecular electrostatic potential (MEP) diagrams were used to get information about ?the size, shape, charge density distribution and site of chemical reactivity of each stable conformer. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were also carried out to obtain an insight into the behavior of the interactions in the compounds. (C) 2019 Elsevier B.V. All rights reserved