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- MakaleYalnız künye2020Structural and physicochemical characterisation and antioxidant activity of an α-D-glucan produced by sourdough isolate Weissella cibaria MED17
Aburas, Hani; İspirli, Hümeyra; Taylan, Osman; Yilmaz, Mustafa Tahsin; Dertli, Enes
An exopolysaccharide (EPS) producer slimy-mucoid type colony was isolated from sourdough and identified as Weissella cibaria MED17. The 1H and 13C NMR spectra of EPS MED17 demonstrated that this EPS was a dextran type glucan ((1 → 6)-linked α-D-glucose core structure) containing (1 → 3)-linked α-D-glucose branches and proportion of (1 → 6)-linked α-D-glucose units to (1 → 3)-linked α-D-glucose units was 94.3:5.7%. The FTIR analysis also confirmed the (1 → 6)-linked α-D-glucose linkage. A high level of thermal stability was observed for glucan MED17 as no degradation up to 300 °C was observed by TGA and DSC analysis. The XRD analysis of glucan MED17 showed its semi- crystalline nature and its compact sheet-like morphology was observed by SEM analysis. Finally, antioxidant characteristics of glucan MED17 were determined by ABTS and DPPH radical scavenging activity tests that revealed a moderate antioxidant activity of glucan MED17. These findings show potential techno-functional characteristics of glucan MED17.
AtıfScopus58WoS55
İncele - MakaleYayıncıda açık erişim2020Temperature dependent current- and capacitance-voltage characteristics of W/n-Si structures with two-dimensional WS2 and three-dimensional WO3 interfaces deposited by RF sputtering technique
Baltakesmez, A.; Tekmen, S.; Güzeldir, B.
In this study, tungsten disulfide (WS2) and tungsten trioxide (WO3) thin films are deposited on n-Si by RF sputtering technique. The optical, morphological and structural characteristics of these films are investigated. The XRD patterns showed that highly crystallinity have been obtained with dominant characteristic diffraction peaks of the WS2 and WO3. The SEM images show that these films are nearly uniform and covered all surface of substrates. Furthermore, the WS2 film has two-dimensional (2D) vertical layers while the WO3 has three-dimensional (3D) structure. From the XPS spectra, it revealed that the peaks confirmed the formation of WS2 and WO3 phases. The Raman spectra presented that different vibrational modes and phases are characteristics of the WS2 and WO3 thin films. Electrical properties of W/n-Si metal-semiconductor (MS) and W/WS2/n-Si and W/WO3/n-Si metal-interfacial layer-semiconductor (MIS) diodes are investigated using current-voltage (I-V) and capacitance-voltage (C-V) characteristics at various temperatures. It was found that I-V and C-V characteristics are strongly dependent on temperature and the interfacial WS2 and WO3 layers are significant roles for the electrical properties of W/WS2/n-Si and W/WO3/n-Si devices.
AtıfScopus19WoS20İncele - MakaleYalnız künye2022Optimization of lactose derivative hetero-oligosaccharides production using whey as the acceptor molecule by an active glucansucrase
Kabli, Mohammad; İspirli, Hümeyra; Balubaid, Mohammed; Taylan, Osman; Yılmaz, Mustafa Tahsin; Dertli, Enes
Glucansucrases are capable of synthesis of distinct oligosaccharides using different acceptor molecules and in this study lactose derivative hetero-oligosaccharides were shown to be produced by an active glucansucrase in its acceptor reaction with sucrose and whey as the donor-acceptor molecules, respectively. Following the monitoring of the reaction products by TLC analysis, the effects of reaction parameters in terms of enzyme concentration, sucrose/whey ratio and reaction temperature on final oligosaccharide yields (OY) were optimized by Response Surface Methodology (RSM). Results indicated that increment of enzyme concentration and reaction temperature decreased the OY in a particular reaction time whereas the OY increased with the increment of sucrose/whey ratio in the acceptor reactions of glucansucrase E81 with whey as the acceptor molecule. A low level of glucansucrase E81 concentration was sufficient to obtain the highest OY in the tested conditions. These findings demonstrated the importance of the optimisation of the reaction parameters for the acceptor reactions of the glucansucrases.
AtıfScopus2WoS4İncele - MakaleYalnız künye2021Synthesis of silver nanoparticles prepared with a dextran-type exopolysaccharide from Weissella cibaria MED17 with antimicrobial functions
İspirli, Hümeyra; Sagdic, Osman; Dertli, Enes
Microbial polysaccharides can find distinct applications as stabilizer agents including synthesis of nanoparticles. In this study, a dextran-type exopolysaccharide (EPS) was used as the stabilizer agent for the green synthesis of silver nanoparticles (AgNPs-Dex) with antimicrobial characteristics. UV–vis spectroscopy analysis was used to test the formation of AgNPs-Dex. The uniform morphology at around 10 nm size was observed for AgNPs-Dex by TEM analysis and importantly EDX analysis demonstrated the embedment of Ag+ ions within dextran as the stabilizer agent. XRD analysis confirmed the crystalline nature of AgNPs-Dex and FTIR analysis demonstrated the interactions of dextran functional groups with silver. DSC and TGA analysis showed the alteration in the thermal stability of AgNPs-Dex compared to the stabilizer dextran. The antibacterial and antifungal activities of AgNPs-Dex were determined against food originated pathogenic bacteria and fungi and important inhibition levels were observed at 1 mg ml−1 concentration of AgNPs-Dex and this activity was observed to be concentration dependent.
AtıfScopus17WoS13İncele - MakaleYalnız künye2019Hydrogen generation via the catalytic hydrolysis of morpholine-borane: A new, efficient and cost-effective hydrogen storage medium
Can, Hasan; Metin, Önder
Herein, for the first time, we introduce the morpholine-borane complex (MB) as a new, efficient, cost-effective and commercially available chemical hydrogen storage material for mobile applications. In this regard, hydrogen production from the hydrolysis of MB catalyzed by in situ generated water-soluble polymer stabilized Ag(0) and Pd(0) nanoparticles (NPs) is reported for the first time. In situ generated PSMA-stabilized Ag(0) and Pd(0) NPs showed remarkable activity in hydrogen production from the hydrolysis of MB at room temperature, providing initial TOFs of 16.1 min−1 and 37.3 min−1, respectively. A set of kinetic studies on the catalytic hydrolysis of MB were conducted by changing the catalyst/substrate amount and temperature, and the rate law expression and activation parameters were produced by collecting the kinetic data. The apparent activation energies for the in situ generated Ag(0) and Pd(0) NPs catalyzed MB hydrolysis were calculated to be 71.4 and 32.5 kJ mol−1, respectively.
AtıfScopus20WoS20İncele