Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 18Citation - Scopus: 17Modifying Pickering Polymerized High Internal Phase Emulsion Morphology by Adjusting Particle Hydrophilicity(Elsevier, 2024) Durgut, Enes; Zhou, Muchu; Dikici, Betuel Aldemir; Foudazi, Reza; Claeyssens, FrederikThis study investigates the use of submicron polymeric particles with varying crosslinking densities as the sole stabilizer for producing Polymerized High Internal Phase Emulsions (PolyHIPE). We establish a direct correlation between the crosslinking density and the hydrophilicity of the polymer particles. The hydrophilicity of these particles significantly influences the morphology and rheology of HIPEs. These differences manifest as various morphological variations in the resulting PolyHIPE templates. It was discovered that by increasing the crosslinker weight percentage in the particles from 0 % to 100 %, PolyHIPEs with semi-open, open, and closed porous structures can be obtained. Furthermore, non-crosslinked particles were observed to dissolve in the continuous phase, acting as macromolecular surfactants that generate small pores akin to surfactant-stabilized structures in PolyHIPE. These findings offer fresh insights into the relationship between particle localization at the interface, HIPE rheology, and the formation of pore throats in Pickering PolyHIPEs, leading to the creation of either closed or open porous networks. Additionally, interfacial rheological results demonstrate that particles synthesized with varying monomer-to-crosslinker ratios exhibit different interfacial elasticities, which are linked to PolyHIPE morphology.Article Citation - WoS: 21Citation - Scopus: 25Milk Fat Substitution by Microparticulated Protein in Reduced-Fat Cheese Emulsion: the Effects on Stability, Microstructure, Rheological and Sensory Properties(Korean Society for Food Science of Animal Resources, 2019) Urgu, Müge; Türk, Aylin; Ünlütürk, Sevcan; Kaymak Ertekin, Figen; Koca, NurcanFat reduction in the formulation of cheese emulsion causes problems in its flowability and functional characteristics during spray-dried cheese powder production. In order to eliminate these problems, the potential of using microparticulated whey protein (MWP) in cheese emulsions was examined in this study. Reduced-fat whitebrined cheese emulsions (RF) with different dry-matters (DM) (15%, 20%, and 25% excluding emulsifying salt) were produced using various MWP concentrations (0%-20% based on cheese DM of emulsion). Their key characteristics were compared to full-fat cheese emulsion (FF). MWP addition had no influence on prevention of the phase separation observed in the instable group (RF 15). The most notable effect of using MWP was a reduction in apparent viscosity of RF which significantly increased by fat reduction. Moreover, increasing the amount of MWP led to a decrease in the values of consistency index and an increase in the values of flow behavior index. On the other hand, using high amounts of MWP made the emulsion more liquid-like compared to full-fat counterpart. MWP utilization also resulted in similar lightness and yellowness parameters in RF as their full-fat counterparts. MWP in RF increased glossiness and flowability scores, while decreased mouth coating scores in sensory analyses. Fat reduction caused a more compact network, while a porous structure similar to FF was observed with MWP addition to RF. In conclusion, MWP showed a good potential for formulation of reducedfat cheese emulsions with rheological and sensorial characteristics suitable to be used as the feeding liquid in the spray drying process.Article Citation - WoS: 123Citation - Scopus: 140Effect of Various Supplementary Cementitious Materials on Rheological Properties of Self-Consolidating Concrete(Elsevier Ltd., 2015) Saleh Ahari, Reza; Erdem, Tahir Kemal; Ramyar, KambizIn design of self-consolidating concrete (SCC) for a given application, the mixture's rheological parameters should be adjusted to achieve a given profile of yield stress and plastic viscosity. Supplementary cementitious materials (SCM) can be useful for this adjustment in addition to their other advantages. In this study, the rheological properties of 57 SCC mixtures with various SCM were investigated for a constant slump flow value. For this aim, various amounts of silica fume (SF), metakaolin (MK), Class F fly ash (FAF), Class C fly ash (FAC) and granulated blast-furnace slag (BFS) were utilized in binary, ternary, and quaternary cementitious blends in three water/binder ratios. Results showed that SF and BFS decreased plastic viscosity and V-funnel time values in comparison with mixtures containing only Portland cement (PC). However the opposite tendency was observed when MK, FAC and FAF were incorporated with PC. Substitution of PC with SF, MK and FAC increased high range water reducer (HRWR) demand in the SCC mixtures having constant slump flow. Use of SCM in SCC mixtures increased yield stress values. Good correlations were established between plastic viscosity and V-funnel flow time values for all w/b ratios.Article Citation - WoS: 13Citation - Scopus: 21An innovative approach: Cow/oat milk based kefir(Hrvatska Mljekarska Udruga, 2015) Dinkçi, Nayil; Kesenkaş, Harun; Korel, Figen; Kınık, ÖzerThe aim of this study was to evaluate the potential of kefir production using cow-oat milk mixture. Therefore kefir samples with 20, 40 and 60 % of oat milk were produced. The effect of oat-milk ratio on physicochemical, rheological, microbiological and sensory characteristics of the kefir samples was studied during 21 days storage at refrigerated conditions. Increasing oat milk concentration affected the whey-off and apparent viscosity by higher whey off and lower viscosity results. Also the proteolytic activity of the samples was decreased by raising the oat milk concentrations. Increase of the oat milk concentration leaded to a decrease of pH of the samples. Statistical analysis showed that the lactococci and lactobacilli viable cell counts differed among the samples while the highest count was detected in sample with the highest amount of oat milk. The control sample (without oat milk) had higher yeast count during the storage period. The final product with 20 % of oat-milk and without addition of flavour was found to be the most acceptable by the sensory panellists. The results indicate the possibility for a new cow/oat milk based kefir.Article Citation - WoS: 10Citation - Scopus: 10Determination of the Particle Interactions, Rheology and the Surface Roughness Relationship for Dental Restorative Ceramics(Elsevier Ltd., 2009) Kes, Mürşide; Polat, Hürriyet; Keleşoğlu, Serkan; Polat, Mehmet; Aksoy, GökhanThe effect of inter-particle interactions on the slurry properties and the final surface roughness of the dental ceramic restoratives was investigated. A commercial dental ceramic powder, IPS Empress 2 veneer, was used as the raw material. The magnitudes of the particle-particle interactions were computed by the DLVO theory for the ceramic slurries of different electrolyte solutions (0.1 M, 0.25 M, 0.5 M, 0.75 M, 1 M NaCl and CaCl2). As expected, the energies of particle-particle interactions were influenced significantly by the presence of electrolytes. These computations demonstrated that addition of electrolytes leads to a progressive depression of the repulsive double layer forces. The absence of these forces should inevitably lead to agglomeration caused by the ever-present van der Waals forces. The rheological measurements carried out using the slurries with same solution properties supported the findings of the DLVO computations. It was found that dental ceramic slurries showed a Newtonian behavior in the absence of electrolytes, which is indicative of little or no agglomeration in the slurry. On the other hand, the same slurries displayed a non-Newtonian, shear thinning behavior in the presence of electrolytes which can be attributed to agglomeration or gelation. Roughness of the ceramic surfaces produced from these slurries was studied by SEM analysis and profilometer measurements. Contact angle studies were also carried out on the same surfaces. It was observed that the surface became rougher initially with electrolyte addition to a maximum, most probably due to formation of isolated agglomerates due to a reduction of the repulsive double layer forces. After reaching a maximum, surface roughness decreased to a much lower value with further increase in electrolyte concentration. This was most probably caused by the formation of a relatively homogeneous, gel-like structure within the extensively agglomerated slurry due to a complete collapse of the double layer.Article Citation - WoS: 33Citation - Scopus: 37Relationship Between Morphology, Rheology and Polygalacturonase Production by Aspergillus Sojae Atcc 20235 in Submerged Cultures(Elsevier Ltd., 2006) Göğüş, Nihan; Tarı, Canan; Öncü, Şelale; Ünlütürk, Sevcan; Tokatlı, FigenA full factorial statistical design, with the factors of, two taxonomically different strains, seven types of seed culture formulations (slants) and two types of fermentation media were used to investigate the effect of these parameters on the morphology and polygalacturonase production. The rheology of the final fermentation medium was analyzed and appropriate mathematical model was applied to calculate suspension viscosity. It was found that most fermentation broths showed non-Newtonian flow behavior. According to statistical analysis, factors of strain types and fermentation media and the interaction between them were found significant on the enzyme activity. The effect of seed culture formulations (slants) were found insignificant at the significance level of 1%. Interaction of slants with strain types and fermentation media were also found insignificant. Considering the morphology of the final culture, Aspergillus sojae with the desired pellet morphology in a complex media, inoculated with a seed culture prepared from molasses resulted in maximum polygalacturonase enzyme activity (0.2 U/ml) and lowest suspension viscosity with a broth rheology close to Newtonian flow behavior.Article Citation - WoS: 91Citation - Scopus: 113Rheological and Dynamic-Mechanical Behavior of Carbon Nanotube/Vinyl Ester-Polyester Suspensions and Their Nanocomposites(Elsevier Ltd., 2007) Seyhan, Abdullah Tuğrul; Gojny, F. H.; Tanoğlu, Metin; Schulte, K.Rheological properties of vinyl ester-polyester resin suspensions containing various amounts (0.05, 0.1 and 0.3 wt.%) of multi walled carbon nanotubes (MWCNT) with and without amine functional groups (-NH2) were investigated by utilization of oscillatory rheometer with parallel plate geometry. Dispersion of corresponding carbon nanotubes within the resin blend was accomplished employing high shear mixing technique (3-roll milling). Based on the dynamic viscoelastic measurements, it was observed that at 0.3 wt.% of CNT loadings, storage modulus (G′) values of suspensions containing MWCNTs and MWCNT-NH2 exhibited frequency-independent pseudo solid like behavior especially at lower frequencies. Moreover, the loss modulus (G″) values of the resin suspensions with respect to frequency were observed to increase with an increase in contents of CNTs within the resin blend. In addition, steady shear viscosity measurements implied that at each given loading rate, the resin suspensions demonstrated shear thinning behavior regardless of amine functional groups, while the neat resin blend was almost the Newtonian fluid. Furthermore, dynamic mechanical behavior of the nanocomposites achieved by polymerizing the resin blend suspensions with MWCNTs and MWCNT-NH2 was investigated through dynamic mechanical thermal analyzer (DMTA). It was revealed that storage modulus (E′) and the loss modulus (E″) values of the resulting nanocomposites increased with regard to carbon nanotubes incorporated into the resin blend. In addition, at each given loading rate, nanocomposites containing MWCNT-NH2 possessed larger loss and storage modulus values as well as higher glass transition temperatures (Tg) as compared to those with MWCNTs. These findings were attributed to evidences for contribution of amine functional groups to chemical interactions at the interface between CNTs and the resin blend matrix. Transmission electron microscopy (TEM) studies performed on the cured resin samples approved that the dispersion state of carbon nanotubes with and without amine functional groups within the matrix resin blend was adequate. This implies that 3-roll milling process described herein is very appropriate technique for blending of carbon nanotubes with a liquid thermoset resin to manufacture nanocomposites with enhanced final properties.