Copyright (c) 2010 All rights reserved. http://works.bepress.com/necati_ozkan Recent documents in Necati Ozkan en-us Wed, 23 Jun 2010 01:30:46 PDT 3600 http://works.bepress.com/necati_ozkan/37 http://works.bepress.com/necati_ozkan/37 Tue, 22 Jun 2010 00:41:15 PDT Rheological properties of the extruded pastes of various extrusion conditions were investigated by dynamic oscillation and creep-recovery tests. Temperature sweep test showed that the starch gelatinization of non-extruded pastes took place at about 67 degrees C and no gelatinization was observed for the extruded sample. Frequency sweep tests could be represented by a Power law model and the samples showed gel-like behavior since storage modulus was much larger than loss modulus. The creep-recovery data were modeled by the Burger's model. With the addition of flaxseed, the viscoelastic modulii of pastes were increased due to the formation of starch-protein-fat network, however, with further increasing the flaxseed content the viscoelastic modulii of pastes were decreased due to excessive fat which lead to network weakening. The water holding capacity results indicated that the viscoelastic properties of pastes were depended on the swelled starch-protein complex granules and the formation of new cross-links in the network. Min Wu Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/36 http://works.bepress.com/necati_ozkan/36 Tue, 22 Jun 2010 00:35:39 PDT The effects of pasting conditions, testing temperature, and shear rate on the anti-thixotropy of waxy maize starch (WMS) dispersions were investigated in this study. Activation energy and viscoelastic properties of the WMS dispersions were also determined to understand the anti-thixotropy of these dispersions. The WMS dispersions (5.0 wt.%) displayed both thixotropic and anti-thixotropic properties in loop and shear recovery tests, depending on pasting conditions and testing temperature. The standard anti-thixotropy test indicated anti-thixotropy of WMS dispersions only appeared at a certain shear rate range. When WMS dispersion was pasted more completely, the shear rate range for anti-thixotropy became wider, also the sample showed improved heat stability. The anti-thixotropy of the WMS dispersions was ascribed to re-range of the amylopectin molecules under appropriate shear rates. The normal maize starch (NMS) dispersion (5.0 wt.%) could not display anti-thixotropy here, due to a different paste structure formed by amylose in the continuous phase. Bao Wang Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/35 http://works.bepress.com/necati_ozkan/35 Tue, 22 Jun 2010 00:28:45 PDT The relaxation, creep, temperature-dependence and frequency-dependence characteristics of sweet potato roots were evaluated using a dynamic mechanical analyzer (DMA). The sweet potato was cut into rectangular to meet the testing requirements and wrapped with sealing film or aluminum foil to prevent water loss. The temperature scanning tests were carried out at 2 degrees C/min and 10 degrees C/min in the temperature range of 30-100 degrees C, and the frequency sweep tests were conducted in a range of 50-0.1 Hz. The regression results suggested that 5-element Maxwell model described relaxation behavior better for consisting of two relaxation times; the creep behavior matched the Burgers model well, and changes in creep parameters were observed after each creep cycle. The temperature scanning tests revealed that starch gelatinization was only obtained when the temperature increased at 2 degrees C/min. A resonance frequency was detected both in 3-point bending and compression deforming clamps. Qian Li Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/33 http://works.bepress.com/necati_ozkan/33 Tue, 03 Nov 2009 03:51:17 PST Creep properties of four varieties japonica cooked rice were tested using a dynamic mechanical analyzer (DMA Q800). The creep curve was described by Burgers model. The creep process of japonica cooked rice mainly consisted of retarded elastic deformation, εR and viscous flow deformation, εV, and negligible instantaneous elastic deformation, εE. The retarded elastic modulus, Ε2, relaxation time, τ, and the viscosity coefficient, η1, of the cooked rice according to the Burger model were estimated through nonlinear regression. The effect of the chemical compositions on the rheological parameters based on creep behavior of cooked rice was assessed. Correlation analysis indicated that the retarded elastic modulus, Ε2, had positive correlations with protein (r = 0.952, P = 0.048). The relaxation time, τ, had negative correlation with protein content (r = -0.909, P = 0.091). The viscosity coefficient, η1, was negatively correlated to amylose (r = -0.915, P = 0.085). The analysis between creep parameters and sensory evaluation showed that the viscosity coefficient, η1, positively correlated to stickiness and total evaluation of cooked rice. So it can be used to evaluate the eating quality of cooked rice. Su-qiang Chang Food Engineering http://works.bepress.com/necati_ozkan/32 http://works.bepress.com/necati_ozkan/32 Tue, 03 Nov 2009 01:59:33 PST BAO WANG Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/31 http://works.bepress.com/necati_ozkan/31 Tue, 03 Nov 2009 00:49:36 PST QIAN Lİ Food Engineering http://works.bepress.com/necati_ozkan/30 http://works.bepress.com/necati_ozkan/30 Tue, 03 Nov 2009 00:43:21 PST Bilsen Tural Nanoscience and Nanotechnology http://works.bepress.com/necati_ozkan/29 http://works.bepress.com/necati_ozkan/29 Tue, 03 Nov 2009 00:36:52 PST B. WANG Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/28 http://works.bepress.com/necati_ozkan/28 Tue, 03 Nov 2009 00:30:16 PST LI-MING CHE Food Engineering http://works.bepress.com/necati_ozkan/27 http://works.bepress.com/necati_ozkan/27 Wed, 17 Sep 2008 03:22:36 PDT Necati Ozkan Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/26 http://works.bepress.com/necati_ozkan/26 Mon, 26 May 2008 05:35:30 PDT The effects of natural zeolite on the rheological and workability properties of the grout mixtures were studied. Setting times of grouts were also determined as part of the experimental study. For comparison, grout mixtures were also prepared with a commercially available viscosity modifying admixture (VMA). The experimental results show that addition of natural zeolite modifies both the rheological and workability properties of grouts. For a constant superplasticizer (SP) content, an increase in the zeolite amount significantly increases the yield stress, the apparent and plastic viscosity, and reduces the fluidity and deformability. Moreover, an increase in the amount of SP causes a significant reduction in both the yield stress and plastic viscosity of the grouts. It was also observed that, grouts prepared with natural zeolite addition have a pseudo-plastic behavior, and shear-thinning behavior increases with an increase in the zeolite amount. Therefore, it has been shown that using natural zeolite as a VMA it is possible to obtain grouts that have satisfactory rheological properties, especially if natural zeolite is used in combination with a superplasticizer. Mustafa Sahmaran Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/25 http://works.bepress.com/necati_ozkan/25 Thu, 13 Mar 2008 03:09:37 PDT In order to produce magnetic microparticles (agglomerates), magnetite (Fe3O4) particles were synthesized using co-precipitation of FeSO4.7H2O and FeCl3.6H2O with the presence of poly(methacrylic acid) (PMAA) in aqueous solution.. Transmission electron microscopy (TEM), X-ray diffraction, and vibrating sample magnetometry (VSM) methods were used to characterize the PMAA coated superparamagnetic agglomerates. The influences of various processing parameters such as, the process temperature, PMAA content, and the addition of surfactant on the agglomerate size and size distribution of produced magnetic microparticles were investigated. The particle size and size distribution characteristics, (the volume weighted mean size (D[4,3], surface weighted mean size D[3,2], the geometric standard deviation, and span value) of the magnetic agglomerates were determined using the laser diffraction technique. The PMAA coated magnetic agglomerates with surface weighted mean sizes ranging from 1.5 to 3 microns were produced successfully. Bilsen Tural Nanoscience and Nanotechnology http://works.bepress.com/necati_ozkan/24 http://works.bepress.com/necati_ozkan/24 Tue, 16 Oct 2007 03:50:12 PDT Zhen Shan Zhang Food Engineering http://works.bepress.com/necati_ozkan/23 http://works.bepress.com/necati_ozkan/23 Tue, 18 Sep 2007 01:17:22 PDT Three major aspects of food powder are described and discussed. Stickiness is one issue that can cause production and product handling difficulties. Stickiness has been interpreted in a number of ways and thus measured differently. Functionality of the primary (single) particles or agglomerated powders is of practical interest to the consumers. The desired quality will have to be matched or exceeded by the powder manufacturers. Finally, microstructure provides a key linkage between the production and the functionality. Its formation has impacts on both the stickiness and functionality. Xiao Dong Chen Food Engineering http://works.bepress.com/necati_ozkan/22 http://works.bepress.com/necati_ozkan/22 Mon, 18 Jun 2007 00:51:46 PDT Ke Cheng Chen Rheological Characterization of Materials http://works.bepress.com/necati_ozkan/21 http://works.bepress.com/necati_ozkan/21 Mon, 29 Jan 2007 01:08:17 PST P. A. Freeman High Tc Ceramic Superconductors http://works.bepress.com/necati_ozkan/20 http://works.bepress.com/necati_ozkan/20 Mon, 29 Jan 2007 00:48:53 PST NECATİ ÖZKAN High Tc Ceramic Superconductors http://works.bepress.com/necati_ozkan/19 http://works.bepress.com/necati_ozkan/19 Mon, 29 Jan 2007 00:42:45 PST The preparation of thin (ca. 200 mm) Ce0.9Gd0.1O1.95 planar electrolytes using the tape rolling technique is described. The processing and formation of these electrolytes involved several steps: (i) the production of a processable ceramic paste, (ii) rolling and cutting, (iii) binder burnout, and (iv) sintering. The rheology of these ceramic pastes is characterized by a hardness indentation test. The material parameters which may be ob-tained from the hardness indentation test such as the hardness (plastic flow stress), elastic modulus, and plasticity index are provided. The rheology, as characterized by the hardness method, of the pastes are shown to be influenced by the nature and extent of processing aids and also the mixing and milling times. Further, it is shown that by using a paste formulation with appropriate rheological properties, it is possible to produce uniform thin green tapes using a twin roll mill. The binder burnout characteristics of the ceramic pastes were studied by using a specially constructed thermal gravimetric apparatus. It is shown that the heating rate and the ambient atmosphere have strong influences upon the binder burnout kinetics of these green tapes. Finally, it is shown that sintered Ce0.9Gd0.1O1.95 electrolytes, with a near theoretical density and with a uniform microstructure as well as a chosen near net shape, may be prepared from the corresponding tape rolled greens. Necati Ozkan Ceramics http://works.bepress.com/necati_ozkan/18 http://works.bepress.com/necati_ozkan/18 Sun, 28 Jan 2007 14:27:57 PST The dissolution kinetics and mechanical properties of whey protein concentrate (WPC) gels were investigated as part of a general study on cleaning mechanisms of milk fouling. The dissolution results showed that the WPC gel is a suitable model material... Hong Xin Food Engineering http://works.bepress.com/necati_ozkan/17 http://works.bepress.com/necati_ozkan/17 Sun, 28 Jan 2007 14:18:46 PST ABSTRACT: A depth sensing indentation hardness test with an associated analysis is described as a convenient and simple technique for characterizing mechanical properties of food materials, such as hardness (H), elastic modulus (E), and an elasticity index... Necati Ozkan Rheological Characterization of Materials