Casson

卡森
  • 文章类型: Journal Article
    罗勒种子胶的分散体具有高粘度并表现出剪切稀化行为。本研究旨在分析不同时间间隔(0、1、2和3分钟)的微波处理(MT)对罗勒种子胶分散体(0.5%,w/v)。这项研究的发现表明,罗勒种子胶分散体(未处理的分散体)的表观粘度从0.330Pa降低。S到0.068Pa。s随着剪切速率(SR)从12.2s-1增加到171.2s-1。此外,罗勒种子胶分散体的表观粘度从0.173Pa降低。s到0.100Pa。s随着MT时间从0增加到3分钟(SR=61s-1)。使用幂律(PL)成功地模拟了口香糖分散体的流变特性,宾汉姆,Herschel-Bulkley(HB),和卡森模型,PL模型是描述罗勒种子胶分散行为的最佳模型。PL模型显示出优异的性能,对于所有口香糖分散体,具有最大r值(平均r值=0.942)和最小平方误差(SSE)值(平均SSE值=5.265)和均方根误差(RMSE)值(平均RMSE值=0.624)。MT对罗勒种子胶分散体的稠度系数(k值)和流动行为指数(n值)的变化有相当大的影响(p<0.05)。罗勒种子胶分散的k值从3.149Pa显着降低。sn到1.153Pa。sn(p<0.05)随着MT时间从0增加到3分钟。随着MT时间的增加,罗勒种子胶分散的n值从0.25显着增加到0.42(p<0.05)。罗勒种子胶分散体的宾汉塑性粘度从0.029Pa显著增加。S到0.039Pa。s(p<0.05),而MT的持续时间增加。随着MT时间从0增加到3分钟,罗勒种子胶分散体的Casson屈服应力从5.010Pa显着降低到2.165Pa(p<0.05)。
    Dispersion of Basil seed gum has high viscosity and exhibits shear-thinning behavior. This study aimed to analyze the influence of microwave treatment (MT) at various time intervals (0, 1, 2, and 3 min) on the viscosity and rheological behavior of Basil seed gum dispersion (0.5%, w/v). The finding of this study revealed that the apparent viscosity of Basil seed gum dispersion (non-treated dispersion) reduced from 0.330 Pa.s to 0.068 Pa.s as the shear rate (SR) increased from 12.2 s-1 to 171.2 s-1. Additionally, the apparent viscosity of the Basil seed gum dispersion reduced from 0.173 Pa.s to 0.100 Pa.s as the MT time increased from 0 to 3 min (SR = 61 s-1). The rheological properties of gum dispersion were successfully modeled using Power law (PL), Bingham, Herschel-Bulkley (HB), and Casson models, and the PL model was the best one for describing the behavior of Basil seed gum dispersion. The PL model showed an excellent performance with the maximum r-value (mean r-value = 0.942) and the minimum sum of squared error (SSE) values (mean SSE value = 5.265) and root mean square error (RMSE) values (mean RMSE value = 0.624) for all gum dispersion. MT had a considerable effect on the changes in the consistency coefficient (k-value) and flow behavior index (n-value) of Basil seed gum dispersion (p < 0.05). The k-value of Basil seed gum dispersion decreased significantly from 3.149 Pa.sn to 1.153 Pa.sn (p < 0.05) with increasing MT time from 0 to 3 min. The n-value of Basil seed gum dispersion increased significantly from 0.25 to 0.42 (p < 0.05) as the MT time increased. The Bingham plastic viscosity of Basil seed gum dispersion increased significantly from 0.029 Pa.s to 0.039 Pa.s (p < 0.05) while the duration of MT increased. The Casson yield stress of Basil seed gum dispersion notably reduced from 5.010 Pa to 2.165 Pa (p < 0.05) with increasing MT time from 0 to 3 min.
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  • 文章类型: Journal Article
    This paper introduces a novel meshless and Lagrangian approach for simulating non-Newtonian flows, named Lagrangian Differencing Dynamics (LDD). Second-order-consistent spatial operators are used to directly discretize and solve generalized Navier-Stokes equations in a strong formulation. The solution is obtained using a split-step scheme, i.e., by decoupling the solutions of the pressure and velocity. The pressure is obtained by solving a Poisson equation, and the velocity is solved in a semi-implicit formulation. The matrix-free solution to the equations, and Lagrangian advection of mesh-free nodes allowed for a fully parallelized implementation on the CPU and GPU, which ensured an affordable computing time and large time steps. A set of four benchmarks are presented to demonstrate the robustness and accuracy of the proposed formulation. The tested two- and three-dimensional simulations used Power Law, Casson and Bingham models. An Abram slump test and a dam break test were performed using the Bingham model, yielding visual and numerical results in accordance with the experimental data. A square lid-driven cavity was tested using the Casson model, while the Power Law model was used for a skewed lid-driven cavity test. The simulation results of the lid-driven cavity tests are in good agreement with velocity profiles and stream lines of published reports. A fully implicit scheme will be introduced in future work. As the method precisely reproduces the pressure field, non-Newtonian models that strongly depend on the pressure will be validated.
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  • 文章类型: Journal Article
    背景:根据市场对更健康的放纵食品的需求,本研究旨在确定高油酸花生油含量的微胶囊黑巧克力的工业化生产的可行性。使用混合时间的变化将高油酸花生油的微胶囊添加到对照制剂中。
    结果:巧克力表现出的流变学特征是根据Casson模型(r>0.98)调整的假塑性行为和指示熔融开始(21°C)的量热行为,峰值熔融(32°C)和熔融结束(41°C);焦糖峰(183°C);和碳化峰(237°C),被认为是热稳定的。混合时间和添加到对照巧克力中的微胶囊的量没有显着影响流动极限(11.09±1.73Pa)或巧克力的物理特性:pH(6.74±0.14),最大粒径(0.019±0.001mm),水分活度(0.358±0.023)和脆性(18.61±3.74N)。然而,添加具有高油酸花生油含量的微胶囊显着提高了巧克力的白度指数,触变性和卡森塑料粘度,尽管它对混合时间没有重大影响。
    结论:获得的产品具有理想的质量和物理性能,适合工业生产。©2018化学工业学会。
    BACKGROUND: In accordance with the market demand for healthier indulgent food products, the present study aimed to determine the viability of the industrial production of dark chocolate with microcapsules of high oleic peanut oil content. Microcapsules of high oleic peanut oil were added to a control formulation using variations of mixing time.
    RESULTS: The chocolates presented a rheology characterized by a pseudoplastic behavior adjusted to the Casson model (r > 0.98) and calorimetric behavior indicating melting onset (21 °C), peak melting (32 °C) and melting end (41 °C); caramelization peak (183 °C); and carbonization peak (237 °C), being considered thermal stable. The mixing time and the amount of microcapsules added to the control chocolate did not significantly influence the flow limit (11.09 ± 1.73 Pa) or the physical characteristics of the chocolate: pH (6.74 ± 0.14), maximum particle size (0.019 ± 0.001 mm), water activity (0.358 ± 0.023) and brittleness (18.61 ± 3.74 N). However, the addition of microcapsules with a high oleic peanut oil content significantly increased the chocolate whiteness index, thixotropy and Casson\'s plastic viscosity, although it did not have a significant influence on the mixing time.
    CONCLUSIONS: The products obtained have a desirable quality and physical properties, being suitable for industrial production. © 2018 Society of Chemical Industry.
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  • 文章类型: Journal Article
    在给定剪切速率下确定剪切应力允许通过数学模型近似流动曲线并计算非牛顿流体的粘度。足月新生儿,平均动脉血压(MAP)明显低于成年人,因此血液的流变特性在维持灌注中起着重要作用。使用LS300粘度计从62个足月新生儿采集的脐带血中测量全血粘度。测量了影响全血粘度的个体参数:红细胞(RBC)聚集,血浆粘度,血细胞比容,和红细胞可变形性。新生儿全血的流量曲线通过最高质量的Ostwald方法近似,而在成年人中,通过Casson方法发现了最佳近似。血细胞比容为0.40时,Ostwald近似的新生儿全血粘度(9.84±5.12mPa·s)明显低于成年人(15.34±3.01mPa·s)。新生儿血液聚集指数(2.98±2.12)明显低于成人(14.63±3.50),而新生儿红细胞变形性较高。Ostwald测定的血浆粘度显示,新生儿(0.94±022)的指数(n)低于成人(1.01±0.12),而牛顿测定的血浆粘度(1.04±0.16mPa·s)低于成人(1.19±0.07mPa·s)。Ostwald模型最接近的新生儿血液流量曲线强调了其在生理低血压条件下所必需的重要粘性特性。
    Determination of shear stresses at given shear rates allow approximation of flow curves by mathematical models and to calculate viscosities of non-Newtonian fluids. In term neonates, the mean arterial blood pressure (MAP) is markedly below that of adults, therefore rheological properties of blood play an important role in maintaining perfusion. Whole blood viscosity was measured in umbilical cord blood taken from 62 term neonates using the LS 300 viscometer. Individual parameters that influence the viscosity of whole blood were measured: red blood cell (RBC) aggregation, plasma viscosity, hematocrit, and RBC deformability. The flow curve of whole blood of neonates was approximated by the method of Ostwald with the highest quality whereas in adults the best approximation was found by the method of Casson. With hematocrits of 0.40, the viscosity of whole blood in newborns approximated by Ostwald (9.84 ± 5.12 mPa·s) was significantly lower than that of adults (15.34 ± 3.01 mPa·s). The aggregation index of the blood of newborns was markedly lower (2.98 ± 2.12) than in adults (14.63 ± 3.50) whereas RBC deformability was higher in neonates. The viscosity of plasma determined by Ostwald revealed a lower exponent (n) in neonates (0.94 ± 022) compared to adults (1.01 ± 0.12) and the viscosity determined by Newton was lower in neonates (1.04 ± 0.16 mPa·s) than in adults (1.19 ± 0.07 mPa·s). The flow curve of neonatal blood which is best approximated by the model of Ostwald emphasizes its important viscous properties necessary for conditions with physiologically low blood pressure.
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  • 文章类型: Journal Article
    Determination of shear stresses at given shear rates with the LS 300 allows approximation of flow curves by mathematical models and to calculate viscosities of non-Newtonian fluids across the entire physiological shear range. Particular in preterm neonates, which in comparison to term neonates and adults have a substantially lower mean arterial blood pressure (MAP), rheological blood properties play a decisive role to maintain the perfusion. Whole blood viscosity was measured in umbilical cord blood taken from 34 preterm neonates using the LS 300 viscometer. In addition aggregation index, plasma viscosity, hematocrit and red blood cell (RBC) deformability was determined. The highest quality of approximation of the flow curve of whole blood was achieved by the method of Ostwald. Shear stresses of whole blood of preterm neonates were significantly lower compared to term neonates at similar shear rates (velocity range 6.16 s-1-50 s-1). With hematocrit calculated to 0.40 the related exponent (n) of the viscosity of preterm neonates (by Ostwald) showed a significant lower exponent (n) (0.71 ± 0.07) than term neonates (0.76 ± 0.06). The highest quality of approximation of the flow curve of plasma was achieved with the model of Ostwald in preterm neonates as well as in term neonates. The viscosity of plasma determined by Newton was lower for preterm neonates (0.89 ± 0.19) than for term neonates (1.04 ± 0.16). Concurrent to term neonates the whole blood of preterm neonates showed a very low aggregation index (term neonates 2.97 ± 2.10; preterm neonates 2.37 ± 1.32) and preterm neonates showed higher RBC deformability than term neonates. Because of the physiologically lower MAP and the particular viscous properties of neonatal blood special attention should be given when treating neonates with conventional blood products derived from adult donors.
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