Agarose Stearate-Carbomer940 as Stabilizer and Rheology Modifier for Surfactant-Free Cosmetic Formulations

Some commonly used surfactants in cosmetic products raise concerns due to their skin-irritating effects and environmental contamination. Multifunctional, high-performance polymers are good alternatives to overcome these problems. In this study, agarose stearate (AS) with emulsifying, thickening, and gel properties was synthesized. Surfactant-free cosmetic formulations were successfully prepared from AS and carbomer940 (CBM940) mixed systems. The correlation of rheological parameter with skin feeling was determined to study the usability of the mixed systems in cosmetics. Based on rheological analysis, the surfactant-free cosmetic cream (SFC) stabilized by AS-carbomer940 showed shear-thinning behavior and strongly synergistic action. The SFC exhibited a gel-like behavior and had rheological properties similar to commercial cosmetic creams. Scanning electron microscope images proved that the AS-CBM940 network played an important role in SFC’s stability. Oil content could reinforce the elastic characteristics of the AS-CBM940 matrix. The SFCs showed a good appearance and sensation during and after rubbing into skin. The knowledge gained from this study may be useful for designing surfactant-free cosmetic cream with rheological properties that can be tailored for particular commercial cosmetic applications. They may also be useful for producing medicine products with highly viscous or gel-like textures, such as some ointments and wound dressings.

Technological Evaluation of High Fiber And Gluten-Free Breads Made With Teff (Eragrostis tef) and Associated Flours

Objectives This study aimed to evaluate technological parameters of high fiber and gluten-free breads made with teff (Eragrostis tef) and associated flours. Methods Four formulations were evaluated: T1, without teff (100% wheat flour- standard); T2, with 100% teff flour; T3, with 75% teff flour, 12.5% rice flour, and 12.5% cassava starch, and T4, with 50% teff flour, 25% rice flour, and 25% cassava starch. Hardness was verified using a texturometer TA.XT plus and a cylindrical probe with a 36 mm radius, by compressions performed on 12 slices of 2 cm thick and three replicates. The maximum force was determined in the first compression cycle and defined from the following conditions: cylindrical texturometer, maximum test speed of 4.0 mm/s; minimum test speed of 0.01 mm/s; rupture distance of 0.001 mm. The other rheological parameters such as: elasticity, cohesiveness, resilience, chewiness and gumminess were calculated. The results were evaluated through analysis of variance, followed by Tukey test, 5%, SPSS Statistics, version 21.0. Results The crust hardness in T1 was significantly (F = 33.09; p < 0.0001) higher (188g, force) than the other samples: T2 (48 g, force), T3 (40g, force) and T4 (59g, force), which were comparable to each other. Regarding crumb hardness it was observed that T1 showed significant (F = 6.20; p < 0.05) higher hardness compared to T3 (1681 g, force) and T4 (1716 g, force) and was comparable to T2 (2188g, force). The crumb elasticity was significantly (F = 27.0, p < 0.0001) higher in T2 (1.10 mm), T3 (1.10 mm) and T4 (1.10 mm) compared to T1 (1.07 mm). Cohesiveness was the unique rheological parameter that it was observed to change among the breads made with teff. The crumb resilience, chewiness and gumminess were significantly higher in T1 (F = 16.31, p < 0.05; F = 25.69, p < 0.0001; F = 29.04, p < 0.0001, respectively) than bread samples with teff. In relation to pH results it can be observed that T1 (5.8) was significantly more acid (F = 95.4, p < 0.0001), than the other samples. Conclusions Teff has shown promising behavior as a new ingredient in food formulation in order to face the worldwide increasing celiac disease. The results suggest that it is possible to develop new gluten-free bakery products using teff flour without decreasing technological quality. Funding Sources We are grateful to UFRGS, CNPq and CAPES for providing scholarship to our researchers.

Energy Consumption of Self-Compacting Concrete during Mixing and Its Impact on the Yield Stress Measured in the Ready-Mix Concrete Plant

To find the energy required during the mixing process of self-compacting concrete in a ready-mixed concrete plant and correlate the results with the yield stress of concrete. Power consumption required during the mixing of concrete is measured with a wattmeter connected to the mixing unit’s power supply. A coaxial cylinder viscometer is used to measure the yield stress of concrete. The clamp meter measures the power when the impeller rotates inside the coaxial cylinder viscometer, which is filled with concrete. When the impeller rotates in a coaxial cylinder filled with concrete, the power is measured by a clamp meter. Torque is obtained through the power relationship, which is an essential factor in determining the yield stress. The cost of a rheometer is so high that all construction industries, research institutions, and researchers cannot measure rheological parameters. Nowadays, all rheometers are automated; hence, the cost is very high. Tattersall’s approach of power requirement in mixing the concrete and calculating the yield stress reduces the complexity in determining the rheological parameter.

Rheological Parameter Analysis in Generalized Bulk Mixture Mass Flow Model

Pokhrel et al. recently developed a generalized quasi two-phase bulk mixture model for mass flow. This model has been constructed by employing full dimensional two-phase mass flow model equations. The model is a set of coupled partial differential equations which is characterized by some new mechanical and dynamical aspects of generalized bulk and shear viscosities, pressure, velocities and effective friction for the mixture where all these are evolving as functions of several dynamical variables, physical parameters, inertial and dynamical coefficients and drift factors. They formulated pressure and rate-dependent Coulumbviscoplastic rheology of the mixture mass flow to describe the model equation. Rheological behavior of the flow dynamics affects the whole dynamics of mixture mass flow. So, in this paper, the relations of mixture pressure and viscosity with respect to pressure drifts and solid volume fractions are studied to describe the rheological behavior of the generalized bulk mixture mass flow model. Moreover, the behaviour of mixture viscosities with respect to isotrophic drifts are also analyzed. We also present the simulation result for the time evolution of the drift induced full dynamical mixture pressure of the material exited from a silo gate that moves down slope along a channel.

MODELING OF HEREDITARY MATERIALS RELAXATION BY ABEL KERNEL

The present work is devoted to mathematical modeling of the process of the hereditary materials relaxation. Nonlinear integral equation of a hereditary type is proposed. The Abel kernel with two unknown parameters is adopted as the kernel of the integral equation: α∈(0,1),δ>0. Two new characteristics were introduced: 1) experimental rheological parameter of relaxation; 2) calculated (model) rheological parameter of relaxation. Using the least squares method, expressions are obtained to determine unknown parameters of the Abel kernel. A mathematical expression is given to approximate the process of the hereditary materials relaxation. Using examples of rheonomic materials different in structure (polyurethane matrix, propellant, polyoxymethylene, fiberglass), it is shown that the proposed methods allow to determine Abel kernel parameters with a high accuracy and to model the process of relaxation of rheonomic materials different in structure during a long period of time: from 102 to 1.8·106 seconds (500 hours).

Influence of Graphene Oxide on Rheological Parameters of Cement Slurries

In recent years, graphene-based nanomaterials have been increasingly and widely used in numerous industrial sectors. In the drilling industry, graphene oxide in cement slurry has significantly improved the mechanical parameters of cement composites and is a future-proof solution. However, prior to placing it in a borehole ring space, cement slurry must feature appropriate fluidity. Graphene oxide has a significant influence on rheological parameters. Therefore, it is necessary to study graphene oxide’s influence on the rheological parameters of cement slurries. Thus, this paper presents rheological models and the results of studies on rheological parameters. A basic cement slurry and a slurry with a latex addition were used. The latex admixture was applied at concentrations of 0.1%, 0.03%, and 0.06%. In total, studies were carried out for six slurries with graphene oxide and two basic slurries. The obtained results of studies on the slurries with graphene oxide were compared with the control slurry. It was found that the smallest graphene oxide concentration increased slurry value, some rheological parameter values, plastic viscosity, and the flow limit. Surprisingly, a concentration up to 0.03% was an acceptable value, since the increase in plastic viscosity was not excessively high, which allowed the use of cement slurry to seal the hole. Once this value was exceeded, the slurry caused problems at its injection to the borehole.

Texture and rheological evaluation of aerated confectionery

Confectionery industry represents a field that uses a large number of ingredients and techniques to develop unique sweet products. To produce aerated confectionery samples two different procedures were used to incorporate the ingredients in the beating vegetable or dairy cream. The objective of this research was to determine the texture parameters and the viscoelastic properties of aerated confections using compression stress-relaxation test and applying a modified Maxwell model. The highest fat content was presented by dairy cream aerated samples (20.04-20.25%), while the samples based on vegetable cream displayed a lower fat content. By applying the modified Maxwell mechanical model to the relaxation curves the equilibrium stress, σe, relaxation time, λrel, viscosity, η, and modulus of elasticity, G0, were determined. The aerated samples’ viscosity was greater than 137.96 kPa·s and less than 451.793 kPa·s; furthermore, Pearson correlation showed that density influences positively this rheological parameter (r = 0.955*). Fixing air into the product structure causes a decrease in density (0.388-0.788 g/cm3), leading to a lower equilibrium stress, a lower elasticity modulus and also a decrease of viscosity and relaxation time.

Use of Machine Learning and Infrared Spectra for Rheological Characterization and Application to the Apricot

Fast advancement of machine learning methods and constant growth of the areas of application open up new horizons for large data management and processing. Among the various types of data available for analysis, the Fourier Transform InfraRed (FTIR) spectroscopy spectra are very challenging datasets to consider. In this study, machine learning is used to analyze and predict a rheological parameter: firmness. Various statistics have been gathered including both chemistry (such as ethylene, titrable acidity or sugars) and spectra values to visualize and analyze a dataset of 731 biological samples. Two-dimensional (2D) and three-dimensional (3D) principal component analyses (PCA) are used to evaluate their ability to discriminate for one parameter: firmness. Partial least squared regression (PLSR) modeling has been carried out to predict the rheological parameter using either sixteen physicochemical parameters or only the infrared spectra. We show that (i) the spectra alone allows good discrimination of the samples based on rheology, (ii) 3D-PCA allows comprehensive and informative visualization of the data, and (iii) that the rheological parameters are predicted accurately using a regression method such as PLSR; instead of using chemical parameters which are laborious to obtain, Mid-FTIR spectra gathering all physicochemical information could be used for efficient prediction of firmness. As a conclusion, rheological and chemical parameters allow good discrimination of the samples according to their firmness. However, using only the IR spectra leads to better results. A good predictive model was built for the prediction of the firmness of the fruit, and we reached a coefficient of determination R2 value of 0.90. This method outperforms a model based on physicochemical descriptors only. Such an approach could be very helpful to technologists and farmers.

Effects of Constant and Space-Dependent Viscosity on Eyring–Powell Fluid in a Pipe: Comparison of the Perturbation and Explicit Finite Difference Methods

The present study explores the effects of constant and space-dependent viscosity on Eyring–Powell fluid inside a circular pipe. The heat transfer analysis is also considered. Using the normalised quantities, the governing equations are transformed into dimensionless form, and then the solution of the constructed nonlinear differential equations is calculated. The perturbation method is used to find the analytical expressions of velocity and temperature profiles as a function of pipe radius. The perturbation solution is validated against explicit finite difference numerical method, and errors of each case are plotted. The accuracy in velocity and temperature of finite difference method relative to the perturbation method is of order 10−2 and 10−4, respectively, in both cases of constant and space-dependent viscosity. The effects of various emerging parameters, namely, modified rheological parameter $\lambda\;\left({=0.1}\right)$, pressure gradient parameter $G\;\left({-1\leq G\leq-0.4}\right)$, rheological parameter $\xi\;\left({=0.1}\right)$ and material parameter $E\;\left({0.1\leq E\leq 1}\right)$ on temperature and velocity fields, are discussed through plots. The heights of both profiles are maximal for the case of constant model as compared to the variable one. The numerical code is also validated with a previous study of Eyring–Powell fluid in a pipe.