Physicochemical Properties and Digestion Resistance of Acetylated Starch Obtained from Annealed Starch

One of the examples of physical starch modifications is the retention of a starch suspension in water having a temperature slightly lower than the pasting temperature (annealing). The aim of this study was to investigate the effect of the annealing process performed at various temperatures as the first stage of starch modification. The annealed starch preparations were then esterified using acetic acid anhydride. Finally, the annealed and acetylated starch preparations were determined for their properties. The annealing of starch before acetylation triggered changes in the properties of the modified preparations. It contributed to a higher degree of starch substitution with acetic acid residues and to the increased swelling power of starch. Both these properties were also affected by the annealing temperature. The highest resistance to amylolysis was found in the case of the starch preparation annealed at 53.5 °C and acetylated. The double modification involving annealing and acetylation processes increased the onset and end pasting temperatures compared to the acetylation alone. Similar observations were made for the consistency coefficient and yield point.

Application of Blue Honeysuckle Powder Obtained by an Innovative Method of Low-Temperature Drying in Skincare Face Masks

Traditional technologies applied for obtaining plant raw materials for cosmetic production are based primarily on high-level processing, which is reflected in the qualitative composition of the resulting materials. By using low-temperature drying, it is possible to retain in the raw materials a range of valuable ingredients. In this study, blue honeysuckle powder was used as an ingredient of cosmetic face masks. The stability of the masks was evaluated. Dynamic viscosity, yield point and texture analysis of the cosmetics was performed. The color of the emulsions and the level of skin hydration after face mask application was determined. Emulsions were found to be stable. A decrease in dynamic viscosity of the emulsions as a function of increasing concentrations of the additive and under the conditions of rising rotational speed were observed. Similarly, an increase in the concentration of blue honeysuckle in the emulsions resulted in a decrease in the value of the yield point. Based on the results, it can be stated that the addition of blue honeysuckle caused a decrease in hardness of the masks, while the opposite trend was observed for adhesive force. It was found that an increase in the concentration of blue honeysuckle gave a reddish-yellow color to the samples. Corneometric assessment confirmed proper skin hydration after the application of the emulsions.

Analysis of Effects of Foreign Clay and Local Clay Additives on Viscosity of Water Based Drilling Mud

This research compared the viscosity and other allied rheological properties of formulated water based drilling mud using local clay (that is modified with cheap and available additives) and foreign clay. These additives (such as xanthum gum, high viscosity polyanionic cellulose (PAC-R), modified natural polyanionic cellulose (PAC-L), potassium hydroxide (KOH), sodium carbonate (Na2CO3), and barite) are added to enhance/control the rheological properties (such as density, viscosity, yield point and gel strength) of the drilling mud. In this work, the viscosity and other allied rheological properties of water based mud were improved by the use of locally sourced clay from Awgu in Enugu State. The local clay was beneficiated/treated with hydrochloric acid (HCl) and characterized using x-ray fluorescence (XRF) spectrometer. The results of the characterization revealed that the local clay is more of silica which is typical of a kaolinitic clay. Local clay was examined as a possible replacement for foreign bentonite by comparing the rheological properties of water based mud (WBM) with bentonite and WBM with clay. Plastic viscosities (PV) of WBM with bentonite and WBM with clay were found to be 11.7 and 12.3 cP respectively. Other allied properties such as yield point, gel strength, pH and mud weight of WBM with bentonite and WBM with clay adequately compared closely. Laboratory analyses on the effects of three process variables (such as temperature, aging time and dosage of clay/bentonite) on the viscosity of the formulated muds were investigated. The laboratory results show that the readily available additives added to the local clay improved its viscosity and other allied rheological properties for effective drilling of oil and gas well when compared with foreign bentonite.

Research on Fuzzy Plastic Constitutive Model Based on Membership Function

Soil has no obvious yield point, and the classical elastoplastic theory contradicts the uncertainty of the plastic yield point of the soil. Therefore, a fuzzy plastic Cambridge model based on the membership function was designed by combining the fuzzy mathematics with the Cambridge model. This model made the plastic membership function to correspond with the fuzzy yield function. The plastic strain at any stress state was calculated using the fuzzy Cambridge model and was compared with the indoor triaxial test results, and they were in good agreement. Therefore, it is appropriate to use fuzzy mathematics to express the unobvious soil yield property. The characteristics of soil yield in any stress state is reflected by the fuzzy plastic theory, which indicates that there is entirely no elasticity at any stress state. Moreover, the varying degrees of plasticity and the degree of plastic yield were uniquely determined by the plastic membership function. The fuzzy plastic model used the membership function change to replace the complex hardening. Additionally, the cyclic loading path was clear and appropriate for the cyclic loading and unloading calculations.

Applicability of single sample method to test strength parameters of sandstone

The single sample method allows the mechanical parameters of rocks to be obtained with very few rock samples; however, the method has not been widely used. This is mainly because the yield point of the single sample method is more difficult to control than the conventional triaxial compressive test and the effect of the different control methods on the measured data is not well understood. The single sample method obtains the strength parameters of the rock by loading a single rock sample with multiple stages of confining pressure. Multistage loading tests are divided into peak strength control and long-term strength control according to yield point control. In this study, multistage loading tests of sandstone were carried out to obtain strength parameters using long-term strength control. The results show that sandstones undergo seriously brittle damage in conventional triaxial compressive tests. Although the sandstones have been rigorously selected, they still vary considerably, and long-term strength points are more difficult to control. The error of strength parameters of sandstone obtained using the single sample method may exceed 20% compared to those obtained by conventional triaxial compressive tests. So this method must be used with caution for sandstones.

Effects of yield point and plastic anisotropy on results of elastic-plastic finite element analysis of tension leveling

Tension leveling is an important industrial process to eliminate the flatness defects and residual stresses of metal strips to provide high-quality sheet metals for subsequent sheet metal forming. The finite element (FE) method can be applied to elucidate the effects of process parameters on the quality of sheets after tension leveling for various materials. In our previous investigation, an accurate FE model considering the anisotropy and cyclic plasticity of materials has been established for the elastic-plastic FE analysis of tension leveling. In this study, we further studied the effects of the yield point and plastic anisotropy on tension leveling using the FE model established in our previous investigation. Aiming at improving the accuracy of simulation, a modified constitutive model was developed to describe the anisotropic hardening of materials under cyclic loading. The modified constitutive model was implemented into Abaqus/Standard as a user-defined material (UMAT) subroutine to simulate the development of the anisotropy in materials during tension leveling. The modified model was also applied to the FE analysis of sheet metal forming processes to demonstrate its simulation capability and accuracy.

Chemical, morphological characterizations of Ririwai biotite and determination of yield point of its weighting agent application in drilling mud

Chemical, morphological characterizations and drilling mud yield point impact of Ririwai biotite have been investigated and reported in this work. Local Ririwai biotite mined in Doguwa Local Government Area of Kano State was used as a weighting agent in drilling mud formulation. Scanning Electron Microscopy (SEM) characterization, X-ray Diffraction (XRD) and Electron Dispersion X-ray (EDX) analysis of the Ririwai biotite were carried out. Water-based drilling mud was prepared using commercial bentonite according to the API 13A Standard. Effect of gradual addition of Ririwai weighting agent; 0 – 100 wt%, on the yield point of the formulated drilling mud was studied. XRD analysis showed that the dominant mineral phase in the material was biotite. Morphological analysis carried out showed that the Ririwai biotite had a sheet-like morphology while the commercial bentonite had clumpy morphology. The estimated average particle sizes were 60 and 25 μm for the Ririwai biotite and commercial bentonite, respectively. EDX analysis showed that silica-alumina ratio of the Ririwai biotite was 9.3 while that of the commercial bentonite was 1.58. The optimum yield point of the formulated drilling mud was 2.0 lb/100 ft2 corresponding to formulation having 0 – 30 wt% weighting agent composition. The specific gravity of Ririwai biotite was determined as 2.4.