Influence of steam jet-cooking on the rheological properties of dry and wet cationized starch solutions.

Steam jet-cooking allows for efficient dissolution of cationic starch in paper production as it operates above the boiling point of water at elevated pressures. However, the processes involved during jet-cooking and its consequences on dissolution and finally paper properties have not been fully resolved so far. As cationic starch is the most important paper additive in the wet end, any energy or material savings during dissolution will enhance the ecologic and economic performance of a paper mill. Here, we address the topic of solubilization of four different industrially relevant cationic starches processed via steam jet-cooking. We showcase that rheology is a useful tool to assess the solubility state of starches. Some starches featured liquid-like rheological behavior (loss moduli, G", greater than storage moduli, G') in linear viscoelastic tests and anti-thixotropic behavior in hysteresis loop tests. In contrast, cationic corn starches exhibited gel-like behavior (G' > G″) and negligible hysteresis directly after cooking. HYPOTHESES: To evaluate the decisive factors for complete dissolution of industrial cationic starches using jet-cooking and to correlate them to rheological properties.

Surface, rheopexy, digestive stability and toxicity of olive oil emulsions stabilized by chitin nanocrystals for vitamin D3 delivery.

Pickering emulsions are of interest in medicament transport systems. The properties of emulsions are influenced by the type of oil and the surface structure of nanoparticles-stabilizers. The process of formation of o/w emulsions of olive oil stabilized by chitin nanocrystals was investigated, their stability under the influence of physical factors, rheological characteristics, acute toxicity after oral administration, stability under the conditions of a model of the gastrointestinal tract, and their potential for oral transport of vitamin D3 were analyzed. Physically stable emulsions were obtained at a stabilizer concentration of 3.6 g/l. The addition of electrolyte leads to a substantial reduction in the average size of microdroplets. The resulting emulsions have rheopexy properties and the rheopexy index increases at 37 °C. Emulsions are classified as non-toxic when taken orally, physically stable in the upper digestive system, and capable of efficiently transporting vitamin D3 with a full release in the small intestine.

Research of rheological properties of medicinal syrup for oral use.

OBJECTIVE: The aim of the present research was to investigate the rheological properties of the medicinal syrup for oral administration with glucosamine hydrochloride and levocarnitine. PATIENTS AND METHODS: Matherials and methods: Coefficient of the dynamic flow (at shear rates of 3,49 and 10,3 s -1, as well as at shear rates of 27.2 and 149.0 s-1), mechanical stability, the index of destruction and restoration were studied. The rheological (structural-mechanical) properties of the samples were determined using a Rheolab QC rotary viscometer (AntonPaar, Austria) with coaxial cylinders CC27 / S-SN29766. The rheological parameters were studied at the temperature 20±0,5 °Ð¡. RESULTS: Results: It is established that the syrup has weakly expressed plastic viscous and thixotropic properties (the hysteresis area for the syrupis 1710.19 Pas/s). Such results characterize the system as a reopex. CONCLUSION: Conclusions: The results of the study enables classification of the research object as system with a low degree of fluidity. Such dependence is typical for systems of the Newtonian type of flow and characterizes the syrup under investigation as a weakly structured disperse system.

Rheopectic Behavior for Aqueous Solutions of Megamolecular Polysaccharide Sacran.

The rheopectic behavior of sacran aqueous solutions, a natural giant molecular polysaccharide with a molecular weight of 1.6 × 107 g/mol, was investigated. When a low shear was applied to 1.0 wt.% sacran solution, the shear viscosity increased from 7.2 to 34 Pas. The increment in the viscosity was enhanced as the shear rate decreased. The shear viscosity was independent of the time at a shear rate of 0.8 s-1; simultaneously, thixotropic behavior was observed at shear rates higher than 1.0 s-1. A crossover was observed at 0.15 wt.% for the concentration dependence of both the viscosity increase and zeta potential, which was the vicinity of the helix transition concentration or gelation concentration. It was clear that the molecular mechanism for the rheopexy was different at lower and higher regions of the crossover concentration.

Osteoarthritic synovial fluid rheology and correlations with protein concentration.

BACKGROUND: Osteoarthritis is a common, localized joint disease that causes pain, stiffness and reduced mobility. Osteoarthritis is particularly common in the knees. The effects of osteoarthritis on the rheology of synovial fluid in the knees are not fully understood and consequently require further study. OBJECTIVE: The purpose of this study is to investigate the effects of protein content on synovial fluid shear rheology. A secondary study outcome will include study of the temperature dependence of synovial fluid behaviour. METHODS: 38 osteoarthritic synovial fluid samples were studied under shear flow. Shear properties were correlated with protein concentration. Viscosupplement was used as a comparison and to verify measurement reliability. The effects of temperature were investigated at 20, 29 and 37°C. RESULTS: Shear rheological properties were found to vary widely between samples, however all samples demonstrated clear non-Newtonian shear thinning behaviour. In general viscoelastic properties were lower in osteoarthritic samples than previously studied healthy synovial fluid. A moderate correlation was observed between synovial fluid dynamic moduli at a frequency of 2.5 Hz and protein concentration. Temperature was found to affect the rheology of osteoarthritic synovial fluid and was fitted with the Arrhenius model. CONCLUSIONS: Increased protein concentration has been correlated with decreased shear rheological parameters. Temperature dependence of synovial fluid was also demonstrated and modelled for use in Part 2 of this article.