Effect of Silica Fume on the Rheological Properties of Cement Paste with Ultra-Low Water Binder Ratio

The effect of silica fume on the rheological properties of a cement–silica fume–high range water reducer–water mixture with ultra-low water binder ratio (CSHWM) was studied. The results indicate that the W/B ratio and silica fume content have different effects on the rheological parameters, including the yield stress, plastic viscosity, and hysteresis loop area. The shear-thickening influence of CSHWM decreased with the increased silica fume content. When the silica fume content increased from 0% to 35%, the mixture with W/B ratio of 0.19 and 0.23 changed from a dilatant fluid to a Newtonian fluid, and then to a pseudoplastic fluid. When the silica fume content was less than 15%, the yield stress was close to 0. With the increase of silica fume content, the yield stress increased rapidly. The plastic viscosity and hysteresis loop area decreased slightly with the addition of a small amount of silica fume, but increased significantly with the continuous increase of silica fume. Compared with the Bingham and modified Bingham models, the Herschel–Buckley model is more applicable for this CSHWM.

INFLUENCE OF OLIVE OIL ON THE RHEOLOGICAL CHARACTERISTICS OF MAYONNAISE

Rheological properties are an important parameter for the quality of mayonnaise. This article in-vestigated the effect of adding olive oil on the rheological properties and color change of mayon-naise. The influence of the storage time of mayonnaise in the refrigerator on the change in rheo-logical properties was also investigated. Mayonnaise was prepared on a laboratory rotary disperser of the Turrex type with a rotor / stator system with a rotor speed range (10000-30000 rpm) at room temperature. Mayonnaise contains 75% oil with varying proportions of sunflower oil and ol-ive oil. Rheological measurements were carried out on a Brookfield rotary viscometer with con-centric cylinders at temperatures of 10 ° C and 25 ° C. Based on the data obtained, the consistency coefficient of the rheological parameters, the flow index and the apparent viscosity were calculat-ed. The color of the test samples of mayonnaise was measured using a three-color colorimeter. All mayonnaise samples exhibit non-Newtonian pseudoplastic flow with a defined thixotropic loop area. Research results have shown that the addition of olive oil affects the rheological properties and color of mayonnaise. The addition of olive oil to the oil phase of mayonnaise reduces shear stress, apparent viscosity, consistency factor and color change at 25 ° C and 10 ° C. When storing mayonnaise in the refrigerator for 15 days, the rheological parameters change. Sunflower oil may-onnaise (75%) has the highest value (L), which means it is measured instrumentally as the bright-est.

Tailoring Local Hysteresis in Small Clusters of Dipolar Interacting Magnetic Nanoparticles

Using first-principle calculations and kinetic Monte Carlo simulation, we study the local and averaged hysteresis in tiny clusters of [Formula: see text] magnetic nanoparticles (MNPs) or [Formula: see text]-mers. We also analyze the variation of local dipolar field acting on the constituent nanoparticles as a function of the external magnetic field. The dipolar interaction is found to promote chain-like arrangement in such a cluster. Irrespective of cluster size, the local hysteresis response depends strongly on the corresponding dipolar field acting on a nanoparticle. In a small [Formula: see text]-mer, there is a wide variation in local hysteresis as a function of nanoparticle position. On the other hand, the local hysteresis is more uniform for larger [Formula: see text]-mer, except for MNPs at the boundary. In the case of superparamagnetic nanoparticle and weak dipolar interaction, the local hysteresis loop area [Formula: see text] is minimal and depends weakly on the [Formula: see text]-mer size. While for ferromagnetic counterpart, [Formula: see text] is considerably large even for weakly interacting MNPs. The value of [Formula: see text] is found to be directly proportional to the dipolar field acting on the nanoparticle. The dipolar interaction and [Formula: see text]-mer size also enhance the coercivity and remanence. There is always an increase in [Formula: see text] with cluster size and dipolar interaction strength. Similarly, the averaged hysteresis loop area [Formula: see text] also depends strongly on the [Formula: see text]-mer size, particle size and dipolar interaction strength. [Formula: see text] and [Formula: see text] always increase with [Formula: see text]-mer size and dipolar interaction strength. Interestingly, the value of [Formula: see text] saturates for [Formula: see text] and considerable dipolar interaction irrespective of particle size. We believe that this work would help understand the intricate role of dipolar interaction on hysteresis and the organizational structure of MNPs and their usage in drug delivery and hyperthermia applications.

Effect of Esterification Conditions on the Physicochemical Properties of Phosphorylated Potato Starch

The aim of this study was to evaluate the effect of the temperature (15 or 45 °C) and the duration (15–120 min) of the modification process on the selected physicochemical, thermal, and rheological properties of phosphorylated potato starch. The modified starches contained 93.6–98.2 mg P/100 g (dry weight basis, d.w.b.). Phosphorylation caused color changes with a total color difference between the starches below 0.55, but these changes were less than those that were recognizable by the human eye. The thermal analysis showed two opposite processes appearing during the modification: the loosening of the structure (dominant among starches obtained at 15 °C) and the strengthening of the structure (dominant among starches obtained at 45 °C). The higher phosphorylation temperature reduced native starch recovery from 140% to 87–116% and increased the hysteresis loop area from −169 to 1040. All of the pastes made from the modified starches showed a weaker tendency for retrogradation (during 21 days of storage) than native starches. The results of the regression analysis conducted between the properties of the starch pastes obtained at 45 °C indicated that the modification time appeared to be a better indicator of the rate of modification progress than the phosphorus content. The PCA (principal component analysis) results made it possible to distinguish starch phosphates obtained at 15 °C from those obtained at 45 °C and those from natural starch.

Investigation of excipients influence on rheological behaviour of hydrogels with dimethindene maleate and dexpanthenol: conditions of controlled shear rate

Every year, the number of cases of hypersensitivity to insect bites increases. Thus, particular attention needs to be paid to the treatment of insect allergy in children, as scratching the bites can complicate the healing process and lead to infection. Therefore, a topical issue for modern medicine and pharmacy is the development of a gel of combined anti-allergic, reparative and anti-inflammatory action for the treatment of local manifestations of allergic skin reactions. Rheological studies are one of the stages of pharmaceutical development of soft dosage forms. In this study, we perform rheological studies of hydrogels containing 0.1% dimethindene maleate and 3.0% dexpanthenol made on different carriers of dispersed structures: Carbopol™ Polymers carbomer Ultrez 10 NF, Hydroxypropyl methylcellulose (HPMC) of brand Metolose SR-90SH-100000SR, Ziboxan F200 xanthan gum. The rheological studies were undertaken using a rheometer in controlled shear rate mode CSR. Basic structural and mechanical indices of the dispersed systems were determined. These included: yield stress, structural viscosity, viscosity at infinite shear rate, the hysteresis loop area. Moreover, dynamic liquefaction coefficients have been calculated. Based on the rheological studies of hydrogels containing 0.1% dimethindene maleate and 3.0% dexpanthenol prepared with various carriers, the use of 1.8% and 2.0% HPMC hydrogels, 2.0% and 2.5% xanthan gum hydrogels, 0.5% and 0.75% carbomer gels is recommended for further biopharmaceutical studies. The application of one of these formulations as the final composition, provides adhesion and will not complicate the scaling-up of the process.

Improving the texture and rheology of set and stirred kombucha fermented milk beverages by addition of transglutaminase

The possibilities of manufacturing fermented milk beverages by applying kombucha inoculum concentrated by evaporation and with addition of transglutaminase have been investigated. The main aims of this study were to investigate influence of concentrated kombucha inoculum and the addition of transglutaminase (TG) on textural, rheological and sensory properties of set and stirred fermented milk beverages. The results showed that the addition of transglutaminase had a great influence on textural characteristics and rheological properties of kombucha fermented milk beverages. Firmness and consistency of kombucha fermented milk products were significantly increased with the incorporation of TG compared to the control sample. Set samples with TG addition had approximately 90 % higher hysteresis loop area compared to stirred samples, while hysteresis loop area of stirred samples without TG was 60 % lower compared to set samples. The enzymatic treatment of milk with TG improved texture, rheology and sensorial characteristics of set and stirred fermented milk beverages obtained by concentrated kombucha inoculum.

Effect of Loading and Heating History on Deformation of LaCoO3

The aim of this work was to study cyclic stress–strain deformation behavior of LaCoO3 as a function of loading and heating history. The ferroelastic hysteretic deformation of LaCoO3 at different stresses and temperatures was characterized using effective Young’s modulus, hysteresis loop area and creep strain shift parameters. The deformation behavior of LaCoO3 was not significantly affected by the previous loading and heating history when tested at constant temperature. The high temperature strength and Young’s modulus of LaCoO3 were higher compared to at room temperature. A creep strain shift parameter was introduced to characterize creep strain in LaCoO3 for the first time.

A 6-month inhalation toxicology study in Apoe−/− mice demonstrates substantially lower effects of e-vapor aerosol compared with cigarette smoke in the respiratory tract

Cigarette smoking is the major cause of chronic obstructive pulmonary disease. Considerable attention has been paid to the reduced harm potential of nicotine-containing inhalable products such as electronic cigarettes (e-cigarettes). We investigated the effects of mainstream cigarette smoke (CS) and e-vapor aerosols (containing nicotine and flavor) generated by a capillary aerosol generator on emphysematous changes, lung function, and molecular alterations in the respiratory system of female Apoe−/− mice. Mice were exposed daily (3 h/day, 5 days/week) for 6 months to aerosols from three different e-vapor formulations—(1) carrier (propylene glycol and vegetable glycerol), (2) base (carrier and nicotine), or (3) test (base and flavor)—or to CS from 3R4F reference cigarettes. The CS and base/test aerosol concentrations were matched at 35 µg nicotine/L. CS exposure, but not e-vapor exposure, led to impairment of lung function (pressure–volume loop area, A and K parameters, quasi-static elastance and compliance) and caused marked lung inflammation and emphysematous changes, which were confirmed histopathologically and morphometrically. CS exposure caused lung transcriptome (activation of oxidative stress and inflammatory responses), lipidome, and proteome dysregulation and changes in DNA methylation; in contrast, these effects were substantially reduced in response to the e-vapor aerosol exposure. Compared with sham, aerosol exposure (carrier, base, and test) caused a slight impact on lung inflammation and epithelia irritation. Our results demonstrated that, in comparison with CS, e-vapor aerosols induced substantially lower biological and pathological changes in the respiratory tract associated with chronic inflammation and emphysema.

Study of structural and mechanical properties of sodium alginate gels

Rheological parameters are an important characteristic of semisolid dosage forms. Structural and mechanical characteristics have a noticeable effect on the processes of release and absorption of drugs from ointments, as well as on their consumer properties: spreadability, adhesion, the ability to squeeze out of the tubes. The aim: to study the rheological parameters of aqueous solutions of sodium alginate in various concentrations to create medicinal hydrogel compositions. Materials and methods: sodium alginate (Shandong Topsea Seaweed Industrial Co., Ltd., China) was used as a gelling agent. The physicochemical properties of the samples were studied according to generally accepted methods of the State Pharmacopoeia of Ukraine. Rheological studies of experimental samples were carried out using a rotational viscometer «Rheolab QC», by Anton Paar (Austria) with coaxial cylinders C-CC27/SS at a temperature 20–25 °С. Results and discussion: the rheological profiles of sodium alginate gels have a non-Newtonian type of flow, which makes it possible to characterize them as systems with plastic-viscous properties. Gels with a sodium alginate concentration of 1.5–2 % have the best indicators of yield stress, hysteresis loop area, mechanical stability and dynamic flow coefficients. This indicates a low degree of destruction of the structural grid in the process of mechanical action and the presence of thixotropic bonds. Conclusions: sodium alginate gel base at 0.5 % and 1 % concentration is less stable under stress compared to sodium alginate bases at 1.5 % and 2 % concentration. The gel base of sodium alginate at a concentration of 2 % has the optimal mechanical stability value.