scholarly journals Investigation of the dependences of the rheology of calcium alginate solutions on concentration, temperature and shear rate

2021 ◽  
Vol 83 (1) ◽  
pp. 100-105
Author(s):  
S.S. Karpova ◽  
◽  
A.K. Ospanova ◽  
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Calcium Alginate ◽  
Room Temperature ◽  
Practical Interest ◽  
Capillary Viscometer ◽  
Organic Salts ◽  
Calcium Salts ◽  
Low Concentrations ◽  
Object Of Study

The main problem: The rheological properties of calcium salts are of theoretical and practical interest for a modern researcher. The theoretical interest is primarily related to the search for general patterns and manifestations of the rheological properties of solutions of calcium salts. The practical component is based on the search for patterns and dependencies of the properties of solutions on the structure and composition of the object of study. Such chemicals as calcium salts are of particular practical interest, they are widely used in various fields, such as the food, chemical and pharmacological industries. Hydrophilic high-molecular solutions of alginates, namely calcium alginate, are actively used in the preparation of soft dosage forms, the manufacture of jelly masses in confectionery, act as thickeners in the food industry. They are characterized by a fairly high percentage of viscosity at low concentrations, bioavailability, prolonging effect, absence of irritating properties, biocompatibility with many polymers, which is especially important in the pharmaceutical industry and medicine. The use of calcium salts for these purposes is currently very promising, since these organic salts have a number of unique properties associated with gelation. Purpose: This paper contains the results of studying the features of the rheology of calcium alginate solutions. A concentration range of 0.1-0.7 % was chosen for the studies, which is sufficient to avoid gelation at room temperature. The dependence of viscosity on concentration, temperature (in the range of 25-45 °C) and shear rate were studied. Methods: Analysis of theoretical sources, observation, comparison of results. The rheological characteristics of the obtained substances were studied using a capillary viscometer. The measurements were carried out in the temperature range of 25-45°C. Results and their significance: it was found that there is a significant dependence of viscosity on concentration and temperature. For concentrations of 0.3 – 0.7 %, a similar type of dependence is observed, in contrast to solutions with a concentration of 0.1 % . Explanations of these dependencies were proposed.

The Rheological Properties of κ-Carrageenan-Konjac Gum Mixed Gel

2013 ◽  
Vol 781-784 ◽  
pp. 1652-1655
Author(s):  
Yu Wei ◽  
Yuan Lan Wang
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Modulus Of Elasticity ◽  
Small Amplitude ◽  
Plastic Behavior ◽  
Rheological Analysis ◽  
Low Concentrations ◽  
Konjac Gum

The rheological properties of κ-Carrageenan-Konjac Gum Mixed Gel were investigated by using dynamic rheological analysis. Results showed that the mixture of κ-Carrageenan and Konjac Gum had higher modulus of elasticity than single κ-Carrageenan or Konjac Gum. Blends solution has a good pseudo-plastic behavior at low concentrations, viscosity declined rapidly with shear rate increased. K+ and Ca2+ participated in the gelatin process and under the controlled condition might enhance force among molecules. With the temperature increasing G' and G" increased, and G' and G" presented suddenly change at 60-70 °C. Small amplitude oscillatory tests in the linear domain of viscoelasticity showed that κ-Carrageenan played the major role in the viscoelasticity of the mixture, and Konjac gum strengthened the gel-net configuration and stability.

scholarly journals Ag Nanoparticles Sensitized In2O3 Nanograin for the Ultrasensitive HCHO Detection at Room Temperature

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Shiqiang Zhou ◽  
Mingpeng Chen ◽  
Qingjie Lu ◽  
Yumin Zhang ◽  
Jin Zhang ◽  
...  
Keyword(s):  
Indoor Air ◽  
Ag Nanoparticles ◽  
Room Temperature ◽  
Unsolved Problem ◽  
Air Pollutant ◽  
Ag Nps ◽  
Performance Targets ◽  
Fabrication Cost ◽  
Low Concentrations ◽  
Stringent Performance

AbstractFormaldehyde (HCHO) is the main source of indoor air pollutant. HCHO sensors are therefore of paramount importance for timely detection in daily life. However, existing sensors do not meet the stringent performance targets, while deactivation due to sensing detection at room temperature, for example, at extremely low concentration of formaldehyde (especially lower than 0.08 ppm), is a widely unsolved problem. Herein, we present the Ag nanoparticles (Ag NPs) sensitized dispersed In2O3 nanograin via a low-fabrication-cost hydrothermal strategy, where the Ag NPs reduces the apparent activation energy for HCHO transporting into and out of the In2O3 nanoparticles, while low concentrations detection at low working temperature is realized. The pristine In2O3 exhibits a sluggish response (Ra/Rg = 4.14 to 10 ppm) with incomplete recovery to HCHO gas. After Ag functionalization, the 5%Ag-In2O3 sensor shows a dramatically enhanced response (135) with a short response time (102 s) and recovery time (157 s) to 1 ppm HCHO gas at 30 °C, which benefits from the Ag NPs that electronically and chemically sensitize the crystal In2O3 nanograin, greatly enhancing the selectivity and sensitivity.

Flow Behaviors of High Acyl Gellan Aqueous Solutions as Affected by Temperature, and Calcium and Gellan Concentrations

2008 ◽  
Vol 4 (5) ◽  
Author(s):  
Yiqun Huang ◽  
Pawan Singh Takhar ◽  
Juming Tang ◽  
Barry G Swanson
Keyword(s):  
Shear Rate ◽  
Aqueous Solutions ◽  
Apparent Viscosity ◽  
Flow Resistance ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Influence Of Temperature ◽  
Rheological Behaviors ◽  
Low Concentrations ◽  
Influence Of Temperature On

Rheological behaviors of high acyl (HA) gellan are not well understood partially because of its relatively late commercialization compared to low acyl gellan. The objective of this study was to investigate the effect of temperature (5-30 °C), calcium (0, 1 and 10 mM) and gellan concentrations (0.0044-0.1000% w/v) on the flow behaviors of high acyl gellan aqueous solutions using rheological tests. Gellan solutions with 0 or 1 mM added Ca++ exhibited shear thinning behavior at gellan concentrations above 0.0125%. The influence of temperature on apparent viscosity (shear rate, 100 s-1) of gellan solutions can be described with an Arrhenius relationship. The apparent viscosity of gellan solution at low concentrations was more sensitive to temperature changes. The addition of Ca++ led to a decrease in flow resistance for a dilute gellan solution (<0.0125%), but an increased resistance for a relatively concentrated gellan solution (>0.0125%).

Enhancing Rheological Properties and Reduction of Total Acid Number of a Heavy Crude Oil Using Ethanol and Trona

2021 ◽  
Author(s):  
Ahmed Almadhaji ◽  
Mohammed Saeed ◽  
Hitham Ibrahim ◽  
Anas Ahmed ◽  
Ragaei Maher
Keyword(s):  
Crude Oil ◽  
Rheological Properties ◽  
Kinematic Viscosity ◽  
Acid Number ◽  
Capillary Viscometer ◽  
Heavy Crude Oil ◽  
Production Operation ◽  
Total Acid ◽  
Total Acid Number ◽  
Heavy Crude

Abstract One of Sudanese fields has a heavy crude oil which has a high Total Acid Number (TAN) and high viscosity, can cause a lot of problems in production operation, transport, and storage facilities. The effect of ethanol dilution on the rheological properties of crude (especially the kinematic viscosity) was studied and presented. Moreover, the consequence of blending Trona (NaHCO3.Na2CO3) with a specified amount of Ethanol in the crude can reduce (TAN) to acceptable limits for solving corrosion and flowability problems. The approach is based on the experiments and laboratory works on the crude's samples after blending with a certain amount of Trona and Ethanol. It depends on the results of apparatuses, that are used to measure the samples, for instance, Calibrated glass capillary viscometer and ASTM D664 titration volume Total Acid Number tester which are employed to get the values of kinematic viscosity and TAN, respectively. The tests are established with crude have kinematic viscosity (187 cst) at temperature 75°C and TAN almost (8.51). While increasing the dosage of Trona at the ambient temperature (38°C) with the certain mass percentage of Ethanol (5%), TAN is decreased from (8.51 to 4.00 mgKOH/g). Also, the kinematic viscosity is declined from (187 cst to 96.75 cst) after increasing the volume of Ethanol at 75°C. These outcomes indicated that Ethanol could reduce Sudanese heavy crude's viscosity, and the Trona could decrease the TAN. This reduction occurred due to Ethanol dilution. The Ethanol molecules disturb the molecular structure of the crude, which forms polar bond within the hydrocarbon chain that leads to lower the friction between molecules of hydrocarbon in the crude. Also, Trona shrinks TAN because the Hydroxide ions (OH+) that founded in Trona neutralize the Hydrogen ions (H−) in Naphthenic acid in Sudanese heavy crude. This study can be summarized in the ability to solve the difficulty of transporting and processing the heavy crude oil in refineries; maintains the quality of the crude while utilizing it with friendly environmental materials and low cost.

scholarly journals Metallicity and Superconductivity in Doped Strontium Titanate

2019 ◽  
Vol 10 (1) ◽  
pp. 25-44 ◽  
Author(s):  
Clément Collignon ◽  
Xiao Lin ◽  
Carl Willem Rischau ◽  
Benoît Fauqué ◽  
Kamran Behnia
Keyword(s):  
Liquid Helium ◽  
Free Path ◽  
Coulomb Interaction ◽  
Strontium Titanate ◽  
Room Temperature ◽  
Mean Free Path ◽  
Helium Temperature ◽  
Ongoing Research ◽  
Low Concentrations ◽  
Wide Gap

Strontium titanate is a wide-gap semiconductor avoiding a ferroelectric instability thanks to quantum fluctuations. This proximity leads to strong screening of static Coulomb interaction and paves the way for the emergence of a very dilute metal with extremely mobile carriers at liquid-helium temperature. Upon warming, mobility decreases by several orders of magnitude. Yet, metallicity persists above room temperature even when the apparent mean free path falls below the electron wavelength. The superconducting instability survives at exceptionally low concentrations and beyond the boundaries of Migdal–Eliashberg approximation. An intimate connection between dilute superconductivity and aborted ferroelectricity is widely suspected. In this review, we give a brief account of ongoing research on bulk strontium titanate as an insulator, a metal, and a superconductor.

Rheological Properties and Anti-Aging Properties of PP/PP-g-AN Blends

2013 ◽  
Vol 815 ◽  
pp. 579-583 ◽  
Author(s):  
Ya Zhen Wang ◽  
Cheng E Yue ◽  
Di Ma ◽  
Wei Nan Jia ◽  
Yong Li
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Solid Phase ◽  
Testing Time ◽  
Pseudoplastic Fluid ◽  
Aging Properties

The effect of PP-g-AN prepared by solid phase grafting on the blends of PP/PP-g-AN was investigated in this paper. The influence of aging testing time, PP-g-AN additives concentration, shear rate on the rheological properties and anti-aging properties of PP/PP-g-AN were mainly discussed. The results show that PP/PP-g-AN blends are pseudoplastic fluid and the presence of PP-g-AN can restrain the degradation of polypropylene when the content of PP-g-AN is in a certain range.

scholarly journals Temperature Effects on Optical Trapping Stability

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 954
Author(s):  
Dasheng Lu ◽  
Francisco Gámez ◽  
Patricia Haro-González
Keyword(s):  
Brownian Motion ◽  
Environmental Conditions ◽  
Temperature Effects ◽  
Room Temperature ◽  
Optical Trapping ◽  
State Of The Art ◽  
Thermal Sensing ◽  
The Stability ◽  
Object Of Study ◽  
Optically Trapped

In recent years, optically trapped luminescent particles have emerged as a reliable probe for contactless thermal sensing because of the dependence of their luminescence on environmental conditions. Although the temperature effect in the optical trapping stability has not always been the object of study, the optical trapping of micro/nanoparticles above room temperature is hindered by disturbances caused by temperature increments of even a few degrees in the Brownian motion that may lead to the release of the particle from the trap. In this report, we summarize recent experimental results on thermal sensing experiments in which micro/nanoparticles are used as probes with the aim of providing the contemporary state of the art about temperature effects in the stability of potential trapping processes.

scholarly journals Effect of GNWs/NiO-WO3/GNWs Heterostructure for NO2 Gas Sensing at Room Temperature

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 626
Author(s):  
Seokhun Kwon ◽  
Seokwon Lee ◽  
Joouk Kim ◽  
Chulmin Park ◽  
Hosung Jung ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Room Temperature ◽  
Microwave Plasma ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Gas Concentration ◽  
Negative Change ◽  
Low Concentrations ◽  
Detection Characteristics ◽  
No2 Detection

Recently, as air pollution and particulate matter worsen, the importance of a platform that can monitor the air environment is emerging. Especially, among air pollutants, nitrogen dioxide (NO2) is a toxic gas that can not only generate secondary particulate matter, but can also derive numerous toxic gases. To detect such NO2 gas at low concentration, we fabricated a GNWs/NiO-WO3/GNWs heterostructure-based gas sensor using microwave plasma-enhanced chemical vapor deposition (MPECVD) and sputter, and we confirmed the NO2 detection characteristics between 10 and 50 ppm at room temperature. The morphology and carbon lattice characteristics of the sensing layer were investigated using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. In the gas detection measurement, the resistance negative change according to the NO2 gas concentration was recorded. Moreover, it reacted even at low concentrations such as 5–7 ppm, and showed excellent recovery characteristics of more than 98%. Furthermore, it also showed a change in which the reactivity decreased with respect to humidity of 33% and 66%.

scholarly journals Electro-Rheological Properties of Liquid Crystal in High Shear Rate Region

2007 ◽  
Vol 35 (2) ◽  
pp. 85-91 ◽  
Author(s):  
Takatsune Narumi ◽  
Hiroyoshi Maeda ◽  
Hiroyuki Yoshizawa ◽  
Tomiichi Hasegawa
Keyword(s):  
Liquid Crystal ◽  
Shear Rate ◽  
Rheological Properties ◽  
High Shear Rate ◽  
High Shear ◽  
Rate Region
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