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The Flow of Cosmetics and Toiletries
Published in Laba Dennis, Rheological Proper ties of Cosmetics and Toiletries, 2017
Rheometer: An instrument used to measure the many different facets of rheology. All viscosimeters are also rheometers. Some Rheometers are much more complicated (and costly) than simple viscometers, but are capable of providing much more information in a variety of ways. For example, a rheometer may be able to run an entire shear rate range automatically, from 10-3 s-1 to 103 s-1, periodically taking viscosity readings and providing a viscosity profile.
Spinning of Dialysis Grade Membranes
Published in Sirshendu De, Anirban Roy, Hemodialysis Membranes, 2017
Standard rheometers that are used to measure viscosity and its variations due to applied shear stress, shear rates, temperature, and so on are available. These are also known as rotational viscometers. There are two types of rheometers: constant shear and constant rate. A typical rheometer machine (Figure 5.5a) has an air bearing–supported DC motor whose rotor is equipped with permanent magnets, whereas in the stator coils have opposite polarity, producing magnetic poles. The magnets in the rotor and the stator interact with each other and produce a flux of current that provides frictionless synchronous movement of the rotor. The torque produced by the motor is varied by varying the input current to the stator coil and, hence, can be measured. This torque is then used to measure shear rates, and the shear stress is measured using displacement of the upper measuring plate; thus, a curve between shear stress and shear rate yields viscosity of the sample. There are two types of arrangements to measure viscosity. These are the parallel plate and cone and plate (Figure 5.5a). Each has its own set of functionalities; the cone and plate are used for applying constant shear rate while the plate type is used for temperature-dependent tests. A typical rheometer is depicted in Figure 5.5b.
Newly developed nano-biocomposite embedded hydrogel to enhance drug loading and modulated release of anti-inflammatory drug
Published in Pharmaceutical Development and Technology, 2023
Sophia Varghese, Jai Prakash Chaudhary, Prachi Thareja, Chinmay Ghoroi
The material characterizations for different formulations CA, β-CD CA, Fe-CNB β-CD CA, and Fe-CNB CA were carried out after drug loading. The surface morphology and the elemental analysis were determined using field emission scanning electron microscopy (FE-SEM) along with EDS. The samples were coated with platinum before image analysis. The experiments were performed using (FE-SEM, JEOL JSM 7600 F, USA) at a working distance of 7–9 mm and 5–10 kV voltage. To study the interactions between drug-ibuprofen and hydrogel matrix fourier transform infrared spectroscopy (FTIR) (Perkin Elmer Spectrum GX-FTIR, USA) using the ATR method from wavenumber 4000–400 cm−1 was carried out. The crystalline nature of the material was investigated using powder X-ray diffraction (P-XRD). P-XRD measurements were performed using (Bruker D8 Discover) Cu-Kα, operating at 40 kV and 30 mA with a scan speed of 0.2 s/step and step size 0.02 and scanning range (2θ) from 5–90. Drug loading and release experiments were performed using a UV-vis spectrophotometer (Analytical Jena, Germany) at the wavelength (λ = 264 nm). Surface charge measurements were performed using a zeta sizer Nano ZS 90 (Malvern Instruments, UK). Rheological properties were measured with stress and strain-controlled modular compact rheometer (MCR 302, Anton Paar GmbH, Germany). All rheological tests were conducted at 25 °C.
A method for the tribological assessment of oral pharmaceutical liquids
Published in Drug Development and Industrial Pharmacy, 2022
Hyun Joo Lee, R. Gary Hollenbeck, Jill A. Morgan, Amy Kruger Howard, Akhtar Siddiqui, Vilayat A. Sayeed, Arzu Selen, Stephen W. Hoag
The HR-2 Discovery Hybrid Rheometer was also used to characterize the rheological behavior of the pharmaceutical liquids. The method was formulated based on recommendations from the TRIOS TA Instrument Guidelines 2016, USP: viscosity – rotational methods and the literature [12,15,26]. The studies were conducted at 25 °C with a 40 mm parallel plate geometry that rotates above the stationary steel Peltier base, with a gap setting of 500 µm. The presence of relatively large particles in some of the suspensions precluded the use of the cone and plate geometry, which has a fixed gap setting. A disposable pipette was used to load the sample onto the steel plate, creating a circular volume with a diameter approximately equal to the parallel plate. After sample loading, the plate was lowered to a trim gap of 520 µm. After lowering the top plate to the trim gap, any excess sample that extends beyond the diameter of the top plate is removed with a pipette or disposable wipe, and after trimming any excess sample, the instrument program moves the parallel plate to the geometry gap of 500 μm and initiates a linear up curve shearing rate ramp from 0.1 to 30 s−1 over a period of 300 s. Once the maximum shear rate is achieved, a down curve is immediately started by ramping the shear rate back down at the same declining rate. The instrument measures and reports the shear stress values at each shear rate and calculates a viscosity based on the ratio of shear stress to shear rate [35].
Rheological and in vitro release measurements of manufactured acyclovir 5% creams: confirming sensitivity of the in vitro release
Published in Pharmaceutical Development and Technology, 2021
Dalia Simona Miron, Flavian Ștefan Rădulescu, Victor A. Voicu, Alina Mînea, Jean-Michel Cardot, Vinod P. Shah
The microstructural analysis of the experimental acyclovir 5% creams was performed at 25 °C, using two screening tests, corresponding to oscillatory and rotational measurements. The equipment used was a HAAKE MARS 40 rheometer (Thermo Instruments, Bayern, Germany), with a temperature module controller and a cooling external circuit (Haake SC100/Haake S5P thermostat), equipped with RheoWin software, version 4.82. The measuring geometry was a cone-plate type C35 2°/Ti (35 mmm diameter, 0.101 mm truncation, cone angle β 2.013°, thermal expansion coefficient 1.100 µm/°C) at a gap size of 0.101 mm. The oscillatory measurements were performed in controlled stress mode for the evaluation of linear viscoelastic (LVER) region and yield stress (shear stress, σ between 1.0 and 100.0 Pa, in logarithmic progression, with acquisition of 100 data points). The yield stress (σy, Pa) values were calculated as the onset of storage modulus, G’ (Krishnaiah et al. 2014). For the rotational measurements, a thixotropy loop test was design: first rotation ramp, continuous and at controlled rate between 0.001 and 100.0 s−1, with logarithmic increase for 100 s and acquisition of 50 data points; rotation at 100 s−1 for 10 s, with an acquisition of 5 data points; second rotation ramp, continuous and at controlled rate between 100 and 0.001 s−1, with logarithmic decrease for 100 s and additional acquisition of 50 data points.