Viscosity

Electromotility is a basis for cochlear amplifier, which controls the sensitivity of the mammalian ear and contributes to its frequency selectivity. Because it is driven by the receptor potential, its frequency characteristics are determined by the low-pass RC filter intrinsic to the cell, which has a corner frequency about 1∕10th of the operating frequency. This filter significantly decreases the efficiency of electromotility as an amplifier. The present paper examines a proposal that the cochlear microphonic, the voltage drop across the extracellular medium by the receptor current, contributes to overcome this problem. It is found that this effect can improve frequency dependence. However, this effect alone is too small to enhance the effectiveness of electromotility beyond 10kHz in the mammalian ear.

Chitosan is an abundant natural biopolymer widely used in industrial and pharmaceutical applications. It stands out for its remarkable biodegradability, biocompatibility, and versatility. Herein, we tried to extract chitosan from mud crab (Scylla spp.), a seafood waste abundantly found in Bangladesh's growing crab farming industry, via a simple low-cost production route. At first, chitin was extracted from crab shells through demineralization and deproteinization to eliminate minerals and proteins. The chitosan biopolymer was then obtained by deacetylation of purified chitin. To evaluate its physicochemical properties, the as-prepared chitosan was characterized by different analyses, such as water and fat binding capacity, solubility, viscosity, molecular weight, fourier transform-infrared, thermogravimetric, scanning electron microscopy, and ash content analysis. The results showed that the crab shell contains around 26.8% chitosan by dry weight, making it an excellent raw material for the massive production of the natural biopolymer chitosan. The prepared chitosan showed fat and water binding capacities of 200-300% and ~680.9%, respectively. Furthermore, it was highly soluble in 1% acetic acid and had an ash content of about 33.7%. Convincingly, the produced chitosan showed great physiochemical properties making it suitable for biomass efficiency, sustainable development, revenue generation, and biomedical applications. In addition, the recycling of seafood waste into a valued product is beneficial to help keep the environment clean, which is among the sustainability goals in Bangladesh and globally.

Selection of appropriate friction factors is paramount for accurate prediction of key flow characteristics in gas–liquid two-phase flows. In this work, experimental investigation of vertical air and oil (with viscosities up to 200 mPa s) flow in a 0.060-m ID pipe is reported. Superficial air and oil velocity ranges utilized are from 22.37 to 59.06 m/s and 0.05 to 0.16 m/s respectively. The influence of estimation of interfacial friction factor on accurate determination of film thickness, void fraction and pressure gradient was investigated using a two-fluid model. The results indicated that the two-fluid model is capable of accurately predicting flow characteristics. Further, it reveals that the best performing correlations are the Belt et al. and Ambrosini et al. correlations.

Summary: Innovative reactor internals consisting of a number of vertically stacked perforated plates have been proposed to increase mass transfer rates of volatiles from highly viscous polymer melts. A mathematical model comprising mass and enthalpy balances for the polycondensation of polyamide 6 has been used to evaluate the new reactor design. According to the simulation, the alternating arrangement of devolatilization and residence zones leads to an effective removal of reaction water from the polymer melt. Compared to the VK‐tube reactor, which is most commonly used to produce high quality PA‐6, the new reactor design produces high quality polymer with a high degree of polymerization within a considerably shorter residence time. The application of the proposed reactor internals is not limited to PA‐6 production, since the removal of volatiles is of the same major importance during all reversible polycondensation reactions, e.g. the production of PET.

We extend the Clusters model to account for the presence of rigid inclusions and use it to analyze the experimental sintering kinetics of composites of 60SiO2·24B2O3·16Na2O glass particles and zirconia fibers. We followed the densification kinetics of such composites as a function of the particle size, volume fraction of fibers, fiber to pore size ratio, temperature, and time of thermal treatment. The parameters of the extended Clusters model are the glass particle size distribution and shape factor, the fiber volume fraction and radii, the glass viscosity and surface tension, the number of nucleating sites per unit surface, and the crystal growth rate in the parent glass. Hydrostatic tensions caused by the fibers were also included in the calculations. The modified Clusters model with only one adjustable parameter, which is largely dominated by viscosity but also includes particle shape, allowed us to account for the effect of surface crystallization and fiber content as inhibitors...

Submitted for the DFD13 Meeting of The American Physical Society Trajectory and flow properties for a rod spinning in a viscous fluid: An asymptotic solution with a no-slip plane LONGHUA ZHAO, Case Western Reserve University, ROBERTO CAMASSA, University of North Carolina at Chapel Hill, TERRY JO LEITERMAN, St. Norbert College, RICHARD MCLAUGHLIN, LEANDRA VICCI, University of North Carolina at Chapel Hill — Utilizing singularity theory and the slender body theory, asymptotic solutions are constructed for a slender body sweeping out a double cone or single cone in free space in the low Reynolds number regime. The asymptotic solutions are compared quantitatively with the exact solutions for a prolate spheroid performing similar motion. With a set of singularities, Blakelet, an asymptotic solution is developed for a slender cylinder attached to a no-slip plane and sweeping out an upright cone. The no-slip boundary condition is satisfied exactly. Trajectory and flow properties are examin...

ABSTRACT:  Physical properties of whey protein isolate (WPI) coating solution incorporating ascorbic palmitate (AP) and α‐tocopherol (tocopherol) were characterized, and the antioxidant activity of dried WPI coatings against lipid oxidation in roasted peanuts were investigated. The AP and tocopherol were mixed into a 10% (w/w) WPI solution containing 6.7% glycerol. Process 1 (P1) blended an AP and tocopherol mixture directly into the WPI solution using a high‐speed homogenizer. Process 2 (P2) used ethanol as a solvent for dissolving AP and tocopherol into the WPI solution. The viscosity and turbidity of the WPI coating solution showed the Newtonian fluid behavior, and 0.25% of critical concentration of AP in WPI solution rheology. After peanuts were coated with WPI solutions, color changes of peanuts were measured during 16 wk of storage at 25 °C, and the oxidation of peanuts was determined by hexanal analysis using solid‐phase micro‐extraction samplers and GC‐MS. Regardless of the ...

Periapical lesions are considered one of the common pathological conditions affecting alveolar bone. The primary focus of this study was to investigate the effectiveness of formulating an injectable in-situ forming scaffold-loaded with risedronate (bone resorption inhibitor) and with lornoxicam (anti-inflammatory drug) for the non-surgical treatment of periapical lesions. The scaffolds were prepared using solvent-induced phase inversion technique. Two insoluble copolymers were investigated namely; PLGA (ester-terminal) and PLGA-A (acid-terminal), additionally, SAIB was added as a high viscosity water-insoluble carrier. The addition of porogenic agents like hydrolyzed collagen was also investigated. The prepared scaffolds were characterized by analyzing their in-vitro release, DSC and rheological properties, besides their morphological properties. The results showed that the scaffolds prepared using 30% (w/v) PLGA or combined PLGA: SAIB (1:1, w/w) with total polymer concentration of ...

Abstract: The paucity of suitable drug formulations for pediatric patients generates a need for customized, compounded medications. This research study was set out to comprehensively analyze
the physical properties of the new, proprietary anhydrous oral vehicle SuspendIt® Anhydrous, which was designed for compounding pediatric oral liquids. A wide range of tests was used, including sedimentation volume, viscosity, droplet size after dispersion in simulated gastric fluid, microscopic examination and content uniformity measurements to evaluate the properties of the anhydrous vehicle. The results showed that the vehicle exhibited consistent physical properties under varying conditions and maintained stability over time. This can be attributed to the unique blend of excipients in its formulation, which not only maintain its viscosity but also confer thixotropic behavior. The unique combination of viscous, thixotropic and self-emulsifying properties allows for rapid redispersibility, sedimentation stability, accurate dosing, potential drug solubility, dispersion and promotion of enhanced gastrointestinal distribution and absorption. Furthermore, the vehicle demonstrated long-term sedimentation stability and content uniformity for a list of 13 anhydrous suspensions. These results suggest that the anhydrous oral vehicle could serve as a versatile base for pediatric formulation, potentially filling an important gap in pediatric drug delivery. Future studies can further investigate its compatibility, stability and performance with other drugs and in different clinical scenarios.

Keywords: pediatric drug delivery; extemporaneous preparations; innovative technologies; pharmaceutical development; anhydrous vehicle; sedimentation stability; thixotropic behavior; droplet size; self-emulsifying properties; content uniformity

Refractive index (RI) is a unique property of liquid or material. It is one of the important physicochemical properties of substances which provide information about the behavior of light. A cost effective system of measuring refractive index of a sample solution has been described here. Two optical fibers, one as transmitter and another as receiver is connected to a black glass chamber used for holding the sample liquid. Light from a He-Ne source is launched at one end of the transmitting fiber of which the other end is connected to one face of the glass chamber. The receiving fiber, connected to the opposite face of the glass chamber, collects a part of the refracted light passing through the sample solution. The light at the other end of the receiving fiber is detected by a photo detector. The output of the photo detector is calibrated in terms of voltage corresponding to the refractive index of the sample solution. By repeating the measurement for a number of times for different...