Pascal Seconds Research Articles

A study of combined minced meat from hydrobionts for snacks

This paper considers the developments whose application is promising for the fishing industry under the production of dried snack products. Fish chips are non-traditional dried products. The goal of this research was to study the functional and technological properties of minced systems consisting of fish and seafood. Minced systems were pre-treated with special food additives to improve their rheological properties and organoleptic indicators. The objects of research were stuffed meat products which included 65% to 75% of pollock, 15% of Pacific herring, and 10% to 20% of seafood. A study of technochemical indicators showed that minced systems were high-protein. They contained 30.0–34.8% of protein, 2.2–3.7% of lipids, and 0.8–2.5% of carbohydrates. Minced systems made of hydrobionts are characterised by the high water-holding capacity of 74.52–90.3%, which indicates good lyophilic properties of raw materials. When studying the rheological parameters of minced systems from hydrobionts, it was found that the maximum shift tension was 6.0–8.1 kPa. The stickiness index was 2 400–3 200 Pa, the dynamic viscosity was within the range of 650–850 Pa s (pascal seconds). The effective viscosity index for fish mince with good mouldability is 600–900 Pa s. The organoleptic evaluation showed that minced systems from hydrobionts pre-treated with food additives had high sensory characteristics.

The rheology and thermal history of Mars revealed by the orbital evolution of Phobos.

The evolution and internal structure of Mars are, by comparison to its present-day surface, poorly known-although evidence of recent volcanic activity1 suggests that its deep interior remains hot and convectively cooling. The cooling rate of Mars is related to its early thermal state and to its rheology, which determines its ability to deform and to dynamically evolve2. Attempts to reconstruct the dynamic history of Mars and reveal its present-day structure, by combining the study of thermal evolution with surface observations, are limited by the interplay between several key quantities-including temperature, composition and rheology. Here we show that by considering Phobos (the closest satellite of Mars)-the orbital evolution of which is governed by the thermochemical history of Mars, through tidal interactions-we can gain insight into the thermal history and rheology of the planet. We investigated the long-term evolution of the main envelopes of Mars; these comprise a liquid metallic core that is overlain by a homogeneous silicate convecting mantle underneath an evolving heterogeneous lithospheric lid that includes a crust enriched in radiogenic elements. By exploiting the relationship between Mars and Phobos within an established in situ scenario for the early origin of the moons of Mars3, we find that-initially-Mars was moderately hotter (100 to 200kelvin) than it is today, and that its mantle sluggishly deforms in the dislocation creep regime. This corresponds to a reference viscosity of 1022.2±0.5pascal seconds and to a moderate to relatively weak intrinsic sensitivity of viscosity to temperature and pressure. Our approach predicts a present-day average crustal thickness of 40±25kilometres and a surface heat flow of 20±1milliwatts per square metre. We show that combining these predictions with data from future and ongoing space missions-such as InSight-could reduce uncertainties in Martian thermal and rheological histories, and help to uncover the origin of Phobos.

Bacteriological Screening of Paediatric Cough Syrups Marketed Within Port Harcourt Metropolis, South-South Nigeria

Non-adherence to good manufacturing practice alongside improper handling during dispensing, packaging and inadequate post-marketing surveillance of pharmaceutical products accounts to product’s deterioration reduced therapeutic effect and adversely affects patient’s safety especially the paediatrics. This study evaluates the microbiological quality of various brands of paediatric cough syrups marketed and used within Port Harcourt metropolis. Twenty cough syrup brands were experimented on in duplicate, coded as USS and UNS (used and unused respectively). They were subjected to organoleptic assessment, pH, viscosity, total aerobic viable count, as well as resistance- susceptibility test of isolates using standard conventional techniques. Results showed viscosity value of 0.22 - 9.09 Pascal seconds (Pa.s), pH values of 3.13 - 8.34 across the UNS and USS categories respectively. While 80% of the UNS cough syrup samples were free from potential microbial threat, 20% fraction and all USS cough syrup (100%) samples were contaminated with objectionable microorganisms and non- compliant with USP permissible limit. The potentially pathogenic isolates were Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumonia, demonstrating varied resistance pattern to exposed antibiotic categories. Microbial contamination might have been caused by poor quality control and improper handling of the products during use. This calls for more stringent measures during product manufacturing and handling to ensure patient’s safety and forestall possible transference of resistance strain.

Investigating the effects of laryngotracheal stenosis on upper airway aerodynamics.

Very little is known about the impact of laryngotracheal stenosis (LTS) on inspiratory airflow and resistance, especially in air hunger states. This study investigates the effect of LTS on airway resistance and volumetric flow across three different inspiratory pressures. Head-and-neck computed tomography scans of 11 subjects from 2010 to 2016 were collected. Three-dimensional reconstructions of the upper airway from the nostrils to carina, including the oral cavity, were created for one subject with a normal airway and for 10 patients with LTS. Airflow simulations were conducted using computational fluid dynamics modeling at three different inspiratory pressures (10, 25, 40 pascals [Pa]) for all subjects under two scenarios: 1) inspiration through nostrils only (MC), and 2) through both nostrils and mouth (MO). Volumetric flows in the normal subject at the three inspiratory pressures were considerably higher (MC: 11.8-26.1 L/min; MO: 17.2-36.9 L/min) compared to those in LTS (MC: 2.86-6.75 L/min; MO: 4.11-9.00 L/min). Airway resistances in the normal subject were 0.051 to 0.092 pascal seconds per milliliter (Pa.s)/mL (MC) and 0.035-0.065 Pa.s/mL (MO), which were approximately tenfold lower than those of subjects with LTS: 0.39 to 0.89 Pa.s/mL (MC) and 0.45 to 0.84 Pa.s/mL (MO). Furthermore, subjects with glottic stenosis had the greatest resistance, whereas subjects with subglottic stenosis had the greatest variability in resistance. Subjects with tracheal stenosis had the lowest resistance. This pilot study demonstrates that LTS increases resistance and decreases airflow. Mouth breathing significantly improved airflow and resistance but cannot completely compensate for the effects of stenosis. Furthermore, location of stenosis appears to modulate the effect of the stenosis on resistance differentially. NA. Laryngoscope, 128:E141-E149, 2018.

Asthenosphere rheology inferred from observations of the 2012 Indian Ocean earthquake.

The concept of a weak asthenospheric layer underlying Earth's mobile tectonic plates is fundamental to our understanding of mantle convection and plate tectonics. However, little is known about the mechanical properties of the asthenosphere (the part of the upper mantle below the lithosphere) underlying the oceanic crust, which covers about 60 per cent of Earth's surface. Great earthquakes cause large coseismic crustal deformation in areas hundreds of kilometres away from and below the rupture area. Subsequent relaxation of the earthquake-induced stresses in the viscoelastic upper mantle leads to prolonged postseismic crustal deformation that may last several decades and can be recorded with geodetic methods. The observed postseismic deformation helps us to understand the rheological properties of the upper mantle, but so far such measurements have been limited to continental-plate boundary zones. Here we consider the postseismic deformation of the very large (moment magnitude 8.6) 2012 Indian Ocean earthquake to provide by far the most direct constraint on the structure of oceanic mantle rheology. In the first three years after the Indian Ocean earthquake, 37 continuous Global Navigation Satellite Systems stations in the region underwent horizontal northeastward displacements of up to 17 centimetres in a direction similar to that of the coseismic offsets. However, a few stations close to the rupture area that had experienced subsidence of up to about 4 centimetres during the earthquake rose by nearly 7 centimetres after the earthquake. Our three-dimensional viscoelastic finite-element models of the post-earthquake deformation show that a thin (30-200 kilometres), low-viscosity (having a steady-state Maxwell viscosity of (0.5-10) × 1018 pascal seconds) asthenospheric layer beneath the elastic oceanic lithosphere is required to produce the observed postseismic uplift.

Comparison of process parameter optimization using different designs in nanoemulsion-based formulation for transdermal delivery of fullerene.

This research aims to formulate and to optimize a nanoemulsion-based formulation containing fullerene, an antioxidant, stabilized by a low amount of mixed surfactants using high shear and the ultrasonic emulsification method for transdermal delivery. Process parameters optimization of fullerene nanoemulsions was done by employing response surface methodology, which involved statistical multivariate analysis. Optimization of independent variables was investigated using experimental design based on Box–Behnken design and central composite rotatable design. An investigation on the effect of the homogenization rate (4,000–5,000 rpm), sonication amplitude (20%–60%), and sonication time (30–150 seconds) on the particle size, ζ-potential, and viscosity of the colloidal systems was conducted. Under the optimum conditions, the central composite rotatable design model suggested the response variables for particle size, ζ-potential, and viscosity of the fullerene nanoemulsion were 152.5 nm, −52.6 mV, and 44.6 pascal seconds, respectively. In contrast, the Box–Behnken design model proposed that preparation under the optimum condition would produce nanoemulsion with particle size, ζ-potential, and viscosity of 148.5 nm, −55.2 mV, and 39.9 pascal seconds, respectively. The suggested process parameters to obtain optimum formulation by both models yielded actual response values similar to the predicted values with residual standard error of <2%. The optimum formulation showed more elastic and solid-like characteristics due to the existence of a large linear viscoelastic region.

Technical Note: New methodology for measuring viscosities in small volumes characteristic of environmental chamber particle samples

Abstract. Herein, a method for the determination of viscosities of small sample volumes is introduced, with important implications for the viscosity determination of particle samples from environmental chambers (used to simulate atmospheric conditions). The amount of sample needed is &lt; 1 μl, and the technique is capable of determining viscosities (η) ranging between 10−3 and 103 Pascal seconds (Pa s) in samples that cover a range of chemical properties and with real-time relative humidity and temperature control; hence, the technique should be well-suited for determining the viscosities, under atmospherically relevant conditions, of particles collected from environmental chambers. In this technique, supermicron particles are first deposited on an inert hydrophobic substrate. Then, insoluble beads (~1 μm in diameter) are embedded in the particles. Next, a flow of gas is introduced over the particles, which generates a shear stress on the particle surfaces. The sample responds to this shear stress by generating internal circulations, which are quantified with an optical microscope by monitoring the movement of the beads. The rate of internal circulation is shown to be a function of particle viscosity but independent of the particle material for a wide range of organic and organic-water samples. A calibration curve is constructed from the experimental data that relates the rate of internal circulation to particle viscosity, and this calibration curve is successfully used to predict viscosities in multicomponent organic mixtures.

Modelling the rheology of MgO under Earth’s mantle pressure, temperature and strain rates

Plate tectonics, which shapes the surface of Earth, is the result of solid-state convection in Earth's mantle over billions of years. Simply driven by buoyancy forces, mantle convection is complicated by the nature of the convecting materials, which are not fluids but polycrystalline rocks. Crystalline materials can flow as the result of the motion of defects--point defects, dislocations, grain boundaries and so on. Reproducing in the laboratory the extreme deformation conditions of the mantle is extremely challenging. In particular, experimental strain rates are at least six orders of magnitude larger than in nature. Here we show that the rheology of MgO at the pressure, temperature and strain rates of the mantle is accessible by multiscale numerical modelling starting from first principles and with no adjustable parameters. Our results demonstrate that extremely low strain rates counteract the influence of pressure. In the mantle, MgO deforms in the athermal regime and this leads to a very weak phase. It is only in the lowermost lower mantle that the pressure effect could dominate and that, under the influence of lattice friction, a viscosity of the order of 10(21)-10(22) pascal seconds can be defined for MgO.

Viscosity of fluids in subduction zones.

The viscosities of aqueous fluids with 10 to 80 weight percent dissolved silicates have been measured at 600 degrees to 950 degrees C and 1.0 to 2.0 gigapascals by in situ observation of falling spheres in the diamond anvil cell. The viscosities at 800 degrees C range from 10(-4) to 10(0.5) pascal seconds. The combination of low viscosities with a favorable wetting angle makes silicate-rich fluid an efficient agent for material transport at low-volume fractions. Our results therefore suggest that there may be a direct relationship between the position of the volcanic front and the onset of complete miscibility between water and silicate melt in the subducting slab.

The Haskell norm

The matter of the viscosity of the mantle has started to become serious. In 1935, Norm Haskell estimated the viscosity to be about 1020 poise and there the matter stood for about half a century. For a little while, people worried about excess ellipticity of the Earth and attributed this to a “fossil bulge” that lagged the rotation rate. For this same little while, 1025 poise was thought to be the viscosity of the lower mantle, but then it was discovered that the equator was also out of shape by about the same amount, ruling out the “fossil bulge” idea. To cover their embarrassment, geodynamicists upped the viscosity of the mantle to 1021 by adopting S.I. (Satan's Invention) units. No one noticed for some time since it didn't really matter whether viscosity was given in stokes, poise, or pascal seconds. It was just a large number with a large uncertainty and no one had a feel for it anyway.

The Nature of the Glass Transition in a Silica-Rich Oxide Melt

The atomic-scale dynamics of the glass-to-liquid transition are, in general, poorly understood in inorganic materials. Here, two-dimensional magic angle spinning nuclear magnetic resonance spectra collected just above the glass transition of K(2)Si(4)O(9) at temperatures as high as 583 degrees C are presented. Rates of exchange for silicon among silicate species, which involves Si-O bond breaking, have been measured and are shown to be closely related in time scale to those defined by viscosity. Thus, even at viscosities as high as 10(10) pascal seconds, local bond breaking (in contrast to the cooperative motion of large clusters) is of major importance in the control of macroscopic flow and diffusion.

Small-Scale Convective Instability and Upper Mantle Viscosity Under California

Thermal calculations and convection analysis, constrained by seismic tomography results, suggest that a small-scale convective instability developed in the upper 200 kilometers of the mantle under California after the upwelling and cooling of asthenosphere into the slab window associated with the formation of the San Andreas transform boundary. The upper bound for the upper mantle viscosity in the slab window, 5 x 10(19) pascal seconds, is similar to independent estimates for the asthenosphere beneath young oceanic and tectonically active continental regions. These model calculations suggest that many tectonically active continental regions characterized by low upper mantle seismic velocities may be affected by time-dependent small-scale convection that can generate localized areas of uplift and subsidence.

Rheological Properties of Magmas

Recent studies of igneous rocks have taken a refreshing new direction, mainly as the result of a greater awareness of the important role played by physical properties of magmas in determining the eruptive behavior and compositional variations of volcanic rocks. This rcview summarizes the present state of knowledge, along with some of the recent rheological studies having a direct bearing on interpretations of volcanic phenomena and processes of crystallization and differentiation of shallow magmatic intrusions. The rheological properties of magmas reflect the inherent structures of molten silicates and will not be thoroughly understood until more is known about the basic nature of silicate liquids. Recent progress in this field has been ably reviewed by Hess (1980) and needs no elaboration here aside from mention of the obvious need for better laboratory measurements in order to place greater constraints on interpretations of silicate melts. For petro­ genetic and volcanological processes, the most conspicuous need is for improved data on rheological properties, chiefly viscosity and yield strength, and for more precise equations for predicting these properties under a wide range of natural conditions. Viscosity, 1'/, is usually defined as the ratio of shear stress to strain rate and is expressed in units of poise (g cm 1 S 1) or Pascal seconds ( 10 poise = 1.0 Pa s). In more general terms, it is the coefficient for transfer of

Effect of gel-forming gums on the intestinal unstirred layer and sugar transport in vitro.

The effect of two gel-forming polysaccharide gums, guar gum and Na-carboxymethyl-cellulose (CMC), on glucose transport in vitro was investigated using everted sacs of rat jejunum. The gums were added to the mucosal bathing media to give apparent viscosities in the range of 1-110 Pascal seconds X 10(-3), mPa.s(cP). Serosal glucose transport fell steeply by about 60% as the viscosities of the mucosal media rose to 20mPa.s, and levelled off thereafter. A similar effect was observed in sacs preincubated with guar gum (15 minutes) and exposed to glucose in a subsequent guar-free incubation. Glucose transport with and without the addition of guar gum was found to be sensitive to mucosal stirring, so that, when shaken at 130 oscillations per minute, sacs exposed to guar gum (0.25 %, viscosity c.a. 16 mPa.s (cP) transported glucose at a similar rate to sacs incubated without guar at 80 oscillations per minute. By measuring the time course for the establishment of osmotic induced potentials, it was shown that incubation with guar or CMC led to an increase in the apparent thickness of the unstirred fluid layer overlying the mucosa (guar-free thickness = 317 +/- 15 mu, guar treated thickness = 468 +/- 25 mu). It is suggested that the presence of a polysaccharide gum in the fluid film surrounding the villi increases its viscosity, and thus gives rise to a thickening of the rate-limiting unstirred layer. If such an effect occurs in vivo, this could contribute to the diminished post-prandial glycaemia observed in human subjects fed guar gum.