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Copyright of Congreso Internacional de Investigacion Academia Journals is the property of PDHTech, LLC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Congreso Internacional de Investigacion Academia Journals is the property of PDHTech, LLC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mucus is mainly composed of water (90-95%) and mucins (2-5%), these mucins being high molecular weight macromolecules forming a 3D cross-linked matrix. It makes it a complex non-Newtonian fluid, displaying viscoplasticity, viscoelasticity, shear-thinning and thixotropy. These properties were qualitatively and separately tested by different authors. Due to the difficulties to collect samples and the extreme sensibility of the tested materials, the results are widely variable. A complete and intrinsically consistent characterization remains to be done to develop a reliable rheological model for future numerical simulations of mucus displacements in airways, in the case of pathologies such as cystic fibrosis. For this purpose, samples of mucus simulants were tested using a controlled stress rheometer. The material consists of macromolecular colloidal gels at different concentrations in macromolecules to mimic the variability in mucin production depending on the disease state and environmental factors. The rheological properties at rest were investigated using small amplitude oscillatory shear tests as a function of stress amplitude, frequency and temperature. They revealed that mucus simulant behaves as a gel within a defined linear viscoelastic region and as a viscoelastic liquid above the yield stress zone. To characterize the behavior of mucus in response to in vivo shearing induced by cough or by air flows produced by clearance helping devices, steady state flow tests have been performed. The steady state flow curves for various polymer concentrations are well fitted using a Herschel-Bulkley law. To account for the time dependent behavior of mucus, 3 intervals thixotropy tests were also implemented to monitor structure breakdown and buildup processes. The combination of all these measurements finally designs a reliable procedure accounting for the rheological complexities of mucus, that now needs to be applied to real mucus for validations. [ABSTRACT FROM AUTHOR]

Surimi products are well-considered by consumers as high-protein, low-fat and ready-to-eat fish products. Various food additives are added to surimi products to enhance the properties and nutritional value of the surimi gel. In recent years, both food researchers and the industry have been trying to use berry pomace as a dietary fibre additive in various foods. There is some research on the effect of dietary fibre on the formation of surimi gel, however, it is insufficient and currently, surimi products are not enriched with dietary fibre. The general objective of this study was to evaluate the influence of sea buckthorn pomace (SBP) on the protein interactions, texture and waterholding capacity (WHC) of surimi, as these properties are among the most important for the formation of surimi gel. Research results indicate that surimi contains mainly hydrophobic (8.15 ± 1.45%) and hydrogen (15.58 ± 0.53%) bonds. The addition of SBP to the surimi reduced the number of hydrophobic and hydrogen bonds to 1.63 ± 1.33% and 8.86 ± 1.89%, respectively. However, the addition of SBP increased the hardness of the gel (2.44 ± 0.19 N), as compared to surimi gel without SBP (1.35 ± 0.15 N). Fortification of surimi with the SBP resulted in an increase of WHC (93.68 to 97.01%). In conclusion, SBP, which is a by-product of berry juice processing, is applicable to improve the properties of surimi gel. Thus, SBP can be used for the enrichment of surimi products with dietary fibre. Moreover, these research results are promising for the production of higher value-added surimi-based products. [ABSTRACT FROM AUTHOR]

Dead Sea Salt (DSS) contains 21 minerials including magnesium, calcium, sulfur, bromide, iodine, sodium, zinc and potassium etc. On the other hand, Guar Gum (GG) is a natural polysaccharide, water soluble, having highest molecular weight and good gelling property. Due to such advantageous properties of DSS and GG, it has been taken interest to prepare a user friendly medicated gel (designated as GG-DSS gel) adding additional ingredients:e.g. Glycerol, Thymol, Ethanol, Seabuckthorn oil, and essencial oils for the improvment of the gel's medicated values and healing properties for the curing of general skin diseases/treatment. In this study, the viscoelastic behavior of GG-DSS gels were characterized by dynamic storage (G') and loss (G") moduli and complex viscosity as a function of angular frequency. The effect of DSS concentration and temperature on these properties of GG-DSS gels was investigated. All GG-DSS gels having different amount DSS shows G' higher than G" over a wide range of angular frequency. Both moduli have the trends to increase with the increase of temperature (temperature varies from 28°C to 50°C), and increase with the increase of DSS concentration higher than about 10%. In conclusion, it can be mentioned that the knowledge about the rheological properties of DSS-GG gels may be useful during the characterization of similar kinds of medicated gel. [ABSTRACT FROM AUTHOR]

Soft recovery of fast objects is an issue of considerable interest for many applications involving shock wave loading, such as ballistics, armor design, or more recently laser-driven inertial confinement fusion, where the characterization of the debris ejected from metallic shells subjected to intense laser irradiation conditions the design of the experiments. In this work, we compare the high velocity ejecta recovery efficiency of two materials: silica aerogel (density 0.03 g/cm³), which has been used as fragment collector for many years, and "varagel" (density 0.9 g/cm³), which we have tested recently in laser shock experiments. Ejected fragments have been recovered in both types of collectors. Then, samples have been analyzed by X-ray tomography at the European Synchrotron Radiation Facility (ESRF). Three-dimensional reconstructions of the fragments populations have been achieved, and quantitative comparisons between both collecting materials, used in the same conditions, have been performed. [ABSTRACT FROM AUTHOR]

Gelled propellants can be a promising replacement for next generation propulsion systems. For rocket engine operation, the application of a gelled fuel and gelled oxidizer can combine the advantages of liquid propellants (e.g., high performance, throttled operation, and multiple starts) without many of the specific disadvantages of the individual systems. A study is presented that describes the rheological behavior of gelled JP-8 turbine fuel and gelled rocket propellant RP-1 when fumed silica is used as a gelling agent. Along with the determination of an optimal gel mixing process, gel stability and rheological parameters showed a significant dependence on the added silica amount. [ABSTRACT FROM AUTHOR]

High-intensity focused ultrasound (HIFU) treatment that employs microbubbles to provide enhanced heating has been investigated in order to develop a less invasive and more rapid tumor therapy. Previous studies by us have demonstrated that ultrasound propagation is disturbed when there are microbubbles in front of the focus. In this study, we develop a method for obtaining enhanced heating by using microbubbles just at the focus, thus avoiding heating on the transducer side. In this method, microbubbles are destroyed in front of the HIFU focus (on the transducer side) by irradiating a very short burst wave of microsecond order, before irradiating the ultrasound waves for heating the focus. The experiment is conducted in a medium of a gel containing microbubbles, and a temperature-sensing liquid crystal sheet is set in the focus to observe the temperature distribution. The ultrasound frequency was 2.2 MHz and the intensity was 5000 W/cm2, and 20 burst wave waves were irradiated at pulse repetition frequency of 1 kHz. The number of wave pulses was varied. The continuous-wave frequency, intensity and irradiation time are 2.2 MHz, 1000 W/cm2 and 60 sec, respectively. As the number of pulses increased, the heating region moves from the transducer side to the focus. This is because microbubbles in front of the focus are destroyed and the ultrasound propagates around the target position effectively. These results suggest that the microbubble distribution and the heating position in the developed HIFU system can be controlled. [ABSTRACT FROM AUTHOR]

We investigated the structure and the formation process of two kinds of gels by Brownian dynamics simulation. The effect of flexibility of main chain oligomer was studied. From our results, hard gel with rigid main chain forms more homogeneous network structure than soft gel with flexible main chain. In soft gel, many small loops are formed, and clusters tend to shrink. This heterogeneous network structure may be caused by microgels. In the low density case, soft gel shows more heterogeneity than the high density case. [ABSTRACT FROM AUTHOR]

Most eukaryotic cells can crawl over surfaces. In general, this motility requires three distinct actions: polymerization at the leading edge, adhesion to the substrate, and retraction at the rear. Recent in vitro experiments with extracts from spermatozoa from the nematode Ascaris suum suggest that retraction forces are generated by depolymerization of the Major Sperm Protein (MSP) cytoskeleton. Combining polymer entropy with a simple kinetic model for disassembly I propose a model for disassembly-induced retraction that fit the in vitro experimental data. This model explains the mechanism by which deconstruction of the cytoskeleton produces the force necessary to pull the cell body forward and suggest further experiments that can test the validity of the model. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]