Characterization at 25°C of Sodium Hyaluronate in Aqueous Solutions Obtained by Transport Techniques

Mutual diffusion coefficients, D, were determined for aqueous solutions of sodium hyaluronate (NaHy) at 25°C and concentrations ranging from 0.00 to 1.00 g·dm-3 using the Taylor dispersion technique. From these experimental data, it was possible to estimate some parameters, such as the hydrodynamic radius Rh, and the diffusion coefficient at infinitesimal concentration, D0, of hyaluronate ion, permitting us to have a better understanding of the structure of these systems of sodium hyaluronate in aqueous solutions. The additional viscosity measurements were done and Huggins constant, kH, and limiting viscosity number, [η], were computed for interaction NaHy/water and NaHy/NaHy determination. © 2015, MDPI AG. All rights reserved.PTDC/AAC-CLI/118092/2010, FCT, Fuel Cycle TechnologiesFCT [PTDC/AAC-CLI/118092/2010]; Coimbra Chemistry Centre from the FCT [Pest-OE/QUI/UI0313/2014]; Centre of Polymer Systems [CZ.1.05/2.1.00/03.0111]; TBU in Zlin - specific university research and national budget of Czech Republic [IGA/FT/2013/015, IGA/FT/2014/018]; [SFRH/BD/72305/2010

Effect of hofmeister ions on transport properties of aqueous solutions of sodium hyaluronate

Tracer diffusion coefficients obtained from the Taylor dispersion technique at 25.0◦C were measured to study the influence of sodium, ammonium and magnesium salts at 0.01 and 0.1 mol dm−3 on the transport behavior of sodium hyaluronate (NaHy, 0.1%). The selection of these salts was based on their position in Hofmeister series, which describe the specific influence of different ions (cations and anions) on some physicochemical properties of a system that can be interpreted as a salting-in or salting-out effect. In our case, in general, an increase in the ionic strength (i.e., concentrations at 0.01 mol dm−3 ) led to a significant decrease in the limiting diffusion coefficient of the NaHy 0.1%, indicating, in those circumstances, the presence of salting-in effects. However, the opposite effect (salting-out) was verified with the increase in concentration of some salts, mainly for NH4SCN at 0.1 mol dm−3 . In this particular salt, the cation is weakly hydrated and, consequently, its presence does not favor interactions between NaHy and water molecules, promoting, in those circumstances, less resistance to the movement of NaHy and thus to the increase of its diffusion (19%). These data, complemented by viscosity measurements, permit us to have a better understanding about the effect of these salts on the transport behaviour of NaHy. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Fundacao para a Ciencia e a Tecnologia (FCT) through COMPETE Programme (Operational Programme for Competitiveness) [UIDB/QUI/00313/2020]; Ministry of Education, Youth and Sports of the Czech Republic DKRVO [RP/CPS/2020/003]Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2020/003; Fundação para a Ciência e a Tecnologia, FCT: UIDB/QUI/00313/202

Influence of lactose on the diffusion of calcium ions at physiological temperature

Mutual diffusion coefficients for calcium chloride (0.100 mol dm−3) in aqueous solutions containing lactose at various concentrations (from 0.005 to 0.200 mol dm−3) have been measured at 37 °C (physiological temperature), by using a conductimetric cell coupled to an automatic system to follow the diffusion. This cell uses an open-ended capillary method based on the measurement of the electrical resistance of a solution placed inside the capillaries at recorded times. The analysis of the CaCl2 diffusion coefficient values obtained suggests the presence of some CaCl2/lactose aggregates in the media, which are influenced by the temperature

FBG sensors application for residual stress measurement using the hole drilling method

This work focus on the development of a new sensor for residual stress measurement using fiber optic Bragg sensors. A known stress field was induced on a specimen and results obtained from both the fiber optic Bragg sensors rosette and traditional electrical strain rosette were compared. Also a FEM model was used to confirm the obtained results