Effect of non-isothermal flow on chloride ion transport in saturated concrete

The presence of a temperature difference changes the mode of motion of the fluid. The macroscopic motion of the fluid causes the relative displacement between the various parts of the fluid, which in turn affects the transfer of temperature in the medium. To investigate the effect of temperature transfer coupled fluid motion on chloride ion transport in concrete, a mesoscopic model of chloride ion transport in non-isothermal flow of concrete was established and compared with experimental data. Based on the finite element software, the influence of temperature transfer on the internal fluid motion and chloride ion transport of concrete was analyzed. And the effect of convective motion of fluid on the temperature transfer in concrete was studied. It is found that when the heating time is the same, the dynamic viscosity of the fluid in the concrete decreases with the increase of temperature; the chloride ion concentration increases with the increase of temperature at the same depth of concrete; when considering the influence of laminar flow, the temperature is transmitted faster in the concrete and exhibits uneven diffusion from high temperature to low temperature; non-isothermal flow promotes the diffusion of chloride ions in concrete, and the higher the temperature.

Analysis of changes in sodium and chloride ion transport in the skin

The measurement of electric potential and resistance reflect the transport of sodium and chloride ions which take place in keratinocytes and is associated with skin response to stimuli arising from external and internal environment. The aim of the study was to assess changes in electrical resistance and the transport of chloride and sodium ions, under iso-osmotic conditions and following the use of inhibitors affecting these ions’ transport, namely amiloride (A) and bumetanide (B). The experiment was performed on 104 fragments of rabbit skin, divided into three groups: control (n = 35), A—inhibited sodium transport (n = 33) and B—inhibited chloride transport (n = 36). Measurement of electrical resistance (R) and electrical potential (PD) confirmed tissue viability during the experiment, no statistically significant differences in relation to control conditions were noted. The minimal and maximal PD measured during stimulation confirmed the repeatability of the recorded reactions to the mechanical and mechanical–chemical stimulus for all examined groups. Measurement of PD during stimulation showed differences in the transport of sodium and chloride ions in each of the analyzed groups relative to the control. The statistical analysis of the PD measured in stationary conditions and during mechanical and/or mechanical–chemical stimulation proved that changes in sodium and chloride ion transport constitute the physiological response of keratinocytes to changes in environmental conditions for all applied experimental conditions. Assessment of transdermal ion transport changes may be a useful tool for assessing the skin condition with tendency to pain hyperactivity and hypersensitivity to xenobiotics.

The short-term rinsing of airways by N-acetylcysteine helps expectoration: The mechanism of sodium and chloride transport

N-acetyl-L-cysteine (NAC) mucolytic and antioxidant role is well known, but the effect on epithelial ion transport has not been yet described. The aim of the study was to evaluate the short-term and prolonged influence of NAC on ion transport in the epithelium. The experiment was performed on 108 fragments of rabbit tracheae. Fragments were divided into four groups: inhibited sodium (I) and chloride (II) transport, NAC with inhibited sodium (III) and NAC with inhibited chloride (IV) transport. The changes in electrophysiological parameters were measured in stationary conditions and during mechanical-chemical stimulation after immediate (15 s) and prolonged (60 min) N-acetylcysteine administration on the tissue. Each 15-second stimulation caused repeatable changes in the electric potential of the tissue. In trachea fragments with blocked chloride ion transport, significantly lower (P <0.0001) values of electric potential following prolonged NAC effect were observed when compared to short-term NAC-stimulation. The values of resistance were constant during experiments, which reflects the vitality of the tissue. Short-term NAC administration influences sodium ion transport, which is not observed in a prolonged stimulation. The use of the NAC solution to rinse the airways is of great clinical importance due to the short and intense contact with the epithelium.

Study of the Effect of Surface Treatment on the Chloride Ion Transport at the Cementitious Spacer–Concrete Interface

Spacers are important components in reinforced concrete structures to provide cover between the steel reinforcement and the formwork. Cementitious spacers are of particular interest for coastal engineering structures, as they are compatible with cement-based chloride-resistant high-performance concrete compared to plastic and steel spacers. However, the cementitious spacer–concrete interface was found to be highly porous and microcracked. This study investigated the effect of surface treatment on the chloride ion transport at the cementitious spacer–concrete interface. A surface treatment technique for potential mass production was introduced and the state-of-practice tests of the hardened concrete were modified to evaluate the performance of the spacer–concrete composite specimens. The results showed that the surface treatment on a cementitious spacer improved the bonding between the spacer and concrete at the interface. The surface treatment of the spacer improved the compressive strength and the chloride resistance of the composite specimen locally compared to those without surface treatment. The advantage of surface treatment on the chloride resistance was partially represented in either the diffusion coefficient or the column electric flux. The maximum chloride ion penetration depth at the spacer–concrete interface was recommended as an additional proxy for the evaluation of the chloride resistance performance of composite specimens.