Two cystic fibrosis transmembrane conductance regulator mutations have different effects on both pulmonary phenotype and regulation of outwardly rectified chloride currents.

Cystic fibrosis (CF), a disorder of electrolyte transport manifest in the lungs, pancreas, sweat duct, and vas deferens, is caused by mutations in the CF transmembrane conductance regulator (CFTR). The CFTR protein has been shown to function as a cAMP-activated chloride channel and also regulates a separate protein, the outwardly rectifying chloride channel (ORCC). To determine the consequence of disease-producing mutations upon these functions, mutant CFTR was transiently expressed in Xenopus oocytes and in human airway epithelial cells lacking functional CFTR. Both G551D, a mutation that causes severe lung disease, and A455E, a mutation associated with mild lung disease, altered but did not abolish CFTR's function as a chloride channel in Xenopus oocytes. Airway epithelial cells transfected with CFTR bearing either A455E or G551D had levels of chloride conductance significantly greater than those of mock-transfected and lower than those of wild-type CFTR-transfected cells, as measured by chloride efflux. A combination of channel blockers and analysis of current-voltage relationships were used to dissect the contribution of CFTR and the ORCC to whole cell currents of transfected cells. While CFTR bearing either mutation could function as a chloride channel, only CFTR bearing A455E retained the function of regulating the ORCC. These results indicate that CF mutations can affect CFTR functions differently and suggest that severity of pulmonary disease may be more closely associated with the regulatory rather than chloride channel function of CFTR.

Recommendation of RILEM TC 178-TMC: Testing and modelling chloride penetration in concrete

This RILEM Technical Recommendation intends to give a general description of methods of sampling for obtaining chloride concentration profiles in concrete, applicable both for laboratory cast concrete specimens, for concrete cores taken from structures and for testing on site. These sampling procedures may be applied for obtaining concentration profiles of any other chemical species present in concrete.

Feasibility of electrochemical chloride extraction from structural reinforced concrete using a sprayed conductive graphite powder–cement paste as anode

This article summarizes research on the application of a conductive cement paste as an anode in the now classical technique of electrochemical extraction of chlorides applied to a concrete structural element by spraying the paste on the surface of a concrete structural element, a pillar. Sprayed conductive cement paste, by adding graphite powder, is particularly useful to treat sizable vertical surfaces such are structural supports. Outcomes indicate that this kind of anode not only provides electrochemical chloride removal with similar efficiency, but also is able to retain moisture even without the use of a continuous dampening system.

Chloride Penetration Prediction in Concrete through an Empirical Model Based on Constant Flux Diffusion

An empirical model based on constant flux is presented for chloride transport through concrete in atmospherical exposure conditions. A continuous supply of chlorides is assumed as a constant mass flux at the exposed concrete surface. The model is applied to experimental chloride profiles obtained from a real marine structure, and results are compared with the classical error-function model. The proposed model shows some advantages. It yields a better predictive capacity than the classical error-function model. The previously observed chloride surface concentration increases are compatible with the proposed model. Nevertheless, the predictive capacity of the model can fail if the concrete microstructure changes with time. The model seems to be appropriate for well-maturated concretes exposed to a marine environment in atmospherical conditions.

Efficiency of a conductive cement-based anodic system for the application of cathodic protection, cathodic prevention and electrochemical chloride extraction to control corrosion in reinforced concrete structures

This article describes the research carried out regarding the application of cathodic protection (CP) and cathodic prevention (CPrev), in some cases with a pre-treatment of electrochemical chloride extraction (ECE), on representative specimens of reinforced concrete structures, using an anodic system consisting of a graphite-cement paste applied as a coating on the surface. The aim of this research is to find out the competence of this anode for the aforementioned electrochemical treatments. The efficiency of this anode has been clearly demonstrated, as well as its capability to apply a combined process of ECE and after CP.

Procedure for calculating the chloride diffusion coefficient and surface concentration from a profile having a maximum beyond the concrete surface

Chlorides induce local corrosion in the steel reinforcements when reaching the bar surface. The measurement of the rate of ingress of these ions, is made by mathematically fitting the so called “error function equation” into the chloride concentration profile, obtaining so the diffusion coefficient and the chloride concentration at the concrete surface. However, the chloride profiles do not always follow Fick’s law by having the maximum concentration at the concrete surface, but often the profile shows a maximum concentration more in the interior, which indicates a different composition and performance of the most external concrete layer with respect to the internal zones. The paper presents a procedure prepared during the time of the RILEM TC 178-TMC: “Testing and modeling chloride penetration in concrete”, which suggests neglecting the external layer where the chloride concentration increases and using the maximum as an “apparent” surface concentration, called C max and to fit the error function equation into the decreasing concentration profile towards the interior. The prediction of evolution should be made also from the maximum.

Shape Effect of Electrochemical Chloride Extraction in Structural Reinforced Concrete Elements Using a New Cement-Based Anodic System

This article shows the research carried out by the authors focused on how the shape of structural reinforced concrete elements treated with electrochemical chloride extraction can affect the efficiency of this process. Assuming the current use of different anode systems, the present study considers the comparison of results between conventional anodes based on Ti-RuO2 wire mesh and a cement-based anodic system such as a paste of graphite-cement. Reinforced concrete elements of a meter length were molded to serve as laboratory specimens, to closely represent authentic structural supports, with circular and rectangular sections. Results confirm almost equal performances for both types of anode systems when electrochemical chloride extraction is applied to isotropic structural elements. In the case of anisotropic ones, such as rectangular sections with no uniformly distributed rebar, differences in electrical flow density were detected during the treatment. Those differences were more extreme for Ti-RuO2 mesh anode system. This particular shape effect is evidenced by obtaining the efficiencies of electrochemical chloride extraction in different points of specimens.

Presence of Siloxanes in the Biogas of a Wastewater Treatment Plant Separation in Condensates and Influence of the Dose of Iron Chloride on its Elimination

The siloxanes present in the biogas produced during anaerobic digestion damage the mechanism of cogeneration equipment and, consequently, negatively affect the energy valorization process. For this reason, the detection and elimination of these silicon-derived chemical compounds are a priority in the management of cogeneration facilities. In this regard, the objectives of this paper are, firstly, to characterize the siloxanes in the biogas and, secondly, to qualitatively evaluate the influence of the dose of iron chloride on its elimination. The research was performed at the Rincón de León Wastewater Treatment Plant (Alicante, Spain). The outflow biogas of the digesters and of the pressurized gasometers was sampled and analyzed. The results obtained made it possible to demonstrate, firstly, the absence of linear siloxanes and that, of the cyclic siloxanes, the predominant type was decamethylcyclopentasiloxane, and, secondly, that the addition of iron chloride in the digesters significantly reduces the siloxane content in the biogas. Additionally, it was demonstrated that the process of compression of the biogas, with the elimination of condensates, also produces significant reductions in the concentration of siloxanes in the biogas.

Dodecyltrimethylammonium chloride adsorption at the silica/water interface studied by Sum Frequency Generation

La génération des fréquences somme (SFG), une technique spectroscopique spécifique aux interfaces, a été utilisée pour caractériser les changements de la structure macromoléculaire du surfactant cationique chlorure de dodécyltriméthylammonium (DTAC) à l’interface silice/eau dans une plage de pH variant entre 3 et 11. Les conditions expérimentales ont été choisies pour imiter les conditions les plus communes trouvées pendant les opérations de récupération assistée du pétrole. Particulièrement, la silice a été étudiée, car elle est un des composantes des surfaces minérales des réservoirs de grès, et l’adsorption du surfactant a été étudiée avec une force ionique pertinente pour les fluides de la fracturation hydraulique. Les spectres SFG ont présenté des pics détectables avec une amplitude croissante dans la région des étirements des groupes méthylène et méthyle lorsque le pH est diminué jusqu’à 3 ou augmenté jusqu’à 11, ce qui suggère des changements de la structure des agrégats de surfactant à l’interface silice/eau à une concentration de DTAC au-delà de la concentration micellaire critique. De plus, des changements dans l’intensité SFG ont été observés pour le spectre de l’eau quand la concentration de DTAC augmente de 0,2 à 50 mM dans les conditions acide, neutre et alcaline. À pH 3, près du point de charge zéro de la surface de silice, l’excès de charge positive en raison de l’adsorption du surfactant cationique crée un champ électrostatique qui oriente les molécules d’eau à l’interface. À pH 7 et 11, ce qui sont des valeurs au-dessus du point de charge zéro de la surface de silice, le champ électrostatique négatif à l’interface silice/eau diminue par un ordre de grandeur avec l’adsorption du surfactant comme résultat de la compensation de la charge négative à la surface par la charge positive du DTAC. Les résultats SFG ont été corrélés avec des mesures de l’angle de contact et de la tension interfaciale à pH 3, 7 et 11.

Dodecyltrimethylammonium chloride adsorption at the silica/water interface studied by Sum Frequency Generation

La génération des fréquences somme (SFG), une technique spectroscopique spécifique aux interfaces, a été utilisée pour caractériser les changements de la structure macromoléculaire du surfactant cationique chlorure de dodécyltriméthylammonium (DTAC) à l’interface silice/eau dans une plage de pH variant entre 3 et 11. Les conditions expérimentales ont été choisies pour imiter les conditions les plus communes trouvées pendant les opérations de récupération assistée du pétrole. Particulièrement, la silice a été étudiée, car elle est un des composantes des surfaces minérales des réservoirs de grès, et l’adsorption du surfactant a été étudiée avec une force ionique pertinente pour les fluides de la fracturation hydraulique. Les spectres SFG ont présenté des pics détectables avec une amplitude croissante dans la région des étirements des groupes méthylène et méthyle lorsque le pH est diminué jusqu’à 3 ou augmenté jusqu’à 11, ce qui suggère des changements de la structure des agrégats de surfactant à l’interface silice/eau à une concentration de DTAC au-delà de la concentration micellaire critique. De plus, des changements dans l’intensité SFG ont été observés pour le spectre de l’eau quand la concentration de DTAC augmente de 0,2 à 50 mM dans les conditions acide, neutre et alcaline. À pH 3, près du point de charge zéro de la surface de silice, l’excès de charge positive en raison de l’adsorption du surfactant cationique crée un champ électrostatique qui oriente les molécules d’eau à l’interface. À pH 7 et 11, ce qui sont des valeurs au-dessus du point de charge zéro de la surface de silice, le champ électrostatique négatif à l’interface silice/eau diminue par un ordre de grandeur avec l’adsorption du surfactant comme résultat de la compensation de la charge négative à la surface par la charge positive du DTAC. Les résultats SFG ont été corrélés avec des mesures de l’angle de contact et de la tension interfaciale à pH 3, 7 et 11.

Rare earth and trace elements in igneous and metamorphic minerals of oceanic gabbros from the Mid-Atlantic Ridge

SIMS analyses have been carried out on clinopyroxenes, plagioclases and amphiboles of six gabbroic samples from Holes 921-924 of the Ocean Drilling Program Leg 153 sited in the MARK area of the Mid-Atlantic Ridge at the ridge-transform intersection, to investigate the rare earth, trace and volatile element distribution in the lower ocean crust during igneous crystallization and higher grade metamorphic conditions. The metagabbros underwent granulite to subgreenschist facies conditions through three main tectono-metamorphic phases: (1) ductile regime (750 < T < 1000 °C and P = 0.3 GPa); (2) transitional regime (600 < T < 700 °C and P = 0.2 GPa); (3) brittle regime (350 < T < 600 °C and P < 0.2 GPa). Igneous clinopyroxenes show Cl-chondrite normalized patterns depleted in LREE, and nearly flat for HREE. The rare earth and trace element distributions in igneous clinopyroxenes and plagioclases indicate that these minerals act as REE reservoirs, and comprise the main contribution to the overall rock content. The abundances in igneous minerals reflect the degree of fractionation of the parent liquids. In metamorphic clinopyroxenes recrystallized in anhydrous assemblages, the REE and trace elements patterns mimic those of the primary ones. Conversely, clinopyroxerie re-equilibrated in amphibolebearing assemblages shows a significant increase in REE, Ti, Zr, Y and V, a negative Eu anomaly, and slight decreases in Sr and Ba. An overall increase of REE and some trace elements is evident in hydrous assemblages, with preferential partitioning in the amphibole. It shows high Ti (18196-22844 ppm), LREE depleted patterns and LaN/SmN = 0.10-0.33, LaN/YbN = 0.10-0.30. Amphiboles from granoblastic assemblages show homogeneous patterns with no or a positive anomaly for TiN and negative anomalies for SrN and ZrN. Volatiles in amphibole are low, with Cl/F < 1; H2O% is significantly lower than the stoichiometric ratio (1.33-1.53%). The composition of the clinopyroxene and amphibole recrystallized in low-strain domains records evidence of incomplete re-equilibration, and element diffusion and partitioning is in part controlled by the textural site. The possible origins of the fluids involved in the metamorphic recrystallization are discussed: (1) remobilization from igneous amphibole; (2) exsolution from evolved melts; (3) introduction of seawater-derived fluids modified in rock-dominated systems; (4) injection of highly evolved hydrous melts during the metamorphic process.

Geochemistry, minerals, color, rare earth elements and d18O at DSDP Hole 92-504B

Investigations of borehole waters sampled in Hole 504B during Leg 92 revealed changes in major-ion composition similar to changes observed previously (during Leg 83). The uniformity of chloride concentrations with increasing depth suggests efficient downhole mixing processes along density gradients caused by large temperature gradients. Chemical and mineralogical studies of suspended drilling mud (bentonite) suggest that this material has undergone substantial alteration and that CaSO4 (anhydrite/gypsum) has precipitated in the deeper parts of the hole. Rare earth element studies suggest contributions of both the bentonites and the basalts to the REE distributions. Studies of the isotopic composition (87Sr/86Sr) of dissolved strontium indicate a strong contribution of basaltic nonradiogenic strontium, although differences between the Leg 83 and Leg 92 data indicate an influence of bentonite during Leg 92. The oxygen isotope composition of the water does not change appreciably downhole. This uniformity can be understood in terms of high water-rock ratios and suggests that the chemical changes observed are due either to alteration processes involving bentonites and basaltic material from the walls of the hole or to exchange with formation fluids from the surrounding basement, which may have altered in composition at relatively high water-rock ratios.

(Table 1) Deuterium ratios, chloride content and hydrate volume of pore water and hydrate meltwater from ODP Site 164-996

Site 996 is located above the Blake Diapir where numerous indications of vertical fluid migration and the presence of hydrate existed prior to Ocean Drilling Program (ODP) Leg 164. Direct sampling of hydrates and visual observations of hydrate-filled veins that could be traced 30-40 cm along cores suggest a connection between fluid migration and hydrate formation. The composition of pore water squeezed from sediment cores showed large variations due to melting of hydrate during core recovery and influence of saline water from the evaporitic diapir below. Analysis of water released during hydrate decomposition experiments showed that the recovered hydrates contained significant amounts of pore water. Solutions of the transport equations for deuterium (d2H) and chloride (Cl-) were used to determine maximum (d2H) and minimum (Cl-) in situ concentrations of these species. Minimum in situ concentrations of hydrate were estimated by combining these results with Cl- and d2H values measured on hydrate meltwaters and pore waters obtained by squeezing of sediments, by the means of a method based on analysis of distances in the two-dimensional Cl- d2H space. The computed Cl- and d2H distribution indicates that the minimum hydrate amount solutions are representative of the actual hydrate amount. The highest and mean hydrate concentrations estimates from our model are 31% and 10% of the pore space, respectively. These concentrations agree well with visual core observations, supporting the validity of the model assumptions. The minimum in situ Cl- concentrations were used to constrain the rates of upward fluid migration. Simulation of all available data gave a mean flow rate of 0.35 m/k.y. (range: 0.125-0.5 m/k.y.).

Impact of a Potassium-enriched, Chloride-depleted 5% Glucose Solution on Gastrointestinal Function after Major Abdominopelvic Surgery: Results of a Randomized Controlled Trial.

BACKGROUND Gastrointestinal (GI) complications often delay recovery after radical cystectomy with urinary diversion. The authors investigated if perioperative administration of a potassium-enriched, chloride-depleted 5% glucose solution (G5K) accelerates recovery of GI function. METHODS This randomized, parallel-group, single-center double-blind trial included 44 consecutive patients undergoing radical cystectomy and pelvic lymph node dissection with urinary diversion. Patients were randomized to receive either a G5K (G5K group) solution or a Ringer's maleate solution (control group). Fluid management aimed for a zero fluid balance. Primary endpoint was time to first defecation. Secondary endpoints were time to normal GI function, need for electrolyte substitution, and renal dysfunction. RESULTS Time to first defecation was not significantly different between groups (G5K group, 93 h [19 to 168 h] and control group, 120 h [43 to 241 h]); estimator of the group difference, -16 (95% CI, -38 to 6); P = 0.173. Return of normal GI function occurred faster in the G5K group than in the control group (median, 138 h [range, 54 to 262 h] vs. 169 h [108 to 318 h]); estimator of the group difference, -38 (95% CI, -74 to -12); P = 0.004. Potassium and magnesium were less frequently substituted in the G5K group (13.6 vs. 54.5% [P = 0.010] and 18.2 vs. 77.3% [P < 0.001]), respectively. The incidence of renal dysfunction (Risk, Injury, Failure, Loss and End-stage kidney disease stage "risk") at discharge was 9.1% in the G5K group and 4.5% in the control group; P = 1.000. CONCLUSIONS Perioperative administration of a G5K did not enhance first defecation, but may accelerate recovery of normal GI function, and reduces potassium and magnesium substitution after radical cystectomy and urinary diversion.