Resistance of alkali activated slag concretes to chloride environments

ABSTRACT: Researchers are focusing their attention on alternative binder systems using 100% supplementary cementitious materials as it allows better control over the microstructure formation and low to moderate environmental footprint. One such system being considered is alkali activated slag concretes (AASC), made by adding alkalis such as sodium hydroxide and sodium silicate to ground granulated blast furnace slag (GGBS). Whilst they have a similar behaviour as that of traditional cement systems in terms of strength and structural behaviour, AASC are reported to exhibit superior performance in terms of abrasion,acid resistance and fire protection.
In this article, the authors investigate chloride ingress into different grades of AASC. The mix variables in AASC included water to binder, and binder to aggregate ratio, percentage of alkali and the SiO2/Na2O ratio (silica modulus, Ms). The first challenge was to develop mixes for different range of workability (with slump values from 40mm to 240mm) and reasonable early age and long term compressive strength. Further chloride ingress into those mixes were assessed and compared with the data from normal concretes based on literature. Findings show that compared to the PC concretes, the AAS concretes have lower rate of chloride ingress.

Oxygen and Chloride Permeability of Alkali-Activated Natural Pozzolan Concrete

One of the important factors in the use of portland cement concrete is its durability, and most of the situations where durability is lacking have been identifi ed and strategies to manage durability have been implemented. Geopolymer concrete, made from an alkali-activated natural pozzolan (AANP), provides an important opportunity for the reduction of carbon dioxide (CO2) emissions associated with the manufacture of concrete but has a limited history of durability studies. Until its different properties are well understood there is no desire to adopt this new technology of unknown provenance by the concrete industry. This paper presents an experimental study of oxygen and chloride permeability of AANP concrete prepared by activating Taftan andesite and Shahindej dacite (Iranian natural pozzolans), with and without calcining, and the correlations between these properties and compressive strength. The results show that compared to ordinary portland cement (OPC) concrete, AANP concrete has lower oxygen permeability at later ages; but it shows moderate to high chloride ion penetrability.

Effect of II‐VI Semiconductor Nanomaterials and Electron Irradiation on Polystyrene (PS) & Poly(ethylene‐co‐vinyl acetate) (EVA)

Organic-inorganic nanocomposites combine unique properties of both the constituents in one material. Among this group of materials, clay based as well as ZnO, TiO2 nanocomposites have been found to have diverse applications. Optoelectronic devices require polymerinorganic systems to meet certain desired properties. Dielectric properties of conventional polymers like poly(ethylene-co-vinyl acetate) (EVA) and polystyrene (PS) may also be tailor tuned with the incorporation of inorganic fillers in very small amounts. Electrical conductivity and surface resistivity of polymer matrices are found to improve with inorganic nanofillers. II-VI semiconductors and their nano materials have attracted material scientists because of their unique optical properties of photoluminescence, UV photodetection and light induced conductivity. Cadmium selenide (CdSe), zinc selenide (ZnSe) and zinc oxide (ZnO) are some of the most promising members of the IIVI semiconductor family, used in light-emitting diodes, nanosensors, non-linear optical (NLO) absorption etc. EVA and PS materials were selected as the matrices in the present study because they are commercially used polymers and have not been the subject of research for opto-electronic properties with semiconductor nanomaterials

Estimating Natural Recharge by Means of Chloride Mass Balance in a Volcanic Aquifer: Northeastern Gran Canaria (Canary Islands, Spain)

[EN]The chloride mass balance method was used to estimate the average diffuse groundwater recharge on northeastern Gran Canaria (Canary Islands), where the largest recharge to the volcanic island aquifer occurs. Rainwater was sampled monthly in ten rainwater collectors to determine the bulk deposition rate of chloride for the 2008–2014 period. Average chloride deposition decreases inwardly from more than 10 g·m−2 ·year−1 to about 4 g·m−2 ·year−1 . The application of the chloride mass balance method resulted in an estimated average recharge of about 28 hm3 /year or 92 mm/year (24% of precipitation) in the study area after subtracting chloride loss with surface runoff.

Influence of grinding operations on surface integrity and chloride induced stress corrosion cracking of stainless steels

Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes. The central theme of this thesis is the mechanical grinding process.  This is commonly used for producing stainless steel components, and results in varied surface properties that will strongly affect their service life. The influence of grinding parameters including abrasive grit size, machine power and grinding lubricant were studied for 304L austenitic stainless steel (Paper II) and 2304 duplex stainless steel (Paper I). Surface integrity was proved to vary significantly with different grinding parameters. Abrasive grit size was found to have the largest influence. Surface defects (deep grooves, smearing, adhesive/cold welding chips and indentations), a highly deformed surface layer up to a few microns in thickness and the generation of high level tensile residual stresses in the surface layer along the grinding direction were observed as the main types of damage when grinding stainless steels. A large degree of residual stress anisotropy is interpreted as being due to mechanical effects dominating over thermal effects. The effect of grinding on stress corrosion cracking behaviour of 304L austenitic stainless steel in a chloride environment was also investigated (Paper III). Depending on the surface conditions, the actual loading by four-point bend was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks initiation on the ground surfaces. Grinding along the loading direction was proved to increase the susceptibility to chloride-induced SCC, while grinding perpendicular to the loading direction improved SCC resistance. The knowledge obtained from this work can provide a reference for choosing appropriate grinding parameters when fabricating stainless steel components; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.

Sub lethal mercuric chloride toxicity induced stress related alterations in the epithelial lining of foot of the freshwater mussel Lamellidens marginalis (Lamarck)

Sub lethal (0.2 ppm) mercuric chloride induced stress related histopathological alterations in the epithelial linings of foot (podium) of the edible freshwater mussel Lamellidens marginalis (Lamarck) were studied using histochemical techniques up to 60 days of exposure. The histomorphological changes were manifested only slowly and its intensity was somewhat proportional to the duration of exposure. The immediate response of the exposed mussels was the altered mucous secretion. There was a progressive incorporation of sulphated glycoproteins into the secretory contents of the mucous cells especially in the first half of the experiment. Marked histopathological changes including necrosis, appearance of pyknotic nuclei, sloughing of epithelial cells and appearance of non-tissue spaces, etc., started appearing during the later half of the experiment. The fag end of the experiment, which witnessed prominent histomorphological changes, was accompanied by highly decreased mucous secretion. KEYWORDS: heavy metal toxicity, mercuric chloride, Lamellidens marginalis, freshwater mussel, histopathology.

The regulation of cancer cell invasive behaviour by Chloride Interacellular Channel 3 (CLIC3) and Transglutaminasae 2

A study into the role of secreted CLIC3 in tumour cell invasion. The initiation and progression of cancers is thought to be linked to their relationship with a population of activated fibroblasts, which are associated with tumours. I have used an organotypic approach, in which plugs of collagen I are preconditioned with fibroblastic cells, to characterise the mechanisms through which carcinoma-associated fibroblasts (CAFs) influence the invasive behaviour of tumour cells. I have found that immortalised cancer-associated fibroblasts (iCAFs) support increased invasiveness of cancer cells, and that this is associated with the ability of CAFs to increase the fibrillar collagen content of the extracellular matrix (ECM). To gain mechanistic insight into this phenomenon, an in-depth SILAC-based mass proteomic analysis was conducted, which allowed quantitative comparison of the proteomes of iCAFs and immortalised normal fibroblast (iNFs) controls. Chloride Intracellular Channel Protein 3 (CLIC3) was one of the most significantly upregulated components of the iCAF proteome. Knockdown of CLIC3 in iCAFs reduced the ability of these cells to remodel the ECM and to support tumour cell invasion through organotypic plugs. A series of experiments, including proteomic analysis of cell culture medium that had been preconditioned by iCAFs, indicated that CLIC3 itself was a component of the iCAF secretome that was responsible for the ability of iCAFs to drive tumour cell invasiveness. Moreover, addition of soluble recombinant CLIC3 (rCLIC3) was sufficient to drive the extension of invasive pseudopods in cancer cell lines, and to promote disruption of the basement membrane in a 3D in vitro model of the ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) transition. My investigation into the mechanism through which extracellular CLIC3 drives tumour cell invasiveness led me to focus on the relationship between CLIC3 and the ECM modifying enzyme, transglutaminase-2 (TG2). Through this, I have found that TG2 physically associates with CLIC3 and that TG2 is necessary for CLIC3 to drive tumour cell invasiveness. These data identifying CLIC3 as a key pro-invasive factor, which is secreted by CAFs, provides an unprecedented mechanism through which the stroma may drive cancer progression.

Thermotolerant cyclamen with reduced acrolein and methyl vinyl ketone

Reduced levels of trienoic fatty acids (TAs) in chloroplast membranes induce thermotolerance in several plant species, but the underlying mechanisms remain unclear. TA peroxidation in plant cell membranes generates cytotoxic, TA-derived compounds containing alpha,beta-unsaturated carbonyl groups. The relationship between low TA levels and the amounts of cytotoxic TA-derived compounds was examined using thermotolerant transgenic cyclamen (Cyclamen persicum Mill.) with low TA contents. Changes in the levels of the cytotoxic TA-derived acrolein (ACR), methyl vinyl ketone (MVK), (E)-2-hexenal, 4-hydroxy-2-nonenal, and malondialdehyde were analysed in the leaf tissues of wild-type (WT) and thermotolerant transgenic cyclamen under heat stress. Levels of ACR and MVK in the WT increased in parallel with the occurrence of heat-induced tissue damage, whereas no such changes were observed in the thermotolerant transgenic lines. Furthermore, exogenous ACR and MVK infiltrated into leaves to concentrations similar to those observed in heat-stressed WT leaves caused similar disease symptoms. These results suggest that thermotolerance in transgenic cyclamen depends on reduced production rates of ACR and MVK under heat stress, due to the low level of TAs in these plants.

Regulation of epithelial chloride transport by tyrosine phosphorylation

Background: Chloride transport proteins are involved in a variety of human diseases and thus represent important drug targets. They are regulated in part through the amount present at the plasma membrane and tyrosine phosphorylation has been described as a novel regulator.

[(3-Chlorobenzamido)methyl]triethylammonium chloride

We report the synthesis of [(3-chlorobenzamido)methyl]triethylammonium chloride in a reaction of N-(chloromethyl)-3-chlorobenzamide and triethylamine in dry acetone. The structure of the newly synthesized compound was characterized with1H-NMR,13C-NMR, FTIR and Mass spectroscopy. © 2015 by the authors; licensee MDPI, Basel, Switzerland.