Mechanisms and Critical Technologies of Transport Inhibitor Agent (TIA) throughout C-S-H Nano-Channels

The critical issue of the durability of marine concrete lies in the continuous penetration and rapid enrichment of corrosive ions. Here a new ion transfer inhibitor, as TIA, with calcium silicate hydrate (C-S-H) interfacial affinity and hydrophobicity is proposed through insights from molecular dynamics into the percolation behavior of the ion solution in C-S-H nano-channels and combined with molecular design concepts. One side of the TIA can be adsorbed on the surface of the cement matrix and can form clusters of corrosive ions to block the gel pores so as to resist the ion solution percolation process. Its other side is structured as a hydrophobic carbon chain, similar to a door hinge, which can stick to the matrix surface smoothly before the erosion solution is percolated. It can then change into a perpendicular chain shape to reduce the percolation channel’s diameter and thereby inhibit the percolation when ions meet the inhibitor. Therefore, once the erosion solution contacts TIA, it can quickly chelate with calcium ions and erosion ions at the interface to form clusters and compact pores. In addition, the water absorption, chloride migration coefficient, and chloride content of concrete samples decreased significantly after adding TIA, proving that TIA can effectively enhance the durability of cement-based materials. The structure–activity relationship of ion transfer that is proposed can provide new ideas for solving the critical problems of durability of cement-based materials and polymer molecular design.

Features of the crystallization of AlCl3·6H2O in the system AlCl3 – MeClx – HCl – H2O

A laboratory setup has been developed to study the regularities of crystallization of aluminium chloride hexahydrate from hydrochloric acid solutions. The influence of the AlCl3 content in the initial solution, the consumption of gaseous HCl, and the behavior of impurities on the crystallization of AlCl3·6H2O from aluminium chloride solutions of leaching cinder obtained as a result of chlorinating ash burning from thermal power plants in Kazakhstan have been studied. The behavior of impurity metals in the process of crystallization of aluminium chloride solution has been studied, and their distribution between the products of the crystallization process has been established. It is shown that aluminium chloride content in the solution decreases with an increase in the consumption of hydrochloric acid. It was found that under the conditions of crystallization of AlCl3·6H2O, all impurities, except for barium, pass by 98% into the mother liquor. To reduce barium and other impurities in the obtained crystals of AlCl3·6H2O, it is proposed to carry out multiple washing of the crystals with hydrochloric acid (32% HCl). It has been shown that a decrease in the acidity of the washing solution from pH = 10 to pH = 5.5 ensures the isolation of ACH crystals with a minimum content of impurity metals, ppm: 3-5 Ca; 3-6 Fe; 1-3 Mg; 0.1-0.5 Ti; 1-3 Na; 20-30 P2O5. The moisture content of the obtained crystals is 4-5%; the particle size is 400-900 microns. As a result of mathematical processing, regression equations were constructed that adequately predict aluminium chloride content in the solution and its extraction into crystalline hydrate, depending on the consumption of hydrochloric acid. The optimal parameters of the crystallization process have been established: Т = 60 ºС, HCl concentration in the solution - 26-30%, HCl gas consumption = 0.5 l/min, duration 1 hour.

The enzymatic method for the quantitative determination of benzalkonium chloride in the antiseptic solution “CUTASEPT® F”

Aim. To develop an alternative method for the quantitative determination of the benzalkonium chloride content as an active pharmaceutical ingredient in the disinfectant solution “CUTASEPT® F”.Materials and methods. The method is based on the ability of benzalkonium chloride to inhibit the enzymatic hydrolysis of acetylcholine by acetylcholinesterase. The reaction rate is assessed by the non-hydrolyzed acetylcholine residue, which is determined by the amount of peracetic acid produced during the interaction with the excess of the hydrogen peroxide solution. The indicator reaction is the interaction of p-phenetidine with peracetic acid that leads to the formation of 4,4’-azoxyphenetole with λmax = 358 nm (log10 ε = 4.2).Results and discussion. As a result of the research conducted the linear dependence of the degree of inhibition of the enzymatic hydrolysis of acetylcholine (U, %) on the concentration of benzalkonium chloride was determined in the concentration range of (0.5 – 7.0) × 10–6 mol L-1 with the correlation coefficient of 0.999. The limit of quantitation was 1.9 × 10–6 mol L-1.Conclusions. As a result of the research conducted the kinetic enzymatic method for the quantitative determination of benzalkonium chloride has been developed by its inhibitory effect in the biochemical reaction of acetylcholine hydrolysis. This method is fast, cheap and easy to perform, does not require expensive equipment, and available for use in the field.

Impact of leaching on chloride ingress profiles in concrete

To investigate the effect of leaching on chloride ingress profiles in concrete and mortar, we exposed concrete and mortar specimens for 90 and 180 days to two different exposure solutions: 3% NaCl, and 3% NaCl with KOH added to limit leaching. The solutions were replaced weekly. After exposure, we determined total chloride profiles to investigate the chloride ingress, and portlandite profiles to assess the extent of leaching. The results showed that leaching during exposure greatly affects the chloride ingress profiles in mortar and concrete. We found that leaching leads to considerably higher maximum total chloride content and deeper chloride penetration into the concrete than in the specimens where leaching was limited. We recommend therefore that leaching should be taken into account in standard laboratory testing and that more mechanistic service life models should be used to take into account the impact of leaching.

Evaluation o Different Starter Cultures in Dry Salami

The main objective of this paper is to evaluate the influence of starter culture (fast and slow) on the technological process and the quality of dried salami. For each finished product were made the same analyzes: the fat content, protein, sodium chloride content, nitrite and moisture content. Following the experimental research, it was found that for slow culture, higher values were obtained in the case of protein content (15.2%) and salt content (2.98%). In the case of fast culture, higher values were obtained for the following properties: moisture (38.32%), fat (29.57%) and nitrites (5.42 ppm). The evolution of the pH every 24 hours in the first 7 days was also monitored, and it can be notice that after 6 days the pH reached the same value for both cultures (6.9) although initially in the case of slow starter cultures the pH was slightly higher.

Using of aluminium slags and products of their pro‑cessing in metallurgical production

The work contains the results of the analysis of technical literature and author’s research on the use of aluminium slags and products of their processing in metallurgical production. It has been shown that the bulk of reagents derived from secondary aluminum production wastes (APWs) are used with increased sodium and potassium chloride. This creates some inconvenience for out‑of‑furnace steel treatment due to the increased chloride content in the working area. It is proposed for steel processing to use APWs formed during flux‑free melting or dump aluminium slags. This allows to reduce the content of salt fluxes residues to 1.0–1.5 % and to improve working conditions at ladle furnaces when liquefying refining slags.

ROLE OF VENTILATION, CALCIUM AND BORON ON SHOOT TIP NECROSIS AND HYPERHYDRICITY REDUCTION OF IN VITRO ROORSTOOCKS OF PISTACIO ‘BADAMI’ ȘI ‘UCB1’

Shoot tip necrosis (STN) is one of the main physiological disorders in the micropropagation of pistachios. In the current study, the effects of CaNO3.4H2O at 196 mg/L and 291 mg/L, H3BO3 at 196 mg/L and 291 mg/L, and CaCl2.2H2O at 2,980 mg/L on STN and hyperhydricity reduction of Pistacia vera L., ‘Badami’ and ‘UCB1’ rootstocks were assessed, compared to the MS standard medium containing 3% sucrose, 0.7% agar supplemented with benzyladenine (BA) (1.5 mg/L), indole butyric acid (IBA) (0.1 mg/L). For ventilation parameter, filter container vessels with a 50-µm microporous polypropylene membrane (Pardis®) were used. Based on the results, an increase in calcium chloride content of the MS standard medium prevented hyperhydricity in the UCB1 rootstock, whereas it increased STN, yellow leaves, decreasing the multiplication of shoots in the ‘Badami’ rootstock. The results also showed that increasing boric acid from 196 mg/L up to 291 mg/L decreased STN in the UCB1 rootstock and increased this disorder by 37% in the ‘Badami’ rootstock. Ventilation showed no significantly reducing effect on the percentage of STN in the regenerated shoots of the ‘Badami’ rootstock, whilst it decreased the STN of the ‘UCB1’ rootstock to the lowest percentage. For the ‘Badami’ rootstock, CaNO3.4H2O at 196 mg/L led to the highest proliferation rate, shoot height, shoot diameter, and leaf number, but for the ‘UCB1’ rootstock, an increase in the concentration of CaNO3.4H2O up to 291 mg/L under ventilated conditions resulted in an increase in proliferation, shoot height, and shoot diameter.

Quantitative Non-Linear Effect of High Ambient Temperature on Chloride Threshold Value for Steel Reinforcement Corrosion in Concrete under Extreme Boundary Conditions

This paper investigates the effect of high ambient temperatures on the chloride threshold value for reinforced concrete (RC) structures. Two commonly available carbon steel rebars were investigated under four different exposure temperatures (20 °C (68 °F), 35 °C (95 °F), 50 °C (122 °F), and 65 °C (149 °C)) using environmental chambers at a constant relative humidity of 80%. For each temperature, six different levels of added chloride ions (0.00%, 0.15%, 0.30%, 0.60%, 0.90%, and 1.20% by weight of cement) were used to study the chloride threshold value. Corrosion initiation was detected by monitoring the corrosion potential and corrosion rate using electrochemical techniques. The water-soluble (free) and acid-soluble (total) chlorides were determined using potentiometric titration according to the relevant ASTM standards. The threshold chloride content for each exposure temperature was determined by analyzing the corrosion potential, corrosion rate, and chloride content of each specimen. The results showed that the chloride threshold values were significantly temperature-dependent. At temperatures of 20 °C (68 °F) and 35 °C (95 °F), the chloride threshold value (expressed as free chlorides) was approximately 0.95% by weight of cement. However, as the temperature increased to 50 °C (122 °F), the chloride threshold decreased significantly to approximately 0.70% by weight of cement. The reduction in the chloride threshold value became more dramatic at an exposure temperature of 65 °C (149 °F), decreasing to approximately 0.25% by weight of cement. The trends were similar for the rebars from the two sources, indicating that the rebar source had little influence on the chloride threshold value.

Physicochemical and microbiological evaluation of surface water quality of aquaculture ponds Located in Savar, Dhaka, Bangladesh

Aquaculture is one of the most vital sectors in Bangladesh as it exhibits a major role in nutrition, livelihoods and foreign exchange incomes/earnings every year. However, due to chemical impurities, infectious diseases caused by microorganisms, heavy metal accumulation, and aquaculture in Bangladesh is gradually declining and posing serious health risks. In Savar, which is one of the major industrial zones in Bangladesh, all industrial sewage and wastes severely deteriorate the water quality of the ponds, rivers, lakes and various waterways that are involved in aquaculture/fish culture. Hence, to determine the water quality by assessing different physicochemical and microbiological parameters, water samples were collected from five selected ponds located in Atomic Energy Research Establishment premises, Savar, Dhaka and analyzed according to the standard procedures. The obtained values of temperature, pH, Salinity, TDS, TA, EC, TH, Chloride content, Free CO2, DO, Nitrate and Sulfate were compared with the recommended values of Bangladesh and WHO standard for suitable water quality. Most of the physicochemical parameters exceeded the Standard value. Total Viable Count, Total Coliform and Fecal Coliform Count were also found to be higher than the standard value of WHO indicating fecal contamination of the pond water. Some fish pathogens were also isolated from the ponds. Water quality index (WQI) was calculated for five sampling sites to determine the level of pollution. It was observed that the water quality of the all the ponds reached to critical point of pollution. It is therefore, a high time to take initiatives to save the ponds that are involved in aquaculture from further pollution. The results revealed that the pond waters of five different sites were excessively polluted and unsuitable for fish culture.

Combined Freeze-Thaw and Chloride Attack Resistance of Concrete Made with Recycled Brick-Concrete Aggregate

The objective of this study was to investigate the physico-chemical properties of concrete made with recycled brick-concrete aggregate, which was the mixture from waste concrete and waste clay brick in a 7:3 ratio. Specifically, this paper investigated the mechanical properties, freeze-thaw resistance, and distribution of water-soluble chloride ions of concrete containing RBCA and fly ash (FA) against combined freeze-thaw and sodium chloride attack. Concrete containing RBCA replacement of natural coarse aggregate and fly ash replacement of Portland cement was subjected to 45 freeze-thaw cycles containing sodium chloride solution. It was discovered that the mechanical properties and freeze-thaw resistance to sodium chloride attack gradually decreased with increasing RBCA content. At the same time, a replacement level of 15% FA by weight resulted in significant improvements in compressive strength and resistance to combined freeze-thaw and chloride attack. Furthermore, using a replacement of 30% FA by weight markedly improved the resistance to chloride ion penetration of concrete due to the lowest water-soluble chloride content.