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Some studies have reported the removal of As (As) and fluoride (F - ) using different sacrificial anodes; however, they have been tested with a synthetic solution in a batch system without hydrated silica (SiO 2 ) interaction. Due to the above, concurrent removal of As, F - , and SiO 2 from natural deep well water was evaluated (initial concentration: 35.5 μg L -1 As, 1.1 mg L -1 F - , 147 mg L -1 SiO 2 , pH 8.6, and conductivity 1024 μS cm -1 ), by electrocoagulation (EC) process in continuous mode comparing three different configurations of sacrificial anodes (Al, Fe, and Al-Fe). EC was performed in a new reactor equipped with a small flow distributor and turbulence promoter at the entrance of the first channel to homogenize the flow. The best removal was found at j = 5 mA cm -2 and u = 1.3 cm s -1 , obtaining arsenic residual concentrations (C As ) of 1.33, 0.45, and 0.77 μg L -1 , fluoride residual concentration ( [Formula: see text] ) of 0.221, 0.495, and 0.622 mg L -1 , and hydrated silica residual concentration ( [Formula: see text] ) of 21, 34, and 56 mg L -1 , with costs of approximately 0.304, 0.198, and 0.228 USD m -3 for the Al, Fe and Al-Fe anodes, respectively. Al anode outperforms Fe and Al-Fe anodes in concurrently removing As, F - and SiO 2 . The residual concentrations of As and F - complied with the recommendations of the World Health Organization (WHO) (As < 10 μg L -1 and F -  < 1 mg L -1 ). The spectroscopic analyses of the Al, Fe, and Al-Fe aggregates showed the formation of aluminosilicates, iron oxyhydroxides and oxides, and calcium and sodium silicates involved in removing As, F - , and SiO 2 . It is concluded that Al would serve as the most suitable sacrificial anode., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This paper concerns simultaneous removal of fluoride and hydrated silica from groundwater (4.08 mg L -1 fluoride, 90 mg L -1 hydrated silica, 50 mg L -1 sulfate, 0.23 mg L -1 phosphate, pH 7.38 and 450 μS cm -1 conductivity) by electrocoagulation (EC), using an up-flow EC reactor, with a six-cell stack in a serpentine array, opened at the top of the cell to favor gas release. Aluminum plates were used as sacrificial electrodes. The effect of current density (4 ≤ j ≤ 7 mA cm -2 ) and mean linear flow rate (1.2 ≤ u ≤ 4.8 cm s -1 ), applied to the EC reactor, on the elimination of fluoride and hydrated silica was analyzed. The removal of fluoride followed the WHO guideline (<1.5 mg L -1 ), while the hydrated silica was abated at 7 mA cm -2 and 1.2 cm s -1 , with energy consumption of 2.48 kWh m -3 and an overall operational cost of 0.441 USD m -3 . Spectroscopic analyses of the flocs by XRD, XRF-EDS, SEM-EDS, and FTIR indicated that hydrated silica reacted with the coagulant forming aluminosilicates, and fluoride replaced a hydroxide from aluminum aggregates, while sulfates and phosphates were removed by adsorption process onto the flocs. The well-engineered EC reactor allowed the simultaneous removal of fluoride and hydrated silica., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Mitochondrial aldehyde dehydrogenase (ALDH2) has been proposed as a key enzyme in cardioprotection during ischemia-reperfusion processes. This proposal led to the search for activators of ALDH2 with the aim to develop cardioprotective drugs. Alda-1 was the first activator of ALDH2 identified and its cardioprotective effect has been extensively proven in vivo; however, the mechanism of activation is not fully understood. A crystallographic study showed that Alda-1 binds to the entrance of the aldehyde-binding site; therefore, Alda-1 should in essence be an inhibitor. In the present study, kinetic experiments were performed to characterize the effect of Alda-1 on the properties of ALDH2 (kinetic parameters, determination of the rate-limiting step, reactivity of the catalytic cysteine) and on the kinetic mechanism (type of kinetics, sequence of substrates entering, and products release). The results showed that Alda-1 dramatically modifies the properties of ALDH2, the K m for NAD + decreased by 2.4-fold, and the catalytic efficiency increased 4.4-fold; however, the K m for the aldehyde increased 8.6-fold, thus, diminishing the catalytic efficiency. The alterations in these parameters resulted in a complex behavior, where Alda-1 acts as inhibitor at low concentrations of aldehyde and as an activator at high concentrations. Additionally, the binding of Alda-1 to ALDH2 made the deacylation less limiting and diminished the pK a of the catalytic cysteine. Finally, NADH inhibition patterns indicated that Alda-1 induced a change in the sequence of substrates entry and products release, in agreement with the proposal of both substrates entering ALDH2 by the NAD + entrance site., (© 2016 Federation of European Biochemical Societies.)

The modulation of aldehyde dehydrogenase (ALDH) activity has been suggested as a promising option for the prevention or treatment of many diseases. To date, only few activating compounds of ALDHs have been described. In this regard, N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide has been used to protect the heart against ischemia/reperfusion damage. In the search for new modulating ALDH molecules, the binding capability of different compounds to the active site of human aldehyde dehydrogenase class 1A1 (ALDH1A1) was analyzed by molecular docking, and their ability to modulate the activity of the enzyme was tested. Surprisingly, tamoxifen, an estrogen receptor antagonist used for breast cancer treatment, increased the activity and decreased the Km for NAD(+) by about twofold in ALDH1A1. No drug effect on human ALDH2 or ALDH3A1 was attained, showing that tamoxifen was specific for ALDH1A1. Protection against thermal denaturation and competition with daidzin suggested that tamoxifen binds to the aldehyde site of ALDH1A1, resembling the interaction of N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide with ALDH2. Further kinetic analysis indicated that tamoxifen activation may be related to an increase in the Kd for NADH, favoring a more rapid release of the coenzyme, which is the rate-limiting step of the reaction for this isozyme. Therefore, tamoxifen might improve the antioxidant response, which is compromised in some diseases., (© 2014 Wiley Periodicals, Inc.)