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The hydrate blockage avoidance performance of two anti-agglomerants (coconut amidopropyl dimethylamine, propylene bis (octadecylamidopropyl dimethylammonium chloride)) and their mixtures with polyvinylpyrrolidone (PVP) was tested in a high-pressure rocking cell apparatus. The effect of gas–liquid ratio, water content and PVP concentration were analyzed. A method for evaluating the kinetic inhibiting and anti-agglomerating performance of hydrate inhibitors was established. It was found that coconut amidopropyl dimethylamine had good anti-agglomerating performance at a low gas–liquid ratio (0.5) and various water content levels (20~80%), while propylene bis (octadecylamidopropyl dimethylammonium chloride) had a good anti-agglomerating performance only at a low gas–liquid ratio (0.5) and high water content (80%), and the hydrate volume fraction was up to 23.27% for good anti-agglomeration. When PVP was mixed with the above two anti-agglomerants, it was found that coconut amidopropyl dimethylamine could significantly reduce the kinetic inhibition performance of PVP, while propylene bis (octadecylamidopropyl dimethylammonium chloride) had no significant effect on the kinetic inhibition performance of PVP. The maximum subcooling was 4.4 °C. PVP had no significant effect on the anti-agglomerating performance of the two anti-agglomerants, and the maximum hydrate volume fraction was 18.87% when the agglomeration was well inhibited. [ABSTRACT FROM AUTHOR]

The ammonia-ethanolamine water chemistry used at NPPs with VVER-1200 ensures low rates of corrosion, mass transfer, and growth of corrosion product deposits. The content of corrosion products in the feedwater of the steam generator is less than 1 μg/dm3. This significantly increases the period between flushing the steam generator to remove deposits. However, ethanolamine and ammonia are absorbed by the cation exchange resin in the ion-exchange filters of the secondary circuit purification systems, which leads to the need to regenerate the cation exchange resin and continuously dose reagents to maintain the required pH value in the feedwater. Waste solutions from regeneration containing ethanolamine and large amounts of ammonia must be treated to ensure that the concentrations of these substances do not exceed maximum permissible values when discharged into the environment. To remove ethanolamine and ammonia from regeneration solutions, special installations are created, the operation of which is based on various principles. A pilot plant for cleaning regeneration solutions was manufactured and installed at the Belarusian NPP with VVER-1200. An analysis of the pilot plant's operation showed that it successfully fulfills its function of protecting the aquatic environment but, at the same time, it is forced to release a significant amount of ammonia into the surrounding air. Removing ammonia is energy-consuming, environmentally unsafe, and requires the additional use of chemical reagents. In this regard, the water-chemical regime of the secondary circuit without ammonia is very promising. Possible options could be either switching from ammonia to dimethylamine or using ethanolamine as the only corrective reagent with the replacement of some of the structural materials of the secondary circuit with steels with a high chromium content, which have higher corrosion resistance compared to those currently used. Both options will simplify the wastewater treatment technology and reduce the environmental impact while maintaining the low corrosion rates achieved by using the ammonia–ethanolamine water chemistry. [ABSTRACT FROM AUTHOR]

Soft corals produce a diverse range of natural products with pharmaceutical potential, such as antiproliferative and anti-inflammatory effects. The Alcyoniidae family, particularly the genera Sarcophyton and Sinularia, is rich in bioactive terpenoids. However, despite extensive research, their anti-biofouling properties against the mussel Mytilus galloprovincialis remain underexplored. This study investigates these compounds as potential eco-friendly antifouling agents. A new cembrane-type diterpenoid, 11,12-epoxycembrene A (1), and 15 known compounds were isolated from three soft corals distributed in Okinawa, Japan. The chemical structures of these secondary metabolites were elucidated based on spectroscopic analysis. Moreover, an anti-biofouling assay of potential anti-biofouling agents against M. galloprovincialis was performed and their toxicities were assessed by means of the brine shrimp mortality test. In conclusion, this study identifies new and known bioactive compounds from soft corals, introduces an improved anti-biofouling assay, and highlights the potential of dimethylamine-containing diterpenes as environmentally friendly antifouling agents. [ABSTRACT FROM AUTHOR]

Accurate detection of amines is crucial in various fields, but the coexistence of homologs severely hinders this accuracy. In this study, theoretical simulations and experiments were utilized to investigate the key factors influencing polyaniline adsorption behavior and gas-sensing selectivity towards amine homologs, which were identified as the charge and steric hindrance of the adsorption sites. Then, substituents such as chlorine, ethyl, amino, and methoxy groups were introduced at the ortho position of aniline monomers to modulate the adsorption driving force and resistance and thus regulate their selectivity towards amine homologs. Among them, poly(o-methoxyaniline) responded to only two primary amines, methylamine (MA) and ethylamine (EA), with MA/EA selectivity coefficient greater than 3, nearly achieving MA-specific detection. Poly(2-chloroaniline) exhibited high selectivity for dimethylamine (DMA), significantly enhanced the discrimination of DMA, EA, trimethylamine (TMA), and triethylamine (TEA), increasing the selectivity coefficients of DMA/EA, DMA/TMA, and DMA/TEA from 2.42, 1.05, and 1.03 for PANI to 3.49, 20.21, and 2.10. Furthermore, poly(2-chloroaniline) achieved an error of only 4 % in detecting DMA in a mixture with TMA at the same concentration. The influence of the material's intrinsic conductivity and matching with the response polarity on the suitability and sensitivity was also discussed. • The key factors impacting amine homologs selectivity of PANI were analyzed. • The effect of substituent on PANI selectivity for amine homologs was explored. • Poly(o-methoxyaniline) had nearly achieved specific detection of methylamine. • Poly(2-chloroaniline) significantly enhanced the discrimination of amine homologs. [ABSTRACT FROM AUTHOR]

• Dimethylamine compounds served as NDMA precursors in SR-AOPs with NO 2 − present. • NO 2 − can be oxidized by SO 4 •⁻ to form NO 2 • which dimerized to N 2 O 4. • Nitrosating agent N 2 O 4 played a key role in NDMA formation. • N 2 O 4 directly attacked the DMA moiety in the precursors to form NDMA. • NDMA yield was negatively related to the bond dissociation energy of precursors. Sulfate radical (SO 4 •−) advanced oxidation processes (SR-AOPs) are efficient for degrading a broad spectrum of contaminants. This study demonstrates that the existence of environmentally relevant concentrations of nitrite (NO 2 −) can lead to the formation of N -nitrosodimethylamine (NDMA), a probable human carcinogen, when heat activated peroxydisulfate (heat/PDS) is applied to address contaminants with dimethylamine moieties, such as tetracyclines. NO 2 − effectively competes with tetracyclines for SO 4 •− at a high second-order reaction rate constant of 8.8 × 108 M−1s−1, thus suppressing the degradation. Simultaneously, SO 4 •− reacts with NO 2 − to form the nitrogen dioxide radical (NO 2 •) which rapidly dimerizes to a potent nitrosating agent named dinitrogen tetroxide (N 2 O 4). N 2 O 4 , in turn, attacks the dimethylamine moiety in tetracyclines via nucleophilic substitution, contributing to the degradation of parent compounds and generating an active intermediate that quickly decomposes to NDMA, along with the release of R+ and NO 3 −. The released R+ can be further oxidized by SO 4 •− to form phenolic intermediates which combine with NO 2 • to generate nitrated products. When 5 μM oxytetracycline (OTC) was treated with 0.5 mM PDS in the presence of 20 μM NO 2 − at 60 °C, the highest formation of NDMA was 0.045 μM in 1 h. NDMA formation was also observed for other compounds with dimethylamine moieties, such as methylene blue, phenylurea herbicides, etc., with the molar yield ranging from 0.07 to 3.53 %, negatively related to the R-N bond dissociation energy of the precursors. These findings suggest that NDMA can be commonly generated when SO 4 •− is applied to the degradation of dimethylamine pollutants in wastewater treatment or groundwater remediation where NO 2 − ubiquitously exists, which may pose a serious threat to the aquatic environment. [Display omitted] [ABSTRACT FROM AUTHOR]

Schematic representation of dimethylamine (DMA, (CH3)2NH) in gas-phase. (a) DMA in the α configuration; (b) DMA in the β configuration. The white, grey and blue spheres represent hydrogen, carbon and nitrogen atoms, respectively. [Display omitted] • Adsorptions of dimethylamine in the α-DMA and β-DMA configurations over Pt (001) and Pt (110) surfaces were investigated. • DFT: PBE, RPBE, revPBE, vdW-DF, vdW-DF2, BEEF-vdW and optPBE-vdW studies have been developed. • vdW functionals give adsorption energies which are higher than the standard DFT. • Projected density of states curves around N, C, and Pt have been discussed. The adsorptions of dimethylamine on Pt(001) and Pt(110) surfaces have been studied with the standard DFT and DFT + vdW methods using the periodic slab models. We determined adsorption energies and structural parameters of the dimethylamine for two adsorption configurations, with the hydrogen of the N H group pointing toward the surface or toward the vacuum region. The analysis of the adsorption energies shows that dimethylamine stabilizes strongly on the Pt(001) surface using DFT + PBE at the top site. However, the inclusion of vdW forces results in the increase of adsorption energy compared to values obtained from standard DFT, and there is chemisorption between dimethylamine and Pt surfaces. The adsorption energy of dimethylamine on the Pt(100) surface is found to be higher than that on the Pt(110) surface. Upon adsorption, changes in the structural parameters of dimethylamine were observed relative to the gas phase. Projected density of states (PDOSs) was also used to analyze the interaction between dimethylamine and Pt surfaces. Finally, our results demonstrate that the nature of standard and vdW functionals would provide significant support to experimentalists to obtain an accurate description of the adsorption of dimythelamine on Pt(001) and Pt(110) surfaces. [ABSTRACT FROM AUTHOR]

This study demonstrated the effects of the sludge type and inoculation method on the N,N-dimethylformamide degradation pathway and associated microbial communities. The sludge type is critical for DMF metabolism, with acclimatized aerobic sludge having a significant advantage in terms of DMF metabolism performance, whereas acclimatized anaerobic sludge has a reduced DMF metabolism capacity. Metagenomic revealed increased abundances of Methanosarcina , Pelomona and Xanthobacter in the adapted anaerobic sludge, suggesting that anaerobic sludge can utilize the methyl products produced by DMF metabolism for growth. Adapted aerobic sludge had high Mycobacterium abundance, significantly boosting DMF hydrolysis. In addition, a large number of dmfA2 genes were found in aerobic sludge, more so in acclimatized sludge, indicating stronger DMF metabolism. Conversely, acclimatized anaerobic sludge showed lower abundance of dmd-tmd and mauA/B , qhpA genes, implying long-term DMF toxicity reduced anaerobic microbial activity. Metaproteomic analysis showed that Methanosarcina and Methanomethylovorans enzymes in anaerobic sludge metabolized dimethylamine and methylamine to methane, aiding DMF degradation. In the aerobic sludge, aminohydrolase proteins, which hydrolyze DMF, were significantly upregulated. These findings provide insights into DMF wastewater treatment. [Display omitted] ● Aerobic sludge adapted to the environment excels in DMF metabolism. ● DMF toxicity inhibits anaerobic sludge, resulting in poorer DMF treatment capacity ● Adapted aerobic sludge shows high dmfA2 levels, crucial for DMF metabolism ● Methanosarcina and Methanomethylovorans key for DMF metabolism in anaerobic sludge [ABSTRACT FROM AUTHOR]