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Ammonia and amines play critical roles in secondary aerosol formation, especially in urban environments. However, fast measurements of ammonia and amines in the atmosphere are very scarce. We measured ammonia and amines with a chemical ionization mass spectrometer (CIMS) at the urban center in Houston, Texas, the fourth most populated urban site in the United States, during October 2022. Ammonia concentrations were on average four parts per billion by volume (ppbv), while the concentration of an individual amine ranged from several parts per trillion by volume (pptv) to hundreds of pptv. These reduced nitrogen compounds were more abundant during weekdays than on weekends and correlated with measured CO concentrations, implying they were mostly emitted from pollutant sources. Both ammonia and amines showed a distinct diurnal cycle, with higher concentrations in the warmer afternoon, indicating dominant gas-to-particle conversion processes taking place with the changing ambient temperatures. Studies have shown that dimethylamine is critical for new particle formation (NPF) in the polluted boundary layer, but currently there are no amine emission inventories in global climate models (as opposed to ammonia). Our observations made in the very polluted area of Houston, as well as a less polluted site (Kent, Ohio) from our previous study (You et al., 2014), indicate there is a consistent ratio of dimethylamine over ammonia at these two sites. Thus, our observations can provide a relatively constrained proxy of dimethylamine using 0.1 % ammonia concentrations at polluted sites in the United States to model NPF processes. [ABSTRACT FROM AUTHOR]

Disinfection by-products (DBPs) such as chloroacetic acids (CAAs) and N-Nitrosodimethylamine (NDMA) are prevalent pollutants in surface waters, particularly with the increasing use of chlorine-based disinfectants. The entry of these DBPs into water bodies may increase accordingly, posing ecological risks to aquatic life. To assess the toxic effects of CAAs and NDMA on submerged macrophytes, Vallisneria natans was exposed to different concentrations of CAAs (1.0, 10.0, and 100.0 μg L−1) and NDMA (0.1, 1.0, and 10.0 μg L−1). A RI value of <1 indicates that simultaneous exposure to CAAs and NDMA can produce an antagonistic effect. Both CAAs and NDMA adversely affect the photosynthetic system of plants. In the NDMA treatment group, chlorophyll a content decreases with increasing concentration, accounting for 96.03%, 60.80%, and 58.67% of the CT group, respectively. Additionally, it effectively triggers the plant's antioxidant response, with significant increases in SOD, POD, and GSH levels. Among these, the combined treatment group AN2 (10 + 1 μg L−1) showed the most significant change in SOD activity, reaching 3.57 times that of the CT group. Ultrastructural changes also revealed stress responses in leaf cells and damage to organelles. Furthermore, metabolomics provided insights into the metabolic responses induced by CAAs or NDMA in V. natans leaves, where the composition and metabolism of lipids, fatty acids, cofactors and vitamins, amino acids, nucleotides, and some antioxidants were regulated, affecting plant growth. This study provides preliminary information for the ecological risk assessment of submerged plants by complex contamination with the disinfection by-products CAA and NDMA. [ABSTRACT FROM AUTHOR]

The anti-diabetic drug metformin is one of the most widely prescribed medicines in the world. Together with its degradation product guanylurea, it is a major pharmaceutical pollutant in wastewater treatment plants and surface waters. An operon comprising two genes of the ureohydrolase family in Pseudomonas and Aminobacter species has recently been implicated in metformin degradation. However, the corresponding proteins have not been characterized. Here we show that these genes encode a Ni2+-dependent enzyme that efficiently and specifically hydrolyzes metformin to guanylurea and dimethylamine. The active enzyme is a heteromeric complex of α- and β- subunits in which only the α-subunits contain the conserved His and Asp residues for the coordination of two Ni2+ ions in the active site. A crystal structure of metformin hydrolase reveals an α2β4 stoichiometry of the hexameric complex, which is unprecedented in the ureohydrolase family. By studying a closely related but more widely distributed enzyme, we find that the putative predecessor specifically hydrolyzes dimethylguanidine instead of metformin. Our findings establish the molecular basis for metformin hydrolysis to guanylurea as the primary pathway for metformin biodegradation and provide insight into the recent evolution of ureohydrolase family proteins in response to an anthropogenic compound. The diabetes drug metformin and its degradation product guanylurea are major pharmaceutical contaminants in waste and surface water. Here, a Ni2+-dependent enzyme that hydrolysed metformin to guanylurea and its evolutionary predecessor are presented. [ABSTRACT FROM AUTHOR]

Three structurally diverse 5‐phenyltetrazolato (Tz) Ti, Zr, and Ta complexes, namely, (C2H8N)[Ti2(C7H5N4)5(C2H6N)4]·1.45C6H6 or (Me2NH2)[Ti2(NMe2)4(2,3‐μ‐Tz)3(2‐η1‐Tz)2]·1.45C6H6, (1·1.45C6H6), [Zr2(C7H5N4)6(C2H6N)2(C2H7N)2]·1.12C6H6·0.382CH2Cl2 or [Zr2(Me2NH)2(NMe2)2(2,3‐μ‐Tz)3(2‐η1‐Tz)2(1,2‐η2‐Tz)]·1.12C6H6·0.38CH2Cl2 (2·1.12C6H6·0.38CH2Cl2), and (C2H8N)2[Ta2(C7H5N4)8(C2H6N)2O]·0.25C7H8 or (Me2NH2)2[Ta2(NMe2)2(2,3‐μ‐Tz)2(2‐η1‐Tz)6O]·0.25C7H8 (3·0.25C7H8), where TzH is 5‐phenyl‐1H‐tetrazole, have been synthesized and structurally characterized. All three complexes are dinuclear; the Ti center in 1 is six‐coordinate, whereas the Zr and Ta atoms in 2 and 3 are seven‐coordinate. The coordination environments of the Ti centers in 1 are similar, and so are the ligations of the Ta centers in 3. In contrast, the two Zr centers in 2 bear a different number of ligands, one of which is a bidentate η2‐5‐phenyltetrazolato ligand that has not been observed previously for d‐block elements. The dimethylamido ligand, present in the starting materials, remained unchanged, or was converted to dimethylamine and dimethylammonium during the synthesis. Dimethylamine coordinates as a neutral ligand, whereas dimethylammonium is retained as a hydrogen‐bonded entity bridging Tz ligands. [ABSTRACT FROM AUTHOR]

Presented herein is a switchable synthesis of naphthalenone spiroindanediones or 4‐acyl‐1‐naphthols via condition‐controlled divergent cascade reactions of aryl enaminones with diazoindanediones. When the reaction was carried out in the presence of an oxidative additive, naphthalenone spiroindanedione was formed through C(sp2)−H alkylation followed by simultaneous spiroannulation and elimination of dimethylamine. When the reaction was carried out in the presence of an acid additive, on the other hand, 4‐acyl‐1‐naphthol was formed through ring opening of the spiroindanedione moiety attacked by the in situ released dimethylamine. In addition, the reactions are suitable for gram‐scale applications and compatible with a variety of substrates. Moreover, the naphthol products allow structural elaborations and hybridization with a drug, thus further enhancing the value of this developed method. [ABSTRACT FROM AUTHOR]

N-nitrosodimethylamine (NDMA) is a potentially carcinogenic byproduct of disinfecting drinking water. NDMA has been classified as a Group B2 carcinogen by the U.S. Environmental Protection Agency (EPA). The pathway of NDMA formation during chlorination has been proposed; however, it is still necessary to identify the most influential factor in this process. The objective of this study was to compare the factors and conditions that lead to the formation of NDMA from dimethylamine (DMA) to identify the primary factors responsible for the occurrence of this compound in drinking water. The study examined the formation of NDMA in chlorinated water under seven different conditions, considering three factors (NO2−, NO3−, and NH3). All factors were maintained at their actual concentrations in tap or surface water. The highest levels of NDMA were observed at pH 6 when NO3− and NH3 were present, with concentrations of 22.7 ng/L and 9.79 ng/L, respectively. At pH 6, NDMA levels were observed to be 22 times higher than at pH 8. Chlorine alone was not sufficient to convert DMA to NDMA within a short period of time, specifically at least 5 h, in the absence of other factors. The concentration of NDMA increased to 41.6 ng/L in the presence of NH3. After 16 h, the presence of NO3− led to a gradual increase in NDMA levels to 19.0 ng/L. However, no further increase was observed at this point. The findings suggest that NO3− and NH3 are important factors of NDMA in chlorinated drinking water. Although previous mechanisms have not given much attention to these factors, they are expected to play a significant role in the formation of nitrosamines in both natural water and drinking water. Controlling the factors or pH appeared to be crucial for managing NDMA formation, and further research on reducing N-nitrosamines is necessary. [ABSTRACT FROM AUTHOR]

Co–xCaO/g-C3N4 catalysts were prepared using incipient wetness impregnation method and applied in isophthalonitrile hydrogenation to M-xylenedimethylamine. The characterization results and experimental data indicate that introduction of CaO crates large number of basic sites and leads to electron rich Co, hence inhibits the side reaction and improves the selectivity to M-xylenedimethylamine. 10Co–2CaO/g-C3N4 gives the best catalytic performance of 100% conversion of isophthalonitrile and 95% selectivity to M-xylenedimethylamine without any alkaline additives in the reacion system. This work is valuable for the design and preparation of hydrogenation catalysts with rich basic sites and provides a green process for nitrile compounds to amine. [ABSTRACT FROM AUTHOR]

2D organic–inorganic hybrid perovskites (OIHPs) are regarded as potential candidates for the advancement of multifunctional phase‐transition materials due to their ability to integrate flexible functionality and superior electronic features from both organic and inorganic components. However, the development of 2D OIHPs with dielectric switches and weak light detection capability that are crucial for high‐resolution sensing and imaging, remains challenge. Herein, a novel 2D OIHP BDADMAPb2Br7 (1, BDA = 1,4‐butanediamine and DMA = dimethylamine) is presented, featuring a 2D Dion–Jacobson (DJ) bilayered structure incorporated with secondary amine. Upon heating and cooling cycles, 1 demonstrates long‐term reversible dielectric switching properties at 328 K. Meanwhile, 1 also shows compelling semiconductor characteristics, including a low dark current of 2.87 × 10−11 A (10 V), a large switching ratio of 4 × 103, and a high detectivity of 1.3 × 1012 Jones. In addition, the photodetector based on 1 exhibits an excellent weak light detection ability of 340 nW cm−2 at 405 nm. Such a 2D OIHP demonstrates a novel platform for creating multifunctional materials and significantly promotes the development of integrated devices. [ABSTRACT FROM AUTHOR]

One effective option to minimize N-nitrosodimethylamine (NDMA) in finished drinking water is to identify and control its precursors. However, previous works to identify significant precursors use formation potential (FP) tests using high doses to assure the maximum NDMA formation rather than the NDMA formation in finished waters. In this study, we applied characteristic low treatment doses of ozone (O3)-to-dissolved organic carbon (DOC) of target compounds of 0.8 mg/mg and NH2Cl of 2.5 ± 0.2 mg Cl2/L to evaluate the NDMAFP yields of organic compounds bearing N,N-dimethylamine (DMA) and N,N-dimethylhydrazine (DMH) during preozonation and post-chloramination. The results in pH-buffered Milli-Q water showed a significant decrease from ≤ 52% to non-detectable levels in the O3-NDMAFP yields of O3-reactive precursors (i.e., DMH-like compounds) after preozonation and post-chloramination. Similarly, a significant decrease from 0.5 to 12% to nonquantifiable levels was observed for the NH2Cl-NDMAFP yields of NH2Cl-reactive precursors; however, the NH2Cl-NDMAFP yields of N,N-dimethylbenzylamine (DMBzA)-like compounds only decreased from ~ 110 to ≤ 43%, suggesting that these compounds could contribute to NH2Cl-NDMAFPs even after preozonation. The effect of the matrix in sewage-effluent and lake water samples varied and was specific for precursors; for example, the O3-NDMAFP yield of 1,1,1′,1′-tetramethyl-4,4′-(methylene-di-p-phenylene) disemicarbazide (TMDS), an important O3-reactive NDMA precursor, did not significantly decrease when tested in sewage-effluent samples. Based on the previous occurrence concentration of TMDS in sewage samples, we estimated an NDMAFP of ~ 315 ng/L. This estimate exceeds the guidance concentrations of NDMA (3–100 ng/L), highlighting the importance of TMDS and its related compounds for NDMA formation. [ABSTRACT FROM AUTHOR]

Next-generation risk assessment relies on mechanistic data from new approach methods, including transcriptome data. Various technologies, such as high-throughput targeted sequencing methods and microarray technologies based on hybridization with complementary probes, are used to determine differentially expressed genes (DEGs). The integration of data from different technologies requires a good understanding of the differences arising from the use of various technologies. To better understand the differences between the TempO-Seq platform and Affymetrix chip technology, whole-genome data for the volatile compound dimethylamine were compared. Selected DEGs were also confirmed using RTqPCR validation. Although the overlap of DEGs between TempO-Seq and Affymetrix was no higher than 37%, a comparison of the gene regulation in terms of log2fold changes revealed a very high concordance. RTqPCR confirmed the majority of DEGs from either platform in the examined dataset. Only a few conflicts were found (11%), while 22% were not confirmed, and 3% were not detected. Despite the observed differences between the two platforms, both can be validated using RTqPCR. Here we highlight some of the differences between the two platforms and discuss their applications in toxicology. [ABSTRACT FROM AUTHOR]

N-nitrosodimethylamine is a carcinogenic agent accidentally found in ranitidine formulations. For the products to be safe for human use and quality control test, the estimation of N-nitrosodimethylamine in ranitidine is significantly important. The goal of this study was to use liquid chromatography with tandem mass spectrometric technique for the development and validation of N-nitrosodimethylamine in ranitidine drug and tablets. The proposed approach was utilized to estimate routine analysis of N-nitrosodimethylamine in ranitidine drug and tablets. The injection volume 20 µl and wavelength 254 nm was selected for N-nitrosodimethylamine and ranitidine quantification. Binary mobile phase in a gradient mode was used for the study. The mixture of solvent A (0.1 % formic acid in water) and solvent B (0.1 % formic acid in methanol) was used as the mobile phase. The flow rate of 0.6 ml/min in gradient mode with complete run time of 14 min was used for the analysis. For N-nitrosodimethylamine analysis multiple reaction monitoring transitions were 75.80/44.20 (quantitative analysis) and 75.80/58.20 (qualitative analysis). N-nitrosodimethylamine retention time was found at 1.25 min. For N-nitrosodimethylamine, the limit of detection was 0.3 ng/ml and limit of quantitation was found to be 1 ng/ml. The linearity range for N-nitrosodimethylamine was decided as 1, 2, 5, 10, 20 and 50 ng/ml from its intensity response. The regression value observed in a linearity graph was 0.9999. The method was specific (no interference of any peak), validated for its accuracy (98.07 to 100.22±1.7565), precision (98.64 to 99.44±0.9083) and robustness (does not effect on developed method by slight change in flow rate and column temperature). In the validation investigation, the quality control levels lower quality control (4 ng/ml), middle quality control (8 ng/ml) and higher quality control (40 ng/ml) were used. Newly developed and validated method for N-nitrosodimethylamine in ranitidine by liquid chromatography with tandem mass spectrometry was accurate, precise and sensitive. The developed method was further used for routine analysis of N-nitrosodimethylamine in ranitidine drug and tablets. [ABSTRACT FROM AUTHOR]

Selective synthesis of primary amines from nitriles is challenging in synthetic chemistry due to the possible en‐route generation of various amines and imines. Herein, we report a practical and operationally simple MOtBu‐mediated (M=Na, K) transfer hydrogenation of nitriles to the corresponding primary amines with a relatively unexplored sacrificial hydrogen source (dimethylamine borane). The strategy encompasses a broad substrate scope under transition metal‐free conditions and does not require any solvent. The mechanistic investigation was performed with the aid of control experiments and spectroscopic studies. The GC analysis of the reaction mixture exhibited the evolution of the H2 gas. Additionally, detailed computational calculations were undertaken to shed light on the possible intermediates and transition states involved during the present protocol. [ABSTRACT FROM AUTHOR]

Monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) are important compounds for atmospheric key processes, e.g., new particle formation (NPF). A description of their multiphase chemical processing within atmospheric models is incomplete, but mandatory to describe their atmospheric budgets. In this study, a detailed multiphase chemistry mechanism was developed and first process model investigations were performed. The simulations focused on pristine marine conditions, where open research questions exist regarding ambient gas-phase concentrations of methylamines, particularly with regards to unexpectedly high DMA levels. The simulations reveal that TMA oxidation in cloud droplets results into DMA formation with a yield of around 87%, a missing DMA production pathway in current models. Also, it is demonstrated that about 21% and 69% of the respective DMA and TMA gas-phase oxidation proceed via autoxidation yielding HOOCH2NHCHO and HOOCH2N(CHO)CH2OOH, respectively. The discussed processes should be included into atmospheric models for advanced predictions of NPF and climate impacts. [ABSTRACT FROM AUTHOR]

α,β‐Unsaturated aldehydes are important building blocks for the synthesis of a wide range of chemicals, including polymers. The synthesis of these molecules from cheap feedstocks such as alkenes remains a scientific challenge, mainly due to the low reactivity of alkenes. Here we report a selective and metal‐free access to α,β‐unsaturated aldehydes from alkenes with formaldehyde. This reaction is catalyzed by dimethylamine and affords α,β‐unsaturated aldehydes in yields of up to 80 %. By combining Density Functional Theory (DFT) calculations and experiments, we elucidate the reaction mechanism which is based on a cascade of hydride transfer, hydrolysis and aldolization reactions. The reaction can be performed under very mild conditions (30–50 °C), in a theoretically 100 % carbon‐economical fashion, with water as the only by‐product. The reaction was successfully applied to non‐activated linear 1‐alkenes, thus opening an access to industrially relevant α,β‐unsaturated aldehydes from cheap and widely abundant chemicals at large scale. [ABSTRACT FROM AUTHOR]

Recent experiments have revealed a vital nucleation process of iodic acid (HIO 3) and iodous acid (HIO 2) under marine boundary layer conditions. However, HIO 3 –HIO 2 nucleation may not effectively drive the observed rapid new particle formation (NPF) in certain coastal regions influenced by urban air masses. Dimethylamine (DMA) is a promising basic precursor to enhance nucleation considering its strong ability to stabilize acidic clusters and the wide distribution in marine atmosphere, while its role in HIO 3 –HIO 2 nucleation remains unrevealed. Hence, a method combining quantum chemical calculations and Atmospheric Cluster Dynamics Code (ACDC) simulations was utilized to study the HIO 3 –HIO 2 –DMA nucleation process. We found that DMA can preferentially accept the proton from HIO 3 as a basic precursor in the most stable configurations of HIO 3 –HIO 2 –DMA clusters. Kinetically, the participation of DMA in the cluster formation pathways of the iodine oxoacid system could be significant at the 10 -1 to 1 pptv level of [DMA]. Furthermore, DMA can enhance the cluster formation rates of the HIO 3 –HIO 2 system in marine and polar regions near DMA sources more than 10 3 -fold. Compared to the classical nucleation mechanism, the HIO 3 –HIO 2 –DMA mechanism exhibits strong nucleation ability, worthy of consideration as a promising mechanism in marine and polar regions rich in amine sources. The newly proposed HIO 3 –HIO 2 –DMA ternary mechanism might provide an explanation for some missing fluxes of atmospheric iodine particles. [ABSTRACT FROM AUTHOR]

Exchange of B800 bacteriochlorophyll (BChl) a in light-harvesting complex 2 (LH2) is promising for a better understanding of the mechanism on intracomplex excitation energy transfer of this protein. Structural and spectroscopic properties of LH2 lacking B800 BChl a (B800-depleted LH2), which is an important intermediate protein in the B800 exchange, will be useful to tackle the energy transfer mechanism in LH2 by the B800 exchange strategy. In this study, we report a unique spectral change of B800-depleted LH2, in which the Qy absorption band of B800 BChl a is automatically recovered under neutral pH conditions. This spectral change was facilitated by factors for destabilization of LH2, namely, a detergent, lauryl dimethylamine N-oxide, and an increase in temperature. Spectral analyses in the preparation of an LH2 variant denoted as B800-recovered LH2 indicated that most BChl a that was released by decomposition of part of B800-depleted LH2 was a source of the production of B800-recovered LH2. Characterization of purified B800-recovered LH2 demonstrated that its spectroscopic and structural features was quite similar to those of native LH2. The current results indicate that the recovery of the B800 Qy band of B800-depleted LH2 originates from the combination of decomposition of part of B800-depleted LH2 and in situ reconstitution of BChl a into the B800 binding pockets of residual B800-depleted LH2, resulting in the formation of stable B800-recovered LH2. [ABSTRACT FROM AUTHOR]

The detection of volatile amines is necessary due to the serious toxicity hazards they pose to human skin, respiratory systems, and nervous systems. However, traditional amines detection methods require bulky equipment, high costs, and complex measurements. Herein, we report a new simple, rapid, convenient, and visual method for the detection of volatile amines based on the gas–solid reactions of tetrachloro-p-benzoquinone (TCBQ) and volatile amines. The gas–solid reactions of TCBQ with a variety of volatile amines showed a visually distinct color in a time-dependent manner. Moreover, TCBQ can be easily fabricated into simple and flexible rapid test strips for detecting and distinguishing n-propylamine from other volatile amines, including ethylamine, n-butyamine, n-pentamine, n-butyamine and dimethylamine, in less than 3 s without any equipment assistance. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded organic frameworks (HOFs) are frameworks formed by organic building blocks through hydrogen bonding forces with promising applications in various fields. However, their development has been hindered by poor stability. In this work, a multiple hydrogen bond strategy with in situ generation of dimethylamine (DMA) is proposed to design robust HOFs. The protic acid HCl and Lewis acid Ag+ catalyze the cleavage of the amide C–N bond in the solvent N,N-dimethylformamide (DMF) molecules to generate dimethylamine (DMA) molecules in situ. Then, DMA molecules form multiple hydrogen bonds with dicarboxylic phenylporphyrin (DBP), and build a crystalline hydrogen-bonded organic framework (DBP-HOF), utilizing both their donor and acceptor on the N atom of each DMA molecule. Additionally, DBP's large π conjugate structure contributes to stabilizing DBP-HOF through strong π–π stacking interactions. Notably, DBP-HOF demonstrates excellent fluorescence performance for selective detection of Cu2+, as well as responsiveness towards methylene blue (MB) and indigo carmine (IC). Interestingly, each analyte elicits distinct fluorescence behavior from DBP-HOF, enabling their effective differentiation. This study holds significant implications for designing stable HOF materials and advancing their application in optical sensing. [ABSTRACT FROM AUTHOR]

The N-nitrosamine, N-nitrosodimethylamine (NDMA), is an environmental mutagen and rodent carcinogen. Small levels of NDMA have been identified as an impurity in some commonly used drugs, resulting in several product recalls. In this study, NDMA was evaluated in an OECD TG-488 compliant Muta™Mouse gene mutation assay (28-day oral dosing across seven daily doses of 0.02-4 mg/kg/day) using an integrated design that assessed mutation at the transgenic lac Z locus in various tissues and at the endogenous Pig-a gene-locus, along with micronucleus frequencies in peripheral blood. Liver pathology was determined together with NDMA exposure in blood and liver. The additivity of mutation induction was assessed by including two acute single-dose treatment groups (i.e. 5 and 10 mg/kg dose on Day 1), which represented the same total dose as two of the repeat dose treatment groups. NDMA did not induce statistically significant increases in mean lac Z mutant frequency (MF) in bone marrow, spleen, bladder, or stomach, nor in peripheral blood (Pig-a mutation or micronucleus induction) when tested up to 4 mg/kg/day. There were dose-dependent increases in mean lac Z MF in the liver, lung, and kidney following 28-day repeat dosing or in the liver and kidney after a single dose (10 mg/kg). No observed genotoxic effect levels (NOGEL) were determined for the positive repeat dose–response relationships. Mutagenicity did not exhibit simple additivity in the liver since there was a reduction in MF following NDMA repeat dosing compared with acute dosing for the same total dose. Benchmark dose modelling was used to estimate point of departure doses for NDMA mutagenicity in Muta™Mouse and rank order target organ tissue sensitivity (liver > kidney or lung). The BMD50 value for liver was 0.32 mg/kg/day following repeat dosing (confidence interval 0.21–0.46 mg/kg/day). In addition, liver toxicity was observed at doses of ≥ 1.1 mg/kg/day NDMA and correlated with systemic and target organ exposure. The integration of these results and their implications for risk assessment are discussed. [ABSTRACT FROM AUTHOR]

Since the initial 2018 recall of angiotensin receptor blockers due to unacceptable levels of mutagenic N-nitrosodimethylamine (NDMA) impurity, numerous drug products delivering diverse active pharmaceutical ingredients (APIs) have been recalled. Regulators and the industry are working together to understand and address this widescale problem. Conventional analysis of NDMA utilizes liquid or gas chromatography-based procedures that can involve complicated sample preparation and slow sample analysis. Selected ion flow tube mass spectrometry (SIFT-MS) analyses NDMA directly in the gas phase using soft chemical ionization, with an LOQ of 2 ng g−1. Through the novel application of the multiple headspace extraction (MHE) technique, NDMA was quantified directly and rapidly from the drug product without dissolution, at levels well below the regulatory acceptable intake of 96 ng day−1. A comparative analysis of recalled metformin using MHE-SIFT-MS and a conventional liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) method showed good agreement. Use of the novel MHE-SIFT-MS approach may enable a wider screening of drug products to be conducted, since it provides around a three-fold increase in daily sample throughput. [ABSTRACT FROM AUTHOR]

Jennifer Corwin-Buell, Denise Callahan, Deborah McGrath, Kimberly Millard, Gary Mosehauer, Nitasha R Phatak Vision Care, Bausch & Lomb Incorporated, Rochester, NY, USACorrespondence: Nitasha R Phatak, Vision Care, Bausch & Lomb Incorporated, Rochester, NY, USA, Tel +1 585-413-6397, Email Nitasha.Phatak@bausch.comPurpose: This study was conducted to evaluate and compare the in vitro disinfection efficacies of six commercial lens cleaning and disinfecting products for planned replacement soft contact lenses.Methods: Disinfection efficacies of five multi-purpose solutions (MPSs) and one hydrogen peroxide solution (HPS) as control were evaluated in the presence of organic soil according to the International Organization for Standardization (ISO, Geneva, Switzerland) ISO 14729 stand-alone test protocol. The five specified compendial organisms, three bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, and Serratia marcescens) and two fungi (Candida albicans and Fusarium solani) were incubated with each solution under standard conditions, after which microbes were recovered and quantified.Results: Each of the solutions evaluated met or exceeded the standard’s primary criteria (3-log reduction of bacteria and 1-log reduction of fungi) after incubation for the manufacturer-recommended soaking time, except for COMPLETE MPS, which achieved only 0.4 ± 0.1 average log reduction for C. albicans. However, differences in efficacy between the solutions were noted. Average log reduction across all microbes for Biotrue Hydration Plus (4.6 ± 0.1) was comparable to that for CLEAR CARE PLUS HPS (4.3 ± 0.1) and greater than those for OPTI-FREE puremoist (3.6 ± 0.1), OPTI-FREE Replenish (4.0 ± 0.2), ACUVUE RevitaLens (3.9 ± 0.03), and COMPLETE MPS (3.6 ± 0.1). Biotrue Hydration Plus was especially effective at reducing the population of C. albicans (4.2 ± 0.7-log reduction).Conclusion: Products marketed for planned replacement soft CL disinfection generally meet the ISO 14729 standard’s primary criteria for reducing populations of compendial organisms, with larger differences between solutions noted with C. albicans.Keywords: multi-purpose solution, MPS, hydrogen peroxide solution, HPS, disinfection, myristamidopropyl dimethylamine, MAPD, polyhexamethylene biguanide, PHMB, ISO 14729

Disinfection by-products (DBPs) such as chloroacetic acids (CAAs) and N-Nitrosodimethylamine (NDMA) are prevalent pollutants in surface waters, particularly with the increasing use of chlorine-based disinfectants. The entry of these DBPs into water bodies may increase accordingly, posing ecological risks to aquatic life. To assess the toxic effects of CAAs and NDMA on submerged macrophytes, Vallisneria natans was exposed to different concentrations of CAAs (1.0, 10.0, and 100.0 μg L−1) and NDMA (0.1, 1.0, and 10.0 μg L−1). A RI value of −1) showed the most significant change in SOD activity, reaching 3.57 times that of the CT group. Ultrastructural changes also revealed stress responses in leaf cells and damage to organelles. Furthermore, metabolomics provided insights into the metabolic responses induced by CAAs or NDMA in V. natans leaves, where the composition and metabolism of lipids, fatty acids, cofactors and vitamins, amino acids, nucleotides, and some antioxidants were regulated, affecting plant growth. This study provides preliminary information for the ecological risk assessment of submerged plants by complex contamination with the disinfection by-products CAA and NDMA.

Through computational analysis we found that pentazine and hexazine, two hypothetical high-energy density materials, exhibit inherent instability due to quantum tunneling effects. This instability remains even near the absolute zero, and therefore they can be deemed as unsynthesizable. We propose substituents that could potentially stabilize pentazine, especially dimethylamine. [ABSTRACT FROM AUTHOR]

The incorporation of organic ligands via post‐device treatment is an effective strategy to improve the stability of perovskite solar cells (PSCs). Although the active area is protected by metal electrode under post‐treatment, the aggression of post‐treatment ligands into active area cannot be avoided thoroughly. Unfortunately, the size of long‐chain amines is too large, and the three‐dimensional (3D) perovskite cannot maintain its 3D perovskite structure once the cation substitution occurs during the post‐treatment. Despite that the low‐dimensional (LD) perovskites are beneficial to stability, long‐chain amines are harmful to carrier transport in PSCs. Here, we introduce dimethylamine (DMA), a slightly oversized cation that can be doped into 3D perovskite structure, for post‐device treatment to improve the efficiency and stability of PSCs. After exposure to DMA gas, the inactive area of Cs/FA/MA mixed cation perovskite device that is not covered by metal electrode is converted into LD perovskite, passivating the defects of 3D perovskite in the active region, suppressing non‐radiation recombination and ion migration. As a result, we achieved a power conversion efficiency (PCE) of 22.29 % with negligible hysteresis and better stability after DMA post‐treatment, which is much higher than that (20.40 %) of the control device. [ABSTRACT FROM AUTHOR]

The reactions of glyoxal (CHO)2) with amines in cloud processes contribute to the formation of brown carbon and oligomer particles in the atmosphere. However, their molecular mechanisms remain unknown. Herein, we investigate the ammonolysis mechanisms of glyoxal with amines at the air‐water nanodroplet interface. We identified three and two distinct pathways for the ammonolysis of glyoxal with dimethylamine and methylamine by using metadynamics simulations at the air‐water nanodroplet interface, respectively. Notably, the stepwise pathways mediated by the water dimer for the reactions of glyoxal with dimethylamine and methylamine display the lowest free energy barriers of 3.6 and 4.9 kcal ⋅ mol−1, respectively. These results showed that the air‐water nanodroplet ammonolysis reactions of glyoxal with dimethylamine and methylamine were more feasible and occurred at faster rates than the corresponding gas phase ammonolysis, the OH+(CHO)2 reaction, and the aqueous phase reaction of glyoxal, leading to the dominant removal of glyoxal. Our results provide new and important insight into the reactions between carbonyl compounds and amines, which are crucial in forming nitrogen‐containing aerosol particles. [ABSTRACT FROM AUTHOR]

We reports the ex situ preparation of nanotitania supported ruthenium(0) nanoparticles (NPs) and their catalytic testing in dehydrogenation of dimethylamine borane (DMAB) in toluene solvent. Ru0/TiO 2 NPs are prepared following a 2-step process: Ru3+ ions are first impregnated from the aqueous solution on titania nanopowder and then, reduced by aqueous solution of sodium borohydride. The prepared Ru0/TiO 2 NPs are dried, bottled under inert N 2 gas atmosphere, and used for characterization by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), ICP-OES (inductively coupled plasma optical emission spectroscopy) and XPS (X-ray photoelectron spectroscopy). Ru0/TiO 2 NPs with various Ru loadings are tested as catalysts in hydrogen generation from DMAB and the Ru0/TiO 2 (0.48% wt. Ru) with an average diameter of 6.7 ± 1.3 nm is found to have the highest initial turnover frequency value of 1700 h−1 for the release of 1.0 mol H 2 per mole of DMAB at 60 °C. Results of the recyclability test indicate quite high durability of Ru0/TiO 2 NPs in dehydrogenation of DMAB. [Display omitted] • Ru0/TiO 2 NPs are prepared by impregnation of Ru3+ ions on the surface of titania followed by their reduction. • Ru0/TiO 2 NPs show high catalytic performance in dehydrogenation of dimethylamine borane. • Ru0/TiO 2 (0.48% wt. Ru) provide a record TOF value of 1700 h−1 in this reaction at 60 °C. [ABSTRACT FROM AUTHOR]

Platinum catalysts with {111} surface has obvious advantages, but the control of {111} exposure usually requires surfactants which cover the surface and decrease the catalytic performance. In this paper, tetrahedral platinum nanoparticle catalysts were successfully prepared with a simple one-step hydrothermal method and their size were successfully controlled under sub-5 nm. The tetrahedral morphology was controlled through the decomposition of dimethylamine by DMF and the small size was determined by alcohol acid radical. Because of the profitable effect of the amines for the tetrahedral morphology, no surfactant was need during the preparation. The catalysis activity was assured by the tetrahedral morphology with Pt {111} exposure without the surfactant covering, and the small size further increased the number of activity sites. For HOR, the catalyst showed higher activity, stronger anti-CO poisoning performance and longer stability than those of commercial catalyst with the same platinum load. For ORR, the catalyst also showed better performances which further promoted the four-electron reaction. Our simple preparation method successfully achieved the aims of the morphology control, size control and the elimination of surfactant, which effectively assured the good catalyst performances. The simple preparation path of such good catalysts shows a great application potential. [ABSTRACT FROM AUTHOR]

Between February 2020 and January 2022, the Food and Drug Administration (FDA) recalled 281 metformin extended-release products due to the presence of N-nitrosodimethylamine (NDMA) above the acceptable daily intake (ADI, 96 ng/day). Our previous studies indicated presence of NDMA levels above ADI in both metformin immediate and extended-release products. When metformin products have NDMA impurities, it is indispensable to check for the same impurities in metformin combination products. Therefore, the objective of the present study was to evaluate in-use stability of commercial metformin combination products for NDMA. For this purpose, metformin products in combination with glyburide (GB1-GB12), glipizide (GP1-GP8), pioglitazone (P1-P3), alogliptin (A1, A2), and linagliptin (L1, L2) were repacked in pharmacy vials, stored at 30°C/75% RH for 3 months, and monitored for NDMA impurity. The NDMA level varied from 0 to 156.8 ± 32.8 ng/tablet initially and increased to 25.4 ± 5.1 to 455.0 ± 28.4 ng/tablet after 3 months of exposure to in-use condition. Initially, 18 products have NDMA level below ADI limit before exposure which decreased to 7 products (GB5, GP3, GP5, A1, A2, L1, and L2) meeting specification. In conclusion, in-use stability study provides quality and safety risk assessment of drug products where nitroso impurities are detected in the probable condition of use. [ABSTRACT FROM AUTHOR]

A double-polyanion-type arsenotungstate, composed of a Dawson-type [Si 0.5 As 0.5 W 18 O 62 ]12.5- polyanion and a [BaNa 2 {As 2 W 19 O 67 (H 2 O)}]10− polyanion in the lattice was synthesized, which exhibits reversible photochromic behavior. [Display omitted] • A double-polyanion-type arsenotungstate was synthesized. • Composed of a Dawson-type [Si 0.5 As 0.5 W 18 O 62 ]12.5- polyanion. • And a [BaNa 2 {As 2 W 19 O 67 (H 2 O)}]10− polyanion. • Exhibits reversible photochromic behavior. A double-polyanion-type arsenotungstate, namely [H 2 N(CH 3) 2 ] 14 H 8.5 [Si 0.5 As 0.5 W 18 O 62 ][BaNa 2 {As 2 W 19 O 67 (H 2 O)}]·29H 2 O was prepared by self-assembly strategy of some simple raw materials, in which a Dawson-type [Si 0.5 As 0.5 W 18 O 62 ]12.5− polyanion and a [BaNa 2 {As 2 W 19 O 67 (H 2 O)}]10− polyanion co-exist in the lattice. Two half-occupied Ba2+ ions were inserted into the pocket-shaped vacancies of {As 2 W 19 } building blocks, while two Na2+ ions served as connectors bridging adjacent units. Furthermore, dimethylamine cations play a vital role in building a hydrogen bond network with the polyoxometalate skeleton to maintain the framework of the solid-state compound 1. In addition, being characterized under the 300 W Xe-lamp, the color of compound 1 changed from light green to bluish grey after 210 s with recovery to its original color after about 14 h treating with darkness, displaying a reversible photochromism. [ABSTRACT FROM AUTHOR]

Reducing nitrites tends to increase the accumulation of hazardous biogenic amines (BAs) in Chinese fermented sausages (CFSs). Gallic acid (GA) has emerged as a potential alternative to reduce nitrite usage and control BAs. This study explored how GA inhibits BAs and nitrosamines accumulation in reduced-nitrite CFSs. Results demonstrated that combining 0.05% (w/w) GA with reduced nitrite effectively curbed BAs and N -nitrosodimethylamine, decreasing total BA from 271.48 to 125.46 mg/kg. Fifty-one metabolites associated with the metabolism of BAs and N -nitrosodimethylamine were identified. GA boosted Lactococcus while reducing spoilage bacteria and Macrococcus. This dual regulation suppressed BAs and dimethylamine accumulation by regulating amino acids and trimethylamine pathways. Consequently, GA achieved an 89.86% reduction in N -nitrosodimethylamine by decreasing the key precursors like putrescine, dimethylamine, and nitrite. These findings offer new insights into utilizing GA and similar plant polyphenols to manage BAs and nitrosamines in meat products with reduced nitrite usage. • Gallic acid suppressed biogenic amines (BAs) in reduced-nitrite Chinese sausages. • Fifty-one metabolites linked closely with BAs and nitrosamines were identified. • Gallic acid dually regulated the microbial community related to amines formation. • Decreasing amine precursors and nitrites ultimately lowered NDMA levels. [ABSTRACT FROM AUTHOR]

To reduce the risk of N -nitrosamines in deli meat products, this study formulated a novel non-contact N -nitrosamines inhibiting preservative IV (NIP-IV) consisting of biocontrol bacteria and plant essential oils (EOs) ( Stenotrophomonas rhizophila SR-1 +  Paenibacillus provencensis PP-2 +  Bacillus subtilis CF-3+ cinnamon EO + grapefruit EO). Luncheon pork, spiced beef, and red sausage were taken as representatives of typical deli meat products and used to validate the effectiveness of NIP-IV in inhibiting N -nitroso dimethylamine (NDMA) production. The results showed that NIP-IV restrain protein degradation and lipid oxidation in deli meat products and effectively control microbial activity. Biogenic amines, such as phenethylamine, spermidine, cadaverine, and tyramine, were reduced. The conversion of nitrite to NDMA in deli meats was effectively inhibited by NIP-IV. Volatile organic compounds were the key to excellent NIP-IV non-contact preservation. Butyric acid, 3-methylbutanoic acid, benzaldehyde, d-limonene, and ( E )-cinnamaldehyde were significantly negatively correlated with NDMA in deli meat products., Competing Interests: 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., (© 2024 The Authors. Published by Elsevier Ltd.)

The Ames test is a widely used bacterial mutagenicity assay to evaluate the potential of chemical compounds to induce mutations. In recent years, there has been growing concern regarding the presence of N-nitrosamines in pharmaceuticals, food, and other consumer products. N-Nitrosamines are probable mutagens and carcinogens. To address the reduced sensitivity of the standard Ames test for N-nitrosamines, particularly N-nitrosodimethylamine, the European Medicines Agency (EMA) and United States Food and Drug Administration (FDA) have recently published recommendations for enhanced Ames test (EAT) conditions. However, there is a lack of clear guidance on the selection of N-nitrosamine positive control concentrations, particularly for 1-cyclopentyl-4-nitrosopiperazine, and the amount of solvent to be used in the EAT. This study aims to address the current gap in concentration and volume specifications by providing a comprehensive guide to set up enhanced Ames test conditions specifically for N-nitrosamine compounds using appropriate amounts of solvent, new solvents, and strain-specific positive control concentrations., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

[Display omitted] • Yeast extract has a good adsorption effect on trimethylamine and dimethylamine. • Yeast extract has higher affinity with dimethylamine than trimethylamine. • The binding changes yeast extract into a conformation with affinity for off-flavors. • Molecular docking reveals insights into the binding sites of trimethylamine and dimethylamine. • Hydrogen bonding and van der Waals forces are the main driving forces of the interaction. The presence of off-flavor compounds in meat products significantly diminishes their sensory quality. In this study, two amine off-flavor compounds, trimethylamine (TMA) and dimethylamine (DMA), were employed as examples to investigate the behavior of yeast extract (YE) in absorbing off-flavors using gas chromatography–mass spectrometry. Additionally, the effects of TMA and DMA on YE conformation were explored based on multi-spectroscopic techniques and molecular docking to elucidate the mechanism of YE adsorption of off-flavors. The results revealed that YE exhibited strong adsorption capabilities towards both TMA and DMA, with a higher affinity for DMA. The presence of TMA and DMA unfolded the YE structure, accompanied by an increase in total sulfhydryl content and zeta potential and a decrease in surface hydrophobicity and particle size of YE. Furthermore, TMA and DMA disrupted the hydrogen-bonding network of YE, causing it to shift from an ordered to a disordered structure. Thermodynamic parameters and molecular docking indicated that YE primarily adsorbed TMA and DMA through hydrogen bonding and van der Waals forces. This study provided valuable insights for utilizing YE in the inhibition of off-flavors in meat products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dimethylamine compounds served as NDMA precursors in the UV/NO 2 – process. • HO• and RNS generated from NO 2 – photolysis were key players in NDMA formation. • DMA was released during the photolysis of dimethylamine compounds by UV/NO 2 –. • N 2 O 3 and N 2 O 4 reacted with DMA via nucleophilic substitution to form NDMA. UV-based treatment technologies have been widely applied in wastewater treatment plants due to its high efficiency in deactivating pathogens and degrading organic contaminants. However, this study demonstrates that N -nitrosodimethylamine (NDMA), a probable human carcinogen, can be generated during UV treatment of dimethylamine (DMA) pollutants of concern, for example isoproturon (IPU), in the presence of nitrite (NO 2 –). Quenching tests have identified that in addition to direct photolysis, hydroxyl radicals (HO•) and nitrogen oxide radicals (NO• and NO 2 •) generated from NO 2 – photolysis play a crucial role in the reaction. They can react with IPU, leading to hydroxylated and nitrated products. More importantly, NO 2 • couples with a NO• or another NO 2 • to form N 2 O 3 and N 2 O 4 , respectively. As nitrosating agents, N 2 O 3 and N 2 O 4 directly attack the released DMA during IPU degradation, yielding NDMA. At IPU initial concentration of 50 μM, the highest concentration of NDMA was 5.62 μg/L in 2.5 h by UV/NO 2 –, corresponding to the molar yield of 0.22%. This study further reveals that other dimethylamine compounds, such as diuron, imipramine, and tetracyclines, can also serve as NDMA precursors during UV disinfection with NO 2 – present. Given that many environmental contaminants contain DMA moieties and NO 2 – is ubiquitously present in wastewaters, formation of NDMA during UV disinfection is probably a common but overlooked problem, which deserves emerging concern. [ABSTRACT FROM AUTHOR]

N-nitrosamines (NAs) are prevalent mutagenic impurities in various consumer products. Their discovery in valsartan-containing medicines in 2018 prompted global regulatory agencies to set guidelines on their presence and permissible levels in pharmaceuticals. In order to determine the NAs content in medicines, efficient and sensitive analytical methods have been developed based on mass spectrometry techniques. Direct analysis in real time-mass spectrometry (DART-MS) has emerged as a prominent ambient ionization technique for pharmaceutical analysis due to its high-throughput capability, simplicity, and minimal sample preparation requirements. Thus, in this study DART-MS was evaluated for the screening and quantification of NAs in medicines. DART-MS analyses were conducted in positive ion mode, for both direct tablet analysis and solution analysis. The analytical performance was evaluated regarding linearity, precision, accuracy, limits of detection, and quantification. The DART-MS proved to be suitable for the determination of NAs in medicines, whether through direct tablet analysis or solution analysis. The analytical performance demonstrated linearity in the range from 1.00 to 200.00 ng mL -1 , limits of quantification about 1.00 ng mL -1 , precision and accuracy lower than 15%, and no significant matrix effect for six drug-related NAs. In conclusion, the DART-MS technique demonstrated to be an alternative method to determine NAs in medicines, aligning with the principles of green chemistry.

1,4-cyclohexanedimethylamine (1,4-BAC) is an important monomer for bio-based materials, it finds wide applications in various fields including organic synthesis, medicine, chemical industry, and materials. At present, its synthesis primarily relies on chemical method, which suffer from issues such as expensive metal catalyst, harsh reaction conditions, and safety risks. Therefore, it is necessary to explore greener alternatives for its synthesis. In this study, a two-bacterium three-enzyme cascade conversion pathway was successfully developed to convert 1,4-cyclohexanedicarboxaldehyde to 1,4-cyclohexanedimethylamine. This pathway used Escherichia coli derived aminotransferase ( Ec TA), Saccharomyces cerevisiae derived glutamate dehydrogenase ( S cGlu-DH), and Candida boidinii derived formate dehydrogenase ( Cb FDH). Through structure-guided protein engineering, a beneficial mutant, Ec TA F91Y , was obtained, exhibiting a 2.2-fold increase in specific activity and a 1.9-fold increase in k cat / K m compared to that of the wild type. By constructing recombinant strains and optimizing reaction conditions, it was found that under the optimal conditions, a substrate concentration of 40 g/L could produce (27.4±0.9) g/L of the product, corresponding to a molar conversion rate of 67.5%±2.1%.

The surge in hazardous volatile organic liquid emissions driven by the rapid growth of the manufacturing industry has compelled a rising demand for gas sensors, which exhibit remarkable sensitivity, selectivity, and room temperature operation. Ternary metal oxide spinel has indeed garnered significant attention in chemi-resistive gas sensors due to their large reactive surface area, physicochemical, and other unique properties. In this work, we have studied chemically sprayed pristine and Cd 2+ incorporated Co 2 SnO 4 thin film as a sensing layer under room temperature (300 K) conditions. The 5 wt% Cd 2+ incorporated Co 2 SnO 4 films unveiled a high sensor response to dimethylamine (DMA) gas (S = I gas /I air = 6153 at 1 ppm), which was boosted by 8.89-fold times compared to pristine Co 2 SnO 4 film, due to the large reactive surface area and enhanced defective oxygen vacancies. It has superior selectivity towards DMA gas, good response time (154 s) / recovery time (90 s), superior pro-longevity (S = 6138) after 60 days, stable repeatability (7 cycles), excellent cross-selectivity, and relative humid resistance at 300 K. This research work provides insights on Cd 2+ incorporated Co 2 SnO 4 thin films and their feasibility in real-time gas sensing devices. [Display omitted] • An Excellent DMA sensor constructed by integrating Cd 2+ ions in Co 2 SnO 4 thin films. • 5 wt% Cd - CTO film shows sensor response (S = 6153 @ 1 ppm) to DMA gas at 300 K. • The Large surface area and oxygen vacancies facilitate the highest sensor response. • The DMA sensor also shows an excellent cross-selectivity and fast responsiveness. [ABSTRACT FROM AUTHOR]

• The stability of DMA on pristine Pt(111) is lower than on a co-adsorbed IL film. • In the presence of DMA/MAC, the IL adsorbs in a different geometry. • Co-adsorbed IL suppresses the co-adsorption of CO after partial dehydrogenation of DMA to MAC. • We suggest that the IL has a pronounced effect on the individual reaction steps. Solid catalysts with ionic liquid layers (SCILLs) are heterogeneous catalysts whose selectivity is significantly improved by the application of a thin coating of an ionic liquid (IL). In this work, we studied the influence of the IL 1-ethyl-3-methyl-imidazolium-trifluormethansulfonate ([C 2 C 1 Im][OTf]) on the dehydrogenation of dimethylamine (DMA) on Pt(111) by surface science experiments under ultrahigh vacuum (UHV) conditions. We investigated the growth, thermal stability, and the dehydrogenation reaction of DMA on Pt(111) both in the presence and absence of [C 2 C 1 Im][OTf] by time-resolved and temperature-programmed infrared reflection absorption spectroscopy (IRAS) and density functional theory (DFT). We found that pre-adsorbed DMA has a strong influence on the interaction of [C 2 C 1 Im][OTf] with the Pt surface. The competition for the same adsorption sites leads to changes in the binding motif and binding angles of the IL. In the presence of the IL, the reaction temperature of DMA is shifted to higher temperature due to the same competition and blocking effects. Thus, the IL leads to an enhanced stability of DMA on the surface and influences the product spectrum of the dehydrogenation reaction at higher temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

Schematic illustration of the synthesis process of hexagonal pine needle-like Sn-WO 3 structures. [Display omitted] • Hexagonal pine needle-like Sn-WO 3 structures were prepared via a hydrothermal method. • The Sn/W ratios play an important role in the morphology and phase of hexagonal pine needle-like Sn-WO 3 structures. • The gas sensor based on hexagonal pine needle-like Sn-WO 3 structures exhibits excellent sensing properties to dimethylamine. Novel hexagonal pine needle-like Sn-WO 3 structures were synthesized using the hydrothermal method. The present study aimed to evaluate the impact of Sn/W ratios and the introduction of several metal elements (Fe, Zn, Cu, and In) on both the morphology and gas-sensing properties of WO 3. The hexagonal pine needle-like 1 % Sn-WO 3 sensor had a significantly elevated response of 89 and a faster response/recovery time of 11/15 s when exposed to 10 ppm dimethylamine (DMA) at the optimal operating temperature of 180 °C. This sensor displayed notable characteristics such as excellent selectivity, repeatability, long-term stability, and a detection limit of 25 ppb. The excellent sensing performances of this sensor can be attributed to their highly (1 0 0) facet, Sn doping and distinctive hexagonal pine needle-like morphology. [ABSTRACT FROM AUTHOR]

Since 2018, N -nitrosodimethylamine (NDMA) has been a reported contaminant in numerous pharmaceutical products. To guide the pharmaceutical industry, FDA identified an acceptable intake (AI) of 96 ng/day NDMA. The approach assumed a linear extrapolation from the Carcinogenic Potency Database (CPDB) harmonic-mean TD 50 identified in chronic studies in rats. Although NDMA has been thought to act as a mutagenic carcinogen in experimental animals, it has not been classified as a known human carcinogen by any regulatory agency. Humans are exposed to high daily exogenous and endogenous doses of NDMA. Due to the likelihood of a threshold dose for NDMA-related tumors in animals, we believe that there is ample scientific basis to utilize the threshold-based benchmark dose or point-of-departure (POD) approach when estimating a Permissible Daily Exposure limit (PDE) for NDMA. We estimated that 29,000 ng/kg/day was an appropriate POD for calculating a PDE. Assuming an average bodyweight of 50 kg, we expect that human exposures to NDMA at doses below 5800 ng/day in pharmaceuticals would not result in an increased risk of liver cancer, and that there is little, if any, risk for any other type of cancer, when accounting for the mode-of-action in humans. • The AI of 96 ng/day for NDMA in pharmaceuricals was calculated based on the assumption of a linear dose-response relationship. • However, there is a likelihood for a threshold-based dose-response relationship between NDMA and liver tumors in animals. • Thus, we utilized a point-of-departure (POD) approach to estimate a PDE for NDMA in pharmaceuticals. • We used a BMDL 10 as a POD (29,000 ng/kg/day) divided by a SF of 250, multiplied by 50 kg to account for human body weight. • Using this approach, we calculated a PDE of 5,800 ng/day NDMA in pharmaceuticals. [ABSTRACT FROM AUTHOR]

The influencing factors, products and mechanism of N -nitrosodimethylamine (NDMA) reduction by zinc (Zn) in the presence of transition-metal ions (Mn2+, Co2+ and Ni2+), were investigated. The NDMA removal by Zn was significantly improved by them, and the promoting effect of Co2+ and Ni2+ were better than Mn2+. With the decrease of pH values and dissolved oxygen concentrations, the removals of NDMA were enhanced in all reaction systems. NDMA was mainly reduced to unsymmetrical dimethylhydrazine (UDMH) in Zn and Zn/Mn2+ systems. It was mainly reduced to dimethylamine (DMA) and ammonium (NH 4 +) in Zn/Co2+ and Zn/Ni2+ systems. There were undetected products in all reaction systems. Catalytic hydrogenation was the main mechanism, and active hydrogen atom was the main active species. The presence of Mn2+, Co2+ and Ni2+ promoted the corrosion of Zn and changed the surface morphology of Zn. The formation of type I film on Zn surface was promoted in the presence of Co2+ and Ni2+, which was conducive to the continuous corrosion of Zn and hydrogen generation. While type II film which would inhibit the corrosion of Zn formed on Zn surface in the presence of Mn2+. MnO 2 , Co 3 O 4 and Ni(OH) 2 were formed in Zn/Mn2+, Zn/Co2+ and Zn/Ni2+ systems, respectively. They would facilitate more generation of active hydrogen atoms. [Display omitted] • Mn2+, Co2+ and Ni2+ could enhance the reduction of NDMA by Zn. • The amounts of products were different with different transition-metal ions. • Active hydrogen atom was the main active species. • The corrosion rates were increased and reaction interface conditions were improved. • The in-situ generated MnO 2 , Co 3 O 4 and Ni(OH) 2 would enhance the reaction. [ABSTRACT FROM AUTHOR]

N -nitrosodimethylamine (NDMA), one of the new nitrogen-containing disinfection by-products, is potentially cytotoxic, genotoxic, and carcinogenic. Its potential toxicological effects have attracted a wide range of attention, but the mechanism is still not sufficiently understood. To better understand the toxicological mechanisms of NDMA, zebrafish embryos were exposed to NDMA from 3 h post-fertilization (hpf) to 120hpf. Mortality and malformation were significantly increased, and hatching rate, heart rate, and swimming behavior were decreased in the exposure groups. The result indicated that NDMA exposure causes cardiac and spinal developmental toxicity. mRNA levels of genes involved in the apoptotic pathway, including p53 , bax , and bcl-2 were significantly affected by NDMA exposure. Moreover, the genes associated with spinal and cardiac development (myh6 , myh7 , nkx2.5 , eph , bmp2b , bmp4 , bmp9 , run2a, and run2b) were significantly downregulated after treatment with NDMA. Wnt and TGF-β signaling pathways, crucial for the development of diverse tissues and organs in the embryo and the establishment of the larval spine, were also significantly disturbed by NDMA treatment. In summary, the disinfection by-product, NDMA, exhibits spinal and cardiac developmental toxicity in zebrafish embryos, providing helpful information for comprehensive analyses and a better understanding the mechanism of its toxicity. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new biosensor based on zein-UCNPs film was prepared for NDMA detection. • The porous structure of zein film provided good immobilization for UCNPs. • On-site detection in food samples with good recoveries and GC–MS validation. • A lower LOD of 0.017 ng/mL can be obtained from this proposed biosensor. Pickled frequently contains nitrosodimethylamine (NDMA), a mutagenic and carcinogenic substance that is dangerous for the general public's health. This study reports on the fabrication of a fluorescent biosensor using zein film and aptamer functionalized upconversion nanoparticles (UCNPs) for on-site monitoring of NDMA in meat. UCNPs were first prepared followed by aptamer binding and mixing with zein film, which was further conjugated with cDNA of dabcyl modified at 5′. The fluorescence resonance energy transfer (FRET) mechanism between the UCNPs and dabcyl was exploited. The fluorescence signals of the zein film recovered when NDMA was present because it was selectively collected by the particular aptamer and damaged the cDNA structure. The designed functionalized zein film was used for on-site and portable determination of NDMA with a lower limit of detection of 0.017 ng/mL, and possessed a satisfactory recovery ranging from 95.8% to 100.2% with no significant difference compared with the GC–MS method. [ABSTRACT FROM AUTHOR]

Herein, we fabricated CoCu-0.25-O v with ternary Co...O v ...Cu sites through simple co-precipitation to achieve effective co-utilization of organics and dissolved oxygen (DO) as endogenous electron donor-acceptor in Fenton-like system. Around 100% of dimethylamine (DMA) min within 30 is removed. The involved kinetics (0.22 min−1) and oxidant utilization efficiency (22.5%) are higher than controls with binary sites. Multi-scaled characterizations and theoretical calculations reveal that electron-polarized Co...O v ...Cu sites facilitate co-activation of DMA and DO as electron donor-acceptor through increasing d -band center and lowering work function of catalyst. Meanwhile, ternary sites favor 1O 2 and SO 4 •− generation, and shorten the migration distance of active species to pollutant, thus achieving excellent dual performance improvements. Semi-quantitative results of ESR indicate that DO activation and peroxymonosulfate (PMS) oxidation contribute about three-fourths and one-fourth to 1O 2 production, respectively. This contribution provides a new and sustainable strategy for high-efficiency and oxidant-saving removal of refractory pollutants in the environment. [Display omitted] • Co...O v ...Cu sites greatly improve removal performance of DMA and PMS utilization rate. • Ternary sites activate DMA and DO to replace PMS and favor the formation of ROSs. • Increased d -band center and lower work function of catalyst boost the co-activation. • DMA is removal by enhanced multipath (self-oxidation, 1O 2 and SO 4 •− attacks). • O 2 activation and PMS oxidation contribute 3/4 and 1/4 to 1O 2 formation, respectively. [ABSTRACT FROM AUTHOR]

In drinking water chloramination, monochloramine autodecomposition occurs in the presence of excess free ammonia through dichloramine, the decay of which was implicated in N -nitrosodimethylamine (NDMA) formation by (i) dichloramine hydrolysis to nitroxyl which reacts with itself to nitrous oxide (N 2 O), (ii) nitroxyl reaction with dissolved oxygen (DO) to peroxynitrite or mono/dichloramine to nitrogen gas (N 2 ), and (iii) peroxynitrite reaction with total dimethylamine (TOTDMA) to NDMA or decomposition to nitrite/nitrate. Here, the yields of nitrogen and oxygen-containing end-products were quantified at pH 9 from NHCl 2 decomposition at 200, 400, or 800 μeq Cl 2 ·L -1 with and without 10 μM-N TOTDMA under ambient DO (∼500 μM-O) and, to limit peroxynitrite formation, low DO (≤40 μM-O). Without TOTDMA, the sum of free ammonia, monochloramine, dichloramine, N 2 , N 2 O, nitrite, and nitrate indicated nitrogen recoveries ±95% confidence intervals were not significantly different under ambient (90 ± 6%) and low (93 ± 7%) DO. With TOTDMA, nitrogen recoveries were less under ambient (82 ± 5%) than low (97 ± 7%) DO. Oxygen recoveries under ambient DO were 88-97%, and the so-called unidentified product of dichloramine decomposition formed at about three-fold greater concentration under ambient compared to low DO, like NDMA, consistent with a DO limitation. Unidentified product formation stemmed from peroxynitrite decomposition products reacting with mono/dichloramine. For a 2:2:1 nitrogen/oxygen/chlorine atom ratio and its estimated molar absorptivity, unidentified product inclusion with uncertainty may close oxygen recoveries and increase nitrogen recoveries to 98% (ambient DO) and 100% (low DO).