Amines are recognized as significant enhancing species on methanesulfonic acid (MSA)-driven new particle formation (NPF). Monoethanolamine (MEA) has been detected in the atmosphere and its concentration could be significantly increased once MEA-based post-combustion CO2 capture technology is widely implemented. Here, we evaluated the enhancing potential of MEA on MSA-driven NPF by examining the formation of MEA-MSA clusters using a combination of quantum chemical calculations and kinetics modeling. The results indicate that-OH group of MEA can form at least one hydrogen bond with MSA or MEA in all MEA-containing clusters. The enhancing potential of MEA is higher than that of the strongest enhancing agent known so far, methylamine (MA), for MSA-driven NPF. Such high enhancing potential can be ascribed to not only the higher gas-phase basicity, but also the role of the additional-OH group of MEA in increasing the binding free energy by forming additional hydrogen bonds. This clarifies the importance of hydrogen-bonding capacity from the non-amino group of amines in enhancing MSA-driven NPF. The main growth pathway for MEA-MSA clusters proceeds via the initial formation of the (MEA)1(MSA)1 cluster, followed by alternately adding one MSA and one MEA molecule, differing from the case of MA-MSA clusters.

Recent findings on the formation of ·Cl in continental urban areas necessitate the consideration of ·Cl initiated degradation when assessing the fate of volatile organic pollutants. Monoethanolamine (MEA) is considered as a potential atmospheric pollutant since it is a benchmark and widely utilized solvent in a leading CO2 capture technology. Especially, ·Cl may have specific interactions with the N atom of MEA, which could make the MEA + ·Cl reaction have different pathways and products from those of the MEA + ·OH reaction. Hence, ·Cl initiated reactions with MEA were investigated by a quantum chemical method [CCSD(T)/aug-cc-pVTZ//MP2/6-31+G(3df,2p)] and kinetics modeling. Results show that the overall rate constant for ·Cl initiated H-abstraction of MEA is 5 times faster than that initiated by ·OH, and the tropospheric lifetimes of MEA will be overestimated by 6-46% when assuming that [·Cl]/[·OH] = 1-10% if the role of ·Cl is ignored. The MEA + ·Cl reaction exclusively produces MEA-N that finally transforms into several products including mutagenic nitramine and carcinogenic nitrosamine via further reactions with O2/NOx, and the contribution of ·Cl to their formation is about 25-250% of that of ·OH. Thus, it is necessary to consider ·Cl initiated tropospheric degradation of MEA for its risk assessment.

Chlorine radicals (·Cl) initiated amine oxidation plays an important role for the formation of carcinogenic nitrosamine in the atmosphere. Piperazine (PZ) is considered as a potential atmospheric pollutant since it is an alternative solvent to monoethanolamine (MEA), a benchmark solvent in a leading CO capture technology. Here, we employed quantum chemical methods and kinetics modeling to investigate ·Cl-initiated atmospheric oxidation of PZ, particularly concerning the potential of PZ to form nitrosamine compared to MEA. Results showed that the ·Cl-initiated PZ reaction exclusively leads to N-center radicals (PZ-N) that mainly react with NO to produce nitrosamine in their further reaction with O/NO. Together with the PZ + ·OH reaction, the PZ-N yield from PZ oxidation is still lower than that of the corresponding MEA reactions. However, the nitrosamine yield of PZ is higher than the reported value for MEA when [NO] is <5 ppb, a concentration commonly encountered in a polluted urban atmosphere. The unexpected high nitrosamine yield from PZ compared to MEA results from a more favorable reaction of N-center radicals with NO compared to O. These findings show that the yield of N-center radicals cannot directly be used as a metric for the yield of the corresponding carcinogenic nitrosamine.

Piperazine (PZ), a cyclic diamine, is one of 160 detected atmospheric amines and an alternative solvent to the widely used monoethanolamine in postcombustion CO2 capture. Participating in H2SO4 (SA)-based new particle formation (NPF) could be an important removal pathway for PZ. Here, we employed quantum chemical calculations and kinetics modeling to evaluate the enhancing potential of PZ on SA-based NPF by examining the formation of PZ-SA clusters. The results indicate that PZ behaves more like a monoamine in stabilizing SA and can enhance SA-based NPF at the parts per trillion (ppt) level. The enhancing potential of PZ is less than that of the chainlike diamine putrescine, and greater than that of dimethylamine which is one of the strongest enhancing agents confirmed by ambient observations and experiments. After the initial formation of the (PZ)1(SA)1 cluster, the cluster mainly grows by gradual addition of SA or PZ monomer, followed by addition of (PZ)1(SA)1 cluster. We find that the ratio of PZ removal by NPF to that by the combination of NPF and oxidations is 0.5-0.97 at 278.15 K. As a result, the participation in the NPF pathway could significantly alter the environmental impact of PZ compared to only considering oxidation pathways.

Resveratrol (3,5,4-trihydroxystilbene, RES), a natural antioxidant, prevents bone loss by attenuating damage caused by oxidative stress. Our previous research revealed that the forkhead box O1 (FoxO1)/β-catenin signaling pathway affected the proliferation and differentiation of osteoblasts through its regulation of redox balance, and RES regulated the expression of FoxO1 to control white adipose tissue and then ameliorate an overweight condition. Based on previous research, we hypothesized that RES regulates FoxO1 transcriptional activity through the phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathway to achieve an antioxidative effect on osteoporosis and then we confirmed this hypothesis in the present study. An ovariectomized (OVX) rat model of osteoporosis and a H2O2-induced oxidative cell injury model in RAW 264.7 cells were established to explore the underlying molecular mechanisms of how RES confers an antioxidant effect and prevents bone loss. The obtained results demonstrated that RES strongly prevented bone loss induced by oxidative stress in vivo. More specifically, RES effectively decreased the receptor activator of nuclear factor-κB ligand (RANKL) together with the tartrate-resistant acid phosphatase-5b (TRAP-5b) level, but elevated the osteoproprotegrin (OPG) level and attenuated bone microarchitecture damage. Notably, RES, due to its antioxidant effect, suppressed RANKL production and then inhibited osteoclastogenesis in the OVX rats. In vitro, RES improved the oxidative stress status of cells and thus inhibited the mRNA expression of osteoclast-specific enzymes. These data indicate that RES has a significant bone protective effect by antagonizing oxidative stress to suppress osteoclast activity, function and formation both in vivo and in vitro. Moreover, at the molecular level, we confirmed, for the first time, that RES upregulated FoxO1 transcriptional activity by inhibiting the PI3K/AKT signaling pathway, and hence promoted resistance to oxidative damage and restrained osteoclastogenesis. Inhibition of the PI3K/AKT signaling pathway may be induced by RANKL. FoxO1 is a major action target of RES to confer anti-osteoporosis function, and whose effect stems from its power to improve redox balance.

Nucleation of neutral iodine particles has recently been found to involve both iodic acid (HIO 3 ) and iodous acid (HIO 2 ). However, the precise role of HIO 2 in iodine oxoacid nucleation remains unclear. Herein, we probe such a role by investigating the cluster formation mechanisms and kinetics of (HIO 3 ) m (HIO 2 ) n ( m = 0–4, n = 0–4) clusters with quantum chemical calculations and atmospheric cluster dynamics modeling. When compared with HIO 3 , we find that HIO 2 binds more strongly with HIO 3 and also more strongly with HIO 2 . After accounting for ambient vapor concentrations, the fastest nucleation rate is predicted for mixed HIO 3 –HIO 2 clusters rather than for pure HIO 3 or HIO 2 ones. Our calculations reveal that the strong binding results from HIO 2 exhibiting a base behavior (accepting a proton from HIO 3 ) and forming stronger halogen bonds. Moreover, the binding energies of (HIO 3 ) m (HIO 2 ) n clusters show a far more tolerant choice of growth paths when compared with the strict stoichiometry required for sulfuric acid–base nucleation. Our predicted cluster formation rates and dimer concentrations are acceptably consistent with those measured by the Cosmic Leaving Outdoor Droplets (CLOUD) experiment. This study suggests that HIO 2 could facilitate the nucleation of other acids beyond HIO 3 in regions where base vapors such as ammonia or amines are scarce.

In this work, a certain amount of dopamine was firstly dissolved into the solution of poly(vinylidene fluoride) (PVDF) and then the fibrillar membranes were prepared through an electrospinning technology.

Among 160 organic NH-containing compounds (x = 1, 2) detected in the atmosphere, there are about 80 species for which the molecules contain p-π conjugate substructures of NH-π-bonds. Here, chlorine radical (·Cl)-initiated reactions for formamide, N-methylformamide, ethenamine, and aniline, as their cases, were investigated by a quantum chemical method [CCSD(T)/aug-cc-pVTZ//MP2/6-31+G(3df,2p)] and kinetics modeling. The calculated overall rate constants are 5.5 × 10, 2.3 × 10, 2.7 × 10, and 1.7 × 10 cm molecule s for formamide, N-methylformamide, ethenamine, and aniline, respectively, and agree well with experimental values for available ones. Importantly, the results show that the reactions of two amides with ·Cl mainly lead to C-center radicals via ·Cl abstracting the -CHO hydrogen of amides. However, both ethenamine + ·Cl and aniline + ·Cl reactions mainly produce delocalized radicals with the radical center on the C-site and N-site via a ·Cl addition and the -NH hydrogen abstraction pathway, respectively. Therefore, this study reveals that reactions of organic NH-containing compounds with ·Cl have various reaction mechanisms, in contrast to our previous understanding that -NH hydrogen abstraction pathways, leading to N-center radicals, are the most favorable. The unveiled reaction mechanisms should be of significance for the risk assessment of atmospheric organic NH-containing compounds and enriching ·Cl chemistry.