ABSTRACT
Both transcription and three-dimensional (3D) architecture of the mammalian genome play critical roles in neurodevelopment and its disorders. However, 3D genome structures of single brain cells have not been solved; little is known about the dynamics of single-cell transcriptome and 3D genome after birth. Here, we generated a transcriptome (3,517 cells) and 3D genome (3,646 cells) atlas of the developing mouse cortex and hippocampus by using our high-resolution multiple annealing and looping-based amplification cycles for digital transcriptomics (MALBAC-DT) and diploid chromatin conformation capture (Dip-C) methods and developing multi-omic analysis pipelines. In adults, 3D genome "structure types" delineate all major cell types, with high correlation between chromatin A/B compartments and gene expression. During development, both transcriptome and 3D genome are extensively transformed in the first post-natal month. In neurons, 3D genome is rewired across scales, correlated with gene expression modules, and independent of sensory experience. Finally, we examine allele-specific structure of imprinted genes, revealing local and chromosome (chr)-wide differences. These findings uncover an unknown dimension of neurodevelopment.
Subject(s)
Brain/growth & development , Genome , Sensation/genetics , Transcription, Genetic , Alleles , Animals , Animals, Newborn , Cell Lineage/genetics , Chromatin/metabolism , Gene Expression Regulation, Developmental , Gene Ontology , Gene Regulatory Networks , Genetic Loci , Genomic Imprinting , Mice , Multigene Family , Neuroglia/metabolism , Neurons/metabolism , Transcriptome/genetics , Visual Cortex/metabolismABSTRACT
Extra-axial cavernous hemangiomas (ECHs) are complex vascular lesions mainly found in the spine and cavernous sinus. Their removal poses significant risk due to their vascularity and diffuse nature, and their genetic underpinnings remain incompletely understood. Our approach involved genetic analyses on 31 tissue samples of ECHs employing whole-exome sequencing and targeted deep sequencing. We explored downstream signaling pathways, gene expression changes, and resultant phenotypic shifts induced by these mutations, both in vitro and in vivo. In our cohort, 77.4% of samples had somatic missense variants in GNA14, GNAQ, or GJA4. Transcriptomic analysis highlighted significant pathway upregulation, with the GNAQ c.626A>G (p.Gln209Arg) mutation elevating PI3K-AKT-mTOR and angiogenesis-related pathways, while GNA14 c.614A>T (p.Gln205Leu) mutation led to MAPK and angiogenesis-related pathway upregulation. Using a mouse xenograft model, we observed enlarged vessels from these mutations. Additionally, we initiated rapamycin treatment in a 14-year-old individual harboring the GNAQ c.626A>G (p.Gln209Arg) variant, resulting in gradual regression of cutaneous cavernous hemangiomas and improved motor strength, with minimal side effects. Understanding these mutations and their pathways provides a foundation for developing therapies for ECHs resistant to current therapies. Indeed, the administration of rapamycin in an individual within this study highlights the promise of targeted treatments in treating these complex lesions.
Subject(s)
GTP-Binding Protein alpha Subunits, Gq-G11 , GTP-Binding Protein alpha Subunits , Humans , GTP-Binding Protein alpha Subunits, Gq-G11/genetics , Animals , Mice , Female , Male , GTP-Binding Protein alpha Subunits/genetics , Mutation , Adult , Middle Aged , Signal Transduction , Hemangioma, Cavernous/genetics , Hemangioma, Cavernous/pathology , Adolescent , Exome Sequencing , Sirolimus/pharmacology , Sirolimus/therapeutic use , TOR Serine-Threonine Kinases/metabolism , TOR Serine-Threonine Kinases/geneticsABSTRACT
Recent advances in single-cell assay for transposase accessible chromatin using sequencing (scATAC-seq) and its coassays have transformed the field of single-cell epigenomics and transcriptomics. However, the low detection efficiency of current methods has limited our understanding of the true complexity of chromatin accessibility and its relationship with gene expression in single cells. Here, we report a high-sensitivity scATAC-seq method, termed multiplexed end-tagging amplification of transposase accessible chromatin (METATAC), which detects a large number of accessible sites per cell and is compatible with automation. Our high detectability and statistical framework allowed precise linking of enhancers to promoters without merging single cells. We systematically investigated allele-specific accessibility in the mouse cerebral cortex, revealing allele-specific accessibility of promotors of certain imprinted genes but biallelic accessibility of their enhancers. Finally, we combined METATAC with our high-sensitivity single-cell RNA sequencing (scRNA-seq) method, multiple annealing and looping based amplification cycles for digital transcriptomics (MALBAC-DT), to develop a joint ATAC-RNA assay, termed METATAC and MALBAC-DT coassay by sequencing (M2C-seq). M2C-seq achieved significant improvements for both ATAC and RNA compared with previous methods, with consistent performance across cell lines and early mouse embryos.
Subject(s)
Chromatin , Transposases , Animals , Chromatin/genetics , Mice , RNA , Sequence Analysis, DNA/methods , Single-Cell Analysis/methods , Transcriptome , Transposases/genetics , Transposases/metabolismABSTRACT
Current treatments of brain arteriovenous malformation (BAVM) are associated with considerable risks and at times incomplete efficacy. Therefore, a clinically consistent animal model of BAVM is urgently needed to investigate its underlying biological mechanisms and develop innovative treatment strategies. Notably, existing mouse models have limited utility due to heterogenous and untypical phenotypes of AVM lesions. Here we developed a novel mouse model of sporadic BAVM that is consistent with clinical manifestations in humans. Mice with BrafV600E mutations in brain ECs developed BAVM closely resembled that of human lesions. This strategy successfully induced BAVMs in mice across different age groups and within various brain regions. Pathological features of BAVM were primarily dilated blood vessels with reduced vascular wall stability, accompanied by spontaneous hemorrhage and neuroinflammation. Single-cell sequencing revealed differentially expressed genes that were related to the cytoskeleton, cell motility, and intercellular junctions. Early administration of Dabrafenib was found to be effective in slowing the progression of BAVMs; however, its efficacy in treating established BAVM lesions remained uncertain. Taken together, our proposed approach successfully induced BAVM that closely resembled human BAVM lesions in mice, rendering the model suitable for investigating the pathogenesis of BAVM and assessing potential therapeutic strategies.
Subject(s)
Intracranial Arteriovenous Malformations , Proto-Oncogene Proteins B-raf , Animals , Intracranial Arteriovenous Malformations/genetics , Intracranial Arteriovenous Malformations/pathology , Intracranial Arteriovenous Malformations/metabolism , Mice , Proto-Oncogene Proteins B-raf/genetics , Proto-Oncogene Proteins B-raf/metabolism , Mutation/genetics , Disease Models, Animal , Humans , Oximes/pharmacology , Imidazoles/pharmacology , Brain/pathology , Brain/metabolism , Brain/blood supply , Endothelium, Vascular/pathology , Endothelium, Vascular/metabolism , Mice, Transgenic , Mice, Inbred C57BLABSTRACT
Single-nucleotide variants (SNVs), pertinent to aging and disease, occur sporadically in the human genome, hence necessitating single-cell measurements. However, detection of single-cell SNVs suffers from false positives (FPs) due to intracellular single-stranded DNA damage and the process of whole-genome amplification (WGA). Here, we report a single-cell WGA method termed multiplexed end-tagging amplification of complementary strands (META-CS), which eliminates nearly all FPs by virtue of DNA complementarity, and achieved the highest accuracy thus far. We validated META-CS by sequencing kindred cells and human sperm, and applied it to other human tissues. Investigation of mature single human neurons revealed increasing SNVs with age and potentially unrepaired strand-specific oxidative guanine damage. We determined SNV frequencies along the genome in differentiated single human blood cells, and identified cell type-dependent mutational patterns for major types of lymphocytes.
Subject(s)
DNA Copy Number Variations , Leukocytes, Mononuclear/cytology , Neurons/cytology , Single-Cell Analysis/methods , Spermatozoa/cytology , Adult , Aged , Female , Genome, Human , High-Throughput Nucleotide Sequencing/methods , Humans , Leukocytes, Mononuclear/physiology , Male , Mutation , Neurons/physiology , Nucleic Acid Amplification Techniques/methods , Reproducibility of ResultsABSTRACT
Inherently chiral calix[4]arenes are an excellent structural scaffold for enantioselective synthesis, chiral recognition, sensing, and circularly polarized luminescence. However, their catalytic enantioselective synthesis remains challenging. Herein, we report an efficient synthesis of inherently chiral calix[4]arene derivatives via cascade enantioselective cyclization and oxidation reactions. The three-component reaction features a broad substrate scope (33â examples), high efficiency (up to 90 % yield), and excellent enantioselectivity (>95 % ee on average). The potential applications of calix[4]arene derivatives are highlighted by their synthetic transformation and a detailed investigation of their photophysical and chiroptical properties.
ABSTRACT
The development of multimode photopatterning systems based on supramolecular coordination complexes (SCCs) is considerably attractive in supramolecular chemistry and materials science, because SCCs can serve as promising platforms for the incorporation of multiple functional building blocks. Herein, we report a light-responsive liquid-crystalline metallacycle that is constructed by coordination-driven self-assembly. By exploiting its fascinating liquid crystal features, bright emission properties, and facile photocyclization capability, a unique system with spatially-controlled fluorescence-resonance energy transfer (FRET) is built through the introduction of a photochromic spiropyran derivative, which led to the realization of the first example of a liquid-crystalline metallacycle for orthogonal photopatterning in three-modes, namely holography, fluorescence, and photochromism.
ABSTRACT
Iron porphyrin carbenes (IPCs) have been extensively recognized as the reactive intermediates in various iron porphyrin-catalyzed carbene transfer reactions. While donor-acceptor diazo compounds have been frequently used for such transformations, the structures and reactivities of donor-acceptor IPCs are less explored. To date, no crystal structures of donor-acceptor IPC complexes have been reported, and therefore, the involvement of IPC intermediacy for such transformations lacks direct evidence. Here we report the synthesis and NMR characterization of several donor-acceptor IPC complexes from iron porphyrin and corresponding donor-acceptor diazo compounds. The X-ray crystal structure of an IPC complex derived from a morpholine-substituted diazo amide was obtained. The carbene transfer reactivities of those IPCs were tested by the N-H insertion reactions with aniline or morpholine as well as the three-component reaction with aniline and γ,δ-unsaturated α-keto ester based on electrophilic trapping of an ammonium ylide intermediate. Based on these results, IPCs were identified as the real intermediates for iron porphyrin-catalyzed carbene transfer reactions from donor-acceptor diazo compounds.
ABSTRACT
Due to the adverse health effects and the role in the formation of secondary organic aerosols, hydroxyl radical (OH) generation by atmospheric fine particulate matter (PM) has been of particular research interest in both bulk solutions and the gas phase. However, OH generation by PM at the air-water interface of atmospheric water droplets, a unique environment where reactions can be accelerated by orders of magnitude, has long been overlooked. Using the field-induced droplet ionization mass spectrometry methodology that selectively samples molecules at the air-water interface, here, we show significant oxidation of amphiphilic lipids and isoprene mediated by water-soluble PM2.5 at the air-water interface under ultraviolet A irradiation, with the OH generation rate estimated to be 1.5 × 1016 molecule·s-1·m-2. Atomistic molecular dynamics simulations support the counter-intuitive affinity for the air-water interface of isoprene. We opine that it is the carboxylic chelators of the surface-active molecules in PM that enrich photocatalytic metals such as iron at the air-water interface and greatly enhance the OH generation therein. This work provides a potential new heterogeneous OH generation channel in the atmosphere.
ABSTRACT
BACKGROUND: Phosphorus (P) and salt stress are common abiotic stressors that limit crop growth and development, but the response mechanism of soybean to low phosphorus (LP) and salt (S) combined stress remains unclear. RESULTS: In this study, two soybean germplasms with similar salt tolerance but contrasting P-efficiency, A74 (salt-tolerant and P-efficient) and A6 (salt-tolerant and P-inefficient), were selected as materials. By combining physiochemical and transcriptional analysis, we aimed to elucidate the mechanism by which soybean maintains high P-efficiency under salt stress. In total, 14,075 differentially expressed genes were identified through pairwise comparison. PageMan analysis subsequently revealed several significantly enriched categories in the LP vs. control (CK) or low phosphorus + salt (LPS) vs. S comparative combination when compared to A6, in the case of A74. These categories included genes involved in mitochondrial electron transport, secondary metabolism, stress, misc, transcription factors and transport. Additionally, weighted correlation network analysis identified two modules that were highly correlated with acid phosphatase and antioxidant enzyme activity. Citrate synthase gene (CS), acyl-coenzyme A oxidase4 gene (ACX), cytokinin dehydrogenase 7 gene (CKXs), and two-component response regulator ARR2 gene (ARR2) were identified as the most central hub genes in these two modules. CONCLUSION: In summary, we have pinpointed the gene categories responsible for the LP response variations between the two salt-tolerant germplasms, which are mainly related to antioxidant, and P uptake process. Further, the discovery of the hub genes layed the foundation for further exploration of the molecular mechanism of salt-tolerant and P-efficient in soybean.
Subject(s)
Antioxidants , Glycine max , Glycine max/genetics , Phosphorus/metabolism , Gene Expression Profiling , Transcription Factors/genetics , Stress, Physiological/genetics , Gene Expression Regulation, PlantABSTRACT
We propose a scheme for the creation of stable optical Ferris wheel (OFW) solitons in a nonlocal Rydberg electromagnetically induced transparency (EIT) medium. Depending on a careful optimization of both the atomic density and the one-photon detuning, we obtain an appropriate nonlocal potential provided by the strong interatomic interaction in Rydberg states that can perfectly compensate for the diffraction of the probe OFW field. Numerical results show that the fidelity remains larger than 0.96, while the propagation distance has exceeded 160 diffraction lengths. Higher-order OFW solitons with arbitrary winding numbers are also discussed. Our study provides a straightforward route to generate spatial optical solitons in the nonlocal response region of cold Rydberg gases.
ABSTRACT
BACKGROUND: We aimed to investigate the clinical characteristics of severe influenza virus-associated pneumonia complicated with bacterial infection in children. METHODS: We retrospectively analysed data concerning 64 paediatric patients with severe influenza virus-associated pneumonia who had been treated at our hospital. The patients were divided into observation (44 patients) and control (20 patients) groups, based on the presence or absence of concomitant bacterial infection, and clinical data were compared between the groups. RESULTS: The mean age in the observation group was 2.71 ± 1.44 years, 42 (95.45%) were aged ≤ 5 years, and 18 (40.9%) had underlying diseases. The mean age in the control group was 4.05 ± 2.21 years, 13 (65%) were aged ≤ 5 years, and 3 (15%) had underlying diseases. There was a statistically significant difference in patient age and the proportion of patients with underlying diseases (P < 0.05). The observation group had higher duration of fever values, a higher number of patients with duration of fever ≥ 7 days, a higher incidence of gasping, and a higher incidence of seizures/consciousness disturbance, and the differences were statistically significant (P < 0.05). Secondary bacterial infections in the observation group were mainly due to gram-negative bacteria, with Haemophilus influenzae and Moraxella catarrhalis being the most common pathogens. The observation group had a higher proportion of patients treated in the paediatric intensive care unit and a longer hospital stay, and the differences were statistically significant (P < 0.05). CONCLUSION: Severe influenza virus-associated pneumonia complicated with bacterial infection was more common in children aged ≤ 5 years. Younger patients with underlying diseases were more susceptible to bacterial infection (mainly due to gram-negative bacteria). The timely administration of neuraminidase inhibitors and antibiotics against susceptible bacteria is likely to help improve cure rates.
Subject(s)
Bacterial Infections , Coinfection , Influenza, Human , Orthomyxoviridae , Humans , Child , Infant , Child, Preschool , Retrospective Studies , Bacterial Infections/complications , Bacterial Infections/epidemiology , Anti-Bacterial Agents/therapeutic use , Antiviral Agents , Coinfection/epidemiology , Influenza, Human/complicationsABSTRACT
Herein, we report a KOtBu-catalysed α-homoallylic alkylation of acyclic amides with 1-aryl-1,3-dienes. With this transition metal-free and atom-economic protocol, a series of α-homoallylic alkylated acyclic amides were synthesized in good to excellent yields. This transformation is proposed to proceed through a cation-π interaction-based C-C bond formation from the in situ-generated potassium enolate with the diene unit.
Subject(s)
Amides , Carboxylic Acids , Molecular Structure , Amides/chemistry , Polyenes , AlkylationABSTRACT
BACKGROUND: The goal was to investigate the inhibitory effect of formononetin, an active component in Astragalus membranaceus, on the pathogenesis and development of esophageal cancer and the mechanism of action. METHODS: The expression of COX-2 in cancer tissue and paracancerous tissue of patients with esophageal cancer detected early. C57BL/6 mice were used to construct a 4-nitroquinoline 1-oxide (4-NQO)-induced esophageal cancer model to verify the inhibitory effect of formononetin on the pathogenesis of esophageal cancer. Additionally, human esophageal cancer cells were treated with formononetin, and the effects on the proliferation and cell cycle of esophageal cancer cells were assessed by the CCK-8 assay and flow cytometry. Changes in the expression levels of cyclin D1 and COX-2 mRNA in cells were detected by RT-qPCR and western blot (WB) analysis. RESULTS: The expression level of COX-2 mRNA in esophageal cancer tissue was significantly higher than that in paracancerous tissue. In the mouse cancer model, the incidence of esophageal cancer in mice in the formononetin treatment group was significantly reduced at week 18 (0/15 vs. 2/15) and at week 24 (6/15 vs. 13/15) (all p < 0.05). Formononetin significantly inhibited the proliferation ability of KYSE170 and KYSE150 cells and inhibited the protein expression of COX-2 and cyclin D1 (both p < 0.05). CONCLUSIONS: Formononetin, an active component of Astragalus membranaceus, can prevent the pathogenesis and progression of esophageal cancer by reducing the expression of the inflammatory proteins COX-2 and cyclin D1.
Subject(s)
Astragalus propinquus , Esophageal Neoplasms , Humans , Animals , Mice , Cyclooxygenase 2/pharmacology , Cell Proliferation , Cyclin D1/genetics , Cyclin D1/pharmacology , Mice, Inbred C57BL , Cell Line, TumorABSTRACT
BACKGROUND: The risk factors for mucus plug in children with adenovirus (ADV) pneumonia. METHODS AND MATERIALS: A retrospective analysis was conducted of children diagnosed ADV pneumonia and underwent fiberoptic bronchoscopy admitted to the Xiamen Children's Hospital from September 2018 to September 2021.The patients were divided into a mucus plug group (39 cases) and a non-mucus plug group (53 cases). The children's data including sex, age, clinical presentation, laboratory test parameters, imaging and bronchoscopic data were collected. The risk factors for the development of airway mucus plug were analysed by multifactorial logistic regression. RESULTS: There were no statistically significant differences in sex, age, fever, hospitalization days, mixed infection, white blood cells (WBC) count, percentage of neutrophils (NE%), C-reactive protein(CRP), and D-dimer (all P > 0.05); Thermal range, procalcitonin (PCT), lactate dehydrogenase (LDH), Pleural effusion and associated decreased breath sounds was significantly higher in mucus plug group than in non-mucus plug group, and the differences were statistically significant (all P < 0.05); multifactorial logistic regression analysis showed that the duration of fever, PCT, and LDH were independent risk factors for the formation of mucus plugs. The critical values of ROC curves were pyroprocedure ≥ 6.5 d, PCT ≥ 0.705 ng/ml and LDH ≥ 478.5 U/L. CONCLUSION: Duration of fever, PCT and LDH levels were the independent risk factors for the formation of an airway mucus plug in children with ADV pneumonia.
Subject(s)
Pneumonia, Mycoplasma , Pneumonia, Viral , Humans , Child , Retrospective Studies , Risk Factors , MucusABSTRACT
Context: With the rapidly aging population globally, osteoporosis (OP) has become a major public health problem, and fracture is a common complication of OP. Older adults, especially postmenopausal women, have a higher incidence of OP. Objective: The study intended to analyze the clinical information, epidemiological characteristics, treatments, and follow-up results of patients with osteoporotic fractures (OPFs) in adults over 65 years old, to provide data support for the prevention, treatment, and use of OPF focus groups in clinical practice. Design: The research team performed a retrospective analysis using electronic medical records and related imaging data of patients. Setting: The study took place at Hebei General Hospital in Hebei, China. Participants: Participants were 387 patients over 65 years old with osteoporotic fractures who had been admitted to the hospital between July 2012 and July 2018. Outcome Measures: The research team recorded participants' ages, genders, fracture causes, and fracture sites. The team performed a follow-up analysis on refractures, treatment with anti-osteoporotic drugs, exercise, and survival status within the 3 years after surgery. Results: The study's male-to-female ratio was 1:3.1, and the rate of osteoporotic fracture for females was significantly higher than that of males. The mean age of participants with fractures was 75.6 ± 8.5 years, and most fractures occurred in participants 78 to 85 years old. Of the 387 participants, 169 participants had hip fractures (43.67%); 98 had vertebral compression fractures (25.32%); 51 had distal radius and ulna fractures (13.18%); 42 had proximal humerus fractures (10.85%); and 27 had other fractures (6.98%). The number of women with fractures at each site was greater than the number of men, but the differences weren't statistically significant (P > .05). The main causes of injury were falls (71.58%), and the main place of the occurrence of injury was at home (65.6%). Of the 387 participants, 346 had surgical treatment (89.41%), and the effective rate of surgical treatment was 99.42%. Three years after surgery, the research team followed up with 235 participants, for a follow-up rate of 60.72%. Within the 3 years of the follow-up period, 61 participants had refractures (25.63%), 29 received treatment with regular anti-osteoporotic drugs (12.34%), 36 exercised twice or more a week (15.32%), and 32 had died for various reasons (13.62%). Conclusions: The study preliminarily described the epidemiological characteristics of 387 osteoporotic fractures in adults over 65 years old. More women had fractures than men; the hip was the most common fracture site, and falls were the main cause of injury. Most of the fractures occurred in the place of residence, and the refracture rate was 25.96% at three years after surgery.
Subject(s)
Fractures, Compression , Osteoporosis , Osteoporotic Fractures , Spinal Fractures , Female , Humans , Male , Aged , Aged, 80 and over , Osteoporotic Fractures/epidemiology , Osteoporotic Fractures/surgery , Retrospective Studies , Osteoporosis/complications , Osteoporosis/epidemiology , Osteoporosis/drug therapyABSTRACT
Targeted protein degradation (TPD) provides unprecedented opportunities for drug discovery. While the proteolysis-targeting chimera (PROTAC) technology has already entered clinical trials and changed the landscape of small-molecule drugs, new degrader technologies harnessing alternative degradation machineries, especially lysosomal pathways, have emerged and broadened the spectrum of degradable targets. We have recently proposed the concept of autophagy-tethering compounds (ATTECs) that hijack the autophagy protein microtubule-associated protein 1A/1B light chain 3 (LC3) for targeted degradation. Other groups also reported degrader technologies engaging lysosomal pathways through different mechanisms including AUTACs, AUTOTACs, LYTACs and MoDE-As. In this review, we analyse and discuss ATTECs along with other lysosomal-relevant degrader technologies. Finally, we will briefly summarize the current status of these degrader technologies and envision possible future studies.
Subject(s)
Drug Discovery , Proteins , Proteolysis , Proteins/metabolism , Autophagy , Lysosomes/metabolismABSTRACT
Objective: To investigate the effect of high-flow nasal cannula (HFNC) and Oxygen Nebuliser mask (ONM) on patients recovering from inhalation anesthesia. Methods: A retrospective analysis was performed on 128 patients after inhalation of general anesthesia in the recovery room of the Anesthesiology Department of The Fourth Hospital of Hebei Medical University from September 2019 to September 2021. All patients received the same anesthesia induction and analgesia methods, inhalation anesthesia or intravenous-inhalation anesthesia maintenance, recovered spontaneous breathing and removed endotracheal intubation after surgery, then were divided into HFNC group and ONM group for oxygen therapy. HFNC setting mode: flow rate: 20-60 L/minutes, humidification temperature: 37°C, the oxygen concentration was adjusted to maintain finger pulse oxygen saturation SPO2>90%; ONM group, the oxygen flow rate was adjusted to maintain finger pulse oxygen saturation SPO2>90%. All patients in the two groups were compared immediately after they entered the recovery room for 0 minutes,, 10 minutes, and 20 minutes,, including tidal volume, blood gas, Richmond Agitation-Sedation Scale (RASS) score and time from sedation to awakening. Results: The changes in tidal volume, oxygenation index and RASS score over time in the HFNC group were higher than those in the ONM group (p<0.05), and the awakening time in the HFNC group was faster than that in the ONM group (p<0.01), with significant statistical differences. Conclusions: Compared with ONM, HFNC can shorten postoperative recovery time, reduce the incidence of agitation and improve lung function and oxygenation state during recovery from anesthesia.
ABSTRACT
Water serves as an inert environment for the dispersion and application of many kinds of herbicides. Viologen compounds, a type of widely used but highly toxic herbicide, are stable in bulk water, whose half-life can be up to 23 weeks in natural water, imposing a severe health risk to mammals. In this study, we present the striking results of the spontaneous and ultrafast reduction-induced degradation of three viologen compounds in water microdroplets and provide the concentration, time, temperature dependence, mechanism, and scale-up of the reactions. We postulate that the electrons existing at the air-water interface of the microdroplets due to the unique redox potential therein initiate the reduction, from which further degradation occurs. The host-guest complexation between cucurbit[7]uril and viologens only slightly changes the redox potential of viologens in the bulk but completely inhibits the reactions in microdroplets, adding to the uniqueness of the redox potentials at the air-water interfaces of microdroplets. Taken together, microdroplets might have been functioning as naturally occurring ubiquitous tiny electrochemical cells for a plethora of unique redox reactions that were thought to be impossible in the bulk water.
Subject(s)
Viologens , Water , Animals , Mammals , Oxidation-Reduction , Temperature , Viologens/chemistry , Water/chemistryABSTRACT
The multiphase oxidation of SO2 to sulfate in aerosol particles is a key process in atmospheric chemistry. However, there is a large gap between the observed and simulated sulfate concentrations during severe haze events. To fill in the gaps in understanding SO2 oxidation chemistry, a combination of experiments and theoretical calculations provided evidence for the direct, spin-forbidden excitation of SO2 to its triplet states using UVA photons at an air-water interface, followed by reactions with water and O2 that facilitate the rapid formation of sulfate. The estimated reaction energy for the whole process, 3SO2 + H2O + 1/2O2 â HSO4- + H+ (298 K, 1 M), was ΔGr = -107.8 kcal·mol-1. Moreover, calculations revealed that this was a multistep reaction involving submerged, small energy barriers (â¼10 kcal·mol-1). These results indicate that photochemical oxidation of SO2 at the air-water interface with solar actinic light may be an important unaccounted source of sulfate aerosols under polluted haze conditions.