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We present experimental evidence for the spontaneous production of hydrogen peroxide (H2O2) at the liquid–ice interface during the freezing of dilute salt solutions. Specifically, sample solutions containing NaCl, NaBr, NH4Cl, and NaI at concentrations between 10–6and 10–1M were subjected to freezing–melting cycles and then analyzed for H2O2content. The relationship between the production rate of H2O2and the salt concentration follows that of the Workman–Reynolds freezing potential (WRFP) values as a function of the salt concentration. Our results suggest that H2O2is formed at the liquid–ice interface from the self-recombination of hydroxyl radicals (OH·), produced from the oxidation of hydroxide anions due to the high electric field generated at the aqueous–ice interface under the WRFP effect. Furthermore, the involvement of O2likely acting as an electron capturer could promote to produce more OH radicals and hydroperoxyl radicals (HO2·), thus enhancing the production of H2O2at the liquid–ice interface. Overall, this study suggests a novel mechanism of H2O2formation in ice via its spontaneous production at the liquid–ice interface, induced by the Workman–Reynolds effect.

Most bankers understand the major chapters of the bankruptcy code: Chapter 7 (liquidation) and Chapter 11 (reorganization). But what about the relatively new Subchapter V form of bankruptcy? Enacted just [...]

In subarctic regions, rising temperature and permafrost thaw lead to the formation of thermokarst ponds, where organics from eroding permafrost accumulate. Despite its environmental significance, limited knowledge exists regarding the photosensitivity of permafrost-derived carbon in these ponds. In this study, laboratory experiments were conducted to explore the photochemical transformations of organic matter in surface water samples from thermokarst ponds from different environments in northern Quebec, Canada. One pond near Kuujjuarapik is characterized by the presence of a collapsing palsa and is therefore organically rich, while the other pond near Umiujaq is adjacent to a collapsing lithalsa and thus contains fewer organic matters. Photobleaching occurred in the Umiujaq sample upon irradiation, whereas the Kuujjuarapik sample exhibited an increase in light absorbance at wavelength related to aromatic functionalities, indicating different photochemical aging processes. Ultrahigh-resolution mass spectrometry analysis reveals that the Kuujjuarapik sample preferentially photoproduced highly unsaturated CHO compounds with great aromaticity, while the irradiated Umiujaq sample produced a higher proportion of CHON aromatics with reduced nitrogen functionalities. Overall, this study illustrates that the photochemical reactivity of thermokarst pond water varies with the source of organic matter. The observed differences in reactivity contribute to an improved understanding of the photochemical emission of volatile organic compounds discovered earlier. Further insights into the photoinduced evolutions in thermokarst ponds may require the classification of permafrost-derived carbon therein.

Recent studies have shown that the air–water interface of aqueous microdroplets is a source of OH radicals and hydrogen peroxide in the atmosphere. Several parameters such as droplet size, salt, and organic content have been suggested to play key roles in the formation of these oxidants. In this study, we focus on the effect of acidity on the spontaneous interfacial hydrogen peroxide formation of salt-containing droplets. Na2SO4, NaCl, and NaBr bulk solutions, at the range of pH 4 to 9.5, were nebulized, using ultra high-purity N2/O2(80%/20%), and H2O2was measured in the collected droplets. All of the experiments were performed in T= 292 ± 1 K and humidity levels of 90 ± 2%. For Na2SO4and NaCl, the H2O2concentration was increased by ∼40% under alkaline conditions, suggesting that OH–enriched environments promote its production. When CO2was added in the ultrapure air, H2O2was observed to be lower at higher pH. This suggests that dissolved CO2can initiate reactions with OH radicals and electrons, impacting the interfacial H2O2production. H2O2formation in NaBr droplets did not display any dependence on the pH or the bath gas, showing that secondary reactions occur at the interface in the presence of Br–, which acts as an efficient interfacial source of electrons.

Several groups have recently reported spontaneous production of atmospherically reactive species, including molecular iodine (I2) at the air–water interface of droplets. In this study, glancing angle laser-induced fluorescence spectroscopy was used to track the luminol fluorescence at the surface of sodium iodide (NaI) and sodium chloride (NaCl) solutions. Although luminol fluorescence is hardly quenched by halide anions, even up to fairly high concentrations, it is effectively quenched by I2. We observe luminol fluorescence quenching at the surface of NaI solutions but not at the surface of NaCl solutions, pointing to the formation of I2at the surface of NaI solutions. This provides further support for the proposal that the strong electric field or the reduction solvation present at the air–water interface can initiate spontaneous iodide activation and other chemistry there. The spontaneous production of I2at the surface of aqueous iodide solutions presents a previously unconsidered source of iodine in the atmosphere.

The impact of water-soluble atmospheric iron on formation, growth and aging of secondary organic aerosol (SOA) is a controversial subject in the literature. Iron chemistry drives Fenton reactions in the aqueous phase which is dependent on pH. Flow reactor experiments in the dark and under humid conditions were conducted to investigate systematically the influence of ferrous iron in the aqueous phase on α-pinene SOA by online physical analysis and offline high-resolution mass spectrometry. During the experiments increased SOA formation under conditions favorable for dark Fenton chemistry in the aqueous phase was observed. Furthermore, samples with an acidified and iron-containing aqueous phase showed a degradation of pinyl-diaterpenyl (C17H26O8) ester which ages through oxidation viaOH radicals and can thus be evidence for ongoing degradation processes of high molecular weight molecules by iron chemistry. Moreover, higher abundance of dimer MW338 (C19H30O5) in the acidic sample affected by Fenton's chemistry was detected which is suggested to be formed viaacid catalysis indicating competing acidity-driven reactions influencing SOA formation. Therefore, this study provides insight into the impact of aqueous phase iron on SOA formation and transformation under simulated natural conditions.

This study explores the potential contribution of secondary production of OH radicals in aerosols and cloud/fog conditions arising from brown carbon (BrC) triplet state chemistry. For this purpose, extracts of brown carbon from atmospheric aerosols from Grenoble, France, were analyzed for their ability to produce triplet states from the degradation of a common triplet state probe, 2,4,6-trimethylphenol (TMP). This ability of brown carbon to produce triplet states was compared to that of three photosensitizers, where it was found that vanillin (VL) showed a similar rate of degradation of the probe and was hence chosen as an alternative to BrC in aqueous aerosols to investigate OH formation from triplet states. The rates of OH formation from the triplet states were compared to those from nitrate anions (NO3−) and hydrogen peroxide (H2O2), which are well-known sources of OH radicals in the aqueous phase, and a species that is structurally similar to VL, 4-hydroxybenzaldehyde (4HB). VL and 4HB both showed a 1–2 orders of magnitude higher rate of secondary OH formation than NO3−, while it was similar or one order of magnitude smaller than H2O2. To evaluate the influence of the different OH radical sources in aqueous aerosols and cloud/fog conditions, the concentrations of the species were summarized from the literature. Considering the concentrations of HULISs in aerosols, the rates of secondary OH formation from BrC triplet states could potentially represent a significant source of OH in the atmospheric aqueous phase under some circumstances. This study shows the relevance of further investigations into the role of triplet states in impacting atmospheric oxidative capacity and studying other effects of triplet states in aerosols, a field that is, until now, still not fully understood.

Mitigating ammonia (NH3) emissions is a significant challenge, given its well-recognized role in the troposphere, contributing to secondary particle formation and impacting acid rain. The difficulty arises from the highly uncertain attribution of atmospheric NH3to specific emission sources, especially when accounting for diverse environments and varying spatial and temporal scales. In this study, we established a refined δ15N fingerprint for eight emission sources, including three previously overlooked sources of potential importance. We applied this approach in a year-long case study conducted in urban and rural sites located only 40 km apart in the Shandong Peninsula, North China Plain. Our findings highlight that although atmospheric NH3concentrations and seasonal trends exhibited similarities, their isotopic compositions revealed significant distinctions in the primary NH3sources. In rural areas, although agriculture emerged as the dominant emission source (64.2 ± 19.5%), a previously underestimated household stove source also played a considerably greater role, particularly during cold seasons (36.5 ± 12.5%). In urban areas, industry and traffic (33.5 ± 15.6%) and, surprisingly, sewage treatment (27.7 ± 11.3%) associated with high population density were identified as the major contributors. Given the relatively short lifetime of atmospheric NH3, our findings highlight the significance of the isotope approach in offering a more comprehensive understanding of localized and seasonal influences of NH3sources compared to emissions inventories. The refined isotopic fingerprint proves to be an effective tool in distinguishing source contributions across spatial and seasonal scales, thereby providing valuable insights for the development of emission mitigation policies aimed at addressing the increasing NH3burden on the local atmosphere.

Recently, secondary organic aerosols (SOAs) emerged as a predominant component of fine particulate matter. However, the pathogenic mechanism(s) of SOAs are still poorly understood. Herein, we show that chronic exposure of mice to SOAs resulted in lung inflammation and tissue destruction. Histological analyses found lung airspace enlargement associated with massive inflammatory cell recruitment predominated by macrophages. Concomitant with such cell influx, our results found changes in the levels of a series of inflammatory mediators in response to SOA. Interestingly, we observed that the expression of the genes encoding for TNF-α and IL-6 increased significantly after one month of exposure to SOAs; mediators that have been largely documented to play a role in chronic pulmonary inflammatory pathologies. Cell culture studies confirmed these in vivofindings. Of importance as well, our study indicates increased matrix metalloproteinase proteolytic activity suggesting its contribution to lung tissue inflammation and degradation. Our work represents the first in vivostudy, which reports that chronic exposure to SOAs leads to lung inflammation and tissue injury. Thus, we hope that these data will foster new studies to enhance our understanding of the underlying pathogenic mechanisms of SOAs and perhaps help in the design of therapeutic strategies against SOA-mediated lung injury.

Nitrogen-containing organic compounds (NOCs) in frost serve as a critical pathway for atmospheric nitrogen deposition, significantly impacting the biogeochemical cycles of nitrogen. However, the molecular characteristics of NOCs in frost and their deposition fluxes are scarcely studied. In this work, frost samples, collected in rural Northeast China in the winter of 2023, were analyzed using nontargeted ultrahigh performance liquid chromatography-orbitrap mass spectrometry (UHPLC-Orbitrap MS) to reveal their content in nitrogen-containing organic compounds (NOCs) and explore their wet deposition fluxes. The average number of assigned molecular formulas were lager on hazy days compared to nonhazy days for both water-soluble (WSOM) and water-insoluble organic matter (WISOM) in frost (3114 vs.1934 for WSOM and 3042 vs. 2224 for WISOM in electrospray ionization (ESI−); 6921 vs. 5954 for WSOM and 6629 vs.5547 in ESI+). Specifically, the number proportions of CHON were 35.6–49.9% (724–1517) and 47–51.1% (2686–3388) in the ESI– and ESI+ modes, respectively. Nitrophenol (C6H5NO3) and methyl nitrophenol (C7H7NO4) were the most abundant NOCs, with wet deposition fluxes (at maximum average concentrations) of 22.2 and 21.2 μg m–2·h–1, respectively. On hazy days, the deposition fluxes of nitrophenol compounds reached up to 1.73 times that of nonhazy days, indicating significant ambient nitrogen deposition during the haze episode. This deposition flux positively correlated with PM2.5concentration, implying the important role of atmospheric particulates in influencing NOC deposition through frost. These findings highlight the susceptibility of frost to capturing NOCs from the atmosphere, potentially impacting nitrogen cycling in ecosystems.

The health effects associated with ultrafine particles (UFPs) have received significant attention. Precisely identifying the sources of UFPs and quantifying their contributions pose considerable challenges. In this study, simultaneous observations were conducted at two suburban sites in Shanghai, a megacity in China, to measure the particle number size distributions (PNSD) and investigate the characteristics of UFPs. The application of the non-negative matrix factorization (NMF) algorithm on PNSD determines 5 factors at each site. The sources of UFPs are very different between the inland (Dianshan Lake, DSL) site and the seacoast (Dongtan, DT) site. By analyzing size distributions and daily variations of resolved factors, and examining their relationships with criteria pollutants and PM2.5(particulate matter with diameters ≤2.5 μm) chemical compositions, we identify the main sources of UFPs. At the DSL site, fresh and aged traffic emissions and traffic nucleation are the main contributors to UFPs. At the DT site, photochemical nucleation and growth processes and marine ship emissions are the most important UFP sources. Industrial emissions and the regional background are characterized by a larger GMD (geometric mean diameter) and contribute more to particle volume concentrations (PVC) rather than particle number concentrations (PNC), indicating their association with PM2.5rather than UFPs. These findings emphasize the underlying reasons why UFPs and PM2.5belong to two different metrics. Concerning the respiratory deposition of particles, the main UFPs sources also pose the greatest health risk. Either during clean days (PM2.5< 35 μg m−3) or during polluted days (PM2.5> 35 μg m−3), PNCDepositsonly varies slightly. And photochemical nucleation (i.e., new particle formation events) can significantly increase PNC deposited in the respiratory system.

The formation of secondary brown carbon (BrC) is chemically complex, leading to an unclear relationship between its molecular composition and optical properties. Here, we present an in-depth investigation of molecular-specific optical properties and aging of secondary BrC produced from the photooxidation of ethylbenzene at varied NOxlevels for the first time. Due to the pronounced formation of unsaturated products, the mass absorption coefficient (MAC) of ethylbenzene secondary organic aerosols (ESOA) at 365 nm was higher than that of biogenic SOA by a factor of 10. A high NOxlevel ([ethylbenzene]0/[NOx]0< 10 ppbC ppb–1) was found to significantly increase the average MAC300–700nmof ESOA by 0.29 m2g–1. The data from two complementary high-resolution mass spectrometers and quantum chemical calculations suggested that nitrogen-containing compounds were largely responsible for the enhanced light absorption of high-NOxESOA, and multifunctional nitroaromatic compounds (such as C8H9NO3and C8H9NO4) were identified as important BrC chromophores. High-NOxESOA underwent photobleaching upon direct exposure to ultraviolet light. Photolysis did not lead to the significant decomposition of C8H9NO3and C8H9NO4, indicating that nitroaromatic compounds may serve as relatively stable nitrogen reservoirs and would effectively absorb solar radiation during the daytime.

The Florida Bar Young Lawyers Division enjoyed a productive and rewarding year. Due to the strength of the governors throughout Florida, the YLD accomplished all the goals established by our [...]

Understanding customer expectations is key in any service context, including indentifying the differences between customer segments. Nonetheless, they remain underresearched topics in the airport industry, with limited empirical evidence on the nature of passenger expectations and how they relate to the service experienced. Therefore, the objectives of this research were twofold: first, to estimate a structural model of the relationships between customer expectations and airport service quality dimensions; second, to examine the differences between groups of passengers. Sample data from a survey administered to passengers at one of Brazil’s largest airports, in São Paulo, were used for structural equation modeling analyses. The results provided models with a good fit to the data. The findings for nonfrequent passengers showed that the effects of expectations on airport service quality were significant for all the service quality dimensions examined, whereas frequent passengers only revealed a significant relationship between expectation and the “processes” dimension. Theoretical and practical contributions to airport planning and management are discussed in light of the findings.

Particulate nitrite is a critical source of hydroxyl radicals; however, it lacks high-resolution methods due to its low abundance and stability to explore its formation mechanism. In this study, a modified versatile aerosol concentration enrichment system (VACES) coupled with ion chromatography (IC) was used to measure particulate NO2–hourly online and achieve a lowered detection limit of 10–3μg m–3. VACES-IC was used to observe a high- and low-concentration events of PM1.0-NO2–in Shanghai, corresponding to the ambient-level concentrations of 0.34 and 0.05 μg m–3, respectively. The morning peak concentrations of NO2–even exceeded 3σ (standard deviation) in the high-concentration event due to the reduction of NO2by aerosol SO32–based on kinetics and regression analysis. This implies that controlling SO2emissions would be an effective strategy to decrease morning NO2–concentrations, correspondingly reducing the kinetic formation of SO42–by 20.8–34.8%. However, after sunrise, NO2–formation was primarily attributed to NO2hydrolysis at pH 4.97–6.14. In the low-concentration event, NO2hydrolysis also accounted for an overwhelming proportion (∼90%) of NO2–formation. This work estimates the contribution of different paths to particulate NO2–formation based on newly established high-resolution measurements.

Brown carbon (BrC) is involved in atmospheric light absorption and climate forcing and can cause adverse health effects. Understanding the formation mechanisms and molecular structure of BrC is of key importance in developing strategies to control its environment and health impact. Structure determination of BrC is challenging, due to the lack of experiments providing molecular fingerprints and the sheer number of molecular candidates with identical mass. Suggestions based on chemical intuition are prone to errors due to the inherent bias. We present an unbiased algorithm, using graph-based molecule generation and machine learning, which can identify all molecular structures of compounds involved in biomass burning and the composition of BrC. We apply this algorithm to C12H12O7, a light-absorbing “test case” molecule identified in chamber experiments on the aqueous photo-oxidation of syringol, a prevalent marker in wood smoke. Of the 260 million molecular graphs, the algorithm leaves only 36,518 (0.01%) as viable candidates matching the spectrum. Although no unique molecular structure is obtained from only a chemical formula and a UV/vis absorption spectrum, we discuss further reduction strategies and their efficacy. With additional data, the method can potentially more rapidly identify isomers extracted from lab and field aerosol particles without introducing human bias.

Nighttime oxidation of biogenic volatile organic compounds (BVOCs) by nitrate radicals (NO3·) represents one of the most important interactions between anthropogenic and natural emissions, leading to substantial secondary organic aerosol (SOA) formation. The direct climatic effect of such SOA cannot be quantified because its optical properties and atmospheric fate are poorly understood. In this study, we generated SOA from the NO3· oxidation of a series BVOCs including isoprene, monoterpenes, and sesquiterpenes. The SOA were subjected to comprehensive online and offline chemical composition analysis using high-resolution mass spectrometry and optical properties measurements using a novel broadband (315–650 nm) cavity-enhanced spectrometer, which covers the wavelength range needed to understand the potential contribution of the SOA to direct radiative forcing. The SOA contained a significant fraction of oxygenated organic nitrates (ONs), consisting of monomers and oligomers that are responsible for the detected light absorption in the 315–400 nm range. The SOA created from β-pinene and α-humulene was further photochemically aged in an oxidation flow reactor. The SOA has an atmospheric photochemical bleaching lifetime of >6.2 h, indicating that some of the ONs in the SOA may serve as atmosphere-stable nitrogen oxide sinks or reservoirs and will absorb and scatter incoming solar radiation during the daytime.

AbstractMunicipal water and wastewater utility systems are experiencing several issues related to an aging workforce. Of particular importance, is the technical knowledge drain generated when the experienced operational workforce retires. It is important to transfer their knowledge into the organization for the future success of system operability. Recent investigations highlight the importance of, and the methods for, knowledge transfer, however, the current literature does not include significant information on the municipal utility industry. The objective of this descriptive research is to assess how municipal utility organizations transfer their operational knowledge. A qualitative case study research approach was used to evaluate operational knowledge transfer in six municipal utility organizations. The results indicate that five methods are commonly used in municipal utility organizations; however, there are some methods that are used more than others depending on the operational learning situation. Engineering managers can use this paper as a guide in the design of custom knowledge management programs in municipal utility organizations. These results can inform future investigations in the areas of knowledge management and knowledge transfer.

Current mass spectrometry techniques for the online measurement of organic aerosol (OA) composition are subjected to either thermal/ionization-induced artifacts or limited mass resolving power, hindering accurate molecular characterization. Here, we combined the soft ionization capability of extractive electrospray ionization (EESI) and the ultrahigh mass resolution of Orbitrap for real-time, near-molecular characterization of OAs. Detection limits as low as tens of ng m–3with linearity up to hundreds of μg m–3at 0.2 Hz time resolution were observed for single- and mixed-component calibrations. The performance of the EESI-Orbitrap system was further evaluated with laboratory-generated secondary OAs (SOAs) and filter extracts of ambient particulate matter. The high mass accuracy and resolution (140 000 at m/z200) of the EESI-Orbitrap system enable unambiguous identification of the aerosol components’ molecular composition and allow a clear separation between adjacent peaks, which would be significantly overlapping if a medium-resolution (20 000) mass analyzer was used. Furthermore, the tandem mass spectrometry (MS2) capability provides valuable insights into the compound structure. For instance, the MS2analysis of ambient OA samples and lab-generated biogenic SOAs points to specific SOA precursors in ambient air among a range of possible isomers based on fingerprint fragment ions. Overall, this newly developed and characterized EESI-Orbitrap system will advance our understanding of the formation and evolution of atmospheric aerosols.

Northern China is regularly subjected to intense wintertime “haze events”, with high levels of fine particles that threaten millions of inhabitants. While sulfate is a known major component of these fine haze particles, its formation mechanism remains unclear especially under highly polluted conditions, with state-of-the-art air quality models unable to reproduce or predict field observations. These haze conditions are generally characterized by simultaneous high emissions of SO2and photosensitizing materials. In this study, we find that the excited triplet states of photosensitizers could induce a direct photosensitized oxidation of hydrated SO2and bisulfite into sulfate S(VI) through energy transfer, electron transfer, or hydrogen atom abstraction. This photosensitized pathway appears to be a new and ubiquitous chemical route for atmospheric sulfate production. Compared to other aqueous-phase sulfate formation pathways with ozone, hydrogen peroxide, nitrogen dioxide, or transition-metal ions, the results also show that this photosensitized oxidation of S(IV) could make an important contribution to aerosol sulfate formation in Asian countries, particularly in China.

I was very surprised to see a picture of my living room inundated with a few feet of water on the cover of the October 1 News. While it is [...]

Atmospheric brown carbon (BrC) is an important contributor to the radiative forcing of climate by organic aerosols. Because of the molecular diversity of BrC compounds and their dynamic transformations, it is challenging to predictively understand BrC optical properties. OH radical and O3reactions, together with photolysis, lead to diminished light absorption and lower warming effects of biomass burning BrC. The effects of night-time aging on the optical properties of BrC aerosols are less known. To address this knowledge gap, night-time NO3radical chemistry with tar aerosols from wood pyrolysis was investigated in a flow reactor. This study shows that the optical properties of BrC change because of transformations driven by reactions with the NO3radical that form new absorbing species and lead to significant absorption enhancement over the ultraviolet–visible (UV-vis) range. The overnight aging increases the mass absorption coefficients of the BrC by a factor of 1.3–3.2 between 380 nm and 650 nm. Nitrated organic compounds, particularly nitroaromatics, were identified as the main products that contribute to the enhanced light absorption in the secondary BrC. Night-time aging of BrC aerosols represents an important source of secondary BrC and can have a pronounced effect on atmospheric chemistry and air pollution.

We investigated the impact of organic matter and mineral particles on atmospheric ice freezing to better understand the mechanisms of nucleation and crystal growth. Differential scanning calorimetry (DSC) and optical cryomicroscopy have been used to investigate liquid–solid transitions of citric acid aqueous solutions in the presence of 1 wt % of Arizona Test Dust (ATD). These two methods have led to complementary results: DSC enables the quantification of the latent heat and phase transitions, while optical cryomicroscopy allows the in situ observation of freezing phenomena and ice growth rates. Different trends have been observed: (i) ATD facilitates the crystallization by acting as nuclei center (NC), the supercooling level decreases around 6 °C in the presence of ATD; (ii) ice crystallization is affected by the citric acid mass fraction: for concentrations over 50 wt %, crystallization does not systematically appear during the cooling phase but during the warming phase, which highlights an amorphous organization; (iii) there is a threshold of citric acid concentration (around 30 wt %) beyond which the ice growth rate significantly decreases. In this work, we have shown that the crystal morphology is linked to the citric acid concentration and evolves from one nucleation monosite with continuous framework for low concentrations to multiple sites with multibranching pattern at high concentrations. A mathematical model is proposed as a first step in the modeling of ice crystal growth in a binary system (water/citric acid) containing mineral particles (ATD), based on the correlation between the ice growth rate and the inverse of the liquid viscosity. These results will be useful for chemical engineering applications and biotechnology, for example, freeze-drying of formulations as well as for better understanding the formation of ice clouds and atmospheric aerosol.

Field observations of daytime HONO source strengths have not been well explained by laboratory measurements and model predictions up until now. More efforts are urgently needed to fill the knowledge gaps concerning how environmental factors, especially relative humidity (RH), affect particulate nitrate photolysis. In this work, two critical attributes for atmospheric particles, i.e., phase state and bulk-phase acidity, both influenced by ambient RH, were focused to illuminate the key regulators for reactive nitrogen production from typical internally mixed systems, i.e., NaNO3and dicarboxylic acid (DCA) mixtures. The dissolution of only few oxalic acid (OA) crystals resulted in a remarkable 50-fold increase in HONO production compared to pure nitrate photolysis at 85% RH. Furthermore, the HONO production rates (PHONO) increased by about 1 order of magnitude as RH rose from <5% to 95%, initially exhibiting an almost linear dependence on the amount of surface absorbed water and subsequently showing a substantial increase in PHONOonce nitrate deliquescence occurred at approximately 75% RH. NaNO3/malonic acid (MA) and NaNO3/succinic acid (SA) mixtures exhibited similar phase state effects on the photochemical HONO production. These results offer a new perspective on how aerosol physicochemical properties influence particulate nitrate photolysis in the atmosphere.

Highly oxygenated organic molecules (HOMs) are a major source of new particles that affect the Earth’s climate. HOM production from the oxidation of volatile organic compounds (VOCs) occurs during both the day and night and can lead to new particle formation (NPF). However, NPF involving organic vapors has been reported much more often during the daytime than during nighttime. Here, we show that the nitrate radicals (NO3), which arise predominantly at night, inhibit NPF during the oxidation of monoterpenes based on three lines of observational evidence: NPF experiments in the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN (European Organization for Nuclear Research), radical chemistry experiments using an oxidation flow reactor, and field observations in a wetland that occasionally exhibits nocturnal NPF. Nitrooxy-peroxy radicals formed from NO3chemistry suppress the production of ultralow-volatility organic compounds (ULVOCs) responsible for biogenic NPF, which are covalently bound peroxy radical (RO2) dimer association products. The ULVOC yield of α-pinene in the presence of NO3is one-fifth of that resulting from ozone chemistry alone. Even trace amounts of NO3radicals, at sub-parts per trillion level, suppress the NPF rate by a factor of 4. Ambient observations further confirm that when NO3chemistry is involved, monoterpene NPF is completely turned off. Our results explain the frequent absence of nocturnal biogenic NPF in monoterpene (α-pinene)-rich environments.

Reduced nitrogen-containing organic compounds (NOCs) in aerosols play a crucial role in altering their light-absorption properties, thereby impacting regional haze and climate. Due to the low concentration levels of individual NOCs in the air, the utilization of accurate detection and quantification technologies becomes essential. For the first time, this study investigated the diurnal variation, chemical characteristics, and potential formation pathways of NOCs in urban ambient aerosols in Shanghai using a versatile aerosol concentration enrichment system (VACES) coupled with HPLC-Q-TOF-MS. The results showed that NOCs accounted over 60% of identified components of urban organic aerosols, with O/N < 3 compounds being the major contributors (>70%). The predominance of the positive ionization mode suggested the prevalence of reduced NOCs. Higher relative intensities and number fractions of NOCs were observed during nighttime, while CHO compounds showed an opposite trend. Notably, a positive correlation between the intensity of NOCs and ammonium during the nighttime was observed, suggesting that the reaction of ammonium to form imines may be a potential pathway for the formation of reduced NOCs during the nighttime. Seven prevalent types of reduced NOCs in autumn and winter were identified and characterized by an enrichment of CH2long-chain homologues. These NOCs included alkyl, cyclic, and aromatic amides in CHON compounds, as well as heterocyclic or cyclic amines and aniline homologue series in CHN compounds, which were associated with anthropogenic activities and may be capable of forming light-absorbing chromophores or posing harm to human health. The findings highlight the significant contributions of both primary emissions and ammonium chemistry, particularly amination processes, to the pollution of reduced NOCs in Shanghai’s atmosphere.

There is now much evidence that OH radicals and H2O2are spontaneously generated at the air–water interface of atmospheric aerosols. Here, we investigated the effect of halide anions (Cl–, Br–, I–), which are abundant in marine aerosols, on this H2O2production. Droplets were generated via nebulization of water solutions containing Na2SO4, NaCl, NaBr, and NaI containing solutions, and H2O2was monitored as a function of the salt concentration under atmospheric relevant conditions. The interfacial OH radical formation was also investigated by adding terephthalic acid (TA) to our salt solutions, and the product of its reaction with OH, hydroxy terephthalic acid (TAOH), was monitored. Finally, a mechanistic investigation was performed to examine the reactions participating in H2O2production, and their respective contributions were quantified. Our results showed that only Br–contributes to the interfacial H2O2formation, promoting the production by acting as an electron donor, while Na2SO4and NaCl stabilized the droplets by only reducing their evaporation. TAOH was observed in the collected droplets and, for the first time, directly in the particle phase by means of online fluorescence spectroscopy, confirming the interfacial OH production. A mechanistic study suggests that H2O2is formed by both OH and HO2self-recombination, as well as HO2reaction with H atoms. This work is expected to enhance our understanding of interfacial processes and assess their impact on climate, air quality, and health.

Atmospheric aerosol particles may contain light absorbing (brown carbon, BrC), triplet forming organic compounds that can sustain catalytic radical reactions and thus contribute to oxidative aerosol aging. We quantify UVA induced radical production initiated by imidazole-2-carboxaldehyde (IC), benzophenone (BPh). and 4-benzoylbenzoic acid (BBA) in the presence of the nonabsorbing organics citric acid (CA), shikimic acid (SA), and syringol (Syr) at varying mixing ratios. We observed a maximum HO2release of 1013molecules min–1cm–2at a mole ratio XBPh< 0.02 for BPh in CA. Mixtures of either IC or BBA with CA resulted in 1011–1012molecules min–1cm–2of HO2at mole ratios (XICand XBBA) between 0.01 and 0.15. HO2release was affected by relative humidity (RH) and film thickness suggesting coupled photochemical reaction and diffusion processes. Quantum yields of HO2formed per absorbed photon for IC, BBA and BPh were between 10–7and 5 × 10–5. The nonphotoactive organics, Syr and SA, increased HO2production due to the reaction with the triplet excited species ensuing ketyl radical production. Rate coefficients of the triplet of IC with Syr and SA measured by laser flash photolysis experiments were kSyr= (9.4 ± 0.3) × 108M–1s–1and kSA= (2.7 ± 0.5) × 107M–1s–1. A simple kinetic model was used to assess total HO2and organic radical production in the condensed phase and to upscale to ambient aerosol, indicating that BrC induced radical production may amount to an upper limit of 20 and 200 M day–1of HO2and organic radical respectively, which is greater or in the same order of magnitude as the internal radical production from other processes, previously estimated to be around 15 M per day.

Mineral dust particles have photochemical properties that can promote heterogeneous reactions on their surfaces and therefore alter atmospheric composition. Even though dust photocatalytic nature has received significant attention recently, most studies have focused on inorganic trace gases. Here, we investigated how light changes the chemical interactions between butanol and Arizona test dust, a proxy for mineral dust, under atmospheric conditions. Butanol uptake kinetics were measured, exploring the effects of UV light irradiation intensity (0–1.4 mW/cm2), relative humidity (0–10%), temperature (283–298 K), and butanol initial concentration (20–55 ppb). The composition of the gas phase was monitored by a high-resolution proton-transfer-reaction mass spectrometer (PTR-ToF-MS) operating in H3O+mode. Water was observed to play a significant role, initially reducing heterogeneous processing of butanol but enhancing reaction rates once it evaporated. Gas phase products were identified, showing that surface reactions of adsorbed butanol led to the emission of a variety of carbonyl containing compounds. Under actinic light these compounds will photolyze and produce hydroxyl radicals, changing dust processing from a sink of VOC into a source of reactive compounds.

[ILLUSTRATION OMITTED] What if all your thoughts were uploaded to the Internet? Not just your best thoughts--your world peace or going green thoughts. But all of them: your dirty laundry […]

BACKGROUND: Lymph node metastasis status is a prognostic factor for further lymph node involvement and for patient survival in breast cancer patients. Frozen section analysis of lymph nodes is a reliable method for detection of macro-metastases. However, this method is far less effective in detecting micro-metastases, requesting improved diagnostic procedures. METHODS: We investigated expression and truncation of ezrin in (i) sentinel lymph node metastases, (ii) unaffected axillary lymph nodes, (iii) primary breast tumors, and (iv) healthy glandular breast tissues using 2D gel electrophoresis, SDS-PAGE, and mass spectrometry in addition to Western blotting. RESULTS: Full-length ezrin (E1; amino acids 1–586) is present in all four investigated tissues. Two truncated ezrin forms, one missing about the first hundred amino acids (E2a) and the other lacking about 150 C-terminal amino acids (E2b) were detectable in primary tumor tissues and in sentinel lymph node metastases but not in glandular tissues. Strikingly, an ezrin truncation (E3) which consists approximately of amino acids 238–586 was found strongly expressed in all sentinel lymph node metastases. Moreover, an N-terminal ezrin fragment (E4) that consists approximately of amino acids 1–273 was identified in sentinel lymph node metastases as well. CONCLUSIONS: We show for the first time the existence of tissue-dependent specific ezrin truncations. The distinguished strong Western blot staining of ezrin E3 in sentinel lymph node metastases underlines its capability to substantiate the occurrence of lymph node (micro)metastases in breast cancer patients.

Mit „Gutenberg Biographics“ steht seit 2016 eine Datenbank mit Biographien Mainzer Gelehrter online zur Verfügung. In der ersten Ausbaustufe werden alle Professorinnen und Professoren der Jahre 1946 bis 1973 erfasst. Die Erweiterung um die Professoren der alten Mainzer Universität sowie die fortschreitende Ergänzung bis in die Gegenwart ist mittelfristig geplant. Durch die Verwendung von Normdaten wird Gutenberg Biographics mit anderen Online-Ressourcen vernetzt. Weitere Möglichkeiten der Interoperabilität sind angelegt. Dadurch bietet der Katalog ein enormes Forschungspotenzial für die digitalen Geisteswissenschaften.

Particulate matter 2.5 (PM2.5) filter samples were collected in July and October 2014 and January and April 2015 in urban Shanghai and analyzed using ultrahigh‐performance liquid chromatography coupled to Orbitrap mass spectrometry. The measured chromatogram‐mass spectra were processed by a nontarget screening approach to identify significant signals. In total, 810–1,510 chemical formulas of organic compounds in the negative polarity (negative electrospray ionization (ESI−)) and 860–1,790 in the positive polarity (ESI+), respectively, were determined. The chemical characteristics of organic aerosols (OAs) in Shanghai varied among different months and between daytime and nighttime. In the January samples, organics were generally richer in terms of both number and abundance, whereas those in the July samples were far lower. More CHO− (compounds containing only carbon, hydrogen, and oxygen and detected in ESI−) and CHOS− (sulfur‐containing organics) were found in the daytime samples, suggesting a photochemical source, whereas CHONS− (nitrogen‐ and sulfur‐containing organics) were more abundant in the nighttime samples, due to nocturnal nitrate radical chemistry. A significant number of monocyclic and polycyclic aromatic compounds, and nitrogen‐ and sulfur‐containing heterocyclic compounds, were detected in all samples, indicating that biomass burning and fossil fuel combustion made important contributions to the OAs in urban Shanghai. Additionally, precursor‐product pair analysis indicates that the epoxide pathway is an important formation route for organosulfates observed in Shanghai. Moreover, a similar analysis suggests that 35–57% of nitrogen‐containing compounds detected in ESI+ could be formed through reactions between ammonia and carbonyls. Our study presents a comprehensive overview of OAs in urban Shanghai, which helps to understand their characteristics and sources. Organic aerosols in Shanghai were characterized, showing that biomass burning and fossil fuel combustion were potentially important sourcesVariations in organic aerosol composition are observed among different months and between daytime and nighttimeEpoxide‐intermediated routes and ammonia‐carbonyl chemistry likely dominate the formation of OSs and nitrogen‐containing species, respectively

In the recent years, photocatalytic self-cleaning and “depolluting” materials have been suggested as a remediation technology mainly for NOxand aromatic VOCs in urban areas. A number of products incorporating the aforementioned technology have been made commercially available with the aim to improve urban air quality. These commercial products are based on the photocatalytic properties of a thin layer of TiO2at the surface of the material (such as glass, pavement, etc.) or embedded in paints or concrete. The use of TiO2photocatalysts as an emerging air pollution control technology has been reported in many locations worldwide. However, up to now, the effectiveness measured in situ and the expected positive impact on air quality of this relatively new technology has only been demonstrated in a limited manner. Assessing and demonstrating the effectiveness of these depolluting techniques in real scale applications aims to create a real added value, in terms of policy making (i.e., implementing air quality strategies) and economics (by providing a demonstration of the actual performance of a new technique).

We present experimental evidence that atomic and molecular iodine, I and I2, are produced spontaneously in the dark at the air–water interface of iodide-containing droplets without any added catalysts, oxidants, or irradiation. Specifically, we observe I3–formation within droplets, and I2emission into the gas phase from NaI-containing droplets over a range of droplet sizes. The formation of both products is enhanced in the presence of electron scavengers, either in the gas phase or in solution, and it clearly follows a Langmuir–Hinshelwood mechanism, suggesting an interfacial process. These observations are consistent with iodide oxidation at the interface, possibly initiated by the strong intrinsic electric field present there, followed by well-known solution-phase reactions of the iodine atom. This interfacial chemistry could be important in many contexts, including atmospheric aerosols.

Ground subsidence caused by permafrost thawing causes the formation of thermokarst ponds, where organic compounds from eroding permafrost accumulate. We photolyzed water samples from two such ponds in Northern Quebec and discovered the emission of volatile organic compounds (VOCs) using mass spectrometry. One pond near peat-covered permafrost mounds was organic-rich, while the other near sandy mounds was organic-poor. Compounds up to C10 were detected, comprising the atoms of O, N, and S. The main compounds were methanol, acetaldehyde, and acetone. Hourly VOC fluxes under actinic fluxes similar to local solar fluxes might reach up to 1.7 nmol C m–2s–1. Unexpectedly, the fluxes of VOCs from the organic-poor pond were greater than those from the organic-rich pond. We suggest that different segregations of organics at the air/water interface may partly explain this observation. This study indicates that sunlit thermokarst ponds are a significant source of atmospheric VOCs, which may affect the environment and climate via ozone and aerosol formation. Further work is required for understanding the relationship between the pond’s organic composition and VOC emission fluxes.

28 snowpack samples were collected across northern Xinjiang, northwestern China in January 2018. 16 of these liquid snowmelt samples, 15 with pH < 6.8 and one with the highest nitrate anion (NO3−) concentration, were selected to investigate the photochemical gaseous nitrous acid (HONO) production rate (P(HONO)(g)), which was observed to range from 4.0 to 180.9 ppt min−1at room temperature. Surprisingly, the ratio of HONO production rate and NO3−concentration (P(HONO)(g)/[NO3ˉ]) was significantly higher than those obtained from the photolysis of aqueous NO3−solutions with similar pH, due to the complex organic compounds present in the snowmelt samples, enhancing HONO formation or the coexistence of other photochemical HONO sources. We also found that P(HONO)(g)was highly correlated with the pH of snowmelt samples, which were significantly lower in rural/remote areas than those from urban/industrial sites, suggesting a significant influence of anthropogenic activities on pH and P(HONO)(g)of snowmelt. Nitrous acid (HONO) is an important trace gas in the troposphere due to its significant contribution to nitrogen oxide (NO) and hydroxyl radical (•OH), both of which contribute to tropospheric ozone (O3) and aerosol production. However, the sources and formation of HONO are still unclear despite its significance to atmospheric chemistry. In this study, 28 snowpack samples were collected across northern Xinjiang, northwestern China. Significant amounts of HONO were produced upon photolysis of acidic snowmelt samples. Besides, low pH was shown to play a major role in gaseous HONO release during the photolysis of NO3−in snowmelt, while NO2ˉ stayed abundant in solution at pH > 3.4. In addition, the complex chemical compositions of the samples greatly enhanced the HONO formation during the NO3−photolysis in the snowmelt. This study showed that photolysis of snowmelt is a significant HONO source across the snow‐covered regions, especially in the arid and semiarid region of northwestern China, where snowmelt is the primary water source. Significant formation of HONO(g)was observed upon photolysis of acidic liquid snowmelt samples collected from 28 sites across northwestern ChinaHONO formation was attributed to the photochemistry of aqueous nitrate ions in the presence of complex organics in the snowmeltHONO(g)release was highly correlated with the pH of snowmelt, which has evident regional characteristics likely influenced by anthropogenic activities Significant formation of HONO(g)was observed upon photolysis of acidic liquid snowmelt samples collected from 28 sites across northwestern China HONO formation was attributed to the photochemistry of aqueous nitrate ions in the presence of complex organics in the snowmelt HONO(g)release was highly correlated with the pH of snowmelt, which has evident regional characteristics likely influenced by anthropogenic activities

The article highlights the significance of labyrinth walking, a prayer in motion that reflects the spiritual yearning to get at the heart of God. It claims that labyrinth is a continuous path leading towards the core of Christian faith. Its relevance as a tool that will nurture one's dimension of the Christian life that draws near into His presence is also emphasized.

Nitroaromatic compounds (NACs) are important light absorption contributors to atmospheric brown carbon; however, their formation pathways and the key influential factors in polluted urban atmospheres are largely unknown. Herein, we present the molecular characterization of atmospheric particulate NACs in urban Shanghai by applying ultra‐high‐performance liquid chromatography coupled to Orbitrap mass spectrometry, and investigated their seasonal and diel variations and formation pathways. The total number and abundance of NACs increased significantly during air pollution episodes, and these NACs exhibited the greatest relative abundance among CHON compounds. The 12 quantified NACs exhibited higher levels in winter (52.3 ± 29.1 ng m−3) than summer (7.83 ± 3.30 ng m−3), largely owing to air masses mostly passing through northern heating regions. Among NACs, 4‐nitrophenol and 4‐nitrocatechol were the most abundant species. Most of NACs were enhanced via photooxidation during the day in summer, while the day‐night variations in winter were not as obvious. Further analysis of atmospheric formation relevance suggested that nitrophenol and its methylated derivatives were mainly formed through gas‐phase photochemical reactions, whereas aqueous‐phase oxidation processing could be an important pathway to form methyl‐nitrocatechols. Formation of NACs was relatively sensitive to NO2under low‐NOxconditions, and became independent of NO2under high‐NOxconditions. A larger fraction of NO2was transformed into NACs than into inorganic nitrate products when nitrate was less abundant, implying that NACs would play more important roles in aerosol properties with the decline in nitrate concentrations. The total number and abundance of detected Nitroaromatic compounds (NACs) increased significantly during air pollution episodesThe quantified NACs exhibited higher levels in winter than summer, largely owing to air masses passing through northern heating regionsControlling NOxand aromatic volatile organic compounds emissions could significantly reduce the NAC formation The total number and abundance of detected Nitroaromatic compounds (NACs) increased significantly during air pollution episodes The quantified NACs exhibited higher levels in winter than summer, largely owing to air masses passing through northern heating regions Controlling NOxand aromatic volatile organic compounds emissions could significantly reduce the NAC formation

The kinetics of the heterogeneous reaction between gas-phase ozone and chlorophyll present at the air−salt water interface are altered in the presence of actinic radiation. Under dark conditions, a Langmuir−Hinshelwood mechanism is followed, but actinic illumination brings about a large enhancement in the rate and a change to a linear dependence on ozone concentration. This change is observed through the entire near-UV and visible spectrum but reverts to that seen in darkness with illumination >800 nm. The excitation spectrum of chlorophyll on the salt-water surface is only somewhat different than that observed with a pure-water substrate. However, the photochemical loss rate of chlorophyll in the absence of ozone is much greater on the surface of salt solutions than upon pure water. In salt solutions, a transient absorption feature assignable to Cl2−is observed following laser excitation of chlorophyll. Also, absorptions due to the chlorophyll cation or triplet state and due to solvated electrons are seen in illuminated salt- and fresh-water chlorophyll solutions. Altogether, these results suggest that Cl atoms are formed in this system via the reduction of the photoformed chlorophyll cation by chloride anions. The yield of Cl is enhanced in the presence of ozone, perhaps through the oxidation of Cl2−. The chlorine atoms thus formed are responsible for the enhanced chlorophyll loss at the surface of illuminated salt-water substrates. The formation of Cl atoms also has implications for gas-phase oxidative chemistry in the marine boundary layer.

An interview with mixed martial artist Matt Hughes is presented. When asked if he sees himself rising prominently in mixed martial arts, Hughes reveals that he started off with the sport as a hobby, never realizing it would eventually support him and his family. He points out that wrestling plays an important part in mixed martial arts competition as it gives competitors control of the matches. Hughes also trains hard all the way up until weigh-in and says that he eats healthy and avoids fast foods.

A personal narrative is presented which explores the author's experience of participating a pilgrimage to Israel.

The uptake coefficients of NO2on aqueous solutions containing guaiacol, syringol and catechol were determined over the pH range from 1 to 13 using the wetted wall flowtube technique. The measured uptake coefficients were used to determine the rate coefficients for the reaction of the physically dissolved NO2with the neutral and deprotonated forms of phenolic compounds listed above. These organic compounds are ubiquitous not only in biomass burning plumes but also in soils, where they form part of the building blocks of humic acids. The NO2uptake kinetics on solutions containing guaiacol, syringol or catechol were observed to be strongly pH dependent with uptake coefficients increasing from below 10−7, under acidic conditions, to more than 10−5at pH values above 10. This behaviour illustrates the difference of reactivity between the neutral phenolic species and the phenoxide ions. The corresponding second order rate coefficients were typically observed to increase from 105M−1s−1for the neutral compounds to a minimum of 108M−1s−1for the phenoxide ions.

Bimolecular rate coefficients for the reactions of the nitrate radical, NO3, with methanol, ethanol, acetaldehyde tert-butyl methyl ether, propionic acid, dimethylmalonate, dimethylsuccinate, dimethyl carbonate and diethylcarbonate in aqueous solutions have been measured using a novel experimental approach. This study was performed using laser flash photolysis LFP with a capillary made of Teflon AF2400 as a long path capillary photolysis cell. Taking benefit of this new material allowing a long optical path length for a very limited irradiated solution volume, new rate constants were established. All experiments were carried out at room temperature. Measured rate coefficients for the reaction of the NO3radical with methanol, ethanol, acetaldehyde, dimethylcarbonate, diethylcarbonate, dimethylmalonate, dimethyl succinate, propionic acid and tert-butyl-methyl ether are units are 105M−1s−1: kNO3  ethanol  4.8 ± 0.5, kNO3  ethanol  19 ± 3, kNO3  acetaldehyde  20 ± 3, kNO3  dimethylcarbonate  0.15 ± 0.04, kNO3  diethylcarbonate  0.84 ± 0.12, kNO3  dimethylmalonate  0.26 ± 0.07, kNO3  dimethylsuccinate  0.34 ± 0.02, kNO3  propionic acid  0.77 ± 0.02, kNO3  tert-butyl-methyl ether  3.9 ± 1.3. The uncertainties in the above expressions are ±2σand represent precision only. The reported rate coefficients for the reactions of NO3with methanol, ethanol and acetaldehyde agree well with currently recommended values. To date, there is no kinetic data reported in the literature for the NO3radical reaction with dimethylcarbonate, diethylcarbonate, dimethylmalonate, dimethylsuccinate, propionic acid and tert-butyl-methyl ether. The reaction mechanism is briefly discussed as a function of bond energies

Bimolecular rate coefficients for the reactions of the nitrate radical, NO₃, with methanol, ethanol, acetaldehyde tert-butyl methyl ether, propionic acid, dimethylmalonate, dimethylsuccinate, dimethyl carbonate and diethylcarbonate in aqueous solutions have been measured using a novel experimental approach. This study was performed using laser flash photolysis (LFP) with a capillary made of Teflon AF2400 as a long path capillary photolysis cell. Taking benefit of this new material allowing a long optical path length for a very limited irradiated solution volume, new rate constants were established. All experiments were carried out at room temperature. Measured rate coefficients for the reaction of the NO₃ radical with methanol, ethanol, acetaldehyde, dimethylcarbonate, diethylcarbonate, dimethylmalonate, dimethyl succinate, propionic acid and tert-butyl-methyl ether are (units are 105 M−1 s−1): k_{NO3 + ethanol} = 4.8 ± 0.5, k_{NO3 + ethanol} = 19 ± 3, k_{NO3 + acetaldehyde} = 20 ± 3, k_{NO3 + dimethylcarbonate} = 0.15 ± 0.04, k_{NO3 + diethylcarbonate} = 0.84 ± 0.12, k_{NO3 + dimethylmalonate} = 0.26 ± 0.07, k_{NO3 + dimethylsuccinate} = 0.34 ± 0.02, k_{NO3 + propionic acid} = 0.77 ± 0.02, k_{NO3 + tert-butyl-methyl ether} = 3.9 ± 1.3. The uncertainties in the above expressions are ±2σ and represent precision only. The reported rate coefficients for the reactions of NO₃ with methanol, ethanol and acetaldehyde agree well with currently recommended values. To date, there is no kinetic data reported in the literature for the NO₃ radical reaction with dimethylcarbonate, diethylcarbonate, dimethylmalonate, dimethylsuccinate, propionic acid and tert-butyl-methyl ether. The reaction mechanism is briefly discussed as a function of bond energies

Bimolecular rate coefficients for the reactions of the hydroxyl radical, OH, with methanol, ethanol, tetrahydrofuran, dimethylmalonate [CH₃OC(O)CH₂C(O)OCH₃], dimethylsuccinate [CH₃OC(O)CH₂CH₂C(O)OCH₃], dimethylcarbonate [CH₃OC(O)OCH₃] and diethylcarbonate [CH₃CH₂OC(O)OCH₂CH₃] in aqueous solutions have been measured using a novel experimental approach. The centrepiece of the new experimental technique reported in this work is a Teflon AF 2400 liquid core waveguide. The physical properties of the Teflon AF 2400 liquid core waveguide allow for the construction of a micro-flowtube reaction photolysis cell with an extremely low volume and a very long optical pathway. Such a reaction system allows for a very sensitive detection of chemical transients in the aqueous phase. The micro-flowtube experiments involved competition kinetics of the OH radical with the organic reactant of interest and an SCN− anion, (k_OH+SCN− = 1.29 × 1010 M−1 s−1).1 The (SCN)−₂ anion was detected using UV-visible spectroscopy following a medium pressure mercury lamp photolysis (λ ≥ 366 nm) of H₂O/H₂O₂/reactant/KSCN mixtures. All experiments were carried out at room temperature. Measured rate coefficients for the reaction of the OH radical with methanol, ethanol, tetrahydrofuran, dimethylmalonate, dimethylsuccinate, dimethylcarbonate and diethylcarbonate are (units are 108 M−1 s−1): k_OH+methanol = 13 ± 4, k_OH+ethanol = 19 ± 5, k_OH+THF = 38 ± 10, k_{OH+dimethylmalonate} = 2.7 ± 0.9, k_{OH+dimethylsuccinate} = 5.3 ± 2.9, k_{OH+dimethylcarbonate} = 0.51 ± 0.22, k_{OH+diethylcarbonate} = 7.9 ± 3.2. Uncertainties in the above expressions are ±2σ and represent precision only. The reported rate coefficients for the reactions of OH with ethanol, methanol and THF agree very well with the currently recommended values. To date, there is no kinetic data reported in the literature for the OH radical reaction with dimethylmalonate, dimethylsuccinate, dimethylcarbonate and diethylcarbonate. The reaction mechanism is briefly discussed as a function of bond energies.