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Purpose Although economists and academics have studied money laundering for several decades, there continues to be gaps in the research due to a lack of reliable data on money laundering activity, and a lack of detailed sources and methods of collection in government-based reporting. The purpose of this study is to apply the Walker-Unger gravity model and examine US-based money launderer preference for the 2000-2020 time frame. This paper then compares those results with previous applications of the model and identifies trends, which may serve as the foundations of a money launderer preference theory. The results of the investigation ranked countries by preference of US-based money launderers and determined that there was consistency in country destination preference even during recessionary periods. Design/methodology/approach The Walker–Unger gravity model as applied by Roman et al. (2021) is used to conduct the investigation, to maintain consistency in the application of the Walker–Unger model and further the objective of validating the attractiveness simulation. The model tests the predictive capability of the independent variables to establish the degree of attractiveness each country represents for the funds of US-based money launderers. A score is generated by the model, which is then used to analyze and interpret its significance in relation to all sampled countries. Findings Model results reveal the countries with the highest attractiveness for US-based money launderers during 2000–2020 were Australia, the Bahamas, Bermuda, Canada, Cayman Islands, Norway, Monaco, Puerto Rico, Switzerland and the USA. Model results show that over the two decades the proportion of money flow scores changed but not to a degree that would alter the country preference of US-based money launderers. US-based money launderers tended to use the same countries for their illicit financial activities, regardless of the state of the legitimate economy. Research limitations/implications One of the limitations of the model is that it does not show the effect of money laundering on legitimate economic activity. Practical implications The model results will give insight into the preferred destination of US-based money launderers and therefore frame one component of money laundering activities in the USA for the examined time period. Social implications A secondary objective of this study is to evaluate if any changes to US-based money launderer preferences occurred during the three most recent periods of economic downturn in the USA. Originality/value The model results will give insight into the preferred destination of US-based money launderers and therefore frame one component of money laundering activities in the USA for the examined time period. A secondary objective of this study is to evaluate if any changes to US-based money launderer preferences occurred during the three most recent periods of economic downturn in the USA. The periods chosen are the 2001 9/11 terrorist attacks, the 2007/08 global financial crisis and the COVID-19 pandemic.

Local content development is a strategic management issue for multinational extractive companies in Africa with significant business implications. As local content statutory regulators aim to increase the average local content value in the Nigeria oil and gas industry from 26% in 2017 to 70% in 2027, supply chain managers need strategies to increase local content. The purpose of this qualitative multiple case study was to explore strategies supply chain managers in the multinational oil and gas companies in Nigeria use to increase local content. The participants comprised eight supply chain managers and leaders in multinational oil and gas companies and the Nigerian Content Development and Monitoring Board involved in local content development activities. Data were collected from semi structured interviews and secondary documents. Thematic analysis generated two themes: Business value drivers for local content development and overarching local content development strategies. A key recommendation is for supply chain managers to document business value drivers for implementing local content development strategies. Future research recommendations include review and ranking of strategies by using a quantitative methodology, and an assessment of the relationship between local content development expenditure and tangible business value created. Key words: Nigeria, Oil and Gas, local content, supply chain.

Germany has been operating permanently crewed research stations in Antarctica for more than 45 years. The opening of the Georg Forster Station (1976) and Georg von Neumayer Station (1981) initiated a period of continuous environmental monitoring that allowed both the former East Germany and West Germany to become contracting parties in, and achieve consultative status with, the framework of the Antarctic Treaty. This marked a milestone in German polar research. Continuous research at the Neumayer Station III, its two predecessors, and the now-dismantled former German Democratic Republic (GDR) Georg Forster Station is undertaken by teams of so-called “overwinterers”, presently with nine members, who stay at the base for longer than an entire Antarctic winter. Their long-term stay in Antarctica is defined by isolation, separation from civilization, routine work to sustain long-term scientific observations, and unique personal experiences. This article is dedicated to them and outlines their part and role in the German Antarctic research landscape. Germany has been operating permanently crewed research stations in Antarctica for more than 45 years. The opening of the Georg Forster Station (1976) and Georg von Neumayer Station (1981) initiated a period of continuous environmental monitoring that allowed both the former East Germany and West Germany to become contracting parties in, and achieve consultative status with, the framework of the Antarctic Treaty. This marked a milestone in German polar research. Continuous research at the Neumayer Station III, its two predecessors, and the now-dismantled former German Democratic Republic (GDR) Georg Forster Station is undertaken by teams of so-called "overwinterers", presently with nine members, who stay at the base for longer than an entire Antarctic winter. Their long-Term stay in Antarctica is defined by isolation, separation from civilization, routine work to sustain long-Term scientific observations, and unique personal experiences. This article is dedicated to them and outlines their part and role in the German Antarctic research landscape.

Reactions in the atmospheric aqueous phase are an important source of secondary organic aerosols (SOA). Within the present study, the reactions of triplet-state imidazole-2-carboxaldehyde (

Over the course of calendar year 2019, businesses around the globe have experienced supply chain disruption due to the COVID-19 global pandemic. The strategic significance of the supply chain has been thrust into the forefront for businesses, economies, and society at large. It has become recognized by researchers and industry that there is a need for higher efficiency within the supply chain while remaining responsive to consumer needs. However, the fragmented and diverse nature of supply chain management, coupled with the complex accountancy and financial outputs of the supply chain, has resulted in limited development of a theoretical foundation specific to supply chain management. The aim of this investigation was to develop a new model (the Supply Chain Efficiency Ratio) that measures supply chain efficiency using financial ratios and by extending the Efficiency Model. Data for this investigation were obtained from U.S.-based public discount stores in the United States. The results of the multiple regression performed indicated that the Supply Chain Efficiency Ratio holds predictive value of an organization's supply chain efficiency p

Purpose This study aims to apply the modified Walker-Unger model to show the degree of attractiveness of a country for Mexican-based money launderers to send their illicit funds for the 2000–2015 time period. Design/methodology/approach The modified Walker-Unger model is used to conduct the analysis, as it combines several independent variables related to an illicit financial activity. These allow the researcher to investigate the attractiveness of a market to money launderers and the possible economic effects of money laundering. In total, 13 categories of indicators were used, namely, gross national product per capita; banking secrecy; government attitude; society for worldwide interbank financial telecommunication membership; financial deposits; conflict; corruption; Egmont group membership; language; trade; culture, colonial background; and physical distance. Findings Model results suggest the preferred destinations for Mexican-based money launderers from 2000 to 2015 were Bermuda (i.e. from 2000–2004), Canada (i.e. in 2005 and 2006) and Monaco (i.e. from 2007–2015). Research limitations/implications Timing and availability of reliable data after 2015. Practical implications Aids in continuing to empirically validate the Walker-Unger model. There is little literature on models that quantify money laundering activity. Social implications May aid policymakers in targeting anti-money laundering policy to more relevant countries. Originality/value The first empirical investigation that looks to quantify money launderer activity in Mexico. Contributes to the limited literature of quantitative investigations on money laundering.

Tartaric acid and mucic acid are dicarboxylic acids (DCAs), a substance class often found in atmospheric aerosols and cloud droplets. The hydroxyl radical (

Glycine, alanine, serine, and threonine are essential amino acids originating from biological activities. These substances can be emitted into the atmosphere directly. In the present study, the aqueous phase reaction kinetics of hydroxyl radicals (˙OH) with the four amino acids is investigated using the competition kinetics method under controlled temperature and pH conditions. The following T-dependent Arrhenius expressions are derived for the ˙OH reactions with glycine

Motivated by the experimental search for the QCD critical point we perform simulations of a stochastic field theory with purely relaxational dynamics (model A). We verify the expected dynamic scaling of correlation functions. Using a finite size scaling analysis we obtain the dynamic critical exponent $z=2.026(56)$. We investigate time dependent correlation functions of higher moments $M^n(t)$ of the order parameter $M(t)$ for $n=1,2,3,4$. We obtain dynamic scaling with the same critical exponent $z$ for all $n$, but the relaxation constant depends on $n$. We also study the relaxation of $M^n(t)$ after a quench, where the simulation is initialized in the high temperature phase, and the dynamics is studied at the critical temperature $T_c$. We find that the evolution does not follow simple scaling with the dynamic exponent $z$, and that it involves an early time rise followed by late stage relaxation., 13 pages, 7 figures. Minor error corrected; shifts normalization of m^2

Photosensitized reactions of organic compounds in the atmospheric aqueous and particle phase might be potential sources for secondary organic aerosol (SOA) formation, addressed as aqueous SOA. However, data regarding the photophysical properties of photosensitizers, their kinetics, as well as reaction mechanisms of such processes in the aqueous/particle phase are scarce. The present study investigates the determination of the photophysical properties of imidazole-2-carboxaldehyde, 2-furaldehyde, and 2-acetylfuran as potential photosensitizers using laser flash excitation in aqueous solution. Quantum yields of the formation of the excited photosensitizers were obtained by a scavenging method with thiocyanate, resulting in values between 0.86 and 0.96 at 298 K and pH = 5. The time-resolved absorbance spectra of the excited photosensitizers were measured, and their molar attenuation coefficients were determined ranging between (0.30 and 1.4) × 104 L mol-1 cm-1 at their absorbance maxima (λmax = 335-440 nm). Additionally, the excited photosensitizers are quenched by water and molecular oxygen, resulting in quenching rate constants of k1st = (1.0 ± 0.2-1.8 ± 0.2) × 105 s-1 and kq(O2) = (2.1 ± 0.2-2.7 ± 0.2) × 109 L mol-1 s-1, respectively.

The aqueous phase that serves as a reaction medium in the atmosphere, is existing in the form of clouds, fogs, rain, and particulate matter consisting of either an aqueous solution containing pollutants or a film of water surrounding. Light-induced reactions facilitate the aqueous phase photochemical reactions. It is believed that light absorbing compounds such as photosensitizers in the atmospheric have a potential influence on the atmospheric aging, growth and formation of secondary organic aerosol (SOA). However, the kinetics, products, and mechanisms of the photosensitized reactions are still poorly understood. This study was aimed to investigate the photosensitized reactions of methyl vinyl ketone (MVK), methacrolein (MACR), and methacrylic acid (MCA by excited 2-IC (imidazole-2-carboxaldehyde) in the aqueous phase. Laser flash excitation-laser long-path absorption and ultra-performance liquid chromatography coupled with high-resolution electrospray ionization spectrometry were used to investigate their kinetics and reaction product(s), respectively. The second-order reaction constants of excited imidazole-2-carboxaldehyde (2-IC) with MVK: k = (1.0 ± 0.1) × 109 L mol−1 s−1 at pH 4 – 5 and 9, with MACR: k = (1.4 ± 0.4) × 109 and k = (1.5 ± 0.1) × 109 L mol−1 s−1 at pH 4 – 5 and 9, and with MCA: k= (1.4 ± 0.4) × 109 and (1.1 ± 0.4) × 108 L mol−1 s−1 at pH 4 – 5 and 9 were determined. Products related with the [2+2] cycloaddition of monomer and dimer of MVK to the excited carbonyl of 2-IC were observed. Similarly, a comparative study of the reaction between 3,4-dimethoxybenzaldehyde (DMB) as a photosensitizer and MVK were performed, and the second-order reaction constants with MVK: k = (1.5 ± 0.1) × 109 L mol−1 s−1 at pH 9, with MACR: k = (1.1 ± 0.1) × 109 and k = (2.8 ± 0.5) × 109 L mol−1 s−1 at pH 2 and 9, and with MCA: k= (1.4 ± 0.4) × 109 at pH 9 were obtained. This study has shown that cycloaddition of α, β-unsaturated carbonyl compounds to the excited triplet state of 2-IC or DMB potentially produced high molecular weight molecules in the atmosphere, which will provide potential insight to alleviate the discrepancy between measured and modelled results.

Aromatic aldehydes are a major gas-phase constitutes of troposphere, which play a fundamental role in the chemistry of polluted regions. They can be directly emitted from vast variety of anthropogenic and biogenic sources. Apart from those, they could be also transformed in the atmosphere by photolysis and/or can get oxidized in presence of atmospheric oxidants such as radicals, yielding hydroxyaldehydes as the main final products. Even though the formation process takes place primarily in the atmospheric gas phase, the produced hydroxyaldehydes are considered as water-soluble compounds due to their Henry’s Law constants, and are therefore capable of undergoing efficient phase transfer to cloud droplets, fog, haze, rain, and deliquescent aerosols, commonly referred as atmospheric aqueous phase. Dissolved organic gases can additionally be oxidized in the aqueous phase, where they contribute to aerosol mass production during cloud evaporation event, forming aqueous-phase secondary organic aerosols (aqSOAs). The potential formation of SOAs in the aqueous phase was estimated by a model prediction, where net global production rate accounts for 10 Tg yr-1 to 50 Tr yr-1. Additionally, there is a lack of aqueous-phase kinetic data with atmospherically relevant radicals that could be used to achieve an accurate description and model prediction of multiphase tropospheric chemistry. Accordingly, in the present study the second-order rate constants for the oxidation reactions of glyceraldehyde, glycolaldehyde, and lactaldehyde with hydroxyl radicals (‧OH), sulfate radicals (SO4‧-), and nitrate radicals (NO3‧) in the aqueous phase were determined. In case of glycolaldehyde, the subsequent radical-initiated second-order rate constants (k2nd) at 298 K were obtained: k(‧OH) = (1.3 ± 0.1) × 109 L mol-1 s-1, k(SO4‧‑) = (2.9 ± 0.2) × 107 L mol‑1 s-1, and k(NO3‧) = (3.9 ±1.1) × 106 L mol-1 s-1, respectively. In addition, the temperature-dependencies of the rate constants were determined in ranges between 278 and 318 K. Through the obtained rate constants and their T-dependencies, the degradation of hydroxyaldehydes with atmospherically relevant radicals in the aqueous-phase can be currently assigned, by which the predictive capabilities of models could be reached. These findings reveal the importance of aqueous phase conversion of gaseous oxidation products, contributing to the budget of important tropospheric aqueous phase carbonyls, which are important for better understanding the formation pathway of in-cloud processed SOAs.

Anthropogenic and biogenic sources produce numerous primary emitted gases, organic compounds, and aerosols in the atmosphere. An important group of such compounds are α, β-unsaturated carbonyl molecules, which can be formed in the atmosphere due to their secondary origin, including oxidation of their precursors such as hydrocarbons with common atmospheric oxidants such as hydroxyl radicals (‧OH). Since those compounds contain at least one double bond and one carbonyl group, they are characterized as water-soluble molecules, which can diffuse on the cloud droplets’ surface and undergo a phase transfer from the gas phase to the atmospheric aqueous phase. In the latter, the oxidized organic compounds can contribute to aerosol mass production through in-cloud processes, yielding aqueous phase secondary organic aerosols (aqSOA). Due to their strong photochemical behavior, the development of a new analytical approach for evaluating the OH radical kinetics in the aqueous phase under dark conditions was essential. One of the most studied non-photolytic reactions is Fenton chemistry (Fe(II)/H2O2), which serves as an OH radical source in the dark in the atmospheric aqueous phase after catalytic decomposition of H2O2 in the presence of Fe(II) at acidic pH values. In a typical experiment, temperature-dependent second-order rate constants of OH radicals with unsaturated dialdehydes, such as (1) crotonaldehyde, and (2) 1,4-butenedial, were determined in a bulk reactor by using the competition kinetics method. In the newly developed method, the role of radical scavenger was performed by isotopically labeled 2-propanol (d8), while the OH-initiated oxidation produces deuterated acetone (d6), being analyzed with GC-MS after derivatization. The findings from our research will be incorporated in the CAPRAM model to explain discrepancies between experimentally observed and predicted aqSOA properties.

Amino acids are key substances in biological activities and can be emitted into the atmosphere as constituents of primary aerosols. Understanding the radical kinetics of amino acids is necessary to evaluate their atmospheric effects. In the present study, the hydroxyl radical (OH) reaction kinetics of glycine, alanine, serine and threonine were investigated in the aqueous phase. The temperature and pH dependent rate constants were measured by a laser flash photolysis-long path absorption setup using the competition kinetics method. Based on the measurements and speciation calculations, the OH radical reaction rate constants of the fully protonated (H2A+) and neutral (HA±) form were determined. The following T-dependent Arrhenius expressions were derived for the OH radical reactions with glycine, k(T, H2A+) = (9.1 ± 0.3) × 109 × exp[(-2360 ± 230 K)/T], k(T, HA±) = (1.3 ± 0.1) × 1010 × exp[(-2040 ± 240 K)/T]; alanine, k(T, H2A+) = (1.0 ± 0.1) × 109 × exp[(-1030 ± 340 K)/T], k(T, HA±) = (6.8 ± 0.4) × 1010 × exp[(-2020 ± 370 K)/T]; serine, k(T, H2A+) = (1.1 ± 0.1) × 109 × exp[(-470 ± 150 K)/T], k(T, HA±) = (3.9 ± 0.1) × 109 × exp[(-720 ± 130 K)/T]; and threonine, k(T, H2A+) = (5.0 ± 0.1) × 1010 × exp[(-1500 ± 100 K)/T], k(T, HA±) = (3.3 ± 0.1) × 1010 × exp[(-1320 ± 90 K)/T] (in units of L mol-1 s-1). The density functional theory calculation was performed using GAUSSIAN to simulate the energy barriers (EBarrier) of OH radical induced H-atom abstraction. According to the simulated results, amino and carboxyl group increase the EBarrier at the adjacent C‑atom and thus reduce the OH radical reactivity. Hydroxide and methyl group decrease the EBarrier at the adjacent C-atom, leading to an increase in the OH radical rate constant.

Green plants exposed to abiotic or biotic stress release C-5 and C-6 unsaturated oxygenated hydrocarbons called Green Leaf Volatiles (GLVs). GLVs partition into tropospheric waters and react to form secondary organic aerosol (SOA). We explored the kinetics of aqueous-phase reactions of 1-penten-3-ol (PENTOL), (Z)-2-hexen-1-ol (HEXOL), and (E)-2-hexen-1-al (HEXAL) with SO4•–, •OH, and NO3•. At 298 K, the rate constants for reactions of PENTOL, HEXOL, and HEXAL with SO4•– were, respectively, (9.4 ± 1.0) × 108 L mol–1 s–1, (2.5 ± 0.3) × 109 L mol–1 s–1, and (4.8 ± 0.2) × 108 L mol–1 s–1; with •OH – (6.3 ± 0.1) × 109 L mol–1 s–1, (6.7 ± 0.3) × 109 L mol–1 s–1, and (4.8 ± 0.3) × 109 L mol–1 s–1; and with NO3• – (1.5 ± 0.15) × 108 L mol–1 s–1, (8.4 ± 2.3) × 108 L mol–1 s–1, and (3.0 ± 0.7) × 107 L mol–1 s–1. The rate constants increased weakly with temperatures ranging from 278 to 318 K. The diffusional limitations of the rate constants appeared significant only for the GLV–•OH reactions. The aqueous-phase reactions appeared negligible in deliquescent aerosol and haze water but not in clouds and rains. The atmospheric lifetimes of GLVs decreased from many days to hours with increasing liquid water content and radicals’ concentration., Green leaf volatiles emitted by plants under biotic and abiotic stress react with atmospheric oxidants in the gas and water phases to influence air quality.

Secondary organic aerosol formation in the atmospheric aqueous/particulate phase by photosensitized reactions is currently subject to uncertainties. To understand the impact of photosensitized reactions, photophysical and -chemical properties of photosensitizers, kinetic data, and reaction mechanisms of these processes are required. The photophysical properties of acetophenones, benzaldehydes, benzophenones, and naphthalenes were investigated in aqueous solution using laser flash excitation. Quantum yields of excited photosensitizers were determined giving values between 0.06-0.80 at 298 K and pH = 5. Molar absorption coefficients (emax(3PS*) = (0.8-13) × 104 L mol-1 cm-1), decay rate constants in water (k1st = (9.4 ± 0.5) × 102 to (2.2 ± 0.1) × 105 s-1), and quenching rate constants with oxygen (kq(O2) = (1.7 ± 0.1-4.4 ± 0.4) × 109 L mol-1 s-1) of the excited triplet states were determined at 298 K and pH = 5. Photosensitized reactions of carboxylic acids and alkenes show second-order rate constants in the range of (37 ± 7.0-0.55 ± 0.1) × 104 and (27 ± 5.0-0.04 ± 0.01) × 108 L mol-1 s-1. The results show that different compound classes act differently as a photosensitizer and can be a sink for certain organic compounds in the atmospheric aqueous phase.

During haze periods in the North China Plain, extremely high NO concentrations have been observed, commonly exceeding 1 ppbv, preventing the classical gas-phase H

Imidazoles formed via the reaction of dicarbonyls with nitrogen containing compounds in the atmospheric particle phase can be expected to initiate secondary organic aerosol (SOA) growth due to their potential to act as photosensitizers. Recent field studies quantified imidazoles for the first time in ambient aerosol samples from Europe and China. However, knowledge about the kinetics and mechanisms of particle-phase reactions involving imidazoles is still very limited. In the present study, the radical-driven aqueous-phase oxidative degradation reactions of the hydroxyl radical (·OH) with imidazoles were investigated. For the imidazoles, the following rate constants at 298 K and acidic conditions are obtained as k(imidazole-2-carboxaldehyde) = (1.8 ± 0.1) × 109 L mol-1 s-1, k(1-methylimidazole) = (2.3 ± 0.1) × 109 L mol-1 s-1, k(2-methylimidazole) = (3.9 ± 0.1) × 109 L mol-1 s-1, k(4-methylimidazole) = (3.2 ± 0.2) × 109 L mol-1 s-1, k(1-ethylimidazole) = (2.6 ± 0.1) × 109 L mol-1 s1, and k(2-ethylimidazole) = (3.9 ± 0.1) × 109 L mol-1 s-1. Temperature and pH dependencies of the reactions as well as the activation parameters have been determined and discussed. The possible implications and restrictions for imidazoles acting as photosensitizers in tropospheric particles have been considered.

Tributyl phosphate (TBP) belongs to the group of trialkyl substituted organophosphate esters. Its chemical reactivity depends on the stability of various chemical bonds. TBP was used as a model compound for the development of a concept using stable isotope fractionation associated with bond cleavage reactions for better understanding the fate of TBP in the environment. Carbon isotope enrichment factors (eC) of TBP hydrolysis were found to be pH dependent (−3.8 ± 0.3‰ at pH 2, -4.6 ± 0.5‰ at pH 7, -2.8 ± 0.1‰ at pH 9, no isotope fractionation at pH 12), which is in accordance with the mode of a SN2 hydrolytic bond cleavage. Hydrogen isotope fractionation was negligible as no H bond cleavage is involved during hydrolysis. The apparent carbon kinetic isotope effect (AKIEC) ranged from 1.045 to 1.058. In contrast to hydrolysis, both carbon and hydrogen isotope fractionation were observed during radical oxidation of TBP by OH and SO4 –, yielding eC from −0.9 ± 0.1‰ to −0.5 ± 0.1‰ and eH from −20 ± 2‰ to −11 ± 1‰. AKIEC and AKIEH varied from 1.007 to 1.011 and from 1.594 to 2.174, respectively. The correlation of 2H and 13C isotope fractionation revealed Λ values ranging from 17 ± 1 to 25 ± 6. Results demonstrated that the correlation of 2H and 13C isotope fractionation of TBP allowed to identify radical reactions and to distinguish them from hydrolysis. The presented dual isotope analysis approach has diagnostic value for characterizing the chemical transformation of TBP in the environment.

Dicarboxylic acids (DCAs) are widely distributed in atmospheric aerosols and cloud droplets and are mainly formed by the oxidation of volatile organic compounds (VOCs). For example, glutaric acid and adipic acid are two kinds of the DCAs that can be oxidized by hydroxyl radical (‧OH) reactions in the aqueous phase of aerosols and droplets. In the present study, the temperature- and pH-dependent rate constants of the aqueous OH radical reactions of the two DCAs were investigated by a laser flash photolysis-long path absorption setup using the competition kinetics method. Based on speciation calculations, the OH radical reaction rate constants of the fully protonated (H2A), deprotonated (HA-) and fully deprotonated (A2-) forms of the two DCAs were determined. The following Arrhenius expressions for the T-dependency of the OH radical reaction of glutaric acid, k(T, H2A) = (3.9 ± 0.1) × 1010 × exp[(-1270 ± 200 K)/T], k(T, HA-) = (2.3 ± 0.1) × 1011 × exp[(-1660 ± 190 K)/T], k(T, A2-) = (1.4 ± 0.1) × 1011 × exp[(-1400 ± 170 K)/T] and adipic acid, k(T, H2A) = (7.5 ± 0.2) × 1010 × exp[(-1210 ± 170 K)/T], k(T, HA-) = (9.5 ± 0.3) × 1010 × exp[(-1200 ± 200 K)/T], k(T, A2-) = (8.7 ± 0.2) × 1010 × exp[(-1100 ± 170 K)/T] (in unit of L mol-1 s-1) were derived.The energy barriers of the H-atom abstractions were simulated by the Density Functional Theory calculations run with the GAUSSIAN package using the M06-2X method and the basis set m062x/6-311++g(3df,2p). The results showed that the energy barriers were lower at the Cβ-atoms and are higher at the Cα-atoms of the two DCAs, clearly suggesting that the H-atom abstractions occurred predominately at the Cβ-atoms. In addition, the ionizations can enhance the electrostatic effects of the carboxyl groups, significantly reducing the energy barriers, leading to the order of OH radical reactivity as < < . This study intends to better characterize the losing processes of glutaric acid and adipic acid in atmospheres.

A new experiment (P. B. Patel et al., Science 370 (2020) 6521, 1222) involving resonantly interacting atoms confined by laser beams sheds light on momentum and energy diffusion in quantum fluids.

Efficiency improvement is the new challenge in all fields of design. In this scenario the reduction of power losses is becoming more and more a main concern also in the design of power transmissions. Appropriate models to predict power losses are therefore required from the earliest stages of the design phase. The aim of this project is to carry out lubrication simulations of several variants of a cylindrical roller bearing to understand the lubricant distribution and the related churning power losses. Several strategies to reduce the computational effort were used. Among them the sectorial symmetry and three innovative meshing strategies (purely analytical with and without interfaces and analytical/subtractive) that were implemented in the OpenFOAM&reg, environment. The results of the different approaches were compared among them and reasonable savings in terms of computational effort were shown.

The acidity of aqueous atmospheric solutions is a key parameter driving both partitioning of semi-volatile acidic or basic trace gases and their linked aqueous-phase chemistry. On the other hand, acidity of atmospheric aqueous phases, e.g. deliquesced aerosol particles, cloud and fog droplets, is conversely affected by aqueous-phase chemistry processes. Those feedbacks in acidity and chemistry have crucial implications for the (i) tropospheric lifetime of air pollutants, hence air quality and atmospheric aerosol composition, (ii) deposition input into other terrestrial and oceanic ecosystems, (iii) the visibility, (iv) climate and (v) human health. Due to their fundamental role, atmospheric research has gained substantial progress in the understanding in feedbacks of acidity and multiphase chemistry. In the present study, the current state of knowledge on the acidity-multiphase chemistry feedbacks has been summarized. From a wide range of topics, two selected issues focusing on impacts of acidity (i) on the hydration of organic carbonyl compounds and (ii) multiphase chemistry of dissociating organic compounds in aqueous particles and clouds will be presented.Hydration processes are typically known to be acid- or base-catalyzed. Thus, the acidity of an aqueous solution can affect the hydration and all other processes linked to it. This comprehensive literature study revealed that the hydration of simple aldehydes and ketones as well as dicarbonyls is less affected by acidity. However, for multifunctional carbonyl compounds such as pyruvic acid, the hydration equilibrium constant of the carbonyl group is strongly influenced by the electronic effects of the adjacent group. The hydration of carbonyl groups in compounds that also contain pH sensitive moieties, such as α-oxocarboxylic acids, is highly influenced by the acidity of the surrounding environment. However, this acidity effect is often not considered in multiphase models.Furthermore, oxidation reactions of dissociating organic compounds can be affected by acidity. To examine the effect of acidity on the chemical processing of dissociating organic compounds, kinetic data for their oxidation by OH, NO3 and O3 have been newly compiled in the present study. Kinetic reactivity data of both protonated and deprotonated organic compounds together with their reactivity ratio have been investigated to identify possible acidity effects. The present study showed that, for OH reactions, the impact of acidity on the chemical kinetics is often quite small and only important for some specific compounds. On the other hand, for NO3 reaction, particularly under cloud conditions, acidity can substantially affect the chemical NO3-initiated processing of organic compounds. Less acidic conditions will enhance the degradation of dissociating compounds via NO3 because of more rapid oxidation and possibility of additional ETR pathway. Furthermore, the present O3 kinetic data analyses have demonstrated the role of acidity for ozonolysis processes, especially for phenolic compounds. Overall, the present study summarizes atmospheric implications and needs for future investigations, particularly with respect to changing aerosol and cloud acidity conditions in the future.

Organosulfates (OSs), also referred to as organic sulfate esters, are well-known and ubiquitous constituents of atmospheric aerosol particles. Commonly, they are assumed to form upon mixing of air masses of biogenic and anthropogenic origin, that is, through multiphase reactions between organic compounds and acidic sulfate particles. However, in contrast to this simplified picture, recent studies suggest that OSs may also originate from purely anthropogenic precursors or even directly from biomass and fossil fuel burning. Moreover, besides classical OS formation pathways, several alternative routes have been discovered, suggesting that OS formation possibly occurs through a wider variety of formation mechanisms in the atmosphere than initially expected. During the past decade, OSs have reached a constantly growing attention within the atmospheric science community with evermore studies reporting on large numbers of OS species in ambient aerosol. Nonetheless, estimates on OS concentrations and implications on atmospheric physicochemical processes are still connected to large uncertainties, calling for combined field, laboratory, and modeling studies. In this Critical Review, we summarize the current state of knowledge in atmospheric OS research, discuss unresolved questions, and outline future research needs, also in view of reductions of anthropogenic sulfur dioxide (SO2) emissions. Particularly, we focus on (1) field measurements of OSs and measurement techniques, (2) formation pathways of OSs and their atmospheric relevance, (3) transformation, reactivity, and fate of OSs in atmospheric particles, and (4) modeling efforts of OS formation and their global abundance.

Background: Propylene glycol and glycerol are e-cigarette constituents that facilitate liquid vaporization and nicotine transport. As these small hydrophilic molecules quickly cross the lung epithelium, we hypothesized that short-term cessation of vaping in regular users would completely clear aerosol deposit from the lungs and reverse vaping-induced cardio-respiratory toxicity. Aims: To assess the acute effects of vaping and their reversibility on biological/clinical cardio-respiratory parameters (serum/urine pneumoproteins, hemodynamic parameters, lung-function test and diffusing capacities, transcutaneous gas tensions (primary outcome) and skin microcirculatory blood flow). Methods: Regular e-cigarette users were enrolled in this randomized, investigator-blinded, three-period crossover-study. The periods consisted of nicotine-vaping (nicotine-session), nicotine-free vaping (nicotine-free-session), and complete cessation of vaping (stop-session), all maintained for five days before the session began. Multiparametric metabolomic analyses were used to verify subjects' protocol compliance. Biological/clinical cardio-respiratory parameters were assessed at the beginning of each session (baseline) and after acute vaping exposure. Results: Compared to the nicotine- and nicotine-free-sessions, a specific metabolomic signature characterized the stop-session. Baseline serum club-cell protein-16 was higher during the stop-session than the other sessions ( p, info:eu-repo/semantics/published

Rate constants for the aqueous-phase reactions of the hydroxyl radical with the dicarboxylic acids, succinic acid and pimelic acid were determined using the relative rate technique over the temperature range 287 K &le, T &le, 318 K and at pH = 2.0, 4.6 or 4.9 and 8.0. OH radicals were generated by H2O2 laser flash photolysis while thiocyanate was used as a competitor. The pH values were adjusted to obtain the different speciation of the dicarboxylic acids. The following Arrhenius expressions were determined (in units of L mol&minus, 1 s&minus, 1):&thinsp, succinic acid, k(T, AH2) (2.1 &plusmn, 0.1) &times, 1010 exp[(&minus, 1530 &plusmn, 250 K)/T], k(T, AH&minus, ) (1.8 &plusmn, 1070 &plusmn, 370 K)/T], k(T, A2&minus, ) (2.9 &plusmn, 0.2) &times, 1011 exp[(&minus, 1830 &plusmn, 350 K)/T] and pimelic acid, k(T, AH2) (7.3 &plusmn, 1040 &plusmn, 140 K)/T], k(T, AH&minus, 1200 &plusmn, 240 K)/T], k(T, A2&minus, ) (1.4 &plusmn, 1012 exp[(&minus, 110 K)/T]. A general OH radical reactivity trend for dicarboxylic acids was found as k(AH2) &lt, k(AH&minus, ) &lt, k(A2&minus, ). By using the pH and temperature dependent rate constants, source and sinking processes in the tropospheric aqueous phase can be described precisely.

Substituted phenols are known to readily react with the hydroxyl radical (OH˙), which is the most powerful atmospheric oxidant and is also most often used in advanced oxidation processes (AOP) for wastewater treatment. We report temperature-dependent (278.15–318.15 K) second order kinetic rate constants for the aqueous-phase reactions of OH˙ with phenol and four substituted phenols: catechol, phloroglucinol, pyrogallol and 3-methylcatechol, with the last two measured for the first time. The constructed Hammett plots for mono- and di-substituted phenols have the potential to be further applied for predicting the reaction rate constants of other substituted phenols at 298.15 K. This will significantly facilitate the optimization of AOP and improve the predictive capabilities of atmospheric multiphase models in the future. Moreover, an advancement in the understanding of the underlying mechanism, i.e. OH˙ addition to the aromatic ring is made by theoretical calculations at the M06-2X level. We demonstrate that the position of substituents on the aromatic ring is important for the [OH–phenol]˙ adduct formation, which is supported by the experiment and theoretical calculations. Adjacent and nonadjacent electron donor/acceptor substituents differently impact the interplay between the activation energy and entropy. We also show that explicit solvation has to be accounted for in theoretical models in order to explicitly describe the formation of the transition state.

Isoprene epoxydiols are well-known intermediates of the isoprene oxidation in the gas phase under pristine conditions. According to their Henry's Law constants, they are well water-soluble and will undergo a phase transfer to the tropospheric aqueous phase to be further processed there. In the present study, the aqueous-phase oxidation by hydroxyl radicals (OH) of the isomer

Efficiency improvement is the new challenge in all fields of design. In this scenario the reduction of power losses is becoming more and more a main concern also in the design of power transmissions. Appropriate models to predict power losses are therefore from the earliest stages of the design phase. The aim of the project is to carry on lubrication simulations of several variants of a cylindrical-roller-bearing to understand the lubricant distribution and the related churning power losses. Several strategies to reduce the computational effort have been used. Among them the sectorial symmetry and three innovative meshing strategies (purely analytical with and without interfaces and analytical/subtractive) that have been implemented in the OpenFOAM® environment. The results of the different approaches were compared among them and with experimental observations showing good agreement and reasonable savings in terms of computational effort.