Combustion chemistry of COS and occurrence of intersystem crossing

This contribution combines results of experiments with kinetic modelling to probe the unusual behaviour of carbonyl sulfide (COS), a sulfur species that frequently arises in fuel systems. The experiments identified CO and SO2 as the primary oxidation products, with no formation of CO2. The low ignition temperature (<600 K) of COS observed in prior experiments conflicts with the high activation barrier for the reaction COS + O2 → CO2 + SO of 211.3 kJ mol−1 on the traditional triplet reaction surface. We proposed that, this kinetic barrier prompts the reaction to transfer onto the singlet surface through intersystem crossing that allows the process to surmount lower-energy hurdles. By considering the oxidation of COS as a single step reaction, we fitted the Arrhenius parameter for the reaction COS + O2 → CO + SO2 directly from our experimental measurements. The fitted activation energy of 70.1 kJ∙mol−1 agrees with that of 85.4 ± 20.0 kJ∙mol−1 as calculated in literature at the Hartree-Fock level of theory, indicating the appearance of the intersystem crossing process in the oxidation of COS. The reaction mechanism based on this comportment leads to excellent agreement between the kinetic model and the experimentally measured quantities, such as the onset temperature and the conversion profiles of detected species. The proposed kinetic model for the oxidation of COS provides a tool to design both the SOx mitigation processes and industrial systems for safe handling of sulfur impurities in fossil fuels

Products of incomplete combustion from biomass reburning

Fuel reburning usually serves in mitigating NOx formation in stationary combustion sources. However, the use of biomass as reburning fuel could facilitate the production of relatively more nitrogen-containing aromatic products of incomplete combustion. This study investigates the heterogeneous reaction between biomass and mixtures of NO/O2 gases, employing isothermal high-temperature experiments in a vertically-entrained reactor, and in situ diffuse reflective infrared Fourier transform spectroscopy (DRIFTS) under a non-isothermal heating condition ranging from ambient temperature to 700 °C. The method enables sensitive evaluation of the surface species ensuing during the thermal reaction. Results from this study elucidate the formation of nitrated structures as active intermediate species of the heterogeneous reaction. The nitrogenated signatures persist on the surface of the residual ash, suggesting the production of N-aromatics such as nitro-PAH. Considering the severe toxicity and bioaccumulative properties of these by-products, further research should focus on the relative contribution of various reburning fuels, while favouring sustainable fuels such as non-charring plastics

Atmospheric emission of NOx from mining explosives: A critical review

High-energy materials such as emulsions, slurries and ammonium-nitrate fuel-oil (ANFO) explosives play crucial roles in mining, quarrying, tunnelling and many other infrastructure activities, because of their excellent transport and blasting properties. These explosives engender environmental concerns, due to atmospheric pollution caused by emission of dust and nitrogen oxides (NOx) from blasts, the latter characterised by the average emission factor of 5 kg (t AN explosive)−1. This first-of-its-kind review provides a concise literature account of the formation of NOx during blasting of AN-based explosives, employed in surface operations. We estimate the total NOx emission rate from AN-based explosives as 0.05 Tg (i.e., 5 × 104 t) N per annum, compared to the total global annual anthropogenic NOx emissions of 41.3 × 106 t N y−1. Although minor in the global sense, the large localised plumes from blasting exhibit high NOx concentration (500 ppm) exceeding up to 3000 times the international standards. This emission has profound consequences at mining sites and for adjacent atmospheric environment, necessitating expensive management of exclusion zones. The review describes different types of AN energetic materials for civilian applications, and summarises the essential properties and terminologies pertaining to their use. Furthermore, we recapitulate the mechanisms that lead to the formation of the reactive nitrogen species in blasting of AN-based explosives, review their implications to atmospheric air pollution, and compare the mechanisms with those experienced in other thermal and combustion operations. We also examine the mitigation approaches, including guidelines and operational-control measures. The review discusses the abatement technologies such as the formulation of new explosive mixtures, comprising secondary fuels, spin traps and other additives, in light of their effectiveness and efficiency. We conclude the review with a summary of unresolved problems, identifying possible future developments and their impacts on the environment with emphasis on local and workplace loads

DFT + U and ab initio atomistic thermodynamics approache for mixed transitional metallic oxides: A case study of CoCu 2 O 3 surface terminations

This study develops a systematic density functional theory alongside on-site Coulomb interaction correction (DFT + U) and ab initio atomistic thermodynamics approachs for ternary (or mixed transitional metal oxides), expressed in three reservoirs. As a case study, among notable multiple metal oxides, synthesized CoCu2O3 exhibits favourable properties towards applications in solar, thermal and catalytic processes. This progressive contribution applies DFT + U and atomistic thermodynamic approaches to examine the structure and relative stability of CoCu2O3 surfaces. Twenty-five surfaces along the [001], [010], [100], [011], [101], [110] and [111] low-Miller-indices, with varying surface-termination configurations were selected in this study. The results portray satisfactory geometrical parameters for bulk CoCu2O3 and a band gap of 1.25 e V. Furthermore, we clarified the stoichiometrically balanced inverted (010)CoCuO, and the non-stoichiometric (001)CuOCu, (001)CoOCo, (110)OCoO and (110)CoOCu surface terminations as the most stable configurations, out of which, the (001)CuOCu shows the optimum stability in ambient conditions. The systematic approach applied in this study should prove instrumental for the analysis of other 3-element multicomponent systems. To the best of our knowledge, the present study is the first to report DFT + U analysis to any 3-multicompnent systems with two of them requires inclusion of U treatment (i.e., f- and d- orbitals) in the electronic structure calculations

Phenol dissociation on pristine and defective graphene

Phenol (C6H5O‒H) dissociation on both pristine and defective graphene sheets in terms of associated enthalpic requirements of the reaction channels was investigated. Here, we considered three common types of defective graphene, namely, Stone-Wales, monovacancy and divacancy configurations. Theoretical results demonstrate that, graphene with monovacancy creates C atoms with dangling bond (unpaired valence electron), which remains particularly useful for spontaneous dissociation of phenol into phenoxy (C6H5O) and hydrogen (H) atom. The reactions studied herein appear barrierless with reaction exothermicity as high as 2.2 eV. Our study offers fundamental insights into another potential application of defective graphene sheets

Systematic review of pathways to care in the U.S. for Black individuals with early psychosis

The pathway to receiving specialty care for first episode psychosis (FEP) among Black youth in the US has received little attention despite documented challenges that negatively impact engagement in care and clinical outcomes. We conducted a systematic review of US-based research, reporting findings related to the pathway experiences of Black individuals with FEP and their family members. A systematic search of PubMed, PsycInfo, and Embase/Medline was performed with no date restrictions up to April 2021. Included studies had samples with at least 75% Black individuals and/or their family members or explicitly examined racial differences. Of the 80 abstracts screened, 28 peer-reviewed articles met the inclusion criteria. Studies were categorized into three categories: premordid and prodromal phase, help-seeking experiences, and the duration of untreated psychosis (DUP). Compounding factors such as trauma, substance use, and structural barriers that occur during the premorbid and prodromal contribute to delays in treatment initiation and highlight the limited use of services for traumatic childhood experiences (e.g., sexual abuse). Studies focused on help-seeking experiences demonstrated the limited use of mental health services and the potentially traumatic entry to services (e.g., law enforcement), which is associated with a longer DUP. Although the majority of studies focused on help-seeking experiences and predictors of DUP, findings suggests that for Black populations, there is a link between trauma and substance use in the pathway to care that impacts the severity of symptoms, initiation of treatment, and DUP. The present review also identifies the need for more representative studies of Black individuals with FEP

Probing the reactivity of singlet oxygen with cyclic monoterpenes

Monoterpenes represent a class of hydrocarbons consisting of two isoprene units. Like many other terpenes, monoterpenes emerge mainly from vegetation, indicating their significance in both atmospheric chemistry and pharmaceutical and food industries. The atmospheric recycling of monoterpenes constitutes a major source of secondary organic aerosols. Therefore, this contribution focuses on the mechanism and kinetics of atmospheric oxidation of five dominant monoterpenes (i.e., limonene, α-pinene, β-pinene, sabinene, and camphene) by singlet oxygen. The reactions are initiated via the ene-type addition of singlet oxygen (O21Δg) to the electron-rich double bond, progressing favorably through the concerted reaction mechanisms. The physical analyses of the frontier molecular orbitals agree well with the thermodynamic properties of the selected reagents, and the computed reaction rate parameters. The reactivity of monoterpenes with O21Δg follows the order of α-pinene > sabinene > limonene > β-pinene > camphene, i.e., α-pinene and camphene retain the highest and lowest reactivity toward singlet oxygen, with rate expressions of k(T) (M–1 s–1) = 1.13 × 108 exp(−48(kJ)/RT(K)) and 6.93 × 108 exp(−139(kJ)/RT(K)), respectively. The effect of solvent on the primary reaction pathways triggers a slight reduction in energy, ranging between 12 and 34 kJ/mol

Homelessness predicts attrition but not alcohol abstinence in outpatients experiencing co-occurring alcohol dependence and serious mental illness.

BACKGROUND: Adults experiencing homelessness and serious mental illnesses (SMI) are at an increased risk of poor mental health and treatment outcomes compared with stably housed adults with SMI. The additional issue of alcohol misuse further complicates the difficulties of those living with homelessness and SMI. In this secondary data analysis, the authors investigated the impact of homelessness on attrition and alcohol use in a contingency management (CM) intervention that rewarded alcohol abstinence in outpatients with SMI. METHODS: The associations between housing status and attrition and alcohol abstinence during treatment, as assessed by ethyl glucuronide (EtG) urine tests, were evaluated in 79 adults diagnosed with alcohol dependence and SMI. RESULTS: Thirty-nine percent (n = 31) of participants reported being homeless at baseline. Individuals who were homeless were more likely to drop out of CM (n = 10, 62.5%) than those who were housed (n = 4, 16.7%), χ CONCLUSIONS: Individuals experiencing homelessness and co-occurring alcohol dependence and SMI receiving CM had higher rates of attrition, relative to those who were housed. Homelessness was not associated with differences in biologically assessed alcohol abstinence

Pretreatment ethyl glucuronide levels predict response to a contingency management intervention for alcohol use disorders among adults with serious mental illness.

BACKGROUND AND OBJECTIVES: This study investigated if pretreatment ethyl glucuronide (EtG) levels corresponding to light (100 ng/mL), heavy (500 ng/mL), and very heavy (1,000 ng/mL) drinking predicted longest duration of alcohol abstinence (LDA) and proportion of EtG-negative urine tests in outpatients receiving a 12-week EtG-based contingency management (CM) intervention for alcohol dependence. METHODS: Participants were 40 adults diagnosed with alcohol use disorders and serious mental illness who submitted up to 12 urine samples for EtG analysis during a 4-week observation period and were then randomized to 12-weeks of CM for alcohol abstinence and addiction treatment attendance. Alcohol use outcomes during CM as assessed by EtG and self-report were compared across those who did and did not attain a pre-treatment average EtG level of 500 ng/mL-a level that equates to frequent heavy drinking. RESULTS: Only the 500 ng/mL cutoff was associated with significant differences in LDA and proportion of EtG-negative samples during CM. Those with a pre-treatment EtG \u3c 500 ng/mL attained a LDA 2.3 (alcohol) to 2.9 (drugs) weeks longer than pre-treatment heavy drinkers. DISCUSSION AND CONCLUSIONS: The EtG biomarker can be used to determine who will respond to a CM intervention for alcohol use disorders and could inform future trials that are designed to be tailored to individual patients. SCIENTIFIC SIGNIFICANCE: Results suggest pre-treatment EtG cutoffs equivalent to heavy and very heavy drinking predict outcomes in CM. (Am J Addict 2017;26:673-675)

Prevalence and Correlates of Cannabis Use in Outpatients with Serious Mental Illness Receiving Treatment for Alcohol Use Disorders.

Introduction: People with serious mental illness (SMI) use cannabis more than any other illicit drug. Cannabis use is associated with increased psychotic symptoms and is highly comorbid with alcohol use disorders (AUDs). Despite the national trend toward decriminalization, little is known about the prevalence, correlates, and impact of cannabis use on those with SMI receiving treatment for substance use disorders, a group at high risk for the negative effects of cannabis use. Methods: In this secondary data analysis, cannabis use prevalence, correlates, and impact on treatment outcomes were examined in 121 adults with cooccurring SMI and AUDs receiving outpatient addiction treatment in a randomized trial of contingency management (CM) for alcohol. Prevalence and frequency of cannabis use were calculated across the 7-month study period using self-report and urine tests. Cannabis users were compared with nonusers by SMI diagnosis, psychiatric symptoms, medical problems, legal problems, and HIV-risk behavior. The relationship between cannabis use and longest duration of alcohol abstinence in participants randomized to CM (n=40) was assessed. Results: Fifty-seven (47%) of participants submitted at least one cannabis-positive urine sample during the study. Out of the 2834 total samples submitted, 751 (27%) were positive for cannabis. Cannabis users were 2.2 times more likely to submit an alcohol-positive sample, and 2.5 times more likely to submit a cocaine-positive sample at baseline, relative to noncannabis users (p=0.01). Cannabis users were more likely to engage in risky sexual behavior (p=0.01) and to report being homeless (p=0.03) than nonusers. When controlling for pretreatment alcohol use, the relationship between comorbid cannabis use and alcohol abstinence during CM was not significant (p=0.77). Conclusion: Rates of comorbid cannabis use were high in this sample of adults with SMI and AUDs. Cannabis use was correlated with recent alcohol and cocaine use, risky sexual behavior, and homelessness, but not with alcohol abstinence during CM