Search

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in space and govern the interstellar chemistry. The two isomers of cyanonaphthalene (1-CNN and 2-CNN) were the first PAHs to be recently identified in the Taurus Molecular Cloud (TMC-1). Their large abundance is attributed to high photostability with nearly no photofragmentation at photon energies above the ionization potential. Here, we show that at ambient light and at densities akin to dense molecular clouds and the upper atmosphere of planets and moons, 1-CNN could undergo extensive fragmentation through a new mechanism leading to daughter cations. On UV photoexcitation, at a photon energy way below the ionization threshold, 1-CNN monomers form photoexcited dimer units. Intermolecular Coulombic decay between the two photoexcited units of the dimer leads to ionization, and the subsequent molecular rearrangements form new daughter cations. These daughter cations could react further, contributing to rich bottom-up astrochemistry, and could play a pivotal role in developmental astrobiology. Photofragmentation in atmospheric and astrophysical environments is hitherto known to be unimolecular, while the present results point a pathway involving bimolecular photofragmentation. [ABSTRACT FROM AUTHOR]

The recent discovery of cyano-substituted aromatic and two-ring polycyclic aromatic hydrocarbon molecules in Taurus Molecular Cloud-1 has prompted questions on how the electronic structure and excited-state dynamics of these molecules are linked with their existence and abundance. Here, we report a photodetachment and frequency- and angle-resolved photoelectron spectroscopy study of jet-cooled para-deprotonated benzonitrile (p-[Bzn-H]−). The adiabatic detachment energy was determined as 1.70 ± 0.01 eV, in good agreement with CCSD(T)/aug-cc-pVTZ calculations. The spectra across the first few electron-volts above threshold are dominated by prompt autodetachment processes associated with excitation of at least five short-lived (tens of femtoseconds) temporary anion shaped resonances since excitation cross sections are several orders of magnitude larger than direct photodetachment cross sections. The photoexcitation vibronic profile is dominated by a ≈640 cm−1 ring deformation mode. [Bzn-H]− lacks a valence-localized excited state situated below the detachment threshold and does not exhibit thermionic emission following excitation of the temporary anion resonances. Thus, [Bzn-H]− is unlikely to be stable in many interstellar environments. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are widely recognized as catalysts for interstellar H2 formation. Extensive exploration into the catalytic potential of various PAHs has encompassed both theoretical investigations and experimental studies. In the present study, we focused on studying the reactivity of an imperfect aromatic molecule, indene (C9H8), and its hydrogenated counterpart, indane (C9H10), as potential catalysts for H2 formation within the interstellar medium. The reactions of these molecules with H atoms at 3.1 K were investigated experimentally using the para-H2 matrix isolation technique. Our experimental results demonstrate that both indene and indane are reactive toward H atoms. Indene can participate in H-atom-abstraction and H-atom-addition reactions, whereas indane primarily undergoes H-atom-abstraction reactions. The H-atom-abstraction reaction of indene results in the formation of the 1-indenyl radical (R1) (C9H7) and H2 molecule. Simultaneously, an H-atom-addition reaction forms the 1,2-dihydro-indene-3-yl radical (R2) (C9H9). Experiments also reveal that the H-atom-abstraction reaction of indane also produces the R2 radical. To the best of our knowledge, this study represents the first reporting of the infrared spectra of R1 and R2 radicals. The experimental results, combined with theoretical findings, suggest that indane and indene may play a role in the catalytic formation of interstellar H2. Furthermore, these results imply a quasi-equilibrium between the investigated molecules and the formed radicals via H-atom-addition and H-atom-abstraction reactions. [ABSTRACT FROM AUTHOR]

Understanding core level shifts in aromatic compounds is crucial for the correct interpretation of x-ray photoelectron spectroscopy (XPS) of polycyclic aromatic hydrocarbons (PAHs), including acenes, as well as of styrenic polymers, which are increasingly relevant for the microelectronic industry, among other applications. The effect of delocalization through π aromatic systems on the stabilization of valence molecular orbitals has been widely investigated in the past. However, little has been reported on the impact on the deeper C1s core energy levels. In this work, we use first-principles calculations at the level of many body perturbation theory to compute the C1s binding energies of several aromatic systems. We report a C1s red shift in PAHs and acenes of increasing size, both in the gas phase and in the molecular crystal. C1s red shifts are also calculated for stacked benzene and naphthalene pairs at decreasing intermolecular distances. A C1s red shift is in addition found between oligomers of poly(p-hydroxystyrene) and polystyrene of increasing length, which we attribute to ring–ring interactions between the side-chains. The predicted shifts are larger than common instrumental errors and could, therefore, be detected in XPS experiments. [ABSTRACT FROM AUTHOR]

The CH stretch overtone region (5750–6300 cm−1) of benzene and naphthalene is assigned herein using anharmonic quantum chemical computations, and the trend of how this extends to larger polycyclic aromatic hydrocarbons (PAHs) is established. The assignment of all experimental bands to specific vibrational states is performed for the first time. Resonance polyads and the inclusion of 3-quanta vibrational states are both needed to compute accurate vibrational frequencies with the proper density-of-states to match the experimental band shape. Hundreds of 3-quanta states produce the observed band structure in naphthalene, anthracene, and tetracene, and this number is expected to increase drastically for larger PAHs. The width and shape of the main peak are consistent from naphthalene to anthracene, necessitating further exploration of this trend to confirm whether it is representative of all PAHs in the CH stretch overtone region. Understanding observations of PAH sources in the 1–3 μm region from the NIRSpec instrument aboard JWST requires new computational data, and this study provides a benchmark and foundation for their computation. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are widely recognized as catalysts for interstellar H2 formation. Extensive exploration into the catalytic potential of various PAHs has encompassed both theoretical investigations and experimental studies. In the present study, we focused on studying the reactivity of an imperfect aromatic molecule, indene (C9H8), and its hydrogenated counterpart, indane (C9H10), as potential catalysts for H2 formation within the interstellar medium. The reactions of these molecules with H atoms at 3.1 K were investigated experimentally using the para-H2 matrix isolation technique. Our experimental results demonstrate that both indene and indane are reactive toward H atoms. Indene can participate in H-atom-abstraction and H-atom-addition reactions, whereas indane primarily undergoes H-atom-abstraction reactions. The H-atom-abstraction reaction of indene results in the formation of the 1-indenyl radical (R1) (C9H7) and H2 molecule. Simultaneously, an H-atom-addition reaction forms the 1,2-dihydro-indene-3-yl radical (R2) (C9H9). Experiments also reveal that the H-atom-abstraction reaction of indane also produces the R2 radical. To the best of our knowledge, this study represents the first reporting of the infrared spectra of R1 and R2 radicals. The experimental results, combined with theoretical findings, suggest that indane and indene may play a role in the catalytic formation of interstellar H2. Furthermore, these results imply a quasi-equilibrium between the investigated molecules and the formed radicals via H-atom-addition and H-atom-abstraction reactions. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are common atmospheric pollutants, and they are also ubiquitous in the interstellar medium. Here, we report the study of a complex O-containing PAH anion, the deprotonated 2-hydroxytriphenylene (2-OtPh–), using high-resolution photoelectron imaging and photodetachment spectroscopy of cryogenically cooled anions. Vibrationally resolved photoelectron spectra yield the electron affinity of the 2-OtPh radical as 2.629(1) eV and several vibrational frequencies for its ground electronic state. Photodetachment spectroscopy reveals bound valence excited electronic states for the 2-OtPh– anion, with unprecedentedly rich vibronic features. Evidence is presented for a low-lying triplet state (T1) and two singlet states (S1 and S2) below the detachment threshold. Single-color resonant two-photon photoelectron spectroscopy uncovers rich photophysics for the 2-OtPh– anion, including vibrational relaxation in S1, internal conversion to the ground state of 2-OtPh–, intersystem crossing from S2 to T1, and a long-lived autodetaching shape resonance about 1.3 eV above the detachment threshold. The rich electronic structure and photophysics afforded by the current study suggest that 2-OtPh– would be an interesting system for pump–probe experiments to unravel the dynamics of the excited states of this complex PAH anion. [ABSTRACT FROM AUTHOR]

Photoinduced symmetry-breaking charge separation (SB-CS) has been extensively observed in various oligomers and aggregates, which holds great potential for robust artificial solar energy conversion systems. It attaches great importance to the precise manipulation of interchromophore electronic coupling in realizing efficient SB-CS. The emerging studies on SB-CS suggested that it could be realized in null-excitonic aggregates, and a long-lived SB-CS state was observed, which offers an advanced platform and has gathered immense attention in the SB-CS field. Here, we unveiled the null-exciton coupling induced ultrafast SB-CS in a rigid polycyclic aromatic hydrocarbon framework, triperyleno[3,3,3]propellane triimides (TPPTI), in which three chromophores were attached through a nonconjugated bridge. Through a combination of theoretical calculations and steady-state absorption results, we demonstrated that this nonconjugated TPPTI possesses negligible exciton coupling. Increased solvent polarity was found to significantly enhance state mixing between local excited and charge transfer states. Using transient absorption spectroscopy, ultrafast SB-CS was observed in highly polar dimethylformamide, facilitated by a selective hole-transfer coupling and a favorable charge separation free energy (ΔGCS). Additionally, the rate ratio between SB-CS and charge recombination was at least high to 1800 in dimethylformamide. This investigation provides profound insights into the role of null-exciton coupling in dominating ultrafast SB-CS in multichromophoric systems. [ABSTRACT FROM AUTHOR]

Resonant electron capture by aza and diaza derivatives of phenanthrene (7,8-benzoquinoline and 1,10-phenanthroline) and anthracene (acridine and phenazine) at incident free electron energies (Ee) in the range of 0–15 eV was studied. All compounds except 7,8-benzoquinoline form long-lived molecular ions (M−) at thermal electron energies (Ee ∼ 0 eV). Acridine and phenazine also form such ions at epithermal electron energies up to Ee = 1.5–2.5 eV. The lifetimes (τa) of M− with respect to electron autodetachment are proportional to the extent of aza-substitution and increase on going from molecules with bent geometry of the fused rings (azaphenanthrenes) to linear isomers (azaanthracenes). These regularities are due to an increase in the adiabatic electron affinities (EAa) of the molecules. The EAa values of the molecules under study were comprehensively assessed based on a comparative analysis of the measured τa values using the Rice–Ramsperger–Kassel–Marcus theory, the electronic structure analysis using the molecular orbital approach, as well as the density functional calculations of the total energy differences between the molecules and anions. The only fragmentation channel of M− ions from the compounds studied is abstraction of hydrogen atoms. When studying [M–H]− ions, electron autodetachment processes were observed, the τa values were measured, and the appearance energies were determined. A comparative analysis of the gas-phase acidity of the molecules and the EAa values of the [M–H]· radicals revealed their proportionality to the EAa values of the parent molecules. [ABSTRACT FROM AUTHOR]

Environmentally persistent free radicals (EPFRs) play an important role in aerosol effects on air quality and public health, but their atmospheric abundance and sources are poorly understood. We measured EPFRs contained in PM2.5 collected in Fairbanks, Alaska, in winter 2022. We find that EPFR concentrations were enhanced during surface-based inversion and correlate strongly with incomplete combustion markers, including carbon monoxide and elemental carbon (R2 > 0.75). EPFRs exhibit moderately good correlations with PAHs, biomass burning organic aerosols, and potassium (R2 > 0.4). We also observe strong correlations of EPFRs with hydrocarbon-like organic aerosols, Fe and Ti (R2 > 0.6), and single-particle mass spectrometry measurements reveal internal mixing of PAHs, with potassium and iron. These results suggest that residential wood burning and vehicle tailpipes are major sources of EPFRs and nontailpipe emissions, such as brake wear and road dust, may contribute to the stabilization of EPFRs. Exposure to the observed EPFR concentrations (18 ± 12 pmol m-3) would be equivalent to smoking ∼0.4-1 cigarette daily. Very strong correlations (R2 > 0.8) of EPFR with hydroxyl radical formation in surrogate lung fluid indicate that exposure to EPFRs may induce oxidative stress in the human respiratory tract.

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) have been linked to adverse birth outcomes that have been reported to be induced by oxidative stress, but few epidemiological studies to date have evaluated associations between urinary PAH metabolites and oxidative stress biomarkers in pregnancy and identified critical periods for these outcomes and PAH exposures in pregnancy. METHODS: A cohort of pregnant women was recruited early in pregnancy from antenatal clinics at the University of California Los Angeles during 2016-2019. We collected urine samples up to three times during pregnancy in a total of 159 women enrolled in the cohort. A total of 7 PAH metabolites and 2 oxidative stress biomarkers [malondialdehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG)] were measured in all available urine samples. Using multiple linear regression models, we estimated the percentage change (%) and 95% confidence interval (CI) in 8-OHdG and MDA measured at each sample collection time per doubling of PAH metabolite concentrations. Furthermore, we used linear mixed models with a random intercept for participant to estimate the associations between PAH metabolite and oxidative stress biomarker concentrations across multiple time points in pregnancy. RESULTS: Most PAH metabolites were positively associated with both urinary oxidative stress biomarkers, MDA and 8-OHdG, with stronger associations in early and late pregnancy. A doubling of each urinary PAH metabolite concentration increased MDA concentrations by 5.8-41.1% and 8-OHdG concentrations by 13.8-49.7%. Linear mixed model results were consistent with those from linear regression models for each gestational sampling period. CONCLUSION: Urinary PAH metabolites are associated with increases in oxidative stress biomarkers during pregnancy, especially in early and late pregnancy.

Topological phases in laterally confined low-dimensional nanographenes have emerged as versatile design tools that can imbue otherwise unremarkable materials with exotic band structures ranging from topological semiconductors and quantum dots to intrinsically metallic bands. The periodic boundary conditions that define the topology of a given lattice have thus far prevented the translation of this technology to the quasi-zero-dimensional (0D) domain of small molecular structures. Here, we describe the synthesis of a polycyclic aromatic hydrocarbon (PAH) featuring two localized zero modes (ZMs) formed by the topological junction interface between a trivial and nontrivial phase within a single molecule. First-principles density functional theory calculations predict a strong hybridization between adjacent ZMs that gives rise to an exceptionally small HOMO-LUMO gap. Scanning tunneling microscopy and spectroscopy corroborate the molecular structure of 9/7/9-double quantum dots and reveal an experimental quasiparticle gap of 0.16 eV, corresponding to a carbon-based small molecule long-wavelength infrared (LWIR) absorber.

Background and aimStudies suggest prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) may influence wheezing or asthma in preschool-aged children. However, the impact of prenatal PAH exposure on asthma and wheeze in middle childhood remain unclear. We investigated these associations in socio-demographically diverse participants from the ECHO PATHWAYS multi-cohort consortium.MethodsWe included 1,081 birth parent-child dyads across five U.S. cities. Maternal urinary mono-hydroxylated PAH metabolite concentrations (OH-PAH) were measured during mid-pregnancy. Asthma at age 8-9 years and wheezing trajectory across childhood were characterized by caregiver reported asthma diagnosis and asthma/wheeze symptoms. We used logistic and multinomial regression to estimate odds ratios of asthma and childhood wheezing trajectories associated with five individual OH-PAHs, adjusting for urine specific gravity, various maternal and child characteristics, study site, prenatal and postnatal smoke exposure, and birth year and season in single metabolite and mutually adjusted models. We used multiplicative interaction terms to evaluate effect modification by child sex and explored OH-PAH mixture effects through Weighted Quantile Sum regression.ResultsThe prevalence of asthma in the study population was 10%. We found limited evidence of adverse associations between pregnancy OH-PAH concentrations and asthma or wheezing trajectories. We observed adverse associations between 1/9-hydroxyphenanthrene and asthma and persistent wheeze among girls, and evidence of inverse associations with asthma for 1-hydroxynathpthalene, which was stronger among boys, though tests for effect modification by child sex were not statistically significant.ConclusionsIn a large, multi-site cohort, we did not find strong evidence of an association between prenatal exposure to PAHs and child asthma at age 8-9 years, though some adverse associations were observed among girls.

The computation of the nuclear quantum dynamics of molecules is challenging, requiring both accuracy and efficiency to be applicable to systems of interest. Recently, theories have been developed for employing time-dependent basis functions (denoted modals) with vibrational coupled cluster theory (TDMVCC). The TDMVCC method was introduced along with a pilot implementation, which illustrated good accuracy in benchmark computations. In this paper, we report an efficient implementation of TDMVCC, covering the case where the wave function and Hamiltonian contain up to two-mode couplings. After a careful regrouping of terms, the wave function can be propagated with a cubic computational scaling with respect to the number of degrees of freedom. We discuss the use of a restricted set of active one-mode basis functions for each mode, as well as two interesting limits: (i) the use of a full active basis where the variational modal determination amounts essentially to the variational determination of a time-dependent reference state for the cluster expansion; and (ii) the use of a single function as an active basis for some degrees of freedom. The latter case defines a hybrid TDMVCC/TDH (time-dependent Hartree) approach that can obtain even lower computational scaling. The resulting computational scaling for hybrid and full TDMVCC[2] is illustrated for polyaromatic hydrocarbons with up to 264 modes. Finally, computations on the internal vibrational redistribution of benzoic acid (39 modes) are used to show the faster convergence of TDMVCC/TDH hybrid computations towards TDMVCC compared to simple neglect of some degrees of freedom. [ABSTRACT FROM AUTHOR]

Wildfires affect soils in multiple ways, leading to numerous challenges for colonizing microorganisms. Although it is thought that fire-adapted microorganisms lie at the forefront of postfire ecosystem recovery, the specific strategies that these organisms use to thrive in burned soils remain largely unknown. Through bioactivity screening of bacterial isolates from burned soils, we discovered that several Paraburkholderia spp. isolates produced a set of unusual rhamnolipid surfactants with a natural methyl ester modification. These rhamnolipid methyl esters (RLMEs) exhibited enhanced antimicrobial activity against other postfire microbial isolates, including pyrophilous Pyronema fungi and Amycolatopsis bacteria, compared to the typical rhamnolipids made by organisms such as Pseudomonas spp. RLMEs also showed enhanced surfactant properties and facilitated bacterial motility on agar surfaces. In vitro assays further demonstrated that RLMEs improved aqueous solubilization of polycyclic aromatic hydrocarbons, which are potential carbon sources found in char. Identification of the rhamnolipid biosynthesis genes in the postfire isolate, Paraburkholderia kirstenboschensis str. F3, led to the discovery of rhlM, whose gene product is responsible for the unique methylation of rhamnolipid substrates. RhlM is the first characterized bacterial representative of a large class of integral membrane methyltransferases that are widespread in bacteria. These results indicate multiple roles for RLMEs in the postfire lifestyle of Paraburkholderia isolates, including enhanced dispersal, solubilization of potential nutrients, and inhibition of competitors. Our findings shed new light on the chemical adaptations that bacteria employ to navigate, grow, and outcompete other soil community members in postfire environments.

OBJECTIVE: Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with adverse birth and developmental outcomes in children. We aimed to describe prenatal PAH exposures in a large, multisite U.S. consortium. METHODS: We measured 12 mono-hydroxylated metabolites (OH-PAHs) of 7 PAHs (naphthalene, fluorene, phenanthrene, pyrene, benzo(c)phenanthrene, chrysene, benz(a)anthracene) in mid-pregnancy urine of 1,892 pregnant individuals from the ECHO PATHWAYS consortium cohorts: CANDLE (n = 988; Memphis), TIDES (n = 664; Minneapolis, Rochester, San Francisco, Seattle) and GAPPS (n = 240; Seattle and Yakima, WA). We described concentrations of 8 OH-PAHs of non-smoking participants (n = 1,695) by site, socioeconomic characteristics, and pregnancy stage (we report intraclass correlation coefficients (ICC) for n = 677 TIDES participants). RESULTS: Exposure to the selected PAHs was ubiquitous at all sites. 2-hydroxynaphthalene had the highest average concentrations at all sites. CANDLE had the highest average concentrations of most metabolites. Among non-smoking participants, we observed some patterns by income, education, and race but these were not consistent and varied by site and metabolite. ICCs of repeated OH-PAH measures from TIDES participants were ≤ 0.51. CONCLUSION: In this geographically-diverse descriptive analysis of U.S. pregnancies, we observed ubiquitous exposure to low molecular weight PAHs, highlighting the importance of better understanding PAH sources and their pediatric health outcomes attributed to early life PAH exposure.

Polycyclic aromatic hydrocarbons (PAHs) are organic molecules containing adjacent aromatic rings. Infrared emission bands show that PAHs are abundant in space, but only a few specific PAHs have been detected in the interstellar medium. We detected 1-cyanopyrene, a cyano-substituted derivative of the related four-ring PAH pyrene, in radio observations of the dense cloud TMC-1, using the Green Bank Telescope. The measured column density of 1-cyanopyrene is ~1.52 × 1012 cm−2, from which we estimate that pyrene contains up to 0.1% of the carbon in TMC-1. This abundance indicates that interstellar PAH chemistry favors the production of pyrene. We suggest that some of the carbon supplied to young planetary systems is carried by PAHs that originate in cold molecular clouds. [ABSTRACT FROM AUTHOR]

Due to the importance and fascination that arises from processes involving Polycyclic Aromatic Hydrocarbon (PAHs) in the interstellar medium (ISM), in this work quantum calculations were used to study the HAVA mechanism (Hydrogen Abstraction Vinylacetylene Addition) involved in the PAHs formation from the benzonitrile (⁠|${\rm C_6H_5CN}$|⁠), molecule recently discovered in the ISM, and vinylacetylene (⁠|${\rm C_4H_4}$|⁠). The reaction force analysis was used to obtain information about the mechanisms in terms of structural and electronic rearrangements presents in the formation of naphthalene, 1-naphthonitrile, 2-naphthonitrile, and 3-ethynylisoquinoline. Due to the presence of the cyano group on the aromatic ring for the formation of 1-naphthonitrile and 2-naphthonitrile, these reactions: (a) follow the HAVA mechanism, showing the same structural nature of the submerged energy barriers and (b) result consistent with the fact that both molecules have recently been found in TMC-1, where benzonitrile and vinylacetylene are also present. The mesomeric and inductive effect of the cyano group on the aromatic ring contributes to lowering the energy barrier when the radical is in the ortho position on the aromatic ring with respect to the cyano group. This decrease contributes greatly to the work of electronic reordering. Although the formation of 3-ethynylisoquinoline (N-Heterocycle) does not follow the HAVA mechanism and involves positive barriers at the conditions of TMC-1, important astrochemical and astrobiological implications can be derived from this result, since N-containing heterocycles, have been detected in carbonaceous chondrites would be providing interesting connection between chemistry in space and the origin of life on Earth. [ABSTRACT FROM AUTHOR]

This work proposed an easy-to-perform but effective strategy to eliminate the ACQ effect of PAHs for ECL enhancement by coordinatively grafting PAH-derived ligands onto ultrathin MOLs, which opened a new horizon to develop high-efficiency Ru-complex-free porous ECL materials for fabricating supersensitive ECL sensing platforms. [Display omitted] • A novel ECL emitter was prepared by coordinatively grafting a new ECL luminophore PyTS on ultrathin MOL. • This work proposed a new and facile strategy to surmount the ACQ effect of PAHs. • This strategy provided significant inspiration for designing high-efficiency Ru-complex-free ECL materials. • The fabricated ECL biosensor accomplished the supersensitive detection of miRNA-21. The exploration of novel electrochemiluminescence (ECL) luminophores with excellent ECL properties is a current research hotspot in the ECL field. Herein, a novel high-efficiency Ru-complex-free ECL emitter PyTS-Zr-BTB-MOL has been prepared by using porous ultrathin Zr-BTB metal–organic layer (MOL) as carrier to coordinatively graft the cheap and easily available polycyclic aromatic hydrocarbon (PAH) derivative luminophore PyTS whose ECL performance has never been investigated. Gratifyingly, the ECL intensity and efficiency of PyTS-Zr-BTB-MOL were markedly enhanced compared to both PyTS monomers and PyTS aggregates. The main reason was that the distance between pyrene rings was greatly expanded after the PyTS grafting on the Zr 6 clusters of Zr-BTB-MOL, which overcame the aggregation-caused quenching (ACQ) effect of PyTS and thus enhanced the ECL emission. Meanwhile, the porous nanosheet structure of PyTS-Zr-BTB-MOL could distinctly increase the exposure of PyTS luminophores and shorten the diffusion paths of coreactants and electrons/ions, which effectively promoted the electrochemical excitation of more PyTS luminophores and thus achieved a further ECL enhancement. In light of the remarkable ECL property of PyTS-Zr-BTB-MOL, it was employed as an ECL indicator to build a novel high-sensitivity ECL biosensor for microRNA-21 determination, possessing a satisfactory response range (100 aM to 100 pM) and an ultralow detection limit (10.4 aM). Overall, this work demonstrated that using MOLs to coordinatively graft the PAH derivative luminophores to eliminate the ACQ effect and increase the utilization rate of the luminophores is a promising and efficient strategy to develop high-performance Ru-complex-free ECL materials for assembling ultrasensitive ECL biosensing platforms. [ABSTRACT FROM AUTHOR]

Iron sulfide catalysts could boost the hydrogenation of polycyclic aromatic hydrocarbons, and have been widely employed in direct coal liquefaction owing to their low price and good activity. In the past, the Fe deficient structure on Fe1−xS was normally considered as the active site. Herein, the promotion effect of S vacancies on the performance in the naphthalene hydrogenation reaction was revealed. Additional S vacancies on the prepared Fe1−xS catalyst were introduced by a heat‐treatment under H2. Multiple characterization techniques verified that the density of S vacancies on catalyst surface increased with the prolonged H2 treatment time, while the Fe deficient structure displayed an opposite trend. The performance in the hydrogenation of naphthalene to tetralin was used to evaluate the catalyst activity. It was found that the sequence of naphthalene conversion over catalysts was consistent with the corresponding content of S vacancies, indicating that S vacancies were more efficient active sites. DFT calculation results revealed that both molecular H2 and naphthalene exhibited a pronounced inclination towards adsorption on S vacancies as compared to intact surface of Fe1−xS. The increasing amount of S vacancies facilitated the adsorption of reactants and the weakening of naphthalene C−C bonds. [ABSTRACT FROM AUTHOR]

Selective hydrocracking of polycyclic aromatic hydrocarbons (PAHs) from heavy oils and tar to high‐value chemicals such as benzene, toluene, and xylene (BTX) is a promising technology. Due to the lack of comprehensive and rational understanding of the reaction mechanisms, the development and preparation of catalysts and the improvement of catalysis technology are rarely carried out. Since zeolites as crucial solid acid catalyst components in catalytic hydrocracking of PAHs are indispensable, this review systematically analyzed the mechanisms and research advances in hydrogenation, isomerization, and ring‐opening (cracking) on zeolite catalysts. Efficient zeolite catalysts for hydrocracking should have appropriate pore structures for the required diffusivity for reactants and products to avoid secondary polymerization and coke formation, an ideal distribution and strength of acid sites for the formation of the desired carbocation intermediates to achieve the selectivity of products and precisely tunable metal to acid functions to control the competition between (de)hydrogenation and ring‐opening reactions leading to the facilitation of the reaction mechanisms for the desired products. This poses challenges for the research and development of industrial relevant zeolite catalysts. [ABSTRACT FROM AUTHOR]

This publication presents a comprehensive method for assessing the homogeneity of the composition of a large batch of polymer materials, with a mass of 1.5 tons, consisting of 60 transport packages, using the example of rubber granulate from recycled car tires. The presented method combines statistical analysis tools used to determine the samples number to be taken from the batch and the pyrolytic thermal desorption technique coupled with gas chromatography-mass spectrometry (Py/TD-GC-MS), used for material identification. Directions for improving the method for the quantitative identification of batch components are also indicated. The developed method can be applied to assess the purity of batches of recycled rubber granulate used in the construction of sports field surfaces and to determine the content of substances harmful to the environment and human health, such as polycyclic aromatic hydrocarbons. The direction for improving the developed spot-check control method using an alternative approach is to supplement it with a quantitative assessment of batch parameters in relation to the threshold values, such as tolerance limits. [ABSTRACT FROM AUTHOR]

With numerical simulations that employ adaptive ray-tracing (ART) for radiative transfer at the same time as evolving gas magnetohydrodynamics, thermodynamics, and photochemistry, it is possible to obtain a high-resolution view of ultraviolet (UV) fields and their effects in realistic models of the multiphase interstellar medium. Here, we analyze results from TIGRESS-NCR simulations, which follow both far-UV (FUV) wavelengths, important for photoelectric heating and polycyclic aromatic hydrocarbon excitation, and the Lyman continuum (LyC), which photoionizes hydrogen. Considering two models, representing solar neighborhood and inner-galaxy conditions, we characterize the spatial distribution and time variation of UV radiation fields, and quantify their correlations with gas. We compare four approximate models for the FUV to simulated values to evaluate alternatives when full ART is infeasible. By convolving FUV radiation with density, we produce mock maps of dust emission. We introduce a method to calibrate mid-IR observations, for example from JWST, to obtain high-resolution gas surface density maps. We then consider the LyC radiation field, finding most of the gas exposed to this radiation to be in ionization–recombination equilibrium and to have a low neutral fraction. Additionally, we characterize the ionization parameter as a function of the environment. Using a simplified model of the LyC radiation field, we produce synthetic maps of emission measure (EM). We show that the simplified model can be used to extract an estimate of the neutral fraction of the photoionized gas and mean free path of ionizing radiation from observed EM maps in galaxies. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs), including acenaphthene, pose a significant threat to aquatic ecosystems by harming vital organisms such as benthic invertebrates. This study evaluated the impact of environmentally relevant concentrations of acenaphthene on Tubifex tubifex, focusing on sublethal acute toxicity and subchronic biomarker responses. Key biomarkers assessed included histopathological changes and the modulation of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and malondialdehyde (MDA). Additionally, the study examined structure–activity relationships and species sensitivity distribution (SSD). Concentrations exceeding the solubility threshold of acenaphthene (3.9 mg/L) triggered distinct, concentration-dependent behavioral responses in Tubifex tubifex, such as clumping, mucus secretion, and body wrinkling. Prolonged exposure exacerbated these behavioral dysfunctions, while subchronic exposure resulted in significant histopathological alterations, including epithelial hyperplasia, inflammation, edema, fibrosis, and degenerative changes. The edematic appearance of the body wall suggested a potential immune response to exposure. Furthermore, increased activities of CAT, SOD, and GST indicated oxidative stress in the worms. The study found a 1.5-fold increase in CAT and GST activity, a fivefold increase in SOD, and a striking 100-fold increase in MDA levels compared to controls, signifying an overwhelmed antioxidant defense system and potential cellular disruption. The SSD curve revealed hazard concentrations (HC50 and HC90), indicating that Tubifex tubifex exhibited lower sensitivity to acenaphthene compared to other taxa. In silico analysis and read-across models confirmed the potential of acenaphthene to induce significant oxidative stress upon exposure. The correlation between biomarker responses and structure–activity relationship analysis highlighted the aromatic nature of acenaphthene as a key factor in generating reactive metabolites, inhibiting antioxidant enzymes, and promoting redox cycling, ultimately contributing to adverse outcomes. These findings, coupled with behavioral responses and SSD curve inferences, underscore the importance of the solubility threshold of acenaphthene as a critical benchmark for evaluating its ecological impact in aquatic environments. [ABSTRACT FROM AUTHOR]

AbstractIn graph theory, a graph is a mathematical structure that consists of a set of vertices and a set of edges connecting those pairs of vertices. Let G=(V,E) be a graph, a dominating set for G is a subset D⊆V of vertices such that every vertex in V∖D has at least one neighbor in D. The domination number of G, denoted by γ(G), is the minimum cardinality of a dominating set in G. Recently, Khan (2023) performed a comparative study of seven important domination parameters with the π-electronic energy of benzenoid hydrocarbons, with a new theoretical approach. Physico-chemical properties are crucial for understanding the physical and chemical behavior of a molecule. In this paper, we perform a comparative study of those seven domination parameters with the physico-chemical properties of benzenoid hydrocarbons. We find the values of those domination parameters for the 22 lower benzenoid hydrocarbons and follow the statistical approach described by Khan (2023). The two physico-chemical properties to be chosen are the normal boiling point Tb, a representative for intermolecular and van-der-Waals type interactions, whereas, the standard enthalpy/heat of formation ΔHfo is referred to represent the thermal properties of a molecular graph. This study further enhances that the performance of paired domination number is exceptional among all other parameters and highly correlated with both of the physico-chemical properties. Its correlation coefficient is 0.9981 (respectively, 0.9726) with Tb (respectively, ΔHfo). The outstanding correlation coefficient of paired domination number ensures further usage in quantitative structure-property relationship (QSPR) models. [ABSTRACT FROM AUTHOR]

Perovskite whentandemed with organic photovoltaics (OPV) for double‐junctions have efficiencypotentials over 40%. However, there is still room for improvement suchas better current matching, higher fill factor, as well as lower voltage and fill factor losses in the top perovskite cell. Here weaddress the issue associated with the top perovskite cell by utilising anovel halogenated polycyclic aromatic hydrocarbon compound, 1‐naphthylammoniumchloride (NA─Cl) playing dual roles of surface modification for the hole selectivelayer (HSL) and passivation of HSL/perovskiteinterface. Results of X‐ray photoelectron spectroscopy and density functionaltheory calculations reveal that NA─Cl retains self‐assembly property for the HSLwhile demonstrating high dipole moment and polarizability. This induces asurface dipole at the HSL/perovskite interface reducing the energetic barrierfor hole extraction by 210 meV thereby enhancing voltage output and fill factorof the device. Such scheme when implemented in a high bandgap (1.78 eV)perovskite solar cell, results in a respectable efficiency of 19.7% and thehighest fill factor of 85.4% amongst those of 1.78 eV perovskite cells reported.We have also achieved 23% cell efficient monolithic perovskite‐OPV tandem withan impressive fill factor of 84%, which is the highest for perovskite‐OPVtandem cells reported to‐date. [ABSTRACT FROM AUTHOR]

Intermolecular interactions with polycyclic aromatic hydrocarbons (PAHs) represent an important area of physisorption studies. These investigations are often hampered by a size of interacting PAHs, which makes the calculation prohibitively expensive. Therefore, methods designed to deal with large molecules could be helpful to reduce the computational costs of such studies. Recently we have introduced a new systematic approach for the molecular fragmentation of PAHs, denoted as AROFRAG, which decomposes a large PAH molecule into a set of predefined small PAHs with a benzene ring being the smallest unbreakable unit, and which in conjunction with the Molecules‐in‐Molecules (MIM) approach provides an accurate description of total molecular energies. In this contribution we propose an extension of the AROFRAG, which provides a description of intermolecular interactions for complexes composed of PAH molecules. The examination of interaction energy partitioning for various test cases shows that the AROFRAG3 model connected with the MIM approach accurately reproduces all important components of the interaction energy. An additional important finding in our study is that the computationally expensive long‐range electron‐correlation part of the interaction energy, that is, the dispersion component, is well described at lower AROFRAG levels even without MIM, which makes the latter models interesting alternatives to existing methods for an accurate description of the electron‐correlated part of the interaction energy. [ABSTRACT FROM AUTHOR]

A d10-Cd cluster containing sandwich-type arsenotungstate [C3H12N2]6[Cd4Cl2(B-α-AsW9O34)2] was synthesized and its structure characterized through elemental analyses, X-ray powder diffraction (XRPD), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and single-crystal X-ray diffraction. The X-ray analysis revealed that the molecular unit of the compound consists of a captivating tetra-Cd-substituted sandwich-type polyoxoanion, accompanied by six elegantly protonated 1,2-diaminopropane as counter ions. The further novelty of the tetranuclear cadmium cluster lies in its occupied chlorine atom sites. This makes it highly susceptible to coordinate reactions with nitrogen on polycyclic aromatic hydrocarbons, thereby exhibiting different fluorescent signals that facilitate the identification and detection of these carcinogenic substances in methanol. [ABSTRACT FROM AUTHOR]

(1) The evidence is mounting that polycyclic aromatic hydrocarbons (PAHs) are a class of hazardous organic compounds with established carcinogenic and toxic properties. Humans may be exposed to PAHs through several different routes, including diet, inhalation, and dermal contact. There is also a possibility that they could transfer into breast milk following maternal exposure, which could potentially endanger breastfeeding infants. (2) The objective of this study was to ascertain the concentration of polycyclic aromatic hydrocarbons (PAHs) in breast milk samples from 50 Hungarian mothers, employing high-performance liquid chromatography with fluorescence detection (HPLC–FLD). An Incremental Life Risk Calculation (IRCL) model estimated the carcinogenic risk to infants. (3) Total PAH concentrations ranged from 0 to 78 ng/mL, with fluorene (5.3 ng/mL), phenanthrene (3.2 ng/mL), and pyrene (2.5 ng/mL) being the most abundant. PAHs were detected in 48 of the 50 samples, with phenanthrene present in 92% of samples. Dibenzo (a,h)anthracene was not detected. (4) According to the model measurements, most of the samples were within acceptable risk levels; however, 2 samples out of 50 posed a higher risk. Statistical analysis of questionnaires completed by the mothers indicated that factors such as diet, residence, and education may influence PAH levels in breast milk. [ABSTRACT FROM AUTHOR]

Valorization of potential thermoplastic waste is an effective strategy to address resource scarcity and reduce valuable thermoplastic waste. In this study, new ecofriendly biomass-derived wood polymer composites (WPCs) were produced from three different types of recycled polyethylene (PE) municipal waste, namely linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), or high-density polyethylene (HDPE), and their blend with equal composition (33/33/33 by wt.%). Bamboo particle reinforcement derived from indigenous Ethiopian lowland bamboo (LLB), which had never been utilized before in a WPC formulation, was used as the dispersed phase. Before utilization, recycled LLDPE, MDPE, and HDPE were carefully characterized to determine their chemical compositions, residual metals, polycyclic aromatic hydrocarbons, and thermal properties. Similarly, the fundamental mechanical properties of the WPCs, such as tensile strength, modulus of elasticity, flexural strength, modulus of rupture, and unnotched impact strength, were evaluated. Finally, the thermal stability and interphase coupling efficiency of maleic-anhydride-grafted polypropylene (MAPP) were carefully investigated. WPCs formulated by melt-blending either of the recycled PEs or the blend of recycled PE with bamboo particles showed significant improvement due to MAPP enhancing interfacial adhesion and thermally induced crosslinking, despite inherent immiscibility. These results were confirmed using Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The formulated WPCs may promote PE waste cascading valorization, offering sustainable alternatives and maximizing LLB utilization. Furthermore, comparison with well-known standards for polyolefin-based WPCs indicated that the prepared WPCs can be used as alternative sustainable building materials and related applications. [ABSTRACT FROM AUTHOR]

Efficient and harmless treatment of microplastics in soil is the current focus of microplastic pollution management. In this study, the pyrolysis effect of soil microplastics at different temperatures and holding times was analyzed. The results showed that temperature and holding time significantly affected the morphology and compositional structure of soil. Pure microplastics and product adhesion after pyrolysis at low temperature (400°C) were not easy to remove. Interestingly, compared with pure polyethylene (PE), direct pyrolysis of microplastics in soil could obtain better results, and the content of organic matter and polycyclic aromatic hydrocarbons (PAH) could be significantly reduced. However, the pyrolysis performance was very unsatisfactory even if the action time was prolonged at 400°C. Prolonged high‐temperature treatment accelerated the fragmentation of the alkane main chain of PE, thus generating more PAH, and the temperature was not high enough (400°C) for further effective degradation of PAH into carbon dioxide and water. Therefore, higher temperature and longer holding time need to be selected to ensure the pyrolysis performance. This study revealed the role and mechanism of pyrolysis in soil microplastic mixed systems, aiming to provide a basis for the treatment of microplastics in terrestrial ecosystems. Core Ideas: Mixing soil and microplastics can achieve better thermal degradation effects.At 400°C pyrolysis, more polycyclic aromatic hydrocarbons were produced.Pyrolysis at 600°C reduced polycyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

Acenes or polyacenes are a group of organic compounds and polycyclic aromatic hydrocarbons consisting of benzene ( C 6 H 6) rings that are linearly fused. They are also the building blocks of nanotubes and graphene and follow the general molecular formula C 4 n + 2 H 2 n + 4 . Due to the applications of polyacenes in optoelectronics, they are interesting for chemical and electrical engineering researchers. In this article, the general formulas for distance-based topological indices of Szeged, Mostar, and Padmakar-Ivan are determined by SMP-polynomials, which do not require edge counting and this formula work only by having the number of benzene rings in the composition of polyacenes. [ABSTRACT FROM AUTHOR]

Rate of horizontal movement of a pollutant such as polycyclic aromatic hydrocarbons in soil plays a major role in spread of pollutants in the segments of the environment. However, the study regarding this aspect is not widely reported. In the present work, the rate of horizontal spread of Fluorene in soil is determined in an experiment spread over a year under natural environment. Known amount of the hydrocarbon was added to a soil at a particular point, extraction of the same was done later on at definite time interval at definite distances from the point of application and quantitative determination was done by HPLC analysis of the extract. Eleven number of important physico-chemical parameters of the soil sample were determined/calculated in order to know the quality of the soil. The values of parameters are in agreement to the characteristics of a good soil. The experimental soil is a mild acidic sandy loam. It has been found that one-year time is sufficient for the applied quantity of the hydrocarbon to spread itself uniformly to attain a concentration, which is at par with natural concentration of the hydrocarbon in the experimental soil. Studies on kinetics of the reaction imply that the reaction occurs in different phases, rate constants being gradually increased with time. The positive influence of increase in ambient temperature and rainfall on disappearance of the hydrocarbon is seen in the experiment. It has been found that the most probable speed of the hydrocarbon for horizontal movement is 3.75 cm per month in the experimental soil. [ABSTRACT FROM AUTHOR]

This study investigated the level of polycyclic aromatic hydrocarbons (PAHs) in seafood, namely, C. sapidus (Crab), P. mollusca (Mollusc), Cambarus sp. (Crayfish), Caridea (Shrimp) from Orashi River in Omoku, Rivers State of Nigeria. The PAHs in the samples were determined by gas chromatography–mass spectrometry. There was no variation in the relative level of PAHs congeners. The mean concentrations of individual PAHs decreased in the order: D(a,h)ant > Pyr > Fluth > B(g,h,i)p > B(a)A > B(b)f > Ind (1,2, 3)pyr > B(a)pyr > Chr > B(k)flu > Ant > Flu > Phen > Aceth > Ace > Nap. Anthracene contributed the highest PAHs values, with 51.685% in Caridea. The EDI values of B(a)P, Ʃ2PAH, Ʃ4PAH, Ʃ8PAH across all the seafood were within the maximum permissible limit recommended by EFSA; this suggests that the accumulation of the PAHs in the body system are within the permitted levels. Similarly, the HI of the PAHs congeners obtained from this study were less than 1 which is the safe limit recommended by USEPA. The total Excess Cancer Risk of the PAHs congeners obtained from this study exceeded the permissible maximum limit recommended by USEPA. This study suggests that the water may be contaminated with PAHs which have the tendency to cause non-carcinogenic and carcinogenic risk because of frequent and high consumption of seafoods. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) exposure is associated with cardiovascular diseases. Toxic effects of PAHs are diverse, while cardiovascular consequences of benzo[ b ]fluoranthene (B[ b ]F) are unclear. Here, we reported the impacts of B[ b ]F on coronary artery and atherosclerosis markers both in mice and umbilical vein endothelial EAhy.926 cells. In mice, we found that B[ b ]F decreases heart-to-body weight ratio, affects aortic physiology, elevates serum low-density lipoprotein and total cholesterol, increases aortic levels of collagen fiber and atherosclerotic marker vascular cell adhesion molecule-1 (VCAM-1), and downregulates oxidative stress related nuclear factor erythroid 2-related factor 2 (Nrf2). In EAhy.926 cells, we showed that B[ b ]F inhibits cell proliferation and migration in a dose-dependent manner, induces cell cycle arrest and apoptosis, increases reactive oxygen species, upregulates VCAM-1 level, and suppresses expression of Nrf2. Taken together, our findings reveal that B[ b ]F exposure may contribute to coronary artery damage and potentially induce atherosclerosis, possibly via the Nrf2-related signaling pathways. • B[ b ]F elevates serum low-density lipoprotein and total cholesterol in mice. • B[ b ]F increases aortic collagen fiber and VCAM-1, and reduces Nrf2 in mice. • B[ b ]F inhibits proliferation and migration of EAhy.926 cells. • B[ b ]F induces cell cycle arrest and apoptosis of EAhy.926 cells. • B[ b ]F increases ROS and VCAM-1, and reduces Nrf2 in EAhy.926 cells. [ABSTRACT FROM AUTHOR]

Polycylic Aromatic Hydrocarbons (PAHs) are produced during the incomplete burning of organic materials. PAH sources include vehicle exhaust, tobacco smoke and waste incineration. Environmental and occupational exposures to PAHs are known to occur. Cancer is a significant endpoint of PAH exposure and several occupations associated with high PAH exposure have been classified by IARC as carcinogenic to humans (Group 1). Pyrene is a common component of PAH mixtures and metabolism of pyrene leads to the excretion of 1-hydroxypyrene glucuronide (1-OHPyrG) in urine. Laboratory measurement of urinary 1-OHPyrG is employed in occupational and environmental biomonitoring programmes. The production of an anti-1-OHPyrG monoclonal antibody would allow the development of a PAH biomonitoring ELISA facilitating large scale laboratory screening and routine testing. The development of a lateral flow immunoassay and the production of a field test (point of use test) would greatly increase the value of biomonitoring. A novel Lateral Flow has been developed which employs an anti-1-OHPyrG sheep monoclonal antibody (Mab) to capture the PAH metabolite. The captured metabolite is visualised through a second Mab raised against the Mab-1-OHPyrG immune complex. This sandwich assay provides a positive correlation between the assay signal and biomarker concentration. A Smartphone camera allows signal measurement and a carefully considered 'app' provides result interpretation and data analysis. Results are provided in an exposed/not-exposed format. Performance of the lateral flow was confirmed through a comparative study and field trial. The development of a lateral flow test provides "real-time" analysis to occupational health professionals. On-site screening allows the immediate confirmation of safe working practice, provides immediate reassurance to those involved in potentially hazardous activities and greatly increases the efficacy of biomonitoring. • A novel lateral flow allows in the field/on-site PAH biomonitoring. • LF testing and integration with mobile technology provides new biomonitoring methods. • On-site testing greatly increases the value of occupational biomonitoring. • A new PAH biomonitoring ELISA facilitates large scale screening programmes. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds frequently detected in the environment with widely varying toxicities. Many PAHs activate the aryl hydrocarbon receptor (AHR), inducing the expression of a battery of genes, including xenobiotic metabolizing enzymes like cytochrome P450s (CYPs); however, not all PAHs act via this mechanism. We screened several parent and substituted PAHs in in vitro AHR activation assays to classify their unique activity. Retene (1-methyl-7-isopropylphenanthrene) displays Ahr2-dependent teratogenicity in zebrafish, but did not activate human AHR or zebrafish Ahr2, suggesting a retene metabolite activates Ahr2 in zebrafish to induce developmental toxicity. To investigate the role of metabolism in retene toxicity, studies were performed to determine the functional role of cyp1a , cyp1b1 , and the microbiome in retene toxicity, identify the zebrafish window of susceptibility, and measure retene uptake, loss, and metabolite formation in vivo. Cyp1a-null fish were generated using CRISPR-Cas9. Cyp1a-null fish showed increased sensitivity to retene toxicity, whereas Cyp1b1-null fish were less susceptible, and microbiome elimination had no significant effect. Zebrafish required exposure to retene between 24 and 48 hours post fertilization (hpf) to exhibit toxicity. After static exposure, retene concentrations in zebrafish embryos increased until 24 hpf, peaked between 24 and 36 hpf, and decreased rapidly thereafter. We detected retene metabolites at 36 and 48 hpf, indicating metabolic onset preceding toxicity. This study highlights the value of combining molecular and systems biology approaches with mechanistic and predictive toxicology to interrogate the role of biotransformation in AHR-dependent toxicity. [ABSTRACT FROM AUTHOR]

Introduction: Heavy metals (HM) and polycyclic aromatic hydrocarbons (PAHs) exposition has been associated with health problems. Therefore, this research evaluated genotoxicity induced in male mice strain CD-1 exposed to benzo[a]anthracene (B[a]A) and benzo[a]pyrene (B[a]P) and their interaction with Fe, Pb, and Al. Methods: Groups of animals were exposed intraperitoneally to HM, PAHs, and mixtures of both. Peripheral blood samples were taken from 0 to 96 h at 24 h intervals; genotoxicity was determined by micronucleus tests and comet assay. Additionally, toxicity and viability were evaluated. Results: HM and PAHs individually were genotoxic. About toxicity, only Al altered polychromatic erythrocytes number and did not change leukocytes viability. Concerning mixtures, Fe + B[a]P, Fe + B[a]A, Pb + B[a]P increased genotoxicity. There were no changes with Pb + B[a]A. Finally, Al mixtures with both PAHs damage was decreased. Conclusions: Exposure to HM and PAH caused genetic damage. Fe, Al, and B[a]A, established a genotoxic potential. Every metal can interact with PAHs in different ways. Also, the micronucleus test and the comet assay demonstrated their high capacity and reliability to determine the genotoxic potential of the compounds evaluated in this work. [ABSTRACT FROM AUTHOR]

In this study, pollution level, distribution, toxicity, molecular composition, probable sources as well as health risks of polycyclic aromatic hydrocarbons (PAHs) in urban and industrial soils of Kerman metropolis were investigated. Kerman is a fast-growing city and a fine example of an arid city in a developing country. For this purpose, concentrations of 16 individual PAHs in 30 samples taken from the city soils and its industrial zones were determined by gas chromatography/mass spectrometry. The ∑PAHs concentration in urban soil samples varied from 26.1 to 902.8 μg/kg, with the mean and median of 302.6 and 148.4 µg/kg, respectively. In comparison, ∑PAHs in industrial soils ranged from 26.8to 251.9 μg/kg, with the mean and median values of 65.9 and 42.9 µg/kg, respectively. Four-ring PAHs comprise the dominant compounds in urban soils, whereas, two- and three-ring PAHs proved to be the most abundant compounds in industrial soils. Source apportionment was conducted using ring classification, diagnostic ratios, PCA, and multilinear regression (MLR). Also, human health risk assessment was undertaken through employing US EPA standard statistical models. This survey revealed that PAH pollution in urban soils originates mainly from fossil fuel combustion and in industrial soils from petrogenic sources. On the whole, in the Kerman environment, the shares of petroleum combustion, natural gas combustion, and petrogenic sources were 45.32%, 34%, and 20.68% respectively. Based on this study, the ecological risk of PAHs was low-to-moderate, and incremental lifetime cancer risk for children and adults were 1.35 × 10−4 and 1.04 × 10−4 respectively, indicating rather high risks. [ABSTRACT FROM AUTHOR]

Elucidating pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in water and assessing the associated carcinogenic risks is crucial for improving public health. PAHs in the surface water of seven main river basins across China, compiled from 95 studies from 2004 to 2022, were used to investigate geographic variations of occurrence, source, and carcinogenic risk. Total PAH concentrations exhibited substantial geographic distributions ranging from 300 to 7552 ng·L−1. Low molecular weight PAHs predominated, showing three-ring PAHs abundant in the north, while two-ring PAHs dominated in the south due to distinctions regarding energy consumption. The northern basins exhibited higher concentrations of PAHs than the southern owing to the synergistic impacts of low temperature, increased energy consumption, and higher industrial activities. Coal combustion and industrial emissions were the primary contributors in the northern basins, accounting for 23–44% and 20–38%, respectively, which were associated with pollutants released from heavy industries and space heating during cold periods. In contrast, vehicle exhaust emissions and petroleum leakage from river transport constituted the principal sources in the relatively economically developed southern basins, accounting for 24–35% and 31–57%, respectively. A lifetime carcinogenic risk model revealed that the highest health risks existed in adults, followed by adolescents and children. Toxic concentrations of BaP and the daily intake of water directly enhanced the PAHs' carcinogenic risks, while body weight featured negative correlations with the risks. [ABSTRACT FROM AUTHOR]

There has been a growing perception of organic pollutants as a threat to the environment. Because of their high persistence in the soil and significant toxicity at extremely low levels of exposure, organic contaminants pose a constant threat in the ecosystem. The most prevalent categories of organic pollutants found in the environment are pesticides, dye pollutants, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dichlorodiphenyltrichloroethane etc. However, researchers have gathered a great deal of knowledge about the source, pathways of contamination to the environment, interactions with constituents, impact on soil microbes and degradability by plants, uptake by plants, and contamination of food. The multifaceted effects on the ecosystem include contaminated food, water, and air, decreased soil enzyme activity that disrupts nutrient transformation processes, decreased biodiversity, and mutagenicity in microorganisms, among other things. Nonetheless, the review covered the origins, effects, and eventual disposal of organic pollutants within the ecosystem. [ABSTRACT FROM AUTHOR]

Anthracene, a polycyclic aromatic hydrocarbon (PAH) from fossil fuel combustion, poses significant environmental threats. This study investigates the role of abscisic acid (ABA) in the anthracene tolerance of the liverwort Marchantia polymorpha using mutants deficient in ABA perception (Mppyl1) or biosynthesis (Mpaba1). In this study, we monitored the role of ABA in the anthracene tolerance response by tracking two ABA-controlled traits: plant growth inhibition and gemmae dormancy. We found that the anthracene-induced inhibition of plant growth is dose-dependent, similar to the growth-inhibiting effect of ABA, but independent of ABA pathways. However, gemmae dormancy was differentially affected by anthracene in ABA-deficient mutants. We found that gemmae from anthracene-exposed WT plants exhibited reduced germination compared to those from mock-treated plants. This suggests that the anthracene exposure of mother plants induces a transgenerational effect, resulting in prolonged dormancy in their asexual propagules. While Mppyl1 gemmae retained a dormancy delay when derived from anthracene-exposed thalli, the ABA biosynthesis mutant Mpaba1 did not display any significant dormancy delay as a consequence of anthracene exposure. These results, together with the strong induction of ABA marker genes upon anthracene treatment, imply that anthracene-induced germination inhibition relies on ABA synthesis in the mother plant, highlighting the critical role of MpABA1 in the tolerance response. These findings reveal a complex interplay between anthracene stress and ABA signaling, where anthracene triggers ABA-mediated responses, influencing reproductive success and highlighting the potential for leveraging genetic and hormonal pathways to enhance plant resilience in contaminated habitats. [ABSTRACT FROM AUTHOR]

The chemical composition of honey, and therefore its quality and properties, is influenced by many factors, including its botanical origin and the harvesting conditions—the location of the apiary, access to melliferous plants, the proximity of industrial infrastructure and communication routes, etc. This quality may be reduced by undesirable, toxic compounds that penetrate honey from a contaminated environment, such as heavy metals and residues from other environmental pollutants. Therefore, the aim of our research was to assess the quality of honeys from urbanized areas—in particular, to assess contamination with heavy metals and persistent organic pollutants (PAHs). In total, 35 samples from six different apiaries located in urbanized areas were examined. The content of heavy metals (Cd, Pb, Zn) was determined by atomic absorption spectrophotometry (AAS), and the content of total PAHs as the sum of the concentrations of the compounds benzo(a)anthracene, chrysene, benzo(b)fluoranthene and benzo(a)pyrene was determined by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The average zinc content ranged from about 2 to 4.5 mg/kg, the average lead content ranged from 3.5 µg/kg to 388 µg/kg and the average cadmium content ranged from 0.5 to 14 µg/kg. It was found that all honeys contained certain amounts of harmful metals, and only lead exceeded the permissible limits. None of the samples tested contained sum content of PAHs exceeding 10 µg/kg of honey. Contrary to our expectations, the results obtained indicate that honeys from urbanized areas do not contain these harmful substances. In general, the presence of harmful metals does not, however, reduce honey's quality or its health value. [ABSTRACT FROM AUTHOR]

Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon, is known to cause teratogenesis. Environmental exposure of BaP has led to wide public concerns due to their potential risk of reproductive toxicity. However, the exact mechanism is still not clear. We aimed to explore the alterations of oxidative stress and DNA hydroxymethylation during BaP‐impaired reproductive function. BALB/c mice were intragastrically administered with different doses of BaP (0.01, 0.1, and 1 mg/kg/day, once a day), while control mice were administered with corn coil. Then, the reproductive function, alterations of oxidative stress, DNA methylation, and DNA hydroxymethylation of testis tissues were evaluated. We found that BaP caused obvious histopathological damages of testis tissues. As for sperm parameters after BaP administration, testis weight and the rate of teratosperm were increased, as well as sperm count and motility were decreased. In mechanism, BaP upregulated HO‐1 and MDA levels and downregulated SOD and CAT activity and GSH content in testis tissues, indicating that oxidative stress was induced by BaP. Furthermore, a significant induction of hydroxymethylation and inhibition of methylation were observed in testis tissues after BaP exposure. Collectively, BaP‐induced oxidative stress and hydroxymethylation were involved in impairing reproductive function, which may be the mechanism of the male infertility. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated biosurfactant production by the bacterial strain of P. aeruginosa gi |KP 163922| for a free and immobilized cells system using waste engine oil (WEO) as a substrate. The polyurethane foam (PUF) cubes (1 cm × 1 cm × 1 cm) were used as carriers for the immobilization. The batch experiments were performed in Erlenmeyer flasks and monitored at every 24‐h interval for both cell systems. The microbial population was counted using the plate count method, and the hydrocarbon degradation percentage was calculated to evaluate the bacterial activity. Surface tension was measured at regular intervals to ensure the presence of biosurfactants. The maximum reduction was 37 and 35 mN/m in a free and immobilized cells system. Immobilization of cells using PUF was found to be efficient in supporting bacterial growth, and after 48 h of incubation, the growth was 2.5 (±0.58) × 1011 CFU/mL. The chemical characterization using Fourier transform infrared (FTIR) spectroscopy confirmed the obtained product as rhamnolipid. Crude biosurfactant yield was found to be maximum in the case of the immobilized system, which was approximately 18 g/L. Scanning electron micrographs (SEM) of the used PUF cubes showed the strong adherence of biofilm to the cube surface and the potential of its reuse in multiple cycles. Gas chromatography–mass spectrometry (GC–MS) analysis confirms that the immobilized strain of P. aeruginosa exhibited superior biodegradation capabilities compared to free cells. Specifically, it was capable of reducing the concentration of polyaromatic hydrocarbons and converting more significant aliphatic compounds into metabolic byproducts such as alkanes, alkenes, cycloalkanes, and carbonyl groups. [ABSTRACT FROM AUTHOR]

Road dust resuspension in urban environments can contribute to high human exposure to metal(loid)s, polycyclic aromatic hydrocarbons, and other potentially toxic organic compounds. However, for many regions, information on loadings, emission factors and chemical profiles is lacking to accurately apply emission inventories and source apportionment models. In the present study, PM10 samples were collected with an in situ road dust sampler from eleven representative streets of Bragança, an inland city of the Iberian Peninsula, and were analysed for organic and elemental carbon by a thermal-optical technique, elemental composition by ICP-MS and ICP-OES, and ecotoxicity by a luminescence inhibition bioassay with Allivibrio fischeri. A global emission factor of 5.36 ± 2.35 mg veh−1 km−1 was obtained but in suburban areas the values reached twice the average. Total carbon accounted for 14.9 ± 6.8% of the PM10 mass, while element oxides represented the largest share (28.6 ± 18.7%). Very high enrichments were found for typical traffic-related elements such as Cu, Zn, S, Pb and Ni. The geochemical index Igeo further confirmed that road dust of the study region is extremely contaminated by elements mainly originated from tyre and brake wear. Although the total non-carcinogenic and carcinogenic risks associated with metal exposure were found to be low for both children and adults, the bioluminescence inhibition assay showed (eco)toxic responses for all samples, indicating that road dust resuspension may pose a significant human health and ecological threat. [ABSTRACT FROM AUTHOR]

Understanding the health risks of polycyclic aromatic hydrocarbons (PAHs) in dust from city parks and prioritizing sources for control are essential for public health and pollution management. The combination of Source-specific and Monte Carlo not only reduces management costs, but also improves the accuracy of assessments. To evaluate the sources of PAHs in urban park dust and the possible health risks caused by different sources, dust samples from 13 popular parks in Kaifeng City were analyzed for PAHs using gas chromatograph-mass spectrometer (GC-MS). The results showed that the surface dust PAH content in the study area ranged from 332.34 µg·kg−1 to 7823.03 µg·kg−1, with a mean value of 1756.59 µg·kg−1. Nemerow Composite Pollution Index in the study area ranged from 0.32 to 14.41, with a mean of 2.24, indicating that the overall pollution warrants attention. Four pollution sources were identified using the positive matrix factorization (PMF) model: transportation source, transportation-coal and biomass combustion source, coke oven emission source, and petroleum source, with contributions of 33.74%, 25.59%, 22.14%, and 18.54%, respectively. The Monte Carlo cancer risk simulation results indicated that park dust PAHs pose a potential cancer risk to all three populations (children, adult male and adult female). Additionally, the cancer risk for children was generally higher than that for adult males and females, with transportation sources being the main contributor to the carcinogenic risk. Lastly, sensitivity analyses results showed that the toxic equivalent concentration (CS) is the parameter contributing the most to carcinogenic risk, followed by Exposure duration (ED). [ABSTRACT FROM AUTHOR]

In this research, for the first time, 16 polycyclic aromatic hydrocarbons (PAHs) in 33 types of honey samples have been analyzed using an efficient, sensitive and rapid high-density solvent-microextraction (HDS-ME) technique coupled to gas chromatography-mass spectrometry (GC-MS). Important parameters in the extraction process were optimized using central composite design (CCD). Good linear relationships were chosen for 16 PAHs in the range of 1–200 ng g−1, with a correlation coefficient (R2) higher than 0.94. The limits of detection and limits of quantification were 0.3–0.8 ng g−1 and 0.9–2.4 ng g−1, respectively. The relative standard deviations for six similar analyses at the optimized point were less than 9%. The recoveries of the proposed method were obtained between 86% and 102%. High recovery, low consumption of the solvent, speed, ease of use and good elimination of matrix interference compared to other methods are the advantages of the proposed method. The performance of the present work was confirmed by the standard addition method and satisfactory results were obtained. The concentrations of PAHs in honey samples were found lower than 11 ng g−1. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread organic contaminants in the environment, and anthropogenic activities can produce PAHs through a variety of pyrogenic or petrogenic means. Knowing the concentrations and sources of PAHs helps evaluate ecosystem health and manage natural resources. In this study, 16 US Environmental Protection Agency priority PAHs were analyzed in water and sediment samples collected from September 2021 to September 2023 in four bay systems along the south and central Texas coast, which are a hotpot of crude oil transportation in the United States. Our results indicated that the total concentration of PAHs ranged from 1.9 to 8.3 ng/mL in surface waters (< 0.5 m) and from 520 to 1257 ng/g in surface sediments (top 5 cm). Grain size analysis revealed that the sediment was dominated by silt (4 - 63 µm), followed by clay (< 4 µm) and sand (> 63 µm) fractions. Both organic carbon and clay content were shown to play a significant role in controlling the PAH content in sediments. Diagnostic ratios indicated that PAHs were primarily sourced via pyrolytic processes, such as the combustion of fossil fuels. Additional sampling at Port Bay, a shallow, secondary bay in the Mission-Aransas National Estuarine Research Reserve, implicated a strong role of resuspension in the distribution and composition of PAHs in the bay systems studied. Overall, these data offer insights into the concentration levels and sources of PAHs in this key region housing oil production and transportation in the United States. [ABSTRACT FROM AUTHOR]