Naphthalene Research Articles

Compensated Ferrimagnetism and Half‐Metallic Behavior in Potassium (K) Intercalated Naphthalene

Compensated Ferrimagnetism and Half‐Metallic Behavior in Potassium (K) Intercalated Naphthalene

The Isopropylation of Naphthalene over USY Zeolite with FAU Topology. The Selectivities of the Products

Abstract The isopropylation of naphthalene (NP) over USY zeolite (FAU06, SiO2/Al2O3 = 6) gave all eight possible diisopropylnaphthalene (DIPN) isomers: β,β- (2,6- and 2,7-), α,β- (1,3-, 1,6-, and 1,7-), and α,α- (1,4- and 1,5-). The catalyses are operated under kinetic and/or thermodynamic controls depending on the reaction temperatures because the cavities of FAU topology are wide enough to form all DIPN isomers. Enhanced selectivities for β,β-DIPN were observed at the early stages at 200, 250, and 300 °C although the selectivities decreased with the increasing periods, accompanying the increase in α,α- and α,β-DIPN. The enhancement occurs under new types of thermodynamic controls through thermodynamically preferred transition states to β,β-DIPN. Triisopropylnaphthalene (TriIPN) isomers are also formed in the isopropylation. Unstable α,α,β-TriIPN (1,4,6- and 1,3,5-) is predominantly formed at lower temperatures; however, decreased with the increase of stable α,β,β-TriIPN (1,3,6- and 1,3,7-) at higher temperatures. The predominant formation of 1,4,6-TriIPN was also observed in the initial stages in the range of 200, 250 and 300 °C, as reaction period was increased, while the selectivity for the isomer was decreased with concomitant increase in the selectivities for the other isomers. These changes of the selectivities operated under kinetic and/or thermodynamic controls. Large cavities of the zeolite allow the formation of all TriIPN isomers without steric restriction.

New Approach to Synthesis of Tetralin via Naphthalene Hydrogenation in Supercritical Conditions Using Polymer-Stabilized Pt Nanoparticles

Supercritical (SC) fluid technologies are well-established methods in modern green chemical synthesis. Using SC fluids as solvents instead of traditional liquids gives benefits of higher diffusivity and lower viscosity, which allows mass transfer intensification and, thus, an increased production rate of chemical transformations. Therefore, a conjugation of heterogeneous catalysis with SC media is a large step toward a green chemistry. Tetralin (TL) is an important hydrogen donor solvent used for biomass liquefaction. In industry, TL is obtained via catalytic hydrogenation of naphthalene (NL). Herein, for the first time we have demonstrated the NL hydrogenation with close to 100% selectivity to TL at almost full conversion in the SC hexane. The observed transformation rates in SC hexane were much higher allowing process intensification. The downstream processes can be also facilitated since hexane after depressurisation can be easily separated from the reaction products via simple rectification. The TL synthesis was studied in a batch reactor at variation of reaction temperature and overall pressure. For the first time for this process, low Pt-loaded (1 wt.%) nanoparticles stabilized within hyper-cross-linked aromatic polymer (HAP) were applied. The Pt/HAP catalyst was stable under reaction conditions (250 °C, 6 MPa) allowing its recovery and reuse.

Synergic effects on degradation of a mixture of polycyclic aromatic hydrocarbons in a UV slurry photocatalytic membrane reactor and its cost estimation

In this study, batch experiments were conducted to investigate the removals of three polycyclic aromatic hydrocarbons (PAHs) namely phenanthrene (PHE), naphthalene (NAP) and acenaphthene (ANA) as a mixture during photocatalysis (UV-TiO2), membrane separation (MS) and integrated photocatalytic membrane (UV-TiO2 + MS) processes in an indigenously developed integrated photocatalytic membrane reactor (PMR). Synergic effects were observed during the removals of model compounds when they were in the mixture as compared to their removals as a sole compound in aqueous solutions. The mineralization efficiencies in terms of total organic carbon (TOC) removals were also evaluated during UV-TiO2 and UV-TiO2 + MS processes. The degradation of PAHs mixture during photocatalytic degradation followed the pseudo-first order kinetics. Furthermore in this study, the cost estimation of PMR was carried out by calculating the treatment cost for both advanced oxidation process (AOP) system and membrane (MS) process separately. The treatment cost per m3 of effluent containing PAHs in PMR was found to be $ 10.4 to $ 13.6 or ₹ 728 to ₹ 752.

Highly redox-active organic molecular nanomaterials: Naphthalene and phenanthrene molecular species π-stacked MWCNT modified electrodes for oxygen-interference free H2O2 sensing in neutral pH

Electrochemical detection of Hydrogen peroxide in neutral pH is an important analytical problem that has been often worked out using horseradish peroxide (HRP) enzyme coupled with organic redox-active molecules as a transducer, and metallic systems in the form of metal nanoparticles and complexes chemically modified electrodes. Owing to non-amenable characteristic, direct electrochemical oxidation/reduction of H2O2 by redox-active organic molecules has been rarely described in the literature. Herein, we report naphthalene (NaP) and phenanthrene (PhenE) moieties immobilized MWCNT as advanced organic nanomaterial systems for enzyme-free, selective (dissolved oxygen, cysteine, citric acid, ascorbic acid, uric acid and glucose-interference free) and direct electrocatalytic reduction and sensing of H2O2 in neutral pH. These new organic-materials have been prepared by multiwall carbon nanotube (MWCNT) surface-bound electrochemical oxidation of NaP and PhenE at ~1.2 V vs Ag/AgCl in pH 2 KCl-HCl solution. The “as prepared” organic molecular materials showed a highly symmetrical voltammetric signal in cyclic voltammetric technique (peak-to-peak separation potential, ΔEp = 10 mV at scan rate = 10 mV s−1) and proton-coupled electron-transfer in characteristic. These new materials were characterized using several physicochemical techniques such as FTIR and Raman spectroscopes, transmission electron-microscope and electrochemical characterization (using radical quenching molecular system, 2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO)). From the collective experimental results, it has been revealed that cationic radical species like organic molecules are stabilized on the organic nanomaterial modified electrode surface (via strong π-π interaction) and showed the redox peak. Amperometric i-t responses of the modified electrodes showed a systematic variation in the H2O2 detection current signal with current linearity in a range of 25–300 μM. Calculated current sensitivities and regression coefficient values are 4.8 nA μM−1 and 0.9996 with NaP-Redox and 4.20 nA μM−1 and 0.9994 with PhenE-Redox systems, respectively.

Determination of Volatile Organic Compounds in Water by Attenuated Total Reflection Infrared Spectroscopy and Diamond-Like Carbon Coated Silicon Wafers

Volatile organic compounds (VOCs) are one of the most commonly detected contaminants in water. The occurrence is mainly in gasoline and other petroleum-based products, fumigants, paints and plastics. Releases into the environment and the widespread use have an impact on the ecosystem such as humans and animals due to their toxicity, mutagenicity, and carcinogenicity. VOCs may persist in groundwater and may enter drinking water supplies. In this paper, a diamond-like carbon (DLC)-coated silicon waveguide in combination with a polymer film (ethylene/propylene copolymer, E/P-co) for enrichment of analytes was investigated to determine its suitability for ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopic detection of VOCs. The DLC film was fluorine-terminated enhancing the adhesion of the hydrophobic polymer to the waveguide surface. The analytes diffuse into the hydrophobic polymer whereas water is excluded from the emanating evanescent field. Therefore, direct detection in aqueous systems is enabled. Nine VOCs, i.e., ethylbenzene (EB), trichloroethylene (TCE), tetrachloroethylene (TeCE), the xylene isomers (p-xylene, pXYL; m-xylene, mXYL; o-xylene, oXYL), naphthalene (NAPH), toluene (TOL), and benzene (BENZ), were evaluated simultaneously qualitatively and quantitatively showing the potential of DLC coatings revealing high sensitivities in the low ppb to ppm concentration range, i.e., 50 ppb for TeCE. To the best of our knowledge, this is the first time of IR spectroscopic detection of VOCs in aqueous solutions using DLC-coated waveguides in combination with a hydrophobic polymer. By utilizing a DLC-coated waveguide, a versatile sensor for real-time monitoring in harsh environments such as effluents, leaking pipelines, and underground storage tanks is feasible due to response times within a few minutes.

Kinetic model of steam reforming for heavy tar decomposition in biomass gasification

Gasification technology as a feasible clean and efficient utilization technology has been developed to convert the low-grade energy resources like biomass into high value syngas.The generation of syngas is often accompanied by tar formation, which causes blockage in the downstream processing as tar condenses. The elimination of naphthalene and pyrene as heavy tar model compounds by steam reforming was studied by experiments in a horizontal tube reactor and simulation with CHEMKIN. A good agreement between the measured and calculated results of light gas products and soot was obsvered, and one can found that the reactivity of naphthalene is higher than that of pyrene in the presnece of steam and most of carbon of both hydrocarbons convert into soot instead of light gaseous products. The reaction pathways of steam reforming were developed by sensitivity analysis and rate of production. Benzene and naphthalene, represented as precursor of light gas product, are dominated intermediate components of naphthalene and pyrene. The simplified reaction schemes including the reaction pathway as well as the associated kinetics were derived by CHEMKIN.

The effects of functional groups on the sorption of naphthalene on microplastics

Ubiquitous microplastics were recognized as an ideal carrier for polycyclic aromatic hydrocarbons (PAHs) to spread in nature or transfer to biota, thus posing risks to human health. However, little is known about how the functional groups in PAH derivatives influence their sorption onto microplastics as compared to parent PAHs. This study investigated the sorption of naphthalene (NAP) and its derivatives onto polystyrene microspheres with (MP-COOH) or without (MP) surface modification of the carboxyl group. NAP derivatives with charged groups (e.g., –NH2, –OH and –COOH) reached the sorption equilibrium more early than NAP and its derivative with an uncharged group (e.g., –CH3), whereas their sorption capacities (Kd = 6.0–8.4 L/g for MP, Kd = 4.5–6.3 L/g for MP-COOH) were significantly lower than that of the latter (Kd = 11.6–12.0 L/g for MP, Kd = 9.4–10.0 L/g for MP-COOH). The inhibition of charged groups on sorption could be attributed to their facilitation on molecular polarity and, thus, their lower hydrophobicity (LogKOW) since hydrophobicity was the crucial factor controlling the sorption of NAP and NAP derivatives onto both MP and MP-COOH. Computational modeling further showed that charged functional groups would weaken the π-π interaction or strengthen the repulsion between NAP or NAP derivative molecule and MP or MP-COOH molecule, which might also contribute to the suppressed sorption. This study provides new insight into the affinity of PAH derivatives with microplastics, which, therefore, improves our understanding of the environmental fates of microplastics and the organic pollutants.

Singlet and Triplet Excited-State Dynamics of 3,7-Bis(arylethynyl)phenothiazines: Intramolecular Charge Transfer and Reverse Intersystem Crossing

A series of 3,7-bis(arylethynyl)-substituted phenothiazine-based fluorophores (bearing benzene, naphthalene, methoxynaphthalene, anthracene, phenanthrene, and pyrene) were designed and synthesized ...

Contribution of Pulmonary CYP-mediated Bioactivation of Naphthalene to Airway Epithelial Injury in the Lung

Previous studies have established that cytochrome P450 enzymes (CYPs) in both liver and lung are capable of bioactivating naphthalene (NA), an omnipresent air pollutant and possible human carcinogen, in vitro and in vivo. The aim of this study was to examine the specific contribution of pulmonary CYPs in airway epithelial cells to NA-induced airway toxicity. We used a lung-Cpr-null mouse model, which undergoes doxycycline-induced, Cre-mediated deletion of the Cpr (a redox partner of all microsomal CYPs) gene specifically in airway epithelial cells. In 2-month-old lung-Cpr-null mice, Cpr deletion occurred in 75%-82% of epithelial cells of conducting airways. The extent of NA-induced acute lung toxicity (as indicated by total protein concentration and lactate dehydrogenase activity in bronchoalveolar lavage fluid collected at 24-h after initiation of a 4-h, nose-only, 10-ppm NA inhalation exposure) was substantially lower (by 37%-39%) in lung-Cpr-null mice, compared with control littermates. Moreover, the extent of cellular proliferation (as indicated by 5-bromo-2'-deoxyuridine incorporation) was noticeably lower in both proximal and distal airways (by 59% and 65%, respectively) of NA-treated lung-Cpr-null mice, compared with control littermates, at 2-day post-NA inhalation exposure. A similar genotype-related difference in the extent of postexposure cell proliferation was also observed in mice exposed to NA via intraperitoneal injection at 200 mg/kg. These results directly validate the hypothesis that microsomal CYP enzymes in airway epithelial cells play a large role in causing injury to airway epithelia following exposure to NA via either inhalation or intraperitoneal route.

Characterization of outdoor air pollution from solid fuel combustion in Xuanwei and Fuyuan, a rural region of China

Outdoor air pollution is a growing public health concern, particularly in urban settings. However, there are limited epidemiological data on outdoor air pollution in rural areas with substantial levels of air pollution attributed to solid fuel burning for household cooking and heating. Xuanwei and Fuyuan are rural counties in China where the domestic combustion of locally sourced bituminous (“smoky”) coal has been associated with the highest lung cancer rates in China. We previously assessed indoor and personal air pollution exposures in this area; however, the influence of indoor coal combustion and household ventilation on outdoor air pollution has not been assessed. Therefore, we measured outdoor fine particulate matter (PM2.5), species of polycyclic aromatic hydrocarbons (PAHs) including naphthalene (NAP) and the known carcinogen benzo(a)pyrene (BaP), sulfur dioxide (SO2), and nitrogen dioxide (NO2) over two consecutive 24-h sampling periods in 29 villages. Just over half of the villages were revisited two to nine months after the initial sampling period to repeat all measurements. The overall geometric mean (GM) of outdoor PM2.5, BaP, NAP, and NO2 were 45.3 µg/m3, 9.7 ng/m3, 707.7 ng/m3, and 91.5 µg/m3, respectively. Using linear mixed effects models, we found that burning smoky coal was associated with higher outdoor BaP concentrations [GM ratio (GMR) = 2.79] and lower outdoor SO2 detection rates (GMR = 0.43), compared to areas burning smokeless coal. Areas with predominantly ventilated stoves (> 50% of stoves) had higher outdoor BaP (GMR = 1.49) compared to areas with fewer ventilated stoves. These results show that outdoor air pollution in a rural region of China was associated with the type of coal used for cooking and heating indoors and the presence of stove ventilation. Our findings suggest that efforts of household stove improvement to reduce indoor air pollution have resulted in higher outdoor air pollution levels. Further reducing adverse health effects in rural villages from household coal combustion will require the use of cleaner fuel types.

KOH-activated porous biochar with high specific surface area for adsorptive removal of chromium (VI) and naphthalene from water: Affecting factors, mechanisms and reusability exploration

Herein, a high-performance porous biochar described as PBCKOH was successfully synthesized by two-step pyrolysis of corn straw with chemical activation of KOH, and was employed for the elimination of Cr(VI) and naphthalene (NAP) from water. Benefiting from KOH activation, the PBCKOH was found to possess huge specific surface area of 2183.80 m2/g and many well-developed micropores with average particle size of 2.75 nm and main pore diameters distribution from 1 to 2 nm. The PBCKOH presented an excellent adsorption performance with a theoretical monolayer uptake of 116.97 mg/g for Cr(VI) and a heterogeneous adsorption capacity of 450.43 mg/g for NAP. The uptake equilibrium was attained within about 120 min for Cr(VI), while about 180 min for NAP following avrami fractional-order model, revealing the existence of multiple kinetics during the adsorption. The thermodynamic results showed that the uptake of both Cr(VI) and NAP occurred spontaneously (-ΔG°), while in an endothermic nature for Cr(VI) (+ΔH°) and an exothermic characteristic for NAP (-ΔH°) with different randomness. Furthermore, the PBCKOH was believed to enhance the Cr(VI) adsorption mainly through the combination of electrostatic attraction, complexation, ion exchange and reduction action, while achieving the high NAP uptake by pore filling and π-π stacking interactions.

Biodegradation of Naphthalene, Anthracene and Ammonia-N in Sequential Fed Batch Reactor

Polycyclic aromatic hydrocarbons (PAH) belongto a group of hydrophobic organic compounds that contains two or more fused benzene rings in cluster arrangement. Due to its ubiquitous presence, carcinogenic and mutagenic properties, recalcitrant nature, PAH compounds have gathered great environmental concern. In this study, a mixed microbial culture is used to degrade 500 mg/L of naphthalene (NAP), 100 mg/L of anthracene (ANT) and 300 mg/L of ammonia-N (NH4-N) in anaerobic-anoxic-aerobic sequential bioreactor operated in fed batch condition. Anaerobic reactor removed maximum 71% of NAP, 36% of ANT, 49% of NH4-N and 79% of COD with total HRT of 16 days. Anoxic reactor was found capable for almost complete removal of all the pollutants from the effluent of anaerobic and aerobic reactor during recycling. Residualconcentration of all the pollutants were efficiently degraded in the aerobic reactor with overall removal efficiency of 92% NAP, 70% ANT, 80% NH4-N and 90% COD.

Bioavailability of polycyclic aromatic hydrocarbons to penguins on the coast of southeastern Brazil

Bioavailability of polycyclic aromatic hydrocarbons on São Paulo state coast (southeastern Brazil) was evaluated through the analysis of biliary metabolites in Spheniscus magellanicus (n = 79). The animals analyzed in present study were either found dead during beach monitoring procedures or died at rehabilitation centers. Analyses of naphthalene (NAP), phenanthrene (PHE) and benzo[a]pyrene (BaP) metabolites were performed using a high-performance liquid chromatograph equipped with fluorescence detectors. Total metabolite (TM) concentrations ranged from below the method quantification limit to 270 μg g−1 of bile. TM concentrations were mainly composed of NAP metabolites, followed by PHE metabolites. BaP metabolites were detected in only two samples. This is the first study using PAHs metabolites in S. magellanicus to assess the bioavailability of these compounds in coastal regions.

Antagonism or synergism? Responses of Hydrocharis dubia (Bl.) Backer to linear alkylbenzene sulfonate, naphthalene and their joint exposure.

The presence of surfactants may affect the bioavailability of polycyclic aromatic hydrocarbons. A hydroponic experiment was conducted to investigate the response of Hydrocharis dubia (Bl.) Backer to different concentrations of linear alkylbenzene sulfonate (LAS), naphthalene (NAP) and their mixture (0.5, 5, 10, and 20mg/L) for 14 days and 28 days. The results showed that LAS had a greater toxic effect on H. dubia growth than NAP at treatment concentrations of 0.5-20mg/L. The combined effect of LAS and NAP was damaging to H. dubia at concentrations of LAS+NAP ≥5+5mg/L. When LAS+NAP ≥10+10mg/L, the underground parts of H. dubia suffered more significant damage than the aboveground parts. Under the treatments with LAS, NAP and their mixture, H. dubia experienced oxidative stress. Soluble proteins and antioxidant enzymes were the main substances protecting H. dubia from LAS stress, and superoxide dismutase (SOD) and peroxidase (POD) were the main protective enzymes. When exposed to NAP, H. dubia growth was stimulated and promoted at the same time. In the short-term treatment (14d), catalase (CAT) activity was sensitive to NAP stimulation, and soluble proteins and SOD were the main protective substances produced. Soluble sugars, SOD and ascorbate peroxidase (APX) played important protective roles during the longer exposure time (28d). The physiological response of H. dubia exposed to the combined toxicants was weaker than the response to exposure to individual toxicants. The responses of SOD and CAT activity were positive in the short term (14d), and these were the main protective enzymes. As the exposure time increased (28d), the plant antioxidant system responded negatively.

Facile and novel ambient pressure drying approach to synthesis and physical characterization of cellulose-based aerogels

In this study, highly porous and ultralight cellulose aerogel (CA) was successfully synthesized via a novel and facile ambient pressure drying technique. In this drying method, naphthalene (NPH) as the porous-making agent occupied space between cellulose fibers and controlled structural collapse and severe shrinkage of samples successfully. By sublimation of NPH crystals at the end of procedure, ultimate CA was obtained. This technique can be considered as a fast, safe and cost-effective drying method. CA samples illustrated appropriate physical characteristics including: low densities (0.058 g cm−3), high porosity (> 96.5%), low thermal conductivity (0.0417 W m−1 K−1), appropriate mechanical strength and negligible shrinkage (< 10%) during the drying procedure. hydrophobic cellulose aerogel (HCA) and carbonized cellulose aerogel (CCA) were also obtained and the oil/water separation efficiency of these samples were investigated. Contact angle test reveled highly hydrophobicity with angle equal to 137° and 126° for HCA and CCA, respectively. Investigation of oils and organic solvents adsorption capacity illustrated that samples adsorbed oils and organic solvents in range from 1200 to 1800% of their weight. Regeneration ability of HCA and CCA was studied in five cycles. Depending on type of adsorbate, regeneration study showed various regeneration capacity from 30 to 98%.

Initiation of callus from different genotypes of Sorghum bicolor L. Moench

The study aimed to examine three genotypes of sorghum for their response in tissue culture using Murashige and Skoog (MS) medium supplemented with auxins (2,4-dichlorophenoxy acetic acid (2,4-D), naphthalene acetic acid (NAA)) and cytokinins (Kinetin, 6-benzyle amino purine (BAP)) at different concentrations. The cultures were initiated from different explants (seed, embryo and hypocotyl). The response of explants varied with the genotype. Callus culture were initiated successfully on MS medium supplemented with 2 mg/l 2,4-D and 0.5 mg/l Kinetin from G4 (L58) seedling and embryo explants. G2 (94) hypocotyl explants gave callus on media supplemented with 2,4-D only. G5 (2) explants failed to initiate callus but bulging from the embryo explants was observed on MS medium supplemented with 2 mg/l 2,4-D and 0.5 mg/l Kinetin. The initiated calluses differed morphologically and in their growth rates. Key words: Sorghum bicolor, callus formation, embryo, Kinetin, 2,4-dichlorophenoxy acetic acid (2,4-D).

Triple Isotopes (δ13C, δ2H, and Δ14C) Compositions and Source Apportionment of Atmospheric Naphthalene: A Key Surrogate of Intermediate-Volatility Organic Compounds (IVOCs).

Naphthalene (NAP), as a surrogate of intermediate-volatility organic compounds (IVOCs), has been proposed to be an important precursor of secondary organic aerosol (SOA). However, the relative contribution of its emission sources is still not explicit. This study firstly conducted the source apportionment of atmospheric NAP using a triple-isotope (δ13C, δ2H, and Δ14C) technique combined with a Bayesian model in the Beijing-Tianjin-Hebei (BTH) region of China. At the urban sites, stable carbon (-27.7 ± 0.7‰, δ13C) and radiocarbon (-944.0 ± 20.4‰, Δ14C) isotope compositions of NAP did not exhibit significant seasonal variation, but the deuterium system showed a relatively more 2H depleted signature in winter (-86.7 ± 8.9‰, δ2H) in comparison to that in summer (-56.4 ± 3.9‰, δ2H). Radiocarbon signatures indicated that 95.1 ± 1.8% of NAP was emitted from fossil sources in these cities. The Bayesian model results indicated that the emission source compositions in the BTH urban sites had a similar pattern. The contribution of liquid fossil combustion was highest (46.7 ± 2.6%), followed by coal high-temperature combustion (26.8 ± 7.1%), coal low-temperature combustion (18.9 ± 6.4%), and biomass burning (7.6 ± 3.1%). At the suburban site, the contribution of coal low-temperature combustion could reach 70.1 ± 6.4%. The triple-isotope based approach provides a top-down constraint on the sources of atmospheric NAP and could be further applied to other IVOCs in the ambient atmosphere.

Regulation of Airway Progenitor Homeostasis and Cell Composition by Tight Junction Protein Claudin‐18

RationaleClaudin‐18 (Cldn18) is comprised of two isoforms, Cldn 18.1 and Cldn18.2. The lung‐specific isoform, Cldn18.1, regulates distal lung epithelial progenitor cell homeostasis. Its role in airway epithelium has not been elucidated, although Cldn18 expression is decreased in lungs of patients with chronic airway diseases (e.g., asthma and chronic obstructive pulmonary disease (COPD)). The airway epithelium is comprised of three progenitor populations, basal cells (BC), pulmonary neuroendocrine cells (PNEC) and club cells, and two non‐progenitor cell populations, namely goblet and ciliated cells. Club cells are secretory cells that are susceptible to naphthalene (NAP) injury. Club cell depletion occurs by day 3 post‐NAP, with spreading of ciliated cells to cover the denuded epithelial surface, and full reconstitution of the airway epithelium by day 14–21. Here we investigated the role of Cldn18.1 in airway epithelium using a previously developed global Cldn18 knockout (KO) mouse model.MethodsWild‐type (WT) and Cldn18 KO mice were injected intraperitoneally with NAP (225–275 mg/kg, corn oil as control). Lungs were harvested at baseline and 3‐days (maximal injury), 7‐days (beginning of regeneration) and 21‐days (full regeneration) post‐NAP, inflated with 4% paraformaldehyde and fixed overnight prior to embedding and sectioning. Hematoxylin and eosin, Periodic Acid‐Schiff (PAS) and immunofluorescence staining were performed.ResultsIn WT mice, Cldn18.1 was expressed in a small subset of airway ciliated cells. Cldn18 KO mice showed increased numbers of pulmonary neuroendocrine cells and neuroendocrine bodies, as well as ectopic localization of club cells and localization of keratin 5‐positive cells within the distal parenchyma. At day 3 post‐NAP in WT mice, Cldn18.1 was transiently expressed in all the ciliated cells covering the denuded epithelium, returning to being expressed in only a subset of cells by day 7. Cldn18 KO mice subjected to injury unexpectedly developed marked goblet cell hyperplasia at day 14–21 post‐NAP, with cells expressing markers for both club (CC‐10) and goblet (MUC5AC) cells.ConclusionsOur findings demonstrate an unexpected role for Cldn18.1 in regulating airway progenitor homeostasis and cell composition, implicating Cldn18.1 in regulation of downstream signaling pathways that inhibit goblet cell differentiation. A transient increase in the number of Cldn18.1‐positive ciliated cells in WT mice in the initial stages post‐injury suggests paracrine regulation of these inhibitory effects. Modulation of Cldn18 expression may be beneficial in the treatment of airway diseases characterized by goblet cell metaplasia.Support or Funding InformationFunding: American Lung Association, Hastings Foundation, NIH

Application of multivariate data techniques in photochemical study of polycyclic aromatic hydrocarbons (PAHs) and transformed PAH products in road dust.

Road dust is a key repository for PAHs and transformed PAH products (TPPs) generated from natural and anthropogenic sources in the urban environment. Eventhough PAHs and TPPs are prone to post-emission photochemical processes, very limited studies exist on the subject for road dust. This knowledge gap is of particular concern since some of the resultant TPPs are notably more carcinogenic than their precursor PAHs. This study evaluated the role of 254nm ultraviolet (UV) photons on the photochemistry of PAHs and TPPs in road dust. The findings show that UV irradiation had varying effects on the fate of analytes, particularly naphthalene (NAP), phenanthrene (PHE), 7, 12-dimethylbenz(a)anthracene (DMBA), 1-hydroxypyrene (HPY), 1-nitropyrene (1NPY), pyrene (PYR) and 5-nitroacenaphthene (5NAC). Photochemical relationship was identified between PYR, 1NPY and HPY, and DMBA and benzo(a)anthracene. Unlike carbonyl-PAHs, parent PAHs, nitro-PAHs and hydroxy-PAHs can originate from photolysis. Photon irradiation durations of 3, 6 and 7.5h had the most intense influence on the photolytic process with 7.5h as optimum. The photochemical rate at optimum irradiation duration shows an increasing trend of NAP<PHE < 1NPY<DMBA < 5NAC<HPY with respective estimates of 0.08, 0.11, 0.21, 0.22, 0.43, and 0.59mgkg-1 hr-1. Physicochemical properties of analytes such as index of refraction and vapour pressure (in logarithmic form) had an inverse effect on photolysis. The knowledge generated is significant for the in-depth understanding of the fate of PAHs and TPPs on urban road surfaces and contributes to the greater protection of human health and the environment.