The aroma transformation of Japanese sea bass (Lateolabrax japonicas) through endogenous enzyme incubation during the lag phase of attached microorganisms.

Endogenous enzymes play a crucial role in determining fish product aroma. However, the attached microorganisms can promote enzyme production, making it challenging to identify specific aromatic compounds resulting from endogenous enzymes. Thus, we investigated the aroma transformation of Japanese sea bass through enzymatic incubation by controlling attached microorganisms during the lag phase. Our results demonstrate that enzymatic incubation significantly enhances grassy and sweet notes while reducing fishy odors. These changes in aroma are associated with increased levels of 10 volatile compounds and decreased levels of 3 volatile compounds. Among them, previous studies have reported enzyme reaction pathways for octanal, 1-nonanal, vanillin, indole, linalool, geraniol, citral, and 6-methyl-5-hepten-2-one; however, the enzymatic reaction pathways for germacrene D, beta-caryophyllene, pristane, 1-tetradecene and trans-beta-ocimene remain unclear. These findings provide novel insights for further study to elucidate the impact of endogenous enzymes on fish product aromas.

Impact of xylene exposure during organogenesis on foeto-placental efficiency and foetal viability: Exploring its association with oxidative stress-induced inflammation and apoptosis in utero.

The potential maternal and foetal toxicity resulting from exposure to xylene at or below the allowable limit of 100 ppm during gestation is not thoroughly studied. The aim of this study was to investigate maternal and foetal outcomes following prenatal exposure to xylene during organogenesis. Pregnant Sprague Dawley (SD) rats were administered intraperitoneal (IP) corn oil (vehicle), 100, 500, and 1000 parts per million (ppm) of xylene from gestational day (GD) 6 until GD17. Clinical signs, maternal weight gain, and food consumption were recorded daily. A caesarean hysterectomy was performed on GD21 to assess the reproductive and foetal outcomes. Exposure to 1000 ppm of xylene caused a significant decrease in the maternal body weight and food consumption, and an increase in intrauterine foetal deaths. Foetal assessment revealed a significant decrease in foetal weight in both male and female foetuses of female rats treated with 500 and 1000 ppm. Male placental weight was significantly decreased in all xylene-treated groups, while 1000 ppm xylene significantly decreased female placental weight. Histologically, marked uterine inflammatory lesions, fibrosis of the liver and renal tissues, as well as increased placental glycogen content were observed. Immunohistochemistry revealed a significant increase in lipid peroxidation and apoptotic markers. Thus, the foeto-maternal toxicities of xylene have been shown to be mediated by a systemic inflammatory response that exacerbates intrauterine oxidative stress and impairs foeto-placental transfer, leading to an increase in foetal mortality.

Enhancement of Gaseous o-Xylene Elimination by Chlorosulfonic Acid-Modified H-Zeolite Socony Mobil-5.

It is important to develop effective strategies for enhancing the removal capacity of aromatic volatile organic compounds (VOCs) by modifying conventional porous adsorbents. In this study, a novel HZSM-5 zeolite-supported sulfonic acid (ZSM-OSO3H) was prepared through ClSO3H modification in dichloromethane and employed for the elimination of gaseous o-xylene. The ClSO3H modification enables the bonding of -OSO3H groups onto the HZSM-5 support, achieving a loading of 8.25 mmol·g-1 and leading to a degradation in both crystallinity and textural structure. Within an active temperature range of 110-145 °C, ZSM-OSO3H can efficiently remove o-xylene through a novel reactive adsorption mechanism, exhibiting a removal rate exceeding 98% and reaching a maximum breakthrough adsorption capacity of 264.7 mg. The adsorbed o-xylene derivative is identified as 3,4-dimethylbenzenesulfonic acid. ZSM-OSO3H demonstrates superior adsorption performance for o-xylene along with excellent recyclability. These findings suggest that ClSO3H sulfonation offers a promising approach for modifying various types of zeolites to enhance both the elimination and resource conversion of aromatic VOCs.

Highly Efficient Separation of Intermediate-Size m-Xylene from Xylenes via a Length-Matched Metal-Organic Framework with Optimal Oxygen Sites Distribution.

Xylene separation is crucial but challenging, especially for the preferential separation of the intermediate-size m-xylene from xylene mixtures. Herein, exploiting the differences in molecular length and alkyl distribution among xylenes, we present a length-matched metal-organic framework, formulated as Al(OH)[O2C-C4H2O-CO2], featuring an effective pore size corresponding to m-xylene molecular length combined with multiple negative O hydrogen bond donors distribution, can serve as a molecular trap for efficient preferential separation of the intermediate-size m-xylene. Benchmark separation performance was achieved for separating m-xylene from a ternary mixture of m-xylene/o-xylene/p-xylene, with simultaneous record-high m-xylene uptake (1.3 mmol g-1) and m-xylene/p-xylene selectivity (5.3) in the liquid-phase competitive adsorption. Both vapor- and liquid-phase fixed-bed tests confirmed its practical separation capability with benchmark dynamic m-xylene/p-xylene and m-xylene/o-xylene selectivities, as well as excellent regenerability. The selective and strong m-xylene binding affinity among xylene molecules was further elucidated by simulations, validating the effectiveness of such a pore environment for the separation of intermediate-size molecules.

Xylene-Free Papanicolaou Staining.

INTRODUCTION: Xylene (XL) is the most commonly used clearing agent in Papanicolaou staining. XL is hazardous and toxic chemical and prolonged exposure to XL can cause many ill-health effects. The health risk due to XL can be minimized by substituting XL with less hazardous clearing reagents such as Pine Oil (PO), Eucalyptus oil (EO), or Limonene (LM). The objective of this study was to compare the clearing ability, staining quality, preservation of morphology, physical properties, and cost of XL, PO, EO, and LM. METHODS: Four smears were prepared from each of 50 serous effusions and were subjected to Papanicolaou stain. Out of four smears, one each was exposed to clearing specifically with XL (control), PO (test), EO (test), and LM (test). Test smears were compared with control for clearing, staining and morphology; graded as excellent, good or fair and further scored as 3, 2, 1, and the quality index (QI) was calculated. Statistical analysis was performed and the p value was calculated. In addition, the physical properties and cost of all the reagents were compared. RESULTS: QI was 0.96 for both XL and PO, whereas 0.92 and 0.54 for EO and LM, respectively. Compared to XL, the quality of staining, clearing and morphology of PO and EO were statistically not significant, whereas the difference was statistically significant with LM (p = 0.005). Physical properties such as volatility, flammability, miscibility with alcohol and DPX and the refractive indices of all the reagents were almost similar and all were recyclable. Odor was pungent for XL and EO but was pleasant for PO and LM. The cost was less for PO as compared to others. CONCLUSION: PO was a natural, less hazardous, less toxic, and economical clearing agent and can be considered as a substitute for XL.

Highly efficient Cu(II) coordination polymer catalyst for the conversion of hazardous volatile organic compounds.

Three novel coordination polymers (CPs), namely [Cu(µ-1κO,2κN-L)2]n (1), [Zn (µ-1κO,2κN-L)2(H2O)2]n (2) and [Cd (µ-1κOO',2κN-L)2]n (3) [where HL = 4-(pyrimidin-5-ylcarbamoyl)benzoic acid], were synthesized and characterized by elemental analysis, ATR-IR, TGA, XPS and single-crystal X-ray diffraction. Despite having the same organic ligand, the various metal cations had an impact in the subsequent frameworks. Hirshfeld surface analysis was performed to investigate the intermolecular interactions and to examine the stability of the crystal structures of the three polymers. Their catalytic performances were screened for the peroxidative oxidation of Volatile Organic Compounds (VOCs), with toluene and p-xylene selected as model substrates. Tert-butyl hydroperoxide (t-BuOOH or TBHP) (aq. 70 %) was employed as the oxidant. The catalytic oxidation of toluene yielded benzyl alcohol, benzaldehyde and benzoic acid. The copper CP 1 exhibited the highest total yield for toluene oxidation, reaching approximately 36% in an aqueous medium. For p-xylene oxidation, tolualdehyde, methylbenzyl alcohol, and toluic acid were produced as the primary products, accompanied by minor ones. The experiments were conducted under diverse conditions, manipulating key parameters such as the choice of solvent (water or acetonitrile), type of oxidant (t-BuOOH or H2O2), the concentration of the oxidant and reaction temperature. In the presence of catalyst 1, a maximum total yield of ca. 80% was achieved for p-xylene oxidation.

Discrimination of Xylene Isomers by Precisely Tuning the Interlayer Spacing of Reduced Graphene Oxide Membrane.

Separating xylene isomers is a challenging task due to their similar physical and chemical properties. In this study, we developed a molecular sieve incorporating a reduced graphene oxide (rGO) membrane for the precise differentiation of xylene isomers. We fabricated GO membranes using a vacuum filtration technique followed by thermal-induced reduction to produce rGO membranes with precisely controllable interlayer spacing. Notably, we could finely tune the interlayer spacing of the rGO membrane from 8.0 to 5.0 Å by simply varying the thermal reduction temperature. We investigated the reverse osmosis separation ability of the rGO membranes for xylene isomers and found that the rGO membrane with an interlayer spacing of 6.1 Å showed a high single component permeance of 0.17 and 0.04 L m-2 h-1 bar-1 for para- and ortho-xylene, respectively, exhibiting clear permselectivity. The separation factor reached 3.4 and 2.8 when 90:10 and 50:50 feed mixtures were used, respectively, with permeance 1 order of magnitude higher than that of current state-of-the-art reverse osmosis membranes. Additionally, the membrane showed negligible permeance and selectivity decay even after continuous operation for more than 5 days, suggesting commendable membrane resistance to solvent swelling and operating pressure.

Assessing VOC emissions from different gas stations: impacts, variations, and modeling fluctuations of air pollutants.

Gas stations distributed around densely populated areas are responsible for toxic pollutant emissions such as volatile organic compounds (VOCs). This study aims to measure VOCs emission from three different kinds of gas stations to determine the extent of pollution from the gas stations and the most frequent type of VOC compound emitted. The concentrations of ambient VOCs at three refueling stations with a different type of fuels in Mashhad were monitored. The result of this study showed that CNG fuel stations are less polluting than petrol stations. In all the studied sites, the highest concentrations were related to xylene isomers, irrespective of the fuel type. Total VOCs at the supply of both compressed natural gas (CNG) and gasoline stations was 482.36 ± 563.45 µg m-3. At a CNG station and a gasoline station, total VOC concentrations were 1363.4 ± 1975 µg m-3 and 410.29 ± 483.37 µg m-3, respectively. The differences in concentrations of toluene and m,p-xylene between the fuel stations can be related to the quality and type of fuel, vapor recovery technology, fuel reserves, dripless nozzles, traffic density in these stations, meteorological conditions and the location of sampling sites. The combination of a sine function and a quadratic function could model the fluctuation behavior of air pollutants like m,p-xylene. In all the sites, the highest concentrations were related to xylene isomers, irrespective of the type of fuel. The changing rate of m,p-xylene pollutant in each station was also modeled in this study.

Development of a Smartwatch with Gas and Environmental Sensors for Air Quality Monitoring.

In recent years, there has been a growing interest in developing portable and personal devices for measuring air quality and surrounding pollutants, partly due to the need for ventilation in the aftermath of COVID-19 situation. Moreover, the monitoring of hazardous chemical agents is a focus for ensuring compliance with safety standards and is an indispensable component in safeguarding human welfare. Air quality measurement is conducted by public institutions with high precision but costly equipment, which requires constant calibration and maintenance by highly qualified personnel for its proper operation. Such devices, used as reference stations, have a low spatial resolution since, due to their high cost, they are usually located in a few fixed places in the city or region to be studied. However, they also have a low temporal resolution, providing few samples per hour. To overcome these drawbacks and to provide people with personalized and up-to-date air quality information, a personal device (smartwatch) based on MEMS gas sensors has been developed. The methodology followed to validate the performance of the prototype was as follows: firstly, the detection capability was tested by measuring carbon dioxide and methane at different concentrations, resulting in low detection limits; secondly, several experiments were performed to test the discrimination capability against gases such as toluene, xylene, and ethylbenzene. principal component analysis of the data showed good separation and discrimination between the gases measured.

The impact of ozone treatment on the removal effectiveness of various refractory compounds in wastewater from petroleum refineries.

Large volumes of wastewater are generated during petroleum refining processes. Petroleum refinery wastewater (PRW) can contain highly toxic compounds that can harm the environment. These toxic compounds can be a challenge in biological treatment technologies due to the effects of these compounds on microorganisms. These challenges can be overcome by using ozone (O3) as a standalone or as a pretreatment to the biological treatment. Ozone was used in this study to degrade the organic pollutants in the heavily contaminated PRW from a refinery in Mpumalanga province of South Africa. The objective was achieved by treating the raw PRW using ozone at different ozone treatment times (15, 30, 45, and 60 min) at a fixed ozone concentration of 3.53 mg/dm3. The ozone treatment was carried out in a 2-liter custom-designed plexiglass cylindrical reactor. Ozone was generated from an Eco-Lab-24 corona discharge ozone generator using clean, dry air from the Afrox air cylinder as feed. The chemical oxygen demand, gas chromatograph characterization, and pH analysis were performed on the pretreated and post-treated PRW samples to ascertain the impact of the ozone treatment. The ozone treatment was effective in reducing the benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds in the PRW. The 60-min ozone treatment of different BTEX pollutants in the PRW resulted in the following percentage reduction: benzene 95%, toluene 77%, m + p-xylene 70%, ethylbenzene 69%, and o-xylene 65%. This study has shown the success of using ozone in reducing the toxic BTEX compounds in a heavily contaminated PRW.

Surveillance of Occupational Exposure to Volatile Organic Compounds at Gas Stations: A Scoping Review Protocol.

Health surveillance guides public policies, allows for the monitoring of occupational exposures that may cause health risks, and can prevent work-related diseases. The scoping review protocol herein is designed to map studies on the surveillance of occupational exposure to volatile organic compounds (VOCs) in gas stations and identify the governmental agencies and public health measures in different countries. This review protocol is based on the Joanna Briggs Institute manual and guided by the PRISMA Extension for Scoping Reviews. It includes research articles, theses, dissertations, and official documents on surveillance measures for occupational exposure to VOCs (i.e., benzene, ethylbenzene, toluene, and xylene) in gas stations from different countries. All languages and publication dates will be considered, and a spreadsheet will be used to extract and analyze qualitative and quantitative data. The final version will present the main surveillance measures implemented, responsible entities, results, challenges, limitations, and potential gaps in gas stations.

Spatial distribution of volatile organic compounds in contaminated soil and distinct microbial effect driven by aerobic and anaerobic conditions.

The vertical distribution of 35 volatile organic compounds (VOCs) was investigated in soil columns from two obsolete industrial sites in Eastern China. The total concentrations of ΣVOCs in surface soils (0-20 cm) were 134-1664 ng g-1. Contamination of VOCs in surface soil exhibited remarkable variability, closely related to previous production activities at the sampling sites. Additionally, the concentrations of ΣVOCs varied with increasing soil depth from 0 to 10 m. Soils at depth of 2 m showed ΣVOCs concentrations of 127-47,389 ng g-1. Among the studied VOCs, xylene was the predominant contaminant in subsoils (2 m), with concentrations ranging from n.d. to 45,400 ng g-1. Chlorinated alkanes and olefins demonstrated a greater downward migration ability compared to monoaromatic hydrocarbons, likely due to their lower hydrophobicity. As a result, this vertical distribution of VOCs led to a high ecological risk in both the surface and deep soil. Notably, the risk quotient (RQ) of xylene in subsoil (2 m, RQ up to 319) was much higher than that in surface soil. Furthermore, distinct effects of VOCs on soil microbes were observed under aerobic and anaerobic conditions. Specifically, after the 30-d incubation of xylene-contaminated soil, Ilumatobacter was enriched under aerobic condition, whereas Anaerolineaceae was enriched under anaerobic condition. Moreover, xylene contamination significantly affected methylotrophy and methanol oxidation functions for aerobic soil (t-test, p < 0.05). However, aromatic compound degradation and ammonification were significantly enhanced by xylene in anaerobic soil (t-test, p < 0.05). These findings suggest that specific VOC compound has distinct microbial ecological effects under different oxygen content conditions in soil. Therefore, when conducting soil risk assessments of VOCs, it is crucial to consider their ecological effects at different soil depths.

Coniferyl ferulate alleviate xylene-caused hematopoietic stem and progenitor cell toxicity by Mgst2.

Xylene exposure is known to induce toxicity in hematopoietic stem and progenitor cells (HSPCs), leading to bone marrow suppression and potential leukemogenesis. However, research on the gene expression profiles associated with xylene-induced toxicity in HSPCs, and effective therapeutic interventions, remains scarce. In our study, we employed single-cell RNA sequencing to capture the transcriptomic shifts within bone marrow HSPCs both prior to and following treatment with coniferyl ferulate (CF) in a mouse model of xylene-induced hematotoxicity. Subsequently, we pinpointed CF as a targeted agent using SPR-LC/MS analysis. This enabled us to confirm the link between the gene Mgst2 and specific cellular subtypes. Our data revealed that CF significantly countered the reduction of both monocyte and neutrophil progenitor cells, which are commonly affected by xylene toxicity. Through targeted analysis, we identified Mgst2 as a direct molecular target of CF. Notably, Mgst2 is preferentially expressed in neutrophil progenitor cells and is implicated in mitochondrial metabolic processes. By selectively inhibiting Mgst2 in bone marrow, we observed amelioration of xylene-induced hematotoxic effects. In summary, our findings suggest that coniferyl ferulate can mitigate the detrimental impact of xylene on hematopoietic stem and progenitor cells by targeting Mgst2, particularly within subpopulations of neutrophil progenitors. This discovery not only advances our comprehension of the cellular response of HSPCs to xenobiotic stressors like xylene but also identifies CF and Mgst2 as potential therapeutic targets for alleviating xylene-induced hematotoxicity.

Climatic conditions and concentrations of BTEX compounds in atmospheric media.

Climatic and meteorological conditions are among the factors affecting the ambient concentrations of BTEX compounds. This systematic review and meta-analysis aimed to interrogate the seasonal effect of climatic conditions on the concentrations of BTEX compounds. Three electronic bibliographic databases including Scopus, PubMed, and Web of Science were systematically searched up to November 14, 2023. The search algorithm followed PRISMA guidance and consisted of three groupings of keywords and their possible combinations. For various climatic conditions, the overall mean and 95% confidence interval (CI) of effect size related to BTEX concentrations were calculated using a random-effect model. In total, 104 articles were included for evaluation in this review. BTEX ambient concentration was higher in winter (ranging from 36 out of 79 relevant studies for xylene to 52 out of 97 relevant studies for benzene) followed by summer and autumn. For humidity conditions, the highest exposure values for BTEX were detected for rainy weather (ranging from 3 out of 5 relevant studies for toluene and xylene to 4 out of 5 relevant studies for benzene and ethyl benzene) compared to dry conditions. The pooled concentration (µg/m3) of benzene, toluene, ethyl benzene, and xylene were computed as 2.61, 7.12, 2.21, and 3.61 in spring, 2.13, 7.53, 1.61, and 2.75 in summer, 3.04, 9.59, 3.14, and 5.50 in autumn, and 3.56, 8.71, 2.35, and 3.91 in winter, respectively. Moreover, the pooled concentrations (µg/m3) of BTEX were measured as 2.98, 7.22, 1.90, and 3.03 in dry weather and 3.15, 6.30, 2.14, and 3.86 in rainy or wet weather, respectively. In most seasons, the ambient concentrations of BTEX were higher in countries with low and middle incomes and in Middle Eastern countries and East/Southeast Asia compared to those in other regions (P < 0.001). The increasing concentrations of BTEX in winter and autumn followed by the summer season and during rainy/wet weather appear to be reasonably consistent despite variations in study methods, quality, or geography. Therefore, it is recommended that more serious control measures are considered for decreasing exposure to BTEX in these climatic conditions.

Clearing Properties Between Coconut Oil and Xylene in Histological Tissue Processing.

Xylene is the commonest clearing agent even though it is hazardous and costly. This study evaluated the clearing properties of coconut oil as an alternative cost-effective clearing agent for histological processes. Ten (10) prostate samples fixed in formalin were taken and each one was cut into 4 before randomly separating them into four groups (A, B, C and D). Tissues were subjected to ascending grades of alcohol for dehydration. Group A was cleared in xylene and Groups B, C, and D were cleared at varying times of 1hr 30mins, 3hrs, and 4hrs in coconut oil respectively before embedding, sectioning, and staining were carried out. Gross and histological features were compared. Results indicated a significant shrinkage in coconut oil-treated specimen compared with the xylene-treated specimen and only the tissues cleared in coconut oil for 4hrs were as rigid as the tissues cleared in xylene (p > 0.05). No significant difference was found in either of the sections when checked for cellular details and staining quality (p > 0.999). Coconut oil is an efficient substitute for xylene in prostate tissues with a minimum clearing time of 4hrs, as it is environmentally friendly and less expensive, but causes significant shrinkage to prostate tissue.

Occupational exposure to organic solvents and risk of bladder cancer.

BACKGROUND: Bladder cancer has been linked to several occupations that involve the use of solvents, including those used in the dry-cleaning industry. OBJECTIVES: We evaluated exposure to solvents and risk of bladder cancer in 1182 incident cases and 1408 controls from a population-based study. METHODS: Exposure to solvents was quantitatively assessed using a job-exposure matrix (CANJEM). Exposure to benzene, toluene and xylene often co-occur. Therefore, we created two additional sets of metrics for combined benzene, toluene and xylene (BTX) exposure: (1) CANJEM-based BTX metrics and (2) hybrid BTX metrics, using an approach that integrates the CANJEM-based BTX metrics together with lifetime occupational histories and exposure-oriented modules that captured within-job, respondent-specific details about tasks and chemicals. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using logistic regression. RESULTS: Bladder cancer risks were increased among those ever exposed to benzene (OR = 1.63, 95% CI: 1.14-2.32), toluene (OR = 1.60, 95% CI: 1.06-2.43), and xylene (OR = 1.67, 95% CI: 1.13-2.48) individually. We further observed a statistically significant exposure-response relationship for cumulative BTX exposure, with a stronger association using the hybrid BTX metrics (ORQ1vsUnexposed = 1.26, 95% CI: 0.83-1.90; ORQ2vsUnexposed = 1.52, 95% CI: 1.00-2.31; ORQ3vsUnexposed = 1.88, 95% CI: 1.24-2.85; and ORQ4vsUnexposed = 2.23, 95% CI: 1.35-3.69) (p-trend=0.001) than using CANJEM-based metrics (p-trend=0.02). IMPACT: There is limited evidence about the role of exposure to specific organic solvents, alone or in combination on the risk of developing bladder cancer. In this study, workers with increasing exposure to benzene, toluene, and xylene as a group (BTX) had a statistically significant exposure-response relationship with bladder cancer. Future evaluation of the carcinogenicity of BTX and other organic solvents, particularly concurrent exposure, on bladder cancer development is needed.

Ester-functionalized pillar[6]arene as the gas chromatographic stationary phase with high-resolution performance towards the challenging isomers of xylenes, diethylbenzenes, and ethyltoluenes.

This work presents the first example of the utilization of polar ester group functionalized pillar[6]arene (P6A-C10-OAc) as a stationary phase for capillary gas chromatographic (GC) separations. The statically coated P6A-C10-OAc column showed a high column efficiency of 5393 plates/m and moderate polar nature. Its resolving capability and retention behaviors were investigated for a mixture of 20 analytes and more than a dozen isomers from apolar to polar in nature. As evidenced, the P6A-C10-OAc column achieved high-resolution separations of all the analytes and good inertness. Importantly, it exhibited distinctly advantageous performance for high resolution of the challenging isomers of xylenes, diethylbenzenes, ethyltoluenes, and halobenzenes over the commercial HP-5 (5% phenyl dimethyl polysiloxane), HP-35 (25% phenyl dimethyl polysiloxane), and PEG-20M (polyethylene glycol) columns.

Health risk assessment of exposure to benzene, toluene, ethyl benzene, and xylene in shoe industry-related workplaces.

Benzene, toluene, ethyl benzene, and xylene (BTEX) are prevalent pollutants in shoe industry-related workplaces. The aim of this study was to assess exposure to BTEX and their carcinogenic and non-carcinogenic risks in shoe-industry-related workplaces. This study was carried out at different shoe manufactures, small shoe workshop units, shoe markets, and shoe stores in Tabriz, Iran in 2021. Personal inhalation exposure to BTEX was measured using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. Carcinogenic and non-carcinogenic risks due to inhalation exposure to BTEX were estimated by United States Environmental Protection Agency (U.S. EPA) method based on Mont Carlo simulation. Results showed that the concentrations of benzene and toluene were higher than the threshold limit value (TLV) in both gluing and non-gluing units of shoe manufactures. The total carcinogenic risk (TCR) due to exposure to benzene and ethyl benzene was considerable in all shoe industry-related workplaces. Also, the hazard index (HI) as a non-carcinogenic index was higher than standard levels in all shoe industry-related workplaces. Therefore, shoe industry-related workers are at cancer and non-cancer risks due to exposure to BTEX. Prevention measures need to be implemented to reduce the concentration of BTEX in shoe industry-related workplaces.

One Collision-Two Substituents: Gas-Phase Preparation of Xylenes under Single-Collision Conditions.

The fundamental reaction pathways to the simplest dialkylsubstituted aromatics-xylenes (C6 H4 (CH3 )2 )-in high-temperature combustion flames and in low-temperature extraterrestrial environments are still unknown, but critical to understand the chemistry and molecular mass growth processes in these extreme environments. Exploiting crossed molecular beam experiments augmented by state-of-the-art electronic structure and statistical calculations, this study uncovers a previously elusive, facile gas-phase synthesis of xylenes through an isomer-selective reaction of 1-propynyl (methylethynyl, CH3 CC) with 2-methyl-1,3-butadiene (isoprene, C5 H8 ). The reaction dynamics are driven by a barrierless addition of the radical to the diene moiety of 2-methyl-1,3-butadiene followed by extensive isomerization (hydrogen shifts, cyclization) prior to unimolecular decomposition accompanied by aromatization via atomic hydrogen loss. This overall exoergic reaction affords a preparation of xylenes not only in high-temperature environments such as in combustion flames and around circumstellar envelopes of carbon-rich Asymptotic Giant Branch (AGB) stars, but also in low-temperature cold molecular clouds (10 K) and in hydrocarbon-rich atmospheres of planets and their moons such as Triton and Titan. Our study established a hitherto unknown gas-phase route to xylenes and potentially more complex, disubstituted benzenes via a single collision event highlighting the significance of an alkyl-substituted ethynyl-mediated preparation of aromatic molecules in our Universe.

Confinement of p-Xylene in the Pores of a Bilanthanide Metal-Organic Framework for Highly Selective Recognition.

The rapid and accurate sensing of p-xylene, an essential raw material with a multi-billion-dollar market, in xylene mixture is of great significance in industry; however, the highly similar molecular structures, energy levels, and spectral characteristics of xylene isomers make the selective recognition extremely challenging. Metal-organic frameworks (MOFs) exhibiting tailorable pores and potential binding sites provide prospects for xylene sensing but a comprehensive understanding of the pore effect is still elusive, primarily due to the intricacies involved in the sensing process. Herein, we reported a robust bilanthanide MOF NKU-999-EuTb with precisely engineered pores to accommodate p-xylene, of which the binding sites were confirmed by single crystal X-ray diffraction and dynamic magnetic susceptibilities. NKU-999-EuTb exhibits high-performance in selective recognition for p-xylene towards its isomers. Through a systematical study, it was revealed that absorbing p-xylene into the pores governs the sensing performance. This work provides insights for developing advanced sensing materials for complex isomers.