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Occupational exposure to solvents, including n-hexane, has been associated with acquired color vision defects. Blue-yellow defects are most common and may be due to neurotoxicity or retinal damage. Acetone may potentiate the neurotoxicity of n-hexane. We present results on nonhexane solvent and hexane exposure and color vision from a cross-sectional study of 835 automotive repair workers in the San Francisco Bay Area, California (2007-2013). Cumulative exposure was estimated from self-reported work history, and color vision was assessed using the Lanthony desaturated D-15 panel test. Log-binomial regression was used to estimate prevalence ratios for color vision defects. Acquired color vision defects were present in 29% of participants, of which 70% were blue-yellow. Elevated prevalence ratios were found for nonhexane solvent exposure, with a maximum of 1.31 (95% confidence interval (CI): 0.86, 2.00) for blue-yellow. Among participants aged ≤50 years, the prevalence ratio for blue-yellow defects was 2.17 (95% CI: 1.03, 4.56) in the highest quartile of nonhexane solvent exposure and 1.62 (95% CI: 0.97, 2.72) in the highest category of exposure to hexane with acetone coexposure. Cumulative exposures to hexane and nonhexane solvents in the highest exposure categories were associated with elevated prevalence ratios for color vision defects in younger participants.

One of the main challenges that hinder the achievement of the third-millennium sustainable development goal is the emergence of infectious agents that are resistant to existing antimicrobials. These challenges entail a search for novel bioactive compounds like exploring the untapped potential of medicinal plants and their associated endophytes. The present study aimed to investigate the antimicrobial activities of crude extracts of endophytic fungi isolated from two medicinal plants: Kigelia africana and Phyllanthus niruri. Isolates of endophytic fungi were subjected to initial screening for antimicrobial activity and the isolates that exhibited antimicrobial activity based on the zone of inhibition were genotyped by Sanger sequencing for identification. Then, antimicrobial activities of crude extracts of Nigrospora sphaerica, Meyerozyma guilliermondii, Alternaria alternata, and Phyllosticta capitalensis were evaluated by the disc diffusion method against Escherichia coli (Gram-negative), Salmonella typhi (Gram-negative), and Staphylococcus aureus (Gram-positive). There was high variability (8.5 -23.1 mm) of the zone of inhibition among isolates. The highest zone of inhibition was that of M. guilliermondii ethyl acetate crude extract against S. aureus. Furthermore, the lowest range (9.9 >MIC>5.0) of minimum inhibition concentration (MIC,) in mg/ml was found in n-hexane crude extract of P. capitalensis against S. typhi. However, E. coli was resistant to all crude extracts. Results of the present study corroborated the influence of extracting solvent on the effectiveness of crude extract of isolates against pathogen microorganisms. Also, findings demonstrated the potential of endophytes from medicinal plants for medical applications, and therefore further investigation may lead to the discovery of novel bioactive compounds potent to resistant infectious agents. [ABSTRACT FROM AUTHOR]

INTRODUCTION: The Spacecraft Maximum Allowable Concentrations (SMACs) for C2-C9 alkanes set by NASA in 2008 under the guidance and approval of the National Research Council specifically excluded SMACs for n-hexane. Unlike other C2-C9 alkanes, n-hexane can cause polyneuropathy after metabolism in humans or rodents and so requires more stringent SMACs than the other members of this group do. This document reviews the relevant published studies of n-hexane toxicity to develop exposure duration-specific SMACs for n-hexane of 200 ppm for 1 hour, 30 ppm for 24 hours, and 2.4 ppm for 7 days, 30 days, 180 days, and 1000 days. [ABSTRACT FROM AUTHOR]

The crude n-hexane extracts Epaltes pygmaea (NH-Epx) displayed a steady larval toxicity against Culex quinquefasciatus and Aedes aegypti at the maximum dosage of 125 ppm. The level of α- and β carboxylesterase activity was downregulated to the sub-lethal dosage of NH-EPx (75 ppm) in both vectors. The level of GST and CYP450 gets upregulated. The LC50 and the LC90 of NH-EPx were observed at 63 and 117 ppm and 73 and 120 ppm dosage against both the vectors, respectively. NH-EPx treatment showed morphological alterations in the gut tissues. The non-target screening recommends that NH-EPx is safe against aquatic predator. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To evaluate the saponins rich fraction of Dioscorea deltoidea (D. deltoidea) for possible antinociceptive activity. METHODS: Saponins were extracted from the crude methanolic extract of D. deltoidea (Wall). Presence of saponins was confirmed through phytochemical screenings. Acute toxicity test was performed to determine safe dose range of the saponins rich fraction (n-butanol fraction) using balb C Mice. The saponins rich fraction was assessed for possible antinociceptive activity using acetic acid induced writhing method and hot plate method. Data was analyzed using Graph Pad Prism 6. ANOVA was used to determine the significance of test samples versus positive control at 95% CI with p

The excessive use of chemical pesticides has led to pest resistance and the accumulation of residues. Pest resistance occurs when pests become immune to pesticides and require higher doses or stronger pesticides for control. This study aims to identify the optimal solvent for dissolving secondary metabolite compounds that selectively and safely kill or inhibit the growth of plant pests. The biopesticide used is derived from melinjo bark extract through the process of soxhlet extraction using methanol and N-hexane solvents. The study employed a two-factor factorial design with three variables. The findings revealed that methanol solvent was more effective in dissolving phenolic compounds, resulting in a phenol content of 34.23 mg/equivalent Gallic Acid. The optimal solvent ratio was achieved at a ratio of 600 ml. The highest yield, reaching 56.27%, was obtained when using methanol as the solvent. Moreover, the pest mortality rate was found to be 100% at the specified concentration.

Canola oil cannot be directly used as a fuel in diesel engines because its physicochemical properties differ considerably from those of diesel oil. Therefore, the studies were intended to make closer the surface tension, viscosity and density of the canola oil to those of diesel fuel by adding n-hexane and ethanol. The surface tension and its components as well as density and viscosity were determined not only for the canola oil mixtures with n-hexane and ethanol but also for the canola oil components. The surface tension components were determined based on the contact angle measurements on PTFE. To obtain the components and parameters of saturated fatty acids, the contact angles of water, diiodomethane and formamide on their layers were measured. The contact angles of the studied mixtures were also measured on the engine valve. The obtained results and theoretical considerations allowed us to explain why the values of the surface tension, density and viscosity of canola oil are higher than those for its components. They also contributed to the explanation of the mechanism of the reduction in these quantities for canola oil by the addition of n-hexane and ethanol. It appeared, for example, that viscosity of the canola oil mixture with 20% n-hexane contacted with ethanol is close to that of diesel fuel.

In this study, the effects of crystallization temperature, crystallization time, and pH value on the textural properties of synthetic ZSM-5 were investigated by the orthogonal test method. Furthermore, the effects of ZSM-5 catalysts synthesized under different preparation conditions on their reactivity during catalytic cracking were evaluated. Moreover, the results have shown that the three factors that affect the ZSM-5 synthesis are in the following order: crystallization temperature > crystallization time > pH value. In addition, the optimal conditions for synthesizing ZSM-5 catalysts were crystallization temperature of 170 °C, crystallization time of 48 h, and pH of 11. Furthermore, under these conditions, the specific surface area, pore-volume, and acidity of the synthetic zeolite were moderate, and the hydrothermal stability was ideal. Finally, when the optimal conditions were applied to the catalytic cleavage of n-hexane, the synthesized zeolite exhibited good activity and stability.

Ultrasonic soil washing processes using organic solvents were investigated for the development of novel remediation technologies for persistent organic pollutants (POPs)- contaminated soils. Aluminum foil erosion was first tested to understand sonophysical activity in water, methanol (polar) and n-hexane (nonpolar) in a 28 kHz double-bath-type sonoreactor. Significant sonophysical damage on the aluminum foil was observed at the antinodes for all solvents, and the order of degree of sonophysical damage was as follows: water > methanol > n-hexane. Subsequently, conventional (mechanical mixing only) and ultrasonic soil washing (mechanical mixing and ultrasound) techniques were compared for the removal of polychlorinated biphenyls (PCBs) from soil. Two types of contaminated soils, fresh (Soil A, C0 = 2.5 mg/kg) and weathered (Soil B, C0 = 0.5 mg/kg), were used and the applied soil-to-liquid (S:L) ratio was 1:5 and 1:10 for methanol and n-hexane, respectively. The polar solvent significantly increased washing efficiencies compared to the nonpolar solvent, despite the nonpolar nature of the PCBs. Washing efficiency was significantly enhanced in ultrasonic soil washing compared to conventional washing, owing to macro- and micro-scale sonophysical actions. The highest washing efficiencies of 90% for Soil A and 70% for Soil B were observed in the ultrasonic washing processes using methanol. Additionally, a single operation of the ultrasonic washing process was superior to two sequential processes with conventional mixing in terms of washing efficiency, consumption of washing agents, treatment of washing leachate, and operation time. Finally, the removal of PCBs in an organic solvent (methanol) was investigated in photolytic and sonolytic processes for the post-treatment of soil washing leachate. A photolysis efficiency of 80% was obtained within 60 min of UV exposure for intensities of 1.0, 2.0, and 4.0 W/cm2. The primary mechanism of PCBs degradation is photolytic dechlorination. In contrast, no degradation was detected in the sonolytic process, as the excess organic solvent acted as a strong radical scavenger.

Background: Chronic n-Hexane poisoning is prevalent among workers in small and micro printing industries in China. Despite this, there is limited research on occupational health risk assessment in these sectors. Conducting comprehensive risk assessments at key positions and proposing effective countermeasures are essential., Methods: Data were collected from 84 key positions across 32 small and micro-sized printing enterprises. Air samples were tested for n-Hexane exposure levels in accordance with Chinese standards. Five risk assessment models were employed: COSHH, EPA, MOM, ICMM, and Technical Guide GBZ/T 289-2017 of China. The consistency of results across these models was analyzed., Results: Workers in 84 job positions were categorized into four exposure groups, with exposure to n-Hexane for 8-10 h daily, 5-6 days weekly. Most positions operated with low automation levels (96.9% in printing, 5.9% in oil blending, and 42.9% in pasting), while others were manual. Localized ventilation rates were notably low in oil blending (23.5%), cleaning (14.3%), and pasting (9.5%) groups. n-Hexane concentrations exceeded Chinese occupational limits in 15.6% of printing, 17.7% of oil blending, and 21.4% of cleaning groups. Risk assessment models identified over 60% of work groups as high risk. Significant differences ( p  < 0.05) were found among the seven risk assessment methods. Consistency analysis revealed moderate agreement between the Chinese synthesis index and exposure index methods ( k  = 0.571, p  < 0.01)., Conclusion: The Chinese synthesis and exposure index methods from Technical Guide GBZ/T 289-2017 are practical and reliable for assessing n-Hexane exposure risks in small and micro printing enterprises. Cleaning and printing roles were found to be at the highest risk for n-Hexane exposure. These findings provide valuable insights for targeted risk management strategies to protect workers' health in the industry., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Hu, Chen, Zhong, Chen, Cai and Cai.)

Objective: To explore the potential evidence of active peripheral nerve necrosis when n-hexane produces toxic effects on peripheral nerves. Methods: In May 2023, 36 SPF grade SD male rats with a body weight of 200-220 g were divided into 4 groups with 9 rats in each group and given normal saline and different doses of n-hexane (168, 675, 2 700 mg/kg) by gavage for 6 consecutive weeks (5 days/week). Three rats in each group were killed at the 2nd, 4th and 6th week, respectively. The spinal cord to sciatic nerve tissue was broken and the supernatant was extracted for SDS-PAGE protein isolation. The expression level of Sarm1 protein was analyzed with the β-Actin color strip of internal reference protein by Western blot. The expression of Sarm1 protein was analyzed by the gray ratio of the two. At the 6th week, the sciatic nerve sections of the each group were observed by light microscope and electron microscope. Results: The number of axons was obviously reduced by light microscopy. According to electron microscope, myelin lesions were mainly local disintegration, deformation, and different thickness. The deformation of axonal surface became smaller. The axons in the nerve bundle membrane showed degeneration and reduction. The gray ratio of Sarm1 protein and internal reference protein bands in each group had no significant change at the second week of exposure, and the ratio of SARM1 protein to internal reference protein bands was 1.47 in the high dose group at the fourth week, and 1.51 and 1.89 in the middle and high dose group at the sixth week, respectively. Conclusion: Waller's degeneration was observed in sciatic neuropathologic manifestations of n-hexane-poisoned rats, and the expression level of Sarm1 protein increased.

The efficiency of polyethylene glycol methyl ether 350 (PEG ME-350) in the process of extracting thiophene from model motor fuel has been studied experimentally. The influence of the contact time of the phases, the composition of the extractant, the initial concentration of thiophene, and the volume ratio of the extractant and model fuel on the extraction of thiophene has been investigated. It is found that PEG ME-350 exhibits effective extraction properties with respect to thiophene, extracting it up to 81.58% in one extraction stage. The results can be further used in the development of the extraction purification of liquid motor fuels from sulfur-containing compounds. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality 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.)

The vapor–liquid phase equilibrium (VLE) data for binary systems of: n-hexane + methylcyclopentane, n-hexane + N-methylpyrrolidone (NMP), methylcyclopentane + NMP and ternary system of n-hexane + methylcyclopentane + NMP were determined with a modified Rose still at atmospheric pressure (101.3 kPa), and all the binary data passed the Wisniak area test and Van Ness point test, which accorded with the thermodynamic consistency. Three thermodynamic models Wilson, NRTL and UNIQUAC were used to correlate binary data and get binary interaction parameters, then the built-in parameters of the Aspen Plus software were replaced by the obtained model parameters to estimate the ternary data of n-hexane + methylcyclopentane + NMP. The estimation values of the three models are in good agreement with the experimental data. Moreover, the effect of NMP was analyzed, and it found to be an effective candidate extractant for the extractive distillation of n-hexane + methylcyclopentane. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Chemical & Petroleum Engineering is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office 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.)

Using a combination of molecular dynamics simulations and first‐principles calculations, the interaction of n‐alkanes with {101¯4} calcite/dolomite is investigated. It is observed that the n‐alkane molecules align preferentially parallel to the interface, despite interaction by weak physisorption, and give rise to distinct adsorption layers. The ordering turns out to be more pronounced on calcite than dolomite due to a smaller average velocity of the n‐alkane molecules. The observations are explained in terms of adsorption energies and charge transfers. The results show that functionalization is no prerequisite of structural ordering and a distinct mass density profile perpendicular to the interface. [ABSTRACT FROM AUTHOR]

Spent methanol-to-propylene (MTP) catalysts have a large specific surface area and high porosity but are usually directly disposed of in landfills, and recycling is rare. In this study, spent MTP catalyst was moderately dealuminized with acids and etched with an alkali solvent to increase its specific surface area. A novel adsorbent was obtained. XRD, SEM, FT-IR, XRD, XRF, and MAS-NMR characterization shows that the adsorbent maintains a typical ZSM-5 zeolite structure, and the dealumination effect of H2C2O4 is better than that of HCl. HCl mainly removes the framework aluminum of the molecular sieve; H2C2O4 not only removes the framework aluminum but also dissolves some of the nonframework aluminum, which increases the BET-specific surface area and pore diameter. The spent catalyst maintains an irregular ellipsoidal shape. After alkali treatment, the surface of the spherical particles becomes rough. With increasing alkali concentration, the damage degree increases. After treatment with 4 mol/L H2C2O4 and 0.1 mol/L NaOH, the p-xylene and n-hexane adsorption capacities reach the maximum, with values of 141.04 mg/g and 106.87 mg/g, respectively, 20.7% and 16.2% greater than those before treatment. These findings indicate that modified spent MTP catalyst has the potential for application in the removal of VOCs from the air.

Phosphorus-doped activated carbon (P@AC), prepared by wet impregnation method, can serve as efficient metal-free catalyst for the dehydroaromatization of n-hexane to benzene under mild conditions. The effect of phosphorus amount and phosphorus sources including phenylphosphonic acid (PPOA), phosphorus acid (H3PO4), triphenylphosphine (TPP), and tributylphosphine (TBP) on catalytic performance of P@AC were investigated. Combining with characterization analysis, functional groups containing -P(O)(OH) on the carbon surface are believed to be the active sites for dehydroaromatization catalysis.

New ignition delay time measurements of natural gas mixtures enriched with small amounts of n-hexane and n-heptane were performed in a rapid compression machine to interpret the sensitization effect of heavier hydrocarbons on auto-ignition at gas-turbine relevant conditions. The experimental data of natural gas mixtures containing alkanes from methane to n-heptane were carried out over a wide range of temperatures (840-1050 K), pressures (20-30 bar), and equivalence ratios (φ = 0.5 and 1.5). The experiments were complimented with numerical simulations using a detailed kinetic model developed to investigate the effect of n-hexane and n-heptane additions. Model predictions show that the addition of even small amounts (1-2%) of n-hexane and n-heptane can lead to an increase in reactivity by ~40-60 ms at compressed temperature (TC) = 700 K. The ignition delay time (IDT) of these mixtures decreases rapidly with an increase in concentration of up to 7.5% but becomes almost independent of the C6/C7 concentration beyond 10%. This sensitization effect of C6 and C7 is also found to be more pronounced in the temperature range 700-900 K compared to that at higher temperatures (>900 K). The reason is attributed to the dependence of IDT primarily on H2O2(+M) ↔ 2ȮH(+M) at higher temperatures while the fuel-dependent reactions such as H-atom abstraction, RȮ2 dissociation, or QOOH + O2 reactions are less important compared to 700-900 K, where they are very important. [ABSTRACT FROM AUTHOR]

[Display omitted] Mass transfer limitations commonly challenge biofiltration for n -hexane emissions due to its high hydrophobicity. In this study, a bench-scale biotrickling filter (BTF) packed with reticulated polyurethane sponge was evaluated for n -hexane removal at various organic loading rates (OLRs) (ranging from 15 to 60 g m−3 h-1) and gas empty bed contact times (EBCTs) (ranging from 30 to 7.5 s). The obtained results show that the designed BTF can effectively remove n -hexane under intermittent spraying mode of the nutrient solution and the reticulated configuration of the packing media, which resulted in the spatial development of mycelium and enhanced mass transfer of n -hexane. The mean maximum removal efficiencies (REs) of n -hexane were 92.6 ± 0.9 %, 86.7 ± 4.8 %, and 63.8 ± 3.3 % under the OLRs of 15.67, 30.20, and 61.59 g m−3 h-1, respectively. When the BTF was operated under gas EBCTs of 30, 15, and 7.5 s, average REs of 85.9 ± 5.7 %, 44.8 ± 6.3 %, and 31.2 ± 2.5 % were achieved. The BTF also showed a superior fluctuation resistance capability and prevented excessive biofilm accumulation due to the reticular configuration of the polyurethane sponge. Results present in this study could provide an alternative consideration for the practical industrial application in treating hydrophobic VOC like n -hexane. [ABSTRACT FROM AUTHOR]

The influence of preparation conditions of the graphene foams on their physicochemical properties is shown. Different graphene aerogels were obtained from various graphene oxide water suspensions using the hydrothermal method (with or without the addition of acrylic microemulsion and varying in drying time—24 and 48 h). Prolonged drying of the hydrogels resulted in smaller pores in the foams. The composition of graphene oxide (GO) and acrylic polymer water suspensions leads to the smallest surface area which is due to the closing of the pores of the composite structure. Thermal treatment of samples at 950 °C removed the polymer residues. The heating process increased the surface area and the total pore volume of all samples, which were used to test the graphene foams (GFs) for adsorption of n-hexane. These tests have shown that the most effective samples for n-hexane adsorption were the samples where for the preparation of the composite GO and acrylic resin were used. The best of obtained samples adsorbed 415 mg g−1 of n-hexane which is a better result than for activated carbon manufactured from natural cork. Further preparation and modification of graphene foams could result in a significant increase in their sorption properties and could be used for contaminated air purification in the nearest future. [ABSTRACT FROM AUTHOR]

The kinetics of oxidative cracking of n‐hexane to light olefins using the lattice oxygen of VOx/SrO‐γAl2O3 catalysts has been investigated. Kinetic experiments were conducted in a CREC Riser Simulator (CERC: Chemical Reactor Engineering Center), which mimics fluidized bed reactors. The catalyst's performance is partly attributed to the moderate interaction between active VOx species and the SrO‐γAl2O3 support. This moderate interaction serves to control the release of lattice oxygen to curtail deep oxidation. The incorporation of basic SrO component in the support also helped to moderate the catalyst's acidity to checkmate excessive cracking. Langmuir‐Hinshelwood model was applied to formulate the rate equations. The intrinsic kinetic parameters were obtained by fitting the experimental data to the kinetic model using a nonlinear regression algorithm at a 95% confidence interval, implemented in MATLAB. n‐Hexane transforms to olefins at a specific reaction rate of 1.33 mol/gcat.s and activation energy of 119.2 kJ/mol. These values when compared with other duplets (i. e., ki° and EA) for paraffins to olefins, show that indeed olefins are stable products of the oxidative conversion of n‐hexane over VOx/SrO‐γAl2O3 under a fluidized bed condition. Values of activation energy for all COx formation routes indicate that intermediate paraffins are likely to be cracked to form CH4 than to be converted directly to COx. On the other hand, olefins may transform partly, and directly to COx (E9=9.65 kJ/mol) than to form CH4 (E8=89.1 kJ/mol) in the presence of excess lattice oxygen. Overall, olefins appear to be stable to deep oxidation due to the role of SrO in controlling the amount of lattice oxygen of the catalyst at the reaction temperature. [ABSTRACT FROM AUTHOR]

Cage‐based small‐pore zeolites are promising catalysts for catalytic applications such as methanol‐to‐olefins to produce light olefins and selective catalytic reduction to mitigate NOx emissions. The present paper reports our recent studies on vapor‐phase adsorption of n‐hexane in a series of small‐pore zeolites with cages such as 3A, 4A, 5A, ITQ‐29, SSZ‐13, SSZ‐16, SSZ‐17, SSZ‐36, SSZ‐50, ITQ‐12, ZK‐5, and Rho. The effects of zeolite compositions and crystal sizes on the adsorption kinetics and capacity are investigated, demonstrating that n‐hexane adsorption is a useful tool for characterizing the effective pore sizes and volumes of small pore zeolites. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to study the slow release effects of eight common kinds of slow release solvents on n-hexane, and to provide a reference for the construction of slow release system of attractants or repellents synthesized by plant volatiles. [Method] The effect of slow release solvents on volatile quantity and release rate of n-hexane was compared by weight loss method. [Result] Under indoor natural conditions [(22+2) °C, RH 50%±10%], the slow release effect of lubricating oil on n-hexane was the best, followed by liquid paraffin. The best ratio of slow release solvent (lubricating oil and liquid paraffin) and n-hexane was 54 and the best mixing time was 3 h, which improved the slow release effects of n-hexane by 6.3 and 4.7 times, and prolonged the half-life of n-hexane by 1.3 and 1.0 times, respectively. Slow release solvents mainly affected the post-half-life period of n-hexane, and the release rates of n-hexane mixed with lubricating oil and liquid paraffin were decreased by 10.4 and 7.7 times, respectively. During the half-life period, the release rates of n-hexane were decreased by 1.3 and 1.0 times, respectively. [Conclusion] Two kinds of slow release solvents with good slow release effect on volatile n-hexane are screened out, and the proportion and mixing time of slow release solvent and volatile are determined, which will provide technical support for the construction of plant volatile slow release system. [ABSTRACT FROM AUTHOR]

In this study, four crude bio-oils (CBOs) obtained from hydrothermal liquefaction of soybean straw (SS), peanut straw (PS), corn straw (CS) and rice straw (RS) were hydrotreated with various amounts of n-hexane. Then the obtained oil was separated into light oil (LO) and heavy oil (HO) by centrifugation. The LO yields increased from 53.89 to 59.15 wt% to 76.25–78.54 wt% when the mass ratio of n-hexane to CBO (w nH / w CBO) increased from 1:1–3:1. Despite containing the least asphaltenes, the hydrotreating of SS-CBO with n-hexane produced the lowest LO yield and the highest solid yield. The obtained LOs were mainly composed of saturated hydrocarbons, aromatics, and phenolic compounds, which showed obviously higher saturation and HHVs, also lower O and N contents than the corresponding HOs. Further hydrotreating of LOs resulted in significantly higher yields of upgraded light oils (ULO), falling in a narrower range of 92.04–93.48 wt%. The N and S content (26–503 ppm and <1 ppm, respectively) of the four ULOs all showed a sharp decline relative to the corresponding LOs. Saturated hydrocarbons (51.08–61.48%) and aromatics (31.98–43.00%) accounted for the vast majority of the identified compounds in the four ULOs, indicating the conversion of phenolic compounds in LOs to benzene and cyclohexane and their alkyl derivatives in the further hydrotreating process. • Four CBOs from HTL of straws were hydrotreated with addition of n-hexane. • Hydrotreated oil was separated into LO and HO by centrifugation. • Increasing w nH / w CBO was conducive to improving the yield and quality of LOs. • Further hydrotreating of LOs produced the ULOs with trace N and S atoms. • The four ULOs mainly contained saturated hydrocarbons and aromatics. [ABSTRACT FROM AUTHOR]

• The LLE data of n-hexane + EA + solvents (sulfolane/1,2-propanediol/DMSO) at 303.15 K, 313.15 K and 323.15 K were obtained. • The binary interaction parameters of the NRTL and UNIQUAC models were obtained. • The reliability of the regressed binary interaction parameters was confirmed by the GUI-MATLAB tool. • The interaction between the components was explored by σ-profile and interaction energy. In order to separate n-hexane/ethyl acetate (EA) produced in industrial production, the liquid–liquid extraction was used to separate the azeotropic system with sulfolane, 1,2-propanediol and dimethyl sulfoxide (DMSO) as extractants. The liquid–liquid equilibrium (LLE) data of the n-hexane + EA + sulfolane/1,2-propanediol/DMSO were measured at 303.15 K, 313.15 K and 323.15 K. The extraction capacity of the extractants were evaluated by the distribution coefficient (D) and separation factor (S). The LLE data were correlated using the NRTL and UNIQUAC thermodynamic models to obtain binary interaction parameters. The root mean square deviation (RMSD) were all less than 0.02 indicating that the two models were suitable for the phase equilibrium behavior. GUI-MATLAB software was used to test the reliability of the regressed binary interaction parameters. The Dmol3 module of the Materials Studio was used to analyze σ-profile of n-hexane, EA and extractants and to assess the interaction energy between the components. The results show that sulfolane is the best extractant for the separation of n-hexane + EA. [ABSTRACT FROM AUTHOR]

Sustainable biodiesel production can be realised by the use of a low-cost feedstock, efficient energy and renewable raw materials. The simultaneous Calophyllum oil-resin extraction and its purification using a binary solvent (n-hexane mixed with alcohol) were examined to meet those aspects. The extraction conditions effect was investigated to determine the optimal oil yield and quality. n-Hexane mixed with alcohol was extracted and purified effectively the oil from Calophyllum seeds. The oil yield and its quality were mainly affected by the n-hexane-to-alcohol ratio. The oil yield enhanced as the n-hexane-to-alcohol ratio enlarged from 1:1 to 2.5:1. The acid value and density of the oil improved as the n-hexane-to-alcohol ratio declined from 2.5:1 to 1:1. The n-Hexane-to-alcohol ratio of 2.5:1 provided the best yield (59%) of the oil extracted at 40°C for 5 hours. The oil presented its best quality at 0.893 g.cm-3 of density, 41.0 mPa.s of viscosity, 8.8 mg KOH.g-1 of the acid value, 88.3 g per 100 g of the iodine value, < 1% of moisture content and < 0.04% of ash content. The oil also had an inhibitory activity against Staphylococcus aureus.

The extraction of fat/oil from fleshing by-products using moist heating (boiled and steamed) produces a fat that contains large amounts of impurities and which is bluish color, whereas when using fatty solvents, it is necessary to dry the ingredients. The purpose of this study was to determine the fat/oil characteristics from fleshing by-products extracted using a combination of wet rendering (temperatures of 80, 90 and 100 °C, and times 1, 2 and 3 hours) with n-hexane. The combined treatment of wet rendering (temperature 90 °C and duration 2 hours) with n-hexane gave rise to the production of fat with the highest yield (11.10% w/w). The higher the temperature and the longer the wet rendering process, results in fat with higher levels of free fatty acid and the saponification value, but the lower the number of peroxides and the darker the color. The fats/oils consist of 37 fatty acid compounds, composed of saturated and unsaturated fatty acids. There are six very present fatty acid compounds, namely butyric acid methyl ester, tetradecanoic acid methyl ester, cis-10-pentadecanoic acid methyl ester, palmitoleic acid methyl ester, octadecanoic acid methyl ester and trans-9-elaidic acid methyl ester.

In this study, we investigated the decomposition characteristics of n-hexane by a dielectric barrier discharge (DBD) plasma. In order to accomplish this, the factors influencing these decomposition characteristics such as background gases (air, N2, and He), residence time (1–10 s), initial n-hexane concentration (10–50 ppm), relative humidity (2.5%, 40%, and 70%), and power (50–80 W) were evaluated. As a result, the decomposition efficiency of n-hexane at N2 atmosphere was found to be lower than those at air and He atmosphere. The removal efficiency of n-hexane was increased when the residence time, relative humidity, and power increased, and when the initial concentration decreased. The concentrations of CO, CO2, and aerosol increased as the specific energy density increased. However, the O3 level increased up to a certain point, then decreased. Various hydrocarbons such as acetone, pentanal, nonanal, etc. were also detected as by-products and their decomposition and recombination pathways were suggested. [ABSTRACT FROM AUTHOR]

BACKGROUND: As an important indicator of land environmental quality, the content of petroleum substances determines the use of land. For the sample of reclaimed land, it reflects the reclamation and treatment effect of contaminated land to a certain extent. The determination methods of petroleum substances in soil samples mainly include gas chromatography, infrared spectrophotometry, and ultraviolet spectroscopy. Gas chromatography is mainly used for the determination of saturated alkanes in samples; infrared spectrophotometry is used to characterize petroleum substances in samples by measuring the characteristic absorption values at different wave numbers. OBJECTIVES: The detection limit is high. In this paper, the content of petroleum substances in the reclaimed land samples is not high, and the components are mostly difficult to volatilize, the structure is complex, and the matrix interference is large. Using n-hexane as the solvent, accelerated solvent extraction (ASE) pretreatment, and fluorescence spectrophotometer Of petroleum-based substances. The working curve was prepared with marine environmental monitoring petroleum standard materials as standard samples, and the linear correlation coefficient r 2 =0.9997; the detection limit of the method was 0.40mg/kg, and the lower limit of detection was 1.60mg/kg; the precision of the actual sample method was 1.10%~8.76 %; The recovery rate of matrix addition is 89.0%~95.7%; the results of detecting actual samples are basically consistent with the currently valid HJ 1051-2019 infrared spectrophotometric method, and the determination results of high-content samples are higher than the infrared method. The toxicity of the solvent n-hexane used in this method is less than that of tetrachloroethylene. The pretreatment method ASE has a high degree of automation, high extraction efficiency, and an increase in precision of 11.5%-67.3%. For samples with relatively complex structure of petroleum components and difficult to extract, the detection limit of this method is lower than that of infrared method (4mg/kg). [ABSTRACT FROM AUTHOR]

This research optimised the application of a hexane-methanol mixture as a binary solvent for the concurrent oil-resin extraction and separation from Calophyllum seeds on a pilot scale, in a direct stage. The optimum oil and resin yields were determined by optimising the extraction conditions using response surface methodology and a second order polynomial model. The extraction conditions affected the oil and resin yields, with the extraction time as the biggest influencing factor. Optimum oil (65%) and resin (16%) yields were predicted to be obtained at 5.2 h and 433 rpm. The model validation with these extraction conditions showed that the predicted results and actual oil (62%) and resin (15%) yields were in passable agreement. The oil was composed of 75.4% triglycerides with a density of 0.874 g·cm-3, a viscosity of 26.4 mPa·s-1, an acid value of 46.4 mg KOH·g-1, an iodine value of 98.0 g iodine·100 g-1, trace water and sediment contents, and zero ash content. The resin had a viscosity of 4 694.8 mPa·s-1, a total phenolic content of a 4.51% gallic acid equivalent, an antioxidant activity of an 8.82 mg ascorbic acid equivalent·g-1, and an acid value of 126.2 mg KOH·g-1. [ABSTRACT FROM AUTHOR]

The principal objective of this study was to evaluate the efficacy of n-hexane extract of pulp seed of Pumpkin (Cucurbita maxima) and Neem (Azadirachta indica) compared with levamisole hydrochloride against Ascaridia galliin vitro. The study included anthelmintic activity of C. maxima and A. indica hexane extract, which consisted of two steps. The first step collection 240 adult A. galli worms and divided into 8 groups 30 worms/group (6 groups) incubated with pumpkin and neem extract at different concentration, 7 and 8 groups incubated with levamisole 0.025 mg/ml and phosphate buffer saline respectively. Worm motility was recorded at 0, 1, 3, and 6 h intervals after incubation. The second steps 150 egg of A. galli divided for seven groups for detect efficacy of plant extract on eggs development to larvae, six groups incubated with C. maxima and A. indica at different concentration, 7th groups incubated with BPS as negative control. Eggs development were examined at 10, 15, 20 days after incubation. The results of the in-vitro anthelmintic activity showed that percent mortality of adult worm after 6hr of incubation 97.38%, 99.50% and 100% of C. maxima, A. indica and levamisole respectively. The result of inhibited larva development of Ascaridia galli eggs was concentration dependent. The lowest concentration 5mg/ml of the C. maxima and A. indica extracts had an inhibition percent, 76% and 84%, respectively. The highest concentration 20 mg/ml recorded higher percentage inhibition 92% and 96% respectively. From the results obtained, it could be concluded that n-hexane extract of C. maxima, A. indica pulp seed was more effective and safe in comparison with anthelmintic agent, have an inhibitory effect on the development of larval stages of Ascaridia galli in vitro and could be a potential alternative for treating cases of A. galli infections in chickens [ABSTRACT FROM AUTHOR]

The paper reports the preparation of two series of nanosized (150–350 nm) ZSM-5 zeolite crystals with a Si/Al molar ratio of 70 to 144 by a template method. The prepared catalysts are distinctive in their mostly intercrystalline macroporosity and random architecture of transport channels formed as a result of the utilization of a high-molecular-weight template represented by suspended or powdered polystyrene particles about 250 nm in size. The crystallinity and the size and packing of the particles depend on the method of template introduction into a precursor mixture. The samples of both series were tested in an n-hexane cracking reaction, and the comparative assessment of their catalytic properties in terms of n-hexane conversion degree and selectivity for alkane, olefin, and isoalkane products is also summarized in the paper. [ABSTRACT FROM AUTHOR]

Shock tubes are used as homogeneous batch reactors to measure ignition delay times, reaction rate coefficients and species time-histories of a variety of chemical systems. Any non-ideality or inhomogeneity in the shock tube experiment would affect the quality and usefulness of measured data. Experimental and computational efforts have previously been carried out to characterize the regimes of ideal operation of shock tubes. High-speed imaging has proven to be a highly useful tool to assess ignition homogeneity. In this work, a dual-camera setup has been used with an optical end-section in a circular shock tube to obtain simultaneous high-speed images from the shock tube endwall and sidewall, thus providing visualization of the ignition phenomenon in three dimensions. Two case studies are presented herein to demonstrate the quality of data and insights that are obtained using this diagnostic technique to study the ignition modes of different fuels. The first is a comparison of the ignition of two alternative fuels, methanol and ethanol, and the second is a study of the ignition dependence on the fuel concentration of a representative paraffinic fuel, n -hexane. The unique dual-camera imaging diagnostic enabled deeper insights into the ignition homogeneity, with all fuels exhibiting localized ignition at low temperatures. Methanol showed a higher propensity than ethanol to ignite far from the endwall, and the high concentration of n -hexane led to inhomogeneous ignition. [ABSTRACT FROM AUTHOR]

Due to the toxic effects from using conventional trypanocidal drugs, there is need for development of safer alternatives to combat trypanosomosis. The aim of this study was to evaluate the effects of n-hexane and ethylacetate fractions of Terminalia catappa leaf extract in Wistar rats experimentally infected with Trypanosoma brucei brucei. Forty-five (45) adult Wistar rats were divided into 9 groups (A–I) comprising of 5 rats each after acclimatisation for 7 days. Groups A-H were infected intraperitoneally with T. brucei brucei (day 0), treatment given to groups A–G at day 3 post-infection while group I were uninfected. Groups A, B and C are treated daily with 100, 200 and 300 mg/kg n-hexane fraction (HF); D, E and F treated daily with 100, 200 and 300 mg/kg ethylacetate fraction (EAF); and G treated with diminazene aceturate once. Blood was collected for parasitaemia determination and haematology. Results revealed parasitaemia detection by day 2 pi and complete clearance by day 10 pi in groups F and G, and 100% mortality in groups A and G. There was significant decrease in packed cells volume, haemoglobin concentration, red and total white blood cells in all infected groups by day 3 pi. Following treatment at day 10 pi, these haematological parameters significantly increase towards pre-infection values and were significantly higher in groups F and G compared to the other treatment groups. The ethylacetate fraction of Terminalia catappa leaf extract at 300 mg/kg exhibited in vivo trypanocidal activity similar to diminazene aceturate. [ABSTRACT FROM AUTHOR]

The speed of sound in high-purity n-hexane and n-heptane was experimentally studied utilizing the double-path length pulse-echo technique. Measurements with each alkane were carried out at temperatures from (233 to 353) K with pressures up to 20 MPa. Considering the uncertainty contributions from temperature, pressure, path-length calibration, pulse timing and sample purity, the relative expanded combined uncertainty (k = 2) in the speed of sound in n-hexane ranges from (0.012 to 0.042) % over the investigated ranges of pressure and temperature; for n-heptane, the uncertainty varies from (0.014 to 0.018) %. The sound speed data measured in n-hexane were among the data used for the development of a new fundamental equation of state, which is, however, not described in this work. The experimental data of n-heptane can be considered appropriate for modeling purposes and validation of existing equations of state. [ABSTRACT FROM AUTHOR]

• Bubbling, turbulent and pneumatic regimes applied in the photocatalytic reactor. • Freeboard Elutriation Model successfully applied to the photo reactor. • Solids holdup of 10% and turbulent regime were found as optimum for operation. The fluidization behaviour of a circulating fluidized bed (CFB) photoreactor was varied by applying different flow (Q) and solid feed rates (F s), and the performance of the reactor for the degradation of the target pollutant n -hexane was compared for a wide range of fluidization regimes. The Freeboard Entrainment Model was applied to model and predict the values of solids hold-up (ε s) in the experimental range evaluated. The optimum n -hexane degradation rate for the CFB was found to be 4.0 × 10−4 mol m-3 s-1 operating in turbulent fluidization regime with ε s = 0.10 with the finer solid size distribution, demonstrating that high-velocity fluidization regimes can be used to enhance photocatalytic reaction rates based on better UV-photocatalyst contact. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) used as an additive in polyvinyl chloride (PVC) products is an endocrine disrupter that causes negative effects on human health. The aim of the present study is to investigate the BPA contents in 26 different plastics bought from China, their major components were identified by Fourier transform infrared (FT‐IR) spectrometry, and the migration of BPA from these materials into four representative solvents and four foods were determined by high‐performance liquid chromatography (HPLC). Results showed that nine kinds of plastics were identified as PVC, and eight plastic samples were PVC‐based films. Recoveries of BPA in films and foods were 88.87%–97.29%, and their precisions expressed as relative standard deviation (RSD) were 1.17%–4.72%. The limit of detection (LOD) was 0.01–0.02 μg ml−1. In the tests of migration into water, 20% ethanol, 4% acetic acid, and n‐hexane, migrations from given films, were in all cases greatest into n‐hexane (7.44–20 mg kg−1 after 24 h). Migrations from the films with nonzero BPA contents to four foods ranged from 0.079 to 0.403 mg kg−1, which were higher than the updated European Union specific migration limit for BPA (0.05 mg kg−1). Therefore, PVC should be taken into account in estimating BPA intake or exposure to this substance. [ABSTRACT FROM AUTHOR]

2-Propanol and n-hexane are widely used (as) chemical reagents in electronic, pharmaceutical, and chemical industries. An efficient separation of the azeotropic system of 2-propanol-n-hexane is of profound practical significance. By using the conductor-like screening model for real solve (COSMO-RS) predictive model, ionic liquids as extractants for separating the azeotropic system of 2-propanol-n-hexane were evaluated with selectivity coefficients ( S ) and capacity ( C ) as the evaluation indexes. Based on the evaluation results, one high-performance extractants named hydroxylamine Cl (C8A19) was selected from 435 kinds of ionic liquids designed by combining 29 kinds of anions and 15 kinds of cations. Moreover, the reliability of the model in predicting the vapor-liquid phase equilibrium behavior of 2-propanol-n-hexane system was verified. Then, the effect of C8A19 on the vapor-liquid phase equilibrium of the 2-propanol-n-hexane system was investigated theoretically and experimentally. The results show that the azeotrope of the system can be broken when the molar fraction of C8A19 is 0.02, denoting that C8A19 can be used for enhanced separation of 2-propanol-n-hexane system. On the basis of the aforementioned study, the selectivity mechanism of the extractant was analyzed from the perspective of microscopic molecular interactions by using the descriptor ( σ -profiles) of COSMO-RS. This study provides both theoretical and data support for further designing high-performance ionic liquid extractants and extraction process., (© 2024 IOP Publishing Ltd.)

The effect of the silicon to aluminum ratio (SAR) and alkali metal cations on adsorption and diffusion properties of ZSM-5 and silicate-1 zeolites was investigated using n-hexane as the model probe via giant canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. A wide range of SAR was considered in this study to explore the possible adsorption sites in the zeolites. The findings show that, at 298 K and 423 K, adsorption and diffusion of n-hexane on/in low SAR (≤50) H-ZSM-5 models were promoted due to the preferable distribution of n-hexane in straight channels and enhanced interaction between protons and n-hexane molecules (about 24 kcal·mol−1). In alkali metal cation (i.e., Na+ and K+) exchanged ZSM-5, the alkali metal cations affected transport of molecules, which led to significant differences in their adsorption and diffusion properties compared to HZSM-5. In the Na+ and K+ systems, lower saturated adsorption capacities were predicted compared to that of silicate-1, which could be attributed to the decrease in effective void size posed by alkali–metal cations. In addition, simulation results also suggested that the T9 and T3 are the most likely sites for n-hexane adsorption, followed by T2, T5, and T10. Findings of the work can be beneficial to the rational design of high-performance zeolite catalysts for n-hexane conversion.

Some of the secondary metabolites present in red algae are terpenoids, quinones, flavonoids, alkaloids, essential oils, diarylheptanoids, steroids, cardioglycosides, oils and fats, tannins, carbohydrates. Activity of rhizomes, leaves and flowers red leaf is as antimicrobial, anti-fungal, anti-oxidants, anti-tumor, anti-cancer and vasodilator. One way to improve the physical, chemical and bioactivity properties of natural compounds was to make them into nanoparticles. In this study, the isolation of bioactive compounds contained in red laos rhizome by maceration method using ethanol solvent was done, then partitioned with n-hexane and ethyl acetate. The extracts thus obtained are fabricated into nanoparticles. Extracts in bulk and nanoparticles were then tested for cytotoxic activity using BSLT method. Results of analysis with PSA showed that ethanol extract had size 410,8 nm, n-hexane extract 220,7 nm and ethyl acetate extract 208,3 nm. The results of cytotoxic tests showed that nanoparticle size increased cytotoxic activity. Ethyl acetate extract was most active compared to ethanol and n-hexane extracts with LC50values of 17.919; 84,956; 166,526 ppm. Whereas the nanoparticle size was respectively 10,491; 74,072 and 84,197 ppm. Cytotoxic activity increases with nanoparticle fabrication.

The Homogeneous Charge Compression Ignition (HCCI) concept shows great potential for improving engine efficiency and reducing pollutant emissions. However, the operation with this concept in Internal Combustion (IC) engines is still limited to low speed and load conditions, as excessive Pressure Rise Rates (PRR) are generated with its fast auto-ignition. To overcome this limitation, the use of moderate thermal and charge stratification has been promoted. This leads to multi-stage ignition, and thus a potentially acceptable PRR. Recently Sarathy et al. (2019), three-stage auto-ignition has been emphasized as a chemical phenomenon where the thermal runaway is inhibited during the main ignition event. The current paper demonstrates experimental evidence on this phenomenon observed during n-heptane and n-hexane auto-ignition at lean diluted conditions in a flat piston Rapid Compression Machine (RCM). Multi-stage ignition events caused by either chemical kinetics or by the well-known thermal stratification of this type of RCM are clearly identified and differentiated. The combination of these two factors seems to be a suitable solution to overcome PRR limitations. [ABSTRACT FROM AUTHOR]

Monitoring the trace amount of chemicals in various samples remains a challenge. This study was conducted to develop a new solid‐phase microextraction (SPME) system (inside‐tube SPME) for trace analysis of n‐hexane in air and urine matrix. The inside‐tube SPME system was prepared based on the phase separation technique. A mixture of carbon aerogel and polystyrene was loaded inside the needle using methanol as the anti‐solvent. The air matrix of n‐hexane was prepared in a Tedlar bag, and n‐hexane vapor was sampled at a flow rate of 0.1 L/min. Urine samples spiked with n‐hexane were used to simulate the sampling method. The limit of detection using the inside‐tube SPME was 0.0003 μg/sample with 2.5 mg of adsorbent, whereas that using the packed needle was 0.004 μg/sample with 5 mg of carbon aerogel. For n‐hexane analysis, the day‐to‐day and within‐day coefficient variation were lower than 1.37%, with recoveries over 98.41% achieved. The inside‐tube SPME is an inter‐link device between two sample preparation methods, namely, a needle trap device and an SPME system. The result of this study suggested the use of the inside‐tube SPME containing carbon aerogel (adsorbent) as a simple and fast method with low cost for n‐hexane evaluation. [ABSTRACT FROM AUTHOR]

The conversion of n-hexane and methanol into value-added aromatic compounds is a promising method for their industrially relevant utilization. In this study, intergrown ZSM-5/ZSM-11 crystals were synthesized and their resulting catalytic performance was investigated and compared to those of the isolated ZSM-5 and ZSM-11 zeolites. The physicochemical properties of ZSM-5/ZSM-11 intergrown zeolite were analyzed using X-ray diffraction, N2 isothermal adsorption-desorption, the temperature-programmed desorption of ammonium, scanning electron microscopy, Fourier transform infrared spectra of adsorbed pyridine, and nuclear magnetic resonance of 27Al, and compared with those of the ZSM-5 and ZSM-11 zeolites. The catalytic performances of the materials were evaluated during the co-feeding reaction of methanol and n-hexane under the fixed bed conditions of 400°C, 0.5 MPa (N2), methanol:n-hexane = 7:3 (mass ratio), and weight hourly space velocity = 1 h−1 (methanol). Compared to the ZSM-5 and ZSM-11 zeolites, the ZSM-5/ZSM-11 zeolite exhibited the largest specific surface area, a unique crystal structure, moderate acidity, and suitable Brønsted/Lewis acid ratio. The evaluation results showed that ZSM-5/ZSM-11 catalyst exhibited better catalytic reactivity than the ZSM-5 and ZSM-11 catalysts in terms of methanol conversion rate, n-hexane conversion rate, and aromatic selectivity. The outstanding catalytic property of the intergrown ZSM-5/ZSM-11 was attributed to the enhanced diffusion associated with its unique crystal structure. The benefit of using zeolite intergrowth in the co-conversion of methanol and alkanes offers a novel route for future catalyst development. [ABSTRACT FROM AUTHOR]

• Solvent exposure caused prolonged menstrual cycles and longer time to get pregnant. • 2,5 hexanedione urinary levels negatively correlated with FSH serum levels. • Cigarette consumption reduced oestradiol levels in women exposed to n-hexane. • N-hexane and its metabolite may play a role as endocrine disruptors. Human exposure to n-hexane has been associated with subfertility and, experimentally, with a decrease in follicular development. In order to assess occupational exposure to n-hexane on ovarian function and gonadotropic hormones, we studied Mexican women labouring in a leather shoe factory (n = 34). Individual environmental levels for seven solvents, n-hexane included, were measured; also, urinary 2,5-hexanedione (2,5-HD) was determined. For ovarian function and hormonal status, FSH, LH, oestradiol and anti-Müllerian hormone (AMH) levels were determined. We performed all determinations also in a reference group, administrative workers with no exposure to solvents (n = 32). Results: N-hexane and urinary 2,5-HD levels were higher in exposed group (p < 0.001). More cases of oligomenorrhea as well as longer time for getting pregnant were observed in exposed women compared with controls; a positive association was found between menstrual cycle length and "time for getting pregnant" (p = 0.010); significant associations between FSH serum levels and 2,5-HD urinary levels (post-shift sample) were observed in non-smokers participants presenting oligomenorrhea from exposed group. Also, we found a trend for lower oestradiol levels in exposed participants with current smoking habit (p = 0.059). Conclusions: 2,5-HD urinary levels are associated with decreased gonadotropins levels; hence, n-hexane should be considered an endocrine disruptor in reproductive-age women. [ABSTRACT FROM AUTHOR]

The effect of individual and multicomponent additives—water-soluble polymers (polyethylene glycol 400, polypropylene glycol 425, and polyvinylpyrrolidone 3500), sodium nitrate, and 1-methyl-2-pyrrolidone—on the extraction of thiophene in an n-hexane–water system has been studied. It is found that, in most cases, the introduction of small amounts of additives into the extraction system leads to a significant increase in the degree of extraction of thiophene from n-hexane in the aqueous phase in comparison with the individual components. [ABSTRACT FROM AUTHOR]