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Isobaric vapor–liquid phase equilibrium (VLE) data for binary systems of n-hexane + methylcyclopentane, n-hexane + N,N-dimethylamide (DMF), methylcyclopentane + DMF and ternary system of n-hexane + methylcyclopentane + DMF were generated using a modified Rose still at 101.3 kPa. The thermodynamic consistency for the VLE data were confirmed by the Wisniak's test. Binary interaction parameters (BIPs) were obtained on the calculation of VLE for these binary systems by Wilson, NRTL and UNIQUAC activity coefficient models. The estimation values of the three models showed a good fit with the experimental data. The BIPs were also employed to predict the T–x–y data of ternary system n-hexane + methylcyclopentane + DMF. The results presented a favorable match between experimental data and the predicted values. The y–x diagram of methylcyclopentane + n-hexane system was plotted with or without DMF, which confirmed that DMF as a extractant has a remarkable effect on the extractive distillation of these two components. [ABSTRACT FROM AUTHOR]

Fluorous solvents are deputed as prominent solvent systems owing to their salient features, unique physical properties, and ecological importance. In this study, the temperature- and composition-dependence of physical properties, density (ρ/g·cm−3), and dynamic viscosity (η/mPa·s), of neat perfluorodecalin (PFD) and PFD-added n-hexane mixtures with select compositions are reported. Density follows a linear decrease with temperature and a quadratic increase with the mole fraction of PFD. The sensitivity or dependence of density on temperature increases with an increase in PFD mole fraction. The temperature-dependence of the dynamic viscosity of the investigated mixtures follows the Arrhenius-type expression from which the resultant activation energy of the viscous flow (Ea,η) is determined. Interestingly, the composition-dependence of dynamic viscosity shows exponential growth with an increase in PFD mole fraction. Excess molar volumes (VE) and deviation in the logarithmic viscosities ∆(ln η) of the mixtures are calculated to highlight the presence of strong repulsive interactions between the two mixture components.

Automotive technicians are commonly exposed to organic and chlorinated solvents, particularly through use of cleaning products. Mainly during the period 1989-2002, n-hexane was a component of some of these products. In other occupational contexts, n-hexane has been shown to be a cause of peripheral neuropathy. The purpose of the present study was to investigate whether previous exposures to low concentrations of n-hexane were a cause of persistent peripheral neuropathy in automotive technicians. Enrolled in the study were 830 San Francisco Bay Area automotive technicians. Each participant underwent a battery of tests to investigate peripheral nervous system impairment. Test results regressed against estimated hexane and total solvent exposures showed only limited evidence of association with solvent exposures. Exposures to both hexane and general solvents were well below their occupational exposure limits. Generally, our results provide reassurance about persistent peripheral neuropathic effects in automotive technicians who previously used hexane-containing automotive cleaning products. This may reflect repair processes, since the exposures occurred some years previous to the study. However, we cannot exclude the possibility that the absence of observed effect in this study may be attributable to low exposures, exposure misclassification and/or the healthy worker survivor effect.

Co-exposure to n-hexane and methyl ethyl ketone (MEK) may induce neurotoxicity in humans. Since biomonitoring of exposed chemicals is a powerful hygienic way of controlling chemical risk, a new molecularly imprinted polymer (MIP) is reported in this study. Polymerization was carried out upon the surface of magnetic silica aerogel (Si@Fe3O4) using 2-octanone as a dummy template to prepare Si@Fe3O4-MIP. The synthesized MIP was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectrometry thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) analysis, and vibration sample magnetometry (VSM). The reported method was utilized for the selective extraction of n-hexane and MEK from humane urine using gas chromatography – flame ionization detection (GC-FID). The highest selectivity coefficient of Si@Fe3O4-MIP was obtained for n-hexane and MEK. The validity of solid phase extraction (SPE)-based Si@Fe3O4-MIP was confirmed by the recovery (> 93.6%) and acceptable reproducibility was obtained with relative standard deviations between 1.6 and 8%. The limit of quantifications (LOQ) for n-hexane and MEK were 1.5 and 128 µg/L, respectively. The validated SPE-based Si@Fe3O4-MIP is suggested for determining n-hexane and MEK in urine of shoemaker workers for biomonitoring purposes. [ABSTRACT FROM AUTHOR]

One of the main challenges that hinder achievement of the third millennium sustainable development goal is emergence of infectious agents that are resistant to existing antimicrobials. These challenges entails search for novel bioactive compounds like exploring untapped potential of medicinal plants and their associated endophytes. The present study was aimed to investigate the antimicrobial activities of crude extracts of endophytic fungi isolated from medicinal plants Kigelia africana and Phyllanthus niruri. Pure isolates of endophytic fungi were subjected to initial screening, and isolates that exhibited inhibition were genotyped by Sanger sequencing for genus and species confirmation. Then, antimicrobial activity of crude extracts of selected isolates: Nigrospora sphaerica, Meyerozyma guilliermondii, Alternaria alternata and Phyllosticta capitalensis was evaluated by disc diffusion method against E. coli (Gram-negative), S. typhi (Gram-negative), and S. aureus (Gram-positive). Findings indicated high variability (8.5 -23.1 mm) of crude extract concentrations of isolates, and the highest zone of inhibition was found in ethyl acetate crude extract of M. guilliermondii against S. aureus. Furthermore, the lowest MIC (9.9 >MIC>5.0) was found in n-hexane crude extract of P.capitalensis against S. typhi. However, all crude extracts did not show any activity against E. coli. Results of present study corroborate on the influence of extracting solvent on the effectiveness of crude extract of isolates against pathogen microorganisms. Interestingly, findings demonstrated the potential of endophytes from medicinal plants for medical applications, and therefore further investigation may lead to discovery of novel bioactive compound potent to resistant infectious agents.

Delonix regia (DR) lignocellulosic biomass waste contributes to large quantities of daily solid waste which is having high volatile matter that can be utilized for the production of bio-oil by pyrolysis. The pyrolytic raw bio-oil consists of both fuel and non-fuel fractions which can be separated by organic solvents. Further, application of mixed or individual metal oxide catalysts in pyrolysis reactor along with the feed reduces the corrosiveness and improves stability of pyrolytic bio-oil. Therefore, novelty statement includes catalytic pyrolysis of DR carried out in the presence of mixed metal oxide catalysts, TiO2 and ZnO; followed by separation of fuel and non-fuel fractions of pyrolytic bio-oil using dichloromethane and n-hexane solvents. The improvement of product quality was realized by catalytic activity though the yield is almost unaffected compared to that of non-catalytic pyrolysis. Addition of solvents, helped improving quality of bio-oil by separating out non-fuel phase from it. Each experiment repeated thrice to ensure repeatability and reliability. Higher heating value (HHV) of pyrolytic raw liquid oil increased by 16.2% by the use of catalyst compared to that of non-catalytic pyrolytic raw liquid oil whereas the pH enhanced from 3.72 to 4.77, which indicated catalytic bio-oil has become less acidic. In addition, the physical and fuel properties of fuel fraction obtained by n-hexane are found to be superior to those obtained by dichloromethane. For instant, HHV of fuel portion separated with n-hexane is 23% higher than that obtained with dichloromethane. Density of fuel part obtained by n-hexane was found to be 0.74 g/ml (close to that of commercial gasoline) which is much low as compared to that obtained by using dichloromethane that is having density of 1.01 g/ml. Fourier-Transform InfraRed (FTIR) spectroscopy and proton Nuclear Magnetic Resonance (NMR) spectroscopy of fuel fraction of liquid product indicated partial deoxygenation of bio-oil by separating it with n-hexane.

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. [ABSTRACT FROM AUTHOR]

VOCs emission reduction in the petroleum and petrochemical industry is a hot and difficult topic at present. The single method may not be able to meet the actual treatment status. Therefore, the adsorption coupled photocatalytic degradation technology was used to remove VOCs. Phosphorus-doped carbon nitride (PCN) and PCN/TiO2 were prepared by hydrothermal synthesis and sol–gel method, and then PCN/TiO2/Zn(OAc)2-ACF composites were prepared by ultrasonic impregnation on zinc acetate modified activated carbon fibers (Zn(OAc)2-ACF). The removal efficiency of n-hexane by composite materials was explored in a self-made reactor, and the factors affecting removal efficiency, removal mechanism, and possible ways of degradation were investigated. The results showed that under the optimum reaction conditions (initial concentration of n-hexane 200 mg/m3, space velocity 1000 h−1, light intensity 24 W, mass fraction of doped PCN 6%, loading twice, calcination temperature 450 °C), PCN/TiO2/Zn(OAc)2-ACF composite has the highest removal efficiency of n-hexane (90.2%). The adsorption capacity of the composites after doping the P element was 215.3 mg/g, which did not enhance the adsorption performance compared with that before doping, but the removal rate of n-hexane was higher. This showed that doping P element was helpful to enhance the photocatalytic activity of the composites. [ABSTRACT FROM AUTHOR]

The present investigation reports the interaction between tri-n-octyl amine (TOA) and n-hexane in the temperature range 298.15 to 313.15 K with 5 K interval. The experimental values of density (ρ), molar volume (Vm), partial molar volume (), apparent molar volume (Vφ), dielectric constant (ɛ), refractive index (nD), molar polarization (Pm), and molar refraction (Rm) at various temperatures are presented. Dielectric constant and refractive index have been estimated using mixing rules. Excess values of ( , , ΔnDm, , and ) are determined to get information regarding the interaction between two components. Redlich–Kister polynomial equation has been used to for the fitting of excess values. This observation is well supported by positive deviation of the refractive index at the reported temperatures. The g values more than unity prove that less interaction in mixture leading to probability of its efficient contribution towards metal solvent extraction. The FTIR studies also complements the observations obtained from the scrutiny of different physicochemical properties. [ABSTRACT FROM AUTHOR]

In this work, we used three gases (CO2, N2 and normal hexane) for diffusivity measurements in Acrylonitrile butadiene styrene (ABS). We proposed a diffusion model that the diffusion coefficients of each gas in ABS could be estimated from the specific volume of ABS/gas mixture and chemical potential of gas in ABS. The solubility and diffusivity of three gases into ABS were determined by a magnetic suspension balance. The results showed that the solubility and diffusivity of three gases increased with increasing of pressure. Also it was determined that N2 has a lowest solubility and the highest diffusivity in ABS in all temperature and pressure ranges. It was shown that there was a suitable overlapping between the experimental and predicted values from the proposed model, in which the proposed model could successfully estimate the diffusion coefficient of mentioned gases in ABS in all temperature and pressure ranges. [ABSTRACT FROM AUTHOR]

Oil-based drilling cuttings (OBDC) have a high content of petroleum pollutants with strong mutagenic, carcinogenic and teratogenic properties. Solvent extraction can effectively separate petroleum pollutants from OBDC. However, single solvent has preferred solubility for different types of petroleum pollutants in OBDC, resulting in a lower oil removal efficiency. Therefore, based on the polarity difference between methanol (Me) and n-hexane (He), a method was developed to extract petroleum pollutants from OBDC using Me&He. Compared with methanol or n-hexane alone, the oil removal efficiency of compound Me&He was significantly increased to 94.58 %, and 37, 37 and 77 petroleum pollutants were extracted using Single methanol, Single n-hexane and Compound Me&He, respectively. Methanol extraction preferentially solubilised polar molecules such as alcohols and carboxylic acids, while n-hexane extraction preferentially solubilised alkanes and other nonpolar molecules. Compound Me&He compensated for the low solubility of single solvents for petroleum pollutant extraction from OBDC. Additionally, because methanol and n-hexane are not mutually soluble, it was easy to separate the recycled components. Compared with other common solvent extraction technologies, compound Me&He had advantages including simple operation and high oil removal efficiency. This study provided a theoretical basis and technical reference for the efficient processing and resource recycling of OBDC. • Methanol and n-hexane are applied to extract petroleum pollutants from OBDC. • Compound solvent compensates for the low oil removal efficiency of single solvents. • Compounds recovered by methanol&n-hexane solvent are identified. • The influential factors and the extraction mechanisms are investigated. [ABSTRACT FROM AUTHOR]

Introduction: : Diabetes Mellitus is a major health problem characterized by hyperglycemia and disturbances in metabolism and implicated in causing oxidative stress. Treatment includes administration of oral hypoglycaemic agents with lifestyle modifications, these offer glycemic control, however, present limitations about availability, affordability and side effects. Traditional anti-diabetic plants are becoming popular in management of diabetes mellitus. This study was carried out to determine the efficacy of Leptadenaia hastata in treatment of diabetes. Materials and methods: Diabetes mellitus was induced in using a single injection of streptozotocin (50 mg kg− 1 i.p.). The rats were divided into four groups of 5 rats each. Groups 3–6 received olive oil, 100 mg kg− 1 extract, 200 mg.kg− 1 extract and insulin (6IU kg− 1), respectively. 10 non-diabetic rats were grouped into two group receiving olive oil and 200 mg kg− 1 extract for 28 days. All groups were sacrificed by injecting with ketamine hydrochloride, blood was collected by cardiac puncture and centrifuged. The serum was analyzed for biochemical parameters. The liver was removed and homogenized with the supernatant of the resultant homogenate collected and used for analysis of oxidative stress enzymes. Results: The extract significantly decreased serum AST (p < 0.05), ALP (p < 0.001), ALT (p < 0.05), TG (p < 0.01), TC (p < 0.001), creatinine (p < 0.001). It had no effect on SOD and CAT levels but it significantly increased (p < 0.001) GSH levels and reduced (p < 0.05) MDA level. Conclusions: The n-hexane extract of Leptadenia hastata significantly decreased the levels of hepatic and renal serum biomarkers proving that it was beneficial in ameliorating diabetic related complications. The extract significantly increased GSH levels and reduced MDA level. [ABSTRACT FROM AUTHOR]

The purpose of research is to investigate the antifungal potential of papaya seed extract and the biosynthesis of silver nanoparticles by C. papaya extract. Here we report 14 secondary metabolites from C. papaya seed extract detected by gas chromatography mass spectroscopy. Bioactive components were majority classified as fatty acid-methyl ester, heterocyclic amides, and phenolic compounds. The proposed mechanisms of those metabolites on inducing antifungal activity were comprehensively studied. We found that the n-hexane fraction was the solely fraction to produce the silver nanoparticles. Scanning electron images presented the aggregation and evenly distribution of spherical silver nanoparticles. The XRD exhibited the crystallization of the bio-organic synthetic phase based on the specific spectrum of 2-theta at 38.9 degree with miller index [1,1,1]. The particle size analyzer also confirmed the nanoscale of synthesized materials as in the average size of 92.1 nm (Z) and 0.406 (PI). Antifungal effects were examined by disc diffusion method upon each fraction with varying concentrations of 25%, 50%, 75%, and 100% (w/w) against C. albicans. ANOVA analysis showed no significant difference among all fractions tested (p > 0.25). The antifungal activity was categorized as a moderate effect with the mean of inhibition zone ranging from 6.1 to 6.8 mm. However, the potential of papaya seed extract is relatively better than the papaya leaves extract, as previously reported. We suggest further studies on the molecular docking of the secondary metabolites against nanoparticle, and specific biomolecular analysis according to the mechanism of action.

• Cracking of n-paraffins of varied carbon chain length was carried out in a fixed bed reactor using H-ZSM-5 catalyst. • Design of experiments was used to study the effect of key variables on ethylene and propylene yield from n-hexane cracking. • Quadratic model equations were proposed to predict the yield of ethylene (E), propylene (P) and total E+P yield. • Optimization study showed maximum 94.7% conversion and 46.1 wt.% yield of E+P at optimized reaction conditions. Catalytic cracking of n-paraffins of varied carbon chain length (C 6 -C 11) to represent light naphtha and gasoline was studied using extrudates of H-ZSM-5 (zeolite: binder = 70: 30) as a catalyst in a fixed bed reactor. Optimization of ethylene and propylene yields using model-based design of experiments (DOE) was carried out for n-hexane cracking by varying the temperature (550–650℃), weight hourly space velocity (3.3–9.9 h−1) and carrier gas (N 2) flowrates (3–10 L/h). These variables showed significant effect on the conversion of n-hexane and yield of ethylene and propylene under studied reaction conditions. The Box-Behnken design coupled with response surface methodology was used to determine the effect of reaction temperature, WHSV and N 2 flow rate on the yield of ethylene and propylene. Empirical models were constructed for the response variables namely n-hexane conversion, ethylene (E) yield, propylene (P) yield and total ethylene and propylene (E+P) yield. Main effect plot showed that the average yield of ethylene and propylene increased with increase in reaction temperature and decreased with increase in WHSV. The optimization study of multiple responses showed maximum 94.7% conversion of n-hexane and 46.1 wt% yield of ethylene and propylene at 650℃ catalyst bed temperature, 3.3 h−1 WHSV and 8.3 L/h N 2 flow rate. The model predicted ethylene and propylene yields matched closely with experimental data for catalytic cracking of naphtha feed at 550 and 650℃ cracking temperature. [ABSTRACT FROM AUTHOR]

• Solent effect of different type of solvents were fully evaluated. • The most evident impact to solvent effect is the comparative retention of the solvent in RPLC regarding the separated components. • Extreme tolerance of n -hexane up to 1/4 of the column bed volume. • A flexible coupling of NPLC and RPLC method was established by using n -hexane based NPLC mobile system. Reversed-phase liquid chromatography (RPLC) represents an effective separation method, and is widely employed as the second dimension in most 2D-LC systems. Nevertheless, the solvent effect of the eluent from the first dimension on RPLC presents a challenge to the online coupling of RPLC with other separation modes, particularly normal phase liquid chromatography (NPLC). To address this issue, a comprehensive understanding of the solvent effect is essential. Following a comprehensive investigation into the influence of diverse solvents on RPLC separations, it was observed that alkane solvents, such as n -hexane, exhibited a pronounced tendency to be retained during RPLC separations. Such solvents do not affect the analysis of samples with weaker retention abilities than themselves, even when a large injection volume is used. The solvent effect was thus reduced by employing n -hexane-based solvent dilution. Leveraging the markedly enhanced solvent tolerance and extensive injection volume in RPLC, a versatile integration of the NPLC and RPLC was devised, necessitating merely a purge pump and a 10 port 2 position valve in conjunction with two sample loops. The novel 2D-LC system was then deployed for the analysis of propolis, a naturally occurring complex sample, and demonstrated remarkable separation efficiency. [ABSTRACT FROM AUTHOR]

• Studied thermophysical properties of some n -hexane + hydrocarbons mixtures. • Densities were modelled with PC-SAFT EoS, and sound speeds were predicted with SCFT and Nomoto's relation. • The density, sound speed, isentropic compressibility, and isobaric expansivity data were correlated with the Jouyban-Acree model. • Excess properties, derived from density and sound speed data, were correlated with the Redlich-Kister equation. • The results are discussed in terms of intermolecular interactions and structural effects between components. The current work reports densities and sound speeds, and related thermodynamic excess properties, namely excess molar volumes and excess isentropic compressibilities, measured at temperatures from (293.15 to 323.15) K and under atmospheric pressure conditions for binary mixtures of n -hexane with benzene, toluene, ethylbenzene, o -xylene, m -xylene, and p -xylene. Redlich-Kister polynomial correlated the thermodynamic excess properties to test the quality of experimental data. Excess properties contributed to understanding molecular interactions between involved molecules and the peculiarities of their packing in the mixture. The Jouyban-Acree model was used to correlate the mixtures' experimental densities, sound speeds, and their related derived properties, namely isobaric thermal expansivities and isentropic compressibilities. The average absolute percentage deviation of the correlated values from the experimental ones was better than 0.036 %, 0.058 %, 0.040 %, and 0.146 % for density, sound speed, isobaric thermal expansivity, and isentropic compressibility, respectively, attesting to the robustness of the Jouyban-Acree correlations. Additionally, the Perturbed Chain Statistical Associating Fluid Theory Equation of State modeled the densities of the current mixtures. Schaaff's Collision Factor Theory and Nomoto's relation were compared for their ability to model the sound speeds of the mixtures. The efficacy of these models was tested by computing the average absolute percentage deviations between experimental and computed values. The modeled densities are reasonably concordant with experimental data, with an overall deviation of 0.02 %. Notably, Nomoto's relation exhibited superior performance over Schaaff's theory in modeling sound speeds of current mixtures, with an overall deviation of 0.33 %. The current findings underline the efficacy and versatility of the used models for thermodynamic modeling in systems of varying complexity. [ABSTRACT FROM AUTHOR]

Biodegradation of hydrophobic volatile organic compounds (VOCs) such as n -hexane is limited by their poor accessibility. Constructing fungal-bacterial degradation alliances is an effective approach, but the role of those fungi without the capability to degrade VOCs may have been overlooked. In this study, a non- n -hexane-degrading fungus, Fusarium keratoplasticum FK, was utilized to enhance n -hexane degradation by the bacterium Mycobacterium neworleansense WCJ. It was shown that strain WCJ removed 64.84% of n -hexane (at a concentration of 648.20 mg L−1) over 3 d, and 84.04% after introducing strain FK. Microbial growth kinetic studies revealed that the growth of strain WCJ was also promoted. Through a stepwise adsorption-degradation experiment combined with qPCR technology, it was found that the strain WCJ could utilize the n -hexane pre-adsorbed by strain FK, with an increase in copy number from 108.2662 to 108.7731. Therefore, the non-degrading fungi can improved the accessibility of n -hexane by providing n-hexane adsorbed by the mycelium to the degrading bacteria. In addition, the adsorption tests and characterization of the fungal samples before and after Soxhlet extraction indicated that the adsorption of n -hexane on strain FK conformed to Lagergren's pseudo-second-order kinetics and Freundlich adsorption isotherms, and was correlated with the presence of lipids and nonpolar groups. This study emphasizes the potential role of non-degrading fungi in bioremediation and proposes a viable strategy to enhance the bacterial degradation of hydrophobic VOCs. [Display omitted] • The introduction of strain FK increased the n -hexane removal to 84.04%. • The k value of strain WCJ was promoted by strain FK from 0.0395 to 0.1681 h−1. • Adsorption of VOCs by fungi through hyphae were confirmed by IFM and kinetics. • Bacterial degradation of the adsorbed n -hexane was indirectly proven by qPCR. • Lipids and nonpolar groups of fungi were found to contribute to the adsorption. [ABSTRACT FROM AUTHOR]

This article presents the results of an assessment of the combustion process of blends of n-hexane and canola oil. Tests were conducted for pure canola oil and its blends with n-hexane, with a max. n-hexane content of 20% by volume. The tests were carried out using the constant volume combustion chamber (CVCC) method as well as a diesel engine. For comparison purposes, the results for typical diesel fuel are also presented. Tests on the self-ignition properties of the n-hexane–canola oil blend, conducted in a CVCC according to the normative method for diesel fuel, showed little effect on the combustion process. However, previous tests conducted on a diesel engine of a passenger car showed a favorable effect of the n-hexane addition to canola oil on the combustion process in the engine, the performance and environmental parameters obtained. This shows that for some fuels, the evaluation of self-ignition and combustion properties in a constant volume combustion chamber, under conditions corresponding to diesel fuel tests, is not sufficient. The findings of this research may be beneficial in optimizing the diesel engine combustion systems fueled by renewable fuels. As the results of the tests have shown, the standardized method for determining the combustion process of the CVCC method does not always fully reflect the results obtained in engine tests. The results obtained by the CVCC method can be successfully used when comparing fuels, but when considering the selection of fuel for the engine, the results obtained in engine tests should be relied on first and foremost.

The article discusses the results of research on the use of canola oil and canola oil with the addition of n-hexane in a compression-ignition engine. An engine with a Common Rail injection system was tested in real traffic conditions on the road and on a chassis dynamometer. The tested fuels were fed to the engine by an additional fuel supply system. An analysis of the effect of the addition of n-hexane on the emission of the main components of toxic exhaust gases was carried out. The proposed solution may contribute to extending the service life of currently used compression ignition engines due to the improvement of the ecological properties of this type of drive sources.

Backgroundn-Hexane (NH) poisoning is a common occupational poisoning in the hardware and electronics industries. However, there is few research data on risk assessment of positions using NH in enclosed workshops. It is very important to assess the risk level of these positions and put forward effective measures and suggestions.MethodsThe information of selected companies and air samples were collected through on-site investigation, and data collation and sample testing were carried out according to the requirements of Chinese standards. The Control of Substances Hazardous to Health (COSHH) Essential, the EPA non-carcinogenic risk assessment model, the Singapore exposure index method and the Chinese semi-quantitative risk assessment models were used to assess the risks of NH.ResultsThe working hours of the exposure groups, printing groups and packing groups all exceeded 9 h per day, less than 30% of each similar exposure groups (SEG) was equipped with the local exhaust ventilation, and 11.1% of the cleaning group and 8.3% of the printing group had NH concentrations in the air that exceeded the Chinese occupational exposure limit (OEL). In the EPA non-carcinogenic risk assessment model, each SEG was evaluated at high risk. In the Chinese semi-quantitative risk assessment models, all of the work groups of exposure groups, 91.7% of the work groups of printing groups, 77.8% of the work groups of printing groups, and 57.1% of the work groups of printing groups were evaluated at unacceptable risk. More than 40.0% of the work groups of printing groups and cleaning groups and over 20.0% of the work groups of exposure groups and packing groups were evaluated at high risk in the Chinese semi-quantitative risk assessment models.ConclusionsThe Chinese exposure index method and the synthesis index method may have a stronger practicability. Some work groups that use NH in air-conditioned enclosed workshops in China, especially the cleaning groups, are still in a high-risk state. It is necessary to increase protective measures and strengthen occupational hygiene management to reduce risks.

In this work hydrogen-free processing (in the absence of hydrogen) and hydrotreating of n-hexane and straight-run petrol fraction on the catalysts samples “C-1” (La-ZSM-Al2O3) and “C-2” (Ni-Mo-La-P-ZSM-Al2O3) were studied. “C-2” catalyst has high activity in both studied processes. The conversion of n-hexane during hydrogen-free processing on the “C-2” catalyst in the range of 350-500ºC increased from 58.8 to 90.7%; the octane rating of the final product in the temperature range of 350-500 ºC was within 55.1-87.9 according to the research method (RM), and from 61.4 to 84.9 according to the motor method (MM). The octane rating of hydrotreating products increases mainly due to an increase in the content of isoalkanes. The octane rating of the resulting gasoline is significantly higher than that of the original straight-run gasoline (73.1 (RM), 54.1 (MM)), and it reaches 92.1 (RM) and 81.7 (MM). The surface of the developed catalysts is within 201.10-252.20 m2/g of the catalyst. The catalysts have pores with d ≈ 1.5– 3.65 nm. The highest concentration of acid sites with medium binding energy is typical for the “C-2” catalyst and determines its high hydroisomerizing activity in the processes of hydrotreating of n-hexane and gasoline fraction. Thus, multifunctional modified zeolite-containing catalysts for hydrotreating gasoline fractions have been developed, which make it possible to simultaneously carry out the processes of hydrotreating, hydroisomerization, and hydrocracking in one stage, as well as to obtain environmentally friendly high-octane gasoline. [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. [ABSTRACT FROM AUTHOR]

The chemical composition of the essential oil and n-hexane extract from Syzygium hemilamprum leaves was first performed. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the essential oil was predominantly composed of monoterpene hydrocarbons (71.5 %) and oxygenated derivatives (20.2 %), with β-pinene (31.5 %), limonene (19.4 %), α-pinene (12.3 %), and α-terpineol (7.4 %) being the principal constituents. The n-hexane extract contained monoterpene hydrocarbons (42.2 %) and non-terpenic compounds (34.0 %), with β-pinene (32.8 %) and n-hexadecane (10.2 %) as the major components. Antimicrobial and mosquito larvicidal assays demonstrated that both samples exhibited antimicrobial activity against Staphylococcus aureus (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Saccharomyces cerevisiae (yeast), with a minimum inhibitory concentration (MIC) of 128 μg/mL for all tested organisms. Both samples also showed significant mosquito larvicidal activity against Aedes aegypti and Culex quinquefasciatus, with LC 50 and LC 90 values below 20 μg/mL at 24 and 48 hours post-treatment. Molecular docking studies suggested that limonene and α-terpineol could serve as potent inhibitors of mosquito odorant binding proteins. Additionally, an in silico analysis was performed to evaluate the physicochemical and ADMET (absorption, distribution, metabolism, and toxicity) properties of the major constituents of the essential oil., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

This research aims to develop a silver nanoparticle (AgNPs) using several plant extracts for antibacterial application. The papaya seed extract has been fractioned by n-hexane, ethyl acetate, water, and ethanol. The n-hexane fraction was the only fraction that succeeded in synthesizing AgNPs. The characterization methods showed AgNPs marked at 430 nm with UV-Vis and 1640 cm-1 with FTIR. SEM observed the aggregation of spherical AgNPs at the 200 nm scale. The particle size of 91.3 nm was measured with PSA that confirmed the nanoscale of the synthesized material. All fractions contained alkaloid compound, and ethyl acetate fraction showed a group of indole with specific wavenumber at 2623 cm-1, 1737 cm-1, and 1237 cm-1 representing N-H, C=O, C-N, respectively. All fractions at every concentration (25%, 50%, 75%, 100%) have been tested and showed the medium effect on bacterial growth inhibition. Among all fractions, the AgNPs n-hexane fraction has the highest bacterial effect, which was indicated by mean values of inhibition zone 7.2 mm against S.aureus, as well as 6.6 mm against E.coli. ANOVA analysis showed that AgNPs n-hexane fraction has a significant inhibition zone compared to other fractions against S.aureus (p=0.002), but not significant to E.coli (p=0.128). The insignificant results on E.coli because of gram-negative bacteria's biophysical characteristics, such as membrane cell wall and flagellin. This research emphasized that AgNPs could be synthesized via a green process of nucleation by using plant extract that effectively inhibits the growth of S.aureus and E.coli. Further studies on the mechanism of the antibacterial effect at the molecular level might be investigated soon.

Biji buah alpukat (Persea americana) merupakan sumber limbah biomassa yang dapat dimanfaatkan sebagai sumber energi alternatif. Pada bagian biji alpukat mengandung selulosa, hemiselulosa, lignin, lipid, protein. Tujuan dari penelitian ini adalah menganalisa pengaruh berat biji alpukat dan solvent n heksana terhadap persentase yield minyak biji alpukat dan mengetahui karakteristik persentase FFA, kadar air, impurities, bilangan iodine, bilangan peroksida dan bilangan saponifikasi minyak dari biji alpukat yang dihasilkan dari proses ekstraksi. Metode penelitian ini dilakukan dengan mengestraksi biji alpukat menggunakan soklet ekstraksi dan solvent n-heksana dengan temperatur 70 °C, tekanan 1 atm dan waktu 240, 360, 480 menit. Hasil penelitian menunjukan variabel berat biji alpukat, volume pelarut dan lamanya waktu ekstraksi mempengaruhi peningkatan jumlah minyak biji alpukat yang dihasilkan. Dari penelitian yang dilakukan yield tertinggi dihasilkan dari ekstraksi biji alpukat adalah sebesar 30,15 % pada variabel massa biji 60 gram, waktu ekstraksi 480 menit dan volume pelarut 300 ml. Hasil analisa kualitas minyak biji alpukat terhadap persentase FFA, kadar air, impurities, bilangan iodine, bilangan peroksida dan bilangan saponifikasi telah memenuhi standar SNI. Namun pada analisa impurities pada proses ekstraksi biji alpukat 60 gram dengan volume n-heksana 300 ml melebihi standar SNI. Hasil uji Gas Chromatography menunjukkan bahwa minyak biji alpukat mengandung senyawa asam lemak dan konsentrasi oleic acid adalah yang tertinggi dibandingkan unsur kimia yang lain. Avocado seeds (Persea americana) are biomass waste that can be used as an alternative source of energy. Avocado seeds contain cellulose, hemicellulose, lignin, lipids, and protein. This research studied the effects of avocado seed weight and n-hexane solvent on the percentage of avocado seed oil yield and determined the characteristics of the FFA percentage, water content, impurities, numbers of iodine, peroxide and oil saponification of obtained from the extraction process. Avocado seeds were extracted using an extraction sox and n-hexane solvent at 70 °C, 1 atm and time 240, 360, 480 minutes. The results showed that avocado seed weight, solvent volume and extraction time affected the amount of avocado seed oil yield. The highest yield was 30.15% obtained from seed mass of 60 grams with 480 minute extraction time and 300 ml solvent. The results also showed that the quality of avocado seed oil in relation to FFA percentage, moisture content, impurities, iodine number, peroxide number and saponification number have fulfilled the SNI standards. However, the analysis of impurities in the extraction process of 60 grams of avocado seeds with a volume 300 ml of n-hexanes exceeds the SNI standard. The Gas Chromatography test showed that vocado seed oil contained fatty acid compounds with highest concentration of oleic acid among other chemical elements.

In the present study, highly acidic sulfated zirconia catalysts were prepared using a facile sol–gel method. A superior catalytic activity of sulfated zirconia nanomaterial for isomerization of n-hexane was observed when loaded with tungstophosphoric acid (WPA). The catalysts were fully characterized using SEM, powder XRD (PXRD), FTIR, and NH3-TPD techniques. The surface characteristics of materials were analysed using N2-adsorption isotherm (at − 196 °C). The results indicate that surface area and pore volume of zirconia were in the ranges of 93–150 m2/g and 0.08–0.31 cm3/g. Impregnation of WPA (loading of 10 to 60 wt%) on to the sulfated zirconia were conducted using the wet incipient method. The acidity of zirconia improved in the range of 0.12–0.69 mmol/g after its modification using sulfuric acid and WPA. The PXRD results revealed a monoclinic phase for the synthesized material. A fixed bed micro reactor was utilized to study the catalytic activity of the material towards isomerization of n-hexane in the temperature range of 150–250 °C, and the maximum conversion was obtained at 225 °C. [ABSTRACT FROM AUTHOR]

The article discusses the results of research on the use of canola oil and canola oil with the addition of n-hexane in a compression-ignition engine. An engine with a Common Rail injection system was tested in real traffic conditions on the road and on a chassis dynamometer. The tested fuels were fed to the engine by an additional fuel supply system. An analysis of the effect of the addition of n-hexane on the emission of the main components of toxic exhaust gases was carried out. The proposed solution may contribute to extending the service life of currently used compression ignition engines due to the improvement of the ecological properties of this type of drive sources. [ABSTRACT FROM AUTHOR]

Novel B-doped NiP/Hβ (Hβ is the hydrogen proton exchanged β molecular sieve) catalysts were prepared and the catalytic performance for n-C6 (n-hexane) isomerization was studied firstly. It was found that the mole ratio of Ni, P and B in preparing B-doped NiP had important influence on the crystalline structure and catalytic activity of NiPB. When the mole ratio of Ni, P and B was 1:1:1, the prepared NiPB was amorphous and NiPB/Hβ had the best catalytic activity with the conversion rate of n-C6, the yield and selectivity of isoparaffins being 79.93%, 78.34% and 98.01% respectively. It was also showed that the preparation conditions of catalyst including NiPB loading on carrier and calcination temperatures were the key factors for the catalytic performance of NiPB/Hβ. In controlled experiments, ammonia poisoned acid sites on the catalyst led to the markedly reducing of catalytic performance and metal sites were essentially for the dehydrogenation-hydrogenation reaction. The isomerization of n-C6 catalyzed by NiPB/Hβ is a continuous alternating process of acid catalysis and metal catalysis, and the matching of acid sites and metal sites is of importance. [ABSTRACT FROM AUTHOR]

Propolis is one of the natural products produced by kelulut bees and is still not widely used. The type of stingless bee that is the prima donna in the community is Heterotrigona itama. This study aims to determine the phytochemical content of the n-hexane fraction of Heterotrigona itama bee propolis collected from Kutai Kartanegara, East Kalimantan. The n-hexane fraction was obtained from the methanol extract of H. itama propolis by the liquid-liquid partition method. After obtaining the n-hexane fraction, the research continued with a qualitative phytochemical test to identify the compound and determine total phenolic. Antibacterial activity was determined by the agar well diffusion method with a serial concentration in Escherichia coli bacteria. Qualitative phytochemical analysis in the form of color changes showed that the n-hexane fraction of H. itama propolis contained flavonoids, alkaloids, saponins, and tannins. Based on the results, the total phenolic content of the n-hexane fraction sample was 490 mgGAE/100 g. It caused the n-hexane fraction to have lower phenolic content than the methanol extract (792 mg GAE100 g). Furthermore, this result indicated that the non-polar fraction was not substantial enough to extracted phenolic compounds. It correlated to the antibacterial activity of the n-hexane fraction, which was very weak (2 mm ± 1.5) at 200µg/mL concentration.

A high number of infections from year to year require infectious diseases to get serious attention. The antimicrobial compound exploration must be continued to anticipate the development of infectious diseases. The purpose of this study was to find out in vitro antimicrobial activity of n-hexane, ethyl acetate, and ethanol fractions of Piper betle green leaves against S. aureus, and profiles of secondary metabolite compounds contained in these three extracts. The antimicrobial activity test was carried out by disk diffusion test of the fraction of n-hexane, ethyl acetate, and ethanol at a concentration of 6,25, 12,5, and 18,75 µg/disk. Detection of secondary metabolite content was done by the Thin Layer Chromatography method with stain-view reagents. The highest antimicrobial activity was found in the ethyl acetate fraction and was significantly different from the activity in the ethanol and n-hexane fractions. However, the antibacterial activity of all fractions was lower compared to the positive control of amoxiclav 30µg/disk. The phytochemical screening results of secondary metabolites of each fraction were shown that the n-hexane fraction contained alkaloids, terpenoids, flavonoids, polyphenols, and anthraquinone; the ethyl acetate fraction contained terpenoids, polyphenols, and anthraquinone; while the ethanol fraction contained alkaloids, terpenoids, polyphenols, and anthraquinone. Based on the test results, it is concluded that all fractions of Piper betle leaf extract had high antimicrobial activity; meanwhile, the ethyl acetate fraction had the highest activities among others. Each fraction was proven to have a different composition of secondary metabolites.

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.

• The dynamic viscosity, interfacial tension and diffusion coefficient data of n -hexane/cyclohexane/2-methylpentane + CO 2 system were obtained using dynamic light scattering method. • The experimental data was correlated by empirical equations. • The influence of different molecular structures on their thermophysical properties was analyzed using molecular simulations. In this work, n -hexane, cyclohexane and 2-methylpentane were selected to represent linear-alkane, cycloalkane and branched-alkane, respectively. Based on the dynamic light method (DLS), the viscosity, interfacial tension and diffusion coefficient of n -hexane/CO 2 , cyclohexane/CO 2 and 2-methylpentane/CO 2 systems under saturation condition were measured in order to explore the change trend of thermophysical properties of the systems with the same carbon atom number but different molecular structures. The experiments were conducted at the temperatures of 303, 343 and 383 K and at pressures up to 5.64 MPa. The expanded uncertainties（ k = 2）of dynamic viscosity, interfacial tension and diffusion coefficient were 3 %, 3 % and 4.4 % respectively. The experimental results show that n -hexane and 2-methylpentane with similar molecular structure have more similar value of the properties. The effects of different alkane structures on system viscosity, interfacial tension, and diffusion coefficient were explained at the molecular level through radial distribution function, interface thickness, and CO 2 coordination number. At 303.15 K and 4 MPa, the peak radial distribution function of CO 2 /cyclohexane is 1.845, which is greater than that of CO 2 /n-hexane and CO 2 /2-methylpentane molecules. It has been proven that the arrangement of CO 2 /cyclohexane is more orderly, resulting in higher viscosity and lower diffusion coefficient of the system. The interface thickness of CO 2 /cyclohexane is 6.13 nm, which is smaller than CO 2 / n -hexane (7.53 nm) and CO 2 /2-methylpentane (6.3 nm). The smaller the interface thickness, the more compact the structure, the stronger the intermolecular forces, and the greater the interfacial tension. At 303.15 K and 2 MPa, the number of CO 2 coordination sites within 1 nm around liquid phase alkanes is 3.96, which is smaller than 4.78 for cyclohexane and 6.62 for 2-methylpentane. Prove that the coordination number is directly proportional to the diffusion coefficient and inversely proportional to viscosity and interfacial tension. [ABSTRACT FROM AUTHOR]

BACKGROUND As an important index of land environmental quality, the content of petroleum substances determines the use of the land. It also reflects the effect of reclamation and treatment of polluted land to a large extent. The determination methods of petroleum substances in soil samples include gas chromatography, infrared spectrometry, and ultraviolet method. The gas chromatography mainly analyzes saturated alkanes in the samples. The infrared spectrometry identifies the petroleum substances in the samples by measuring the characteristic absorption values under different wave numbers. However, tetrachloroethene used as the solvent is harmful to the environment. Moreover, the pretreatment efficiency is low and the detection limit is high. OBJECTIVES To develop a method with high pre-treatment efficiency, low detection limit and good reproducibility. METHODS Petroleum substances in the reclaimed land samples have low content, most of the components are difficult to volatilize, the structure is complex, and the matrix interference is large. Using n-hexane as the solvent and accelerated solvent extraction (ASE) as the pretreatment method, the petroleum substances in the samples were determined by fluorescence photometer. RESULTS Using the petroleum standard material for marine environmental monitoring as the calibration material to prepare a working curve, the linear correlation coefficient was 0.9997, the detection limit was 0.40mg/kg, precision was 1.10% to 8.76% and the recovery was 89.0% to 95.7%. The results of actual samples were consistent with those of the currently valid infrared spectrophotometry method HJ 1051-2019, and the measurement results of high-content samples were higher than those of the infrared method. CONCLUSIONS The pretreatment method ASE has high automation and high extraction efficiency. It can be used to increase the precision by 11.5%-67.3%. For samples with a relatively complex structure of petroleum components and that are difficult to extract, the detection limit of this method is lower than that of the infrared method (4mg/kg).

The zeolites ZSM-5 with different Si/Al ratios were modified with a buffer solution of HF and NH4F. This acidic treatment led to the obtaining of a material with secondary mesoporosity. The deposition of cobalt from an aqueous solution of cobalt acetate on the surface of treated samples generates the formation of different cobalt oxide species: bulk-like Co3O4 phases strongly interacting with the support, Co2+ in ion exchange positions (γ and β sites) and silicate-like phases. The mechanism of cobalt silicate phase formation is proposed here and includes a replacement of silanol groups and the bridging hydrogens by Co and the inclusion of the Co atoms in tetrahedral framework positions. The catalysts, obtained through use of the treated ZSM-5, exhibit higher activity in the reactions of propane, and n-hexane completes oxidation compared with the catalyst samples containing un-treated zeolite. Both the finer dispersion of metal oxide particles on the hierarchical sample and the presence of secondary mesoporosity improve the effectiveness of the active phase utilization via access to larger number of active sites.

Addressing contemporary environmental and health concerns requires reducing pollutant emissions and converting them into less harmful or valuable compounds within the framework of the circular economy. Guefoam materials offer a promising solution by enabling the capture and pre-concentration of volatile organic compounds (VOCs), while facilitating the structuring of active phases for heterogeneous catalytic conversions. This study demonstrates the benefits of merging two newly designed electromagnetic induction-assisted ceramic matrix Guefoams into a portable integrated unit, synergizing the pre-concentration and chemical transformation of n-hexane, a VOC with special challenges. One Guefoam serves as an adsorbent, whereas the other plays a catalytic role. These Guefoams host guest phases, which consist of composite materials combining a steel core with magneto-inductive properties encased in a highly porous carbonaceous layer. This carbonaceous material undertakes a dual mission: adsorbing n-hexane from a nitrogen stream within the adsorptive Guefoam and, upon phosphorus doping in the catalytic Guefoam, orchestrating the metal-free selective dehydroaromatization of n-hexane into benzene. The design and integration of these novel Guefoam materials into a unified functional entity prove highly effective in pre-concentrating (enrichment factors up to 275) and catalyzing n-hexane with up to 84 % conversion and 94 % benzene selectivity while remaining energy-efficient and environmentally sustainable. [Display omitted] • Guefoams were fabricated using cement and adsorptive/magneto-inductive guest phases. • Guest phases consisted of steel spheres coated with (functionalized) carbon material. • A guefoam-containing portable device captured and converted n-hexane into benzene. • High selectivity (94 %) and excellent catalytic conversion (84 %) were achieved. • Environmental sustainability is proven given high energy efficiency (savings > 85 %). [ABSTRACT FROM AUTHOR]

Naphtha cracking is the most common process for producing light olefins such as ethylene, propylene, and butene. This process consumes enormous amounts of energy, so decreasing the energy consumption and operating temperature is an urgent issue. To decrease the reaction temperature for naphtha cracking, we focused on the metal-assisted cracking reaction, in which paraffin is first dehydrogenated into the corresponding olefin on a metal catalyst, and the produced olefin is then decomposed into light olefins. To effectively realize metal-assisted cracking, we considered metal-encapsulated zeolite catalysts to be useful. In metal-encapsulated zeolite catalysts, the dehydrogenation reaction proceeds inside the zeolite particles, and the dehydrogenated intermediates can access the solid-acid sites frequently. In this study, Rh nanoparticle encapsulated ZSM-5 catalysts (Rh@ZSM-5) were employed for the metal-assisted cracking of n -hexane. Rh@ZSM-5 exhibited significantly high activity for n -hexane cracking below 450 °C owing to the metal encapsulation structure and close proximity between the metal and solid-acid sites. Furthermore, the effects of reaction conditions, reaction temperature, amounts of metal and solid-acid sites, and contact time on metal-assisted n -hexane cracking over the Rh@ZSM-5 catalysts were investigated. The highest light-olefin yield of 38.6 carbon mol% was achieved by the conversion of n -hexane over Rh@ZSM-5 using 0.3 wt% Rh loading, an Si/Al ratio of 100, temperature of 450 °C, reaction time of 0.5 h, and W / F of 2 h. [Display omitted] • Low-temperature cracking of n -hexane was performed on Rh-loaded ZSM-5 catalysts. • n -Hexane was dehydrogenated, and the dehydrogenated intermediate was cracked. • Encapsulation structure of metal in zeolite significantly improved activity. • Dehydrogenation of n -hexane over the metal was the rate-determining step. • Reaction temperature, amounts of active sites, and contact time were investigated. [ABSTRACT FROM AUTHOR]

This study delves into the adsorption behavior of both polar and non-polar molecules on silica surfaces, spanning a range from low coverage to full adsorption scenarios. Our results reveal that isopropanol exhibits a self-competitive adsorption mechanism on the surface. However, due to its thermodynamic stability, we anticipate fully covered pores under experimental conditions. In contrast, n-hexane demonstrates a substantial interaction with the hydrophilic substrate, displaying an enhanced adsorption effect whereby the adsorption gets stronger with an increasing number of molecules adhering to the pore's surface. As a consequence, we predict a complete coverage of the pores under experimental conditions, accompanied by a discernible reduction in the mobility of these attached molecules. This observation carries significance, as alkanes are typically employed as probing molecules for measuring the geometric tortuosity of silica pores, assuming a reflective surface. Caution is advised, particularly for pores with thin diameters, in the order of a few molecular sizes. [Display omitted] • Studied adsorption of polar and non-polar molecules on silica surfaces at different coverages. • Isopropanol's adsorption is anti-cooperative but is expected to fully cover pores due to stability. • N-hexane interacts notably with hydrophilic substrates, showing stronger adsorption with more molecules. • The importance of using alkanes to measure geometric tortuosity of silica pores, especially thin ones is highlighted. [ABSTRACT FROM AUTHOR]

• Choline-based DESs was prepared for the separation of MeOH/IPA-NHA. • The extraction performance of three kinds of DESs was compared by LLE experiment. • MD simulation was used to explore the mechanism of extraction process. • The extraction effects of DESs on different low-carbon alcohols were compared. Deep eutectic solvent (DES) has been used in chemical and pharmaceutical fields on account of their characteristics of high capacity, low toxicity and low price. Low-carbon alcohol, as a fuel additive, has the characteristics of high energy density, low corrosiveness, and high added value. Therefore, extracting low-carbon alcohols from azeotropes as fuel additives can improve the combustion efficiency of the fuel. To realize the separation of low-carbon alcohols-alkanes azeotropes, three choline-based DESs were synthesized in this work. The liquid–liquid equilibrium data of n -hexane-methanol/isopropyl alcohol-DESs were determined under 298.15 K and 1 atm. The separation efficiency of DESs for two azeotropes was compared through calculating the distribution coefficient and selectivity of DESs for low-carbon alcohols. To further explore the reasons for the different separation effects of DESs on two azeotropes, the internal mechanism of DESs extraction of two low-carbon alcohols was studied by molecular dynamics method. Based on the results of molecular dynamics simulation, the kinetic analysis results such as the interaction energies, spatial distribution function between DESs and azeotropes in the separation process were obtained. The results showed that the separation effect of three DESs on methanol- n -hexane azeotrope was better than that of isopropyl alcohol- n -hexane azeotrope, the DES1 composed of choline chloride and ethylene glycol in the molar ratio of 1:2 had the highest extraction efficiency for two low-carbon alcohols among the three DESs, and Cl- made the greatest contribution in the separation process. [ABSTRACT FROM AUTHOR]

Health risks to humans after „fume and smell events", short-term incidents on aircrafts that are accompanied by unpleasant odour or visible smoke, remain a subject of controversy. We assessed exposure to volatile organic compounds (VOC) and organophosphorus compounds (OPC) by biomonitoring in 375 aircrew members after self-reported "fume and smell events" and in 88 persons of the general population. A total of 20 parameters were analysed in blood and urine by gas chromatography and mass spectrometry. Median levels of acetone in blood and urine and 2-propanol in blood were elevated in aircrews compared to controls (p < 0.0001). Additionally, elevated peak exposures, best estimated by the 95th percentiles, were observed in aircrews for n -heptane and n -octane in blood, and acetone, 2,5-hexanedione and o -cresol in urine. Only the maximum observed levels of 2,5-hexandione in urine (768 μg/L) and toluene in blood (77 μg/L) in aircrew members were higher than the current biological exposure indices (BEI® levels) (500 and 20 μg/L, respectively) of the American Conference of Governmental Industrial Hygienists (US-ACGIH) for workers occupationally exposed to n -hexane and toluene, two well-accepted human neurotoxicants. Low-level exposures to n -hexane and toluene could be also observed in controls. The majority of OPC parameters in urine, including those of neurotoxic ortho -isomers of tricresylphosphate, were below the limit of quantitation in both aircrews and controls. Our comparative VOC and OPC analyses in biological samples of a large number of aircrew members and controls suggest that exposures are similar in both groups and generally low. [ABSTRACT FROM AUTHOR]

In this study, a Dielectric-Barrier Discharge (DBD) plasma reactor was used for the degradation of n -hexane from an air stream. a Central Composite Design (CCD) based Response Surface Methodology (RSM), (CCD-RSM) was utilized to explore the effects of experimental parameters including discharge voltage, initial concentration, gas flow rate, relative humidity and their interactions on the reactor performance. The proposed optimization model showed a satisfactory correlation between the predicted and actual results. According to the results, discharge voltage was the most significant parameter affecting the removal efficiency, CO 2 selectivity and the level of O 3 and NO x formation, whereas energy yield was mainly influenced by gas flow rate and initial concentration. At optimized conditions (discharge voltage of 8.5 kV, inlet concentration of 94.3 ppm, relative humidity of 55 % and gas flow rate of 733.16 ml/min with combined desirability of 0.921), removal efficiency of 92.57 %, CO 2 selectivity of 58.87 %, energy efficiency of 0.25 g/kWh, O 3 formation of 140.88 mg/m3 and NO x formation of 122.46 ppm were obtained. Water vapour significantly increased the removal efficiency and CO 2 selectivity as well as reduced O 3 and NO x. The results revealed that the CCD-RSM provided the optimum process parameters for the Non-Thermal Plasma (NTP) system. [Display omitted] • A dielectric-barrier discharge (DBD) plasma reactor was used for the degradation of n -hexane from an air stream. • Response surface methodology (RSM) and central composite design (CCD) were used to create the optimization procedure. • The n- hexane removal efficiency and the CO 2 selectivity increased with discharge voltage and relative humidity. • Energy yield was mainly influenced by gas flow rate and initial concentration. • The water vapour decreased the formation of O 3 and NO x. [ABSTRACT FROM AUTHOR]

The main aim of this study was to explore the role of light microscopy in the identification of microalgae as a source of study. Three microalgal species (Nostoc, Anabaena, and Volvox) were identified by light. In this study, different parameters of the oil extraction process from algae biomass were studied. The samples of Nostoc, Anabaena, and Volvox were collected from the freshwater bodies in Lahore, and the samples were identified by light microscopy. Pretreatment of algae was done which includes harvesting, drying, and grinding. The sun drying of sample was done. Solvent extraction was done for the extraction of oil from algal cells. Solvent n‐hexane and diethyl ether were used alone as well as in combination. Effects of n‐hexane to oil ratio, size of algal biomass, and contact time on the percentage yield of extracted oil were studied and analyzed. It was concluded that maximum amount of oil was extracted from algae by using a greater ratio of solvent to algal biomass, maximum contact time, and smaller algal biomass size. The extracted oil yield was satisfactory, demonstrating the potential of microalgae for biodiesel production. It was discovered that if algal oil is subjected to transesterification, it can be turned into biodiesel, and light microscopy can be used to assess anatomical characteristics. However, more research will be required for transesterification. [ABSTRACT FROM AUTHOR]

Momordica charantia (Curcubitaceae) commonly called bitter lemon is an edible slender, tendril and climbing annual vine that is indigenous to the tropical and subtropical regions of the world. It is used in ethno-medicine to treat febrile convulsion in children. The n-hexane, ethyl acetate, methanol and aqueous extracts of Momordica charantia were subjected to phytochemical analysis, and evaluated for anticonvulsant activities using the maximal electroshock (MES) and the pentylenetetrazol (PTZ)-induced seizures in mice at the graded doses of 25, 50 and 100 mg/kg. The MES active nhexane extract was subjected to solvent/solvent Vacuum Liquid Chromatography (VLC) fractionation and fractions obtained were evaluated for anticonvulsant activity. The active VLC fractions were further fractionated using Column Chromatography (CC) to obtain anticonvulsant active fractions which were analyzed with Gas Chromatography-Mass Spectrometry (GC-MS). Results of the phytochemical analysis of the four extracts showed the presence of alkaloids, tannins, saponins, phenols, flavonoids, lipids, amino acids and terpenoids. The n-hexane extract was selectively active against the MES-induced seizure, and provided 65, 85 and 90% protection at the doses of 25, 50 and 100mg/kg respectively. The active VLC fractions provided 85 and 100% protection at the doses of 6.25 and 12.5mg/kg, while the CC fractions provided 90 and 100% protection at the doses of 1.5625 and 6.25m/kg respectively. The GC-MS analyses of the CC fractions revealed the presence of linoleic acid (LA), alpha linolenic acid (ALA), C-16 and C-18 medium-chain fatty acids as the major components, which have previously been shown to have antiseizure activity. With the results of the experiments, it is concluded that the n-hexane extract and its VLC and column fractions selectively protected albino mice against the maximal electroshock-induced seizures and had no activity against the pentylenetrazol-induced seizures. The antiseizure activity of the active n-Hexane extract could be due to the presence of linoleic acid, alpha linolenic acid, the C-16 and C-18 medium-chain fatty acids. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate an n-hexane extract of Artemisia cina (Acn-h) as a natural anthelmintic treatment for periparturient goats naturally infected with the nematodes Haemonchus contortus and Teladorsagia circumcincta. A total of 200 periparturient Alpine and Nubian goats were used. Deworming criteria were based on the following parameters: fecal egg account (epg), ocular mucosa color (OMC), and body condition (BC). A previous analysis using coprocultures of the flock revealed the presence of H. contortus (80%) and T. circumcincta (20%). The Acn-h contained two new compounds identified by mass spectrometry data as isoguaiacin and norisoguaiacin at 284.14 and 315 m/z. The lethal effects of Acn-h at 0.5, 1, 2, and 4 mg/mL on H. contortus adult stages were 31.6, 66.5, 81.3, and 86.9%, respectively (p < 0.05), showing similar efficacy at 2 and 4 mg/mL with albendazole (positive control group). Then, two experimental groups, with 100 goats in peripartum in each, were distributed randomly and treated at day 0 as follows: group 1 = 4 mg/kg of Acn-h as single oral dose, and group 2 = control group, treated with water (as a placebo). The epg, OMC, and BC parameters were recorded at 0 (periparturient period), 7 (birth period), and 23 (postpartum) days and analyzed using a completely randomized design with Duncan’s test for comparison of means and analysis of variance. The following epg reductions were recorded in the Acn-h-treated group as follows: 20.1 ± 34.4 and 31.7 ± 38.2% at days 7 and 23 compared to the control group. During the whole experiment, no significant differences in OMC or BC were observed in relation to the control group, excepting at day 23 (p < 0.05) for BC in the group treated with A. cina. Thus, Acn-h can be a useful natural alternative tool for the control of the nematodes H. contortus and T. circumcincta in periparturient goat flocks. [ABSTRACT FROM AUTHOR]

Olea ferruginea has been used to treat skin ailments, as well as kidney and ocular problems for a long time. The current study was designed with the aim of investigating and scientifically validating its widespread use. Chloroform, n-hexane, and ethyl acetate were used to assess the antibacterial, hemagglutination, and insecticidal properties of O. ferruginea roots. Escherichia coli, Micrococcus luteus, Klebsiella pneumoniae, and Pseudomonas aeruginosa were among the bacterial strains selected for assessing antibacterial activity. The results showed that ethyl-acetate (EtOAc) extract (56%) and chloroform (CHCl3) extract (56%) showed the widest zone of inhibition against K. pneumonia, while n-hexane extract (13.4%) had the lowest zone of inhibition against P. aeruginosa. All three extracts remained inactive against M. luteus. During hemagglutination activity, the CHCl3 and EtOAc extracts, when used at different concentrations, only agglutinated the AB-ve and O+ve blood groups, respectively, while the n-hexane extract strongly agglutinated the A-ve and B-ve blood groups at different concentrations. The plant extracts were also checked for insecticidal activity against Rhizopertha dominica. The results also revealed the high mortality rate of CHCl3 extract (70%) against R. dominica as compared to other extracts. The aforesaid activities suggest that the roots of O. ferruginea have excellent medicinal viability and contain a wide variety of agglutinins and lectins, as shown in this study. [ABSTRACT FROM AUTHOR]

Oil from neem and yellow oleander seeds were extracted using Soxhlet extractor with normal hexane as solvent and characterized using standard methods and their Physico chemical properties determined. The results revealed that the oil yields of neem and yellow oleander seeds are 38.80% and 49.69% respectively. Both oil samples contain high free fatty acid values, 8.77% for neem and 7.21% for yellow oleander. The characterization revealed the following results for neem seed oil; saponification value = 185.50 mg KOH/g, acid value = 17.54 mg KOH/g, iodine value = 58 mg I/100g, peroxide value = 7.95 mg/peroxide/kg, viscosity at 40 °C = 37.80 mm/s2, specific gravity = 0.87, and refractive index = 1.469 while saponification value = 196.30 mg KOH/g, acid value = 14.42 mg KOH/g, iodine value = 81 mg I/100g, peroxide value = 4.20 mg/peroxide/kg, viscosity at 40 °C = 31.40 mm/s2, specific gravity = 0.96, and refractive index = 1.467 for yellow oleander seed oil. The results of the experimental analyses carried out in this study indicate that neem and yellow oleander seeds are high-yielding and good sources of oil for commercial biodiesel production. Values obtained for physico chemical properties of the extracted oils fall within the acceptable limits for oils suitable for biodiesel production by international standards. High free fatty values obtained revealed that the oils must undergo acid esterification before transesterification to avoid the formation of soap.