Butyl Acetate Research Articles

Solvent screening for the extraction of aromatic aldehydes

The aromatic aldehydes vanillin, syringaldehyde, and p-hydroxybenzaldehyde find applicability in a broad field ranging from additives in food, cosmetics, and fragrances to precursors of electrochemically active substances used in organic redox flow batteries. These aldehydes can be obtained by wet oxidation of lignin a macromolecule present in woody biomass followed by the isolation via solvent extraction from the resulting acidic solutions.The present study investigates solvents grouped by esters, ethers, terpenes, and terpenoids, in addition to 1-octanol for their performance in extraction of the aromatic aldehydes vanillin, p-hydroxybenzaldehyde and syringaldehyde from an acidic aqueous solution. Solvent extractions are performed at 25 and 50 °C in double-walled tempered separation funnels. The overall extraction efficiency is determined by back-extractions performing a pH-swing at 25 °C. Aldehyde concentrations are measured by HPLC-UV. Karl-Fischer titration and total organic carbon measurements are used to account for the mutual solubility.The best-performing solvent in the case of aldehyde yields at low mutual solubility is given by the ester butyl acetate with extraction efficiencies of 96.53 % for p-hydroxybenzaldehyde, and > 95 % and > 93 % for vanillin and syringaldehyde, respectively. The highest overall extraction efficiency among all solvents suitable for alkaline back-extraction is achieved by cyclopentyl methyl ether with 94.73 % for p-hydroxybenzaldehyde, 94.04 % for vanillin and 87.91 % for syringaldehyde. The solvents geraniol, 1-octanol, ethyl acetate, and 2-methyl tetrahydrofuran show increased uptake of water with ethyl acetate, and 2-methyl tetrahydrofuran pointing out a high solvent loss with 9.82 vol% and 15.84 vol%, respectively. The terpene p-cymene showed preferable extraction of vanillin and syringaldehyde over p-hydroxybenzaldehyde with mutual solubility below 0.02 vol%, which makes it and interesting candidate for multistage solvent extraction.

Simulation analysis of hazardous chemicals released from the furniture plant using ALOHA software.

The manufacturing of wooden furniture is extensive in Thailand's east. Hazardous chemicals were used in the wooden furniture industry's manufacturing process. Hazardous substances released into the surrounding atmosphere appear to have an impact on the environment and individuals. The ALOHA model is frequently used to assess hazardous chemicals released into the environment; this simulation model is an effective tool for modeling chemical compounds and detecting chemical disasters. It has a tremendous potential for preventing mishaps in potentially hazardous or emergency situations. Acetone and butyl acetate were extracted from the hardwood furniture business to identify accidents such as leaking, spillage, and evaporation. It is described as a highly poisonous, combustible, and explosive material. Toxic accident releases have negative implications for the surrounding areas. The goal of this work was to examine each accident using ALOHA software, and the computation of acetone and butyl acetate accidents was shown in this study. This project provides critical data for the furniture plant's chemical emergency rescue strategy as well as recommendations for emergency evacuation site decision-making.

A Hydrothermal Synthesis Process of ZSM-5 Zeolite for VOCs Adsorption Using Desilication Solution

ZSM-5 zeolite is a kind of high-value-added porous aluminosilicate zeolite. The use of the coal gasification slag utilization process by-product desilication liquid as a silicon raw material to replace the current raw materials such as water glass will help reduce production costs and achieve high-value utilization of solid waste. ZSM-5 zeolites for volatile organic compounds (VOCs) adsorption were prepared by a one-step hydrothermal method using the desilication solution prepared from coal gasification slag as the main silicon source and sodium source. The effects of crystallization reaction time, the crystallization temperature, the Na2O/SiO2 molar ratio, and the SiO2/Al2O3 molar ratio on the relative crystallinity and the specific surface area of the ZSM-5 zeolite were investigated and optimized. The optical reaction conditions were as follows: a crystallization time of 12 h, a crystallization temperature of 170 °C, a Na2O/SiO2 molar ratio of 0.2, and a SiO2/Al2O3 molar ratio of 200. The optimal ZSM-5 zeolite synthesized is hexagonal, with regular grains, a relative crystallinity of 101.48%, a specific surface area of 337.48 m2·g−1, and a pore volume of 0.190 cm3·g−1. And the optimal ZSM-5 zeolite was composed of SiO2 content of 97.52 wt%, Al2O3 content of 1.58 wt%, Na2O content of 0.33 wt%, and SiO2/Al2O3 molar ratio of 104.93. Na2O/SiO2 molar ratio is 0.0033. The results of static adsorption experiments show that the static adsorption capacities of ZSM-5 zeolite for p-xylene, benzene, toluene, and butyl acetate were 118.85, 69.98, 68.74, and 95.85 mg·g−1, respectively, which can effectively adsorb VOCs. The synthetic process of the ZSM-5 zeolite is a simple preparation process and short in synthesis time. The results of this study not only help to realize the high-value utilization of silicon components in solid waste, but also provide an economical and effective way to synthesize VOCs adsorption materials.

Direct Performance of Triple-Stage Tandem Mass Spectrometry Analysis Using Dual-Direction Dipolar Excitation in a Digital Linear Ion Trap.

The ion trap mass spectrometer offers a unique advantage over other mass spectrometers by enabling multistage tandem mass spectrometry analysis with a single mass analyzer. It is employed to generate fragment ions through collision-induced dissociation (CID) usually by applying alternating current (AC) signals to a pair of electrodes for dipole excitation. The process of achieving double-stage tandem mass spectrometry analysis (MS/MS) in the mass spectrometer involves successive stages of injection, cooling, isolation, excitation, and scanning. For triple-stage tandem mass spectrometry analysis (MS/MS/MS), additional stages of isolation, cooling, and excitation need to be added based on the MS/MS analysis, resulting in a complex and time-consuming mass spectrometry workflow. In this study, a digital ion trap technology with the method of simultaneously applying dipole excitation signals to two pairs of electrodes in the ion trap was developed. This allows fragmentation of the precursor ion in one direction while exciting the first-generation product ions in the other direction, enabling direct acquisition of MS/MS/MS spectra. This approach simplifies the process of tandem mass spectrometry, as demonstrated by experimental studies on methamphetamine, which show that dual-direction excitation effectively reduces workflow and enhances the intensity of product ions. Additionally, the method of direct MS/MS/MS spectra achieved through dual-direction excitation in a digital ion trap mass spectrometer allows for a lower q value of the precursor ion owing to a pseudopotential well depth that is 1.648 times greater than that of a traditional sinusoidal ion trap. The experiments of analyzing high concentration n-butyl acetate and isobutyl acetate have shown that the implementation of MS/MS/MS analysis using dual-direction excitation can provide more mass spectral information and effectively distinguish between the two isomeric samples. The results of direct triple-stage spectra obtained by this technique for several typical volatile hazardous chemicals demonstrate the method's capability for rapid analysis and detection of such substances. In summary, the developed method of dual-directional excitation coupled with digital ion trap technology enables direct performance of triple-stage tandem mass spectrometry analysis, improving fragment ion intensities and providing more valuable mass spectral information. It offers advantages such as simplified workflows, faster analysis, and enhanced accuracy for analyzing compounds with low mass fragment ions.

Revelation of the discrepancy of volatile compounds in fig (Ficus carica) via gas chromatography ion-mobility spectrometry.

The volatile compounds of fig (Ficus carica) are influenced by various factors. To explore the composition and difference of volatile compounds among figs, gas chromatography ion mobility spectrometry (GC-IMS) was used to study the volatiles of figs from various regions, diverse cultivars, and after treatment with different drying methods. Aldehydes were the main volatile compounds in Bojihong from Shandong, while esters, ketones, and alcohols were the main volatile compounds in Bojihong from Sichuan and Guangdong. The volatiles of Branswick and Banane were similar, but differed significantly from those of Bojihong. Drying had the most significant effect on fig volatiles, which greatly reduced the content of benzaldehyde, (E)-2-hexenal, 2-methylbutanal aldehydes, lost the content of esters such as isoamyl acetate, butyl acetate, ethyl butyrate, and generated some ketones and ethers. The results showed that Bojihong from Shandong was more suitable for the processing of subsequent fig drying products.

Dynamic changes in microbial communities and flavor during different fermentation stages of proso millet Baijiu, a new product from Shanxi light-flavored Baijiu.

Proso millet, a high-quality fermentation material used for Chinese yellow wine production, can produce special flavored substances; however, its role in improving the flavor and altering microbial communities of light-flavored Baijiu during fermentation remain unknown. Thus, we aimed to investigate the effect of proso millet on improving the flavor of light-flavored Baijiu and altering microbial communities during different fermentation stages. The dynamic changes in the microbial communities and flavor of proso millet (50%) + sorghum (50%) mixed fermentation samples were analyzed through intermittent sampling on days 7, 14, 21, and 28 of the fermentation process. Microbial high-throughput sequencing and the analysis of flavor characteristics were conducted through 16S DNA/ ITS amplicon sequencing and gas chromatography (multi-capillary column)-ion mobility spectrometry, respectively. Proso millet significantly changed the core flavor compound composition of traditional light-flavored Baijiu from ethyl acetate, ethyl hexanoate, ethyl hexanoate dimer, ethyl butanoate, ethyl lactate, and butyl acetate to oct-2-ene, 2-butanol, propyl propanoate, 2-pentenal, and 4-methylpentanal. The amplicon sequencing analysis revealed that the alpha diversity parameters of bacterial and fungal communities, including the Chao1, Pielou_e, Shannon, and Simpson indices, for proso millet-sorghum mixed fermentation samples were significantly higher than those for sorghum fermentation samples (p < 0.05). Of the 40 most significant microbial genera in two treatments, proso millet significantly increased the abundance of 12 bacterial and 18 fungal genera. Among the 40 most significant bacterial and fungal species, 23 bacterial species belonged to the Lactobacillus genus, whereas the 30 primary fungal species belonged to 28 different genera. The analysis of the relationship between microbial changes and the main flavor compounds of light-flavored Baijiu showed that bacteria from the Weissella, Acinetobacter, Bacteroides, Psychrobacter, Pseudarthrobacter, Lactococcus, Chloroplast, Saccharopolyspora, Psychrobacter, Saccharopolyspora, Pseudonocardiaceae, Bacteroides genera and fungi from the Thermoascus, Aspergillus, Pichia, Rhizomucor, Papiliotrema, Hyphopichia, and Mucor genera significantly inhibited the synthesis of ethyl hexanoate, ethyl butanoate, ethyl lactate ethyl lactate, and butyl acetate but increased the synthesis of ethyl acetate (p < 0.05). Moreover, these microbes exhibited a significantly greater abundance in proso millet-sorghum mixed fermentation samples than in sorghum samples. The synthesis of special flavored compounds in proso millet Baijiu was significantly positively correlated with the presence of fungi from the Rhizopus, Papiliotrema, Wickerhamomyces, Aspergillus, and Thermoascus genera but negative correlated with the presence of bacteria from the Weissella, Acinetobacter, Psychrobacter, Pseudarthrobacter, Bacteroides, and Saccharopolyspora genera. Regarding ethanol content, the low alcohol content of Fenjiu may be due to the significantly high abundance of fungi from the Psathyrella genus and bacteria from the Staphylococcus, Kroppenstedtia, Brevibacterium, and Acetobacter genera during fermentation. In summary, proso millet significantly altered the flavor of light-flavored Baijiu by inducing the formation of a special microbial community; however, it did not increase alcohol concentration. This study lays the foundation for future research on Baijiu fermentation. Additionally, the study findings may help improve the production efficiency and elevate the quality and flavor of the final product.

Solid-liquid equilibrium solubility, modeling, Hansen solubility parameter and thermodynamic analysis of 2-Mercaptobenzimidazole in eleven mono-solvents and three binary solvents at different temperatures

The solubility of drugs is an important physicochemical data for its development and design. In this work, the solubility of 2-mercaptobenzimidazole (2-MBI) in eleven mono-solvent solvents (2-propoxyethanol, isopropyl acetate, butyl acetate, 2-methoxyethanol, 2-butanol, ethyl formate, 2-ethoxyethanol, isobutanol, 4-methyl-2-pentanone, 2-butoxyethanol and ethylene glycol) and three binary solvents (2-methoxyethanol + ethyl formate, 2-methoxyethanol + isopropyl acetate, 2-ethoxyethanol+ ethyl formate) was measured by a gravimetric analysis method at the temperatures from 283.15 to 323.15 K. The solubility of 2-MBI in the studied solvents increased with the increasing temperature. The measured solubility data of 2-MBI was described mathematically and back-calculated by CNIBS/R-K model, Margules model, UNIQUAC model, Jouyban-Acree-van't Hoff model and NRTL model. Hansen solubility parameters was calculated to assess the qualitative trend of 2-MBI in all selected mono and binary mixed solvents, analysis results indicating that the solubilization behavior of 2-MBI was intricate and can not only be assessed by one factor. In this study, the apparent thermodynamic parameters including ∆solHo, ∆solSo, ∆solGo, ξH and ξTS were investigated, positive values of ∆solHo indicating that the corresponding dissolution process of 2-MBI in all selected solvents was endothermic. In conclusion, these experimental and thermodynamic analysis can enrich the database and give support for design and optimize the crystallization process of 2-MBI.

Investigation of intermolecular interactions in butyl acetate using vibrational spectroscopy and non-empirical calculations

In this work, on the example of butyl acetate, the nature of intermolecular interactions was studied using vibrational spectroscopy (Raman and FTIR) and non-empirical calculations. The geometric structures of the most stable dimer and trimer aggregates of butyl acetate were optimized using the Density Functional Theory (DFT) method based on the B3LYP/6-311++G(d,p) basis set. Molecular aggregations in liquid butyl acetate were shown to be formed by dipole-dipole interactions and weak C-H…O hydrogen bonds. A potential energy distribution (PED) analysis was performed for the butyl acetate molecule, and experimental and calculated frequencies were found to be in good agreement. Frontier molecular orbitals such as the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the butyl acetate molecule were analyzed.

Calculating diffusion coefficients from molecular dynamics simulations for modelling foam processes of polypropylene: Investigating different process conditions and blowing agents

The choice of blowing agent is very important in foaming processes. In an earlier work the use of molecular dynamics simulations for the estimation of the diffusion coefficients of different blowing agents was discussed at elevated temperatures above the melting point. Therein it was shown that these simulations can give valuable information on blowing agent diffusion in polypropylene. The aim of the recent work is to expand this discussion to the simulation of different influences like pressure, blowing agent mixtures and blowing agents with higher molecular weight at temperatures above the melting point of PP. First a pressure range applied on the combined system of polymer and blowing agent, reasonable for the foam processing is discussed and their influence on the diffusion coefficients for CO2 in polypropylene is evaluated via MD simulations. The next step is the investigation of the influence of mixing a blowing agent with a co-blowing agent. The last part is the presentation of diffusion coefficients for different organic solvents, namely 2-propanol, acetone, ethyl acetate and butyl acetate which could be used as potential co-blowing agents. For both, the change in pressure and the mixing of blowing agents for the systems in question only small influences on the diffusion coefficients was discovered. The results of the diffusion coefficients for the different organic solvents are compared to each other and with former results, considered different molecular structure, size and polarities and are found to be reasonable.

Exposure assessment during paint spraying and drying using PTR-ToF-MS.

Spraying is a common way to distribute occupational products, but it puts worker's health at risk by exposing them to potentially harmful particles and gases. The objective of this study is to use time-resolved measurements to gain an understanding of spray applications at the process level and to compare them to predictions of exposure models. We used proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) at 1-s time resolution to monitor the gas phase concentration of the solvents acetone, ethanol, butyl acetate, xylene and 1-methoxy-2-propy acetate during outdoor spraying and indoor drying of metal plate under various conditions of outdoor air supply. We found that during spraying, gas-phase exposure was dominated by the more volatile solvents acetone and ethanol, which exhibited strong concentration variations due to the outdoor winds. During drying, exposure strongly depended on the strength of ventilation. Under conditions with high supply of outdoor air, our measurements show a near-exponential decay of the solvent concentrations during drying. Conversely, under conditions without outdoor air supply, the drying process required hours, during which the less volatile solvents passed through a concentration maximum in the gas phase, so that the exposure during drying exceeded the exposure during spraying. The concentrations measured during spraying were then compared for each of the substances individually with the predictions of the exposure models ECETOC TRA, Stoffenmanager, and ART using TREXMO. For these conditions, ECETOC TRA and Stoffenmanager predicted exposures in the measured concentration range, albeit not conservative for all solvents and each application. In contrast, ART largely overestimated the exposure for the more volatile solvents acetone and ethanol and slightly underestimated exposure to 1M2PA for one spraying. ECETOC TRA and ART do not have options to predict exposure during drying. Stoffenmanager has the option to predict drying together with spraying, but not to predict the drying phase independently. Our study demonstrates the importance of considering both the spray cloud and solvent evaporation during the drying process. To improve workplace safety, there is a critical need for enhanced exposure models and comprehensive datasets for calibration and validation covering a broader range of exposure situations.

Effect of UV-C Radiation and Thermal Treatment on Volatile Compounds, Physicochemical, Microbiological and Phytochemical Parameters on Apple Juice (Malus domestica) with Raspberry (Rubus idaleus L.)

Volatile compounds contribute to aroma and flavor, these being the main sensory attributes in food acceptance. This work addresses the physicochemical, volatile compounds, polyphenols, and flavonoids content and, antioxidant activity of apple-raspberry (90/10%) juice treated by thermal and ultraviolet radiation (UV-C) alone or in combination with moderate heat-treatment. Nineteen volatile compounds were identified which experienced changes depending on the treatment. Compounds such as α-ionone and β-ionone, that contribute to raspberries characteristic aroma, were present in a greater concentration in the UV-C treatment and lower in the thermal treatment. Likewise, 2-methyl butyl acetate, which give a fruity-sweet aroma typical of apples was present in a greater concentration in the UV-C treatment. Regarding polyphenol content, control and combined treatment presented the greater concentrations. However, after twenty days of storage, control and combined treatment presented the lower flavonoid concentration. Nevertheless, at this time, treatments showed no variations in antioxidant activity. Yeast and mold and total aerobic mesophilic and psychrophilic counts were reduced in the heat and combined treatments. In conclusion, UV-C and moderate heat might successfully be used to process a stable apple-raspberry juice while maintaining its quality and safety.

RAPID EXTRACTIVE SPECTROPHOTOMETRIC DETERMINATION OF PALLADIUM(II) USING 5- CHLOROSALICYLALDEHYDE THIOSEMICARBAZONE

Quantitative extraction of the Pd(II) complex with 5-Chlorosalicylaldehyde thiosemicarbazone (CSTSC) was achieved at pH levels ranging from 3.6 to 4.4 after a 30-second equilibration period in n-butyl acetate. When the concentration of Pd(II) does not exceed 9.0 μg mL-1, the complex formed between Pd(II) and 5-Chlorosalicylaldehyde thiosemicarbazone complies with Beer's law, and it displays the highest absorbance at 400 nm. By means of the mole ratio method and the Jobs continuous variation method, it was determined that the stoichiometry of the Pd(II)-CSTSC complex is 1:2. The stability of the extracted complex persisted for 96 hours. The calculated Sandell's sensitivity was 9.92 x 10-3 μg cm-2, while the molar absorptivity was found to be 1.072 x 104 L mol-1 cm-1. Utilizing this method, effective analysis has been carried out on synthetic samples, complexes, and water samples.

Towards biotechnological production of bio-based low molecular weight esters: a patent review.

Low molecular weight (LMW) esters, like ethyl acetate, methyl formate or butyl acetate, are widespread bulk chemicals in many industries. Each of them is currently produced in huge amounts (millions of tons per year scale) starting from fossil-based feedstock and they are used mainly because of their low toxicity and complete biodegradability. Energy transition is just half of the story on the path of fighting climate change: 45% of the global greenhouse gas emissions are caused by the production and use of all the products, materials and food necessary for modern human life. If the world is to reach its climate goals, there is the need to leave underground a significant proportion of the fossil feedstock and minimize environmental impacts of chemical manufacturing. This is the reason why a lot of efforts have been made to find novel routes for LMW esters production starting from renewable raw materials (e.g. biomasses or off-gases) and exploiting low-impact manufacturing, such as microbial fermentation or enzymatic reactions. This review reports the most significant patents, in the field of white biotechnology, that will hopefully lead to the commercialization of bio-based LMW esters as well as novel strategies, current problems to be solved, newer technologies, and some patent applications aiming at possible future developments.

Characteristics and correlation of flavor substances and hangover indexes in Chinese baijiu during storage

It is generally believed that there is a great relationship between hangover and the age of Baijiu. However, what factors make Baijiu (stored for a long time) feel better after drinking has not been well explained. In this study, ethanol metabolism, oxidation stress, inflammation and release of inhibitory neurotransmitter were selected as the indicator of hangover. The results showed that the longer the age of Baijiu, the higher the antioxidant and anti-inflammatory levels, the less damage to the liver of mice. In addition, we also found that the longer the age of Baijiu, the faster the ethanol metabolism rate, the smaller the impact on the brain. A correlation analysis on Baijiu ingredients and hangover related indicators was conducted. These results showed that ethyl acetate, n-butanol, n-hexanol, butyl acetate, ethyl octanoate, isovaleric acid, 2-hydroxypropionic acid had a great correlation with all hangover related indicators.

Excess Enthalpies and Heat of Esterification Reaction in Acetic Acid–n-Butanol–n-Butyl Acetate–Water System at 313.15 K

Excess Enthalpies and Heat of Esterification Reaction in Acetic Acid–n-Butanol–n-Butyl Acetate–Water System at 313.15 K

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ РАСПРОСТРАНЕНИЯ ЗАГРЯЗНЯЮЩИХ ВЕЩЕСТВ В ВОЗДУШНОЙ СРЕДЕ ПРОИЗВОДСТВЕННЫХ ПОМЕЩЕНИЙ

The mathematical model of pollutants diffusion in the air environment of industrial premises is considered, which is based on the classical model of continuous medium on the basis of the system of Navier-Stokes equations using the standard k - ε turbulence model, which takes into account the degree of air flow vortexing in the room. The developed mathematical model of heat and mass transfer of pollutants in the room, unlike existing models, allows to take into account the movement of a person and to estimate the concentration fields in different rooms in the building. The mathematical model is implemented on a computer in the problem-oriented environment SolidWorks 2020. The results of experimental studies and computational experiment on the spread of butyl acetate in the air environment of the room are presented. The received values of concentrations of butyl acetate satisfactorily agree with each other. Results of researches confirm possibility of use of the developed mathematical model in the software environment SolidWorks 2020 for carrying out computational experiments. The results of numerical modelling of butyl acetate distribution in air environment of premises at different location of a source are presented. It is shown, that moving of the person has essential influence on distribution of concentration field of butyl acetate in air environment of industrial premises.

Liquid-liquid phase of imidazolium-based ionic liquids in n-butyl acetate + n-butanol mixtures: Experimental measurements, quality testing, phase stability, thermodynamic modeling

The ester n-butyl acetate is an important chemical compound produced by esterification with n-butanol and used as solvent for pigments, vegetable oils and fats, and in the production of varnishes, coatings, waxes and resins. This work investigated the use of ionic liquids (ILs) as solvents in separation processes involving these substances. The ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) was synthesized, while 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtSO4]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) were purchased. The liquid–liquid equilibrium (LLE) was analyzed based on the experimental measurements (binodal curve, tie-lines), σ-profiles analysis (COSMOTherm), experimental data quality tests, phase stability and thermodynamic modeling with NRTL for the n-butyl acetate + n-butanol + IL ([BMIM][Cl], [EMIM][EtSO4], [EMIM][BF4]) systems at 298.15 K and 101.3 kPa. Experimental results indicated that the studied systems had the LLE phase behavior of type I. Experiments and calculations showed that [EMIM][EtSO4] and [BMIM][Cl] had the best capacities to separate the azeotrope n-butanol and n-butyl acetate. All systems showed separation factors values higher than unity. Low deviations, in the compositions of both liquid phases, indicate that the NRTL model was able to analyze the phase stability and model the phase behavior of the n-butyl acetate + n-butanol + IL systems using gamma-gamma approach.

Dissolution behavior, thermodynamic analysis and molecular simulation of lithium bis(fluorosulfonyl)imide in organic solvent at 273.15 K to 313.15 K

The solubility of LiFSI in ethanol, n-propanol, isopropanol, n-butanol, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate at 273.15 K to 313.15 K were determined. Elevated temperatures can actuate the continued mixing of LIFSI in the 11 fluids outlined above. In comparison, the addition of an alkyl group to the carbon chain of a structurally similar solvent molecule will result in a smaller solubility of LiFSI. Overall the molar solubility of LiFSI in esters are significantly higher than the other four alcohols. Besides, the corresponding theoretical results were mounted by fitting the classical equation. The deviation of the fitted values from the measured values showed that the Apelblat equation and Yaws model was more effectively in fitting the solubility of LiFSI. Then, The ΔsolHo, ΔsolGo, ΔsolSo of electrolyte solution were discussed by Van’t Hoff equation. Their fruits implied that the dissolution of LiFSI is found to be accompanied by heat absorption and entropy gain processes. Finally, the solvent molecular polarity index and solvation free energy were calculated by molecular visualization analysis and molecular dynamics simulation, and the correlation analysis with solubility order was carried out to illustrate the role of molecular features on the LiFSI solubility was explained. Electrostatic interactions and molecular polarity are the leading players in determining its solubility limit. These results will provide valuable reference for the purification of LiFSI and the development of new electrolyte solutions.

Pulmonary oxygen toxicity breath markers after heliox diving to 81 metres.

Pulmonary oxygen toxicity (POT), an adverse reaction to an elevated partial pressure of oxygen in the lungs, can develop as a result of prolonged hyperbaric hyperoxic conditions. Initially starting with tracheal discomfort, it results in pulmonary symptoms and ultimately lung fibrosis. Previous studies identified several volatile organic compounds (VOCs) in exhaled breath indicative of POT after various wet and dry hyperbaric hypoxic exposures, predominantly in laboratory settings. This study examined VOCs after exposures to 81 metres of seawater by three navy divers during operational heliox diving. Univariate testing did not yield significant results. However, targeted multivariate analysis of POT-associated VOCs identified significant (P = 0.004) changes of dodecane, tetradecane, octane, methylcyclohexane, and butyl acetate during the 4 h post-dive sampling period. No airway symptoms or discomfort were reported. This study demonstrates that breath sampling can be performed in the field, and VOCs indicative of oxygen toxicity are exhaled without clinical symptoms of POT, strengthening the belief that POT develops on a subclinical-to-symptomatic spectrum. However, this study was performed during an actual diving operation and therefore various confounders were introduced, which were excluded in previous laboratory studies. Future studies could focus on optimising sampling protocols for field use to ensure uniformity and reproducibility, and on establishing dose-response relationships.

Dynamic controlled atmosphere monitored by respiratory quotient as a new method to store pears: Effect on the volatile compounds profile and general quality

Pears (Pyrus communis) are climacteric fruit that require storage under appropriate conditions to extend availability and delay ripening. This study evaluated the production of volatile organic compounds (VOCs) and the physicochemical quality of ‘Santa Maria’ and ‘Rocha’ pears after storage in a controlled atmosphere (CA) or dynamic controlled atmosphere (DCA), monitored by respiratory quotient (RQ). The pears, harvested from an orchard in São Joaquim (Santa Catarina State), were stored at − 0.5 °C in CA (2.0 kPa O2) and DCA with RQ levels of 1.1, 1.2, 1.3, and 1.4, all under 1.0 kPa CO2. ‘Santa Maria’ pears were stored for four months, and ‘Rocha’ pears for six months, followed by seven days at 20 °C before quality analysis. Storage of ‘Santa Maria’ pears in CA resulted in fruit with a more yellow skin color, lower flesh firmness, and higher ethylene production, while ‘Rocha’ pears in CA retained higher flesh firmness and produced less ethylene at 4 and 7 days at 20 °C compared to DCA conditions. Storage conditions did not significantly affect soluble solids and acidity. In ‘Rocha’ pears, DCA, regardless of RQ, suppressed the production of butyl acetate, hexyl acetate, pentyl acetate, methyl acetate, and propyl acetate, while in ‘Santa Maria’ pears, esters such as butyl acetate and hexyl acetate were less affected. In conclusion, no significant differences were found between the DCA-RQ levels evaluated in this research in maintaining physicochemical quality and VOCs production. However, DCA suppressed VOCs production in both ‘Santa Maria’ and ‘Rocha’ pears compared with CA storage.