Tetrahydrofuran Extraction Research Articles

Isolation of the Antifungal Compound Alliodorin from the Heartwood of Cordia elaeagnoides A. DC. and the In Silico Analysis of the Laccase.

Cordia elaeagnoides A. DC. is an endemic species of Mexico valued for its timber. Renowned for its durability, resistance, and versatile applications in medicine, this tree holds significant commercial importance. Tetrahydrofuran (THF) extract from the heartwood of C. elaeagnoides was studied. Through chromatographic column purification, the compound 8-(2,5-Dihydroxyphenyl)-2,6-dimethylocta-2,6-dienal, also known as alliodorin, was successfully isolated. Identification of alliodorin was confirmed through comprehensive analysis utilizing NMR, IR, and mass spectrometry techniques. Inhibition tests were conducted using both the THF extract and alliodorin against the rotting fungus Trametes versicolor (L.) Lloyd, employing the agar well diffusion assay. Remarkably, alliodorin exhibited 100% inhibition with a median lethal concentration of 0.079 mg/mL and a total lethal concentration of 0.127 mg/mL, in comparison to the commercial fungicide benomyl, which requires a concentration of 1 mg/mL. In silico analysis through molecular docking on the laccase enzyme was proposed in order to explain the inhibitory activity against the fungus T. versicolor, as this enzyme is one of the main sources of nutrients and development for the fungus. Based on these findings, we deduced that alliodorin holds promise as a potent antifungal agent, potentially applicable in a wide array of technological and environmentally friendly initiatives.

Experimental study on changes in components and pore characteristics of acidified coal treated by organic solvents

Chemical solvents could change coal components and effectively enhance conductivity of coal reservoir, which is beneficial to efficient methane extraction. Relationship between coal chemical structure parameters and main functional groups variations affected by acidification and tetrahydrofuran (THF) is investigated through infrared spectroscopy tests and curve peak fitting. Meanwhile, variations in fractal dimensionality and pore structure characteristics are studied by adopting low-temperature nitrogen adsorption tests and Frenkel-Halsey-Hill (FHH) fractal model. Main results are: (1) After extracting raw coal and acidified coal using THF with varying concentrations, absorbance of aromatic hydrocarbon –CH surface and aromatic methyl bond become weaker. While the proportion of substituted aromatic hydrocarbons increases in acidified coal than in raw coal. Acidification treatment could reduce strength of C-O-C absorption peak. Proportion of CH2 and CH3 in raw coal decreases with increasing THF concentration, indicating that THF could react with aliphatic structure to reduce CH2 and CH3 content. Extraction with THF dissolves aromatic structure, lowering C = C content in coal to different degrees. (2) Acidification pretreatment could produce more micropores in coal samples. Micropore contents of acidified coal after THF extraction are all lower than coal sample S, while transition pores and mesopores contents are both higher than those in coal sample S. (3) Fractal dimension D1 of raw coal indicates a relatively linear relationship with specific surface area, while the D1 of acidified coal is less correlated with specific surface area. The factor D2 shows a linear relationship with average pore size. After treatment of THF, average pore size of raw coal increases with D2, while that of acidified coal varies in different degrees with uneven distribution of pore sizes.

Separation and characterisation of glyceryl glycosides and lignin from acid-catalysed glycerol pretreatment hydrolysate of sugarcane bagasse

Acid-catalysed glycerol (ACG) pretreatment of biomass is one of the pre-treating techniques for the enzyme-mediated lignocellulosic biorefinery, while inadequate attention has been paid to the glycerol modified saccharides and lignin redistributed to the hydrolysate, nor their bioactive properties. In this study, a sequential process involving tetrahydrofuran (THF) extraction and carbon/celite adsorption-elution was employed to recover lignin and glyceryl glycosides (GG) from ACG hydrolysate. The physicochemical and structural properties of lignin were systematically explored, and were related to their antioxidation properties, the composition and moisturising activities of GG was investigated. Two types of lignin i.e., water-insoluble lignin (WIL) and water-soluble lignin (WSL) were obtained, accounting for 49.60 wt% and 38.00 wt% of the total lignin in raw bagasse, respectively. GG separated from the hydrolysate yielded an overall recovery of 68.17 wt% of the xylan from the raw bagasse. The relatively high yield of lignin and GG can be attributed to the incorporation of glycerol molecules. 2D HSQC NMR results revealed that glycerol effectively preserved the β-O-4 structure of lignin during ACG pretreatment through α-etherification and γ-esterification. 31P NMR results showed that WSL has more aliphatic hydroxyl groups, resulting in increased water solubility, whereas WIL exhibited a higher amount of phenolic hydroxyl groups, contributing to the increased in vitro antioxidant properties. WSL contained significant proportion of p-coumaric acid glycerides and demonstrated low cytotoxicity along with a favorable cellular antioxidant capacity (CAA). HPLC-MS analysis revealed that the GG was a mixture of 56.44% glyceryl xylosides and 36.49% glyceryl glucosides, which displayed a superior moisturising capacity compared to commercial humectants such as hyaluronic acid (HA) and α-glyceryl glucosides (αGG). Overall, this study establishes a foundation for the extraction of value-adding bioactive compounds from acid-catalysed glycerol pretreatment hydrolysate, supporting the implementation of ACG techniques in biorefineries.

Preparation of pitch precursor with excellent spinnability for general-purpose carbon fibre using coal tar pitch as raw material

Tetrahydrofuran (THF) extract of coal tar pitch (CTP) was used instead of blending CTP with pretreated pyrolysis fuel oil to prepare an isotropic pitch precursor with excellent spinnability for general-purpose carbon fibre through bromination–dehydrobromination. The feasibility and effectiveness of synthesising an isotropic pitch precursor derived from THF-soluble (CTP-THFs) is demonstrated in this study. The results show that CTP-THFs contains more light components than CTP; CTP-THFs and CTP monomer proportions were 62.52% and 45.32%, respectively. However, based on comparisons of CTP-THFsBr0 and CTPBr0 characterisations, CTP-THFs exhibits better polycondensation than CTP. Bromination–dehydrobromination promotes polycondensation of pitch precursors, leading to greater carbon aromaticity in CTP-THFsBr5, CTP-THFsBr10, and CTP-THFsBr15 than that in CTP-THFsBr0 and CTPBr0. CTP-THFsBr5 and CTP-THFsBr10 have excellent spinnability even with softening points as high as 230 °C. The peri-condensed carbon and carbon aromaticity of CTP-THFsBr5 and CTP-THFsBr10 are high owing to the higher degree of polycondensation; however, they still possess a more linear molecular structure. The as-prepared carbon fibre exhibits homogeneity and uniformity, and the mechanical performance is comparable with that of commercial general-purpose carbon fibre products.

Multistage gradient extractive separation and direct and indirect analysis of petroleum ether insoluble fractions from low temperature coal tar

The composition and structure of heavy components in coal tar are very complex, which affect the further processing and utilization of coal tar. In this paper, the multistage gradient extractive separation and analysis of petroleum ether (PE) insoluble fractions from low temperature coal tar (CTPI) were performed. CTPI was separated into diethyl ether extracts (DEE) and residues (DER) by Soxhlet extraction with quartz sand. DEE was further stepwise separated into tetrachloromethane extracts (TME), toluene extracts (MBE) and residues (MBR). DER was separated into ethyl acetate extracts (EAE), tetrahydrofuran extracts (THFE) and residues (THFR). Physical and chemical characterization of the six fractions were analyzed, using GPC, Uv-fluorescence spectroscopy, FTIR, 13C CP/MAS NMR, 1H MAS NMR, XRD, TG-FTIR and Py-GC/MS, to obtain the composition and structure of these fractions. The results show that the extraction yields of TME, MBE, MBR, EAE, THFE and THFR are 29.98 wt%, 42.13 wt%, 10.93 wt%, 6.02 wt%, 6.98 wt% and 3.96 wt%, respectively. The order of the maximum molecular weights is THFE > EAE > MBE > TME > MBR. THFE has the largest polycyclic aromatic structure. THFE and EAE contain more ethers than other fractions, and they may be mainly composed of polycyclic aromatic structure with -CH2- as bridge bonds. The order of fa values is EAE > CTPI > MBR > MBE > THFE > TME. The aromatic layer spacing d002 follows the order of MBE > TME > MBR > THFE > EAE > CTPI. The final thermal weight loss rates of these fractions follow the order of TME > MBE > THFE > EAE > MBR > THFR. Oxygen-containing compounds, acid compounds and heteroatomic compounds have been enriched in the pyrolysis volatiles derived from the separated fractions (EAE, THFE and THFR) of DER. The common feature of DEE and DER is the presence of the widely distributed phenolic compounds.

Effects of chemical solvents on coal pore structural and fractal characteristics: An experimental investigation

Chemical solvent treatment is one of the most effective means to improve pore structure of low-permeability coal and increase production of coalbed methane. Low-temperature liquid nitrogen adsorption method, X-ray diffraction (XRD) mineral analysis and fractal theory were adopted to study variations in coal pore structural parameters and fractal characteristics affected by hydrochloric acid (HCl), tetrahydrofuran (THF) and carbon disulfide (CS2). Liquid nitrogen adsorption results of coal samples were analyzed using density functional theory (DFT), Brunauer-Emmett-Teller (BET) equation and Barrett-Johner-Halenda (BJH) model. Meanwhile, changes in fractal dimensions of pore surface (D1) and pore structure (D2) were calculated based on Frenkel-Halsey-Hill (FHH) model. Relationship between pore volume, average pore diameter, specific surface area and two fractal dimensions were established. Results show that: (1) Hysteresis lines exist in all isothermal adsorption-desorption processes of coal. Pores of raw coal are mainly semi-open pores with poor connectivity. The types of pores do not change significantly after THF and CS2 treatment, while the number of pores rise. In contrast, affected by HCl treatment, ink-bottle pores and open pores increase and pore fracture network connectivity becomes better. (2) Pore sizes of treated coal mainly distribute in range of 0–10 nm. After HCl treatment, many closed pores are opened, with growth in proportion of micropores. Meanwhile, specific surface area (SSA) of pores increases by 55.21% and 31.36%, respectively. THF extraction results in an increase in pore volume and SSA. After CS2 extraction, dissolution of organic material increases pore size and further improve volume of transition pores and mesopores. (3) HCl treatment causes decrease in D1 value of pores. However, in organic-solvent-treatment cases, solvent residues retain on coal pores, resulting in growth in D1 value and pore surface becoming rougher. Proportion of total pore volume of transition pores and mesopores of acidized coal decreases and D2 value rises. Pore distribution is more uneven. Relevant results could provide theoretical references for revealing mechanism of chemical solvents effects on gas flow in coal.

Mechanism of solvent extraction-induced changes to nanoscale pores of coal before and after acidification

As the most widely used reservoir stimulation method, hydraulic fracturing requires the injection of large volumes of fluid with certain viscosity, mainly formed by water and various additives in a certain proportion, into coal seam for the purpose of improving the permeability of coal reservoir, and thus the selection of appropriate fracturing fluid is very important to improve the fracturing effect. In the study, using a medium-volatile bituminous coal as the research object, solvent extraction experiments of coal samples before and after acidification under different solvent concentrations were carried out. After the soluble low molecular weight compounds in coal were extracted and dissolved, and the differences in pore structure parameters and their mechanisms in coal were investigated by using low-temperature liquid nitrogen adsorption apparatus and capillary coalescence theory. The research results show that, after tetrahydrofuran (THF) extraction with different concentrations, the pore volume (PV) of each pore size section for raw coal decreases, and with the increase of the pore size, the decreasing PV tends to be stable. The PV of acidified coal increases significantly in all pore size ranges, especially in the range of 5 ∼ 10 nm. Compared with unacidified coals, the low-temperature nitrogen adsorption isotherm of acidified coals after extracted with different concentrations of THF were more prominent in the relative pressure of 0.8 ∼ 1.0. As THF concentration increases, the fractal dimension D of raw coal and nitrogen adsorption capacity decrease, while the fractal dimension D of acidified coal and nitrogen adsorption capacity increase and are significantly bigger than those of raw coal. The nitrogen adsorption capacity of raw coal and acidified coal shows an inverted “N” and “N” trend, respectively, and the nitrogen adsorption capacity of the residue with 50%THF extraction after acidification reaches the maximum value of 1.47 cm3/g. This study suggests that adding a certain proportion of organic solvent (THF) and acid into fracturing fluids can be beneficial to improve reservoir porosity and thus increasing gas production.

The effect of organic solvent washing on the structure of hydrochar-based dissolved organic matters and its potential environmental toxicity.

With the increased interest in the practical use of hydrochar, concerns about the possible environmental biotoxicity of hydrochar and its released dissolved organic matters (DOM) have grown. As a common method for removing bio-oil on the surface of hydrochar, the effect of organic solvent washing on the properties of hydrochar released DOM remains unclear. In this study, we made a comprehensive comparison of hydrochar properties and molecule structure as well as biotoxicity of DOM released from HC (raw hydrochar) and THC (hydrochar washed by tetrahydrofuran). The results indicated that the mass loss of hydrochar was obvious after tetrahydrofuran (THF) washing, and a decline of H/C atomic ratio and increase of N/C and O/C atomic ratios was observed based on Van Krevelen (VK) diagram. This result was further confirmed by FTIR, 13C NMR, and XPS results. Meanwhile, the molecule structure of DOM was shifted to lower molecule weight with higher O-contain compounds after THF extraction due to the demethanation process. However, the biotoxicity experiments indicated that both extracted DOM had no significant impact on germination rate of wheat, and HC-treated sample even exhibited growth superiority. Nevertheless, potential toxicity was observed with the increase of the activity of antioxidant enzymes, and THF washing aggravated the potential oxidative damage through increasing the aromaticity of DOM. Such understanding highlights the importance of evaluating hydrochar and its released DOM before applications, so as to reduce the potential environment biotoxicity.

Characterisation of Elastomers as Food Contact Materials-Part 1: Quantification of Extractable Compounds, Swelling of Elastomers in Food Simulants and Release of Elements.

Elastomers are not a uniform class of materials but comprise a broad spectrum of chemically different polymers. Sealing gaskets, gloves, teats, conveyor belts and tubing are examples of elastomers being used as food contact materials (FCMs). Ten elastomer samples were evaluated with respect to the content of extractable compounds, migration of substances into ethanolic food simulants, swelling in food simulants and release of elements in different food simulants. The number of extractable substances <1000 Da was determined by comprehensive two-dimensional gas chromatography coupled with flame ionisation detection (GC × GC–FID) analysis of tetrahydrofuran (THF) extracts. The number of signals ranged from 61 (a thermoplastic elastomer (TPE)) to 690 (a natural rubber/styrene-butadiene-rubber blend (NR/SBR)). As for risk assessment, the decisive factor is which substances reach the food. The extent of substances that migrate into ethanolic food simulants was investigated. Elastomer FCMs can be the source of food contamination with heavy metals. Notably, contamination with lead was detected in some samples investigated in this study. It was shown that food simulants harbour the potential to morphologically alter or even disintegrate elastomeric materials. The results presented here highlight the importance to carefully choose the elastomer type for the intended use as FCMs as not every application may prove safe for consumers.

Wide‐scale evaluation of Origanum munzurense Kit Tan &amp; Sorger using different extraction techniques: Antioxidant capacity, chemical compounds, trace element content, total phenolic content, antibacterial activity and genotoxic effect

AbstractThis aim of this work was to investigate the various properties of Origanum munzurense Kit Tan &amp; Sorger that are previously unknown. In this context, chemical compound, antioxidant activity, total polyphenol content, mineral and trace element composition, antibacterial activity and genotoxicity effects of its extracts and essential oil were widely analysed. The extracts and essential oil of Origanum munzurense were obtained by three different extraction methods. All contents of extracts and essential oil were analysed by GC‐MS and evaluated according to mass spectral libraries of GC‐MS. The identified compounds were evaluated according to literature to put forward their benefits on human health. The phenolic content analysis of Origanum munzurense was performed using the Folin‐Ciocalteu method. 178.59, 184.20, 231.17, 319.28 and 1051.94 mg GAE/100 g dry weight were determined for methanol, water, acetonitrile, ethanol and subcritical water extracts, respectively. DPPH and CUPRAC methods were used to determine antioxidant activity. The highest half‐maximal inhibitory concentration and Trolox equivalent antioxidant capacity values were found as 0.110 mg mL−1 and 2.197 using water and tetrahydrofuran extracts, respectively. A total of 21 mineral and trace elements were detected in the ICP‐MS analysis of O munzurense using the wet digestion procedure. The effects of the extracts and essential oil on Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and S aureus were examined using disc diffusion and microdilution methods. Essential oil exhibited the highest antibacterial activity. The essential oil was found to cause less DNA damage using the comet assay in Hep G2 cells compared with tetrahydrofuran extract.

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

Understanding the catalytic pyrolysis mechanism of lignite is of great significance for obtaining a high yield of the target products or designing high-efficiency catalysts, which are generally derived by using simple model compounds, while the ordinary model compounds cannot represent the real atmosphere of lignite pyrolysis owing to the simple structures and single reactions. Based on the coal two-phase model, the extractable compounds are the important compositions of coal, which can reflect the partial characteristics of raw coal while obtaining a high extraction yield. Hence, a better understanding of the interaction between the coal structure and catalyst can be inferred by using a mobile phase in coal as model compounds instead of conventional simple compounds. In this work, tetrahydrofuran extracts of lignite were chosen as model compounds to study the catalytic pyrolysis mechanism with separate addition of Fe(NO3)3 and FeCl3 by using a thermogravimetric combined with mass spectrometry. It was found that about 77.88% of the extracts were vaporized before 700 °C, and the residual yield was 22.12%. With the separate addition of 5 wt % of Fe(NO3)3 and FeCl3, the conversion of the extracts increased to 84.38% and 89.66%. Meanwhile, the final temperature decreased to 650 and 550 °C, respectively. The addition of Fe(NO3)3 and FeCl3 promoted the breakage of aliphatic chains at approximately 150 °C, leading to the generation of CH4 and H2 in the temperature range 100–200 °C, which were nearly invisible for that without catalyst. The addition of iron-based catalysts allowed more CO2 formation at approximately 200 °C since they enabled efficient promotion of the cleavage of carboxyl functionals at lower temperatures. The enlarged peak of H2O and CH4 at approximately 500 °C means that iron-based catalysts are significant for the cleavage of methoxy groups in the catalytic respect. Aromatic side chains facilitated cracking at approximately 500 °C, leading to more light aliphatics and aromatics generation in this temperature range.

Dissolution behavior and chemical characteristics of low molecular weight compounds from tectonically deformed coal under tetrahydrofuran extraction

Tectonically deformed coal (TDC) is formed by complex and variable tectonic stresses. The induced physical-chemical effects result in a variety of chemical compositions and structures in TDCs. In this work, medium volatile bituminous coals with four types of tectonic deformation were selected and extracted with tetrahydrofuran to investigate the dissolution behavior and distribution of low molecular weight compounds in TDCs. The results revealed that a higher degree of tectonic deformation in the coal produces a higher total extraction yield as the total extraction time increases. A diffusion model also establishes a good relationship between the extraction mass and extraction time, and the diffusion coefficient Dobs can be used to describe the extraction kinetics. Chemical analysis of the extracts using column chromatography and GC/MS further found that there are more binding points for forming non-covalent bonds in long chain aliphatic hydrocarbons. So the alkanes with more than 20 carbon atoms are often dissolved at the medium and late stages. Aromatic compounds, which are mostly dissolved at the medium stage, are essentially combined into the coal macromolecular structure by π–π stacking interactions or hydrogen bonds. While a large number of heteroatomic compounds are distributed widely in coals, resulting in diverse dissolution behaviors. Under the tectonic stresses, the type and content of low molecular weight compounds in TDCs increase compared to intact coal. Particularly, an increase in tectonic deformation appeared to produce more aromatic hydrocarbons and long chain alkanes in TDCs, whilst the presence of heteroatomic compounds becomes more complex.

Effect of Tetrahydrofuran Extraction on Surface Functional Groups of Coking Coal and Its Wettability.

Coking coal was extracted with tetrahydrofuran solvent using ultrasonic and microwave-assisted method at 50°C and atmospheric pressure. Wettability of raw coal and its residue (residual coal) was tested with capillary penetration method. The raw and residual coals were studied by Fourier transform infrared spectroscopy (FTIR) with curve-fitting analysis. The variation of main surface functional groups of coking coal before and after extraction and its effect on wettability were analyzed. The results were obtained as the following: after extraction with tetrahydrofuran, hydroxyl, ether oxygen, and carbonyl in the coal structure were dissolved, the content of hydrophilic functional groups reduced, and then the hydrophobicity of coal enhanced. At the same time, part of aliphatic hydrocarbon dissolved, the length of aliphatic chains (I2) decreased from 3.961 of raw coal to 3.636 of residual coal, the length of aliphatic chains became shorter, aliphatic CH2 side-chains decreased and aliphatic CH3 side-chains increased, and hydrophobic functional groups content increased. In the aromatic structure, four hydrogens per ring increased and two, three, and five hydrogens per ring decreased. Reduction of substitution functional groups and aliphatic hydrocarbon decreased with the side-chains breakage produce more active sites, which increases the degree of condensation of the aromatic ring (I3). The combined action of the decrease of the hydrophilic functional groups and the increase of the hydrophobic functional groups made the wettability of the coking coal become weak.

Evolution of coke in the catalytic conversion of biomass-derivates by combined in-situ DRIFTS and ex-situ approach: Effect of functional structure

To understand the evolution of coke in the catalytic conversion of biomass-derivates, in-situ diffuse reflectance Fourier transform infrared spectroscopy experiments and ex-situ extraction method were combined to identify the coke species. Considering the ring-shape and unsaturation of furan as an important intermediate from biomass pyrolysis, other simplified biomass-derivates like tetrahydrofuran, butanol, ethylene glycol and methanol was also studied to investigate the effect of its chemical structure on coke formation. The ex-situ study showed that the performance in the induction period and deactivation stage was closely related to the functional group of biomass-derivates. Coke extraction of furan and tetrahydrofuran were of similar composition, which was of doubt. Combined results with in-situ diffuse reflectance Fourier transform infrared spectroscopy revealed that polymethyl benzaldehyde was the main composition of active coke in the catalytic conversion of furan, and then intermediate of benzofuran was detected, and finally alkyl naphthalene and polyaromatic hydrocarbons were formed by polymerization and hydrogen transfer. This study will provide guidelines to enhance hydrocarbon production from the viewpoint of active coke like pre-feeding of polymethyl benzaldehyde.

Structures and fractal characteristics of pores in low volatile bituminous deformed coals by low-temperature N2 adsorption after different solvents treatments

Coal is a porous medium with fractal characteristics. With the removal of soluble fractions under solvent treatment, the structures and fractal characteristics of pores are bound to produce changes. Exampled by low volatile bituminous coals with different degrees of deformation from Huoerxinhe and Changcun coal mines in Qinshui basin, North China, the paper investigated on the changes of pore structure parameters and minerals compositions of coals before and after different solvents treatments, including tetrahydrofuran (THF), hydrochloric acid (HCl) and chlorine dioxide (ClO2). And Insight into the relationships between fractal dimensions and pore structure parameters and coal compositions were provided. Results show that: The shapes of N2 adsorption/desorption isotherms rarely change but their adsorption quantities differ sharply after different solvents treatments for coal with same deformation, indicating no change in pore type but a change in the number of pore in the same pore size. Compared to raw coals, with the removal of soluble fractions in coals pore volume (PV) and specific surface area (SSA) tend to ascend after THF extraction; changes in PV and SSA depend jointly on the dissolution of carbonate minerals and the swelling of clay minerals after HCl treatment; and the varieties of PV and SSA, to a great extent, are closely related to the swelling of clay minerals after ClO2 treatment. Pore structure fractal dimension (DA) and surface fractal dimension (DB) are obtained based on Frenkel-Halsey-Hill model. DA is mainly affected by the proportion of transitional pores and mesopores on PV; therefore, DA can be used to describe pore volumetric roughness of these transitional pores and mesopores. Meanwhile, DB is mainly influenced by the proportion of micropores on SSA; therefore, DB can be utilized to represent pore surface roughness of these micropores. As coal deformation increases, DA grows for raw coals and coals after extraction with THF; therefore, PV has a significant migration to the pores of small apertures causing the growing contribution of micropores to PV. However, DA declines for coals treated by HCl and ClO2, potentially because the welling of clay minerals blocks the pores of small apertures and increase the proportion of the pores of large apertures on PV. DB shows no clear trends with increasing coal deformation. A “reversed U-shaped” curve relationship is observed between moisture in coal and two fractal dimensions, which is due to the effect of water molecule interfacial tension. Ash correlates negatively with DA and positively with DB because of the various influences of minerals on pore homogeneity in pores of different apertures.

Hierarchical structure and properties of rigid PVC foam crosslinked by the reaction between anhydride and diisocyanate

ABSTRACTRigid crosslinked poly(vinyl chloride) (c‐PVC) foams by forming semi‐interpenetrating network (SIPN) structure via the reaction of phthalic anhydride (PA) and diisocyanate were prepared. The influence of PA on hierarchical structure and mechanical properties of c‐PVC foam was studied. The Fourier transform infrared spectrometer results showed that the presence of PA resulted in the formation of imide structure in the SIPN of obtained c‐PVC foams, which introduced a structural defect of SIPN. Thus, the residue (gel) from tetrahydrofuran extraction of the foams decreased with the increase of PA content. Dynamic thermal analysis showed the presence of three aggregation state structures in the c‐PVC foams, depending on the loading of PA. The addition of PA in the formulations affected cellular structure and mechanical properties of the obtained foams. Furthermore, the influence of chemical environment of anhydride compounds on the formation of imide structure in the crosslinking network of c‐PVC foams was discussed. A strategy for reducing defect of crosslinking network and improving mechanical properties was put forward. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46141.

Thermoplastic development of coking and non-coking maceral concentrates and molecular weight distribution of their pyrolysis products

A suit of nitrogen-dried maceral concentrates derived from a coking coal and a non-coking coal was investigated to reveal the impact of varying coal main organic constituent, the vitrinite, on their thermoplasticity and pyrolysis products. The thermoplastic development of maceral concentrates during pyrolysis was evaluated via their thermo-swelling and dynamic volatile release. These measurements were then linked to molecular weight distributions of vaporised tars and tetrahydrofuran (THF) extracts obtained from heat-treated samples. Regardless of the vitrinite content, only coking macerals agglomerated during pyrolysis while non-coking macerals retained their powdered structure. This result indicated that although concentrating the vitrinite could alter the extent of coal thermoplasticity, such process could not grant or remove thermoplasticity from a maceral concentrate. This was reflected in the similar molecular weight distribution of solvent extracts produced between the parent coals and their concentrates. In specific, coking concentrates generated extractable materials with a relatively more complex structure, consisting of a bimodal molecular weight distribution with 12–14Da repeating structures at <600Da and 24Da reoccurring units between 600 and ∼1500Da. Solvent extracts isolated from non-coking concentrates, on the other hand, possessed a unimodal molecular weight distribution with only 12–14Da repeating structures extending to ∼800Da. The absence of high-range molecular weight materials (the 24Da repeating units) in non-coking coal and its concentrates was speculated to play a vital role to their inability to exhibit thermoplastic behaviour during pyrolysis.

Secondary Metabolites in Allergic Plant Pollen Samples Modulate Afferent Neurons and Murine Tracheal Rings.

Plant pollens are strong airborne elicitors of asthma. Their proteinaceous allergens have been studied intensively, but little is known about a possible contribution of pollen secondary metabolites to the nonallergic exacerbation of asthma. Pollen samples originating from 30 plant species were analyzed by HPLC coupled to PDA, ESIMS, and ELSD detectors and off-line NMR spectroscopy. Polyamine conjugates, flavonoids, and sesquiterpene lactones were identified. Polyamine conjugates were characteristic of all Asteraceae species. The presence of sesquiterpene lactones in Asteraceae pollen varied between species and pollen lots. All plant pollen, including those from non-Asteraceae species, contained to some extent electrophiles as determined by their reaction with N-acetyl-l-cysteine. Selected pollen extracts and pure compounds were tested in murine afferent neurons and in murine tracheal preparations. Tetrahydrofuran extracts of Ambrosia artemisiifolia and Ambrosia psilostachya pollen and a mixture of sesquiterpene lactones coronopilin/parthenin increased the intracellular Ca2+ concentration in 15%, 32%, and 37% of cinnamaldehyde-responsive neurons, respectively. In organ bath experiments, only the sesquiterpene lactones tested induced a weak dilatation of naïve tracheas and strongly lowered the maximal methacholine-induced tracheal constriction. A tetrahydrofuran extract of A. psilostachya and coronopilin/parthenin led to a time-dependent relaxation of the methacholine-preconstricted trachea. These results provide the first evidence for a potential role of pollen secondary metabolites in the modulation of the tracheal tone.

Comparative Antioxidant Properties of Juniperus communis L. and Juniperus virginiana L. Extracts Obtained by Refluxing and Sonication Methods

The aim of this study was to evaluate the antioxidant activity of ethyl acetate and tetrahydrofuran extracts of Juniperus berries, branches and needles, by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Two Juniperus species, Juniperus communis and Juniperus virginiana, from different regions were used. The extracts obtained by sonication and refluxing extraction were studied by gas chromatography-mass spectrometry, which revealed that the Romanian juniper extracts are largely comprised of monoterpene hydrocarbons, such as a-pinene, b-pinene, b-hellandrene, sabinene, b-cadinene, t-cadinene, b-caryophyllene, b-cubebene, b-elemene and germacrene D. The antioxidant activity was highest in ethyl acetate Juniperus communis needles extract from Lipova (Romania) and in ethyl acetate Juniperus virginiana branches extract from Macea Botanical Garden (Romania). The mean rates (vm) of DPPH consumption were higher for the tetrahydrofuran Juniperus communis branches extract from Lipova and ethyl acetate Juniperus virginiana branches extract than in tetrahydrofuran Juniperus communis berries extract from Lipova.

Separation and analysis of high range extractable molecules formed during coal pyrolysis using coupled thin layer chromatography-imaging mass spectrometry (TLC-LDI-IMS)

A new coupled thin layer chromatography-imaging mass spectrometry method was developed to investigate solvent extracts from a coal. The technique was used to assess the separation of complex molecular structures in a tetrahydrofuran (THF) soluble extract taken from a semi-coke (the solid residue obtained after thermal pre-treatment of coal at 430°C). Thin layer chromatography (TLC) was then used with acetone as a mobile phase and silica as a stationary phase. The component separation was determined by laser desorption/ionisation time-of-flight imaging mass spectrometry (i.e. TLC-LDI-IMS). This provided the molecular weight distributions and spatial concentrations of coal derived structures observed over the TLC plate. In general, acetone lifted and concentrated lighter molecular species in the range of 200–500Da by up to 55% compared to the THF extract. Structures of 500–1000Da in molecular weight were lifted, but to lesser extent, distributing these more evenly across the TLC plate. The structures observed in the acetone-concentrate repeated every 12–14Da as in a homologous series, similar to previous studies. Residual material remaining in the sample (unascended by the mobile phase) showed repeating structures every 24Da from 600–3000Da, also similar to previous work.A novel methodology was also evaluated using the TLC plate as a heated substrate for inducing and studying cross-linking reactions. Acetone soluble material between 200–500Da was loaded onto the TLC plate and heated to 250°C. This was found to convert the low molecular weight compounds into more complex structures between 1500 and 4000Da. Direct use of a MALDI-suitable TLC plate as a reaction surface provided a means of characterising the high molecular weight products without the need for a solvent to transfer material onto a second MALDI analysis plate. This avoided limitations in molecular weight with solvent solubility. Overall, the TLC-LDI-IMS method was shown to be a suitable method for tracking the separation and potential cross-linking mechanisms involved in coal derived extracts.