Ethylene Concentration Research Articles

Modified HKUST-1-based packaging with ethylene adsorption property for food preservation

Ethylene-induced quality deterioration of postharvest fruits aggravates food wastage worldwide, therefore, the development of effective approaches for reducing ethylene concentration of packaged fruits is of paramount importance in extending shelf life and minimizing food spoilage. In this work, a modified HKUST-1 (i.e., HKUST-1-P) was added to a chitosan quaternary ammonium salt (CQAS)-gelatin matrix to prepare a food packaging film (i.e., HPCGF) with ethylene adsorption property and improved water stability. Molecular simulation revealed that the ethylene preferentially bonds to the C and O sites of HKUST-1, followed by the H and Cu sites to achieve adsorption. The physical adsorption performance of HKUST-1 and HKUST-1-P was 89.91 and 89.05 cm3/g STP, respectively. Moreover, HPCGF showed improved physicochemical (e.g., thermal stability, mechanical, and gas barriers) properties that are beneficial for food packaging. As a validation experiment, the effectiveness of HPCGF for preserving a climacteric fruit (banana) was demonstrated by absorpting the ethylene, maintaining the color and hardness, delaying lipid peroxidation, and prolonging shelf life of bananas. This study will aid in the development of novel packaging materials with ethylene adsorption properties for preserving perishable foods, helping reduce food waste.

Occurrence and tissue-specific partitioning of alternative brominated flame retardants in northwest Atlantic harbor seal pups (Phoca vitulina vitulina)

Brominated flame retardants such as polybrominated diphenyl ethers (PBDEs) have been used for decades until evidence of negative health effects led to bans in many countries. PBDEs have since been replaced by alternative legacy compounds or newly developed chemicals. In this study, eight alternative brominated flame retardants were analyzed in blubber and liver of harbor seal pups (≤6 months) from the Northwest Atlantic collected during 2001–2010 to elucidate concentrations, patterns, contamination trends, potential maternal transfer, and tissue partitioning. All compounds were detected in liver and blubber tissues with hexabromocyclododecane (HBCD) isomers and 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB) predominating. Overall, α-HBCD was the dominant HBCD isomer in both tissues although the concentrations of γ-HBCD exceeded those of α-HBCD in seven pups, indicating their mothers may have had alternative dietary patterns or recent exposure to the commercial mixture. Although it was detected in less than half of the samples, to our knowledge, this is the first study to report tetrabromobisphenol A (TBBPA) concentrations in multiple tissues of a top marine predator. For the brominated components of Firemaster® flame retardants, TBB concentrations exceeded bis-(2-ethylhexyl)-tetrabromophthalate (TBPH). This pattern may result from recent exposure to commercial mixtures in which TBB exceeds TBPH 4:1 or from differences in perinatal or lactational transfer efficiency of the two compounds. Between the two tissues, lipid-normalized β-HBCD, γ-HBCD, TBB and decabromodiphenyl ethane (DBDPE) concentrations were significantly higher in liver than blubber. This indicates that the bioaccumulation of these chemicals is not simply related to lipid dynamics but may be linked to blood proteins. This study demonstrates that harbor seal pups from this region are contaminated with alternative flame retardants passed to them via placental or lactational transfer. Given the evidence for negative health effects of these chemicals, this contamination adds additional pressure on the first year survival of these young, developing animals.

Potential of metal-organic frameworks to adsorb ethylene for fresh produce active packaging applications

Metal-organic framework (MOF) is an innovative synthetic porous material widely used for gas storage and separation, but its applications for food packaging have barely been investigated. The objective was to evaluate MOFs’ potential to be embedded in packaging films as ethylene adsorbers to control ripening and extend the shelf life of fresh produce during distribution. The potential was evaluated at two levels. The first evaluation was at the MOF powder level, where the ethylene adsorption capacities of eight commercial MOF powders were measured using gas chromatography (GC). As a result, Mg formate MOF (MgF) and Al(OH) fumarate MOF (AlF) were found to have much higher ethylene adsorption capacities than the other six MOFs. Overall, MgF was the best ethylene adsorber due to its stable ethylene adsorption under various temperatures, relative humidities, and ethylene concentrations. The second evaluation was at the packaging film level, where MgF powder was embedded into three different packaging films. The results showed that MgF-embedded LDPE film had higher ethylene adsorption than MgF-embedded PLA and PVA films. Furthermore, a bio-efficacy study confirmed that MgF-embedded LDPE film could effectively delay banana ripening and extended their shelf life. In conclusion, this study indicates that MgF has promising potential as an ethylene adsorber for shelf life extension of bananas and probably other fresh produce.

Efeitos de concentrações de etileno e temperaturas na climatização de bananas de regiões subtropicais

ABSTRACT: Brazil is one of the largest banana producers and despite overall adequate climatic conditions to produce good quality fruit, postharvest handling procedures still are inappropriate. Only a few growers have degreening facilities at their groves. Mostly, bananas are prepared for the market by distributors. Two banana cultivars: Grande Naine (group AAA) and Prata Anã (AAB) were harvested from commercial groves and immediately submitted to degreening procedures in which three temperatures and four ethylene concentrations were evaluated. Bananas were degreened at 24 hour intervals at 13, 17 and 21 ºC with a commercial ethylene source (Banasil®) from which 12.5, 25, 50, and 100mL were placed in an ethylene generator. During the degreening process, ethylene concentrations in the degreening room were monitored for periods up to 6 hours. At the beginning of the degreening process and after three and five more days, epidermal color and pulp firmness were determined. Ethylene concentrations did not influence color changes and ripening processes of both cultivars. A maximum ethylene concentration (1,350 µL L-1) was determined in the degreening room when 100 mL of Banasil® was used at 21ºC. Even with the lowest Banasil® amount, a 90 µL L-1 ethylene peak was determined in the degreening room, enough to ripen adequately both cultivars. Degreening at 13 ºC delayed for two days the ripening of ‘Grande Naine’ bananas. ‘Grande Naine’ reached the fully ripe stage in four days while ‘Prata Anã’ completed ripening after three days. ‘Prata Anã’ bananas are more responsive to ethylene degreening than ‘Grande Naine’ bananas.

Quantification of Ethylene Production in Leaf and Bud Tissue of the Subtropical Tree Crop Litchi (Litchi chinensis Sonn.) Using Gas Chromatography and Flame Ionization Detection.

Ethylene is an important plant hormone that is involved in the regulation of numerous processes in plant development. It also acts as a signaling molecule in response to biotic and abiotic stress conditions. Most studies have investigated ethylene evolution of harvested fruit or small herbaceous plants under controlled conditions, but only a few explored ethylene release in other plant tissues, such as leaves and buds, particularly those of subtropical crops. However, in light of increasing environmental challenges in agriculture (such as temperature extremes, droughts, floods, and high solar radiation), studies on these challenges and on potential chemical treatments for mitigating their effects on plant physiology have become more and more important. Thus, adequate techniques for the sampling and analysis of tree crops are needed to ensure accurate ethylene quantification. As part of a study on ethephon as a mitigating agent to improve litchi flowering under warm winter conditions, a protocol was developed for ethylene quantification in leaf and bud tissue of litchi following ethephon application, taking into account that these plant organs release lower ethylene concentrations than fruit. At sampling, leaves and buds were placed in glass vials of appropriate sizes for the respective plant tissue volumes and allowed to equilibrate for 10 min to release possible wound ethylene before incubating the samples for 3 h at ambient temperature. Thereafter, ethylene samples were aspirated from the vials and analyzed using a gas chromatograph with flame ionization detection, the TG-BOND Q+ column for separation of ethylene, and helium as the carrier gas. Quantification was achieved based on a standard curve derived from an external standard gas calibration with certified ethylene gas. This protocol will also be appropriate for other tree crops with similar plant materials as study foci. It will enable researchers to accurately determine ethylene production in various studies investigating the role of ethylene in general plant physiology or stress-induced plant responses following a range of treatment conditions.

Temporal trends in concentrations of brominated flame retardants in UK foodstuffs suggest active impacts of global phase-out of PBDEs and HBCDD

Global restrictions on use of legacy brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) have generated demand for novel BFRs (NBFRs) as substitutes. Our research group has previously reported decreased concentrations of PBDEs and HBCDD and increased concentrations of NBFRs in UK indoor environments, suggesting that restrictions on PBDEs and HBCDD are exerting an impact. In this study, we analysed UK foodstuffs collected in 2020–21 and compared the BFR concentrations found with those found in similar samples collected in 2015 to investigate whether similar trends in BFR concentrations would be observed. Concentrations of PBDEs and HBCDD isomers detected in our samples had declined by 78–92 % and 59–97 % since the 2015 study, respectively. Moreover, concentrations of NBFRs (dominated by 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE or TBE), and bis(2-ethyl hexyl) tetrabromophthalate (BEH-TEBP or TBPH)) in UK foodstuffs increased significantly (28–1400 %) between 2015 and 2020–21. Combined, these findings suggest that restrictions on use of PBDEs and HBCDD have had a discernible impact on concentrations of these legacy BFRs and their NBFR replacements in UK foodstuffs. Interestingly, given recent reports of a significant increase in concentrations of decabromodiphenyl ethane (DBDPE) in UK house dust between 2014 and 2019, a significant decline (70–84 %) in concentrations of DBDPE was observed in UK foodstuffs.

Influence of vent size and vent burst pressure on vented ethylene-air explosion: Experimental and numerical study

This paper describes the numerical simulation of the vented explosion of ethylene-air mixtures. The influence of concentration, vent size, and vent burst pressure on the vented ethylene-air explosion is investigated by comparing simulation results and experiments. The different phases of external flame propagation are concluded by comparing the experimental photos and the simulation results. The external explosion process is captured by the high-speed camera and simulation. It is found that the unburned mixture expanded to the external atmosphere, which was ignited by the flame. The flow velocity, velocity vector, and turbulence kinetic energy are applied to analyze the mechanism of external flame propagation. The velocity vector is deflected to both sides of the flame front and the reverse flow velocity is captured in the external flow field. The change of ethylene concentration and the venting flow velocity is used to explain the relationship between the pressure rise, chemical reaction rate, and venting flow. Results show that the internal pressure for AV= 0.18 m2 is significantly greater than the internal pressure for AV= 0.55 m2 in this case. The smaller vent size results in higher flow velocity and turbulence kinetic energy inside of the vessel. The vent burst pressure growth promotes the acceleration of the flame front inside of the vessel. The variation curve of ethylene concentration and venting flow velocity has a similar law with different vent burst pressures. The experimental and simulated results can provide technical and theoretical support for the design of gas explosion prevention in the field of process safety and risk engineering.

STUDY OF THE EFFECT OF PLASMA CHEMICAL OXIDATION OF ETHYLENE IMPURITY ON THE EFFICIENCY OF BANANA STORAGE

The effect of the products of plasma chemical reactions (including ozone) on the storage of fruits and berries was studied. Being the product of greatest commercial interest, bananas were selected as the test object. It was shown that the growth of pathogenic microflora is effectively inhibited by the products of plasma chemical reactions. It was shown that the use of a plasma chemical system, due to which ethylene concentration is reduced and ozone concentration is simultaneously maintained at the level of several ppm, could reduce the amount of spoiled products by several times.

Sources and concentrations of methane, ethane, and CO2 in deep aquifers of the Surat Basin, Great Artesian Basin

Understanding the occurrence and sources of methane in aquifers is an international issue, especially in regions that host oil and gas reservoirs. Multi-isotopic studies are important to understand sources and concentrations of dissolved gases in aquifers of basins that host oil and gas extraction; or future CO2, natural gas, hydrogen storage, or compressed air energy storage. The largest artesian basin in the world, the Great Artesian Basin, extends across more than one fifth of Australia providing a fresh water source from various aquifers. The Precipice and Hutton sandstones, aquifers of the Surat Basin in the eastern Great Artesian Basin, are important water resources for town water supply, agriculture, mines, feedlots, and private landholders in Queensland. Overlying and underlying formations host gas extraction. The southern part of the basin in Queensland additionally hosts an oil field, and potential CO2 storage sites, therefore understanding the aquifer gas concentrations, processes and sources is important for fluid management. The dissolved concentrations of methane and ethane in the Hutton Sandstone were up to 96 mg/L and 1 mg/L respectively, and in the Precipice Sandstone methane ranged up to 2100 mg/L and ethane 6.5 mg/L in the southern Surat Basin. Dissolved gas concentrations were measured by an open and closed sampling method, with the concentrations lower from open sampling, and the gas wetness parameter systematically slightly lower. The Hutton Sandstone aquifer dissolved gas isotopic signatures are mainly consistent with primary microbial CO2 reduction generating methane in situ, with fractionation factors indicating acetate fermentation in a few cases. The Hutton Sandstone δ13C-DIC, δ13C-CO2, and δ13C-CH4 have an enrichment trend with increasing depth that indicate a microbial substrate depletion effect. Moonie Oil Field Precipice Sandstone and Evergreen Formation samples plot in the thermogenic region, with enriched δ13C-CO2 indicating microbial biodegradation is also occurring. The Precipice Sandstone aquifer samples have a mixed microbial CO2 reduction and early mature thermogenic gas signature in both isotope cross plots and gas wetness diagrams, with a subset of sampled δ13C-C2H6 and isotope factors consistent with early mature thermogenic gas. A potential historic source of thermogenic gas is the underlying gas reservoir of the Bowen Basin. Large volumes of water are abstracted from these aquifers, hence dissolved gases may contribute to greenhouse gas emissions.

Potential of Released Essential Oils from Active Packaging to Reduce Refrigeration Needs of Fruit and Vegetables

The energy efficiency of fruit and vegetables refrigeration facilities can be increased through the reduction of heat generated by produce (in kWh/kg). Ethylene production in fruit and vegetables is closely linked to their respiration rates. Clean technologies that can reduce ethylene production of fruit and vegetables are needed to relax (increase) the setpoint temperature of cold rooms. The heat produced may be reduced by up to 50% when ethylene concentrations surrounding the produce are reduced from 0.1–1 to 0.001–0.01 μL L−1 during the storage of some vegetables. There is a need to find green alternatives to ethylene scavenging techniques (of high cost and chemical origin) such as, for example, active packaging with encapsulated essential oils. Hence, respiration and ethylene production rates of flat peaches and broccoli were reduced by up to 30–50% with active packaging with essential oils. It would imply a lower produce heat generation of 14–30% with the consequent energy savings in the refrigeration systems of horticultural facilities. Consequently, the potential of essential oils released from active packaging to reduce the energy consumption related to respiratory heat of produce is hereby firstly reviewed and proposed as a clean technology to extend the postharvest life of fruit and vegetables.

Ethylene scavenging film based on low-density polyethylene incorporating pumice and potassium permanganate and its application to preserve avocados

The ethylene scavenging film was prepared to extend the shelf life of fresh fruit and vegetables. This film consisted of low-density polyethylene (LDPE) as matrix, the mixture of pumice and potassium permanganate (KMnO4) (weight ratio: 10 to 1) (pumice acted as the support of KMnO4) as active agents, and maleic anhydride grafted polyethylene (PE-g-MA) as compatibilizer. The study revealed that low loadings of active agents (1 wt% and 3 wt%) were evenly distributed in the LDPE matrix and were beneficial to the improvement of the mechanical property, crystallinity, and gas barrier performance against oxygen and water vapor. In addition, the film (thickness: 60 μm) incorporating 3 wt% active agents had an ethylene scavenging capacity of 7.31 μmol/(25 in2) within 12 d at 25 °C. Further, the ethylene scavenging film with 3 wt% active agents preserved avocados well for 20 d at 25 °C, inhibited the ethylene and carbon dioxide (CO2) concentrations in the packaging headspace, and reduced the flesh firmness loss, while the shelf life of avocados packaged with pure LDPE film was only 10 d.

Combined Jasmonic Acid and Ethylene Treatment Induces Resistance Effect in Faba Bean Plants Against Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae).

Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is a serious invasive pest in China. In this study, we determined whether exogenous jasmonic acid (JA) and ethylene (ET) treatments could induce resistance against F. occidentalis in faba bean plants. First, we investigated the effects of different concentrations of JA or ET alone on F. occidentalis and then assessed the effects of optimal concentrations of JA and ET combined. Our results showed that the optimal concertation of JA was 2 mmol/L and ET was 0.5 mmol/L. JA + ET mixture showed the greatest inhibitory effect in terms of oviposition and feeding. JA with ET was found to induce changes in the activities of lipoxygenase (LOX), allene oxide synthase (AOS), polyphenol oxidase (PPO), 1-aminocyclopropane 1-carboxylic acid synthase (ACS), and trypsin inhibitor (TI). This treatment also activated or inhibited the relative expression levels of LOX1, ACO2, ACS2, and AP2/ERF. Treatment of faba bean plants with JA and ET significantly prolonged F. occidentalis development and adult preoviposition period, significantly reduced per-female oviposition, and altered male longevity and offspring demographic parameters. These results indicate that JA with ET can induce defenses against the growth and development of F. occidentalis in faba bean plants.

CFD modeling of ethylene degradation in gas-phase photocatalytic reactors.

Photocatalytic oxidation is a promising technology to degrade volatile organic compounds. The performance of photocatalytic reactors is affected by the hydrodynamics, radiation transfer, mass transfer and reaction kinetics. Baffles may improve the hydrodynamics. The effect of baffles on heterogeneous photocatalytic oxidation of gas-phase ethylene in three annular reactors is simulated using computational fluid dynamics. ANSYS Fluent is used to solve all governing equations. Baffles can improve the uniformity of flow and prolong the residence time. The residence time of the C-type reactor and B-type reactor is 0.5% greater than the unbaffled reactor. Baffles have little effect on the radiation distribution. The concentric arrangement of lamp and the reactor leads to a radial dominance of radiation. The effect of baffles on the diffusion of ethylene is complex. The effective diffusion coefficient at the catalyst surface in the C-type reactor decreases 9.5% and that in the B-type reactor increases 3% with respect to the unbaffled reactor. The outlet ethylene concentration is 4.19 ppmv for the U-type reactor, 3.93 ppmv for the C-type reactor and 3.62 ppmv for the B-type reactor. The optimal performance in the B-type reactor is due to the large diffusion coefficient of ethylene. The arrangement of baffles should enlarge the effective diffusion coefficient at the catalyst surface as far as possible.

Microwave catalytic conversion of acetylene for co-production of hydrogen and carbon nanotubes

Natural gas conversion to hydrogen and solid carbon can drastically reduce the carbon footprint. Microwave plasma pyrolysis is an emerging process for chemical industries to directly convert methane (CH4), the major component of natural gas, to hydrogen and carbon, which offers benefits such as fast process dynamics, flexibility, and high product yield. However, the formation of unwanted by-products, like acetylene (C2H2), will require extra cost for gas separation. Plasma pyrolysis of CH4 produces large amount of acetylene at downstream, which is currently used mainly for welding. To avoid gas separation and upgrade acetylene from the downstream of methane plasma reactor, a novel approach toward its transformation to carbon nanotubes (CNT) and pure hydrogen (H2) over Ni-based bimetallic catalyst driven by microwave irradiation has been reported in this work. The dominant gas product was hydrogen. Low concentrations of methane, ethane, and ethylene were observed in the product stream. Catalytic acetylene decomposition was carried out at 400 °C over Al2O3 supported Ni catalyst. The results showed that, at 400 °C, acetylene was dehydrogenated to CNT and hydrogen was the dominant gas in product stream over 10Ni-1Pd-Al2O3 catalyst. Characterizations of spent catalysts was conducted using Raman spectroscopy and transmission electron microscopy (TEM) to investigate the properties of carbon deposited over the catalyst during the catalytic acetylene decomposition. The results highlight that methane can be efficiently converted to hydrogen and CNT through 2-step process, microwave plasma and microwave catalytic conversion of intermediate acetylene, operated in a single reactor system driven by microwave.

Infection by Endophytic Epichloë sibirica Was Associated with Activation of Defense Hormone Signal Transduction Pathways and Enhanced Pathogen Resistance in the Grass Achnatherum sibiricum.

Epichloë endophytes can improve the resistance of host grasses to pathogenic fungi, but the underlying mechanisms remain largely unknown. Here, we used phytohormone quantifications, gene expression analysis, and pathogenicity experiments to investigate the effect of Epichloë sibirica on the resistance of Achnatherum sibiricum to Curvularia lunata pathogens. Comparison of gene expression patterns between endophyte-infected and endophyte-free leaves revealed that endophyte infection was associated with significant induction of 1,758 and 765 differentially expressed genes in the host before and after pathogen inoculation, respectively. Functional analysis of the differentially expressed genes suggested that endophyte infection could activate the constitutive resistance of the host by increasing photosynthesis, enhancing the ability to scavenge reactive oxygen species, and actively regulating the expression of genes with function related to disease resistance. We found that endophyte infection was associated with induction of the expression of genes involved in the biosynthesis pathways of jasmonic acid, ethylene, and pipecolic acid and amplified the defense response of the jasmonic acid/ethylene co-regulated EIN/ERF1 transduction pathway and Pip-mediated TGA transduction pathway. Phytohormone quantifications showed that endophyte infection was associated with significant accumulation of jasmonic acid, ethylene, and pipecolic acid after pathogen inoculation. Exogenous phytohormone treatments confirmed that the disease index of plants was negatively related to both jasmonic acid and ethylene concentrations. Our results demonstrate that endophyte infection can not only improve the constitutive resistance of the host to phytopathogens before pathogen inoculation but also be associated with enhanced systemic resistance of the host to necrotrophs after C. lunata inoculation.

Multicomponent vapor-liquid equilibrium measurements and modeling of triethylene glycol, water, and natural gas mixtures at 6.0, 9.0 and 12.5 MPa

Triethylene glycol (TEG) is commonly used for natural gas dehydration, and with subsea processing facilities on the rise, an increasing interest is being shown in complex phase equilibria involving petroleum fluids and polar compounds. In this study, examples of such phase equilibria have been studied. New measurements for multicomponent vapor-liquid equilibrium (VLE) of TEG/Water/Natural Gas systems have been performed at pressures ranging from 6.0 MPa to 12.5 MPa and temperatures in the range 15 °C to 40 °C. Two types of natural gas, a Synthetic Gas (xCH4=0.62) and a Real Gas (xCH4=0.92), were mixed with an aqueous TEG solution, with TEG weight percentages ranging from 95 wt.% to 99 wt.%. Glycol in gas (y1), water in gas (y2), and gas solubility in liquid (xNG) were measured with relative experimental uncertainties below 32%. Since the systems are highly associating, the Cubic-Plus-Association (CPA) equation of state (EoS) was selected to model their phase behavior . Different association schemes (4C, 4F, 5F, 6F and 5C) were tested for TEG, and the classical 4C scheme is shown to perform best. The CPA EoS performed in general terms well, considering the number of components in the systems, the associated complexities, and high measurement uncertainty for such low concentrations (<1 ppm) in the gas phase. Furthermore, the content of N2, CO2, CH4 and ethane were modelled in the liquid phase at various conditions.

Metabolome patterns identify active dechlorination in bioaugmentation consortium SDC-9™.

Ultra-high performance liquid chromatography-high-resolution mass spectrometry (UPHLC-HRMS) is used to discover and monitor single or sets of biomarkers informing about metabolic processes of interest. The technique can detect 1000's of molecules (i.e., metabolites) in a single instrument run and provide a measurement of the global metabolome, which could be a fingerprint of activity. Despite the power of this approach, technical challenges have hindered the effective use of metabolomics to interrogate microbial communities implicated in the removal of priority contaminants. Herein, our efforts to circumvent these challenges and apply this emerging systems biology technique to microbiomes relevant for contaminant biodegradation will be discussed. Chlorinated ethenes impact many contaminated sites, and detoxification can be achieved by organohalide-respiring bacteria, a process currently assessed by quantitative gene-centric tools (e.g., quantitative PCR). This laboratory study monitored the metabolome of the SDC-9™ bioaugmentation consortium during cis-1,2-dichloroethene (cDCE) conversion to vinyl chloride (VC) and nontoxic ethene. Untargeted metabolomics using an UHPLC-Orbitrap mass spectrometer and performed on SDC-9™ cultures at different stages of the reductive dechlorination process detected ~10,000 spectral features per sample arising from water-soluble molecules with both known and unknown structures. Multivariate statistical techniques including partial least squares-discriminate analysis (PLSDA) identified patterns of measurable spectral features (peak patterns) that correlated with dechlorination (in)activity, and ANOVA analyses identified 18 potential biomarkers for this process. Statistical clustering of samples with these 18 features identified dechlorination activity more reliably than clustering of samples based only on chlorinated ethene concentration and Dhc 16S rRNA gene abundance data, highlighting the potential value of metabolomic workflows as an innovative site assessment and bioremediation monitoring tool.

Study on Spontaneous Combustion Characteristics and Oxidation Kinetic Parameters of Lignite at Different Oxygen Concentrations.

The spontaneous combustion parameters of lignite at different oxygen concentrations and temperatures were studied by temperature-programmed oxidation experiments. The characteristic parameters, tendency, oxygen consumption rate, kinetic parameters of oxidation reaction, and heat release intensity of coal's spontaneous combustion were studied. The results show that the variation of export oxygen volume fraction of coal samples under different oxygen concentrations is similar. It has a general s-shaped downward trend. The change trend of the CO concentration of the coal sample export is basically the same at different oxygen concentrations. The CO concentration at the outlet of the coal sample increases with the increase in coal temperature. The CO concentration at 0-200 °C increased exponentially with the coal temperature. The distribution pattern of CO/CO2 ranging from 0 to 320 °C was similar at different oxygen concentrations. With the increase of coal temperature, CO/CO2 first increases and then decreases after reaching the extreme point. The change curve of CH4 with coal temperature under different oxygen concentrations meets the exponential change rule. At different oxygen concentrations, the concentration of ethylene at 0-300 °C changes exponentially, but at 300-400 °C there is no rule. When the oxygen concentration is 20.9%, according to the comprehensive judgment index method and cross temperature method, the comprehensive determination of the spontaneous combustion trend of coal samples is grade II. Under different oxygen concentrations, the oxygen consumption rate of coal increases with the increase of temperature; the oxygen consumption rate increases with the increase of oxygen concentration at the same temperature. The activation energy of coal samples increases with the decrease of oxygen supply concentration or the increase of temperature. The thermal strength of the coal sample is consistent with the change trend of the oxygen consumption rate. The heat release intensity of coal samples conforms to an exponential function and polynomial function in the early and late stages, respectively.

Assessing apple coming from agroclimatic differing locations: a tool for evaluating impact of environmental variation on postharvest

ABSTRACT The potential effect of preharvest environmental variation on the postharvest behaviour of apples (Malus domestica Borkh.) was assessed for ‘Cripps Pink’ variety apples grown in four different agroclimatic locations along the irrigated valley of Central Chile (Llancanao, Malloa, El Radal and El Parrón). The flesh firmness, total soluble solids (TSS), skin colour, internal ethylene concentration (IEC), internal browning (IB) and index of absorbance difference (IAD) were assessed in apples that had been stored at 0.5 and 2°C for 4 and 6 months and correlated with environmental parameters prior to harvest (February). There was notable variation in the IAD, percentage of red-coloured skin, TSS, firmness and IEC among the orchards at both storage temperatures, and both radial and diffuse IB were identified. Further analysis showed that the preharvest environmental conditions were correlated with the evaluated parameters, with five significant correlations (P < 0.05) being found and 63 of the 120 correlations examined having r values above 0.5. These findings indicate that preharvest environmental conditions affected fruit parameters during storage, which has implications under climate change.

Draft genome of Pseudomonas sp. RGM 2987 isolated from Stevia philippiana roots reveals its potential as a plant biostimulant and potentially constitutes a novel species

BackgroundReports on Pseudomonas species associated with Chilean native plants and their diversity are scarce. The draft genome of Pseudomonas sp. RGM 2987 isolated from the rhizosphere of Stevia philippiana, a native Chilean plant from the Altiplano, is presented. ResultsThe assembled genome features 6,161,133 bp, a G+C content of 61.3%, and 5,350 predicted open reading frames. dDDH, and ANIb differences between RGM 2987 and the closest relatives support its classification as a new species within the Pseudomonas genus. Genome mining and functional classification revealed the presence of genes involved in cell function and metabolism as well as plant-growth promotion, including those for indole acetic acid production, phosphate solubilization, and ethylene concentration. ConclusionsThe draft genome of Pseudomonas sp. RGM 2987 provides insights on its phylogeny and classification as a new species and shed light on its potential as a plant-biostimulant, expanding our knowledge on Pseudomonas biodiversity worldwide and, specifically, for those strains associated with native Chilean plants.How to cite: Guerra M, Carrasco-Fernández J, Valdés JH, et al. Draft genome of Pseudomonas sp. RGM 2987 isolated from Stevia philippiana roots reveals its potential as a plant biostimulant and potentially constitutes a novel species. Electron J Biotechnol 2023;61. https://doi.org/10.1016/j.ejbt.2022.10.001.