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The proven world reserves of natural gas are up to 7400 trillion cubic feet, providing cheap and abundant light alkanes as feedstocks for chemical and energy transformation. However, efficient conversion of light alkanes (with inert C–H and C–C bonds) to value-added chemicals with more active functional groups remains a formidable challenge. The conventional catalytic reactions, including steam/dry reforming, oxidative/non-oxidative dehydrogenation, dehydroaromatization, and partial oxidation, have been extensively studied for light alkane conversion, whereas alternative catalytic systems, such as ammonia-assisted reforming and dehydrogenation, have been less studied. Green ammonia from renewable energy has been considered as an important energy carrier; therefore, it could be an important co-reactant for light alkane conversion. This perspective highlights the potential of ammonia reforming (for COx-free H2 and HCN) and dehydrogenation (for acetonitrile and H2) as alternative catalytic processes for efficient light alkane conversion. [ABSTRACT FROM AUTHOR]

The ultimate recovery of shale oil is mostly dependent upon the occurrence and content of free oil within the nano-scaled pore network of shale reservoirs. Due to the nanoporous nature of shale, quantitatively characterizing the occurrence and content of free oil in shale is a formidable undertaking. To tackle this challenge, 12 lacustrine shale samples with diverse organic matter content from the Chang7 Member in the southern Ordos Basin were selected, and the characteristics of free oil occurrence were indirectly characterized by comparing changes in pore structure before and after organic solvent extraction. The free oil enrichment in shale was assessed using the oil saturation index (OSI), corrected oil saturation index (OSIcorr), and percentage of saturated hydrocarbons. The results revealed that slit-like interparticle pores with diameters less than 30 nm are dominant in the Chang7 shale. Conceptual models for the pore structures containing free oil were established for shale with total organic carbon (TOC) content less than 9% and greater than 9%, respectively. Shale samples with TOC content less than 9% exhibit a well-developed pore network characterized by relatively larger pore volume, surface area, and heterogeneity. Conversely, shale samples with TOC content exceeding 9% display a less developed pore network characterized by relatively smaller pore volume, surface area, and heterogeneity. Larger pore volume and lower organic matter abundance favor the enrichment of free oil within the lacustrine shale pore network. This study may have significant implications for understanding oil transport in shales. [ABSTRACT FROM AUTHOR]

Multi element compound-specific stable isotope analysis (ME-CSIA) is a tool to assess (bio)chemical reactions of molecules in the environment based on their isotopic fingerprints. To that effect, ME-CSIA concepts are initially developed with laboratory model experiments to determine the isotope fractionation factors specific for distinct (bio)chemical reactions. Here, we determined for the first time the carbon and hydrogen isotope fractionation factors for the monooxygenation of the short-chain alkanes ethane, propane, and butane. As model organism we used Thauera butanivorans strain Bu-B1211 which employs a non-haem iron monooxygenase (butane monooxygenase) to activate alkanes. Monooxygenation of alkanes was associated with strong carbon and hydrogen isotope effects: εbulkC = -2.95 ± 0.5 ‰ for ethane, -2.68 ± 0.1 ‰ for propane, -1.19 ± 0.18 ‰ for butane; εbulkH = -56.3 ± 15 ‰ for ethane, -40.5 ± 2.3 ‰ for propane, -14.6 ± 3.6 ‰ for butane. This resulted in lambda (Λ ≈ εHbulk/εCbulk) values of 16.2 ± 3.7 for ethane, 13.2 ± 0.7 for propane, and 11.4 ± 2.8 for butane. The results show that ME-CSIA can be used to track the occurrence and impact of monooxygenase-dependent aerobic processes converting short-chain alkanes in natural settings like marine and terrestrial seeps, gas reservoirs, and other geological formations impacted by natural gas. [ABSTRACT FROM AUTHOR]

A novel synthetic protocol for the direct oxidation of alkanes, including cyclic and linear ones, to give ketones and alcohols using hydrogen peroxide as terminal oxidant under ambient conditions is presented. The active catalyst for this challenging transformation is conveniently generated by combination of simple Fe salts with N‐methyl bis(picolylamine) (Me‐bpa). Utilizing picolinic acid as additive leads to improved yields of ketones and alcohols (32‐57 %). The reaction can be conveniently scaled up to multi‐g scale. [ABSTRACT FROM AUTHOR]

One of the most promising strategies for the management of plastic waste is microbial biodegradation, but efficient degraders for many types of plastics are still lacking, including those for polystyrene (PS). Genomics has emerged as a powerful tool for mining environmental microbes that may have the ability to degrade different types of plastics. In this study, we use 16S rRNA sequencing to analyze the microbiomes for multiple PS samples collected from sites with different vegetation in Taiwan to reveal potential common properties between species that exhibit growth advantages on PS surfaces. Phylum enrichment analysis identified Cyanobacteria and Deinococcus-Thermus as being the most over-represented groups on PS, and both phyla include species known to reside in extreme environments and could encode unique enzymes that grant them properties suitable for colonization on PS surfaces. Investigation of functional enrichment using reference genomes of PS-enriched species highlighted carbon metabolic pathways, especially those related to hydrocarbon degradation. This is corroborated by the finding that genes encoding long-chain alkane hydroxylases such as AlmA are more prevalent in the genomes of PS-associated bacteria. Our analyses illustrate how plastic in the environment support the colonization by different microbes compared to surrounding soil. In addition, our results point to the possibility that alkane hydroxylases could confer growth advantages of microbes on PS. [ABSTRACT FROM AUTHOR]

Molecular descriptors are mathematical representations of molecular properties, generated through numerous algorithms. These numerical values are used to quantitatively represent the physical and chemical attributes of molecules. In the field of chemical graph theory, two indices, namely the revised Szeged index and the revised edge-Szeged index, were introduced to characterize molecular properties. The Szeged index (Γ) Sz of a simple connected graph Γ is computed by summing the products of ( ) u n e and ( ) v n e for all edges = e uv in Γ, where ( ) u n e denotes the number of vertices in Γ that are closer to vertex u than to vertex v, and ( ) v n e is defined similarly. In this paper, the role of different variants of Szeged indices in modeling different physical properties of alkanes and benzenoid hydrocarbon is investigated. Their isomer discrimination ability is also examined. In addition, we obtain lower and upper bounds on revised Szeged index, revised edge-Szeged index and the difference between vertex-edge Szeged index and edge-vertex Szeged index of bicyclic graphs. [ABSTRACT FROM AUTHOR]

Paraffin/carbon nanotube (Pa/CNTs) nanocomposite with different CNTs lengths was prepared in order to investigate the change of thermophysical properties of paraffin phase change material (PCM). For this purpose, CNTs were first treated with sulfuric and nitric acids, which reduced the length of CNTs. Then, for complete dispersion of CNTs in paraffin, secondary functionalization was done using dodecylamine and they were added to paraffin with different wt.%. In order to stabilize the shape of paraffin, composites were inserted into graphene aerogel by vacuum impregnation method. Experiments showed that with the increase in the wt.% of CNTs, the thermal conductivity of composites increases, and the highest increase of 26.92% was observed for the composite containing 1 h refluxed CNTs with 1.2 wt.% in solid paraffin. Also, with an increase in the wt.% of CNTs, the latent heat of melting and solidifying of the composite increased, but the specific heat decreased. The absorption capacity of paraffin by graphene aerogel was investigated and the maximum absorption capacity was observed for the composite containing 1 h refluxed CNTs with 0.6 wt.% which showed 36.11% increase compared to the pure paraffin. In addition, by performing the leakage test, it was observed that the GA/Pa/CNTs structure has very good shape stability. [ABSTRACT FROM AUTHOR]

• The solubility of solid CO 2 in alkanes was experimentally investigated. • A novel experimental setup using the cooling curve method was designed, built and verified. • The temperature and pressure of the triple point of CO 2 were measured. • Activity coefficients were determined for the binary mixtures studied. • The Wilson equation was used for modelling the solubility of CO 2. The solid-liquid equilibrium (SLE) of binary systems containing carbon dioxide (R744) and alkanes propane (R290) and isobutane (R600a) was experimentally investigated. A novel experimental setup using the cooling curve method was designed, built and verified, enabling SLE measurements at temperatures down to 173 K. The temperature and pressure of the triple point of carbon dioxide (CO 2) were measured. The results for R744 and the binary mixture of carbon dioxide and propane were in agreement with the available literature data, demonstrating the accuracy of the experimental setup. Activity coefficients were determined for the binary mixtures studied. The Schröder and Wilson equations were used to calculate solubility over various temperatures and compositions. The Wilson model produced a very accurate correlation for the studied non-ideal binary mixtures, while the Schröder equation did not provide satisfactory results. Determined activity coefficients and SLE curves should be useful for the design of low-temperature refrigeration systems operating on carbon dioxide mixtures with low global warming potential. [ABSTRACT FROM AUTHOR]

Hydrogen atom‐donating ability of alkane is a research hotspot and has been extensively studied. In this article, the second‐order rate constants of 20 hydrogen atom transfer (HAT) reactions between aliphatic, benzylic, and allylic alkanes and alkane derivatives with CumO• in acetonitrile at 298 K were studied. The thermo‐kinetic parameter ΔG≠o(XH), bond dissociation free energy ΔGo(XH), and kinetic intrinsic resistance energy ΔG≠XH/X were determined and used to evaluate the H‐donating abilities of these substrates in thermodynamics, kinetics, and HAT reactions. Structure–activity relationships including the factors (electronic, stereoelectronic, and steric effects), introduction of CH3, Ph, or Cl in alkanes, and introduction of N atom in cycloalkane were discussed carefully. The results show that the order of H‐donating abilities is allylic alkanes > cycloalkanes > chain alkanes ≈ benzylic alkanes > haloalkanes. The introduction of CH3, Ph, or Cl in alkanes and the introduction of N atom to the carbon ring reduce ΔGo(XH) but increase ΔG≠XH/X, and ΔG≠o(XH) is the synthesis result of these two parameters. The reliability of ΔG≠o(XH) was verified, and the accuracy and reliability of the parameters were proved. Through the study of this paper, not only the ΔGo(XH), ΔG≠XH/X, and ΔG≠o(XH) of these alkanes and derivatives in HAT reaction can be quantitatively evaluated but also the structure–activity relationship of alkane is clearly researched. [ABSTRACT FROM AUTHOR]

A series of NiM/SiO2 (M = Ce, Co, Cu, Fe, Sn, Zr, Mo) catalysts are prepared and used in the selective hydrodeoxygenation (HDO) of aliphatic acid to produce alkanes with the same number of carbon atoms as the reactant (alkane-Cx). The results indicate the introduction of Mo promotes the hydrodehydration of aliphatic alcohol and suppresses the decarbonylation of aliphatic aldehyde. The selective to alkane-Cx is more than 70% in the case of a complete conversion of aliphatic acid. A mechanism study proves that, due to the higher electronegativity of Mo, electrons transfer from Ni to Mo easily and facilitate the reduction of Mo, and the partially reduced Mo species is favorable for the hydrodehydration of aliphatic alcohol. Meanwhile, the adsorption of alcohol on Mo is more favorable than on the Ni site, and the hydrogen bond between hydroxyl hydrogen and O atoms on the catalyst improves the adsorption stability of aliphatic alcohol. Further COHP analysis indicates that the C-OH bond was activated when alcohol was adsorbed on the Ni5/MoO2 surface, which promoted the hydrodehydration of aliphatic alcohols and improved carbon atom utilization. [ABSTRACT FROM AUTHOR]

In this study, organic geochemical and petrological analyses were conducted on 111 shale samples from a well to understand the retention, intraformational migration and segmented accumulation (shale oil enrichment in different intervals is unconnected) features of shale oil within the organic‐rich shale in the Qingshankou Formation of the Gulong Sag. Our study shows that retained petroleum characteristics in the investigated succession are mainly influenced by three factors: organic richness, intraformational migration and segmented accumulation. Organic matter richness primarily controls the amount of retained petroleum, especially the 'live' component indicated by the S2 value rather than the total organic carbon (TOC) figure alone. The negative expulsion efficiencies determined by mass‐balance calculations of hydrocarbons reveal that petroleum from adjacent organic‐rich intervals migrates into the interval of about 2386–2408 m, which is characterized by high free hydrocarbon (S1), OSI and saturated hydrocarbons content, along with a greater difference in δ13C values between polar compounds (including resins and asphaltenes) and saturated hydrocarbons. The depth‐dependent heterogeneity of carbon isotope ratios (δ13C) of mud methane gas, δ13C of extracts gross composition (SARA), δ13C of kerogen and SARA content of extracts suggest that the studied succession can be subdivided into four intervals. The shale oil sealing enrichment character in each interval is further corroborated by the distinct δ13C values of mud methane gas in different intervals. Due to the migration of petroleum into the 2386–2408 m interval, the S1, OSI and saturated hydrocarbons content of the interval show higher relative values. The maturity of organic matter in the 2471–2500 m interval is at the highest with the smaller size molecular components of the retained petroleum. Thus, favorable 'sweet spots' may be found in the 2386–2408 m interval and the 2471–2500 m interval, according to the experiment results in this study. [ABSTRACT FROM AUTHOR]

Bacterial degradation of crude oil is a promising strategy for reducing the concentration of hydrocarbons in contaminated environments. In the first part of this study, we report the enrichment of two bacterial consortia from deep sediments of the Gulf of Mexico with crude oil as the sole carbon and energy source. We conducted a comparative analysis of the bacterial community in the original sediment, assessing its diversity, and compared it to the enrichment observed after exposure to crude oil in defined cultures. The consortium exhibiting the highest hydrocarbon degradation was predominantly enriched with Rhodococcus (75%). Bacterial community analysis revealed the presence of other hydrocarbonoclastic members in both consortia. In the second part, we report the isolation of the strain Rhodococcus sp. GOMB7 with crude oil as a unique carbon source under microaerobic conditions and its characterization. This strain demonstrated the ability to degrade long-chain alkanes, including eicosane, tetracosane, and octacosane. We named this new strain Rhodococcus qingshengii GOMB7. Genome analysis revealed the presence of several genes related to aromatic compound degradation, such as benA, benB, benC, catA, catB, and catC; and five alkB genes related to alkane degradation. Although members of the genus Rhodococcus are well known for their great metabolic versatility, including the aerobic degradation of recalcitrant organic compounds such as petroleum hydrocarbons, this is the first report of a novel strain of Rhodococcus capable of degrading long-chain alkanes under microaerobic conditions. The potential of R. qingshengii GOMB7 for applications in bioreactors or controlled systems with low oxygen levels offers an energy-efficient approach for treating crude oil-contaminated water and sediments. [ABSTRACT FROM AUTHOR]

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Production of fuel and chemicals from plastic waste is one of the effective ways to upcycle spent plastics, which is an interesting topic and of significance for green and sustainable development. Herein, we demonstrate a highly efficient catalyst, TiO2 nanoparticle supported Ru nanocatalyst (Ru/TiO2), for upcycling polyethylene terephthalate (PET) to alkanes in the presence of H2 and water. Under the optimal conditions (200 °C, 60 bar H2, and small amount of H2O), PET could completely convert into alkanes, dominated with cyclohexane and methane. It was indicated that the strong interaction between the TiO2 support and Ru nanoparticles made electrons flow from the TiO2 support to the Ru nanoparticles, which thus rendered Ru/TiO2 to have ability to simultaneously catalyze PET hydrolysis and intermediate hydrogenation. This work realizes the transformation of PET to alkanes, which provides a promising way to chemically upcycle PET. [ABSTRACT FROM AUTHOR]

The component composition and the quantitative content of compounds distilled with water vapor in the thalli of Cetraria islandica (L.) Ach. harvested in Ukraine were determined using the method of gas chromatography with mass spectrometric detection (GC/MS). 24 compounds distilled with water vapor were identified with the prevalence of fatty acids and their derivatives (57.86 ± 2.00 % of the total compounds), terpenoids and their derivatives (23.57 ± 0.97 % of the total compounds) and acyclic saturated hydrocarbons (10.99 ± 0.45 % of the total compounds). The highest percentage was observed for octadecadienoic (linoleic) acid (20.08 ± 0.67 % of the total compounds), hexadecanoic (palmitic) acid (19.21 ± 0.77 % of the total compounds) and 9,17-octadecadienal (18.57 ± 0.56 % of the total compounds). The presence of 4 monoterpenoids and 6 sesquiterpenoids in the raw material studied was determined for the first time. [ABSTRACT FROM AUTHOR]

Numerous tribological applications, wherein the use of liquid lubricants is infeasible, require adequate dry lubrication. Despite the use of polymers as an effective solution for dry sliding tribological applications, their poor wear resistance prevents the utilization in harsh industrial environment. Different methods are typically implemented to tackle the poor wear performance of polymers, however sacrificing some of their mechanical/tribological properties. Herein, we discussed the introduction of a novel additive, namely microencapsulated phase change material (MPCM) into an advanced polymeric coating. Specifically, paraffin was encapsulated into melamine-based resin, and the capsules were dispersed in an aromatic thermosetting co-polyester (ATSP) coating. We found that the MPCM-filled composite exhibited a unique tribological behavior, manifested as "zero wear", and a super-low coefficient of friction (COF) of 0.05. The developed composite outperformed the state-of-the-art polytetrafluoroethylene (PTFE)-filled coatings, under the experimental conditions examined herein. [ABSTRACT FROM AUTHOR]

The recent leveraging of genome-resolved metagenomics has generated an enormous number of genomes from novel uncultured microbial lineages yet left many clades undescribed. Here, we present a global analysis of genomes belonging to Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. All orders in Binatota encoded the capacity for aerobic methylotrophy using methanol, methylamine, sulfomethanes, and chloromethanes as the substrates. Methylotrophy in Binatota was characterized by order-specific substrate degradation preferences, as well as extensive metabolic versatility, i.e., the utilization of diverse sets of genes, pathways, and combinations to achieve a specific metabolic goal. The genomes also encoded multiple alkane hydroxylases and monooxygenases, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids (lycopene, β- and γ-carotenes, xanthins, chlorobactenes, and spheroidenes) production. Further, the majority of genes involved in bacteriochlorophyll a, c, and d biosynthesis were identified, although absence of key genes and failure to identify a photosynthetic reaction center preclude proposing phototrophic capacities. Analysis of 16S rRNA databases showed the preferences of Binatota to terrestrial and freshwater ecosystems, hydrocarbon-rich habitats, and sponges, supporting their potential role in mitigating methanol and methane emissions, breakdown of alkanes, and their association with sponges. Our results expand the lists of methylotrophic, aerobic alkane-degrading, and pigment-producing lineages. We also highlight the consistent encountering of incomplete biosynthetic pathways in microbial genomes, a phenomenon necessitating careful assessment when assigning putative functions based on a set-threshold of pathway completion.IMPORTANCE A wide range of microbial lineages remain uncultured, yet little is known regarding their metabolic capacities, physiological preferences, and ecological roles in various ecosystems. We conducted a thorough comparative genomic analysis of 108 genomes belonging to the Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. We present evidence that members of the order Binatota specialize in methylotrophy and identify an extensive repertoire of genes and pathways mediating the oxidation of multiple one-carbon (C1) compounds in Binatota genomes. The occurrence of multiple alkane hydroxylases and monooxygenases in these genomes was also identified, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids production. We also report on the presence of incomplete chlorophyll biosynthetic pathways in all genomes and propose several evolutionary-grounded scenarios that could explain such a pattern. Assessment of the ecological distribution patterns of the Binatota indicates preference of its members to terrestrial and freshwater ecosystems characterized by high methane and methanol emissions, as well as multiple hydrocarbon-rich habitats and marine sponges.

Increasing global temperatures have the potential to stimulate decomposition and alter the composition of soil organic matter (SOM). However, questions remain about the extent to which SOM quality and quantity along the soil profile may change under future warming. In this study we assessed how +4 °C whole-soil warming affected the quantity and quality of SOM down to 90 cm depth in a mixed-coniferous temperate forest using biomarker analyses. Our findings indicate that 4.5 years of soil warming led to divergent responses in subsoils (>20 cm) as compared to surface soils. Warming enhanced the accumulation of plant-derived n-alkanes over the whole soil profile. In the subsoil, this was at the expense of plant- and microorganism-derived fatty acids, and the relative abundance of SOM molecular components shifted from less microbially transformed to more transformed organic matter. Fine root mass declined by 24.0 ± 7.5% with warming over the whole soil profile, accompanied by reduced plant-derived inputs and accelerated decomposition of aromatic compounds and plant-derived fatty acids in the subsoils. Our study suggests that warming accelerated microbial decomposition of plant-derived inputs, leaving behind more degraded organic matter. The non-uniform, and depth dependent SOM composition and warming response implies that subsoil carbon cycling is as sensitive and complex as in surface soils.

Increasing global temperatures have the potential to stimulate decomposition and alter the composition of soil organic matter (SOM). However, questions remain about the extent to which SOM quality and quantity along the soil profile may change under future warming. In this study we assessed how +4 °C whole-soil warming affected the quantity and quality of SOM down to 90 cm depth in a mixed-coniferous temperate forest using biomarker analyses. Our findings indicate that 4.5 years of soil warming led to divergent responses in subsoils (>20 cm) as compared to surface soils. Warming enhanced the accumulation of plant-derived n-alkanes over the whole soil profile. In the subsoil, this was at the expense of plant- and microorganism-derived fatty acids, and the relative abundance of SOM molecular components shifted from less microbially transformed to more transformed organic matter. Fine root mass declined by 24.0 ± 7.5% with warming over the whole soil profile, accompanied by reduced plant-derived inputs and accelerated decomposition of aromatic compounds and plant-derived fatty acids in the subsoils. Our study suggests that warming accelerated microbial decomposition of plant-derived inputs, leaving behind more degraded organic matter. The non-uniform, and depth dependent SOM composition and warming response implies that subsoil carbon cycling is as sensitive and complex as in surface soils.

Encoding the complex features of an energy landscape is a challenging task, and often, chemists pursue the most salient features (minima and barriers) along a highly reduced space, i.e., two- or three-dimensions. Even though disconnectivity graphs or merge trees summarize the connectivity of the local minima of an energy landscape via the lowest-barrier pathways, there is much information to be gained by also considering the topology of each connected component at different energy thresholds (or sublevelsets). We propose sublevelset persistent homology as an appropriate tool for this purpose. Our computations on the configuration phase space of n-alkanes from butane to octane allow us to conjecture, and then prove, a complete characterization of the sublevelset persistent homology of the alkane CmH2m+2 Potential Energy Landscapes (PELs), for all m, in all homological dimensions. We further compare both the analytical configurational PELs and sampled data from molecular dynamics simulation using the united and all-atom descriptions of the intramolecular interactions. In turn, this supports the application of distance metrics to quantify sampling fidelity and lays the foundation for future work regarding new metrics that quantify differences between the topological features of high-dimensional energy landscapes. [ABSTRACT FROM AUTHOR]

A lack of comprehensive studies of the C–C bond cleavage in organic molecules hampers the rational design of catalysts for many applications, such as in fuel cells and steam reforming technologies. Employing ethanol on Ir(100) as an example, we studied 14 C–C bond cleavages of various species involved in the ethanol oxidation reaction using density functional theory calculations and used the degree of dehydrogenation (DoDH) of the reactant species as a variable to correlate the C–C bond cleavage barrier and reaction energy. This correlation method was also applied to the dehydrogenation reactions of ethanol on various catalysts, and great insight was obtained. The results show that the C–C cleavage barrier generally decreases with DoDH, with a local minimum around 33.3% DoDH. For reactants having more than 50% DoDH, the C–C cleavage is more ready to take place than the dehydrogenation and can occur at room temperature. Furthermore, the O atom in the reactive species plays a critical role in lowering the C–C bond cleavage barrier. The results provide necessary inputs for kinetic studies of ethanol reactions under operando conditions, where a reaction network beyond the minimum energy pathway is needed. The results will also serve as a benchmark for future studies of the ethanol C–C cleavage on other facets of Ir catalysts or on different catalysts. Furthermore, this work demonstrates that the proposed method opens up a new and effective way of correlating catalytic activities for the C–C bond cleavage involving long-chain alkanes and alcohols. [ABSTRACT FROM AUTHOR]

The microbial conversion of alkanes to methane in hydrocarbon-contaminated environments is an intrinsic bioremediation strategy under anoxic conditions. However, the mechanism of microbial methanogenic alkane degradation is currently unclear. Under ten years of continuous efforts, we obtained a methanogenic n-alkane-degrading (C15–C20) enrichment culture that exhibited sustained improvements in the kinetic properties of methane production. The integrated metagenomic and metatranscriptomic analyses revealed that n-alkanes were mainly attacked by members of Desulfosarcinaceae, Firmicutes, and Synergistetes using the fumarate addition strategy, and were then further degraded in a common effort by Tepidiphilus members. Meanwhile, the abundant members of Anaerolineaceae were mainly responsible for cell debris recycling. However, according to the metatranscriptomic analyses, methane was predicted to be produced mainly via H2-dependent methylotrophic methanogenesis, primarily from necromass-derived trimethylamine mediated by Methanomethyliaceae within the candidate phylum Verstraetearchaeota. These findings reveal that H2-dependent methylotrophic methanogens, as well as methylotrophic methanogens, may play important ecological roles in the carbon cycle of hydrocarbon enriched subsurface ecosystems.

Abstract Background Cyanobacteria and eukaryotic phytoplankton produce long-chain alkanes and generate around 100 times greater quantities of hydrocarbons in the ocean compared to natural seeps and anthropogenic sources. Yet, these compounds do not accumulate in the water column, suggesting rapid biodegradation by co-localized microbial populations. Despite their ecological importance, the identities of microbes involved in this cryptic hydrocarbon cycle are mostly unknown. Here, we identified genes encoding enzymes involved in the hydrocarbon cycle across the salinity gradient of a remote, vertically stratified, seawater-containing High Arctic lake that is isolated from anthropogenic petroleum sources and natural seeps. Metagenomic analysis revealed diverse hydrocarbon cycling genes and populations, with patterns of variation along gradients of light, salinity, oxygen, and sulfur that are relevant to freshwater, oceanic, hadal, and anoxic deep sea ecosystems. Results Analyzing genes and metagenome-assembled genomes down the water column of Lake A in the Canadian High Arctic, we detected microbial hydrocarbon production and degradation pathways at all depths, from surface freshwaters to dark, saline, anoxic waters. In addition to Cyanobacteria, members of the phyla Flavobacteria, Nitrospina, Deltaproteobacteria, Planctomycetes, and Verrucomicrobia had pathways for alkane and alkene production, providing additional sources of biogenic hydrocarbons. Known oil-degrading microorganisms were poorly represented in the system, while long-chain hydrocarbon degradation genes were identified in various freshwater and marine lineages such as Actinobacteria, Schleiferiaceae, and Marinimicrobia. Genes involved in sulfur and nitrogen compound transformations were abundant in hydrocarbon producing and degrading lineages, suggesting strong interconnections with nitrogen and sulfur cycles and a potential for widespread distribution in the ocean. Conclusions Our detailed metagenomic analyses across water column gradients in a remote petroleum-free lake derived from the Arctic Ocean suggest that the current estimation of bacterial hydrocarbon production in the ocean could be substantially underestimated by neglecting non-phototrophic production and by not taking low oxygen zones into account. Our findings also suggest that biogenic hydrocarbons may sustain a large fraction of freshwater and oceanic microbiomes, with global biogeochemical implications for carbon, sulfur, and nitrogen cycles. Video Abstract

CrystEngCommrsc. li/ crystengcomm ISSN 1466- 8033 Volume 26 Number 39 21 October 2024 Pages 5481– 5666 PAPER Manabu Yamada et al. Crystalline thiacalixarene assembly for adsorption ability toward linear and branched C6 alkane vapor isomers ChemComm Uncover new possibilities with outstanding preliminary research Original discoveries, fuelling every step of scientific progress Registered charity number: 207890 rsc. li/ chemcomm Fundamental questions Elemental answers [Extracted from the article]

Studying the fates of oil components and their interactions with ecological systems is essential for developing comprehensive management strategies and enhancing restoration following oil spill incidents. The potential expansion of Kazakhstan’s role in the global oil market necessitates the existence of land-specific studies that contribute to the field of bioremediation. In this study, a set of experiments was designed to assess the growth and biodegradation capacities of eight fungal strains sourced from Kazakhstan soil when exposed to the hydrocarbon substrates from which they were initially isolated. The strains were identified as Aspergillus sp. SBUG-M1743, Penicillium javanicum SBUG-M1744, SBUG-M1770, Trichoderma harzianum SBUG-M1750 and Fusarium oxysporum SBUG-1746, SBUG-M1748, SBUG-M1768 and SBUG-M1769 using the internal transcribed spacer (ITS) region. Furthermore, microscopic and macroscopic evaluations agreed with the sequence-based identification. Aspergillus sp. SBUG-M1743 and P. javanicum SBUG-M1744 displayed remarkable biodegradation capabilities in the presence of tetradecane with up to a 9-fold biomass increase in the static cultures. T. harzianum SBUG-M1750 exhibited poor growth, which was a consequence of its low efficiency of tetradecane degradation. Monocarboxylic acids were the main degradation products by SBUG-M1743, SBUG-M1744, SBUG-M1750, and SBUG-M1770 indicating the monoterminal degradation pathway through β-oxidation, while the additional detection of dicarboxylic acid in SBUG-M1768 and SBUG-M1769 cultures was indicative of the fungus’ ability to undertake both monoterminal and diterminal degradation pathways. F. oxysporum SBUG-M1746 and SBUG-M1748 in the presence of cyclohexanone showed a doubling of the biomass with the ability to degrade the substrate almost completely in shake cultures. F. oxysporum SBUG-M1746 was also able to degrade cyclohexane completely and excreted all possible metabolites of the degradation pathway. Understanding the degradation potential of these fungal isolates to different hydrocarbon substrates will help in developing effective bioremediation strategies tailored to local conditions.

Force fields for four small molecules, methane, ethane, methanol, and ethanol, were created by force matching MP2 gradients computed with triple-zeta-quality basis sets using the Adaptive Force Matching method. Without fitting to any experimental properties, the force fields created were able to predict hydration free energies, enthalpies of hydration, and diffusion constants in excellent agreements with experiments. The root mean square error for the predicted hydration free energies is within 1 kJ/mol of experimental measurements of Ben-Naim et al. [J. Chem. Phys. 81(4), 2016–2027 (1984)]. The good prediction of hydration free energies is particularly noteworthy, as it is an important fundamental property. Similar hydration free energies of ethane relative to methane and of ethanol relative to methanol are attributed to a near cancellation of cavitation penalty and favorable contributions from dispersion and Coulombic interactions as a result of the additional methyl group. [ABSTRACT FROM AUTHOR]

Using molecular dynamics simulation of octane (C8) and nonadecane (C19), we probe the mechanism of n-alkane surface freezing, the appearance of a crystalline monolayer above the liquid at a temperature Tsf above the bulk freezing point Tf. Formation of a crystalline monolayer occurs robustly in these systems. When Tf > Tsf, the surface frozen phase is metastable with respect to the solid but persists for long periods for study in simulations. Surface freezing of both C8 and C19 is driven by significant energy-lowering when alkane chains become ordered along the surface normal, and we elucidate the origins of this phenomenon. The degree of configurational disorder in the surface frozen layer relative to the solid is much larger for C8 compared to C19. From the Gibbsian viewpoint, we extract the excess energy and entropy of the liquid and surface frozen phases. We also consider the surface frozen layer as an intervening third phase, the viewpoint taken in previous theoretical analyses. Here, we find significantly increased entropy of the surface frozen phase of C8 associated with configurational disorder, while the energy and entropy of the surface frozen phase of C19 are marginally different from the bulk solid. Finally, by combining our previously determined solid–vapor surface free energies of C8 and C19 with liquid–vapor surface tensions from this work, we eliminate wetting as a possible mechanism for C8 surface freezing, but it remains a possibility for C19. We analyze the molecular structure of the liquid, surface frozen, and solid surfaces and discuss its relevance to thermodynamic properties. [ABSTRACT FROM AUTHOR]

The model-potential approach previously developed by the authors to study positron interactions with molecules is used to calculate the positron binding energy for n-alkanes (CnH2n+2) and the corresponding cycloalkanes (CnH2n). For n-alkanes, the dependence of the binding energy on the conformation of the molecule is investigated, with more compact structures showing greater binding energies. As a result, thermally averaged binding energies for larger alkanes (n ≳ 9) show a strong temperature dependence in the range of 100 K–600 K. This suggests that positron resonant annihilation can be used as a probe of rotational (trans-gauche) isomerization of n-alkanes. In particular, the presence of different conformers leads to shifts and broadening of vibrational Feshbach resonances in the annihilation rate, as observed with a trap-based low-energy positron beam. [ABSTRACT FROM AUTHOR]

We perform molecular dynamics simulations to model density as a function of temperature for 74 alkanes with 5–10 carbon atoms and non-equilibrium molecular dynamics simulations in the NVT ensemble to model the kinematic viscosity of 10 linear alkanes as a function of molecular weight, pressure, and temperature. To model density, we perform simulations in the NPT ensemble before applying correction factors to exploit the systematic error in the SciPCFF force field and compare the results to experimental values, obtaining an average absolute deviation of 3.4 g l at 25 °C and of 7.2 g l at 100 °C. We develop a sampling algorithm that automatically selects good shear rates at which to perform viscosity simulations in the NVT ensemble and use the Carreau model with weighted least squares regression to extrapolate Newtonian viscosity. Viscosity simulations are performed at experimental densities and show an excellent agreement with experimental viscosities, with an average percent deviation of −1% and an average absolute percent deviation of 5%. Future plans to study and apply the sampling algorithm are outlined. [ABSTRACT FROM AUTHOR]

Exploring the behavior of hydrocarbon under pressure is important for understanding its role in planetary sciences and also for exploring novel organic chemistry. In this study, we explored the high-pressure behavior of a linear-chain hydrocarbon, tricosane (C23H48), using Raman spectroscopy. We compressed tricosane up to 23 GPa and did not find any evidence for pressure-induced amorphization within the conditions explored in this study. Upon compression, we observe new modes in the low energy region 100–300 cm−1. In order to understand the appearance of these new modes at high pressures, we used complementary ab initio calculations and explored the effect of chain configurations (linear and bent) on the predicted Raman spectra. We find that these new modes observed at higher pressures are better explained by bent configuration of tricosane chains. Thus, based on high-pressure Raman spectra, it is very likely that a linear chain of tricosane is bent under pressure, i.e., it undergoes a pressure-induced trans-gauche transformation. It is also likely that such bent regions (i.e., kinks) will act as sites along which large chain hydrocarbons could dissociate into smaller chain lengths at extreme conditions relevant to the interiors of Jovian planets. [ABSTRACT FROM AUTHOR]

An efficient representation of molecular correlated wave functions is proposed, which features regularization of the Coulomb electron–electron singularities via the F12-style explicit correlation and a pair-natural orbital factorization of the correlation components of the wave function expressed in the real space. The pair-natural orbitals are expressed in an adaptive multiresolution basis and computed directly by iterative variational optimization. The approach is demonstrated by computing the second-order Moller–Plesset energies of small- and medium-sized molecules. The resulting MRA-PNO-MP2-F12 method allows for the first time to compute correlated wave functions in a real-space representation for systems with dozens of atoms (as demonstrated here by computations on alkanes as large as C10H22), with precision exceeding what is achievable with the conventional explicitly correlated MP2 approaches based on the atomic orbital representations. [ABSTRACT FROM AUTHOR]

We have measured the Soret coefficients of three halobenzenes—fluoro-, chloro-, and bromobenzene—in n-alkanes ranging from hexane to hexadecane over the entire composition range at a temperature of 25 °C. With these new results, two semi-empirical models for the Soret effect, which are based on the pseudo-isotope effect and on the single-component thermophobicities, could significantly be expanded and put on a broader common experimental basis. In particular, for the longer alkanes, above decane, a simplified version of the pseudo-isotope effect yields a good description. In the dilute limit, the agreement of the chemical contributions to the Soret coefficient is perfect, but there are some unexplained systematic deviations at finite concentrations. We have used these Soret coefficients, together with the measurements of 1-bromonaphthalene in the n-alkanes, to expand the database for the thermophobicities of equimolar binary mixtures. Due to a vanishing mixing term in symmetric mixtures, the heats of transport computed from the Soret coefficients can be considered as differences in additive single component properties, the thermophobicities. This allows an ordering of the substances according to these numbers. In a binary mixture, the component with the higher thermophobicity migrates toward the cold side. With the new measurements, the database now contains 24 compounds with 107 out of 276 possible binary mixtures measured. [ABSTRACT FROM AUTHOR]

The feasibility of the compression of localized virtual orbitals is explored in the context of intramolecular long-range dispersion interactions. Singular value decomposition (SVD) of coupled cluster doubles amplitudes associated with the dispersion interactions is analyzed for a number of long-chain systems, including saturated and unsaturated hydrocarbons and a silane chain. Further decomposition of the most important amplitudes obtained from these SVDs allows for the analysis of the dispersion-specific virtual orbitals that are naturally localized. Consistent with previous work on intermolecular dispersion interactions in dimers, it is found that three important geminals arise and account for the majority of dispersion interactions at the long range, even in the many body intramolecular case. Furthermore, it is shown that as few as three localized virtual orbitals per occupied orbital can be enough to capture all pairwise long-range dispersion interactions within a molecule. [ABSTRACT FROM AUTHOR]

Glycine-glucolipid, a glycolipid, is natively synthesized by the marine bacterium Alcanivorax borkumensis SK2. A. borkumensis is a Gram-negative, non-motile, aerobic, halophilic, rod-shaped γ-proteobacterium, classified as an obligate hydrocarbonoclastic bacterium. Naturally, this bacterium exists in low cell numbers in unpolluted marine environments, but during oil spills, the cell number significantly increases and can account for up to 90% of the microbial community responsible for oil degradation. This growth surge is attributed to two remarkable abilities: hydrocarbon degradation and membrane-associated biosurfactant production. This study aimed to characterize and enhance the growth and biosurfactant production of A. borkumensis, which initially exhibited poor growth in the previously published ONR7a, a defined salt medium. Various online analytic tools for monitoring growth were employed to optimize the published medium, leading to improved growth rates and elongated growth on pyruvate as a carbon source. The modified medium was supplemented with different carbon sources to stimulate glycine-glucolipid production. Pyruvate, acetate, and various hydrophobic carbon sources were utilized for glycolipid production. Growth was monitored via online determined oxygen transfer rate in shake flasks, while a recently published hyphenated HPLC-MS method was used for glycine-glucolipid analytics. To transfer into 3 L stirred-tank bioreactor, aerated batch fermentations were conducted using n-tetradecane and acetate as carbon sources. The challenge of foam formation was overcome using bubble-free membrane aeration with acetate as the carbon source. In conclusion, the growth kinetics of A. borkumensis and glycine-glucolipid production were significantly improved, while reaching product titers relevant for applications remains a challenge.

Introduction: Adjuvants can effectively enhance the utilization rate of pesticides, but the application of adjuvants in plant growth regulators is rarely studied. Methods: This work explored the effects of adjuvants dioctyl sulfosuccinate sodium salt (AOT) and methyl oleate (MO) on lime sulfur (LS), especially the drop behavior on flower and paraffin surface. Results: The results showed that the addition of AOT and AOT+MO can significantly reduce the static and dynamic surface tension of LS from 72mN/m to 28mN/m and 32mN/m respectively, and increase the spreading factor from 0.18 to 1.83 and 3.10 respectively, reduce the bounce factor from 2.72 to 0.37 and 0.27 respectively. The fluorescence tracer test showed that the addition of adjuvants could promote the spreading and permeation of droplets. The field test results revealed that the flower thinning rate of adjuvant and non-adjuvant were 80.55% and 54.4% respectively, and the flower thinning effect of adding adjuvant was the same as that of artificial which the flower thinning rate was 84.77%. The quality of apples treated with adjuvants was similar to that treated with artificial, and the weight of single fruit increased by 24.08% compared with CK (spray water). Discussion: The application of tank-mixture adjuvant could reduce the dosage of LS for thinning agent application, improve apple's quality, and decrease labor cost and improve the economic benefits of fruit planting and the environmental benefits of plant growth regulators. [ABSTRACT FROM AUTHOR]

Copyright of Oilfield Chemistry is the property of Sichuan University, Oilfield Chemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herein, we report a green and sustainable electrochemical strategy for α-alkylation of tertiary amines with halogenated alkanes under undivided electrolytic conditions. A Barbier–Grignard-type reaction at the cathode produces an organozinc reagent that reacts with an iminium ion produced at the anode to provide the α-alkylated amine. The reaction proceeds under mild reaction conditions with wide-ranging functional-group and substrate compatibilities, affording the products in good yields. More importantly, convergent pair electrolysis, an ideal but challenging electrochemical technique, is effectively utilized in this reaction system. Detailed mechanistic study indicated that an imine ion intermediate is involved in the reaction process. [ABSTRACT FROM AUTHOR]

Advanced functional fibers, which can endow common textiles with specific functionalities by traditional weaving processes without losing their basic features, including flexibility, breathability, and wash ability, are desired in flexible and wearable devices. However, the performance of piezoelectric wire sensors in previous studies has been unsatisfactory, especially in harsh environments. This article reports a thermally stable thin piezoelectric fiber with a lotus root structure, consisting of a core electrode, a perfluoroalkoxy alkane piezoelectret layer, a ground/shield electrode, and an outer jacket. The specific structure together with a small diameter of 0.4 mm makes such fiber sensors very flexible and suitable to be woven into clothing or integrated into thin substrates. The piezoelectric sensitivity of the fibers, up to 1.50 pC/N at 0.25 MPa, is achieved and very stable in a broad operating temperature ranging from −79 to 150 °C, showing a promising application prospect in extreme environments. The fabrics and socks woven with such fibers can detect various motions, demonstrating their practicability in smart clothing for ordinary applications such as rehabilitation and gait analysis and special purposes such as functional clothing for astronauts and firefighters who may expose to very low- or high-temperature environments. [ABSTRACT FROM AUTHOR]

The Al ions released from the sacrificial Al anode could combine with chloride anion to regenerate the Lewis acid AlCl SB 3 sb . To further illustrate the practicability of this deoxygenation method, the electroreductive deoxygenation of ketones was explored. To clarify the mechanism of the deoxygenation reaction, cyclic voltammetry (CV) experiments were explored to determine the role of AlCl SB 3 sb . Keywords: organic electrosynthesis; deoxygenation; alcohols; reduction EN organic electrosynthesis deoxygenation alcohols reduction 2993 2998 6 08/31/23 20230915 NES 230915 Graph Alcohol is a naturally abundant moiety found in natural products, bioactive molecules, and functional materials. [Extracted from the article]

Maternal taurine supplementation has been shown to exert protective effects following a maternal obesogenic diet on offspring growth and metabolism. However, the long-term effects of maternal cafeteria diet on adiposity, metabolic profile, and hepatic gene expression patterns following supplementation of taurine in adult offspring remains unclear. In this study, we hypothesized that exposure to maternal taurine supplementation would modulate the effects of maternal cafeteria diet by reducing adiposity and hepatic gene expression patterns involved in lipid metabolism in adult offspring. Female Wistar rats were fed a control diet, control diet supplemented with 1.5% taurine in drinking water, cafeteria diet (CAF) or CAF supplemented with taurine (CAFT) from weaning. After 8 weeks, all animals were mated and maintained on the same diets during pregnancy and lactation. After weaning, all offspring were fed with control chow diet until the age of 20 weeks. Despite similar body weights, CAFT offspring had significantly lower fat deposition and body fat when compared with CAF offspring. Microarray analysis revealed that genes (Akr1c3, Cyp7a1, Hsd17b6, Cd36, Acsm3 , and Aldh1b1) related to steroid hormone biosynthesis, cholesterol metabolism, peroxisome proliferator-activated receptor signaling pathway, butanoate metabolism, and fatty acid degradation were down-regulated in CAFT offspring. The current study shows that exposure to maternal cafeteria diet promoted adiposity and taurine supplementation reduced lipid deposition and in both male and female offspring and led to alterations in hepatic gene expression patterns, reducing the detrimental effects of maternal cafeteria diet. Long-term effects of maternal cafeteria diet and taurine are decreased fat deposition and hepatic gene expression of Akr1c3, Cyp7a1, Hsd17b6, Acsm3 , and Aldh1b1 in rat offspring. Abbreviations: Acsm3, acyl-CoA synthetase medium-chain family member 3; Aldh1b1, Aldehyde dehydrogenase 1 family, member B1; Akr1c3, aldo-keto reductase family 1, member C3; Cyp7a1, cytochrome P450, family 7, subfamily a, polypeptide 1; Hsd17b6, Hydroxysteroid (17-beta) dehydrogenase 6; PPAR, peroxisome proliferator-activated receptor. [Display omitted] [ABSTRACT FROM AUTHOR]

Dehydrogenation of saturated N‐heterocycles and hydrocarbons provides an important route to corresponding aromatic compounds. Herein, an efficient and selective MnAlO‐catalyzed aerobic oxidative dehydrogenation of five‐ and six‐membered N‐heterocycles, imines and hydrocarbons is presented. The reaction features excellent yields of the products, mild reaction conditions, readily available and reusable catalyst. Various N‐heterocycles and hydrocarbons can be tolerated by the reaction system and transformed to the corresponding aromatic counterparts. Mechanistic studies revealed that the reaction proceeds mainly through an electron transfer mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Intracrystalline Pt nanoparticles lead to higher n-heptane isomerization rates (per H+). • These rate enhancements (and selectivity trends) do not reflect chemical origins. • Such rate and selectivity trends reflect intradomain reaction-transport interplays. • A diffusion-convection-reaction model is developed to describe the observed trends. Bifunctional isomerization and β -scission of alkanes involve kinetic cascades mediated by alkenes that form at a (de)hydrogenation function that resides within diffusion distances from the acid function at which alkenes react. Such distances matter for reactivity and selectivity, especially within voids of molecular dimensions, because of gradients in reactant and product concentrations within acid domains. Dispersing Pt nanoparticles within zeolite crystals places the two functions within nanometer distances, instead of the larger distances prevalent when the Pt function resides outside zeolite crystals. Such intimacy leads to higher n-heptane conversion turnover rates (per H+) and shifts selectivities towards primary isoalkanes, most evidently on medium-pore zeolites (MFI), because confinement effects lead to slower diffusion and higher intrinsic H+ reactivity than in larger-pore zeolites, and for shorter Pt-H+ distances, which define the dimensions of the acid domain. Intracrystalline Pt nanoparticles do not affect the number or intrinsic properties of the metal or acid functions or introduce reaction channels mediated by more reactive (but less abundant) diene intermediates, as demonstrated here by reactive probes of metal (CO oxidation) and acid (CH 3 OH dehydration) functions, infrared spectra of OH groups and chemisorbed CO, kinetic effects of H 2 pressures, and transition state energies from density functional theory. Metal-acid distances influence the requisite kinetic cascades instead through the formation and scavenging of reactants and intermediates along the isomerization-scission sequence in the presence of significant gradients in their concentrations. Reaction-transport treatments show that such gradients weaken with increasing intracrystalline densities of Pt nanoparticles (and consequent smaller acid domains), thus circumventing isoalkene equilibration and local thermodynamic bottlenecks through hydrogenation of the primary isoalkene products. Such scavenging inhibits the formation of dimethylpentenes, which act as required precursors to β -scission products, leading to higher selectivities to isoalkanes as Pt-H+ distances decrease. These data and reaction-transport formalisms resolve persistent controversies about the chemical or diffusional origins of rate and selectivity consequences of the location of a metal function. They demonstrate the essential, but often neglected, need to determine the precise location of the metal function and to develop reaction-transport treatments to describe rates and selectivity in bifunctional metal-acid catalysis. [ABSTRACT FROM AUTHOR]

Mineral oil hydrocarbons (MOH) are composed of saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH). Due to the complexity of the MOH composition, their complete chemical characterisation is not possible. MOSH accumulation is observed in various tissues, with species‐specific differences. Formation of liver epithelioid lipogranulomas and inflammation, as well as increased liver and spleen weights, are observed in Fischer 344 (F344) rats, but not in Sprague–Dawley (SD) rats. These effects are related to specific accumulation of wax components in the liver of F344 rats, which is not observed in SD rats or humans. The CONTAM Panel concluded that F344 rats are not an appropriate model for effects of MOSH with wax components. A NOAEL of 236 mg/kg body weight (bw) per day, corresponding to the highest tested dose in F344 rats of a white mineral oil product virtually free of wax components, was selected as relevant reference point (RP). The highest dietary exposure to MOSH was estimated for the young population, with lower bound–upper bound (LB–UB) means and 95th percentiles of 0.085–0.126 and 0.157–0.212 mg/kg bw per day, respectively. Considering a margin of exposure approach, the Panel concluded that the present dietary exposure to MOSH does not raise concern for human health for all age classes. Genotoxicity and carcinogenicity are associated with MOAH with three or more aromatic rings. For this subfraction, a surrogate RP of 0.49 mg/kg bw per day, calculated from data on eight polycyclic aromatic hydrocarbons, was considered. The highest dietary exposure to MOAH was also in the young population, with LB–UB mean and 95th percentile estimations of 0.003–0.031 and 0.011–0.059 mg/kg bw per day, respectively. Based on two scenarios on three or more ring MOAH contents in the diet and lacking toxicological information on effects of 1 and 2 ring MOAH, a possible concern for human health was raised. This publication is linked to the following EFSA Journal article: https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2023.p210901 [ABSTRACT FROM AUTHOR]

This study aimed to develop a technically better and economically affordable phase change material (PCM) for thermal energy storage (TES) applications. In this context, the influence of low mass fraction impregnation of graphene oxide nanoparticles (GONP) in the thermal properties of paraffin has been investigated. GONP has been synthesized by modifying Hummer's method. The morphological, structural and thermal properties of prepared composite PCM have been analysed by different characterization techniques like XRD, FTIR, scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry and laser flash analyzer (LFA). The average latent heat storage capacity of the prepared paraffin/GONP composite is obtained as ~161.34 J g−1, which shows a 27.2% loss in latent heat compared to pure paraffin (225.50 J g−1). Also, only ~3% loss in latent heat has been noticed after 250 thermal cycles, suggesting excellent thermal durability. On the other hand, LFA results showed a 45% increment in thermal conductivity of the paraffin/GONP composite compared to pure paraffin (0.22 Wm−1 K−1). Moreover, the lower mass fraction paraffin/GONP composite showed equivalent latent heat enthalpy and acceptable enhanced thermal conductivity compared to higher mass fraction impregnation. Therefore, the paraffin/GONP composite PCM could be technically and economically more favourable for TES application. [ABSTRACT FROM AUTHOR]

For decades, researchers have focused on containing terrestrial oil pollution. The heterogeneity of soils, with immense microbial diversity, inspires them to transform pollutants and find cost-effective bioremediation methods. In this study, the mycoremediation potentials of five filamentous fungi isolated from polluted soils in Kazakhstan were investigated for their degradability of n-alkanes and branched-chain alkanes as sole carbon and energy sources. Dry weight estimation and gas chromatography–mass spectrometry (GC-MS) monitored the growth and the changes in the metabolic profile during degradation, respectively. Penicillium javanicum SBUG-M1741 and SBUG-M1742 oxidized medium-chain alkanes almost completely through mono- and di-terminal degradation. Pristane degradation by P. javanicum SBUG-M1741 was >95%, while its degradation with Purpureocillium lilacinum SBUG-M1751 was >90%. P. lilacinum SBUG-M1751 also exhibited the visible degradation potential of tetradecane and phytane, whereby in the transformation of phytane, both the mono- and di-terminal degradation pathways as well as α- and ß-oxidation steps could be described. Scedosporium boydii SBUG-M1749 used both mono- and di-terminal degradation pathways for n-alkanes, but with poor growth. Degradation of pristane by Fusarium oxysporum SBUG-M1747 followed the di-terminal oxidation mechanism, resulting in one dicarboxylic acid. These findings highlight the role of filamentous fungi in containing oil pollution and suggest possible degradation pathways. [ABSTRACT FROM AUTHOR]

During high-temperature pulse pyrolysis of acyclic butanes and pentanes under adiabatic compression conditions, cyclopropane, a stressed cyclic hydrocarbon, was found among the reaction products in small quantities for the first time. The analysis of the reaction products was performed by gas chromatography using three capillary columns of different polarity, selectivity and sufficient efficiency. The identification of reaction products, including cyclopropane, was performed using retention times of individual substances and model mixtures, as well as comparing chromatograms with reference chromatograms from the literature and the ScanView Application Database. It was shown that the chromatographic peak attributed to cyclopropane could not be a ghost peak. Additional confirmation of this conclusion was obtained in a series of experiments on the pyrolysis of n-butane at a reduced initial temperature of the adiabatic compression reactor (from 120 °C to 50 °C) and a modified mode of GC analysis. Cyclopropane yields as a function of maximum temperature have a bell-shaped asymmetric dependence. The maximum value of the yield of cyclopropane increases with the transition from normal alkanes to isoalkanes, and from pentanes to butanes; for n-pentane, 0.009 wt. %, and for isobutene, ≈0.017 wt. %. During the pulse pyrolysis of isobutane, n-butane, isopentane and n-pentane, cyclopropane is not a primary product. Further theoretical and experimental studies are needed to establish the mechanism of cyclopropane formation during pyrolysis of C4–C5 acyclic alkanes. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)