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Intermediate-volatility organic compounds (IVOCs) serve as pivotal precursors to secondary organic aerosol (SOA). They are highly susceptible to substantial wall losses both in indoor environments and within smog chambers even with Teflon walls. Accurately characterizing the wall loss effects of IVOCs is thus essential for simulation studies aiming to replicate their atmospheric behaviors in smog chambers to ensure precise modeling of their physical and chemical processes, including SOA formation, yet a comprehensive understanding of the wall loss behavior of IVOCs remains elusive. In this study, we conducted a thorough characterization of wall losses for typical intermediate-volatility hydrocarbon compounds, including eight normal alkanes (n-alkanes) and eight polycyclic aromatic hydrocarbons (PAHs), using the smog chamber with a 30 m3 Teflon reactor. Changes in the concentrations of gaseous IVOCs with the chamber were observed under dark conditions, and the experimental data were fitted to the reversible gas–wall mass transfer theory to determine the key parameters such as the wall accommodation coefficient (αw) and the equivalent organic aerosol concentration (Cw) for different species. Our results reveal that Cw values for these hydrocarbon IVOCs range from 0.02 to 5.41 mg/m3, which increase with volatility for the PAHs but are relative stable for alkanes with an average of 3.82 ± 0.92 mg/m3. αw span from 1.24 × 10−7 to 1.01 × 10−6, with the values for n-alkanes initially showing an increase followed by a decrease as carbon numbers rise and volatility decreases. The average αw for n-alkanes and PAHs are 3.34 × 10−7 and 6.53 × 10−7, respectively. Our study shows that IVOCs exhibit different loss rates onto clean chamber walls under dry and dark conditions, with increasing rate as the volatility decreases. This study demonstrates how parameters can be acquired to address wall losses when conducting smog chamber simulation on atmospheric processes of IVOCs. [ABSTRACT FROM AUTHOR]

The dimorphic yeast Yarrowia lipolytica possesses an excellent ability to utilize n-alkane as a sole carbon and energy source. Although there are detailed studies on the enzymes that catalyze the reactions in the metabolic processes of n-alkane in Y. lipolytica, the molecular mechanism underlying the incorporation of n-alkane into the cells remains to be elucidated. Because Y. lipolytica adsorbs n-alkane, we postulated that Y. lipolytica incorporates n-alkane through direct interaction with it. We isolated and characterized mutants defective in adsorption to n-hexadecane. One of the mutants harbored a nonsense mutation in MAR1 (Morphology and n-alkane Adsorption Regulator 1) encoding a protein containing a high mobility group box. The deletion mutant of MAR1 exhibited defects in adsorption to n-hexadecane and filamentous growth on solid media, whereas the strain that overexpressed MAR1 exhibited hyperfilamentous growth. Fluorescence microscopic observations suggested that Mar1 localizes in the nucleus. RNA-sequencing analysis revealed the alteration of the transcript levels of several genes, including those encoding transcription factors and cell surface proteins, by the deletion of MAR1. These findings suggest that MAR1 is involved in the transcriptional regulation of the genes required for n-alkane adsorption and cell morphology transition. [ABSTRACT FROM AUTHOR]

[Objective] Since the Paleogene, with the uplift of the Qinghai-Tibetan Plateau and the large-scale thrust and strike-slip of the strata, many inland basins were formed in the northern part of the Qinghai-Tibetan Plateau. Be-cause of their particular location, the evolution of paleoclimate and paleo-vegetation in the basins is very significant for clarifying the climatic evolution in the Paleogene in Eurasia. [Methods] In this study, the evolution history of paleoclimate and paleo-vegetation in the Nangqian Basin in central and eastern Qinghai-Tibetan Plateau (51.8-37.5 Ma) was reconstructed from biomarkers and total organic carbon (TOC). [Results and Conclusions] The evolution history of Paleogene climate index in Nangqian Basin is in three stages, each with different changes of sedimentary facies. Stage I (51.8-46.4 Ma) : The sedimentary facies are mainly fluvial and short-term lacustrine, with lower CPI and TOC values and higher Paq values. ACL and nC27/nC3, show an obvious change trend in this period, which may have been affected by the mixing of terrestrial sediments brought by rivers. Most of the main peak carbon was nC22 and nC23; the vegetation type was predominantly woody plants, and the climate was relatively humid. Stage II (46.4-42.7 Ma): The Paq value and nC27/nC3, ratio gradually decreased, ACL gradually increased, the carbon number of the main peak gradually changed from low to medium or high, the vegetation gradually changed from woody to herbaceous plants, and the climate gradually became drought alternating with wet conditions. Stage III (42.7-37.5 Ma) : Paq, nC27/nC3, and ACL changed little, the carbon number of the main peak increased significantly, n-alkanes with high carbon numbers increased significantly, and drought conditions increased. TOC also significantly increased, reflecting increasing total vegetation productivity, which may have been a response to the warm Middle Eocene Climatic Optimum (MECO). In addition, from comparisons with previous reports of climate change in the study area and adjacent basins, it is considered that the climate change in the Nangqian Basin during 51.8-37.5 Ma was mainly affected by global climate change and the retreat of the Tethys Sea. The uplift of the Qinghai-Tibetan Plateau and its higher elevation greatly influenced water vapor in the Nangqian Basin, whereas monsoons have little influence on water vapor. [ABSTRACT FROM AUTHOR]

The seasonal variation of petroleum pollution including n-alkanes in surface sediments of the Selangor River in Malaysia during all four climatic seasons was investigated using GC–MS. The concentrations of n-alkanes in the sediment samples did not significantly correlate with TOC (r = 0.34, p > 0.05). The concentrations of the 29 n-alkanes in the Selangor River ranged from 967 to 3711 µg g-1 dw, with higher concentrations detected during the dry season. The overall mean per cent of grain-sized particles in the Selangor River was 85.9 ± 2.85% sand, 13.5 ± 2.8% clay, and 0.59 ± 0.34% gravel, respectively. n-alkanes are derived from a variety of sources, including fresh oil, terrestrial plants, and heavy/degraded oil in estuaries. The results of this study highlight concerns and serve as a warning that hydrocarbon contamination is affecting human health. As a result, constant monitoring and assessment of aliphatic hydrocarbons in coastal and riverine environments are needed. [ABSTRACT FROM AUTHOR]

Marine microorganisms are primary drivers of the elemental cycling. The interaction between heterotrophic prokaryotes and biomarker (n-alkane) in Kuroshio Extension (KE) remains unclear. Here, we categorize KE into three characteristic areas based on ocean temperatures and nutrient conditions: Cold Water Area (CWA), Mixed Area (MA), and Warm Water Area (WWA). A total of 49 samples were collected during two–year voyage to identify the source of n-alkane and associated degrading microorganisms. Total n-alkane concentrations (Σn–Alk) in surface water (SW) spanned from 1,308 ng L–1 to 1,890 ng L–1, it was significantly higher (Tukey–Kramer test, p

Composites based on n-alkane and nanoscale additives were investigated to determine the efficiency of heat transfer during phase transitions in phase change materials. There was justified a new technique for obtaining thermal conductivity by analyzing shapes of the peaks recorded in thermograms by the method of differential scanning calorimetry. It was found that the thermal conductivity of composite materials is several times higher than the thermal conductivity of the initial n-alkane. The observed effect is due to the specificity of the supramolecular nanostructure of the composite, which differs from the supramolecular structure of the nonadecane. [ABSTRACT FROM AUTHOR]

Yarrowia lipolytica, a dimorphic yeast belonging to the Ascomycota, has potent abilities to utilize hydrophobic compounds, such as n-alkanes and fatty acids, as carbon and energy sources. Yarrowia lipolytica can synthesize and accumulate large amounts of lipids, making it a promising host to produce various lipids and convert n-alkanes to useful compounds. For advanced use of Y. lipolytica in these applications, it is necessary to understand the metabolism of these hydrophobic compounds in this yeast and the underlying molecular mechanisms. In this review, current knowledge on the n-alkane metabolism and how this is regulated in Y. lipolytica is summarized. Furthermore, recent studies revealed that lipid transfer proteins are involved in the utilization of n-alkanes and the regulation of cell morphology in response to n-alkanes. This review discusses the roles of membrane lipids in these processes in Y. lipolytica. [ABSTRACT FROM AUTHOR]

Large carbon number n -alkanes are a notable component in all real transportation fuels, and their chemical structure fosters substantial low temperature kinetic reactivity. Normal alkanes have been studied in various canonical configurations but rarely in systems with strong coupling between low temperature chemistry and transport for pure as well as for multi-component n -alkane mixtures. The Fl ame Ex tinguishment (FLEX) experiments onboard the International Space Station provided a unique platform for investigating low temperature multi-phase n -alkane and iso -alkane combustion. Among the many interesting phenomena experimentally observed, cool flame extinction can occur, accompanied by the concurrent formation of a surrounding cloud of condensed vapor. In this work we conduct numerical simulations of high and low temperature combustion of large, initially single-component n -heptane, n -decane and n -dodecane droplets. The role of initial droplet diameter, operating pressure, and n -alkyl carbon number on the extinction of hot and low temperature flames is investigated and compared against the available experimental data. While all three fuels exhibit similar hot flame behavior, cool flame activity increases with the carbon number, resulting in an increased cool flame temperature and decreased extinction diameter. Multi-cyclic "hot/cool flame transitions" are found in air as pressure is slightly increased above one atmosphere. The cyclic behaviors correspond to continuously varying hot and cool flame transitions across the high, low, and negative temperature coefficient (NTC) kinetic regimes. Further increase in pressure results in a second stage steady " Warm flame " transition. The extinction of hot and cool flame has a strong non-linear dependence on ambient pressure but as the hot flame extinction diameter increases with pressure the extinction diameter of the cool flame decreases. The computational results are compared with a recent asymptotic analysis of FLEX n -alkane cool flames. [ABSTRACT FROM AUTHOR]

This research provides a critical baseline for chemical and macromolecular characteristics of organic matter (OM) sources in high-elevation lake sediments. Such studies are essential for accurate paleoenvironmental interpretation of organic matter characteristics, particularly in mountain regions where steep environmental gradients lead to spatially variable OM inputs among lakes. We analyzed the carbon- and nitrogen-isotope compositions (δ13CTOC, δ15NTN), and total organic carbon to total nitrogen atomic ratios (TOC:TN), of whole tissues of modern vegetation, lichen and algae from Uinta Mountain lakes, along with the abundances and carbon- and hydrogen-isotope compositions of n-alkanes (δ13Cn-alkane, δ2Hn-alkane). TOC:TN can be used to distinguish between aquatic and terrestrial sources, but the differentiating values are higher in the Uinta Mountains than in low-elevation regions. Chain lengths of n-alkanes are more useful than n-alkane isotope compositions for differentiating between terrestrial and semi-aquatic sources in the Uinta Mountains. The ratio of n-alkanes C23 to C27 in mountain lake sediment OM can be used to detect inputs from coniferous krummholz trees and may serve as a proxy for treeline position. We used the isotope data from n-alkanes to calculate the carbon-isotope fractionation between atmospheric carbon dioxide and the n-alkane C23 (ɛbulk), and the hydrogen-isotope fractionation between source water and the n-alkane C25 (ɛwater). These fractionation factors, and the isotope compositions of n-alkanes extracted from lake sediments, suggest that the δ13C of atmospheric CO2 was − 7.0 ± 2‰ and the δ2H of precipitation was − 133 ± 7‰ at ~ 1400 CE in this region. These calculations demonstrate potential applications of our results for obtaining additional paleoclimatic information from paleolimnological organic matter archives. [ABSTRACT FROM AUTHOR]

C9~C33 n-alkane standard solution and Smart Database Pesticides database were used to establish a rapid analytical method for the determination of 32 fungicides in strawberry based on retention index. Thirty-two fungicides were selected as the target, the samples were extracted and purified by QuEChERS method. Gas chromatography tandem mass spectrometry was used for qualitative and quantitative analysis. Results showed that, the 32 fungicides showed good linear relationship in the range of 5~200 μg/L, and the correlation coefficients were greater than 0.9982. The recoveries of 32 fungicides spiked at 10, 50, 100 μg/kg were 70.3%~117.8% and therelative standard deviations were 0.01%~8.50%. The limits of detection were 0.01~2.91 μg/kg, and the limits of quantitative were 0.04~9.71 μg/kg. This method was rapid, simple, accurate, steady, and achieved good performance in strawberry sample analyses, and was suitable for monitoring fungicides using in strawberry, and provided reliable date and technical support for determination of multi-component pesticide residues studies．

The complete genome of the naphthalene- and n-alkane-degrading strain Pseudomonas sp. strain OVF7 was collected and analyzed. Clusters of genes encoding enzymes for the degradation of naphthalene and n-alkanes are localized on the chromosome. Based on the Average Nucleotide Identity and digital DNA–DNA Hybridization compared with type strains of the group of fluorescent pseudomonads, the bacterium studied probably belongs to a new species. Using light, fluorescent, and scanning electron microscopy, the ability of the studied bacterium to form biofilms of different architectures when cultured in liquid mineral medium with different carbon sources, including naphthalene and n-dodecane, was demonstrated. When grown on a mixture of naphthalene and n-dodecane, the strain first consumed naphthalene and then n-dodecane. Cultivation of the strain on n-dodecane was characterized by a long adaptation phase, in contrast to cultivation on naphthalene and a mixture of naphthalene and n-dodecane.

Abstract Investigating organic compounds in marine sediments can potentially unlock a wealth of new information in these climate archives. Here, we present pilot study results of organic geochemical features of long-chain n-alkanes and alkenones and individual carbon isotope ratios of long-chain n-alkanes from a newly collected, approximately 8 m long, located in the far reaches of the Pacific sector of the Southern Ocean. We analyzed a suite of organic compounds in the core. The results show abundant long-chain n-alkanes (C29 –C35) with predominant odd-over-even carbon preference, suggesting an origin of terrestrial higher plant waxes via long-range transport of dust, possibly from Australia and New Zealand. The δ13C values of the C31 n-alkane range from −29.4 to −24.8‰, in which the higher δ13C values suggest more contributions from C4 plant waxes. In the analysis, we found that the mid-chain n-alkanes (C23 –C25) have a small odd-over-even carbon preference, indicating that they were derived from marine non-diatom pelagic phytoplankton and microalgae and terrestrial sources. Furthermore, the C26 and C28 with lower δ13C values (~−34‰) indicate an origin from marine chemoautotrophic bacteria. We found that the abundances of tetra-unsaturated alkenones (C37:4) in this Southern Ocean sediment core ranges from 11 to 37%, perhaps a marker of low sea surface temperature (SST). The results of this study strongly indicate that the δ13C values of long-chain n-alkanes and U 37 k $$ {U}_{37}^{\mathrm{k}} $$ index are potentially useful to reconstruct the detailed history of C3/C4 plants and SST change in the higher latitudes of the Southern Ocean.

Ornithogenic sediment may contain important paleoecological information concerning past bird population dynamics. In this paper, we analyse the distribution of n -alkanes and polycyclic aromatic hydrocarbons (PAHs) in two sedimentary profiles collected from abandoned penguin colonies at Cape Bird, Ross Island, Antarctica. The geochronology of the sediment profiles was determined using 210Pb and AMS 14C dating techniques, and spans the past 1500 years. We observe low levels of n -alkanes (0.93–2.67 μg g−1) and PAHs (20.5–46.8 ng g−1) concentrations dominated by short-chain n -alkanes, low-molecular-weight and alkyl PAHs. Principal Component Analysis (PCA) shows that the PC 1 scores for n -alkanes and PAHs are significantly correlated with the input intensity of penguin guano and penguin bioelements. Using these proxies in combination with Generalized Additive Model (GAM), we reveal that breeding penguin population growth reaches a historical peak during the Medieval Climate Anomaly (MCA) prior to 1550 CE. This growth in population size corresponds to the extent of sea ice cover and the activity of the local atmospheric-ocean circulation. Warming induced by El Niño and the positive phase of the Southern Annular Mode, along with the expansion of ice-free zones and increased oceanic nutrient and food availability, are considered primary factors contributing to the growth of breeding penguin populations. Additionally, variations in sea ice extent and Amundsen Sea Low significantly influence penguin population dynamics. Our study suggests that n -alkanes and PAHs may be valuable organic proxies for reconstructing historical changes in breeding penguin populations, with the local sea ice extent and atmospheric-oceanic circulation exerting a major influence on Antarctic penguin population dynamics. [Display omitted] • n -Alkanes and PAHs can function as proxy indicators for historical penguin guano input. • PC 1 scores for n -alkanes and PAHs correlate with guano input intensity metrics and bioelements. • Penguin population significantly increase in mid Cape Bird during the Medieval Climate Anomaly. • Atmospheric-ocean circulation influences penguin population dynamics. [ABSTRACT FROM AUTHOR]

The purpose of the current study is twofold: first, to propose a group contribution method able to predict speed of sound in high molecular weight n-alkanes based on group decomposition into two groups (pentyl and methylene); second, to present correlations of speed of sound as a function of temperature and pressure for each pure component in the n-alkane series from n-C10 to n-C36 in the temperature range from 293.15 to 423.15 K and for pressures of up to 150 MPa, using available experimental data supplemented by group contribution predictions to make up for the lack of data in the case of some n-alkanes. The uncertainties of the proposed correlations are 0.1% at atmospheric pressure and 0.2% (with a 95% confidence level) across the entire high-pressure range. [ABSTRACT FROM AUTHOR]

n-Alkanes are one of the most used proxies in lake sediments to reconstruct past climate change. However, the distribution and concentration of n-alkanes are controlled by multiple factors, and their interpretation across northern China has revealed obvious discrepancies. It is therefore important to investigate the controlling factors of n-alkane proxies before using them for paleoclimate reconstruction. In this study, we collected fresh plant leaves, basin surface soils, lake surface sediments, and a short sediment core (DH20B) in the Daihai Lake basin to analyze the paleoclimate implications of n-alkanes. Our results show that long-chain (C27–C35) n-alkanes in Daihai Lake are dominated by allochthonous sources. The average chain length of long-chain n-alkanes (ACL27–35) and total long-chain n-alkane concentration (∑alklong-chain) of DH20B are significantly correlated with regional summer temperature (r = 0.54, p < 0.01) and summer precipitation (r = 0.41, p < 0.05) over the past 60 years. These results indicate that ACL27–35 and ∑alklong-chain from Daihai Lake sediments have the potential to reconstruct past summer temperature and summer precipitation, respectively, because higher summer temperature promotes the synthesis of longer-chain n-alkanes to reduce water loss (leading to higher ACL27–35) and increased summer precipitation promotes plant growth (leading to higher ∑alklong-chain). Moreover, we found that human activity significantly affected ∑alklong-chain through cultivation and grazing after 2005. Our findings may have broad significance for paleoclimate reconstruction of other hydrologically closed lakes, highlighting the importance of proxy validation studies.

[Display omitted] Weakly bound, physisorbed hydrocarbons could in principle provide a similar water-repellency as obtained by chemisorption of strongly bound hydrophobic molecules at surfaces. Here we present experiments and computer simulations on the wetting behaviour of water on molecularly thin, self-assembled alkane carpets of dotriacontane (n -C 32 H 66 or C32) physisorbed on the hydrophilic native oxide layer of silicon surfaces during dip-coating from a binary alkane solution. By changing the dip-coating velocity we control the initial C32 surface coverage and achieve distinct film morphologies, encompassing homogeneous coatings with self-organised nanopatterns that range from dendritic nano-islands to stripes. These patterns exhibit a good water wettability even though the carpets are initially prepared with a high coverage of hydrophobic alkane molecules. Using in-liquid atomic force microscopy, along with molecular dynamics simulations, we trace this to a rearrangement of the alkane layers upon contact with water. This restructuring is correlated to the morphology of the C32 coatings, i.e. their fractal dimension. Water molecules displace to a large extent the first adsorbed alkane monolayer and thereby reduce the hydrophobic C32 surface coverage. Thus, our experiments evidence that water molecules can very effectively hydrophilize initially hydrophobic surfaces that consist of weakly bound hydrocarbon carpets. [ABSTRACT FROM AUTHOR]

The Deccan Traps in Western India is hypothesized to have caused significant fluctuations in climatic condition and organic matter (OM) productivity across the Cretaceous‐Paleogene Boundary (K/PgB). The periodic release of large amounts of volatiles into the atmosphere is thought to drive these changes. Yet, direct impact of volcanism on the carbon cycle and ecosystem remains relatively unconstrained. For the first time, we attempt to trace changes in both marine and terrestrial carbon reservoirs from pre‐ and intervolcanic sedimentary units (infra‐ and inter‐trappeans respectively) from Rajahmundry, ~1500 km SE of main eruption sites in Western India. Molecular level characterization of OM and stable isotope composition of carbonates (δ13Ccarb), bulk OM (δ13Corg), and n‐alkane (δ13Calk and δDalk) have been analysed to provide a chemo‐stratigraphic framework. In Rajahmundry, high CO2 concentration estimated from infra‐trappean carbonate nodule is synchronous with the onset of the Deccan Traps and the Late Maastrichtian warming episode. Impact of the warming event is reflected in Rajahmundry from a major shift in the terrestrial ecosystem. Marine OM production also seems to have been low throughout the infra‐trappean. A steady decrease in δ13Ccarb values, increase in mortality rates and dwarfism in invertebrates immediately below the first volcanic units in Rajahmundry suggest stressed conditions from eruption in the western part of India ~40–60 kyrs prior to K/PgB. A significant increase in heterotrophic activity is observed after the volcanic deposits in Rajahmundry that seems to have controlled the marine carbon reservoir for a maximum of ~200 kyrs after the boundary. Advent of pteridophytes, increase in carbon content and positive shifts in δ13Ccarb and δ13Calk values in the upper inter‐trappean units mark the onset of recovery in terrestrial and marine environments. Overall, our results suggest significant perturbations in the carbon reservoir as a consequence of the Deccan eruption. [ABSTRACT FROM AUTHOR]

Agricultural grass cultivars bred for increased forage yield commonly have extensive root systems. As roots are an important input of organic matter into the soil, it follows that such cultivars could lead to important increases in soil organic carbon (SOC), but this, and the mechanisms involved, are poorly understood with little empirical field evidence. We assessed the effect of two cultivars, Lolium perenne L. cv. "AberMagic" and L. perenne L. × Festuca pratensis Huds. cv. "Prior", in comparison with mixed‐species permanent pasture ("Pasture") in a field experiment on temperate alluvial soil in the southwest UK. Root and SOC stocks, and specific plant‐derived lipids as mechanistic biomarkers for shoot and root inputs of C, were measured on intact 1‐m volumetric soil cores collected on four dates in 2013–2015. Total grass yields were greater for both grass cultivars (40–43 Mg ha−1) than Pasture (39 Mg ha−1), and by 2015 root stocks in the upper 0.1 m were significantly greater by more than 4.7 Mg ha−1. At 0.1–0.3 m depth, SOC stocks (per 0.1‐m depth) were significantly greater under the two grass cultivars (24–50 Mg ha−1) compared to Pasture (18–32 Mg ha−1). In the full 1‐m profile, mean SOC stocks were 137, 133 and 110 Mg ha−1 for AberMagic, Prior and Pasture, respectively, matching root biomass distribution. Odd‐chain n‐alkane concentrations were significantly greater for shoots than roots (274 vs. 64 mg kg−1, respectively), and roots had significantly greater concentrations than shoots of even‐chain hydroxy fatty acids (1829 vs. 305 mg kg−1, respectively) and diacids (317 vs. 93 mg kg−1, respectively). This confirmed lipids as candidate biomarkers for distinguishing shoot and root inputs into the soil, with roots being the dominant source of SOC. Based on the observations of increased forage yield and SOC stock, high‐yielding forage grass cultivars can contribute to future strategies for climate‐smart agriculture in grassland‐dominated temperate regions. Highlights: Selected root traits for increased depth, density and diameter may increase SOC in grassland.The effect of two high‐yielding forage grass cultivars were assessed in a field trial.Fast‐growing, high‐yielding cultivars enhanced root and SOC stocks compared to typical pasture.Lipid biomarkers confirmed that root inputs were the predominant C input to soil. [ABSTRACT FROM AUTHOR]

The accurate description of the phase equilibria of CO2 and n-alkane multicomponent mixtures over a wide range of temperature, pressure, and n-alkane molecular weight, requires the models that are both consistent and mathematically flexible for such highly non-ideal systems. In this study, a predictive correlation was proposed for the vapor-liquid equilibrium data (VLE) of CO2 and n-alkane ternary systems, based on the Peng-Robinson equation of state (PR EOS), coupled to cubic mixing rules (CMRs). The ternary interaction parameters (TIP) correlation is developed using binary VLE data and tested for CO2 + n-alkane+ n-alkane ternary systems. For this purpose, binary VLE data of CO2 + n-alkane and n-alkane + n-alkane systems for n-alkane from C3 to C24, covering a total of about 70 references, used to correlate TIP in the ranges of 0.5-31 MPa and 230-663 K. Two temperature-dependent TIP correlations, based on acentric factor ratio, have been tuned with more than 2000 data points of the CO2 + n-alkane and the n-alkane + n-alkane binary systems with AARD of 3.13% and 6.71%, respectively. The generalized predictive correlation was proposed based on the proper three-body interaction contributions and successfully tested for VLE data of the CO2 + n-alkane + n-alkane ternary systems.

The interaction of a host plant with pathogen implies an extremely complex process involving the outer waxy layer of the cuticle, cutin, cell membrane, and intracellular structures. However, the initial contact between plants and pathogens takes place in cuticular waxes covering the surface of leaves, stems and fruits. Despite many findings on the role of plant epicuticular waxes, there is a gap in the understanding of the relationship between individual compounds and their functions. The pathogenic fungus Clasterosporium carpohilum (Lev.) Aderh. parasitizes the tissues of many stone fruit trees, damaging leaf and fruit surface. The aim of this work was to find out if the quantity and composition of leaf epicuticular wax could be responsible for the resistance to clasterosporium disease. The study of differences of plants in fungal resistance was carried out on species and hybrids of the genus Prunus from the collection of the Botanical Garden of Oles Honchar Dnipro National University (Dnipro city, Ukraine). The chloroform extracts of epicuticular waxes from the surface of mature leaves were analyzed by gas chromatography connected to mass-spectrometry. GC/MS assay was performed using Shimadzu GCMS-QP 2020 El equipped with capillary column (5% diphenyl/95% dimethyl polysiloxane), and helium as a carrier gas. Mass Spectrum Library 2014 for GSMS was used to identify the separated compounds of the wax extracts. The maximum total wax amount on the adaxial and abaxial leaf surface of hybrid 2 was twice the minimum wax accumulation for hybrid 4. Overall, 20 individual compounds belonging to six hydrocarbon classes were identified. Leaf epicuticular wax composition both in Prunus persica (L.) Batsch and P. dulcis (Mill.) D. A. Webb, and hybrids was dominated by long-chain n-alkanes with even carbon number (77.6–90.9% of total sum). The alkenes’ class was represented only by 17-pentatriacontene detected in the wax of both Prunus species. Octadecanaldehyde was found in epicuticular wax of P. dulcis while absent in wax of the more resistant species P. persica. Prime alcohols 1-tetradecanol and 1-hexacosanol were detected in leaf waxes of hybrid 4 and P. dulcis respectively. The ester class contained seven compounds found in leaf epicuticular waxes of both plant species and all hybrid forms. The identification of phthalic acid esters in leaf wax extracts was unexpected, and the phthalates’ origin is discussed. Strong positive correlation between leaf damage and tetrapentacontane content in epicuticular waxes could presumably be the result of infection-induced metabolism reprogramming in epidermal cells of infected leaves.

Colloidal Cu 2 O nanoparticles can exhibit both photocatalytic activity under visible light illumination and resonant Mie scattering, but, for their practical application, they have to be immobilized on a substrate. Butterfly wings, with complex hierarchical photonic nanoarchitectures, constitute a promising substrate for the immobilization of nanoparticles and for the tuning of their optical properties. The native wax layer covering the wing scales of Polyommatus icarus butterflies was removed by simple ethanol pretreatment prior to the deposition of Cu 2 O nanoparticles, which allowed reproducible deposition on the dorsal blue wing scale nanoarchitectures via drop casting. The samples were investigated by optical and electron microscopy, attenuated total reflectance infrared spectroscopy, UV-visible spectrophotometry, microspectrophotometry, and hyperspectral spectrophotometry. It was found that the Cu 2 O nanoparticles integrated well into the photonic nanoarchitecture of the P. icarus wing scales, they exhibited Mie resonance on the glass slides, and the spectral signature of this resonance was absent on Si(100). A novel bio-nanohybrid photonic nanoarchitecture was produced in which the spectral properties of the butterfly wings were tuned by the Cu 2 O nanoparticles and their backscattering due to the Mie resonance was suppressed despite the low refractive index of the chitinous substrate.

The dimorphic yeast Yarrowia lipolytica possesses an excellent ability to utilize n -alkane as a sole carbon and energy source. Although there are detailed studies on the enzymes that catalyze the reactions in the metabolic processes of n -alkane in Y. lipolytica , the molecular mechanism underlying the incorporation of n -alkane into the cells remains to be elucidated. Because Y. lipolytica adsorbs n -alkane, we postulated that Y. lipolytica incorporates n -alkane through direct interaction with it. We isolated and characterized mutants defective in adsorption to n -hexadecane. One of the mutants harbored a nonsense mutation in MAR1 ( M orphology and n -alkane A dsorption R egulator 1) encoding a protein containing a high mobility group box. The deletion mutant of MAR1 exhibited defects in adsorption to n -hexadecane and filamentous growth on solid media, whereas the strain that overexpressed MAR1 exhibited hyperfilamentous growth. Fluorescence microscopic observations suggested that Mar1 localizes in the nucleus. RNA-sequencing analysis revealed the alteration of the transcript levels of several genes, including those encoding transcription factors and cell surface proteins, by the deletion of MAR1 . These findings suggest that MAR1 is involved in the transcriptional regulation of the genes required for n -alkane adsorption and cell morphology transition.IMPORTANCE Yarrowia lipolytica , a dimorphic yeast capable of assimilating n -alkane as a carbon and energy source, has been extensively studied as a promising host for bioconversion of n -alkane into useful chemicals and bioremediation of soil and water contaminated by petroleum. While the metabolic pathway of n -alkane in this yeast and the enzymes involved in this pathway have been well characterized, the molecular mechanism to incorporate n -alkane into the cells is yet to be fully understood. Due to the ability of Y. lipolytica to adsorb n -alkane, it has been hypothesized that Y. lipolytica incorporates n -alkane through direct interaction with it. In this study, we identified a gene, MAR1 , which plays a crucial role in the transcriptional regulation of the genes necessary for the adsorption to n -alkane and the transition of the cell morphology in Y. lipolytica . Our findings provide valuable insights that could lead to advanced applications of Y. lipolytica in n -alkane bioconversion and bioremediation., Competing Interests: The authors declare no conflict of interest.

Modeling of heat and mass transfer in liquid fuel combustion requires several material properties in a wide temperature and pressure range. The unavailable data are commonly patched with various estimation methods. In this paper, group contribution methods (GCM) and law of corresponding states (LCS) were analyzed for estimating material properties of n-alkanes (up to C10H22 and C12H26), 1-alcohols (up to C10H22O), and methyl esters (up to C19H38O2 and C19H36O2). These were compared to reference data to evaluate their applicability. LCS suggested by Poling et al. provides proper estimation for the acentric factor. GCM of Joback accurately estimates normal boiling point, critical properties, and specific heat capacity of the vapor-phase, the latter was corrected for methanol, however, GCM of Constantinou is more accurate for critical pressure of methyl esters. GCM of Ruzicka is suitable for estimating liquid-phase specific heat capacity. This method was updated for methanol. GCM of Elbro gives a proper estimation for liquid-phase density, while LCS of Lucas estimates vapor-phase viscosity properly. LCS of Chung and the modified Eucken method for vapor-phase and GCM of Sastri for liquid-phase thermal conductivity are appropriate. Considering the gas-phase mutual diffusion coefficient, the method of Fuller provides the best estimation, while LCS methods of Riedel and Chen are suitable for the enthalpy of vaporization at the normal boiling point. [ABSTRACT FROM AUTHOR]

To understand the thermal evolution of lacustrine sedimentary n‐alkane hydrogen isotopic composition (δD), especially bacterially derived n‐alkanes, anhydrous thermal simulation experiments were performed with sediments from Lake Gahai (Gannan, China). We analyzed the original and pyrolysis‐generated n‐alkanes and their δD values. The results showed that thermal maturity and n‐alkane origins significantly affected the distribution of pyrolysis‐generated n‐alkanes. In immature to post‐mature sediments, the bacterial‐derived medium‐chain n‐alkanes generally had depleted δD values. The maximum difference in average δD values between the bacterial‐and herbaceous plant‐derived medium‐chain n‐alkanes was 32‰, and the maximum difference in δD values among individual n‐alkanes was 59‰. We found that the average δD value of pyrolysis‐generated n‐alkanes from different latitude was significantly different in immature to highly mature sediments, but similar in post‐mature ssediments. The hydrogen isotopes of sedimentary n‐alkanes can be used as indicators for paleoclimate/paleo‐environment conditions only when sediments are immature to highly mature. During thermal evolution, the δD value of generated individual n‐alkanes and the average δD value increased with thermal maturity, indicating that hydrogen isotopes of sedimentary n‐alkanes can be used as an index of organic matter maturity. We established mathematical models of average δD values of generated n‐alkanes from immature to post‐mature sediments using nC21−‐/nC21+ and average chain lengths. These results improve our understanding of the distribution and δD value of sedimentary n‐alkanes derived from herbaceous plants in mid‐latitude plateau cold regions. [ABSTRACT FROM AUTHOR]

A comparison is made between theoretical and experimental studies of the position of eutectics in two-component systems consisting of tetrachlorethylene and n-alkanes with 10 to 20 carbon atoms. Data on the composition of the eutectics, their temperatures of melting, and the coefficients of activity of each component are calculated in three ways: using experimental data, the UNIFAC procedure, and a modified UNIFAC Dortmund procedure. The equilibria of liquid–solid phases are studied theoretically using Schröder's equation and the UNIFAC and modified UNIFAC Dortmund procedure. Experimental data were obtained via DTA. Relative deviations of the calculated melting temperatures and compositions of the eutectics from the corresponding experimental data are reported. [ABSTRACT FROM AUTHOR]

An accurate dry matter intake (DMI) measurement method is of great importance for determining the performance of dairy cows. While n-alkane technique is commonly used to estimate the DMI of ruminants, the protocols used to measure alkanes are complex, time consuming and low throughput. Herein we present a simplified and miniaturised protocol that combines a smaller sample matrix (60 mg of faeces or herbage), a shorter (3 h) saponification step and a direct purification of the crude extract by filtration through silica powder or mixing with silica powder prior to GC-FID analysis. In addition to a much higher throughput compared with the existing methods, by skipping the commercial SPE columns and reducing the organic solvent volume, our miniaturised protocol should significantly reduce the sample processing cost and is thus suitable for alkane determination for large-scale experiments.

This study explores the paleoclimate changes around the 4 ka BP period in the central Qaidam Basin (QB), assessing the differences in spectral characteristics and organic composition of salt lake sediments under different climate change conditions. Sediment samples (10-m-depth profile) were collected from the middle of dry salt flats in East Taijinar Lake (China). Sediment organic matter (SOM) was assessed by Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS). Results showed a significant difference in the TOC content of sediments with different lithological characteristics. A lower TOC content in salt-bearing strata was attributed to the extreme sedimentary environment with minimal exogenous inputs. FTIR spectroscopy revealed that the SOM in sediments included aliphatic C, ketones and alcohols. Sediments of salt-bearing strata generally exhibited a rise in the content of ketone C=O groups and a decrease in aliphatic C, with an equal content of alcohols compared with silty sand. Therefore, exogenous OM and the content of TOC in silty sand strata are higher than in salt-bearing strata, indicating that the paleoclimate became warmer and wetter after 4 ka BP. GC-MS analysis showed a significant difference between the phenol and aldehyde content in different strata, further indicating that the paleoclimate changed from dry to relatively warm around 4 ka BP. Seven organic compound types were identified in SOM, including aldehydes, hydrocarbons, phenols, esters, ketones, alcohols, and furans. Different strata exhibited different distributions of organic compounds, with particularly high concentrations of aldehydes in salt-bearing strata and phenols in silty sand. Correlation analysis was performed between detrital minerals and OM types in all samples. Results showed a strong positive correlation between detrital minerals and phenols and a strong negative correlation between detrital minerals and aldehydes, with a negative correlation also identified between detrital minerals and ketones. Overall, the reduction in volatile organic compounds demonstrates that the paleoclimate changed from cooler and dry to wet and warm around the 4 ka BP period in the central QB, with the carbon preference index and n-alkane values further demonstrating these results. This study also confirms the importance of volatile organic compound monitoring to assess paleoclimate changes.

The main objective of this study was to explore the composition and distribution of volatile organic compounds (VOCs) and the factors that affect their distribution in the salt lake sediments. Thirteen sediment samples were collected from a depth profile in the East Taijinar Lake, China. VOCs of different samples were extracted by headspace solid phase microextraction. Gas chromatography-ion mobility spectrometry, gas chromatography-mass spectrometry, and X-ray diffraction were used to analyze the VOCs, n-alkanes, and minerals present in samples. Thirty-four VOCs were identified and classified into seven types, including terpenes, furans, esters, aldehydes, ketones, alcohols, and acids, apart from six contaminants. It was found that 24 of the most prevalent compounds in clay were on average 101.45% higher than those in sandstone and halite because of the sedimentary environment, while the remaining ten (2-acetylfuran, 2-pinene D, etc.) were on average 13.27% higher in sandstone and halite sediments than in clay. This can be attributed to their different biological sources, porosity, and higher salinity. Based on the Q-cluster analysis, the 13 sediment samples were split into two groups, including the group according to composition and the group based on distribution of VOCs. In this study, it was found that the VOCs correlate positively with detrital minerals, with Group I exhibiting a high content of detrital minerals (>25%), while Group II showed the opposite characteristics. The consumption of organic matter (OM) by microorganisms leads to the formation of VOCs in sediment. The values of carbon preference index and n-alkane further demonstrate that the organic matter of the two groups came from different sources, exogenous and endogenous. Pr/Ph ratios, Pr/C17, and Pr/C18 also suggest that the OM in all sediments was strongly affected by microorganisms in an anoxic environment. Together, these results demonstrate that the OM from different biological sources and microbial activities played a critical role in deciding the composition and distribution of VOCs in the sediment. This study also shows that the proportion of VOCs in halite was discernably higher than that in clay and sandstone and that the content of VOCs should be considered when studying OM in salt lake sediments.

Advanced gas turbine and internal combustion engine combustion chambers operate at highly elevated pressures and temperatures. Therefore, spray vaporization analysis cannot be limited to the atmospheric environment since evaporation strongly depends on ambient conditions. Presently, the effect of air pressure and temperature on droplet evaporation rate was investigated by using both a transient and a steady-state approach. A corresponding states model was derived for the steady-state evaporation rate for n-alkanes in the range of C2–C9 with an excellent fit quality and < 1% model uncertainty, considering the thermophysical data uncertainties. The model was tested for C1, C10, and C12 n-alkanes as well with low success. The ambient conditions were evaluated in terms of reduced pressures and temperatures, covering the range of 0.02–0.5 and 1.2–1.5, respectively. However, the applicability of the model was limited to reduced temperature of 1.3–1.5, as higher discrepancy was observed between the trends of the different n-alkanes at lower temperatures. Since the heat-up phase of practical sprays in combustion chambers is often short, the present model might significantly reduce the computational effort required for liquid evaporation calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Total n -alkane concentration in surface water spanned from 1308 to 1890 ng L–1. • Total n -alkane concentration in surface sediments increased from north to south. • Bacteria and algae were the primary sources of n -alkanes in Kuroshio Extension. • Proteobacteria was the most widely distributed among three areas. • Rhodobacteraceae with alkB affected the n -alkane concentrations. Marine microorganisms are primary drivers of the elemental cycling. The interaction between heterotrophic prokaryotes and biomarker (n -alkane) in Kuroshio Extension (KE) remains unclear. Here, we categorize KE into three characteristic areas based on ocean temperatures and nutrient conditions: Cold Water Area (CWA), Mixed Area (MA), and Warm Water Area (WWA). A total of 49 samples were collected during two–year voyage to identify the source of n -alkane and associated degrading microorganisms. Total n -alkane concentrations (Σ n –Alk) in surface water (SW) spanned from 1,308 ng L–1 to 1,890 ng L–1, it was significantly higher (Tukey–Kramer test, p < 0.05) in MA than CWA and WWA. The Σ n –Alk in surface sediments (SS) gradually increased from north to south, ranging from 5,982 ng g−1 to 37,857 ng g−1. Bacteria and algae were the primary sources of n -alkane in both SW and SS. Proteobacteria was the most widely distributed among three areas. The presence of Rhodobacteraceae with alkB was the primary reason affecting n -alkane concentrations in SW. The Gammaproteobacteria with alkB and alkR chiefly affected n -alkane concentrations in SS. In summary, n -alkane s serve as an energy source for particular microorganisms, shaping the unique oceanographic patterns. [ABSTRACT FROM AUTHOR]

• Taraxerol is abundant in modern mangrove sediment, particularly below Rhizophora. • Taraxerol is near-absent in supratidal sediment. • Taraxerol is a proxy for mangrove sediment with utility for reconstructing sea level. • Micronesian cores have taraxerol concentrations consistent with modern mangroves. Mangrove sediments are valuable archives of relative sea-level change if they can be distinguished in the stratigraphic record from other organic-rich depositional environments (e.g., freshwater swamps). Proxies for establishing environment of deposition can be poorly preserved (e.g., foraminifera) in mangrove sediment. Consequently, differentiating mangrove and freshwater sediment in the stratigraphic record is often subjective. We explore if biomarkers can objectively identify mangrove sediment with emphasis on their utility for reconstructing relative sea level. Our approach is specific to identifying in situ sediment, which has received less attention than identifying allochthonous mangrove organic matter. To characterize mangrove and non-mangrove (freshwater) environments, we measured n -alkane, sterol, and triterpenoid abundances in surface sediments at three sites in the Federated States of Micronesia. Elevated taraxerol abundance is diagnostic of sediment accumulating in mangroves and taraxerol is particularly abundant beneath monospecific stands of Rhizophora spp. Taraxerol was undetectable in freshwater sediment. Other triterpenoids are more abundant in mangrove sediment than in freshwater sediment. Using cores from Micronesian mangroves, we examine if biomarkers in sediments are indicative of in situ deposition in a mangrove, and have utility as a relative sea-level proxy. Taraxerol concentrations in cores are comparable to surface mangrove sediments, which indicates deposition in a mangrove. This interpretation is supported by pollen assemblages. Downcore taraxerol variability may reflect changing inputs from Rhizophora spp. rather than diagenesis. We propose that taraxerol is a proxy that differentiates between organic sediment that accumulated in mangrove vs. freshwater environments, lending it utility for reconstructing relative sea level. [ABSTRACT FROM AUTHOR]

Understanding the exact origin of sedimentary organic matter (OM) was crucial for assessing carbon cycle processes and environmental contamination in continental margin. However, such studies are less performed on shelves far away from the mainland. Here, the abundance and composition of lipid biomarkers were determined in surface sediments from 58 sites at the eastern Sunda Shelf, South China Sea, to identify the sedimentary OM sources and characterize the spatial variation of OM input from specific sources. The results indicated that the sedimentary OM were derived mainly from algae, bacteria, seagrass, terrestrial plants, mangroves, petroleum, and rock erosion products, and the relative significance of these sources varied between different sites. Algal OM input, as indicated by the abundances of short-chain n -alkanes, cholest-2-ene, dinosterol, brassicasterol, and C 30 1,15 alkyl diol, was relatively high at five sites (ZW 47, 51, 55, 82, and 86). Conversely, long-chain n -alkane and long-chain n -alkanol proxies suggested terrestrial plant input was most predominant at three other sites (ZW68, 103, and 106), and high abundances of taraxerol and β-amyrin in these sites imply the dominance of mangrove vegetation in the terrestrial OM. UCM (unresolved complex mixture) and αβ-hopanes indicated a relatively high input of petroleum-derived OM at another five sites (ZW3, 8, 25, 51, and 97). The analysis of abundance variations in the biomarkers suggested a substantial spatial heterogeneity in terrestrial plant OM input and a much lower heterogeneity in algal OM input, probably resulting from great variation in riverine transport intensity and relatively homogeneous water environment across the studied region. Correlation analysis indicated that both algal and terrestrial plant OM significantly contributed to the OM buried in the sediments. These results can form a basis for understanding the carbon cycle processes in Sunda Shelf. The finding of petroleum contamination in several sites can benefit for environmental protection and management of the shelf. • Sedimentary OM source and spatial variation in OM input were studied in eastern Sunda Shelf. • Both algae and terrestrial plants contributed significantly to the sediment OM. • Mangroves may be the dominant component of terrestrial OM in some sites. • Input of petroleum-derived OM was prominent at a few sites of the shelf. • Input of terrestrial plant OM had a much greater spatial heterogeneity than algal OM. [ABSTRACT FROM AUTHOR]

Investigating organic compounds in marine sediments can potentially unlock a wealth of new information in these climate archives. Here, we present pilot study results of organic geochemical features of long-chain n-alkanes and alkenones and individual carbon isotope ratios of long-chain n-alkanes from a newly collected, approximately 8 m long, located in the far reaches of the Pacific sector of the Southern Ocean. We analyzed a suite of organic compounds in the core. The results show abundant long-chain n-alkanes (C29–C35) with predominant odd-over-even carbon preference, suggesting an origin of terrestrial higher plant waxes via long-range transport of dust, possibly from Australia and New Zealand. The δ13C values of the C31n-alkane range from −29.4 to −24.8‰, in which the higher δ13C values suggest more contributions from C4 plant waxes. In the analysis, we found that the mid-chain n-alkanes (C23–C25) have a small odd-over-even carbon preference, indicating that they were derived from marine non-diatom pelagic phytoplankton and microalgae and terrestrial sources. Furthermore, the C26 and C28 with lower δ13C values (~−34‰) indicate an origin from marine chemoautotrophic bacteria. We found that the abundances of tetra-unsaturated alkenones (C37:4) in this Southern Ocean sediment core ranges from 11 to 37%, perhaps a marker of low sea surface temperature (SST). The results of this study strongly indicate that the δ13C values of long-chain n-alkanes and U 37 k index are potentially useful to reconstruct the detailed history of C3/C4 plants and SST change in the higher latitudes of the Southern Ocean. [ABSTRACT FROM AUTHOR]

The hydrogen isotopic composition of leaf wax–derived n-alkane (δ2Hn-alkane) and oxygen isotopic composition of hemicellulose–derived sugar (δ18Osugar) biomarkers are valuable proxies for paleoclimate reconstructions. Here, we present a calibration study along the Bale Mountains in Ethiopia to evaluate how accurately and precisely the isotopic composition of precipitation is imprinted in these biomarkers. n-Alkanes and sugars were extracted from the leaf and topsoil samples and compound–specific δ2Hn-alkane and δ18Osugar values were measured using a gas chromatograph–thermal conversion–isotope ratio mass spectrometer (GC–TC–IRMS). The weighted mean δ2Hn-alkane and δ18Osugar values range from − 186 to − 89‰ and from + 27 to + 46‰, respectively. Degradation and root inputs did not appear to alter the isotopic composition of the biomarkers in the soil samples analyzed. Yet, the δ2Hn-alkane values show a statistically significant species dependence and δ18Osugar yielded the same species–dependent trends. The reconstructed leaf water of Erica arborea and Erica trimera is 2H– and 18O–enriched by + 55 ± 5 and + 9 ± 1‰, respectively, compared to precipitation. By contrast, Festuca abyssinica reveals the most negative δ2Hn-alkane and least positive δ18Osugar values. This can be attributed to "signal–dampening" caused by basal grass leaf growth. The intermediate values for Alchemilla haumannii and Helichrysum splendidum can be likely explained with plant physiological differences or microclimatic conditions affecting relative humidity (RH) and thus RH–dependent leaf water isotope enrichment. While the actual RH values range from 69 to 82% (x̄ = 80 ± 3.4%), the reconstructed RH values based on a recently suggested coupled δ2Hn-alkane –δ18Osugar (paleo–) hygrometer approach yielded a mean of 78 ± 21%. Our findings corroborate (i) that vegetation changes, particularly in terms of grass versus non–grassy vegetation, need to be considered in paleoclimate studies based on δ2Hn-alkane and δ18Osugar records and (ii) that the coupled δ2Hn-alkane –δ18Osugar (paleo–) hygrometer approach holds great potential for deriving additional paleoclimatic information compared to single isotope approaches. [ABSTRACT FROM AUTHOR]

Total organic carbon (TOC), total nitrogen (TN) and multi-biomarker indexes were analyzed for two sediment cores from the eastern coastal area of the Beibu Gulf (core 45, AMS 14C dated) and Qiongzhou Strait (core 29), South China Sea. The results showed that the TOC and TN content of the samples studied were 0.32–0.62% and 0.02–0.07%, respectively. The hydrocarbons in offshore sediments of Leizhou Peninsula were consisted of biogenic hydrocarbons and petrogenic hydrocarbons. The Core 29 sediments contain more terrigenous organic matter than that of sediments in core 45 due to the difference in hydrodynamic conditions. The composition and distribution of various lipid biomarkers indicate the presence of petrogenic hydrocarbons in the sediments of the whole profile of two sediment cores. There are multiple natural sources of hydrocarbons that could potentially contribute to the petroleum background through oil seeps and erosion of carbon-rich rock outcrops or bitumen deposits. Deep sourced hydrocarbon inputs from the submarine hydrocarbon seepage cannot be excluded. Further study is needed to resolve the specific sources for the petrogenic hydrocarbons and may be significant to petroleum exploration in the study area.

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Norse colonization of North Atlantic islands in the 1st millennium of the Common Era led to drastic prehistoric environmental changes in these previously "pristine" landscapes. In Iceland, Norse settlement is associated with a rapid decline in birch trees and heightened soil erosion, yet the timing of Norse exploration in the North Atlantic coincided with large climate changes that also influenced Icelandic environments. To date, there are few records that disentangle climatic and human impacts on terrestrial ecosystems, and there has been very little work on the impacts of Norse arrival on Iceland's aquatic ecosystems. Here we use a high-resolution lake-sediment record from Vestra Gíslholtsvatn (VGHV), southwest Iceland to investigate these processes during the last 2,000 years. Norse arrival (c. 870 CE) in Iceland is followed by a rapid increase in sedimentation rate and a transition in leaf wax n-alkanes indicating a decrease in trees and expansion of grasses. This transition coincides with limnological changes, including increased primary productivity (i.e. C17n-alkane and biogenic opal fluxes) and shifts in the haptophyte algal community. Many of these changes are still apparent today. Comparisons with a new winter-spring alkenone temperature reconstruction from VGHV and marine sea surface temperature records show little to no correlation between terrestrial and aquatic ecological changes and climate at this time. Similarly, volcanic eruptions recorded in VGHV are not associated with any long-term environmental changes. Rather, the VGHV record suggests that human settlement had a lasting impact on the catchment area of VGHV and changes within the lake ecosystem. [ABSTRACT FROM AUTHOR]

Aims: This study aims to evaluate the variations of soil organic matter and plant leaf cuticular waxes along an altitude gradient at two mountains in the east side of the Qinghai-Tibet Plateau. Methods: Surface soils were sampled along an altitude gradient (2600, 3000, 3400, 3800 and 4200 m). We analyzed the soil total organic carbon (TOC), dissolved organic carbon (DOC), soil lipids and leaf cuticular waxes in Kobresia humilis which distributed at all tested altitudes. Results: A sharp concentration increase of TOC was observed when altitudes increased, whereas the proportions of DOC in TOC at low altitudes (3000 m and 2600 m) were significantly higher than those at higher altitudes. Altitudes also influenced the molecular weight, humification degree, aromaticity, and hydrophobicity of DOC molecular. Though soils at higher altitudes relatively had higher abundance of odd carbon alkanes and even carbon alcohols, soil lipid concentrations showed no significant difference between altitudes. Relatively higher total wax coverage at high and low altitude was observed on leaves of K. humilis. Conclusions: The changes of altitudes at alpine ecosystem were associated with alterations of both quantity and quality of soil organic matter as well as leaf cuticular wax coverage, which contributed to their environmental adaptations. [ABSTRACT FROM AUTHOR]

Research on the production of bio-hydrogenated diesel as a green second-generation biodiesel is increasingly attractive for renewable energy utilization in engines, and has potentially been produced from the hydrotreating of vegetable oils. The present work investigated the hydrodeoxygenation of palm oil catalyzed by unsupported nickel-molybdenum (Ni–Mo) sulfide synthesized by a hydrothermal method. The effects of the operating parameters, such as the reaction time (0.5–3 h), temperature (280–320 °C), oil concentration (5–15%) on the n-alkane yield were evaluated. A longer reaction time and higher temperature promoted the reaction via decarboxylation and decarbonylation pathways. Under the appropriate condition (300 °C, 2 h, and initial H 2 pressure of 30 bar), the yield of C 14–18 alkanes was 75.3 wt%, while the selectivity of n-C 15 , n-C 16 , n-C 17 , and n-C 18 alkanes was 21.8, 19.7, 29.6, and 28.1%, respectively. Gas chromatography-mass spectrometry analysis revealed n-alkenes, alcohols, and esters as byproducts. Characterization of catalyst revealed it had a sandwich structure consisting of weakly coupled layers, rim sites and Ni edges, which catalyzed the reaction efficiently. The catalyst could be reused for at least four cycles of palm oil hydrodeoxygenation with retention of a good performance with the decreased 17–25% alkane yield (2nd to 4th cycle with 50.8–57.3% n-C 14–18 yield). Image 1 • The unsupported 0.2-NiMoS 2 catalyst was effective for palm oil hydrotreating. • The appropriate condition (300 °C, 30 bar) gave high C 14 –C 18 yield of 75.3 wt%. • The catalyst can be reused for 4 cycles of palm oil treating with good performance (50.8–57.3% C 14 –C 18 yield). • The morphology of 0.2-NiMoS 2 catalyst had increased number of layers with rim and edge active sites. • The 0.2-NiMoS 2 catalyst exhibited high acidity (0.609 mmol/g) relating to high activity. [ABSTRACT FROM AUTHOR]

In this study, experimental investigations of solid-liquid phase diagram of binary and ternary mixtures formed by the C 11 H 24 , C 12 H 26 and C 14 H 30 were carried out to employ the potential phase change materials (PCMs) for cryogenic applications using the differential scanning calorimetry (DSC). In addition, the thermodynamic equilibrium was modeled employing the ideal model, and the Wilson and NRTL model were applied to correlate the liquidus line. The results show that the C 11 -C 12 system exhibits a peritectic transition and the composition of possibly peritectic point is 60wt% C 12 with the temperature of 251.65 K. The compositions of the eutectic points appear at 10wt% C 14 for C 11 -C 14 system and 18wt% C 14 for C 12 -C 14 system with eutectic temperatures of 246.85 K and 260.45 K, respectively. The C 11 -C 12 -C 14 ternary system presents two possibly eutectic points at compositions of 67wt% C 11 /5wt% C 12 and 86wt% C 11 /10wt% C 12 with eutectic temperatures of 246.45 K and 248.05 K, and has the slight supercooling (1.7 ˚C and 0.5 ˚C), indicating miscibility in liquid phase and immiscibility in solid phase. Moreover, the liquidus lines calculated by the theoretical models are in good agreement with the experimental results. The best predicted results of the ternary mixture and C 11 -C 12 binary subsystem are obtained by the ideal model, with deviations of 0.75% and 0.58% respectively. [ABSTRACT FROM AUTHOR]

This study investigates the molecular, carbon, and hydrogen isotope compositions of n-alkanes in eight pairs of a holoparasitic plant (Cuscuta chinensis) and its hosts. It is unexpected that C. chinensis has a higher concentration of n-alkanes than its hosts in seven of the eight pairs, and it is preferentially dominated by n-C29 alkane (representing > 75% of the total n-alkanes). In addition, the δ13C values of C29 alkane in C. chinensis are less negative (avg. 1.8 ‰) than those in the hosts, while the δ2H values of C29 alkane are more negative in C. chinensis (the difference averages 48 ‰). We propose that the 2H-depletion of n-alkanes in the stem parasite C. chinensis may result from the utilization of stem water with less influence from evapotranspiration or the use of newly synthesized carbohydrates which is 2H-depleted relative to stored sugars. These results highlight the importance of plant nutrient status on the molecular and isotopic compositions of leaf waxes, which shed light on the (paleo)ecological potential of leaf wax δ2H values. [ABSTRACT FROM AUTHOR]

Theoretical calculations are compared to data from an experimental study of the position of eutectics in two-component systems consisting of benzene, diphenyl, and n-alkanes with 12 to 17 carbon atoms. Data on diphenyl–n-alkane (n = 12–17) and benzene–n-alkane (n = 12–17) systems are given for the composition of eutectics, their melting points, and activity coefficients of each component. The theoretical study is based on the Schröder–Le Chatelier approach and the original UNIFAC system; the experimental study is performed via DTA. Deviations of the experimental data from ones calculated for the studied systems are presented. The change in the activity coefficients of benzene and n-hexadecane is illustrated graphically according to UNIFAC and the experimental data. [ABSTRACT FROM AUTHOR]

Both monsoons and westerlies have exerted influence on climate dynamics over the Tibetan Plateau (TP) since the last deglaciation, producing complex patterns of paleohydroclimatic conditions. Diverse proxy records are essential to forge a robust understanding of the climate system on the TP. Currently, there is a general lack of understanding of the response of inland lakes over the TP to climate change, especially glacier‐fed lakes. Paleohydrological reconstructions of such lakes could deepen our understanding of the history of lake systems and their relationship to regional climate variability. Here we use records of n‐alkanes and grain size from the sediments of Bangong Co in the western TP to reconstruct paleohydrological changes over the past 16,000 years. The Paq record (the ratio of non‐emergent aquatic macrophytes versus emergent aquatic macrophytes and terrestrial plants) is generally consistent with the variations in summer temperature and precipitation isotopes. The changes in grain‐size distributions show a similar trend to Paq but with less pronounced fluctuations in the early‐middle Holocene. The new data combined with previous results from the site demonstrate that: 1) Bangong Co experienced relatively large water‐level fluctuations during the last deglaciation, with a steadily high lake‐level during the early‐middle Holocene and a decreasing lake‐level in the late Holocene; 2) The lake level fluctuations were driven by both high summer temperatures via the melting water and monsoon precipitation. However, the dominant factor controlling lake level changed over time. The lake‐level history at Bangong Co deduced from the n‐alkanes and grain‐size records reveals the past hydrological changes in the catchment area, and stimulates more discussion about the future of glacier‐fed lakes under the conditions of unprecedented warming in the region. [ABSTRACT FROM AUTHOR]

In the scope of investigating phase equilibria and thermodynamic magnitudes related to equipment design and optimization for edible oil industry, this paper reports refractive index on mixing and ultrasonic velocity of binary systems enclosing a collection of n-alkanes (n-hexane, n-heptane, n-octane, n-nonane), or esters (ethyl acetate, vinyl acetate, propyl acetate, isopropyl acetate, butyl acetate) + olive oil at temperatures from 288.15-298.15 K. From these physical properties, the corresponding derived magnitudes, changes of refractive indices on mixing and change of isentropic compressibilities were computed, being fitted by a modified Redlich-Kister polynomial. Due to the fact of industrial processes design to be strongly computer oriented, consideration was also given to quantify how accurate different theoretical estimation models work. The validity of estimation of these thermodynamic properties was tested by different models, which were selected attending to ease of use, wide range of application and accuracy. From the obtained results we can conclude that an adequate agreement between experimental and computed data, both in magnitude or sign in all range of compositions, was observed. [ABSTRACT FROM AUTHOR]

This paper analyzes the source of n-alkanes in sediments spanning 63 years since 1943 from Songhua Lake, using the method of correspondence analysis and geochemical index. The area of Songhua Lake is 554 km2, and its ecological problems affect hundreds of thousands of people in the basin. The concentration of total n-alkanes (C13–C36) in the sediments ranged from 20.39 to 168.35 μg/g, averaged at 72.58 μg/g, indicating that the Songhua Lake has an ecological risk of n-alkanes and should be taken seriously and protected. The analysis of geochemical indexes, including main carbon distributions (MH), LMW/HMW ratio, Paq, average chain length and so on, shows the n-alkanes in the Songhua Lake sediments are mainly derived from modern higher terrestrial plants, followed by human activities, and a small part from aquatic vascular plants and algae. Moreover, the source and sedimentary history of n-alkanes in Songhua Lake were carried out by corresponding analysis. And the correspondence analysis could be a feasible and effective means of source tracing. [ABSTRACT FROM AUTHOR]

Leaf wax n- alkanes are one of the most abundant molecular biomarkers, and they have tremendous potential for climate study. To understand the relationship between distribution characteristics of terrestrial higher plant long chain n- alkanes and climate, we assessed the correlation between average chain length (ACL 25-33)/carbon preference index (CPI 25-33) and mean annual temperature (MAT), growing season temperature (GST), and mean annual precipitation (MAP) and growing season precipitation (GSP) over the Tibetan Plateau (TP). It is important to note that the distribution characteristics of these long chain n- alkanes must be determined in surface soils and surface lake sediments. Statistical analysis and multi-proxy approaches (CPI and Paq) were applied to deal with this problem. The answer was that the long-chain n- alkanes corresponding to the conditions (CPI 25-33 ≥5, aquatic macrophyte versus aquatic macrophyte and terrestrial plant ratio Paq≤0.20) were basically derived from terrestrial higher plants. Using these long chain n- alkanes to assess the correlation between ACL 25-33 /CPI 25-33 and MAT, GST, MAP and GSP, we concluded that (i) weak positive correlations between ACL 25-33 and MAT/GST were observed on the TP. Under high temperatures, the ACL values of terrestrial higher plants will increase to reduce cuticular transpiration. (ii) there are negative relationships between CPI 25-33 and MAP/GSP. (iii) based on the studies of two proxies (ACL and CPI) for paleoclimate application, the long-chain n- alkane ACL 25-33 may become a useful qualitative indicator of temperature change in paleoclimate studies from Xining Basin, Ximen Co, Glacially eroded lake, and Lake Dangxiong Co on the TP. CPI 25-33 values might serve as a qualitative indicator of precipitation in paleoclimate studies when the plant species do not vary on the TP. [ABSTRACT FROM AUTHOR]