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1. Opracowanie rekordu ze środkow MNiSW, umowa Nr 461252 w ramach programu "Spoleczna odpowiedzialnośc nauki" - modul: Popularyzacja nauki i promocja sportu (2021). 2. This work was financially supported by the Ministry of Science and Higher Education as a statutory activity of Technical Physics Applications Department of the Military University of Technology.

A method to achieve the synthesis of highly substituted spirocyclic cyclobutanes is disclosed. The reaction involves the catalytic arylboration of cyclobutenes. Depending on the substitution pattern of the cyclobutene, either a Cu/Pd- or a Ni-catalyzed reaction was utilized. In the case of the Cu/Pd catalyzed reactions, the identification of a Cu-complex for arylboration was crucial to observe high selectivity. The synthetic utility of the products is demonstrated, and the mechanistic details are discussed.

Comparative analysis of the composition of lipid biomarkers (n-alkanes and n-alkan-2-ones) in sphagnum mosses, herbaceous plants, heather dwarf shrubs, and peats of high bogs of Western Siberia was carried out by gas chromatography–mass spectrometry. It was shown that different marsh plant species differ in ratios between long-chain n-alkanes, and this fact makes it possible to diagnose the source of these compounds in peat. It was found that sphagnum peats occurring in high bogs formed in different natural and climatic conditions differ in the distribution of n-alkan-2-ones, which can be used for the reconstruction of paleoclimatic conditions.

Long chain n-alkanes of leaf waxes are widely used in paleoclimatic reconstructions. The application of these proxies depends on profound understandings gained from studies of the relationship between climatic factors and long chain n-alkanes in living plants. However, a lot of uncertainties still exist in the relationship due to the interactions among climatic factors, geographical and topographical factors, and phylogeny. In addition, unrealistic or inaccurate climatic data also introduce errors. To evaluate the effect of climate with minimized interfering factors, we conducted long-term measurements of leaf wax n-alkanes of the plants growing on Dongling Mountain, north China from 2004 to 2019, where a meterological observatory is located. On the whole, total n-alkane concentration (Σalk) was positively correlated mean annual precipitation (MAP); average chain length (ACL) was negatively related to MAP; carbon preference index (CPI) had poor correlations with all climate factors. Compared with Σalk, ACL is a better indicator that reflects annual precipitation. The coefficient of ACL vs. MAP is 0.0015/mm. However, MAP accounted for only 40% of the variability in the year-averaged ACL of all plants together due to the significant interspecific differences in the response of leaf wax n-alkane distribution to climatic parameters; thus, ACL should be employed in parallel with other proxies to quantitatively reconstruct paleoprecipitation. We conducted a sample reconstruction of paleoprecipitation using ACL records preserved in the annually laminated sediments of Maar Lake Twintaung, Myanmar. The results of reconstruction using ACL are completely consistent with the results of reconstruction using carbon isotope ratios of n-alkanes, and are highly consistent with historical documents.

Integration of palaeobotanical (spores, pollen, phytoliths and non-pollen palynomorphs) and organic geochemical proxies, such as stable isotopes of organic carbon (δ13C) and n-alkanes, for studying the evolution and palaeoenvironmental conditions of an archaeological site are rare in India. The evolution of a protohistoric-historic site at Erenda, situated in the eastern coastal region of India, has been studied by using multiple palaeobotanical and organic geochemical proxies assisted with AMS radiocarbon dates. The excavated site lies above Late Pleistocene–Early Holocene Sijua Formation. The absence of anthropogenic evidence in the Sijua Formation likely indicates inhabitable conditions in nearshore/estuarine marshy conditions. The earliest human settlements at the excavation site begin during the first millennium BCE after the initiation of habitable conditions along the coast. The presence of fungal spores and the dominance of C4 phytolith morphotypes indicate prevailing warm and humid climatic conditions and proximity to a freshwater body. The δ13C signature and n-alkane composition indicate the use of C4 grass for the construction of the mud and clay-built huts. The settlers most likely used to consume wild or domestic variety of rice, as evidenced by the presence of bilobate scooped morphotypes. The site was partly abandoned, covered with C3 and C4 vegetation and used as a dumping ground after 663 ± 92 BCE. This implies that people continued to live in the area but possibly moved to a nearby site while using the excavated site as refuse.

The present study mixed twelve kinds of n-heptadecane, n-octadecane, and n-eicosane composite phase transition materials to prepare two-component mixtures. The phase transition temperature and pote...

New phase equilibrium data of CO2 in n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane were measured at temperatures from 333.15 to 373.15 K up to 23.73 MPa by a constant-volu...

The carbon isotopic compositions (δ13C) of n-alkanes in various environmental samples have been previously proposed as suitable fingerprints for assessing the origin of organic matter (OM) in diverse environmental systems. However, with respect to using gas chromatography–combustion–isotope ratio mass spectrometry for the carbon isotopic analysis of n-alkanes, analytical uncertainty may often be caused by the co-elution of interfering unsaturated compounds (e.g., aromatic and branched compounds). Hence, we propose a simple but reliable method for purification that uses column chromatography. The performance of two different solid stationary phases (i.e., aluminum oxide and Ag+-impregnated silica) was compared in terms of their capacity to eliminate unsaturated compounds from total hydrocarbons and thus increase the precision of δ13C measurements. Compared to the use of an activated aluminum oxide column, elution from an Ag+-impregnated silica column allows more effective isolation of individual n-alkanes, which results in more precise δ13C measurements for diverse environmental samples. Thus, Ag+-impregnated silica column separation can be effective as a routine experimental technique for increasing the accuracy of the δ13C values for n-alkanes in OM, which includes a large proportion of unsaturated compounds.

Formation of oil-suspended sediment aggregates (OSAs) is believed to be one of the natural cleaning processes in the marine environment. In this study, we have investigated the formation processes of OSAs under different mixing periods (continuous mixing and with the addition of sediments in between), oil-sediment ratios (1:1, 1:2 and 2:1) and crude oils (Arabian Light (AL), Kuwait (KW) and Murban (MB)). The results revealed that size of OSAs significantly increased (up to ≈ 1.41 mm) with the addition of sediments. Aggregates (total 36) were extracted for n-alkanes and polycyclic aromatic hydrocarbons to quantify and assess their weathering and toxic levels. The maximum n-alkane depletion was 84% (111-02), 94% (212-02) and 84% (321-02) and PAH depletion was ≈ 72% (111-02), 79% (212-02) and 81% (311-03) for the OSAs of AL, KW and MB crude oils, respectively, for the different samples considered, indicating that n-alkanes were depleted relatively higher than the PAHs. The highest depletion of both n-alkane and PAHs has occurred in OSAs of 10-h continuous mixing. The depletion of both n-alkane and PAHs reduced after the addition of sediments, however, escalated the growth of OSAs, resulting in bigger size OSAs. The concentration of PAHs of all 36 OSAs is greater than 5000 ng/g, indicating very high PAH pollution. Though the formation of OSAs helps in cleaning the spill sites, the carcinogenic threat to the marine ecosystem caused by these OSAs cannot be ignored. This study is funded by the Department of Science and Technology through Climate Change Programme to VS.

SAFT-VR Mie is extended to quadrupolar molecules and their mixtures by incorporating an explicit Helmholtz contribution for quadrupole–quadrupole interactions. Two quadrupolar terms are considered:...

Modulation of the electronic structure of metal-based catalysts is a key to optimize the catalytic activity. Here, we have shown the electronic tuning of Ni by Mo species anchored on SAPO-11 (Ni–Mo...

The leaf wax n-alkanes in modern ecosystems serve as proxies for assessing the ecologic and climatic conditions in soils, sediments and other geologic archives, and potentially as baselines for future ecological changes. In this study, the concentrations and distributions of long-chain (C25-C35) n-alkanes in fresh mature leaves, leaf litter fall, and surface soil (0-5 cm) from 0.4 ha, low diversity (oak-hickory-maple), deciduous angiosperm forest are quantified. Owing to degradation and dilution, leaf litter (350 ± 227 μg/g dw) and soil (13 ± 13 μg/g dw) each contain significantly lower concentrations of long-chain n-alkanes than fresh mature leaves (574 ± 291 μg/g dw). The average chain length and odd-even predominance (OEP) of fresh mature leaves increased and decreased, respectively, in leaf litter and soil indicating preferential and progressive degradation of the more abundant C27 and C29 homologues relative to less abundant C31 and C33 homologues. A poor relationship between OEP and a normalised n-alkane ratio(s) demonstrates the large potential effects of inter- and inner-species variability and/or varying effects of degradation on leaf wax n-alkanes, and highlights the potential limitations of the endmember modelling in paleo reconstructions.

Background With the high demand for diesel across the world, environmental decontamination from its improper usage, storage and accidental spills becomes necessary. One highly environmentally friendly and cost-effective decontamination method is to utilize diesel-degrading microbes as a means for bioremediation. Here, we present a newly isolated and identified strain of Acinetobacter calcoaceticus (‘CA16’) as a candidate for the bioremediation of diesel-contaminated areas. Results Acinetobacter calcoaceticus CA16 was able to survive and grow in minimal medium with diesel as the only source of carbon. We determined through metabolomics that A. calcoaceticus CA16 appears to be efficient at diesel degradation. Specifically, CA16 is able to degrade 82 to 92% of aliphatic alkane hydrocarbons (CnHn + 2; where n = 12–18) in 28 days. Several diesel-degrading genes (such as alkM and xcpR) that are present in other microbes were also found to be activated in CA16. Conclusions The results presented here suggest that Acinetobacter strain CA16 has good potential in the bioremediation of diesel-polluted environments.

The effect of pH on the zeta potential of dispersions of individual n-alkanes C23H48 and C28H58 with particle sizes of the order of 100 nm, which were prepared by ultrasonic dispersion without the addition of surfactants, was studied. It is shown that at pH ranged from 4 to 12, the investigated n-alkanes form stable dispersions in water. They are characterized by a high zeta potential varying from −30 to −50 mV. The phase transition temperatures (melting point, crystallization temperature, formation of rotator phases) were determined for the dispersions using an optical method.

The Hulun Buir sandy land in northern China is located at the northern limit region of the East Asian summer monsoon (EASM) and is therefore sensitive to the extension of the front of the rainfall belt. Here we report an n-alkane and compound-specific carbon isotope record from the Holocene sediments of Lake Yiheshariwusu in the middle of the Hulun Buir sandy land. The sediments contain a suite of n-alkanes with a strong odd over even carbon number predominance, with the maximum contribution from nC31, which is a typical distribution in grassland regions. The low temperatures in this cold region greatly limit the growth of C4 plants and thus the long-chain n-alkanes in lake sediments are mainly derived from leaf wax lipids of C3 plants growing within the sandy land. In this C3-vegetation-dominated region, the δ13C27–33 value (weighted carbon isotope values of nC27– nC33) are regulated mainly by the physiological and biochemical responses of plants to water stress and are therefore interpreted as a proxy of effective precipitation or humidity. The δ13C27–33 time series shows a trend of gradually decreasing values that suggests an increase in effective precipitation since 8.5 ka (1 ka = 1000 cal yr BP). Relative droughts occurred during the intervals of 6.3–5.5, 4.1–3.6 ka, and during the last 200 years. In addition, the δ13C27–33 time series and comparable paleoenvironmental records from neighboring sites suggest opposite trends of summer monsoon rainfall between northeastern and southeastern China. We suggest that a coupled process between low and high latitudes (the western Pacific Subtropical High and the Okhotsk High) may have played a fundamental role in regulating the shift of the frontal rainfall belt and monsoon rainfall distribution in eastern China during the Holocene.

Excess molar enthalpies, HE, for the binary mixtures of 2-pentanol with n-alkanes(n-heptane, n-octane, and n-nonane) have been determined at three different temperatures T = (293.15, 298.15 and 303.15) K and normal atmospheric pressure over the entire composition range using a Calvet microcalorimeter. All mixtures show endothermic mixing with the maximum values of the excess enthalpies occurring in the n-alkane-rich region. The HE data are smoothed using Redlich–Kister equation. The applicability of the Treszczanowicz–Benson, ERAS,Renon–Prausnitz and Chen–Bagley models to correlate HE of studied mixtures is tested, and the agreement between experimental and theoretical results is satisfactory. Each model includes a self-association equilibrium constant that represents hydrogen bonding and an adjustable parameter that reflects physical interactions.

Surface sediment samples were collected along the margins of Lakes Dachaidan, Xiaochaidan, Gahai (Delinha), Chaka, Gahai, and Qinghai, and from the Jinyingtan peat deposit, to study the lipid geoch...

The Sanchi oil tanker collision in the East China Sea on January 6th, 2018 has caused worldwide attention due to its uniqueness. A considerable amount of highly volatile natural-gas condensate oil was spilled, burned and sank with the Sanchi tanker, this entirely new kind of maritime disaster has posed massive unknowns to the public. In this study, for better understanding of the evaporative behavior of condensate oils, two condensate oils were investigated under various laboratory conditions. The overall result demonstrates that the evaporation of condensate oils is highly dependent on the air-exposed time and the total loss of condensate oils could be more than 90% within a short time. However, a certain amount of the high-molecular weight and toxic oil contents such as phenanthrenes still highly remain in the aquatic system even after a long evaporation process, indicating their detrimental potentials to the aquatic organisms. Based on these data, for the Sanchi oil spill accident, it is assumed that although the evaporation weathering of the total condensate oil mass is probably tremendous, the long-term ecological risks of the remaining oil components in the marine environment are strongly recommended to be carefully evaluated.

A new technique to extract lipid biomarkers (n-alkanes and n-methyl-ketones) from forest litters and soils using the accelerated solvent extraction (ASE) method was developed. The maximum output of n-alkanes and n-methyl-ketones was obtained by sequential extraction using the chloroform : methanol mixture [3 : 1 (vol)] in the first two extraction cycles and chloroform in the subsequent two cycles. The extraction has been carried out at the temperature of 100°С, pressure of 10.3 MPa, and static extraction time of 5 min. The repeated chloroform treatment by ASE was shown to increase the output of long-chain n-alkanes and n-methyl-ketones.

The exploitation of phase change materials (PCMs) with excellent shape stability, considerable latent heat storage capacity, and superior thermal conductivity is essential for their applications in...

This work reported the n-alkanes contents in a 10 m peat core collected at Timbarap, Sarawak. Different biomarker proxies were used to understand the predominance of sources present in the tropical peatland of Borneo. The total concentrations of n-alkanes in selected depths of Timbarap peat core ranged between 0.01 and 12.60 μg/g with an average of 1.58 μg/g. The presence of strong odd-to-even predominance from higher molecular weight n-alkanes homologues with high values of carbon preference index (CPI) provide clear evidences of the terrestrial plant wax assemblages. Increment of low-molecular-weight n-alkanes provide an indicator of biogenic-aquatic organic materials. The ratios of isoprenoids (pristane and phytane) have shown that the peat core was under anaerobic and reducingdepositional conditions, which could result the predominance source that alternated between aquatic-biogenic and terrestrial-derived materials.

The content of nonacosan-10-ol and n-alkanes in needle waxes of twelve Pinus taxa (Pinus halepensis, P. heldreichii, P. mugo, P. nigra ssp. nigra, P. nigra ssp. dalmatica, P. peuce, P. pinaster, P. pinea, P. ponderosa, P. strobus, P. sylvestris, and P. wallichiana) were examined. In eight Pinus taxa (except of P. halepensis, P. pinaster, P. heldreichii and P. peuce) nonacosan-10-ol contents were examined for the first time. In all examined pines C29, C27 or C25 were the main n-alkane compounds. C range was mainly 18-33. In six Pinus taxa (P. mugo, P. nigra ssp. dalmatica, P. sylvestris, P. pinea, P. strobus and P. wallichiana) CPI and ACL values were examined for the first time. In the plane of Axis 1 (PCA), P. strobus, P. mugo, and P. wallichiana were strongly separated from P. heldreichii and P. pinea. In the plane of Axis 2, P. peuce, P. strobus, and P. wallichiana as well as P. heldreichii and P. pinea diverged from other examined species. In DA P. heldreichii, P. strobus, P. peuce, and P. wallichiana diversed. CA divided sections Pinus and Pinaster from section Strobi. This is the peer-reviewed version of the article: Nikolic, B. M.; Đorđević, I.; Todosijevic, M.; Mitic, Z.; Stefanović, M. A.; Stankovic, J. M.; Bojović, S.; Tešević, V.; Marin, P. D. Diversity of Nonacosan-10-Ol and n-Alkanes among 12 Pinus Taxa. Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology 2020, 0 (0), 1–8. [https://doi.org/10.1080/11263504.2020.1857867]

Deposited dust (DD) in urban environments contains carcinogenic organic compounds. The Indoor air quality is greatly affected by heating, ventilation, and air conditioning systems (HVAC), and in the Middle East most of the buildings are equipped by HVAC on top of them. It is possible that the DD on the roof near this equipment would be transferred to an indoor area. For these reasons, 40 samples of the over the roof DD were prepared, and organic compounds (16PAH compounds, 20n-alkane homologs, 8hopanes, and 6steranes) of DD were extracted using Soxhlet and analyzed by GC-MS. Source identification of organic compounds conducted by ring classification, diagnostic ratios, and factor analysis (FA). The results showed that the average (±SD) of total PAHs, n-alkanes, hopanes and steranes in DD were 1356.00 (±291.45) ng kg−1dw, 3211.65 (±969.18), 146.37 (±79.45) and 469.76 (±188.25) µg.g_1dw, respectively. The highest concentration of organic compounds was in the city center, where traffic congestion is common. Diagnostic ratios of n-alkanes results showed the dominant source is vehicular emission. FA results indicated vehicular emission and biogenic sources. In agreement, the results of sterane and hopane profiles confirm these results. On the other hand, the PAHs diagnostic ratios results indicated petroleum combustion sources. In this regard, FA findings showed combustion from vehicular emission and natural gas and wood combustion were the main factors. Furthermore, the incremental lifetime cancer risk was calculated as 8.45× 10−12 for children and 9.80 × 10−7 for adults, and the imposed risk was negligible.

The orientation of hydrocarbon chains plays a key role in the applications of organic materials. And chain folding in the process of molecular orientation is also of great significance for the design of organic molecular thin films. The effect of chain length and simulation temperature on the isothermal orientation of n-alkanes on graphene surface is studied by molecular dynamics simulation in this paper. And the chain folding is also described. The n-alkanes can form perpendicular ordered structure, parallel ordered structure or perpendicular orientation at relative low temperature and parallel orientation at relative high temperature on graphene surface. The chain fold happens when long n-alkanes form perpendicular ordered structure on graphene surface. And the simulation results show the interactions of n-alkane−graphene and n-alkane−n-alkane affect chain fold.

Barium tetrafluorobromate Ba(BrF4)2 is a brominating agent for hexane, octane, and decane. The reaction occurs under very mild conditions at –25 to –20°C and results in preferential formation of 2-bromoalkanes.

This study investigates the magnitude and direction of stable C and H isotope shifts of n-C15–30 alkanes from biodegraded oils sourced from Type II (Oil suite S) and Type II/III (Oil suite H) kerogens. Compound-specific isotope data show a 2.0‰ 13C-enrichment and no D-enrichment of n-alkanes in the most biodegraded oil from sample suite S. Similarly, there is a 1.5–2.5‰ 13C-enrichment and no D-enrichment in Oil suite H. Overall, there is a &lt, 2.5‰ δ13C and &lt, 20‰ δD variability among individual n-alkanes in the whole sequence of biodegradation. N-alkanes from the least biodegraded Oil H samples are 2–4‰ 13C-enriched in comparison with the least biodegraded Oil S. However, there are no differences in the δD values of n-alkanes in these samples. Our indirect isotopic evidence suggests (1) a site-specific biodegradation process, most likely at position C-2 and/or C-3 or another site-specific process, and (2) a significant D/H exchange between organic compounds in the source rock and isotopically similar marine formation waters. We conclude that, unlike δD methodology, investigation of δ13C composition of n-alkanes has strong potential as a supplementary tool for oil–oil and oil–source-rock correlation even in biodegraded oils when n-alkanes are present.

Ultrasonic speeds (u) and refractive indices (n) of the binary liquid mixtures of ethanol with diisopropyl ether (DIPE) or cyclohexane or n-alkane (C6-C9) were experimentally measured from 298.15 to 318.15 K over entire composition range. Using these measurements deviation in ultrasonic speed (Δu), deviation in refractive index (Δn), excess intermolecular free length (Lf E ) and excess isentropic compressibility (Ks E ) were calculated and fitted with Redlich-Kister equation. The Δu values are negative for all binary mixture and magnitude of negative deviation for binary mixture of ethanol and n-alkane decreases as chain length increases. At equimolar composition, Ks E follows the order: n-hexane > n-heptane >n-otcane > n-nonane > diisopropyl ether > cyclohexane. Experimental results were analyzed to understand the various molecular interactions present in the binary mixtures. The u values for all binary liquid solutions were also correlated using different empirical correlations such as Nomoto, impedence dependence relation and van Dael ideal mixing relation. The u for binary liquid mixtures were also computed theoretically using Schaaff′s collision factor theory. Free length theory was used to compute inter-molecular free length (Lf E ). Various correlations e.g., Arago-Biot (A-B), Gladstone-Dale (G-D), Heller (H), Lorentz-Lorentz (L-L), Eyring-John (E-J), Newton (Nw) and Weiner (W) were used for calculating refractive indices of selected systems theoretically.

Owning to the sensitivity of enhanced oil recovery process, the accurate approximation for the viscosity of n-alkane and bitumen mixture is important to decrease uncertainty. Current study ...

The variation and its level of hydrogen isotopic composition of individual n-alkanes in sediments from different latitudes and climatic environments from immature to post-mature are still unclear. ...

The origin of mid-chain (C23 and C25) and C27 n-alkanes in sedimentary archives can be ambiguous. In coastal Portugal, a peat deposit representing a mid-Holocene paleowetland (PRC-South) that was initially dominated by Sphagnum presents an ideal setting for assessing methods of mid-chain n-alkane source elucidation. In particular, we examine a comprehensive record of the difference in δD between mid-chain (δDmid) and C29 n-alkanes (ΔDmid-C29) in relation to n-alkane molecular distributions and compound-specific δ13C values in order to improve interpretations of paleoenvironmental change and evaluate the reliability of δDmid values for hydrologic reconstructions. Mid-chain n-alkane production remains significant at PRC-South after a substantial Sphagnum decline, yet an increase in ΔDmid-C29 values indicates a primarily terrestrial origin of mid-chain n-alkanes in the upper 50 cm of the deposit. This progression towards more positive ΔDmid-C29 values coincides with a relative increase in n-C27 abundance and potentially represents the replacement of Sphagnum moss by tree species that produce abundant mid-chain n-alkanes, such as Betula, Quercus, or Fagus spp. According to our analysis, ΔDmid-C29 displays promise as a tool for mid-chain n-alkane source attribution in Sphagnum paleoenvironments, but interspecies variability of hydrogen isotope fractionation in Sphagnum mosses and terrestrial vegetation could critically hinder its application. Our use of ΔDmid-C29 at PRC-South ultimately exemplifies the importance of accounting for vegetation composition when qualitatively or quantitatively interpreting sedimentary δDn-alkane values, particularly in Sphagnum wetlands.

Dynamic viscosities (η) of the binary liquid mixtures of 2-propanol (1)+n-alkanes (C6, C7, C9) (2) at T=288.15 K to 303.15 K and ethanol (1)+n-alkanes (C6, C7, C8) (2) at T=308.15 K to 318.15 K were experimentally measured over the whole composition range. Experimental values of η were used to compute the deviation in dynamic viscosity (Δη) and these Δη values were correlated with the Redlich-Kister equation. The η values of binary mixtures were also calculated using several empirical correlations and mixing rules like Grunberg-Nissan, Tamura-Kurata, Kati-Chaudhari and McLaughlin-Ubbelohde and found that the Grunberg-Nissan correlation gave the best estimation. The Δη values were also predicted by an approach given by Singh et al. [Indian J Chem 29, 263 (1990)].

N-alkane-based proxies are widely employed to reconstruct paleoclimate and paleoenvironment in lacustrine environments. However, little is known about the influence of microbially mediated alkane-degradation on n-alkane-derived proxies. In this study, the chemical composition of n-alkanes and microbially mediated n-alkane degradation potential were investigated in the surface sediment samples collected from seven lakes with a range of salinity from freshwater to salt saturation on the northern Qinghai-Tibetan Plateau (QTP). The results showed that the chemical composition of n-alkanes differed among the studied QTP lakes. Significant correlations were observed between salinity and some n-alkane-based paleoclimate and paleoenvironment proxies, such as ratio of C21−/C22+, average chain length (ACL) and carbon preference index (CPI). This suggested that salinity may affect the validity of some n-alkane-based paleoclimate and paleoenvironment proxies. Alkane-degrading bacteria were abundant and widespread in the studied freshwater and saline/hypersaline lakes but were minor or absent in salt-saturation lakes. The obtained alkane-degrading bacterial strains showed active ability to degrade n-hexadecane. This suggested that the salinity influence on the n-alkane distribution may be partially related to microbial degradation, which awaits further in-situ investigation. So salinity variation should be taken into account when using n-alkane-based proxies for reconstructing paleoclimate and paleoenvironment in lakes.

Aviation industry has the challenge of halving CO2 emissions by 2050, as compared to 2005. An alternative are drop-in biofuels, which are sustainable and fully compatible with aircraft engines and ...

In this work, a predictive nonrandom two-liquid (NRTL) equation analyzed from binary experimental data is proposed to model the solid–liquid equilibrium in the n-alkanes mixture. The predictive NRT...

We present direct room-temperature vapour pressure measurements for eight semi-volatile n-alkanes of atmospheric importance. Measured vapour pressures range from 8.4 ± 1.6 × 10−3 Pa for C17, to 1.7 ± 0.6 × 10−8 Pa for C31. The new measurements for C17–C18 are in reasonable agreement but at the lower end of values in the literature; the new measurements for C28 and C31 are one-to-two orders of magnitude higher than most literature values, but six orders of magnitude higher than the lowest values in the literature. Our measurements are suitable for atmospheric aerosol modelling and interpretation of environmental measurements, interpolated in carbon number where necessary, and extrapolated over temperatures relevant to the atmospheric boundary layer using the Clausius-Clapeyron equation with literature values of the enthalpy of vaporisation.

In this work, two crossover procedures were applied to the Soave-Redlich-Kwong (SRK) equation of state (EoS) in order to describe the thermodynamic behavior of hydrocarbons from far away up to close to the critical point. The first one is based on a renormalization group theory method, which uses a recursive procedure originally proposed by White and coworkers (Salvino and White, J. Chem. Phys. 96 (1992) 4559–4568). The second one incorporates the scaling laws close to the critical point into the cubic EoS, and was developed by Kiselev (Kiselev, Fluid Phase Equilibria, 147 (1998) 7–23). The classical and crossover SRK EoS are applied to describe the phase behavior of pure n-alkanes (from methane to n-decane), and the comparison with experimental data indicates that the non-mean-field models are superior to the classical one for the representations of vapor-liquid coexistence data, isothermal pressure-density data and critical properties. Additionally, a thorough comparison of the two crossover approaches is done indicating the advantages and disadvantages of each approach.

In this paper, we have extended our previous study of the static and dynamic properties (self-diffusion coefficient Dself and friction coefficient ζ) of liquid n-alkane systems up C400 at s...

This study aims to determine the content of n-alkanes in the sediment around the coast of Makassar using the MOPI (Marine Oil Pollution Index) indicator. The method includes the sediment sampling from nine different stations with the Phleger Corer Sampler in gravimetric analysis to identify the concentration of organic material extract and aliphatic fraction. To identify the characteristic of n-alkane hydrocarbons, gas chromatography of mass spectra method was applied. The results of the aliphatic fraction (F1) analysis of the coastal sediments which were contaminated with low biogenic - petrogenic have a MOPI scores of 3, which is supported by a high UCM (Unresolved Complex Mixture) and n-alkane identified between C1-C44. While the sediments that come from natural processes, pure - biogenic and biogenic, have MOPI scores ​​between 1 and 2. This is supported by the chromatogram profile with an area of ​​UCM generally smaller by n-alkanes identified between C15-C58

The liquid–liquid extraction of a nitrogen-containing aromatic “pyridine” and nitrogen/sulfur-containing aromatic “benzothiazole” from n-hexane and n-heptane using deep eutectic solvents (DESs) was...

Molecular compositions and stable carbon isotope ratios (δ13C) of n-alkanes and fatty acids (FA) were investigated in urban aerosols from Beijing, China. Seasonal trends for n-alkanes showed a high...

Molecular chaperones are known to assist proteins in achieving their native state conformations by providing them a confined environment through encapsulation and altering their free energy landscapes. Instances of structural rearrangements in molecules confined to narrow nano-dimensional spaces are often encountered in vivo where the intermolecular interactions play a decisive role in determining the molecular conformations. As a simple analogue, we model a system of n-alkanes encapsulated into a supramolecular host cavitand forming a capsular host-guest assembly of volume less than half a cubic nanometer. Here, we provide a detailed insight of process of host-induced conformational changes in guests by exploring the conformational dynamics. Interestingly, the conformational analysis reveals that the host apart from being able to fold some of the guests into coiled conformations also unfolds a few of the guests while rearranging its hydrogen-bonded network.

Oil hydrocarbon fingerprints derived from polycyclic aromatic and aliphatic hydrocarbon were analyzed in marine organisms of various aquatic species muscles collected from 10 different sites along ...