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Background: For a long time, the prevailing viewpoint suggests that shorter telomere contribute to chromosomal instability, which is a shared characteristic of both aging and cancer. The newest research presented that T cell immune deficiency rather than chromosome instability predisposes patients with short telomere syndromes to some cancers. However, the relationship between genetically determined telomere length (TL) and immune cells remains unclear. Methods: The two‐sample Mendelian randomization analysis was conducted to elucidate the potential causal relationship. The genetic data of TL and immune cells were obtained from the Genome‐Wide Association Study. The inverse variance weighted (IVW) method was used to estimate the effects primarily and another four methods were as a supplement. Sensitivity analysis was used to test the results. Results: The IVW method showed a significant correlation between TL and the percentage of T cells in lymphocytes (odds ratio [OR]: 1.222, 95% confidence interval [CI]: 1.014–1.472, p =.035), indicating that shorter TL significantly increases the risk of low T cell percentage. Further analysis of T cell subsets indicated that shorter TL may primarily lead to a lower percentage of Natural Killer T cells (OR: 1.574, 95% CI: 1.281–1.935, p <.001). Analysis of B cell subsets revealed that shorter TL may be associated with a higher percentage of Naive‐mature B cells, and a lower percentage of Memory B cells. And the sensitivity analysis indicated the validity and robustness of our findings. Conclusion: In summary, our findings suggest that shorter TL may be associated with a decline in the percentage of T cell, as well as impediments in the differentiation of B cell, consequently leading to the onset of immunosenescence and immunodeficiency. The relevant mechanisms and potential therapeutic avenues still need further investigation. Shorter telomere length may be associated with a decline in the percentage of T cell, as well as impediments in the differentiation of B cell, consequently leading to the onset of immunosenescence and immunodeficiency. [ABSTRACT FROM AUTHOR]

Background: Previous observational studies have identified an association between rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). However, the causal relationship between RA and IBD in the East Asian population remains uncertain. Methods: The two-sample Mendelian randomization (MR) analysis was conducted to elucidate the potential causal relationship between RA and IBD. Summary-level data from genome-wide association studies (GWAS) in the East Asian population were utilized, including RA (n = 19,190) and IBD (n = 6543), including Crohn's disease (CD, n = 5409) and ulcerative colitis (UC, n = 4853). The inverse variance weighted (IVW) method was employed as the primary analysis, supplemented by weighted median, weighted mode, simple median, MR-Egger, and MR-PRESSO analyses. Sensitivity analyses were conducted to assess the robustness of the results. Genetic data for RA (n = 22,515) were utilized to validate the findings in the East Asian population. Results: The IVW method showed no significant association between genetically predicted RA and overall IBD in the East Asian population (OR = 1.028; 95% CI: 0.935–1.129; P = 0.567). The subgroup analysis revealed a positive association between RA and CD (OR = 1.268; 95% CI: 1.108–1.451; P < 0.001), while a negative association was observed with UC (OR = 0.839; 95% CI: 0.710–0.993; P = 0.041). These findings were supported by another set of RA data. Additionally, an SNP rs2071475 was identified to play an important role in CD and UC. Conclusion: This study revealed a potential increased susceptibility to CD and a decreased susceptibility to UC in the East Asian population with RA. Furthermore, a key SNP rs2071475 was discovered along with its opposite effects in CD and UC. These findings provide new evidence for research on the corresponding molecular mechanisms and offer insights for clinical management of RA-associated IBD. [ABSTRACT FROM AUTHOR]

• Intramolecular C isotopes of propane were analyzed in overmature shale gases. • Unusual 13C depletion observed in the central C of all propane samples. • Inter- and intramolecular isotopes support C 2+ alkanes formed by C 1 polymerization. Abiotically synthesized hydrocarbons are significant in the fields of astrobiology, biosphere, energy, environment, and geology. Abiotic hydrocarbons have never been unambiguously proven to occur in common sediments partly because identifying these components in crustal settings is challenging as they share similar characteristics with hydrocarbons of biotic origin. In this study, we measured intramolecular carbon isotopes of 10 propane samples from Longmaxi shale in the Sichuan Basin, China, and found distinct 13C-depletion in the central position carbon with its δ13C decreased by −8.0 to −7.0‰ (Vienna Pee Dee Belemnite) with respect to terminal carbons. The δ13C value of central carbon (H 3 C–#CH 2 -CH 3) in propane is equal to the second methyl (H 3 C–#CH 3) in ethane possibly resulting from surface catalytic polymerization reactions of methane. Our novel findings indicate that the abiotic synthesis of C 2+ hydrocarbons by the surface catalyzed polymerization of methane occurs in commercial gas reservoirs and suggest that this process may be more common than previously thought in methane-rich scenarios on Earth and other planets. [ABSTRACT FROM AUTHOR]

Highly mature solid bitumen, a residue of oil cracking, is widespread in the lower Paleozoic paleo-oil reservoirs of southern China. Solid bitumen is not a simple, pure component, but rather a compositionally and structurally variable mixture of materials. This study investigated the formation of thermogenic solid bitumen and the effects of oil composition and reservoir environment. A series of seven gold-tube pyrolysis experiments were conducted: three used the main fraction groups (i.e., saturated, aromatic, and resin + asphaltene fractions) of crude oil to evaluate the effect of oil composition on the formation of solid bitumen during cracking; the other four tested the effects of water and pressure in reservoirs by simulating the cracking of crude oil under different reservoir conditions. Quantitative analyses of pyrolytic products (including methane, C 2 –C 5 gaseous hydrocarbons, C 6 –C 13 light hydrocarbons, C 13+ heavy hydrocarbons, and solid bitumen) indicated that thermogenic solid bitumen formed at different stages of oil cracking, and its formation was clearly affected by oil composition. In contrast, water and pressure in the reservoir had little effect on the formation of solid bitumen. [ABSTRACT FROM AUTHOR]

An abundance of organic matter is present as solid bitumen in highly mature shales. Changes in chemical structure of solid bitumen during catagenesis could alter the way its mechanical properties evolve. This study considers a series of solid bitumen samples artificially produced from the pyrolysis at 420–618 °C of soluble organic matter which originated from Maoming shale, to examine alternations in their chemical structure, nano-morphological and mechanical properties during maturation. Solid-state 13 C nuclear magnetic resonance spectroscopy and elemental analysis were employed to characterize the structural changes. Young's modulus and microstructures were determined by atomic force microscopy. The results show that both structural (including C/H atomic ratio and carbon aromaticity) and mechanical (Young's modulus) variations in solid bitumen exhibit two staged evolutions (i.e., wet gas stage and dry gas stage) during maturation. In the wet gas stage (EasyRo 1.85%–2.64%), the C/H ratio and carbon aromaticity increase substantially with maturation, and the solid bitumen is relatively compliant with an average Young's modulus varying from 2.7 ± 0.6 to 3.0 ± 0.6 GPa. When maturity reaches to dry gas stage (EasyRo 2.64%–4.59%), structural parameters do not change greatly, whereas solid bitumen becomes much stiffer with modulus rising sharply to 7.2 ± 1.1 GPa at EasyRo 3.49% and further gently to 8.8 ± 1.4 GPa at EasyRo 4.59%. Concomitantly, great variations are observed on surface morphology, and the degree of heterogeneity in solid bitumen is recorded to be increasingly high along thermal simulation. Given the strong correlation between structural parameters and Young's modulus, we suggest that the stiffening of solid bitumen is extensively affected by its structural condensation due to the loss of aliphatic carbons and the increase of aromaticity. [ABSTRACT FROM AUTHOR]

Low-pressure gas adsorption analysis based on density functional theory (DFT) or non-local DFT (NLDFT) has become an increasingly reliable method for the characterization of nanopore structures in porous materials. The accuracy of the characterization of nanoporous structures in organic-rich shales can be improved by using a variety of probe molecules and models: carbon dioxide, nitrogen, and argon are considered using the CO 2 -DFT, N 2 /Ar-DFT, N 2 /Ar-NLDFT models and so on. Three types of shale sample with different maturity levels (i.e., mudstone, oil shale, and gas shale) are studied to investigate the effect of soluble components and maturity on the nanopore structure. The results show that the CO 2 -DFT and N 2 /Ar-DFT models are more suitable than the other models based on DFT or NLDFT and that composite CO 2 –Ar adsorption analysis is the most accurate for assessing micro-, meso-, and macropores in the shales over the complete nanopore range (∼0.33–100 nm). The best method (i.e., DFT-based CO 2 –Ar analysis) is applied to characterize the pore structures of original and extracted shales, revealing that solvent extraction can increase the total pore volume (i.e., micro-, meso-, and macropore). However, the effect is not obvious in overmature gas shale. Micropores in the three shales display favorable pore size distributions of 0.4–0.7, 0.7–0.9, and 1.0–2.0 nm, respectively. [ABSTRACT FROM AUTHOR]

The influence of oil-expulsion efficiency on nanopore development in highly mature shale was investigated by using anhydrous pyrolysis (425–600 °C) on solvent-extracted and non-extracted shales at a pressure of 50 MPa. Additional pyrolysis studies were conducted using non-extracted shales at pressures of 25 and 80 MPa to further characterize the impact of pressure on pore evolution at high maturity. The pore structures of the original shale and relevant artificially matured samples after pyrolysis were characterized by using low-pressure nitrogen and carbon-dioxide adsorption techniques, and gas yields during pyrolysis were measured. The results show that oil-expulsion efficiency can strongly influence gas generation and nanopore development in highly mature shales, as bitumen remained in shales with low oil expulsion efficiency significantly promotes gaseous hydrocarbon generation and nanopore (diameter < 10 nm) development. The evolution of micropores and fine mesopores at high maturity can be divided into two main stages: Stage I, corresponding to wet gas generation (EasyRo 1.2%–2.4%), and Stage II, corresponding to dry gas generation (EasyRo 2.4%–4.5%). For shales with low oil expulsion efficiency, nanopore (diameter < 10 nm) evolution increases rapidly in Stage I, whereas slowly in Stage II, and such difference between two stages may be attributed to the changes of the organic matter (OM)’s mechanical properties. Comparatively, for shales with high oil expulsion efficiency, the evolution grows slightly in Stage I, not as rapidly as shales with low efficiency, and decays in Stage II. The different pore evolution behaviors of these two types of shales are attributed to the contribution of bitumen. However, the evolution of medium–coarse mesopores and macropores (diameter >10 nm) remains flat at high maturation. In addition, high pressure can promote the development of micropores and fine mesopores in highly mature shales. [ABSTRACT FROM AUTHOR]

Solid bitumen is widespread throughout lower Paleozoic paleo-reservoirs in southern China. However, the processes that control its formation and evolution remain unclear. Here, we document temporal changes in the yield and characteristics of solid bitumen generated during oil cracking using an experimental approach involving the anhydrous pyrolysis of crude oil. The results indicate that solid bitumen is predominantly produced in environments of high thermal maturity associated with the dry gas stage of oil cracking (i.e., during rapid methane generation and C 2 –C 5 gaseous hydrocarbon destruction), with maximum solid bitumen yields up to about 42% of the original amount of crude oil. A near linear relationship exists between solid bitumen yields and methane abundance during the main stage of solid bitumen formation, although there is no clear variation in the δ 13 C values of solid bitumen produced at any stage of this process. This suggests that the isotopic composition and distribution of solid bitumen within a reservoir can be used to identify hydrocarbon sources, delineate the range of paleo-reservoirs, and assess the size of paleo-oil reservoirs and oil-cracked gas reservoirs within a basin. [ABSTRACT FROM AUTHOR]

In order to better understand the generation and primary source of mature thermogenic gas in shale, and to evaluate the residual gas generation potential of the shale at different maturity levels, we performed pyrolysis experiments on an organic-rich marine shale and its kerogens prepared by artificial maturation. The results indicate that the thermal maturation of organic matter in the shale can be divided into four stages: oil generation (<0.6–1.0% EasyRo), condensate generation (1.0–1.5% EasyRo), wet gas generation (1.5–2.2% EasyRo), and dry gas generation (2.2–4.5% EasyRo). Thermogenic methane is produced mainly during wet gas and dry gas generation, while most of the C 2+ hydrocarbon gases are produced during condensate and wet gas generation. The kerogen at a thermal maturity of >3.0% EasyRo still has methane generation potential. Whether or not gas generation potential of a highly mature kerogen has a commercial significance depends on its organic matter richness, thermal maturity internal and some other geological factors, such as caprock sealing property, reservoir physical property, and tectonic movement. In addition to the gas produced from kerogen cracking, gas is also generated from the secondary cracking of residual bitumen as maturation progresses. Early hydrocarbon expulsion during oil generation likely has a considerable effect on the amount and δ 13 C values of the late-generated shale gas. The lower the oil expulsion efficiency of a shale, i.e., the more retained bitumen, then the higher the productivity of post-mature shale gas and comparative enrichment of the latter in 1 2 C. [ABSTRACT FROM AUTHOR]

The combination of low-pressure N 2 and CO 2 adsorption could provide an effective approach for characterizing the pore structure of shales. Although gas adsorption methods generally do not destroy the pore structure during experimental process, sample particle sizes could significantly affect experimental results that can approach or deviate from the real value. Therefore, the determination of pore structure is closely related to the sample particle size. In the current study, 4 fresh core samples of different compositions and total organic carbon (TOC) ranges collected from the Sichuan Basin were analyzed to elucidate the effect of sample particle size on the determination of pore structure parameters. Samples were ground and then sieved into seven groups based on particle size ranges, i.e., < 60, 60–80, 80–100, 100–120, 120–140, 140–200 and > 200 mesh, for measurements of low-pressure N 2 and CO 2 adsorption, TOC contents, and X-ray diffraction (XRD) mineralogy. TOC results show a slight enrichment whereas XRD minerals vary irregularly, with sample particle size decreases. Meanwhile, the TOC and mineral contents show insignificant statistical relation with pore structure parameters in all sample particle size ranges. Therefore, variations in organic matter content and mineral composition that result from sieving are unlikely to have a significant influence on the pore structure of shale. Rather, sample particle size may be the most important control on pore structure characteristics in the samples analyzed in this study. The relative standard deviations (RSDs) for Brunauer–Emmett–Teller (BET) N 2 surface areas, Dubinin–Radushkevich (D–R) CO 2 micropore surface areas and non-local density functional theory (NLDFT) N 2 and CO 2 nanopore surface areas measurements are < 5%, within analytical error. Therefore, in the studied grain size range (60–200 mesh), the sample particle size shows insignificant effects on surface area results. However, samples with smaller particle size have a greater effect on pore volume and pore size, especially for pore size distribution (PSD) of N 2 low-pressure adsorption. The RSDs of the Barrett–Joyner–Halenda (BJH) pore volumes and BET pore sizes of all samples in the 140–200 mesh range are obviously greater than the values of other mesh ranges. Moreover, in the dV/dlogw plots of PSD analysis, high N 2 peaks and new N 2 peaks appeared in the 10–100 nm pore-width range, particularly for samples in the > 140 mesh range. The 60–140 mesh particle-size range is therefore recommended for N 2 low-pressure adsorption. Finally, the sample particle size has insignificant effect on the pore system parameters for grains in the 60–200 mesh range for CO 2 low-pressure adsorption. Overall, the results confirm that the 60–140 mesh particle-size range can be used for both N 2 and CO 2 low-pressure adsorption measurements. [ABSTRACT FROM AUTHOR]

On the basis of the results of simulation experiments, now we better understand the contribution of high carbon number hydrocarbons to diamondoid generation during thermal pyrolysis of crude oil and its sub-fractions (saturated, aromatic, resin, and asphalene fractions). However, little is known about the effect of volatile components in oil on diamondoid generation and diamondoid indices due to the lack of attention to these components in experiments. In this study, the effect of volatile components in oil on diamondoid generation and maturity indices was investigated by the pyrolysis simulation experiments on a normal crude oil from the HD23 well of the Tarim Basin and its residual oil after artificial volatilization, combined with quantitative analysis of diamondoids. The results indicate that the volatile components (≤ nC) in oil have an obvious contribution to the generation of adamantanes, which occurs mainly in the early stage of oil cracking (Easy R<1.0%), and influences the variations in maturity indices of adamantanes; but they have no obvious effect on the generation and maturity indices of diamantanes. Therefore, some secondary alterations e.g., migration, gas washing, and biodegradation, which may result in the loss of light hydrocarbons in oil under actual geological conditions, could affect the identification of adamantanes generated during the late-stage cracking of crude oil, and further influence the practical application of adamantane indices. [ABSTRACT FROM AUTHOR]

Thermal maturation-related variations in the abundance and distribution of diamondoids in source rocks were investigated by thermal simulation experiments on extracts and kerogen obtained from a same marine shale, and by quantitative analysis of diamondoids within pyrolysates using highly sensitive and selective gas chromatography–triple quadrupole mass spectrometry (GC–MS–MS). The results indicate that diamondoids within the marine shale are generated mainly during 0.8%–1.7% EasyRo, generally deriving from extractable organic matter within source rocks, and are destroyed after 1.7% EasyRo to be entirely removed by ca. 3.0% EasyRo. Ternary plots of the relative distribution of diamondoids and bivariate diagrams for diamondoid parameters (e.g., DMA/MD vs. DMAI-1, and DMA/MD vs. TMAI-1) show systematic changes in diamondoids with increasing thermal maturity (expressed as EasyRo). [ABSTRACT FROM AUTHOR]

Highlights: [•] Diamondoids concentration depends on oil type, evaporation extent, boiling point. [•] Evaporation has different effects on adamantane and diamantane indices. [•] Some diamondoid ratios can be used to deduce the evaporation extent of oils. [•] Slight-moderate evaporation extent can be estimated using diamantane concentrations. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the origin and evolution of adamantanes and diamantanes in petroleum, based on the results of pyrolysis experiments on different group components of crude oil and quantitative analyses of diamondoids in the pyrolysates. Results show that the formation and evolution of lower diamondoids in petroleum occurs in three main stages: (1) early generation during the formation of oil (< ca. 0.8–1.0% EasyRo), (2) generation during the cracking of oil (>1.0% EasyRo), and (3) destruction during the late period of oil cracking. The lower diamondoids that formed during the early generation stage include free diamondoids present in the original oil and diamondoids released or transformed from group fractions of oil at relatively low levels of maturity (< ca. 0.8–1.0% EasyRo). During the process of oil cracking, all four group fractions (saturated, aromatic, resin, and asphaltene fractions) can produce adamantanes and diamantanes. Overall, adamantanes are generated primarily within the maturity range 1.0–2.3% EasyRo, and diamantanes within the maturity range 1.6–2.7% EasyRo. Group composition of the oil is probably a major factor controlling the yield and distribution of diamondoids in the main generation stage. The yield ratios of diamondoids can be used as maturity indices to assess the thermal maturity of oil, while the isomerization ratios of diamondoids are potential source facies indices for the generation stage of diamondoids. The destruction of diamondoids is observed at thermal maturity ranges >2.3% EasyRo in adamantanes and >2.7% EasyRo in diamantanes. The thermal stability of diamondoid compounds becomes a critical factor influencing the isomerization index of diamondoids during the destruction stage. The isomerization ratios of some diamondoids (e.g., MAI, DMAI-1, DMAI-2, TMAI-1, TMAI-2, and EAI) are well correlated with maturity within certain maturity ranges, indicating that isomerization indices provide good estimates of the thermal maturity of highly cracked oils. Bivariate diagrams of concentration versus isomerization indices of diamondoids are introduced to assess the maturity of oils; these diagrams provide more refined maturity assessments over a wider range of maturities than are available from single diamondoid parameters only. [Copyright &y& Elsevier]

Abstract: In this study, changes in the abundance and distribution of diamondoids in petroleum with thermal maturity were investigated by a simulation oil cracking experiment. Highly sensitive and selective gas chromatography–triple quadrupole mass spectrometry (GC–MS–MS) was employed to quantify diamondoids at ppm and sub-ppm levels. The results indicate that diamondoids were generated primarily within the maturity range 1.0–2.1% EasyRo and destroyed at high thermal maturity (>2.1% EasyRo). Hence, the occurrence of high concentrations of diamondoids probably corresponds to the maturity range from the wet gas to the early dry gas stage (i.e., 1.5–2.5% EasyRo). Good correlations were observed between a few ratios of diamondoids (i.e., EAI, DMAI-1, DMDI-1 and TMAI-1) and EasyRo. This finding indicates that these parameters may be useful maturity indices for organic matter from the late oil window to the dry gas window. [Copyright &y& Elsevier]

Abstract: In this study, a simple solvent dilution followed by highly selective and sensitive gas chromatography–triple quadrupole mass spectrometry (GC–MS–MS) detection was employed to quantify diamondoids in crude oils. Runtime parameters, i.e., parent and daughter ions, collision energy (CE) and scan time, were optimized to obtain maximum selectivity and sensitivity for target analytes. Under optimum conditions, the reproducibility and accuracy of the method were tested and found to be satisfactory. Comparison of GC–MS–MS and GC–MS methods for the determination of diamondoids indicates that GC–MS–MS yields higher sensitivity (method quantitation limits of 0.08–0.37μg/goil) and better selectivity than GC–MS (method quantitation limits of 0.78–8.44μg/goil) due to the elimination of matrix ion interferences using the selected reaction monitoring (SRM) mode. In addition, quantitative data confirm that group separation has a considerable effect on the quantification of diamondoids and the effect appears to depend on multiple factors. Two crude oils (TZ261 and TD2) from the Tarim Basin, China were used to evaluate the GC–MS–MS method. The results prove that the GC–MS–MS method is a promising tool for quantitative analysis of diamondoids in crude oils, especially for oil samples with low diamondoid concentrations. [Copyright &y& Elsevier]

Abstract: In this study, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography–isotope ratio mass spectrometry (GC–IRMS), was employed to determine compound specific carbon isotopic values (δ13C) of gasoline range hydrocarbons. The reproducibility of the method was found to be satisfactory. By comparison with the δ13C values of the twelve target compounds determined using direct injection of their n-C16 solution, no obvious isotopic fractionation was observed during the HS-SDME procedures. Some parameters that could affect the carbon isotopic fractionation, such as ionic strength of working solutions and inlet split ratio, were examined. The results also suggest that these factors had no significant effect on the carbon isotopic determination of gasoline range hydrocarbons. The application of HS-SDME to a crude oil sample proved that this method could be a promising tool for the determination of carbon isotopic values of gasoline range hydrocarbons in oils or aqueous samples. [Copyright &y& Elsevier]

Abstract: In this study, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography-flame ionization detection (GC-FID) was tested to determine C6–C12 light hydrocarbons (LHs) in petroleum and aqueous samples. Several significant experimental parameters, such as drop solvent type, drop volume, sample solution ionic strength, agitation speed and extraction time were optimized. Under optimum extraction conditions, specifically, a 1.5μl microdrop of n-hexadecane, 30min extraction of a 5ml aqueous sample placed in a 10ml vial, and stirring at 1000rpm at room temperature, the reproducibility and accuracy of this method were found to be satisfactory. Two examples using this method indicated that HS-SDME is a simple, efficient and promising technique for the determination of volatile C6–C12 LHs in complex matrices. [Copyright &y& Elsevier]

Abstract: In this study, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography-flame ionization detection (GC-FID), was employed to determine short-chain fatty acids (SCFAs) in ruthenium tetroxide (RuO4) oxidation products of asphaltenes. Several significant parameters, such as drop solvent type, drop volume, sample solution ionic strength, agitation speed, extraction time, and ratio of headspace volume to sample volume were optimized. Under optimum extraction conditions (i.e., a 3-μL drop of 1-butanol, 20min exposure to the headspace of a 6mL aqueous sample placed in a 10mL vial, stirring at 1000rpm at room temperature, and 30% (w/v) NaCl content), the reproducibility and accuracy of the method have been tested and found to be satisfactory. The analysis of a real asphaltene sample using this method proved that HS-SDME can be a promising tool for the determination of volatile SCFAs in complex matrices. [Copyright &y& Elsevier]

Recently, application-layer overlay networks have been suggested as a promising solution for live video streaming over the Internet. To organize a multicast overlay, a natural structure is a tree, which, however, is known vulnerable to end-hosts dynamics. Data-driven approaches address this problem by employing a mesh structure, which enables data exchanges among multiple neighbors, and thus, greatly improves the overlay resilience. It unfortunately suffers from an efficiency-delay trade-off, because data have to be pulled from mesh neighbors by using extra notifications periodically. In this paper, we closely examine the contributions of overlay nodes, and argue that performance of a mesh overlay closely depends on a small set of stable backbone nodes. This is validated through a real trace study on PPLive, the largest commercial application-layer live streaming system to date. Motivated by this observation, we then suggest a novel collaborative tree-mesh design that leverages both mesh and tree structures. The key idea is to identify a set of stable nodes to construct a tree-based backbone, called treebone, with most of the data being pushed over this backbone. These stable nodes, together with others, are further organized through an auxiliary mesh overlay, which facilitates the treebone to accommodate node dynamics and fully exploit the available bandwidth between overlay nodes. This hybrid design, referred to as mTreebone, brings a series of unique and critical design challenges. In particular, the identification of stable nodes and seamless data delivery using both push and pull methods. In this paper, we present optimized solutions to these problems, which reconcile the two overlays under a coherent framework with controlled overhead. We evaluate mTreebone through both simulations and PlanetLab experiments. The results demonstrate the superior efficiency and robustness of this hybrid solution in both static and dynamic scenarios. [ABSTRACT FROM AUTHOR]

Abstract: In this study, hollow fiber based liquid-phase microextraction (HF-LPME), coupled with GC, GC–MS and GC–IRMS detections, was employed to determine petroleum hydrocarbons in spilled oils. According to the results, the HF-LPME method collected more low-molecular weight components, such as C7–C11 n-alkanes, naphthalene, and phenanthrene, than those collected in conventional liquid–liquid extraction (LLE). The results also showed that this method had no remarkable effect on the distributions of high-molecular weight compounds such as >C18 n-alkanes, C1–C3 phenanthrene, and hopanes. Also, the carbon isotopic compositions of individual n-alkanes in the two preparation processes were identical. Accordingly, HF-LPME, as a simple, fast, and inexpensive sample preparation technique, could become a promising method for the identification of oil spill sources. [Copyright &y& Elsevier]

Abstract: The Bohai Bay Basin is one of the most important oil-producing provinces in China. Molecular organic geochemical characteristics of Lower Paleozoic source rocks in this area have been investigated by analyzing chemical and isotopic compositions of solvent extracts and acid-released organic matter from the Lower Paleozoic carbonate rocks in the Jiyang Sub-basin of the Bohai Bay Basin. The results indicate that enclosed organic matter in carbonate rocks has not been recognizably altered by post-depositional processes. Two end-member compositions are suggested for early organic matter trapped in the Lower Paleozoic carbonate rocks: (1) a source dominated by aquatic organisms and deposited in a relatively deep marine environment and (2) a relatively high saline, evaporative marine depositional environment. In contrast, chemical and isotopic compositions of solvent extracts from these Lower Paleozoic carbonate rocks are relatively complicated, not only inheriting original characteristics of their precursors, but also overprinted by various post-depositional alterations, such as thermal maturation, biodegradation and mixing. Therefore, the integration of both organic matter characteristics can provide more useful information on the origin of organic matter present in carbonate rocks and the environments of their deposition. [Copyright &y& Elsevier]

Abstract: Molecular and isotopic compositions of crude oils in the Beaufort–Mackenzie Basin confirm three genetic end-member oil groups and suggest extensive cross-formational hydrocarbon fluid flows in the Tertiary deltaic system. Inter- and intra-fractional variations in the geochemistry of the Tertiary-reservoired oils indicate that the oil source/maturity signatures were substantially masked by biomarkers that were picked up along migration pathways. Thus, many of the previously recognized “immature non-marine oils” are in fact thermally mature, probably derived from unpenetrated deeper marine source rocks. Although the effective source rock volumes have not been evaluated and their exact stratigraphic levels remain unknown, the relative timing of oil generation versus trap formation, rather than poor source quality, may be the cause of under-filled traps in the offshore area. [Copyright &y& Elsevier]

Abstract: In order to characterize the H isotopic compositions of individual lipid compounds from different terrestrial depositional environments, the δD values of C-bound H in individual n-alkanes from typical terrestrial source rocks of the Liaohe Basin and the Turpan Basin, China, were measured using gas chromatography–thermal conversion–isotope ratio mass spectrometry (GC–TC–IRMS). The analytical results indicate that the δD values of individual n-alkanes in the extracts of terrestrial source rocks have a large variation, ranging from −140‰ to −250‰, and are obviously lighter than the δD of marine-sourced n-alkanes. Moreover, a trend of depletion in 2H(D) was observed for individual n-alkanes from different terrestrial depositional environments, from saline lacustrine to freshwater paralic lacustrine, and to swamp. For example, the δD values of n-alkanes from a stratified saline lacustrine environment vary from −140‰ to −200‰, δD for n-alkanes from swamp facies range from −200‰ to −250‰, while those from freshwater paralic lacustrine–lacustrine environments fall between the δD values of the end members. The shift toward lighter δD from saltwater to freshwater environments indicates that the source water δD is the major controlling factor for the H isotopic composition of individual compounds. In addition, H exchange between formation water and sedimentary organic matter may possibly be important in regard to the δD of individual n-alkanes. Therefore, other lines of geochemical evidence must be considered when depositional paleoenvironments of source rocks are reconstructed based on the H isotopic composition of individual n-alkanes. [Copyright &y& Elsevier]

Abstract: The main purpose of this study is to model the δ13C values of methane derived from coal by combining kinetic-simulating experiment with the gas chromatography–isotope ratio mass spectrum (GC-IRMS) analysis. The stable carbon isotopic variation of methane in pyrolysates with heating temperature indicates that the assumptions for both a constant kinetic isotope effect (α) and a uniform initial isotopic composition (δ13Co) are impractical for explaining the carbon isotopic fractionation during coalification. For purposes of simplification, two approaches are used in this paper to deal with the heterogeneity of terrestrial organic matter. One is that, assuming a uniform initial isotopic composition (i.e., δ13Ci, o=δ13Co) for all methane-generating precursors in coal, the isotopic variation of methane is fitted by adjusting ΔEa, i (Ea13C, i−Ea12C, i) for each hypothetical reaction. The other is that, assuming a constant kinetic isotope effect during the whole gas formation, that is all ΔEa, i values are identical, the modeling of methane isotopic composition is achieved by changing the 13CH4 generation potential of each reaction (fi, 13C), namely, by adjusting the initial δ13C value (δ13Ci, o) for each methane-generating precursor. Results of the kinetic calculation shows that the two simulating methods can yield a similar result at a geological heating rate of 2 °C/My, which further demonstrates that those natural gases with methane δ13C value being approximately −36‰ are possibly sourced from the upper Triassic coal measure strata in the Northwestern Sichuan Basin. [Copyright &y& Elsevier]

The mechanism of carbon isotopic fractionation for gaseous hydrocarbons is revealed by investigating the residual liquid hydrocarbons in laboratory pyrolysates of n-octodecane. The results indicate that cracking and polymerization in the relatively low temperatures and disproportionation reactions leading to light hydrocarbons and polyaromatic hydrocarbons at high temperatures are probably causes for the carbon isotope reversal of gaseous hydrocarbons that is commonly observed in pyrolysis experiments. This study provides significant insight for quantitative modeling of natural gas Δ13C values and aid in the identification and assessment of natural gases derived from oil cracking. [ABSTRACT FROM AUTHOR]

Since the Shu103 well was successfully drilled in 1995, the Buried Hill reservoir is receiving a new exploration emphasis in the Liaohe Basin, China. The Buried Hill oils can be divided into 3 main types in the Shuguang-Huangxiling area based on their chemical and isotopic compositions. The first type is collected mostly from the Shuguang area. The similarity to the Es4 oils and the Es4 source rock extracts indicates that they were mainly expelled from the fourth member of the Shahejie formation (Es4) in the Chenjia Sag and/or Panshan Sag, deposited in a stratified paleolake system. The second is charactized by a relative high Pr/Ph ratio, low gammacerane content and depletion of 12C in individual n-alkanes. These characteristics represent a typical origin from dominantly freshwater paralic lacustrine sediments. Various biomarker indices of the other Buried Hill oils fall between the former two types. The authors infer that these oils may be derived from the adjacent Qingshui Sag and/or Panshan Sag, and were likely generated from transitional sedimentary facies between well-circulated freshwater paralic lacustrine and relatively closed saline lacustrine. [Copyright &y& Elsevier]

The carbon isotopic composition of individual light hydrocarbons generated from source rocks that had been pyrolysed in vacuum glass tube were determined by using the GC-IRMS techniques. The results indicate that abundant CO2 in the pyrolysates has a remarkable effect on the determination of CH4δ13C. Running cryogenically with an initial temperature of −40°C can effectively eliminate the effect. In addition, it conduces to measuring the δ13C of C2+ hydrocarbons by increasing the injection volume and/or absorbing CO2 with the solution of sodium hydroxide. The above measures will help to get the carbon isotopic composition of C1–C7 components, which is of great significance for gas/source rock correlation and for study on the genesis of natural gas. [ABSTRACT FROM AUTHOR]

Presents information on a study which determined the carbon isotopic compositions of individual terpenoids in the heavy oils from the Karamay oilfield in China. Experimental procedure; Results and discussion.

The accurate determination of mechanical parameters (namely, Young's modulus and hardness) of shale-constitutive minerals is crucial for predicting the macroscale mechanical parameters of shale composites. This study employed an advanced nanoindentation apparatus equipped with a high-resolution microscope (4000×) and a newly emerging nano-dynamic mechanical analysis (nano-DMA) module to conduct mineral-positioned indentation and investigate the depth profiles of mechanical parameters of shale matrix minerals, with the objective of obtaining their intrinsic mechanical values. To conduct mineral-positioned nanoindentation, various matrix minerals were pre-discerned under the optical microscope based on their particle shapes, surface features, and reflection colors. The mechanical response curves show that silicates (quartz and feldspar) exhibit significant elastic characteristics, whereas carbonates (dolomite and calcite) and clay minerals exhibit a combined deformation behavior of elasticity and plasticity based on the elastic recovery ratio and plastic work ratio. The mechanical depth profiles produced by nano-DMA show that the mechanical parameters of all aforementioned minerals decrease rapidly with respective to the increase in indentation depth, before reaching stable values. This variation pattern for the mechanical parameters is a result of the indentation size effect (ISE), which comes from the internal structure (or texture) adjustment of the indented material in small deformed volumes during indenter invasion. Whereas the platform section represents the indenter overcoming the ISE layer and actually probing the material as it is, the mechanical values measured at this stage can be recognized as the true values for the indented materials. In addition, the tested mineral grains would be easily affected by the substrate phases at a much larger indentation depth, and the mechanical parameters would correspondingly change in the mechanical depth profiles after the plateau stage. Overall, our findings identify reliable Young's moduli and hardnesses for different matrix minerals: 30 GPa and 1.5 GPa for clay minerals, 105–110 GPa and 14–16 GPa for quartz, 75–85 GPa and 9–10 GPa for feldspar, 70–75 GPa and 2–3 GPa for calcite, and 115–120 GPa and 7–8 GPa for dolomite. • Conducted mineral-positioned nanoindentation in shale. • Depicted the deformation behavior of shale matrix minerals. • Gave the mechanical depth profiles using dynamic nanoindentation. • Revealed the indentation size effect and substrate effect of shale matrix minerals. [ABSTRACT FROM AUTHOR]

The overmature marine Ordovician–Silurian Wufeng–Longmaxi (WF–LMX) formation shale is the most important exploration target for shale gas in South China. In this study, WF–LMX shale samples from Well XY-1 in the Northwestern Guizhou Province (NGP) were selected to comprehensively investigate organic matter (OM) assemblages and OM-hosted nanopores. Petrographic observations under an optical microscope and a scanning electron microscope (SEM) revealed that the OM in the WF–LMX shale is predominately solid bitumen (pyrobitumen), followed by organic zooclasts (predominantly as graptolites), with a minor amount of micrinites (as the heavier conversion products of the oil-prone kerogen macerals). Additionally, the degraded alginites were traced by their bright halo feature in reflected light and blurred fluorescence in blue light when enhancing the exposure intensity, which demonstrates that the previously deposited alginites in the WF–LMX shale were basically converted to hydrocarbons. SEM imaging revealed that the secondary OM pores associated with hydrocarbon generation are pervasive in pyrobitumen, while undeveloped in organic zooclasts and micrinites. Conversely, the good linear relationship between TOC contents and methane absorbed amounts indicates that there must be numerous SEM-invisible pores existed in both the solid bitumen and organic zooclasts in addition to the secondary pores. Aiming to certify and quantify the SEM-invisible pores, the OM were separated from the WF-LMX shale and then were subjected to a series physical and chemical measurements. The combined N 2 and CO 2 adsorption on the OM isolates of the WF–LMX shale further revealed two pore concentration sections, i.e., pores of 0.33–0.5 nm and 1.2–2.0 nm within the micropore regime, which contributed approximately 82% and 18% to the total surface area and pore volume of the OM, respectively. X-ray diffraction testing further correlated the micropores to the spacing of aromatic rings and macromolecular structural units that constitute the OM. As such, it is the micropores related to the chemical structure of the OM that essentially determine the sorptive capacity of OM and also the WF–LMX bulk shale, whereas the main contribution of SEM-visible OM pores is affording the effective porosity for gas storage. Overall, the clarification of OM assemblages, carriers of secondary OM pores, and existence and origin of OM micropores in the WF–LMX shale provide a further understanding of the generation and occurrence of shale gas in South China. • WF-LM shale is predominately solid bitumen, rather than primary kerogen macerals. • Degraded alginites were traced by enhancing the optical exposure intensity. • Secondary OM pores are limited in solid bitumen, whereas undeveloped in graptolite. • N 2 -CO 2 adsorption on the isolated OM revealed numerous micropores within OM. • X-ray diffraction correlated the micropores to the chemical structure of OM. [ABSTRACT FROM AUTHOR]

Creep behavior of rocks could impair fracture conductivity and wellbore stability during gas production from highly matured organic-rich shales in South China, of which the organic matter is mainly in the form as solid bitumen and is thought to be a major contributor for the creep deformation. To get a better insight into this phenomenon, this paper for the first time characterizes the mechanical properties and creep behavior of a millimeter-sized solid bitumen sample by using quasi-static state creep tests and Dynamic Mechanical Analysis in nanoindentation, and reports their dependences on indentation size and loading rate, respectively. Mechanical properties (including hardness and Young's modulus) are found to be negatively related with both indentation size and loading rate. The extremely small creep strain rate sensitivity (m) of solid bitumen indicates a localized shear flow inside. And m exhibits slightly positive dependences on indentation size and loading rate. The potential mechanisms controlling the deformation of solid bitumen under indentation are also discussed. • Creep behavior and mechanical properties of solid bitumen are studied with nanoindentation. • The hardness is recorded to decrease with increasing indentation depth and loading rate. • The Creep strain rate sensitivity shows a weak dependence on indentation depth and loading rate. [ABSTRACT FROM AUTHOR]

Highlights • Different diamondoid indices are available for certain thermal maturity stages. • Oil maturities can be broadly constrained by diamondoid concentrations. • Some diamondoid concentration ratios can differentiate the sources of oils. • Diamondoid concentration ratios can be used to assess the maturity of normal oils. • Diamondoid isomerization ratios are effective for maturity evaluation of condensates. Abstract Here we discuss three types of diamondoid parameters for oils from the Junggar Basin. These are: absolute concentrations, concentration ratios, and isomerization ratios. According to the absolute diamondoid concentrations, the oils collected from different areas of the basin were broadly divided into three maturity stages: (1) low-mature (<100 ppm adamantanes; <5 ppm diamantanes); (2) mature (100–1000 ppm adamantanes; 5–50 ppm diamantanes); and (3) highly mature (>1000 ppm adamantanes; >50 ppm diamantanes). The oils in the northwestern region of the Junggar Basin are in the low-mature to mature stages. Based on a combination of diamondoid concentration ratios and biomarker indices, these oils can be divided into three groups, i.e., Group I oils in the Wuxia Zone derived from the lower Permian Fengcheng Formation (P 1f), Group II oils in the Kebai Zone sourced from middle Permian Lower Wuerhe Formation (P 2w), and Group III oils in the Mahu Depression generated from more mature source rocks of Jiamuhe Formation (P 1j) or the P 1f. Diamondoid concentrations and isomerization ratios were used to precisely evaluate the thermal maturity of mature oils and highly mature condensates, respectively. Our results indicate that the oils in the central part of the basin have decreasing thermal maturity from south to north, whereas the oils in the Kelameili area display increasing thermal maturity from east to west. In this study we found that different diamondoid indices are useful only in certain thermal maturity ranges. Therefore, at least for the Junggar Basin, it is crucial to know which thermal region one is in before using diamondoid ratios for maturity assessment. [ABSTRACT FROM AUTHOR]

Black carbon was produced by slow pyrolysis under an oxygen-limited condition at 500 °C, and was modified by some chemical methods (oxidation, hydrolysis, activation, and surface recombination). The modified samples were characterized by using elemental analysis, Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) surface analysis, Boehm titration, cation exchange capacity(CEC)analysis, CO 2 adsorption analysis, and then used to investigate the sorption behavior of phenanthrene. The results showed that the activation of ZnCl 2 gave a maximum nanopore volume of 96.5 μL/g and a specific surface area of 241 m 2 /g, while the oxidation of NaClO gave a minimum nanopore volume of 63.3 μL/g and a specific surface area of 158 m 2 /g. The FTIR, XPS, and Boehm titration analysis showed that the new oxygen-containing functional groups were introduced during the oxidation treatments of H 2 O 2 and NaClO. The sorption of phenanthrene on all samples was typically nonlinear, and the nonlinear factor ( n ) was negatively correlated with V o , especially with V o at 0–1.1 nm. The sorption parameter (log K OC ) was positively correlated with nanopore volume ( V o ) and specific surface area (SSA). Moreover, the model analysis showed that the nanopore filling was the main sorption mechanism, and molecular sieve effect was observed in the sorption of phenanthrene. [ABSTRACT FROM AUTHOR]

To effectively treat the pollutant in sewage, a new-type three-dimensional aerogel based on graphene oxide and waste paper was fabricated via simple mixing and freeze-drying processes. Therein, waste paper was activated in advance, and polyvinyl alcohol served as physical crosslinking agent. The results showed that the obtained aerogel with porous three-dimensional network structure exhibited good thermal stability. When it acted as adsorbent for treating organic dye (methylene blue) and antibiotic (ciprofloxacin), the adsorption process was explored. In single system, the pseudo-first-order and pseudo-second-order kinetic models were used to discuss the detail about the aerogel adsorbing pollutant. Moreover, the Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and calculate the isotherm constants. Thermodynamic results stated that the adsorption of pollutant onto aerogel was feasible and spontaneous. In binary system, the adsorption capacity of methylene blue by aerogel increased, while the adsorption capacity of ciprofloxacin by aerogel declined. The pseudo-second-order kinetics was consistent with the adsorption of pollutant by aerogel in such binary system. This study would provide a new boulevard to develop environmental, low-cost and high-efficiency adsorbent for removing pollutant from wastewater. [ABSTRACT FROM AUTHOR]

On-line gas chromatography–pyrolysis coupled to gas chromatography–isotope ratio mass spectrometry was used here for the position-specific isotope analysis (PSIA) of propane. First, based on the conversion rate of propane and its products, 800–840 °C was considered optimal for propane pyrolysis. The major pyrolytic fragments of propane included CH 4 , C 2 H 4 , C 3 H 6 , and C 2 H 6 . Subsequent isotope labeling experiments showed that CH 4 and C 2 H 6 were derived entirely from the terminal carbons, whereas C 2 H 4 and C 3 H 6 were derived from both terminal and central positions of propane. Therefore, the 13 C enrichment factor associated with the major reactions during the pyrolysis process and position-specific δ 13 C values of propane can be estimated from the amount and δ 13 C values of the pyrolytic fragments using isotope mass balance. The obtained enrichment factors depended on the pyrolysis temperature, which can be used to calculate position-specific δ 13 C values for propane measured with this system. The results suggest that a relatively accurate site-preference value for propane can be obtained by this method. Therefore, the combination of compound-specific isotope analysis and PSIA of propane will be a powerful tool to discriminate the different origins of gases. [ABSTRACT FROM AUTHOR]

A series of anhydrous pyrolysis experiments, using sealed gold tubes, were performed on three types of kerogen to investigate the effect organic matter type has on the generation and evolution of thermogenic diamondoids. Based on the compositional variation of pyrolysis products, the cracking of kerogens can be divided into three stages: oil generation (0.6%–1.5% EasyRo), wet-gas generation (1.5%–2.1% EasyRo) and dry-gas generation (>2.1% EasyRo). The experimental results indicate that diamondoids were mainly generated in the oil and wet-gas generation stages and decomposed in the dry-gas generation stage. In addition to thermal maturity, the formation of diamondoids is also influenced by the type of organic matter. Type I and II A kerogens produced more diamondoids than Type III kerogen, and diamondoids generated from Type III kerogen were dominantly adamantanes. Therefore, the concentration and concentration ratios of diamondoids can be used to assess the maturity of source rocks (1.0%–1.5% EasyRo) and determine the type of organic matter (1.0%–2.0% EasyRo). Isomerization ratios of diamondoids depend mainly on thermal maturity and the type of organic matter has little effect. The use of isomerization ratios to determine thermal maturity is best for source rocks at higher maturity levels (1.5%–3.0% EasyRo). Therefore, bivariate diagrams of concentration versus isomerization indices of diamondoids (e.g., DMAs/MDs vs. DMAI-1 and DMAs/MDs vs. TMAI-1) can be used to evaluate the source rock maturity over a wider EasyRo range (1.0%–3.0% EasyRo) than single diamondoid parameters. As there are differences in the concentration and distribution of diamondoids in the extracts of three source rocks, the possibility exists to use diamondoid indices of immature rocks to determine the type of source rock. [ABSTRACT FROM AUTHOR]

[Display omitted] Liquid organic electrolytes commonly employed in commercial Li-ion batteries suffer from safety issues such as flammability and explosions. Replacing liquid electrolytes with nonflammable electrolytes has become increasingly attractive in the development of safe, high-energy Li-metal batteries (LMBs). In this work, nonflammable, robust, and flexible composite polymer–polymer electrolytes (PPEs) were successfully fabricated by flame-retardant solution casting with polyimide (PI) and polyvinylidene fluoride (PVDF). The optimized nonflammable PPEs (e.g., PPE-50) demonstrate not only good mechanical properties (i.e., a high tensile strength of 29.6 MPa with an elongation at break of 87.2%), but also high Li salts dissolubility, the former of which ensures the suppression of Li dendrites, while the latter further improves the ionic conductivity (∼1.86 × 10−4 S cm−1 at 30 °C). The resulting symmetric cells (Li|PPE-50|Li) offer excellent Li stripping and plating stability for 1000 h at 0.5 mA cm−2/0.25 mAh cm−2 and 600 h at 2.0 mA cm−2/1.0 mAh cm−2. In addition, the LiFePO 4 |PPE-50|Li half cells show high cycling performance (e.g., a reversible discharge capacity of 135.9 mAh g−1 after 300 cycles at 1C) and rate capability (e.g., 117.2 mAh g−1 at 4C). The PPE-50 is also compatible with a high-voltage cathode (e.g., LiNi 0.5 Mn 0.3 Co 0.2 O 2), and the resulting batteries demonstrate long-term cycling stability with a high cut-off voltage of 4.5 V vs. Li/Li+. Because of the incorporation of a mechanically robust and thermally stable PI, a polar PVDF, and flame-retardant trimethyl phosphate (TMP) within PPEs, as well as the coordination between Li salts and TMP, and the interaction between Li salts and polymers (especially between Li bis(oxalato)borate) and PI, as well as the bis(oxalato)borate anion and PI), PPEs show great potential for practical and high-energy LMBs without safety concerns. [ABSTRACT FROM AUTHOR]

Low-pressure gas adsorption is widely used for pore size analysis of porous materials, and has been employed to characterize pore systems in shale. However, the complexity of shale pore structures means that different methods and models may lead to distinct interprets for adsorption data. Non-local-density functional theory (NLDFT) analysis based on N 2 and CO 2 composited adsorption isotherms is used here to investigate the pore structure of nanopores in marine organic-rich shale and compare with the results from some conventional methods in this paper. The results indicate that (1) The N 2 adsorption isotherms of organic-rich shale are a composite of Types I(b), II, and IV(a), according to the IUPAC (2015) classification of physisorption isotherms. The hysteresis loops show similar shapes to Type H2(a). Delayed capillary condensation is observed in the adsorption isotherms, and the desorption step is shifted to the lower relative pressure of ∼0.45 characteristic of the cavitation mechanism, indicating ink-bottle pores with narrow necks. The CO 2 adsorption isotherms are similar to Type I(b), but appear to increase without limit when p / p 0 = 0.03 because of the occurrence of meso- and macropores in the shales. (2) NLDFT method based on N 2 and CO 2 composited adsorption isotherms is the most suitable and accurate method for using gas physisorption when considering the entire size distribution of nanopores, which allows a suitable range of critical pore sizes (∼0.33–100 nm) to be explored. [ABSTRACT FROM AUTHOR]

Heart failure (HF) is one of the major causes of death among diabetic patients. Although studies have shown that curcumin analog C66 can remarkably relieve diabetes-associated cardiovascular and kidney complications, the role of SJ-12, SJ-12, a novel curcumin analog, in diabetic cardiomyopathy and its molecular targets are unknown. 7-week-old male C57BL/6 mice were intraperitoneally injected with single streptozotocin (STZ) (160 mg/kg) to develop diabetic cardiomyopathy (DCM). The diabetic mice were then treated with SJ-12 via gavage for two months. Body weight, fast blood glucose, cardiac utrasonography, myocardial injury markers, pathological morphology of the heart, hypertrophic and fibrotic markers were assessed. The potential target of SJ-12 was evaluated via RNA-sequencing analysis. The O-GlcNAcylation levels of SP1 were detected via immunoprecipitation. SJ-12 effectively suppressed myocardial hypertrophy and fibrosis, thereby preventing heart dysfunction in mice with STZ-induced heart failure. RNA-sequencing analysis revealed that SJ-12 exerted its therapeutic effects through the modulation of the calcium signaling pathway. Furthermore, SJ-12 reduced the O-GlcNAcylation levels of SP1 by inhibiting O-linked N -acetylglucosamine transferase (OGT). Also, SJ-12 stabilized Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase 2a (SERCA2a), a crucial regulator of calcium homeostasis, thus reducing hypertrophy and fibrosis in mouse hearts and cultured cardiomyocytes. However, the anti-fibrotic effects of SJ-12 were not detected in SERCA2a or OGT-silenced cardiomyocytes, indicating that SJ-12 can prevent DCM by targeting OGT-dependent O-GlcNAcylation of SP1.These findings indicate that SJ-12 can exert cardioprotective effects in STZ-induced mice by reducing the O-GlcNAcylation levels of SP1, thus stabilizing SERCA2a and reducing myocardial fibrosis and hypertrophy. Therefore, SJ-12 can be used for the treatment of diabetic cardiomyopathy. [Display omitted] • Compound SJ-12 alleviates cardiac dysfunction, hypertrophy, and fibrosis in DCM. • SJ-12 increases the level of SERCA2a, a crucial regulator of calcium homeostasis, thus playing a protective role in DCM. • Mechanistically, the cardiac protection effect of SJ-12 was targeting OGT-regulated O-GlcNAc-Sp1/SERCA2a axis. [ABSTRACT FROM AUTHOR]

• Reversal of δ13C and anomalous positive SP value reveals CH 4 polymerization. • Three evolution stages were identified for thermogenic gases. • A remarkable feature of stage III is surface-catalyzed abiotic CH 4 polymerization. • Contribution of CH 4 polymerization can be determined by a two-end member model. • High methane, high temperature, abundant catalyst are good to CH 4 polymerization. The formation and evolution of thermogenic gases were investigated using a combination of intermolecular and intramolecular isotope analyses of 32 natural gas samples collected from the Sichuan and Tarim basins (China) and the Arkoma Basin (USA). Three evolution stages (I–III) were identified: In stage I, hydrocarbon gases are produced through thermal decomposition of organic matter, and kinetic isotope effects in C–C bond breakage control their isotopic distributions; In stage II, C 2 –C 5 hydrocarbons crack with increasing thermal maturity, with their formation and decomposition tending toward thermodynamic equilibrium, and at the end of this stage, the intermolecular and intramolecular isotopic compositions of gaseous hydrocarbons are in thermodynamic equilibrium; A remarkable feature of stage III is the surface-catalyzed abiotic polymerization of methane, which provides a critical origin of C 2+ hydrocarbons in this stages and leads to isotopic anomalies in C 2+ hydrocarbons, including the reversal of δ13C distributions of C 1 –C 3 and the reverse evolution trend of SP value of propane (i.e., tending to be positive). The contribution of C 2+ hydrocarbons from the abiotic polymerization of methane can be determined based on a two-end member model. C 2+ hydrocarbons in the Changning shale gases are all generated from abiotic methane polymerization, and the contribution ratio in the Weiyuan shale gases is about 85 %, while, the contribution of C 2+ hydrocarbons in dry gases from the Tarim Basin formed by this way is no more than 55 %. High methane abundance, high temperature, and abundant catalyst are beneficial to abiotic methane polymerization. [ABSTRACT FROM AUTHOR]

The lower Cambrian Niutitang/Qiongzhusi shale gas in the Middle-Upper Yangtz Block had been regarded as a very promising unconventional natural gas resource due to its high total organic carbon, great thickness, and large areal distribution. However, no commercial shale gas fields have yet been reported. From the northwest to the southeast there are considerable differences in the sedimentary environments, lithology, and erosive nature of the underlying interval (the floor interval) of the Niutitang shale. However, systematic research on whether and how these regional differences influence shale petrophysical properties and shale gas preservation in the Niutitang shale is lacking. A comparison of Niutitang shale reservoirs as influenced by different sedimentary and tectonic backgrounds is necessary. Samples were selected from both the overmature Niutitang shales and the floor interval. These samples cover the late Ediacaran and early Cambrian, with sedimentary environments varying from carbonate platform and carbonate platform marginal zone facies to continental shelf/slope. Previously published data on the lower Cambrian samples from Kaiyang (carbonate platform), Youyang (carbonate platform marginal zone) and Cen'gong (continental shelf/slope) sections were integrated and compared. The results indicate that the petrophysical properties of the floor interval can affect not only the preservation conditions (sealing capacity) of the shale gas, but also the petrophysical properties (pore volume, porosity, specific surface area and permeability) and methane content of the Niutitang shale. From the carbonate platform face to the continental shelf/slope the sealing capacity of the floor interval gradually improves because the latter gradually passes from high permeability dolostone (the Dengying Formation) to low permeability dense chert (the Liuchapo Formation). In addition, in contrast with several unconformities that occur in the carbonate platform face in the northern Guizhou depression, no unconformity contact occurs between the Niutitang shale and the floor interval on the continental shelf/slope developed in eastern Chongqing Province and northwestern Hunan Province. Such regional differences in floor interval could lead to significant differences in hydrocarbon expulsion behaviour and the development of organic pores within the Niutitang shale. Therefore, shale gas prospects in the Niutitang shales deposited on the continental shelf/slope should be significantly better than those of shales deposited on the carbonate platform face. [ABSTRACT FROM AUTHOR]

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), likely produced by bacteria in soil and peat, are widely distributed, easily detected, newly adopted biomarker compounds. In this study, brGDGTs were used to explore the relationship between the absolute abundance of brGDGTs and the distribution of oil and gas fields in the Duoshiqiao area of the Jiyang depression. The results showed that the concentrations at the Xiakou fault and in the oil and gas fields were obviously higher than those in the contrast areas. The clear relationship among the concentration of brGDGTs, the distribution of oil and gas fields, and the acidolysis hydrocarbon (ethane) indicates that the concentration effectively responds to hydrocarbon seeps from the oil and gas field below. brGDGTs may become some of the most important indicators in surface geochemical prospecting for oil and gas. [ABSTRACT FROM AUTHOR]

The viscoelastic behavior of minerals in shales is important in predicting the macroscale creep behavior of heterogeneous bulk shale. In this study, in situ indentation measurements of two major constitutive minerals (i.e., quartz and clay) in Longmaxi Formation shale from the Sichuan Basin, South China, were conducted using a nanoindentation technique and high-resolution optical microscope. Firstly, quartz and clay minerals were identified under an optical microscope based on their morphology, surface features, reflection characteristics, particle shapes, and indentation responses. Three viscoelastic models (i.e., three-element Voigt, Burger's, and two-dashpot Kelvin models) were then used to fit the creep data for both minerals. Finally, the effects of peak load on the viscoelastic behavior of quartz and clay minerals were investigated. Our results show that the sizes of the residual imprints on clay minerals were larger than that of quartz for a specific peak load. Moreover, the initial creep rates and depths in clay minerals were higher than those in quartz. However, the creep rates of quartz and clay minerals displayed similar trends, which were independent of peak load. In addition, all three viscoelastic models produced good fits to the experimental data. However, due to the poor fit in the initial holding stage of the three-element Voigt model and instability of the two-dashpot Kelvin model, Burger's model is best in obtaining the regression parameters. The regression results indicate that the viscoelastic parameters obtained by these models are associated with peak load, and that a relatively small peak load is more reliable for the determination of viscoelastic parameters. Furthermore, the regression values for the viscoelastic parameters of clay minerals were lower than those of quartz and the bulk shale, suggesting the former facilitates the viscoelastic deformation of shale. Our study provides a better understanding of the nanoscale viscoelastic properties of shale, which can be used to predict the time-dependent deformation of shale. [ABSTRACT FROM AUTHOR]

Abstract: The distribution and compound-specific carbon isotope ratios of n-alkanes and fatty acids in a sediment core (63cm) collected from Lake Dianchi were examined to investigate organic matter sources in the eutrophic lake. Fatty acids included free and bound fatty acids. The carbon isotope compositions of individual n-alkanes and fatty acids from Lake Dianchi sediments were determined using gas chromatography/isotope ratio mass spectrometry (GC–IRMS). The δ13C values of individual n-alkanes (C16–C31) varied between −24.1‰ and −35.6‰, suggesting a dominance of 13C-depleted n-alkanes that originated from C3 plants and lacustrine algae. Fatty acids from the sediment extracts were analyzed for their abundances and carbon isotopic compositions. Molecular and isotopic evidence indicates that most of the short-chain fatty acids from Lake Dianchi sediment extracts are sourced from intense microbial recycling and resynthesis of organic matter. Long-chain free fatty acids are mainly derived from terrestrial sources. However, long-chain bound fatty acids are sourced from a combination of terrestrial organic matter, bacteria and algae, with the contribution from algal sources higher in the hypereutrophic stage. [Copyright &y& Elsevier]

Highlights: [•] An improved sample pre-treatment method for the analysis of SCFAs in RICO products. [•] Combine the HS-SDME with derivatization method for quantitative analysis of SCFAs in complex matrices. [•] This method allows detection of the studied analytes at low concentrations in aqueous phases. [ABSTRACT FROM AUTHOR]

• Intramolecular isotopes of 40 propane and 5 methane samples were analyzed. • Different intramolecular C isotopes of propane from coal and coal mudstone. • Extreme 13C depletion in central C of over mature propane at cooling setting. • Different effect on intramolecular isotopes by various post-generation processes. Evaluating the origin and fate of hydrocarbons holds significance in many fields, such as energy, geology, astrobiology, biosphere, and environment. However, challenges arise in many cases owing to the limitations of conventional methods. Intramolecular isotope analysis of propane is a new technique that offers the potential to provide insights into gas formation mechanisms; however, a comprehensive understanding of the method remains limited. Specifically, there is little knowledge about its ability to distinguish gases generated by source rocks deposited in similar sedimentary environments such as coal and coaly mudstone. Therefore, this study was undertaken to investigate position-specific carbon isotopes of 40 propane samples from 15 coal-type gas accumulations across four basins in China (Sichuan, Ordos, Qaidam, and Songliao); additionally, clumped isotopologues of methane samples were also analyzed. These coal systems cover a wide range of thermal maturity (from marginally mature to over-mature) at various age strata from the Permian, Triassic, and Jurassic periods, to the Cretaceous period. Our results revealed that propane generated from coal and coaly mudstone differed greatly in intramolecular isotope compositions despite having similar bulk δ13C 3 values. Propane generated from coaly mudstone at a wide range of maturity had relatively more stable δ13C values in both the central (δ13C cental) and terminal carbons (δ13C terminal), near the theory generation line of chain-alkane cracking in the plot of δ13C terminal vs. δ13C cental. However, propane generated from coal had higher stable δ13C terminal values and lower δ13C central values that progressively increased with maturity. Under cooling-down conditions, propane from over-mature natural gases became extremely 13C-depleted in both the terminal and central positions, with Δ13C central (δ13C central minus δ13C terminal) values being as low as –10‰, suggesting a partial origin of methane polymerization. Two propane samples from Cretaceous brown sandstone in the Songliao Basin exhibited an increase in both central and terminal carbons, suggesting that they may have surpassed chemical oxidation owing to high-valence Fe(Mn) oxides. These results indicate that intramolecular isotopes of propane can effectively differentiate dominant gas sources in a coal system with coal or coaly mudstone, as well as easily identify isotopic fractionation caused by post-generation processes, such as methane polymerization, mixing and chemical oxidation. [ABSTRACT FROM AUTHOR]

• n -C 18 and squalane yield simple precursors for modeling gas generation. • Two isotopic fractionation patterns are observed in n - and iso -propyl generative models. • Free radical reactions are the main pathway during the main stage of propane generation. Investigating the mechanisms that determine the bulk and position-specific carbon isotopic distributions of propane in natural gas will help elucidate its formation and evolution. We used octadecane and squalane as model compounds that give simple precursors for gas production in gold-tube isothermal pyrolysis experiments to study the variations in intermolecular and intramolecular distributions of isotopes in the generated gaseous hydrocarbons. The δ13C values of the products and inverses of their carbon numbers (1/ n where n = C 1 –C 5) showed a negative linear relationship versus maturity, indicating that they formed by homolytic cleavage of C–C bonds and that the precursors showed homogeneous distributions of carbon isotopes. However, the significant difference in the kinetic isotopic effects (KIEs) of the gas generated by cracking of two model compounds under the same experimental conditions is not readily explained by single homolytic bond cleavage. The results indicate that besides the KIE of C–C bond cleavage, the bulk and position-specific carbon isotopic compositions of propane are related to the chemical and isotopic structures of the precursors and the propane transformation ratio. Based on the sites of C–C bond cleavage, two isotopic fractionation patterns (i.e., normal propyl and isopropyl models) may explain the bulk and position-specific carbon isotopic distributions of the generated propane. According to the propyl model, propane originates from (normal) propyl structures (CH 3 CH 2 CH 2 *) in the precursor via C–C bond cleavage at a terminal site of a propyl group, while the isopropyl model involves propane derived from isopropyl structures (CH 3 CH*CH 3) in the precursor, with C–C bond cleavage at the central site. Simulations show that these distributions for propane cracked from octadecane closely follow the propyl model, whereas propane generated from squalane showed mixed contributions from both models, and its bulk and position-specific carbon isotopic distributions depend on the proportions of propyl and isopropyl structures in the precursors. Variations of propane's position-specific carbon isotopic distributions during the main stage of propane generation indicate that free radical reactions are the main pathway for thermogenic propane formation, resulting in similar KIEs for propane terminal and central carbons. Therefore, the position-specific carbon isotopic distribution of propane can provide evidence of its formation mechanism and shows potential for revealing the origin and evolution of natural gas. [ABSTRACT FROM AUTHOR]

Clumped-isotope analysis provides new constraints on the formation and evolution of methane. High-resolution isotope-ratio mass spectrometry (HR-IRMS) is a sensitive, precise, and stable analytical technique increasingly used in methane clumped-isotope analysis. However, the lack of standard reference frames hinders the comparison of data from different laboratories and the evaluation of accuracy. In this study, an absolute reference frame was introduced for HR-IRMS analysis of the multiply substituted methane isotopologues 13CH 3 D and 12CH 2 D 2. We evaluated the optimized performance of a Panorama (Nu Instruments, UK) HR-IRMS system by repeated analysis of an intra-laboratory standard gas, finding that these rare isotopologues can be analyzed separately with high precision, repeatability, and reproducibility. Internal precision (a key parameter in instrument performance) reached 0.15‰ − 0.25‰ for Δ13CH 3 D and 0.70‰ − 0.85‰ for Δ12CH 2 D 2 values, ensuring the reliability of data. Comparison of results before and after purification demonstrated that purification procedures caused negligible isotopic fractionation of clumped isotopes. Isotopic-exchange experiments revealed source effects in the MS ion source, depending on the difference in bulk H isotopic composition between sample and reference gas, but independent of bulk C isotopic composition. To improve analytical accuracy for methane isotopologues, an absolute reference frame was developed through experiments involving a suite of mixed gases of different H isotopic composition equilibrated at 100 °C and a standard gas equilibrated at 2 °C–500 °C. Based on the reference frame, raw data were processed with a non-linearity correction and converted to real values with empirical transformation functions. The reference frame was applied to analyses of two methane standard gases and three natural gases from Tarim Basin, China. Measured Δ13CH 3 D and Δ12CH 2 D 2 values for two standard gases were consistent with published values. Clumped-isotope signatures of natural gases preserve information related to the formation temperature of methane. • Clumped-isotope analysis provides new constraints on the formation and evolution of methane. • Isotopic-exchange experiments demonstrated the presence of source scrambling in Panorama. • An absolute reference frame was established to calibrate source scrambling to achieve the accurate clumped-isotope value. • We measured CH 4 clumped-isotope of natural gases and proved that the absolute reference frame is accurate and feasible. [ABSTRACT FROM AUTHOR]