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A suite of oils from the Bongor Basin, South Western Chad was characterized geochemically to investigate the behavior of carbazoles and benzocarbazoles during biodegradation. The oils show similar maturity levels and organic facies type with biodegradation as the primary control on molecular compositions. According to compositional variation, the biodegradation levels of oils fell within PM level 0–8 [PM biodegradation scale (Peters, K.E., Moldowan, J.M., 1993)]. Absolute concentrations of carbazole, methylcarbazoles, C 2 -carbazoles, and benzocarbazoles in the oils show an increase from PM level 1–3, fluctuation at PM level 4–7, and sharp decrease above PM level 7. Relative abundances of the carbazole series indicate that C 0 –C 2 -carbazoles are more susceptible to biodegradation than benzocarbazoles, 2- and 3-methylcarbazoles are more susceptible than 1- and 4-methylcarbazoles, partially shielded dimethylcarbazoles are more susceptible than the exposed ones and both of these are more susceptible than shielded dimethylcarbazoles. Benzo[c]carbazole seems to show a higher ability to resist biodegradation than benzo[a]carbazole in heavily biodegraded oils. Therefore, ratios of 1-/(2-+3-) methylcarbazole, 4-/(2-+3-) methylcarbazole, 1,8-dimethylcarbazole/total dimethylcarbazoles, 1,8-/1,3-dimethylcarbazole, and 1,8-/2,4-dimethylcarbazole may be used to assess the degree of biodegradation in this area. [ABSTRACT FROM AUTHOR]

Abstract: SnO2 nanorod bundles were synthesized by hydrothermal method. Field-emission scanning electron microscopy and transmission electron microscopy images showed that the as-prepared flowerlike SnO2 nanorod bundles consist of tetragonal nanorods with size readily tunable. Their electrochemical properties and application as anode for lithium-ion battery were evaluated by galvanostatic discharge–charge testing and cycle voltammetry. SnO2 nanorod flowers possess improved discharge capacity of 694mAhg−1 up to 40th cycle at 0.1C. [Copyright &y& Elsevier]

Abstract: Porous SnO2 nanospheres have been successfully fabricated through hydrothermal synthesis followed by annealing. Precursor nanospheres were synthesized by reaction of SnCl2·2H2O and C2H2O4·2H2O and SnO2 nanospheres were obtained through annealing of precursor. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) respectively. The results indicated that these SnO2 nanospheres of 300nm in diameters are composed of numerous nanoparticles around 20–35nm. Their electrochemical properties and application as anode for lithium-ion battery were evaluated by galvanostatic discharge–charge testing and cycling voltammetry. Porous SnO2 nanospheres exhibited improved discharge capacity of 522mAhg−1 up to 30th cycle at of 0.1C. Tentative cause of such an improvement in electrochemical performance has been proposed. [Copyright &y& Elsevier]

Geological structure has become a hot research topic in gas-hydrate exploration. Until now, gas hydrate has not been found in the Mohe permafrost. Lack of information about geological structures that are closely related to the potential gas-hydrate accumulation in the permafrost, seems to be one of the limitations to the gas-hydrate exploration. In this paper, imaging logging and isotope dating are adopted to indicate that geological structures, associated with the potential gas-hydrate accumulations, including faults, fractures, and anticlines, are highly developed in the permafrost. The north-dipping normal faults and the unfilled fractures below 700 m, are considered as structure passages for the migration of hydrocarbon gas in the permafrost, while reverse faults, unfilled fractures, and anticlines of approximately 100–700 m provide the majority of reservoir spaces for the potential gas-hydrate accumulation. The area is surrounded by Luoguhe Village, Laoyeling Hill, Beihong Village, Shuangjianshan Hill, and Ershibazhan Forest Farm and is conducive for the accumulation of the potential gas-hydrate in the Mohe permafrost, because it contains the most developed permafrost and a large number of wide-space anticlines and faults. Furthermore, the depths of 300–700 m, where the unfilled high-angle fractures have been developed, are identified as the most favourable interval for the potential gas-hydrate occurrence. Therefore, it is concluded that the reverse faults, unfilled fractures, and the anticlines at the depth of 300–700 m in this area can be considered as the primary drilling objects for the gas-hydrate exploration. The importance of this study is to minimise the cost of gas-hydrate exploration drilling in the Mohe permafrost. These findings can also be used for future gas-hydrate exploration projects in similar permafrost zones. • The geological structures associated with potential gas-hydrate accumulation are highly developed in the Mohe permafrost. • The reactivations of the structures in the Cenozoic are conducive to potential gas-hydrate accumulation in the Permafrost. • The normal and reverse faults and the unfilled crevices could be passages for gas migration during the gas-hydrate formation. • The reverse faults, unfilled crevices and anticlines provided the reservoir spaces for potential gas-hydrate accumulation. • The anticlines and north-dipping faults determine the regional distributions of potential hydrate, while the reverse faults and unfilled high-angle crevices restrict its occurrence. [ABSTRACT FROM AUTHOR]

The occurrence and enrichment of shale plays are highly controlled by pore characteristics of the formation. In this study, an immature sample rich in kerogen type III from the Damoguaihe formation, Hailar Basin in China is subjected to hydrous and anhydrous pyrolysis (HP and AHP) across an extensive temperature range (300–450 °C). Next, low-pressure N 2 adsorption analysis was conducted on the pyrolyzate of each maturity stage to study the pore structures' evolution during thermal maturity simulation. Moreover, deconvolution and fractal dimension analyses were implemented to study pore families and the complexity of pores within the shale samples. Finally, radial basis function (RBF) neural networks optimized by four evolutionary approaches were applied for modeling N 2 adsorption data obtained from the HP and AHP samples. According to the results, the original shale sample and all pyrolyzates obtained with HP and AHP scenarios exhibited type IV isotherm with H3 hysteresis loops. As a whole, BET surface area, micro-, meso- and total pore volume of HP pyrolyzates were higher than AHP ones. The unheated shale sample had seven families containing three mesopore and four macropore groups. Although all pyrolyzates obtained from the pyrolysis had families with similar means, their pore volumes were entirely different, which proves that the pore structure of samples undergoes changes during thermal maturation and the presence of water can also enforce these changes. Both fractal dimensions showed a direct relationship with BET surface area and a negative correlation with the average pore diameter of shale samples. The RBF model optimized by differential evolution (DE) delivered a mean absolute percent relative error (MAPRE) value of 4.84% and determination coefficient (R2) of 0.9946 for the total data set, which outperforms other RBF models in predicting N 2 adsorption/desorption tests of pyrolyzates. The outcome of sensitivity analysis suggested that the N 2 adsorption/desorption behavior of the pyrolyzates was mostly affected by relative pressure and the pyrolysis type (HP or AHP). Ultimately, the results clearly revealed that the effect of water on the pores' alteration of shales with type III kerogen is greater than the effect of temperature or thermal maturity itself. • An immature kerogen type III sample from Damoguaihe formation is subjected to HP and AHP tests. • Original and all artificially matured samples exhibited type IV isotherm with H3 hysteresis loops. • BET surface area, micro-, meso- and total PV of HP samples were higher than AHP ones. • The RBF AI model optimized by DE outperformed other RBF models in predicting N 2 adsorption/desorption. • N 2 adsorption/desorption is affected by relative pressure and pyrolysis pathway, the most, among all parameters. [ABSTRACT FROM AUTHOR]

• Primary and secondary cracking doesn't overlap under geological conditions. • Maturation yields heavier fluid with lower P sat , and lighter one with higher P sat. • Phase evolution systematics mimic natural petroleum well at similar maturity. For the exploration of shale oil, there is still an urgent need to relate hydrocarbon generation reactions and changing phase behavior to exact levels of thermal maturity. Six organic-rich shale samples from the Cretaceous Qingshankou Formation, Songliao Basin spanning the maturity range with vitrinite reflectance (R o) 0.58%–1.16% were studied for petroleum generation characteristics using the PhaseKinetics, PhaseSnapshot, and GORFit approaches. All samples show very good petroleum potential and contain Type I kerogen with total organic carbon contents ranging between 1.5% and 5%. A full spectrum of light to heavy hydrocarbons, consistent with live oils, occurs in thermal extracts of all samples. Gas chromatography fingerprints of samples with R o > 0.7% closely resemble waxy oils derived from lacustrine organic matter (OM); fingerprints of lower maturity samples are not yet as wax rich. The inferred petroleum type organofacies of all samples is paraffinic high wax with low organic sulfur levels. Hydrocarbon generation from the least mature sample is characterized by one dominant activation energy at 55 kcal/mol, accounting for 87% of the total bulk reaction. Assuming a simplified geological scenario, i.e., a 3 K/My linear heating rate, primary petroleum is generated (transformation ratio, i.e., TR : 10%–90%) over a narrow temperature interval of only 23 °C. Onset (10% TR), maximum (T peak), and completion (90% TR) temperatures and R o values are 141 °C at R o 0.85%, 155 °C at R o 1.08%, and 164 °C at R o 1.2%, respectively. Primary gas generation (148–172 °C) occurs 10 °C later (300 m deeper) than the generation of C 6+ compounds (138–161 °C). Secondary gas formation from oil cracking begins at 182 °C, maximizes at 197 °C, and is completed well before 225 °C (beginning of late gas generation from the secondary cracking of thermally matured, macromolecular organic matter) at 206 °C. Thus, primary and secondary oil cracking processes do not overlap under geological conditions. In line with a paraffinic high-wax oil petroleum type organofacies, cumulative fluids generated from the least mature sample fall within the black oil class over most of the primary kerogen conversion range up to 90% TR as indicated by low saturation pressures (P sat) and gas-oil-ratios generally below 160 Sm3/Sm3. Maturation results in relatively heavy fluids with P sat values in the range 40–70 bar when the free hydrocarbons, i.e., already present prior to pyrolysis, are included, and in lighter fluids with P sat values in the range 70–90 bar, when the free, mostly waxy hydrocarbons, are excluded. Systematics of physical properties and fluid compositions evolution reproduce the general behavior of naturally occurring petroleum sourced from lacustrine OM very well and fit physical properties and compositions of produced shale oils in the Songliao Basin at comparable maturity levels. [ABSTRACT FROM AUTHOR]

Graphical abstract A highly efficient enzyme-based ultrasound-assisted method with a response surface methodology (RSM) was carried out to exctract the tannins from the acorns. Interestingly, the extracted tannins exhibited the good corrosion inhibition for the mild steel in the NaCl solution. Highlights • Highly efficient enzyme-based ultrasound-assisted extraction method was used to extract the tannins from acorns. • Response surface methodology (RSM) was carried out to optimize the extraction conditions. • The optimized conditions were obtained. • Corrosion inhibition property of the extracted tannins was demonstrated. Abstract In this work, a highly efficient enzyme-based ultrasound-assisted method for the extraction of tannins from acorns was demonstrated and optimized. Based on a three-level four-factor Box Behnken Design (BBD), response surface methodology (RSM) was carried out to optimize the extraction conditions, including the ultrasonic time, ultrasonic power, cellulose concentration, and extraction temperature. Additionally, a second-order polynomial fit was performed to fit the experimental data. The optimized conditions were obtained, including the ultrasonic time (2.51 h), ultrasonic power (97.92 W), cellulose concentration (3.44 g/L), and extraction temperature (38.00 °C). Furthermore, the experimental extraction yield was 63.16 ± 0.12% under the optimal extraction conditions, which was in good agreement with the predictive yield of 63.42%. Interestingly, the potentiodynamic polarization and electrochemical impedance spectroscopy demonstrated that the extracted tannins exhibited the good corrosion inhibition for the mild steel in the NaCl solution. The corrosion inhibition efficiency of tannins reached 86.0%. [ABSTRACT FROM AUTHOR]

It is widely accepted that significant perturbations in ocean redox states are closely related to biological evolution during the early Cambrian. However, the host and geochemical cycle of redox-sensitive elements (V and Zn) of the Niutitang Formation shale in South China have not been well-constrained. This study reports lithofacies, mineralogy and geochemical data of high-resolution samples from slope and basin settings (Xa1 and Xb1 wells, Hunan Province), to evaluate the significance of redox condition and hydrothermal contribution to trace element accumulation during the early Cambrian. Our results reveal the Zn-rich host is primarily sphalerite, while the V-rich host includes organic matter, illite, and anatase minerals in the Niutitang shale. Illite and anatase minerals have significant V concentration (14.8% and 18.3%), whereas organic matter contains relatively lower V concentration (1.4%). Trace elements can be scavenged by dissolved organic matter in seawater, and then taken up by clay minerals or form sulfide during deposition/diagenesis of organic-rich shales. Although seawater restriction of the lower member (LM) shale was stronger than in the upper member (UM) shale, euxinic conditions were more conducive to V and Zn enrichment than ferruginous conditions. Specifically, dwindling concentrations of V and Zn in seawater existed in South China during deposition of the early LM shale. However, the ocean experienced episodic hydrothermal activity, which may have supplied abundant trace elements to supplement seawater content. Overall, we propose that the V and Zn geochemical cycles in the early Cambrian paleo-ocean were controlled by redox condition, organic matter, and the trace element inventory of seawater. • The hosts of V and Zn elements in organic-rich shale of Niutitang Formation have been determined. • Euxinic condition was more favorable for the enrichment of trace elements relative to ferruginous condition. • The seawater restriction of UM/LM shale of Niutitang Formation was investigated. • V and Zn inventory in the ocean was in a drawdown trend during the early Cambrian. • Hydrothermal activity may carry abundant trace elements into the ocean. [ABSTRACT FROM AUTHOR]

The Tuofutai Bulge in central Tabei of northern Tarim Basin provides insights into the complex geochemical processes of deep oil accumulations. Fifteen crude oil samples collected from deep Ordovician reservoirs were tested and analyzed with light hydrocarbons (LHs) and diamondoids to evaluate the oil family, secondary alteration, and mixing processes. Results show that the oil samples share similar distribution characteristics of LHs and diamondoids and contain low concentrations of methyldiamantanes, suggesting that they belong to one group and have not been significantly altered by thermal cracking. Geochemistry of LHs and diamondoids indicate that the thermochemical sulfate reduction is limited and negligible, whereas some samples are severely altered by biodegradation. The phase fractionation is mainly related to the leakage of light hydrocarbon caused by geological activities such as tectonic uplift and fault activity, and some samples show weak evaporative fractionation. The biodegradation causes the increase in the values of methyladamantane to adamantane (MAs/A) and the concentrations of (1 + 2)-methyladamantane and (3 + 4)-methyldiamantane. The thermal maturity of oil calculated on the basis of LHs and diamondoids is generally higher than that calculated using saturated and aromatic fractions. The difference of various maturity parameters related to saturated hydrocarbon, aromatic hydrocarbon, LHs and diamondoids records multiple oil charging and mixing processes. • Light hydrocarbons and diamondoids of the deep oils was revealed. • The deep oil suffered limited thermal cracking and weak evaporative fractionation. • Significant biodegradation was revealed in some oil samples. • Effect of biodegradation on diamondoid parameter was revealed. • Different molecular maturity indicators reflect multiple charging and mixing. [ABSTRACT FROM AUTHOR]

Pore structure plays an important role in controlling the oil migration and accumulation mechanism of subaqueous volcanic rocks (SVRs). The Santanghu Basin in western China is a unique region for providing insight into the pore structure characteristics of SVRs; however, little attention has been given to them. Thin-section analysis, scanning electron microscopy, low-temperature nitrogen adsorption (LTNA), pressure-controlled porosimetry, and nuclear magnetic resonance (NMR) experiments are performed on SVRs in the Santanghu Basin to reveal their pore structure characteristics and pore development patterns. The results show that the SVRs are dominated by ink bottle-shaped pores and have the characteristics of rather low matrix permeabilities (the Swanson parameters are mainly <4.0%/MPa), fine pore throats (r apex mainly <0.5 μm) and high capillary pressures (P 50 > 14.0 MPa). An effective method, namely, integrating NMR and LTNA experiments, is proposed to estimate the full-range pore size distribution (PSD) of the SVRs. In the full-range PSD, three peaks are identified at pore sizes of <1 μm, 1–10 μm and >10 μm, mainly corresponding to intercrystalline pores (IPs), dissolved pores (DPs), and residual vesicles (RVs), respectively. The storage space of SVRs is dominated by IPs, while the contents of DPs and RVs are the key to SVRs becoming effective reservoirs. The content of RVs is mainly controlled by the depth of the water body during deposition and the distance from the volcanic strata boundary. The higher the content of K and Na in the original composition and the closer the distance to the source rock is, the higher the proportion of DPs. In accordance with the original composition and the depth of the water body during deposition, the SVRs are divided into four types. Moreover, we propose the pore development patterns of the four types of volcanic rocks. RVs mainly exist in type I and type II SVRs, while DPs are important storage spaces in type I and type III SVRs. Finally, type IV SVRs only develop IPs and a few nanoscale DPs. • This paper characterized the pore development characteristics of SVRs in detail. • Pore development in SVRs depends on the depth of the water body during deposition and the original composition. • Division of four types of SVRs based on the formation environment and original composition. • Various types of SVRs show distinct differences in pore development pattern. [ABSTRACT FROM AUTHOR]

Abstract: Examination of whole oils and isolated oil acidic fractions using Fourier transform infrared (FT-IR), negative-ion microelectrospray high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR–MS) and gas chromatography–mass spectrometry (GC–MS) reveals significant differences in the functional groups, chemical classes and molecular weights of acidic components in crude oils derived from inland lacustrine source rocks in the Fula Sub-basin, Muglad Basin, Sudan. Correlation of the total acid number value (TAN) and bulk and molecular compositions with reservoir depth (temperature) indicates a strong influence of biodegradation on the origin of the high acidity in the oils and the possibility of distinguishing acidic compounds newly formed by way of in-reservoir biodegradation and those contributed directly from oil degrading bacteria. [Copyright &y& Elsevier]