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Accurately predicting permeability is important to elucidate the fluid mobility and development potential of tight reservoirs. However, for tight sandstones with the same porosity, permeability can change by nearly three orders of magnitude, which greatly increases the difficulty of permeability prediction. In this paper, we performed casting thin section, scanning electron microscopy and high-pressure mercury injection experiments to analyze the influence of pore structure parameters and fractal dimensions on the permeability of Chang 7 tight sandstones. Furthermore, the key parameters affecting the permeability were optimized, and a new permeability prediction model was established. The results show that the pore throat structure of Chang 7 tight sandstone exhibits three-stage fractal characteristics. Thus, the pore throat structure was divided into large pore throat, medium pore throat and small pore throat. The large pore throat reflects the microfracture system, whose fractal dimension was distributed above 2.99, indicating that the heterogeneity of the large pore throat was the strongest. The medium pore throat is dominated by the conventional pore throat system, and its fractal dimension ranged from 2.378 to 2.997. Small pore throats are mainly composed of the tree-shaped pore throat system, and its fractal dimension varied from 2.652 to 2.870. The medium pore throat volume and its fractal dimension were key factors affecting the permeability of Chang 7 tight sandstones. A new permeability prediction model was established based on the medium pore throat volume and its fractal dimension. Compared to other models, the prediction results of the new model are the best according to the analysis of root mean square value, average absolute percentage error and correlation coefficient. These results indicate that the permeability of tight sandstones can be accurately predicted using mesopore throat volume and fractal dimension. [ABSTRACT FROM AUTHOR]

This study analysed the associations of sex steroids with fat-free mass (FFM) and handgrip strength in 641 Chinese boys. Serum total testosterone (TT) and oestradiol were measured by chemiluminescence immunoassay. Free testosterone (FT) and oestradiol were calculated. FFM and handgrip strength were measured by bioelectrical impedance analysis and a hand dynamometer, respectively. Generalised additive models and multiple linear regression were used to explore the relationships. A subgroup analysis was conducted in early-mid pubertal and late-post pubertal groups. Age, height, weight, physical activity, intake of dietary protein and/or stage of puberty were adjusted. TT and FT were positively related to FFM and handgrip strength, with a curvilinear relationship being detected for handgrip strength (p<0.050). This curvilinear relationship was only observed in the late-post pubertal group, suggesting a potential threshold effect (FT>11.99ng/dL, β = 1.275, p = 0.039). In the early-mid pubertal group, TT and/or FT were linearly or near-linearly related to FFM or handgrip strength (β = 0.003–0.271, p<0.050). The association between FT and FFM was stronger than that in the late-post pubertal group. This study found that serum T had different associations with muscle parameters in Chinese early-mid pubertal and late-post pubertal boys. In the late-post pubertal boys, serum T was curvilinearly related to muscle strength with a threshold effect and its link with muscle mass was weaker. [ABSTRACT FROM AUTHOR]

In order to establish the distribution pattern of fine-grained sedimentary rocks and clarify the coupling relationship between lacustrine organic-rich fine-grained sedimentary rocks and tight oil reservoir, the Chang7 Member of Triassic Yanchang Formation in Longdong area was taken as an example to be studied by core description and log interpretation, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Lacustrine organic-rich fine-grained sedimentary rocks were divided into shale and mudstone according to their lithology and texture. The results show that the shale is mainly developed in Chang73 Sub-member, while the mudstone is developed in each sub-member of Chang7 Member. The organic-rich fine-grained sedimentary rocks in Bazhu-Maling-Qingcheng-Huachi area are the thickest in Longdong area. During the Chang73 sedimentary period, the shale was widely distributed in the center of the lake. In the Chang72 sedimentary period, the mudstone and turbidite were interstratified and superimposed. During the Chang71 sedimentary period, the mudstone was only distributed as thin layers between the thick turbidite. The Chang7 tight oil is widely distributed in the turbidite sand bodies, and it is mainly sourced from the Chang73 shale. The distribution of tight oil is controlled by the development of organic-rich fine-grained sedimentary rocks. [ABSTRACT FROM AUTHOR]

A multi-user multiple-input single-output simultaneous wireless information and power transfer full-duplex system with imperfect channel state information is considered. Under the assumption that the unknown channel estimation error is within a certain range, the self-interference cannot be suppressed completely at the base station and at the multi-user nodes. The proposed design problem is formulated as maximizing the average harvested energy of multi-user nodes and maintaining the signal-to-interference-plus-noise ratio requirement, which is proved to be non-convex. Utilizing semidefinite relaxation and S-procedure methods, a convex optimization problem of optimal beamforming vector for the multi-antenna transmitter is obtained. Moreover, semidefinite relaxation is proved to be tight by showing the existence of rank-one optimal solutions. Simulation results are presented to verify the robustness and effectiveness of the proposed algorithm compared with the non-robust design. [ABSTRACT FROM AUTHOR]

A multiple-input multiple-output two-way amplify-and-forward relay network with energy harvesting is considered in this paper. Under the transmit power constraints at sources and relay, a beamforming design problem is formulated, which minimizes the total mean square error while still guaranteeing sufficient energy harvested at the sources. Since this problem is nonconvex, an alternating optimization method based on generalized singular value decomposition (GSVD) is proposed and the algorithm is proved to be convergent. Moreover, based on the successive convex approximation, an iterative refinement is further designed to improve the solution quality of the GSVD scheme. Numerical results show good performance of the proposed schemes. [ABSTRACT FROM PUBLISHER]

A full-duplex (FD) two-way relay channel (TWRC) with multiple antennas is considered. For this three-node network, the beamforming design needs to suppress self-interference (SI). While a traditional way is to apply zero forcing (ZF) for SI mitigation, it may harm the desired signals. In this paper, a design that reserves a fraction of SI is proposed by solving a quality-of-service (QoS) constrained beamforming design problem. Since the problem is challenging due to the loop SI, a convergence-guaranteed alternating optimization (AO) algorithm is proposed to jointly design the relay–user beamformers. Numerical results show that the proposed scheme outperforms ZF method and achieves a transmit power value close to the ideal case. [ABSTRACT FROM PUBLISHER]

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]

In this paper, we first analyze the scalability and programming network architectures for Internet of things (IoT) in industries. Then, a representational state transfer(REST) framework for IoT based on software defined network (SDN) is proposed. Based on the proposed framework, control plane model and data plane model for IoT are proposed. In addition, a gateway model is provided to evaluate the proposed framework and use case results show that the proposed architectures are good for raw sensor data collecting. This framework provides a sharing mechanism for IoT in the modern manufacturing. [ABSTRACT FROM AUTHOR]

A multi-cell multi-input multi-output energy-harvesting network for factory-of-things is considered, where the control panel and smart devices are equipped with multiple antennas. Simultaneous wireless information and power transfer can deliver radio frequency energy for devices in the network, thus formulating the issue of quality of service(QoS). Each cell composes of one control panel and several smart devices where the process of SWIPT causes interference to each other, leading to a complicated non-convex problem. In order to solve it, the linear beamformers and receivers have been designed to maintain the QoS by minimizing the interference. Based on the minimum mean-square-error criterion, an joint controller-device design in which the control panels and smart devices would satisfy the transmit power constraints and the receiving energy bound is proposed. Numerical results of MSE uncover good performance of our proposed algorithm in this network. [ABSTRACT FROM AUTHOR]

In the Benxi Formation of the Carboniferous system of the Upper Paleozoic in the Ordos Basin, there are many sets of coal measures dark organic-rich shale, being marine continental transitional facies, with significant unconventional natural gas potential. Previous studies are only limited to the evaluation of tight sandstone reservoir in this set of strata, with no sufficient study on gas bearing and geological characteristics of organic-rich shale, restricting the exploration and evaluation of shale gas resources. In this study, analysis has been conducted on the organic carbon content, the major elements, the trace elements, and the mineral composition of core samples from the Benxi Formation in key drilling sections. In addition, qualitative and quantitative pore observation and characterization of core samples have been conducted. The sedimentary environments and reservoir characteristics of the shale of the Benxi Formation have been analyzed. Combined with the gas content analyzing the results of the field coring samples, the shale gas resource potentials of the Benxi Formation have been studied, and the geological characteristics of the Benxi Formation shale gas in the eastern Ordos Basin have been made clear, to provide a theoretical basis for shale gas resource evaluation of the Benxi Formation in the Ordos Basin. The results show that (1) in the Hutian Member, Pangou Member, and Jinci Member of the Benxi Formation, organic-rich shale is well developed, with the characteristics of seawater input as a whole. There is a slight difference in sedimentary redox index, which shows that the reducibility increases gradually from bottom to top. (2) There is an evident difference in the mineral characteristics of shale in these three members. The Hutian Member is rich in clay minerals, while the Jinci Member is high in quartz minerals. (3) The pores are mainly inorganic mineral intergranular pores, clay interlayer fractures, and micro fractures, and organic matter pores are developed on the surface of local organic matter. (4) The mud shale in the Jinci Member has a large cumulative thickness, has relatively high gas-bearing property, and is rich in brittle minerals. The Jinci Member is a favorable section for shale gas exploration of the Benxi Formation. [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]

Solid and hollow CoO nanospheres were synthesized by solvothermal method with oleic acid as reactant and SiO as template. Each sample of high-purity CoO was characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron energy spectroscopy, respectively. Both solid and hollow CoO nanospheres as anode for lithium-ion battery were tested by galvanostatic discharge-charge experiments. The first discharge capacity of 1598 and 1640 mAh g was obtained at 0.1 C for solid and hollow CoO nanospheres, respectively. Hollow CoO nanospheres showed better cycle performance. [ABSTRACT FROM AUTHOR]

The title compound, 1, with the formula [Mn2(pmt)2(1,10-phen)2].2ClO4 [N-(2-pyridylmethylidene)taurine (abbreviated as pmt), consists of a structurally centrosymmetric dinuclear MnII complex and two discrete perchlorate anions. Each Mn center is six-coordinated with an N4O2 donors set of the pmt and 1,10-phenanthorline ligands, resulting in a compressed octahedral. In the crystal packing, the component cations interact with pairs of intermolecular C-H···O and π-π contacts forming a 2-D network. Also, the neighboring 2-D cationic layers are connected to each other with C–H···O interactions of perchlorate oxygen atoms with the separate C···O distances of 3.204(7)-3.365(8) Å, giving a supramolecular 3-D network. [Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.] [ABSTRACT FROM AUTHOR]

A new Schiff base compound, (E)-N'-(5-bromo-2-hydroxy- benzylidene)-4-(quinolin-8-yloxy)butanehydrazide, 1, was synthesized and characterized by elemental analysis, IR spectrum, 1HNMR, and single crystal X-ray diffraction. The asymmetric unit of 1 contains two crystallographic independent molecules with different conformations along the bond sequence linking the benzene and quinoline rings, which have a mean interplanar dihedral angle of 58.9(6) and 10.2(6)°, respectively. In the crystal, the molecules are linked through hydrogen bonds of N-H...O and C-H...O to form an infinite 1-D chain, which is further extended to a supramolecular 3-D network via Br...Br and π...π interactions. The fluorescence property of the compound 1 was investigated. [ABSTRACT FROM AUTHOR]

Forty-six crude oil samples were selected from the Ordovician in the northwestern part of the Tahe oilfield for detailed molecular geochemical and isotopic analysis, including group compositions, carbon-hydrogen isotopes and gas chromatograms of saturated hydrocarbons, as well as the characteristics of terpane, sterane and other biomarkers, indicating that crude oils are of the same origin from different districts in the Tahe oilfield and were derived from the same source kitchen (or oil source formation), i.e., mainly stemming from marine hydrocarbons. Detailed studies of oil physical properties of 25-honpane revealed that such oils have heavy or thick oil qualities due to biodegradation. Comprehensive assessment in terms of five maturity parameters shows that the oils from the Ordovician with R values varying from 0.80% to 1.59% are widely distributed in the northwest of the Tahe oilfield. [ABSTRACT FROM AUTHOR]

In the future time the exploration of marine oil and gas will be one of the significant domains in China. In this paper the biomarker assemblage characteristics of oilshow in the Nanlinghu Formation of the Majiashan profile, which is located in Chaoxian County, south of Anhui Province, are described in the light of gas chromatography/mass spectrometric (GCMS) analysis on the qualitative and quantitative basis. Based on the investigation of the biomarker assemblage characteristics of possible source rocks developed in the area studied, a conclusion is drawn that the oilshow was generated from the Nanlinghu Formation source rocks (abbreviated as T1 n), instead of the Qixia Formation source rocks (abbreviated as P1 q). It is pointed out that the T1 n is of strong potential for future oil exploration, and therefore much attention should be paid to it. [ABSTRACT FROM AUTHOR]

The geochemical characteristics of natural gases discovered in the Bozhong Depression are systematically described in this paper. The natural gases are composed mainly of hydrocarbon gases. Natural gases occurring in the Paleogene and older reservoirs are wet gases, whereas those in the Neogene reservoirs are dry gases. Methane and ethane in the gases are significantly different in carbon isotopic composition. The methane carbon isotopic composition of the gases in structure BZ28-1 and the ethane carbon isotopic composition of the gases in structure QHD30-1 are characterized by the heaviest values, respectively. The natural gases are in the mature to highly mature stages. The hydrocarbon gases are of organic origin and can be classified as oil-type gases, coal-derived gases and mixed gases with the third one accounting for the major portion. [ABSTRACT FROM AUTHOR]

Gas chromatography fingerprint technique has the advantages of fast performance and low cost. It can be used to conduct analysis without interruption either in the field or at laboratory. This technique has been used successfully in such cases that conventional production logging techniques are powerless. Taking low-concentration anthracene as internal standard, we calculated the absolute concentrations of fingerprints, initially made some experiments directly on biodegradation of crude oils, and calculated production allocation in the Gudong Oil field. Compared with the production logging, this method has made up for the deficiencies of the former GC fingerprint technique. It will find wide applications in monitoring the trend of production in various oil-fields. [ABSTRACT FROM AUTHOR]

Field and laboratory analyses of carbonate rock samples from the Qiangtang Basin, Tibet, indicate that carbonate source rocks are mainly developed in the Middle Jurassic Xiali Formation and Upper Jurassic Suowa Formation. Comprehensive studies showed that the Suowa Formation carbonate source rocks have a favorable hydrocarbon-generating potential. The abundance of organic matter in the carbonate rocks is controlled mainly by sedimentary environment and inorganic compounds in the rocks, which is higher in the restricted platform facies than in the open platform facies. Organic carbon contents decrease with increasing CaO contents in the source rocks. [ABSTRACT FROM AUTHOR]

In order to analyze the organic matter (OM) composition, this study carefully identified the OM types of 66 samples from Well A in the Dingshan area under microscope, and made an effort to obtain the semi-quantitative statistics contents of different bio-precursor derived OM. The results of OM content obtained under microscope showed a strong positive relationship (R2 = 0.85) with the TOC content analyzed by carbon–sulfur analyzer. The OM contained bethic algae debris, phytoplankton amorphous organic matter (AOM), acritarch, vitrinite-like particles, zooplankton (including graptolite, chitinozoa and others) and solid bitumen which was secondary formation OM. The phytoplankton AOM, graptolite and solid bitumen were the dominated OM in this interval. Solid bitumen (8%~11%) was filled at the bottom of the Wufeng Formation, which could be one reason for the high shale gas production in the lower part of this shale interval. N2 adsorption results showed that micropores and mesopores were predominant in this shale gas system, while pore volumes illustrated better positive relationships with organic matter than minerals, especially AOM content. Thus, both solid bitumen and AOM kerogen were the main sources for shale gas generation in this shale gas system. [ABSTRACT FROM AUTHOR]

Establishing a suitable classification and evaluation scheme is crucial for sweet spot prediction and efficient development of shale oil in the Chang 71-2 sub-member of the Longdong area. In this paper, a series of experiments, such as casting thin sections (CTS), scanning electron microscopy (SEM), low-temperature nitrogen adsorption (LTNA), high-pressure mercury intrusion porosimetry (HMIP), and nuclear magnetic resonance (NMR), were integrated to classify the pore throats and shale oil reservoirs in the study area. Moreover, the pore structure characteristics of different types of reservoirs and their contributions to productivity were revealed. The results show that the pore-throat system can be divided into four parts: large pore throats (>0.2 μm), medium pore throats (0.08~0.2 μm), small pore throats (0.03~0.08 μm), and micropore throats (<0.03 μm). Based on the development degree of various pore throats, the reservoir is divided into four types: type I (Φ ≥ 10%, K > 0.1 mD), type II (Φ ≥ 8%, 0.05 mD < K < 0.1 mD), type III (Φ ≥ 5%, 0.02 mD < K < 0.05 mD) and type IV (Φ < 5% or K < 0.02 mD). From type I to IV reservoirs, the proportion of dissolved pores and intergranular pores gradually decreases, and the proportion of intercrystalline pores increases. The proportion of large pore throats gradually decreases, and the proportions of medium pore throats and small pore throats increase initially and then decrease, while the proportion of micropore throats increases successively. The NMR pore size distribution changes from the right peak to the left peak. The developed section of the type I reservoir corresponds to the oil layer, and the developed section of the type I and II reservoirs corresponds to the poor oil layer. In contrast, the developed section of the type III and IV reservoirs corresponds to the dry layer. The daily production from single wells is primarily attributable to type I and II reservoirs. [ABSTRACT FROM AUTHOR]

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]

Carbazole compounds are widely used in determining the direction of petroleum migration, but the effect of thermal maturity on carbazoles is still ambiguity. In this paper, using compaction pyrolysis simulation experiments, artificial mature samples with vitrinite reflectance (Ro) range from 0.38 to 3.0% were acquired. And the content and composition change characteristics of carbazole compounds were analyzed in coal source rocks. The experimental results showed that thermal maturity controls the generation of a large amount of carbazole compounds in coal rocks. Compared with the low mature stage, the content of carbazole compounds was about 10–100 times higher in the mature stage. With the increasing maturity, in the coal sample, the content of carbazole compounds showed a trend of first increasing and then decreasing. In derivatives of carbazole, the corresponding maturity for the maximum generation of ethylcarbazole (EC), dimethylcarbazole (DMCA), methylcarbazole (MCA), carbazole (CA) and benzocarbazole (BCA) performed the increasing sequence. With the increasing maturity, the relative abundance of 2-MCA, 1,7-DMCA and benzo[a]carbazole increased with the increasing maturity, while 4-MCA, 1,4-DMCA and benzo[c]carbazole gradually decreased. Benzocarbazole ratio [a]/[a] +[ c] varies only in a narrow range 0.36–0.61 in the entire maturity range, suggesting limited maturity dependence. The experimental conclusion provides more theoretical basis for future geochemical analysis using carbazole compounds. [ABSTRACT FROM AUTHOR]

We present a decade of observations of pulse arrival times for 85 pulsars using the Nanshan radio telescope from July 2002 to March 2014. The Cholesky method can accurately estimate the covariance function of the timing residuals, significantly improving the parameter's estimation accuracy when red noise is prominent. We utilize the Cholesky method to determine positions and basic timing parameters of these pulsars, as well as to obtain timing residuals. Most of these sources showed evidence of significant timing irregularities, which are described. The spectral analyses of timing residuals are presented for pulsars showing obvious red noise. Our results show that timing residuals in half of these pulsars are attributed to rotational irregularities. The red noise in normal pulsars may originate from a random walk in spin frequency or spin-down rate. [ABSTRACT FROM AUTHOR]

The exceptionally low geothermal gradient (~2 °C/100 m) in the Tarim Basin, notably in the Shuntuoguole (STGL) area with depths exceeding 7000 m, has catalyzed the discovery of ultra-deep liquid hydrocarbons. Yet, the genesis of these hydrocarbons remains elusive, presenting significant challenges to further exploration and development endeavors. To address this quandary, an extensive analysis involving biomarker assessments and compound-specific δ2H and δ13C isotopic evaluations of n-alkanes was conducted, unveiling the secondary alterations and origins of these crude oils. For the first time, an approximately horizontal distribution of compound-specific δ2H and δ13C in n-alkanes was observed. Through the integration of diagnostic biomarker compounds, it was elucidated that the STGL crude oils did not undergo significant biodegradation, thermal alteration, or thermal sulfate reduction. Biomarker- and compound-specific C/H isotopic correlations suggest that the STGL crude oil predominantly originates from the Lower Cambrian calcareous shale, positing it as a potential end-member oil for this lithofacial source rock. Furthermore, the STGL crude oil exhibits similar biomarker configurations (notably abundant C28 triaromatic sterones, C23 tricyclic terpenoids, and aryl isoprenoids, with minimal 4-methylstane and gammacerane presence) to those oils previously considered as mixed from the Tazhong and Tabei Uplifts within the Tarim Basin. This similarity suggests that these previously deemed mixed oils may also derive from the Lower Cambrian calcareous shale. Consequently, more focused investigations into the Lower Cambrian calcareous shale are imperative to bolster refined deep and ultra-deep petroleum exploration efforts within the Tarim Basin in forthcoming studies. [ABSTRACT FROM AUTHOR]

The simultaneous wireless information and power transfer (SWIPT) technique has been considered as a promising approach to prolong the lifetime of energy-constraint wireless sensor networks (WSNs). In this paper, a multiple-input multiple-output (MIMO) full-duplex (FD) bidirectional wireless sensor network (BWSN) with SWIPT is investigated. Based on minimum total mean-square-error (total-MSE) criterion, a joint optimization problem for source and relay beamforming and source receiving subject to transmitting power and harvesting energy constraints is established. Since this problem is non-convex, an iterative algorithm based on feasible point pursuit-successive convex approximation (FPP-SCA) is derived to obtain a local optimum. Moreover, considering the scenarios in which source and relay nodes equipped with the same and different numbers of antennas, a low-complexity diagonalizing design-based scheme is employed to simplify each non-convex subproblem into convex problems and to reduce the computational complexity. Numerical results of the total-MSE and bit error rate (BER) are implemented to demonstrate the performance of the two different schemes. [ABSTRACT FROM AUTHOR]

We consider a multiple-input multiple-output amplify-and-forward wireless multiple-hop sensor network (WMSN). The simultaneous wireless information and power transfer technology is deployed to potentially achieve an autonomous system. We investigate two practical receiver schemes, which are the power splitting (PS) and the time switching (TS). The power splitting receiver splits received signals into two streams, one for information decoding (ID) and the other for energy harvesting (EH). On the other hand, the time switching receiver only serves in ID mode or energy harvesting mode during a certain time slot. Subject to transmit power constraints and destination harvested energy constraint, we aim to obtain a joint beam-forming solution of source and relay precoders to maximize the maximum achievable rate of the WSN. In order to make the non-convex problem tractable, diagonalization-based alternating optimization algorithms are proposed. Numerical results show the convergence and good performance of the proposed algorithms under both PS and TS protocols. [ABSTRACT FROM AUTHOR]

Although tight oil reservoirs have abundant resources, their recovery efficiency is generally low. In recent years, CO2 injection huff-n-puff has become an effective method for improving oil recovery on the basis of depleted production of volume-fracturing horizontal wells in tight oil reservoirs. In order to study the effects of CO2 huff-n-puff (CO2-HnP) on production, a compositional numerical simulation study of CO2 huff-n-puff (CO2-HnP) was conducted in tight oil reservoirs with complex fractures. Embedded discrete fracture model technology was used in the simulations to characterize complex fractures. The process of CO2 huff-n-puff (CO2-HnP) was simulated, which consists of CO2 injection, CO2 soaking, and CO2 production. Taking into account the threshold pressure gradient and stress sensitivity in the model, we conducted a series of numerical simulations with different production condition parameters, such as bottom-hole pressure, CO2 injection rate, injection time, soaking time, and the number of cycles of CO2 huff-n-puff (CO2-HnP). Then, the effects of these sensitivity parameters on the cumulative oil production (COP) were studied. The results indicate that the threshold pressure gradient and rock stress sensitivity factors greatly affect the pressure field of tight reservoirs and the cumulative oil production (COP) of multistage-fracturing horizontal wells. The production parameters all have an impact on the COP. The injection rate and circulation number both have optimal values, and the injection time and soak time tend to have less significant effects on the growth of cumulative oil production over time. According to the numerical simulation, the optimal solution is 5 × 104 m3/day injection rate per cycle, 25 days of injection time, 35 days of soaking time, three cycles, and production for 5 years, which can obtain the optimal cumulative oil production. [ABSTRACT FROM AUTHOR]

This paper discussed the direction of secondary migration of oil in the No. 6 area of the Melut Basin by making use of nitrogen compounds as secondary oil migration tracers. From the results, we have found that the occurrence and compositional characteristics of isomeric-nitrogen compounds in crude oil precisely manifest the fractionation effect of oil migration: with increasing secondary migration distance, the absolute concentrations tend to decrease, and the ratio of nitrogen-shielded isomers to nitrogen exposed isomers tends to increase. It is considered that the main direction of oil migration in the No. 6 area of the Melut Basin is from north to south. [ABSTRACT FROM AUTHOR]

The oil discovery in the Precambrian basement fractured buried-hills of the Bongor Basin, Chad, is a milestone for the African onshore exploration play. Geochemical techniques including GC, GC/MS were adopted to analyze the biomarker composition and geochemical characteristics of oils from the Baobab buried-hill and shales from the Baobab N and Mimosa (MM) sags, respectively. The oil-source correlations were carried out for the buried hill oils and source rocks of BN/MM sags, and the hydrocarbon accumulation process was interpreted based on the thermal evolution history. The results indicate that BN/MM sags have contributed to the oils of the Baobab buried-hill field along with two phases of hydrocarbon accumulations. The MM sag started to expel hydrocarbon in the middle Late Cretaceous (about 85 Ma), and then in the late Late Cretaceous (about 70 Ma) both the MM and BN sags expelled hydrocarbons for the Baobab buried-hill trap. [ABSTRACT FROM AUTHOR]

The Non-uniformity of Infrared Focal Plane Arrays (IRFPA) severely degrades the infrared image quality. An effective non-uniformity correction (NUC) algorithm is necessary for an IRFPA imaging and application system. However traditional scene-based NUC algorithm suffers the image blurring and artificial ghosting. In addition, few effective hardware platforms have been proposed to implement corresponding NUC algorithms. Thus, this paper proposed an improved neural-network based NUC algorithm by the guided image filter and the projection-based motion detection algorithm. First, the guided image filter is utilized to achieve the accurate desired image to decrease the artificial ghosting. Then a projection-based moving detection algorithm is utilized to determine whether the correction coefficients should be updated or not. In this way the problem of image blurring can be overcome. At last, an FPGA-based hardware design is introduced to realize the proposed NUC algorithm. A real and a simulated infrared image sequences are utilized to verify the performance of the proposed algorithm. Experimental results indicated that the proposed NUC algorithm can effectively eliminate the fix pattern noise with less image blurring and artificial ghosting. The proposed hardware design takes less logic elements in FPGA and spends less clock cycles to process one frame of image. [ABSTRACT FROM AUTHOR]

PSR B0820 + 02 is known to exhibit the subpulse drifting phenomenon, which carries vital information about the pulsar radiation process. In this work, we studied the subpulse drifting of PSR B0820 + 02 at a central frequency of 1250 MHz using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Thanks to the superior sensitivity of FAST, we found that PSR B0820 + 02 shows four distinct subpulse drifting modes (A, B, C, and D), the last three of which have not been reported before. The drifting periodicities of these four modes are found to be 4.3 P 1, 6.4 P 1, 8.2 P 1, and 10.3 P 1 (P 1 is the pulse period), respectively. No null pulse is found in our FAST observation. By comparing the energy distribution of single pulses of all four modes, we found that mode A has the highest energy and mode D has the lowest energy. Finally, we interpreted the drift modes in terms of the carousel model, and showed that if B0820 + 02's different drift modes are due to aliasing effects, the carousel rotation period of P 4 lies in the range 29 P 1–33 P 1. The new subpulse drifting phenomena of PSR B0820 + 02 reported here provide a unique opportunity for understanding the mechanism and radiation geometry of pulsar radio radiation. [ABSTRACT FROM AUTHOR]

• The cherts in the slope and basin setting were strongly affected by hydrothermal activities. • The oxygen isotope value of paleo-seawater was assessed during the early Cambrian. • The paleo-seawater temperature presented an obvious gradient trend in South China. • There existed an oxygen minimum zone (OMZ) during the shelf and slope transition. • Biological reproduction was closely related to seawater temperature and oxic environment. The Ediacaran–Cambrian transition period was a critical time interval for the environmental fluctuations and organismal evolution in geological history, popularly known as the "Cambrian Explosion". The diagenetic mechanism of the widely developed Liuchapo bedded cherts in South China remain unclear and controversial during this critical time interval. To address this, we examined silicon and oxygen isotopes, as well as major and trace elements in the Liuchapo cherts from three wells developed from slope to basin facies in South China. Results reveal that the bedded cherts from the three wells were affected by episodic hydrothermal activity, and the percentage of hydrothermal fluids is highest in the Xc1 well and lowest in the Xb1 well. The paleo-seawater temperature, calculated from chert oxygen isotope values, present a gradual increasing trend from shallow- to deep- areas in South China from 542 to 526 Ma. Redox proxies indicate that the water column of the Xa1 and Xc1 wells were dominated by suboxic condition, while those of the Xb1 well was mainly in oxic conditions. There should exist an oxygen minimum zone (OMZ) during the shelf and slope transition. A suitable temperature and oxic environment are conducive to biological reproduction, which is consistent with higher primary productivity and abundant acritarch fossils in the Xb1 well. Silicon isotope values range from −0.6 ‰ to 1.2 ‰ in the three wells. The diagenetic origin of the Xa1, Xb1, and Xc1 wells was the consequence of the mixture of hydrothermal fluid and seawater, biological activity, and direct hydrothermal precipitation, respectively. Due to the redox condition and seawater temperature variation, silica-secreting organisms should be relatively limited. The episodic hydrothermal fluid, biological activity, and replacement of precursor rock may jointly affect the formation of the Liuchapo bedded cherts during the Ediacaran–Cambrian transition. [ABSTRACT FROM AUTHOR]

In Internet of Things scenarios, the problem of restricted energy and limited computation capability of user node usually exists. To address the problem, a multiple‐input‐multiple‐output full‐duplex multi‐hop relay simultaneous wireless information and power transfer (SWIPT) mobile‐edge computing (MEC) system is proposed in this paper, where energy harvesting model is non‐linear. With the aid of MEC and SWIPT, user node equipped with power splitting receiver can locally execute computation tasks or offload partial or all of it to access point associated with an MEC server by using its battery energy, and harvest energy to replenish its battery while downloading the computation results. In addition, the system introduces full‐duplex multi‐hop relay and non‐linear energy model to improve network coverage and model practical energy harvesting circuit. Aiming at minimising the system energy consumption, an energy efficient optimisation problem is formulated while satisfying the latency and energy constraints. Since the original problem is non‐linear and non‐convex, it is converted into two subproblems and successive convex approximation‐based algorithm and geometric programming‐based algorithm based alternating optimisation technique are adopted to solve them. Numerical results verify the superiority of the proposed optimisation scheme compared with other benchmark schemes. [ABSTRACT FROM AUTHOR]

In Internet of Things scenarios, the problem of restricted energy and limited computation capability of user node usually exists. To address the problem, a multiple‐input‐multiple‐output full‐duplex multi‐hop relay simultaneous wireless information and power transfer (SWIPT) mobile‐edge computing (MEC) system is proposed in this paper, where energy harvesting model is non‐linear. With the aid of MEC and SWIPT, user node equipped with power splitting receiver can locally execute computation tasks or offload partial or all of it to access point associated with an MEC server by using its battery energy, and harvest energy to replenish its battery while downloading the computation results. In addition, the system introduces full‐duplex multi‐hop relay and non‐linear energy model to improve network coverage and model practical energy harvesting circuit. Aiming at minimising the system energy consumption, an energy efficient optimisation problem is formulated while satisfying the latency and energy constraints. Since the original problem is non‐linear and non‐convex, it is converted into two subproblems and successive convex approximation‐based algorithm and geometric programming‐based algorithm based alternating optimisation technique are adopted to solve them. Numerical results verify the superiority of the proposed optimisation scheme compared with other benchmark schemes. [ABSTRACT FROM AUTHOR]

This paper proposes a multiple‐input multiple‐output full‐duplex relay Internet of Things system under imperfect channel state information, where the relay uses time switching relaying protocol to harvest energy. Particularly, due to the uncertainty channel circumstance, the self‐interference in full‐duplex relay cannot be eliminated completely. For such a system, a joint source‐relay beamforming optimization problem which maximizes the system achievable rate subject to the transmit power and harvested energy constraints is studied. In light of the intractability of the problem, a singular value decomposition based geometric programming algorithm is investigated. The considered problem is reformulated to a diagonalized form by using singular value decomposition method. Then, the geometric programming algorithm is adopted to obtain the optimal solution for the reformulated problem. Numerical results validate the effectiveness and superiority of the proposed optimization scheme. [ABSTRACT FROM AUTHOR]

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]

• A europium-doped CdTe quantum dots fluorescence sensor was easily fabricated. • The sensor exhibited a dosage-sensitive and broad-chromatic detection strategy. • CdTe quantum dots enhanced the emission of europium ions by charge transfer. • Dual-response sensor offered multicolor variations for naked eyes. • The sensor visibly detected tetracycline under the maximum residue limits in milk. Residues in animal food and drinking water caused by the abuse of antibiotics lead to cell resistance and many chronic diseases in the human body. Therefore, it has become an inevitable trend to develop a fast, easy-to-use, on-site/real-time visualization method for the detection of antibiotics. Herein, we report a dual-response ratiometric fluorescence sensor which is fabricated by chelating europium ions (Eu3+) onto cadmium telluride quantum dots (CdTe QDs) for real-time and visible detection of tetracycline (TC). With the TC addition, the fluorescence of probe can be seen by the naked eye, from green to yellow and finally to red, exhibiting a dosage-sensitive and broad-chromatic detection strategy for TC. The fluorescence intensity ratio of I 616 /I 512 of Eu/CdTe QDs sensor displays a good linear relation to TC concentrations in the range of 0–80 μM with a limit of detection (LOD) of 2.2 nM. In addition, the sensor can visually detect 200 nM TC in actual samples, which is lower than the maximum residue limit (MRL) of the safety standard. The methodology reported here opens a window toward the real applications of fluorescent and shows the wide applicability in pursuing the concepts simple, rapid, visual, and real-time for food safety and environmental protection. [ABSTRACT FROM AUTHOR]

An immature humic coal sample from the Yaojie Formation of the Muli coal field is pyrolysed in a hydrous closed system. The differences in aromatic hydrocarbon compositon between bitumens and expelled oils are investigated with the simulation temperature ranging from 250 to 500 °C. The absolute concentrations of the main aromatic classes in bitumens and expelled oils initially increase and thereafter decrease with increasing maturity. The absolute concentrations of naphthalene are always higher in expelled oils than in the corresponding bitumens; however, the absolute concentrations of alkyl-naphthalenes, phenanthrene, and alkyl-phenanthrenes are higher in bitumens than in expelled oils at the lower-maturity stage, and reversals occur with continuous increase in R O. Most of the common parameters—MNR, MPI1, MPR, F 1, and F 2—exhibit regular differences in bitumen–expelled oil pairs. The ratios of different alkylation degrees of naphthalenes and phenanthrenes (such as N/C 1–5 -N, C 1 -N/C 1–5 -N, C 1 -N/C 5 -N, P/C 1–3 -P, and C 1 -P/C 3 -P) and the ratios of aromatic components (such as naphthalene/phenanthrene, phenanthrene/fluoranthene, and phenanthrene/pyrene) that have different numbers of aromatic rings exhibit regular differences in bitumen–expelled oil pairs. These ratios of expelled oils are always higher than those of corresponding bitumens; reversals may occur at a high maturity stage. The systematic differences between the compositions of the main aromatic hydrocarbons in bitumens and expelled oils could be predominantly controlled by the fractionation effect at a lower-temperature stage and differentiated decomposition at a higher-temperature stage during the hydrous pyrolysis of coal. • Fractionation effects of aromatic hydrocarbons during expulsion process have been studied by hydrous pyrolysis of coal. • The fractionation effects occur at lower temperature stage and general reversal occurs at higher temperature stage. • The major control factors are fractionation effect at lower maturity and differentiated decomposition at higher maturity. [ABSTRACT FROM AUTHOR]

Oil samples from the Bongor Basin, SW Chad have been geochemically characterized to investigate the biodegradation influence on alkylphenanthrenes. Concentrations of C0–3-alkylphenanthrenes (C0–3Ps) increase markedly after level 6 biodegradation due to the removal of other vulnerable components, decrease sharply after level 7 biodegradation and approach to absence at level 8. Phenanthrene appears to have higher ability to resist biodegradation than C1–3Ps at certain biodegradation levels (≤level 7) due to demethylation, which has been inferred as a possible reaction process during biodegradation of the aromatic hydrocarbons. The enrichment of non-alkylated phenanthrene in biodegraded oils makes biodegradation assessment complicated on the basis of alkylphenanthrene distributions. Individual isomers in alkylphenanthrenes exhibit variable ability to resist biodegradation influence. While certain isomers do show higher ability to resist biodegradation than others, no uniform biodegradation sequence can be established. Meanwhile, the biodegradation susceptibility between hopanes and alkylphenanthrenes varies greatly in different samples. The biodegradation systematics of alkylphenanthrenes proves to be highly complex, which may be indicative of the multiple charges and mixing during biodegradation. [ABSTRACT FROM AUTHOR]

The simultaneous wireless information and power transfer (SWIPT) technique has been regarded as an appealing approach to prolong the lifetime of wireless sensor networks. However, co-channel interferences with SWIPT in wireless networks have not been investigated from a green communication perspective. In this paper, joint transmit and receive beamforming design for a full-duplex multiple-input multiple-output amplify-and-forward relay system with simultaneous wireless information and power transfer in WSNs is investigated. Multiple co-channel interferers are considered at the relay and destination sensor nodes. To minimize the mean-squared-error of the system, joint source and relay beamforming optimization is proposed while guaranteeing the transmit power constraints and destination's energy harvesting constraint. An iterative algorithm based on alternating optimization with successive convex approximation which converges to a local optimum is proposed to solve the non-convex problem. Moreover, a low-complexity scheme is derived to reduce the computational complexity. Simulations for MSE versus iterations and MSE versus signal-to-noise ratio (SNR) demonstrate the convergence and good performance of the proposed schemes. [ABSTRACT FROM AUTHOR]

We describe PSR J1926−0652, a pulsar recently discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive single-pulse detections from FAST and long-term timing observations from the Parkes 64 m radio telescope, we probed phenomena on both long and short timescales. The FAST observations covered a wide frequency range from 270 to 800 MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at least four profile components, short-term nulling lasting from 4 to 450 pulses, complex subpulse drifting behaviors and intermittency on scales of tens of minutes. While the average band spacing P3 is relatively constant across different bursts and components, significant variations in the separation of adjacent bands are seen, especially near the beginning and end of a burst. Band shapes and slopes are quite variable, especially for the trailing components and for the shorter bursts. We show that for each burst the last detectable pulse prior to emission ceasing has different properties compared to other pulses. These complexities pose challenges for the classic carousel-type models. [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]

• Using neutral alumina as a stationary phase and disposable glassware such as Pasteur pipettes can separate hopanes successfully. • The sterane content of the collected hopanes decreased from the original 12% to 0.84%, compared to urea complexation. • Neutral alumina column chromatography meets the needs of experimenters for smaller and simpler devices. • The separated hopanes can meet the requirements of stable carbon isotopes of monomer hydrocarbons detection. This paper presents a small-scale column chromatography method for separating hopanes in crude oil or rock extracts using neutral alumina as a solid phase adsorbent and a Pasteur pipette as a separation device. Three oil samples were selected to study the effect of solid phase adsorbent type and column length on the separation of hopanes. The oil samples were eluted with mixed reagents (V hexane : V petroleum ether = 8:2) and collected at intervals of 0.5 ml. Ten Fractions were collected and tested for the compounds using GC–MS. A quantitative approach was used to reveal distribution characteristics of compounds in each eluted Fraction. Experimental results showed that 100–200 um neutral alumina exhibited significant differences in the adsorptive capacity of biomarkers from oil samples and rock extracts. The elution order of the biomarkers in the chromatographic column (the length is 180 mm) was n-alkanes, steranes and hopanes. The separation of hopanes could be realized by collecting the eluted Fractions 4 and 5. Compared with the urea complexation, the purity of hopanes separated by column chromatography was higher. The concentration of n-alkanes (nC 16 - nC 34) could be reduced from 1.99 to 4.83 mg/ml to 0.79–0.94 mg/ml, and the content of steranes can be reduced from the original 12% to 0.45%. Residual n-alkanes and steranes were not visible in the GC–MS detection. The Total Ion Chromatography (TIC) of hopanes was consistent with the distribution characteristics of the m/z 191 mass chromatogram. The isolated hopanes could meet the detection requirements of isotope ratio mass spectrometry. The C 29 Ts / C 29 αβ ratio of hopanes decreased gradually from 1.63 to 0.73 as the column length increased. It is speculated that the variation of the C 29 Ts/C 29 αβ ratio is not only affected by maturity but also by the oil and gas migration. This method is a new attempt in the field of compound purification and can be widely used in the study of stable carbon isotopes of hopanes monomeric hydrocarbons. [ABSTRACT FROM AUTHOR]

The central Junggar Basin in western China is unique because it provides insights into the geochemistry of oil from Jurassic coal measures. The analysis of TOC, Rock-Eval pyrolysis, gas chromatography-mass spectrometry (GC-MS), and carbon isotopes was performed to characterize the oil geochemistry and evaluate the hydrocarbon generation potential of source rocks in a coal-bearing formation. Fluid inclusions, fluorescence microscopy, and burial-thermal history were also used to study the oil generation and charging histories. The results show that the mudstone of the Badaowan Formation is the main source rock of the Jurassic and has relatively high hydrocarbon generation potential. The Jurassic oil in the Zhong-4 Block is moderately mature, with an equivalent Ro of about 0.75%. The oil is characterized by heavy carbon isotopes, a predominance of Pr over the Ph, low abundances of trisnorhopane (Ts), tricyclic terpanes and gammacerane, predominance of C 29 steranes among regular steranes, a preponderance of naphthalene and its alkylated analogues in aromatic compounds, and abundant polycyclic compounds. Such geochemical data indicate a contribution of Jurassic humic type organic matter to the oil. The mudstone in the Badaowan Formation started generating hydrocarbons in the Early Cretaceous and reached the peak of hydrocarbon generation in the middle Cretaceous. One major hydrocarbon charging episode is suggested in the Late Cretaceous and another in the early Neogene. The Fukang Depression in the south is the source kitchen, and oil migrates in a direction of southwest to northeast through faults and sandstone carrier beds. • The Jurassic mudstones and oils are mostly within the oil window. • The mudstone in Badaowan Formation is the primary Jurassic source rock. • Unique biomarker characteristics of the Jurassic oil are demonstrated. • The Jurassic oil shows heavy carbon isotopes (δ 13 C > -28‰). • Two major hydrocarbon charging periods for the Jurassic reservoirs are suggested. [ABSTRACT FROM AUTHOR]

This paper proposes an approach to establishing correspondences for line intersections on multi-sensor images containing lines. Keypoints have been widely applied in a variety of computer vision fields. On multi-sensor images the number of keypoints may be much smaller than on single-sensor images due to the lack of texture. In addition, the multimodality often causes the incorrect assignment of main orientation to keypoints. Observing this, this paper proposes extracting line intersections as keypoints and utilizing one line as the main orientation to compute edge oriented histogram (EOH) descriptor. For EOH descriptor, gradient orientation is employed to compute the filter responses. Experimental results show that the proposed method can build more reliable keypoint matchings on challenging image pairs such as visible image and middle/long-wave infrared images. [ABSTRACT FROM AUTHOR]