•Geo-mechanical effects, gas adsorption effects, real gas effects and rarefaction effects were reviewed.•Klinkenberg correction and slip boundary conditions were collected and compared.•Bulk phase ...gas transporting models are classified into eight types.•Surface diffusion in shale gas reservoirs were summarized and compared.•Three types of gas transporting models are categorized.
Accurate understanding of gas micro seepage mechanisms in shale plays is of great importance for numerical simulation and productivity prediction. Classical seepage theory fails to build the constitutive relation of fluid flow in shale matrix, while current models show discrepancies from one to another. In this review, current bulk phase gas transporting models in literatures are classified into eight types, where consistency and diversity among them are revealed, with three recommended for shale gas seepage modeling on different purposes. The unification contributes to understand the role of different seepage mechanisms and helps to eliminate the confusion of different roles that each mechanism may play during mathematical modeling and gas production. Different approaches of handling geo-mechanical effects, ad-/de-sorption, real gas effects and rarefaction effects are introduced and compared, with recommended methods given after comparison. Based on practical pore size distribution, in-situ pressure and temperature, five ways of calculating gas mean free paths are compared, after which the possible flow regimes in practical shale plays are divided according to Knudsen number. Various empirical Klinkenberg correction methods and slip boundary conditions are summarized and compared, showing that some are inappropriate to describe rarefaction effects. Different ways of modeling Knudsen and surface diffusion are reviewed and analyzed. Considering the role of viscous flow, slippage effect, Knudsen diffusion and surface diffusion, gas transporting models are categorized into three types. The review provides the recent development and a systematic summarization on analytical modeling of gas transporting as well as the related unique phenomena in shale nanopores, which promotes the understanding of the complex and special micro seepage mechanisms in shale gas reservoirs.
Cross-interference is not only an important factor that affects the measuring accuracy of three-dimensional force sensors, but also a technical difficulty in three-dimensional force sensor design. In ...this paper, a cross-interference suppression method is proposed, based on the octagonal ring's structural symmetry as well as Wheatstone bridge's balance principle. Then, three-dimensional force sensors are developed and tested to verify the feasibility of the proposed method. Experimental results show that the proposed method is effective in cross-interference suppression, and the optimal cross-interference error of the developed sensors is 1.03%. By optimizing the positioning error, angle deviation, and bonding process of strain gauges, the cross-interference error of the sensor can be further reduced to -0.36%.
Nitrogen-doped (N-doped) graphene has been prepared by a simple one-step hydrothermal approach using hexamethylenetetramine (HMTA) as single carbon and nitrogen source. In this hydrothermal process, ...HMTA pyrolyzes at high temperature and the N-doped graphene subsequently self-assembles on the surface of MgO particles (formed by the Mg powder reacting with H2O) during which graphene synthesis and nitrogen doping are simultaneously achieved. The as-synthesized graphene with incorporation of nitrogen groups possesses unique structure including thin layer thickness, high surface area, mesopores and vacancies. These structural features and their synergistic effects could not only improve ions and electrons transportation with nanometer-scale diffusion distances but also promote the penetration of electrolyte. The N-doped graphene exhibits high reversible capacity, superior rate capability as well as long-term cycling stability, which demonstrate that the N-doped graphene with great potential to be an efficient electrode material. The experimental results provide a new hydrothermal route to synthesize N-doped graphene with potential application for advanced energy storage, as well as useful information to design new graphene materials.
Siliciclastic grain size, clay mineralogy, and major element geochemistry of Core MD05–2893 from the lower continental slope off the Sunda Shelf in the southern South China Sea were investigated to ...assess the response of terrigenous sediment input to sea-level and climatic changes since the last deglaciation. The chronology is based on foraminiferal AMS 14C dates and oxygen isotope records combined with carbonate stratigraphy. In this study, we reconstruct variations in terrigenous sediment input using clay/silt, TiO2/CaO, SiO2/Al2O3, Al2O3/K2O, and smectite/(illite + chlorite) proxies. Clay/silt, TiO2/CaO, and SiO2/Al2O3 ratios are clearly correlated to sea-level change, showing high values during the early phase of deglacial sea-level rise (17.2–14.5 cal ka BP, Stage I) and rapidly decreasing values during the meltwater pulse 1A and further sea-level rise (14.5–11.1 cal ka BP, Stage II). Meanwhile, variations in Al2O3/K2O and smectite/(illite + chlorite) correspond well to monsoon rainfall variability during the late phase of deglacial sea-level rise and Holocene sea-level highstand (11.1–1.5 cal ka BP, Stage III). Based on these records, we recognize three stages of evolution of terrigenous sediment input to the southern South China Sea continental slope. Dominance of terrigenous sediment input occurred during Stage I, when most part of the Sunda Shelf was still exposed and drained by several rivers. The stepwise elevated sea level by meltwater pulse 1A and subsequent rising sea-level after 14.5 cal ka BP could have led to a drop in terrigenous sediment input to this area due to regression of the paleo-Sunda river systems (Stage II). Thereafter during last phase of sea-level rise and sea-level highstand with the evolution of the modern coast, sediments have a clear fingerprint of chemical weathering induced by a strengthening of the East Asian summer monsoon (Stage III). Our findings highlight that the variability of terrigenous sediment input to the lower continental slope in the southern South China Sea was first in the late Pleistocene mainly driven by sea-level change and later in the Holocene by a strengthened East Asian summer monsoon.
•Multiple sources have contributed terrigenous sediments to the southern South China Sea.•Higher terrigenous sediment input to the South China Sea occurred during the sea-level lowstand.•Terrigenous input has been controlled by sea-level change and East Asian monsoon evolution.
The South China Sea offers an excellent case for studying source-to-sink transport processes of fluvial sediments among the global marginal seas. This study synthesizes existing clay mineralogical ...and geochemical data from ~1500 samples from the seafloor and surrounding rivers, deepwater mooring observation results, and high-resolution glacial–cyclic clay mineralogy records from six high-quality sediment cores. Source-to-sink sediment transport from the river mouth to the continental shelf and then to the abyssal basin is investigated at two time scales: modern process and Late Quaternary glacial cycles. The results firstly show the high diversity of clay mineralogical and geochemical compositions in riverbed surface sediments surrounding the South China Sea, e.g., dominant illite and chlorite in Taiwan, overwhelming majority of smectite in Luzon, dominant kaolinite in South China, and similar amounts of the four clay mineral species in Red and Mekong river systems. The formation of these fluvial sediments through chemical weathering in surrounding drainage systems is controlled principally by the East Asian monsoon climate with warm temperature and high precipitation, and subordinately by tectonic activity and specific lithological character. The basin-wide distribution of clay mineral assemblages combined with neodymium and strontium isotopic compositions reflects strong provenance control and differential settling effects. The differential settling of kaolinite in slightly saline and proximal regions relative to smectite in more saline and distal regions is well demonstrated in the South China Sea. Through combining clay mineralogical distributions on the seafloor with observed oceanic current systems, the modern transport pathways can be well established, e.g., in the northern South China Sea, illite and chlorite from Taiwan are mainly carried by contour currents with the strong influence of mesoscale eddies.
High-resolution sediment dynamic analysis for the Late Quaternary reveals different sediment transport patterns in the northern, western, and southern South China Sea when the land–sea configuration dramatically changed during glacial conditions. In the north, the terrigenous dispersal is mainly controlled by provenance supply and oceanic current transport. In the west, the clay mineral assemblage reflects variations of the prevailing surface current influenced by monsoon winds. In the south, the clay mineral input indicates intensive chemical weathering during interglacial periods and strengthened physical erosion during glacial periods. The transport of terrigenous sediments since the last glaciation is quantitatively reconstructed through studying two deepwater sediment cores located in the northern South China Sea. The relative contributions from three provenances (South China, Luzon, and Taiwan) highlight their distinct variability over the last 28ka, implying that the southward shift of the inter-tropical convergence zone (ITCZ) at 16ka BP caused an increased sediment contribution from South China, the intensified influence of the Kuroshio Current intrusion controls more efficient westward transport of Luzon sediments, and the stronger deepwater current transports Taiwan-sourced sediments further westward from the last glaciation to the Holocene.
Summary Background Clonal haemopoiesis of indeterminate potential (CHIP) is an age-associated genetic event linked to increased risk of primary haematological malignancies and increased all-cause ...mortality, but the prevalence of CHIP in patients who develop therapy-related myeloid neoplasms is unknown. We did this study to investigate whether chemotherapy-treated patients with cancer who have CHIP are at increased risk of developing therapy-related myeloid neoplasms. Methods We did a nested, case-control, proof-of-concept study to compare the prevalence of CHIP between patients with cancer who later developed therapy-related myeloid neoplasms (cases) and patients who did not develop these neoplasms (controls). We identified cases from our internal biorepository of 123 357 patients who consented to participate in the Total Cancer Care biobanking protocol at Moffitt Cancer Center (Tampa, FL, USA) between Jan 1, 2006, and June 1, 2016. We included all individuals who were diagnosed with a primary malignancy, were treated with chemotherapy, subsequently developed a therapy-related myeloid neoplasm, and were 70 years or older at either diagnosis. For inclusion in this study, individuals must have had a peripheral blood or mononuclear cell sample collected before the diagnosis of therapy-related myeloid neoplasm. Controls were individuals who were diagnosed with a primary malignancy at age 70 years or older and were treated with chemotherapy but did not develop therapy-related myeloid neoplasms. Controls were matched to cases in at least a 4:1 ratio on the basis of sex, primary tumour type, age at diagnosis, smoking status, chemotherapy drug class, and duration of follow-up. We used sequential targeted and whole-exome sequencing and described clonal evolution in cases for whom paired CHIP and therapy-related myeloid neoplasm samples were available. The primary endpoint of this study was the development of therapy-related myeloid neoplasm and the primary exposure was CHIP. Findings We identified 13 cases and 56 case-matched controls. The prevalence of CHIP in all patients (23 33% of 69 patients) was higher than has previously been reported in elderly individuals without cancer (about 10%). Cases had a significantly higher prevalence of CHIP than did matched controls (eight 62% of 13 cases vs 15 27% of 56 controls, p=0·024; odds ratio 5·75, 95% CI 1·52–25·09, p=0·013). The most commonly mutated genes in cases with CHIP were TET2 (three 38% of eight patients) and TP53 (three 38% of eight patients), whereas controls most often had TET2 mutations (six 40% of 15 patients). In most (four 67% of six patients) cases for whom paired CHIP and therapy-related myeloid neoplasm samples were available, the mean allele frequency of CHIP mutations had expanded by the time of the therapy-related myeloid neoplasm diagnosis. However, a subset of paired samples (two 33% of six patients) had CHIP mutations that decreased in allele frequency, giving way to expansion of a distinct mutant clone. Interpretation Patients with cancer who have CHIP are at increased risk of developing therapy-related myeloid neoplasms. The distribution of CHIP-related gene mutations differs between individuals with therapy-related myeloid neoplasm and those without, suggesting that mutation-specific differences might exist in therapy-related myeloid neoplasm risk. Funding Moffitt Cancer Center.
High-resolution major element geochemistry of Core MD05–2892 from the lower Sunda Slope was analyzed to investigate the variation of chemical weathering records and its controlling factors in the ...southern South China Sea since the last glaciation. Chemical index of alteration (CIA) and SiO2/Na2O ratio were selected as chemical weathering proxies. The values of the proxies are higher during the last glaciation than during the Holocene. We attribute this to the provenance shift caused by sea level change. Provenance analysis indicates that the Malay Peninsula and Sumatra were the major sediment sources for the study region during the last glaciation, while the Indochina Peninsula has been the major source since the early Holocene. Accordingly, the weathering evolution analysis reveals increased physical erosion in the Malay Peninsula and Sumatra during enhanced East Asian summer monsoon rainfall, while increased chemical weathering in the Indochina Peninsula during the intensified monsoon rainfall. Therefore, the chemical weathering records of the deep-sea sediments in the southern South China Sea were regulated by monsoon rainfall-driven physical erosion in the Malay Peninsula and Sumatra during the last glaciation, while the records have been influenced by monsoon rainfall-induced chemical weathering in the Indochina Peninsula since the early Holocene. This study emphasizes that higher weathering values of the deep-sea sediments during the last glaciation could be related to the provenance variation driven by sea level change, rather than to enhanced chemical weathering in the same provenance.
•Provenance of sediments off the Sunda Shelf has changed from glaciation to Holocene.•Intensive chemical weathering occurred on Malay Peninsula/Sumatra during glaciation.•Sea level and East Asian monsoon have jointly affected deep-sea weathering records.
•An intermediate fluid thermoelectric generator system is proposed.•Separation of the exhaust channel and the thermoelectric module is achieved.•Heat is transferred by the boiling and condensation of ...the intermediate fluid.•The peak output power increases and optimal thermoelectric module area is reduced.•Module temperature distribution is more uniform than in the traditional system.
In order to improve the power generation performance of automobile exhaust thermoelectric generator, an intermediate fluid thermoelectric generator system is proposed in this work. In the proposed system, the waste exhaust heat is transferred through boiling and condensation of the intermediate fluid. Consequently, the separation between the exhaust channel and thermoelectric module induces a higher heat flux on the hot side of the module. A mathematical model is also established to analyze the power generation characteristics of the proposed system. Compared with the traditional thermoelectric generator system, for the same heat exchange area on the exhaust side, not only is the peak output power increased by 32.6%, but the optimal thermoelectric module area is also reduced by 73.8%. The generation capacity per unit area is 1162 W/m2 at peak output power, which is 5.12 times that of the traditional thermoelectric generator system.
Spatial separation of the reductive and oxidative reaction sites of ZnIn2S4 nanosheet and acceleration of the hole transfer process was achieved by simply depositing cobalt phosphate (Co-Pi), a ...non-precious co-catalyst, on its basal plane. Co atoms of Co-Pi preferentially bonded with S atoms nearby the Zn vacancies to form Co-S bonds, which could passivate the surface states of ZnIn2S4 by extracting the trapped holes.
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Developing photocatalyst with effective charge separation and fast surface reaction kinetics is crucial to high-efficiency photocatalytic H2 evolution. Herein we spatially separate the reductive and oxidative reaction sites of ZnIn2S4 nanosheet and accelerate the hole transfer process by simply depositing cobalt phosphate (CoHxPOy, noted as Co-Pi), a non-precious co-catalyst, on its basal plane. Theoretical calculations combined with comprehensive characterizations reveal that Zn vacancies induced deep local energy levels serve as hole trap states to pin the photogenerated holes on (001) surface of ZnIn2S4. Upon Co-Pi deposition, Co atoms preferentially bond with S atoms nearby the Zn vacancies of ZnIn2S4. Taking advantage of the formation of Co-S bonds, Co-Pi acts as a hole receptor to extract the trapped holes effectively. As the photocatalytic activity of ZnIn2S4 is caused by active S atoms on its edge side, deposition of Co-Pi on planar side of nanosheets helps electron-hole migration to different facets. As a result of inert facet activation and spatial carrier separation, Co-Pi/ZnIn2S4 exhibits a superior photocatalytic H2 evolution rate of 10.19 mmol g-1h−1 under visible light, which is superior to most of reported ZnIn2S4-based photocatalysts. This work will provide novel insights into the activation of inert basal planes of two-dimensional photocatalysts.
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