Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these reso...Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these resources are hindered due to an incomplete understanding of their nature and origin.Here we present results from a comprehensive study on the hydrochemical parameters,whole-rock geochemistry,H-O isotopes,and Li concentrations in surface brine,river water,geothermal springs,and associated rocks from two representative lithium-enriched salt lakes,the Laguo Co(LGC)and Cangmu Co(CMC)in Tibet to understand the genetic mechanisms.Our water-salt balance calculations and H-O isotopic analysis reveal that Li in LGC and CMC primarily originates from the Suomei Zangbo(SMZB,~91%)and Donglong Zangbo(DLZB,~75%)rivers,respectively.It is estimated that the LGC and CMC took a minimum of 6.0 ka and 3.0 ka to accumulate their current lithium resources,respectively.The distinct geological characteristics reflect evolutionary differences between the two lakes,suggesting diverse lithium sources and enrichment processes.The high lithium ion concentration and light lithium isotope composition in the SMZB river waters indicate the genetic relationship with lithium-enriched geothermal springs in the Tibetan Plateau.Our results suggest that lithium in the LGC originates from lithium-enriched geothermal springs and is primarily supplied through the small-scale SMZB river.In contrast,the formation and evolution of CMC are influenced by the northern Lunggar rifts,receiving a prolonged and stable input from the DLZB,resulting in high lithium concentrations and isotopic values.The absence of lithium-enriched geothermal springs and the prevalence of silicate rocks in the CMC catchment suggest that lithium may be sourced from the weathering of silicate rocks,such as granitic pegmatite veins containing lithium-rich beryl,widely distributed in the upstream area of DLZB.The forward modeling approach,quantifying the contribution fractions of different reservoirs(atmospheric precipitation,silicate,carbonate,and evaporite),indicates that the distinct lithium concentrations in the mainstream(>1 mg/L)and tributaries(<0.1 mg/L)are positively correlated with the ratio of silicate contributions to carbonate contributions,suggesting that dissolved lithium in river waters primarily originates from the weathering and dissolution of silicate rocks.The distinct sources and enrichment mechanisms of lithium in these two salt lakes are attributed to various evolutionary processes,topographical features,hydrological factors,fundamental geological settings,and tectonic histories,despite their spatial proximity.Furthermore,our study highlights the significant role of rivers in the formation of young salt lakes,in addition to geothermal springs.展开更多
The phenomenon of carbon isotopic fractionation,induced by the transport of methane in tight sedimentary rocks through processes primarily involving diffusion and adsorption/desorption,is ubiquitous in nature and play...The phenomenon of carbon isotopic fractionation,induced by the transport of methane in tight sedimentary rocks through processes primarily involving diffusion and adsorption/desorption,is ubiquitous in nature and plays a significant role in numerous geological and geochemical systems.Consequently,understanding the mechanisms of transport-induced carbon isotopic fractionation both theoretically and experimentally is of considerable scientific importance.However,previous experimental studies have observed carbon isotope fractionation phenomena that are entirely distinct,and even exhibit opposing characteristics.At present,there is a lack of a convincing mechanistic explanation and valid numerical model for this discrepancy.Here,we performed gas transport experiments under different gas pressures(1–5 MPa)and confining pressures(10–20 MPa).The results show that methane carbon isotope fractionation during natural gas transport through shale is controlled by its pore structure and evolves regularly with increasing effective stress.Compared with the carbon isotopic composition of the source gas,the initial effluent methane is predominantly depleted in^(13)C,but occasionally exhibits^(13)C enrichment.The carbon isotopic composition of effluent methane converges to that of the source gas as mass transport reaches a steady state.The evolution patterns of the isotope fractionation curve,transitioning from the initial non-steady state to the final steady state,can be categorized into five distinct types.The combined effect of multi-level transport channels offers the most compelling mechanistic explanation for the observed evolution patterns and their interconversion.Numerical simulation studies demonstrate that existing models,including the Rayleigh model,the diffusion model,and the coupled diffusion-adsorption/desorption model,are unable to describe the observed complex isotope fractionation behavior.In contrast,the multi-scale multi-mechanism coupled model developed herein,incorporating diffusion and adsorption/desorption across multi-level transport channels,effectively reproduces all the observed fractionation patterns and supports the mechanistic rationale for the combined effect.Finally,the potential carbon isotopic fractionation resulting from natural gas transport in/through porous media and its geological implications are discussed in several hypothetical scenarios combining numerical simulations.These findings highlight the limitations of carbon isotopic parameters for determining the origin and maturity of natural gas,and underscore their potential in identifying greenhouse gas leaks and tracing sources.展开更多
In this paper,we present a fast mode decomposition method for few-mode fibers,utilizing a lightweight neural network called MobileNetV3-Light.This method can quickly and accurately predict the amplitude and phase info...In this paper,we present a fast mode decomposition method for few-mode fibers,utilizing a lightweight neural network called MobileNetV3-Light.This method can quickly and accurately predict the amplitude and phase information of different modes,enabling us to fully characterize the optical field without the need for expensive experimental equipment.We train the MobileNetV3-Light using simulated near-field optical field maps,and evaluate its performance using both simulated and reconstructed near-field optical field maps.To validate the effectiveness of this method,we conduct mode decomposition experiments on a few-mode fiber supporting six linear polarization(LP)modes(LP01,LP11e,LP11o,LP21e,LP21o,LP02).The results demonstrate a remarkable average correlation of 0.9995 between our simulated and reconstructed near-field lightfield maps.And the mode decomposition speed is about 6 ms per frame,indicating its powerful real-time processing capability.In addition,the proposed network model is compact,with a size of only 6.5 MB,making it well suited for deployment on portable mobile devices.展开更多
Tantalum carbon(TaC)alternate coatings with sublayers comprised of different crystallite morphologies were prepared on carbon/carbon composites by chemical vapor deposition.Their ablative behaviors and defending mecha...Tantalum carbon(TaC)alternate coatings with sublayers comprised of different crystallite morphologies were prepared on carbon/carbon composites by chemical vapor deposition.Their ablative behaviors and defending mechanisms were both investigated.The specimen with the sublayer composed of columnar crystals exhibited a better ablation resistance due to the toughness enhancement induced by the lami-nated structure.However,the mechanical denudation of the sample only containing acicular crystals and the coating spallation caused by superfluous gaseous products of the sample with the sublayer composed of nanocrystals both indicate their inferior anti-ablation properties.It is believed that the results will be helpful for the structural design and practical application of chemical vapor deposition(CVD)alternate coatings.展开更多
OBJECTIVE:To observe the therapeutic effect of lumbar tender point deep tissue massage plus lumbar traction on chronic non-specific low back pain using change in pressure pain threshold,muscle hardness and pain intens...OBJECTIVE:To observe the therapeutic effect of lumbar tender point deep tissue massage plus lumbar traction on chronic non-specific low back pain using change in pressure pain threshold,muscle hardness and pain intensity as indices.METHODS:We randomly divided 64 patients into a treatment group(32 cases) and a control group(32 cases).Two drop-outs occurred in each group.Patients in the treatment group received tender point deep tissue massage plus lumbar traction and patients in the control group received lumbar traction,alone.We used a tissue hardness meter/algometer and visual analog scale(VAS) to assess the pressure pain threshold,muscle hardness and pain intensity.RESULTS:Following treatment,we obtained the following results in the treatment and control groups,respectively:the pressure pain threshold difference was 1.5±0.8 and 1.1±0.7;the muscle hardness difference was 4.2±1.6 and 3.5±1.3;and the VAS score difference was 1.9±0.9 and 1.4±0.8.Compared to the control group,the treatment group had higher pressure pain threshold(t=2.09,P<0.05),and lower muscle hardness(t=2.05,P<0.05) and pain intensity(t=2.46,P<0.05).CONCLUSION:Lumbar tender point deep tissue massage combined with lumbar traction produced better improvement in pressure pain threshold,muscle hardness and pain intensity in patients with chronic non-specific low back pain than with lumbar traction alone.展开更多
Following shale gas, shale oil has become another highlight in unconventional hydrocarbon exploration and development. A large amount of shale oil has been produced from a host of marine shale in North America in rece...Following shale gas, shale oil has become another highlight in unconventional hydrocarbon exploration and development. A large amount of shale oil has been produced from a host of marine shale in North America in recent years. In China, lacustrine shale, as the main source rock of conventional oil and gas, should also have abundant oil retained in place. In this study, geochemical and geologic characteristics of lacustrine shale from Es3L sub-member in Bonan sag were characterized by using total organic carbon（TOC）, Rock-Eval pyrolysis, X-ray diffraction, and ？log R method. The results show that the Es3L sub-member shale have TOC contents ranging from 0.5 wt.% to 9.3 wt.%, with an average of 2.9 wt.%. The organic matter is predominantly Type I kerogen, with minor amounts of Type II1 kerogen. The temperature of maximum yield of pyrolysate（Tmax） values ranges from 424 to 447 ℃, with an average of 440 ℃, and vitrinite reflectance（Ro%） ranges from 0.7% to 0.9%, indicating most of shales are thermally mature. The dominant minerals of Es3L shale in Bonan sag are carbonates（including calcite and dolomite）, averaging 51.82 wt.%, and the second minerals are clay（mostly are montmorillonite-illite-mixed layer and illite） and quartz, averaging about 18 wt.%. Finally, its shale oil resources were evaluated by using the volumetric method, and the evaluation result shows that the shale oil resource is up to 5.94 billion tons, and mostly Class I resource. Therefore, the exploration of the lacustrine shale oil of Es3L in Bonan sag should be strengthened.展开更多
Ternary organic solar cells(OSCs) have received extensive attention for improving the power conversion efficiency(PCE) of organic photovoltaics(OPVs). In this work, a novel donor material(ECTBD) consisting of benzodit...Ternary organic solar cells(OSCs) have received extensive attention for improving the power conversion efficiency(PCE) of organic photovoltaics(OPVs). In this work, a novel donor material(ECTBD) consisting of benzodithiophene(BDT) central electron donor unit was developed and synthesized. The small molecular donor has the same central unit as PM6. The addition of ECTBD into PM6:Y6 system could improve the morphology of active blend layer. In addition, ECTBD showed good morphologically compatibility when blending with PM6:Y6 host, resulting in the improvement of fill factor and current density. As a result, the ternary devices based on PM6:ECTBD:Y6 ternary system achieved a highest PCE of 16.51% with fill factor of 76.24%, which was much higher than that of the binary devices(15.7%). Overall, this work provided an effective strategy to fabricate highly efficient ternary organic solar cells through design of the novel small molecular donor as the third component.展开更多
The power co nversion efficiency(PCE)of OFQx-T:PC_(71)BM blend films reaches 7.59%.On this basis,ternary organic solar cells(OSCs)were fabricated with ITIC or PTB7-Th as the third component.The ternary OSCs with 50 wt...The power co nversion efficiency(PCE)of OFQx-T:PC_(71)BM blend films reaches 7.59%.On this basis,ternary organic solar cells(OSCs)were fabricated with ITIC or PTB7-Th as the third component.The ternary OSCs with 50 wt%ITIC in acceptors exhibits an enhanced efficiency,from 7.59%to 8.17%.Also,the PCE of ternary OSCs with 50 wt%PTB7-Th in donors achieves 8.72%,which is 13%higher than that of binary OSCs.The PCE improvement of two ternary OSCs is mainly due to the increase of short-circuit current density(J_(SC)),which can be attributed to the complementary absorption spectra and improved film morphology.This work suggests that the selection of an appropriate third component plays a critical role in improving the PCE of ternary OSCs.展开更多
基金This project was jointly supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2022QZKK0202)the National Natural Science Foundation of China(Grant No.U22A20573)the Fundamental Research Funds for the Central Universities(Grant No.B230201014).
文摘Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these resources are hindered due to an incomplete understanding of their nature and origin.Here we present results from a comprehensive study on the hydrochemical parameters,whole-rock geochemistry,H-O isotopes,and Li concentrations in surface brine,river water,geothermal springs,and associated rocks from two representative lithium-enriched salt lakes,the Laguo Co(LGC)and Cangmu Co(CMC)in Tibet to understand the genetic mechanisms.Our water-salt balance calculations and H-O isotopic analysis reveal that Li in LGC and CMC primarily originates from the Suomei Zangbo(SMZB,~91%)and Donglong Zangbo(DLZB,~75%)rivers,respectively.It is estimated that the LGC and CMC took a minimum of 6.0 ka and 3.0 ka to accumulate their current lithium resources,respectively.The distinct geological characteristics reflect evolutionary differences between the two lakes,suggesting diverse lithium sources and enrichment processes.The high lithium ion concentration and light lithium isotope composition in the SMZB river waters indicate the genetic relationship with lithium-enriched geothermal springs in the Tibetan Plateau.Our results suggest that lithium in the LGC originates from lithium-enriched geothermal springs and is primarily supplied through the small-scale SMZB river.In contrast,the formation and evolution of CMC are influenced by the northern Lunggar rifts,receiving a prolonged and stable input from the DLZB,resulting in high lithium concentrations and isotopic values.The absence of lithium-enriched geothermal springs and the prevalence of silicate rocks in the CMC catchment suggest that lithium may be sourced from the weathering of silicate rocks,such as granitic pegmatite veins containing lithium-rich beryl,widely distributed in the upstream area of DLZB.The forward modeling approach,quantifying the contribution fractions of different reservoirs(atmospheric precipitation,silicate,carbonate,and evaporite),indicates that the distinct lithium concentrations in the mainstream(>1 mg/L)and tributaries(<0.1 mg/L)are positively correlated with the ratio of silicate contributions to carbonate contributions,suggesting that dissolved lithium in river waters primarily originates from the weathering and dissolution of silicate rocks.The distinct sources and enrichment mechanisms of lithium in these two salt lakes are attributed to various evolutionary processes,topographical features,hydrological factors,fundamental geological settings,and tectonic histories,despite their spatial proximity.Furthermore,our study highlights the significant role of rivers in the formation of young salt lakes,in addition to geothermal springs.
基金the National Natural Science Foundation of China(Grant Nos.42302170,42302160)the Innovation Platform for Academicians of Hainan Province(YSPTZX202301)+3 种基金the National Postdoctoral Innovative Talent Support Program(Grant No.BX20220062)the National Science Foundation of Heilongjiang Province of China(Grant No.YQ2023D001)the Project of Sanya Yazhou Bay Science and Technology City(Grant No.SCKJ-JYRC-2023-01)CNPC Innovation Found(Grant No.2022DQ02-0104).
文摘The phenomenon of carbon isotopic fractionation,induced by the transport of methane in tight sedimentary rocks through processes primarily involving diffusion and adsorption/desorption,is ubiquitous in nature and plays a significant role in numerous geological and geochemical systems.Consequently,understanding the mechanisms of transport-induced carbon isotopic fractionation both theoretically and experimentally is of considerable scientific importance.However,previous experimental studies have observed carbon isotope fractionation phenomena that are entirely distinct,and even exhibit opposing characteristics.At present,there is a lack of a convincing mechanistic explanation and valid numerical model for this discrepancy.Here,we performed gas transport experiments under different gas pressures(1–5 MPa)and confining pressures(10–20 MPa).The results show that methane carbon isotope fractionation during natural gas transport through shale is controlled by its pore structure and evolves regularly with increasing effective stress.Compared with the carbon isotopic composition of the source gas,the initial effluent methane is predominantly depleted in^(13)C,but occasionally exhibits^(13)C enrichment.The carbon isotopic composition of effluent methane converges to that of the source gas as mass transport reaches a steady state.The evolution patterns of the isotope fractionation curve,transitioning from the initial non-steady state to the final steady state,can be categorized into five distinct types.The combined effect of multi-level transport channels offers the most compelling mechanistic explanation for the observed evolution patterns and their interconversion.Numerical simulation studies demonstrate that existing models,including the Rayleigh model,the diffusion model,and the coupled diffusion-adsorption/desorption model,are unable to describe the observed complex isotope fractionation behavior.In contrast,the multi-scale multi-mechanism coupled model developed herein,incorporating diffusion and adsorption/desorption across multi-level transport channels,effectively reproduces all the observed fractionation patterns and supports the mechanistic rationale for the combined effect.Finally,the potential carbon isotopic fractionation resulting from natural gas transport in/through porous media and its geological implications are discussed in several hypothetical scenarios combining numerical simulations.These findings highlight the limitations of carbon isotopic parameters for determining the origin and maturity of natural gas,and underscore their potential in identifying greenhouse gas leaks and tracing sources.
基金supported by the Scientific Research Fund of Hunan Provincial Education Department of China(No.22B0324)the Natural Science Foundation of Hunan Province of China(No.2020JJ5606)。
文摘In this paper,we present a fast mode decomposition method for few-mode fibers,utilizing a lightweight neural network called MobileNetV3-Light.This method can quickly and accurately predict the amplitude and phase information of different modes,enabling us to fully characterize the optical field without the need for expensive experimental equipment.We train the MobileNetV3-Light using simulated near-field optical field maps,and evaluate its performance using both simulated and reconstructed near-field optical field maps.To validate the effectiveness of this method,we conduct mode decomposition experiments on a few-mode fiber supporting six linear polarization(LP)modes(LP01,LP11e,LP11o,LP21e,LP21o,LP02).The results demonstrate a remarkable average correlation of 0.9995 between our simulated and reconstructed near-field lightfield maps.And the mode decomposition speed is about 6 ms per frame,indicating its powerful real-time processing capability.In addition,the proposed network model is compact,with a size of only 6.5 MB,making it well suited for deployment on portable mobile devices.
基金supported by the National Natu-ral Science Foundations of China(Nos.51727804,52130205,and 91860203)the National Key R&D Program of China(No.2021YFA0715803)The authors also thank the Analytical&Testing Center of Northwestern Polytechnical University for the characteri-zation of our samples.
文摘Tantalum carbon(TaC)alternate coatings with sublayers comprised of different crystallite morphologies were prepared on carbon/carbon composites by chemical vapor deposition.Their ablative behaviors and defending mechanisms were both investigated.The specimen with the sublayer composed of columnar crystals exhibited a better ablation resistance due to the toughness enhancement induced by the lami-nated structure.However,the mechanical denudation of the sample only containing acicular crystals and the coating spallation caused by superfluous gaseous products of the sample with the sublayer composed of nanocrystals both indicate their inferior anti-ablation properties.It is believed that the results will be helpful for the structural design and practical application of chemical vapor deposition(CVD)alternate coatings.
基金Supported by the Olympic Games scientific research project of the General Administration of Sport of China No.2011A020the National Natural Science Foundation of China(No.61172007/F010810)
文摘OBJECTIVE:To observe the therapeutic effect of lumbar tender point deep tissue massage plus lumbar traction on chronic non-specific low back pain using change in pressure pain threshold,muscle hardness and pain intensity as indices.METHODS:We randomly divided 64 patients into a treatment group(32 cases) and a control group(32 cases).Two drop-outs occurred in each group.Patients in the treatment group received tender point deep tissue massage plus lumbar traction and patients in the control group received lumbar traction,alone.We used a tissue hardness meter/algometer and visual analog scale(VAS) to assess the pressure pain threshold,muscle hardness and pain intensity.RESULTS:Following treatment,we obtained the following results in the treatment and control groups,respectively:the pressure pain threshold difference was 1.5±0.8 and 1.1±0.7;the muscle hardness difference was 4.2±1.6 and 3.5±1.3;and the VAS score difference was 1.9±0.9 and 1.4±0.8.Compared to the control group,the treatment group had higher pressure pain threshold(t=2.09,P<0.05),and lower muscle hardness(t=2.05,P<0.05) and pain intensity(t=2.46,P<0.05).CONCLUSION:Lumbar tender point deep tissue massage combined with lumbar traction produced better improvement in pressure pain threshold,muscle hardness and pain intensity in patients with chronic non-specific low back pain than with lumbar traction alone.
基金supported by the National Natural Science Foundation of China (Nos. 41672116, 41330313)the Fundamental Research Funds for the Central Universities (No. 17CX05012)National Science and Technology Major Project of China (Nos. 2017ZX05049004, 2016ZX05046-001)
文摘Following shale gas, shale oil has become another highlight in unconventional hydrocarbon exploration and development. A large amount of shale oil has been produced from a host of marine shale in North America in recent years. In China, lacustrine shale, as the main source rock of conventional oil and gas, should also have abundant oil retained in place. In this study, geochemical and geologic characteristics of lacustrine shale from Es3L sub-member in Bonan sag were characterized by using total organic carbon（TOC）, Rock-Eval pyrolysis, X-ray diffraction, and ？log R method. The results show that the Es3L sub-member shale have TOC contents ranging from 0.5 wt.% to 9.3 wt.%, with an average of 2.9 wt.%. The organic matter is predominantly Type I kerogen, with minor amounts of Type II1 kerogen. The temperature of maximum yield of pyrolysate（Tmax） values ranges from 424 to 447 ℃, with an average of 440 ℃, and vitrinite reflectance（Ro%） ranges from 0.7% to 0.9%, indicating most of shales are thermally mature. The dominant minerals of Es3L shale in Bonan sag are carbonates（including calcite and dolomite）, averaging 51.82 wt.%, and the second minerals are clay（mostly are montmorillonite-illite-mixed layer and illite） and quartz, averaging about 18 wt.%. Finally, its shale oil resources were evaluated by using the volumetric method, and the evaluation result shows that the shale oil resource is up to 5.94 billion tons, and mostly Class I resource. Therefore, the exploration of the lacustrine shale oil of Es3L in Bonan sag should be strengthened.
基金supported by the National Science Fund for Distinguished Young Scholars (21925506)the National Key R&D Program of China (2017YFE0106000)+5 种基金the National Natural Science Foundation of China (51773212)National Natural Science Foundation of China (21875286)Ningbo S&T Innovation 2025 Major Special Programme (2018B10055)Ningbo Municipal Science and Technology Innovative Research Team (2015B11002, 2016B10005)CAS Key Project of Frontier Science Research (QYZDB-SSW-SYS030)Science Fund for Distinguished Young Scholars of Hunan Province (2017JJ1029)。
文摘Ternary organic solar cells(OSCs) have received extensive attention for improving the power conversion efficiency(PCE) of organic photovoltaics(OPVs). In this work, a novel donor material(ECTBD) consisting of benzodithiophene(BDT) central electron donor unit was developed and synthesized. The small molecular donor has the same central unit as PM6. The addition of ECTBD into PM6:Y6 system could improve the morphology of active blend layer. In addition, ECTBD showed good morphologically compatibility when blending with PM6:Y6 host, resulting in the improvement of fill factor and current density. As a result, the ternary devices based on PM6:ECTBD:Y6 ternary system achieved a highest PCE of 16.51% with fill factor of 76.24%, which was much higher than that of the binary devices(15.7%). Overall, this work provided an effective strategy to fabricate highly efficient ternary organic solar cells through design of the novel small molecular donor as the third component.
基金supported by the National Natural Science Foundation of China(No.21506258)Natural Science Foundation of Hunan Province(Nos.2016JJ3134,2017JJ2325)。
文摘The power co nversion efficiency(PCE)of OFQx-T:PC_(71)BM blend films reaches 7.59%.On this basis,ternary organic solar cells(OSCs)were fabricated with ITIC or PTB7-Th as the third component.The ternary OSCs with 50 wt%ITIC in acceptors exhibits an enhanced efficiency,from 7.59%to 8.17%.Also,the PCE of ternary OSCs with 50 wt%PTB7-Th in donors achieves 8.72%,which is 13%higher than that of binary OSCs.The PCE improvement of two ternary OSCs is mainly due to the increase of short-circuit current density(J_(SC)),which can be attributed to the complementary absorption spectra and improved film morphology.This work suggests that the selection of an appropriate third component plays a critical role in improving the PCE of ternary OSCs.
