With the development of aero-engines, the turbine inlet temperature continues to rise. In order to ensure the safety and reliability of the turbine blades, cooling structures must be set inside turbine blades to cool ...With the development of aero-engines, the turbine inlet temperature continues to rise. In order to ensure the safety and reliability of the turbine blades, cooling structures must be set inside turbine blades to cool them. Heat transfer coefficient and flow resistance are the key parameters to measure the cooling characteristics of internal cooling structures. In this paper, the characteristics of flow resistance in a rotating ribbed channel is presented numerical simulation under different rib spacings, rib angles, and thermal boundary conditions. The results show that, separation and reattachment of fluid between ribs is the key effect of rib spacing on flow resistance. The flow resistance is small when the rib spacing is small, because it's difficult for the fluid to form reattachment between the ribs. With the increase of rib spacing, the reattachment phenomenon is more obvious and the flow resistance increases accordingly. In general,p: e=10 channel has the maximum flow resistance. Secondary flow caused by the ribs is the key factor affecting the flow resistance characteristics with different rib angles. The secondary flow interacts with the main flow and causes flow loss through mixing, thus affecting the flow resistance of the channel. Under static condition, the flow resistance of 60°ribbed channel is the largest. The flow resistance of channel was affected by the temperature rise ratio also. And with the increase of the Ro, the temperature rise ratio has a more obvious effect on the flow resistance of the ribbed channel.When Ro=0.45, the flow resistance of the channel with a temperature rise ratio of 0.4 is 2.4 times that of the channel without temperature rise, while when Ro=0.3, it is 1.6 times, and when Ro=0.15, it is 1.2 times.展开更多
In this paper,the flow and heat transfer characteristics in U-shaped channel with three different turn shapes are studied.The rotation number ranges from 0~0.251,Reynolds number are 11500,23000,34500,respectively.The ...In this paper,the flow and heat transfer characteristics in U-shaped channel with three different turn shapes are studied.The rotation number ranges from 0~0.251,Reynolds number are 11500,23000,34500,respectively.The results show that the flow separation and reattachment in the turning section are the key factors affecting the local heat transfer and pressure loss of U-shaped channel.The square turn will generate corner vortices at the outside of the turning section,and the size of the inner separation vortex and reattachment vortex is larger than that of the other two turn shapes.The existence of vortex system will increase the mixing and enhance heat transfer,but increase the pressure loss,so its relative Nusselt number and pressure loss are the largest.There are corner vortices on the outside of the turning section of the channel with a inner circle turn and outer square turn,but the arc-shaped inner edge makes its separation delay and the separation vortex decrease,and the size of the reattachment vortex also decreases.The arc shaped outer edge of the channel with circle turn in both inner and outer further inhibits the generation of corner vortices,so its relative Nusselt number and pressure loss are the lowest.Rotation will cause the fluid to deflect under the influence of Coriolis force,strengthen the heat transfer on the trailing surface of radial outflow and the leading surface of radial internal flow,and generate secondary flow and separation vortex in the turning section,resulting in the change of vortex structure in the turning section.With the increase of rotation number,the Nusselt number of the three types of turning section structures increases.The thermal performance factor of the three channels increases with the increase of rotating speed,and the channel with a inner circle turn and outer square turn is the highest,which is 9.6%higher than the channel with circle turn in both inner and outer on average,and 17.8%higher than the channel with square turn in both inner and outer.展开更多
In this paper,the numerical simulation method is used to study the flow resistance law of u-shaped channels under rotating conditions based on similarity theory.The study compares three geometric models:real model,com...In this paper,the numerical simulation method is used to study the flow resistance law of u-shaped channels under rotating conditions based on similarity theory.The study compares three geometric models:real model,completely similar model and incompletely similar model for cooling typical U-shaped channels inside turbine rotating blades.The completely similar model is geometrically 4.8 times magnification of the real model,and the rotation radius ratio of the real model is 5.4 times that of the incomplete similar model.It is found that the friction factor of the completely similar model increases with the rotation number,and the difference varies from 6%to 38%.The friction factor of the model after incomplete similarity amplification decreases with the increase of rotation number,and the difference varies from-2%to-30%.The friction factor of the laboratory imperfectly similar amplification model combined the effects of the above two laws,and the predicted difference was within 12%.This study provides a theoretical basis for subsequent experiments related to flow resistance.展开更多
Brittleness and ductility of shale are closely related to shale gas exploration and production. How to predict brittleness and ductility of shale is one of the key issues in the study of shale gas preservation and hyd...Brittleness and ductility of shale are closely related to shale gas exploration and production. How to predict brittleness and ductility of shale is one of the key issues in the study of shale gas preservation and hydraulic fracturing treatments. The magnitude of shale brittleness was often determined by brittle mineral content(for example, quartz and feldspars) in shale gas exploration.However, the shale brittleness is also controlled by burial depth. Shale brittle/ductile properties such as brittle, semibrittle and ductile can mutually transform with burial depth variation. We established a work flow of determining the burial depth interval of brittle–ductile transition zone for a given shale. Two boundaries were employed to divide the burial depth interval of shale brittle/ductile properties. One is the bottom boundary of the brittle zone(BZ), and the other is the top boundary of the ductile zone(DZ). The brittle–ductile transition zone(BDTZ) is between them.The bottom boundary of BZ was determined by the overconsolidation ratio(OCR) threshold value combined with pre-consolidation stress which the shale experienced over geological time. The top boundary of DZ was determined based on the critical confining pressure of brittle–ductile transition. The OCR threshold value and the critical confining pressure were obtained from uniaxial strain andtriaxial compression tests. The BZ, DZ and BDTZ of the Lower Silurian Longmaxi shale in some representative shale gas exploration wells in eastern Sichuan and western Hubei areas were determined according to the above work flow. The results show that the BZ varies with the maximum burial depth and the DZ varies with the density of the overlying rocks except for the critical confining pressure.Moreover, the BDTZ determined by the above work flow is probably the best burial depth interval for marine shale gas exploration and production in Southern China. Shale located in the BDTZ is semi-brittle and is not prone to be severely naturally fractured but likely to respond w展开更多
Post-anthesis photoassimilation is very important for wheat （Triticum aestivum L.） grain filling. The aim of the present study was to map quantitative trait loci （QTL） for post-anthesis dry matter accumulation （...Post-anthesis photoassimilation is very important for wheat （Triticum aestivum L.） grain filling. The aim of the present study was to map quantitative trait loci （QTL） for post-anthesis dry matter accumulation （DMA）. A set of 120 doubled haploid （DH） lines, derived from winter wheat varieties Hanxuan 10 and Lumai 14, was grown under field conditions in two consecutive growing seasons during 2002-2004 in Beijing. Post-anthesis DMA per culm and related traits, including flag leaf greenness （FLG） and flag leaf weight （FLW; dry weight per flag leaf） at flowering, and grain weight per ear （GWE） were investigated. All traits segregated continuously in the DH population in both trials. The DMA was significantly and positively correlated with GWE, with the correlation coefficients being 0.79 and 0.66 in the 2002-2003 and 2003-2004 growing seasons （both P〈0.01）, suggesting the importance of DMA in grain filling. Further correlation analysis showed that FLW was more closely correlated with DMA and GWE than FLG in both growing seasons, indicating that FLW was more important than FLG in influencing DMA and GWE. In total, 30 QTLs for these four traits were mapped and distributed on 10 chromosomes. Phenotypic variations explained by an individual QTL were in the range 5.8%-21.3%, 5.9%-17.2%, 5.1%-18.1%, and 5.6%-16.2% for FLG, FLW, DMA, and GWE, respectively. Eight QTLs for DMA were detected, of which four （on chromosome arms 2AS, 4BL, 5AS, and 7AS） were linked with QTLs for GWE; two （on chromosome arms 5BL and 7BL） coincided with QTLs for FLW. These results may provide useful information for developing marker-assisted selection for the improvement of DMA.展开更多
Under long-term artificial selection, the domestic silkworm （Bombyx mori） has increased its silk yield tremendously in comparison with its wild progenitor, Bombyx mandarina. However, the molecular mechanism of silk ...Under long-term artificial selection, the domestic silkworm （Bombyx mori） has increased its silk yield tremendously in comparison with its wild progenitor, Bombyx mandarina. However, the molecular mechanism of silk yield increase is still unknown. Comparative analysis of long non-coding RNAs （lncRNAs） may provide some insights into understanding this phenotypic variation. In this study, using RNA sequencing technology data of silk gland in domestic and wild silkworms, we identified 599 lncRNAs in the silk gland of the silkworm. Compared with protein-coding genes, the silk gland lncRNA genes tend to have fewer exon numbers, shorter transcript length and lower GC-content. Moreover, we found that three lncRNA genes are significantly and differentially expressed between domestic and wild silkworms. The potential targets of two differentially expressed lncRNAs （DELs） （dw4sg_0040 and dw4sg_0483） and the expression-correlated genes with the two DELs are mainly enriched in the related processes of silk protein translation. This implies that these DELs may affect the phenotypic variation in silk yield between the domestic and wild silkworms through the post-transcriptional regulation of silk protein.展开更多
Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and ...Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device.Generally,various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation stability.Here,we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]acridine-7,9′-fluorene](SFDBA)to pack tightly to resist fluorescence decay caused by oxidation.In this case,the inert group of SFDBA acts as a“steric armor”,protecting the photosensitive group from being attacked by oxygen.Therefore,compared with the fluorescence quenching of SFDBA powder under 2 h of sunlight,SFDBA crystal can maintain its fluorescence emission for more than 8 h under the same conditions.Furthermore,the photoluminescence quantum yields(PLQYs)of the crystalline film is 327%higher than that of the amorphous film.It shows that the crystallization strategy is an effective method to resist oxidation.展开更多
Globally,most organic-rich shales are deposited with volcanic ash layers.Volcanic ash,a source for many sedimentary basins,can affect the sedimentary water environment,alter the primary productivity,and preserve the o...Globally,most organic-rich shales are deposited with volcanic ash layers.Volcanic ash,a source for many sedimentary basins,can affect the sedimentary water environment,alter the primary productivity,and preserve the organic matter(OM)through physical,chemical,and biological reactions.With an increasing number of breakthroughs in shale oil exploration in the Bohai Bay Basin in recent years,less attention has been paid to the crucial role of volcanic impact especially its influence on the OM enrichment and hydrocarbon formation.Here,we studied the petrology,mineralogy,and geochemical characteristics of the organic-rich shale in the upper submember of the fourth member(Es_(4)^(1))and the lower submember of the third member(Es_(3)^(3))of the Shahejie Formation,aiming to better understand the volcanic impact on organic-rich shale formation.Our results show that total organic carbon is higher in the upper shale intervals rich in volcanic ash with enriched light rare earth elements and moderate Eu anomalies.This indicates that volcanism promoted OM formation before or after the eruption.The positive correlation between Eu/Eu*and Post-Archean Australian Shale indicates hydrothermal activity before the volcanic eruption.The plane graph of the hydrocarbon-generating intensity(S1+S2)suggests that the heat released by volcanism promoted hydrocarbon generation.Meanwhile,the nutrients carried by volcanic ash promoted biological blooms during Es_(4)^(1 )and Es_(3)^(3) deposition,yielding a high primary productivity.Biological blooms consume large amounts of oxygen and form anoxic environments conducive to the burial and preservation of OM.Therefore,this study helps to further understand the organic-inorganic interactions caused by typical geological events and provides a guide for the next step of shale oil exploration and development in other lacustrine basins in China.展开更多
Shape persistent conformations reduce the complexity of polymer materials. Herein, we propose a concept on the nanopolymer that is a nanoscale polymer chain with the repeat units of nanomonomers, In this article, a so...Shape persistent conformations reduce the complexity of polymer materials. Herein, we propose a concept on the nanopolymer that is a nanoscale polymer chain with the repeat units of nanomonomers, In this article, a soluble organic nanopolymer of wide bandgap semiconductors was synthesized by the Yamamoto polymerization of nanogrid monomer as the repeat units with the rectangle size of -1.7 nm × 1.2 nm. The alkyl side chain substituent at 9-position of fluorenes guarantees the polygrid with excellent solubility. Tetrafluorenes in the conjugation-interrupted backbones of polygrid acts as the active light-emitting centers without obvious green band in the fluorescence spectra of the films after 10 h annealing at 180 ℃, indicating this nanopolymer exhibits excellent spectral stability. Such soluble nanopolymers will be the fifth- generation of macromolecular materials with a potential character of overall performance improvement.展开更多
Terahertz(THz) pulse imaging can be used for biomedicine, material, and food security. However, image quality is lower attributed to the THz time-domain spectroscopy system. Such as, noises and lower space resolution ...Terahertz(THz) pulse imaging can be used for biomedicine, material, and food security. However, image quality is lower attributed to the THz time-domain spectroscopy system. Such as, noises and lower space resolution are presented in some THz images. To improve the THz image quality, we proposed a novel method which combining the simulation evolutionary with the symmetric fourth order partial differential equation. The image edge is first detected by using the simulation evolutionary. Then the symmetric fourth order partial differential equation(PDE) is applied on the non-edge image for noise reduction. Finally, the de-noise image is combined with the edge image obtained from the edge detection step. Experiments on four different THz images prove that the proposed method can preserve the edge information during noise reduction.展开更多
Rare attention has been paid to the comparison between a monomer and its corresponding polymer in terms of the optoelectronic characteristics. In this article, a model H-shaped molecule and its corresponding polymer, ...Rare attention has been paid to the comparison between a monomer and its corresponding polymer in terms of the optoelectronic characteristics. In this article, a model H-shaped molecule and its corresponding polymer, both of which exhibited similar properties including blue emission and solution processing, were designed and synthesized. Optoelectronic properties and various kinds of stability features, including the thermostabilities, spectral stabilities and amplified spontaneous emission characteristic of the monomer and polymer were investigated. In general, the corresponding polymer PH exhibited similar optoelectronic properties but deteriorated stabilities compared with its H-shaped monomer H-1 probably owing to the similar chemical structure but the wider molecular weight distribution and metal catalyst residue. Importantly, monomer H-1 displayed a comparable ASE threshold value with its polymer PH,suggesting that H-shaped fluorene-based small molecules may be more promising optical gain media in solid state amplifers and lasers.展开更多
In this paper, the author presents an overview of the development of CALL and understanding of CALL research in recent years; and then, indicates the trend of CALL research-AR and the research on AR-could be interpret...In this paper, the author presents an overview of the development of CALL and understanding of CALL research in recent years; and then, indicates the trend of CALL research-AR and the research on AR-could be interpreted as the research framework of CALL in China by introducing the four elements of AR-involvement, improvement, systematization and publicity.展开更多
基金Beijing Nova Program (No. 20220484129)National Natural Science Foundation of China (No.52376042)+1 种基金Advanced Aerodynamic Innovation Workstation (Grant No. HKCX2022-01-07)National Science and Technology Major Project (Grant No. J2019-II-0022-0043)。
文摘With the development of aero-engines, the turbine inlet temperature continues to rise. In order to ensure the safety and reliability of the turbine blades, cooling structures must be set inside turbine blades to cool them. Heat transfer coefficient and flow resistance are the key parameters to measure the cooling characteristics of internal cooling structures. In this paper, the characteristics of flow resistance in a rotating ribbed channel is presented numerical simulation under different rib spacings, rib angles, and thermal boundary conditions. The results show that, separation and reattachment of fluid between ribs is the key effect of rib spacing on flow resistance. The flow resistance is small when the rib spacing is small, because it's difficult for the fluid to form reattachment between the ribs. With the increase of rib spacing, the reattachment phenomenon is more obvious and the flow resistance increases accordingly. In general,p: e=10 channel has the maximum flow resistance. Secondary flow caused by the ribs is the key factor affecting the flow resistance characteristics with different rib angles. The secondary flow interacts with the main flow and causes flow loss through mixing, thus affecting the flow resistance of the channel. Under static condition, the flow resistance of 60°ribbed channel is the largest. The flow resistance of channel was affected by the temperature rise ratio also. And with the increase of the Ro, the temperature rise ratio has a more obvious effect on the flow resistance of the ribbed channel.When Ro=0.45, the flow resistance of the channel with a temperature rise ratio of 0.4 is 2.4 times that of the channel without temperature rise, while when Ro=0.3, it is 1.6 times, and when Ro=0.15, it is 1.2 times.
基金National Natural Science Foundation of China(51906008)。
文摘In this paper,the flow and heat transfer characteristics in U-shaped channel with three different turn shapes are studied.The rotation number ranges from 0~0.251,Reynolds number are 11500,23000,34500,respectively.The results show that the flow separation and reattachment in the turning section are the key factors affecting the local heat transfer and pressure loss of U-shaped channel.The square turn will generate corner vortices at the outside of the turning section,and the size of the inner separation vortex and reattachment vortex is larger than that of the other two turn shapes.The existence of vortex system will increase the mixing and enhance heat transfer,but increase the pressure loss,so its relative Nusselt number and pressure loss are the largest.There are corner vortices on the outside of the turning section of the channel with a inner circle turn and outer square turn,but the arc-shaped inner edge makes its separation delay and the separation vortex decrease,and the size of the reattachment vortex also decreases.The arc shaped outer edge of the channel with circle turn in both inner and outer further inhibits the generation of corner vortices,so its relative Nusselt number and pressure loss are the lowest.Rotation will cause the fluid to deflect under the influence of Coriolis force,strengthen the heat transfer on the trailing surface of radial outflow and the leading surface of radial internal flow,and generate secondary flow and separation vortex in the turning section,resulting in the change of vortex structure in the turning section.With the increase of rotation number,the Nusselt number of the three types of turning section structures increases.The thermal performance factor of the three channels increases with the increase of rotating speed,and the channel with a inner circle turn and outer square turn is the highest,which is 9.6%higher than the channel with circle turn in both inner and outer on average,and 17.8%higher than the channel with square turn in both inner and outer.
基金National Natural Science Foundation of China(52005074)Natural Science Foundation of Liaoning Province(2022-MS-135)。
文摘In this paper,the numerical simulation method is used to study the flow resistance law of u-shaped channels under rotating conditions based on similarity theory.The study compares three geometric models:real model,completely similar model and incompletely similar model for cooling typical U-shaped channels inside turbine rotating blades.The completely similar model is geometrically 4.8 times magnification of the real model,and the rotation radius ratio of the real model is 5.4 times that of the incomplete similar model.It is found that the friction factor of the completely similar model increases with the rotation number,and the difference varies from 6%to 38%.The friction factor of the model after incomplete similarity amplification decreases with the increase of rotation number,and the difference varies from-2%to-30%.The friction factor of the laboratory imperfectly similar amplification model combined the effects of the above two laws,and the predicted difference was within 12%.This study provides a theoretical basis for subsequent experiments related to flow resistance.
基金financially supported by the National Science&Technology Special Project(Grant No.2016ZX05061001)
文摘Brittleness and ductility of shale are closely related to shale gas exploration and production. How to predict brittleness and ductility of shale is one of the key issues in the study of shale gas preservation and hydraulic fracturing treatments. The magnitude of shale brittleness was often determined by brittle mineral content(for example, quartz and feldspars) in shale gas exploration.However, the shale brittleness is also controlled by burial depth. Shale brittle/ductile properties such as brittle, semibrittle and ductile can mutually transform with burial depth variation. We established a work flow of determining the burial depth interval of brittle–ductile transition zone for a given shale. Two boundaries were employed to divide the burial depth interval of shale brittle/ductile properties. One is the bottom boundary of the brittle zone(BZ), and the other is the top boundary of the ductile zone(DZ). The brittle–ductile transition zone(BDTZ) is between them.The bottom boundary of BZ was determined by the overconsolidation ratio(OCR) threshold value combined with pre-consolidation stress which the shale experienced over geological time. The top boundary of DZ was determined based on the critical confining pressure of brittle–ductile transition. The OCR threshold value and the critical confining pressure were obtained from uniaxial strain andtriaxial compression tests. The BZ, DZ and BDTZ of the Lower Silurian Longmaxi shale in some representative shale gas exploration wells in eastern Sichuan and western Hubei areas were determined according to the above work flow. The results show that the BZ varies with the maximum burial depth and the DZ varies with the density of the overlying rocks except for the critical confining pressure.Moreover, the BDTZ determined by the above work flow is probably the best burial depth interval for marine shale gas exploration and production in Southern China. Shale located in the BDTZ is semi-brittle and is not prone to be severely naturally fractured but likely to respond w
基金Supported by the National Natural Science Foundation of China (30330390 and 30390083)the State Key Basic Research and Development Plan of China(2004CB117200)+2 种基金the Hi-Tech Re- search and Development(863) Program of China(2003AA207080)the Special Project for Adjusting Agricultural Production Structure from the Ministry of Agriculture of China(05-02-01A)the Knowledge Innovation Program of the Chinese Academy of Sciences(KSCX2-SW-304)
文摘Post-anthesis photoassimilation is very important for wheat （Triticum aestivum L.） grain filling. The aim of the present study was to map quantitative trait loci （QTL） for post-anthesis dry matter accumulation （DMA）. A set of 120 doubled haploid （DH） lines, derived from winter wheat varieties Hanxuan 10 and Lumai 14, was grown under field conditions in two consecutive growing seasons during 2002-2004 in Beijing. Post-anthesis DMA per culm and related traits, including flag leaf greenness （FLG） and flag leaf weight （FLW; dry weight per flag leaf） at flowering, and grain weight per ear （GWE） were investigated. All traits segregated continuously in the DH population in both trials. The DMA was significantly and positively correlated with GWE, with the correlation coefficients being 0.79 and 0.66 in the 2002-2003 and 2003-2004 growing seasons （both P〈0.01）, suggesting the importance of DMA in grain filling. Further correlation analysis showed that FLW was more closely correlated with DMA and GWE than FLG in both growing seasons, indicating that FLW was more important than FLG in influencing DMA and GWE. In total, 30 QTLs for these four traits were mapped and distributed on 10 chromosomes. Phenotypic variations explained by an individual QTL were in the range 5.8%-21.3%, 5.9%-17.2%, 5.1%-18.1%, and 5.6%-16.2% for FLG, FLW, DMA, and GWE, respectively. Eight QTLs for DMA were detected, of which four （on chromosome arms 2AS, 4BL, 5AS, and 7AS） were linked with QTLs for GWE; two （on chromosome arms 5BL and 7BL） coincided with QTLs for FLW. These results may provide useful information for developing marker-assisted selection for the improvement of DMA.
文摘Under long-term artificial selection, the domestic silkworm （Bombyx mori） has increased its silk yield tremendously in comparison with its wild progenitor, Bombyx mandarina. However, the molecular mechanism of silk yield increase is still unknown. Comparative analysis of long non-coding RNAs （lncRNAs） may provide some insights into understanding this phenotypic variation. In this study, using RNA sequencing technology data of silk gland in domestic and wild silkworms, we identified 599 lncRNAs in the silk gland of the silkworm. Compared with protein-coding genes, the silk gland lncRNA genes tend to have fewer exon numbers, shorter transcript length and lower GC-content. Moreover, we found that three lncRNA genes are significantly and differentially expressed between domestic and wild silkworms. The potential targets of two differentially expressed lncRNAs （DELs） （dw4sg_0040 and dw4sg_0483） and the expression-correlated genes with the two DELs are mainly enriched in the related processes of silk protein translation. This implies that these DELs may affect the phenotypic variation in silk yield between the domestic and wild silkworms through the post-transcriptional regulation of silk protein.
基金supported by the Natural Science Foundation of Nanjing University of Posts and Telecommunications(NY222157,NY221085)State Key Laboratory of Organic Electronics and Information Display(GZR2022010008)+5 种基金Key Laboratory of Low-dimensional Materials Chemistry of Jiangsu Province(JSKC20022)General Program of China Postdoctoral Science Foundation(2022M711684)General Program of Basic Science(Natural Science)of Colleges and Universities of Jiangsu Province(22KJB430036)National Overseas Study Fund(202008320051)National Key Laboratory(2009DS690095)the National Natural Science Foundation of China(62288102).
文摘Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device.Generally,various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation stability.Here,we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]acridine-7,9′-fluorene](SFDBA)to pack tightly to resist fluorescence decay caused by oxidation.In this case,the inert group of SFDBA acts as a“steric armor”,protecting the photosensitive group from being attacked by oxygen.Therefore,compared with the fluorescence quenching of SFDBA powder under 2 h of sunlight,SFDBA crystal can maintain its fluorescence emission for more than 8 h under the same conditions.Furthermore,the photoluminescence quantum yields(PLQYs)of the crystalline film is 327%higher than that of the amorphous film.It shows that the crystallization strategy is an effective method to resist oxidation.
基金the financial support from the National Natural Science Foundation of China(42172151,42090025,41811530094,and 41625009)the China Postdoctoral Science Foundation(2021M690204)the National Key Research and Development Program(2019YFA0708504&2023YFF0806200)。
文摘Globally,most organic-rich shales are deposited with volcanic ash layers.Volcanic ash,a source for many sedimentary basins,can affect the sedimentary water environment,alter the primary productivity,and preserve the organic matter(OM)through physical,chemical,and biological reactions.With an increasing number of breakthroughs in shale oil exploration in the Bohai Bay Basin in recent years,less attention has been paid to the crucial role of volcanic impact especially its influence on the OM enrichment and hydrocarbon formation.Here,we studied the petrology,mineralogy,and geochemical characteristics of the organic-rich shale in the upper submember of the fourth member(Es_(4)^(1))and the lower submember of the third member(Es_(3)^(3))of the Shahejie Formation,aiming to better understand the volcanic impact on organic-rich shale formation.Our results show that total organic carbon is higher in the upper shale intervals rich in volcanic ash with enriched light rare earth elements and moderate Eu anomalies.This indicates that volcanism promoted OM formation before or after the eruption.The positive correlation between Eu/Eu*and Post-Archean Australian Shale indicates hydrothermal activity before the volcanic eruption.The plane graph of the hydrocarbon-generating intensity(S1+S2)suggests that the heat released by volcanism promoted hydrocarbon generation.Meanwhile,the nutrients carried by volcanic ash promoted biological blooms during Es_(4)^(1 )and Es_(3)^(3) deposition,yielding a high primary productivity.Biological blooms consume large amounts of oxygen and form anoxic environments conducive to the burial and preservation of OM.Therefore,this study helps to further understand the organic-inorganic interactions caused by typical geological events and provides a guide for the next step of shale oil exploration and development in other lacustrine basins in China.
基金partially financially supported by the National Natural Science Funds for Excellent Young Scholar(No.21322402)the National Natural Science Foundation of China(Nos.21274064,21504041,21504047 and 61136003)+4 种基金Excellent Science and Technology Innovation Team of Jiangsu Higher Education Institutions(2013)Synergetic Innovation Center for Organic Electronics and Information Displays,the Natural Science Foundation of Jiangsu Province(Nos.BK20150834 and BM2012010)Open Project from State Key Laboratory of Supramolecular Structure and Materials at Jilin University(No.klssm201612)Project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Nanjing University of Posts and Telecommunications Scientific Foundation(NUPTSF)(No.NY214179)
文摘Shape persistent conformations reduce the complexity of polymer materials. Herein, we propose a concept on the nanopolymer that is a nanoscale polymer chain with the repeat units of nanomonomers, In this article, a soluble organic nanopolymer of wide bandgap semiconductors was synthesized by the Yamamoto polymerization of nanogrid monomer as the repeat units with the rectangle size of -1.7 nm × 1.2 nm. The alkyl side chain substituent at 9-position of fluorenes guarantees the polygrid with excellent solubility. Tetrafluorenes in the conjugation-interrupted backbones of polygrid acts as the active light-emitting centers without obvious green band in the fluorescence spectra of the films after 10 h annealing at 180 ℃, indicating this nanopolymer exhibits excellent spectral stability. Such soluble nanopolymers will be the fifth- generation of macromolecular materials with a potential character of overall performance improvement.
基金This work has been supported by the Hunan Provincial Natural Science Foundation Program(No.2020JJ4327)the Department of Education Science Research General Project in Hunan Province(No.18C1063)+2 种基金the Featured Application Discipline in Hunan University of Science and Engineering(Computer Science and Technology)the Scientific Research Projects in Colleges and Universities(No.2019KTSCX165)the Shaoguan Science and Technology Department Project(No.2019sn066)。
文摘Terahertz(THz) pulse imaging can be used for biomedicine, material, and food security. However, image quality is lower attributed to the THz time-domain spectroscopy system. Such as, noises and lower space resolution are presented in some THz images. To improve the THz image quality, we proposed a novel method which combining the simulation evolutionary with the symmetric fourth order partial differential equation. The image edge is first detected by using the simulation evolutionary. Then the symmetric fourth order partial differential equation(PDE) is applied on the non-edge image for noise reduction. Finally, the de-noise image is combined with the edge image obtained from the edge detection step. Experiments on four different THz images prove that the proposed method can preserve the edge information during noise reduction.
基金financially supported by the National Natural Science Foundation of China (Nos. 21504047, 21774061)the Six Peak Talents Foundation of Jiangsu Province (No. XCL-CXTD009)+1 种基金Natural Science Foundation of Jiangsu Province (No. BK20150834)Synergetic Innovation Center for Organic Electronics and Information Displays
文摘Rare attention has been paid to the comparison between a monomer and its corresponding polymer in terms of the optoelectronic characteristics. In this article, a model H-shaped molecule and its corresponding polymer, both of which exhibited similar properties including blue emission and solution processing, were designed and synthesized. Optoelectronic properties and various kinds of stability features, including the thermostabilities, spectral stabilities and amplified spontaneous emission characteristic of the monomer and polymer were investigated. In general, the corresponding polymer PH exhibited similar optoelectronic properties but deteriorated stabilities compared with its H-shaped monomer H-1 probably owing to the similar chemical structure but the wider molecular weight distribution and metal catalyst residue. Importantly, monomer H-1 displayed a comparable ASE threshold value with its polymer PH,suggesting that H-shaped fluorene-based small molecules may be more promising optical gain media in solid state amplifers and lasers.
文摘In this paper, the author presents an overview of the development of CALL and understanding of CALL research in recent years; and then, indicates the trend of CALL research-AR and the research on AR-could be interpreted as the research framework of CALL in China by introducing the four elements of AR-involvement, improvement, systematization and publicity.
