In accordance with the confusion on classification of source rocks, the authors raised a source rock classification for its enriched and dispersed organic matter types based on both Alpern’s idea and maceral genesis/...In accordance with the confusion on classification of source rocks, the authors raised a source rock classification for its enriched and dispersed organic matter types based on both Alpern’s idea and maceral genesis/composition. The determined rock type is roughly similar to palynofacies of Combaz , whereas it is "rock maceral facies (for coal viz. coal facies)" in strictly speaking. Therefore, it is necessary to use the organic ingredients classification proposed by the authors so that it can be used for both maceral analysis and environment research . This source rock classification not only shows sedimentology and diagenetic changes but also acquires organic matter type even if hydrocarbon potential derived from maceral’s geochemical parameters. So, it is considered as genetic classification. The "rock maceral facies" may be transformed to sedimentary organic facies , which is used as quantitative evaluation means if research being perfect.Now, there are many models in terms of structure either for coal or for kerogen. In our opinion, whatever coal or kerogen ought be polymer, then we follow Combaz’s thought and study structure of amorphous kerogens which are accordance with genetic mechanism showing biochemical and geochemical process perfectly. Here, we use the time of flight secondary ion mass spectrometry (TOFSIMS) to expand Combaz’s models from three to five. They are also models for coal.展开更多
In this paper,we study the epidemic model of respiratory syncytial virus SIRS with age structure.Firstly,the basic reproduction number R_(0) of the model is calculated and the positivity and ultimate boundedness of th...In this paper,we study the epidemic model of respiratory syncytial virus SIRS with age structure.Firstly,the basic reproduction number R_(0) of the model is calculated and the positivity and ultimate boundedness of the solution to the model under initial conditions are proven.Secondly,it is proven that when R_(0)<1,the disease-free equilibrium is locally and globally asymptotically stable;and when R_(0)>1,the disease is uniformly persistent and there is at least a positive equilibrium.Finally,the effectiveness of the theoretical results is demonstrated by numerical simulation,and the impact of vaccination on disease transmission is predicted.展开更多
As a trypsin-like serine protease, Urokinase-type plasminogen activator （uPA） plays a key role in a range of biological processes including plasminogen activation, angiogenesis, wound healing, tissue remodeling, tum...As a trypsin-like serine protease, Urokinase-type plasminogen activator （uPA） plays a key role in a range of biological processes including plasminogen activation, angiogenesis, wound healing, tissue remodeling, tumor growth and tumor metastasis, uPA is shown as the most validated marker for prognosis of breast cancer. Inhibitors of uPA may then be useful in the treatment of cancer by retarding tumor growth and metastasis. Most current uPA inhibitors employ a highly basic group （amidine or guanidine group） to target the primary specific pocket of uPA active site, which leads to poor oral bioavailability. Here, a uPA inhibitor with weak basic P1 group, 2-（2-amino- benzothiazole-6-carboxamido）acetic acid （ABTCA）, was synthesized and reported here. In addition, we also determined the crystal structure of ABTCA in complex with uPA. The structural information will be useful for further improvements of potency and selectivity of this promising new type ofuPA inhibitors.展开更多
Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+...Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant diagrams distribution areas of the characteristic values of ore-free melt and those of ore-forming melt are overlapped in different degrees, which possibly indicates that not all the magmas have mineralizing ability. It can be well distinguished whether basic-ultrabasic rocks are favourable to Cu or Au mineralization or they are just ore-free rocks by analysing integrated diagrams of the characteristic values of the magmatic melt structure.展开更多
Seeking for innovative structures with higher mechanical performance is a continuous target in railway vehicle crashworthiness design.In the present study,three types of hexagonal reinforced honeycomb-like structures ...Seeking for innovative structures with higher mechanical performance is a continuous target in railway vehicle crashworthiness design.In the present study,three types of hexagonal reinforced honeycomb-like structures were developed and analyzed subjected to out-of-plane compression,namely triangular honeycomb(TH),double honeycomb(DH)and full inside honeycomb(FH).Theoretical formulas of average force and specific energy absorption(SEA)were constructed based on the energy minimization principle.To validate,corresponding numerical simulations were carried out by explicit finite element method.Good agreement has been observed between them.The results show that all these honeycomb-like structures maintain the same collapsed stages as conventional honeycomb;cell reinforcement can significantly promote the performance,both in the average force and SEA;full inside honeycomb performs better than the general,triangular and double schemes in average force;meanwhile,its SEA is close to that of double scheme;toroidal surface can dissipate higher plastic energy,so more toroidal surfaces should be considered in design of thin-walled structure.These achievements pave a way for designing high-performance cellular energy absorption devices.展开更多
The existing research for unsteady flow field and the corresponding flow induced vibration analysis of centrifugal pump are mainly carried out respectively without considering the interaction between fluid and structu...The existing research for unsteady flow field and the corresponding flow induced vibration analysis of centrifugal pump are mainly carried out respectively without considering the interaction between fluid and structure.The ignorance of fluid structure interaction(FSI)means that the energy transfer between fluid and structure is neglected.To some extent,the accuracy and reliability of unsteady flow and rotor deflection analysis should be affected by this interaction mechanism.In this paper,a combined calculation between two executables for turbulent flow and vibrating structure was established using two-way coupling method to study the effect of FSI.Pressure distributions,radial forces,rotor deflection and equivalent stress are analyzed.The results show that the FSI effect to pressure distribution in flow field is complex.The pressure distribution is affected not only around impeller outlet where different variation trends of pressure values with and without FSI appear according to different relative positions between blade and cutwater,but also in the diffusion section of volute.Variation trends of peak values of radial force amplitude calculated with and without FSI are nearly same under high flow rate and designed conditions while the peak value with FSI is slightly smaller,and differently,the peak value with FSI is larger with low flow rate.In addition,the effect of FSI on the angle of radial force is quite complex,especially under 0.5Q condition.Fluctuation of radial deflection of the rotor has obvious four periods,of which the extent is relatively small under design condition and is relatively large under off-design condition.Finally,fluctuations of equivalent stress with time are obvious under different conditions,and stress value is small.The proposed research establishes the FSI calculation method for centrifugal pump analysis,and ensures the existing affect by fluid structure interaction.展开更多
In this paper, the X-ray nondestructive test method of small defects in precision weldments with complex structure was presented. To resolve the difficulty of defect segmentation in variable grey image, the image proc...In this paper, the X-ray nondestructive test method of small defects in precision weldments with complex structure was presented. To resolve the difficulty of defect segmentation in variable grey image, the image processing based on Visual Basic programming method was adopted. The methods of automatic contrast and partial grey stretch were used to enhance the X-ray detection image which has relatively low contrast, then automatic threshold method was carried out to segment the two high intensity zones, and weld zones which contain the small defects was extracted. Smoothing and sharpen processing were proceeded on the extracted weld zones, and small defects in X-ray detection image of weldments with complex structure were segmented by using the method of background subtraction in the end. The effects of raster were eliminated, and because of that the image processing was only proceeded on the extracted weld zones, the calculated speed using the above provided algorithm was improved.展开更多
A new complex, [Ni（L）2]·2（H2O） I （HL = 2-iminomethyl-6-methoxyphenol）, has been synthesized and structurally determined. The crystal belongs to the trigonal system, space group R3- with a = 1.9341 （3）, b ...A new complex, [Ni（L）2]·2（H2O） I （HL = 2-iminomethyl-6-methoxyphenol）, has been synthesized and structurally determined. The crystal belongs to the trigonal system, space group R3- with a = 1.9341 （3）, b = 1.9341 （3）, C = 1.2048（2） nm, V = 3.9029（11） nm^3, Mr = 395.05, Z = 9, Dc = 1.513 g·cm^-3, F（000） = 1854,μ= 1.153 mm^-1 and S = 1.014. Each Ni^Ⅱ atom is four-coordinated by two N and two O atoms from two different L anions to give a slightly distorted square-plane geometry. The complex forms a 3-D network structure through N-H...O and O-H...O hydrogen bonds containing an interesting six-membered water ring.展开更多
In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence....In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence. Based on these new BCs we propose a type of basic-structural-units （BSUs） and investigate the optical transmission of the one-dimensional （1D） superlattices composed of these BSUs. It is found that if the substrates of the 1D BSU superlattices are certain, the optical transmission at the central wavelength （CW） will be determined completely by the number and the type of BSUs and has nothing to do with the marshalling sequence. In particular, if the substrates are identical, the numbers of different types of BSUs are all the same and the middle two elements of BSUs constitute a cycle, then no matter whether the system is periodic, or quasiperiodic, or aperiodic, or unordered, or even random, it will be transparent at the CW. The conclusion is confirmed by the numerical results. Similar to the even layers of neighbourhood identical elements in TCD method, such a kind of optical BSU subsystem can also be decimated from the chain in the process of transmission investigation. There would be a potential application in the designing of some interesting optical devices.展开更多
The implementation of structural readjustment is the strategic consideration to deepening reforms in the Chinese Academy of Sciences (CAS). and the readjustment of basic research is one of its major contents. By analy...The implementation of structural readjustment is the strategic consideration to deepening reforms in the Chinese Academy of Sciences (CAS). and the readjustment of basic research is one of its major contents. By analyzing the historical roles, status quo and existing problems in CAS basic research, this article points out the needs for structural readjustment and puts forward some suggestions on this point in basic research in the context of the possible models of basic structural units for basic research and their ways of combination as well as the implementing procedures of structural readjustment.展开更多
The importance of epidemiology in our life has stimulated researchers to extend the classic Susceptibles-Infectives-Removed (SIR) model to sophisticated models by including more factors in order to give detailed trans...The importance of epidemiology in our life has stimulated researchers to extend the classic Susceptibles-Infectives-Removed (SIR) model to sophisticated models by including more factors in order to give detailed transmission dynamics of epidemic diseases. However, the integration of the quarantine policy and age-structure is less addressed. In this work we propose an age-structured MSIQR (temporarily immune-susceptibles-infectives-quarantined-removed) model to study the impact of quarantine policies on the spread of epidemic diseases. Specifically, we investigate the existence of steady state solutions and stability property of the proposed model. The derived explicit expression of the basic reproductive number shows that the disease-free equilibrium is globally asymptotically stable if, and that the unique endemic equilibrium exists if. In addition, the stability conditions of the endemic equilibrium are derived.展开更多
This text uses the regional geological investigation data and the remote sensing image data of earth-satellite remote sensing to synthetically analyze the structural system of Taiwan region of China. Authors detection...This text uses the regional geological investigation data and the remote sensing image data of earth-satellite remote sensing to synthetically analyze the structural system of Taiwan region of China. Authors detection-marked and assurance-marked and divided 5 kinds of structural system of the Taiwan region: (1) the wreath-shaped structural system, (2) the N-N-E oriented structural system, (3) the S-N oriented structural system, (4) the N-E oriented structural system, (5) the arc-shaped structural system. Combination of the texture faces and associated method were adopted to recover and reconstruct the structural evolution sequences and the formation periods. In this paper, problems such as the development process in geology etc. are also discussed, contributing new information to research the structural field of the East Asia and its tectonic plate movements and structural actions inside the land plate .展开更多
This paper briefly introduces the systemic structure of Vocational English series--Basic English, and puts forwards the four key compiling principles, namely, system, cognition, practicality and interest.
基金National Natural Science Foundation of China(4 9672 13 1)
文摘In accordance with the confusion on classification of source rocks, the authors raised a source rock classification for its enriched and dispersed organic matter types based on both Alpern’s idea and maceral genesis/composition. The determined rock type is roughly similar to palynofacies of Combaz , whereas it is "rock maceral facies (for coal viz. coal facies)" in strictly speaking. Therefore, it is necessary to use the organic ingredients classification proposed by the authors so that it can be used for both maceral analysis and environment research . This source rock classification not only shows sedimentology and diagenetic changes but also acquires organic matter type even if hydrocarbon potential derived from maceral’s geochemical parameters. So, it is considered as genetic classification. The "rock maceral facies" may be transformed to sedimentary organic facies , which is used as quantitative evaluation means if research being perfect.Now, there are many models in terms of structure either for coal or for kerogen. In our opinion, whatever coal or kerogen ought be polymer, then we follow Combaz’s thought and study structure of amorphous kerogens which are accordance with genetic mechanism showing biochemical and geochemical process perfectly. Here, we use the time of flight secondary ion mass spectrometry (TOFSIMS) to expand Combaz’s models from three to five. They are also models for coal.
基金supported by the Natural Science Foundation of Xinjiang(No.2022D01E41)the National Natural Science Foundation of China(No.12261087)the Open Project of Key Laboratory of Applied Mathematics of Xinjiang Autonomous Region(No.2021D04014)。
文摘In this paper,we study the epidemic model of respiratory syncytial virus SIRS with age structure.Firstly,the basic reproduction number R_(0) of the model is calculated and the positivity and ultimate boundedness of the solution to the model under initial conditions are proven.Secondly,it is proven that when R_(0)<1,the disease-free equilibrium is locally and globally asymptotically stable;and when R_(0)>1,the disease is uniformly persistent and there is at least a positive equilibrium.Finally,the effectiveness of the theoretical results is demonstrated by numerical simulation,and the impact of vaccination on disease transmission is predicted.
基金supported by the National Natural Foundation of China (No.31161130356)Foundation of Fujian Provincial Education Department (No.JA11020)Foundation of Fuzhou University (No.2010-XQ-06)
文摘As a trypsin-like serine protease, Urokinase-type plasminogen activator （uPA） plays a key role in a range of biological processes including plasminogen activation, angiogenesis, wound healing, tissue remodeling, tumor growth and tumor metastasis, uPA is shown as the most validated marker for prognosis of breast cancer. Inhibitors of uPA may then be useful in the treatment of cancer by retarding tumor growth and metastasis. Most current uPA inhibitors employ a highly basic group （amidine or guanidine group） to target the primary specific pocket of uPA active site, which leads to poor oral bioavailability. Here, a uPA inhibitor with weak basic P1 group, 2-（2-amino- benzothiazole-6-carboxamido）acetic acid （ABTCA）, was synthesized and reported here. In addition, we also determined the crystal structure of ABTCA in complex with uPA. The structural information will be useful for further improvements of potency and selectivity of this promising new type ofuPA inhibitors.
文摘Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant diagrams distribution areas of the characteristic values of ore-free melt and those of ore-forming melt are overlapped in different degrees, which possibly indicates that not all the magmas have mineralizing ability. It can be well distinguished whether basic-ultrabasic rocks are favourable to Cu or Au mineralization or they are just ore-free rocks by analysing integrated diagrams of the characteristic values of the magmatic melt structure.
基金Projects(51875581,51505502)supported by the National Natural Science Foundation of ChinaProjects(2017M620358,2018T110707)supported by China Postdoctoral Science FoundationProject(kq1905057)supported by the Training Program for Excellent Young Innovators of Changsha,China
文摘Seeking for innovative structures with higher mechanical performance is a continuous target in railway vehicle crashworthiness design.In the present study,three types of hexagonal reinforced honeycomb-like structures were developed and analyzed subjected to out-of-plane compression,namely triangular honeycomb(TH),double honeycomb(DH)and full inside honeycomb(FH).Theoretical formulas of average force and specific energy absorption(SEA)were constructed based on the energy minimization principle.To validate,corresponding numerical simulations were carried out by explicit finite element method.Good agreement has been observed between them.The results show that all these honeycomb-like structures maintain the same collapsed stages as conventional honeycomb;cell reinforcement can significantly promote the performance,both in the average force and SEA;full inside honeycomb performs better than the general,triangular and double schemes in average force;meanwhile,its SEA is close to that of double scheme;toroidal surface can dissipate higher plastic energy,so more toroidal surfaces should be considered in design of thin-walled structure.These achievements pave a way for designing high-performance cellular energy absorption devices.
基金supported by National Outstanding Young Scientists Founds of China(Grant No.50825902)Jiangsu Provincial Innovative Scholars"Climbing"Project of China(Grant No.BK 2009006)+1 种基金National Natural Science Foundation of China(Grant No.50979034)Jiangsu Provincial Project for Innovative Postgraduates of China(Grant No.CX10B_262Z)
文摘The existing research for unsteady flow field and the corresponding flow induced vibration analysis of centrifugal pump are mainly carried out respectively without considering the interaction between fluid and structure.The ignorance of fluid structure interaction(FSI)means that the energy transfer between fluid and structure is neglected.To some extent,the accuracy and reliability of unsteady flow and rotor deflection analysis should be affected by this interaction mechanism.In this paper,a combined calculation between two executables for turbulent flow and vibrating structure was established using two-way coupling method to study the effect of FSI.Pressure distributions,radial forces,rotor deflection and equivalent stress are analyzed.The results show that the FSI effect to pressure distribution in flow field is complex.The pressure distribution is affected not only around impeller outlet where different variation trends of pressure values with and without FSI appear according to different relative positions between blade and cutwater,but also in the diffusion section of volute.Variation trends of peak values of radial force amplitude calculated with and without FSI are nearly same under high flow rate and designed conditions while the peak value with FSI is slightly smaller,and differently,the peak value with FSI is larger with low flow rate.In addition,the effect of FSI on the angle of radial force is quite complex,especially under 0.5Q condition.Fluctuation of radial deflection of the rotor has obvious four periods,of which the extent is relatively small under design condition and is relatively large under off-design condition.Finally,fluctuations of equivalent stress with time are obvious under different conditions,and stress value is small.The proposed research establishes the FSI calculation method for centrifugal pump analysis,and ensures the existing affect by fluid structure interaction.
文摘In this paper, the X-ray nondestructive test method of small defects in precision weldments with complex structure was presented. To resolve the difficulty of defect segmentation in variable grey image, the image processing based on Visual Basic programming method was adopted. The methods of automatic contrast and partial grey stretch were used to enhance the X-ray detection image which has relatively low contrast, then automatic threshold method was carried out to segment the two high intensity zones, and weld zones which contain the small defects was extracted. Smoothing and sharpen processing were proceeded on the extracted weld zones, and small defects in X-ray detection image of weldments with complex structure were segmented by using the method of background subtraction in the end. The effects of raster were eliminated, and because of that the image processing was only proceeded on the extracted weld zones, the calculated speed using the above provided algorithm was improved.
基金the Key Laboratory of Non-ferrous Metal Materials and New Processing Technology, Ministry of Education and the State Key Laboratory of Coordination Chemistry
文摘A new complex, [Ni（L）2]·2（H2O） I （HL = 2-iminomethyl-6-methoxyphenol）, has been synthesized and structurally determined. The crystal belongs to the trigonal system, space group R3- with a = 1.9341 （3）, b = 1.9341 （3）, C = 1.2048（2） nm, V = 3.9029（11） nm^3, Mr = 395.05, Z = 9, Dc = 1.513 g·cm^-3, F（000） = 1854,μ= 1.153 mm^-1 and S = 1.014. Each Ni^Ⅱ atom is four-coordinated by two N and two O atoms from two different L anions to give a slightly distorted square-plane geometry. The complex forms a 3-D network structure through N-H...O and O-H...O hydrogen bonds containing an interesting six-membered water ring.
基金supported by the National Natural Science Foundation of China (Grant No.10974061)the Program for Innovative Research Team of the Higher Education in Guangdong,China (Grant No.06CXTD005)
文摘In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence. Based on these new BCs we propose a type of basic-structural-units （BSUs） and investigate the optical transmission of the one-dimensional （1D） superlattices composed of these BSUs. It is found that if the substrates of the 1D BSU superlattices are certain, the optical transmission at the central wavelength （CW） will be determined completely by the number and the type of BSUs and has nothing to do with the marshalling sequence. In particular, if the substrates are identical, the numbers of different types of BSUs are all the same and the middle two elements of BSUs constitute a cycle, then no matter whether the system is periodic, or quasiperiodic, or aperiodic, or unordered, or even random, it will be transparent at the CW. The conclusion is confirmed by the numerical results. Similar to the even layers of neighbourhood identical elements in TCD method, such a kind of optical BSU subsystem can also be decimated from the chain in the process of transmission investigation. There would be a potential application in the designing of some interesting optical devices.
文摘The implementation of structural readjustment is the strategic consideration to deepening reforms in the Chinese Academy of Sciences (CAS). and the readjustment of basic research is one of its major contents. By analyzing the historical roles, status quo and existing problems in CAS basic research, this article points out the needs for structural readjustment and puts forward some suggestions on this point in basic research in the context of the possible models of basic structural units for basic research and their ways of combination as well as the implementing procedures of structural readjustment.
文摘The importance of epidemiology in our life has stimulated researchers to extend the classic Susceptibles-Infectives-Removed (SIR) model to sophisticated models by including more factors in order to give detailed transmission dynamics of epidemic diseases. However, the integration of the quarantine policy and age-structure is less addressed. In this work we propose an age-structured MSIQR (temporarily immune-susceptibles-infectives-quarantined-removed) model to study the impact of quarantine policies on the spread of epidemic diseases. Specifically, we investigate the existence of steady state solutions and stability property of the proposed model. The derived explicit expression of the basic reproductive number shows that the disease-free equilibrium is globally asymptotically stable if, and that the unique endemic equilibrium exists if. In addition, the stability conditions of the endemic equilibrium are derived.
基金Science Fund Itemof Hunan Normal University (serial number :260106612)
文摘This text uses the regional geological investigation data and the remote sensing image data of earth-satellite remote sensing to synthetically analyze the structural system of Taiwan region of China. Authors detection-marked and assurance-marked and divided 5 kinds of structural system of the Taiwan region: (1) the wreath-shaped structural system, (2) the N-N-E oriented structural system, (3) the S-N oriented structural system, (4) the N-E oriented structural system, (5) the arc-shaped structural system. Combination of the texture faces and associated method were adopted to recover and reconstruct the structural evolution sequences and the formation periods. In this paper, problems such as the development process in geology etc. are also discussed, contributing new information to research the structural field of the East Asia and its tectonic plate movements and structural actions inside the land plate .
文摘This paper briefly introduces the systemic structure of Vocational English series--Basic English, and puts forwards the four key compiling principles, namely, system, cognition, practicality and interest.
