Based on analysis of pore features and pore skeleton composition of shale,a“rigid elastic chimeric”pore skeleton model of shale gas reservoir was built.Pore deformation mechanisms leading to increase of shale porosi...Based on analysis of pore features and pore skeleton composition of shale,a“rigid elastic chimeric”pore skeleton model of shale gas reservoir was built.Pore deformation mechanisms leading to increase of shale porosity due to the pore skeleton deformation under overpressure were sorted out through analysis of stress on the shale pore and skeleton.After reviewing the difficulties and defects of existent porosity measurement methods,a dynamic deformed porosity measurement method was worked out and used to measure the porosity of overpressure Silurian Longmaxi Formation shale under real formation conditions in southern Sichuan Basin.The results show:(1)The shale reservoir is a mixture of inorganic rock particles and organic matter,which contains inorganic pores supported by rigid skeleton particles and organic pores supported by elastic-plastic particles,and thus has a special“rigid elastic chimeric”pore structure.(2)Under the action of formation overpressure,the inorganic pores have tiny changes that can be assumed that they don’t change in porosity,while the organic pores may have large deformation due to skeleton compression,leading to the increase of radius,connectivity and ultimately porosity of these pores.(3)The“dynamic”deformation porosity measurement method combining high injection pressure helium porosity measurement and kerosene porosity measurement method under ultra-high variable pressure can accurately measure porosity of unconnected micro-pores under normal pressure conditions,and also the porosity increment caused by plastic skeleton compression deformation.(4)The pore deformation mechanism of shale may result in the"abnormal"phenomenon that the shale under formation conditions has higher porosity than that under normal pressure,so the overpressure shale reservoir is not necessarily“ultra-low in porosity”,and can have porosity over 10%.Application of this method in Well L210 in southern Sichuan has confirmed its practicality and reliability.展开更多
目的·建立一种定量检测唐氏综合征嵌合体小鼠各脏器嵌合情况的方法,并初步探究其不同器官中的嵌合规律。方法·分别针对唐氏综合征模型Tc1小鼠细胞(三体细胞)内人源21号染色体(记为Hsa21)上SIM2基因和小鼠15号染色体(记为Mmu15...目的·建立一种定量检测唐氏综合征嵌合体小鼠各脏器嵌合情况的方法,并初步探究其不同器官中的嵌合规律。方法·分别针对唐氏综合征模型Tc1小鼠细胞(三体细胞)内人源21号染色体(记为Hsa21)上SIM2基因和小鼠15号染色体(记为Mmu15)上Derl1基因设计引物,采用实时荧光定量PCR(quantitative real time PCR,qPCR)技术对SIM2和Derl1进行检测来反映Hsa21和Mmu15的比例,并以此计算嵌合体小鼠各器官中Tc1小鼠细胞的嵌合占比。结果·所鉴定的小鼠中有3只为嵌合体小鼠。该3只小鼠心脏组织Tc1小鼠细胞嵌合率分别为8.98%、21.71%和57.70%,小脑组织分别为5.62%、20.17%和40.43%,大脑组织分别为8.48%、15.35%和20.45%,肝脏组织分别为2.66%、6.50%和16.84%,脾脏组织分别为1.73%、3.80%和11.80%。结论·基于qPCR技术对不同染色体上的基因进行定量分析的方法可用于唐氏综合征嵌合体小鼠中三体细胞嵌合率的定量检测。Tc1小鼠细胞在嵌合体小鼠的心脏、小脑、大脑、肝脏、脾脏均可发生嵌合,心脏组织的嵌合率偏向最高。展开更多
Chimera states have been studied in 1D arrays, and a variety of different chimera states have been found using different models. Research has recently been extended to 2D arrays but only to phase models of them. Here,...Chimera states have been studied in 1D arrays, and a variety of different chimera states have been found using different models. Research has recently been extended to 2D arrays but only to phase models of them. Here, we extend it to a nonphase model of 2D arrays of neurons and focus on the influence of nonlocal coupling. Using extensive numerical simulations, we find, surprisingly, that this system can show most types of previously observed chimera states, in contrast to previous models, where only one or a few types of chimera states can be observed in each model. We also find that this model can show some special chimera-like patterns such as gridding and multicolumn patterns, which were previously observed only in phase models. Further, we present an effective approach, i.e., removing some of the coupling links, to generate heterogeneous coupling, which results in diverse chimera-like patterns and even induces transformations from one chimera-like pattern to another.展开更多
Pluripotent stem cells are unspecialized cells withunlimited self-renewal, and they can be triggered to differentiate into desired specialized cell types. These features provide the basis for an unlimited cell source ...Pluripotent stem cells are unspecialized cells withunlimited self-renewal, and they can be triggered to differentiate into desired specialized cell types. These features provide the basis for an unlimited cell source for innovative cell therapies. Pluripotent cells also allow to study developmental pathways, and to employ them or their differentiated cell derivatives in pharmaceutical testing and biotechnological applications. Via blastocyst complementation, pluripotent cells are a favoured tool for the generation of genetically modified mice. The recently established technology to generate an induced pluripotency status by ectopic co-expression of the transcription factors Oct4, Sox2, Klf4 and c-Myc allows to extending these applications to farm animal species, for which the derivation of genuine embryonic stem cells was not successful so far. Most induced pluripotent stem(i PS) cells are generated by retroviral or lentiviral transduction of reprogramming factors. Multiple viral integrations into the genome may cause insertional mutagenesis and may increase the risk of tumour formation. Non-integration methods have been reported to overcome the safety concerns associated with retro and lentiviral-derived i PS cells, such as transient expression of the reprogramming factors using episomal plasmids, and direct delivery of reprogramming m RNAs or proteins. In this review, we focus on the mechanisms of cellular reprogramming and current methods used to induce pluripotency. We also highlight problems associated with the generation of i PS cells. An increased understanding of the fundamental mechanisms underlying pluripotency and refining the methodology of i PS cell generation will have a profound impact on future development and application in regenerative medicine and reproductive biotechnology of farm animals.展开更多
基金Supported by the National Science and Technology Major Project of China(2017ZX05035).
文摘Based on analysis of pore features and pore skeleton composition of shale,a“rigid elastic chimeric”pore skeleton model of shale gas reservoir was built.Pore deformation mechanisms leading to increase of shale porosity due to the pore skeleton deformation under overpressure were sorted out through analysis of stress on the shale pore and skeleton.After reviewing the difficulties and defects of existent porosity measurement methods,a dynamic deformed porosity measurement method was worked out and used to measure the porosity of overpressure Silurian Longmaxi Formation shale under real formation conditions in southern Sichuan Basin.The results show:(1)The shale reservoir is a mixture of inorganic rock particles and organic matter,which contains inorganic pores supported by rigid skeleton particles and organic pores supported by elastic-plastic particles,and thus has a special“rigid elastic chimeric”pore structure.(2)Under the action of formation overpressure,the inorganic pores have tiny changes that can be assumed that they don’t change in porosity,while the organic pores may have large deformation due to skeleton compression,leading to the increase of radius,connectivity and ultimately porosity of these pores.(3)The“dynamic”deformation porosity measurement method combining high injection pressure helium porosity measurement and kerosene porosity measurement method under ultra-high variable pressure can accurately measure porosity of unconnected micro-pores under normal pressure conditions,and also the porosity increment caused by plastic skeleton compression deformation.(4)The pore deformation mechanism of shale may result in the"abnormal"phenomenon that the shale under formation conditions has higher porosity than that under normal pressure,so the overpressure shale reservoir is not necessarily“ultra-low in porosity”,and can have porosity over 10%.Application of this method in Well L210 in southern Sichuan has confirmed its practicality and reliability.
文摘目的·建立一种定量检测唐氏综合征嵌合体小鼠各脏器嵌合情况的方法,并初步探究其不同器官中的嵌合规律。方法·分别针对唐氏综合征模型Tc1小鼠细胞(三体细胞)内人源21号染色体(记为Hsa21)上SIM2基因和小鼠15号染色体(记为Mmu15)上Derl1基因设计引物,采用实时荧光定量PCR(quantitative real time PCR,qPCR)技术对SIM2和Derl1进行检测来反映Hsa21和Mmu15的比例,并以此计算嵌合体小鼠各器官中Tc1小鼠细胞的嵌合占比。结果·所鉴定的小鼠中有3只为嵌合体小鼠。该3只小鼠心脏组织Tc1小鼠细胞嵌合率分别为8.98%、21.71%和57.70%,小脑组织分别为5.62%、20.17%和40.43%,大脑组织分别为8.48%、15.35%和20.45%,肝脏组织分别为2.66%、6.50%和16.84%,脾脏组织分别为1.73%、3.80%和11.80%。结论·基于qPCR技术对不同染色体上的基因进行定量分析的方法可用于唐氏综合征嵌合体小鼠中三体细胞嵌合率的定量检测。Tc1小鼠细胞在嵌合体小鼠的心脏、小脑、大脑、肝脏、脾脏均可发生嵌合,心脏组织的嵌合率偏向最高。
文摘Chimera states have been studied in 1D arrays, and a variety of different chimera states have been found using different models. Research has recently been extended to 2D arrays but only to phase models of them. Here, we extend it to a nonphase model of 2D arrays of neurons and focus on the influence of nonlocal coupling. Using extensive numerical simulations, we find, surprisingly, that this system can show most types of previously observed chimera states, in contrast to previous models, where only one or a few types of chimera states can be observed in each model. We also find that this model can show some special chimera-like patterns such as gridding and multicolumn patterns, which were previously observed only in phase models. Further, we present an effective approach, i.e., removing some of the coupling links, to generate heterogeneous coupling, which results in diverse chimera-like patterns and even induces transformations from one chimera-like pattern to another.
基金Supported by CREST fellowship from Department of Biotechnology,Ministry of Science and Technology,Government of India(DK)International fellowship for Ph D from ICAR(TRT),Government of IndiaInternational training in generation of i PS cells from NAIP,ICAR,Government of India(TA)
文摘Pluripotent stem cells are unspecialized cells withunlimited self-renewal, and they can be triggered to differentiate into desired specialized cell types. These features provide the basis for an unlimited cell source for innovative cell therapies. Pluripotent cells also allow to study developmental pathways, and to employ them or their differentiated cell derivatives in pharmaceutical testing and biotechnological applications. Via blastocyst complementation, pluripotent cells are a favoured tool for the generation of genetically modified mice. The recently established technology to generate an induced pluripotency status by ectopic co-expression of the transcription factors Oct4, Sox2, Klf4 and c-Myc allows to extending these applications to farm animal species, for which the derivation of genuine embryonic stem cells was not successful so far. Most induced pluripotent stem(i PS) cells are generated by retroviral or lentiviral transduction of reprogramming factors. Multiple viral integrations into the genome may cause insertional mutagenesis and may increase the risk of tumour formation. Non-integration methods have been reported to overcome the safety concerns associated with retro and lentiviral-derived i PS cells, such as transient expression of the reprogramming factors using episomal plasmids, and direct delivery of reprogramming m RNAs or proteins. In this review, we focus on the mechanisms of cellular reprogramming and current methods used to induce pluripotency. We also highlight problems associated with the generation of i PS cells. An increased understanding of the fundamental mechanisms underlying pluripotency and refining the methodology of i PS cell generation will have a profound impact on future development and application in regenerative medicine and reproductive biotechnology of farm animals.
