When a polymer chain has only one end group attaching to the boundary and all the other segments are located in the half-space divided by the boundary, it is defined as a tail chain~. Obviously, the model of tail chai...When a polymer chain has only one end group attaching to the boundary and all the other segments are located in the half-space divided by the boundary, it is defined as a tail chain~. Obviously, the model of tail chain represents the simplest form of展开更多
The simplest form of a polymer chain adsorbed on a solid surface is that the polymer chain has only one end group attached to the surface, i.e. the polymer chain forms the "tail" conformation. In the present...The simplest form of a polymer chain adsorbed on a solid surface is that the polymer chain has only one end group attached to the surface, i.e. the polymer chain forms the "tail" conformation. In the present work, the problem was simplified as the random walk confined in the half-infinite space and studied systematically. The conformational distribution functions of the model tail chain in different dimensions were obtained. It has been found that the ratio of the conformational number of the model tail chains to that of the free chains varies as a power function N-12 when the chain length N→∞. It has also been proved that for the tail chain the component of the mean square end-to-end distance in the normal direction of the confined boundary is doubled and the other components are constant in comparison with the case of the free chain.展开更多
The SAW tail chains were studied.The permitted conformational number and the mean square end-to-end distance as a function of the chain length N for such a model tail chain were obtained by computer simulations,includ...The SAW tail chains were studied.The permitted conformational number and the mean square end-to-end distance as a function of the chain length N for such a model tail chain were obtained by computer simulations,including the exact enumeration and Monte Carlo method.These two basic quantities obeyed the relations deduced from the scaling law.The critical exponents and the lattice indexes were given by fitting the data of the computer experiments.It has been shown that there is a certain extension in the size of the SAW tail chains as well as the NRW tail chains in the direction normal to the wall.The normal component of the mean square end-to-end distance is almost twice as large as the parallel component of the short chain SAW.However,as N→∞,the effect of the wall on the chain conformation becomes a little weak because of the self-avoiding behavior for the model.That is quite different from the case of the NRW tail chain.展开更多
The configurational properties of tail-like polymer chains with one end attached to a flat surface are studied by using dynamic Monte Carlo technique. We find that the probability distribution of the free end in z dir...The configurational properties of tail-like polymer chains with one end attached to a flat surface are studied by using dynamic Monte Carlo technique. We find that the probability distribution of the free end in z direction P(Rz) and the density profile ρ(z) can be scaled approximately by a factor β to be a length independent function for both random walking (RW) and self-avoiding walking (SAW) tail-like chains, where the factor β is related to the mean square end-to-end distance <R2>. The scaled P(Rz) of the SAW chain roughly overlaps that of the RW chain, but the scaled ρ(z) of the SAW chain locates at smaller βz than that of the RW chain.展开更多
Based on the introduction of the Long Tail,the political,economical,social and technological environment for the development of rural supermarket chain in Ningxia is analyzed.The problems in the marketing strategy of ...Based on the introduction of the Long Tail,the political,economical,social and technological environment for the development of rural supermarket chain in Ningxia is analyzed.The problems in the marketing strategy of Ningxia rural supermarket chain are pointed out,including single products and uneven level of quality,the products,which can not satisfy farmers' needs;low quality of the personnel and imperfect information system,thus the traditional way of marketing is challenged.In the end,from the perspective of products,position,price,and personnel,the marketing strategies for the development of Ningxia rural supermarket chain based on the Long Tail Theory are put forward.展开更多
Some polarity terms of two groups of nitrogen-containing surfactants （six alkanolamides and nine polyoxyethylenated long chain amines） are measured through gas chromatography. The apparent methanol carbon number (CM...Some polarity terms of two groups of nitrogen-containing surfactants （six alkanolamides and nine polyoxyethylenated long chain amines） are measured through gas chromatography. The apparent methanol carbon number (CMeOH) and polarity index （IP） values are determined on the investigated surfactants as stationary phases in packed columns. Similarly, CMeOH and IP values are determined on simulated hydrophobic tail （SHT） models. The obtained results reveal that the introduction of SHT approach permits the distinction between the polarities of different surfactants and their head groups. The measured polarity terms are discussed as related to hydrophile-lipophile balance （HLB） number and the hydrophobic group carbon number （RCN）. Some equations relating the measured polarity values and these variable have been developed.展开更多
A systemic study was initiated to identify stage-specific expression genes in fish embryogenesis by using suppression subtractive hybridization (SSH) technique. In this study, we presented a preliminary result on scre...A systemic study was initiated to identify stage-specific expression genes in fish embryogenesis by using suppression subtractive hybridization (SSH) technique. In this study, we presented a preliminary result on screen for stage-specific expression genes between tail bud stage (TBS) and heartbeat beginning stage (HBS) in gynogenetic silver crucian carp (Carassius auratus gibelio). Two SSH plasmid libraries specific for TBS embryos and HBS embryos were constructed, and stage-specific expression genes were screened between the two stages. 1963 TBS positive clones and 2466 HBS positive clones were sampled to PCR amplification, and 1373 TBS and 1809 HBS PCR positive clones were selected to carry out dot blots. 169TBS dot blot positive clones and 272 HBS dot blot positive clones were sequenced. Searching GenBank by using these nucleotide sequences indicated that most of the TBS dot blot positive clones could not be found homologous sequences in the database, while known genes were mainly detected from HBS dot blot positive clones. Of the 79 known genes, 20 were enzymes or kinases involved in important metabolism of embryonic development. Moreover, specific expressions of partial genes were further confirmed by virtual northern blots. This study is the first step for making a large attempt to study temporal and spatial control f gene expression in the gynogenetic fish embryogenesis.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘When a polymer chain has only one end group attaching to the boundary and all the other segments are located in the half-space divided by the boundary, it is defined as a tail chain~. Obviously, the model of tail chain represents the simplest form of
基金Project supported by the National Natural Science Foundation of China
文摘The simplest form of a polymer chain adsorbed on a solid surface is that the polymer chain has only one end group attached to the surface, i.e. the polymer chain forms the "tail" conformation. In the present work, the problem was simplified as the random walk confined in the half-infinite space and studied systematically. The conformational distribution functions of the model tail chain in different dimensions were obtained. It has been found that the ratio of the conformational number of the model tail chains to that of the free chains varies as a power function N-12 when the chain length N→∞. It has also been proved that for the tail chain the component of the mean square end-to-end distance in the normal direction of the confined boundary is doubled and the other components are constant in comparison with the case of the free chain.
基金supported by the National Natural Science Foundation of China
文摘The SAW tail chains were studied.The permitted conformational number and the mean square end-to-end distance as a function of the chain length N for such a model tail chain were obtained by computer simulations,including the exact enumeration and Monte Carlo method.These two basic quantities obeyed the relations deduced from the scaling law.The critical exponents and the lattice indexes were given by fitting the data of the computer experiments.It has been shown that there is a certain extension in the size of the SAW tail chains as well as the NRW tail chains in the direction normal to the wall.The normal component of the mean square end-to-end distance is almost twice as large as the parallel component of the short chain SAW.However,as N→∞,the effect of the wall on the chain conformation becomes a little weak because of the self-avoiding behavior for the model.That is quite different from the case of the NRW tail chain.
基金Project (No. 20204014) supported by the National Natural ScienceFoundation of China
文摘The configurational properties of tail-like polymer chains with one end attached to a flat surface are studied by using dynamic Monte Carlo technique. We find that the probability distribution of the free end in z direction P(Rz) and the density profile ρ(z) can be scaled approximately by a factor β to be a length independent function for both random walking (RW) and self-avoiding walking (SAW) tail-like chains, where the factor β is related to the mean square end-to-end distance <R2>. The scaled P(Rz) of the SAW chain roughly overlaps that of the RW chain, but the scaled ρ(z) of the SAW chain locates at smaller βz than that of the RW chain.
基金Supported by Scientific Research Item of Ningxia Higher EducationScience Research Fund of Ningxia University(NDSK09-34)
文摘Based on the introduction of the Long Tail,the political,economical,social and technological environment for the development of rural supermarket chain in Ningxia is analyzed.The problems in the marketing strategy of Ningxia rural supermarket chain are pointed out,including single products and uneven level of quality,the products,which can not satisfy farmers' needs;low quality of the personnel and imperfect information system,thus the traditional way of marketing is challenged.In the end,from the perspective of products,position,price,and personnel,the marketing strategies for the development of Ningxia rural supermarket chain based on the Long Tail Theory are put forward.
文摘Some polarity terms of two groups of nitrogen-containing surfactants （six alkanolamides and nine polyoxyethylenated long chain amines） are measured through gas chromatography. The apparent methanol carbon number (CMeOH) and polarity index （IP） values are determined on the investigated surfactants as stationary phases in packed columns. Similarly, CMeOH and IP values are determined on simulated hydrophobic tail （SHT） models. The obtained results reveal that the introduction of SHT approach permits the distinction between the polarities of different surfactants and their head groups. The measured polarity terms are discussed as related to hydrophile-lipophile balance （HLB） number and the hydrophobic group carbon number （RCN）. Some equations relating the measured polarity values and these variable have been developed.
基金This work was supported by the National Nat-ural Science Foundation of China(Grant No.30130240),the Chinese Academy of Sciences(GrantNo.KSCX2-SW-303).
文摘A systemic study was initiated to identify stage-specific expression genes in fish embryogenesis by using suppression subtractive hybridization (SSH) technique. In this study, we presented a preliminary result on screen for stage-specific expression genes between tail bud stage (TBS) and heartbeat beginning stage (HBS) in gynogenetic silver crucian carp (Carassius auratus gibelio). Two SSH plasmid libraries specific for TBS embryos and HBS embryos were constructed, and stage-specific expression genes were screened between the two stages. 1963 TBS positive clones and 2466 HBS positive clones were sampled to PCR amplification, and 1373 TBS and 1809 HBS PCR positive clones were selected to carry out dot blots. 169TBS dot blot positive clones and 272 HBS dot blot positive clones were sequenced. Searching GenBank by using these nucleotide sequences indicated that most of the TBS dot blot positive clones could not be found homologous sequences in the database, while known genes were mainly detected from HBS dot blot positive clones. Of the 79 known genes, 20 were enzymes or kinases involved in important metabolism of embryonic development. Moreover, specific expressions of partial genes were further confirmed by virtual northern blots. This study is the first step for making a large attempt to study temporal and spatial control f gene expression in the gynogenetic fish embryogenesis.
