The time processes of photosynthetic induction responses to various irradiances in Korean pine (Pinus koraiensis) seedlings grown in open-light environments and in understory of forest were studied in an area near the...The time processes of photosynthetic induction responses to various irradiances in Korean pine (Pinus koraiensis) seedlings grown in open-light environments and in understory of forest were studied in an area near the Research Station of Changbai Mountain Forest Ecosystems, Jilin Province, China from July 15 to August 5, 1997. The results showed that at 200 靘olm-2s-1 photosynthetic photon flux density (PPFD) and 500 靘olm-2s-1 PPFD, the induction time for the photosynthetic rates of understory-grown seedlings to reach 50% and 90% steady-state net photosynthetic rates was longer than that of the open-grown seedlings. The induction responses of open-growth seedlings at 500 靘olm-2s-1 PPFD were slower than those at 200 靘olm-2s-1 PPFD, but it was the very reverse for understory-growth seedlings, which indicates that the photosynthetic induction times of Korean pine seedlings grown in the understory depended on the sunfleck intensity.展开更多
The competition-density effect of plant populations is of significance in theory and practice of forest management and has been studied for long time. The differences between the two reciprocal equations of the compet...The competition-density effect of plant populations is of significance in theory and practice of forest management and has been studied for long time. The differences between the two reciprocal equations of the competition-density effect in nonself-thinning populations and self-thinning populations were analyzed theoretically. This supplies a theoretical basis for analyzing the dynamics of forest populations and evaluating the effect of forest management.展开更多
This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as th...This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as the epidermis of apples, with SEM (Scanning Electronic Microscope) showed that natural structures’ pores can be classified into uniform pores, gradient pores and multi pores from the viewpoint of the distribution variation of pore density, size and geometry. Furthermore, an optimal design of porous bearings was for the first time developed based on the gradient configuration of natural materials. The bionic design of porous structures is predicted to be widely developed and applied in the fields of materials and mechanical engineering in the future.展开更多
Density functional theory B3LYP method with 6-31＋＋G＊＊ basis was used to optimize the geometries of the ground states for 1,2,3-triazine-（H2O）n（n=1,2,3） complexes. All calculations indicate that the 1,2,3- tria...Density functional theory B3LYP method with 6-31＋＋G＊＊ basis was used to optimize the geometries of the ground states for 1,2,3-triazine-（H2O）n（n=1,2,3） complexes. All calculations indicate that the 1,2,3- triazine-water complexes in the ground states have strong hydrogen-bonding interaction, and the complex having a N… .H-O hydrogen bond and a chain of water molecules which is terminated by a O. … .H-C hydrogen bond is the most stable. The H-O stretching modes of complexes are red-shifted relative to that of the monomer. In addition, the Natural bond orbit （NBO） analysis indicates that the intermolecular charge transfer between 1,2,3-triazine and water is 0.0222e, 0.0261e and 0.0273e for the most stable 1：1, 1：2 and 1：3 complexes, respectively. The first singlet （n, π＊） vertical excitation energy of the monomer 1,2,3-triazine and the hydrogen-bonding complexes of 1,2,3-triazine-（H2O）n were investigated by time-dependent density functional theory.展开更多
Saline aquifers are chosen for geological storage of greenhouse gas CO_2 because of their storage potential.In almost all cases of practical interest,CO_2 is present on top of the liquid and CO_2 dissolution leads to ...Saline aquifers are chosen for geological storage of greenhouse gas CO_2 because of their storage potential.In almost all cases of practical interest,CO_2 is present on top of the liquid and CO_2 dissolution leads to a small increase in the density of the aqueous phase.This situation results in the creation of negative buoyancy force for downward density-driven natural convection and consequently enhances CO_2 sequestration.In order to study CO_2 injection at pore-level,an isothermal Lattice Boltzmann Model(LBM) with two distribution functions is adopted to simulate density-driven natural convection in porous media with irregular geometry obtained by image treatment.The present analysis showed that after the onset of natural convection instability,the brine with a high CO_2 concentration infringed into the underlying unaffected brine,in favor of the migration of CO_2 into the pore structure.With low Rayleigh numbers,the instantaneous mass flux and total dissolved CO_2 mass are very close to that derived from penetration theory(diffusion only),but the fluxes are significantly enhanced with high Ra number.The simulated results show that as the time increases,some chaotic and recirculation zones in the flow appear obviously,which promotes the renewal of interfacial liquid,and hence enhances dissolution of CO_2 into brine.This study is focused on the scale of a few pores,but shows implications in enhanced oil/gas recovery with CO_2 sequestration in aquifers.展开更多
Density function M06 method has been used to optimize the geometries of camptothecin-cytosine at 6-3 I＋G＊ basis. Finally, thirteen stabilized complexes have been obtained. Theories of atoms in molecules （AIM） and ...Density function M06 method has been used to optimize the geometries of camptothecin-cytosine at 6-3 I＋G＊ basis. Finally, thirteen stabilized complexes have been obtained. Theories of atoms in molecules （AIM） and natural bond orbital （NBO） have been utilized to investigate the hydrogen bonds involved in all the complexes. The interaction energies of all the complexes are corrected by basis set superposition error （BSSE）. By the analysis of complexes interaction energy, charge density, second- order interaction energies E（2）; it is indicated that the complex 6 is the most stable structure.展开更多
Besides arguments like fighting against dispersed urbanization, improving economies of infrastructure and preserving natural resources, another measure to sustainability is the delight of people in staying together wi...Besides arguments like fighting against dispersed urbanization, improving economies of infrastructure and preserving natural resources, another measure to sustainability is the delight of people in staying together with others sharing a well-designed urban landscape. Analyzing the Celebration’s urban setting is highlighted how some design firms are turning to reclaim the types of urbanism and traditional American architecture, representing the wish for reinforcing the daily vicinity relationships. As a matter of sustainability, it mentioned aspects of vehicular accessibility and the population density which is higher in Celebration than that in other suburban towns in USA. Attention is given both to the management of natural landscape and the role of the entrepreneur to construct a town in a so fragile soil. The relationship between community and sustainability is highlighted, leading to the idea of building spaces to become places, capable to convey the feeling of joy of living.展开更多
To reveal the mechanism of control of the Woolly Apple Aphid （Eriosoma lanigerum Hausm, WAA） by increase of biodiversity in the apple orchard, a consecutive two-year field trials were conducted in Yurman province, C...To reveal the mechanism of control of the Woolly Apple Aphid （Eriosoma lanigerum Hausm, WAA） by increase of biodiversity in the apple orchard, a consecutive two-year field trials were conducted in Yurman province, China. The results showed that the peak of natural enemy density curve in the cover cropping orchard was well temporally synchronized with that of the WAA density on trees, but did not synchronize with that of WAA density on trees in clean orchard. In addition, the frequency of natural enemies and WAA within a same sample in cover cropping orchard was obviously higher than that in clean cultivated orchard during the peak of population curves, indicating that natural enemies spatially synchronized with aphids. The density of WAA for the whole growing season in cover cropping orchard was much less than that in clean orchard. Therefore, the temporal-spatial synchrony of natural enemy and aphid populations was proposed as one of the mechanisms for aphid control in cover cropped orchards.展开更多
基金The project was supported by the North China University of Water Conservancy and Electric Power High-level Experts Scientific Research Foundation,China(201114)Henan Provincial Education Department,China(14A150024)+4 种基金Jiangxi Provincial Education Department,China(GJJ14230)Sponsored Program for Cultivating Youths of Outstanding Ability in Jiangxi Normal University,ChinaYoung Scientist Foundation of Jiangxi Province,China(20133BCB23011)"Gan-Po Talent 555"Project of Jiangxi Province,ChinaNational Natural Science Foundation of China(21103074)~~
文摘The time processes of photosynthetic induction responses to various irradiances in Korean pine (Pinus koraiensis) seedlings grown in open-light environments and in understory of forest were studied in an area near the Research Station of Changbai Mountain Forest Ecosystems, Jilin Province, China from July 15 to August 5, 1997. The results showed that at 200 靘olm-2s-1 photosynthetic photon flux density (PPFD) and 500 靘olm-2s-1 PPFD, the induction time for the photosynthetic rates of understory-grown seedlings to reach 50% and 90% steady-state net photosynthetic rates was longer than that of the open-grown seedlings. The induction responses of open-growth seedlings at 500 靘olm-2s-1 PPFD were slower than those at 200 靘olm-2s-1 PPFD, but it was the very reverse for understory-growth seedlings, which indicates that the photosynthetic induction times of Korean pine seedlings grown in the understory depended on the sunfleck intensity.
文摘The competition-density effect of plant populations is of significance in theory and practice of forest management and has been studied for long time. The differences between the two reciprocal equations of the competition-density effect in nonself-thinning populations and self-thinning populations were analyzed theoretically. This supplies a theoretical basis for analyzing the dynamics of forest populations and evaluating the effect of forest management.
文摘This investigation and morphology analysis of porous structure of some kinds of natural materials such as chicken eggshell, partridge eggshell, pig bone, and seeds of mung bean, soja, ginkgo, lotus seed, as well as the epidermis of apples, with SEM (Scanning Electronic Microscope) showed that natural structures’ pores can be classified into uniform pores, gradient pores and multi pores from the viewpoint of the distribution variation of pore density, size and geometry. Furthermore, an optimal design of porous bearings was for the first time developed based on the gradient configuration of natural materials. The bionic design of porous structures is predicted to be widely developed and applied in the fields of materials and mechanical engineering in the future.
文摘Density functional theory B3LYP method with 6-31＋＋G＊＊ basis was used to optimize the geometries of the ground states for 1,2,3-triazine-（H2O）n（n=1,2,3） complexes. All calculations indicate that the 1,2,3- triazine-water complexes in the ground states have strong hydrogen-bonding interaction, and the complex having a N… .H-O hydrogen bond and a chain of water molecules which is terminated by a O. … .H-C hydrogen bond is the most stable. The H-O stretching modes of complexes are red-shifted relative to that of the monomer. In addition, the Natural bond orbit （NBO） analysis indicates that the intermolecular charge transfer between 1,2,3-triazine and water is 0.0222e, 0.0261e and 0.0273e for the most stable 1：1, 1：2 and 1：3 complexes, respectively. The first singlet （n, π＊） vertical excitation energy of the monomer 1,2,3-triazine and the hydrogen-bonding complexes of 1,2,3-triazine-（H2O）n were investigated by time-dependent density functional theory.
文摘Saline aquifers are chosen for geological storage of greenhouse gas CO_2 because of their storage potential.In almost all cases of practical interest,CO_2 is present on top of the liquid and CO_2 dissolution leads to a small increase in the density of the aqueous phase.This situation results in the creation of negative buoyancy force for downward density-driven natural convection and consequently enhances CO_2 sequestration.In order to study CO_2 injection at pore-level,an isothermal Lattice Boltzmann Model(LBM) with two distribution functions is adopted to simulate density-driven natural convection in porous media with irregular geometry obtained by image treatment.The present analysis showed that after the onset of natural convection instability,the brine with a high CO_2 concentration infringed into the underlying unaffected brine,in favor of the migration of CO_2 into the pore structure.With low Rayleigh numbers,the instantaneous mass flux and total dissolved CO_2 mass are very close to that derived from penetration theory(diffusion only),but the fluxes are significantly enhanced with high Ra number.The simulated results show that as the time increases,some chaotic and recirculation zones in the flow appear obviously,which promotes the renewal of interfacial liquid,and hence enhances dissolution of CO_2 into brine.This study is focused on the scale of a few pores,but shows implications in enhanced oil/gas recovery with CO_2 sequestration in aquifers.
基金Funded by the Health Department Science Foundation of Sichuan(Grant No. 2011-236)
文摘Density function M06 method has been used to optimize the geometries of camptothecin-cytosine at 6-3 I＋G＊ basis. Finally, thirteen stabilized complexes have been obtained. Theories of atoms in molecules （AIM） and natural bond orbital （NBO） have been utilized to investigate the hydrogen bonds involved in all the complexes. The interaction energies of all the complexes are corrected by basis set superposition error （BSSE）. By the analysis of complexes interaction energy, charge density, second- order interaction energies E（2）; it is indicated that the complex 6 is the most stable structure.
文摘Besides arguments like fighting against dispersed urbanization, improving economies of infrastructure and preserving natural resources, another measure to sustainability is the delight of people in staying together with others sharing a well-designed urban landscape. Analyzing the Celebration’s urban setting is highlighted how some design firms are turning to reclaim the types of urbanism and traditional American architecture, representing the wish for reinforcing the daily vicinity relationships. As a matter of sustainability, it mentioned aspects of vehicular accessibility and the population density which is higher in Celebration than that in other suburban towns in USA. Attention is given both to the management of natural landscape and the role of the entrepreneur to construct a town in a so fragile soil. The relationship between community and sustainability is highlighted, leading to the idea of building spaces to become places, capable to convey the feeling of joy of living.
文摘To reveal the mechanism of control of the Woolly Apple Aphid （Eriosoma lanigerum Hausm, WAA） by increase of biodiversity in the apple orchard, a consecutive two-year field trials were conducted in Yurman province, China. The results showed that the peak of natural enemy density curve in the cover cropping orchard was well temporally synchronized with that of the WAA density on trees, but did not synchronize with that of WAA density on trees in clean orchard. In addition, the frequency of natural enemies and WAA within a same sample in cover cropping orchard was obviously higher than that in clean cultivated orchard during the peak of population curves, indicating that natural enemies spatially synchronized with aphids. The density of WAA for the whole growing season in cover cropping orchard was much less than that in clean orchard. Therefore, the temporal-spatial synchrony of natural enemy and aphid populations was proposed as one of the mechanisms for aphid control in cover cropped orchards.
