1. Introduction In quantum optics, optical frequency conversion is a typical nonlinear process and is worth studying, for example, a second harmonic frequency generation will generate a squeezed state.[1＇2l In this ...1. Introduction In quantum optics, optical frequency conversion is a typical nonlinear process and is worth studying, for example, a second harmonic frequency generation will generate a squeezed state.[1＇2l In this work, we tackle the evolution of an initial coherent state in a Raman dispersion process which is also a nonlinear process. The process involves the inelastic scattering of a pho- ton when it is incident on a molecule. The photon loses some of its energy to the molecule or gains some from it, and so leaves the molecule with a lower or a higher frequency. The lower frequency components of the scattered radiation are called the Stokes lines and the higher frequency components are called the anti- Stokes lines. The Hamiltonian governing its dynamics is[3]展开更多
The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of pa...The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of patches in different stages of ecological succession. The aim of this study is to follow and describe the resilience in artificial disturbed sediment in a polluted bay in Rio de Janeiro. The sediment was collected, sterilized and placed inside corers (10 cmdiameter ×15 cmheight) in the same place where it was collected. We allocated the samples in two structures, the difference between them was that one was placed closed to the bottom and the other was placed50 cmheight. We found 2352 organisms distributed in 14 taxons. The class Polychaeta and the order Amphipoda showed the highest density in all the survey and treatments. We identified the factors influencing the scenarium: different mechanisms of dispersal, the position of the structures and life history of each group. Disturbance can be the main cause of the patch’s diversity found in estuaries and coastal areas. Because of this, monitoring of selected areas becomes an important tool to understand the regime of disturbance as a key factor structuring benthic communities in soft sediment, also suggesting a metapopulation dynamics.展开更多
Nanosized dispersive hexagonal magnesium hydroxide （Mg（OH）2） has been prepared using an ammonia- hydrothermal method. Citric acid and monoethanolamine （MEA） were added to the reaction system during the ammonia p...Nanosized dispersive hexagonal magnesium hydroxide （Mg（OH）2） has been prepared using an ammonia- hydrothermal method. Citric acid and monoethanolamine （MEA） were added to the reaction system during the ammonia precipitation and hydrothermal processes, respectively, to improve the crystallinity and dispersion of the （Mg（OH）2） particles. The resulting Mg（OH）2 samples obtained under the opti- mum preparation conditions were characterized by scanning electron microscopy, X-ray diffraction and thermal gravity analysis, which showed that this newly developed procedure afforded well-dispersed hexagonal nanoolates of Mg（OH）2 with a mean diameter of 246 nm.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10775097 and 10475056)
文摘1. Introduction In quantum optics, optical frequency conversion is a typical nonlinear process and is worth studying, for example, a second harmonic frequency generation will generate a squeezed state.[1＇2l In this work, we tackle the evolution of an initial coherent state in a Raman dispersion process which is also a nonlinear process. The process involves the inelastic scattering of a pho- ton when it is incident on a molecule. The photon loses some of its energy to the molecule or gains some from it, and so leaves the molecule with a lower or a higher frequency. The lower frequency components of the scattered radiation are called the Stokes lines and the higher frequency components are called the anti- Stokes lines. The Hamiltonian governing its dynamics is[3]
文摘The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of patches in different stages of ecological succession. The aim of this study is to follow and describe the resilience in artificial disturbed sediment in a polluted bay in Rio de Janeiro. The sediment was collected, sterilized and placed inside corers (10 cmdiameter ×15 cmheight) in the same place where it was collected. We allocated the samples in two structures, the difference between them was that one was placed closed to the bottom and the other was placed50 cmheight. We found 2352 organisms distributed in 14 taxons. The class Polychaeta and the order Amphipoda showed the highest density in all the survey and treatments. We identified the factors influencing the scenarium: different mechanisms of dispersal, the position of the structures and life history of each group. Disturbance can be the main cause of the patch’s diversity found in estuaries and coastal areas. Because of this, monitoring of selected areas becomes an important tool to understand the regime of disturbance as a key factor structuring benthic communities in soft sediment, also suggesting a metapopulation dynamics.
文摘Nanosized dispersive hexagonal magnesium hydroxide （Mg（OH）2） has been prepared using an ammonia- hydrothermal method. Citric acid and monoethanolamine （MEA） were added to the reaction system during the ammonia precipitation and hydrothermal processes, respectively, to improve the crystallinity and dispersion of the （Mg（OH）2） particles. The resulting Mg（OH）2 samples obtained under the opti- mum preparation conditions were characterized by scanning electron microscopy, X-ray diffraction and thermal gravity analysis, which showed that this newly developed procedure afforded well-dispersed hexagonal nanoolates of Mg（OH）2 with a mean diameter of 246 nm.
