Surface phonon spectra,from Ta/Al Fibonacci multilayers are studied via Brillouin scattering.Determination of the frequency positions of the Rayleigh wave and the intensity dip corresponding to the longitudinal thresh...Surface phonon spectra,from Ta/Al Fibonacci multilayers are studied via Brillouin scattering.Determination of the frequency positions of the Rayleigh wave and the intensity dip corresponding to the longitudinal threshold has enabled us to extract two effective elastic constants C_(44) and C_(11) of the whole structure.The 22.6% enhancement of the shear modulus is found in our experiment.展开更多
Low-frequency phonon spectra,in a-SiN_(x):H/Si lieterostructures have been observed by means of Brilloiiiii light scattering.Afeasurement of the frequency shift on longi-tudintil and transverse Acoustic phonons as wel...Low-frequency phonon spectra,in a-SiN_(x):H/Si lieterostructures have been observed by means of Brilloiiiii light scattering.Afeasurement of the frequency shift on longi-tudintil and transverse Acoustic phonons as well as on surface phonons enabled us to extract accurately two independent elastic moduli:c_(11) and C_(44) deduced irom phase velocities of bulk acoustic modes and scat taring wavevector^within effective medium approximation.展开更多
Raman scattering experiments from acoustic phonons in Fibonacci metallic Nb-Cu superlattices were performed.The main features of the experimental results show that the Raman spectrum is dominated by triplet peaks whic...Raman scattering experiments from acoustic phonons in Fibonacci metallic Nb-Cu superlattices were performed.The main features of the experimental results show that the Raman spectrum is dominated by triplet peaks which originate from the density of states of longitudinal-acoustic(LA)phonons in the subbands of phonon dispersion.The expected rich structure of gaps in the phonon spectrum has been labeled by strongest diffraction wave vector factor nτP.展开更多
Green tides are caused by the proliferation of chlorophytes under suitable hydrographic conditions.These blooms lead to environmental degradation and negatively impact the waters and seagrass beds,as well as fishing a...Green tides are caused by the proliferation of chlorophytes under suitable hydrographic conditions.These blooms lead to environmental degradation and negatively impact the waters and seagrass beds,as well as fishing and other recreational activities in the bay.A comprehensive ecological understanding of the bloom dynamics,including the origin and persistence,is needed to foster management decisions.The algae in the great majority of green tide blooms usually belong to two genera of Ulvophyceae,Ulva and Enteromorpha.Ulva has been observed more often in recent years.In China,green tides occurred for the first time in the middle area of the Yellow Sea in 2007,and a large-scale algae blooming broke out in the middle and southern areas of the Yellow Sea in late May 2008.We identified them as Ulva prolifera by comparative analysis of the rDNA internal transcribed spacer 1 (ITS1),5.8S and ITS2 sequences in combination with microscopic observation.Morphological differences were found between the free-floating algae and the attached thalli.Various reproduction patterns of the free-floating algae include sexual,asexual and vegetative propagations,which played important roles in the long-term green tide persistence in China.The ITS sequences of the blooming algae were identical to those of the samples from the Lianyungang sea area but were different from the attached samples from the Qingdao sea area.The results infer that the blooms are originated from other sea areas rather than from the local attached populations.展开更多
By employing a gettered annealing technique,we studied the relationship between the resistivity p(x,T)(20℃≤T≤300℃)and oxygen content»n the high-Tc superconductor YBa_(2)Cu_(3)O_(7-x).ρ(x,T)is approximately l...By employing a gettered annealing technique,we studied the relationship between the resistivity p(x,T)(20℃≤T≤300℃)and oxygen content»n the high-Tc superconductor YBa_(2)Cu_(3)O_(7-x).ρ(x,T)is approximately linear for 0.0≤x≤0.6,and both the slope dp/dT and the residual resistivity increase continuously with decreasing oxygen content.A qualitative analysis is given.展开更多
基金Supported by the National Natural Science Foundation of Cliina,and Science Foundation of Education Committee of Cliina,as well as Center for Material Analysis of Naiying University.
文摘Surface phonon spectra,from Ta/Al Fibonacci multilayers are studied via Brillouin scattering.Determination of the frequency positions of the Rayleigh wave and the intensity dip corresponding to the longitudinal threshold has enabled us to extract two effective elastic constants C_(44) and C_(11) of the whole structure.The 22.6% enhancement of the shear modulus is found in our experiment.
基金Supported by the National Natxu al Science Foiuidation of ChinaScience Found of Chinese Educatioxi Conunittee.
文摘Low-frequency phonon spectra,in a-SiN_(x):H/Si lieterostructures have been observed by means of Brilloiiiii light scattering.Afeasurement of the frequency shift on longi-tudintil and transverse Acoustic phonons as well as on surface phonons enabled us to extract accurately two independent elastic moduli:c_(11) and C_(44) deduced irom phase velocities of bulk acoustic modes and scat taring wavevector^within effective medium approximation.
基金Project supported by the National Science Foundation of China.
文摘Raman scattering experiments from acoustic phonons in Fibonacci metallic Nb-Cu superlattices were performed.The main features of the experimental results show that the Raman spectrum is dominated by triplet peaks which originate from the density of states of longitudinal-acoustic(LA)phonons in the subbands of phonon dispersion.The expected rich structure of gaps in the phonon spectrum has been labeled by strongest diffraction wave vector factor nτP.
基金supported by ShanDong Province Important Science & Technology Specific Project (No.2008ZHZX1A1203)Science & Technology Specific Project of Qingdao (No.08-1-7-2-hy,No.09-2-5-3-hy)
文摘Green tides are caused by the proliferation of chlorophytes under suitable hydrographic conditions.These blooms lead to environmental degradation and negatively impact the waters and seagrass beds,as well as fishing and other recreational activities in the bay.A comprehensive ecological understanding of the bloom dynamics,including the origin and persistence,is needed to foster management decisions.The algae in the great majority of green tide blooms usually belong to two genera of Ulvophyceae,Ulva and Enteromorpha.Ulva has been observed more often in recent years.In China,green tides occurred for the first time in the middle area of the Yellow Sea in 2007,and a large-scale algae blooming broke out in the middle and southern areas of the Yellow Sea in late May 2008.We identified them as Ulva prolifera by comparative analysis of the rDNA internal transcribed spacer 1 (ITS1),5.8S and ITS2 sequences in combination with microscopic observation.Morphological differences were found between the free-floating algae and the attached thalli.Various reproduction patterns of the free-floating algae include sexual,asexual and vegetative propagations,which played important roles in the long-term green tide persistence in China.The ITS sequences of the blooming algae were identical to those of the samples from the Lianyungang sea area but were different from the attached samples from the Qingdao sea area.The results infer that the blooms are originated from other sea areas rather than from the local attached populations.
文摘By employing a gettered annealing technique,we studied the relationship between the resistivity p(x,T)(20℃≤T≤300℃)and oxygen content»n the high-Tc superconductor YBa_(2)Cu_(3)O_(7-x).ρ(x,T)is approximately linear for 0.0≤x≤0.6,and both the slope dp/dT and the residual resistivity increase continuously with decreasing oxygen content.A qualitative analysis is given.
