Reduction of global livestock numbers and meat consumption have been recommended for climate change mitigation. However, the basic assumptions made to come up with that kind of recommendations reveal severe methodolog...Reduction of global livestock numbers and meat consumption have been recommended for climate change mitigation. However, the basic assumptions made to come up with that kind of recommendations reveal severe methodological deficiencies： （1） Carbon footprint, emission intensity, and life-cycle assessments of domestic livestock products reported in scientific literature consistently overlooked the necessity of correcting non CO2 GHG （greenhouse gas） emissions （nitrous oxide and methane） from managed ecosystems for baseline emission scenarios over time and space （pristine ecosystem and/or pre-climate change emissions）; （2） Uncertainties associated with the climate sensitivity of anthropogenic GHG-emissions have been ignored; （3） Inconsistencies in the methodological treatment of land use change （deforestation） in emission intensity calculations （per unit of product） can be detected in the literature; （4） The virtual lack of a discernable livestock signal in global methane distribution and historical methane emission rates has not been acknowledged; theoretical bottom up calculations do not reflect the relative insignificance of livestock-born methane for the global methane budget; （5） Potential substrate induced enhancement of methane breakdown rates have not been taken into consideration. A tremendous over-assessment of potential livestock contribution to climate change is the logical consequence of these important methodological deficiencies which have been inexorably propagated through recent scientific literature.展开更多
ZnO nanorods prepared by a solution-phase method are annealed at different temperatures in oxygen ambient.The luminescence properties of the samples are investigated.In the same excitation condition,the photoluminesce...ZnO nanorods prepared by a solution-phase method are annealed at different temperatures in oxygen ambient.The luminescence properties of the samples are investigated.In the same excitation condition,the photoluminescence(PL) spectra of all samples show an ultraviolet(UV) emission and a broad strong visible emission band.The asymmetric visible emis-sion band of annealed samples has a red-shift as the annealing temperature increasing from 200 ℃ to 600 ℃ and it can be deconvoluted into two subband emissions centered at 535 nm(green emission) and 611 nm(orange-red emission) by Gaussian-fitting analysis.Analyses of PL excitation(PLE) spectra and PL spectra at different excitation wavelengths reveal that the green emission and the orange-red emission have a uniform initial state,which can be attributed to the electron transition from Zn interstitial(Zni) to oxygen vacancy(Vo) and oxygen interstitial(Oi),respectively.展开更多
文摘Reduction of global livestock numbers and meat consumption have been recommended for climate change mitigation. However, the basic assumptions made to come up with that kind of recommendations reveal severe methodological deficiencies： （1） Carbon footprint, emission intensity, and life-cycle assessments of domestic livestock products reported in scientific literature consistently overlooked the necessity of correcting non CO2 GHG （greenhouse gas） emissions （nitrous oxide and methane） from managed ecosystems for baseline emission scenarios over time and space （pristine ecosystem and/or pre-climate change emissions）; （2） Uncertainties associated with the climate sensitivity of anthropogenic GHG-emissions have been ignored; （3） Inconsistencies in the methodological treatment of land use change （deforestation） in emission intensity calculations （per unit of product） can be detected in the literature; （4） The virtual lack of a discernable livestock signal in global methane distribution and historical methane emission rates has not been acknowledged; theoretical bottom up calculations do not reflect the relative insignificance of livestock-born methane for the global methane budget; （5） Potential substrate induced enhancement of methane breakdown rates have not been taken into consideration. A tremendous over-assessment of potential livestock contribution to climate change is the logical consequence of these important methodological deficiencies which have been inexorably propagated through recent scientific literature.
基金supported by the National Natural Science Foundation of China(Nos.60877029,10904109,60977035 and 60907021)the Natural Science Foundation of Tianjin(Nos.09JCYBJC01400 and 10SYSYJC28100)+1 种基金the Key Subject for Materials Physics and Chemistry of Tianjinthe Open Foundation of Key Laboratory of Luminescence and Optical Information of Ministry of Education(Nos.2010LOI02 and 2010LOI11)
文摘ZnO nanorods prepared by a solution-phase method are annealed at different temperatures in oxygen ambient.The luminescence properties of the samples are investigated.In the same excitation condition,the photoluminescence(PL) spectra of all samples show an ultraviolet(UV) emission and a broad strong visible emission band.The asymmetric visible emis-sion band of annealed samples has a red-shift as the annealing temperature increasing from 200 ℃ to 600 ℃ and it can be deconvoluted into two subband emissions centered at 535 nm(green emission) and 611 nm(orange-red emission) by Gaussian-fitting analysis.Analyses of PL excitation(PLE) spectra and PL spectra at different excitation wavelengths reveal that the green emission and the orange-red emission have a uniform initial state,which can be attributed to the electron transition from Zn interstitial(Zni) to oxygen vacancy(Vo) and oxygen interstitial(Oi),respectively.
