采用自制的序批式"厌氧发酵产氢反应装置",以餐厨垃圾为发酵底物,污水处理厂剩余污泥为接种微生物,初始pH为7.0、温度为37℃条件下,研究餐厨垃圾和剩余污泥不同质量混合比对厌氧发酵产氢的影响。结果表明,餐厨垃圾和剩余污泥...采用自制的序批式"厌氧发酵产氢反应装置",以餐厨垃圾为发酵底物,污水处理厂剩余污泥为接种微生物,初始pH为7.0、温度为37℃条件下,研究餐厨垃圾和剩余污泥不同质量混合比对厌氧发酵产氢的影响。结果表明,餐厨垃圾和剩余污泥质量比为4∶1时,厌氧发酵产氢效果最好,累积产氢量和单位产氢量(以VS计)最大,分别为252.2 m L和53.3 m L/g,TS和VS的去除率分别为20.9%和13.8%。展开更多
To make recycling utilization of organic materials produced in various agricultural systems, five kinds of organic materials were applied in a field test, including crop straw （CS）, biogas residue （BR）, mushroom r...To make recycling utilization of organic materials produced in various agricultural systems, five kinds of organic materials were applied in a field test, including crop straw （CS）, biogas residue （BR）, mushroom residue （MR）, wine residue （WR）, pig manure （PM）, with a mineral fertilizer （CF） and a no-fertilizer （CK） treatment as a control. Our objectives were： i） to quantify the effects of organic materials on soil C and N accumulation; ii） to evaluate the effects of organic materials on soil aggregate stability, along with the total organic carbon （TOC）, and N in different aggregate fractions; and iii） to assess the relationships among the organic material components, soil C and N, and C, N in aggregate fractions. The trial was conducted in Wuqiao County, Hebei Province, China. The organic materials were incorporated at an equal rate of C, and combined with a mineral fertilizer in amounts of 150 kg N ha^-1, 26 kg P ha^-1 and 124 kg K ha-1 respectively during each crop season of a wheat-maize rotation system. The inputted C quantity of each organic material treatment was equivalent to the total amount of C contained in the crop straw harvested in CS treatement in the previous season. TOC, N, water-stable aggregates, and aggregate-associated TOC and N were investigated. The results showed that organic material incorporation increased soil aggregation and stabilization. On average, the soil macroaggregate proportion increased by 14%, the microaggregate proportion increased by 3%, and mean-weight diameter （MWD） increased by 20%. TOC content followed the order of PM〉WR〉MR〉BR〉CS〉CK〉CF; N content followed the order WR〉PM〉MR〉BR〉CS〉CF〉CK. No significant correlation was found between TOC, N, and the quality of organic material. Soil silt and clay particles contained the largest part of TOC, whereas the small macroaggregate fraction was the most sensitive to organic materials. Our results indicate that PM and WR exerted better effects on soil C and N accumulation, followed by MR and BR, suggesting that organic materials from ex situ farmland could promote soil quality more as compared to straw returned in situ.展开更多
Understanding the trade-offs among ecosystem services(ESs)at multiple scales is a key challenge to effective environmental management.However,the scale effect of ESs trade-offs in the Qinghai-Tibetan Plateau(QTP)has r...Understanding the trade-offs among ecosystem services(ESs)at multiple scales is a key challenge to effective environmental management.However,the scale effect of ESs trade-offs in the Qinghai-Tibetan Plateau(QTP)has received little attention.This study investigated the scale effects of ESs trade-offs in Bailongjiang Watershed(BLJW),a typical transitional ecotone from the Loess Plateau to the Tibetan Plateau with multiple ESs,intensive human activities and frequent geological disasters in the Eastern Margin of the QTP,China.Four key ESs including food supply(FS),soil conservation(SC),water conservation(WC),and habitat quality(HQ)in BLJW in 1990,2002,and 2016 were mapped to analyze the scale effects at the watershed,county,and township scales.The results indicated varying scale-related temporal and spatial relationships among FS,SC,WC,and HQ.The trade-offs between FS-SC and FS-WC initially increased and then decreased during 1990-2002 and 2002-2016,respectively,while the trade-offs between SC-WC,SC-HQ,HQ-WC,and HQ-FS first decreased and then increased at the same period.The magnitudes of the trade-offs among the four ESs are in the order of watershed scale>township scale>county scale.Among the major land-use types in BLJW,the trade-offs between WC-FS and between HQ-FS in farmland and grassland were higher than those of other land uses.There is a strong trade-off between SC-HQ in forestland and a weak trade-off between SC-WC in farmland and grassland.The trade-offs between the six ESs pairs varied and were scale-dependent mainly due to spatial heterogeneity in the landscape and in human activities.Understanding the ESs trade-offs at the watershed,county,and township scales provides a scientific basis for the formulation of environmental management strategies at appropriate spatial scales.At the BLJW watershed scale,more attention should be paid on farmland and grassland planning and its management,also,forestland should be enlarged if possible.At the county and township scales,land consolidation and planning should be paid more attention to develop ecological agricultural tourism and multi-functional landscapes for strategic spatial planning and integrated watershed management.展开更多
The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of curr...The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of current densities and the recombination rate in organic single layer devices is presented taking into account the charge injection process at each electrode, charge transport and recombination in organic layer. The calculated results indicate that efficient single-layer devices are possible by adjusting the barrier heights at two electrodes and the carrier mobilities. Lowering the barrier heights can improve the electroluminescent(EL) efficiency pronouncedly in many cases, and efficient devices are still possible using an ohmic contact to inject the low mobility carrier, and a contact limited contact to inject the high mobility carrier. All in all, high EL efficiency needs to consider sufficient recombination, enough injected carriers and well transport.展开更多
The transmission properties of one-dimensional photonie crystals （1DPCs） containing anisotropic metamaterials are theoretically studied. It is shown that the 1DPCs can possess a similar zero average index （zero-n）...The transmission properties of one-dimensional photonie crystals （1DPCs） containing anisotropic metamaterials are theoretically studied. It is shown that the 1DPCs can possess a similar zero average index （zero-n） gaps, the edges of zero-~ gap are weakly dependent on the incident angles, scale length and the polarization of the electromagnetic wave. When an impurity is introduced, a defect mode appears inside the zeron gap with a very weak dependence on incident angles and sealing. It is found that in such photonic crystals, a transmitted Gaussian pulse with its carrier frequency lying in the lower gap edge, in the defect mode and in the bandgap, can experience a positive or negative group delay and hence a subluminal, ultra.slow or superluminal propagation with small distortions. These properties of the photonic crystals have potential applications in the transfer of information.展开更多
生态系统服务研究已成为生态学、地理学、环境经济学等学科的热点议题.基于Citespace与Carrot2文献分析工具,以Web of Science为数据源,本文分析了1997—2018年生态系统服务研究热点与发展趋势.结果表明:近20年来,生态系统服务研究文献...生态系统服务研究已成为生态学、地理学、环境经济学等学科的热点议题.基于Citespace与Carrot2文献分析工具,以Web of Science为数据源,本文分析了1997—2018年生态系统服务研究热点与发展趋势.结果表明:近20年来,生态系统服务研究文献数量、研究机构均明显增加,主要的发文国家有美国、英国、德国、中国、澳大利亚,其中,美国的发文量与影响力最大.综合来看,中国在生态系统服务研究方面起步较晚,近期发展势头迅猛,科研产出量显著增加;但与国际相比还存在一定差距,文献质量及影响力还有待提高,国际合作交流有待提升.生态系统服务的热点主要集中在评估方法与模型、气候变化、生物多样性、土地利用变化、权衡与协同关系、科学研究决策及管理6方面.未来亟需加强的研究方向主要包括:生态系统服务的形成机制、评估指标及方法与模型、权衡与协同关系的时空动态与影响因素、生态系统服务与人类福祉的耦合关系、面向可持续发展的生态系统服务科学研究与决策管理等.展开更多
文摘采用自制的序批式"厌氧发酵产氢反应装置",以餐厨垃圾为发酵底物,污水处理厂剩余污泥为接种微生物,初始pH为7.0、温度为37℃条件下,研究餐厨垃圾和剩余污泥不同质量混合比对厌氧发酵产氢的影响。结果表明,餐厨垃圾和剩余污泥质量比为4∶1时,厌氧发酵产氢效果最好,累积产氢量和单位产氢量(以VS计)最大,分别为252.2 m L和53.3 m L/g,TS和VS的去除率分别为20.9%和13.8%。
基金supported by the National Key Technologies R&D Program of China during the 12th Five-Year Plan period (2011BAD16B15 and 2012BAD14B03)
文摘To make recycling utilization of organic materials produced in various agricultural systems, five kinds of organic materials were applied in a field test, including crop straw （CS）, biogas residue （BR）, mushroom residue （MR）, wine residue （WR）, pig manure （PM）, with a mineral fertilizer （CF） and a no-fertilizer （CK） treatment as a control. Our objectives were： i） to quantify the effects of organic materials on soil C and N accumulation; ii） to evaluate the effects of organic materials on soil aggregate stability, along with the total organic carbon （TOC）, and N in different aggregate fractions; and iii） to assess the relationships among the organic material components, soil C and N, and C, N in aggregate fractions. The trial was conducted in Wuqiao County, Hebei Province, China. The organic materials were incorporated at an equal rate of C, and combined with a mineral fertilizer in amounts of 150 kg N ha^-1, 26 kg P ha^-1 and 124 kg K ha-1 respectively during each crop season of a wheat-maize rotation system. The inputted C quantity of each organic material treatment was equivalent to the total amount of C contained in the crop straw harvested in CS treatement in the previous season. TOC, N, water-stable aggregates, and aggregate-associated TOC and N were investigated. The results showed that organic material incorporation increased soil aggregation and stabilization. On average, the soil macroaggregate proportion increased by 14%, the microaggregate proportion increased by 3%, and mean-weight diameter （MWD） increased by 20%. TOC content followed the order of PM〉WR〉MR〉BR〉CS〉CK〉CF; N content followed the order WR〉PM〉MR〉BR〉CS〉CF〉CK. No significant correlation was found between TOC, N, and the quality of organic material. Soil silt and clay particles contained the largest part of TOC, whereas the small macroaggregate fraction was the most sensitive to organic materials. Our results indicate that PM and WR exerted better effects on soil C and N accumulation, followed by MR and BR, suggesting that organic materials from ex situ farmland could promote soil quality more as compared to straw returned in situ.
基金This work was supported by the National Natural Science Foundation of China(Grant No.41771196)the Second Tibetan Plateau Scientific Expedition and Research(No.2019QZKK0603)National Key R&D Program of China(No.2016YFC0501701).
文摘Understanding the trade-offs among ecosystem services(ESs)at multiple scales is a key challenge to effective environmental management.However,the scale effect of ESs trade-offs in the Qinghai-Tibetan Plateau(QTP)has received little attention.This study investigated the scale effects of ESs trade-offs in Bailongjiang Watershed(BLJW),a typical transitional ecotone from the Loess Plateau to the Tibetan Plateau with multiple ESs,intensive human activities and frequent geological disasters in the Eastern Margin of the QTP,China.Four key ESs including food supply(FS),soil conservation(SC),water conservation(WC),and habitat quality(HQ)in BLJW in 1990,2002,and 2016 were mapped to analyze the scale effects at the watershed,county,and township scales.The results indicated varying scale-related temporal and spatial relationships among FS,SC,WC,and HQ.The trade-offs between FS-SC and FS-WC initially increased and then decreased during 1990-2002 and 2002-2016,respectively,while the trade-offs between SC-WC,SC-HQ,HQ-WC,and HQ-FS first decreased and then increased at the same period.The magnitudes of the trade-offs among the four ESs are in the order of watershed scale>township scale>county scale.Among the major land-use types in BLJW,the trade-offs between WC-FS and between HQ-FS in farmland and grassland were higher than those of other land uses.There is a strong trade-off between SC-HQ in forestland and a weak trade-off between SC-WC in farmland and grassland.The trade-offs between the six ESs pairs varied and were scale-dependent mainly due to spatial heterogeneity in the landscape and in human activities.Understanding the ESs trade-offs at the watershed,county,and township scales provides a scientific basis for the formulation of environmental management strategies at appropriate spatial scales.At the BLJW watershed scale,more attention should be paid on farmland and grassland planning and its management,also,forestland should be enlarged if possible.At the county and township scales,land consolidation and planning should be paid more attention to develop ecological agricultural tourism and multi-functional landscapes for strategic spatial planning and integrated watershed management.
基金Excellent Youth Foundation of Hunan Province(03JJY1008) Science Foundation for Post-doctorate of China(2004035083) Science Foundation of Central South University( 0601059)
文摘The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of current densities and the recombination rate in organic single layer devices is presented taking into account the charge injection process at each electrode, charge transport and recombination in organic layer. The calculated results indicate that efficient single-layer devices are possible by adjusting the barrier heights at two electrodes and the carrier mobilities. Lowering the barrier heights can improve the electroluminescent(EL) efficiency pronouncedly in many cases, and efficient devices are still possible using an ohmic contact to inject the low mobility carrier, and a contact limited contact to inject the high mobility carrier. All in all, high EL efficiency needs to consider sufficient recombination, enough injected carriers and well transport.
基金Supported by the National Natural Science Foundation of China under Grant No 10904032, the Natural Science Foundation of Henan Educational Committee （No 2010B140005）, the PhD Foundation of the Ministry of Education of China under Grant No 20090072110052, the Doctoral Foundation （No B2009-88）, the Youth Fund （No Q2008-49） and the Program for Youthful Key Teachers （No 649144） in Henan Polytechnic University
文摘The transmission properties of one-dimensional photonie crystals （1DPCs） containing anisotropic metamaterials are theoretically studied. It is shown that the 1DPCs can possess a similar zero average index （zero-n） gaps, the edges of zero-~ gap are weakly dependent on the incident angles, scale length and the polarization of the electromagnetic wave. When an impurity is introduced, a defect mode appears inside the zeron gap with a very weak dependence on incident angles and sealing. It is found that in such photonic crystals, a transmitted Gaussian pulse with its carrier frequency lying in the lower gap edge, in the defect mode and in the bandgap, can experience a positive or negative group delay and hence a subluminal, ultra.slow or superluminal propagation with small distortions. These properties of the photonic crystals have potential applications in the transfer of information.
文摘生态系统服务研究已成为生态学、地理学、环境经济学等学科的热点议题.基于Citespace与Carrot2文献分析工具,以Web of Science为数据源,本文分析了1997—2018年生态系统服务研究热点与发展趋势.结果表明:近20年来,生态系统服务研究文献数量、研究机构均明显增加,主要的发文国家有美国、英国、德国、中国、澳大利亚,其中,美国的发文量与影响力最大.综合来看,中国在生态系统服务研究方面起步较晚,近期发展势头迅猛,科研产出量显著增加;但与国际相比还存在一定差距,文献质量及影响力还有待提高,国际合作交流有待提升.生态系统服务的热点主要集中在评估方法与模型、气候变化、生物多样性、土地利用变化、权衡与协同关系、科学研究决策及管理6方面.未来亟需加强的研究方向主要包括:生态系统服务的形成机制、评估指标及方法与模型、权衡与协同关系的时空动态与影响因素、生态系统服务与人类福祉的耦合关系、面向可持续发展的生态系统服务科学研究与决策管理等.
