Nanocrystalline Mg2Ni-type alloys with nominal compositions of Mg20Ni10–xCux(x=0,1,2,3,4,mass fraction,%) were synthesized by rapid quenching technique.The microstructures of the as-cast and quenched alloys were char...Nanocrystalline Mg2Ni-type alloys with nominal compositions of Mg20Ni10–xCux(x=0,1,2,3,4,mass fraction,%) were synthesized by rapid quenching technique.The microstructures of the as-cast and quenched alloys were characterized by XRD,SEM and HRTEM.The electrochemical hydrogen storage performances were tested by an automatic galvanostatic system.The hydriding and dehydriding kinetics of the alloys were measured using an automatically controlled Sieverts apparatus.The results show that all the as-quenched alloys hold the typical nanocrystalline structure and the rapid quenching does not change the major phase Mg2Ni.The rapid quenching significantly improves the electrochemical hydrogen storage capacity of the alloys,whereas it slightly impairs the cycling stability of the alloys.Additionally,the hydrogen absorption and desorption capacities of the alloys significantly increase with rising quenching rate.展开更多
The conventional fast converted-wave imaging method directly uses backward Pand converted S-wavefield to produce joint images. However, this image is accompanied by strong background noises, because the wavefi elds in...The conventional fast converted-wave imaging method directly uses backward Pand converted S-wavefield to produce joint images. However, this image is accompanied by strong background noises, because the wavefi elds in all propagation directions contribute to it. Given this issue, we improve the conventional imaging method in the two aspects. First, the amplitude-preserved P-and S-wavef ield are obtained by using an improved space-domain wavef ield separation scheme to decouple the original elastic wavef ield. Second, a convertedwave imaging condition is constructed based on the directional-wavefield separation and only the wavefields propagating in the same directions used for cross-correlation imaging, resulting in effectively eliminating the imaging artifacts of the wavefields with different directions;Complex-wavefi eld extrapolation is adopted to decompose the decoupled P-and S-wavefield into directional-wavefields during backward propagation, this improves the eff iciency of the directional-wavef ield separation. Experiments on synthetic data show that the improved method generates more accurate converted-wave images than the conventional one. Moreover, the improved method has application potential in micro-seismic and passive-source exploration due to its source-independent characteristic.展开更多
This exploratory research studied the contribution of homegardens to household income generation. In Burkina Faso, the Bieha department was purposively selected. The initial rapid rural appraisal was complemented by a...This exploratory research studied the contribution of homegardens to household income generation. In Burkina Faso, the Bieha department was purposively selected. The initial rapid rural appraisal was complemented by a household survey. Tools of data collection included observation, key informant interview, and focus group discussion. For the survey, eighty households were selected based on systematic sampling. Data was collected by individual interviews at household level, and for statistical calculations, the households were subsequently categorized as small, medium and commercial based on their homegarden size. It was found that all the surveyed households managed homegardens composed of trees, crops and animals. Majority of the farmers （43%） belonged to the small category due to land constraints. Generally, farms contributed more income than the plant component of homegardens. However, when the livestock component of homegardens was added, homegardens became far more important than farms and accounted for over 60% of income generation for all categories. It can be concluded that homegardens are important to rural people for food and cash income.展开更多
MRSI plays a more and more important role in clinical application. In this paper,we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI,the data reconstruct...MRSI plays a more and more important role in clinical application. In this paper,we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI,the data reconstruction using FFT is simple. But the data acquisition is very time consuming and thus prohibitive in clinical settings. Up to now,the MRSI technologies based on echo-planar, spiral trajectories and sensitivity encoding are the fastest in data acquisition,but their data reconstruction is complex. EPSI reconstruction uses shift of odd and even echoes. Spiral SI uses gridding FFT. SENSE-SI,a new approach to reducing the acquisition time,uses the distinct spatial sensitivities of the individual coil elements to recover the missing encoding information. These improvements in data acquisition and image reconstruction provide a potential value of metabolic imaging as a clinical tool.展开更多
An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this stud...An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this study. Ten marker compounds were simultaneously quantified, including 5-caffeoylquinic acid （5-CQA）, 3-caffeoylquinic acid （3-CQA）, 4-caffeoylquinic acid （4-CQA）, 1-caffeoylquinic acid （1-CQA）, 3,5-dicaffeoylquinic acid （3,5-diCQA）, 4,5-dicaffeoylquinic acid （4,5-diCQA）, 3,4-dicaffeoylquinic acid （3,4-diCQA）, astragalin, kaempferol-3,7-di-O-glucoside and （±）eriodictyol-7-O-β-D-glucuronide. Chromatography was performed on a Kromasil 100-2.5C18 （100 mm×2.1 mm, 2.5 μm） C18 column with gradient elution. The mobile phases consisted of 0.1% formic acid/water （A） and 0.1% formic acid/methanol （B）. The detection wavelength was set at 326 nm and the flow rate was 0.4 mL/min. Ten components were separated well with good linearity （r2〉0.9998）, precision, repeatability, stability. The recovery was in the range of 99.08%-102.77%. The results showed that the content determination using RP-UFLC-DAD fingerprint technique provides an efficient, sensitive, accurate and rapid analytical method for quality assessment ofP. petiolosa （Christ） Ching. Cluster analysis and principal components analysis were successfully applied to analyze 20 samples, the results revealed that the method was efficient and authentic to distinguish producing areas and the source of P. petiolosa （Christ） Ching. Keywords： Pyrrosiapetiolosa （Christ） Ching, Caffeoylquinic acids, Flavonoids, Multicomponent determination, UFLC展开更多
Hierarchical porous zeolitic imidazolate frameworks （ZIFs） have potential for adsorption, catalysis and chemical sensing applications. Ultrafast synthesis of ZIFs at room temperature and pressure is particularly des...Hierarchical porous zeolitic imidazolate frameworks （ZIFs） have potential for adsorption, catalysis and chemical sensing applications. Ultrafast synthesis of ZIFs at room temperature and pressure is particularly desirable for large-scale industrial production. Here, we developed a green and versatile method using organic amines as supramolecular templates （organic amine-template） to rapidly synthesize hierarchical porous ZIFs （ZIF-8, ZIF-61 and ZIF-90） at room temperature and pressure. The synthesis time was reduced dramatically to within 1 min, and the resulting ZIFs had multimodal hierarchical porous structures with mesopores/ macropores interconnected with micropores. Notably, the space-time yield （STY） of hierarchical porous ZIF-8 was up to 1.29×10^4 kg m^-3 d^-1, which is more than three times higher than that reported using other methods. Furthermore, the morphologies and porosities of the produced ZIFs could be readily tuned by controlling the synthesis time or type of organic amine. The organic amine played two roles in the synthesis： （1） a protonation agent to deprotonate organic ligands, facilitating the formation of ZIF crystals, and （2） an structure directing agent to direct mesopore/macropore formation. The resulting hierarchical porous ZIF-8 exhibited enhanced uptake capacities and diffusion rates for guest molecules relative to its microporous counterpart. This work provides a new direction for the green and efficient synthesis of various hierarchical porous ZIFs with high STYs for a wide range of applications.展开更多
基金Project(2007AA03Z227) supported by High-tech Research and Development Program of ChinaProjects(50871050,50701011) supported by the National Natural Science Foundation of China+1 种基金Project(200711020703) supported by the Natural Science Foundation of Inner Mongolia,ChinaProject(NJzy08071) supported by High Education Science Research Project of Inner Mongolia,China
文摘Nanocrystalline Mg2Ni-type alloys with nominal compositions of Mg20Ni10–xCux(x=0,1,2,3,4,mass fraction,%) were synthesized by rapid quenching technique.The microstructures of the as-cast and quenched alloys were characterized by XRD,SEM and HRTEM.The electrochemical hydrogen storage performances were tested by an automatic galvanostatic system.The hydriding and dehydriding kinetics of the alloys were measured using an automatically controlled Sieverts apparatus.The results show that all the as-quenched alloys hold the typical nanocrystalline structure and the rapid quenching does not change the major phase Mg2Ni.The rapid quenching significantly improves the electrochemical hydrogen storage capacity of the alloys,whereas it slightly impairs the cycling stability of the alloys.Additionally,the hydrogen absorption and desorption capacities of the alloys significantly increase with rising quenching rate.
基金supported by the National Science and Technology Major Project of China(No.2017ZX05018-005)National Natural Science Foundation of China(No.41474110)
文摘The conventional fast converted-wave imaging method directly uses backward Pand converted S-wavefield to produce joint images. However, this image is accompanied by strong background noises, because the wavefi elds in all propagation directions contribute to it. Given this issue, we improve the conventional imaging method in the two aspects. First, the amplitude-preserved P-and S-wavef ield are obtained by using an improved space-domain wavef ield separation scheme to decouple the original elastic wavef ield. Second, a convertedwave imaging condition is constructed based on the directional-wavefield separation and only the wavefields propagating in the same directions used for cross-correlation imaging, resulting in effectively eliminating the imaging artifacts of the wavefields with different directions;Complex-wavefi eld extrapolation is adopted to decompose the decoupled P-and S-wavefield into directional-wavefields during backward propagation, this improves the eff iciency of the directional-wavef ield separation. Experiments on synthetic data show that the improved method generates more accurate converted-wave images than the conventional one. Moreover, the improved method has application potential in micro-seismic and passive-source exploration due to its source-independent characteristic.
文摘This exploratory research studied the contribution of homegardens to household income generation. In Burkina Faso, the Bieha department was purposively selected. The initial rapid rural appraisal was complemented by a household survey. Tools of data collection included observation, key informant interview, and focus group discussion. For the survey, eighty households were selected based on systematic sampling. Data was collected by individual interviews at household level, and for statistical calculations, the households were subsequently categorized as small, medium and commercial based on their homegarden size. It was found that all the surveyed households managed homegardens composed of trees, crops and animals. Majority of the farmers （43%） belonged to the small category due to land constraints. Generally, farms contributed more income than the plant component of homegardens. However, when the livestock component of homegardens was added, homegardens became far more important than farms and accounted for over 60% of income generation for all categories. It can be concluded that homegardens are important to rural people for food and cash income.
基金National NaturalScinece Foundation of China.Grant number:30 0 70 336.U niversity FoundationofHUST.Grant number:0 10 1170 0 5 4
文摘MRSI plays a more and more important role in clinical application. In this paper,we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI,the data reconstruction using FFT is simple. But the data acquisition is very time consuming and thus prohibitive in clinical settings. Up to now,the MRSI technologies based on echo-planar, spiral trajectories and sensitivity encoding are the fastest in data acquisition,but their data reconstruction is complex. EPSI reconstruction uses shift of odd and even echoes. Spiral SI uses gridding FFT. SENSE-SI,a new approach to reducing the acquisition time,uses the distinct spatial sensitivities of the individual coil elements to recover the missing encoding information. These improvements in data acquisition and image reconstruction provide a potential value of metabolic imaging as a clinical tool.
基金Study of Safety Testing Techniques and Standards on New Traditional Chinese Drug(National Key Science and Technology Special Projects,Grant No.2014ZX09304307-001-001)
文摘An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this study. Ten marker compounds were simultaneously quantified, including 5-caffeoylquinic acid （5-CQA）, 3-caffeoylquinic acid （3-CQA）, 4-caffeoylquinic acid （4-CQA）, 1-caffeoylquinic acid （1-CQA）, 3,5-dicaffeoylquinic acid （3,5-diCQA）, 4,5-dicaffeoylquinic acid （4,5-diCQA）, 3,4-dicaffeoylquinic acid （3,4-diCQA）, astragalin, kaempferol-3,7-di-O-glucoside and （±）eriodictyol-7-O-β-D-glucuronide. Chromatography was performed on a Kromasil 100-2.5C18 （100 mm×2.1 mm, 2.5 μm） C18 column with gradient elution. The mobile phases consisted of 0.1% formic acid/water （A） and 0.1% formic acid/methanol （B）. The detection wavelength was set at 326 nm and the flow rate was 0.4 mL/min. Ten components were separated well with good linearity （r2〉0.9998）, precision, repeatability, stability. The recovery was in the range of 99.08%-102.77%. The results showed that the content determination using RP-UFLC-DAD fingerprint technique provides an efficient, sensitive, accurate and rapid analytical method for quality assessment ofP. petiolosa （Christ） Ching. Cluster analysis and principal components analysis were successfully applied to analyze 20 samples, the results revealed that the method was efficient and authentic to distinguish producing areas and the source of P. petiolosa （Christ） Ching. Keywords： Pyrrosiapetiolosa （Christ） Ching, Caffeoylquinic acids, Flavonoids, Multicomponent determination, UFLC
基金supported by the National Natural Science Foundation of China (21576094)SRFDP (20130172110012)the Fundamental Research Funds for the Central Universities (2015ZM046)
文摘Hierarchical porous zeolitic imidazolate frameworks （ZIFs） have potential for adsorption, catalysis and chemical sensing applications. Ultrafast synthesis of ZIFs at room temperature and pressure is particularly desirable for large-scale industrial production. Here, we developed a green and versatile method using organic amines as supramolecular templates （organic amine-template） to rapidly synthesize hierarchical porous ZIFs （ZIF-8, ZIF-61 and ZIF-90） at room temperature and pressure. The synthesis time was reduced dramatically to within 1 min, and the resulting ZIFs had multimodal hierarchical porous structures with mesopores/ macropores interconnected with micropores. Notably, the space-time yield （STY） of hierarchical porous ZIF-8 was up to 1.29×10^4 kg m^-3 d^-1, which is more than three times higher than that reported using other methods. Furthermore, the morphologies and porosities of the produced ZIFs could be readily tuned by controlling the synthesis time or type of organic amine. The organic amine played two roles in the synthesis： （1） a protonation agent to deprotonate organic ligands, facilitating the formation of ZIF crystals, and （2） an structure directing agent to direct mesopore/macropore formation. The resulting hierarchical porous ZIF-8 exhibited enhanced uptake capacities and diffusion rates for guest molecules relative to its microporous counterpart. This work provides a new direction for the green and efficient synthesis of various hierarchical porous ZIFs with high STYs for a wide range of applications.
