Electrochemical CO_(2)reduction to formate is a promising approach to store renewable electricity and utilize CO_(2).Tin oxide catalysts are efficient catalysts for this process,while the mechanisms underneath,especia...Electrochemical CO_(2)reduction to formate is a promising approach to store renewable electricity and utilize CO_(2).Tin oxide catalysts are efficient catalysts for this process,while the mechanisms underneath,especially the existence and role of oxidized tin species under CO2 electroreduction conditions remain unclear.In this work,we provide strong evidence on the presence of oxidized tin species on both SnO_(2)and Sn during CO_(2)reduction via in situ surface‐enhanced Raman spectroscopy,while in different nature.Reactivity measurements show similar activity and selectivity to formate production on SnO_(2)and Sn catalysts.Combined analysis of Raman spectra and reactivity results suggests that Sn(IV)and Sn(II)oxide species are unlikely the catalytic species in CO_(2)electroreduction to formate.展开更多
A serological survey of Toxoplasma gondii was conducted using LAT （Latex Agglutination Test） on 205 sera collected from working horses and donkeys in Khartoum State, Sudan. The overall sero-prevalence of the investi...A serological survey of Toxoplasma gondii was conducted using LAT （Latex Agglutination Test） on 205 sera collected from working horses and donkeys in Khartoum State, Sudan. The overall sero-prevalence of the investigated equines was 32.7%. Antibodies to T. gondii were found in 38% of 100 horses and 27.6% of 105 donkeys. The titers were 1：2 （4 heads）, 1：4 （11 heads）, 1：8 （13 heads）, 1：16 （17 heads）, 1：32 （5 heads）, 1：64 （10 donkeys） and 1：128 （7 donkeys）. Neither the area nor animal species showed significant differences between the investigated groups. However, age was reported to show significant （P 〈 0.05） effect on equine toxoplasmosis in the Sudan. This is the first report on equine toxoplasmosis in the Sudan.展开更多
Photocatalytic oxidative organic reactions are important synthetic transformations,and research on reaction selectivity by reactive oxygen species(ROS)is significant.To date,however,there has rarely been any focus on ...Photocatalytic oxidative organic reactions are important synthetic transformations,and research on reaction selectivity by reactive oxygen species(ROS)is significant.To date,however,there has rarely been any focus on the directed generation of ROSs.Herein,we report the first identification of tunable molecular oxygen activation induced by polymeric conjugation in nonmetallic conjugated microporous polymers(CMP).The conjugation between these can be achieved by the introduction of alkynyl groups.CMP-A with an alkynyl bridge facilitates the intramolecular charge mobility while CMP-D,lacking an alkynyl group enhances the photoexcited carrier build-up on the surface from diffusion.These different processes dominate the directed ROS generation of the superoxide radical(·O_(2)^(-))and singlet oxygen(^(1)O_(2)),respectively.This theory is substantiated by the different performances of these CMPs in the aerobic oxidation of sulfides and the dehydrogenative coupling of amines,and could provide insight into the rational design of CMPs for various heterogeneous organic photosynthesis.展开更多
The Bale Mountains of Ethiopia represent the world＇s largest continuous extent of afroalpine habitat. With a peak combined density of over 8000 individuals/km2, the endemic giant mole rat Tachyoryctes macrocephalus, ...The Bale Mountains of Ethiopia represent the world＇s largest continuous extent of afroalpine habitat. With a peak combined density of over 8000 individuals/km2, the endemic giant mole rat Tachyoryctes macrocephalus, Blick＇s grass rat Arvi- canthis blicki and the brush-furred mouse Lophuromys melanonyx are the dominant wild herbivores within this ecosystem and may be affected by the presence of high densities of domestic livestock. The purpose of this study was to establish whether these endemic rodent populations could respond to the removal of grazing pressure inside three 0.25 hectare livestock exclosures （paired with grazed control plots） and to determine whether such response was mediated through concomitant changes in the vegetation structure. We hypothesised that livestock grazing negatively affects endemic rodent populations through competition or increased predation risk and we predicted an increase in rodent biomass following the removal of grazing pressure. We found no evidence of rodent populations responding to the removal of livestock after fourteen months. The short-term nature of the ex- perimental design, environmental fluctuations and the ecosystem＇s inherent stochasticity may explain the apparent lack of a sig- nificant response. However, while this study is inconclusive, it emphasises the need for more long-term experimental investiga- tions to assess the effects of domestic grazers on vegetation and on dependent communities. The effects of rapidly increasing livestock numbers in the Bale Mountains will require continued close monitoring of vegetation and endemic animal communities as the afroalpine is altered by external biotic and abiotic forces .展开更多
Phenotypic plasticity is often an adaptation of organisms to cope with temporally or spatially heter- ogenous landscapes. Like other adaptations, one would predict that different species, populations, or sexes might t...Phenotypic plasticity is often an adaptation of organisms to cope with temporally or spatially heter- ogenous landscapes. Like other adaptations, one would predict that different species, populations, or sexes might thus show some degree of parallel evolution of plasticity, in the form of parallel reaction norms, when exposed to analogous environmental gradients. Indeed, one might even ex- pect parallelism of plasticity to repeatedly evolve in multiple traits responding to the same gradi- ent, resulting in integrated parallelism of plasticity. In this study, we experimentally tested for paral- lel patterns of predator-mediated plasticity of size, shape, and behavior of 2 species and sexes of mosquitofish. Examination of behavioral trials indicated that the 2 species showed unique patterns of behavioral plasticity, whereas the 2 sexes in each species showed parallel responses. Fish shape showed parallel patterns of plasticity for both sexes and species, albeit males showed evidence of unique plasticity related to reproductive anatomy. Moreover, patterns of shape plasticity due to predator exposure were broadly parallel to what has been depicted for predator-mediated popula- tion divergence in other studies （slender bodies, expanded caudal regions, ventrally located eyes, and reduced male gonopodia）. We did not find evidence of phenotypic plasticity in fish size for ei- ther species or sex. Hence, our findings support broadly integrated parallelism of plasticity for sexes within species and less integrated parallelism for species. We interpret these findings with respect to their potential broader implications for the interacting roles of adaptation and constraint in the evolutionary origins of parallelism of plasticity in general.展开更多
Cobalt-based oxygenic compounds Co(OH)2,CoO and Co3 O4 are attractive for electrochemical energy storage owing to their high theoretical capacities and pseudocapacitive properties.Despite the great efforts to their co...Cobalt-based oxygenic compounds Co(OH)2,CoO and Co3 O4 are attractive for electrochemical energy storage owing to their high theoretical capacities and pseudocapacitive properties.Despite the great efforts to their compositional and morphological regulations,the performances to date are still quite limited owing to the low active surface area and sluggish charge transfer kinetics.Herein,different Co-based nanocrystals(Co-NCs)were conveniently anchored on the hierarchical nitrogen-doped carbon nanocages(hNCNCs)with high specific surface area and coexisting micro-meso-macropores to decrease the size and facilitate the charge transfer.Accordingly,a high specific capacity of1170 Fg^-1 is achieved at 2 Ag^-1 for the Co(OH)2/hNCNCs hybrid,in which the capacitance of Co(OH)2(2214 F gco(OH)2)is approaching to its theoretical maximum(2595 Fg^-1),demonstrating the high utilization of active materials by the hybridization with N-doped nanocarbons.This study also reveals that these Co-NCs store/release electrical energy via the same reversible redox reaction despite their different pristine compositions.This insight on the energy storage of Co-based nanomaterials suggests that the commonly-employed transformation of the Co-NCs from Co(OH)2 to CoO and Co3 O4 on carbon supports is unnecessary and even could be harmful to the energy storage performance.The result is instructive to develop high-energy-density electrodes from transition metal compounds.展开更多
文摘Electrochemical CO_(2)reduction to formate is a promising approach to store renewable electricity and utilize CO_(2).Tin oxide catalysts are efficient catalysts for this process,while the mechanisms underneath,especially the existence and role of oxidized tin species under CO2 electroreduction conditions remain unclear.In this work,we provide strong evidence on the presence of oxidized tin species on both SnO_(2)and Sn during CO_(2)reduction via in situ surface‐enhanced Raman spectroscopy,while in different nature.Reactivity measurements show similar activity and selectivity to formate production on SnO_(2)and Sn catalysts.Combined analysis of Raman spectra and reactivity results suggests that Sn(IV)and Sn(II)oxide species are unlikely the catalytic species in CO_(2)electroreduction to formate.
文摘A serological survey of Toxoplasma gondii was conducted using LAT （Latex Agglutination Test） on 205 sera collected from working horses and donkeys in Khartoum State, Sudan. The overall sero-prevalence of the investigated equines was 32.7%. Antibodies to T. gondii were found in 38% of 100 horses and 27.6% of 105 donkeys. The titers were 1：2 （4 heads）, 1：4 （11 heads）, 1：8 （13 heads）, 1：16 （17 heads）, 1：32 （5 heads）, 1：64 （10 donkeys） and 1：128 （7 donkeys）. Neither the area nor animal species showed significant differences between the investigated groups. However, age was reported to show significant （P 〈 0.05） effect on equine toxoplasmosis in the Sudan. This is the first report on equine toxoplasmosis in the Sudan.
基金supported by the National Natural Science Foundation of China(51902121,52073110,22071072,51872107,21975090,and 21801086)the Fundamental Research Funds for the Central Universities of China(2662018QD011,2662018PY052,and 2662019PY023)the Natural Science Foundation of Hubei Province(2019CFB322)。
文摘Photocatalytic oxidative organic reactions are important synthetic transformations,and research on reaction selectivity by reactive oxygen species(ROS)is significant.To date,however,there has rarely been any focus on the directed generation of ROSs.Herein,we report the first identification of tunable molecular oxygen activation induced by polymeric conjugation in nonmetallic conjugated microporous polymers(CMP).The conjugation between these can be achieved by the introduction of alkynyl groups.CMP-A with an alkynyl bridge facilitates the intramolecular charge mobility while CMP-D,lacking an alkynyl group enhances the photoexcited carrier build-up on the surface from diffusion.These different processes dominate the directed ROS generation of the superoxide radical(·O_(2)^(-))and singlet oxygen(^(1)O_(2)),respectively.This theory is substantiated by the different performances of these CMPs in the aerobic oxidation of sulfides and the dehydrogenative coupling of amines,and could provide insight into the rational design of CMPs for various heterogeneous organic photosynthesis.
文摘The Bale Mountains of Ethiopia represent the world＇s largest continuous extent of afroalpine habitat. With a peak combined density of over 8000 individuals/km2, the endemic giant mole rat Tachyoryctes macrocephalus, Blick＇s grass rat Arvi- canthis blicki and the brush-furred mouse Lophuromys melanonyx are the dominant wild herbivores within this ecosystem and may be affected by the presence of high densities of domestic livestock. The purpose of this study was to establish whether these endemic rodent populations could respond to the removal of grazing pressure inside three 0.25 hectare livestock exclosures （paired with grazed control plots） and to determine whether such response was mediated through concomitant changes in the vegetation structure. We hypothesised that livestock grazing negatively affects endemic rodent populations through competition or increased predation risk and we predicted an increase in rodent biomass following the removal of grazing pressure. We found no evidence of rodent populations responding to the removal of livestock after fourteen months. The short-term nature of the ex- perimental design, environmental fluctuations and the ecosystem＇s inherent stochasticity may explain the apparent lack of a sig- nificant response. However, while this study is inconclusive, it emphasises the need for more long-term experimental investiga- tions to assess the effects of domestic grazers on vegetation and on dependent communities. The effects of rapidly increasing livestock numbers in the Bale Mountains will require continued close monitoring of vegetation and endemic animal communities as the afroalpine is altered by external biotic and abiotic forces .
文摘Phenotypic plasticity is often an adaptation of organisms to cope with temporally or spatially heter- ogenous landscapes. Like other adaptations, one would predict that different species, populations, or sexes might thus show some degree of parallel evolution of plasticity, in the form of parallel reaction norms, when exposed to analogous environmental gradients. Indeed, one might even ex- pect parallelism of plasticity to repeatedly evolve in multiple traits responding to the same gradi- ent, resulting in integrated parallelism of plasticity. In this study, we experimentally tested for paral- lel patterns of predator-mediated plasticity of size, shape, and behavior of 2 species and sexes of mosquitofish. Examination of behavioral trials indicated that the 2 species showed unique patterns of behavioral plasticity, whereas the 2 sexes in each species showed parallel responses. Fish shape showed parallel patterns of plasticity for both sexes and species, albeit males showed evidence of unique plasticity related to reproductive anatomy. Moreover, patterns of shape plasticity due to predator exposure were broadly parallel to what has been depicted for predator-mediated popula- tion divergence in other studies （slender bodies, expanded caudal regions, ventrally located eyes, and reduced male gonopodia）. We did not find evidence of phenotypic plasticity in fish size for ei- ther species or sex. Hence, our findings support broadly integrated parallelism of plasticity for sexes within species and less integrated parallelism for species. We interpret these findings with respect to their potential broader implications for the interacting roles of adaptation and constraint in the evolutionary origins of parallelism of plasticity in general.
基金jointly supported by the National Key Research and Development Program of China(2017YFA0206500and 2018YFA0209103)the National Natural Science Foundation of China(21832003,21773111,51571110 and 21573107)the Fundamental Research Funds for the Central Universities(020514380126)
文摘Cobalt-based oxygenic compounds Co(OH)2,CoO and Co3 O4 are attractive for electrochemical energy storage owing to their high theoretical capacities and pseudocapacitive properties.Despite the great efforts to their compositional and morphological regulations,the performances to date are still quite limited owing to the low active surface area and sluggish charge transfer kinetics.Herein,different Co-based nanocrystals(Co-NCs)were conveniently anchored on the hierarchical nitrogen-doped carbon nanocages(hNCNCs)with high specific surface area and coexisting micro-meso-macropores to decrease the size and facilitate the charge transfer.Accordingly,a high specific capacity of1170 Fg^-1 is achieved at 2 Ag^-1 for the Co(OH)2/hNCNCs hybrid,in which the capacitance of Co(OH)2(2214 F gco(OH)2)is approaching to its theoretical maximum(2595 Fg^-1),demonstrating the high utilization of active materials by the hybridization with N-doped nanocarbons.This study also reveals that these Co-NCs store/release electrical energy via the same reversible redox reaction despite their different pristine compositions.This insight on the energy storage of Co-based nanomaterials suggests that the commonly-employed transformation of the Co-NCs from Co(OH)2 to CoO and Co3 O4 on carbon supports is unnecessary and even could be harmful to the energy storage performance.The result is instructive to develop high-energy-density electrodes from transition metal compounds.
