Biochar,a carbon-rich material derived from the thermochemical conversion of biomass under oxygenfree conditions,has emerged as a sustainable resource for radar-absorbing technologies.This study explores the productio...Biochar,a carbon-rich material derived from the thermochemical conversion of biomass under oxygenfree conditions,has emerged as a sustainable resource for radar-absorbing technologies.This study explores the production of activated biochars from end-of-life wood panels using a scalable and sustainable physical activation method with CO_(2) at different temperatures,avoiding the extensive use of corrosive chemicals and complex procedures associated with chemical or vacuum activation.Compared to conventional chemically or vacuum-activated biochars,the physically activated biochar demonstrated competitive performance while minimizing environmental impact,operational complexity,and energy consumption.Furthermore,activation at 750℃ reduces energy consumption by 14% and 28% compared to activations at 850℃ and 950℃,respectively,emphasizing the cost-effectiveness of this method for large-scale applications.The composite with 15% of biochar embedded in silicon rubber presented good electromagnetic performance,achieving a measured reflection loss(RL)of−37.2 dB at 11.3 GHz with an 8.4 mm thickness and an effective absorption bandwidth(EAB)of 1.25 GHz.These results highlight the potential of biocharsilicone rubber composites as flexible radar-absorbing materials(RAMs)for applications in electromagnetic shielding,anechoic chambers,and Internet of Things(IoT)devices.This study also shows the importance of forestry residues as sustainable precursors for producing low-cost porous carbon materials,aligning with circular economy principles and the United Nations’2030 Agenda for Sustainable Development.This work establishes a framework for scalable,cost-effective,and sustainable biochar production,addressing critical challenges in electromagnetic interference(EMI)mitigation and advancing the global adoption of green technologies.展开更多
Afforestation and reforestation are useful approaches to improve carbon sequestration. With the advent of forest plantations, growing environment conditions have become increasingly restrictive for light, soil nutrien...Afforestation and reforestation are useful approaches to improve carbon sequestration. With the advent of forest plantations, growing environment conditions have become increasingly restrictive for light, soil nutrients, and interactions between trees to acquire available resources. Tree biomass data are essential for understanding the forest carbon cycle and plant adaptations to the environment. The distribution of tree biomass depends on the sum of multiple stand conditions. The data are from a dedicated experiment with two very contrasting areas of fertility, and two planting densities, including a high density at planting in order to achieve thinning. The plant material consists of the high-performance clones of Eucalyptus urophylla × E. grandis and the reference clone E. PF1. We hypothesize that the distribution of biomass changes as the intensity of competition changes and that this is accelerated by the fertility of the sites in time. The results indicate that fertilization, planting density and clones have an impact on biomass partitioning.展开更多
In this study, the effects of Radio Electric Asymmetric Conveyer(REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with1-methyl-4-phenyl-...In this study, the effects of Radio Electric Asymmetric Conveyer(REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP),were investigated in vivo. We found that the REAC tissue optimization treatment specific for neuro-regenerative purposes(REAC TO-RGN-N) attenuated the inflammatory picture evoked by MPTP-induced nigro-striatal damage inmice, decreasing the levels of pro-inflammatory molecules and increasing anti-inflammatory mediators. Besides, there was a significant reduction of both astrocyte and microglial activation in MPTP-treated mice exposed to REAC TORGN-N. These results indicated that REAC TO-RGN-N treatment modulates the pro-inflammatory responses and reduces neuronal damage in MPTP-induced parkinsonism.展开更多
The study aimed at evaluating the natural regeneration of some characteristic species in the Loukaya peri-urban forest was carried out in Brazzaville, over three surveys of one hectare each. The botanical inventory of...The study aimed at evaluating the natural regeneration of some characteristic species in the Loukaya peri-urban forest was carried out in Brazzaville, over three surveys of one hectare each. The botanical inventory of the 23 species monitored covers the subjects of 2 ≤ d<sup>0.20</sup> < 10 cm and d<sup>1.30</sup> ≥ 10 cm. The study shows 1255 individuals of which 68.27% are 2 ≤ d<sup>0.20</sup> < 10 cm. While being tropophilic and mesophilic, this ecosystem is pauciflorous and paucispecific. The phytoecological data show that this formation, which is a link in the African dense humid forest, presents values far below those known elsewhere;while being faithful to the forests of the Cataractes Plateau. As for the rate of natural regeneration, this index is greater than or equal to 100 for 69.56% of the taxa. Sarcochores and heliophytes are the taxa that best support this natural regeneration. This high rate of regeneration would be correlated with the high level of anthropization, whose large canopy gaps are accompanied by a flow of light conducive to the installation of seedlings.展开更多
The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The g...The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.展开更多
A study of the typology of soils and floristic diversity was carried out in the forest of the “Cité Scientifique” of Brazzaville. The study aimed to assess the influence of soil cover on the distribution of tax...A study of the typology of soils and floristic diversity was carried out in the forest of the “Cité Scientifique” of Brazzaville. The study aimed to assess the influence of soil cover on the distribution of taxa. The study covers 18 plots of 625 m2 each, distributed in different soil profiles. The floristic inventory concerns the measurement of diameter of trees with dbh ≥ 10 cm and the counting of herbaceous and shrubs of dbh < 10 cm. The floristic composition reveals a total of 129 plant species distributed in 48 families dominated by Fabaceae and a preponderance of pioneer taxa. The Jaccard coefficients of similarity reveal a low degree of homology of woody plots, whereas for the flora as a whole, the floristic composition is heterogeneous. The Shannon biological diversity index of ligneous varies from 0.6 to 2, against a maximum diversity of 0.69 to 3. The Pielou index of ligneous (0.5 to 0.9) does not reveal any dominance. Soil cover consists of ferrallitic and podzol soils. Their texture is sandy, weakly structured, fragmentary polyhedral throughout the profile, but lumpy and/or nuciform at the surface and sub angular in depth. The porosity decreases proportionally with the depth and thickness of the horizons. The floristic analysis presents an ecosystem with a low degree of diversification for a high floristic richness. The preponderance of anthropization markers is a proof of its very advanced state of disturbance. The study shows that soil cover does not influence the distribution of timber. Indeed, the establishment and development of pioneer species are less prone to soil properties.展开更多
The soil seed bank is an important source of restoration and resilience of disturbed ecosystems. This study evaluates the regeneration potential through the soil seed bank of the shrub savannas of Nguela and Mbe in or...The soil seed bank is an important source of restoration and resilience of disturbed ecosystems. This study evaluates the regeneration potential through the soil seed bank of the shrub savannas of Nguela and Mbe in order to predict the eventual dynamics. Three plots of 0.25 ha subdivided into four sub-plots of 0.015 ha have been installed in each savannah. In total, 48 samples of each savannah, i.e. 96 samples of both savannas, have been taken from the soil layers, 0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm. Species diversity and abundance of the soil seed bank have been assessed after germination. The results reveal 167 seedlings belonging to 23 species in the Mbe savannah and 144 seedlings belonging to 14 species in the Nguela savannah. The total densities of the germinated seeds were respectively 463.63 seeds/m<sup>2</sup> and 400 seeds/m<sup>2</sup>. Nevertheless, the 20 cm deep layers have illustrated themselves compared to the superficial layers with densities of 16.29 seeds/m<sup>2</sup> and 21.66 seeds/m<sup>2</sup>, respectively, in the savannas of Mbe and Nguela. Herbaceous species largely dominated, with percentages of 91% and 100%, respectively, in the savannas of Mbe and Nguela. Alone, the Trema orientalis (L.) Blume species has been identified as woody species in the Mbe savannah. The greatest specific richness has been obtained in the first five centimeters of soil, with 21.73% and 28.57% of exclusive species, respectively, in the savannas of Mbe and Nguela. The results reveal that restoration through the soil seed bank would be limited to a single woody species found (T. orientalis). Consequently, the study suggests silvicultural interventions based on planting or enrichment techniques for sustainably managed savannas exposed to anthropogenic disturbances.展开更多
Reconstituted wood panels have several advantages in terms of ease of manufacturing,but their shorter life span results in a huge amount of reconstituted wood panels being discarded in sorting centers yearly.Currently...Reconstituted wood panels have several advantages in terms of ease of manufacturing,but their shorter life span results in a huge amount of reconstituted wood panels being discarded in sorting centers yearly.Currently,the most common approach for dealing with this waste is incineration.In this study,reconstituted wood panels were converted into activated biochar through a two-step thermochemical process:(i)biochar production using pilot scale fast pyrolysis at 250 kg/h and 450℃;and(ii)a physical activation at three temperatures(750℃,850℃ and 950℃)using an in-house activation furnace(1 kg/h).Results showed that the first stage removed about 66% of the nitrogen from the wood panels in the form of NO,NH3,and trimethylamine,which were detected in small amounts compared to emitted CO_(2).Compared to other types of thermochemical conversion methods(e.g.,slow pyrolysis),isocyanic acid and hydrogen cyanide were not detected in this study.The second stage produced activated biochar with a specific surface area of up to 865 m^(2)/g at 950℃.The volatile gases generated during activation were predominantly composed of toluene and benzene.This two-step process resulted in nitrogen-rich carbon in the form of pyrrolic and pyridinic nitrogen.Activated biochars were then evaluated for their SO_(2) retention performance and showed an excellent adsorption capacity of up to 2140 mg/g compared to 65 mg/g for a commercial activated carbon(889 m^(2)/g).End-of-life reconstituted wood panels and SO_(2) gas are problematic issues in Canada where the economy largely revolves around forestry and mining industries.展开更多
The soil seed bank is a key indicator of natural regeneration and/or forests resilience after disturbances. This study evaluates the soil seed bank characteristics in two Marantaceae forests plots of Ouesso Forest Ind...The soil seed bank is a key indicator of natural regeneration and/or forests resilience after disturbances. This study evaluates the soil seed bank characteristics in two Marantaceae forests plots of Ouesso Forest Industry (IFO) in north of the Republic of Congo. In each plot, 12 samples were taken per soil layers (0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm deep). Diversity and abundance seed were estimated after germination of soil samples. The results revealed 101 seedlings belonging to 17 species for plot 1 and 129 seedlings belonging to 15 species for plot 2. The average densities of germinated seeds were respectively 281 seedling/m<sup>2</sup> and 358 seedling/m<sup>2</sup>. There were no significant differences (p > 0.05) between the mean densities of the two plots. Herbaceous species dominated with percentages of 71% and 73%, respectively in plot 1 and plot 2. Both plots showed potential of regeneration from the soil seed bank. However, this potential seems higher in plot 2. Pioneer taxa were more abundant in the soil seed bank of plot 1 (4 woody pioneer species) than in plot 2 (1 woody pioneer species). The highest species richness was obtained in the first two soil layers (0 - 5 cm and 5 - 10 cm depth) while 25% of species were exclusively found in the deepest layer (15 - 20 cm) in plot 2. The study suggests silvicultural interventions based on planting or enrichment techniques for contribute to sustainable management of Marantaceae forests that could prevent the growth and development of seedlings.展开更多
Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-log...Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population.展开更多
The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in...The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m<sup>2</sup> and 1742 seedlings/m<sup>2</sup>. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m<sup>2</sup> and 4 seedlings/m<sup>2</sup>, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.展开更多
Continuous adaptation to changing environmental conditions is an evolutionary trait that many plant species have acquired to cope with biotic and abiotic stresses.Several plant families have adapted to synthesize a wi...Continuous adaptation to changing environmental conditions is an evolutionary trait that many plant species have acquired to cope with biotic and abiotic stresses.Several plant families have adapted to synthesize a wide range of specialized metabolites,many of which serve protective functions.The significant biological activities of these specialized metabolites have been exploited by humans for pharmacological purposes.Notable examples include the monoterpenoid indole alkaloids vinblastine and vincristine fromtheMadagascar periwinkle(Apocynaceae)and the sesquiterpene lactone artemisinin from the annual wormwood(Asteraceae),which are used to treat cancers and malaria,respectively.The clinical importance of these compounds and their potential ecophysiological roles have motivated researchers to elucidate the biosynthetic pathways of many specialized metabolites.展开更多
Dear Editor,Although primary metabolism is assumed to be highly evolutionarily conserved in plants,specialized metabolism is more prone to active diversification to allow adaptation to changing environments.Notably,th...Dear Editor,Although primary metabolism is assumed to be highly evolutionarily conserved in plants,specialized metabolism is more prone to active diversification to allow adaptation to changing environments.Notably,this diversification results from core metabolic enzyme hijacking or gene duplication events that are highly prevalent in plants,as observed for cytochrome P450s.展开更多
Dear Editor,Rauvolfia tetraphylla(aka the Devil pepper)(Supplemental Figure 1)is a well-known medicinal plant that produces monoterpenoid indole alkaloids(MIAs).This MIA biosynthesis occurs in several organs,including...Dear Editor,Rauvolfia tetraphylla(aka the Devil pepper)(Supplemental Figure 1)is a well-known medicinal plant that produces monoterpenoid indole alkaloids(MIAs).This MIA biosynthesis occurs in several organs,including leaves,stems,fruit,and roots,which accumulate the famous antiarrhythmic ajmaline(Kumar et al.2016a,2016b;Kumara et al.,2019).MIAs are natural products notably involved in plant adaptation to the environment and defense against aggressors.This mainly results from their high biological activities,which also explain their pharmacological properties.展开更多
KM2A is one of the main sub-arrays of LHAASO,working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV.Detector simulation is the important foundation for estimating detector performance and data ...KM2A is one of the main sub-arrays of LHAASO,working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV.Detector simulation is the important foundation for estimating detector performance and data analysis.It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units(>6000)with large altitude difference(30)and huge coverage(1.3).In this paper,the design of the KM2A simulation code G4KM2A based on Geant4 is introduced.The process of G4KM2A is optimized mainly in memory consumption to avoid memory overflow.Some simplifications are used to significantly speed up the execution of G4KM2A.The running time is reduced by at least 30 times compared to full detector simulation.The particle distributions and the core/angle resolution comparison between simulation and experimental data of the full KM2A array are also presented,which show good agreement.展开更多
Synthetic biology is constantly making progress for producing compounds on demand.Recently,Yocum and collaborators have developed an outstanding approach based on the anchoring of biosynthetic enzymes to the peroxisom...Synthetic biology is constantly making progress for producing compounds on demand.Recently,Yocum and collaborators have developed an outstanding approach based on the anchoring of biosynthetic enzymes to the peroxisomal membrane.This allowed access to an untapped resource of acetyl-CoA and stimulated the synthesis of a valuable polyketide.展开更多
基金FINEP No.01.22.0305.00CAPES—Finance Code 88887.832847/2023-00 and 88887.631486/2021-00.
文摘Biochar,a carbon-rich material derived from the thermochemical conversion of biomass under oxygenfree conditions,has emerged as a sustainable resource for radar-absorbing technologies.This study explores the production of activated biochars from end-of-life wood panels using a scalable and sustainable physical activation method with CO_(2) at different temperatures,avoiding the extensive use of corrosive chemicals and complex procedures associated with chemical or vacuum activation.Compared to conventional chemically or vacuum-activated biochars,the physically activated biochar demonstrated competitive performance while minimizing environmental impact,operational complexity,and energy consumption.Furthermore,activation at 750℃ reduces energy consumption by 14% and 28% compared to activations at 850℃ and 950℃,respectively,emphasizing the cost-effectiveness of this method for large-scale applications.The composite with 15% of biochar embedded in silicon rubber presented good electromagnetic performance,achieving a measured reflection loss(RL)of−37.2 dB at 11.3 GHz with an 8.4 mm thickness and an effective absorption bandwidth(EAB)of 1.25 GHz.These results highlight the potential of biocharsilicone rubber composites as flexible radar-absorbing materials(RAMs)for applications in electromagnetic shielding,anechoic chambers,and Internet of Things(IoT)devices.This study also shows the importance of forestry residues as sustainable precursors for producing low-cost porous carbon materials,aligning with circular economy principles and the United Nations’2030 Agenda for Sustainable Development.This work establishes a framework for scalable,cost-effective,and sustainable biochar production,addressing critical challenges in electromagnetic interference(EMI)mitigation and advancing the global adoption of green technologies.
文摘Afforestation and reforestation are useful approaches to improve carbon sequestration. With the advent of forest plantations, growing environment conditions have become increasingly restrictive for light, soil nutrients, and interactions between trees to acquire available resources. Tree biomass data are essential for understanding the forest carbon cycle and plant adaptations to the environment. The distribution of tree biomass depends on the sum of multiple stand conditions. The data are from a dedicated experiment with two very contrasting areas of fertility, and two planting densities, including a high density at planting in order to achieve thinning. The plant material consists of the high-performance clones of Eucalyptus urophylla × E. grandis and the reference clone E. PF1. We hypothesize that the distribution of biomass changes as the intensity of competition changes and that this is accelerated by the fertility of the sites in time. The results indicate that fertilization, planting density and clones have an impact on biomass partitioning.
基金supported by a Fondazione Umberto Veronesi 2011 grant to RRa grant from the University of Bari(Fondi di Ateneo 2014)a grant from the University of Salento(Fondi di Ateneo 2014)
文摘In this study, the effects of Radio Electric Asymmetric Conveyer(REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP),were investigated in vivo. We found that the REAC tissue optimization treatment specific for neuro-regenerative purposes(REAC TO-RGN-N) attenuated the inflammatory picture evoked by MPTP-induced nigro-striatal damage inmice, decreasing the levels of pro-inflammatory molecules and increasing anti-inflammatory mediators. Besides, there was a significant reduction of both astrocyte and microglial activation in MPTP-treated mice exposed to REAC TORGN-N. These results indicated that REAC TO-RGN-N treatment modulates the pro-inflammatory responses and reduces neuronal damage in MPTP-induced parkinsonism.
文摘The study aimed at evaluating the natural regeneration of some characteristic species in the Loukaya peri-urban forest was carried out in Brazzaville, over three surveys of one hectare each. The botanical inventory of the 23 species monitored covers the subjects of 2 ≤ d<sup>0.20</sup> < 10 cm and d<sup>1.30</sup> ≥ 10 cm. The study shows 1255 individuals of which 68.27% are 2 ≤ d<sup>0.20</sup> < 10 cm. While being tropophilic and mesophilic, this ecosystem is pauciflorous and paucispecific. The phytoecological data show that this formation, which is a link in the African dense humid forest, presents values far below those known elsewhere;while being faithful to the forests of the Cataractes Plateau. As for the rate of natural regeneration, this index is greater than or equal to 100 for 69.56% of the taxa. Sarcochores and heliophytes are the taxa that best support this natural regeneration. This high rate of regeneration would be correlated with the high level of anthropization, whose large canopy gaps are accompanied by a flow of light conducive to the installation of seedlings.
文摘The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.
文摘A study of the typology of soils and floristic diversity was carried out in the forest of the “Cité Scientifique” of Brazzaville. The study aimed to assess the influence of soil cover on the distribution of taxa. The study covers 18 plots of 625 m2 each, distributed in different soil profiles. The floristic inventory concerns the measurement of diameter of trees with dbh ≥ 10 cm and the counting of herbaceous and shrubs of dbh < 10 cm. The floristic composition reveals a total of 129 plant species distributed in 48 families dominated by Fabaceae and a preponderance of pioneer taxa. The Jaccard coefficients of similarity reveal a low degree of homology of woody plots, whereas for the flora as a whole, the floristic composition is heterogeneous. The Shannon biological diversity index of ligneous varies from 0.6 to 2, against a maximum diversity of 0.69 to 3. The Pielou index of ligneous (0.5 to 0.9) does not reveal any dominance. Soil cover consists of ferrallitic and podzol soils. Their texture is sandy, weakly structured, fragmentary polyhedral throughout the profile, but lumpy and/or nuciform at the surface and sub angular in depth. The porosity decreases proportionally with the depth and thickness of the horizons. The floristic analysis presents an ecosystem with a low degree of diversification for a high floristic richness. The preponderance of anthropization markers is a proof of its very advanced state of disturbance. The study shows that soil cover does not influence the distribution of timber. Indeed, the establishment and development of pioneer species are less prone to soil properties.
文摘The soil seed bank is an important source of restoration and resilience of disturbed ecosystems. This study evaluates the regeneration potential through the soil seed bank of the shrub savannas of Nguela and Mbe in order to predict the eventual dynamics. Three plots of 0.25 ha subdivided into four sub-plots of 0.015 ha have been installed in each savannah. In total, 48 samples of each savannah, i.e. 96 samples of both savannas, have been taken from the soil layers, 0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm. Species diversity and abundance of the soil seed bank have been assessed after germination. The results reveal 167 seedlings belonging to 23 species in the Mbe savannah and 144 seedlings belonging to 14 species in the Nguela savannah. The total densities of the germinated seeds were respectively 463.63 seeds/m<sup>2</sup> and 400 seeds/m<sup>2</sup>. Nevertheless, the 20 cm deep layers have illustrated themselves compared to the superficial layers with densities of 16.29 seeds/m<sup>2</sup> and 21.66 seeds/m<sup>2</sup>, respectively, in the savannas of Mbe and Nguela. Herbaceous species largely dominated, with percentages of 91% and 100%, respectively, in the savannas of Mbe and Nguela. Alone, the Trema orientalis (L.) Blume species has been identified as woody species in the Mbe savannah. The greatest specific richness has been obtained in the first five centimeters of soil, with 21.73% and 28.57% of exclusive species, respectively, in the savannas of Mbe and Nguela. The results reveal that restoration through the soil seed bank would be limited to a single woody species found (T. orientalis). Consequently, the study suggests silvicultural interventions based on planting or enrichment techniques for sustainably managed savannas exposed to anthropogenic disturbances.
基金funded by the Ministere de l’Economie,de la Science et de l’Innovation du Quebec,the Natural Sciences and Engineering Research Council of Canada(NSERC)the Consortium de recherche et innovations en bioprocedes industriels au Quebec(Cribiq)+1 种基金the Canada Research Chair Program,the College of Abitibi-Temiscaminguethe Industrial Waste Technology Centre(Centre Technologique des Residus Industriels)through its partner on this project,Airex Energy.
文摘Reconstituted wood panels have several advantages in terms of ease of manufacturing,but their shorter life span results in a huge amount of reconstituted wood panels being discarded in sorting centers yearly.Currently,the most common approach for dealing with this waste is incineration.In this study,reconstituted wood panels were converted into activated biochar through a two-step thermochemical process:(i)biochar production using pilot scale fast pyrolysis at 250 kg/h and 450℃;and(ii)a physical activation at three temperatures(750℃,850℃ and 950℃)using an in-house activation furnace(1 kg/h).Results showed that the first stage removed about 66% of the nitrogen from the wood panels in the form of NO,NH3,and trimethylamine,which were detected in small amounts compared to emitted CO_(2).Compared to other types of thermochemical conversion methods(e.g.,slow pyrolysis),isocyanic acid and hydrogen cyanide were not detected in this study.The second stage produced activated biochar with a specific surface area of up to 865 m^(2)/g at 950℃.The volatile gases generated during activation were predominantly composed of toluene and benzene.This two-step process resulted in nitrogen-rich carbon in the form of pyrrolic and pyridinic nitrogen.Activated biochars were then evaluated for their SO_(2) retention performance and showed an excellent adsorption capacity of up to 2140 mg/g compared to 65 mg/g for a commercial activated carbon(889 m^(2)/g).End-of-life reconstituted wood panels and SO_(2) gas are problematic issues in Canada where the economy largely revolves around forestry and mining industries.
文摘The soil seed bank is a key indicator of natural regeneration and/or forests resilience after disturbances. This study evaluates the soil seed bank characteristics in two Marantaceae forests plots of Ouesso Forest Industry (IFO) in north of the Republic of Congo. In each plot, 12 samples were taken per soil layers (0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm deep). Diversity and abundance seed were estimated after germination of soil samples. The results revealed 101 seedlings belonging to 17 species for plot 1 and 129 seedlings belonging to 15 species for plot 2. The average densities of germinated seeds were respectively 281 seedling/m<sup>2</sup> and 358 seedling/m<sup>2</sup>. There were no significant differences (p > 0.05) between the mean densities of the two plots. Herbaceous species dominated with percentages of 71% and 73%, respectively in plot 1 and plot 2. Both plots showed potential of regeneration from the soil seed bank. However, this potential seems higher in plot 2. Pioneer taxa were more abundant in the soil seed bank of plot 1 (4 woody pioneer species) than in plot 2 (1 woody pioneer species). The highest species richness was obtained in the first two soil layers (0 - 5 cm and 5 - 10 cm depth) while 25% of species were exclusively found in the deepest layer (15 - 20 cm) in plot 2. The study suggests silvicultural interventions based on planting or enrichment techniques for contribute to sustainable management of Marantaceae forests that could prevent the growth and development of seedlings.
文摘Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population.
文摘The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m<sup>2</sup> and 1742 seedlings/m<sup>2</sup>. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m<sup>2</sup> and 4 seedlings/m<sup>2</sup>, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.
基金supported by the APR IR program of the Re´gion Centre-Val de Loire(ScaleBio project),the ANR(project MIACYC–ANR-20-CE43-0010)the European Union’s Horizon Europe Framework(project COMBO under grant agreement N101135438).
文摘Continuous adaptation to changing environmental conditions is an evolutionary trait that many plant species have acquired to cope with biotic and abiotic stresses.Several plant families have adapted to synthesize a wide range of specialized metabolites,many of which serve protective functions.The significant biological activities of these specialized metabolites have been exploited by humans for pharmacological purposes.Notable examples include the monoterpenoid indole alkaloids vinblastine and vincristine fromtheMadagascar periwinkle(Apocynaceae)and the sesquiterpene lactone artemisinin from the annual wormwood(Asteraceae),which are used to treat cancers and malaria,respectively.The clinical importance of these compounds and their potential ecophysiological roles have motivated researchers to elucidate the biosynthetic pathways of many specialized metabolites.
基金supported by the Agence Nationale de la Recherche(ANR,project MIACYC-ANR-20-CE43-0010)the Région Centre-Val de Loire(ARP-IR ScaleBio project)the European Union’s Horizon Europe Framework(project COMBO under agreement N°101135438).
文摘Dear Editor,Although primary metabolism is assumed to be highly evolutionarily conserved in plants,specialized metabolism is more prone to active diversification to allow adaptation to changing environments.Notably,this diversification results from core metabolic enzyme hijacking or gene duplication events that are highly prevalent in plants,as observed for cytochrome P450s.
基金supported by the EU Horizon 2020 research and innovation program (MIAMi project-grant agreement N°814645)the ARD CVL Biopharmaceutical program of the Region Centre-Val de Loire (ETOPOCentre project)the ANR (project MIACYC–ANR-20-CE43-0010).
文摘Dear Editor,Rauvolfia tetraphylla(aka the Devil pepper)(Supplemental Figure 1)is a well-known medicinal plant that produces monoterpenoid indole alkaloids(MIAs).This MIA biosynthesis occurs in several organs,including leaves,stems,fruit,and roots,which accumulate the famous antiarrhythmic ajmaline(Kumar et al.2016a,2016b;Kumara et al.,2019).MIAs are natural products notably involved in plant adaptation to the environment and defense against aggressors.This mainly results from their high biological activities,which also explain their pharmacological properties.
基金supported by the following grants:The National Key R&D program of China under grants 2018YFA0404201the National Natural Science Foundation of China(NSFC)No.12022502,No.12205314,No.12105301,No.12261160362,No.12105294,No.U1931201,No.12393851,No.12393854+1 种基金In Thailand,support was provided by the National Science and Technology Development Agency(NSTDA)the National Research Council of Thailand(NRCT)under the High-Potential Research Team Grant Program(N42A650868).
文摘KM2A is one of the main sub-arrays of LHAASO,working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV.Detector simulation is the important foundation for estimating detector performance and data analysis.It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units(>6000)with large altitude difference(30)and huge coverage(1.3).In this paper,the design of the KM2A simulation code G4KM2A based on Geant4 is introduced.The process of G4KM2A is optimized mainly in memory consumption to avoid memory overflow.Some simplifications are used to significantly speed up the execution of G4KM2A.The running time is reduced by at least 30 times compared to full detector simulation.The particle distributions and the core/angle resolution comparison between simulation and experimental data of the full KM2A array are also presented,which show good agreement.
基金funding from the EU Horizon 2020 research and innovation program(MIAMi project-Grant agreement N°814645)ARD-CVL Biopharmaceutical program of the Region Centre Val de Loire(ETOPOCentre project),Le Studium Institute(Consortium Fellowship)and ANR(project MIACYC-ANR-20-CE43-0010).
文摘Synthetic biology is constantly making progress for producing compounds on demand.Recently,Yocum and collaborators have developed an outstanding approach based on the anchoring of biosynthetic enzymes to the peroxisomal membrane.This allowed access to an untapped resource of acetyl-CoA and stimulated the synthesis of a valuable polyketide.
