Abundant and well-preserved remains of noncalcareous algae and soft-bodied metazoans were collected from Middle Cambrian Kaili biota in Taijiang county, Guizhou Province, China. These remains provide further evidence ...Abundant and well-preserved remains of noncalcareous algae and soft-bodied metazoans were collected from Middle Cambrian Kaili biota in Taijiang county, Guizhou Province, China. These remains provide further evidence for the wide geographic distribution of many Burgess Shale taxa. Among the algae, 5 genera (including two new genera) and 5 species are described. They are Marpolia spissa Walcott, Acinocricus stichus Conway Morris and Robison, Udotealga erecta Yang, Eosargassum sawata Yang, and Rhizophyton zhaoyuanlongii Yang. Contrasting the macroalgal fossil assemblage in the Kaili biota with one in the Burgess Shale biota, it is clear that similarity of the Kaili biota and the Burgess Shale biota is reflected by the same content of not only the soft-bodied metazoans, but also the noncalcareous algae.展开更多
Phase transitions, morphology changes, and oxidation mechanism of the ilmenite oxidation process were investigated. FeTi03 transforms to hematite and rutile when oxidation at 700-800 ℃, and pseudobrookite is formed w...Phase transitions, morphology changes, and oxidation mechanism of the ilmenite oxidation process were investigated. FeTi03 transforms to hematite and rutile when oxidation at 700-800 ℃, and pseudobrookite is formed when the oxidation temperature reaches 900 ℃. The initial ilmenite powder exhibits paramagnetism; however, after being oxidized at the intermediate temperature (800-850 ℃), the oxidation product exhibits weak ferromagnetism. The oxidation mechanism was discussed. The microstructure observations show that a lot of micro-pores emerge on the surfaces of ilmenite particles at the intermediate temperature, which is deemed to be caoable ofenhancin~ the mass transfer ofoxgen during oxidation.展开更多
Within a forested watershed at the Uryu Experimental Forest of Hokkaido University in northern Hokkaido, overstory litterfall and related nutrient fluxes were measured at different landscape zones over two years. The ...Within a forested watershed at the Uryu Experimental Forest of Hokkaido University in northern Hokkaido, overstory litterfall and related nutrient fluxes were measured at different landscape zones over two years. The wetland zone covered with Picea glehnii pure stand. The riparian zone was deciduous broad-leaved stand dominated by Alnus hirsuta and Salix spp., while the mixture of deciduous broadleaf and evergreen conifer dominated by Betula platyphylla, Quercus crispula and Abies sachalinensis distributed on the upland zone. Annual litterfall averaged 1444, 5122, and 4123 kg.hm^-2·a^-1 in the wetland, riparian and upland zones, respectively. Litterfall production peaked in September-October, and foliage litter contributed the greatest amount (73.4%-87.6 %) of the annual total litterfall. Concentrations of nutrients analyzed in foliage litter of the dominant species showed a similar seasonal variation over the year except for N in P glehnii and A. hirsuta. The nutrient fluxes for all elements analyzed were greatest on riparian zone and lowest in wetland zone. Nutrient fluxes via litterfall followed the decreasing sequence: N (11-129 kg.hm-2.aq) 〉 Ca (9-69) 〉 K (5-20) 〉 Mg (3-15) 〉 P (0.4-4.7) for all stands. Significant differences were found in litterfall production and nutrient fluxes among the different landscape components. There existed significant differences in soil chemistry between the different landscape zones. The consistently low soil C:N ratios at the riparian zone might be due to the higher-quality litter inputs (largely N-fixing alder).展开更多
Ni-45.5Al-9Mo (mole fraction,%) alloy was directionally solidified with a constant temperature gradient (GL=334 K/cm) and growth rates ranging from 2 to 300 μm/s using a Bridgman type crystal growing facility wit...Ni-45.5Al-9Mo (mole fraction,%) alloy was directionally solidified with a constant temperature gradient (GL=334 K/cm) and growth rates ranging from 2 to 300 μm/s using a Bridgman type crystal growing facility with liquid metal cooling (LMC) technique. The effect of growth rate (v) on the solidified microstructures such as rod spacing (λ), rod size (d) and rod volume fraction was experimentally investigated. Two types of the solidified interfaces, planar and cellular, were identified. On the condition of both planar and cellular eutectic microstructures, the relationships between λ, d and v were given as: λv1/2=5.90 μm·μm1/2·s1/2 and dv1/2=2.18μm·μm1/2·s1/2, respectively. It was observed that the volume fraction of Mo phase could be adjusted in a certain range. The variation of phase volume fraction was attributed to undercooling increase and the growth characteristics of the individual constituent phases during the eutectic growth.展开更多
With the accelerating development of modern residential districts and the improvement of living levels, the requirement of people on environment is increasingly enhanced as well as the demand for culture. Based on peo...With the accelerating development of modern residential districts and the improvement of living levels, the requirement of people on environment is increasingly enhanced as well as the demand for culture. Based on people-oriented principle, this design utilized Chinese 'Fu' (blessings) culture to express people’s eager for a better life and the atmosphere of good fortune. It also produced the image of ecological environment by designing water landscapes and plant landscapes, created active space like squares for activity and active water system and developed the characteristics of residential districts by designing landscape sketches and plant landscapes.展开更多
Huizhou-style gardens have been greatly influenced by Huizhou culture, their plant landscapes have also been integrated with various aspects of Huizhou culture, which demonstrated the ideology, historical and cultural...Huizhou-style gardens have been greatly influenced by Huizhou culture, their plant landscapes have also been integrated with various aspects of Huizhou culture, which demonstrated the ideology, historical and cultural connotation of the society in an abstract and impalpable way. In this study, Huizhou-style miniature landscapes, plants of virtual implications, flowers or fruit trees of special connotations are taken for examples to analyze the influence of Xin’an Neo-Confucianism on plant landscapes in Huizhou-style gardens, the demonstration of Huizhou businessmen’s aesthetic tastes, as well as folk cultures of Huizhou, which implies that plant landscapes in Huizhou-style gardens are those incorporating with humanistic spirits, ornamental and practical uses. This study aims to provide references for further researches in the present situation of ancient Huizhou areas, protection of ancient Huizhou-style gardens and construction of new-style Huizhou gardens.展开更多
Tricalcium silicate cement(TSC)has been widely used in dental materials because of its self-setting behavior,good bioactivity,biocompatibility,osteoinductivity,and antibacterial effect.Tricalcium silicate(C3S)powder w...Tricalcium silicate cement(TSC)has been widely used in dental materials because of its self-setting behavior,good bioactivity,biocompatibility,osteoinductivity,and antibacterial effect.Tricalcium silicate(C3S)powder was prepared by Pechini technique with a calcining temperature of 1300℃ for 3 h.The influence of liquid/powder(L/P)rate on the setting time and the mechanical property of TSC was studied.Characterization methods including XRD,FTIR,SEM-EDS,TEM,and ICP-AES were utilized to study the properties of C3S powder and its hydrated cement.The bioactivity and biocompatibility of the cement were investigated by soaking test and cell culture,respectively.The results show that the L/P rate plays an important role in the setting time and the compressive strength of TSC.The surface of TSC was covered by hydroxyapatite deposition during the immersion experiment and the cells attachment on the surface of TSC was well,which indicated that TSC has good bioactivity and biocompatibility.In addition,TSC has excellent antibacterial properties against Staphylococcus aureus.In conclusion,TSC is a promising candidate for root canal filling materials.展开更多
Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies...Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only(Pisang site) while the other pair has clear differences in land use in addition to slope exposure(Braka site). In each site, we sampled 72 plots(36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis(CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables(e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.展开更多
This study was conducted to evaluate the intake, total and partial digestibility of nutrient, ruminal pH and ammonia concentration, microbial protein synthesis and performance in crossbred Holstein × Zebu cattle ...This study was conducted to evaluate the intake, total and partial digestibility of nutrient, ruminal pH and ammonia concentration, microbial protein synthesis and performance in crossbred Holstein × Zebu cattle fed four different hybrids sorghum silages (1F305, XBF60329, BRS610, Volumax). In Experiment 1, four rumen and abomasum fistulated steers, 400 ± 80 kg, distributed in a 4 × 4 Latin Square, were used. In Experiment 2, 28 crossbred Holstein × Zebu steers, 350 ± 50 kg, distributed in a randomized block design with four treatments and seven replicates, were used. In Experiment 1, it was observed that nutrient intake, as well as total, ruminal and intestinal digestibility of nutrient, were not affected (P 〉 0.05) by diets, except for total apparent digestibility of neutral detergent fiber (NDFap), which was lower for the BRS610 hybrid. There was lower NDFap ingestion in animals that received a diet containing silage from the BRS610 hybrid, however, the lowest intake non-fibrous carbohydrates (NFC) was observed for the diet containing silage from the Volumax hybrid. In Experiment 2, nutrient intake were not affected by the diets (P 〉 0.05), whereas, NDFap intake was lesser for hybrid BRS610. It was found that daily weight gain and feed conversion were not affected by different silages diets. Therefore, it may be concluded that the diets used were nutritionally equivalent, as they promoted similar animal performance without affecting ruminal parameters.展开更多
In this paper,15Cr-ODS steels containing 0,1 wt%,2 wt%and 3 wt%Al element were fabricated by combining wet-milling and spark plasma sintering(SPS)methods.The microstructure and mechanical properties of ODS steel were ...In this paper,15Cr-ODS steels containing 0,1 wt%,2 wt%and 3 wt%Al element were fabricated by combining wet-milling and spark plasma sintering(SPS)methods.The microstructure and mechanical properties of ODS steel were investigated by XRD,SEM,TEM,EBSD and tensile tests.The results demonstrate that the Al addition significantly refines the particle precipitates in the Fe-Cr matrix,leading to the obvious refinement in grain size of matrix and the improvement of mechanical properties.The dispersion particles in ODS steels with Al addition are identified as Al2O3 and Y_(2)Ti_(2)O_(7)nanoparticles,which has a heterogeneous size distribution in the range of 5 nm to 300 nm.Increasing Al addition causes an obvious increase in tensile strength and a decline in elongation.The tensile strength and elongation of 15Cr-ODS steel containing 3 wt%Al are 775.3 MPa and 15.1%,respectively.The existence of Al element improves the corrosion resistance of materials.The ODS steel containing 2 wt%Al shows corrosion potential of 0.39 V and passivation current density of 2.61×10^(−3)A/cm^(2)(1.37 V).This work shows that Al-doped ODS steels prepared by wet-milling and SPS methods have a potential application in structural parts for nuclear system.展开更多
The marine macroalgae Enteromorpha prolifera was one of the main algal genera that occurred in the widespread green tides in Qingdao, China, during the summers of 2007, 2008 and 2010. It is thus a plentiful source of ...The marine macroalgae Enteromorpha prolifera was one of the main algal genera that occurred in the widespread green tides in Qingdao, China, during the summers of 2007, 2008 and 2010. It is thus a plentiful source of biomass and could be used as a biofuel. In this study, the pyrolytic characteristics and kinetics of E. prolifera were investigated using thermogravimetric analysis (TGA) method. Cornstalk and sawdust were used as comparisons. Pyrolytic characteristics were studied using TG-DTG (thermogravimetry-derivative thermogravimetry) curves. Three stages in the pyrolytic process were determined: dehydration, dramatic weight loss and slow weight loss. E. prolifera was pyrolyzed at a lower initial temperature than the two terrestrial biomass forms. The apparent activation energy values for the three types of biomass were calculated and the mechanism functions were determined using 16 different mechanism functions, frequently used in thermal kinetics analysis. Activation energy values varied with mechanism function and the range of activation energy values for E. prolifera, cornstalk, and sawdust were 25-50 kJ/mol, 60-90 kJ/mol and 120-155 kJ/mol, respectively. This indicates that E. prolifera has low thermal stability for pyrolysis and good combustion characteristics.展开更多
Pyrenoids found in green algae Order Ulvales have taxonomical significance.Their morphology,microstructure,and the location and number in the cells have been widely used as identification criteria. As these traits can...Pyrenoids found in green algae Order Ulvales have taxonomical significance.Their morphology,microstructure,and the location and number in the cells have been widely used as identification criteria. As these traits can be affected by environmental conditions,it is necessary to look for other different characteristics.Here pyrenoids in several algae species collected along the Qingdao coast were studied for such purpose. The morphology and distribution of pyrenoids in the cells,as well as their change in different parts of the frond and at different times were studied with light microscope.The results are as follows.Pyrenoids appeared to be spherical or oval in observed Ulvales'algae cells.They were embedded in chloroplasts with the number of 1-3 per cell on average.The number of pyrenoids for Ulva pertusa could change drastically with continuing culture and could reach up to 10-20 per cell in late-growth stages.Generally, the pyrenoids in the marginal part were more observable than those in the central part for Ulva pertusa. In addition, the basal part of frond had more distinct pyrenoids with an average diameter of 2.42 μm for Enteromorpha linza. For some species the pyrenoids were difficult to be observed while dark treatment made them more distinguishable.The apoptosis rate of pyrenoids in different species varied under continuing dark treatment, which could be used to identify different species. Pyrenoids disappeared faster in E. linza than those in E.intestinalis.展开更多
TIG welding-brazing process with high frequency induction hot wire technology was presented to create joints between 5A06 aluminum alloy and SUS32! stainless steel using ER1100 filler wire with different temperature. ...TIG welding-brazing process with high frequency induction hot wire technology was presented to create joints between 5A06 aluminum alloy and SUS32! stainless steel using ER1100 filler wire with different temperature. The joints were evaluated by mechanical test and microstructural analyses. The welding procedure using hot fiUer wire (400 ℃ ) significantly increases strength stability by 71% and average value of tensile strength by 30. 8 % of the joints, compared with cold wire. The research of microstructures in interfaces and welded seams reveals that using 400 ℃ hot filler wire can decrease the thickness of intermetallic compounds ( IMCs ) from 6 to 3.5 txm approximately, which is the main reason of mechanical property improvement.展开更多
The paper addresses the controversial question of the role of clay-sized dust in the formation of paleosols in coastal eolianites, Israel. At the Habonim type section, the pedocomplex dated by archaeology and luminesc...The paper addresses the controversial question of the role of clay-sized dust in the formation of paleosols in coastal eolianites, Israel. At the Habonim type section, the pedocomplex dated by archaeology and luminescence to 45-135 ka ago shows at least three paleosols, not separated by non-soil sediments. The oldest reddish paleosol (apparently related to MIS 5) is magnetically enhanced, leached from carbonates, with signs of bioturbation and strongly aged clay coatings. The reddening is due to very fine, -20 nm, poorly crystallized, superparamagnetic (SP) hematite, as determined by Mossbauer studies. In subsoil, lithorelics of eolianite are found. Over time, the soil surface aggraded due to accelerated fine dust accumulation alongside local slope wash. On younger materials formed magnetically depleted vertisols, dominated by smectite-type expandable paramagnetic clays. In thin sections, vertisols exhibit strong stipple-speckled and striated b-fabric due to shrink-swell processes, impregnative calcite nodules and Fe-Mn redistribution. The uppermost hydric vertisol shows the strongest expression of juxtaposed features of recurrent calcite and Fe precipitation. This paleosol developed on colluvial soil materials, as evidenced by mixing of clay coated and uncoated grains of quartz and calcite allochems. M6ssbauer spectra show high amounts of Fe(III) incorporated in the clay structure, low amounts of SP goethite and absence of SP hematite. Whilst magnetic susceptibility drops in vertisols to minimal values, increase. The latter along ferrimagnetie grain sizes with differences in the hierarchy of microfabric features is taken as indication for lithologic discontinuities which may have resulted from continuous, albeit variable and low-intensity, input of eolian clay from both remote Saharan and local sources, roughly dated to the earlier to middle part of the Last Glacial.展开更多
文摘Abundant and well-preserved remains of noncalcareous algae and soft-bodied metazoans were collected from Middle Cambrian Kaili biota in Taijiang county, Guizhou Province, China. These remains provide further evidence for the wide geographic distribution of many Burgess Shale taxa. Among the algae, 5 genera (including two new genera) and 5 species are described. They are Marpolia spissa Walcott, Acinocricus stichus Conway Morris and Robison, Udotealga erecta Yang, Eosargassum sawata Yang, and Rhizophyton zhaoyuanlongii Yang. Contrasting the macroalgal fossil assemblage in the Kaili biota with one in the Burgess Shale biota, it is clear that similarity of the Kaili biota and the Burgess Shale biota is reflected by the same content of not only the soft-bodied metazoans, but also the noncalcareous algae.
基金Project(51074105) supported by the National Natural Science Foundation of ChinaProject(51225401) supported by the China National Funds for Distinguished Young Scientists
文摘Phase transitions, morphology changes, and oxidation mechanism of the ilmenite oxidation process were investigated. FeTi03 transforms to hematite and rutile when oxidation at 700-800 ℃, and pseudobrookite is formed when the oxidation temperature reaches 900 ℃. The initial ilmenite powder exhibits paramagnetism; however, after being oxidized at the intermediate temperature (800-850 ℃), the oxidation product exhibits weak ferromagnetism. The oxidation mechanism was discussed. The microstructure observations show that a lot of micro-pores emerge on the surfaces of ilmenite particles at the intermediate temperature, which is deemed to be caoable ofenhancin~ the mass transfer ofoxgen during oxidation.
基金The project was supported by Japanese Society for Promotion of Sciences (15P03118).
文摘Within a forested watershed at the Uryu Experimental Forest of Hokkaido University in northern Hokkaido, overstory litterfall and related nutrient fluxes were measured at different landscape zones over two years. The wetland zone covered with Picea glehnii pure stand. The riparian zone was deciduous broad-leaved stand dominated by Alnus hirsuta and Salix spp., while the mixture of deciduous broadleaf and evergreen conifer dominated by Betula platyphylla, Quercus crispula and Abies sachalinensis distributed on the upland zone. Annual litterfall averaged 1444, 5122, and 4123 kg.hm^-2·a^-1 in the wetland, riparian and upland zones, respectively. Litterfall production peaked in September-October, and foliage litter contributed the greatest amount (73.4%-87.6 %) of the annual total litterfall. Concentrations of nutrients analyzed in foliage litter of the dominant species showed a similar seasonal variation over the year except for N in P glehnii and A. hirsuta. The nutrient fluxes for all elements analyzed were greatest on riparian zone and lowest in wetland zone. Nutrient fluxes via litterfall followed the decreasing sequence: N (11-129 kg.hm-2.aq) 〉 Ca (9-69) 〉 K (5-20) 〉 Mg (3-15) 〉 P (0.4-4.7) for all stands. Significant differences were found in litterfall production and nutrient fluxes among the different landscape components. There existed significant differences in soil chemistry between the different landscape zones. The consistently low soil C:N ratios at the riparian zone might be due to the higher-quality litter inputs (largely N-fixing alder).
基金Project (51074128) supported by the National Natural Science Foundation of ChinaProject (2007ZF53067) supported by the Aeronautical Science Foundation of China+1 种基金Project (2010JM6002) supported by the Natural Science Foundation of Shaanxi Province of ChinaProjec t(2012NCL004) supported by the Innovation Foundation of Inner Mongolia University of Science and Technology
文摘Ni-45.5Al-9Mo (mole fraction,%) alloy was directionally solidified with a constant temperature gradient (GL=334 K/cm) and growth rates ranging from 2 to 300 μm/s using a Bridgman type crystal growing facility with liquid metal cooling (LMC) technique. The effect of growth rate (v) on the solidified microstructures such as rod spacing (λ), rod size (d) and rod volume fraction was experimentally investigated. Two types of the solidified interfaces, planar and cellular, were identified. On the condition of both planar and cellular eutectic microstructures, the relationships between λ, d and v were given as: λv1/2=5.90 μm·μm1/2·s1/2 and dv1/2=2.18μm·μm1/2·s1/2, respectively. It was observed that the volume fraction of Mo phase could be adjusted in a certain range. The variation of phase volume fraction was attributed to undercooling increase and the growth characteristics of the individual constituent phases during the eutectic growth.
文摘With the accelerating development of modern residential districts and the improvement of living levels, the requirement of people on environment is increasingly enhanced as well as the demand for culture. Based on people-oriented principle, this design utilized Chinese 'Fu' (blessings) culture to express people’s eager for a better life and the atmosphere of good fortune. It also produced the image of ecological environment by designing water landscapes and plant landscapes, created active space like squares for activity and active water system and developed the characteristics of residential districts by designing landscape sketches and plant landscapes.
文摘Huizhou-style gardens have been greatly influenced by Huizhou culture, their plant landscapes have also been integrated with various aspects of Huizhou culture, which demonstrated the ideology, historical and cultural connotation of the society in an abstract and impalpable way. In this study, Huizhou-style miniature landscapes, plants of virtual implications, flowers or fruit trees of special connotations are taken for examples to analyze the influence of Xin’an Neo-Confucianism on plant landscapes in Huizhou-style gardens, the demonstration of Huizhou businessmen’s aesthetic tastes, as well as folk cultures of Huizhou, which implies that plant landscapes in Huizhou-style gardens are those incorporating with humanistic spirits, ornamental and practical uses. This study aims to provide references for further researches in the present situation of ancient Huizhou areas, protection of ancient Huizhou-style gardens and construction of new-style Huizhou gardens.
基金Project(2019JJ50797)supported by Hunan Provincial Natural Science Foundation of China。
文摘Tricalcium silicate cement(TSC)has been widely used in dental materials because of its self-setting behavior,good bioactivity,biocompatibility,osteoinductivity,and antibacterial effect.Tricalcium silicate(C3S)powder was prepared by Pechini technique with a calcining temperature of 1300℃ for 3 h.The influence of liquid/powder(L/P)rate on the setting time and the mechanical property of TSC was studied.Characterization methods including XRD,FTIR,SEM-EDS,TEM,and ICP-AES were utilized to study the properties of C3S powder and its hydrated cement.The bioactivity and biocompatibility of the cement were investigated by soaking test and cell culture,respectively.The results show that the L/P rate plays an important role in the setting time and the compressive strength of TSC.The surface of TSC was covered by hydroxyapatite deposition during the immersion experiment and the cells attachment on the surface of TSC was well,which indicated that TSC has good bioactivity and biocompatibility.In addition,TSC has excellent antibacterial properties against Staphylococcus aureus.In conclusion,TSC is a promising candidate for root canal filling materials.
基金Annapurna Conservation Area Project (ACAP)Norwegian State Educational Loan Fund (Lnekassen)+2 种基金Faculty of Mathematics and Natural Sciences,University of Bergen for financingfunded by Norwegian Research Council(project no.148910/730)supported by The Norwegian Council for Higher Education Programme for Development Research and Education(NUFU Project ID:PRO 04/2002)
文摘Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only(Pisang site) while the other pair has clear differences in land use in addition to slope exposure(Braka site). In each site, we sampled 72 plots(36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis(CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables(e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.
文摘This study was conducted to evaluate the intake, total and partial digestibility of nutrient, ruminal pH and ammonia concentration, microbial protein synthesis and performance in crossbred Holstein × Zebu cattle fed four different hybrids sorghum silages (1F305, XBF60329, BRS610, Volumax). In Experiment 1, four rumen and abomasum fistulated steers, 400 ± 80 kg, distributed in a 4 × 4 Latin Square, were used. In Experiment 2, 28 crossbred Holstein × Zebu steers, 350 ± 50 kg, distributed in a randomized block design with four treatments and seven replicates, were used. In Experiment 1, it was observed that nutrient intake, as well as total, ruminal and intestinal digestibility of nutrient, were not affected (P 〉 0.05) by diets, except for total apparent digestibility of neutral detergent fiber (NDFap), which was lower for the BRS610 hybrid. There was lower NDFap ingestion in animals that received a diet containing silage from the BRS610 hybrid, however, the lowest intake non-fibrous carbohydrates (NFC) was observed for the diet containing silage from the Volumax hybrid. In Experiment 2, nutrient intake were not affected by the diets (P 〉 0.05), whereas, NDFap intake was lesser for hybrid BRS610. It was found that daily weight gain and feed conversion were not affected by different silages diets. Therefore, it may be concluded that the diets used were nutritionally equivalent, as they promoted similar animal performance without affecting ruminal parameters.
基金Project(2020JJ2001)supported by Outstanding Youth Scientist Foundation of Hunan Province,ChinaProject(6142912200102)supported by Foundation for National Key Laboratory of Science and Technology on Highstrength Structural Materials,China。
文摘In this paper,15Cr-ODS steels containing 0,1 wt%,2 wt%and 3 wt%Al element were fabricated by combining wet-milling and spark plasma sintering(SPS)methods.The microstructure and mechanical properties of ODS steel were investigated by XRD,SEM,TEM,EBSD and tensile tests.The results demonstrate that the Al addition significantly refines the particle precipitates in the Fe-Cr matrix,leading to the obvious refinement in grain size of matrix and the improvement of mechanical properties.The dispersion particles in ODS steels with Al addition are identified as Al2O3 and Y_(2)Ti_(2)O_(7)nanoparticles,which has a heterogeneous size distribution in the range of 5 nm to 300 nm.Increasing Al addition causes an obvious increase in tensile strength and a decline in elongation.The tensile strength and elongation of 15Cr-ODS steel containing 3 wt%Al are 775.3 MPa and 15.1%,respectively.The existence of Al element improves the corrosion resistance of materials.The ODS steel containing 2 wt%Al shows corrosion potential of 0.39 V and passivation current density of 2.61×10^(−3)A/cm^(2)(1.37 V).This work shows that Al-doped ODS steels prepared by wet-milling and SPS methods have a potential application in structural parts for nuclear system.
基金Supported by the National Natural Science Foundation of China (No. 21076117)Shandong Province Higher Educational Science and Technology Program (Nos. J09LC22 and J10LC15)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX2-YW-209)the Open Fund of the Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences (No. Kf201016)
文摘The marine macroalgae Enteromorpha prolifera was one of the main algal genera that occurred in the widespread green tides in Qingdao, China, during the summers of 2007, 2008 and 2010. It is thus a plentiful source of biomass and could be used as a biofuel. In this study, the pyrolytic characteristics and kinetics of E. prolifera were investigated using thermogravimetric analysis (TGA) method. Cornstalk and sawdust were used as comparisons. Pyrolytic characteristics were studied using TG-DTG (thermogravimetry-derivative thermogravimetry) curves. Three stages in the pyrolytic process were determined: dehydration, dramatic weight loss and slow weight loss. E. prolifera was pyrolyzed at a lower initial temperature than the two terrestrial biomass forms. The apparent activation energy values for the three types of biomass were calculated and the mechanism functions were determined using 16 different mechanism functions, frequently used in thermal kinetics analysis. Activation energy values varied with mechanism function and the range of activation energy values for E. prolifera, cornstalk, and sawdust were 25-50 kJ/mol, 60-90 kJ/mol and 120-155 kJ/mol, respectively. This indicates that E. prolifera has low thermal stability for pyrolysis and good combustion characteristics.
基金supported by the National Natural Science Foundation of China(Nos.40876081 and 30570125)
文摘Pyrenoids found in green algae Order Ulvales have taxonomical significance.Their morphology,microstructure,and the location and number in the cells have been widely used as identification criteria. As these traits can be affected by environmental conditions,it is necessary to look for other different characteristics.Here pyrenoids in several algae species collected along the Qingdao coast were studied for such purpose. The morphology and distribution of pyrenoids in the cells,as well as their change in different parts of the frond and at different times were studied with light microscope.The results are as follows.Pyrenoids appeared to be spherical or oval in observed Ulvales'algae cells.They were embedded in chloroplasts with the number of 1-3 per cell on average.The number of pyrenoids for Ulva pertusa could change drastically with continuing culture and could reach up to 10-20 per cell in late-growth stages.Generally, the pyrenoids in the marginal part were more observable than those in the central part for Ulva pertusa. In addition, the basal part of frond had more distinct pyrenoids with an average diameter of 2.42 μm for Enteromorpha linza. For some species the pyrenoids were difficult to be observed while dark treatment made them more distinguishable.The apoptosis rate of pyrenoids in different species varied under continuing dark treatment, which could be used to identify different species. Pyrenoids disappeared faster in E. linza than those in E.intestinalis.
基金Acknowledgement The authors would like to appreciate the financial support from the National Natural Science Foundation of China (Grant No. 50874033 ).
文摘TIG welding-brazing process with high frequency induction hot wire technology was presented to create joints between 5A06 aluminum alloy and SUS32! stainless steel using ER1100 filler wire with different temperature. The joints were evaluated by mechanical test and microstructural analyses. The welding procedure using hot fiUer wire (400 ℃ ) significantly increases strength stability by 71% and average value of tensile strength by 30. 8 % of the joints, compared with cold wire. The research of microstructures in interfaces and welded seams reveals that using 400 ℃ hot filler wire can decrease the thickness of intermetallic compounds ( IMCs ) from 6 to 3.5 txm approximately, which is the main reason of mechanical property improvement.
基金supported by the Research Authority of the University of Haifa, and the Joint Foundation between Technion and University of Haifa
文摘The paper addresses the controversial question of the role of clay-sized dust in the formation of paleosols in coastal eolianites, Israel. At the Habonim type section, the pedocomplex dated by archaeology and luminescence to 45-135 ka ago shows at least three paleosols, not separated by non-soil sediments. The oldest reddish paleosol (apparently related to MIS 5) is magnetically enhanced, leached from carbonates, with signs of bioturbation and strongly aged clay coatings. The reddening is due to very fine, -20 nm, poorly crystallized, superparamagnetic (SP) hematite, as determined by Mossbauer studies. In subsoil, lithorelics of eolianite are found. Over time, the soil surface aggraded due to accelerated fine dust accumulation alongside local slope wash. On younger materials formed magnetically depleted vertisols, dominated by smectite-type expandable paramagnetic clays. In thin sections, vertisols exhibit strong stipple-speckled and striated b-fabric due to shrink-swell processes, impregnative calcite nodules and Fe-Mn redistribution. The uppermost hydric vertisol shows the strongest expression of juxtaposed features of recurrent calcite and Fe precipitation. This paleosol developed on colluvial soil materials, as evidenced by mixing of clay coated and uncoated grains of quartz and calcite allochems. M6ssbauer spectra show high amounts of Fe(III) incorporated in the clay structure, low amounts of SP goethite and absence of SP hematite. Whilst magnetic susceptibility drops in vertisols to minimal values, increase. The latter along ferrimagnetie grain sizes with differences in the hierarchy of microfabric features is taken as indication for lithologic discontinuities which may have resulted from continuous, albeit variable and low-intensity, input of eolian clay from both remote Saharan and local sources, roughly dated to the earlier to middle part of the Last Glacial.