density

摘要： Aiming at the process of smelting ultra-high(>80%)or even full vanadium titanomagnetite in blast furnace,we are conducting a series of works on physics character of high TiO_(2) bearing blast furnace slag(BFS)for slag optimization.This work discussed the density and surface tension of high TiO_(2) bearing BFS using the Archimedean principle and the maximum bubble pressure method,respectively.The influence of TiO_(2) content and the MgO/CaO mass ratio on the density and surface tension of CaO-SiO_(2)-TiO_(2)-MgO-Al_(2)O_(3)slags were investigated Results indicated that the density of slags decreased with the TiO_(2) content increasing from 20wt%to 30wt%,but it increased slightly with the MgO/CaO mass ratio increasing from 0.32 to 0.73.In view of silicate network structure,the density and the degree of polymerization(DOP)of network structure have a consistent trend.The addition of TiO_(2) reduced(Q^(3))^(2)/(Q^(2)) ratio(Q^(2) and Q^(3) represent structural unit with bridge oxygen number of 2 and 3,respectively)and then decreased DOP,which led to the decrease of slag density.The surface tension of CaO-SiO_(2)-TiO_(2)-MgO-Al_(2)O_(3) slags decreased dramatically with the TiO_(2) content increasing from 20wt%to 30wt%.Conversely,it increased with the MgO/CaO mass ratio increasing from 0.32 to 0.73.Furthermore,the iso-surface tension lines were obtained under 1723 K using the Tanaka developed model in view of Butler formula.It may be useful for slag optimization of ultra-high proportion(>80%)or even full vanadium titanomagnetite under BF smelting.

摘要： Population management of herbivores is widely applied to decrease damage to forests in the northern hemisphere. Culling more antlerless deer, including females and fawns, is an effective means of reducing the population and helps to improve management efficiency. To increase the efficiency of antlerless-biased culling, we assessed the spatiotemporal distribution of the antlerless ratio in culled sika deer (Cervus nippon) in relation to population density. We hypothesized that the antlerless ratio is higher at the center of the distribution than at the margins of the deer’s range, because dispersal processes differ according to sex and age: Young male deer first disperse into an unoccupied area, and then males may become established in the new area for approximately 10–15 years before the number of females increases. A statistical model revealed spatiotemporal changes in the antlerless ratio of culled sika deer. The change in the ratio basically fit the density distribution of the deer, which was estimated independently on the basis of fecal pellet count surveys. The antlerless ratio estimated from the model increased asymptotically as deer density rose. The results support our hypothesis and suggest that antlerless sika deer will be more easily culled at the center rather than at the margins of the distribution range. These findings should help to increase the efficiency of managing the deer via antlerless-biased culling.

摘要： Wood anatomical structures of various tree species help identify the wood. The characteristics and composition of these structures affect their utilisation. In this work, the microstructure of Blighia sapida a lesser-known Ghanaian hardwood species using light microscope and scanning electron microscope (SEM) was studied. The relationship between the microstructure and some physical properties such as density, and bending strength were also studied. The anatomical features studied were fibre length, double fibre wall thickness, fibre proportion, vessel diameter and proportion, rays and axial parenchyma proportions. It was observed that the use of SEM in studying the anatomical or ultra-structural aspects of wood gives a clearer understanding of the features and structures found in wood. Anatomical features such as presence of crystals and absence of axial parenchyma in Blighia sapida are reported in the work. The study also established that Blighia sapida had a low water uptake even though it had vessel distribution of 12 vessels/mm2. Having not very distinct axial parenchyma may have accounted for the low water uptake. The presence of occluded pits could also account for the low water uptake and the fibre wall thickness may also account for a medium bending strength of 62.8 N/mm2 at 12% moisture content.

摘要： Arbuscular Mycorrhizal Fungi (AMFs) could be used to sustainably improve crop yields. The present study evaluated the diversity of AMF species associated with soybean (Glycine max L. Merill) in main soybean-producing areas in Benin. Composite soil samples from 13 production areas at a rate of 04 villages per production areas were collected. A spore trapping device was set up to reveal the diversity of spores. The physical and chemical properties of the soils, the frequency and intensity of mycorrhization of roots, and the diversity of AMF spores were determined in the soil samples following trapping. As result, eight morphotypes belonging to four genera: Glomus, Acaulospora Gigaspora and Disversispora and three families: Diversisporales, Glomérales and Paraglomérales were observed. An important variability of spore densities was observed from one production areas to another with a higher abundance in the production areas of Copargo estimated at 3584 spores/100g soil. The biological diversity indexes as Shannon (0.0311), Simpson (0.0204) and Hill (0.0235), varied significantly (p < 0.05) from one production areas to another. There was significant correlation between the parameters studied, particularly between the physico-chemical parameters of the soils and between the physico-chemical parameters and the biological diversity indexes. For the mycorrhization parameters, the mycorhization frequencies did not vary from one production areas to another, unlike the intensities, which significantly varied from one production areas to another (2.31% to 24.62%). Finally, this study revealed that the physico-chemical parameters of the soils had an influence on the other parameters studied. Moreover, there were an abundance and a significant diversification of AMFs associated with soybean in the different production areas, which are influenced by certain physico-chemical soil parameters.

摘要： It provides a theoretical basis for the artificial promotion of the reproduction and regeneration of Liriodendron chinense through exploring the effects of light intensity and seeding density on the seed germination and seedling growth of this rare plant. Controlled experiments were conducted by setting different seeding densities and shading intensities to observe and detect the seed germination and seedling growth under different experimental conditions. The data were analyzed by SPSS and the model was fitted to calculate the seed germination rate, seedling emergence rate and seedling growth parameters of Liriodendron chinense, which were used to analyze the effects of seeding density and light intensity on the seed germination and seedling growth of Liriodendron chinense. Light has a significant impact on the seed germination and seedling growth of Liriodendron chinense (P P > 0.05). High density promotes the seedling height (the seedling height showed a rising trend with the increase of seeding density, reaching the highest at 500 seeds/m2. “3-stitch + 300 seeds/m2” combination is an appropriate condition for Liriodendron chinense reproduction since it can realize higher germination rate and better seedling growth potential. The seedling height and basal diameter growth curve of Liriodendron chinense fits well to the Logistic equation (R2 ≥ 0.977). Light has a significant impact on the seed germination and seedling growth of Liriodendron chinense, and appropriate shading treatment can increase the seed germination rate and seedling emergence rate of Liriodendron chinense. Seeding density has little influence on the seed germination rate of Liriodendron chinense, but high density will promote seedling height.

摘要： Fire is regarded as management practice for maintaining grasslands and savannas. The vegetation occurring in fire prone areas becomes highly adapted to fire occurrences in savannas and grasslands. However, documentation on the influence of burning on vegetation is still limited in an albany thicket biome. The aim of the study was to evaluate the short-term influence of burning on species abundance, biomass production, wood plant density and browsing unit. Six plots (2500 m2) were demarcated;in each plot two parallel transects of 120 m2 with 5 m distance apart were measured. Three plots were burned in spring season, while no burning was done on the other remaining plots. Forty points per plot were obtained using step-point method to determine the relative abundance at burned and unburned plots. Woody plants occurred within a transect were identified, counted and recorded to determine density and browsing unit. Three quadrats (i.e. 0.25 m2) per plot were randomly laid within the transect;aboveground plant material within a quadrat were harvested. A total of 18 samples were harvested and oven dried at 60˚C for 48 hours to determine biomass production. The results showed that Themeda triandra (14%) and Panicum maximum (10%) were most abundant grass species at the burned plots. Burned plots had significantly higher biomass production (4804 kg/ha) compared to unburned plots (3641 kg/ha). Vachellia karoo (burned: 65.85% & unburn: 13.70%) and Searsia pallens (burned: 26.83% & unburned: 6.85%) were most dominant wood plant species at both burned and unburned plots. Burned plots had the highest browsing unit (3221 BU/ha) compared to unburned plots (2058 BU/ha). The decrease of woody plants at the burned plots proved that fire has a tremendous potential for managing woody plants. This study provided information on short-term influence of burning, however further long-term trials are required to determine the effects of burning.

摘要： Biological yield indicates the potential for increasing yield.Leaf carbon metabolism plays an important role in the biomass accumulation of rapeseed(Brassica napus L.).Field experiments with the hybrid HZ62(with a conventional plant architecture)grown in 2016–2017,and HZ62 and accession 1301(with a compact plant architecture)grown in 2017–2018 were conducted to characterize the physiological and proteomic responses of leaf photosynthetic carbon metabolism to density and row spacing configurations.The densities were set at 15×10;ha^(-1)(D1),30×10^(4)ha^(-1)(D2),and 45×10^(4)ha^(-1)(D3)(main plot),with row spacings of 15 cm(R15),25 cm(R25),and 35 cm(R35)(subplot).Individual and plant population biomass accumulation was greatest at R25,R15,and R15 for D1,D2,and D3,respectively,for both genotypes.In comparison with D1 R25,the individual aboveground biomass of HZ62 decreased by60.2%,whereas the population biomass increased by 31.9%,and the individual biomass of genotype1301 decreased by 54.0%and the population biomass increased by 53.9%at D3 R15.Leaf carbon metabolic enzymes varied between genotypes at flowering stage.In contrast to D1 R25,at D3 R15 the activities of ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)and sucrose phosphate synthase(SPS)and the contents of starch,sucrose and soluble sugars in leaves were significantly decreased in HZ62 and increased in genotype 1301.The activities of fructose-1,6-bisphosphatase(FBPase)decreased,in consistency with the abundance of fructose-bisphosphate aldolase in HZ62.In contrast,sucrose synthase(Su Sy)activity appeared to decrease in both genotypes,but a significant increase in abundance of a protein with sucrose synthase was found in the 1301 genotype by proteomic analysis.With increased density and reduced row spacing,the expression of most key proteins involved in carbon metabolism was elevated,and enzyme activity and carbon assimilate content were increased in 1301,whereas HZ62 showed the opposite trend,indicating that the compact plant type can accumulate more population biomass with denser planting.

摘要： 1 Introduction and Main Results Consider the first Piola-Kirchhoff stress P defined as[1]P(F)=?W(F)/?F,(1.1)where F and W refer to the deformation tensor and strain energy density.Due to the principle of material frame-indifference and the material symmetry,two important constraints should be satisfied by these relations[1].

摘要： Determining the suitable fish farming conditions for optimal growth is necessary for aquaculture production, but it is not very obvious because it requires a good understanding of species biology. Thus, this study aims to evaluate the effects of different temperature regimes, stocking densities, and feeding rates on the growth of Nile tilapia, Oreochromis niloticus fingerlings that have been sex-reversed with 17α methyl testosterone. Three independent experiments were performed (with replicates) at the IRD Bel-Air fish farm (Dakar, Senegal) on 27-day-old fry maintained in six 25 L tanks with a batch of 100 individuals each. These fry were subjected to three different temperatures (26˚C, 28˚C, 30˚C;kept constant with thermostats), stocking densities (5, 10 and 15 ind/l) and feeding rates (5%, 10% and 15% of biomass;distributed three times a day). For the temperature and density treatments, fry was fed a pelleted feed containing 38% protein, distributed by hand at 10% of their total biomass, readjusted after each measurement. Growth performance (total weight, weight gain and daily weight gain), physicochemical parameters (temperature, oxygen, nitrite and phosphorus), feed conversion ratio (FCR) and survival rate (SR) were regularly monitored (weekly) during the experimental period. For the heat treatment, the results did not show an apparent relationship between growth performance and nitrite, phosphorus or dissolved oxygen (DO) contents. In contrast, there was a significant correlation between temperature and growth rates, with the best growth being obtained at 30˚C compared to 28˚C and 26˚C. Similarly, growth rates were correlated with stocking density and feeding rate but not with oxygen, temperature, nitrite or phosphorus levels. The best growth rates were observed at the lowest density (5 ind/l) and for the highest feeding rate (15% of biomass), which coincides with the best FCR and survival rates. Thus, 30˚C, 5 ind/l and 15% of biomass appeared to be the most favorable temperature, stocking density and feeding rate for optimal growth of Nile tilapia fry after inversion. The application of these results in the culture systems will allow to reach a good production of O. niloticus and thus to contribute to sustainable development of fish culture in Senegal.

摘要： DEAR EDITOR,The giant panda(Ailuropoda melanoleuca)is a unique forest-dwelling species endemic to China.Previous studies have suggested that giant pandas are heavily reliant on old-growth forests with high vegetation coverage.As such,management has primarily focused on improving vegetation coverage in the potential range of giant pandas to increase the availability of suitable habitat.However,it remains unclear whether high vegetation coverage itself results in higher giant panda density.Here,we analyzed changes in vegetation coverage from 2001 to 2011 as well as the occurrence of wild giant pandas in five mountain areas.