Planarization of B20 clusters by Si and C atom substitution.

An optimization strategy combining a global semi-empirical quantum mechanical search and all-electron density functional theory was adopted to determine the lowest energy structures of B19Si and B19C clusters. The planarization of a B20 cluster by Si and C atom substitution was observed. The structural transition was from the double-ring tubular B20 to an almost perfect planar B19Si and a quasi-planar bowl B19C. B19Si possessed a geometry with a central B atom surrounded by a six-membered ring and a 13-atom outer ring. B19C adopted a geometry with a B5C six-membered hole. Both Si and C atoms occupied peripheral positions. The observed planarization may be attributed to sp2 hybridization, changes in the peripheral bonding, and structural mechanics. Some properties, including the HOMO-LUMO gaps, on-site charge on Si and C atoms, and deformed charge distribution, were discussed.

Analysis of the Structures and Properties of (GaSb)n (n = 4-9) Clusters through Density Functional Theory.

An optimization strategy combining global semiempirical quantum mechanical search with all-electron density functional theory was adopted to determine the lowest energy structure of (GaSb)n clusters up to n = 9. The growth pattern of the clusters differed from those of previously reported group III-V binary clusters. A cagelike configuration was found for cluster sizes n ≤ 7. The structure of (GaSb)6 deviated from that of other III-V clusters. Competition existed between core-shell and hollow cage structures of (GaSb)7. Novel noncagelike structures were energetically preferred over the cages for the (GaSb)8 and (GaSb)9 clusters. Electronic properties, such as vertical ionization potential, adiabatic electron affinities, HOMO-LUMO gaps, and average on-site charges on Ga or Sb atoms, as well as binding energies, were computed.

DFT study on endohedral and exohedral B38 fullerenes: M@B38 (M = Sc, Y, Ti) and M&B38 (M = Nb, Fe, Co, Ni).

The structures, stabilities and electronic properties of endohedral and exohedral B38 fullerenes with transition metal atoms (M = Sc, Y, Ti, Nb, Fe, Co, Ni) are studied using all-electron density functional theory. M@B38 (M = Sc, Y, Ti) possess endohedral structures as their lowest energy structures, while Nb, Fe, Co and Ni atoms favor the coordination of B38 fullerenes in an exohedral manner. Sizable HOMO-LUMO gaps and high binding energies imply the viability of M@B38 towards experimental realization. The distributions of electron density and frontier orbitals are analyzed in detail. The analysis of vertical ionization potential and vertical electron affinity indicates that M@B38 are good electron acceptors and bad electron donors.

Variations in nitrogen-15 natural abundance of plant and soil systems in four remote tropical rainforests, southern China.

The foliar stable N isotope ratio (δ(15)N) can provide integrated information on ecosystem N cycling. Here we present the δ(15)N of plant and soil in four remote typical tropical rainforests (one primary and three secondary) of southern China. We aimed to examine if (1) foliar δ(15)N in the study forests is negative, as observed in other tropical and subtropical sites in eastern Asia; (2) variation in δ(15)N among different species is smaller compared to that in many N-limited temperate and boreal ecosystems; and (3) the primary forest is more N rich than the younger secondary forests and therefore is more (15)N enriched. Our results show that foliar δ(15)N ranged from -5.1 to 1.3‰ for 39 collected plant species with different growth strategies and mycorrhizal types, and that for 35 species it was negative. Soil NO3 (-) had low δ(15)N (-11.4 to -3.2‰) and plant NO3 (-) uptake could not explain the negative foliar δ(15)N values (NH4 (+) was dominant in the soil inorganic-N fraction). We suggest that negative values might be caused by isotope fractionation during soil NH4 (+) uptake and mycorrhizal N transfer, and by direct uptake of atmospheric NH3/NH4 (+). The variation in foliar δ(15)N among species (by about 6‰) was smaller than in many N-limited ecosystems, which is typically about or over 10‰. The primary forest had a larger N capital in plants than the secondary forests. Foliar δ(15)N and the enrichment factor (foliar δ(15)N minus soil δ(15)N) were higher in the primary forest than in the secondary forests, albeit differences were small, while there was no consistent pattern in soil δ(15)N between primary and secondary forests.

Gross ecosystem product accounting of national park: Taking Hainan Tropical Rainforest National Park as an example.

Hainan Tropical Rainforest National Park has the most representative and largest contiguous tropical rainforest in China, which has advantages in exploring the realization mechanism of ecological product value in national parks. Based on the basic framework of "The Technical Guideline on Gross Ecosystem Product (GEP)", we constructed a GEP accounting system in line with the characteristics of tropical rain forest national park, and calculated the GEP of Hainan Tropical Rainforest National Park in 2019. The results showed that the GEP of Hainan Tropical Rainforest National Park in 2019 was 204.513 billion yuan, and the GEP per unit area was 0.046 billion yuan·km-2. Among all the service types, the value of material services was 4.850 billion yuan, accounting for 2.4% of the total GEP in the national park. The ecosystem regulation service value was 168.891 billion yuan, accounting for 82.6%. The value of cultural services was 30.772 billion yuan, accounting for 15.0%. Among different ecosystem types, the unit area value of the tropical rain forest ecosystem represented by mountain rain forest, lowland rain forest, deciduous monsoon forest, and tropical cloud forest was much higher than that of plantation or other ecosystems, indicating the dominant role of tropical rain forest ecosystem in providing ecosystem services. In addition, based on the GEP accounting results of the national park, we put forward relevant suggestions for further exploring the realization path and realization mechanism of ecological product value.

[Influence of LBP alone or Combined with TRAIL on Apoptosis of MLL Rearranged Leukemic Cells].

OBJECTIVE: To investigate the effect of lycium barbarum polysaccharide (LBP) alone or combined with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the apoptosis of leukemia cell lines with MLL gene-rearrangement, and to explore the cell apoptotic pathway after the combined action. METHODS: MLL-ALL cell line KOCL44 and KOCL45 were selected as the research object, then the control and experimental groups were set up. The cell survival rate was measured by the trypan blue dye exclusion method, the cell early apoptosis and expression of death receptors on the cell surface were detected by flow cytometry with Annexin-V/PI double staining. The protein level of caspase-8, BID, caspase-3, caspase-9, BAD, BCL-2, as well as mitochondrial and cytosol Cyto-C were detected by Western blot. RESULTS: LBF combined with TRAIL inhibited the growth of KOCL44 and KOCL-45 cells and showed the synergistic effect, the results of flow cytometry with Amnexiu V/PI double staining were consistent with above-mentioned results. After treatment of KOCL44 and KOCL45 cells with LBF plus TRAIL, the significant expression of DR4 on cell surface was not found, while the expression of DR4 receptor was enhanced significantly, the pro-apoptotic proteins including caspase-8, BID, caspase-3, caspase-9 and BAD were activated significantly and BCL-2 was suppressed significantly with time-dependent manner. The expression of mitochondria cyto-C in KOCL44 and KOCL45 decreased along with prolonging of treatment time (r=-0.95, r=-0.866), while the expression of cytosol cyto-C in KOCL44 and KOCL45 increased along with prolonging of treatment time (r=0.883, r=0.903). CONCLUSION: The combination of LBP and TRAIL significantly increases the apoptosis of KOCL44 and KOCL45, and the LBP and TRAIL can up-regulate the expression of TRAIL death receptor-DR5 on the cell surface, activate the pathway of caspase and mito-chrondia mitachondria, thus enhance the sensitivity of KOCL44 and KOCL45 to TRAIL induced apoptosis through both mitochondrial and apoptotic pathway.

[Functional diversity characteristics of canopy tree species of Jianfengling tropical montane rainforest on Hainan Island, China.] / æµ·å—å°–å³°å²­çƒ­å¸¦å±±åœ°é›¨æž—æž—å† å±‚æ ‘ç§åŠŸèƒ½å¤šæ ·æ€§ç‰¹å¾.

Based on three 1-hm2 plots of Jianfengling tropical montane rainforest on Hainan Island, 11 commom used functional traits of canopy trees were measured. After combining with topographical factors and trees census data of these three plots, we compared the impacts of weighted species abundance on two functional dispersion indices, mean pairwise distance (MPD) and mean nearest taxon distance (MNTD), by using single- and multi-dimensional traits, respectively. The relationship between functional richness of the forest canopies and species abundance was analyzed. We used a null model approach to explore the variations in standardized size effects of MPD and MNTD, which were weighted by species abundance and eliminated the influences of species richness diffe-rences among communities, and assessed functional diversity patterns of the forest canopies and their responses to local habitat heterogeneity at community's level. The results showed that variation in MPD was greatly dependent on the dimensionalities of functional traits as well as species abundance. The correlations between weighted and non-weighted MPD based on different dimensional traits were relatively weak (R=0.359-0.628). On the contrary, functional traits and species abundance had relatively weak effects on MNTD, which brought stronger correlations between weighted and non-weighted MNTD based on different dimensional traits (R=0.746-0.820). Functional dispersion of the forest canopies were generally overestimated when using non-weighted MPD and MNTD. Functional richness of the forest canopies showed an exponential relationship with species abundance (F=128.20; R2=0.632; AIC=97.72; P＜0.001), which might exist a species abundance threshold value. Patterns of functional diversity of the forest canopies based on different dimensional functional traits and their habitat responses showed variations in some degree. Forest canopies in the valley usually had relatively stronger biological competition, and functional diversity was higher than expected functional diversity randomized by null model, which indicated dispersed distribution of functional traits among canopy tree species in this habitat. However, the functional diversity of the forest canopies tended to be close or lower than randomization in the other habitat types, which demonstrated random or clustered distribution of the functional traits among canopy tree species.

[Bird species diversity and related protection measures in urban park green spaces of Loudi City, Hunan Province of China].

Urban park green space is an important physical part of urban ecosystem, and also, the important habitat and carrier for birds and other animals. Rapid urbanization induces the great change in the spatial pattern of urban park green space, while the patched distribution of urban park green space has the habitat features similar to 'habitat islands', giving obvious effects on urban avian communities. In order to understand the bird species distribution and species diversity in Loudi City and to provide the basic information for the bird conservation, a line transect method and a quadrat sampling method were adopted to investigate the distribution pattern and species richness of the birds across seven urban parks in the Loudi City from November, 2010 to January, 2012. A total of 56 birds species belonging to 11 orders and 27 families were recorded, among which, there were 32, 12 and 12 species belonging to resident birds, summer migrant birds and winter migrant birds, accounting for 57.2%, 21.4% and 21.4%, respectively. As for the fauna, there were 27, 14, and 15 bird species belonging to oriental species, palaearctic species and widely distributed species, accounting for 48.2%, 25.0% and 26.8%, respectively. A total of 7 species belonging to the second class of the national key protected species were recorded, accounting for 12.5% of the total. The Shannon, Pielou and G-F indices of the bird communities in the urban parks in Loudi City were 1.49, 0.85 and 0.62, respectively. Zhushan Park had the highest species number (42), Shannon index (1.41), G index (3.46), F index (6.12) and G-F index (0.43), and Yueqin Hill Park had the highest Pielou index (0.92). The reasons of the poor bird species in Loudi City were analyzed, and some suggestions for preventing the birds were put forward.

Strong neutral spatial effects shape tree species distributions across life stages at multiple scales.

Traditionally, ecologists use lattice (regional summary) count data to simulate tree species distributions to explore species coexistence. However, no previous study has explicitly compared the difference between using lattice count and basal area data and analyzed species distributions at both individual species and community levels while simultaneously considering the combined scenarios of life stage and scale. In this study, we hypothesized that basal area data are more closely related to environmental variables than are count data because of strong environmental filtering effects. We also address the contribution of niche and the neutral (i.e., solely dependent on distance) factors to species distributions. Specifically, we separately modeled count data and basal area data while considering life stage and scale effects at the two levels with simultaneous autoregressive models and variation partitioning. A principal coordinates of neighbor matrix (PCNM) was used to model neutral spatial effects at the community level. The explained variations of species distribution data did not differ significantly between the two types of data at either the individual species level or the community level, indicating that the two types of data can be used nearly identically to model species distributions. Neutral spatial effects represented by spatial autoregressive parameters and the PCNM eigenfunctions drove species distributions on multiple scales, different life stages and individual species and community levels in this plot. We concluded that strong neutral spatial effects are the principal mechanisms underlying the species distributions and thus shape biodiversity spatial patterns.