1,770 research outputs found
Influence of Thread Design on Implant Positioning in Immediate Implant Placement
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141508/1/jper1420.pd
Anti-tumor effect of polysaccharides from rhizome of Curculigo orchioides Gaertn on cervical cancer
Purpose: To investigate the anti-tumor effects of polysaccharides from Curculigo orchioides (PDC) on cervical cancer and the possible mechanisms involved.Methods: A Box–Behnken design (BBD) was employed to optimize extraction conditions for PDC. The anti-tumor effect of PDC on cervical cancer was investigated in vivo in mice injected with Hela cells. The parameters measured were tumor volume and weight. In vitro anti-tumor effects of PDC were assessed by measuring expressions of caspase-3, caspase-9 and P53 proteins in Hela cells via ELISA assay. Thymus and spleen indices were calculated for assessment of PDC effect on immune function.Results: The optimum extraction conditions predicted by the response surface methodology (RSM) were: extraction time = 1.58 h, ratio-of-water-to-sample = 30.05 mL/g and extraction number = 1.95. PDC showed significant anti-tumor effect on cervical cancer in mice. It significantly increased thymus and spleen indices in mice; and significantly up-regulated expressions of caspase-3, caspase-9 and P53 proteins in HeLa cells.Conclusion: PDC has significant anti-tumor effect on cervical cancer in vivo and in vitro, most probably through mechanisms involving enhancement on immune function and induction of apoptosis.Keyword: Curculigo orchioides, Polysaccharides, Cervical cancer, HeLa cells, Apoptosi
Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau
The mechanisms of species coexistence within a community have always been the focus in ecological research. Community phylogenetic structure reflects the relationship of historical processes, regional environments, and interactions between species, and studying it is imperative to understand the formation and maintenance mechanisms of community composition and biodiversity. We studied the phylogenetic structure of the shrub communities in arid and semiarid areas of the Mongolian Plateau. First, the phylogenetic signals of four plant traits (height, canopy, leaf length, and leaf width) of shrubs and subshrubs were measured to determine the phylogenetic conservation of these traits. Then, the net relatedness index (NRI) of shrub communities was calculated to characterize their phylogenetic structure. Finally, the relationship between the NRI and current climate and paleoclimate (since the Last Glacial Maximum, LGM) factors was analyzed to understand the formation and maintenance mechanisms of these plant communities. We found that desert shrub communities showed a trend toward phylogenetic overdispersion; that is, limiting similarity was predominant in arid and semiarid areas of the Mongolian Plateau despite the phylogenetic structure and formation mechanisms differing across habitats. The typical desert and sandy shrub communities showed a significant phylogenetic overdispersion, while the steppified desert shrub communities showed a weak phylogenetic clustering. It was found that mean winter temperature (i.e., in the driest quarter) was the major factor limiting steppified desert shrub phylogeny distribution. Both cold and drought (despite having opposite consequences) differentiated the typical desert to steppified desert shrub communities. The increase in temperature since the LGM is conducive to the invasion of shrub plants into steppe grassland, and this process may be intensified by global warming
Oxygen dissociation on the C3N monolayer: A first-principles study
The oxygen dissociation and the oxidized structure on the pristine C3N
monolayer in exposure to air are the inevitably critical issues for the C3N
engineering and surface functionalization yet have not been revealed in detail.
Using the first-principles calculations, we have systematically investigated
the possible O2 adsorption sites, various O2 dissociation pathways and the
oxidized structures. It is demonstrated that the pristine C3N monolayer shows
more O2 physisorption sites and exhibits stronger O2 adsorption than the
pristine graphene. Among various dissociation pathways, the most preferable one
is a two-step process involving an intermediate state with the chemisorbed O2
and the barrier is lower than that on the pristine graphene, indicating that
the pristine C3N monolayer is more susceptible to oxidation than the pristine
graphene. Furthermore, we found that the most stable oxidized structure is not
produced by the most preferable dissociation pathway but generated from a
direct dissociation process. These results can be generalized into a wide range
of temperatures and pressures using ab initio atomistic thermodynamics. Our
findings deepen the understanding of the chemical stability of 2D crystalline
carbon nitrides under ambient conditions, and could provide insights into the
tailoring of the surface chemical structures via doping and oxidation.Comment: 23 pages,8 figure
Cervical Enamel Projections in Unusual Locations: A Case Report and Miniâ Review
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142078/1/jper0789.pd
2-{[3-Methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methylsulfanyl}-1H-benzimidazole monohydrate
The asymmetric unit of the title compound, C16H14F3N3OS·H2O, contains two independent molecules (A and B) and two water molecules, one of which is disordered over two positions in a 0.790 (8):0.210 (8) ratio. The molecular conformations are close, the benzimidazole mean plane and pyridine ring forming dihedral angles of 1.8 (3) and 0.1 (2)° in molecules A and B, respectively. The water molecules are involved in formation of two independent hydrogen-bonded chains via N—H⋯O and O—H⋯N hydrogen bonds. Chains propagating along the a axis are formed by molecule A and one independent water molecule, while chains propagating along the b axis are formed by molecule B and the other independent water molecule. The crystal packing exhibits π–π interactions, as indicated by short distances of 3.607 (3) and 3.701 (3) Å between the centroids of the imidazole and pyridine rings of neighbouring molecules
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