63 research outputs found
The detection and interpretation of long-term changes in ozone from space
Long-term measurements of backscattered ultraviolet radiances, now being acquired by orbiting monochromators, will provide the basis for seeking trends in atmospheric ozone. The unambiguous detection of ozone trends on decadal time scales demands a data set that is essentially free of instrument drifts. Periodic flights of an ultraviolet monochromator on the space shuttle will provide an independent means of evaluating the long-term stability of identical instruments operating on free-flying satellites. A successful calibration of the free-flying sensors using the shuttle instrument places strict demands on calibration repeatability from one flight to the next. In addition, spatial and temporal variability in cloud cover could pose further complications in carrying out these in-flight calibrations
Electrorheological Elastomers
Electrorheological elastomers (EREs) are smart elastomers with tunable dynamic properties by applying electric field. They are composed by polarizable particles dispersing within elastomers matrix. In comparison with electrorheological fluids, the particles in EREs do not undergo aggregation and sedimentation. Without the requirement of large-sized electromagnetic coils, the smart devices based on EREs have simpler structures than those based on magnetorheological (MR) elastomers. The unique properties and merits of EREs give rise to their bright future in various fields. During the past decades, great progress has been made by scholars around the world. In this chapter, the conception, preparation, physical mechanisms, classification, development, influence factors, and applications of electrorheological elastomers is reviewed
Influence of Fe 3
The magnetic electrospinning (MES) method has been applied to generate aligned nanofibers. But researchers have different viewpoints on the usage of magnetic particles in the polymeric solutions. In order to investigate the effect of magnetic particles in forming the ordered fibers, the poly(lactic-co-glycolic acid) solutions with or without Fe3O4 nanoparticles were electrospun via MES. The fibers were compared at different voltages (13.5, 15.5, 17.5, and 19.5âkV) and flow rates (0.6, 0.9, 1.2, and 1.8âmL/h). It is shown that the well-aligned fibers can be fabricated by both magnetic and nonmagnetic solutions. The doping of Fe3O4 nanoparticles can increase the aligned fibers in some degree, especially at high applied voltage and flow rate. The diameters of fibers electrospun by MES were smaller than those by conventional electrospinning, and the diameter of fibers by MES without magnet particles was the smallest
Microspheres Assembled from ChitosanâGraftâPoly(lactic acid) MicelleâLike CoreâShell Nanospheres for Distinctly Controlled Release of Hydrophobic and Hydrophilic Biomolecules
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122426/1/mabi201600020-sup-0001-S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122426/2/mabi201600020.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122426/3/mabi201600020_am.pd
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Integrated Bio-Entity Network: A System for Biological Knowledge Discovery
A significant part of our biological knowledge is centered on relationships between biological entities (bio-entities) such as proteins, genes, small molecules, pathways, gene ontology (GO) terms and diseases. Accumulated at an increasing speed, the information on bio-entity relationships is archived in different forms at scattered places. Most of such information is buried in scientific literature as unstructured text. Organizing heterogeneous information in a structured form not only facilitates study of biological systems using integrative approaches, but also allows discovery of new knowledge in an automatic and systematic way. In this study, we performed a large scale integration of bio-entity relationship information from both databases containing manually annotated, structured information and automatic information extraction of unstructured text in scientific literature. The relationship information we integrated in this study includes proteinâprotein interactions, protein/gene regulations, proteinâsmall molecule interactions, proteinâGO relationships, proteinâpathway relationships, and pathwayâdisease relationships. The relationship information is organized in a graph data structure, named integrated bio-entity network (IBN), where the vertices are the bio-entities and edges represent their relationships. Under this framework, graph theoretic algorithms can be designed to perform various knowledge discovery tasks. We designed breadth-first search with pruning (BFSP) and most probable path (MPP) algorithms to automatically generate hypothesesâthe indirect relationships with high probabilities in the network. We show that IBN can be used to generate plausible hypotheses, which not only help to better understand the complex interactions in biological systems, but also provide guidance for experimental designs
Two-stage association study to identify the genetic susceptibility of a novel common variant of rs2075290 in ZPR1 to type 2 diabetes
The SNP of rs964184 in ZPR1 has recently been associated with type 2 diabetes mellitus (T2DM) in Japanese individuals. To comprehensively investigate the association of common variants in ZPR1 with T2DM in Han Chinese individuals, we designed a two-stage case-control study of 3,505 T2DM patients and 6,911 unrelated healthy Han Chinese individuals. A total of 24 single nucleotide polymorphisms (SNPs) were genotyped, and single-SNP association, imputation and gender-specific association analyses were performed. To increase the coverage of genetic markers, we implemented imputation techniques to extend the number of tested makers to 280. A novel SNP, rs2075290, and the previously reported SNP, rs964184, were significantly associated with T2DM in the two independent datasets, and individuals harboring the CC genotype of rs2075290 and GG genotype of rs964184 exhibited higher levels of fasting plasma glucose (FPG) and blood hemoglobin A1c (HbA1c) than individuals of other genotypes. Additionally, haplotype analyses indicated that two haplotype blocks containing rs2075290 or rs964184 were also significantly associated with T2DM. In summary, these results suggest that ZPR1 plays an important role in the etiology of T2DM, and this gene might be involved in abnormal glucose metabolism
Photoacoustic Identification of Laser-induced Microbubbles as Light Scattering Centers for Optical Limiting in Liquid Suspension of Graphene Nanosheets
Liquid suspensions of carbon nanotubes, graphene and transition metal
dichalcogenides have exhibited excellent performance in optical limiting.
However, the underlying mechanism has remained elusive and is generally
ascribed to their superior nonlinear optical properties such as nonlinear
absorption or nonlinear scattering. Using graphene as an example, we show that
photo-thermal microbubbles are responsible for the optical limiting as strong
light scattering centers: graphene sheets absorb incident light and become
heated up above the boiling point of water, resulting in vapor and microbubble
generation. This conclusion is based on direct observation of bubbles above the
laser beam as well as a strong correlation between laser-induced ultrasound and
optical limiting. In-situ Raman scattering of graphene further confirms that
the temperature of graphene under laser pulses rises above the boiling point of
water but still remains too low to vaporize graphene and create graphene plasma
bubbles. Photo-thermal bubble scattering is not a nonlinear optical process and
requires very low laser intensity. This understanding helps us to design more
efficient optical limiting materials and understand the intrinsic nonlinear
optical properties of nanomaterials
Effect of Microstructure of Spongy Bone in Different Parts of Woodpeckerâs Skull on Resistance to Impact Injury
Natural biological materials such as bone, teeth and nacre are nano-composites of protein and mineral frequently exhibit highly superior strength for self-assembly and nanofabrication. Mineral mass and microstructure/nanostructure of bone are susceptible to stimulation by mechanical loads, ensuring that its mechanical behavior and strength are adapted to environmental changes. Woodpeckers repeatedly drum tree trunks at a speed of 6-7âmâsâ1 and acceleration of ~1000âg with no head injuries. The uneven distribution of spongy bone has been founded on woodpecker's skull in our previous study. More knowledge of the distribution of the shock-absorbing spongy bone could be incorporated into the design of new safety helmets, sports products, and other devices that need to be able to resist the impact. In this study, the effect of microstructure of spongy bone in different parts on woodpeckerâs skull compared with other birds was observed and analyzed. It was found that the unique coordinate ability of micro-parameters in different parts of woodpeckerâs skull could be one of the most important roles of its resistance to impact injury. Better understanding of the materials would provide new inspirations of shock-absorbing composite materials in engineering
MiR-9 promotes microglial activation by targeting MCPIP1
Microglia participate in innate inflammatory responses within the central nervous system. The highly conserved microRNA-9 (miR-9) plays critical roles in neurogenesis as well as axonal extension. Its role in microglial inflammatory responses, however, remains poorly understood. Here we identify a unique role of miR-9 in mediating the microglial inflammatory response via distinct signalling pathways. MiR-9-mediated regulation of cellular activation involved downregulated expression of the target protein, monocyte chemotactic protein-induced protein 1 (MCPIP1) that is crucial for controlling inflammation. Results indicate that miR-9-mediated cellular activation involved signalling via the NF-kappa B pathway, but not the beta-catenin pathway
Examining the Dynamic Association of BMI and Mortality in the Framingham Heart Study
Based on the 40-year follow-up of the Framingham Heart Study (FHS), we used logistic regression models to demonstrate that different designs of an observational study may lead to different results about the association between BMI and all-cause mortality. We also used dynamic survival models to capture the time-varying relationships between BMI and mortality in FHS. The results consistently show that the association between BMI and mortality is dynamic, especially for men. Our analysis suggests that the dynamic property may explain part of the heterogeneity observed in the literature about the association of BMI and mortality
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