Synthesis and EL Properties of Conjugated Copolymer Materials Containing Various Comonomers

1 Results Polymeric light-emitting diodes (PLEDs) have attracted much scientific and technological research interest due to a number of advantages over inorganic or organic small molecules for use in LEDs: better processability,lower operating voltages,faster response times,lower production costs,and high flexibility.Polyfluorene has been selected for the polymer backbone,because of its large band gap,facile substitution at the C9 position of fluorene,good chemical and thermal stability,and high photolu...     

A new algorithm for building the GSA-form

Gated Single Assignment (GSA) form is used to transform an imperative program into a form suitable for dataflow interpretation. We describe a GSA-formed Control Flow Graph (CFG) that contains gating functions and the information of switches. We also present an algorithm to transform an imperative program into a GSA-formed CFG. Transformation of an imperative program into a GSA-formed CFG provides the basis for generating dataflow graphs(DFG). By using GSA-formed CFG, we can transform an imperative program into a DFG more simply comparing with previous methods, and show an expectation of use with demand- and control-driven model. As we create an intermediate form which has essential information for translation, it will be used to do transformations for various kinds of dataflow models.     

Function and regulation of Dyrk1A: towards understanding Down syndrome

Down syndrome (DS) is associated with a variety of symptoms, such as incapacitating mental retardation and neurodegeneration (i.e., Alzheimer’s disease), that prevent patients from leading fully independent lives. These phenotypes are a direct consequence of the overexpression of chromosome 21 genes, which are present in duplicate due to non-disjunction of chromosome 21. Accumulating data suggest that the chromosome 21 gene product, dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (Dyrk1A), participates in the pathogenic mechanisms underlying the mental and other physical symptoms of DS. In this review, we summarize the evidence supporting a role for Dyrk1A in DS, especially DS pathogenesis. Recently, several natural and synthetic compounds have been identified as Dyrk1A inhibitors. Understanding the function and regulation of Dyrk1A may lead to the development of novel therapeutic agents aimed at treating DS.     

Parameter Space Restrictions in State Space Models

The state space model is widely used to handle time series data driven by related latent processes in many fields. In this article, we suggest a framework to examine the relationship between state space models and autoregressive integrated moving average (ARIMA) models by examining the existence and positive‐definiteness conditions implied by auto‐covariance structures. This study covers broad types of state space models frequently used in previous studies. We also suggest a simple statistical test to check whether a certain state space model is appropriate for the specific data. For illustration, we apply the suggested procedure in the analysis of the United States real gross domestic product data. Copyright © 2011 John Wiley & Sons, Ltd.     

Crystal structure of the human centromeric nucleosome containing CENP-A

In eukaryotes, accurate chromosome segregation during mitosis and meiosis is coordinated by kinetochores, which are unique chromosomal sites for microtubule attachment. Centromeres specify the kinetochore formation sites on individual chromosomes, and are epigenetically marked by the assembly of nucleosomes containing the centromere-specific histone H3 variant, CENP-A. Although the underlying mechanism is unclear, centromere inheritance is probably dictated by the architecture of the centromeric nucleosome. Here we report the crystal structure of the human centromeric nucleosome containing CENP-A and its cognate α-satellite DNA derivative (147 base pairs). In the human CENP-A nucleosome, the DNA is wrapped around the histone octamer, consisting of two each of histones H2A, H2B, H4 and CENP-A, in a left-handed orientation. However, unlike the canonical H3 nucleosome, only the central 121 base pairs of the DNA are visible. The thirteen base pairs from both ends of the DNA are invisible in the crystal structure, and the αN helix of CENP-A is shorter than that of H3, which is known to be important for the orientation of the DNA ends in the canonical H3 nucleosome. A structural comparison of the CENP-A and H3 nucleosomes revealed that CENP-A contains two extra amino acid residues (Arg?80 and Gly?81) in the loop 1 region, which is completely exposed to the solvent. Mutations of the CENP-A loop 1 residues reduced CENP-A retention at the centromeres in human cells. Therefore, the CENP-A loop 1 may function in stabilizing the centromeric chromatin containing CENP-A, possibly by providing a binding site for trans-acting factors. The structure provides the first atomic-resolution picture of the centromere-specific nucleosome.     

Hundreds of variants clustered in genomic loci and biological pathways affect human height

Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P?相似文献   

Numerical simulation on the microstress and microstrain of low Si-Mn-Nb dual-phase steel

According to the stress-strain curves of single-phase martensite and single-phase ferrite steels, whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel, the stress-strain curve of the low Si-Mn-Nb dual-phase steel was simulated using the finite element method (FEM). The simulated result was compared with the measured one and they fit closely with each other, which proves that the FE model is correct. Based on the FE model, the microstress and microstrain of the dual-phase steel were analyzed. Meanwhile, the effective factors such as the volume fraction of martensite and the yield stress ratio between martensite and ferrite phases on the stress-strain curves of the dual-phase steel were simulated, too. The simulated results indicate that for the low Si-Mn-Nb dual-phase steel, the maximum stress occurs in the martensite region, while the maximum strain occurs in the ferrite one. The effect of the volume fraction of martensite (f_M) and the yield stress ratio on the stress-strain curve of the dual-phase steel is small in the elastic part, while it is obvious in the plastic part. In the plastic part of this curve, the strain decreases with the increase of f_M, while it decreases with the decrease of the yield stress ratio.     

Graphene and boron nitride lateral heterostructures for atomically thin circuitry

Precise spatial control over the electrical properties of thin films is the key capability enabling the production of modern integrated circuitry. Although recent advances in chemical vapour deposition methods have enabled the large-scale production of both intrinsic and doped graphene, as well as hexagonal boron nitride (h-BN), controlled fabrication of lateral heterostructures in these truly atomically thin systems has not been achieved. Graphene/h-BN interfaces are of particular interest, because it is known that areas of different atomic compositions may coexist within continuous atomically thin films and that, with proper control, the bandgap and magnetic properties can be precisely engineered. However, previously reported approaches for controlling these interfaces have fundamental limitations and cannot be easily integrated with conventional lithography. Here we report a versatile and scalable process, which we call 'patterned regrowth', that allows for the spatially controlled synthesis of lateral junctions between electrically conductive graphene and insulating h-BN, as well as between intrinsic and substitutionally doped graphene. We demonstrate that the resulting films form mechanically continuous sheets across these heterojunctions. Conductance measurements confirm laterally insulating behaviour for h-BN regions, while the electrical behaviour of both doped and undoped graphene sheets maintain excellent properties, with low sheet resistances and high carrier mobilities. Our results represent an important step towards developing atomically thin integrated circuitry and enable the fabrication of electrically isolated active and passive elements embedded in continuous, one-atom-thick sheets, which could be manipulated and stacked to form complex devices at the ultimate thickness limit.