Logic Ciucuits Using Solution-processed Single-walled Carbon Nanotue Transistors

This letter reports on the realization of logic circuits employing solution-processed networks of single-walled carbon nanotubes. We constructed basic logic gates (inverter, NAND and NOR) with n- and p-type field-effect transistors fabricated by solution-based chemical doping. Complementary metal-oxide-semiconductor inverters exhibited voltage gains of up to 20, which illustrates the great potential of carbon nanotube networks for printable flexible electronics.Comment: 12 PAGES, 3 FIGURE

Measure of synonymous codon usage diversity among genes in bacteria

<p>Abstract</p> <p>Background</p> <p>In many bacteria, intragenomic diversity in synonymous codon usage among genes has been reported. However, no quantitative attempt has been made to compare the diversity levels among different genomes. Here, we introduce a mean dissimilarity-based index (<it>D</it>mean) for quantifying the level of diversity in synonymous codon usage among all genes within a genome.</p> <p>Results</p> <p>The application of <it>D</it>mean to 268 bacterial genomes shows that in bacteria with extremely biased genomic G+C compositions there is little diversity in synonymous codon usage among genes. Furthermore, our findings contradict previous reports. For example, a low level of diversity in codon usage among genes has been reported for <it>Helicobacter pylori</it>, but based on <it>D</it>mean, the diversity level of this species is higher than those of more than half of bacteria tested here. The discrepancies between our findings and previous reports are probably due to differences in the methods used for measuring codon usage diversity.</p> <p>Conclusion</p> <p>We recommend that <it>D</it>mean be used to measure the diversity level of codon usage among genes. This measure can be applied to other compositional features such as amino acid usage and dinucleotide relative abundance as a genomic signature.</p

Variation in the Correlation of G + C Composition with Synonymous Codon Usage Bias among Bacteria

G + C composition at the third codon position (GC3) is widely reported to be correlated with synonymous codon usage bias. However, no quantitative attempt has been made to compare the extent of this correlation among different genomes. Here, we applied Shannon entropy from information theory to measure the degree of GC3 bias and that of synonymous codon usage bias of each gene. The strength of the correlation of GC3 with synonymous codon usage bias, quantified by a correlation coefficient, varied widely among bacterial genomes, ranging from −0.07 to 0.95. Previous analyses suggesting that the relationship between GC3 and synonymous codon usage bias is independent of species are thus inconsistent with the more detailed analyses obtained here for individual species

Quantitative analysis of replication-related mutation and selection pressures in bacterial chromosomes and plasmids using generalised GC skew index

BACKGROUND: Due to their bi-directional replication machinery starting from a single finite origin, bacterial genomes show characteristic nucleotide compositional bias between the two replichores, which can be visualised through GC skew or (C-G)/(C+G). Although this polarisation is used for computational prediction of replication origins in many bacterial genomes, the degree of GC skew visibility varies widely among different species, necessitating a quantitative measurement of GC skew strength in order to provide confidence measures for GC skew-based predictions of replication origins. RESULTS: Here we discuss a quantitative index for the measurement of GC skew strength, named the generalised GC skew index (gGCSI), which is applicable to genomes of any length, including bacterial chromosomes and plasmids. We demonstrate that gGCSI is independent of the window size and can thus be used to compare genomes with different sizes, such as bacterial chromosomes and plasmids. It can suggest the existence of different replication mechanisms in archaea and of rolling-circle replication in plasmids. Correlation of gGCSI values between plasmids and their corresponding host chromosomes suggests that within the same strain, these replicons have reproduced using the same replication machinery and thus exhibit similar strengths of replication strand skew. CONCLUSIONS: gGCSI can be applied to genomes of any length and thus allows comparative study of replication-related mutation and selection pressures in genomes of different lengths such as bacterial chromosomes and plasmids. Using gGCSI, we showed that replication-related mutation or selection pressure is similar for replicons with similar machinery

The Effects of Malonic Acid Derivatives and Acetic Acid Derivatives as Coadsorbents on the Photovoltaic Performance of Dye-Sensitized Solar Cells

The effects of malonic acid derivatives and acetic acid derivatives as coadsorbents on the photovoltaic performance of D908 dye-sensitized nanocrystalline TiO 2 solar cells were investigated. Each of phenylmalonic acid (PMA) and cyclopentylacetic acid (CPEAA) coadsorptions was revealed to improve both the photocurrent and the photovoltage of the solar cells. The improved photocurrent was probably due to the suppression of self-quenching of the excited electrons in the dyes by coadsorption of PMA or CPEAA on the TiO 2 that increased in the electron-injection yields from the dye to the TiO 2 . The improved photovoltage was probably due to suppression of recombination between the injected electrons and I 3 − ions on the TiO 2 surface. ATR-FTIR spectroscopy indicated that PMA or CPEAA coadsorption increased the content of bound dye on the TiO 2 surface. This result suggests that PMA or CPEAA coadsorption improved the photocurrent of the solar cells. Electrochemical impedance spectroscopy indicated that PMA or CPEAA coadsorption on the TiO 2 surface increased the charge recombination resistance (R2) and decreased the diffusion resistance in the electrolyte (R3). These results suggest that the coadsorption of PMA or CPEAA on the TiO 2 may improve its photovoltage and photocurrent

Proteome-Wide Prediction of Novel DNA/RNA-Binding Proteins Using Amino Acid Composition and Periodicity in the Hyperthermophilic Archaeon Pyrococcus furiosus

Proteins play a critical role in complex biological systems, yet about half of the proteins in publicly available databases are annotated as functionally unknown. Proteome-wide functional classification using bioinformatics approaches thus is becoming an important method for revealing unknown protein functions. Using the hyperthermophilic archaeon Pyrococcus furiosus as a model species, we used the support vector machine (SVM) method to discriminate DNA/RNA-binding proteins from proteins with other functions, using amino acid composition and periodicities as feature vectors. We defined this value as the composition score (CO) and periodicity score (PD). The P. furiosus proteins were classified into three classes (I–III) on the basis of the two-dimensional correlation analysis of CO score and PD score. As a result, approximately 87% of the functionally known proteins categorized as class I proteins (CO score + PD score > 0.6) were found to be DNA/RNA-binding proteins. Applying the two-dimensional correlation analysis to the 994 hypothetical proteins in P. furiosus, a total of 151 proteins were predicted to be novel DNA/RNA-binding protein candidates. DNA/RNA-binding activities of randomly chosen hypothetical proteins were experimentally verified. Six out of seven candidate proteins in class I possessed DNA/RNA-binding activities, supporting the efficacy of our method

SORL1 Is Genetically Associated with Late-Onset Alzheimer’s Disease in Japanese, Koreans and Caucasians

To discover susceptibility genes of late-onset Alzheimer’s disease (LOAD), we conducted a 3-stage genome-wide association study (GWAS) using three populations: Japanese from the Japanese Genetic Consortium for Alzheimer Disease (JGSCAD), Koreans, and Caucasians from the Alzheimer Disease Genetic Consortium (ADGC). In Stage 1, we evaluated data for 5,877,918 genotyped and imputed SNPs in Japanese cases (n = 1,008) and controls (n = 1,016). Genome-wide significance was observed with 12 SNPs in the APOE region. Seven SNPs from other distinct regions with p-values ,261025 were genotyped in a second Japanese sample (885 cases, 985 controls), and evidence of association was confirmed for one SORL1 SNP (rs3781834, P=7.3361027 in the combined sample). Subsequent analysis combining results for several SORL1 SNPs in the Japanese, Korean (339 cases, 1,129 controls) and Caucasians (11,840 AD cases, 10,931 controls) revealed genome wide significance with rs11218343 (P=1.7761029) and rs3781834 (P=1.0461028). SNPs in previously established AD loci in Caucasians showed strong evidence of association in Japanese including rs3851179 near PICALM (P=1.7161025) and rs744373 near BIN1 (P = 1.3961024). The associated allele for each of these SNPs was the same as in Caucasians. These data demonstrate for the first time genome-wide significance of LOAD with SORL1 and confirm the role of other known loci for LOAD in Japanese. Our study highlights the importance of examining associations in multiple ethnic populations