On multiple portmanteau tests*

Abstract. The portmanteau statistic based on the first m residual autocorrelations is used for diagnostic checks on the adequacy of fitting a model with varying m. In this article, we propose an approximation of the joint probability of multiple portmanteau tests with different degrees of freedom (DF). This distribution is easy to compute when all DF are even integers; its empirical behaviour is clarified in terms of asymptotic theory.     

Functional binders for reversible lithium intercalation into graphite in propylene carbonate and ionic liquid media

Poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), and poly(vinyl alcohol) (PVA), which have oxygen species as functional groups, were utilized as a binder for graphite electrodes, and the electrochemical reversibility of lithium intercalation was examined in PC medium and ionic liquid electrolyte, lithium bis(trifluoromethanesulfonyl)amide dissolved in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide (BMP-TFSA). Columbic efficiency of 75–80% with more than 300 mAh g^?1 was achieved upon first reduction/oxidation cycle in both electrolytes using these binding polymers, which were significantly improved in comparison to a conventional PVdF binder (less than 45% of columbic efficiency for the first cycle). For the graphite-PVdF electrode, co-intercalation and/or decomposition of PC molecules solvating to Li ions were observed by the electrochemical reduction, resulting in the cracking of graphite particles. In contrast, the co-intercalation and decomposition of PC molecules and BMP cations for the first reduction process were completely suppressed for the graphite electrodes prepared with the polymers containing oxygen atoms. It was proposed that the selective permeability of lithium ions was attained by the uniform coating of the graphite particles with PAA, PMA, and PVA polymers, because the electrostatic interaction between the positively charged lithium ions and negatively charged oxygen atom in the polymer should modulate the desolvation process of lithium ions during the lithium intercalation into graphite, showing the similar functions like artificial solid-electrolyte interphase.     

β-FeOOH thin film as positive electrode for lithium-ion cells

β-FeOOH thin film was prepared on the surface of a foamed Ni substrate by liquid phase deposition (LPD) method with a chemical equilibrium reaction between metal-fluoro complex and oxyhydroxide to make a low-cost and environmentally friendly positive electrode for high-power batteries. The new film electrode, with a thickness of 316 nm, was found out to give a large discharge capacity of 260 mAh g⁻¹ at 0.05 C rate even without an electro-conductive material. Furthermore, the electrode also showed good discharge performance with the retention of 69.9% at 10-0.05 C current rate, which means a promising positive active material for high-power use.     

Bacteriophages isolated from activated sludge processes and their polyvalency

In this study, bacteriophages were isolated from activated sludge and their host range was studied. Bacterial isolates were obtained from an activated sludge process treating urban sewage, and bacteriophages were obtained by plaque assay using the bacterial isolates obtained in this study as the host. Out of 15 bacteria isolated, 9 supported plaque formation. The host range test was conducted with a combination of 8 bacteriophage isolates and 9 bacterial isolates. All of the 8 bacteriophages tested were found to form plaques on more than 1 host, and 4 of them formed plaques on both gram-positive and gram-negative bacterial isolates. Three of the 8 bacteriophages failed to form plaques on their original bacterial host. The experimental result indicates that bacteriophages are an active part of the activated sludge microbial ecosystem, having a very close ecological relationship with their host bacteria.     

The design of cyclic AMP--recognizing oligopeptides and evaluation of its capability for cyclic AMP recognition using an electrochemical system

A novel 17-mer peptide ligand for cyclic AMP was designed using the amino acid sequences of essential subsites in various cyclic AMP-dependent protein kinase (protein kinase A) families. The Au disk electrode, which was modified with the designed 17-mer oligopeptide, responded to cyclic AMP but virtually did not respond to any other cyclic nucleotides using the ion channel sensor mechanism. On the other hand, a scrambled peptide, which had the same amino acid composition as and had an amino acid sequence different from the 17-mer oligopeptide, did not respond to any nucleotides. This indicates that the designed 17-mer peptide actually acted as a selective ligand for cyclic AMP. This ligand-designing strategy using peptide sequences in target-binding proteins may possibly be extended to the design of peptide ligands for other second messengers.     

Dual-wavelength optical head with a wavelength-selective filter for 0.6- and 1.2-mm-thick-substrate optical disks

A dual-wavelength optical head, believed to be new in design, for 0.6- and 1.2-mm-thick-substrate optical disks was developed by use of 650- and 780-nm-wavelength light and a wavelength-selective filter, which reduces the spherical aberration that is due to the difference in substrate thicknesses and restricts the numerical aperture for 780-nm-wavelength light. According to this configuration, both high light power efficiency and wide image field characteristics are obtained, which are suitable not only for read-only but also for recordable or rewritable optical disk systems. A reading operation for a digital video disc and for a compact disc and a recording operation for a phase change optical disk were successfully demonstrated.     

Influence of cell surface glycoprotein gC produced by pseudorabies virus on cytopathic effect

The wild-type pseudorabies virus (WT-PRV) produced a round-type cytopathic effect (CPE) in PK-15 cell line of porcine kidney origin, while PRVgCs lacking in gC-transmembrane-anchor region and PRVgC-defecting in gC gene produced a syncytium-type CPE. The mouse embryo cell line (BALB/3T3 clone A31) were transfected with recombinant plasmid of pcDNA3 which incorporated with gC gene. The transfected A31/gC cells were stably expressing gC. Only a round-type CPE was observed in these cells infected with WT-PRV, while a syncytium-type CPE was observed in the cells infected with each of the PRVgCs and PRVgC-. Any viruses described above induced a syncytium-type CPE in A31/pcDNA cells transfected with a plasmid without gC gene. By WT-PRV infection, PK-15 cells generated about 2- or 8-fold more gC than the A31/gC and A31/pcDNA cells when gC was measured by hemagglutination test. Flowcytometric analysis revealed that amount of gC on the cell surface of A31/gC and PK-15 cells increased after infection with WT-PRV. Round-type CPE was observed with the increase of gC. These results suggest that the type of CPE formation induced by PRV is dominated by the amount of gC on the infected cell surface.     

Dynein arms are oscillating force generators

Eukaryotic flagella beat rhythmically. Dynein is a protein that powers flagellar motion, and oscillation may be inherent to this protein. Here we determine whether oscillation is a property of dynein arms themselves or whether oscillation requires an intact axoneme, which is the central core of the flagellum and consists of a regular array of microtubules. Using optical trapping nanometry, we measured the force generated by a few dynein arms on an isolated doublet microtubule. When the dynein arms on the doublet microtubule contact a singlet microtubule and are activated by photolysis of caged ATP8, they generate a peak force of approximately 6pN and move the singlet microtubule over the doublet microtubule in a processive manner. The force and displacement oscillate with a peak-to-peak force and amplitude of approximately 2 pN and approximately 30 nm, respectively. The geometry of the interaction indicates that very few (possibly one) dynein arms are needed to generate the oscillation. The maximum frequency of the oscillation at 0.75 mM ATP is approximately 70 Hz; this frequency decreases as the ATP concentration decreases. A similar oscillatory force is also generated by inner dynein arms alone on doublet microtubules that are depleted of outer dynein arms. The oscillation of the dynein arm may be a basic mechanism underlying flagellar beating.