Some new results on superimposed codes

A (w,r) cover‐free family is a family of subsets of a finite set such that no intersection of w members of the family is covered by a union of r others. A (w,r) superimposed code is the incidence matrix of such a family. Such a family also arises in cryptography as the concept of key distribution pattern. In the present paper, we give some new results on superimposed codes. First we construct superimposed codes from super‐simple designs which give us results better than superimposed codes constructed by other known methods. Next we prove the uniqueness of the (1,2) superimposed code of size 9 × 12, the (2,2) superimposed code of size 14 × 8, and the (2,3) superimposed code of size 30 × 10. Finally, we improve numerical values of upper bounds for the asymptotic rate of some (w,r) superimposed codes. © 2004 Wiley Periodicals, Inc.     

The effect of the bridge group on the thermal stability of nitro-substituted aromatic polyamides

The effect of introducing a bridge group into the diamine moiety on the thermal stability of aromatic polyamides substituted with nitro group in the diamine ring at the ortho position to the amide group was studied. Our present work showed that the bridge group, whether it was electron withdrawing or releasing, did not have a significant effect on the activity of the nitro group for the intramolecular cyclization reaction to poly(benzoxazole)s.     

Substrate interaction effects on order to disorder transition behavior in block copolymer films

We present an overview of the recent progress on the phase transition in the block copolymer (BCP) films in terms of the interfacial interactions effects of the substrates and the χ (Flory-Huggins segmental interaction parameter) effects between the two blocks. For the BCP films thinner than a critical thickness (L_c) above which the transition is independent of film thickness, the order-to-disorder transition (ODT) increased or decreased with decreasing film thickness depending on the interfacial interaction types. The rapid and slow changes in the ODT were attributed to the relative magnitude of enthalpic contribution to χ between two blocks. Interestingly, a periodic amplification in the block composition for the BCP films suppressed the compositional fluctuation in the film geometry, resulting in the ODT shifts from the bulk ODTs above L_c. This effect of the BCP films was more illustrated by the ODT shift effects depending on the strength of the preferential interactions on the substrates. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Sieving properties of end group‐halogenated Pluronic polymer matrix in DNA separation under nondenaturing CE analysis

CE‐SSCP analysis is a well‐established DNA separation method that is based on variations in mobility caused by sequence‐induced differences in the conformation of single‐stranded DNA. The resolution of CE‐SSCP analysis was improved by using a Pluronic polymer matrix, and it has been successfully applied in various genetic analyses. Because the Pluronic polymer forms a micellar cubic structure in the capillary, it provides a stable internal structure for high‐resolution CE‐SSCP analysis. We hypothesized that formation of micellar cubic structure is influenced by the end hydroxyl group of the Pluronic polymer, which affords structural stability through hydrogen bonding. To test this hypothesis, the hydroxyl group was halogenated to eliminate the hydrogen bonding without disturbing the polarity of polymer matrix. CE‐SSCP resolution of two DNA fragments with a single base difference was significantly worse in the halogenated polymer matrices due to band broadening. The viscoelastic properties of control (which has hydroxyl group), chlorinated, and brominated F108 solution upon heating were also investigated by rheological experiments, and we found that gelation was significantly associated with resolution. In this series of experiments, the effect of the hydroxyl group in Pluronic polymer matrix on separation resolution of CE‐SSCP analysis was demonstrated.     

Precise characterization method of antibody‐conjugated magnetic nanoparticles for pathogen detection using stuffer‐free multiplex ligation‐dependent probe amplification

Antibody‐conjugated magnetic nanoparticles (Ab‐MNPs) have potential in pathogen detection because they allow target cells to be easily separated from complex sample matrices. However, the sensitivity and specificity of pathogen capture by Ab‐MNPs generally vary according to the types of MNPs, antibodies, and sample matrices, as well as preparation methods, including immobilization. Therefore, achieving a reproducible analysis utilizing Ab‐MNPs as a pathogen detection method requires accurate characterization of Ab‐MNP capture ability and standardization of all handling processes. In this study, we used high‐resolution CE‐single strand conformational polymorphism coupled with a stuffer‐free multiplex ligation‐dependent probe amplification system to characterize Ab‐MNPs. The capture ability of Ab‐MNPs targeting Salmonella enteritidis and nine pathogens, including S. enteritidis, was analyzed in phosphate buffer and milk. The effect of storage conditions on the stability of Ab‐MNPs was also assessed. The results showed that the stuffer‐free multiplex ligation‐dependent probe amplification system has the potential to serve as a standard characterization method for Ab‐MNPs. Moreover, the precise characterization of Ab‐MNPs facilitated robust pathogen detection in various applications.     

A multiplex single nucleotide polymorphism genotyping method using ligase‐based mismatch discrimination and CE‐SSCP

Accuracy, simplicity, and cost‐effectiveness are the most important criteria for a genotyping method for SNPs compatible with clinical use. One method developed for SNP genotyping, ligase‐based discrimination, is considered the simplest for clinical diagnosis. However, multiplex assays using this method are limited by the detection method. Although CE has been introduced as an alternative to error prone microarray‐based detection, the design process and multiplex assay procedure are complicated because of the DNA size‐dependent separation principle. In this study, we developed a simple and accurate multiplex genotyping method using reaction condition‐optimized ligation and high‐resolution CE‐based SSCP. With this high‐resolution CE‐SSCP system, we are able to use similar‐sized probes, thereby eliminating the complex probe design step and simplifying the optimization process. We found that this method could accurately discriminate single‐base mismatches in SNPs of the tp53 gene, used as targets for multiplex detection.     

Rapid and sensitive detection of lower respiratory tract infections by stuffer‐free multiplex ligation‐dependent probe amplification

Lower respiratory tract infection is one of the most common infectious diseases. However, conventional methods for detecting infectious pathogens are time‐consuming, and generally have a limited impact on early therapeutic decisions. We previously reported a rapid and sensitive method for detecting such pathogens using stuffer‐free multiplex ligation‐dependent probe amplification coupled with high‐resolution CE‐SSCP. In this study, we report an application of this method to the detection of respiratory pathogens. As originally configured, this method was capable of simultaneously detecting seven bacterial species responsible for lower respiratory tract infections, but its detection limit and assay time were insufficient to provide useful information for early therapeutic decisions. To improve sensitivity and shorten assay time, we added a target‐specific preamplification step, improving the detection limit from 50 pg of genomic DNA to 500 fg. We further decreased time requirements by optimizing the hybridization step, enabling the entire assay to be completed within 7 h while maintaining the same detection limit. Taken together, these improvements enable the rapid detection of infectious doses of pathogens (i.e. a few dozen cells), establishing the strong potential of the refined method, particularly for aiding early treatment decisions.     

Efficient Diketopyrrolopyrrole‐Based Small‐Molecule Bulk‐Heterojunction Solar Cells with Different Electron‐Donating End‐Groups

A series of small molecules that contained identical π‐spacers (ethyne), a central diketopyrrolopyrrole (DPP) unit, and different aromatic electron‐donating end‐groups were synthesized and used in organic solar cells (OSCs) to study the effect of electron‐donating groups on the device performance. The three compounds, DPP‐A‐Ph , DPP‐A‐Na , and DPP‐A‐An , possessed intense absorption bands that covered a wide range, from 350 to 750 nm, and relatively low HOMO energy levels, from ?5.50 to ?5.55 eV. DPP‐A‐An , which contained anthracene end‐groups, demonstrated a stronger absorbance and a higher hole mobility than DPP‐A‐Ph , which contained phenyl groups, and DPP‐A‐Na , which contained naphthalene units. The power‐conversion efficiencies (PCEs) of OSCs based on organic:PC₇₁BM blends (1:1, w/w) with a processed DIO additive were 3.93 % for DPP‐A‐An , 3.02 % for DPP‐Na , and 2.26 % for DPP‐A‐Ph . These findings suggest that a DPP core that is functionalized with electron‐donating capping groups constitutes a promising new class of solution‐processable small molecules for OSC applications.     

Tritium and stable isotope content variation in precipitation at Hongseung: West Korea Region

Journal of Radioanalytical and Nuclear Chemistry - Tritium and stable isotopes contents in precipitation were analyzed on a monthly base at Hongseung which was located middle west of Korea...