INTRODUCTION OF CATIONIC GROUPS ONTO CARBON BLACK SURFACE AND THEIR DISPERSIBILITY IN WATER

Imidazoline hydrochlonde groups were successfully introduced onto carbon black surface by the treatment of imidazoline groups, which were introduced by the trapping of 2-(2-imidazolin-2-yl)propane radicals formed by the thermal decomposition of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (AJP) with hydrochloric acid. In addition, arrridine hydrochlonde groups were introduced onto carbon black surface by the radical trapping of 2-methylpropionamidine dihydrochloride radicals formed by the thermal decomposition of 22'-azobis(2-methylpropionamidine) dihydrochloride (AMPAD). The content of imidazoline hydrochlonde and amidine hydrochlonde groups introduced onto carbon black was determined to be 0.6 mmol/g and 0,7 mmol/g, respectively. The mean particle size of AIP/HCl-lreated and AMPAD-treated carbon black was determined to be 31 nm and 16 nm, respectively, by dynamic light scattering method. It was found that the surface of carbon black turned from hydraphobic to hydrophilic by the introduction of cationic moieties and gave a very stable colloidal dispersion in neutral and acidic water at room temperature.     

An Efficient Synthesis of 3-Cyano-1(3H)-Isobehzofuranones

Reaction of o-formyl-N, N-diethylbenzamides (5) with trimethylsilyl cyanide affords the corresponding (0-trimethylsi-lyl)cyanohydrins (6), which on treatment with acetic acid produce 3-cyanophthalides (7) in 80–90% isolated yields.     

Importance of CH/π hydrogen bonds in recognition of the core motif in proline-recognition domains: an ab initio fragment molecular orbital study

We examined CH/π hydrogen bonds in protein/ligand complexes involving at least one proline residue using the ab initio fragment molecular orbital (FMO) method and the program CHPI. FMO calculations were carried out at the Hartree–Fock (HF)/6‐31G*, HF/6‐31G**, second‐order Møller–Plesset perturbation (MP2)/6‐31G*, and MP2/6‐31G** levels for three Src homology 3 (SH3) domains and five proline‐recognition domains (PRDs) complexed with their corresponding ligand peptides. PRDs use a conserved set of aromatic residues to recognize proline‐rich sequences of specific ligands. Many CH/π hydrogen bonds were identified in these complexes. CH/π hydrogen bonds occurred, in particular, in the central part of the proline‐rich motifs. Our results suggest that CH/π hydrogen bonds are important in the recognition of SH3 and PRDs by their ligand peptides and play a vital role in the signal transduction system. Combined use of the FMO method and CHPI analysis is a valuable tool for the study of protein/protein and protein/ligand interactions and may be useful in rational drug design. © 2011 Wiley Periodicals, Inc. J Comput Chem 2011     

Coordination‐Driven Macrocyclization for Locking of Photo‐ and Thermal cis→trans Isomerization of Azobenzene

Both trans and cis isomers of azobenzene‐linked bis‐terpyridine ligand L1 were incorporated in rigid macrocycles linked by Fe^II(tpy)₂ (tpy: terpyridine) units. The complex of the longer trans‐ L1 is dinuclear [(trans‐ L1 )₂ ? Fe^II₂], whereas the complex of the shorter cis‐ L1 is mononuclear [cis‐ L1? Fe^II]. The complex cis‐ L1? Fe^II was not only thermally stable but also photochemically inactive. These results indicate a perfectly locked state of cis‐azobenzene. The stable macrocyclic structure of cis‐ L1? Fe^II causes locking of the isomerization. To the best of our knowledge, this is first example of dual locking of photo‐ and thermal isomerization of cis‐azobenzene.     

Force‐field parameters of the Ψ and Φ around glycosidic bonds to oxygen and sulfur atoms

The Ψ and Φ torsion angles around glycosidic bonds in a glycoside chain are the most important determinants of the conformation of a glycoside chain. We determined force‐field parameters for Ψ and Φ torsion angles around a glycosidic bond bridged by a sulfur atom, as well as a bond bridged by an oxygen atom as a preparation for the next study, i.e., molecular dynamics free energy calculations for protein‐sugar and protein‐inhibitor complexes. First, we extracted the Ψ or Φ torsion energy component from a quantum mechanics (QM) total energy by subtracting all the molecular mechanics (MM) force‐field components except for the Ψ or Φ torsion angle. The Ψ and Φ energy components extracted (hereafter called “the remaining energy components”) were calculated for simple sugar models and plotted as functions of the Ψ and Φ angles. The remaining energy component curves of Ψ and Φ were well represented by the torsion force‐field functions consisting of four and three cosine functions, respectively. To confirm the reliability of the force‐field parameters and to confirm its compatibility with other force‐fields, we calculated adiabatic potential curves as functions of Ψ and Φ for the model glycosides by adopting the Ψ and Φ force‐field parameters obtained and by energetically optimizing other degrees of freedom. The MM potential energy curves obtained for Ψ and Φ well represented the QM adiabatic curves and also these curves' differences with regard to the glycosidic oxygen and sulfur atoms. Our Ψ and Φ force‐fields of glycosidic oxygen gave MM potential energy curves that more closely represented the respective QM curves than did those of the recently developed GLYCAM force‐field. © 2009 Wiley Periodicals, Inc., J Comput Chem, 2009     

Single chirality extraction of single-wall carbon nanotubes for the encapsulation of organic molecules

The hollow inner spaces of single-wall carbon nanotubes (SWCNTs) can confine various types of molecules. Many remarkable phenomena have been observed inside SWCNTs while encapsulating organic molecules (peapods). However, a mixed electronic structure state of the surrounding SWCNTs has impeded a detailed understanding of the physical/chemical properties of peapods and their device applications. We present a single-chirality purification method for SWCNTs that can encapsulate organic molecules. A single-chiral state of (11,10) SWCNTs with a diameter of 1.44 nm, which is large enough for molecular encapsulation, was obtained after a two-step purification method: metal-semiconductor sorting and cesium-chloride sorting. The encapsulation of C(60) to the (11,10) SWCNTs was also succeeded, promising a route toward single-chirality peapod devices.     

Particle dispersibility and giant reduction in dynamic modulus of magnetic gels containing barium ferrite and iron oxide particles

The particle dispersibility of barium ferrite and iron oxide magnetic particles in carrageenan gels was investigated, and the influence of the dispersibility on the giant reduction in the dynamic modulus of the gels was discussed. The gels containing barium ferrite demonstrated giant reductions in the storage Young's modulus on the order of 10 (5) Pa due to magnetization; however, small reductions in the storage modulus of less than 10 (4) Pa were observed for the gels containing iron oxide. The storage modulus of gels with barium ferrite did not follow the Krieger-Dougherty equation above volume fractions of 0.06, indicating the heterogeneous dispersion of the magnetic particles; however, the modulus of the gels with iron oxide satisfied the equation at all volume fractions, suggesting the random dispersion of the particles. It was noted that the gels with barium ferrite demonstrated enhanced nonlinear viscoelasticity and a large value of the loss tangent, while the gels with iron oxide exhibited weak nonlinear viscoelasticity and a small value of the loss tangent. Magnetic measurements indicated high values of remanent magnetization for barium ferrite and low values for iron oxide. After magnetization at 1 T, the magnetic gels with barium ferrite became elongated parallel to the magnetic field and shrunk perpendicular to the field. In contrast, the magnetic gels with iron oxide did not undergo a marked deformation. These results strongly indicate that the giant reduction in the storage modulus requires both enhanced nonlinear viscoelasticity and magnetostriction which originate from the particle dispersibility. The relationship between the dispersibility of magnetic particles and the giant reduction in the storage modulus is discussed using rheological and morphological data.     

QSNPlite, a software system for quantitative analysis of SNPs based on capillary array SSCP analysis

We present a newly developed software called "QSNPlite" that comprehensively interprets the data of SSCP and sequencing analyses obtained from capillary array electrophoresis systems used in the quantitative characterization of SNPs. QSNPlite assists in the genotyping of individuals with SNPs and in estimating the allele frequencies of SNPs using pooled DNA. We show that this estimation is accurate (mean absolute error, 1.4%) by comparing the results of the pooled analysis using QSNPlite with the true frequencies based on the allele counting after performing individual genotypings. The QSNPlite program runs on Windows XP and can be used to determine the allele frequencies of SNPs among a large number of individuals, such as in association studies of disease-responsible genes using the candidate gene approach.     

Production of ultrafine calcite particles by coccolithophorid algae grown in a biosolar reactor supplied with sunlight

Applied Biochemistry and Biotechnology - Ultrafine calcite particle production by coccolithophorid algae using a biosolar reactor system was carried out. Solar light was collected by Fresnel lenses...