Dissipative crystallization of sodium salt of deoxyribonucleic acid

Drying patterns of aqueous solutions of sodium salt of deoxyribonucleic acid (NaDNA) were studied on a cover glass, a watch glass, and a Petri glass dish at room temperature. Orientation of the rod-like single crystals of NaDNA molecules in the radial direction was observed especially at low polymer concentrations. The ratios of the size of the broad ring against initial size of the liquid on a cover glass and a watch glass were very small between 0.05 and 0.1 compared with those of the typical polyelectrolytes. Main cause is the compact conformation of NaDNA forming single or double stranded helix structures in the dried film. Microscopic drying patterns were long rods accompanied with the many short rods especially on a cover glass. Thick and short rods and dendritic crystals were fogrmed at the inward and outward areas of the dried films, respectively, on a watch glass and a Petri glass dish. Rod-like and dendritic crystals resembled the distorted hedrite and/or spherulite structures. Dissipative crystallization such as the orientation and accumulation of the single crystals of NaDNA were observed and the importance of the convectional and sedimentation processes was demonstrated during the course of crystallization.     

Thermal cured epoxy resins using certain calixarenes and their esterified derivatives as curing agents

The acetyl esterified calixarene (CA) derivatives were prepared from calix[4]resorcinarene (CRA), and p‐tert‐butylcalixarene (BCA[n], n = 4, 6, 8), respectively. Using these CA derivatives as curing agents, the thermal curing reactions of two multifunctional epoxy resins (jER 828, 186 g/equiv., and ESCN, 193.7 g/equiv.) were investigated. The temperatures of glass transition (T_g) and decomposition (T) were measured by DSC and TGA, respectively. Based on the yields, T_gs, and T_ds of the thermal cured jER 828 epoxy resin with CRA‐E100, the curing conditions were optimized to be tetrabutylphosphonium bromide (TBPB) as catalyst in NMP at 160 °C for 15 h. Under this curing condition, the cured materials of jER 828 or ESCN using various CA derivatives as curing agents were prepared. Except for BCA4 derivatives, the yields of thermal curing reaction were higher than 90%. T_gs and Ts of the resultant cured materials were in the range of 113–248 °C and 363–404 °C, respectively. These results mean that the cured epoxy resins with excellent T_gs were successfully formed by using CA derivatives as curing agents. It was also found that the T_gs of cured epoxy resins were strongly affected by the degree of esterification of CA derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1931–1942, 2010     

Novel prenylated and geranylated aromatic compounds isolated from Polysphondylium cellular slime molds

We have studied the diversity of secondary metabolites of cellular slime molds to utilize them as new biological resources for natural product chemistry. From the methanol extract of fruiting bodies of Polysphondylium tenuissimum, we obtained five prenylated and geranylated aromatic compounds, Pt-1-5 (1-5). An additional aromatic compound, Ppc-1 (6), was isolated from Polysphondylium pseudo-candidum. The structures of these compounds were determined by spectral analysis, and synthetic routes to 4, 5, and 6 were developed. Compound 5 showed the glucose consumption-promotive activity on 3T3-L1 cells.     

Evaluation of chemiluminescence reagents for selective detection of reactive oxygen species

In order to evaluate the chemiluminescence (CL) reagents for selective detection of reactive oxygen species (ROS), we comprehensively measured the CL responses of 20 CL reagents (three luminol derivatives, two imidazopyrazinone derivatives, eight lophine derivatives, six acridinium ester derivatives and lucigenin) against six types of ROS (superoxide anion: O₂⁻, hydroxyl radical: OH, hydrogen peroxide: H₂O₂, hypochlorite anion: ClO⁻, singlet oxygen: ¹O₂, and nitric oxide: NO). As a result of the screening, it was found that nine CL reagents selectively detected O₂⁻ while one CL reagent selectively detected OH. However, no CL reagent had selectivity on the detection of H₂O₂, ClO⁻, ¹O₂ and NO. Our screening results could help to select the most suitable CL reagent for selective determination of different ROS.As an application study, 4-methoxyphenyl-10-methylacridinium-9-carboxylate (MMAC), one of the acridinium ester derivatives, showed high selectivity on the detection of O₂⁻, and thus was applied to the assay of superoxide dismutase (SOD) activity. The dynamic range and detection limit of the developed CL assay were 0.1-10 and 0.06 U mL⁻¹, respectively. Significant correlation (r = 0.997) was observed between the results by the CL assay using MMAC and the spectrophotometric assay using 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt.     

Characterization of Ultra‐Thin Temperature‐Responsive Polymer Layer and Its Polymer Thickness Dependency on Cell Attachment/Detachment Properties

Ultra thin poly(N‐isopropylacrylamide) (PIPAAm) modified glass coverslips (PIAPAm‐CS) using electron beam irradiation exhibited a clear relationship between the polymer thickness and thermal cell adhesion/detachment behavior. The polymer thickness dependency and the characteristic of ultra thin PIPAAm layer, has been illustrated in terms of the molecular motion of the modified PIPAAm chains. PIPAAm‐CSs surfaces with various area‐polymer densities and thicknesses were characterized by AFM and protein adsorption assay. The newly obtained results gave a further insight into the illustration. Finally, the future application of intelligent surfaces was discussed for fabricating tissue and organ.

     

Fabrication of marker area to align TEM tomographic tilt series of rod-shaped specimens

In this study, we present a new method for placing markers for alignment of tomographic tilt-series of rod-shaped specimen before 3D reconstructions. By this method, markers (gold nanoparticles) were placed only on the carbon layer (referred to as the "marker area") deposited for protecting the specimen surface against ion beam irradiation; this placement was achieved by vacuum evaporation of gold with the help of a mask fabricated adjacent to the specimen. Experimental results showed that the use of the proposed method facilitates the identification of the markers in the alignment process, because the image of the marker area consists of simple high-contrast images of the gold nanoparticles on the carbon layer. The performance of the proposed method was successfully verified experimentally by applying it to a high-density Au/SiO? nanocomposite material as a test specimen.     

Non-decoupling effects in supersymmetric Higgs sectors

A wide class of Higgs sectors is investigated in supersymmetric standard models. When the lightest Higgs boson (h  ) looks the standard model one, the mass (mh$m_h$) and the triple Higgs boson coupling (the hhh   coupling) are evaluated at the one-loop level in each model. While mh$m_h$ is at most 120–130 GeV in the minimal supersymmetric standard model (MSSM), that in models with an additional neutral singlet or triplet fields can be much larger. The hhh coupling can also be sensitive to the models: while in the MSSM the deviation from the standard model prediction is not significant, that can be 30–60% in some models such as the MSSM with the additional singlet or with extra doublets and charged singlets. These models are motivated by specific physics problems like the μ-problem, the neutrino mass, the scalar dark matter and so on. Therefore, when h   is found at the CERN Large Hadron Collider, we can classify supersymmetric models by measuring mh$m_h$ and the hhh coupling accurately at future collider experiments.     

Indirect bounds on heavy scalar masses of the two-Higgs-doublet model in light of recent Higgs boson searches

We study an upper bound on masses of additional scalar bosons from the electroweak precision data and theoretical constraints such as perturbative unitarity and vacuum stability in the two-Higgs-doublet model taking account of recent Higgs boson search results. If the mass of the Standard-Model-like Higgs boson is rather heavy and is outside the allowed region by the electroweak precision data, such a discrepancy should be compensated by contributions from the additional scalar bosons. We show the upper bound on masses of the additional scalar bosons to be about 2 (1) TeV for the mass of the Standard-Model-like Higgs boson to be 240 (500) GeV.