Preparation and characterization of end-alkoxysilylated polystyrene and the grafting behaviors onto inorganic pigments. II. Utilization of 4-triethoxysilyl-α-methylstyrene

Novel polystyrene was prepared with triethoxysilyl (TES) groups at the end of the chain, and the grafting behaviors of the resulting polymer onto silica, alumina, and titania were studied. TES groups were introduced by the reaction between living polystyryl anion and 4-triethoxysilyl-α-methylstyrene (1) in THF at 195 K. The end-functional polymer was characterized by GPC, ¹H-NMR, and TLC. It was confirmed that the polymer had several units of 1 at the chain end and a fairly narrow molecular weight distribution. TES groups in the present polymer were found to be hydrolyzed with both acids and bases such as mono-n-butylphosphate (MBP) and tetrabutylammonium hydroxide (TBAH), respectively. The polymer was effectively grafted onto silica and alumina in toluene in the presence of MBP and TBAH, respectively. The amount of graft, estimated by thermogravimetry, changed with the selection of substrates and catalysts; about 2 mg/m² at the highest. The change in the amount of graft can be explained by the amount of effective acidic- or basic-hydroxyl groups on the substrate surfaces. However, titania received the largest amount of graft in the absence of catalyst. This may be because the strong acidic sites on the surface of titania act as a hydrolytic catalyst. The present polymer is expected to find wide application as a macromolecular dispersant for various types of inorganic pigments. © 1996 John Wiley & Sons, Inc.     

Thermal and dynamic mechanical properties of organic–inorganic hybrid composites of itaconate‐containing poly(butylene succinate) and methacrylate‐substituted polysilsesquioxane

Itaconate‐unit‐containing poly(butylene succinate) (PBSI) was synthesized by the reaction of 1,4‐butanediol, succinic acid, and itaconic acid in a molar ratio of 2.0 : 1.0 : 1.0, and the obtained PBSI was reacted with methacryl‐group‐substituted polysilsesquioxane (ME‐PSQ) in the presence of benzoyl peroxide (BPO) at 130°C to produce PBSI/ME‐PSQ hybrid composites. The thermal and dynamic mechanical properties of the PBSI/ME‐PSQ hybrid composites were investigated in comparison with those of PBSI cured at 130°C in the presence of BPO. As a result, the hybrid composites showed a much higher thermal degradation temperature and storage modulus in the rubbery state than the cured PBSI (C‐PBSI). The thermal degradation temperature and storage modulus of the hybrid composites increased with increasing ME‐PSQ content. The glass‐transition temperature, measured by dynamic mechanical analysis of the hybrid composites, somewhat increased with increasing ME‐PSQ content. However, the glass‐transition temperatures of all the hybrid composites were lower than that of C‐PBSI. Although the IR absorption peak related to C?C groups was not detected for C‐PBSI, some olefinic absorption peaks remained for all the hybrid composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

New concept bioceramics composed of octacalcium phosphate (OCP) and dicarboxylic acid-intercalated OCP via hydrothermal hot-pressing

Octacalcium phosphate (OCP) and adipic acid-intercalated complexed OCP (Adi-OCP) were synthesized. Moreover, we made ceramic bodies out of them through a hydrothermal hot-pressing (HHP) method. Characteristic features of both the powder and ceramics were investigated by the X-ray diffraction method (XRD). Surface morphology of the ceramics was observed by scanning electron microscopy (SEM). Density, compressive strength and pore size distribution of the ceramics were measured. Crystalline structure of the newly developed OCP ceramics had no phase transformation from the starting materials. Moreover, the newly developed OCP ceramics had good mechanical properties only through the HHP treatment with a temperature as low as 110 °C. In order to evaluate bioactivity, the ceramics were immersed in simulating body fluid (SBF). It was predicted that OCP and Adi-OCP had better bioactivity than that of conventional HAp ceramics.     

Reaction–diffusion algorithm for stereo disparity detection

The present paper proposes a novel stereo algorithm utilizing multi-sets of reaction–diffusion equations. The problem of detecting a stereo disparity map becomes the segmentation problem, in which the uniqueness assumption and the continuity assumption on disparity distribution are taken into account. A set of reaction–diffusion equations realizes the continuity assumption, while a mutual-inhibition mechanism among the multi-sets realizes the uniqueness one. In addition, each set of equations has a self-inhibition mechanism, which is necessary for the reaction-diffusion equations applied to stereo disparity detection. Performance of the proposed algorithm is evaluated for well-known test stereo images.     

A comparative study on determination method of heat transfer coefficient using inverse heat transfer and iterative modification

The distortion control of heat-treated steel parts is a main consideration when dealing with hardening by quenching process. Before implementing this heat treating process, prediction of distortion is necessary to be done by experiment and computer simulation for determining a quenching technique which gives the smaller distortion. Temperature-dependent heat transfer coefficient (HTC) estimated from SUS304 cylinder can be determined by both iterative modification of lumped heat capacity method (LumpHC) and inverse heat transfer method (InvHT). Predicted HTC from silver probe is needed for the LumpHC, whereas initial set of assumption is needed for the InvHT. The zone-based HTC estimated from SUS304 cylinder then is employed on S45C cylinder. The prediction accuracy results from both methods are evaluated. As expected, stir quenching gives less distortion than that of still quenching. More accurate prediction of cooling curves, cooling rate curves, and distortion is achieved by employing the LumpHC than that by the InvHT. All analyses were performed by DEFORM-HT 2D.     

Dispersion polymerization of vinyl acetate in a mixture of ethanol and water

Dispersion polymerization of vinyl acetate (VAc) was studied in a mixed solvent of ethanol and water using poly(vinyl alcohol) (PVA) with a low degree of hydrolysis as a steric stabilizer. Six compositions were chosen from a homogeneous phase before the polymerization. In a composition with the highest solubility parameter, 450 nm particles with a size distribution close to monodispersity were obtained. With decreasing solubility parameters of the compositions, the particles became polydisperse. In the compositions with solubility parameter lower than 17.1, particles were not formed even at 100 % conversion. Degrees of polymerization obtained in this homogeneous phase were less than 100 and close to calculated values. With increasing solubility parameters of the system, degrees of polymerization increased but were still less than 200. Grafting of VAc onto PVA and grafted PVA were very small, indicating the presence of a competing reaction to the grafting. Copyright © 2004 Society of Chemical Industry     

A novel mutation causing an aberrant splicing in the protein 4.2 gene associated with hereditary spherocytosis (protein 4.2Notame)

We investigated a Japanese patient with protein 4.2 deficiency. SDS-PAGE showed a complete deficiency of protein 4.2, while Western blot analysis revealed a marked decrease in the amount of protein 4.2, and the existence of a doublet of 74 and 72 kDa bands. Direct sequencing and dot-blot hybridization with allele-specific oligonucleotide probes indicated that the proband was compound heterozygous for a missense mutation in codon 142 with Ala-->Thr (GCT-->ACT) and a single nucleotide substitution (G-->A) of the first base of intron 6 (G-->A) of the protein 4.2 gene. The former is the commonest mutation observed in cases of protein 4.2 deficiency, whereas the latter is a novel mutation, located within the consensus sequence of the 5' splicing site (AGGU) (Protein 4.2Notame). RT-PCR analysis using total RNA isolated from reticulocytes of the proband revealed that the intron 6 donor site mutation causes an abnormal splicing; exon 6 is spliced out with intron 6. The abnormal mRNA has a premature termination codon, as the result of a frameshift, and this instability may lead to degradation. Thus, there is a close relation between this mutation and the molecular pathogenesis of protein 4.2 deficiency.     

Construction of a dictionary of sequence motifs that characterize groups of related proteins

An automatic procedure is proposed to identify, from the proteinsequence database, conserved amino acid patterns (or sequencemotifs) that are exclusive to a group of functionally relatedproteins. This procedure is applied to the PIR database anda dictionary of sequence motifs that relate to specific superfamiliesconstructed. The motifs have a practical relevance in identifyingthe membership of specific superfamilies without the need toperform sequence database searches in 20% of newly determinedsequences. The sequence motifs identified represent functionallyimportant sites on protein molecules. When multiple blocks existin a single motif they are often close together in the 3-D structure.Furthermore, occasionally these motif blocks were found to besplit by introns when the correlation with exon structures wasexamined.     

Inhibitory effects of methanolic extract from corydalis tuber against types I-IV allergic models

Methanolic extract (CM-ext) from tubers of Corydalis turtschaninovii forma yanhusuo has been screened for activity in experimental models of types I-IV allergy. In type I allergic models, CM-ext at doses of 200, 500 mg/kg, p.o. inhibited 48-h homologous passive cutaneous anaphylaxis (PCA) in rats which is related to IgE, and 4-h heterologous PCA in guinea pigs which is related to IgG. The inhibition of CM-ext on 48-h PCA was also recognized in adrenalectomized rats. CM-ext exhibited the inhibitory effect on formation of IgE antibody in BALB/c mice. In type II allergic model, it was found that CM-ext inhibits reversed cutaneous anaphylaxis (RCA). In type III allergic model, CM-ext showed the inhibitory effect on direct passive arthus reaction (DPAR) in rats. Furthermore, in type IV allergic model, CM-ext had the inhibitory effects on induction phase and effector phase in picryl chloride-induced contact dermatitis (PC-CD). It also showed therapeutic action on PC-CD. These results indicated that CM-ext not only inhibits antibody-mediated allergic reactions but also influences cell-mediated allergic reactions and should be recognized as a potent material for allergic reactions, although the mechanisms and active principles of CM-ext have not yet been completely determined.