Self-condensing vinyl polymerization: an approach to dendritic materials

Self-condensing vinyl polymerization was used to produce dendritic polymers with both highly branched structures and numerous reactive groups. A vinyl monomer will undergo self-polymerization if it contains a pendant group that can be transformed into an initiating moiety by the action of an external stimulus. The self-polymerization combines features of a classical vinyl polymerization process with those of a polycondensation because growth is accomplished by the coupling of reactive oligomers. Highly branched, irregular dendritic structures with a multiplicity of reactive functionalities are obtained by polymerization of 3-(1-chloroethyl)-ethenylbenzene.

High performance RO membranes for desalination and wastewater reclamation and their operation results

Reverse osmosis (RO) membrane is one of the most powerful tools for solving the global water crisis, and is used in a variety of water treatment scenes such as drinking water purification, waste-water treatment, boiler feed water production, ultra pure water production for semiconductor industry, etc. The desired performance of RO membrane varies according to quality of feed water being treated, and Toray has been developing RO membranes with suitable characteristic for each operating condition. RO membranes for seawater desalination and wastewater reclamation are especially regarded as most promising targets. Recently, high boron removal and energy saving RO membrane for seawater desalination and low fouling RO membrane for wastewater reclamation have been developed. In this paper, the prospect of attaining these renovative RO membrane, and furthermore, job references will be discussed.

Resonantly enhanced nonlinear conductance in long quantum point contacts near pinch-off

We report on a remarkable resonance in the differential conductance of long quantum point contacts (QPCs) that is observed as a precursor to regular quantized transport. This effect is increasingly pronounced in longer QPCs, in which the differential conductance may resonantly exceed 2e2/h. From a study of the experimental characteristics of this feature, we suggest that it may be associated with the formation of a well-resolved energy gap that opens dynamically as a result of enhanced many-body interactions in long QPCs.

[The role of anti L-asparaginase antibody in childhood acute lymphoblastic leukemia]

The function of IgG antibody with regard to L-asparaginase (L-asp) was investigated in vivo. Blood samples were collected before, during and after IV administration of L-asp (6,000 U/sqm for 10 days) in 18 children with acute lymphoblastic leukemia (ALL) previously treated with L-asp. Using enzyme-linked immunosorbent assay (ELISA), serum levels of L-asp and anti-L-asp IgG antibody were measured simultaneously. In 11 cases, the level of anti-L-asp IgG antibody increased prior to, but decreased to within the normal range after drug administration whereas the level of serum L-asp increased after drug administration. In 5 cases, the level of anti-L-asp IgG antibody increased as the level of serum L-asp decreased after drug administration. In contrast, in the 13 cases with no increase in anti-L-asp IgG antibody during L-asp administration, the serum L-asp level was stable. These data indicate that anti-L-asp IgG antibodies play an important role in the immunoclearance of L-asp. We would like to continue to carefully follow patients showing high titers of anti-L-asp IgG antibody during the administration of L-asp.

Locus of a histidine-based, stable trifunctional, helix to helix collagen cross-link: stereospecific collagen structure of type I skin fibrils

The loci of the three amino acid residues that contribute their prosthetic groups to form the stable, nonreducible, trifunctional intermolecular cross-link histidinohydroxylysinonorleucine in skin collagen fibrils were identified. Two apparently homogeneous three-chained histidinohydroxylysinonorleucine cross-linked peptides were chromatographically isolated. They were obtained from a tryptic digest of denatured unreduced 6 M guanidine hydrochloride insoluble bovine skin collagen. Amino acid and sequence analyses demonstrated that the prosthetic groups of alpha 1(I)-chain Hyl-87, alpha 1(I)-chain Lys-16c, and alpha 2(I)-chain His-92 formed the cross-link. The latter results served to define the locus of the stable, nonreducible trifunctional moiety. Identical types of analyses were performed on the three-chained peptides isolated after bacterial collagenase digestion of the cross-linked tryptic peptides. This confirmed the initial identification and location of the three peptides linked by the cross-link. In addition, data reported here provide for a correction of the micromolecular structure for the alpha 2(I) chain. Stereochemical considerations concerning this trifunctional cross-link's specific locus indicate that the steric relationships between the alpha chains of skin and skeletal tissue collagens are fundamentally different and the intermolecular relationships in skin fibrils are specific for skin. The same molecular relationships also indicate that histidinohydroxylysinonorleucine links three molecules of collagen. The stereochemistry of cross-linking for skin collagen is in accordance with and explains the X-ray findings of a 65-nm periodicity found for this tissue [Stinson, R. H., & Sweeny, P. R. (1980) Biochim. Biophys. Acta 621, 158; Brodsky, B., Eikenberry, E. F., & Cassidy, K. (1980) Biochim. Biophys. Acta 621, 162].

Structural crosslinking of lung connective tissue collagen in the blotchy mouse

Male mice with the sex-linked mutation Blotchy (Blo) have a defect in copper metabolism which results in deficient activity of a number of copper-containing enzymes. Inbred Blo/y mice spontaneously develop lung abnormalities which resemble emphysema and often die of ruptured aortic aneurysm. Lung, tail tendon, and tibial bone collagens from inbred Blo/y and their normal (+/y) litter mates were reduced with standardized [3H]NaBH4, acid and alkaline hydrolyzed, and chromatographed in order to quantify the aldehydic crosslink precursors, and the labile reducible and nonreducible stable mature covalent intermolecular crosslinks. Reducible lung collagen crosslinks were markedly (60%) decreased in the Blo/y mice and few, if any, mature nonreducible crosslinks were present. Total aldehydes were also decreased (65%) when Blo/y was compared to +/y. In tail tendon and bone, collagen crosslinks were decreased by only 28% and 15%, respectively. Selectively severe lack of activity of the copper-dependent enzyme level oxidase in lung with only partial lack in tendon and bone could account for the results obtained. Alternatively, insufficient reducible crosslinks, coupled with increased collagen turnover in the lung could prevent formation of the more mature stable crosslinks required to provide a proper connective tissue framework for the Blo/y lung.