Biomedical subjects
Publications and source records attributed to P Brant.
In the title compound, [(CH(3))(2)(C(7)H(7))NH][(C(6)F(5))(3)B(OH)] or C(9)H(14)N(+).C(18)HBF(15)O(-), the distorted tetrahedral borate anions are strongly hydrogen bonded to the substituted ammonium cations. The N.O separation in the N-H.O hydrogen bond is 2.728 (3) A.
Spectacular advances in organometallic chemistry over the past two decades have resulted in single-site catalysts that are revolutionizing production of polyethylene (PE) and isotactic polypropylene (iPP). This report describes an unanticipated benefit of metallocene-catalyzed semicrystalline polyolefins, namely welded joint strengths in PE/iPP laminates that can exceed the cohesive strength of the constituents. We propose that interfacial polymer entanglements, established in the molten state and subsequently anchored in chain-folded lamellae upon crystallization, are responsible for this intrinsic property. The poor adhesion exhibited by traditional Ziegler-Natta-catalyzed polyolefins is shown to derive from the accumulation of amorphous polymer, a by-product of the polymerization reactions, at the interface. These results should facilitate fabrication and improve the properties of composites based on materials that dominate the plastics industry.
Chromosome 21 is the smallest human autosome. An extra copy of chromosome 21 causes Down syndrome, the most frequent genetic cause of significant mental retardation, which affects up to 1 in 700 live births. Several anonymous loci for monogenic disorders and predispositions for common complex disorders have also been mapped to this chromosome, and loss of heterozygosity has been observed in regions associated with solid tumours. Here we report the sequence and gene catalogue of the long arm of chromosome 21. We have sequenced 33,546,361 base pairs (bp) of DNA with very high accuracy, the largest contig being 25,491,867 bp. Only three small clone gaps and seven sequencing gaps remain, comprising about 100 kilobases. Thus, we achieved 99.7% coverage of 21q. We also sequenced 281,116 bp from the short arm. The structural features identified include duplications that are probably involved in chromosomal abnormalities and repeat structures in the telomeric and pericentromeric regions. Analysis of the chromosome revealed 127 known genes, 98 predicted genes and 59 pseudogenes.
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