Polymerizability,copolymerizability, and properties of cyanoacrylate‐telechelic polyisobutylenes I: three‐arm star cyanoacrylate‐telechelic polyisobutylene

This series of papers concern new materials for possible biological applications created by combining the chemistry of highly reactive cyanoacrylates (CAs) with polyisobutylene (PIB) rubbers. First, a new strategy for the synthesis of CA–telechelic PIBs is described. Subsequently, the strategy is employed for the synthesis of low viscosity (syringible) CA–telechelic three‐arm star PIB [Ø(PIB–CA)₃]. The intermediates of the synthesis route are characterized by ¹H NMR spectroscopy. Injecting liquid Ø(PIB–CA)₃ into living tissue (fresh chicken egg) produces a bolus of crosslinked PIB rubber. The spectacular oxidative resistance of this rubber is documented by its resistance to concentrated HNO₃. A structural model of the crosslinked rubber obtained upon contacting Ø(PIB–CA)₃ with proteinaceous tissue is proposed. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and characterization of novel poly(vinyl chloride)‐based grafts: Poly(vinyl chloride‐co‐2‐chloropropene) fitted with multiple high‐glass‐transition‐temperature polyolefin branches

The tertiary chlorine (Cl^t) content of vinyl chloride/2‐chloropropene copolymers [P(VC‐co‐2CP)] was determined by NMR spectroscopy. Copolymers containing 6.8–47.0 Cl^t's per P(VC‐co‐2CP) chain were used to initiate the cationic grafting of α‐methylstyrene, norbornadiene, indene, and norbornene with Et₂AlCl under various conditions. Grafting was demonstrated by selective solvent extraction, and the effect of the experimental conditions on the grafting efficiency was examined. Select rheological and thermal characteristics of P(VC‐co‐2CP) grafts, including the glass‐transition temperature, heat deflection temperature, and discoloration upon heating, were studied. P(VC‐co‐2CP) carrying 7–11 poly(α‐methylstyrene) or polynorbornadiene branches per chain raised the glass‐transition temperature to, or above, that of a blend control. P(VC‐co‐2CP)s fitted with polyindene or polynorbornene branches were less effective in raising the mechanical properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3644–3651, 2002     

SENSITIVITY OF Porphyromonas AND Prevotella SPECIES IN LIQUID MEDIA TO ARGON LASER

Abstract— The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all "black-pigmented bacteria," BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of Periodontol disease. Non-black-pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for Periodontol infections. Cell suspensions were irradiated with an argon laser at fluences of 20–200 J/cm². When cultured in hemin-supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non-black-pigmented bacteria were much less sensitive to irradiation than BPB.     

Inclusivef 2 (1270) meson production in νp and\bar vp charged current interactions

Using data obtained with the bubble chamber BEBC at CERN, the inclusivef ₂ (1270) meson production invp and \(\bar vp\) charged current reactions is studied. It is found thatf ₂ production occurs mainly in events with a hadronic invariant massW?7 GeV. In these events, the averagef ₂ multiplicity is about half the average ρ^O multiplicity, and thex _F andp _T ² distributions of thef ₂ agree in shape with those of the ρ^O. The predictions of a semi-empirical model (Wells model) are in accord with the measured multiplicities atW>7 GeV, whereas at lowerW the model predicts too largef ₂ multiplicities.