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Spontaneous Oxidation and in‐situ Polymerization of Pyrrole in Channels of the Three‐Dimensional Coordination Polymer [(Me3Sn)3FeIII(CN)6]∞

Precursors to highly conducting polypyrrole (Ppy) are formed in the lipophilic channels of 1 subsequent to a spontaneous, strictly stoichiometric [N(Ppy)/Fe = 1/1] redox reaction. In view of the diameter of the channel (6.8 Å) the entrapped Ppy should be free of cross-linking (thus approximating a “molecular wire”).

The Concept of Filament Strength and the Weibull Modulus

Abstract The strength of high-performance filaments is a complex parameter which can not be fully described with a single value. The Weibull model is used to describe the intrinsic statistical nature of the fracture strength. Possibilities and limitations of the Weibull model are illustrated. The relationship between…

Quantitative infrared methods for the measurement of crystallinity and its temperature dependence: polyethylene

Vibrational spectroscopic methods are widely used to characterize semicrystalline polymers in terms of crystallinity. The temperature coefficient of crystallinity, an important and fundamental quantity, is seldom determined for lack of a sensitive method. In this paper, we describe an infrared approach to the measurem…

Crystal Structure of Orthorhombic Zirconia in Partially Stabilized Zirconia

A neutron powder diffraction investigation confirms that, in tough magnesiapartially‐stabilized zirconia cooled to 30 K, most of the tetragonal zirconia transforms to an orthorhombic phase. This phase is retained on heating to room temperature; the lattice parameters at 295 K are a = 0.5068, b = 0.5260, and c = 0.5077…

Potassium monopersulfate and a water-soluble manganese porphyrin complex, [Mn(TMPyP)](OAc)5, as an efficient reagent for the oxidative cleavage of DNA

Reported studies indicate that the association of potassium monopersulfate with [Mn(TMPyP)](OAc)5, a water-soluble manganese porphyrin complex, leads to an efficient reagent for the oxidative cleavage of DNA. Single-strand breaks (SSBs) are observed on double-stranded DNA at manganese porphyrin concentrations as low a…

The crevice model of bubble nucleation

The crevice model for heterogeneous nucleation of bubbles in water in response to a decreasing liquid pressure is studied. The model neglects gas-diffusion effects and is therefore more suited for acoustic than for flow cavitation. It is argued that previous work has overlooked the essential requirement of unstable gr…

Poly-β-hydroxybutyrate biosynthesis in Alcaligenes eutrophus H16

The poly-beta-hydroxybutyrate biosynthetic thiolase gene from Zoogloea ramigera was used as a hybridization probe to screen restriction digests of Alcaligenes eutrophus H16 DNA. Specific hybridization signals were obtained and two fragments (a 2.3-kilobase PstI fragment and a 15-kilobase EcoRI fragment) cloned in the…

The Role of Mg17Al12 Phase in the Corrosion of Mg Alloy AZ91

Corrosion behavior of mold-cast Mg alloy AZ91 is investigated in as-cast (F), homogenized (T4), and artificially-aged (T6) conditions in chloride media. Heat treatment influences mainly the distribution of intermetallic β-phase (Mg17Al12) in the alloy. Aging to T6 temper causes precipitation of the phase as a nearly c…

Stabilization of a liquid-crystalline phase through noncovalent interaction with a polymer side chain

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStabilization of a liquid-crystalline phase through noncovalent interaction with a polymer side chainTakashi Kato and Jean M. J. FrechetCite this: Macromolecules 1989, 22, 9, 3818–3819Publication Date (Print):September 1, 1989Publication History Published online1 May 2002Pub…

In‐situ photopolymerization of oriented liquid‐crystalline acrylates, 3. Oriented polymer networks from a mesogenic diacrylate

Abstract Synthesis, mesomorphism, orientation and photo‐initiated chain crosslinking of the liquid‐crystalline diacrylate 1,4‐phenylene bis{4‐[6‐(acryloyloxy)hexyloxy]benzoate} ( 1 ) are studied. Monomer 1 exhibits a broad nematic phase between 108 and 155°C and a monotropic smectic phase below 88°C. The monomer is un…

Poly-β-hydroxybutyrate (PHB) biosynthesis in Alcaligenes eutrophus H16

The phbC gene encoding the third enzyme of the poly-beta-hydroxybutyrate biosynthetic pathway, poly-beta-hydroxybutyrate polymerase, in Alcaligenes eutrophus H16 has been identified by the complementation of poly-beta-hydroxybutyrate negative mutants of A. eutrophus H16. These results demonstrate that the three enzyme…

Optical and acoustic investigations of the dynamics of laser-produced cavitation bubbles near a solid boundary

The dynamics of laser-produced cavitation bubbles near a solid boundary and its dependence on the distance between bubble and wall are investigated experimentally. It is shown by means of high-speed photography with up to 1 million frames/s that jet and counterjet formation and the development of a ring vortex resulti…

Evolution of the vacuolar H+-ATPase: implications for the origin of eukaryotes.

Active transport across the vacuolar components of the eukaryotic endomembrane system is energized by a specific vacuolar H+-ATPase. The amino acid sequences of the 70- and 60-kDa subunits of the vacuolar H+-ATPase are approximately equal to 25% identical to the beta and alpha subunits, respectively, of the eubacteria…

Magnetocaloric effects in rare-earth magnetic materials

A review is given of the experimental investigations of the magnetocaloric effect (MCE) in rare-earth magnetic materials of different classes: heavy rare-earth metals and their alloys, iron garnets, and intermetallic compounds. The results of measurements of the MCE near phase transitions are given for the vicinity of…

Nitrite reductase from Pseudomonas aeruginosa: Sequence of the gene and the protein

The gene coding for nitrite reductase of Pseudomonas aeruginosa has been cloned and its sequence determined. The coding region is 1707 bp long and contains information for a polypeptide chain of 568 amino acids. The sequence of the mature protein has been confirmed independently by extensive amino acid sequencing. The…

Binding of dimethyl sulfoxide to lysozyme in crystals, studied with neutron diffraction

Crystals of hen egg white lysozyme soaked in 15% (v/v) dimethyl sulfoxide have been studied with single-crystal neutron diffraction to determine the effect of the solvent molecules on the protein configuration. A total of 9423 statistically significant Bragg reflections to a resolution of approximately 1.8 A were used…

Diffusion-controlled wetting films

The dynamics of ultra-thin wetting films has been studied experimentally under a controlled atmosphere using a dynamic ellipsometric technique. The spreading fluid was PDMS and the substrates were oxide covered silicon wafers. The situations of capillary rise up a vertical wall, and the spreading of 'nanoscopic' drops…

Thermal conductivity of the charge-density-wave systemsK0.3MoO3and (TaSe4)2I near the Peierls transition

We report on measurements of the thermal conductivity ${\mathrm{\ensuremath{\kappa}}}_{\mathrm{T}}$ close to the Peierls transition temperature ${\mathrm{T}}_{\mathrm{P}}$ in ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$ and (${\mathrm{TaSe}}_{4}$${)}_{2}$I. In both cases there is an enhancement of ${\mathrm{\ensuremath{\k…

Double fluorescence lifetimes of metal-free phthalocyanine in a mixed-solvent Shpol'skii matrix at 4·2 K

We report identical double fluorescence lifetimes of τ = 3·7 and 6·3 ns for the 0-0 fluorescences of each of the two tautomeric species of metal-free phthalocyanine (H2Pc) in a mixed solvent matrix of α-chloronaphthalene and n-octane at 4·2K. Such double lifetime feature has not been reported previously for this molec…