The effect of organic nitriles on the radiation induced polymerization of styrene

The effect of a range of 10 organic nitriles on the radiation-induced polymerization of styrene was studied. A dose rate of 4.4 rad s^?1 was used. A rate of polymerization of styrene (1.744 mol L^?1 of toluene solution) of 5.0 × 10^?7 mol L^?1 s^?1 was found. With organic nitriles present (styrene:nitrile ratio of 1:0.28) the rate of polymerization increased. Rates in the range of 5.5 × 10^?7 ?5.2 × 10^?6 mol L^?1 s^?1, depending on the nitrile present, were obtained. The polymers were partially characterized and evidence of involvement of each of the nitriles in the polymer chains was revealed. The increase in rate of polymerization has been attributed to the part played by nitrile radicals in the initiation of styrene polymerization. Radical yield values [as G(nitrile radical)] were derived from the relevant rate expressions. Values ranged from 2.7 to 49.5, depending on the particular nitrile. Corresponding values of G(nitrile radical) in the range of 5.1–129.4 were obtained by the manipulation of number-average molar mass data. Values of k_pk_t of approximately 2 × 10^?5 L mol^?1 s^?1 were found. Trommsdorff types of effect are absent from these systems.     

An experiment to test an explanation of a possible violation of quantum theory

An experiment to test a possible explanation of the Schmidt backwards causation results is suggested. The experiment might distinguish between many- and one- world interpretations of quantum theory.     

Internal molecular disorder in the nematic and smectic phases of thermotropic liquid crystals studied by NMR SPDE experiments

The recently developed NMR SPDE experiment is shown to provide a new and particularly convenient technique for probing the conformational dynamics of mesogens in thermotropic liquid crystals. Measurements have been made in the nematic and smectic phases of the 4,4′-di-n-alkoxyazoxybenzenes. It is shown for the first time that the internal disorder of the alkyl end chains is intimately related to the molecular organization of these mesophases.     

Contributions to the Mechanism of Isobutene Polymerization. VII. Effect of HCI and Chloroethyl Benzene and a Brief Summary of the Data

Der Einfluss von HCI und Chloräthylbenzol auf die Ausbeute und das Molekulargewicht von Polyisobutylen wurde untersucht. Es konnten keine sinnvollen Vergiftungs-und Übetrträgerkoeffizienten abgeleitet werden da HC1 als ausbeuteverbessernder Promotor wirkte und der Einfluss des Chloräthylbenzols sich als sehr komplex erwies. Die Molekulargewichte der Polyisobutylene waren geringer, je grösser die Menge der vorhandenen Halogenverbindungen war. Es wird postuliert, dass HC1 als Promotor und Überträger wirkt.

Die in dieser Untersuchungsreihe erhaltenen Ergebnisse wurden durch Auftragung des Vergiftungskoeffizienten jeder Verbindung gegen den ëbertragungskoeffizienten dargestellt. Die meisten der untersuchten Ver-bindungen sind sowohl Gifte als auch ëbertràger, nur wenige sind reine (oder fast reine) Gifte oder Ubertràger. Es wird betont, dass diese Eigen-schaften rein empirisch sind und dass diese Ergebnisse nur mit grösster Vorsicht verallgemeinert werden dürdrfen.     

Contributions to the Mechanism of Isobutene Polymerization. VI. Effect of Halides

The effects of various allyl chlorides and alkyl halides on the overall yield of polymerization and molecular weight of polyisobutene have been investigated and expressed quantitatively by poison and transfer coefficients. The poison and transfer coefficients of halides have been compared with those obtained previously for corresponding hydorcarbons. The poison coefficients of halides and hydrocarbons can be treated formally in a similar manner (1/W_p vs. [X] plots linear for both classes); however, the appropriate transfer coefficients indicate fundamentally dissimilar transfer mechanisms in these systems (1/MW_p vs. [X] plots linear for hydrocarbons, whereas 1/MW_p vs. [X]^1/2 plots linear for halides). These results are discussed in terms of the allylic termination mechanism.     

Processes associated with ionic current rectification at a 2D-titanate nanosheet deposit on a microhole poly(ethylene terephthalate) substrate

Films of titanate nanosheets (approx. 1.8-nm layer thickness and 200-nm size) having a lamellar structure can form electrolyte-filled semi-permeable channels containing tetrabutylammonium cations. By evaporation of a colloidal solution, persistent deposits are readily formed with approx. 10-μm thickness on a 6-μm-thick poly(ethylene-terephthalate) (PET) substrate with a 20-μm diameter microhole. When immersed in aqueous solution, the titanate nanosheets exhibit a p.z.c. of − 37 mV, consistent with the formation of a cation conducting (semi-permeable) deposit. With a sufficiently low ionic strength in the aqueous electrolyte, ionic current rectification is observed (cationic diode behaviour). Currents can be dissected into (i) electrolyte cation transport, (ii) electrolyte anion transport and (iii) water heterolysis causing additional proton transport. For all types of electrolyte cations, a water heterolysis mechanism is observed. For Ca²⁺ and Mg²⁺ions, water heterolysis causes ion current blocking, presumably due to localised hydroxide-induced precipitation processes. Aqueous NBu₄⁺ is shown to ‘invert’ the diode effect (from cationic to anionic diode). Potential for applications in desalination and/or ion sensing are discussed.

     

A thermobalance for high pressure process studies

A DuPont 950 TG has been modified to permit operation at up to 30 atm, 1100°C, with corrosive atmospheres, and steam partial pressures up to 20 atm.The major areas of instrument development included: weight and temperature measurement at high pressures in a dynamic flow system; modification of a TG to accept corrosive gas atmospheres containing high partial pressures of steam; design of a pressure balanced flow system for safe introduction of corrosive gas atmospheres; design of a working steam generation system for low flows.Process studies illustrating the utility of the high presure thermobalance include the cyclic CO₂-acceptor reaction for half-calcined dolomite

and the cyclic H₂S absorption and regeneration reaction for half-calcined dolomite

     

Optimizing the vertebrate vestibular semicircular canal: could we balance any better?

The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has "optimally designed." Four geometric parameters characterize the SCC, and "building materials" of given physical properties are assumed. Identifying physical and physiological constraints on SCC operation, we find the most sensitive SCC has dimensions consistent with available data. Since natural selection involves optimization, this approach may find broader use in understanding biological structures.