Preparation and properties of disyndiotactic poly(alkyl crotonate)s

Ethyl, n-propyl, iso-propyl and n-butyl crotonates were polymerized by group transfer polymerization (GTP) using ketene trialkylsilyl acetals as initiators in the presence of mercury (II) iodide as catalyst and iodotriethylsilane as co-catalyst. Predominantly disyndiotactic polymers with number-average molecular weights ranging from 56,000 to 90,000 were obtained almost quantitatively. Thermal and mechanical properties of poly(alkyl crotonate)s, such as glass transition temperature (T_g), refractive index, transmissivity, Izod impact strength, Young's modulus, hardness, tensile strength, tensile elongation at break, gas permeability coefficient and density were measured. All the polycrotonates have 65–90 °C higher T_g than the corresponding polymethacrylates.     

Open systems interconnection — the teletex-based session protocol: Part 1

Two draft proposals for an international standard for the teletex-based session protocol have now been considered by the ISO. The ECMA 75 protocol has been found to be relatively complex as a result of ECMA having to sort out some weak points within the protocol. S.62, proposed by the CCITT, is quite suitable for the kernel of the session service, but not for the entire service. The paper suggests possible developments towards an international standard, and discusses the specification of the BAS subset. It then examines the services available, and how they operate. A proposal for a standard for service conventions is presented, along with a summary of the parameters of the service elements.     

Peroxid-induzierte thioladdition an polybutadien

The free-radical addition of 1-octanediol or 3-(trimethoxysilyl)-1-propanethiol on polybutadiene occurs redox-induced with dibenzoylperoxid (DBPO) at room temperature, without any side-reaction. 1,4-trans double bonds do not undergo thiol reactions, similar to the photochemical addition. The molecular weight distribution of the products is comparable with that of the initial polybutadiene.     

The Influence of Inverter Feeding on the Apparent Stray Inductance of Asynchronous Machines

The stray inductance is an important parameter for the design of inverters feeding asynchronous machines. Measurements are proposed which are relevant for determining the apparent stray inductance of an inverter-fed asynchronous machine. These measurements show that the apparent stray inductance is considerably smaller than the one obtained with classical sinusoidal methods. This amounts to smaller commutating capacitors in current source inverter (CSI) motor drives. A theoretical explanation for this phenomenon is presented and confirmed by calculation.     

Involvement of the olfactory bulb in consolidation processes associated with long-term memory in rats.

In a daily training paradigm, rats were trained to discriminate between spatially distinct electrical stimulations delivered to one olfactory bulb. Xylocaine injections were used to disrupt the olfactory bulb functioning in the region close to the electrode tips for 1 hr after each training session. The treatment started either just after the session or 2 hrs later. When compared with the performance of saline-injected rats, the performance of Xylocaine-injected rats was unimpaired except when the treatment started just after the daily session. In that case, acquisition of the task was slightly altered, and retention over a 5-day period was dramatically impaired. It is concluded that, within 1 hr following training, the olfactory bulb is engaged in consolidation processes critical for long-term retention of learned olfactory cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Open systems interconnection — the teletex-based session protocol: Part 2

The development of an international standard for the teletex-based session protocol has involved combining the best points of two draft proposals, ECMA 75 and S.62. Recently, the ISO has completed a specification comprising three subsets: the ISO/ECMA subset, the ISO/CCITT subset and the null functionality subset. The paper discusses the development of the standard, lays out the specification and describes the operation of each of the protocol phases. Three appendices describe the conformance problem and the BAS subset, protocol machines and the interworking problem.     

Synthesis of Microporous Carbon Nanofibers and Nanotubes from Conjugated Polymer Network and Evaluation in Electrochemical Capacitor

One‐dimensional fibers and tubes are constructed through the oriented carbon‐carbon cross‐linking reactions towards rigid conjugated polymer networks. As the result, a template‐free and one‐step synthesis of CNTs and CNFs is achieved through a simple carbonization of the as‐formed carbon‐rich tubular and fiberlike polyphenylene precursors under argon. Microporous CNTs and CNFs with a surface area up to 900 m² g^–1 are obtained, together with HR‐TEM characterizations indicating the formation of intrinsic microporous structure in these rigid carbon‐rich networks. The primary electrochemical experiments reveal their promising applications as advanced electrodes in electrochemical double‐layered capacitor (EDLC).