Cascade Reactions in Multicompartmentalized Polymersomes

Enzyme‐filled polystyrene‐b‐poly(3‐(isocyano‐L ‐alanyl‐aminoethyl)thiophene) (PS‐b‐PIAT) nanoreactors are encapsulated together with free enzymes and substrates in a larger polybutadiene‐b‐poly(ethylene oxide) (PB‐b‐PEO) polymersome, forming a multicompartmentalized structure, which shows structural resemblance to the cell and its organelles. An original cofactor‐dependent three‐enzyme cascade reaction is performed, using either compatible or incompatible enzymes, which takes place across multiple compartments.     

Barrier properties and microstructure modifications induced by liquid water for a semiaromatic polyamide

This work deals with the role of liquid water on the microstructure of a semiaromatic polyamide (MXD6). One side of injected plates is kept in contact with water during different durations. After immersion, microtomic cuts are performed at different depth and are analyzed by X‐ray diffraction, differential scanning calorimetry, and permeation tests. Measurements show that the water plasticizes the initially amorphous plates and induces a spherulitic crystallization, which grows from the wet side to the dry one. As a consequence, the permeation curve is unusual, and the water flux goes through a maximum before reaching a lower plateau when the front of crystallization reaches the opposite dry face. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2604–2616, 2005     

First application of mass spectrometry and gas chromatography in investigation of α-cellulose hydrolysates: the influence of climate changes on glucose molecules in pine tree-rings

We present the first results of the quantitative and qualitative gas chromatographic and isotope ratio mass spectrometric analysis of monosaccharides derived from acid hydrolysis of α-cellulose extracted from annual pine tree-rings. The conifers investigated in this study grew in the Niepolomice Forest in Poland, and the annual rings covered the time span from 1940 to 2000 AD. The main components of the α-cellulose samples were two saccharides: glucose and mannose. The amount of glucose in the annual rings varied between 17 and 44%. The δ(13)C of glucose was found to be less negative than that of α-cellulose and the δ(18)O values in glucose were less positive than those in α-cellulose. The content of monosaccharides in the α-cellulose samples has an influence on the isotope fractionation factors. The values of the carbon isotope fractionation factor increase with an increase in the monosaccharides concentration in α-cellulose, while the values of the oxygen isotope fractionation factor decrease with an increase in monosaccharides concentration in α-cellulose. The challenge is to establish, with respect to climate changes and environmental conditions, the significance of the interannual variations in the observed monosaccharide concentration.     

Ab initio study of cationic polymeric membranes in water and methanol

The work is devoted to a computational study of three types of cationic polymeric membranes in Li⁺-ionic form, in water and methanol environments, at various solvation levels. The studied membranes Nafion, IonClad, and M3 possess the perfluorinated backbone; however, various side chains were terminated with the functional groups of distinctly different ionic strength. The paper discusses the structural features of the membrane-solvent clusters as well as an influence of the side chain nature on the dissociation of the functional groups and the binding energy of the solvent molecules. Additionally, the paper compares the obtained results for Li⁺-Nafion membrane in water with the results published earlier for H⁺ and Na⁺ forms.     

A study of some parameters relevant to the response of harwell PMMA dosimeters to gamma and electron irradiation

The effects on the radiation response of Harwell polymethylmethacrylate (PMMA) dosimeters of dose-rate, radiation type, temperature during irradiation and post-irradiation storage, and post-irradiation stability, are of importance to the operators of commercial irradiation facilities.

This paper describes recent studies of the effects of some of these parameters on the radiation response of Harwell Red 4034, Amber 3042, and Gammachrome YR Perspex dosimeters, and provides data on batch to batch variation and shelf-life.     

Analysis of urinary biomarkers for exposure to alkyl benzenes by isotope dilution gas chromatography-mass spectrometry

A validated GC-MS method for the analysis of urinary metabolites of alkyl benzenes is reported. Metabolites for exposure to toluene, xylene and ethylbenzene were analyzed simultaneously using stable isotope substituted internal standards. The method entailed acidic deconjugation of urine samples followed by extractive alkylation with pentafluorobenzyl bromide as alkylating agent. The resulting pentafluorobenzyl derivatives of ortho-, meta-, para-cresol, mandelic acid (MA), hippuric acid (HA) and ortho-, meta-, para-methylhippuric acid (MHA) were then quantified by SIM. Optimized reaction conditions for the extractive alkylation step are reported. The derivatives were found to be sufficiently stable for overnight batch analysis. The LODs were below 0.1 micromol/L for the cresols and below 1 micromol/L for MA and the HAs. Within-batch precision for o-MHA was 7%, for m-MHA 5%, for p-MHA 5.2% and below 5% for the rest of the analytes.     

Polyepichlorhydrin membranes for alkaline fuel cells: sorption and conduction properties

Polymer electrolytes, using a poly(epichlorhydrin-allyl glycidyl ether) copolymer as matrix, are shown to perform well in alkaline fuel cell electrolyte. An anion-conducting network is obtained by the incorporation of cyclic diamines, 1,4-diazabicyclo[2.2.2]octane (DABCO) and 1-azabicyclo[2.2.2]octane (quinuclidine). The physicochemical and electrochemical characteristics are evaluated. The best conductivity of 1.3.10 (-2) S/cm is obtained at 60 degrees C and a relative humidity of RH = 98%. Ionic conductivity is particularly sensitive to relative humidity. To gain insight into the OH (-) conduction mechanism and the role of water, sorption measurements versus water activity, differential scanning calorimetry, and NMR measurements are carried out.     

Extensible Software Systems in Oberon

Abstract

Extensible software systems play an important role in prototyping environments where a fast compile-and-test turnaround is required. Typically, extensible software systems combine ways to reuse code, an approach to object-oriented programming, and ways to preserve state from one session to another. In this article we introduce the Oberon system from the perspective of an extensible system. In Oberon, the stated requirements manifest themselves as separate hierarchies related to modularity, the type system, runtime system organization, and persistency. We discuss issues related to these hierarchies and the approaches selected in Oberon for their implementation. The article is mainly a short introduction to Oberon and a summary of what has been accomplished with this system.     

On a Facile Synthesis of Melatonin and Other Related Indoles

An efficient laboratory synthesis for melatonin and other related indoles utilising enamides and enecarbamates is described.