Search results for "ether"

Relevance of creep and oscillatory tests for understanding how cellulose emulsions function as fat replacers in biscuits

2015

Abstract The fats that are mostly employed in biscuit manufacturing contain a high percentage of saturated fatty acids, giving them the solid consistency that is needed for biscuit manufacture. For health reasons, lower levels of saturated fatty acids and elimination of trans fatty acids are desirable. An emulsion of sunflower oil, water and a cellulose ether was employed to replace all the conventional fat in a short dough recipe. The structure of the different doughs was measured by oscillatory and creep rheological tests and the results were related to dough performance during baking. The effect of the methoxyl and hydroxypropyl content of the cellulose was also evaluated. The compliance…

Enantiomeric separation of chiral phenoxy acid herbicides by electrokinetic chromatography. Application to the determination of analyte-selector appa…

2001

The enantiomeric resolution of chiral phenoxy acid herbicides was performed by electrokinetic chromatography using a cyclodextrin as chiral pseudophase (CD-EKC). A systematic evaluation of several neutral and charged cyclodextrins was made. Among the cyclodextrins tested, (2-hydroxy)propyl beta-cyclodextrin (HP-beta-CD) was found to be the most appropriate for the enantioseparation of phenoxy acids. The influence of some experimental conditions, such as nature and pH of the background electrolyte, chiral selector concentration, and temperature, on the enantiomeric separation of phenoxy acids was also studied. The use of a 50 mM electrolyte solution in ammonium formate at pH 5 and a temperat…

Structure Effect of Imidazolium-Based Dicationic Ionic Liquids on Claisen Rearrangement

2014

A large group of imidazolium-based dicationic ionic liquids (DILs) has been prepared in good yields. Thermal stability of all DILs has been determined. The effects of the reaction time, cation, imidazolium C2–H acidity, and anion on the Claisen rearrangement of allyl phenyl ether have been investigated. Type of anion and the presence of the acidic C2–H bond in the imidazolium moieties have proven to be essential for this reaction. The simple procedure and the possibility of avoiding the use catalysts and volatile organic solvents make this synthetic method environmentally benign and adaptable for large-scale applications.

Phase diagrams of the system tetrahydrofuran/γ-butyrolactone/poly(ether imide) and determination of interaction parameters

1998

Abstract The thermodynamic interactions in the ternary mixture tetrahydrofuran/γ-butyrolactone/poly(ether imide) (THF/γ-BL/PEI) are investigated from 30 to 50°C. This is a membrane-forming system with a high He-selectivity. Cloud point measurements show that the two binary polymer solutions THF/PEI and γ-BL/PEI exhibit miscibility gaps which close towards the centre of the ternary phase diagram where the mixtures become homogeneous (cosolvency). Vapour pressures were determined for the subsystem THF/γ-BL. For the theoretical calculations the Gibbs energy of mixing is formulated according to the Flory-Huggins theory and the interaction parameter χ THF γ-BL calculated from the vapour pressure…

Education Students’ Use of Collaborative Writing Tools in Collectively Reflective Essay Papers

2014

Published version of an article in the journal: Journal of Information Technology Education: Research. Also available from the publisher at: http://www.jite.org/documents/Vol13/JITEv13ResearchP091-120Brodahl0463.pdf Open Access Google Docs and EtherPad are Web 2.0 tools providing opportunity for multiple users to work online on the same document consecutively or simultaneously. Over the last few years a number of research papers on the use of these collaborative tools in a teaching and learning environment have been published. This work builds on that of Brodahl, Hadjerrouit, and Hansen (2011) expanding its case study. The theoretical framework is the same as the one underlying Brodahl et a…

Ab initio study of halogenated diphenyl ethers. NMR chemical shift prediction

2000

All-Solid-State Ag+-ISE Based on [2.2.2]p,p,p-Cyclophane

2001

All-solid-state ion-selective electrodes (ISEs) based on two ionophores with similar structure, i.e., [2.2.2] p,p,p-cyclophane and [2.2.2]m,p,p-cyclophane, were prepared and investigated. The ion-selective membranes were composed of the corresponding ionophore (1 %), potassium tetrakis(4-chlorophenyl)borate (0.5 %), 2-nitrophenyl octyl ether (65–66 %), and PVC (33 %). The ion-selective membrane was placed on top of a layer of the conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), working as ion-to-electron transducer. The resulting all-solid-state ISEs were conditioned in 0.01 M AgNO3 and investigated as Ag+-ISEs. The results show that [2.2.2] p,p,p-cyclophane is much more select…

Recent Developments in Calixarenes and Their Properties

1989

The increasing number of reports, monographs and patents dealing with the hemistry of inclusion compounds shows the growing interest of organic chemists in elaborating new chemical systems presenting novel physical and chemical properties. These properties are available for fundamental as well as applied research. On the one hand, basic studies on the structure and the nature of inclusion compounds provide information on the intermolecular forces implicated in organized systems and in enzyme processes. On the other hand, applications are in progress in laboratories and industries, for instance, in catalyzing chemical reactions, in transporting and extracting metallic cations, and in modifyi…

Analyses of known and new types of polyhalogenated aromatic substances in oven ash from recycled aluminium production

2003

Abstract Persistent aromatic bromine, chlorine and mixed chlorine-bromine compounds were analysed from recycled aluminium smelter (ALS) ashes to explore the impact of brominated flame retardants (BFR) on their formation. Polybrominated diphenyl ethers (PBDE) were the most abundant original BFRs found. Induction furnace ash contained tetra- to octa-BDEs about 2000 ng g −1 in similar congener ratios as the original scrap, but contents of nona- and deca-BDEs were only 25 and 5 ng g −1 indicating their significant degradation in ALS process. In the most non-polar fraction, PCB levels and profiles were similar as earlier ALS ash samples in 1990s. The highest PCB level measured was that of deca-C…

What makes learning and understanding in virtual teams so difficult?

2004

The ideas presented in this article are especially challenged by critical questions raised by the other authors in this special issue. One of the core questions throughout the different studies is whether participants in distributed learning groups are able to successfully work on a common task and achieve a type of interaction that leads them to educationally relevant higher-level discussion and learning. This article discusses the central findings of these studies in light of the recent research on computer-supported collaborative learning. At the beginning of the article, typical problems and challenges related to learning in virtual teams are described. In the end of the discussion, som…