Thermal degradation of copolymers based on 2-substituted oxazolines and β-methylhydrogenitaconate

Summary The thermal stabilities of poly(-methylhydrogenitaconate-co-2-methyl-2-oxazoline) and poly(-methylhydrogenitaconate-co-2-ethyl-2-oxazoline) obtained by spontaneous copolymerization have been studied by programmed thermogravimetric analysis over the temperature range from 293 K to 773 K under a flow of nitrogen. Most of the copolymers do not show weight loss until 473 K and they degrade in one step. The kinetic parameters Ea, n and A were obtained following one method of thermogravimetric analysis. The reaction order for all copolymers was 1.0. The poly(-methylhydrogenitaconate-co-2-methyl-2-oxazoline)s were the most thermostable copolymers.     

Design of luminescent inorganic materials: new photophysical processes studied by optical spectroscopy

Recent spectroscopic results in the emerging area of transition-metal NIR-to-visible upconversion are related. The examples of Ti(2+)-, Re(4+)-, and Os(4+)-doped materials showing upconversion illustrate GSA/ESA, GSA/ETU, and photon avalanche multiphoton excitation mechanisms, respectively. Strategies for manipulation of such upconversion processes using the spectroscopic or magnetic properties of the host material are described. High-resolution low-temperature continuous-wave absorption and emission and time-resolved emission experiments combine to yield information about energy splittings, intensities, and excited-state dynamics, and assist in the design and development of luminescent materials showing novel multiphoton excitation properties.     

Influence of cooking and drying processes at different temperatures on the nutritive value of the protein of mussels (Mytilus edulis)

The effect of steam cooking (96 degrees C for 15 minutes) and drying at two temperatures, 70 degrees C and 110 degrees C, on nutritive value of mussel protein was studied. The measurements were carried out by nitrogen balance techniques in growing rats, and the nutritional parameters studied were: CD, BV and NPU. The crude digestibility (CD) values were: 87 +/- 1 and 82 +/- 1, and the biological values (BV), 80 +/- 1 and 74 +/- 1 for raw mussels, dried at 70 degrees C and at 110 degrees C respectively. This implies a significant decrease in the protein nutritive values of the mussel dried at a higher temperature. Cooking prior to drying significantly improved the digestibility and the biological value of the mussel's protein. In effect, improvement was so great, that the different drying temperatures did not affect the previously cooked product in a different way; therefore, the CD (94 +/- 1 and 94 +/- 1) and the BV (90 +/- 1 and 90 +/- 2) were the same for the mussel's protein, cooked and dried at 70 degrees C or at 110 degrees C.     

Application of a synthetic water-soluble poly(N-maleyl glycine-co-acrylamide) as polychelatogen for inorganic ions in aqueous solutions

Summary The water-soluble poly(N-maleyl glycine-co-acrylamide) (P(MG-co-Am)) reagent with strong complexing properties for the inorganic ions Cr(III), Co(II), Zn(II), Ni(II), Cu(II), Cd(II), Pb(II), Hg(II), As(V), and Se(IV) was investigated in aqueous phase in conjunction with membrane filtration using the Liquid-phase Polymer-based Retention (LPR) technique. The P(MG-co-Am) was shown to be useful for retention of different inorganic ions and their separation from elements not bound to the polymeric reagent. The inorganic ion interaction with the hydrophilic polymer was determined as a function of pH and filtration factor. At higher pH, the copolymer can be applied to the separation and preconcentration of most of the inorganic ions. Viscosimetric measurements of the copolymers were performed in the presence of metal ions at different pH values. Received: 8 July 1998/Revised version: 23 October 1998/Accepted: 27 October 1998     

Generalized Orowan-Petch Plot for Brittle Fracture

The fracture of brittle solids is considered to be based on a defect configuration consisting of a stress concentrator, in our case a hemispherical pore, and a starter crack, in our case either a semicircular crack, a circular crack, or a circumferential crack. Computation of the stress field, application of the relevant weight functions, and an averaging scheme based on the assumption of a virtual crack increment provides stress intensity factors for all defect configurations considered. A normalization scheme yields a generalized version of the Orowan-Petch plot in the form of a normalized strength to normalized defect size relationship.     

Urban Imaginaries: Locating the Modern City

In this article, we review three microcomputer programs for assessing regional economic impacts. The programs are ADOTMATR, GRIMP, and REMI, which we discuss in terms of their suitability for policy analysis and planning practice. We assess the programs in terms of range of applicability, flexibility and ease of use in conducting impact analyses, quality of output, and cost. ADOTMATR and GRIMP are similar; however, GRIMP is easier to use but less flexible and more limited than ADOTMATR. Although REMI is more sophisticated than the other two programs, it is more expensive and more limited in application.     

A process for the complete fractionation of baker's yeast

A process for the preparation of yeast-derived food additives was developed. The four products obtained, yeast protein concentrate (YPC), cell-wall protein (CWP), semi-pure glucomannan (SPG) and yeast extract, compared well with similar products, present in the current market, with respect to functional properties. YPC and CWP exhibited improved water-holding and oil-binding properties over those of soy-protein isolate (SPI). The emulsifying capacity was very close to that observed in commercial samples. A one-step alkaline extraction enhanced the functional properties of primary yeast glycan to match traditional food hydrocolloid sources. SPG showed oil-binding properties significantly greater than commercial glucomannan.     

Dielectric relaxation studies on polymeric salts: Poly(methylmethacrylate-co-N,N-dimethylaminopropyl-acrylamide) benzoic acid systems

A series of polymeric salts of p-substituted benzoic acids in poly(methylmethacrylate-co-N,N-dimethylaminopropylacrylamide) were prepared and AC impedance studies of film-attached electrodes were carried out. The impedance curves and conductivity variation with temperature were analysed. The parameter which describes the shape of the circular arcs in the impedance curves was temperature independent, and the distribution of relaxation times remained constant during the test on the material. Furthermore, the ionic conductivity was highly dependent on the chemical structure produced by the substituted benzoic group.     

Statistical validation of an LTE emulation tool using live video streaming over reliable transport protocols

Telecommunication Systems - Multimedia services such as Live Video-Streaming (LVS) or Video on Demand are the main drivers behind the notable traffic growth in cellular networks. This fact has...