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91.
92.
As waterborne emulsions continue to replace their solvent‐based counterparts in various applications, the water resistance of cast films is attracting significant interest. The characterization of the water sorption kinetics and structure–property relationships related to water sorption is, therefore, an important area for investigation. In this study, the water sorption kinetics of emulsion blends were compared with those of their blend components. The investigated blends were at equal weight (dry basis) fractions for each emulsion. The initial water sorption rate for immiscible emulsion blends was found to be significantly higher than composite values of the constituents. This behavior was due to percolation networks in the blends because thermodynamic constraints prevented diffusion across the interface bordering dissimilar particles, leaving a interface enriched with water‐sensitive species. The peak water sorption for the immiscible emulsion blends was lower than the composite values because of the ability of the water‐sensitive species to rapidly diffuse out of the samples due to the percolation network. This behavior existed for room‐temperature‐cast samples and persisted as the time and temperature exposure was increased. Atomic force microscopy results clearly showed the potential for percolation networks in the blends. Higher glass‐transition emulsion polymers [e.g., poly(vinyl acetate)] exhibited similar behavior, and this indicated poor film formation like that for the immiscible emulsion blends. These results indicated that the degree of film formation was critical with respect to the water sorption characteristics of emulsion films. Immiscible emulsion blends were compared with miscible emulsion blends for which all constituents exhibited excellent film formation (unblended). The immiscible blends exhibited a significant difference in water sorption compared with the miscible blends because of the existence of percolation networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 933–939, 2003 相似文献
93.
Decsi T Boehm G Tjoonk HM Molnár S Dijck-Brouwer DA Hadders-Algra M Martini IA Muskiet FA Boersma ER 《Lipids》2002,37(10):959-965
Long-chain PUFA play an important role in early human neurodevelopment. Significant inverse correlations were reported between values of trans isomeric and long-chain PUFA in plasma lipids of preterm infants and children aged 1–15 yr as well as in venous cord blood lipids of full-term infants. Here we report FA compositional data of cord blood vessel wall lipids in 308 healthy, full-term infants (gestational age: 39.7±1.2 wk, birth weight: 3528±429 g, mean±SD). The median (interquartile range) of the sum of 18-carbon trans FA was 0.22 (0.13)% w/w in umbilical artery and 0.16 (0.10)% w/w in umbilical vein lipids. Nonparametric correlation analysis showed significant inverse correlations between the sum of 18-carbon trans FA and both arachidonic acid and DHA in artery (r=−0.38, P<0.01, and r=−0.20, P<0.01) and vein (r=−0.36, P<0.01, and −0.17, P<0.01) wall lipids. In addition, the sum of 18-carbon trans FA was significantly positively correlated to Mead acid, a general indicator of EFA deficiency, in both artery (r=+0.35, P<0.01) and vein (r=+0.31, P<0.01) wall lipids. The present results obtained in a large group of full-term infants suggest that maternal trans FA intake is inversely associated with long-chain PUFA status of the infant at birth. 相似文献
94.
Freeze‐dried and milled lignocellulose nanofibrils (LCNF) were used to reinforce polypropylene (PP) nanocomposites. The LCNF, containing up to 9% lignin, was obtained from residual Empty Palm Fruit Bunch (EPFB) fibers. Soy protein isolate (SPI) and hydroxypropyl cellulose (HPC) were tested as coupling agents as well as maleic anhydride grafted polypropylene (MAPP), which was used as a reference. A good level of dispersion of LCNF in the PP matrix while mechanical testing and thermal analyses indicated an improvement of the thermo‐mechanical behavior of the nanocomposites was revealed upon loading of the lignin‐containing nanofibrils. The tensile modulus of PP was increased by 15% upon the addition of 1% LCNF with SPI as a compatibilizer. Likewise, the thermal stability of the composites was most markedly enhanced. Overall, LCNF and SPI, two important bioresources, are introduced here for the development of novel and cost‐effective PP‐based composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43854. 相似文献
95.
96.
Ingrid Campo-Ruiz 《Planning Perspectives》2013,28(4):639-657
The exponential growth of industrialized cities at the turn of the twentieth century led town planners and architects in Sweden to design new cemeteries and engage in the discussion with novel approaches to commemoration. Malmö Eastern Cemetery (1916–1973) was designed by Sigurd Lewerentz (1885–1975) and represented an ambitious experiment: a new scale of cemetery landscape, which involved planting vegetation anew and detracted from sweeping picturesque designs. This paper analyses how Lewerentz's approach to the equality of individual tombstones affected his design of Malmö Eastern Cemetery, both in terms of burial spaces for individuals and the commemorative public realm. Based on archival research and field work, this paper delves into the interplay between the cemetery designers and the different urban planners of Malmö over a period of dramatic transformation in the eastern districts of the increasingly industrialized city. Although Lewerentz initially differentiated between tombstones, after 1922 he reconsidered his cemetery plans, setting standards that made commemoration accessible to everyone while limiting individual choices. Lewerentz's homogenizing decisions in planning Malmö cemetery provide a lens through which to examine how equality has shaped discussions around commemoration, representing ideals of societies across history and the underlying tensions between individual freedom and society. 相似文献
97.
Comments on the article by B. D. Slife and R. N. Williams (see record 84-17550) concerning theoretical psychology as a subdiscipline of psychology. The authors agree that important philosophical and metatheoretical issues confront psychology and that greater training in these areas is needed at the doctoral level; however, they do not agree with the negative assessment of positivism nor with the recommendation that specially trained theoreticians should serve as consultants in psychology departments. It is believed that the content of the proposal was vague and the use of the term theory is confusing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
99.
Ingrid Fogy Erich R. Schmid und Josef F. K. Huber 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1980,170(3):194-199
Zusammenfassung Carbamatpesticide können auch in sehr komplex zusammengesetzten Obst- und Gemüsearten mit Hilfe der mehrdimensionalen Hochdruckflüssigkeitschromatographie im ppm-Bereich nachgewiesen werden. Dabei wird eine Fraktion des Effluents der ersten Säule, die das von Matrixbestandteilen nur unvollständig getrennte Pesticid enthält, mittels eines Schalthahns auf eine zweite Säule mit einer anderen stationären Phase gebracht, wo die Trennung vervollständigt wird. Die erhöhte Auflösung im Zweisäulen Betrieb wird durch die unterschiedlichen Selektivitätskoeffizienten von Wirkstoff und störenden Pflanzenbestandteilen in den beiden Phasensystemen bewirkt. Daneben kann man bei geeigneter Wahl der Fraktionsgrenzen eine relative Anreicherung des Carbamateserreichen. Da bei den verwendeten Phasensystemen die meisten Pflanzenbestandteile relativ schnell eluiert werden, gelingt besonders bei Carbamaten mit hohem Kapazitätskoeffizienten eine eindeutige Identifizierung und Quantifizierung manchmal schon mit der ersten chromatographischen Säule allein. Wegen der hohen Trennkapazität der mehrdimensionalen Hochdruckflüssigkeitschromatographie besteht die Probenvorbereitung nur aus einer Extraktion des Pflanzenmaterials mit Dichlormethan. Nach Ersatz des Extraktionsmittels durch die mobile Phase kann die Lösung direkt in den Flüssigkeitschromatographen injiziert werden.
Determination of carbamate pesticides in fruits and vegetables by multi-dimensional high pressure liquid chromatography
Summary Carbamate pesticides can be determined at the ppm level even in very complex extracts of different kinds of fruits and vegetables by means of multidimensional high pressure liquid chromatography. The effluent fraction of the first column containing the pesticide insufficiently separated from matrix compounds is transferred by column-switching to a second column with another stationary phase, where the separation is completed. The improved resolution in the two-column mode is caused by the different selectivity coefficients of carbamate and plant components for the two phase systems used. Furthermore, a relative enrichment of the carbamate can be achieved by a suitable choice of size and position of the transferred fraction. Carbamates with a high capacity factor can be determined on a single chromatographic column in general, since most plant constituents are eluted early on this type of column.Due to the high separating power of multidimensional high pressure liquid chromatography the sample pretreatment consists only of an extraction of the plant material with dichloromethane. After replacing the extraction solvent by the mobile phase the sample can be injected directly into the liquid chromatograph.相似文献
100.
Ingrid Einsiedler 《电子与电脑》2009,(4):37-40
对于需要零故障和误差的自动充填和包装生产线而言,先进的图像处理系统正成为越来越不可或缺的部分。系统中使用的嵌入式计算机技术需要在恶劣环境中提供最佳的价格、高可靠性的实时性能。为满足这些需求, 相似文献