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41.
42.
Carlo Sansour Jozef Bocko 《International journal for numerical methods in engineering》2003,58(14):2131-2160
The statement that theories of inelasticity at finite strains have arrived at a high level of development is only true in conjunction with isotropic material behaviour. From both points of view (theoretical and computational), the extension to anisotropic material behaviour seems to be a complicated task. The statement is especially true when the multiplicative decomposition of the deformation gradient is considered a basis for the formulation. Of special interest are questions related to the mathematical form of the stored energy function or, equivalently, of the constitutive relation for the material stress tensor as the thermodynamical force. This paper deals with the above issues. The anisotropic formulation is accomplished using the notion of structural tensors. Here we suggest that the privileged directions of the material should be transformed in a specific way under the action of the inelastic part of the deformation gradient. The inelastic behaviour is assumed to be governed by evolution equations of the unified type. Numerically, we deal with the full multiplicative structure of the theory. The numerical treatment is developed in full detail. Expressions concerning the local iteration as well as the tangent operator are derived. Various numerical examples with applications to shells are presented which demonstrate the influence of anisotropy and the applicability of the theory. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
43.
Kronek J Kroneková Z Lustoň J Paulovičová E Paulovičová L Mendrek B 《Journal of materials science. Materials in medicine》2011,22(7):1725-1734
Poly(2-oxazolines) with varying alkyl chain lengths (e.g., methyl, ethyl, aryl) and molar masses have been tested for cell
cytotoxicity in vitro. A standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used for the
estimation of cell viability. Two monomers, 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline, were found to provide polymers with
non-cytotoxic properties. The dependence of cell viability on molar mass confirmed the expected trend; the viability increased
with the higher molar mass of poly(2-ethyl-2-oxazoline) (PETOX), up to 15,000 g/mol. The results obtained for the polymers
with aliphatic side chains were compared with the analogues that possessed an aromatic moiety. All results confirmed low cytotoxicity
of the polymers prepared by cationic polymerization of 2-alkyl- and 2-aryl-2-oxazolines, which supports their utilization
in biomedical applications. Fluorescence microscopy and steady-state fluorescence were used to observe pyrene-labeled polymer
interactions with living cells. Polymer accumulated within the cells was found to be dependent on polymer concentration in
media. The immunoefficiency of aromatic and aliphatic oxazoline polymers and copolymers was also studied. Phagocytic and metabolic
activities of macrophages were used to assess the immunosuppressive effects of the selected copolymers for possible applications
in drug delivery and immunobiology. Overall, the tested polymers demonstrated no significant influences on the cellular immunological
parameters. 相似文献
44.
Jozef Ková Jozef Tekel Magda Kurucová 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1987,184(2):96-100
Summary The method described is based on the biochemical detection of herbicides on a silica gel thin layer following their chromatographic separation. The detection reagent is a mixture of a homogenate of bean leaves (Phaseolus vulgaris) and of the redox indicator 2,6-dichloroindophenol. This chronometric determination of herbicide residues is based on the observation that dark blue inhibition zones appear on a pale yellow-green background during the exposure of the sprayed chromatoplates Silufol to light. The dark blue zones disappear again after a time, their lifetime is proportional to the amount of the herbicide in the zone.Because of the high selectivity and sensitivity of the biochemical detection this method does not require a multiple clean-up procedure, nor does it require sophisticated instrumentation. It equals gas chromatography in sensitivity and precision. The determination limit lies between 0.01 and 0.001 mg · kg–1, the average recovery rate is 85 to 90%.
Bestimmung der Herbicid-Rückstände in landwirtschaftlichen Produkten, in Lebensmitteln, im Boden und Wasser mit der chronometrischen Methode
Zusammenfassung Die Methode stützt sich auf einen biochemischen Nachweis der Herbicide auf einer Silicagel-Dünnschichtplatte nach ihrer chromatographischen Verteilung. Das Nachweisreagens ist eine Mischung aus einem Homogenat von Blättern der Bohnen (Phaseolus vulgaris, L.) und des Redoxindikators 2,6-Dichlorphenolindophenol. Die chronometrische Bestimmung der Herbicidrückstände gründet sich auf die Beobachtung, daß während der Lichtexposition der besprühten Dünnschichtplatte Silufol auf einem gelbgrünen Hintergrund dunkelblaue Inhibitionszoneu entstehen, welche nach einer bestimmten Zeit verschwinden. Die Haltbarkeitszeit der Zone ist der Menge des Herbicids in der Zone direkt proportionell.In Betracht der hohen Selektivität und Empfindlichkeit des biochemischen Nachweises benötigt die Methode keine komplizierte Reinigung der Extrakte und keine hochentwickelte Ausstattung des Labors mit Instrumenten. Die Empfindlichkeit und Genauigkeit der chronometrischen Methode ist gleich der der Gaschromatographie. Die Bestimmungsgrenze ist 0,01 bis 0,001 mg·kg–1, die Wiederfindung ist 85–90%.相似文献
45.
Sam Schellens Cynthia Lenaerts María del Rocío Prez Baca Dorien Cools Paulien Peeters Elisabeth Marchal Jozef Vanden Broeck 《International journal of molecular sciences》2022,23(16)
Ecdysteroids are widely investigated for their role during the molting cascade in insects; however, they are also involved in the development of the female reproductive system. Ecdysteroids are synthesized from cholesterol, which is further converted via a series of enzymatic steps into the main molting hormone, 20-hydoxyecdysone. Most of these biosynthetic conversion steps involve the activity of cytochrome P450 (CYP) hydroxylases, which are encoded by the Halloween genes. Three of these genes, spook (spo), phantom (phm) and shade (shd), were previously characterized in the desert locust, Schistocerca gregaria. Based on recent sequencing data, we have now identified the sequences of disembodied (dib) and shadow (sad), for which we also analyzed spatiotemporal expression profiles using qRT-PCR. Furthermore, we investigated the possible role(s) of five different Halloween genes in the oogenesis process by means of RNA interference mediated knockdown experiments. Our results showed that depleting the expression of SchgrSpo, SchgrSad and SchgrShd had a significant impact on oocyte development, oviposition and hatching of the eggs. Moreover, the shape of the growing oocytes, as well as the deposited eggs, was very drastically altered by the experimental treatments. Consequently, it can be proposed that these three enzymes play an important role in oogenesis. 相似文献
46.
Susan Joseph Maria Rutkowska Mariola Jastrzêbska Helena Janik Jozef T. Haponiuk Sabu Thomas 《应用聚合物科学杂志》2003,89(4):1007-1016
Blends of polystyrene and polybutadiene were prepared by melt mixing. The melt rheology behavior of the blends was studied with a capillary rheometer. The morphology of the blends was examined with scanning electron microscopy. The levels of continuity and cocontinuity were studied by both morphology and dissolution techniques. The region of phase inversion was observed at 50 wt % polystyrene. Various theoretical models were applied to determine the region of cophase continuity and to locate the point of phase inversion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1007–1016, 2003 相似文献
47.
48.
Zoran Djuric Zoran Djinovic Zarko Lazic Jozef Piotrowski 《Journal of Electronic Materials》1988,17(3):223-228
A quantitative model of isothermal vapor phase epitaxy is proposed. It can be applied to both closed and open tube systems.
This model enables the prediction of compositional profiles of the layers grown by isothermal vapor phase epitaxy with dependence
on the growth parameters and thermodynamical data of the (Hg,Cd)Te system. The dependence of compositional profiles of the
ISOVPE layers on temperature and time of deposition, source to substrate spacing, mercury and inert gas pressures are discussed
for both solid and liquid sources. Modification of the compositional profiles by the postgrowth annealing has also been studied.
The proper choice of growth and annealing parameters makes the optimization of the profiles possible. The calculated profiles
are compared with the experimental data and a satisfactory quantitative fit is found in most cases. The possible reasons for
remaining discrepancies are discussed. 相似文献
49.
Wil?A.?M.?van Loon Jozef?P.?H.?LinssenEmail author Aagje?Legger Ruud?M.?H.?Heijmans Henk?C.?van Deventer Maurits?J.?M.?Burgering Bas?L.?van Drooge Alphons?G.?J.?Voragen 《European Food Research and Technology》2005,221(6):779-786
A new, energy efficient production process for French fries was developed and evaluated. Superheated steam (SHS) was used
for evaporation of water instead of pre-drying with air and par-frying with oil. The product was frozen by vacuum cooling.
Unfortunately, with this process it was not possible to reach the quality of conventional French fries. Sensory analysis indicated
that the main quality defect was a tough crust with a fatty appearance. Confocal Scanning Laser Microscopy showed that this
was caused by skin formation on the surface during both SHS drying and vacuum cooling. A frying step was necessary to obtain
a porous crust. A satisfactory product quality was feasible after drying with SHS instead of air. Due to the concessions made
for the product quality, the final energy reduction was limited. Nevertheless, this study has gained more insight into how
processing affects potato tissue on micro-scale and it has shown that a porous structure is essential for good quality French
fries. 相似文献
50.
Polaczek E Tomasik PJ Mazurkiewicz J Wrzalik R Stobinski L Tomasik P Lin HM 《Journal of nanoscience and nanotechnology》2005,5(3):479-483
Closed-end single-walled carbon nanotubes were wetted in aqueous solutions of monosaccharides, forming weak surface complexes, as proven by the estimation of the content of monosaccharides in complexes isolated from aqueous solutions. The complexation was confirmed by micro-Raman spectroscopy. The Gaussian 03 (Molecular Mechanics UFF method) computations of total energy of the single-walled carbon nanotube-monosaccharides inclusion and surface complexes showed that inclusion complexes should be more stable than corresponding surface complexes. Computed total energies for particular complexes pointed to a lack of preferences for the formation of complexes with either alpha- or beta-tautomers and either pyranoses or furanoses. The forms preferred in the formation of the surface complexes usually differ from these favored in the formation of the inclusion complexes. 相似文献