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51.
A new discretization for simultaneous aggregation, breakage, growth and nucleation is presented. The new discretization is an extension of the cell average technique developed by the authors [J. Kumar, M. Peglow, G. Warnecke, S. Heinrich, and L. Mörl. Improved accuracy and convergence of discretized population balance for aggregation: The cell average technique. Chemical Engineering Science 61 (2006) 3327-3342.]. It is shown that the cell average scheme enjoys the major advantage of simplicity for solving combined problems over other existing schemes. This is done by a special coupling of the different processes that treats all processes in a similar fashion as it handles the individual process. It is demonstrated that the new coupling makes the technique more useful by being not only more accurate but also computationally less expensive. At first, the coupling is performed for combined aggregation and breakage problems. Furthermore, a new idea that considers the growth process as aggregation of existing particle with new small nuclei is presented. In that way the resulting discretization of the growth process becomes very simple and consistent with first two moments. Additionally, it becomes easy to combine the growth discretization with other processes. The new discretization of pure growth is a little diffusive but it predicts the first two moments exactly without any computational difficulties like appearance of negative values or instability etc. The numerical scheme proposed in this work is consistent only with the first two moments but it can easily be extended to the consistency with any two or more than two moments. Finally, the discretization of pure and coupled problems is tasted on several analytically solvable problems. 相似文献
52.
Ashraf El-Sayed Josef Gödde Peter Witzgall Heinrich Arn 《Journal of chemical ecology》1999,25(2):389-400
The behavioral responses of Lobesia botrana males to calling females, pheromone gland extracts, and synthetic sex pheromones were recorded in a wind tunnel. Gland extracts and synthetic pheromones were released from a pheromone evaporator. The numbers of males reaching the source and their flight tracks in response to calling females and pheromone gland extracts were compared to those of synthetic blends. Upwind flights to natural sex pheromone were straighter and faster than to a three-component blend of (E)-7,(Z)-9-dodecadienyl acetate (E7,Z9–12:Ac), (E)-7,(Z)-9-dodecadien-1-ol (E7,Z9–12:OH), and (Z)-9-docecenyl acetate (Z9–12:Ac) (100:20:5). The optimum ratio of E7,Z9–12:OH and Z9–12:Ac to E7,Z9–12:Ac was found to be 5% and 1%, respectively. An additional seven compounds identified in the sex pheromone gland were investigated for their biological activity. Two unsaturated acetates, i.e., (E)-9-dodecenyl acetate (E9–12:Ac) and 11-dodecenyl acetate (11–12:Ac), increased the number of males reaching the source as well as straightness, linear velocity, and decreased the track angle of upwind flight. Optimum response was obtained by releasing 10 pg/min E7,Z9–12:Ac in a mixture with 0.5 pg/min E7,Z9–12:OH, 0.1 pg/min Z9–12:Ac, 0.1 pg/min E9– 12:Ac and 1 pg/min 11-12–Ac. The saturated acetates previously identified in the female glands were biologically inactive. 相似文献
53.
Stephan Back Wolfgang Frosch Ignacio del Río Gerard van Koten Heinrich Lang 《Inorganic chemistry communications》1999,2(12):162
Heterotrinuclear Ti–Cu–Ru (5) and heterotetranuclear Ti–Cu–Pt–Fe (7) containing complexes are accessible by using {[Ti](CCtBu)2}CuMe (1) ([Ti]=(η5-C5H4SiMe3)2Ti) as key molecule; in 5 and 7, the corresponding early and late transition metal atoms are linked by π-conjugated organic moieties. 相似文献
54.
C. Oelgardt J. Anderson J.G. Heinrich G.L. Messing 《Journal of the European Ceramic Society》2010,30(3):649-656
We report on how the mechanical properties of sintered ceramics (i.e., a random mixture of equiaxed grains) with the Al2O3–Y2O3–ZrO2 eutectic composition compare with those of rapidly or directionally solidified Al2O3–Y2O3–ZrO2 eutectic melts. Ceramic microcomposites with the Al2O3–Y2O3–ZrO2 eutectic composition were fabricated by sintering in air at 1400–1500 °C, or hot pressing at 1300–1400 °C. Fully dense, three phase composites of Al2O3, Y2O3-stabilized ZrO2 and YAG with grain sizes ranging from 0.4 to 0.8 μm were obtained. The grain size of the three phases was controlled by the size of the initial powders. Annealing at 1500 °C for 96 h resulted in grain sizes of 0.5–1.8 μm. The finest scale microcomposite had a maximum hardness of 19 GPa and a four-point bend strength of 282 MPa. The fracture toughness, as determined by Vickers indentation and indented four-point bending methods, ranged from 2.3 to 4.7 MPa m1/2. Although strengths and fracture toughnesses are lower than some directionally or rapidly solidified eutectic composites, the intergranular fracture patterns in the sintered ceramic suggest that ceramic microcomposites have the potential to be tailored to yield stronger, tougher composites that may be comparable with melt solidified eutectic composites. 相似文献
55.
56.
Nasir Mahmood Mohammad Sohail Khan Asad Ullah Khan Klaus Werner Stöckelhuber Gert Heinrich 《应用聚合物科学杂志》2010,117(3):1493-1501
This article reports the purification and surface modification of coal ash silica and afterwards its utilization as reinforcing filler in solution‐styrene‐butadiene rubber/butadiene rubber (S‐SBR/BR). The coal ash silica free of unwanted metal ions/mineral oxides was obtained using phosphoric acid. The chemical composition of the purified coal ash silica in comparison to impure coal ash indicates the presence of characteristic hydroxyl functional group at 3440 cm?1 and an increase in the oxygen content as determined with the help of Fourier Transform Infrared and x‐ray photoelectron spectroscopy, respectively. The contact angle analysis shows that after purification the polar part of the surface energy increased to 17.5 from 12 m Jm?2. While the surface area increased to an order of magnitude, i.e., 11.6 to 110.5 m2 g?1. The modification of purified silica particles with bis(3‐triethoxysilylpropyl) tetrasulfane reveal the functionalization of hydroxyl to ‐Si‐O‐R groups as detected at 1560 cm?1. As a consequence, the modified silica based S‐SBR/BR composite resulted in improved mechanical properties due to enhanced silica‐rubber interaction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
57.
For the simulation of thermal spray coating build-up and the prediction of the coating-thickness distribution on given workpieces, an accurate representation of the mass flow emitted from the spray torch is essential. For two-dimensional (2D) simulations, this flow function often is acquired by measuring the coating thickness in cross-sectional profiles of linear spray beads, and for 3D simulations, usually some form of rotationally symmetric normal distribution function is fitted to measured profile data. However, when using free-formed complex workpieces or arbitrary and nonuniform spray paths, more realistic, nonsymmetric, and 3D flow functions are required. We present an approach to acquire accurate and fully 3D flow distribution functions by measuring 3D coating profiles which result from spraying onto a flat surface with a stationary gun, and improving them by means of a developed optimization method that takes more precise cross-sectional measurements into account. This approach thus combines the advantages of the higher accuracy of 2D measurements while fully preserving the 3D characteristics of the measured profile. 相似文献
58.
Nowadays, software tools for the flowsheet simulation of industrial processes are commonly used for design, simulation, balancing, troubleshooting and optimization purposes. Most of the tools are applicable to fluid processes only and cannot be effectively used for processes which involve solids.In this contribution we want to present the conceptual design of a new system applicable for the dynamic flowsheet simulation of complex solids processes. This system is developed as an enhancement to the existing simulation program.The novel software is able to simulate the unsteady behaviour of complex circuits of granulation processes. The transient behaviour during the start-up and changing of the process or material parameters can also be examined.As flowsheet examples, a typical spray granulation process with different schemes consisting of fluidized bed granulators, screens, mill and splitters was used. The mathematical model of the fluidized bed granulator is described by a one-dimensional population balance equation and coupled with heat and mass transfer and simple fluid dynamics.Received simulation results have shown that the proposed concept of the dynamic flowsheet simulation of granulation processes can be used effectively and has the potential to be generalized for other types of solids processes. 相似文献
59.
Chinmoy Saha Siva Ponnupandian Francis R. Costa Gert Heinrich Nikhil K. Singha 《Polymer Engineering and Science》2021,61(12):3163-3169
This investigation reports the synthesis of a new class of polyurethane (PU) based on bis(hydroxyalkyl) polydimethylsiloxane (PDMS) as diol and isophorone diisocyanate as diisocyanate followed by the preparation of PU/layered double hydroxide (PU/LDH) nanocomposite via ex-situ technique. Nuclear magnetic resonance and Fourier-transform infrared spectroscopy studies confirm the formation of PU and incorporation of PDMS into the PU backbone. Thermogravimetry analysis revealed that thermal stability of the composite improves significantly with incorporation of LDH into the PU matrix. This may be accredited to the barrier effect rendered by the LDH layers. Differential scanning calorimetry study reveals that with the incorporation of LDH, glass transition temperature (Tg) of the composite increases for an optimum level of loading beyond which it remains constant. 相似文献
60.
Natalia Schiefermeier-Mach Violetta Moresco Stephan Geley Lea Heinrich Lukas Lechner Heidi Oberhauser Susanne Perkhofer 《International journal of molecular sciences》2021,22(11)
Inhaled Aspergillus fumigatus spores can be internalized by alveolar type II cells. Cell lines stably expressing fluorescently labeled components of endocytic pathway enable investigations of intracellular organization during conidia internalization and measurement of the process kinetics. The goal of this report was to evaluate the methodological appliance of cell lines for studying fungal conidia internalization. We have generated A549 cell lines stably expressing fluorescently labeled actin (LifeAct-mRuby2) and late endosomal protein (LAMP1-NeonGreen) following an evaluation of cell-pathogen interactions in live and fixed cells. Our data show that the LAMP1-NeonGreen cell line can be used to visualize conidia co-localization with LAMP1 in live and fixed cells. However, caution is necessary when using LifeAct-mRuby2-cell lines as it may affect the conidia internalization dynamics. 相似文献