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31.
32.
Wey Yang Teoh Frans Denny Rose Amal Donia Friedmann Lutz Mädler Sotiris E. Pratsinis 《Topics in Catalysis》2007,44(4):489-497
A comparative photocatalytic analysis was carried out on TiO2 made in a Flame Spray Pyrolysis (FSP) process and flame-made Degussa P25. Both have similar crystallinity, phase composition,
phase segregation and a non-porous surface. Hence comparison was made based on their difference in specific surface area,
organic adsorption and the amount of OH• generated upon illumination. The photocatalytic activity tests were carried out using
the following series of organic compounds: sucrose, glucose, fructose, maleic acid, glyoxylic acid, oxalic acid, isobutyric
acid, phenol and methanol. FSP-made TiO2 outperformed P25 for saccharides mineralisation, while for phenol and methanol mineralisation P25 was better than FSP-made
TiO2. Similar mineralisation rates were observed for both FSP-made and P25 TiO2 for the mineralisation of carboxylic acids. This shows that the relative performance of the photocatalysts depends on the
type of organic compounds to be degraded. The high surface area and possibly a more efficient interfacial charge transfer
of FSP-made TiO2 provided an efficient pathway for saccharides mineralisation. As for phenol and methanol, the mineralisation rates were higher
when using P25 due to the greater amount of OH• radicals generated by this photocatalyst. The fast mineralisation rates of
carboxylic acids made degradation of these organic compounds to be less affected by the TiO2 photocatalyst properties and conditions tested in this work. 相似文献
33.
Dynamic process simulation in industrial practice. Dynamic process simulation is gaining in importance in process development and plant design. In addition to simulation tools for steady state calculations and optimization, recent years have seen increased development of software tools suitable for dynamic simulation. In particular, dynamic process models have been developed for various unit operations at universities and in industry. Application of the models includes synthesis and analysis of the control structure, start-up and shut down, safety assessments, optimization, and training. In addition, dynamic flowsheet programs analogous to the steady state programs were developed. Wider use of these program systems requires increased flexibility, solving procedures, user interfaces, model library, interfaces to external programs, etc. The present article is intended not only to describe the state of the art and describe some typical applications, but in particular to examine the demands placed on dynamic process simulation and the simulators and to delineate the current limitations of dynamic process simulation from an industrial viewpoint. 相似文献
34.
Reading frame selection of nucleic acids has important implications for protein engineering and genomics. Current methods are limited because selection of the gene of interest inevitably depends on the solubility of its translated product. Here we report the construction of the pInSALect vector, which provides strict reading frame selection without concomitant selection for protein solubility or folding. This plasmid incorporates the cis-splicing VMA intein sequence from Saccharomyces cerevisiae to facilitate the post-translational self-excision of the protein of interest, thereby eliminating potential aggregation problems. Results from two libraries of chimeric glycinamide ribonucleotide formyltransferases confirm the superior performance of pInSALect over existing reading frame selection systems. 相似文献
35.
Aqueous dispersions of anionic polyurethanes were prepared by reaction of polyethers, 1,6-hexamethylene diisocyanate, 1,2,4-benzenetricarboxylic acid anhydride and triethyl amine. Formation of the dispersion was achieved by phase reversal or by precipitation. Phase reversal occurred when the solution or the melt of the polymer was treated with water, while precipitation took place when the solution was stirred into water. The amount of acetone used has an effect on the mean particle diameter, D?T, obtained by turbidity measurements. There was an optimal acetone concentration at which D?T reached a minimum. A similar effect was observed when tetrahydrofuran, 2-butanone or acetonitrile were used as solvents instead of acetone. When the dispersion was formed by precipitation, only adequately diluted acetonic solutions formed colloidal dispersions, while concentrated solutions gave dispersions with a broad particle size distribution. 相似文献
36.
Gade LH 《Accounts of chemical research》2002,35(7):575-582
The chemistry of transition metal amides has received new impetus in recent years due to the systematic exploitation of the amido function [NR(2)](-) in ligand design. A class of 3-fold symmetrical tripodal amido ligands has proved to be a valuable tool in the stabilization of early transition metal and main group metal complexes and complex fragments. Moreover, promising strategies for their use as chemical reagents and homogeneous catalysts have been developed. An overwiew of the current state of this field is given and the potential for further development will be highlighted. 相似文献
37.
Belletier Clément Charkhabi Morteza Pires de Andrade Silva Gustavo Ametepe Kevin Lutz Mathieu Izaute Marie 《Cognition, Technology & Work》2021,23(1):103-116
Cognition, Technology & Work - Rapid technological innovations are constantly influencing the complexification and automatization of the work lines pushing human operators to use diverse... 相似文献
38.
Software and Systems Modeling - Advances in model-based system engineering have greatly increased the predictive power of models and the analyses that can be run on them. At the same time, designs... 相似文献
39.
Saif R. Kazi Michael Short Lorenz T. Biegler 《American Institute of Chemical Engineers》2021,67(1):e17056
A new method for the detailed design of shell and tube heat exchangers is presented through the formulation of coupled differential heat equations, along with algebraic equations for design variables. Heat exchanger design components (tube passes, baffles, and shells) are used to discretize the differential equations and are solved simultaneously with the algebraic design equations. The coupled differential algebraic equation (DAE) system is suitable for numerical optimization as it replaces the nonsmooth log mean temperature difference (LMTD) term. Discrete decisions regarding the number of shells, fluid allocation, tube sizes, and number of baffles are determined by solving an LMTD-based method iteratively. The resulting heat exchanger topology is then used to discretize the detailed DAE model, which is solved as a nonlinear programming model to obtain the detailed exchanger design by minimizing an economic objective function through varying the tube length. The DAE model also provides the stream temperature profiles inside the exchanger simultaneously with the detailed design. It is observed that the DAE model results are almost equal to the LMTD-based design model for one-shell heat exchangers with constant stream properties but shows significant differences when streams properties are allowed to vary with temperature or the number of shells are increased. The accuracy of the solutions and the required computational costs show that the model is well suited for solving heat exchanger network synthesis problems combined with detailed exchanger designs, which is demonstrated in Part 2 of the paper. 相似文献
40.
Silica gel or zeolites AlPO-5 and SAPO-34 are recommended as adsorbents in water-driven heat pumps because of their selective water uptake. Secondary energy, like solar energy, can be used for regeneration of loaded adsorbers. In case of the availability of only low energy levels, the use of dealuminated Y zeolite (DAY) is the better choice because of the infinitely variation of its hydrophilic properties by tailoring of the framework Si/Al ratio. Actual data on the hydrothermal stability of DAY are lacking. Thus, we report on the long-term behavior of DAY zeolites with different Si/Al ratios. 相似文献