Chemical Robustness

The situation gains complexity when CO2 and H2O are fed simultaneously. These molecules compete with oxygen for the adsorption sites in the membrane 

As for the BSCF family, B-site substitution improves the stability toward CO2-rich atmospheres. Sirman [74] established that the CO2 tolerance of perovskite 

Irrespective of the selected concept, important advances have been made in the recent years, and a variety of promising materials are reported. Nevertheless, the presence of more gases has to be taken into consideration. 

The influence of carbon dioxide on the oxygen permeation of MIEC membranes has been extensively studied compared with the effect of other gases, such as SO2, which can also be present in the gas streams. Of course, CO2 will be the major component of a hypothetical gas mixture where the MIEC membrane should work (e.g., oxy-fuel process). Nevertheless, the influence of SO2 must be mandatorily evaluated and represents one of the biggest concerns in this area. For example, the SO2 concentration in the flux gas can be around 400 ppm or even higher than 1000 ppm, as reported before the scrubber system in some power plants in China [82]. Up to 2011, few reports can be found dealing with membrane operation in SO2 environments. However, on related topics, for example, catalysis, several studies revealed the formation of sulfetes and sulfldes 

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Even the chemically robust perfluoroalkanes can undergo electron-transfer reactions (equation 4) because of their relatively high electron affinities [89]. Strong reduemg agents like alkali metals [90] or sodium naphthahde [91] are normally required for reaction, but perfluoroalkanes with low-energy, tert-C-F a anti-... 

Membrane Types Key membrane properties include their size rating, selectivity, permeability, mechanical robustness (to allow module fabrication and withstand operating conditions), chemical robustness (to fabrication materials, process fluids, cleaners, and sanitizers), low extractibles, low fouling characteristics, high capacity, low cost, and consistency. 

Kay C, Murray PJ, Sandow L, Flolmes AB. A novel, chemically robust, amine-releasing linker. Tetrahedron Lett 1997 38 6941-6944. 

The glass is chemically robust, so the GE can be used in oxidizing or reducing conditions and the internal acid solution cannot contaminate the analyte... 

If one examines the evolution of new zeolite structures over the past decade the most interesting discoveries have been made with high silica compositions. Many of these phases can be prepared in essentially all silica forms. Purists would prefer to classify such molecular sieves as organosilicates or porosils (1), in part because the physical properties differ from more classical low Si/Al ratio zeolites. In particular, the high silica zeolites tend to be more thermally stable and chemically robust. Additionally, the higher the Si/Al ratio the more hydrophobic the zeolite. These features are desirable for catalysts that may be used in catalytic processes such as cracking (3). 

As was demonstrated, a variety of polymeric materials are used for preparation of dye-doped beads. Dye-doped silica beads are also extremely popular due to their chemical robustness, biocompatibility and simplicity in preparation and further functionalization of the surface [55]. Thus, polymeric, silica and Ormosil beads (which occupy intermediate position) are widely used as nanosensors and labels. On the other hand, quantum dots possess much higher cytotoxicity which often limits their application in biological systems. 

SrTiOs is a mechanically and chemically robust material with a simple perovskite structure. N-type SrTiOz can be achieved by reducing it with Hz for 4h at 1050-1100°C the resulting single... 

The problem with the ether and ester linkage is that they are often hydrolytically unstable, and so there have been approaches to replace the CIO acetal linkage with more chemically robust linkages. Posner s group prepared a series of CIO olefinic non-acetal dimers and CIO saturated dimers that showed good antiproliferative activities . Dimers 108-110 were aU especially potent and selective at inhibiting leukaemia and colon cancer in the NCI assay (Scheme 38) . ... 

Amylose brushes (a layer consisting of polymer chains dangling in a solvent with one end attached to a surface is frequently referred to as a polymer brush) on spherical and planar surfaces can have several advantageous uses, such as detoxification of surfaces etc. The modification of surfaces with thin polymer films is widely used to tailor surface properties such as wettability, biocompatibility, corrosion resistance, and friction [142-144]. The advantage of polymer brushes over other surface modification methods like self-assembled monolayers is their mechanical and chemical robustness, coupled with a high degree of synthetic flexibility towards the introduction of a variety of functional groups. 

There is still no perfect green IL and the search for improvements that combine chemical robustness with favorable biodegradability and toxicology remains an active field of research. 

Ni, Z-J. Maclean, D. Holmes, C. P. Murphy, M. M. Ruhland, B. Jacobs, J. W. Gordon, E. M. Gallop, M. A. Versatile Approach To Encoding Combinatorial Organic Syntheses Using Chemically Robust Secondary Amine Tags, J. Med. Chem. 1996, 39, 1601. 

The still modest yield (8%) obtained with the hexamethylene linker being far from satisfactory, we explored various other possibilities. Among them a 1,3-phe-nylene spacer, already used with success by others in the construction of helical complexes [99-101], seemed very appealing owing to its expected chemical robustness (necessary to survive the harsh cyclization conditions) and ease of introduction following our methodology [95]. 

In summary, we were able to develop a chemically robust synthetic route to lipid I, the penultimate intermediate utilized in bacterial cell wall biosynthesis. The identification of a method for stereoselective introduction of the anomeric phosphate and a protocol to enable diphosphate coupling were pivotal to our success and ultimately provided the precedent for our chemical synthesis of lipid II detailed in the sections that follow. 

A more chemically robust polymer-supported chiral catalyst, based on a,a-diphenyl-L-prolinol, was designed by Kell et a/.11411 for reduction of prochiral ketones with borane. 

Kell, R. J., Hodge, P., Snedden, P. and Watson, D. Towards more chemically robust polymer-supported chiral catalysts alpha,alpha-diphenyl-L-prolinol based catalysts for the reduction of prochiral ketones withborane. Org. Biomol. Chem., 2003,1, 3238-3243. 

These redistribution reactions between metal-tin complexes not only provide extremely useful transition-metal-substituted organotin chlorides, but also demonstrate the chemical robustness of the M—Sn bonds. For example, whereas the W—Sn bond in [(CO)5WSnPh3] resists attack by dry HC1, the silicon and germanium analogs are cleaved to [C1W(C0)5] 49. 

Molecular tags overcome the chemical sensitivity and orthogonal protection required by both peptide and oligonucleotide encoding. Two such methods have been developed and applied to the synthesis of both peptide and nonoligomeric libraries. One of these [34] approaches uses chemically robust haloaromatic tags which are used in a binary encoding... 

The synthesis of the tetracyanoborate anion [TCB] was first described by Bessler [89, 90], but only the improvement of the sinter process of the key intermediate potassium [TCB] [91] has made this material available in reasonable amounts and thus allowed the synthesis of [TCB] -based ionic liquids [92]. The low viscosity (20 cP at 20 °C) and thermal and chemical robustness led to the use of [EMIM][TCB] as an electrolyte for DSSC [93]. 

To achieve chemically robust low-cost separators, ceramic membranes have been suggested by Sanchez etal. [89], ANafion 117 membrane and a ceramic diaphragm... 

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