Other Future Applications

PHA operons expressed in prokaryotes or eukaryotes can be used to help enhance cellular robustness. This mechanism should be tested In more Industrial microbial strains aiming to select strains with better resistance to the stressed conditions and, as such, enhanced yields of the bio-products, including antibiotics, vitamins, and amino acids. 

The amphiphilic proteins on PHA granule surfaces should be exploited for more applications in specific drug targeting, cell sorting, protein purification, and so on. 

There was a breakthrough when it was found that one mutant of PHA synthase was capable of incorporating lactic acid (LA) from its CoA form, lactyl-CoA (LA-CoA), into the polymer chain [67]. PHAs containing 2HA monomers, lactic acid (LA), glycolate (GL), and 2HB can be synthesized by engineered microbes in which the broad substrate specificities of PHA synthase and propionyl-CoA transferase (PCX) are critical factors for the incorporation of the monomers into the polymer chain. LA-based polymers, such as P[LA-co-3HB], have the properties of pliability and stretchiness which are distinctly different from those of the rigid poly(lactic acid) and P(3HB) homopolymers. 

To obtain a new 2HA-polymerizing PHA synthase, the class 1 PHA synthase from R. eutropha was engineered so as to achieve the first incorporation of LA units. The analysis of the polymer synthesized using this new LA-polymerizing PHA synthase unexpectedly focused on the studies on block copolymer biosynthesis. 

From the point when LA polymerization was first demonstrated, the common question has been whether it is possible to produce PLA homopolymer. The answer has been no because recombinant E. coli expressing only a combination of PhaClPsSTQK and PCT did not produce any polymer [67]. The supply of 3HB-CoA seemed to be essential to the production of LA-incorporated polymers, which was a serious obstacle for the biosynthesis of PLA and/or PLA-like polymers. 

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Molecular encapsulation in dendritic and highly branched polymers has received increasing attention recently. It was shown for dendrimers that the site isolation of a fimaional core unit in a dendritic scaffold is of great interest with respect to optical properties, catalysis, and other future applications. Detailed studies on dendrimers have revealed that at some critical dendrimer generation, the core is encapsulated by the sterically aowded and densely packed highly branched architecture. Within this context, Frechet et al introduced l-(N,N-dimethylamino)-4-nitrobenzene as a solvatochromic chromophore at the focal point of a poly(benzyl ether) dendrimer. In other works, manganese and zinc porphyrins... 

The total synthesis of ( )-estrone [( )-1 ] by Vollhardt et al. is a novel extension of transition metal mediated alkyne cyclotrimeriza-tion technology. This remarkable total synthesis is achieved in only five steps from 2-methylcyclopentenone (19) in an overall yield of 22%. The most striking maneuver in this synthesis is, of course, the construction of tetracycle 13 from the comparatively simple diyne 16 by combining cobalt-mediated and ort/io-quinodimethane cycloaddition reactions. This achievement bodes well for future applications of this chemistry to the total synthesis of other natural products. 

Other than for energy use the main current and future applications for renewable feedstocks are likely to remain in the following areas ... 

In summary, the Avada process is an excellent example of process intensification to achieve higher energy efficiency and reduction of waste streams due to the use of a solid acid catalyst. The successful application of supported HP As for the production of ethyl acetate paves the way for future applications of supported HP As in new green processes for the production of other chemicals, fuels and lubricants. Our results also show that application of characterization techniques enables a better understanding of the effects of process parameters on reactivity and the eventual rational design of more active catalysts. 

The upgrade of a frequency-domain fluorescence lifetime imaging microscope (FLIM) to a prismless objective-based total internal reflection-FLIM (TIR-FLIM) system is described. By off-axis coupling of the intensity-modulated laser from a fiber and using a high numerical aperture oil objective, TIR-FLIM can be readily achieved. The usefulness of the technique is demonstrated by a fluorescence resonance energy transfer study of Annexin A4 relocation and two-dimensional crystal formation near the plasma membrane of cultured mammalian cells. Possible future applications and comparison to other techniques are discussed. 

The applications of polarized x-ray absorption spectroscopy (PXAS) for structure determination in inorganic and bioinorganic systems are discussed. PXAS studies of oriented samples add angular detail to the information obtained from x-ray absorption edges and from EXAFS. In some cases, PXAS can be used to determine molecular orientation. In other cases, PXAS can be used to infer the details of electronic structure or of chemical bonding. Some of the potential future applications of PXAS are discussed. 

Future applications will also be considered, in particular with respect to the use of these techniques combined with the NMR of other nuclei (Na, Al, Si) for the investigation of zeolite synthesis mechanisms (12-14). 

Intermetallic science has a long and interesting history. Several interrelated topics can be considered within this subject, both from a basic viewpoint and with a view to their potential for future applications. These topics are closely connected with, or even part of, other disciplines such as physics, chemistry, metallurgy, materials science and technology, engineering. 

The cell and stacks that compose the power section have been discussed extensively in the previous sections of this handbook. Section 9.1 addresses system processes such as fuel processors, rejected heat utilization, the power conditioner, and equipment performance guidelines. System optimization issues are addressed in Section 9.2. System design examples for present day and future applications are presented in Sections 9.3 and 9.4 respectively. Section 9.5 discusses research and development areas that are required for the future system designs to be developed. Section 9.5 presents some advanced fuel cell network designs, and Section 9.6 introduces hybrid systems that combine fuel cells with other generating technologies in integrated systems. 

In this section we shall describe the results of VOA studies from the perspective of their stereochemical significance. The stereochemical applications of ROA through 1983 have recently been reviewed by Barron (14) and we consider here only a recent application from our laboratory, as well as some stereochemical correlations with existing ROA data that were uncovered as is a result of this work. In some cases for VCD, the results of a study have an immediate stereochemical impact on the molecules under investigation. In other cases, the VCD is analyzed for a molecule possessing a known, well-defined stereochemical stmcture with the aim of understanding the observed VCD and laying a foundation for future applications. 

Intramolecular rhodium-catalyzed carbamate C-H insertion has broad utility for substrates fashioned from most 1° and 3° alcohols. As is typically observed, 3° and benzylic C-H bonds are favored over other C-H centers for amination of this type. Stereospecific oxidation of optically pure 3° units greatly facilitates the preparation of enantiomeric tetrasubstituted carbinolamines, and should find future applications in synthesis vide infra). Importantly, use of PhI(OAc)2 as a terminal oxidant for this process has enabled reactions with a class of starting materials (that is, 1° carbamates) for which iminoiodi-nane synthesis has not proven possible. Thus, by obviating the need for such reagents, substrate scope for this process and related aziridination reactions is significantly expanded vide infra). Looking forward, the versatility of this method for C-N bond formation will be advanced further with the advent of chiral catalysts for diastero- and enantio-controlled C-H insertion. In addition, new catalysts may increase the range of 2° alkanol-based carbamates that perform as viable substrates for this process. 

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