Technical hurdles

However, a number of technical hurdles remain that prevent routine production of human monoclonal preparations. These include ... 

RNAi technology has obvious therapeutic potential as an antisense agent, and initial therapeutic targets of RNAi include viral infection, neurological diseases and cancer therapy. The synthesis of dsRNA displaying the desired nucleotide sequence is straightforward. However, as in the case of additional nucleic-acid-based therapeutic approaches, major technical hurdles remain to be overcome before RNAi becomes a therapeutic reality. Naked unmodified siRNAs for example display a serum half-life of less than 1 min, due to serum nuclease degradation. Approaches to improve the RNAi pharmacokinetic profile include chemical modification of the nucleotide backbone, to render it nuclease resistant, and the use of viral or non-viral vectors, to achieve safe product delivery to cells. As such, the jury remains out in terms of the development and approval of RNAi-based medicines, in the short to medium term at least. 

The economic)technical approach focuses on the question of which occurrences can be extracted economically with today s technology. According to this approach, all occurrences that at present are economically extractable with existing available technology are classified as conventional, whereas occurrences that are not extract-able at present owing to economic or technical hurdles are considered unconventional. The physical properties of the oil are not taken into account. It is important to note that, in this approach, the boundary between conventional and unconventional crude oil is current, as it is subject to the market price of oil, the production cost and the available technology. 

The potential for MR sensors to interrogate on-line/in-line processes in the Food Processing industry is reiterated on an almost annual basis. Nevertheless there are a number of significant technical hurdles to be... 

The periodic table is rich and complex, and very heavy elements pose rather distinct challenges to MO theory. First, there is the purely technical hurdle that such elements have large numbers of electrons, and there is thus a concomitant requirement to use a large number of basis functions to describe them. Of course, these extra electrons are mostly core electrons, and finis a minimal representation will probably be adequate. Nevertheless, if one wants to model a small cluster of uranium atoms, for instance, the basis set size quickly becomes intractable. Not surprisingly, more electrons means more energy associated with electron correlation, too. 

Was this your answeT Because there are many technical hurdles yet to be overcome in building fusion plants, there are currently none in operation... 

The methods for the direct measurement of tropospheric hydroxyl radical, HO, are reviewed, and the technical hurdles that remain to be surmounted are discussed in the light of theoretical and experimental results. Sensitivities, advantages, and disadvantages of several HO methods are compared, and a way to compare many of the existing HO methods experimentally is presented. 

This report identifies technical hurdles and opportunities and discusses the role that government and academia can play in overcoming the nontechnical barriers to successful research, development, and transfer of these technologies to the ocean science community. Major conclusions and recommendations, discussed in detail at the end of this report, fall into two major categories, the role of the federal government and the role of academic scientists. Achievement of the recommendations will require cooperative activities between the federal government, industry, and academia (NRC, 1992). 

At this point, we had achieved access to an orthogonally protected phosphomuramyl pentapeptide derivative poised to enable completion of our lipid I total synthesis. The technical hurdles that remained to be addressed were 1) identification of a mild method for installation of the lipid diphosphate linkage, 2) global deprotection, and 3) final purification of our synthetic lipid I. Our solutions to these problems are addressed in the following section. 

Carrier facilitated transport processes often achieve spectacular separations between closely related species because of the selectivity of the carriers. However, no coupled transport process has advanced to the commercial stage despite a steady stream of papers in the academic literature. The instability of the membranes is a major technical hurdle, but another issue has been the marginal improvements in economics offered by coupled transport processes over conventional technology such as solvent extraction or ion exchange. Major breakthroughs in performance are required to make coupled transport technology commercially competitive. 

Hydrogen can be potentially produced from renewable sources, thus enabling the intermittent and excess power generated to be stored for applications in transport, homes, and businesses, thereby making off-grid wind and solar sources economic. However, it must be noted, that commercial applications of these concepts are fairly limited at best or nonexistent at worst, and many decades of research and development may be necessary to solve the technical hurdles for application in a large-scale fashion. 

The use of recombinant microorganisms for cofermentation is one of the most promising approaches in the field of bioethanol production, though their use for large-scale industrial processes still requires fine-tuning of the reliability of the entire process (2). The technical hurdles of cofermentation increase when real biomass hydrolysates have to be fermented. In fact, whatever the biomass pretreatment, the formation of degradation byproducts that could inhibit the fermentation usually requires the addition of a further detoxification step. Therefore, the production of ethanol from hydrolysates should be considered in its entirety, from the optimal pretreatment to the choice of the proper fermentation process. 

C.M. Douglas, unpublished). Demonstration of specific physical binding of MK-0911 to a fungal target remains a technical hurdle. 

The French R D focuses on three baseline processes which require high temperatures high temperature steam electrolysis (HTSE), and the sulphur-iodine (S-I) and hybrid sulphur (HyS) thermochemical cycles. Alternative cycles able to operate at lower temperatures (Cu-Cl in particular) have also been investigated. All these cycles are being assessed from a feasibility point of view and some technical hurdles remain. Laboratory-scale experiments are ongoing and will give important... 

At CEA, the studies on this process have started more recently. The two critical components of the process components are the high-temperature decomposition reactor and the SDE. Beside the European project mentioned above on the process heat reactor for S03 decomposition, CEA studies therefore focus on the electrolysis section, with a pilot now in operation in Marcoule (see Figure 7). Indeed, a major challenge for the HyS process is the development of an efficient, cost-effective SDE. Prevention of S02 migration through the separation membrane of the electrolyser, which leads to undesired sulphur deposits, remains a major technical hurdle to overcome. Like for all electrolytic processes, economic competitiveness of the cycle will also depend on the minimisation of electrolysis overvoltage and on components lifetime (membrane, interconnectors). 

The biggest advantages of fuel cells over conventional automotive energy production is the efficiency (twice as high internal combustion engines) and near zero emissions. There are, however, still a number of technical hurdles that need to be overcome before this process is commercialized these hurdles include how the fuel may safely be supplied and how the cost of the catalyst can be minimized. 

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