Incremental synthesis

The synthesis of new material can also be divided into the twin paths of incremental synthesis of the derivatives of known structures and the wildcat synthesis of totally unrelated structures. The incremental approach is used when a material with interesting properties is discovered, and research chemists will swarm around it to make every conceivable derivative to see whether they can enlarge the menu to choose from, and to ensure that the new province is well explored. The opposite wildcat approach seeks new and exciting families of material that would not be found by adhering exclusively to known provinces. 

Though quantitative conversions on solid phase are hard to reach, besides the imperative to block truncated sequences there is another excellent chance to limit the theoretical microheterogeneity of the end product of a Merrifield synthesis. As shown above, the distribution and quantity of contaminations increase exponentially with the number of stages of an incremental synthesis, whereas the possibility of distinguishing between the main and by-products decreases in the same exponential proportion. 

The (positive and negative) examples are presented one-by-one, and the incremental synthesis mechanism debugs its current program accordingly. 

Algorithm 3-1 Incremental synthesis of logic programs from examples. 

Using the criteria defined in the two previous sections, a huge variety of stepwise synthesis strategies can be defined, fitting any valid combination of the features enumerated above. In Section 7.3.1, we briefly sketch a strategy for incremental synthesis, and in Section 7.3.2, we fully describe a strategy for non-incremental synthesis. 

In the case of incremental synthesis, let s view the steps of one synthesis increment as a macro-step performing a transformation trans. Synthesis is then the design of a series of logic algorithms ... 

In such a non-incremental synthesis, the series of expanded logic algorithms can be shown to progress upwards (see below). To achieve this expansion, we here only consider logic algorithms whose bodies are in disjunctive normal form. The used predicates are assumed to be either primitives or the predicate rhi that is defined by the logic algorithm. Let s start with a few basic definitions. 

The non-incremental synthesis strategy above can now be refined as follows, so as to achieve simultaneous upward and downward progressions [Flener and Deville 92,93ab] ... 

Now, what is the chosen strategy for stepwise synthesis We consider that all the specification information should be available for every inference during synthesis, and that a single run through all synthesis steps is hence sufficient. We thus favor a non-incremental (all-at-once) presentation of examples and properties to the synthesis mechanism. This leads to non-incremental synthesis, which is more disciplined than incremental synthesis, where parts of algorithms are continuously designed/ debugged/rejected from partial information (which is extracted from an incomplete specification). The drawback of our approach is that we can t use the identification-in-the-limit results that are known for incremental synthesis. 

So we adopt the non-incremental synthesis strategy presented in Section 7.3.2, which reflects monotonically decreasing synthesis (and is actually also monotonically increasing, if one also considers the expanded logic algorithms), as well as consistent synthesis. We also strive to make each synthesis step comply with Theorem 7-7. 

In Part III, we develop an actual logic algorithm synthesis mechanism from specifications by examples and properties, as seen in Chapter 6. It fits the particular non-incremental synthesis strategy presented in Chapter 7, is guided by the divide-and-conquer algorithm schema seen in Chapter 8, and uses the tool-box of methods developed in Chapters 9 and 10. 

BrMS89] O. Bross, P. Marwedel and W. Schenk, Incremental Synthesis and Support for Manual Binding in MIMOLA, High Level Synthesis Workshop, 1989. 

By-product power does not give enough power to match the demand for many processes such as ammonia synthesis, and designs have historically incorporated condensing turbines for incremental power with heat rejection to cooling water. A more effective response is use of the gas turbine combined cycle shown by Figures 5c and 6c. 

A molecular variation of plasma membrane has been reported by Puccia et al. Reduction of total lipids (XL) content and significant variations of triglyceride (TG) and phospholipids (PL) fractions were observed as a consequence of exposure of C. intestinalis ovaries to TBTCl solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell-adaptive standing mechanism toward the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUPA), important in the synthesis of compounds such as prostaglandin which are present in the ovary in a stress situation, was probably a consequence of a defense mechanism to the stress provoked by the presence of TBTCl. 

Use of the relatively small cyclopropane ring drastically reduces the potential for deleterious steric bulk effects and adds only a relatively small lipophilic increment to the partition coefficient of the drug. One of the clever elements of the rolicyprine synthesis itself is the reaction of d,l tranylcypromine (67) with L-5-pyrrolidone-2-carboxylic acid (derived from glutamic acid) to form a highly crystalline diastereomeric salt, thereby effecting resolution. Addition of dicyclohexylcarbodiimide activates the carboxyl group to nucleophilic attack by the primary amine thus forming the amide rolicyprine (68). 

Since zeolite catalysts are successfully introduced in the refining and petrochemical industries, it is not surprising that most of the recent advances concern incremental improvements of existing processes with the development of new generations of catalysts (e.g., dewaxing, ethylbenzene and cumene synthesis). The number of newer applications is much more limited, for example, direct synthesis of phenol from benzene and aromatization of short-chain alkanes, etc. However, both the improvement and development of processes contribute significantly to environmental advances. 

Renal osteodystrophy is a complex disorder with several pathogenic factors. Histological evidence of bone disease is common in early renal failure and deficits in calcitriol synthesis seems to be an important factor in the pathogenesis of secondary hyperparathyroidism in early CRF. The most common component is osteitis fibrosa manifested as subperiosteal resorption of bone. This is due to decreased excretion as well as increased secretion of parathyroid hormone. In CRF small increments of serum phosphorus cause small decreases in serum calcium. 

---