Third-generation

In the late twentieth and early twenty-first centuries, manufactured protein fibers attracted attention again due to the demand for fibers with a reduced ecological footprint. Many manufactured protein fibers are being developed with a primary emphasis on imitating the structure and properties of silk. 

For this third generation of manufactured protein fibers, milk and soy beans are the two most important protein sources. Chicken feathers also are being widely used in the development. In addition to the common methods used in the first and second generations, many technical innovations have been applied to the production of these manufactured protein fibers. Examples include the use of biochemistry to modity the protein structure, the incorporation of synthetic polymers to improve the fiber strength and modulus, the formation of protein-based copolymers by chemical grafting, etc. 

Fibers , in Structure Formation in Polymeric Fibers, editor Salem, D.R., Hauser Gardner Publications, 2000. 

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The LMTO method [58, 79] can be considered to be the linear version of the KKR teclmique. According to official LMTO historians, the method has now reached its third generation [79] the first starting with Andersen in 1975 [58], the second connnonly known as TB-LMTO. In the LMTO approach, the wavefimction is expanded in a basis of so-called muffin-tin orbitals. These orbitals are adapted to the potential by constmcting them from solutions of the radial Scln-ddinger equation so as to fomi a minimal basis set. Interstitial properties are represented by Hankel fiinctions, which means that, in contrast to the LAPW teclmique, the orbitals are localized in real space. The small basis set makes the method fast computationally, yet at the same time it restricts the accuracy. The localization of the basis fiinctions diminishes the quality of the description of the wavefimction in die interstitial region. 

Tank R W and Arcangell C 2000 An Introduction to the third-generation LMTO method Status Solid B 217 89... 

Cell—Cell Interactions. Older generations of leukocyte filters depended partly on the formation of platelet—leukocyte—thrombin formations. It is not clear whether this mechanism plays a role in third-generation filters. 

Gestodene Gestodene (54), along with norgestimate and desogestrel, are the progestin components of the third-generation oral contraceptives (see Contraceptives). It may be crystallised from hexane/acetone (81) or ethyl acetate (82), and its crystal stmcture (83) and other spectral data have been reported (84). 

The third generation are latices made with independentiy prepared surfactant to mimic the in situ prepared functional monomer surfactant. These emulsifiers are often A—B block polymers where A is compatible with the polymer and B with the aqueous phase. In this way surface adsorption of the surfactant is more likely. These emulsions are known to exhibit excellent properties. 

As of 1995, there were no nuclear fuel reprocessing plants operating in the United States. Other nuclear nations have constmcted second- or third-generation reprocessing faciUties. These nations have signed the nuclear nonproliferation treaty, and the faciUties are under the purview of the International Atomic Energy Agency (IAEA). 

First generation Second generation Third generation... 

Fig. 4. Activity vs polymerization time. Polymerization occurs in hexane at 343 K (70°C) and 0.7 MPa (7 bat) with a superactive third-generation catalyst...

Montedison and Mitsui Petrochemical iatroduced MgCl2-supported high yield catalysts ia 1975 (7). These third-generation catalyst systems reduced the level of corrosive catalyst residues to the extent that neutralization or removal from the polymer was not required. Stereospecificity, however, was iasufficient to eliminate the requirement for removal of the atactic polymer fraction. These catalysts are used ia the Montedison high yield slurry process (Fig. 9), which demonstrates the process simplification achieved when the sections for polymer de-ashing and separation and purification of the hydrocarbon diluent and alcohol are eliminated (121). These catalysts have also been used ia retrofitted RexaH (El Paso) Hquid monomer processes, eliminating the de-ashing sections of the plant (Fig. 10) (129). 

Third-generation high yield supported catalysts are also used in processes in which Hquid monomer is polymerized in continuous stirred tank reactors. The Hypol process (Mitsui Petrochemical), utilizes the same supported catalyst technology as the Spheripol process (133). Rexene has converted the hquid monomer process to the newer high yield catalysts. Shell uses its high yield (SHAC) catalysts to produce homopolymers and random copolymers in the Lippshac process (130). 

Future Outlook for Antidepressants. Third-generation antidepressants are expected to combine superior efficacy and improved safety, but are unlikely to reduce the onset of therapeutic action in depressed patients (179). Many dmgs in clinical development as antidepressive agents focus on estabhshed properties such as inhibition of serotonin, dopamine, and/or noradrenaline reuptake, agonistic or antagonistic action at various serotonin receptor subtypes, presynaptic tt2-adrenoceptor antagonism, or specific monoamine—oxidase type A inhibition. Examples include buspirone (3) (only... 

P. A. Roussel, K. N. Saad, and J. J. Eiickson, Third Generation RC D, Haivaid Busiaess School Piess, Bostoa, Mass., 1991. 

It should be noted that the classification iato generations is not chronological, and so some second-generation compounds came to the market relatively recendy, after the third-generation was firmly estabUshed. Within each class there is also a further classification as to whether the compounds are administered orally or parenteraHy. A contemporary variation of the generation classification has been proposed, but has not found widespread use (85). Another proposal groups cephalosporins according to clinical indication or appHcation (86). 

The antibacterial spectmm of moxalactam (Table 9) is similar in breadth and potency to that of cefotaxime (36). Hence, moxalactam (48) is classified with the third-generation cephalosporins. In general 1-oxacephalosporins are considerably more susceptible to P-lactamases than their sulfur counterparts... 

Cephalosporins first entered the marketplace in 1964, when cephalothin (27) and cephaloridine (51), which are both injectable, were launched. By the late 1970s, the injectable cephalosporins had become important therapeutic agents in the hospitals. Also in 1964 the first oral cephalosporin, cephaloglycin [3577-01 -3] C gH N OgS, was launched only to be displaced by the end of the year by cephalexin (12). For years cephalexin was the leading oral cephalosporin on the market. It has since been displaced by cefaclor (13). With the advent of the more -lactamase stable cephalosporins such as cefoxitin (23) and cefuroxime (35), and the more potent agents such as cefotaxime (36) and other third-generation compounds, cephalosporins now dominate the antibiotic market worldwide. 

None of these second- or third-generation processes has been commercialized, largely because of the relatively low price of available Hquid and gaseous fuels. 

T. Inoue and co-workers, Toyota Eean Combustion System—the Third Generation System, SAE 930873, Society of Automotive Engineers, Warrendale, Pa., 1993. 

Norfloxacin (1, R = C2H5, R = H), a typical example, exhibits broad-spectrum activity and is useful in the treatment of upper respiratory tract and urinary infections [7] Lomefloxacin (2), a very recent introduction, is a third-generation product that, given once daily, is especially useful against pathogens resistant to cephalosponns, penicillins, and aminoglycosides [4] Floxacillin (J) is a stable, orally active antibacterial with improved activity over thenonfluonnated product (cloxacillin) [5]... 

More then a dozen representatives of the above ring systems were introduced into the human therapy. Actisomide (2) and trequinsin (3) are used as antiarrhytmic and antihypertensive agents, respectively. Sunepitron (4), a a 2-adrenoceptor antagonist, is under clinical trials for the treatment of anxiety and depression. Representatives of the third generation of antibacterial quinolone-3-carboxylic acids the blockbluster ofloxacin (5), its levorotatory enantiomer, levofloxacin (6), and rufloxacin (7) have gained wide acceptance for the treatment of bacterial infections of the respiratory and urinary tracts, skin, and soft tissues, as well as sexually transmitted diseases, and pazufloxacin (8) is under development. Praziquantel (9) is widely applied for the treatment of schistosomes- and cestode-caused infection in both veterinary and human therapies (Scheme 4). 

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