Functionality starters

Flexible polyether polyols based on high functionality starters (chain initiators) (for example a hexafunctional polyether polyol of equivalent weight 1000-2000, based on alkoxylation of sorbitol instead of glycerol), produces flexible PU foams with higher load bearing properties, but with a decrease in tensile strength and elongation. These polyols were used in carpet underlay [18]. 

Leroy, F. and De Vuyst, L. (2004) Lactic acid bacteria as functional starter cultures for the food fermentation industry. Trends Food Sci. Technol, 15, Bl-IR. 

Chung, S.FL, Kim, I.H, Park, H.G., Kang, H.S. et al (2008) Synthesis of conjugated linoleic acid by human-derived Bifidobacterium breve LMC 017 utilization as a functional starter culture for milk fermentation. ). Agric. Food Chem., 56, 3311-3316. 

However, when considering the use of probiotic strains as functional starters or co-cultures, it is important that they do not enhance acidification and thereby reduce the shelf-life of the product, and that they do not have adverse effects on the aroma or taste of the product (Heller, 2001). Uncertainty still exists as to whether multifunctional strains possessing all desirable metabolic features would result from modem isolation techniques and selection procedures. Therefore, recent studies focus on the improvement of selected strains by the application of recombinant DNA technology. By its application, certain beneficial features, such as health-promoting properties, accelerated acid production, wholesomeness and overproduction of specific enzymes or bacteriocins can be improved (Holzapfel, 2002). Gene dismption may be used to... 

In another test, Cadex measured the CCA and capacity of 20 aging but still functioning starter batteries. Figure 8.6 shows the relationship between CCA and capacity, sorted according to capacity. CCA drops somewhat with age, but not to a point where the cranking performance would be affected. Meanwhile, capacity demonstrates predictable losses on batteries 10 to 20 on the chart. Such performance degradation may not be noticeable until the motor won t crank on a cold morning due to insufficient capacity. Capacity is a more reliable state-of-health indicator than CCA (or internal resistance). 

De Vuyst, L., Zamfir, M., Mozzi, E, et al. (2003) Exopolysaccharide-produdng strains as functional starter cultures in the production of fermented milks. Int Dairy J 13, 707-717. 

Line Starters and Combination Starters A line starter consists of a contactor (motor-starting switch) and motor-overload relays, (Contactors are capable of canving and interrupting normal motor-starting and -running currents they are not, hovv ever, normally capable of interrupting short-circuit currents. They must be backed up by fuses or a circuit breaker for this function,... 

Magnetic motor starters are similar in function to manual starters except that thev are solenoid-operated, Thev are available up to 3730 kW (5()()0 hp). One of the main advantages is the convenience of electrical operation. Start-stop push buttons can be located anywhere, lien automatic or remote operation is needed, magnetic starters are essential. 

A starter or contactor with manual push-button or thermostatic operation to start and stop the fan normally controls simple systems. More complex systems that incorporate components that need control or monitoring are normally operated from purpose-built central control panels. The most common functions provided are fan motor stop, start and speed control, damper control, filter-condition indication and heater battery control. For optimum control, the system should be automatically controlled from thermostats or other sensors and a timeswitch. 

Members of the CHS/STS family of condensing enzymes are relatively modest-sized proteins of 40-47 kDa that function as homodimers. Each enzyme typically reacts with a cinnamoyl-CoA starter unit and catalyzes three successive chain extensions with reactive acetyl groups derived from enzyme catalyzed decarboxylation of malonyl-CoA.11 Release of the resultant tetraketide together with or prior to polyketide chain cyclization and/or decarboxylation yields chalcone or resveratrol (a stilbene). Notably, CHS and STS catalyze identical reactions up to the formation of the intermediate tetraketide. Divergence occurs during the termination step of the biosynthetic cascade as each tetraketide intermediate undergoes a distinct cyclization reaction (Fig. 12.2). 

The other acetogenins, shown in Table II, are a varied assortment of small molecule compounds which as a group contain alkene, alcohol, and carbonyl (acid, ester, aldehyde, and ketone) functionality. They are fairly typical substances with common structural features. Again, those compounds possessing an odd number of carbon atoms are less common, and biogenetlcally may be derived from a propionate starter unit. 

A different approach, presently appfied by the Perstorp company in the production of hyperbranched afiphatic polyesters from 2,2-bis(methylol)propionic acid [8], utihzes a B starter molecule with AB -groups condensed in consecutive steps see Fig. 1 in the middle of the diagram. In principle, the function of the B component can also be regarded as a chain stopper when all building blocks are polycondensed in one step. This also leads to a predictable and stable molecular weight at total conversion due to the excess of B-groups in the system. 

Table 4 Polymerization conditions and molecular weight data as a function of starter sequence stoichiometry for imine- containing mPEs...

Polymerization of the oxiranes is typically propagated from a starter molecule that is chosen to define the functionality if) of the final polyol. The functionality and the molecular weight of polyols are the main design features that define the polyurethane properties in the end-use applications. Additionally, the balance of EO and PO in the polyether polyols, mainly for flexible foam polyols, is tailored to enhance the compatibility of formulations and the processability of the foam products. The exact composition of the polyols defines the crucial performance features of the final polyurethane product. Even seemingly small differences in polyol composition can result in changes to polyol processabihty and polyurethane performance. This becomes a crucial issue when replacing conventional petrochemical polyols with polyols from different feedstocks. To demonstrate the sensitivity of commercial formulations to changes in feedstocks, a simple example is offered below. 

---