Metal tuning

The combination of metal tuning and double stereodifferentiation helps to prepare chelation and nonchelation products in the imine series7. In the case of an alkoxy substituent adjacent to the aldimino, the chelation product 10 is predominantly obtained with allylmagnesium chloride, chloromagnesium allyltriethylaluminate or allylzinc bromide, while the use of allyl-boronates or allyltitanium triisopropoxide, which lack the requisite Lewis acidity for chelation, gives 11 with good Cram selectivity. 

Neglect the tube and shell metal. Tune PI controllers experimentally for each system. Find the outlet temperature deviations for a 25 percent step, increase in process flow rate. 

When a yaw rate occurs, the Coriolis force leads to a deflection of the ends of the tuning fork out of the oscillating plane. This sensor element consists of a metal tuning fork, on which four piezoelements are located two for the drive in the lower area and two for detection in the upper area. 

Qian, C. Zhu, D. Studies on organolanthanide complexes. Part 55. Synthesis of fiiran-bridged bis(cyclopentadienyl)lanthanide and yttrium chlorides, and hgand and metal tuning of reactivity of organolanthanide hydrides (in situ). J. Chem. Soc., Dalton Trans. 1994, 1599-1603. 

Boron is one element that features in a study of the influence of "metal-tuning" on stereo and regio-chemical convergence in... 

The influence of (organo)metallics metal-tuning on stereo- and regio-chemical convergence in reactions of allylic carbanions with aldehydes, Y. Yamamoto, Y. Saito and K. Maruyama, J.Organomet.Ch n.. 1985, 292, 311. 

S. Hiinig, DCNQI-based Organic Metals Tuning Solid State Properties by Molecular Substitution, in New Organic Materials, C. Seoane and N. Martin (Eds.), Universidad Complutense de Madrid, 1994. 

Metal catalyzed polymerizations are chain reactions necessitating a constant valence of the metal. In contrast to that metal catalyzed polycondensations are step growth reactions involving a change of the valence of the metal. Tuning of the reaction by structural variations of the metal catalyst are demonstrated with the Pd-catalyzed vinyl polymerization of norbomene, the alternating copolymerization of ethylene with carbon monoxide and the Heck reaction as examples. One and two electron processes can be involved in metal catalyzed polycondensations. The Heck reactions, the Ni-catalyzed synthesis of polyphenylenes, and Ru-catalyzed ArH-insertion reactions are discuss. ... 

Each metal or metalloid displays a reactivity pattern of its own. "Metal tuning," the search of the optimal element for a given transformation, is a central issue in metal-mediated organic synthesis.Far from being exhaustive, the survey below highlights just a few typical aspects. 

Electron donor molecules are oxidized in solution easily. Eor example, for TTE is 0.33V vs SCE in acetonitrile. Similarly, electron acceptors such as TCNQ are reduced easily. TCNQ exhibits a reduction wave at — 0.06V vs SCE in acetonitrile. The redox potentials can be adjusted by derivatizing the donor and acceptor molecules, and this tuning of HOMO and LUMO levels can be used to tailor charge-transfer and conductivity properties of the material. Knowledge of HOMO and LUMO levels can also be used to choose materials for efficient charge injection from metallic electrodes. 

Unlike the aircraft turbiae, the ground-based gas turbiae operates continuously at the same power setting, usually 60—80% of maximum power output except when starting. Air and fuel flow patterns are constant and the combustor can be tuned to minimise smoke formation and high metal temperatures. 

Synthetic polymers have become extremely important as materials over the past 50 years and have replaced other materials because they possess high strength-to-weight ratios, easy processabiUty, and other desirable features. Used in appHcations previously dominated by metals, ceramics, and natural fibers, polymers make up much of the sales in the automotive, durables, and clothing markets. In these appHcations, polymers possess desired attributes, often at a much lower cost than the materials they replace. The emphasis in research has shifted from developing new synthetic macromolecules toward preparation of cost-effective multicomponent systems (ie, copolymers, polymer blends, and composites) rather than preparation of new and frequendy more expensive homopolymers. These multicomponent systems can be "tuned" to achieve the desired properties (within limits, of course) much easier than through the total synthesis of new macromolecules. 

Chemical inhibitors, when added in small amounts, reduce corrosion by affecting cathodic and/or anodic processes. A wide variety of treatments may be used, including soluble hydroxides, chromates, phosphates, silicates, carbonates, zinc salts, molybdates, nitrates, and magnesium salts. The exact amount of inhibitor to be used, once again, depends on system parameters such as temperature, flow, water chemistry, and metal composition. For these reasons, experts in water treatment acknowledge that treatment should be fine tuned for a given system. 

This first group of chapters looks at metals. There are so many different metals - literally hundreds of them - that it is impossible to remember them all. It isn t necessary - nearly all have evolved from a few "generic" metals and are simply tuned-up modifications of the basic recipes. If you know about the generic metals, you know most of what you need. 

The torsionally soft or resilient coupling such as the quill shaft and the metal-metal resilient transmit torque can handle misalignment through springs, metal strips, coils, disks and diaphragms, They will tune the system by changing the spring constant K. 

The elastomer compression coupling provides both tuning and damp ing to the system. In some cases, the two functions interact, that is, the stiffness K or damping C may be a function of the other. The elastomers are torsionally softer than the metal-metal resilients, but will introduce higher levels of damping into the system. 

Abstich, m. tapping, drawing running tapped metal contrast, -loch, n., -bffnung, /. tap hole, -pfanne,/. (Metal.) tap ladle. abstimmen, v.i. disagree vote. — v.t. tune ... 

In comparison with catalytic reactions in compressed CO2 alone, many transition metal complexes are much more soluble in ionic liquids without the need for special ligands. Moreover, the ionic liquid catalyst phase provides the potential to activate and tune the organometallic catalyst. Furthermore, product separation from the catalyst is now possible without exposure of the catalyst to changes of temperature, pressure, or substrate concentration. 

Based on the above results they have concluded that the ligand groups circularly arranged on the lower rim of the calixarene cavity construct a novel cyclic metal receptor for selective extraction of transition metal cations. Results suggest that the fine tuning in molecular... 

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