Control molecular-level

Abstract To appreciate the technological potential of controlled molecular-level motion one only has to consider that it lies at the heart of virtually every biological process. When we learn how to build synthetic molecular motors and machines that can interface their effects directly with other molecular-level sub-structures and the outside world it will add a new dimension to functional molecule and materials design. In this review we discuss both the influence of chirality on the design of molecular level machines and, in turn, how molecular level machines can control the expression of chirality of a physical response to an inherently achiral stimulus. 

Based on the plethora of applications of thermistor/thermopile based devices, it can be concluded that the field of thermometric sensing offers several avenues of progress in materials science, process monitoring, process control, molecular level detection, characterization of biocatalysts, hybrid sensing and multisensing devices, as well as in telemedicine and other areas of biomedical analysis. 

The DEP of numerous particle types has been studied, and many apphcations have been developed. Particles studied have included aerosols, glass, minerals, polymer molecules, hving cells, and cell organelles. Apphcations developed include filtration, orientation, sorting or separation, characterization, and levitation and materials handhng. Effects of DEP are easily exhibited, especially by large particles, and can be apphed in many useful and desirable ways. DEP effects can, however, be observed on particles ranging in size even down to the molecular level in special cases. Since thermal effects tend to disrupt DEP with molecular-sized particles, they can be controlled only under special conditions such as in molecular beams. 

The aim of the model is to find the relation between the energy dissipated in growing the crack tip craze, as that is the macroscopic toughness and the local force at the fibril closest to the crack tip which controls the molecular level failure... 

Le Chatelier s Principle permits the chemist to make qualitative predictions about the equilibrium state. Despite the usefulness of such predictions, they represent far less than we wish to know. It is a help to know that raising the pressure will favor production of NH3 in reaction (10a). But how much will the pressure change favor NH3 production Will the yield change by a factor of ten or by one-tenth of a percent To control a reaction, we need quantitative information about equilibrium. Experiments show that quantitative predictions are possible and they can be explained in terms of our view of equilibrium on the molecular level. 

Molecular structure of coenzyme Q, an antioxidant used by the bodv to control the level of radicals. 

This chapter begins by explaining how the rates of reactions are determined experimentally and showing how their dependence on concentration can be summarized by succinct expressions known as rate laws. We then see how this information gives us insight into how reactions take place at a molecular level. Finally, we see how substances called catalysts accelerate reactions and control biological processes. 

The rate law for a reaction is a window into the changes that take place at the molecular level in the course of the reaction. Knowing how those changes take place provides answers to many important questions. For example, what controls the rate of formation of the DNA double helix from its individual strands What molecular events convert ozone into oxygen or turn a mixture of fuel and air into carbon dioxide and water when it ignites in an engine ... 

A major force behind this evolntion will be the explosion of new products and materials that will enter the market dnring the next two decades. Whether from the biotechnology industry, the electronics industry, or the high-performance materials indnstry, these products will be critically dependent on structure and design at the molecular level for their usefulness. They will require manufacturing processes that can precisely control their chemical composition and stracture. These demands will create new opportunities for chemical engineers, both in product design and in process irmovation. 

In the past three decades, industrial polymerization research and development aimed at controlling average polymer properties such as molecular weight averages, melt flow index and copolymer composition. These properties were modeled using either first principle models or empirical models represented by differential equations or statistical model equations. However, recent advances in polymerization chemistry, polymerization catalysis, polymer characterization techniques, and computational tools are making the molecular level design and control of polymer microstructure a reality. 

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