Molecular organization requirements

Of course, the molecular organization required to achieve the desired chemical and electrical properties will also determine the mechanical properties of any practical structure we are to make. These three properties (chemical, electrical, and mechanical) are inextricably linked. 

The most important task of the red blood cells (erythrocytes) is to transport molecular oxygen (O2) from the lungs into the tissues, and carbon dioxide (CO2) from the tissues back into the lungs. To achieve this, the higher organisms require a special transport system, since O2 is poorly soluble in water. For example, only around 3.2 mb O2 is soluble in 1 L blood plasma. By contrast, the protein hemoglobin (Hb), contained in the erythrocytes, can bind a maximum of 220 mb O2 per liter—70 times the physically soluble amount. 

This book, my opera prima, was conceived for both beginner and experienced chemists, physicists and material scientists interested in the amazing field of molecular organic materials. Some basic notions of solid-state physics and chemistry and of quantum mechanics are required, but the book is written trying to reach a broad multidisciplinary audience. 

The calculations of the molecular orbital energies e (which we employ in the same manner as is usual in the semiempirica] methods for organic molecules) and the evaluation of the coefficients of the atomic orbitals and sets of atomic orbitals in Table I in the final molecular orbital requires the solution of secular determinants (one for each irreducible representation) of the form 6 c =0, where Htj has its usual... 

One example of molecular transport requiring energy is the reuptake of neurotransmitter into its presynaptic neuron, as already mentioned above. In this case, the energy comes from linkage to an enzyme known as sodium-potassium ATPase (Fig. 2—9). An active transport pump is the term for this type of organization of two neurotransmitters, namely a transport carrier and an energy-providing system, which function as a team to accomplish transport of a molecule into the cell (Fig. 2—11). 

Those which do occur, their rates, and routes, depend on a complicated balance between the influences of many factors. Major among these are temperature, reaction time, other constituents in the environment, physical state, and molecular organization. Indeed, studies with model systems are invaluable, however, perfect simulation of the natural situation is practically impossible. The model and the real systems are still far apart and much more research is required with both to better understand the wide gap in between. 

In polymer crystallization the challenge is to identify and clarify the transformations by which chain molecules pass from a disordered, molten state to the ordered supra-molecular organization known as the semi-crystalline state. The subject is highly relevant in terms of both basic science and technology it is indeed clear that many modern applications require complete control of the structure and the morphology of polymers from macroscopic dimensions down to below the nanoscale. As a simple example, making the crystallites in a polymer liber equally oriented and reducing the number of chain folds (or hairpins) therein, usually turn out to be very favorable requisites for mechanical performance. 

The bulk properties of these block copolymers are also unusual and are not limited only to hydrophilic /hydrophobic systems(33). The only requirement is that the homopolymers of the A-block and B-block are not miscible, which holds for nearly all polymers deviating in chemical constitution. With the variation of the A-or B-block length, amorphous and structured microphase-separated systems occur, as summarized in Figure 12. The cubic, hexagonal, lamellar and the inverse structures are similar to the molecular organization of surfactants... 

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