Primitive examples

This section focuses on surface coatings and design for orthopaedic and dental implants. For implanted materials, both mammalian cell—material and bacterial cell-material interactions are important. For the former, active cell—material adhesion is preferred because it may promote tissue integration with the implant or scaffold materials. For the latter, nonadhesion is preferred because bacterial attachment may lead to infection. 

Both mammalian cell—material interactions and bacterial adhesion are affected by various chemical and physical factors on the material surface. These factors include the surface biochemistry, surface charge, surface hydrophobicity, surface roughness/ topography, surface porosity, surface crystaUinity and surface stiffness. All of these will be discussed as follows. 

To promote mammalian cell—material interactions, chemical and biochemical surface modifications of the materials can be used. These include inducing immobilized ECM proteins on the implant surfaces and applying CaP and so on. 

For example, hydroxyapatite (HA), a typical CaP, is an osteoconductive material that has been shown to promote osteoblast adhesion, and which has been widely used as a coating for orthopaedic and dental implants. However, the loss of ELA coating owing to delamination leads to micromotion of the implant and increased fretting and wear debris particles, which may cause failure of the implant. Therefore, it has been proposed to combine HA (a relatively insoluble calcium ceramic) and tricalcium 

In addition, other coatings such as titanium dioxide layers can promote 

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High vacuum technique (h.v.t.) is one of several types of experimental technique which can be employed to obtain a controlled experimental environment. The most usual reason for wanting this is the necessity to exclude oxygen and/or water and, less commonly, carbon dioxide from the reaction being studied. Perhaps the most primitive example of creating a controlled environment is the use of a soda-lime tube to protect a store of sodium hydroxide from the ingress of carbon dioxide. 

Among the structural factors that should be controlled in polymer syntheses (Fig. 1, Section I), perhaps the least exploited is the sequence of constitutional repeat units along a polymer main chain. We have already discussed the syntheses of block copolymers, where two or more homopolymer segments are connected, such as AAAAA-BBBBB- -, which is among the most primitive examples of sequence control in synthetic polymers. 

Even more simple constructs such as Art is art, or A dog is a dog, or A dog is not a dog might be considered primitive examples of recursive definitions. Sometimes the term self-referential is used when referring to these constructs. 

Carbonaceous chondrites are the second most abundant subset of chondritic meteorites and are thought to be some of the most primitive examples of solid materials from our early solar system because they contain (Klemperer 2006) ... 

Pneumatics is derived from Latin meaning pertaining to air. The blacksmith s bellows pumping a fire is a primitive example. Windmills in twelfth century central Europe exhibited the technology s first large-scale possibility. Development was dependent on discoveries made in the seventeenth and eighteenth centuries about gas properties, especially how... 

This is perhaps the oldest and most primitive example of a sequential or combinational test. When the product complexity exceeds the capacity of a fixture design to solve the test requirement with a single fixture, it is possible to divide the test responsibility among multiple fixtures. The flip test method of dual-side access described earher is one example of this. More typically, the test department has dual-side-access equipment, but the density of test sites exceeds the capability of the fixture and/or test system. 

It is often the case that a reaction enthalpy is needed but is not available in tables of data. Now the fact that enthalpy is a state function comes in handy, because it implies that we can construct the required reaction enthalpy from the reaction enthalpies of known reactions. We have already seen a primitive example when we calculated the enthalpy of sublimation from the sum of the enthalpies of fusion and vaporization. The only difference is that we now apply the technique to a sequence of chemical reactions. The procedure is summarized by Hess s law, which in its modern form is ... 

The Hiickel method is a very primitive example of a semi-empirical method in which various integrals are set equal to either a or p and treated as empirical parameters overlap integrals are ignored. The removal of the restriction of the Hiickel method to planar hydrocarbon systems was achieved with the introduction of the extended Hiickel theory (EHT) in about 1963. In heteroatomic non-planar systems (such as d-metal complexes) the separation of orbitals into k and a is no longer appropriate and each type of atom has a different value of Hu (which in Hiickel theory is set equal to a for all atoms). In this approximation, the overlap integrals are not set equal to zero but ue cdculated expKdtly. Furthermore, the Hjk, which in Hiickel theory are set equal to p, in EHT are made proportional to the overlap integral between the orbitals J and K. 

The first, primitive, example is represented in the EuNiGe type (the total unit cell contains 12 atoms). Figure 202 shows the three-dimensional arrangement of the filled and unfilled, half-substituted upon corners, trigonal prisms [NiEujGcj] and [hole EujGcj],... 

The Wood notation ean be generalized somewhat fiirther, by adding either the prefix e for eentred, or the prefix p for primitive. For instanee, one may have a e (2 x 2) unit eell or a p(2 x 2) unit eell, the latter often abbreviated to (2 x 2) beeause it is identieal to it. In a eentred unit eell, the eentre of the eell is an exaet eopy of the eomers of the eell this makes the eell non-primitive, i.e. it is no longer the smallest eell that, when repeated periodieally aeross the surfaee, generates the entire surfaee stnieture. Nonetheless, the eentred notation is often used beeause it ean be quite eonvenient, as the next example will illustrate. 

After aluminium, iron is the most abundant metal and the fourth most abundant of all the elements it occurs chiefly as oxides (for example haematite (FCjO,), magnetite (lodestonej (FC3O4) and as iron pyrites FeSj- Free iron is found in meteorites, and it is probable that primitive man used this source of iron for tools and weapons. The extraction of iron began several thousand years ago, and it is still the most important metal in everyday life because of its abundance and cheapness, and its ability to be cast, drawn and forged for a variety of uses. 

The functions put into the determinant do not need to be individual GTO functions, called Gaussian primitives. They can be a weighted sum of basis functions on the same atom or different atoms. Sums of functions on the same atom are often used to make the calculation run faster, as discussed in Chapter 10. Sums of basis functions on different atoms are used to give the orbital a particular symmetry. For example, a water molecule with symmetry will have orbitals that transform as A, A2, B, B2, which are the irreducible representations of the C2t point group. The resulting orbitals that use functions from multiple atoms are called molecular orbitals. This is done to make the calculation run much faster. Any overlap integral over orbitals of different symmetry does not need to be computed because it is zero by symmetry. 

Many basis sets are just identihed by the author s surname and the number of primitive functions. Some examples of this are the Huzinaga, Dunning, and Duijneveldt basis sets. For example, D95 and D95V are basis sets created by Dunning with nine s primitives and hve p primitives. The V implies one particular contraction scheme for the valence orbitals. Another example would be a basis set listed as Duijneveldt 13s8p . 

In order to describe the number of primitives and contractions more directly, the notation (6s,5p) (ls,3p) or (6s,5p)/(ls,3p) is sometimes used. This example indicates that six s primitives and hve p primitives are contracted into one s contraction and three p contractions. Thus, this might be a description of the 6—311G basis set. However, this notation is not precise enough to tell whether the three p contractions consist of three, one, and one primitives or two, two, and one primitives. The notation (6,311) or (6,221) is used to distinguish these cases. Some authors use round parentheses ( ) to denote the number of primitives and square brackets [ ] to denote the number of contractions. 

Protected-Membrane Roofs. Primitive roofs coveted with earth and sod over sloping wood decks shingled with bark were early examples of protected-membrane roofs (PMRs). Grass and earth provided iasulation and protected the shingled deck from inclement weather. 

Catalyst design is in a primitive stage. There are hardly any examples of tme design of catalysts (42). However, development of improved catalysts has been guided successfully in instances when the central issues were the interplay of mass transport and reaction. An example is catalysts used for hydroprocessing of heavy fossil fuels. 

One of the reasons the tribes of early history were nomadic was to move periodically away from the stench of the animal, vegetable, and human wastes they generated. When the tribesmen learned to use fire, they used it for millennia in a way that filled the air inside their living quarters with the products of incomplete combustion. Examples of this can still be seen today in some of fhe more primitive parts of the world. After its invention, the chimney removed the combustion products and cooking smells from the living quarters, but for centuries the open fire in the fireplace caused its emission to be smoky. In ad 61 the Roman philosopher Seneca reported thus on conditions in Rome ... 

The equations are presented in their primitive form to keep them more universal. Consistent units must be used, as appropriate, at the time of application. The example problems will include conversion values for the units presented. The symbol g will be used for the universal gravity constant to maintain open form to the units. 

When calculating the primitive ROI, it s best to establish a criterion. For example, one acceptable ROI calculation is to take an average benefit over 3 to 5 years and divide that by the initial cost to the investment. Another calculation basis, used by the U.S. DOE (Department of Energy) for P2 assessments is as follows ... 

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