Technological potential

Although several other early studies were conducted using Supercritical Fluids (SFs), also termed at that time as dense gases , this field did not receive the attention it deserved during the first half century after its discovery. Even then, the small number of investigators dedicated to further explore the scientific and technological potential of supercritical fluids concentrated then efforts on industrial rather than analytical applications (9, 10). 

Metals and semiconductors are electronic conductors in which an electric current is carried by delocalized electrons. A metallic conductor is an electronic conductor in which the electrical conductivity decreases as the temperature is raised. A semiconductor is an electronic conductor in which the electrical conductivity increases as the temperature is raised. In most cases, a metallic conductor has a much higher electrical conductivity than a semiconductor, but it is the temperature dependence of the conductivity that distinguishes the two types of conductors. An insulator does not conduct electricity. A superconductor is a solid that has zero resistance to an electric current. Some metals become superconductors at very low temperatures, at about 20 K or less, and some compounds also show superconductivity (see Box 5.2). High-temperature superconductors have enormous technological potential because they offer the prospect of more efficient power transmission and the generation of high magnetic fields for use in transport systems (Fig. 3.42). 

This increase in the flowability of fire retardant plastics melts compensates for lack of heat stability by providing the same technological potentialities as high processing heat stability using low temperature processing (Fig. 2). 

A few of the reactions carried out by the monooxygenase system of methanotrophic bacteria are summarized in Figure 2.9, and it is on account of this that methylotrophs have received attention for their technological potential (Lidstrom and Stirling 1990). An equally wide metabolic potential has also been demonstrated for cyclohexane monooxygenase, which has been shown to accomplish two broad types of reaction one in which formally nucleophilic oxygen reacts with the substrate, and... 

Although polyphosphazene chemistry is nearly 100 years old, the technological potential of this class of polymers is only now being realized. 

The early work in the field of conducting polymers was performed by physicists and hence the terminology employed by them has found its way into electrochemistry. Thus, the films conduct only when they are oxidised, suggesting that conduction is via positive carriers (i.e. holes) and the polymer is termed p-(for positive)-doped, which is merely a descriptive term for the conduction. However, it was quickly realised that if they are to fulfil their full technological potential, a full understanding of the conduction process is essential and this includes determining the identity of the carriers. 

In the years that followed, attempts were made to exploit the technological potential of the two properties of superconductivity ... 

Young, H., Rossiter, K., Wang, M., Miller, M. (1999) Characterization of Royal Gala apple aroma using electronic nose technology potential matirrity indicator. J. Agric. Food Chem. 47 5173-5177. 

Solitons are considered to be important defect states in these conjugated polymers (see Fig. 6.48). It has however been shown that correlation energy is the more important factor in giving rise to the energy gap in (CH) (Soos Ramasesha, 1983). Other polymers related to polyacetylene are polythiophene, polypyrrole, poly-phenylenesulphide, and polyparaphenylene (Section 3.3). Extensive measurements on doped polyacetylenes have been reported in the last five years and these materials, unlike other conducting polymers such as (SN), seem to have good technological potential. 

Interest in the field of nonlinear optics has grown tremendously in recent years. This is due, at least partially, to the technological potential of certain nonlinear optical effects for photonic based technologies. In addition, the responses generated through nonlinear optical interactions in molecules and materials are intimately related to molecular electronic structure as well as atomic and molecular arrangement in condensed states of matter. 

Since mesoporous materials contain pores from 2 nm upwards, these materials are not restricted to the catalysis of small molecules only, as is the case for zeolites. Therefore, mesoporous materials have great potential in catalytic/separation technology applications in the fine chemical and pharmaceutical industries. The first mesoporous materials were pure silicates and aluminosilicates. More recently, the addition of key metallic or molecular species into or onto the siliceous mesoporous framework, and the synthesis of various other mesoporous transition metal oxide materials, has extended their applications to very diverse areas of technology. Potential uses for mesoporous smart materials in sensors, solar cells, nanoelectrodes, optical devices, batteries, fuel cells and electrochromic devices, amongst other applications, have been suggested in the literature.11 51... 

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. 

The reader is also referred to other literature for a more comprehensive introduction to various aspects of optical nonlinearity and for more in-depth reviews of certain topics than can be covered in this review [2,3,5,24-87]. It is also suggested that the reader use these cited reviews to access literature not cited here. The literature on the topic of organic electro-optic materials now stands at many thousands of papers. It is unrealistic to attempt to even cite this entire body of literature here let alone discuss in depth all of the salient features of research into organic electro-optic materials. It is hoped that a readable overview of poled polymer electro-optic materials is provided in the following sections and that insight is provided both into the technological potential and problems associated with these materials. 

Even though Ziegler catalysts have been known for almost half a century, rare earth metals (Ln), particularly neodymium (Nd)-based Ziegler catalyst systems, only came into the focus of industrial and academic research well after the large scale application of titanium, cobalt and nickel catalyst systems. As a direct consequence of the late recognition of the technological potential of rare earth metal Ziegler catalysts, these systems have attracted much attention. 

Nanowire systems have attracted a great deal of attention recently due to their technological potential They are of fundamental interest because they exhibit unique quantum confinement effects. In this article, advances in the fabrication of nanowires via template-assisted and laser-assisted approaches are reviewed. The structure and characteristics of different nanowire systems are discussed. To understand and predict the unusual properties of nanowires, we have developed a generalized theoretical model for the band structure of these onedimensional systems. A unique semimetal-semiconductor transition that occurs in bismuth nanowires is described. Transport measurements on bismuth and antimony nanowires illustrate that these novel materials are very different from their bulk counterparts. A transport... 

Based on these encouraging achievements, in the last five or six years, the interest of the researchers shifted from easy-to-compute polymer penetrant systems to those which have interesting technological potentials in such fields as gas barriers (114— 117), gas or liquid separation processes (118-121), molded objects (packagings for example) (122) or swelling of polymers by solvents (123-126). 

Materials which exhibit both magnetic and electrical ordering have attracted great interest in the past few years, partly because of their technological potential. 

Although tin complexes exhibit very good activity for vegetable oil alcoholysis, their technological potential in homogeneous conditions is very poor. Indeed, as long as these complexes remain dissolved in the reaction medium,... 

So, our investigations allow us to establish the correlation between physico-chemical properties of the crystallization media (capillary properties of the diamond-metal melt interface, carbon supersaturation in the melt with respect to diamond) and adsorption-structure and energy proreties of the produced diamond powders. Our findings permit us to extend scientific and technological potentialities for production of diamond grinding and micron powders having unique properties. 

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