Passive functional material

High responsiveness is often found in a stability edge of a physical property, or near a structural phase transition. The commonly referred phase transitions are thermally driven structural instabilities in which ionic displace-ments/rearrangements occur in the crystal structure at a critical temperature Tc- In other words, at the crystal structure of the high temperature phase becomes unstable and the ions will form a new crystal structure with lower crystal symmetry below Tc- As a signature of structural phase transitions, at least one physical quantity vanishes, or appears, or becomes discontinuous. Phase transitions can be induced by temperature or field changes, and are the origin of anomalous responses in many crystalline systems that are considered passive functional materials. 

As passive functional materials are based on anomalies, the criteria for good functional materials are very different from that for common materials. 

Proteins are usually separated into two distinct functional classes passive structural materials, which are built up from long fibers, and active components of cellular machinery in which the protein chains are arranged in small compact domains, as we have discussed in earlier chapters. In spite of their differences in structure and function, both these classes of proteins contain a helices and/or p sheets separated by regions of irregular structure. In most cases the fibrous proteins contain specific repetitive amino acid sequences that are necessary for their specific three-dimensional structure. 

Slentz et al. [133] described the effects of geometry (size, shape, and dimensions) on the performance of COMOSS. Vreeland and Barron [134] described the design of functional materials for genomic and proteomic analyses in NCE. The authors discussed different polymer chemistries for micro-channel surface passivation and improved DNA separation. 

The role of the solvent in inkjet ink is a vehicle with which to deliver a functional material to the surface of a substrate. The solvent is normally driven off by either passive drying or an active drying mechanism. 

The past two decades have brought advances in many sectors and led to a much larger number of ceramic products as well as completely new applications, particularly in the technical field. On an initiative within the German Ceramic Society (DKG), professors and other experts reviewed the classification of ceramic materials at the end of 2004. They decided that the structure had been too detailed in some cases whereas it would be sensible make additions in other fields. This applies particularly to electrical ceramics, where the differences between products with active and passive functions are now so great that these are now divided into two main groups. 

The safety-related features of the SCBs are inherently passive (i.e., they provide passive radioactive material confinement functions). Thus, the only functional requirement applicable to the SCBs is ... 

One requirement that is always added (or should be added) to the functional constraints such as conductivity, color, elasticity, and toughness is chemical and mechanical passivity. The material must not corrode, sinter, wear, or react irreversibly during use. High durability is a nontrivial design constraint but it is not always mentioned explicitly. 

H. Yang and P. H. Holloway, Efficient and photostable ZnS-Passivated CdS Mn luminescent nanocrystals. Advanced Functional Materials, 14(2), 152-156 (2004). 

The range of available active and passive optical materials is much too extensive to be described in detail and thus we will focus on the handful which are of broadest interest to optofluidics and separate them into those which are usable in the infrared and visible spectra. Within the former of these silicon specifically, silicon on insulator, tends to be the material of choice, primarily due to the well developed fabrication procedures, simplicity of integration with electronics and high refractive index. The underlying oxide layer serves to isolate the optical components but also as a convenient surface for biochemical functionalization. While generally compatible with most fluids, the conductivity of silicon can lead to some difficulties with electrically driven flow mechanisms such as electrokinetics. 

Fluorine can be handled using a variety of materials (100—103). Table 4 shows the corrosion rates of some of these as a function of temperature. System cleanliness and passivation ate critical to success. Materials such as nickel, Monel, aluminum, magnesium, copper, brass, stainless steel, and carbon steel ate commonly used. Mote information is available in the Hterature (20,104). 

Passive perimeter gas control systems are designed to alter the path of contaminant flow through the use of trenches or wells, and typically include synthetic flexible membrane liners (FMLs) and/or natural clays as containment materials. The membrane is held in place by a backfilled trench, the depth of which is determined by the distance to a limiting structure, such as groundwater or bedrock. A permeable trench installation functions to direct lateral migration to the surface, where the gases can be vented (if acceptable) or collected and conveyed to a treatment system (Figure 10a and 10b). 

Artificial organs that perform the physical and biochemical functions of the heart, hver, pancreas, or lung are one class of organ replacements. A rather different target of opportunity is the development of biologieal materials that play a more passive role in the body for example,... 

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