Material optimisation

As a rule of thumb, given that a material fulfils all relevant functional demands, the material that has the lowest environmental impact should be chosen. This generally means that the product, or at least the material, has to be recyclable. 

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Even with all process parameters and material optimisations, it is usually not possible to reach acceptable levels of post-CMP planarity and therefore additional optimization of the wafer to be polished itself is needed [25]. The next section discusses several different optimization techniques. 

Bulk heterojunction device performance has improved by strides since the first reports of charge separation in bulk heterojunctions, with power conversion efficiencies that now approach 5% (Li et al., 2005 Reyes-Reyes et al, 2005 Kim et al, 2006a). Smdies have focused on varying the donor and acceptor materials, optimising the... 

Furthermore, metals present additional intrinsic properties, such as redox reversibility, magnetism and luminescence. It is, therefore, possible to take benefit from these peculiarities for the design of redox-controlled NLO switches as illustrated in this chapter or for the elaboration of materials combining two or more properties. This latter field of research is in its infancy but it is possible to anticipate many improvements in the future for the elaboration of multifunctional molecular material optimising simultaneously all the wonderful capacities of metals. 

Changes in the production process Replace hazardous raw materials Optimise reactions Consider alternative low-waste routes Eliminate leaks and spills Consider product substitution... 

Kinloch, A J., Fulmer Materials Optimiser, 2nd Edn, Section I.D.-J.b.5.1, Fulmer Research Institute Limited, Stoke Poges. 

Materials suitable as filter aids include diatomaceous earth, expanded perilitic rock, asbestos, ceUulose, nonactivated carbon, ashes, ground chalk, or mixtures of those materials. The amount of body feed is subject to optimisa tion, and the criterion for the optimisa tion depends on the purpose of the filtration. Maximum yield of filtrate per unit mass of filter aid is probably most common but longest cycle, fastest flow, or maximum utilisation of cake space are other criteria that requite a different rate of body feed addition. The tests to be carried out for such optimisation normally use laboratory or pilot-scale filters, and must include variation of the filtration parameters such as pressure or cake thickness in the optimisation. 

In electrolytic processes, the anode is the positive terminal through which electrons pass from the electrolyte. Anode design and selection of anode materials of constmction have traditionally been the result of an optimisation of anode cost and operating economics, in addition to being dependent on the requirements of the process. Most materials used in metal anode fabrication are characteristically expensive use has, however, been justified by enhanced performance and reduced operating cost. An additional consideration that has had increasing influence on selection of the appropriate anode is concern for the environment (see Electrochemical processing). 

Processing temperatures should not exceed 180°C, and the duration of time that the material is in the melt state should be kept to a minimum. At the end of a run the processing equipment should be purged with polyethylene. When blow moulding, the blow pin and mould should be at about 60°C to optimise crystallisation rates. Similarly, injection moulds are recommended to be held at 60 5 C. 

These kinds of maps and optimisation approaches represent impressive applications of the quantitative revolution to purposes in materials engineering. 

The advent of the integrated circuit and its foundry has now firmly integrated materials scientists into modern electronics, their function both to optimise production processes and to resolve problems. To cite Just one example, many materials scientists have worked on the problem of clectronugraiion in the thin metallic conductors built into integrated circuits, a process which eventually leads to short circuits and circuit breakdown. At high current densities, migrating electrons in... 

Co-design—(http //www.montell. com / montell/products/p-codesign.html) active involvement in product design to optimise the use of material and manufacturing resources. 

The expert tried to optimise the design of unbreakable crockery. First he wanted to find reasons for using ceramic as the main material in terms of desired properties. From this first step, he concluded that ceramic had some advantages over metals or composites. The expert made a sharp distinction between intrinsic and extrinsic properties. The choice of type of ceramics was not relevant becanse the desired properties are extrinsically determined. Thns relevant properties cannot be much influenced by the difference in bonding strength due to the different types of ions of the material. Consequently, the properties of ceramic crockery are not mnch inflnenced by the actual choice of ceramic material. Because of this, the expert did not inclnde the ionic stmcture in his reasoning. When he was asked why he did not nse this snb-microscopic level, he explained it was not necessary becanse this [the desired properly] is not imdeigoing influences at atomic level at all . 

Computer simulations therefore have several inter-related objectives. In the long term one would hope that molecular level simulations of structure and bonding in liquid crystal systems would become sufficiently predictive so as to remove the need for costly and time-consuming synthesis of many compounds in order to optimise certain properties. In this way, predictive simulations would become a routine tool in the design of new materials. Predictive, in this sense, refers to calculations without reference to experimental results. Such calculations are said to be from first principles or ab initio. As a step toward this goal, simulations of properties at the molecular level can be used to parametrise interaction potentials for use in the study of phase behaviour and condensed phase properties such as elastic constants, viscosities, molecular diffusion and reorientational motion with maximum specificity to real systems. Another role of ab initio computer simulation lies in its interaction... 

Jorgensen et al. has developed a series of united atom intermolecular potential functions based on multiple Monte Carlo simulations of small molecules [10-23]. Careful optimisation of these functions has been possible by fitting to the thermodynamic properties of the materials studied. Combining these OPLS functions (Optimised Potentials for Liquid Simulation) with the AMBER intramolecular force field provides a powerful united-atom force field [24] which has been used in bulk simulations of liquid crystals [25-27],... 

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. 

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