Replacement alternatives

The use of calcium carbonate in thermosets continues to grow as these plastics replace alternative materials, especially in automotive appHcations. Increased loadings of calcium carbonate in thermosets reduce cost and provide better surface characteristics. 

The Lewis structure of borazine is nearly identical to that of benzene. It is obtained by replacing alternating C atoms in the benzene structure with B and N as shown. The orbitals at each B and N atom are sp2 hybridized. 

Fig. 1.14. Evacuablecell for UV-visible spectra. This cell is evacuated and then flushed through an inert-gas inlet attached to the O-ring joint. The Teflon stem of the valve is removed under flush, solutions are introduced through this Opening, and then tipped over into the cuvette after the valve stem has been replaced. Alternatively, condensable solvents and solutes may be condensed into the reservoir on a vacuum line.

In the context of laboratory animal use, alternative methods include all procedures that can completely replace the need for animals (replacement alternatives), reduce the number of animals... 

The concept of the three Rs (replacement, reduction, and refinement), attributed to Russell and Burch (1959), is now enshrined in the laws of many countries and in Directive 86/609/EEC on the protection of animals used for experimental and other scientific purposes (European Commission, 1986). This directive requires that replacement alternatives, reduction alternatives, and refinement alternatives should be used wherever and whenever possible. 

These refer to methods which permit a given purpose to be achieved without conducting experiments or other scientific procedures on animals [5]. A scientist s long-term aim should be to replace all experiments on living animals through the development and use of suitable non-animal methods. Replacement alternatives include ... 

Water or sewer line decontamination In situ cleaning replacement alternative supply... 

One trap which must be avoided is to use animal test data as the gold standard to be matched by nonanimal, replacement alternative tests. If the animal tests themselves are not sufficiently relevant and reliable, how can the data they provide be used in the validation of human-based (by definition, more relevant) tests Sadly, this trap is often laid, not least by... 

The mechanisms of dolomitisation are not well understood [2.3, 2.4], but undoubtedly involve passage of sea water through the pores of the limestone over long periods. The dissolved magnesium is able to replace alternate calcium ions in the crystal lattice, because dolomite is a little more stable than calcite. Moreover, as the crystal density of dolomite is about 10 % higher than that of calcite, dolom-itization is accompanied by an increase of porosity. This facilitates further dolomitisation. It also raises the capacity of a deposit to act as a reservoir for oil, water, or gas. 

Darnell (1978) has reported the formation of a carbon-oxygen compound R2CO with rare earths Ce, Sm, Eu, Gd, Tm and Yb by heating the metals in a quartz tube with a stoichiometric amount of CO to 800°C. The crystal structure of these compounds was observed to be similar to the NaCl structure of the corresponding nitrides (the nitrogen in the metal nitrides being replaced alternately by carbon and oxygen). Only traces of the sesquioxide phase were detected by X-ray diffraction. 

The structure of BPO4 is derived from that of Si02 by replacing alternate Si atoms by B or P atoms. Explain how this description relates to the isoelectronic principle. 

The structured boehmite product provides essentially equivalent film antiblock and film clarity properties as antiblocking quality silica, when both are employed in a 1 mil blown LDPE film at a 0.25% loading level. This equivalent film performance thereby offers the plastics compounder a low crystalline silica, drop-in replacement alternative. ... 

---