Refinement alternatives

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 alleviate or minimize potential pain, suffering, and distress, and which enhance animal well-being [5], Scientists should try to refine their experiments, improving the care and treatment of laboratory animals to minimize any possible pain and suffering experienced by the animals which have to be used. Refinement alternatives include ... 

Reduction, Replacement, and Refinement alternatives are also important in human research and the Three Rs should be considered as a principle guiding this area too. The possibilities of extending the principle of the Three Rs to human experiments are presently being evaluated as part of the objectives of BioSim - an EU Network of Excellence in Biosimulation [15]. 

PROCHECKcan be downloaded from the following web site http //www.biochenL ucl.ac.uk/ roman/procheckyprocheck.html. To run PROCHECK, one simply types procheck mycoordinates.pdb resolution limit , where mycoordinates.pdb should contain coordinates of your refined protein structure in standard Protein Data Bank (PDB) format, and resolutionjimit should correspond to the high resolution limit of the data (in A) used in the refinement. Alternatively, one can submit coordinates to either of two websites the SAVS server or the PDB validation server (www.deposit.pdb.org/validate/). For additional information, consult the PROCHECK manual www.biochem.ucl.ac.uk/ roman/procheck/manual/. 

It is important to note that there is a clear and distinct difference between the refinement of individual dtematives, or optimization step of analysis, and the evaluation and interpretation of the sets of refined alternatives that result from the analysis step. In some few cases, refinement or optimization of individual alternative decision policies may not be needed in the analysis step. More than one alternative course of action or decision must be available if there is but a single policy alternative, then there really is no decision to be taken at aU. Evaluation of alternatives is always needed. It is especially important to avoid a large number of cognitive biases in evaluation and decision making. Clearly, the efforts involved in the interpretation step of evaluation and decision making interact most strongly with the efforts in the other steps of the systems process. A number of methods for evaluation and choice making are of importance. A few wUl be described briefly here. 

Low temperature filtration (qv) is a common final refining step to remove paraffin wax in order to lower the pour point of the oil (14). As an alternative to traditional filtration aided by a propane or methyl ethyl ketone solvent, catalytic hydrodewaxing cracks the wax molecules which are then removed as lower boiling products. Finished lubricating oils are then made by blending these refined stocks to the desired viscosity, followed by introducing additives needed to provide the required performance. Table 3 Usts properties of typical commercial petroleum oils. Methods for measuring these properties are available from the ASTM (10). 

S. E. Housh and V. Petrovich, "Magnesium Refining A Fluxless Alternative," Society of Automotive Engineers Internationa/ Congress and Exposition Paper 920071, Detroit, Mich., 1992. 

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

A ruthenium-based catalyst is used but low yields resulting from unexpected side reactions are stiU a problem. Refinement of alternative route ammonia manufacture and advances in genetic engineering, allowing a wider range of plant life to fix nitrogen in situ should provide assurance for long term world food needs. 

In the Sulser-MWB process the naphthalene fractions produced by the crystallisation process are stored in tanks and fed alternately into the crystalliser. The crystalliser contains around 1100 cooling tubes of 25-mm diameter, through which the naphthalene fraction passes downward in turbulent flow and pardy crystallises out on the tube walls. The residual melt is recycled and pumped into a storage tank at the end of the crystallisation process. The crystals that have been deposited on the tube walls are then pardy melted for further purification. Following the removal of the drained Hquid, the purified naphthalene is melted. Four to six crystallisation stages are required to obtain refined naphthalene with a crystallisation point of 80°C, depending on the quaHty of the feedstock. The yield is typically between 88 and 94%, depending on the concentration of the feedstock fraction. 

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