Factors in selection

The time needed to complete an analysis for a single sample is often fairly similar from method to method. This is somewhat misleading, however, because much of this time is spent preparing the solutions and equipment needed for the analysis. Once the solutions and equipment are in place, the number of samples that can be analyzed per hour differs substantially from method to method. This is a significant factor in selecting a method for laboratories that handle a high volume of samples. 

Time constraints ate an important factor in selecting nmr experiments. There are four parameters that affect the amount of instmment time requited for an experiment, A preparation delay of 1—3 times should be used. Too short a delay results in artifacts showing up in the 2-D spectmm whereas too long a delay wastes instmment time. The number of evolution times can be adjusted. This affects the F resolution. The acquisition time or number of data points in can be adjusted. This affects resolution in F. EinaHy, the number of scans per EID can be altered. This determines the SNR for the 2-D matrix. In general, a lower SNR is acceptable for 2-D than for 1-D studies. 

Cost is always a factor in selecting a component for a pyrotechnic composition, as is the water-attracting abiHty of a substance (hygroscopicity). In general, substances that attract water from the atmosphere are avoided in pyrotechnic formulations for a variety of reasons, thereby supporting the centuries-old adage, "Keep your powder dry."... 

The cost of a carrier, in addition to its satisfactory performance in dyeing, is often a considerable factor in selection. The rising cost of petroleum-derived chemicals is a factor in the price stmcture of carrier-active chemicals and most carriers, unfortunately, fall in this category. 

Many models have been proposed for adsorption and ion exchange equilibria. The most important factor in selecting a model from an engineering standpoint is to have an accurate mathematical description over the entire range of process conditions. It is usually fairly easy to obtain correcl capacities at selected points, but isotherm shape over the entire range is often a critical concern for a regenerable process. 

There are five major factors in selection of the size of a core for an application ... 

Successful recrystallization of an impure solid is usually a function of solvent selection. The ideal solvent, of course, dissolves a large amount of the compound at the boiling point but very little at a lower temperature. Such a solvent or solvent mixture must exist (one feels) for the compound at hand, but its identification may necessitate a laborious trial and error search. Solvent polarity and boiling point are probably the most important factors in selection. Benzhydrol, for example, is only slightly soluble in 30-60 petroleum ether at the boiling point but readily dissolves in 60-90° petroleum ether at the boiling point. 

The most important factors in selecting drill collar size are ... 

The following are the key factors in selecting a location, and these are discussed in more detail below ... 

The distinction between a simple part and a complex assembly is an important factor in selecting a temporary protective. The solvent-containing protectives may not be suited to treating assemblies, because ... 

Interconnect. Three-dimensional structures require interconnections between the various levels. This is achieved by small, high aspect-ratio holes that provide electrical contact. These holes include the contact fills which connect the semiconductor silicon area of the device to the first-level metal, and the via holes which connect the first level metal to the second and subsequent metal levels (see Fig. 13.1). The interconnect presents a major fabrication challenge since these high-aspect holes, which may be as small as 0.25 im across, must be completely filled with a diffusion barrier material (such as CVD titanium nitride) and a conductor metal such as CVD tungsten. The ability to fill the interconnects is a major factor in selecting a thin-film deposition process. 

If surgical intervention does not achieve satisfactory disease control, select subsequent appropriate pharmacologic therapy based on patient-specific factors. In selecting therapy, be sure to consider if the patient has any contraindications or allergies to therapies. 

The gangue constituents and their nature are sometimes determining factors in selection of a treatment process for beneficiation of oxide copper ores. Highly weathered ores usually contain a fairly large amount of slimes, which has a negative effect on the floatability of oxide copper minerals. Also, there is an appreciable difference in floatability between oxide minerals from carbonaceous and siliceous ores. 

Fourthly, ecological and economic issues have proved important factors in selection of species for genomic sequencing. The weed Arabidopsis is not only an important experimental species for plant biologists but also plants in general are of enormous importance to us. Getting the rice, Oryza, genome was driven by the commercial importance of this plant as a key component of the human diet. 

PCR instruments are available in different specifications from numerous companies. They now usually include a heated lid, which prevents evaporation of the sample and allows PCR amplification without mineral oil. Important factors in selecting the right instrument include ... 

Factors in selecting and applying commercial expls and blasting agents 6 F2... 

Salection of Commercial Explosives and Blasting Agents [From R.A. Dick, Factors in Selecting and Applying Commercial Explosives and Blasting Agents , USBurMines IC8405 (1968)]... 

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