Tools of the Trade

Scientists can fabricate microelectromechanical devices such as the cantilever above, which is a beam of silicon anchored at one end. The beam has a resonant vibrational frequency near 13 X 106 hertz (13 MHz) when stimulated with a piezoelectric vibrator. (A piezoelectric crystal, such as quartz, is one whose dimensions change in response to an electric field.) When 93 attograms (93 X 10, 8g) of an organic compound bind to the gold dot near the end of the cantilever, the vibrational frequency decreases by 3.5 kHz because of the extra mass on the beam. The minimum mass that can be detected is estimated as 0.4 attogram. 

Microcantilevers can be coated with DNA or antibodies to respond to biological molecules or even a single virus.1-2-3 Bound material can be detected by the change in resonant frequency, as above, or by measuring nanometer-scale static bending, shown at the left, caused by stress on the surface of the cantilever when molecules bind. 

Binding of molecules to one side creates surface stress that bends the cantilever. 

Chemical experimentation, like driving a car or operating a household, creates hazards. The primary safety rule is to familiarize yourself with the hazards and then to do nothing that you 

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To meet this requirement for documented procedures you will need two types of procedure procedures which provide for the necessary inspections and tests to be planned and carried out at the appropriate stage of the process and procedures for carrying out the specific inspections and tests. However, this is not to say that you need to document how you conduct every type of inspection or test. You only need procedures which define how inspections and tests are to be performed when the lack of them will adversely affect the result. Where the inspection and test methods are no more than using the tools of the trade, no procedures will be necessary providing the acceptance criteria are specified in a specification, drawing, or other such document. 

There are two categories of equipment which determine the selection of equipment general-purpose and special-to-type equipment. It should not be necessary to specify all the general-purpose equipment needed to perform basic measurements, which would be expected to be known by appropriately trained personnel. You should not need to tell an inspector or tester which micrometer, vernier caliper, voltmeter, or oscilloscope to use. These are the tools of the trade and they should select the tool which is capable of measuring the particular parameters with the accuracy and precision required. However, you will need to tell them which device to use if the measurement requires unusual equipment or the environmental conditions prevailing require that only equipment be selected that will operate in such an environment. In such cases the particular devices to be used should be specified in the test or inspection procedures. In order to demonstrate that you selected the appropriate device at some later date, you should consider recording the actual device used in the record of results. With mechanical devices this is not normally necessary because wear should be detected well in advance of there being a problem by periodic calibration. 

If a spectrum does not yield the definitive information that you require on inspection, there are many other tools of the trade that we can use to further elucidate structures. Broadly speaking, these fall into two categories - chemical techniques and instrumental techniques. 

Analytical procedure is a systems problem and the samphng, pretreatment, measurement, data collection and reduction, and final reporting all have to be considered in a fiilly automatic approach. Computerization is often considered to he synonymous with automation but, although microprocessor technology is certainly changing the face of automatic instrumentation and influences both the control aspects and the data reduction, computerization is only a part of automation. Computers should simply be considered as tools of the trade within the area of automation. 

Balogh, M. P. (2006). Spectral Interpretation, Part II Tools of the trade. LCGC 24 762-769. 

Since the time of alchemy those engaged in research have continually needed to further refine and define their basic experimental reagents, their scientific tools of the trade. The resulting progress... 

Wu, S. and Chappell, J. (2008) Metabolic engineering of natural products in plants tools of the trade and challenges for the future. Curr. Opin. BiotechnoL, 19,145-52. 

An algebraic expressionfor the pair-potentialfunctionU is one of the tools of the trade of the molecular scientist or engineer. The methods of statistical mechanics provide for its relation to both thennodynamicand transport properties. Shown in Fig. 16.1 are specific values for U and r that may appear as species-dependent parameters in a pair-potential function. 

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