Specific Devices

Three major field studies have been conducted to determine the precision and accuracy of measurements made using lead-specific PXRF analyzers. The results of these studies are summarized in McKnight et al. (1989) and 

McKnight (1991). In addition, laboratory work was carried out by the National Institute of Standards and Technology (NIST) to understand further parameters thought to affect a measurement result. 

Since the detection level of a measurement procedure is limited by the precision of a blank measiuement (Currie, 1988), data were analyzed using a standard analysis of variance procedure to determine the precision of a blank measurement and the precision of lead concentration measurements near 1 mg/ cm. The estimated precision levels for a blank observation varied from 0.20-0.39 mg/cm for the four devices included in the study. For samples with lead-containing films, the precision varied from 0.26-0.49 mg/cm for the four devices. The variability was primarily associated with the substrate and replicate measurements within an observation. 

The procedure used in carrying out field studies to obtain estimates of precision and bias in the field measurements was the same for all three field studies. Three individual replicate PXRF measurements were made of a painted substrate, and a known area of the entire thickness of the paint film was removed for laboratory analysis. Three replicate PXRF measurements were also made of a corresponding bare substrate i.e., paint was removed by either chemieal stripping or scraping). The mean of a set of results, corrected for the 

The analysis to estimate method precision and bias was carried out by first finding the differences between the corresponding field SRF measurements and the laboratory measurement, then determining the mean and standard deviation of the difference distribution. For all three sets of field data, the estimate of the standard deviation of the difference distribution was about 0.6 mg/cm for measurements made over wood, plaster, and gypsum wallboard. The means of the difference distributions were slightly greater than zero, with a pooled estimate of 0.2 mg/cm for measurements over wood, plaster, and gypsum wall board. There were insufficient data points for other substrates, i.e., steel, to carry out a similar analysis. 

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Resistivity can be used as a guide to the role a material performs ia a specific device. Materials having high values, such as Teflon, serve an iasulation function (see Insulation, electrical). Metals such as silver and copper are excellent conductors. Organic compounds and polymers can cover a wide range of values, and the actual resistivity depends on exact composition. 

Physical devices (catalytic devices) for the nonchemical treatment of water and, more specifically, devices for scale prevention that employ magnetic fields have been part of the water treatment marketplace around the world since its earliest days. These devices include electronic, catalytic, electrostatic, and magnetic water treatments. There are also various other types of more recent alternative technologies (to chemical treatments) now available in the marketplace. These are being promoted for use in treating all types of MU water, FW, and BW. 

Different conformity assessment options are available, depending on the type of device and the level of associated risk. For lotv-risk devices, the manufacturer can make a declaration of conformity based solely on self-assessment, without the need for the involvement of a Notified Body. For all other devices Notified Bodies are required to perform one or more of the tasks outlined in Table 10.2. HIV and hepatitis tests and blood grouping tests represent the highest risk devices, as they are critical to ensuring the safety of blood and blood products. For example, a defective HIV test device could result in widespread infection in an unsuspecting population, whereas the detrimental effects ofan AIMD or a Class III device failure will just be confined to the individuals treated by the device. At this end of the risk spectrum. Notified Bodies are required to verify the applied quality system, the specific device design, and the... 

The 510(k) pre-market notification process is not as onerous as the pre-market approval procedure, as clearance to market a device is not based on actual assessment of the safety and effectiveness of the particular device in question. Instead, devices can be cleared on the basis that they are substantially equivalent to existing devices that have been recognised as safe and effective, or that they conform to specific device standards promulgated or recognised by the FDA. There are four procedural variations to the 510(k) notification process. 

However, if one desires a large sdngle-ciystal, then the methods needed to grow it differ considerably. This is the subject of this Chapter. We will examine crystal-growing methods and the equipment needed to do so. We will then examine the different t5q>e of ciystals used both as sensors and as the basis of specific devices used in the electronics industry. 

Intercenter consultation CDER, when lead Center, will consult with CDRH if CDER determines that a specific device is required as part of the NDA process. CDRH as lead center will consult with CDER if the device is intended for use with a marketed drug and the device creates a significant change in the intended use, mode of delivery (e.g., topical, IV), or dose/schedule of the drug. 

A drug whose labeling or promotional materials makes reference to a specific device or generic class of devices ordinarily remains a drug regulated by CDER. It may, however, also be subject to the combination products regulation. 

The curing of the adhesive bonding is carried out by heat and pressure specific device, vacuum bagging, autoclave, press... 

For the measurement of a single chemical entity, analyzers in the form of NDIR analyzers have been in use for decades for both industrial and environmental monitoring applications. These featnre one or more wavelength specific devices, usually optical filters, customized for the specific analyte, snch as CO, CO2, hydrocarbons, moisture, etc. This type of instrument is normally inexpensive (on average around 5000) and relatively easy to service, dependent on its design. This class of instrument is by far the most popular if one reviews the instrumentation market in terms of nsage and the number of analyzers installed. 

Another recommended test is to expose samples of propellant to testing on a vibration unit for weeks to months. The specific device we use is a model 100 HLA-D (horizontal) vibration fatigue tester made by All American Tool and Manufacturing Co. Samples, 1 liter in size, are tested, and temperatures can be adjusted easily from below 0° to above 100°F. 

The molecules shown in Figure. 7 represent nnlv a few of the materials that have been studied In LB film form. Nonetheless, a great deal more needs iti be done to tup (he vast wealth of opportunities available with organic systems. There will inevitahly be short-term opportunistic attempts aimed at discovering molecules for specific devices. However, there is a more pressing need for a systematic approach (hat will yield rules governing structure-property correlations, so us 10 enable scientists confidently to predict the molecular architecture of monolayer assemblies. See also Macromolecular Science. 

Questions of accuracy, reproducibility and durability have only been touched on slig htly. They depend critically on such factors as fabrication techniques, materials properties, etc. which are still in a state of development for the specific device designs. 

There must be a quality system in place appropriate to the specific device... 

Pressure relief device is the general term for a device designed to prevent pressure or vacuum from exceeding a predetermined value in a pressure vessel by the transfer of a fluid during emergency or abnormal pressure conditions. There are, however, different definitions for specific devices, their testing and their operating characteristics. 

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