Temperature measurement recent applications

Recent applications of relaxation dispersion measurements to concrete or cement-based materials are promising for characterizing reactive nanopor-ous materials, the structure of which may evolve over time (75-78). The MRD profiles have provided, for the first time, a direct means for characterizing the specific surface area, Sp, of a hydrated cement-based material (79), without exposing the sample to extremes of temperature or pressure (80-83). The interest in such a surface area is to provide information on the microsctruc-ture and its impact on macroscopic or structural properties. The method is based on a clear separation of surface and bulk contributions of the overall... 

VI. Recent Applications of Modern Temperature Measurement Methods in... 

VI. RECENT APPLICATIONS OF MODERN TEMPERATURE MEASUREMENT METHODS IN BIOCHEMISTRY... 

Finally, we mention several current applications somewhat outside of biochemistry in the usual sense. Thermography has slowly been coming to the fore. Many of the problems associated with the analysis of thermograms were treated at the Fifth International Symposium on Temperature (Plumb, 1972) in 1972 and new applications were discussed at the Sixth Symposium (Schooley, 1982) in 1982. Of perhaps more current interest is the greatly expanded interest in temperature measurement in hyperthermia and hypothermia. A recent New York Academy of Sciences conference has done an excellent job of reviewing this (Ann. N.Y. Acad., 1980). Cetas also wrote a general review of thermometry in this field (Cetas, 1968). Perhaps the most exciting new method in thermometry is that of optical fluorescence, which we described earlier. Catheters, whole-body scanners, etc., have been made for use with this method. At this point, 0.01°C is probably the least imprecision that can be obtained with the commercial instrument (Luxtron), with data obtained every 0.1 sec. Improvements are likely, however, as needs are made known to the company. 

Because the fabrication process is such an essential part of microfluidics, an overview of the principles underlying the microfabrication technology is presented. Pressure, flow, and temperature measurements are essential variables for characterizing fluid motion in any system. An important goal is the design and construction of self-contained microfluidic systems. Because of their small size, incorporation of pressure, flow, and temperature sensors directly on the microfluid system chip is highly desirable. There are relatively few examples where microfluidic systems have been constructed with these on-board sensors. There have been so many microsensor developments in recent years that it is only a matter of time before such systems will appear. Small-scale actuators to provide either open- or closed-loop control of the flow in microchannels are needed and these efforts are addressed. While experimental work on fluid flow itself in microscale structures is rather sparse, some results will be presented that emphasize the similarity and/or differences between macroscopic and microscopic flow of liquids. Although there are not many applications of... 

In the cryoscopic method, the freezing temperature of a solution is compared with that of the pure solvent. The polymer must be solvable in the solvent at flie freezing temperature and must not react with the solvent either ehemieally or physically. Difficulties may arise from limited solubility and from the formation of solid solutions on freezing. Application of cryoscopy to polymer solutions is not widespread in literature despite the simplicity of the required equipment. Cryoscopy was reviewed by Glover, who also discussed technical details and problems in concern with application to polymer solutions. A detailed review on cryometers and cryoscopic measurements for low-molar mass systems was recently made by Doucet. Cryometers are sold commercially, e.g., Knauer. Measurements of thermodynamic data are infrequent. Applications usually determine molar masses. Accurate data require precise temperature measurement and control as well as caution with the initiation of the crystallization process and the subsequent establishment of equilibrium (or steady state) conditions. High purity is required for the solvent and also for the solute. 

Ceramic sensors are devices that provide environmental feedback by transforming a nonelectrical input into an electrical output. The applications for which these devices are used are widely varied. A brief list includes the use of sensors to determine the concentration of various gases, such as oxygen and carbon monoxide, temperature measurement devices, and pressure, radiation, and humidity sensors. Sensors have also become widely used in automotive applications. In manufacturing, because of the increasing need for waste minimization, process control, and environmentally conscious manufacturing, the increasing emphasis on sensor use and development is likely to continue to expand. The use of feedback loops in conjunction with sensors for process control/optimization has also increased in recent years. 

The drop or mixing method is one of the oldest tools of the thermochemist. As no fundamental change has been made in recent years a detailed description is unnecessary. However, very high temperatures have now been studied by the application of modern methods of temperature measurement and heating. For example, Fredrickson et alJ have used... 

The first automatic control systems proposed date back to the early 1960s, and were based either on the barometric temperature measurement of the batch or on the monitoring of the resistivity of one or more sampled vials. Even if they had many limitations, and up to recent times were never really applied in industrial applications, especially those of the second kind, they introduced the concept of modem closed-loop control, and some control strategies that are still vahd (Nail and Gatlin, 1985 Jennings, 1999). 

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