Development of commercial instruments

Microcalorimetry has gained importance as one of the most reliable method for the study of gas-solid interactions due to the development of commercial instrumentation able to measure small heat quantities and also the adsorbed amounts. There are basically three types of calorimeters sensitive enough (i.e., microcalorimeters) to measure differential heats of adsorption of simple gas molecules on powdered solids isoperibol calorimeters [131,132], constant temperature calorimeters [133], and heat-flow calorimeters [134,135]. During the early days of adsorption calorimetry, the most widely used calorimeters were of the isoperibol type [136-138] and their use in heterogeneous catalysis has been discussed in [134]. Many of these calorimeters consist of an inner vessel that is imperfectly insulated from its surroundings, the latter usually maintained at a constant temperature. These calorimeters usually do not have high resolution or accuracy. 

Data Acquisition, Storage, and Display. Fourier-transform spectrometers require access to an on-line computer in order to permit rapid transformation of interferograms to spectra, and, in fact, the development of commercial instruments was in large... 

To access the energetic heterogeneity of surface, small doses of probe gas (typically < 10 ttmol g ) have to be added successively on the solid to saturate active sites progressively. Corresponding heats range from 100 to 1000 mJ, and require few hours for being evolved. Since the development of commercial instrumentation able... 

For it to be applied more extensively at the clinical level, one needs to develop standardized commercial instrumentation and its utility has to be demonstrated in more controlled and rigorous pre-clinical and clinical studies in terms of the accepted surgical norms in North America and Western Europe. 

The instrument constant B can be determined by measuring the t in two fluids of known density. Air and water are used by most workers (22). In our laboratory we used seawater of known conductivity and pure water to calibrate our vibrating flow systems (53). The system gives accurate densities in dilute solutions, however, care must be taken when using the system in concentrated solutions or in solutions with large viscosities. The development of commercial flow densimeters has caused a rapid increase in the output of density measurements of solutions. Desnoyers, Jolicoeur and coworkers (54-69) have used this system to measure the densities of numerous electrolyte solutions. We have used the system to study the densities of electrolyte mixtures and natural waters (53,70-81). We routinely take our system to sea on oceanographic cruises (79) and find the system to perform very well on a rocking ship. 

The rotational relaxation of DNA from 1 to 150 ns is due mainly to Brownian torsional (twisting) deformations of the elastic filament. Partial relaxation of the FPA on a 30-ns time scale was observed and qualitatively attributed to torsional deformations already in 1970.(15) However, our quantitative understanding of DNA motions in the 0- to 150-ns time range has come from more accurate time-resolved measurements of the FPA in conjunction with new theory and has developed entirely since 1979. In that year, the first theoretical treatments of FPA relaxation by spontaneous torsional deformations appeared. 16 171 and the first commercial synch-pump dye laser systems were delivered. Experimental confirmation of the predicted FPA decay function and determination of the torsional rigidity of DNA were first reported in 1980.(18) Other labs 19 21" subsequently reported similar results, although their anisotropy formulas were not entirely correct, and they did not so rigorously test the predicted decay function or attempt to fit likely alternatives. The development of new instrumentation, new data analysis techniques, and new theory and their application to different DNAs in various circumstances have continued to advance this field up to the present time. 

Interest in the use of calorimetry as a routine diagnostic or analysis tool has gained significant momentum only in the last 50 years. This interest has lead to the development of popular procedures such as differential thermal analysis (DTA) and differential scanning calorimetry (DSC). A wide variety of solution calorimetric techniques exist today. These techniques include thermometric titration, injection and flow emhalpimetry. The major growth of commercial instrumentation for calorimetry has occurred to address applications in routine analysis and the rapid characLerizaiion of materials. 

Laser diffraction is the most commonly used instrumental method for determining the droplet size distribution of emulsions. The possibility of using laser diffraction for this purpose was realized many years ago (van der Hulst, 1957 Kerker, 1969 Bohren and Huffman, 1983). Nevertheless, it is only the rapid advances in electronic components and computers that have occurred during the past decade or so that has led to the development of commercial analytical instruments that are specifically designed for particle size characterization. These instruments are simple to use, generate precise data, and rapidly provide full particle size distributions. It is for this reason that they have largely replaced the more time-consuming and laborious optical and electron microscopy techniques. 

The determination of the thickness of the layers of fat and lean tissue in animal flesh is the most popular use of ultrasound in the food industry at present [5,6]. In fact there are over a hundred references pertaining to this application of ultrasound in the Food Science and Technology Abstracts (1969-1993). In contrast to most other applications of ultrasound in the food industry, which have rarely developed further than use in the laboratory, there are a number of commercial instruments available for grading meat quality [6, 30-32]. This application is based on measurement of time intervals between ultrasonic pulses reflected from boundaries between layers of fat, lean tissue and bone. Ultrasonic techniques have the advantage that they are fairly cheap, easy to operate and give predictions of meat quality of live animals. Other examples of thickness determinations include liquid levels in cans or tanks, thickness of coatings on confectioneries, egg shell thickness. 

In fact, the simple detection device used in the laboratory was unable to detect the exothermal reaction At laboratory scale, the heat exchange area is larger by about two orders of magnitude (see Section 2.4.1.2), compared to plant scale. Hence the heat of reaction could be removed without detectable temperature difference, whereas at plant scale the same exotherm could not be mastered. This incident enhanced the necessity of a reaction calorimeter and promoted the development of the instrument, which was under development at this time by Regenass [1], Later, it became a commercial device (RC1). 

Chemists only began to use the technique routinely when commercial IR spectrometers had been developed.223 226 Three wartime research programmes created the initial demand, and provided the impetus for the production of commercial instruments. These were the US synthetic rubber programme,227 the British project to identify hydrocarbons in fuels from enemy aircraft,228 and the joint British-US penicillin programme. The mineral oil mull technique for obtaining the IR spectrum... 

One of the most important problems in the development of commercial biosensors is the stabilization of the enzymes used as the biological detection agents in the sensor. Although many different biosensors have been constructed, few have been developed in commercially successful instruments. The molecular parameters which influence the activity and stability of enzymes in die dry state, and when re-hydrated in an electrode surface, have been investigated A new and novel system has been developed, which appears to have broad application to the stabilization of enzymes. The use of this system to stabilize enzymes on electrodes is reported, together with a discussion on the mode of action of stabilization in general. 

The Human Genome Project has been a major driving force in the development of suitable instruments and methods for genome analysis. The companies that can identify genes that will be useful for drug discovery will reap the harvest in terms of new therapeutic agents and therapeutic approaches and commercial success in the future. 

Application of x-ray methods, either diffraction or absorption, to the development of commercial catalysts still relies predominantly on two approaches. In one approach, a real commercial material is treated under real test conditions and then characterized following transfer of the used material to the appropriate instrument. A second approach attempts to recreate some critical aspect of the catalyst s reaction environment in an in situ reactor attached to the appropriate instrument, but uses a model catalyst. Considerable opportunity exists in the careful melding of these two approaches so that real catalysts are treated under real conditions and are measured without intervening exposure to ambient. Only under such well controlled conditions can we hope to extract the maximum amount of information from x-ray based measurements. 

Tt is well-known that Werner determined the structure of a number of metal complexes by skillfully combining his famous coordination theory with chemical methods (30). Modern physico-chemical methods such as x-ray diffraction and infrared spectroscopy, used in the study of Werner complexes, have paralleled the development of these techniques. The results of these investigations have not only confirmed the validity of Werner s coordination theory but have also provided more detailed structural and bonding information. In early 1932, Damaschun (13) measured the Raman spectra of seven complex ions, such as [Cu(NH3)4]" and [Zn(CN)4j and these may be the first vibrational spectra ever obtained for Werner complexes. In these early days, vibrational spectra were mainly observed as Raman spectra because they were technically much easier to obtain than infrared spectra. In 1939, Wilson 35, 36) developed a new theory, the GF method," which enabled him to analyze the normal vibrations of complex molecules. This theoretical revolution, coupled with rapid developments of commercial infrared and Raman instruments after World War II, ushered in the most fruitful period in the history of vibrational studies of inorganic and coordination compounds. 

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