Crystallization data acquisition

The SIMULAR, developed by Hazard Evaluation Laboratory Ltd., is a chemical reactor control and data acquisition system. It can also perform calorimetry measurements and be employed to investigate chemical reaction and unit operations such as mixing, blending, crystallization, and distillation. Ligure 12-24 shows a schematic detail of the SIMULAR, and Ligure 12-25 illustrates the SIMULAR reaction calorimeter with computer controlled solids addition. 

A benefit of the use of accelerometers is that they do not require a calibration program to ensure accuracy. However, they are susceptible to thermal damage. If sufficient heat radiates into the piezoelectric crystal, it can be damaged or destroyed. However, thermal damage is rare since data acquisition time is relatively short (i.e. less than thirty seconds) using temporary mounting techniques. 

Although simple intensity correction techniques can be used to develop very adequate XRPD methods of quantitative analysis, the introduction of more sophisticated data acquisition and handling techniques can greatly improve the quality of the developed method. For instance, improvement of the powder pattern quality through the use of the Rietveld method has been used to evaluate mixtures of two anhydrous polymorphs of carbamazepine and the dihydrate solvatomorph [43]. The method of whole pattern analysis developed by Rietveld [44] has found widespread use in crystal structure refinement and in the quantitative analysis of complex mixtures. Using this approach, the detection of analyte species was possible even when their concentration was less than 1% in the sample matrix. It was reported that good quantitation of analytes could be obtained in complex mixtures even without the requirement of calibration curves. 

A fully automated protein crystallography beamline at a third-generation synchrotron source can screen several hundred crystals daily. Automatic evaluation of the diffraction images to ascertain crystal quality is, therefore, a critical step for high-throughput data acquisition. Evaluation of each image requires software that mimics the traditional visual assessment of crystal quality. 

Ward et ai, 1988 Jones et al., 1987). A crystallization plate, on which the protein solution is sandwiched between glass plates, was designed for the automated visual inspection of crystallization experiments (Jones et al., 1987). Photographs of crystals first produced % an automated instrument together with some reproduced from the literature a shown in Fig. 4E-H. As a complement to the automated setup of crystallization experiments, a database system for recording crystallization results (Fig. 10) has been developed to facilitate data acquisition and to aid in the design of subsequent experiments. 

Our processing is much better now, and we can get the properties right so they re reproducible. We know enough about the process and the conditions, and so we can always get to reasonable quality with 95 K materials. We have a lot more instrumentation now to do things that we had done by just pure happenstance. We ve put eyes into the ceramists methods. We put a resistor, say, into it so that as you go up and down the temperature scale, you monitor the differences as you see them, and that s called differential thermal analysis. Once the ceramists make the stuff, we go to an electron microscope and see what that little glitch means insofar as the microstructure is concerned. We go to the data acquisition system, the computer, and find out where the atoms are, what the crystal structure is, and we ask, Did the electrons go the wrong way ... 

Dynamic crystallization under precise control of shear and temperature was studied in a prototype apparatus specially developed. The whole cell, similar to a Couette viscometer, was made out of glass. The inner cylinder rotated at a controlled speed, CO, while the outer wall was fixed. A double-mantel with a circulation of water allowed precise control of the temperature. Temperature of cocoa butter in the cell was measured with a chromel-alumel thermocouple. Measures were recorded with a data acquisition system. Shear rate imposed to cocoa butter in the system could be estimated from the rotation speed of the inner cylinder, assuming that the fluid is Newtonian and incompressible. There is no normal speed, only tangential speed. The shear rate, y> in the specimen is a single function of the radiu. In the rest of this work, shear in the cell was characterized by its average value, y, calculated by integration over the cell thickness (7). 

The second stage is data acquisition. This stage is initiated when the operator starts the instrument. For the DSC operation, data are collected on three analog channels corresponding to the two pens (Y and Y1) on the DuPont 990 console and to the temperature axis. Data are collected on a time base using the microcomputer s crystal based real-time prograimable clock. 

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