Searle system

Fig. 7. Schematic representation of examples of test geometries used. Open systems channel, rotating disc (Hoyt 1972, 1986). Closed systems pipe flow, couette- or searle-systems (Kulicke 1986)...

Viscosities of liquids mixed with C02 have been measured in a high-pressure rotational viscometer, which works according to a Searle-system. The pressure influence on the viscosity of the pure liquid can be described with known correlations [9]. 

Viscometers are being increasingly used for accurate measurements on modern industrial paints, especially waterborne paints. Rotating viscometers with a concentric cylindrical geometry (Searle system. Fig. 9.1) are advantageous for paints. Precise thermostatic control is easily achieved because the outer cylinder does not rotate. The drive and torque sensor are combined to form a single unit with the rotating inner cylinder. 

Used for glass, sol-gels, blood, polymers, etc. The cup-and-bob types define the volume of sample to be sheared in a test cell. The torque needed to achieve a particular rotational speed is measured. The two geometries are known as the Couette or Searle systems the difference depends on whether the cup or bob rotates. The cup can be a cylinder. 

According to DIN 53018, simple rotational viscosimeter have a coaxial cylinder system with a cup (inner radius R ) and a cylinder with an outer radius Rj and a length h, that is lowered into the cup. For the Couette system, the outer cup is moved and the measurement of the torque T takes place at the inner cylinder. For the Searle system on the other hand, the inner cylinder is moved. 

Because of centrifugal forces in the Searle System, crosscurrents can arise, that are called Taylor vortices. Couette Systems on the other hand have the disadvantage that temperature control of the rotating outer cylinder is achieved only with complicated equipment. Most rotational viscosimeters are therefore built in the Searle Type. 

Furthermore, in Searle cylinder systems, secondary currents occur above certain Taylor numbers, resulting in greater power input than that resulting with Eq. (12). Comparison with experimentally determined Ne numbers shows that the laminar flow range in internally driven cylindrical stirrers in the range of radius ratios r2/ri= 1.05-2 is only valid for Taylor numbers Takrit= <400-200 [38]. Above Ta >Takritsecondary currents in the... 

The results presented here were found by investigations with a special cyUn-der system [45,48]. This system was constructed for an existing Searle viscosimeter (rotation of inner cylinder), such that the gap widths were large in relation to the reference floe diameter of the floccular system used, so that the formation of the floes and their disintegration in the cylinder system are not impaired. For this system, with r2 = 22 mm, rj = 20.04 mm, and Li = 60 mm (r2/ri > 1.098), the following Newton number relationships were determined from the experimental values collected by Reiter [38] for the Taylor number range of 400 < Ta < 3000 used here ... 

Figure 11 shows the reference floe diameter for viscometers as a function of shear stress and also the comparison with the results for stirred tanks. The stress was determined in the case of viscosimeters from Eq. (13) and impeller systems from Eqs. (2) and (4) using the maximum energy density according to Eq. (20). For r > 1 N/m (Ta > 2000), the disintegration performance produced by the flow in the viscosimeter with laminar flow of Taylor eddies is less than that in the turbulent flow of stirred tanks. Whereas in the stirred tank according to Eq. (4) and (16b) the particle diameter is inversely affected by the turbulent stress dp l/T, in viscosimeters it was found for r > 1.5 N/m, independently of the type (Searle or Couette), the dependency dp l/ pi (see Fig. 11). 

Microreservoir dissolution-controlled system in which microscopic spheres of drug reservoir are dispersed in a polymer matrix Nitrodisc (nitroglycerin Searle). 

N. L. Paddock and H. T. Searle The Sulfuric Acid Solvent System R. J. Gillespie and E. A. Robinson... 

With the general name of cyclohexylsulphamate, this sweetener was discovered in 1937 by Michael Sveda at the University of Illinois. The sodium salt is the most commonly used form. It is a white crystalline salt with good solubility. The relative sweetness of cyclamate is comparatively low, at approximately 35, in most food systems (Bakal, 1983). The taste quality of cyclamate as a sole sweetener has a slow onset time and can have a sweet/sour aftertaste at high concentrations (Franta et al., 1986). Sweetness quality is greatly unproved in combination with other sweeteners. Cyclamate is synergistic with acesulfame K (Von Rymon Lipinsky, 1985), aspartame (Searle, 1971), saccharin (Von Rymon Lipinsky, 1987) and sucralose (Tate Lyle Pic, 2002). 

Instrumentation. The HPLC equipment consisted of two Model 740 solvent delivery systems combined with a Model 744 solvent programmer, Model 714 pressure monitor and a Model 755 sample injector (all from Spectra-Physics, Santa Clara, CA). The column used was 25 cm x 3 mm i.d. stainless steel tube packed with either Spherisorb silica 5 y or Spherisorb ODS 5 y. Detection was made with a Schoeffel Instrument Corporation (Westwood, NJ) Model SF 770 spectromonitor. Peak areas were measured by the cut and weight method. Radioactivity was measured by direct measurement in a Searle Model 1185 Automatic Gamma System. 

In 1953, G. D. Searle and Co. patented a related compound, norethynodrel. This steroid is also an active contraceptive when taken orally. This fact is not at all surprising to an experienced organic chemist because it is well known that a CC double bond such as the one in norethynodrel is readily isomerized into conjugation with a carbonyl group. This acid-catalyzed isomerization occurs via an enol intermediate, and the equilibrium favors the more stable, conjugated compound. The acidic conditions in the human gastric system are quite sufficient to accomplish the transformation of norethynodrel to norethindrone. It seems that chemical reactions do not care much about patents ... 

Searles Lake. Searles Lake is a large evaporite deposit about 78 km square and 46 rn deep. It contains a complex mixed salt system that includes trona along with potassium, boron, and other salts (23,24). North American Chemical Company recovers soda ash (1.0 x 10° t/yr) from the lake by carbonating and cooling the brine to crystallize sodium bicarbonate (25). The bicarbonate is filtered and calcined to light soda ash which is densified by conversion to the monohydrate followed by calcining. The procedure results in a dense ash with properties equivalent to Wyoming trona derived ash. 

The samples were sheared using a rotational viscometer with a coaxial cylinder system, based on the Searle-type, where the inner cylinder (connected to a sensor system) rotates while the outer cylinder remains stationary. The outer cylinder surrounding the inner one was jacketed, allowing good temperature control, and the annular gap was of constant width. The sensor system used was the NV type, with a rotor with a recommended viscosity range of 2x10 mPa, a maximum recommended shear stress of 178 Pa, and a maximum recommended shear strain rate of 2700 s this rotor could work with volumes from 10-50 ml. Flow was laminar. 

Over the past 15 years a number of important fundamental theorems in nonequilibrium statistical mechanics of many-particle systems have been proved. These proofs result in a number of important relations in nonequilibrium statistical mechanics. In this review we focus on three new relationships the dissipation function or Evans-Searles fluctuation relation (ES the Jarzynski equality... 

C. Wu M. Berry Y. S. Fung J. McLarty, In Neural Networks for Molecular Sequence Classification, Proceedings of the 1 st International Conference on Intelligent Systems for Molecular Biology, L. Hunter, D. Searls, J. Shavlik, Eds. Bethesda, MD, USA, 1993 pp 429-437. 

Routburg, M. Swenson, R. Schmitt, B. Washington, A. Mueller, S. Hochlowski, J. Maslana, G. Minn, B. Matuszak, K. Searle, P. Pan, J. Implementation of an Automated Purification/Verification System, presented at The International Symposium on Laboratory Automation and Robotics, Boston, MA, October, 1996. 

Searle, P. An Automated Preparative HPLC-MS System for the Rapid Purification of Combinatorial Libraries, presented at The Strategic Institute Conference High-Throughput Compound Characterization, Dallas, TX, March, 1998. 

Searle, P Hochlowski, J. High Throughput Purification of Parallel Synthesis Samples An Integrated Preparative-LC/MS System with Quantitation by Chemiluminescent Nitrogen Detection, presented at The HPLC 2002, Montreal, Canada, June, 2002. 

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