Temperature measurement and control of analytical rotors in the ultracentrifuge

Gropper, L.; Boyd, William J.

doi:10.1016/0003-2697(65)90011-4

Cited by 16 publications

(9 citation statements)

References 5 publications

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“…As pointed out by Gropper & Boyd [19], due to the ~ 3 fold higher stiffness of titanium rotors as compared to aluminum rotors, the magnitude of the effect is smaller than when initially discovered by Waugh & Yphantis. An opposing effect of pressure-induced heating of the base of the solution column was predicted by Mijnlieff et al [26], amounting to a gradient of a few tens of °C per centimeter for aqueous columns at high rotor speeds.…”

Section: Discussionmentioning

confidence: 85%

“…Systems have been developed that were based on electrical conductance [6,19], optical scanning [8], thermal infrared radiation [9,10], and radio telemetry [20]. Taking advantage of recent developments in integrated circuits, it has become possible to omit any information transfer from the spinning rotor, and instead store the measurements for later retrieval.…”

Section: Discussionmentioning

confidence: 99%

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Improved measurement of the rotor temperature in analytical ultracentrifugation

Zhao

Balbo

Metger

et al. 2014

Analytical Biochemistry

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Sedimentation velocity is a classical method for measuring the hydrodynamic, translational friction coefficient of biological macromolecules. In a recent study, comparing various analytical ultracentrifuges, we have shown that external calibration of the scan time, radial magnification, and temperature are critically important for accurate measurements (Anal. Biochem., 2013, doi: 10.1016/j.ab.2013.05.011). To achieve accurate temperature calibration, we have introduced the use of an autonomous miniature temperature logging integrated circuit (Maxim Thermochron iButton ™) that can be inserted in an ultracentrifugation cell assembly and spun at low rotor speeds. In the present work, we developed an improved holder for the temperature sensor located in the rotor handle. This has the advantage of not reducing the rotor capacity and allows for a direct temperature measurement of the spinning rotor during high-speed sedimentation velocity experiments up to 60,000 rpm. We demonstrate the sensitivity of this approach by monitoring the adiabatic cooling due to rotor stretching during rotor acceleration, and the reverse process upon rotor deceleration. Based on this, we developed a procedure to approximate isothermal rotor acceleration for better temperature control.

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Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Improved measurement of the rotor temperature in analytical ultracentrifugation

Zhao

Balbo

Metger

et al. 2014

Analytical Biochemistry

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“…Unfortunately, our digital temperature loggers cannot withstand the high gravitational fields so that we could not directly measure this effect. However, with the titanium rotors currently in use this effect should be small, based on their smaller coefficient of expansion and lower specific heats than the historic aluminum rotors [70]. In fact, much like our observations when setting up sedimentation velocity experiments, Gropper and Boyd have demonstrated that titanium rotors transiently cool by 0.2 – 0.3 °C when accelerated to 68,000 rpm – fivefold less than with aluminum rotors, which should make this factor negligible in current practice [70].…”

Section: Discussionmentioning

confidence: 99%

Improving the thermal, radial, and temporal accuracy of the analytical ultracentrifuge through external references

Ghirlando

Balbo

Piszczek

et al. 2013

Analytical Biochemistry

106

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Sedimentation velocity (SV) is a method based on first-principles that provides a precise hydrodynamic characterization of macromolecules in solution. Due to recent improvements in data analysis, the accuracy of experimental SV data emerges as a limiting factor in its interpretation. Our goal was to unravel the sources of experimental error and develop improved calibration procedures. We implemented the use of a Thermochron iButton® temperature logger to directly measure the temperature of a spinning rotor, and detected deviations that can translate into an error of as much as 10% in the sedimentation coefficient. We further designed a precision mask with equidistant markers to correct for instrumental errors in the radial calibration, which were observed to span a range of 8.6%. The need for an independent time calibration emerged with use of the current data acquisition software (Zhao et al., doi 10.1016/j.ab.2013.02.011) and we now show that smaller but significant time errors of up to 2% also occur with earlier versions. After application of these calibration corrections, the sedimentation coefficients obtained from eleven instruments displayed a significantly reduced standard deviation of ∼ 0.7 %. This study demonstrates the need for external calibration procedures and regular control experiments with a sedimentation coefficient standard.

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“…The Model Ε analytical ultracentrifuge, manufactured by Beckman Instruments, Inc., was equipped with a schlieren optical system and a photographic unit to take pictures of the schlieren patterns at various rotation speeds, up to the maximum of 60,000 rpm. Rotor temperature was maintained constant to within ± 0.02°C (12) and rotor speed was controlled electronically to within db 0.2% of any selecting setting. The pictures were measured using a Gaertner M2060 microcomparator.…”

Section: Methodsmentioning

confidence: 99%

Determination of the Critical Exponent δ for a Binary Mixture Using a Centrifugal Field

Salinas¹,

Huang

Winnick

1979

Advances in Chemistry

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A determination of the critical exponent δ has been made for the liquid-liquid system, n-decane-β,β' dichloroethyl ether (chlorex). Utilizing schlieren photographs of the system in an ultracentrifuge at a temperature slightly below the critical solution point, the density gradient was obtained as a func tion of radius. These gradients, used in conjunction with sedimentation theory, provided a means for calculating values for the exponent δ. The values thus obtained are consistent with accepted values for the exponents β and γ in two-fluid systems. They are, however, smaller than those found for pure fluids.nrhe behavior of binary solutions near their critical solution point has been studied extensively in centrifugal fields (1,2,3).This behavior is similar to that of a pure component at its gas-liquid critical point, now known to be governed by exponential relations of the form . r din ι r-7el /H \ where ξ is the critical exponent for property Y as the critical temperature is approached (4). The critical isotherm is described by «-lim^ff-ff (2) v + vc din (V -Vc)

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Temperature measurement and control of analytical rotors in the ultracentrifuge

Cited by 16 publications

References 5 publications

Improved measurement of the rotor temperature in analytical ultracentrifugation

Improved measurement of the rotor temperature in analytical ultracentrifugation

Improving the thermal, radial, and temporal accuracy of the analytical ultracentrifuge through external references

Determination of the Critical Exponent δ for a Binary Mixture Using a Centrifugal Field

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