Temperature spinning

Allow the precipitate to form overnight at the required temperature (do not store in a refrigerator if % saturation is made for room temperature). Spin with 2000 x g for 10 min, wash the pellet by suspending in ammonium sulfate solution of the indicated degree of saturation, spin again and decant the supernatant. If the precipitate contains the wanted protein, solve it in pure water and dialyze against an appropriate buffer. 

From the viewpoint of polymer applications, the full exploitation of the combined resolution/sensitivity enhancement techniques to obtain "high-resolution" spectra of rare-spin nuclei in solids requires variable temperature spinning capability. In this paper, we describe briefly a spinner assembly suitable for routine operation over a wide range of temperature at the full complement of spinning angles and report - C spectral data at low temperature on several polymers, including fluoropolymers. In addition, variable temperature spin-lattice and rotating frame relaxation times are reported for isotactic poly(propylene). 

Keywords rare-earth compounds, hydride, magnetic ordering temperature, spin-reorien-... 

The checkers used a 30-em jacketed, low temperature spinning band column for this distillation. The IR spectrum of the distilled product is Identical to that of an authentic sample IR (vapor) cm-1 1806 (OO). 

The g factors, line widths, AHpp at room temperature, spin concentrations n25. nj, n , and AEj, are compiled in Table 1. 

Applied to VPO catalysts, spin-echo mapping not only provides information on the oxidation state of different vanadium nuclei, but can also differentiate different phases with the same oxidation state. The development of a NMR technique to probe such materials has been extremely valuable, as their often poorly crystalline nature prevents characterization through X-ray diffraction. Additionally, variable-temperature spin-echo mapping has been shown capable of determining magnetic characteristics of materials, such as their Weiss temperature [34, 37]. 

The decomposition of Co2(CO)8 in faujasites has been studied in some detail. Low-temperature spin-echo ferromagnetic nuclear resonance spectroscopy shows that very small Co particles are formed in supercages of zeolite NaX by microwave plasma activation at low temperatures (86). In situ far-infrared spectroscopy revealed that adsorbed Co2(CO)s interacts with accessible supercage cations in NaY and CoY (239). Carbonyl complexes of different Co nuclearity, such as Co4(CO)i2 and Co(CO)4, are also formed (227,228). In HY the Co atoms are oxidized to Co ions by the zeolite protons. 

Such obvious benefits have stimulated solid-state MAS experiments at cryogenic temperatures in several research laboratories. In the most successful and reproducible case, a sealed sample with a liquid-nitrogen temperature spinning module was cooled in a helium bath, but rotation speeds did not exceed 2 kHz at 40 K and 1 kHz at 5 K [ 15]. This is a serious limitation for practical applications. 

Al very low temperatures spins at neighboring sites are strongly correlated, and hence one may expand the cosine keeping only the quadratic term. For long wavelength fluctuations one may also make a continuum approximation, replacing the 0j by 9 (x) and hence... 

SPA and TFA are toxic if ingested or inhaled and require proper protection (safety glasses as well as an adequately ventilated room). For the saturated SPA solution make a solution of 12.5 mg/ml of SPA in 0.5% TFA and 50% acetonitrile. Vortex 2 min, let stand for 5 min at room temperature, spin 10 min at maximum speed to remove undissolved SPA. Aliquot the supernatant in small volumes and store them at -80 °C. The solution is then stable for 1 month. 

Boil whole cell lysate place screw cap tube containing the thawed lysate sample in a boiling water bath or heat block at 100 °C for 5 min. Remove tubes from heat and allow tubes to cool to room temperature. Spin briefly in a microcentrifuge. 

An example of the first type is the use of low-acid, low-salt, and low-temperature spin-baths, which slow down the cellulose regeneration sufficiently to yield HWM polynosic rayon [190]. Another example is the Lilienfeld process for which the viscose, made from unaged alkali cellulose with excess carbon disulfide and only a short ripening, is spun into a cold spin-bath containing 50-85% of sulfuric acid. This is a case of stabilizing the xanthic acid. Rayon produced in this way has tenacities greater than 5 g/den. 

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