Eutectic freeze crystallization in a 2nd generation cooled disk column crystallizer for MgSO4·H2O system

Genceli, F. Elif; Gärtner, Robert S.; Witkamp, G.J.

doi:10.1016/j.jcrysgro.2004.11.172

Cited by 26 publications

(22 citation statements)

References 6 publications

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“…Therefore, considering that the saline bonds are at the basis of NAP/ iv NAP formation, it can be inferred that, in NaCl‐free solutions, polyamine–phosphate salt precipitation occurs more easily in a crystalline form than in an amorphous one [16]. In our case, in these pockets of unfrozen salt‐concentrated brine, greater suprastructures assembled and finally precipitated, forming crystallites as a consequence of the increased concentrations of polyamines and phosphate salts [16,19].…”

Section: Resultsmentioning

confidence: 96%

The in vitro nuclear aggregates of polyamines

et al. 2009

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Self-assembly of polyamines -putrescine (Put), spermidine (Spd), and spermine (Spm) -with phosphate ions was previously described by our group [1]: the intercalation of a phosphate anion between the N-terminal ends of two polyamines determines, by electrostatic interaction, the formation of basic cyclical structures that further aggregate into supramolecular complexes [2] by means of hydrogen bonds, thus producing three different structural classes of molecular aggregates that interact with the genomic DNA [1,3,4]. These compounds were named nuclear aggregates of polyamines (NAPs). Interestingly, other authors have described the phosphate-induced self-assembly of polyamines in a different biological setting [5].Polyamine and phosphate self-aggregation is reputed to be an important phenomenon in directing DNA organization and functions [1]. In our earlier studies, Caco-2 cells were used to assess the biological properties of NAPs, but investigations concerning NAPs extracted from nuclei of many different cell types have also been described [1,3]. However, only preliminary observations concerning the in vitro production of these compounds have been reported [1,3,4]. In addition, the mechanism(s) regulating the supramolecular self-aggregation of polyamines and phosphates and the cooperative action of NAP-DNA aggregates have yet to be defined.For this reason, we determined the conditions necessary for the aggregation of polyamines in a simplified Natural polyamines (putrescine, spermidine, and spermine) self-assemble in a simulated physiological environment (50 mm sodium phosphate buffer, pH 7.2), generating in vitro nuclear aggregates of polyamines (ivNAPs). These supramolecular compounds are similar in structure and molecular mass to naturally occurring cellular nuclear aggregates of polyamines, and they share the ability of NAPs to interact with and protect the genomic DNA against nuclease degradation. Three main ivNAP compounds were separated by gel permeation chromatography. Their elution was carried out with 50 mm sodium phosphate buffer supplemented with 150 mm NaCl. Freezing and thawing of selected chromatographic fractions obtained by GPC runs in which the mobile phase was sodium phosphate buffer not supplemented with NaCl yielded three different microcrystallites, specifically corresponding to the ivNAPs, all of which were able to bind DNA. In this study, we demonstrated that in vitro self-assembly of polyamines and phosphates is a spontaneous, reproducible and inexpensive event, and provided the indications for the production of the ivNAPs as a new tool for manipulating the genomic DNA machinery.Abbreviations DLS, dynamic light scattering; EtBr, ethidium bromide; GPC, gel permeation chromatography; ivNAP, in vitro nuclear aggregate of polyamines; NAP, nuclear aggregate of polyamines; Put, putrescine; Spd, spermidine; Spm, spermine.

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Section: Resultsmentioning

confidence: 96%

The in vitro nuclear aggregates of polyamines

et al. 2009

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“…We have developed the eutectic freeze crystallization (EFC) technique as a production method for various salts, including magnesium sulfate from industrial solutions. 6,7 EFC is a promising technique for processing waste and process streams of mixed aqueous electrolyte/organic solutions, yielding highly pure water and salt. Single crystals synthesized by EFC and cooling crystallization methods were characterized using single crystal X-ray diffraction (XRD).…”

Section: Introductionmentioning

confidence: 99%

Crystallization and Characterization of a New Magnesium Sulfate Hydrate MgSO₄·11H₂O

Genceli

Lutz

Spek

et al. 2007

Crystal Growth & Design

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ABSTRACT:The MgSO 4 crystal hydrate formed below approximately 0°C was proven to be the undecahydrate, MgSO 4 · 11H 2 O (meridianiite) instead of the reported dodecahydrate MgSO 4 · 12H 2 O. The crystals were grown from solution by eutectic freeze and by cooling crystallization. The crystal structure analysis and the molecular arrangement of these crystals were determined using single crystal X-ray diffraction (XRD). Reflections were measured at a temperature of 110(2) K. The structure is triclinic with space group P j 1 (No. 2). The crystal is a colorless block with the following parameters F.W. ) 318.55, 0.54 × 0.24 × 0.18 mm 3 , a ) 6.72548 (7)

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“…Based upon experience with previous models much attention was paid to the unhampered transport of ice from the crystallizer ( Van der Ham et al, 2004;Gencelli et al, 2005). At the top of the crystallizer a conically shaped plastic cylinder is fixed to the rotating shaft.…”

Section: Scaled Up Version Of the Scwc-2mentioning

confidence: 99%