Isolating and purifying nucleic acids

Isolating and purifying nucleic acids

The performance of fermentations is better when the pH is slightly higher than the pK a of the organic acid which is to be produced. This condition re...

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The performance of fermentations is better when the pH is slightly higher than the pK a of the organic acid which is to be produced. This condition requires the addition of a base to maintain this elevated pH. Following this procedure, the product of the fermentation is a dilute salt of the organic acid. For example, in the case of the production of lactic acid, the conventional process requires a lot of different ion-exchange steps, which produces a high volume of waste-water and organic solvents. These have to be recovered. Furthermore, possible losses of product and a potential contamination of the product have to be taken into account (Figure 4a). The recovery of lactic acid from a fermentation broth can also be performed by the use of two electrodialysis steps. In the first, the dilute sodium lactate solution is concentrated by a conventional two-compartment electrodialysis. In addition this step also purifies the product because only the ionised components of the broth are transported through the ion-exchange membranes. The other components of the broth are redirected to the fermentation reactor again. In the second step, the concentrated sodium lactate is split, using two-compartment bipolar electrodialysis, to generate lactic acid and NaOH. The acid stream, still containing Na + ions, is then purified by a cation-exchange resin, while caustic soda is recycled to the fermenter for pH control. For economic reasons the conversion rate of sodium lactacte in the bipolar electrodialysis step is kept at 95%, but almost 100% is achievable (Figure 4b).

Patents Fuel cell membrane humidification Applicant: University of California, USA (Los

Alamos National Laboratory) The polymer electrolyte membrane fuel-cell assembly described here has anode and cathode sides separated by the membrane. The anode side comprises a hydrophobic gas-diffusion backing, in contact with one side of the membrane. It also has hydrophilic areas for providing water directly to one side of the membrane. The hydrophilic areas of the gas diffusion backing are formed by sewing a hydrophilic thread through the gas-diffusion backing. Patent number: W O 00/25377 Inventor: M.S. Wilson Publication date: 4 May 2000

Isolating and purifying nucleic acids Applicant: Qiagen GmbH, Germany The invention relates to novel methods and devices for isolating and purifying nucleic acids on surfaces. The invention is directed at methods which use surfaces, for example porous membranes, on which the nucleic acids can be

MembraneTechnologyNo. 125

Concludingremarks Bipolar membrane technology is a newly emerging field of membrane technology, and it involves more than the preparation and characterisation of bipolar membranes. Although a lot of research needs to be performed in order to gain a thorough understanding of the mechanism of electrodialytic water splitting and the new methods of preparing bipolar membranes, it is also clear that further development of this technology also depends on the improvement, in particular, of anion-exchange membranes, to improve the process efficiency in many of the applications. The improvement of these membranes will also benefit traditional electrodialysis processes. A special three-day conference is scheduled to be held on 25-27 October at the University of Twente in Enschede, The Netherlands. The event will cover both the fundamentals and applications of the bipolar membrane technology.

Electro-membrane processesrevealed A conference covering electro-membrane processes and bipolar membrane technology is scheduled to be held on 25-27 October 2000 at the University of Twente in Enschede, The Netherlands. Presentations will cover fundamentals of electro-membrane processes, including the preparation and characterisation of membranes, transport phenomena, module and process design, and applications. The conference is also the closing event of the Thematic Network on Bipolar Membrane Technology, which was established to encourage collaboration between European membrane research organisations, manufacturers and end-users. The network is financially supported by the European Community (contract number BRRT-CT97-

5038). For more information, contact: Wim Boeken,

Acknowledgment The author wishes to thank the editors and authors of the Handbook of Bipolar Membrane Technology, which is currently being prepared as part of the Thematic Network on Electromembrane Processes. This handbook will appear in print at the end of this year.

MembraneApplication CenterTwente, PO Box 545, NL-7500AM Enschede,The Netherlands. Tel: +31 53483 6330, Fax:+31 53483 6430, Email: [email protected] For more information, contact: Tony Franken,

MembraneApplication Center Twente,PO 80x 545, NL-7500AM Enschede,The Netherlands.Tel: +31 53483 6330, Fax:+31 53483 6430, Email:

[email protected] immobilised in a simple manner from the sample containing the nucleic acids, and can be detached again using an equally simple approach. The patent also explains how to carry out the methods in a completely automatic manner. An additional aspect of the invention is directed at binding nucleic acids to an immobile phase, particularly to a membrane, in such a way that they can be easily detached again in a successive reaction step, and optionally can be used in additional applications, such as digestion by restriction, RT, PCR or RT-PCR or in every other suitable analysis or enzyme reaction. Patent number."W O 00/24927 Inventors: S. Gauch, H. Bastian, S. Ullmann, U. Oelmiiller, Uwe, M. Weber, G. Fuhrmann, J. Schorr Publication date: 4 May 2000

Ion-conducting materials Applicant." Foster-Miller Inc, USA This covers novel ion-conducting materials which are suitable for use as solid polymer electrolyte membranes in electrochemical applications including fuel cell systems. More specifically, these ion-conducting polymers are based on sulfonated polyaryletherketone polymers or sulfonated polyphenylsulfone polymers, including co-polymers, or blends thereof. The

patent also describes novel processes for producing these ion-conducting materials. Patent number."WO 00/24796 Inventors: R.M. Formato, P. Osenar, R.E Kovar, N. Langrau Publication date: 4 May 2000

Thermo-membrane device Applicant/Inventor: A. Noack (Germany) The invention relates to a method and device for separating a fluid mixture. The mixture is initially placed in contact with a carbon membrane in a first operating zone at low temperature. The membrane is adjacent to a surf:ace of a porous transport matrix, or applied to the matrix surface. At this stage, at least one fluid component is adsorbed and at least one component of the mixture permeates through the membrane. Heating a surface away from the membrane, and/or a part of the porous transport matrix, to a higher temperature facilitates the thermal desorption of adsorbed components in a second operating zone. The depleted fluid mixture is removed from the first operating zone, and the enriched fluid mixture is removed from the second operating zone. Patent number: W O 00/24500 Publication date: 4 May 2000

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