Vapour diffusion

Meidner, H. (1975). Water supply, evaporation and vapour diffusion in leaves. Journal of Experimental Botany, 26, 666-73. 

From zPr3PSeBr2 two different crystalline phases were isolated. The intended preparation from zPr3PSe with Br2 led by recrystallisation of the crude product from dichloromethane/pentane (vapour diffusion method) to monoclinic crystals (phase 1). Bromination of zPr3PSe with an excess of bromine led to a mixture of products from which a few single crystals of phase 2 were collected. 

At the conclusion of the first falling rate period it may be assumed that the surface is dry and that the plane of separation has moved into the solid. In this case, evaporation takes place from within the solid and the vapour reaches the surface by molecular diffusion through the material. The forces controlling the vapour diffusion determine the final rate of drying, and these are largely independent of the conditions outside the material. 

An increasing number of membrane proteins, in a variety of different detergents, have been crystallized in microbatch under oil. Some of these had failed to crystallize by all methods other than microbatch. Dispensing is quick and simple, even when performed manually, and the drops in oil do not spread out as they do in vapour diffusion over the siliconized coverslips (Chayen, 2006). Using robots thousands of microbatch trials can be dispensed in high-throughput mode in nanolitre volumes. 

Although microbatch is the simplest method of crystallization, it is a relatively new technique and many experimenters still prefer to use vapour diffusion which has been around and has worked well for over 40 years. Hence, there has also been major development in automating and scaling down the quantities of sample using the popular vapour diffusion method (both sitting and hanging drops). An increasing variety of robots are available commercially. 

In the case of vapour diffusion, either the drops themselves or the reservoirs can be diluted. 

Control of the evaporation kinetics of vapour diffusion trials... 

Gelled trials are performed in vapour diffusion, counter diffusion, and in batch. To date, the most simple and speedy procedure for performing trials... 

Chayen, N. E. (1997b). A novel technique to control the rate of vapour diffusion, giving larger protein crystals. /. Appl. Cryst. 30,198-202. 

Chayen, N. E. (1998). Comparative studies of protein crystallization by vapour-diffusion and microbatch techniques. Acta Crystallogr. D 54, 8-15. 

The main technique employed to set up crystal screens is the vapour diffusion method, either in the hanging drop or sitting drop set up. This method is based on slowly concentrating the droplet solution against a reservoir solution of infinite volmne (ml scale) compared to the volume of the droplet ( xl scale, see Fig. 14.2). Other techniques based on diffusion or counter-diffusion in agarose gels (Biertmnpfel et al., 2002) can also be useful. The... 

In the example of the aminoglycoside/ A site complexes, different crystallization solutions were prepared to test various glycerol/MPD ratios 5, 2, 1, 0.75, 0.67, and 0.5 (Table 14.2). All trials are performed at the optimal temperature of 37°C using the vapour diffusion method in the hanging drop set-up 1 xl RNA-antibiotic complex solution was added to 1 xl crystallization solution and equilibrated over a 40% MPD reservoir. 

Light precipitates indicates that the relative supersaturation between sample and reagent is too high. Prepare new tests with a decreased RNA and/or precipitant concentration or dilute the droplet by vapour diffusion by adding water into the reservoir. 

The technique of choice for screening crystallization conditions is the vapour diffusion hanging drop described in Chapter 3. in this method drops containing different concentrations of protein-DNA mixtures, buffer, additive, and precipitant are suspended from a sihconized coverslips placed over sealed reservoirs containing different precipitant... 

Cockburn, J. J., et al. (2003). Crystalhzation of the membrane-containing bacteriophage PRDl in quartz capillaries by vapour diffusion. Acta Crystallogr. D 59, 538-540. 

The two starting components were packed into a glass capillary from opposite ends until they met in the centre. A coloured reaction product was observed visually after 7 to 10 min at the reactant interface. As time progressed, the product interface was observed to advance in the direction of the picric acid reactant. Further study of this reaction supported a vapour diffusion mechanism, bolstered in part by the observation that complexation proceeds even if a small gap of space exists between the two reactants [12]. The nature of the complex was investigated in additional work, whereby it was proposed that a donor/acceptor 71-complex was produced [13]. A crystal structure confirming this deduction was later published [14]. 

Dyrstad, K., Veggeland, J., and Thomassen, C. (1999), A multivariate method to predict the water vapour diffusion rate through polypropylene packaging, Int. J. Pharm., 188,... 

House dust mites were of interest also for our research group. In particular, we have evaluated the activity of the essential oils of four plants, Lavandula angustifolia, L. stoechas, Mentha x piperita (Lamiaceae) and Eucalyptus globulus (Myrtaceae), against a mite of stored food, Tyrophagus longior (Acari Acaridae) [230,231]. We have analyzed by GC-MS all the essential oils and applied two different methods to test the activity of these compounds one by direct contact and the other by vapour diffusion. In the direct contact assays five different quantities of... 

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