Diffusion crystallization technique

Lusty, C. J. (1999). A gentle vapor-diffusion technique for cross-Unking of protein crystals for cryocrystallography. /. Appl. Cryst. 32,106-112. 

In the case of TTF-TCNQ, single crystals with typical dimensions of 2 x 0.2 x 0.02 mm can be grown from solutions of multiply distilled CH3CN using a U-tube diffusion technique in a glove box filled with argon. High quality crystals are usually obtained after approximately 3 days. 

Salemme, F.R., A free interface diffusion technique for the crystallization of proteins for X-ray crystallography. Arch. Bio-chem. Biophys. 1972, 151. 

The electrochemical reduction of Ti02 is known to be accompanied by the intercalation of small cations. This finding has been explored in sensitizing anatase films for battery applications [149]. Cation coordination to titanium alkoxide sol-gel precursors is also well known [150]. Lyon and Hupp used quartz crystal microbalance techniques to determine the mass of intercalating cations as the TiOa film is reduced [151]. Hagfeldt and co-workers have studied Li+ and Na intercalation into anatase Ti02 both theoretically and experimentally [152, 153). They found that the diffusion constants for Li and Na+ are temperature dependent with an activation barrier of 0.4 eV for insertion and 0.5 eV for extraction. The Li+ diffusion coefficient at 25 °C into the nanoporous structure was approximately 2 X 10 cm s for insertion and 4 x 10 cm s for extraction. 

Crystallization can also be done from acetonitrile-chloroform or acetonitrile-benzene systems over several days using vapor diffusion techniques at 40 to 45 "C (ref. 9)... 

A requirement for making YAG crystals is a homogeneous, high-purity starting material for use in the Czochralski technique. This means that the application of mechanical mixing and solid-state diffusion techniques are limited. Accordingly, a variety of synthesis techniques have been developed, most of which are sol-gel based. 

Compounds which are particularly difficult to crystallize, or which are exceptionally sensitive, may often be successfully crystallized by a vapor diffusion technique. The technique uses the apparatus shown in Figure 8, and in a typical recrystallization a solution of the compound in a polar solvent is placed in one of the two flasks, while a volatile, less polar solvent is placed in the second flask. The whole system is then placed under reduced pressure. Diffusion of the less polar solvent into the solution may be controlled by the pressure within the apparatus, or by introducing a temperature differential by cooling or warming one of the flasks as convenient. 

The monoclinic form ( 3-lead azide) was first grown by Miles by a diffusion technique [18]. Dilute solutions of a lead salt and sodium azide were allowed to diffuse together in a water medium to cause crystallization. Numerous spontaneous explosions occurred using this method however, the crystals, once... 

Crystallization procedures are carried out using the hanging-drop vapor diffusion technique. The droplet (typically 4 p.1) is prepared by mixing equal volumes (2 p,l) of the protein and reservoir solutions. ... 

Cyclic voltammetric studies of these metallodendrimers showed one reversible oxidation wave, characteristic of independent, non-interacting redox centers. Also, the use of these materials for the modification of electrode surfaces was explored [37-39]. The researchers found that platinum, glass, and carbon-disk electrodes modified by electrodeposited films of these dendrimers are extremely durable and reproducible, with no detected loss of electroactivity even after their use in different electrolyte solutions or after standing for long periods in air. Studies on the thermodynamics and kinetics of adsorption of these redox-active dendrimers onto Pt electrodes by means of electrochemical and electrochemical quartz crystal microbalance techniques were conducted. These showed the adsorption processes to be activation-controlled rather than diffusion-controDed, and to be dependent on... 

A new class of liquid crystal/polymer network composite with very small amounts of polymer network (3 Wt%) is described. These composites are formed by photopolymerization of the monomers in-situ from a solution of monomer dissolved in low-molar-mass liquid crystals. Several techniques have proven useful to characterize these polymer networks. This review describes polymer network structure and its influence on electro-optic behavior of liquid crystals. Structural formation in these composites begins with the phase separation of polymer micronetworks, which aggregate initially by reaction-limited, and then by diffusion-limited modes. The morphology can be manipulated advantageously by controlling the crossover condition between such modes, the order of the monomer solution prior to photopolymerization, and the molecular structure of monomers or comonomers. 

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