Storage in Solids

Relatively purified proteins are easily crystallized at 1%, usually 5-10%, of the protein concentration in buffer. So, crystallization is the final stage of purification, and useful for storage of proteins and X-ray crystal structure analysis. In protein chemistry, crystallization does not mean the protein is 100% pure even though it is in crystalline form. As described for salting out, a crystallized protein is in a solid state together with precipitation aids such as salts, organic solvents, water-soluble polymers etc. 

Freeze drying is one of the crystallization methods however, denaturation, deactivation, or a slight change in the three-dimensional structure of a protein is sometimes observed. It is necessary to check the stability before freeze drying. 

Polysaccharides like dextrin, sugars, sugar-alcohols like sorbitol and mannitol, glycerol and ethylene glycol are sometimes used as stabilizers. Some peptides and amino acids are useful excipients for purification. Compounds with a similar structure to that of the substrate are generally effective as stabilizers and are used as fillers for storage. 

Degradation by proteases derived from the same microorganism or from contamination during purification must be avoided. Once a protease contaminates an enzyme solution, the desired enzyme is degraded during purification and might disappear. To prevent degradation by proteases, it is helpful to add protease inhibitors like PMSF (SH protease) and EDTA (metal protease). 

Common enzymes in liquid form should be stored below 4 °C in a refrigerator and kept with a stabilizer. Most enzymes keep their activity for several years under suitable conditions, especially thermostable enzymes. 

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In practice, two basic bonding mechanisms are considered for hydrogen storage in solid-state materials ... 

The essential requirements for hydrogen storage in solids are that it be (a) high H-mass density (b) high H-volume density (c) appropriate pressure, temperature stability (d) reversible absorption/desorption. The results of research in the field of hydrogen solubility in the metal-hydrogen systems and carbon nanostructures are presented in this paper. 

Hada H., Takaoka K., Saikawa M. and Yonezawa Y. (1981), Energy conversion and storage in solid-state photogalvanic cells , Bull. Chem. Soc. Jpn. 54, 1640-1644. 

H2 and positive ion storage in solids are related to a process called intercalation which is exploited in current research for the development of composite electrodes for Li rechargeable batteries. 

Compact storage in solid metal ammine materials... 

NO removal (DeNO ) from diesel or lean-bum gasoline engines can be done by SCR by controlled dosing of ammonia to the exhaust line. As in many other applications, pressure vessels of liquid ammonia are too hazardous for cars and safe storage in solid form enables on-board transportation. Ammonia may also be stored on-board indirectly as an aqueous solution of urea (AdBlue ), but the storage density is three times lower and the chemical conversion of urea must take place before ammonia is available in the exhaust line (Elm0e et al., 2006). 

Gross, B., Charge Storage in Solid Dielectrics. A Bibliographical Review on the Electret and Related EfiFects. Elsevier, New York, 1964. 

The HAR was usually studied from permeation experiments using the electrochemical permeation technique. The other way was by charging experiments. With the development of techniques of hydrogen storage in solid materials, there has been a renewal of interest in the H absorption reaction [2-6] and a need to monitor the conditions for obtaining high concentrations of H in the bulk (and establishing relations not restricted to low levels of H concentrations and to low overpotentials). 

B. Orosa, Charge Storage in Solid Diekarics, A BMiographieat Review on the Eleetra and Related Effects, Elsevier, Amsterdam. 1964. 

So, the question I have is. Do you think the research ideas for hydrogen storage in solids are adequate or should we be putting more resources into this, perhaps approaching hydrogen storage in a significantly different way ... 

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