Solubility modulation

GA McClelland, SC Sutton, K Engle, GM Zentner. The solubility-modulated osmotic pump In vitro/in vivo release of diltiazem hydrochloride. Pharm Res 8 88-92, 1991. 

This indicates that the prebaking temperature higher than the melting point of the azide decomposes the azide (50%) and it totally decomposes upto 100 mJ/cm2 irradiation. It is possible that subsequent reactions of the nitrene, generated from the azide thermolysis and photolysis, with the styrene resin could be responsible for solubility modulation of this type resist (16). 

Molecular catalysts, often in the form of metal ions complexed to a suitable ligand, can also be attached to dendrimer surfaces [3,9,10,93,94,96,148,149]. Such materials are generally structurally better defined than catalysts bounded to linear polymers, but like random-polymer catalysts they can be easily separated from reaction products. Note, however, that this approach results in a synthetic dead-end as far as further manipulation of the terminal groups is concerned, and thus some of the advantages of using dendrimers, such as solubility modulation, are lost. 

McClelland, G.A. and Zentner, GM., Solubility modulated drug delivery system, US Patent 4946686, 1990. 

As would be anticipated for a carboxylic acid, mandelic acid is known to exhibit a pH strong dependence in its aqueous solubility. This pH dependence was calculated using the solubility module of the ACD PhysChem computational program (version 6.0, Advanced Chemistry Development, Toronto, Canada), and these results are plotted in Figure 1. The results indicate that mandelic acid will be freely soluble in basic solution, which would be interpreted to imply that the sodium salt would be freely soluble as well. 

The simplicity of the approach in terms of experimental set-up, together with the mild reaction conditions and the almost endless choice of amine/acrylate combinations, render the nucleophilic amine-thiol-ene conjugation a powerful and versatile PPM tool for site-specific double modification. The possibility for simultaneous introduction of chemical functionalities and solubility modulators provides paths to multifunctional tailor-made materials. 

A further factor affecting k- is the air-sea temperature difference. When the sea is colder than the air above it, the enhanced solubility of the gas in the water (relative to the air temperature) tends to increase kj. This will occur in summer in sub-polar waters and over upwelling regions. The opposite is also found, and much of the ocean equatorward of 45"" latitude is colder than the overlying air for much of the year. However, air-sea temperature differences are generally less than 2-3 "C so that this effect results in a less than 10% modulation of k- on average. 

Major problems inherent in general applications of RO systems have to do with (1) the presence of particulate and colloidal matter in feed water, (2) precipitation of soluble salts, and (3) physical and chemical makeup of the feed water. All RO membranes can become clogged, some more readily than others. This problem is most severe for spiral-wound and hollow-fiber modules, especially when submicron and colloidal particles enter the unit (larger particulate matter can be easily removed by standard filtration methods). A similar problem is the occurrence of concentration-polarization, previously discussed for ED processes. Concentration-polarization is caused by an accumulation of solute on or near the membrane surface and results in lower flux and reduced salt rejection. 

Click Coached Problems for a self-study module on factors affecting solubility. 

Purinergic System. Figure 2 Schematic of sympathetic cotransmission. ATP and NA released from small granular vesicles (SGV) act on P2X and a-i receptors on smooth muscle, respectively. ATP acting on inotropic P2X receptors evokes excitatory junction potentials (EJPs), increase in intracellular calcium ([Ca2+]j) and fast contraction while occupation of metabotropic ar-adrenoceptors leads to production of inositol triphosphate (IP3), increase in [Ca2+]j and slow contraction. Neuropeptide Y (NPY) stored in large granular vesicles (LGV) acts after release both as a prejunctional inhibitory modulator of release of ATP and NA and as a postjunctional modulatory potentiator of the actions of ATP and NA. Soluble nucleotidases are released from nerve varicosities, and are also present as ectonucleotidases. (Reproduced from Burnstock G (2007) Neurotransmission, neuromodulation cotransmission. In Squire LR (ed) New encyclopaedia of neuroscience. Elsevier, The Netherlands (In Press), with permission from Elsevier). 

We have gained considerable insight into the therapeutic potential of this protein through the use of TGF-(3 antagonists and transgenic mice with defective TGF-(3 signaling and we have evaluated the potential toxicity of TGF-(3 modulation and its overall efficacy in treating cancer. FC Soluble Type II Receptor... 

Modulate physicochemical properties, eg, solubility, viscosity, charge, conformation, denaturation, and binding sites for bacteria and viruses... 

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