Water chemical stability issues

Through alteration of the solid-state form it is possible to increase the dissolution rate, or apparent solubility of a drug. These increases can potentially increase the bioavailability of a poorly water soluble drug. However, the practical use of a higher energy solid form is limited due to physical and chemical stability issues. Significant investigation must be made in order... 

Usually, the chemical stability issue of an AEM involves the degradation of polymer backbone and decomposition of side-chain functional groups. In order to discern how much these two factors contribute to the stability problan of the developed AEM materials, the manbranes are subjected to accelerating aging test by immersing in alkali solution or hot water for a certain time at a given temperature. KOH or NaOH solutions (1.0-6.0 M) are usually chosen as the alkali condition the test is often carried out at room tanperature to for 24-2000 h. A harsher condition was conducted ou a PEEK-based AEM, in which the membrane sample was treated with 10 M NaOH solution at lOO C, but the test only continued for 24... 

It is difficult to imagine cosmetology and the field of modem aesthetic medicine without hyaluronan. A glance at the worldwide periodical literature would reveal that practically every issue includes several articles more or less connected with HA. Physician-cosmetologists were initially interested in hyaluronan because of its unique ability to retain large amounts of water. This property has been maximized for cosmetic products and moisturising masks. From the mid-nineteenth to the twentieth century, chemically stabilized (cross-linked) HA became used as intradermal micro-implants (fillers) for the contour correction of the involuntary changed skin [1]. 

For SLMs, there are several important stability issues including the integrity of the immobilized liquid film, the mechanical stability of the porous support, and chemical stability of the carrier. Danesi et al (76) have correlated SLM lifetime with the following parameters interfacial tension, carrier interaction with water, concentration of the feed and stripping solution, viscosity of the liquid membrane, and the water solubility in the liquid membrane. They concluded that low osmotic pressure differences between the feed and strip solutions, low water solubility in the liquid membrane, and low carrier solubility in water favor stable SLMs. 

The use of water instead of organic solvents is key to attaining the goal of environmentally benign chemical synthesis. In this context, organic reactions in water are now of great interest and much research effort has been devoted to pursuing efficient reactions in water [1-5]. Unique reactivity and selectivity have been often observed in aqueous media, but one of the big issues is the stability of catalysts in water. Many active catalysts are not stable in water but decompose in the presence of even a small amount of water. To overcome this, we searched for efficient catalysts that are stable and can work well in aqueous media. 

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