Unresolved Issues

Although considerable progress has been made in the elucidation of relaxation mechanisms of pharmaceutical glasses, there still exist several unresolved questions, all of which have a bearing on the reliability of accelerated storage assays. They include  

Possibly several of these remaining puzzles are interrelated. Until cause-and-effect relationships can be established, there remain uncertainties about predictions of long-term behaviour of freeze-dried preparations, based solely on physical measurements in real time. For safety considerations alone, therefore, reliable predictions will presumably have to involve laborious and time-consuming real-time chemical assays. 

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Consequently, the antioxidant activity of GA in biological systems is still an unresolved issue, and therefore it requires a more direct knowledge of the antioxidant capacity of GA that can be obtained by in vitro experiments against different types of oxidant species. The total antioxidant activity of a compound or substance is associated with several processes that include the scavenging of free radical species (eg. HO, ROO ), ability to quench reactive excited states (triplet excited states and/ or oxygen singlet molecular 1O2), and/or sequester of metal ions (Fe2+, Cu2+) to avoid the formation of HO by Fenton type reactions. In the following sections, we will discuss the in vitro antioxidant capacity of GA for some of these processes. 

GuidottiTL. 1994. Occupational exposure to hydrogen sulfide in the sour gas industry Some unresolved issues. Int Arch Occup Environ Health 66 153-160. 

Although there is some evidence for the efficacy of long-term treatment with rifaximin for symptomatic relief in patients with uncomplicated diverticular disease, an unresolved issue is whether rifaximin can prevent major inflammatory complications of diverticular disease. In the two prospective open trials discussed above, the occurrence rate of complications in 12 months was lower in patients treated with glucomannan plus rifaximin compared to patients treated with glucomannan only 2.7 versus 0.9% [43] and 3.2 versus 1.3% [44], This observation was not confirmed in the double-blind placebo-controlled trial [45] in which no difference in the 1-year complication rate was observed between the rifaximin and placebo groups. However, in all the studies, the number of patients suffering complications in a 12-month period was too small to detect any statistically significant... 

A novel second-order nonlinear optical medium which should offer considerable fabrication flexibility has been described. The physics of alignment of the highly nonlinearly polarizable moiety was discussed. However, observation of complex dynamical and thermal behavior indicates that an important role is played by the polymer liquid crystalline host. Additional properties of modified members of this family of lc polymers were consequently investigated. The explanations of guest alignment stabilization and thermal dependence of the alignability remain unresolved issues. 

Since there are unresolved issues in the fine detail of reaction mechanism, it is worth recalling an earlier publication on reactive intermediates in iridium hydrogenation [61]. In general, conventional Ir diphosphine complexes turnover slowly or not at all when enantioselective hydrogenation of standard substrates is attempted, and essentially all the practical and useful recent synthetic contri-... 

Unresolved issues such as conformance with electrical, plumbing, fuel-management, and emissions rules and other safety considerations could hinder the efforts of companies that manufacture, sell, and install natural-gas-powered fuel cells for residential, industrial, and commercial applications. 

The chief unresolved issue with ginkgo is the concern of bleeding when combined with anticoagulant medications. The possibility of combining herbal and/or pharmaceutical medications for a greater cognitive effect has not yet been addressed. 

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