Bacteria living in oxic environments experience iron deficiency due to limited solubility and slow dissolution kinetics of iron-bearing minerals. To cope with iron deprivation, aerobic bacteria have evolved various strategies, including release of siderophores or other organic acids that scavenge external Fe(III) and deliver it to the cells. This research investigated the role of siderophores p...

The central control of mineral weathering rates on biogeochemical systems has motivated studies of dissolution for more than 50 years. A complete physical picture that explains widely observed variations in dissolution behavior is lacking, and some data show apparent serious inconsistencies that cannot be explained by the largely empirical kinetic "laws." Here, we show that mineral dissolution ...

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. I...

Because drug quality is the focus for pharmaceutical industry and regulatory agencies, the in vitro dissolution test becomes a standard tool for characterization of manufactured products. However, results of the dissolution test must be expressed in mathematical terms; this is realized by fitting various models to the cumulative dissolution curves. The models might be either mechanistic or empi...

Unlike the case of conventional drug formulations, dissolution tests have hitherto not been required for herbal medicinal products commercially available in South Africa. This study investigated dissolution of the South African Sutherlandia frutescens using selected flavonoid glycosides as marker compounds. Dissolution of markers was assessed in three dissolution media at pH 1.2, 4.5 and 6.8, a...

clarithromycin (cla), a broad-spectrum macrolide, is a poorly soluble drug with dissolution rate limited absorption. the aim of this investigation was to prepare cla nanoparticles from a ternary ground mixture in the presence of sodium lauryl sulfate (sls) and polyvinyl pyrrolidone (pvp) as co-grinding water-soluble compounds, in order to improve the drug dissolution rate. different weight rati...

Here we study the carbonate dissolution history of the deep SE Atlantic as evidenced in proxy records in Core T89-40 from the Walvis Ridge, spanning the last 1.1 million years. All dissolution proxy records (fragmentation index, ratio of planktonic and benthic foraminifera, sand fraction and number of planktonic foraminifera per gram sediment) show similar patterns, unique events, and these pro...

This study describes various complications related to sample preparation (filtration) during development of a dissolution method intended to discriminate among different fenofibrate immediate-release formulations. Several dissolution apparatus and sample preparation techniques were tested. The flow-through cell apparatus (USP 4) was found unfit for dissolution testing of fenofibrate MeltDose fo...