Dissolution

... Available online 12 March 2002. Abstract. The present contribution shows the results of tests on geological materials for determination of the rare-earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Y and Sc. ...

A number of motored auger holes have been drilled in 2002 and 2006 in four sand-clay deposits preserved in dissolution pockets within the Dinantian limestones of the watershed north of the Vesdre valley. These deposits of unknown age are currently classified as (Tertiary) SBL in the new geological map of Wallonia. We present detailed lithostratigraphic logs of the deposits and describe the results of sedimentological and mineralogical analyses. In particular, K-Ar dating of neoformed Mn oxides found at the base of one augerhole at Rechain yielded ages ranging from Cenomanian to Santonian, allowing us to place the Rechain and Andrimont deposits within the early Late Cretaceous. This is fully consistent with their topographic location very close beneath the trace of the pre-Cretaceous erosion surface and makes them the westernmost remains of the Hergenrath Member of the Late Cretaceous Aachen Formation. To the west, the Magnee deposit is more "typical SBL", probably correspo...

The solubility of drugs remains one of the most challenging aspects of formulation development. There are numerous ways to improve the solubility of drugs amongst which the most promising strategy is solid dispersion. Different ratios of sulfathiazole: PVP-K29/32: sodium lauryl sulfate (SLS) were prepared (1:1:0.1, 1:1:0.5, 1:1:1) and various methods were employed to characterize the prepared solid dispersions, namely modulated differential scanning calorimeter, X-ray powder diffraction, Fourier Transformed Infrared Spectroscopy and dissolution studies. Lack of crystallinity was observed in internal and external systems suggesting a loss of crystallinity, whereas the physical mixtures showed a characteristic peak of sulfathiazole. In vitro dissolution results clearly showed that the incorporation of a relatively small amount of surfactants (5, 20 or 33% w/w) into a solid dispersion can improve its dissolution rates compared to binary solid dispersion (SD) alone and pure sulfathiazole. In all ratios solid dispersion internal shows a higher dissolution rate compared to a physical mixture and solid dispersion external which suggests that the way that the surfactant is incorporated into the solid dispersion plays an important role in changing the solubility of a drug. The solubilization mechanism is mainly responsible for this higher dissolution rate when we incorporate the SLS in SD.

Dissolution process of natural fluorapatite in phosphoric acid at the nanolevel was investigated by scanning electron microscopy, Auger-electron and infrared spectroscopy. Dissolution process at this level was described by non-stoichiometry of the ionic dissolution from the crystal lattice of fluorapatite. The experimental data obtained were extended with the results taken from literature. The following sequence of ionic dissolution was proposed: first fluorine, next calcium and afterwards phosphate. A new mechanism for apatite dissolution at the nanolevel was created as a result. This mechanism was based on the chemical logic and consisted of five chemical reactions, following one after another. A schematic description of this mechanism is also presented.

Bowden, James W.J. and Nicholas A. MacDonald. “Cabinet Manuals and the Crown.” Chapter 12 in Canada and the Crown: Essays on Constitutional Monarchy, edited by D. Michael Jackson and Philippe Lagassé, 179-195. Kingston-Montreal: Queen’s-McGill University Press, 2013.

Leaching was performed to recover zinc from a zinc leach residue which contained 9.87% Zn and 4.93% Fe. During sulfuric acid leaching, Fe was dissolved as well as Zn which can reduce the Zn extraction efficiency. Leaching the residue in the presence of an oxidizing reagent such as hydrogen peroxide or manganese dioxide significantly reduced the iron content of the leach liquor. Effect of pH, temperature, solid/liquid ratio, reaction time and hydrogen peroxide or manganese dioxide concentration on the recovery of zinc and iron in non-oxidative and oxidative leaching conditions were investigated. By using the optimum oxidative leaching conditions, iron recovery reduced from 70% in non-oxidative leaching to 0.4 and 5% in the presence of MnO2 and H2O2, respectively, with acceptable Zn recovery. This reduction in the iron content was due to the different iron compounds formed at different conditions.

"This article introduces the Manual of Official Procedure of the Government of Canada, particularly its guidelines on the formation of governments, the crown’s reserve powers on dissolution and prorogation, and the principle of restraint. It will conclude that scholars looking to create a new "Canadian cabinet manual" need to take this document from 1968 into consideration.

Bioactive glasses have attracted considerable interest in recent years, due to their technological application, especially in biomaterials research. Differential scanning calorimetry (DSC) has been used in the study of the crystallization mechanism in the SiO2–Na2O–CaO–P2O5 glass system, as a function of particle size. The curve of the bulk glass presents a slightly asymmetric crystallization peak that could be deconvoluted into two separate peaks, their separation being followed in the form of powder glasses. Also, a shift of the crystallization peaks to lower temperatures was observed with the decrease of the particle size. FTIR studies – that are confirmed by XRD measurements – proved that the different peaks could be attributed to different crystallization mechanisms. Moreover, it is presented the bioactive behavior of the specific glass as a function of particle size. The study of bioactivity is performed through the process of its immersion in simulated human blood plasma (simulated body fluid, SBF) and the subsequent examination of the development of carbonate-containing hydroxyapatite layer on the surface of the particles. The bioactive response is improved with the increase of the particle size of powders up to 80 μm and remains almost unchanged for further increase, following the specific surface to volume ratio decrease.

Fundamental aspects of electrolyte chemistry were used to design an appropriate dissolution medium with the capacity to maintain sink conditions throughout the test. Dissolution of various bolus dosage forms was studied using USP Apparatus II at various stirring speeds. Complete dissolution of each drug in the designed medium was achieved, and there is evidence that such a dissolution test could be discriminating. This review details the development of potentially discriminating in vitro dissolution tests for veterinary boluses using USP Apparatus II and examines the potential role of such testing during product quality assessments, in the evaluation of postapproval manufacturing changes and for the establishment of the generic equivalence of veterinary products.

Sludge, soil and leachate samples collected from a chromium-contaminated tannery waste dumping site in Kanpur, India, were found to contain considerable amounts of Cr(VI), despite the fresh tannery sludge containing little or no Cr(VI). Literature reports suggested that dry Cr(III) ...

We sought to evaluate whether U.S. Pharmacopeia (USP) apparatus 3 can be used as an alternative to USP apparatus 2 for dissolution testing of immediate-release (IR) dosage forms. Highly soluble drugs, metoprolol and ranitidine, and poorly soluble drugs, acyclovir and furosemide, were chosen as model drugs. The dissolution profiles of both innovator and generic IR products were determined using USP apparatus 2 at 50 rpm and apparatus 3 at 5, 15, and 25 dips per minute (dpm). The dissolution profiles from USP apparatus 3 were compared to those from USP apparatus 2 using the f 2 similarity test. The dissolution profile from USP apparatus 3 generally depends on the agitation rate, with a faster agitation rate producing a faster dissolution rate. It was found that USP apparatus 3 at the extreme low end of the possible agitation range, such as 5 dpm, gave hydrodynamic conditions equivalent to USP apparatus 2 at 50 rpm. With appropriate agitation rate, USP apparatus 3 can produce similar dissolution profiles to USP apparatus 2 or distinguish dissolution characteristics for the IR products of metoprolol, ranitidine, and acyclovir. Incomplete dissolution was observed for the furosemide tablets using USP apparatus 3. Although it is primarily designed for the release testing of extended-release products, USP apparatus 3 may be used for the dissolution testing of IR products of highly soluble drugs, such as metoprolol and ranitidine, and some IR products of poorly soluble drugs, such as acyclovir. USP apparatus 3 offers the advantages of avoiding cone formation and mimicking the changes in physiochemical conditions and mechanical forces experienced by products in the gastrointestinal tract.

Ghosting describes a popular contemporary dating disengagement strategy that abruptly ends communication using technological medium(s). For the target of ghosting, the noninitiator, the action usually creates an incomplete account of the loss. This investigation explores the non-initiators’ retroactive rationalization of ghosting as loss. Utilizing Amazon Mechanical Turk, we conducted two studies. In Study I, noninitiators (N=189) provided reasons for why they were ghosted. Utilizing analytic induction, eight themes emerged from non-initiators accounts. In Study II, (N¼169), the themes were further examined to determine validity. The retrospective rationalizations determine the incoherent account-making processes in post-dissolution from ghosting.

Abstract Ghosting describes a popular contemporary dating disengagement strategy that abruptly ends communication using technological medium(s). For the target of ghosting, the non-initiator, the action usually creates an incomplete account of the loss. This investigation explores the non-initiators’ retroactive rationalization of ghosting as loss. Utilizing Amazon Mechanical Turk, we conducted two studies. In Study I, non-initiators (N = 189) provided reasons for why they were ghosted. Utilizing analytic induction, eight themes emerged from non-initiators accounts. In Study II, (N = 169), the themes were further examined to determine validity. The retrospective rationalizations determine the incoherent account-making processes in post-dissolution from ghosting.

This paper firstly will focus on the historical background of Czechoslovakia and relations between Czechs and Slovaks. In the second part, the main topic will be the break up of these two nations and the fundamental reasons behind the separation -especially economic and political reasons- will be examined with details. And the paper will be concluded with searching for answers to questions like why did this separation take place in a peaceful way rather than violence, and are they better off in two separate countries.