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It has been observed that hindered settling experiments usually lead to voluminous data, which is usually characterized as “poorly reproducible”. Many factors might affect these techniques. The ability to control these parameters may result in a better analysis of the outcome and the correct estimation of the particle size. An attempt was made to investigate calcium oxalate monohydrate stability in the presence and absence of cholesterol, while determining the factors which may undermine the results obtained. The data may provide interesting information which may be used in other similar investigations to reduce the negative compacts caused by the low reproducibility. *Posthumously.

A new viscosity–capillary dipometer was designed and used in this investigation. Comparing this piece of equipment with other viscometers, the capillary dipometer is accurate, easy to operate, and much less expensive. The viscosities for calcium hydrogen phosphate and calcium oxalate suspensions are determined using the capillary dipometer. The data shows that this method is suitable for suspensions. This method could also be applied to other liquid dosage forms (i.e., emulsions) to provide quick and accurate results.

The purpose of this study was to identify the degradation products for folic acid which may form under thermal stress. An attempt was made to identify each of the decomposition products using various analytical techniques, such as infrared spectroscopy, mass spectroscopy, and X-ray diffraction, which suggested that the glutamic acid fragment of folic acid is lost first, as evidenced by acid loss and amide enhancement in the IR spectra. The vitamin was ultimately degrading to carbon fragments and further identification was not necessary.

A new titration method proposed by Huyhn et al., which directly measures the interparticular pore volume between the particles in a concentrated suspension, has been further investigated. It is expected that for an ideal powder with uniform spherical particles, the plot of weight versus the void volume should be a straight line passing through the origin. Glass beads, which are nonporous and expected to be ideal, were used in this study and the results were compared with the results of the experiments by Huyhn et al. Glass beads of different size ranges are used to study the effect of particle size on voidage. It was observed that the voidage increases with a decrease in particle size, However, the non-porous glass beads were also found not to be ideal.

Nicotinic acid belongs to the B group of vitamins and is often referred to as Vitamin B3. It is an essential component of a balanced diet and is prescribed as tablet, and in parenteral dosage forms in cases of vitamin deficiency. This study involves a preliminary preformulation study to assess whether nicotinic acid is a good candidate for tablet and capsule manufacture. The manufacturing process for solid dosage forms involves high energy-intensive processes, which mainly include grinding and compaction. The effect of these high-energy processes on the stability of nicotinic acid was evaluated using thermogravimetry (TG) as the primary analytical tool. The initial stage involved characterizing the thermal behavior of the material. It was found that nicotinic acid shows a solid-solid state phase transition, which is reversible. This transition appears as a small endothermic peak on the differential thermal analysis (DTA) curve, just before the dual sublimation-evaporation stage. This was followed by study...

The heat treatment of parahydroxy benzoic acid esters follows zero order rate processes that are in good correlation with their evaporation process. Rising temperature experiments were performed and the optimum conditions were found when the heating rate was 10°C/min in an atmosphere of dry nitrogen, the flow rate of which was maintained at 100 mL/min. The Antoine constants for methyl paraben were substituted into the Antoine equation to get the corresponding vapor pressures that were then used in the Langmuir equation to obtain the value for the coefficient of evaporation k . The Eact value, obtained from the Arrhenius plot, was 75.1 kJ mol−1; the enthalpy of vaporization (ΔHvap) was calculated to be 77.9 kJ mol−1, in very close agreement with the Eact value. Using the Antoine and Langmuir equations, the value of k was experimentally determined to be 124525 ± 0.8, units being in the S.I. system. Taking the value of k to be independent of the substance, the corresponding vapor pressures were obtained for ...

Dolomite decomposes via a 2-stage mechanism in an atmosphere of CO2. The first stage of the decomposition was analyzed in depth using both isothermal and rising temperature kinetics. It was found that the first stage of decomposition follows the Avrami-Erofeev A2 mechanism for the isothermal experiments. However, for the rising temperature experiment, the reaction follows the Avrami-Erofeev A4 mechanism. The energy of activation (Ea) obtained for the isothermal experiments was determined to be 424.97 kJ/mol, while the value for the rising temperature experiment was 647.20 kJ/mol. Similarly, the ln A-value for the isothermal experiments was found to be 49.22, while the ln A-value for the rising temperature experiment was 74.20. The effect of procedural variables on the thermal behavior of dolomite in a nitrogen atmosphere is investigated. The program design variables include alterations in the flow rate, heating rate, grain size, and sample size. Out of these variables, heating rate, flow rate, and grain s...