Global Navigation Satellite Systems as Signals of Opportunity for Environmental Applications: Reflectometry and Scintillation

L'abstract è presente nell'allegato / the abstract is in the attachmen

FORMULATION AND EVALUATION OF SOLID DISPERSION TABLETS OF FUROSEMIDE USING POLYVINYLPYRROLIDONE K-30

Objective: The objective of the present study was to improve the aqueous solubility and dissolution characteristics of the loop diuretic furosemide (FUR); a class IV drug in the Biopharmaceutical Classification System (BCS) using solid dispersion technique. Methods: Solvent evaporation and kneading methods were used to produce solid dispersions of FUR in different ratios with the hydrophilic carrier polyvinylpyrrolidone K-30 (PVP-K30). The prepared solid dispersions were evaluated in terms of solubility study, percentage yield, drug content and Fourier transform infrared spectroscopic study (FT-IR). Tablets containing the optimized formula of solid dispersions ( were formulated and their dissolution characteristics were compared with commercial furosemide tablets. Results: The prepared solid dispersions showed an increase in aqueous solubility, especially those formulated in a 1:2 drug: carrier ratio using solvent evaporation method ( it showed a four-fold increase in solubility compared to the parent drug. The absence of drug-carrier chemical interactions that could affect the dissolution was proved by FT-IR. Solid dispersion tablets exhibited a better dissolution profile in simulated gastric fluid pH 1.2 at 37°C ± 0.5 than the commercial FUR tablets in terms of mean dissolution time (8.44 min) and dissolution efficiency in 30 min (42.54%). Both FUR solid dispersions and commercial tablets followed Weibull and Krosmeyer models as the two best models of drug release kinetics proving that they were immediate release. Conclusion: According to the results obtained in this study, solid dispersion techniques could be successfully used for the enhancement of aqueous solubility and dissolution rate of FUR

Accuracy and reliability of traditional measurement techniques for tooth widths and arch perimeter compared to CAD/CAM

>Magister Scientiae - MScBackground: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. Aim: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. Method: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). Results: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). Conclusion: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models

Accuracy and reliability of traditional measurement techniques for tooth widths and arch perimeter compared to CAD/CAM

Magister Scientiae Dentium - MSc(Dent)BACKGROUND: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. AIM: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. METHOD: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). RESULTS: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). CONCLUSION: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models

Accuracy and reliability of traditional measurement techniques for tooth widths and arch perimeter compared to CAD/CAM

Magister Scientiae Dentium - MSc(Dent)BACKGROUND: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. AIM: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. METHOD: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). RESULTS: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). CONCLUSION: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models

Challenges during Operation and Shutdown of Waxy Crude Pipelines

Transportation of waxy crude oil faces great challenges due to shear and temperature dependency. At high temperatures, waxy crude exhibits low viscous Newtonian behavior where the resistance to flow due to friction is low, and hence low pumping pressure is required to transport it. At low temperatures, however, the crude exhibits shear thinning non-Newtonian behavior where its apparent viscosity becomes shear-dependent. In such cases, the operated pipeline needs to maintain a high pressure to guarantee a continuous flow. Moreover, due to heat transfer between the internal pipeline and surroundings, oil temperature declines along the pipeline. It follows that the crude viscosity and, hence, frictional resistance increase. If the flow is interrupted for any reason, i.e., emergency or planned shutdown, then the restartability of the pipeline becomes a challenge because of the nonexistence of heating generated from friction. In this chapter, the challenges normally facing transportation of waxy crude oil will be discussed. The chapter will introduce the rheological properties of waxy crude oil and explain and describe how these properties can affect the pressure losses inside the pipeline during its operation and shutdown. The measures that need to be considered when designing a waxy crude pipeline will be discussed