In situ gelling systems based on Pluronic F127/Pluronic F68 formulations for ocular drug delivery

This study evaluated the use of Pluronic F127 and Pluronic F68 as excipients for formulating in situ gelling systems for ocular drug delivery. Thermal transitions have been studied in aqueous solutions of Pluronic F127, Pluronic F68 as well as their binary mixtures using differential scanning calorimetry, rheological measurements, and dynamic light scattering. It was established that the formation of transparent gels at physiologically relevant temperatures is observed only in the case of 20 wt % of Pluronic F127. The addition of Pluronic F68 to Pluronic F127 solutions increases the gelation temperature of binary formulation to above physiological range of temperatures. The biocompatibility evaluation of these formulations using slug mucosa irritation assay and bovine corneal erosion studies revealed that these polymers and their combinations do not cause significant irritation. In vitro drug retention study on glass surfaces and freshly excised bovine cornea showed superior performance of 20 wt % Pluronic F127 compared to other formulations. In addition, in vivo studies in rabbits demonstrated better retention performance of 20 wt % Pluronic F127 compared to Pluronic F68. These results confirmed that 20 wt % Pluronic F127 offers an attractive ocular formulation that can form a transparent gel in situ under physiological conditions with minimal irritation

Poloxamer-based thermoresponsive ketorolac tromethamine in situ gel preparations : design, characterisation, toxicity and transcorneal permeation studies

This study was aimed at preparing, characterising and evaluating in situ gel formulations based on a blend of two hydrophilic polymers i.e. poloxamer 407 (P407) and poloxamer 188 (P188) for a sustained ocular delivery of ketorolac tromethamine (KT). Drug-polymer interaction studies were performed using {DSC} and FT-IR. The gelation temperature (Tsol-gel), gelation time, rheological behaviour, mucoadhesive characteristics of these gels, transcorneal permeation and ocular irritation as well as toxicity was investigated. {DSC} and FT-IR studies revealed that there may be electrostatic interactions between the drug and the polymers used. {P188} modified the Tsol/gel of {P407} bringing it close to eye temperature (35°C) compared with the formulation containing {P407} alone. Moreover, gels that comprised {P407} and {P188} exhibited a pseudoplastic behaviour at different concentrations. Furthermore, mucoadhesion study using mucin discs showed that in situ gel formulations have good mucoadhesive characteristics upon increasing the concentration of P407. When comparing formulations {PP11} and PP12, the work of adhesion decreased significantly (P < 0.001) from 377.9 ± 7.79 mN.mm to 272.3 ± 6.11 mN.mm. In vitro release and ex vivo permeation experiments indicated that the in situ gels were able to prolong and control {KT} release as only 48 of the {KT} released within 12 h. In addition, the HET-CAM and {BCOP} tests confirmed the non-irritancy of {KT} loaded in situ gels, and HET-CAM test demonstrated the ability of ocular protection against strongly irritant substances. {MTT} assay on primary corneal epithelial cells revealed that in situ gel formulations loaded with {KT} showed reasonable and acceptable percent cell viability compared with control samples

Armering i kantförstyvad platta vid olika betongkvaliteter. : En ekonomisk jämförelse.

This thesis is about how different concrete quality in foundation slabs affects the reinforcement content and the drying time. Changing the concrete quality also changes the reinforcement content and drying time. Its common that a change of concrete quality is requested by the contractor to avoid delays and thus making financial savings. But changing concrete quality can lead to problems if the changes in the reinforcement content are not taken into account. Foundation slabs are sensitive structural parts that are exposed to creep and shrink deformations. These deformations can cause cracks in reinforced foundation slabs.The purpose of this thesis is to study the effects that result from the increase of the concrete strength, to show the difference that occurs in the amount of the reinforcement and the time required for the concrete to dry out.To solve this, a calculation template have been developed based on MathCAD in which slabs on soil with different thicknesses and different concrete qualities were analyzed with respect to the reinforcement amounts and drying time. Two different concrete grades were used in the work, one was concrete C30-37, and the other was C45-55.Results show that an increase in the concrete quality of the slab on the ground leads to an increase in the reinforcement content that the slab needs and leads to a reduction in the drying time needed. This leads to an increase in the cost of the slab that has been cast. An example is a slab on the ground with a thickness of 150 mm, the amount of the reinforcement has increased by 19%, concrete cost has increased by 11.64% but drying time has decreased by 70%

Armering i kantförstyvad platta vid olika betongkvaliteter. : En ekonomisk jämförelse.

This thesis is about how different concrete quality in foundation slabs affects the reinforcement content and the drying time. Changing the concrete quality also changes the reinforcement content and drying time. Its common that a change of concrete quality is requested by the contractor to avoid delays and thus making financial savings. But changing concrete quality can lead to problems if the changes in the reinforcement content are not taken into account. Foundation slabs are sensitive structural parts that are exposed to creep and shrink deformations. These deformations can cause cracks in reinforced foundation slabs.The purpose of this thesis is to study the effects that result from the increase of the concrete strength, to show the difference that occurs in the amount of the reinforcement and the time required for the concrete to dry out.To solve this, a calculation template have been developed based on MathCAD in which slabs on soil with different thicknesses and different concrete qualities were analyzed with respect to the reinforcement amounts and drying time. Two different concrete grades were used in the work, one was concrete C30-37, and the other was C45-55.Results show that an increase in the concrete quality of the slab on the ground leads to an increase in the reinforcement content that the slab needs and leads to a reduction in the drying time needed. This leads to an increase in the cost of the slab that has been cast. An example is a slab on the ground with a thickness of 150 mm, the amount of the reinforcement has increased by 19%, concrete cost has increased by 11.64% but drying time has decreased by 70%

Natural Sciences Publishing Cor. Spectral Galerkin Method for Optimal Control Problems Governed by Integral and Integro- Differential Equations

Abstract::In this paper a Legendre integral method is proposed to solve integral and integro- differential problems and optimal control problems governed by integral and integro- differential equations. Galerkin method is used to reformulate the problem as constrained optimization problem. The resulting constrained optimization problem is solved by Hybrid penalty partial quadratic interpolation technique. Numerical results are included to confirm the efficiency and accuracy of the method. Keywords:Spectral methods- Legendre polynomials – Hybrid penalty partial quadratic interpolation technique-Integral equations – Integro differential equations- Optimal control Problems. 1