A comprehensive understanding of lowly-hydrolyzed polyvinyl alcohol-based ternary solid dispersions with the use of a combined mixture-process design

Abstract

We recently reported lowly hydrolyzed polyvinyl alcohol (L-PVA, 70–74% hydrolyzed, about 580 polymerized, JR-05) as a promising matrix for hot-melt extrusion (HME) due to its unique micelle formation ability compared to the most commonly used PVA (87–89% hydrolyzed, about 580 polymerized). In the present study, we focused on the effect of composition [indomethacin (IND), L-PVA, sorbitol] and process parameters (temperature and screw speed) on each response, i.e. processing torque, and physicochemical properties such as residual crystallinity, residual ratio, and area under the dissolution curve (AUDC) in supersaturated solution using a HME by applying the design of experiment (DoE) approach. To overcome the poor processability of L-PVA, given its semicrystalline nature, we applied sorbitol as a plasticizer and systematically and simultaneously evaluated its influence on the outputs based on the mixture design combined with process factors. Few studies have focused on comprehensive evaluation of the composition and HME process conditions because obtaining a design space requires numerous experiments. We found that incorporating sorbitol into the L-PVA greatly improved the processing torque. However, sorbitol negatively influenced the degree of residual crystallinity and the AUDC of IND. Lastly, we established a laboratory-scale design space that could achieve high supersaturation and ensure adequate miscibility between each component, using an acceptable processing torque for HME, by applying the minimum amount of sorbitol. These fundamental results suggest that sorbitol maximizes the potency of L-PVA as a carrier in HME.     

Inclusion of temperature effects in a model of magnetoelasticity

In this paper, we report on temperature effects associated with elastic electromagnetic forming by pulsed electromagnetic fields in inhomogeneous, linear, and lossy media. In a previous paper, we discussed the electromagnetic forces associated with these pulsed electromagnetic fields. Here, we calculate the temperature rise from the equation of heat flow in an isolated object to be deformed. The temperature rise is included in the elastodynamic problem to be solved for the presence of electromagnetic forces, and as a consequence the thermoelastic field can be obtained. As an example, we calculate the thermoelastic field in a hollow cylindrical object.     

Exfoliation of a Rigid Linear Inclusion under Static Loading

We present a solution of the problem of exfoliation of a linear rigid inclusion in a homogeneous isotropic matrix. It is assumed that prefracture strips appear under loading near the tips of the inclusion. They are modeled by the jumps of tangential displacements along the matrix–inclusion interface. The problem is reduced to the Cauchy problem for a first-order differential equation. We also perform the numerical analysis of the problem.     

Thermal Mismatch Stress of a Spherical Inclusion in a Cubic Crystal

The thermal stress induced in a spherical inclusion by the difference of the thermal expansion coefficiences of the inclusion and its embedding matrix is considered. Both the inclusion and the matrix are assumed to be of cubic symmetry. Eshelby’s equivalent inclusion method is used to solve the problem. A smple expression for the determination of thermal mismatch stress is thus derived. Some numerical examples are provided.     

Dynamic Stresses in a Body with Nonsmooth Inclusion

We propose a method for the investigation of the dynamic stressed state of a three-dimensional isotropic body containing a nonsmooth inclusion under the action of external dynamic loads. The problem is reduced to the well-known well-known elastic retarded potentials of simple and double layer and volume potentials, the problem is reduced to a system of functional equations solved by the method of successive approximations. As an example, we consider the case of a body with circular conic inclusion subjected to the action of a suddenly applied external load. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 4, pp. 9–18, July–August, 2005.     

Inclusion Complexes of Terfenadine-Cyclodextrins

Terfenadine, a poorly soluble, H₁-antihistamine was solubilised using B-cyclodextrin and its derivatives. A molar ratio of 1:1 of the drug and cyclodextrin was prepared by the kneading method. The inclusion complex was characterised and evaluated by Differential Scanning Calorimetry & X-ray Diffractometry. In vitro dissolution profile of the inclusion complex was studied. Dissolution rates of the drug-cyclodextrin complexes were more as compared to the drug alone. An attempt was also made to prepare a palatable syrup of terfenadine-cyclodextrin complex. Various combination of co-solvents and additives were used to formulate a stable and an acceptable liquid oral.     

Nonstationary Perturbations of a Three-Dimensional Elastic Matrix Containing a Rigid Disc-Shaped Inclusion

The problem of propagation of nonstationary elastic waves in a three-dimensional infinite matrix containing a thin rigid moving inclusion of given mass is solved by the method of boundary integral equations in a time domain. The mechanical contact between the inclusion and the medium is regarded as perfect. We propose a step-by-step algorithm of quantization of the deduced equations taking into account the character of singularity of the required functions on the contour of the inclusion. In the case of normal incidence of nonstationary elastic waves with different profiles upon a circular disk-shaped inclusion, we determine the time dependences of the translational displacements of the inclusion and the mode I stress intensity factors. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 2, pp. 7–15, March–April, 2005.     

Elastoplastic Equilibrium of a Composition Containing an Elastic High-Modulus Inclusion

We pose and solve a two-dimensional model elastoplastic problem for a body containing a high-modulus elastic inclusion. Plasticity zones develop in the vicinity of the tips of the inclusion along its boundary. The problem is reduced to the solution of a singular integro-differential equation, which, in turn, is reduced to an infinite system of equations. The influence of the compliance of the inclusion on the sizes of the plasticity zones is analyzed.     

Antiplane Deformation of a Perfectly Elastoplastic Body with Rigid Rectangular Inclusion

We solve the problem of plastic exfoliation of a rigid rectangular inclusion in a perfectly elastoplastic medium loaded at infinity by shear forces parallel to the horizontal sides of the inclusion. It is assumed that plastic strains are concentrated on the boundary of the inclusion, in layers whose thickness is equal to zero starting from the vertices of the inclusion. We find the length of plastic strips and the degree of exfoliation (i.e., the jump of displacements) at the vertex of the inclusion as functions of the acting load. It is shown that the complete exfoliation of the horizontal sides of the inclusion occurs under a certain load (which increases with the width of the inclusion) but its vertical sides never exfoliate completely. We prove that the solution of the elastic problem represents the limiting case of the solution of the corresponding elastoplastic problem as the yield limit tends to infinity. By using this limit transition, we obtain the elastic solution of the analyzed problem.     

Towards a better understanding of SEA effectiveness in Ireland

The first review of strategic environmental assessment (SEA) effectiveness in Ireland examined how a number of selected case studies performed procedurally. The findings pointed not only to deficiencies in the consideration of alternatives, monitoring and SEA Statements, but also in its capability to lead to more informed and sustainable decisions. Six years on from that review, this paper revisits some of the case studies and appraises non-procedural effectiveness via stakeholder interviews to obtain a more comprehensive account of SEA effectiveness across the life of the reviewed plans. The case studies illustrate a general openness to SEA. Overall, consulted experts agreed that SEA contributes significant knowledge to planning decisions. SEA iterations tend to be more efficient as a result of learning; in some cases, the process led to internal organisational restructuring, facilitating better environmental integration in subsequent plans. There is limited implementation of monitoring across the case studies, so while the review points to positive outcomes of SEA (e.g. new data and knowledge, mitigation by avoidance), it remains to be evidenced whether it ultimately prevents adverse environmental effects.     

Inclusion of phthalate esters by a self-assembled monolayer of thiolated cyclodextrin on a gold electrode

Complexation of phthalic acid esters (PAEs) by a self-assembled monolayer (SAM) of thiolated alpha-cyclodextrin (6-(2-mercaptoethylamino)-6-deoxy-alpha-cyclodextrin, MEA-alpha-CD) on a gold electrode was examined by a cyclic voltammetry using hydroquinone (HQ) as a probe. From the inhibitory effect of the phthalate esters on the inclusion of HQ by the surface-confined cyclodextrin (CD), the association constants (Kasn) of the esters with the immobilized CD were estimated. For comparison, the association of PAEs with free alpha-CD was examined spectrophotometrically using methyl orange as a probe. It was concluded that, in both free and surface-confined CD systems, the Kasn value increased with an increase in the length of aliphatic alcohols conjugated to phthalic acid. Furthermore, the Kasn values for PAEs in the SAM system were much larger than those in a free CD system. This could be intuitively ascribed to the steric factor for the PAEs to come out from the cavity of surface-confined CD, whose rim was in contact with the PAEs. Thermodynamic parameters indicated that the inclusion of PAEs in the SAM system was entropy-driven, which is different from the free CD system where the inclusion was favored by both enthalpy and entropy. This is partly due to the difficulties in cancellation of strain energy by the inclusion into the cavity of the densely fixed CD (97% of the calculated maximum) and partly due to the reduction of hydrogen bonding between the PAEs and the surface-confined CD. Desolvation of the PAEs and CD by the friction at the penetration into the cavity of CD, which was rigidly fixed to the electrode, might also contribute to the positive entropy change. These factors might emphasize the apolar factor of binding to be characterized by a favorable entropy change in the immobilized CD system.     

Archaeometallurgical contributions to a better understanding of the past

Archaeometallurgical investigations, and in particular those employing metallographic techniques, have greatly increased our understanding of the past, primarily by improving our knowledge of the histories of technological developments. However, these studies have potential for contributing to our comprehension of many more aspects of life in the past. The series of case studies presented here illustrate the application of metallography not only in elucidating the history of technology but also in areas such as the dating of objects, the determination of the spread of technologies and the nature and implications of the contact of cultures with the ‘outside’ world.     

Inclusion complexation of vitamin a palmitate with β-cyclodextrin in aqueous solution

Abstract

Study of the inclusion complex between vitamin A palmitate and β-cyclodextrin in aqueous solution was performed to determine the stoichiometry and the association constant of the complex by the phase solubility diagram and fluorescence intensity measurements.     

Potential fabric-reinforced composites: a comprehensive review

Journal of Materials Science - Fabric-based laminated composites are used considerably for multifaceted applications in the automotive, transportation, defense, and structural construction sectors....