Preparation of cross-linked sodium alginate microparticles using glutaraldehyde in methanol

Polymeric sodium alginate microparticles were prepared by precipitating sodium alginate in methanol, followed by cross-linking with glutaraldehyde. The extent of cross-linking was controlled by the time of exposure to glutaraldehyde. The topology of microparticles was characterized by scanning electron microscopy (SEM), which indicated smooth surfaces. The equilibrium swelling experiments were carried out in water to observe the effect of cross-linking and drug loading for better utility of microparticles. It was found that swelling decreased, but drug loading increased, with an increase in cross-linking of the matrix.     

The Importance of Bonded Structural Material

Gluing is of tremendous importance to the wood industry. About 70% of all wood used today involves gluing. As an increasing amount of lower quality wood is used in the future, gluing will become even more important. Additional developments in harvesting previously unused species and forest residues and cleaning dirty material, and a means to reclaim urban waste wood, are needed to assure an adequate wood supply. New or improved economical adhesive systems will be important in accelerating the development of glued products. The future of the wood products industry lies with the use of glue, since the wood raw material will continue to be harvested in ever smaller sizes.     

Influence of Particle Size on the Drying Kinetics of Single Droplets Containing Mixtures of Nanoparticles and Microparticles: Modeling and Pilot-Scale Validation

The particle size of the primary particles is an important parameter influencing the drying behavior of droplets. In this work, the influence of particle size on the drying kinetics and grain properties was analyzed for droplets containing silica nanoparticles, microparticles, and mixtures of the two. The presence of microparticles was found to increase the drying rate and shrinkage of the droplet. The drying curves were modeled using a reaction engineering approach (REA) model. Finally, different suspensions were dried in a pilot-scale spray dryer in order to prove the influence of the particle size obtained in the levitator tests.     

A review of models for single particle compression and their application to silica microspheres

We report on the deformation behavior of single silica microspheres. For the first time a detailed discussion on the quantitative evaluation of force–deformation data in the elastic and plastic regime is given. The microspheres are compressed between two flat plates of a custom built manipulation device supported by a scanning electron microscope. The device allows a high sample throughput enabling full statistical evaluation of force–deformation data of single microspheres. Existing theories describing the deformation behavior of single spheres are discussed and applied to the elastic and plastic deformation regime of silica microspheres. The results obtained from the theories are compared between each other and values reported in literature. The silica microspheres exhibit a significantly different deformation behavior than expected from bulk fused silica, i.e. a distinct plastic deformation behavior. Furthermore, a significant decrease in Young’s modulus and hardness was observed caused by high porosity and reduced crosslinking of silicon atoms, respectively, that is inherent to silica produced by Stöber synthesis. However, the calculated contact pressures exceed the compressive strength of bulk fused silica by at least a factor of two as an effect of a reduced amount of material flaws in microstructures.     

Intensification of biopolymeric microparticles production by ultrasonic assisted atomization

In this work ultrasonic atomization process is applied to produce biopolymer microparticles with potential applications in pharmaceutical and nutraceutical fields. Natural polymer (alginate)/water solution is atomized by ultrasonic assisted process and the droplets spray is reticulated using a solution of copper sulfate, where the Cu²⁺ ions cause the formation of a network structure (hard porous gel). Several operating parameters (solution concentration, flow rate, atomization power) are changed to study their effects on the produced microparticles. Literature correlations able to predict the features of the droplets as functions of process parameters are optimized using a statistical approach. Furthermore, the energy requirement for the drops production is compared with the energy required by traditional techniques to evaluate the intensification effect of the ultrasonic on the atomization process.     

Structured biopolymer-based delivery systems for encapsulation,protection, and release of lipophilic compounds

Food-grade biopolymers, such as proteins and polysaccharides, can be used to create a diverse range of delivery systems suitable for encapsulating, protecting, and delivering lipophilic functional components, such as ω-3 rich oils, conjugated linoleic acid (CLA), oil-soluble vitamins, flavors, colors, and nutraceuticals. This article provides an overview of a number of different approaches that can be used to create structured delivery systems based on biopolymers, including molecular complexation, coacervation, thermodynamic incompatibility, moulding, and extrusion methods. These delivery systems can be produced from food-grade ingredients using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured delivery system are discussed.     

Persistent luminescent particles containing bioactive glasses: Prospect toward tracking in-vivo implant mineralization using biophotonic ceramics

In this paper, we demonstrate that persistent luminescent bodies can be obtained by carefully choosing the sintering temperatures and duration. A borosilicate and a phosphate glasses were sintered into bodies with persistent luminescent (PeL) SrAl₂O₄:Eu²⁺,Dy³⁺ microparticles which have a green emission up to tens of hours after ceasing irradiation. When sintered at high temperature for a short time or at lower temperature for a longer time, a decrease in the PeL from the bodies was observed and was related to the glasses crystallization. A decrease in the PeL from the bodies was also observed after immersion in simulated body fluid and was related to the mineralization of the sintered bodies. Therefore, we clearly show that by tracking the changes in the PeL overtime, these PeL bodies have a real potential application as biophotonic sensors to track dissolution and mineralization of the implant in the body.     

Design and Performance of a Laboratory Spray Dryer to Realize Evaporation-Induced Self-Assembly of Nanoparticles

This work discusses the design, development, and performance of an indigenous laboratory spray dryer with a relatively slow drying rate. The drying time of droplets of colloidal silica (5 wt%) and sodium chloride solution (20 wt%) in this spray dryer was nearly 10 s. The present system was composed of a four-jet compressed air nebulizer that generates a droplet size of 2–5 µm with a nebulization rate of nearly 60 mL/h. The generated powder can be collected using a cyclone or a wire mesh collector. Design and characterization of this system as well as characterization of the micrometric self-assembled powder grains obtained by this spray dryer are discussed.